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Mechanisms of cardiac radiation injury and potential preventive approaches1

Jan Slezak, Branislav Kura, Tá[icirc]na Ravingerová, Narcisa Tribulova, Ludmila Okruhlicova, and Miroslav Barancik

Received 7 January 2015. Accepted 17 February 2015.

Institute for Heart Research, Slovak Academy of Sciences, Dúbravská cesta 9, 842 33 Bratislava, Slovak Republic.

Corresponding author: Jan Slezak (e-mail: [email protected]).

Comment [JD1]: Please confirm that author names and affiliations are correct and in the format

1This Invited Review is part of a Special Issue entitled “Cardioprotection and Arrhythmias, Part 2.”

Abstract:: In addition to cytostatic treatment and surgery, the most common cancer treatment in addition to the cytostatic and surgical is usingis gamma radiation. Despite sophisticated radiological techniques, however, in addition to irradiation of the tumor, irradiation of the surrounding healthy tissue also takes place, which results in various side-effects, depending on the absorbed dose of radiation. Radiation either damages the cell DNA directly affects the DNA, or indirectly via the formation of oxygen radicals, which that in addition to the DNA damage, react with all cell organelles, and interfere with their molecular mechanisms. The main features of radiation injury besidebesides DNA damage is the inflammation, and increased expression of pro-inflammatory genes and

cytokines. Endothelial damage and dysfunction of capillaries and small blood

Comment [JD2]:

vessels plays a particularly important role in radiation injury. This review is focused on summarizing the currently available data concerning the mechanisms of radiation injury, andas well as the effectiveness of the use of various antioxidants, anti-inflammatory cytokines, and cytoprtectivecytoprotective substances that may be utilized in preventing, mitigating, or treatment oftreating the toxic effects of ionizing radiation on the heart.

Key words: radiation, cardiac toxicity, free oxygen radicals, mechanisms of radiation injury, mitigation, prevention, treatment, antioxidants.

Résumé : Le traitement contre le cancer le plus fréquent, outre les agents cytostatiques et la chirurgie, est lirradiation gamma. Cependant, malgré lutilisation de techniques radiologiques sophistiquées, en plus de lirradiation de la tumeur, une irradiation des tissus sains adjacents survient aussi, ce qui résulte en plusieurs effets secondaires, dépendamment de la dose de radiation absorbée. La radiation affecte lADN soit directement, ou indirectement par lintermédiaire de la formation de radicaux doxygène qui, en plus dendommager lADN, réagissent avec tous les organites cellulaires et interfèrent avec leurs mécanismes moléculaires. Les caractéristiques principales du dommage causé par lirradiation, hormis

ceux sur lADN, sont linflammation et lexpression accrue de gènes pro-inflammatoires et de cytokines. Le dommage endothélial et la dysfonction des capillaires et des petits vaisseaux sanguins jouent un rôle particulièrement important dans le dommage causé par lirradiation. Cet article de revue résume surtout les données actuellement disponibles qui concernent les mécanismes de dommages causés par lirradiation, et lefficacité de lutilisation de différents antioxydants, cytokines antiinflammatoires et substances cytoprotectrices, qui peuvent servir à la prévention, latténuation ou le traitement des effets toxiques des radiations ionisantes sur le cœur.[lsqb]Traduit par la Rédaction[rsqb]

Mots-clés : radiation, toxicité cardiaque, radicaux libres doxygène, mécanismes de dommage causés par lirradiation, atténuation, prévention, traitement, antioxydants.

Introduction

Before 1950, the generators ofproducing therapeutic radiation were not so powerful, and had only limited depth-dose capacity (Lacher 1990). The advent of megavoltage techniques resulted in higher tumor

doses and alsoreaching tumors, as well as the adjacent tissues, with a subsequent increase in side-effects (Stewart and Fajardo 1984).

The clinical importance of radiation-induced heart disease has been recognized for many years. The first indication of the relative radiosensitivity of the heart came from long-term follow-up studies of patients treated for Hodgkins disease (Andratschke et al. 2011).

Today, chronic injury of the myocardium is increasingly recognized as an undesired side-effect offrom irradiation after thoracic/mediastinal radiation therapy offor malignancies.

Currently, the use of technology to reduce the toxicity of ionizing radiation to normal healthy tissue toxicity includes radiation techniques such as conformal radiotherapy, intensity-modulated radiotherapy, image-guided radiotherapy, and proton radiotherapy. Each of these techniques helps to reduce the volume of normal tissue exposed to high doses of radiation, thus reducing the risk of injury to normal tissue. Despite modern radiotherapy techniques, in some cases it inevitably involves the exposure of adjacent tissues, causing undesired side effect-effects. Radiation-induced heart disease (RIHD) has attracted much interest in the recent

10 years and pointed out to, focused on the mechanisms involved in the development of radiation-induced cardiovascular injury. The mechanism of radiation injury is a complex and multifactorial issue and involves endothelial damage of the microvasculature and coronary arteries, DNA damage, and release of multiple inflammatory and profibrotic cytokines (Sencus;151>SenkusKonefka and Jassem 2007; Boerma and Hauer-Jensen 2010; Lee et al. 2013).

The mechanisms whereby these cardiac effects occur are not fully understood, and different factors are probably involved after high therapeutic doses of radiation. These various mechanisms probably result in different cardiac pathologies, e.g., coronary artery atherosclerosis leading to myocardial infarction, versusor microvascular damage and fibrosis leading to congestive heart failure (Stewart et al. 2013). The

Inflammatory cell infiltrate, which is another consequence of radiation

damage, disturbs the filtration properties of the endothelium, and the basement

Comment [JD3]: Author: change made because it was unclear as to which context the inflammatory cell infiltrate was connected to the previous paragraph. Is the change OK?

membrane of the capillary wall thickens as a result of collagen deposition and fibrosis (Gaya and Ashford 2005).

Better understanding of the molecular pathways of radiation injury might help to unravel basic mechanisms of RIHD, with the ultimate goal to identifyof identifing potential targets for intervention (Andratschke et al. 2011). Studies might also provide knowledge ofinformation on how to

Comment [JD4]: Author: change OK?

modify the progression of radiation damage in the heart by using drugs or biological molecules (Citrin et al. 2010; Mège et al. 2011).

RIHD can be modulated by therapies directed at mitigating the cascade of events resulting from normal tissue injury. This review is focused on the mechanisms of radiation-induced cardiovascular toxicity and the prevention of injury ofto healthy tissues in the areas at risk.

Mechamismshd1>>Mechanisms and factors of radiation injury

Mechanisms by which radiation causes tissue injury ofin both malignant and normal tissues involves the induction of apoptosis due to free-radical–mediated DNA damage, and the sequence of overlapping events that include activation of the coagulation system, inflammation, and tissue remodeling. This complex process is orchestrated by a large number of interacting molecular signals includingthat include cytokines, chemokines, and growth factors.

There are several crucial factors determining the intensity of radiation tissue damage. These can be shortly summarized as dose- size (the higher dose the

greater injury), speed of dose delivered- (the faster delivery results in more injurious effecteffects), size of exposed body- (the bigger part of body the more severe the injury), sensitivity of tissue to radiation, age, health status, and genetic abnormalities (Fig. 1).

The dependence of damage from a dose of radiation dose targeted on the thoracic region is very prominent. Results showedhave shown that irradiation with 5 Gy resulted only in a modest increase in right ventricular weightmass and a reduction in lung angiotensin converting enzyme (ACE) activity. Rats

Comment [JD5]: AUTHOR: We follow the Canadian Metric Practice Guide; a weight is a force usually expressed in Newtons (or its multiples), while a mass is a quantity of matter usually expressed in grams.

receivingexposed to 10 Gy exhibited pulmonary vascular dropout, right

ventricular hypertrophy, increased pulmonary vascular resistance, increased dry lung weightmass, and decreases indecreased total lung angiotensin converting enzymeACE activity, as well as pulmonary artery distensibility after one month

(Ghosh et al. 2009; Slezak et al. 2011;>, Slezak et al. 2012;>, Slezak et al. ;???>2013). Activation of protein kinase C wasis involved in radiationinduced adaptive responses, and the intracellular signal transduction pathway induced by protein phosphorylation with protein kinase C wasis a key step in the signal transduction pathways induced by low-dose irradiation (Matsumoto et al. 2004).

Comment [ON6]: Please add a (ref. 157), b (ref. 158), or c (ref. 159) to publication year to match reference list.

Correct is the ref. no. 157 (a).

Radiation at doses of 14 and 25 Gy increasedincreases cGMP, increased levels, and increases inducible nitric oxide synthase (iNOS) activity and nitrite

Comment [JD7]: Author: change correct?

content. Both doses of radiation significantly decreased the L-arginine transport and increased iNOS gene expression significantly.. It was proposed that radiation induces the nitric oxide (NO) generation by up-regulating the iNOS activity

(Zhong et al. 2004).

Radiation damage to vasculature can be demonstrated by the fact that breastcancer patients exposed to post-operative radiotherapy showed in later stages a significant increase in mortality from ischaemic heart disease in the later stages (Rutqvist et al. 1992). About 50% of the patients had new scintigraphic defects whichthat could be related to radiation-induced damage to the micro-circulation (Gyenes et al. 1996) resulting in reduced myocardial capillary density (Baker et al. 2009), focal loss of endothelial alkaline phosphatase (Schultz-Hector and Balz 1994), and increased expression of von Willebrand factor (vWf) (Boerma et al. 2004). It was estimated that 1 Gy added to the mean dose would increase the cardiotoxic risk by 4% (Mège et al. 2011).

Comment [JD8]: AUTHOR: Please note that our style is to use italic type for genotypes, genes, alleles, and loci, and roman type for phenotypes, proteins, and enzymes. Please would you check that your paper has been correctly set.

Shortly after a 20 Gy dose, cardiac function wasis slightly reduced then maintained in a steady state for several weeks, probably due to a compensatory upregulation of cardiac -adrenergic receptors. In denervated working heart preparations (in vitro), however, these compensatory mechanisms are not effective, and stroke volume as well as cardiac contractility show a rapid and steady deterioration (Schultz-Hector 1992).

The state after six After 6 weeks of 25 Gy irradiation of with 25 Gy, the mediastinal area is characterized by general alteration of the animals, e.g.,the following changes: body- and heart weight retardation,-mass reduction and the presence of exudate in the chest and abdominal cavity. In isolated Langendorffperfused hearts, the effect of irradiation on the heart function was manifested byas mild bradycardia and surprisingly enhanced coronary flow, but bythere were no changes in heart contractile parameters. Under conditions of ischaemia/– reperfusion (I/R), the incidence of reperfusion arrhythmias was higher than in the control hearts. Interestingly, the size of infarction in the irradiated hearts was smaller than in the intact hearts (Ravingerova et al. 2011; Carnicka et al. 2013a,b; Slezak et al. 2011; Slezak et al. 2012; Slezak et al.

Comment [JD9]: Author: change correct? “Retardation” is not the correct word in this context

2014; Carnicka et al. 2013a,2013b).

At aroundAfter ca. 70 days afterof irradiation at 20 Gy, a marked reduction in capillary density as well as ultrastructural endothelial cell degeneration can be observed. Simultaneously to structural capillary damage, a focal loss of the endothelial marker enzyme alkaline phosphatase washas been observed in rats in the areas with subsequent myocardial degeneration (Schultz-Hector 1992).

Radiation whichthat is absorbed in a cell, has the potential to influence a variety of critical targets in the cell, the most important of which is the DNA. The evidence indicates that damage to the DNA is what causes cell death, mutation, and carcinogenesis (Schultz-Hector 1992). Radiation further causes alteration inchanges to the cell membranemembranes and nuclear membrane permeability, functional aberrations in chromosomes and cellular organelles, and can change its functionalso cause functional changes (Fig. 2).

After exposure to ionizing radiation, atoms or molecules became ionized or excited and these can produce free radicals from other molecules, they can break

many of chemical bonds in other chemical compounds, or they can produce a new

chemical bonds from existing chemical compounds. Ionized/excited formforms of atoms/molecules can damage some important molecules, for example DNA, RNA or, and proteins (Fig. 3).

Direct and indirect effects of radiation

Direct action

DNA is the principle target for the biological effects of radiation. Radiation may damage the DNA directly, causing ionization of the atoms in the DNA molecule (Fig. 4). The misrepaired or unrepaired DNA damages, in particulardamage, DNA double-strand breaks in particular, induce

chromosomal aberrations and gene mutations. Radiation-induced DNA doublestrand breaks play an important role in the induction of apoptosis and cell-cycle arrest (Han and Yu 2009).

Radiation produces a variety of DNA and other cellular lesions that elicit a stress response. Altered gene profiles are one characteristic feature of this response. Increased expression of pro-inflammatory and other genes has been

demonstrated within hours following irradiation (Hong et al. 1995; Kyrkanides et al. 2002). These include the genes offor transcription factors such as nuclear factor–-kappa B (NF-B), cytokines such as tumor necrosis factor–- (TNF),-), interleukin–-1 (IL-1), and basic fibroblast growth factor (bFGF)), which are involved in inflammatory processes.

The biological effects of ionizing radiation have long been considered a consequence of DNA damage in the irradiated cells. Unrepaired or misrepaired DNA damage in the irradiated cells areis responsible for the genetic effects. At the same time, no effects are expected in the cells in the population that have not been exposed to radiation. This conventional dogma was, however, challenged by the occurrence of the radiation-induced bystander effect (RIBE). RIBE was reported back in 1954, when cells exposed to doses of low linear energy transfer (LET) radiation were found to have an indirect effect in producing a plasma-borne factor, which that led to chromosome breakage and cytogenetic disorders

(Mothersill and Seymour 2001).

From the early 1990s, development in single-cell irradiation has led to an immense interest in the bystander effects. Generally, RIBE can be defined as the


phenomenon whereby the irradiated cells can release some sort of signaling molecule, which is transferred via the medium or gap-junctions, so that the same cytotoxicity or genotoxicity can be observed in the non-irradiated cells (Han and Yu 2009).

Indirect action via production of oxygen free radicals

Radiation interacts with non-critical target atoms or molecules, usually water. This results in the production of free radicals. Free radicals can then attack critical targets such as the DNA, because they are able tocan diffuse for some distance in the cell. Thus, the initial ionization event does not have to occur so close to the DNA to cause damage. Radiation treatment causes direct damage to blood vessels by the generation of reactive oxygen species (ROS) that disrupt DNA strands and leading to an inflammatory cascade (Hatoum et al. 2006).

Mechanisms of free radicals-radical action

Free radiacalsradicals are molecules containing one or more unpaired electrons in atomic or molecular orbitals (Gutteridge and Halliwell

2000). Unpaired electrons, result in high chemical reactivity. Most of the energy deposited in cells is absorbed initially absorbed in water, which is the main component of cells, leading to a rapid production of oxidizing and reducing reactive hydroxyl radicals.

Reactive free radicals play a crucial part in different physiological processes ranging fromincluding cell signaling, inflammation, and the immune defense

(Elahi and Matata 2006).

Hydroxyl radicals ( OH (OH)) may diffuse over distancessome distance to interact with DNA toand cause damage. Fortunately, some defensive systems or responses in cells can protect the cells from the damage (Han and Yu 2009).

The formation of ROS is originatingoriginates from a variety of sources such as nitric oxide (NO) synthase (, NOS),, xanthine oxidases (XO), the cyclooxygenases, nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase isoforms, and metal-catalyzed reactions (Elahi et al. 2009). Abnormal production of free radicals leads to changes in molecular pathways, resulting in pathogenesis of several important pathological states including heart disease,

neurological disease, and cancer, and is involved in the process of physiological aging.

Reduction and oxidation can render the reduced molecule unstable and make it free to react with other molecules to cause damage to cellular and sub-cellular components. This includes free radicals such as superoxide anion ( O2 (O2-),), hydroxyl radical ( HO (HO),), lipid radicals ( ROO (ROO-)), and nitric oxide (NO). Although other reactive oxygen species,ROS such as hydrogen peroxide (H2O2), peroxynitrite (ONOO-)–), and hypochlorous acid (HOCl),) are not free radicals, they have oxidizing effects that contribute to oxidative stress. ROS have been implicated in cell damage, necrosis, and cell apoptosis dueowing to their direct oxidizing effects on macromolecules such as lipids, proteins, and DNA (Valko et al. 2005;>, Valko et al. 2006). Reaction between radicals and polyunsaturated fatty acids within the cell membrane can result in fatty acid peroxyl radicals, which accumulate in the cell membrane and alter protein function and signal transduction. ROS can also induce the opening of the mitochondrial membrane permeability transition pore and cause a release of cytochromec and other factors that can lead to apoptosismediated cell death (Tatton et al. 2003; Tsutsui et al. 2009). O2 .- radicalsRadicals such as O2 can further interact with the

Comment [JD11]: Author: change correct? Or did you mean hydroperoxide anion of aqueous phase initiator ROO-- ?

signaling molecule nitric oxide (NO), resulting in the formation of reactive nitrogen species (RNS), which further reduce NO bioavailability and cause NO toxicity known as “nitrosative stress” (Elahi et al. 2007).

Under the physiological situationconditions, defences such as specialized enzymes and antioxidants can cope with the situation and maintain the reduction-– oxidation (redox) balance. However, during excessive production of ROS, enzymes and antioxidants can get exhausted resulting in oxidative/–nitrosative disbalanceimbalance, a process that is an important mediator of cell damage

(Pacher and Szabo 2008; Vassalle et al. 2008; Elahi et al. 2009).

Excessive production of RNS results in nitrosylation reactions that change the structure of proteins (Ridnour et al. 2004) leading to the loss or change of protein function. The oxidation and nitration of cellular proteins, lipids, and nucleic acids, and the formation of aggregates of oxidized molecules underlie the loss of cellular function, cellular aging, and the inability of cells to withstand physiological stresses. ROS modulate signal transduction processes and energy metabolism in response to conditions of oxidative/–nitrosative stress.

This suggests that radiation causes an inflammatory response and, in a later phase, oxidative damage in large vessels that, in combination with high levels of cholesterol, increases the oxidation of low-density lipoproteins and allows them to be ingested by macrophages, thus triggering the start of the atherosclerotic process. Once the atherosclerotic process is initiated, the lipid cells secrete further inflammatory cytokines and growth factors, which stimulate the proliferation and migration of the smooth muscle cells (Stewart et al. 2010).

Ionizing radiation is associated with induction of inflammatory markers including cytokine expression. An increase in cyclooxygenase–-2 (COX-2) expression and COX–-2-mediated prostanoid production was observedhas been detected in the irradiated mouse brain. COX–-2 is one of two2 isoforms of the obligate enzyme in prostanoid synthesis and a principal target of non-steroidal antiinflammatory drugs (NSAIDs). Inhibition of COX–-2 attenuates prostanoid induction and cerebral edema in mice after XRTX-ray treatment (Moore et al. 2004).

Sources of ROS, physiological and pathophysiological conditions, and cellular oxidant targets determine the characteristic feature of a disease process and resultant outcomes (Elahi et al. 2009).


In this context, cytokines and growth factors probably play a central role in this process and, in particular, transforming growth factor (TGF-)-1, TGF-2, and TGF-3 are highly pleiotropic cytokines secreted by all cell types; TGF- molecules are proposed to act as cellular switches that regulate processes such as immune function, proliferation, and epithelial-–mesenchymal transition. TGF-1 is the isoform most frequently implicated in the fibro-proliferative process, and it appears to be a key-molecule and a master switch for the general fibrotic program (Lawrence 1996; Hendry et al. 2008).

ROS signaling can progress via NF-B activation. NF-B belongs to a family of inducible transcription factors (Baeuerle and Henkel 1994), and is one of the most commonly studied transcriptional factors influenced by cellular redox state (Imbert et al. 1996). ROS is anare important intermediate second messengermessengers of NF-B activation by

upstream stimuli such as TNF-α and IL–-1. It isThey are involved in the regulation of inflammation, stress responses, expression of cytokines and cell adhesion molecules, regulation of immune response, and programmed cell death. NF-B targets multiple genes involved in inflammation including ICAM, VCAM, and IL–1, the production of cytokines, upregulation of prothrombotic markers, and

Comment [JD13]: Author: change correct? Changed throughout

pathogenesis of atherosclerosis. (Wilson et al. 2000; Kim et al. 2001). PostirradiationPost-irradiation activation of NF-B wasis prevented by NO, and thus a reduction in the bioavailability of NO may result in epigenetic changes that promote vascular inflammation and atherosclerosis (Peng et al. 1995).

NF-B is found to be upregulated in atherosclerotic vessels, and its nuclear translocation has been detected in the intima and media of atherosclerotic lesions and in smooth muscle cells, endothelial cells, macrophages, and the Tcells of atherosclerotic plaques. It has also been reported that NF-B plays a role in mediating of T-cell signaling in atheromatous plaques (Brand et al. 1997; Landry et al. 1997; Mach et al. 1998; Kawano et al. 2006; Barlic et al. 2007).

Peroxisome proliferatorsproliferator activated receptors (PPAR) and ROS signaling

PPARs are expressed in vascular cells where they exert antiatherogenic, anti-inflammatory, and vasculoprotective actions. Activators of PPARalphaPPARα

Comment [JD14]: Author: change correct? You are not talking about the gene?

(fibrates) and PPARgammaPPARγ (thiazolidinediones or glitazones) antagonize the effects of angiotensinII effects in vivo and in vitro, and have cardiovascular antioxidant and anti-inflammatory actions. in the cardiovascular setting (;173>Touyz and SchriffrinSchiffrin 2006).

PPAR transcription factor has been implicated in the inflammatory processes involved in the pathogenesis of atherosclerosis. Oxidized low-density lipoprotein (LDL) has been shown to increase expression of PPAR in the foam cells of


atherosclerotic lesions. However, PPAR doesPPARs do not have a sole role in the mediation of only mediate inflammation.: the activation of PPARalphaPPARα and PPARgammaPPARγ isoforms results in anti-inflammatory responses in the walls of

blood vessel wallvessels. Specific agonists of PPARgammaPPARγ have been shown to suppress pro-inflammatory gene expression in monocytes. Activators of PPAR alphaPPARα have also been shown to block inflammatory responses in aortic

smooth muscle cells, and PPARgamma activation of PPARγ has been shown to mitigate the inflammation associated with chronic and acute neurological insults (Rieber and Baeuerle 1991; Slezak et al. 2013).


Correct is the ref. no. 157 (a). Pivotal role of endothelium in radiation-induced injury

The endothelium plays an essential role in maintaining of cardiovascular function, and early changes in endothelial function are indicators of cardiovascular morbidity and mortality (Okruhlicova et al. 2012; Triggle et al. 2012). An important functional role of the endothelium is represented by the control of blood flow angiogenesis, inflammation, platelet aggregation, and vascular remodeling, as well as by control of metabolism.

Radiation damage to the myocardium is caused primarily by inflammatory changes in the microvasculature, leading to microthrombi and the occlusion of vessels, laterfollowed by reduced vascular density, perfusion defects, and focal ischemia. This is followed by progressive myocardial cell death and fibrosis. Irradiation of endothelial cells lining large vessels also increases the expression of inflammatory molecules, leading to the adhesion and transmigration of circulating monocytes that transform into activated macrophages (Stewart et al. 2010).

The endothelium is not only an important source of nitric oxide (NO),, but also of numerous other signaling molecules, including the putative endothelium-derived

hyperpolarizing factor (EDHF), prostacyclin (PGI2), and hydrogen peroxide (H2O2), which have both vasodilating and vasoconstricting properties. ItThe endothelium modulates flow-mediated vasodilatation as well asand influences mitogenic activity, platelet aggregation, and neutrophil adhesion. These early effects are followed by endothelial cellscell proliferation and obstruction of the myocardial capillary lumen (Gyenes 1998).

Radiation injury of endothelial cells results in a reduction in the bioavailability of NO, and increases the recruitment of leukocytes to the endothelium, indicating that endothelial cell-derived NO plays an important antiinflammatory role that, in part, is mediated by the inhibition of adhesion molecule expression (Kubes et al. 1991; Niu et al. 1994). Reduced bioavailability of NO promotes endothelial and vascular dysfunction, not only via profound effects on vascular tone and blood flow, but also via promotion of cell proliferation and enhanced expression of adhesion molecules. In addition, a reduced bioavailability of NO and (or) PGI2 will also enhance the potential for platelet aggregation (Triggle et al. 2012).


It has been postulated that damage to the microvascular components begins with the injury of endothelial cells within heart blood capillaries. Endothelial damage leads to an acute inflammatory reaction and to activation of the coagulation mechanisms with consequent fibrin deposition. The activation of macrophages and monocytes during the inflammatory process results in the continuous secretion of cytokines and growth factors, including Tumor Necrosis Factor (TNF), Interleukin (-α, IL)–-1, IL–-6, and IL–-18, monocytesand monocyte

chemotactic factor. Besides induction of adhesion molecules, up-regulation of some cytokines (namely IL-6 and IL-8) has been observed after endothelial cell irradiation in a time- and dose-related fashion manner (Burger et al. 1998; Van der Meeren et al. 1999).

Although microvascular injury is a major underlying cause of radiationinduced myocardial damage, radiation couldmay also damage the major arteries, leading to an accelerated development of age-related atherosclerosis. The initial event in radiation-induced atherosclerosis is endothelial cell damage and transmigration of monocytes into the intima, with subsequent ingestion of lowdensity lipoproteins and formation of fatty streaks (Konings et al. 1978; Vos et al. 1983).

Schultz-Hector and Trott (2007) concluded that in rodents, radiation-induced heart disease was caused by radiation damage to the micro-vasculature leading to focal ischemia. Atherosclerosis of the coronary arteries has been never observed in rodent hearts except in constitutionally hypertensive rats (Lauk and Trott 1988).

Radiation may cause micro-vascular disease whichthat is characterised by a decrease in capillary density causing chronic ischemic heart disease and focal myocardial degeneration, and macro-vascular disease through the faster development of age-related atherosclerosis in the coronary arteries (Schultz-Hector and Trott 2007).

Progressive decrease of capillary density occurrsoccurs later (after two2 months)), both as a random rarefication bythrough the disappearance of individual capillaries and as a focal loss of groups of capillaries, which gradually leadleads to ischemic necrosis. Before the focal loss of capillaries, the focal disappearance of alkaline phosphatase activity was observed (Lauk 1987; Schultz-Hector and Balz 1994; Seddon et al. 2002). This focal functional injury of endothelial cells is detectable within a few weeks after irradiation. Focal loss of capillaries is preceded by

increased endothelial proliferation, but in the enzyme-negative areas only (Schultz-Hector et al. 1993).

Radiation-induced vascular injury and endothelial dysfunction are mediated also in part by Transforming Growth Factor-  (TGF- )- (Kruse et al. 2009), which is a pluripotent growth factor.

Also, there is evidence of the prothrombotic effects offrom radiation (Verheij et al. 1994; van Kleef et al. 1998; Boerma et al. 2004) whichthat may be the cause of the increased platelet adherence and thrombus formation observed in irradiated capillaries and arteries (;???>Schultz-Hector et al. 1992; Darby et al. 2005; Ivanov et al. 2006; Hussein et al. 2008).

Comment [ON18]: Please add a (ref. 145) or b (ref. 146) to publication year to match reference list.

Correct is the ref. no. 145 (a). There is experimental evidence suggeststo suggest that RIHD is the result of an indirect myocytes secondary effect on myocytes, caused by microvascular and macro-vascular damage (Corn et al. 1990; Gagliardi et al. 2001; Jaworski et al. 2013).

Endothelial dysfunction is believed to be a precipitating factor in the development of cardiac sequelae (Paris et al. 2001)>), and is most likely a combination of impaired endothelial function, stimulation of growth factors, and eventual fibrosis (Darby et al. 2010).

Interestingly, according to animal studies, the pathophysiology of RIHD seems to be fundamentally different from non-radiation-related chronic heart failure. In the latter, the reduction of cardiac output induces a sustained activation of the sympathetic nervous system and, subsequently, a down-regulation of cardiac -receptors. In RIHD, the adrenal catecholamine synthesis is unchanged and cardiac catecholamine content is reduced, leading to an increase of -receptor density (;???>Schultz-Hector et al. 1992; Gyenes 1998).


Correct is the ref. no. 146 (b). Other strategies may thus may include modulating the effects of vascular endothelial growth factor (VEGF) on tight junction proteins. VEGF-mediated increases in vascular permeability are associated with endothelial nitric oxide synthase (eNOS) activity and the release of nitric oxide (NO) (Bates 2010).

This

process is probably related to microcirculatory damage, as therapeutic

doses of irradiation do not seem to cause direct damage to myocytes. Endothelial damage leads to an acute inflammatory reaction (dueowing to acute swelling of the endothelial cells). The activation of the coagulation mechanisms leads to fibrin deposition. The activation of macrophages and monocytes during the inflammatory process results in the secretion of cytokines, including TNF-α, IL–-1, IL–-6, IL–-8, monocyte chemotactic factor, and later platelet-derived growth factor (PDGF) and TGF-. These early effects are followed by organized fibrin formation, endothelial proliferation, and collagen deposition (Slezak et al. 2013;>, Slezak et al. 2014), and, in the late phase, fibroblastic proliferation and enhanced atherosclerosis. Microscopy has revealed an


Correct is the ref. no. 158 (b).

increased amount of collagen and a higher proportion of type I collagen (relative to type III) amount (; morphometry) of collagen) 6 w weeks after irradiation.


Significant increase ofincreases in collagen I, enhances the rigidity of the myocardium (;???>Schultz-Hector et al. 1992; Chello et al. 1996; Gyenes 1998, Slezak et al. 2014.).

The early and late side-effects of radiation limit dose escalation, and affect the patients quality of life. Irradiated endothelial cells acquire a



proinflammatory, procoagulant, and prothrombotic phenotype. Reduced myocardial capillary density in later stages (Baker et al. 2009), focal loss of endothelial alkaline phosphatase (Schultz-Hector and Balz 1994), and increased expression of von Willebrand factorvWf (Boerma et al. 2004) are leading hallmarks of irradiation damage.

Von Willebrand factor (vWf), is a glycoprotein involved in blood coagulation, and is synthesized by endothelial cells. vWf mediates the adherence of platelets to one another and to the sites of vascular damage. Increased amounts of vWf in blood plasma or tissue samples are indicative of damaged endothelium. It is important in the modulation of platelets and leukocyte recruitment and the formation of blood clots (Gabriels et al. 2012). Six weeks after irradiation, vessels had increased von Willebrand Factor expression, of vWf, which is indicative of endothelial cell damage (Slezak et al. 2013).


Correct is the ref. no. 158 (b). Radiation is alteringalso alters the functional properties of cardiac sarcolemmal Na, K-ATPase (Mezesova et al. 2014).


These various mechanisms probably result in different cardiac pathologies, e.g., coronary artery atherosclerosis leading to myocardial infarction, versusor microvascular damage and fibrosis leading to congestive heart failure (Stewart et al. 2013).

The role of mononuclears mononuclear cells and mastocytes in irradiated myocardium

Early radiation-induced damage to the myocardium wasis primarily represented primarily by chronic inflammatory cellscell infiltration in the ventricular myocardium at 6 weeks after 25 Gy irradiation. with 25 Gy, without decreases in microvascular density was not decreased at this time period (after 6 weeks and 25 Gy (Slezak et al 2014)).>). Myocardial and

microvascular inflammatory changes were leadingled to extravasation of blood cells, creationproduction of microthrombi, and signs of fibrosis. Monocytes -(a type of

mononuclear leukocytesleukocyte) infiltrate the myocardium in response to radiation-induced inflammatory signals and undergo activation. Activated monocytes produce and secrete several pro-inflammatory cytokines (TNF-α, IL-1, and IL-12) that amplify the inflammatory response (Okunieff et al. 2008).


Postirradiation inducedIrradiation induces mast mast-cellcells degranulation and interaction with many cellular and molecular systems in the heart. For instance, mast-cell-derived proteinases, have been shown to contribute to both the formation and degradation of endothelin–-1 (ET-1) (Metsärinne et al. 2002; Maurer et al. 2004). Long-term up-regulation of the endothelin system may have detrimental effects due to the vasopressor, prohypertrophic, and pro-fibrotic properties of ET–-1 (Giannessi et al. 2001). Mast cells express the receptor endothelin A receptor (ET-A), which, upon activation by ET–-1, induces mast cell degranulation (Yamamura et al. 1994), a pathway by which ET–-1 may enhance the activity of matrix metalloproteinases (MMPs) in the heart (Janicki et al. 2006; Lundequist et al. 2006).

In recent years, microRNAs (miRNAs) have also emerged as novel regulators of gene expression. miRNAs

participate in many cellular processes, such as apoptosis, fat

metabolism, cell differentiation, tumorigenesis, and cardiogenesis. MiRNAs are also critically involved in the pathological processprocesses of cardiac hypertrophy, angiogenesis, arrhythmogenesis, radiation injury, and heart failure. Suppression of


injurious genes may lead to upregulationup-regulation of protective proteins, including eNOS and HSP70. Nevertheless, the protection observed clearly suggests that the concerted action of one or perhaps several miRNAs, may have been responsible for the increased expression of cardioprotective substances (Yin et al. 2009). MiR15b is pro-apoptotic and is linked with injury caused by ischemia. Six weeks after 25 Gy mediastinal irradiation with 25 Gy, miR–-15b was down-regulated in the heartsheart almost by 42% which is%, indicating that these hearts are the heart is probably protected or that there is an

adaptive compensatory mechanism triggered upon irradiation (Slezak et al. 2013). Expression of microRNA–-21 in these heartsthe heart was increased nearly 10-fold, which points to

compensatory/protective effecteffects in the myocardium 6 weeks after radiation



(Sayed et al. 2010; Qin et al. 2012; Slezak et al. 2013; Skommer et al. 2014).


Correct is the ref. no. 157 (a). Postischemia/reperfusion mRNA levels of mRNA of PPAR alpha werePPARα are significantly lower after I/R in the hearts of irradiated animals than in the hearts of their control counterparts, indicating a shift in substrate preferences from fatty acids to glucose.

Myocardial Cx43 was upregulatedis up-regulated via reduced levels of miRNA–-1 that coud, which could be interpreted as is an adaptive/protective mechanism triggered 6 weeks uponafter irradiation (Radosinska et al.

Comment [JD29]: Author: do the changes preserve your meaning?

2011; Viczenczova et al. 2013;>,


Viczenczova et al. 2014). Connexin–-43 (Cx43) cardiac gap junction channels play thea crucial role in synchronizing the myocardium, allowing impulse propagation from pacemaker cells along the conduction system and throughout the atria and ventricles. TheThese channels, in addition, are permeable to ions and small molecules (up to 1 kD) that), which is important for direct cell-to-cell communication. Cx43 channels are opened and closed (gated) by various treatments. Likewise, Cx43 expression and distribution can be modulated by various physiological and pathophysiological stimuli (Salameh and Dhein 2005). Impaired intercellular communication due to diseaserelated alterations in myocardial Cx43 distribution and (or) expression promotes the development of life-threatening arrhythmias and contractile dysfunction (Severs et al. 2004; Tribulova et al. 2008).


Barancik et al. (2013) demonstrated tissue-specific alterations in the activation of cardiac MMP–-2 sixat 6 weeks after exposure to irradiation. The stimulatory effects of irradiation on circulating MMP–-2 in rats suggest that this enzyme plays a significant role in the progression of the effects induced by irradiation and may be responsible for the development of pathological changes induced by cardiac irradiation.

Circulating MMPs have been proposed to beas a prognostic factor for survival in patients with heart failure, and a recent study has demonstrated a strong positive correlation between plasma levels of MMP–-2, myocardial infarction size, and left ventricular dysfunction. These findings suggest that the observed activation of MMP–-2 in circulation may have a negative impact on the progression of pathological changes induced as a consequence of mediastinal irradiation.

It washas been found that irradiation of rats significantly increased the activities of circulating 72 kDa MMP–-2. in the circulation. Importantly, the application of acetylsalicylic acid (ASA) or statin markedly reduced the effecteffects of irradiation on circulating MMP–-2 (Barancik et al.

2013).

The induction of heat-shock proteins washas also been reported to be involved in the adaptive response (Kang et al. 2002).

Ceramides are a family of waxy lipid molecules found in high concentrations within the cell membranes. A ceramide is composed of sphingosine and a fatty acid. They are one of the structural elements and componentcomponents that make up sphingomyelin, one of the major lipids in the lipid bilayer that can participate, which participates in a variety of cellular signaling, including regulation of cell differentiation, and proliferation, andas well as programmed cell death of cells. Apoptotic signaling can be also facilitated by the interaction of ionizing radiation with cellular membranes, suggesting that direct DNA damage to DNA mediates radiation-induced cell death. It is noteworthy that the substances that can cause ceramide to be generated, tend to be stress signals that can cause the cells to go into programmed cell death. Ceramide thus acts as an intermediatory signal that links the external signalsignals with the internal metabolism of the cells

(Haimovitz-Friedman et al. 1994; Hallahan 1996). Recent evidence suggestshas suggested that ceramide regulates stress signaling via reorganization of the plasma membrane (Stancevic and Kolesnick 2010).

Following thoracic irradiation, ICAM–1intracellular adhesion molecule-1 (ICAM-1) and inflammation contribute to pulmonary fibrosis and injury. Expression of vascular cell adhesion molecule–-1 (VCAM–-1) and intracellular adhesion molecule–1 (ICAM-1) in the irradiated mouse lung wasis decreased by

manganese superoxide dismutase – plasmid/liposome gene therapy (Epperly et al. 2002).

Experimental findings suggest that radiation injury to the myocardial capillary network is the underlying cause of myocardial degeneration and heart failure after heart irradiation. A number of pro-inflammatory molecules have been reported to be upregulatedup-regulated by endothelial cell irradiation in vitro and in vivo. These adhesion molecules include E-selectin (a mediator of leukocyte rolling), ICAM (a mediator of leukocyte arrest), and PECAM–-1 (involved in leukocyte transmigration). These pro-inflammatory factors may be the molecular correlateindicators of early radiation-induced ultrastructural changes observed in the

microvessels of the myocardium (Fajardo and Stewart 1971; Schultz-Hector and Balz 1994).

The selectins are a family of cell adhesion molecules (or CAMs). All selectins are single-chain transmembrane glycoproteins. Selectins bind to sugar

Comment [JD31]: Author: change correct? “Correlate” is not correct in this context

moieties, and thus are considered to be a type of lectin, cell adhesion proteinsi.e., CAMs that bindsbind sugar polymers. There are three3 subsets of selectins: Eselectin (in endothelial cells), L-selectin (in lymphocytes), and P-selectin (in platelets and endothelial cells) (;???>Fajardo 1970; Corn et al. 1990; Somers et al. 2000; Ley 2003; van Luijk et aal. 2005).).

The p53 protein plays a key role in the adaptive response. It is crucial infor multicellular organisms, where it regulates the cell cycle and, thus, functions as a tumor suppressor, preventing cancer and supporting cell and gene stability. The role of p53 in the response to radiation damage is complex, since it affects some aspects of DNA repair, controls checkpoint cell cycle arrest, and initiates apoptosis, etc. (Fei and El-Deiry 2003). Low doses of radiation can modulate the expression of a variety of genes (Sasaki et al. 2002). Exposure to high-dose doses of radiation could suppresssuppresses p53-dependent apoptosis (Takahashi

2001).

The morphological alterations in the early phase, about 6 h after the exposure to radiation, include acute inflammation of small/–medium size arteries

Comment [ON32]: Citation not found in reference list. Please add or change here.

This citation has wrong year of publication correct year is 1971 (ref. no. 41).

and a neutrophils infiltrateneutrophil infiltration affecting all layers of the heart. During the following latent phase, only slight progressive fibrosis can be detected bywith light microscopy. Electron microscopy studies demonstrate, however,

progressive damage ofto the myocardial capillary endothelial cells, leading to obstruction of the lumen and the formation of thrombi of fibrin and platelets. Eventually, the decreased patency of capillaries results in ischemic damage and subsequent myocardial cell death. As myocytes have no capability doto divide, these processes lead to their replacement by fibrosis. Damage may also affect myocardial cells involved in conduction processes, leading to arrhythmias (Stewart et al. 1995; Gagliardi et al. 2001). Early radiation damage to the myocardium wasis primarily represented primarily by chronic inflammatory cellscell infiltration in the ventricular myocardium at 6 weeks after 25 Gy irradiation. SuprisinglySurprisingly, microvascular density wasis not decreased at this time. The presence of monocytes and mast cells represent thean important feature of this phase. Myocardial and microvascular inflammatory changes were leadinglead to extravasation of blood cells, creationproduction of microthrombi, and signessigns of fibrosis. A number of more or less acute effects including endothelial damage (seen in EM),

Comment [JD33]: Author: please define “EM”

inflammatory cell infiltration, and lysosomal activation, werehave been observed (Slezak et al. 2013).



Early structural alterations inchanges to irradiated endothelial cells are reversible, and later are followed by a persistent decrease in capillary density (Schultz-Hector and Balz 1994). Systematic morphometric studies in rats show that capillary volume and length density begin to decline about 20 days after heart irradiation, and the decline continues in a dose-dependent manner. A Capillary rarefication is also accompanied by a simultaneous focal loss of the endothelial cell marker enzyme, alkaline phosphatase, whichthe increase of which is time-dependent. SomeThere is evidence showsshowing that this enzyme is involved in regulating endothelial cell proliferation and microvascular blood flow by dephosphorylating extracellular nucleoside phosphates. When foci of myocardial degeneration developeddevelop, they wereare invariably situated in the areas of enzyme deficiency. Ultrastructural studies showedhave shown that the enzyme loss was not caused by a loss of endothelial cells, but was associated with the signs of endothelial cell activation, such as swelling, lymphocyte adhesion, and extravasation (Schultz-Hector and Balz 1994), as well as with increased endothelial cell proliferation (Lauk and Trott 1990; Slezak et al. 2013;>, Slezak et al. 2014). In the late phase, vessel lumen progressive obstruction of the


Correct is the ref. no. 158 vessel lumen and formation of fibrin thrombi and platelets, likesuch as those shown (b).

in electron microscopy studies, result in ischemia and subsequent myocardial cell death. This process leads to replacement of cardiac tissue by fibrotic tissueandtissue, and to chronic heart failure (Stewart et al. 1995; Gyenes 1998; Seddon et al. 2002; Adams et al. 2003; ;???>Schultz-Hector 2007).

DamageRadiation damage may also affect myocardial cells involved in the

Comment [ON36]: Citation not found in reference list. Please add or change (Schultz-Hector and Trott 2007-ref. 144) here.

Schultz-Hector and Trott 2007 (ref. 144). Comment [JD37]: Author: change correct?

process of conduction, leading to arrhythmias (Stewart et al. 1995). Injury of the pericardium may be presentappear as excessive pericardial fluid effusion, extensive fibrotic thickening, pericardial adhesions, and finally pericarditis (Stewart et al. 1995).

Cardiac output diddoes not decrease progressively in the early phase. after exposure to radiation. There wasis a modest, early decrease of cardiac output,;


however, after this drop, cardiac output remainedremains stable until the final heart failure (Schultz-Hector et al. 1992; Slezak et al. 2013). The concentration of beta-adrenoceptors in the irradiated heart increasedincreases by 50%, already% at 2 months after the irradiation, before there is any evidence of myocardial damage was apparent (Schultz-

Comment [ON39]: Please add a (ref. 145) or b (ref. 146) to publication year to match reference list. Comment [ON40]: Please add a (ref. 157), b (ref. 158), or c (ref. 159) to publication year to match reference list. Comment [ON41]: Please add a (ref. 145) or b (ref. 146) to publication year to match reference list.

ON39: Correct is the ref. no. 145 (a). ON40: Correct is the ref. no. 158 (b). ON41: Correct is the ref. no.146 (b).

Hector et al. 1992). This suggests that the initial radiation damage stimulated an up-regulation of cardiac contractility to a stable level via adrenergic mechanisms until the failure of compensatory mechanisms was evident. At the time of beginning of congestive heart failure, a sudden drop of left ventricular ejection

fraction and of cardiac output has been measured (Kitahara et al. 1993). This points outsuggests that cardiac output is not a safereliable criterion of sub-clinicalfor subclinical radiation damage to the heart, neither in experimental animals noror in the patients. SummarySome of some ofthe effects on the heart afterfrom irradiation is givenof the heart are summarized in the Fig.

5.

Radiation protection and treatment

Antioxidants have been studied for at least 50 years for their capacity to reduce the cytotoxic effects of radiation in normal tissues for at least 50 years. Early research identified sulfur-containing antioxidants as those with

the most beneficial therapeutic ratio. These compounds have substantial toxicity when given in vivo. Radiation protectorsCompounds that protect against radiation and that are not primarily antioxidants, including those that act through acceleration of cell proliferation (e.g., growth factors), prevention of apoptosis, other cellular

signaling effects (e.g., cytokine signal modifiers), or augmentation of DNA repair, all have direct or indirect effects on cellular redox state and levels of endogenous antioxidants (Okunieff et al. 2008).

Differences in the management of radiation-induced oxidative stress between tumors and normal tissues can provide a fundamental basis on which to design new anti-cancer therapeutic agents whichthat can exploit differences between the mechanisms by which normal tissue and tumor mechanisms of handlingtumors handle the oxidative stress offrom ionizing irradiation damage (Epperly et al. 2007; Greenberger and Epperly 2007). Unfortunately, some of known radioprotectors are toxic at doses required for radioprotection.

Treatments that reduce the risk or severity of damage to normal tissue or that facilitate the healing of radiation injury are being developed. These could greatly improve the quality of life of patients treated for cancer (Stone et al. 2003).

Although prevention ofpreventing radiation toxicity may provide the best opportunity to minimize impact on quality of life, few radioprotectors are in

clinical use, and the treatment of radiation injury remains an important target to dealfor dealing with radiation-induced side-effects. Novel technologies, such as

gene therapy, may offer the ability to reverse radiation-induced toxicities (Citrin et al. 2010).

In general, chemical/biological agents used to combat tissue toxicity from radiation can be broadly divided into three3 categories based on the timing of delivery in relation to radiation: (i) chemical radioprotectors,; (ii) mitigators,; and (iii) treatment (Stone et al. 2004).

Pharmacological agents can be used before or after radiation to reduce sideeffects, and are classified based on the timing of radiation delivery. “Radioprotectors,”, which are used as a molecular prophylactic strategy before

radiation, are mostly based on antioxidant properties. Currently, amifostine is the only radioprotector approved for theclinical use in the clinic. “. Mitigators,”, which are given during or shortly after irradiation, reduce the action of cellular ionizing radiation on normal tissues before the appearance of symptoms. Lastly, a “treatment” is the administration of an agent, once symptoms have developed, to

reverse those that are mostly due to fibrosis (Bentzen 2006; Citrin et al. 2010; Bourgier et al. 2012).

There is aare large amountamounts of data on the radioprotective effects of antioxidants at the cellular level, especially at the level of nuclear DNA, where the radical scavenging by the antioxidant protects this and other sensitive cellular targets. Many antioxidants have been shown to protect the cell by increasing cellular antioxidant capacity through their ability to elevate the levels of natural antioxidants and antioxidant enzymes. There are a number of hypotheses that have been suggested to explain the enhanced radioprotective effect of combined antioxidant treatments related to the regulation and response to ROS, including the regeneration of vitamin E and other antioxidants by vitamin C, induction of cellular antioxidant systems, and interaction with inflammatory mediators (Okunieff et al. 2008).

Antioxidants may interfere with the initial mediation of apoptosis by ROS (Salganik 2001), as well as later membrane lipid peroxidation later on, which is characteristic of radiation-induced apoptosis (McClain et al. 1995). The impact of radiation on the mitochondrial DNA, and thus, long-term reproductive health of the mitochondria, reproduction of the cell, and on cellular redox and energy state has not been studied in detailsdetail. The long-term consequences of radiation may be very

dependent on this mechanism of radiation toxicity, and may be greatly alleviated by properly designed antioxidant treatment (Okunieff et al. 2008).

Regarding the oxidative stress inunder physiological conditions, cells could increase the activities of antioxidant enzymes and other antioxidant defences to counteract the effects of oxidative stress. These include manganese dependent superoxide dismutase (Mn-SOD), copper/zinc superoxide dismutase (Cu/Zn-SOD), glutathione peroxidase, (GPx), glutathione reductase, and catalase (CAT). MnSODMn-SOD and Cu/ZnSODZn-SOD convert O 2 O2 to hydrogen peroxide,

which is then transformed to water by glutathione peroxidaseGPx or catalase.

When discussing antioxidants as radioprotectors, it is worth mentioning the use of SOD as a method to prevent radiotherapy-induced toxicity. Ionizing radiation results in the formation of superoxide radicals that are highly reactive and potentially damaging to cells. SOD is an enzyme that is naturally present in human cells. It catalyzes the conversion of superoxide to oxygen and hydrogen peroxide and functions as an antioxidant during normal conditions and after radiation. Protection of normal tissue against radiation-induced damage may increase the therapeutic ratio of radiotherapy. A promising strategy for testing this approach is

gene therapy-mediated overexpression of the copper-zinc (CuZnSOD) or manganese superoxide dismutase (MnSOD)Cu/Zn-SOD or Mn-SOD using recombinant adeno-

associated viral vectors (Tribble et al. 1999; Dröge 2002; Ferreira et al. 2004; Vassalle et al. 2008; Veldwijk et al. 2009; Citrin et al. 2010). Administration of manganese superoxide dismutase- – plasmid liposomes (MnSOD-PL) has been demonstrated to provide local radiation protection to the lung, esophagus, oral cavity, urinary bladder, and intestine. Radiation protection has been shown to be mediated in part by MnSODMn-SOD stabilization of the antioxidant pool including glutathione (GSH) and total thiols within cells and in normal tissues.

General antioxidant defense is also provided by low molecular weight antioxidants, which are hydrogen-atom–-donating reducing agents such as ascorbic acid, tocopherols, and polyphenols, and thiols such as glutathioneGSH. In this situation, the oxidants are neutralized by hydrogen atom donation, resulting in a less reactive or nonreactive product from the original oxidant and a radical product from the antioxidant, which no longer can exert detrimental effects (Citrin et al. 2010).

Radioprotective effect of antioxidants

Prevention of immediate radiation-induced genotoxicity requires that an antioxidant be present at the time of irradiation. To be maximally effective, the antioxidant must be present in the vicinity of DNA and thus must have an access to the nucleus. It must be able to either, 1) (i) react with all the oxygen-related free radicals and detoxify them to radicals that are not themselves genotoxic and (or) 2)(ii) effectively compete with oxygen to repair damage to the DNA chemically through reactions with free radicals on the DNA. Thiol-based compounds are especially good antioxidants because these compounds are capable of both scavenging oxygen radicals and affecting chemical repair of some forms of DNA damage with the subsequent formation of sulfur-based radicals, which are not reactive with DNA (Held 1988).

Sulfhydryl compounds such as cysteine and cysteamine have long been known to act as radioprotectors via free radical scavenging and H atom donation (Patt et al. 1949; Bacq 1954). Aminothiols could function as both radical scavengers and polyamine mimetics that influence DNA protection, repair, and synthetic processes.

Thiols such as amifostine and the newly developed nitroxides have sufficient reactivity to efficiently scavenge secondary radicals,; in fact, amifostine is the only synthetic antioxidant used clinically (Seed 2005).

The application of antioxidant radioprotectors in various human radiation exposure situations has not been extensive, although it is generally accepted that endogenous antioxidants, such as cellular non-protein thiols and antioxidant enzymes, provide some degree of protection.

Pathohistology examinations have revealed better radioprotective effects offrom fullerenol compared towith those of amifostine on the spleen, small

intestine, and lung, whilewhereas amifostine hadhas shown better radioprotective effects than fullerenol in protection of the heart, liver, and kidney (Trajkovi[acute]c et al. 2007). Captopril (Yarom et al. 1993), amifostine (Kruse et al. 2003)>), and a combination of pentoxifylline and alphaα-tocopherol (Boerma et al. 2008) showedhave shown some potential advantage inadvantages for the prevention of myocardial damage, but their clinical

usefulness has to be yet demonstrated.

A number of nonthiolnon-thiol radioprotective agents including protease inhibitors, vitamins, metalloelements, and calcium antagonists, are also used. as radioprotectors. There has been a virtual explosion of interest in biological, as opposed to chemical, modifiers of radiation injury. These biologicbiological compounds include cytokines, (such as interleukin IL-1 and granulocyte colonystimulating factor,), eicosanoids, (such as prostaglandins and leukotrienes,), and steroids/glucocorticoids, (such as dexamethasone and methylprednisolone.). In addition, an array of immunomodulatory agents, such as glucan and endotoxin have been described, which act nonspecifically by enhancing immunological and hemopoietic responses. Although some of these biologicbiological agents act best when given prior to irradiation, many of them can modulate radiation injury when given after irradiation, presumably by affecting the recovery and repopulation of critical tissue elements (Murray and McBride 2000).

Activation of proinflammatory and proliferative pathways is an integral part of the inflammatory response and involves activation of nuclear factor kappa B (NFkB)κB and TNF-α.

The involvement of NF-B was demonstrated in the induced expression of the antioxidant enzyme MnSODMn-SOD (Murley et al.


2004;>, Murley et al. 2006;>, Murley et al. 2007). Antioxidants including vitamin E and N-acetylcysteine have been shown to reverse activation of NF-B by TNF-α and IL–-1; however, it is thought that a non-antioxidant action on NF-B activity may also be responsible (Allport et al. 2000; Yeung et al. 2004).

TheThere are data indicateindicating that atorvastatin exerts protective effects on irradiated heart by reducing apoptosis byvia up-regulating thrombomodulin expression, (a thrombin membrane receptor) and enhancing protein C activation in


irradiated tissues (Ran et al. 2010).

TheA new, effective prevention of, preventative for radiation-induced inflammation could be based upon using of NF-kBκB inhibitors, anti TNF-TN-αF, statins, matrix metalloproteinasesmetalloproteinase inhibitors, free-radical scavengers, and inhibitors of mast-cell degranulation (Rainsford 2007; Slezak et al. 2013;>, Slezak et al. 2014).


Correct is the ref. no. 159 (c). Metalloporphyrin antioxidants ameliorate normal tissue radiation damage to normal tissue and are servingused as SOD mimetics to combat oxidative stress

against acute radiation-induced apoptosis and ameliorated delayed. They also ameliorate late phase damage to the blood-–brain barrier without producing a discernible increase in tissue superoxide disumtase (SOD) activity of SOD (Pearlstein et al. 2010).

Antioxidants derived from natural sources also exhibit dose-modifying effects on DNA damage and cell survival when present at the time of irradiation. This immediate protection is mediated by the scavenging of radicals. For example, there is a number of antioxidants, (including caffeine, melatonin, flavonoids, polyphenols, and other phytochemicals, which) that are shown to decrease radiation-induced damage in either plasmid or cellular DNA through the scavenging of oxygen radicals and (or) peroxides (Kumar et al. 2001; Frei and Higdon 2003).

Antioxidants are also phytochemicals, vitamins, and other nutrients that protect cells from damage caused by free radicals.

Phytochemicals are nonnutritivenon-nutritive bioactive plant substances, (such as a flavonoids or carotenoids) that are recognized to have a beneficial effect on human health and are also called phytonutrients. FromOf the antioxidant nutrients, only vitamins E and C and the mineral selenium are considered to be dietary antioxidants, and are defined as “a substance in foods that significantly decreases


the adverse effects of reactive species, such as reactive oxygenROS and nitrogen speciesRNS (Weiss and Landauer 2003). Also

Further, radioprotection by dietary vitamin A and -carotene in mice

exposed to partial-body irradiation or total-body irradiation has been reported (Seifter et al. 1988).

With the understanding that free radicals perpetuate a significant amount of the damage caused by ionizing radiation, multiple vitamin antioxidants have been tested as a methodfor their potential to reduce the toxicity of radiotherapy. Antioxidant compounds such as glutathioneGSH, lipoic acid, and the antioxidant vitamins A, C, and E have been evaluated in this context. Conversely, well-known antioxidants such as vitamin C and vitamin E do not act as classic radioprotectors (Citrin et al. 2010).

The vitamin E analog -tocotrienol (GT3) is regarded to be a potent radioprotector and mitigator. The efficacy of GT3 can be enhanced by the addition of the phosphodiesterase inhibitor pentoxifylline (PTX).) (Berbée et al. 2011).

Antifibrotic treatments, such as PTX and vitamin E, have shown promise in clinical trials.

Oral administration of PTX alone from 3 months to 6 months after irradiation did not significantly reverse myocardial remodeling or intracellular signaling, but instead, had an adverse effect on cardiac rhythm after local heart irradiation. While addition of a tocotrienol-enriched oral formulation could not correct the adverse effects of PTX on cardiac function, it reduced myocardial inflammatory infiltration (Sridharan et al. 2013).

Treatment with PTX and -tocopherol may have beneficial effects on radiation-induced myocardial fibrosis and left ventricular ex-vivo function, both when started before irradiation and when started later during the process of RIHD (Boerma et al. 2008). This approach should be expanded and new promising concepts of delaying the clinical manifestations of progressive ischemic heart disease should also be tested in RIHD (particularly in rats).

The ability to treat chronic inflammation by targeting NF-kappaBκB has been suggested for a number of available drugs, but there is a paucity of therapeuticaltherapeutic adjuncts suggested to cope with the adverse effects of

radiotherapy. It is, therefore, of utmost interest that the effects of PTX have been

studied even beyond NF-kappaBκB in the context of radiation-induced inflammation (Halle and Tornvall 2011).

Tocotrienols reduced a numberreduce levels of cardiac mast cells and macrophages. While this newa recent rat model of localized heart irradiation doesdid not support the use of PTX alone, the effects of tocotrienols on chronic manifestations of RIHD deserve further investigation (Sridharan et al. 2013).

The comment that PTX is suggested to prevent radiation-induced cardiotoxicity is indeed very interesting. Unfortunately, in our review, we were only able to mention a few potential targets of treatment to ameliorate radiationinduced tissue damage.

A large number of selenium (Se) derivatives, Se itself, and selenium and selenium/Se–vitamin E combinations have been studied for their radioprotective

effects (reviewed by Weiss et al. 1994).

Se compounds are found in a variety of foods; for example, Semethylselenocysteine is found in garlic and broccoli. Selenomethionine is a

Comment [JD46]: Author: does the change preserve your meaning?

naturally occurring derivative of low toxicity and is found in soy, grains, legumes, and selenium-enriched yeast (Whanger 2002).

Antioxidants derived from natural sources also exhibit dose-modifying effects on DNA damage and cell survival when present at the time of irradiation. This immediate protection is mediated by the scavenging of radicals. For example, there is a number of antioxidants, including caffeine, melatonin, flavonoids, polyphenols, and other phytochemicals (e.g., albana), which arethat have been shown to attenuate radiation-induced damage in either plasmid or cellular DNA through the scavenging of oxygen radicals and (or) peroxides (Kumar et al. 2001; Frei and Higdon 2003).

Finally, a number of phytochemicals, including caffeine, genistein, and melatonin, have been shown to have multiple physiological effects, as well as antioxidant activity, which resultresulted in radioprotection in vivo. Many antioxidant nutrients and phytochemicals have antimutagenic properties, and their modulation of long-term radiation effects have been demonstrated. A number of flavonoids (genistein, quercetin, luteolin, and other tea components of tea) reduce the frequency of micronucleated reticulocytes in the peripheral blood of irradiated mice (Shimoi et al. 1994). Procyanadins (flavan-3-ols) ),

including rutin, from grape seed extract, including rutin, were are radioprotective, as confirmed by a decrease in the number of micronucleated erythrocytes from bone marrow of irradiated mice (Castillo et al. 2000).

Melatonin (N-acetyl-5-methoxytryptamine), an endogenous antioxidant found in high concentrations in the pineal gland, is thought to act as an antioxidant itself (Lopez-Burillo et al. 2003; ;???>Reiter et al. 2003)>), but also is capable to increaseof increasing the expression of antioxidant enzymes such as SOD and glutathione peroxidaseGPx (Okatani et al. 2001). Radioprotection with melatonin and melatonin analogs has been documented in a number of animal models (Manda et al. 2007; Hussein et al. 2008). Melatonin




(N-acetyl-5-methoxytryptamine) has been shown to augment the activity

of glutathione peroxidaseGPx in addition to stimulating the activity of glutathione reductaseGR and increasing the synthesis of glutathione (GSH);; all of which are

important in reducing levels of oxygen radicals and peroxides in the cells (;???>Reiter et al. 2003; El-Missiry et al. 2007). Edible plants such as cherries may be a significant source of melatonin (Reiter and Tan 2002). Numerous studies have



demonstrated the protective effects of melatonin against oxidative stress caused by radiation.

Melatoninedible plants,

such as cherries, may be a significant source of melatonin, an endogenous antioxidant found in high concentrations in the pineal gland (Reiter and

Comment [JD50]: Author: please provide references

Tan 2002). A large number of studies has demonstrated the protective effects of melatonin against oxidative stress caused by radiation.

Resveratrol (RSV),) is a natural polyphenol, produced inby many plants. It is presentfound in the human diet, e.g., in fruits and in wine. RSV is known for its

antioxidant, anti-inflammatory, analgetic, antiviral, cardioprotective, neuroprotective, and antiaginganti-aging effects. Depending on the dose, RSV may act as an antioxidant or as a pro-oxidant. RSV is able to modulatemodulates the behavior of the cells in response to radiation-induced damage (Dobrzy[acute]nska 2013).

Methylxanthines, such as caffeine and theophylline, are adenosine receptor antagonists that modulate responses to radiation. This protective effect wasis related to the demonstrated antioxidant properties of caffeine in vitro, including scavenging of primary and secondary ROS.

Dietary flaxseed (FS) displays antioxidant and anti-inflammatory properties in preclinical models of lung disease, including radiation-induced pneumonopathy. FS inducedFS has been shown to induce significant changes in lung miRNA profile,

suggesting that modulation of small RNA by dietary supplements may represent a novel strategy to prevent the adverse side-effects of thoracic radiotherapy (Christofidou-Solomidou et al. 2014). Dietary FS given early

post-irradiation mitigatedhas been shown to mitigate radiation effects by decreasing inflammation, lung injury, and eventual fibrosis, while improving survival. FS may be a useful agent mitigating adverse effects of radiation in individuals exposed to radiation, inhaled radioisotopes, or even after the initiation of radiation therapy to treat the malignancy (Pietrofesa et al. 2013).

A number of new strategies and drugs including certain growth factors, compounds involved in signal transduction and apoptosis, synthetic aminothiols, cytokines, and gene therapies are under development to protect the cardiovascular system from the side effects of radiation (Basavaraju and Easterly 2002).

An important potential neuroprotector that has a pleiotropic function is

erythropoietin (EPO). ItEPO is a cytokine (protein signaling molecule) for erythrocyte (erythrocytes (Wong and Van der Kogel

2004), which>) that plays an important role in the brain response to neural injury.

Studies in experimental animals have shown protective effects of carnitine against exposure to ionizing radiation (Khan and Alhomida 2011).

Comment [JD51]: Author: do you have a reference?

Treatments that reduce the risk or severity of damage to normal tissue or that facilitate the healing of radiation injury are being developed. These could greatly improve the quality of life of patients treated for cancer (Stone et al. 2003).

Although the prevention of radiation toxicity may provide the best opportunity to minimize the impact on quality of life, few radioprotectors are in clinical use, and the treatment of radiation injury remains an important mechanism to deal with radiation-induced toxicity. Novel technologies, such as gene therapy, may offer the capability to reverse radiation-induced toxicities (Citrin et al. 2010).

Many cytokines and growth factors are radiation mitigators when used near the time of radiation. These agents stimulate the differentiation of stem cells in bone marrow or the intestine, thus preventing bone marrow failure or gastrointestinal syndrome after total body exposure. A number ofNumerous cytokines and growth factors hashave been explored as radioprotectors/mitigators.

Keratinocyte-Growth-Factor KGF is a growth factor that(KGF) stimulates a number of cellular processes such as differentiation, proliferation, DNA repair, and

detoxification of ROS (Finch and Rubin 2004). These properties make KGF an attractive method to stimulatefor stimulating the recovery of mucosa after ionizing radiation.

A variety ofVarious agents that protect against fibrosis hashave been evaluated as mitigators of radiation fibrosis. Transforming growth factor (TGF)-- plays a critical role in the development of radiation-induced fibrosis. It is, therefore, not surprising that many of the agents that have been used to prevent the development of radiation fibrosis directly or indirectly inhibit the TGF- signaling pathway (Citrin et al. 2010).

Moreover, some studies used animal models to test potential therapeutic strategies to utilizefor use before and after heart irradiation. It was shown that administration of Methylprednisolonmethylprednisolone or ibuprofen retarded the development of myocardial fibrosis, pericarditis, and pericardial effusion, and improved survival of rabitsrabbits in an experimental model of radiation-induced heart disease (Reeves et al. 1982).

Proinflammatory molecules COX–-2 and mPGES–-1 are involved in irradiation injury. PostirradiationPost-irradiation alterations in both COX–-1 and

COX–-2 vasoactive products contribute to endothelial and vascular dysfunction. Stewart et al. (2006) tested the efficacy of acetylsalicylic acid (ASA) and demonstrated protective effect in radiation induced endothelial dysfunction. Therefore, acetylosalicilic acidASA treatment may attenuate the


inflammatory response in the rat heart 6 weeks after irradiation (Slezak et al. 2013;>, Slezak et al. 2014). Inhibitor of COX–-2 regulates the production of PGs involved in

Comment [ON53]: Please add a (ref. 157), b (ref. 158), or c (ref. 159) to publication year to match reference list. Comment [JD54]: Author: define PGs

inflammation, pain, and fever. The roles of COX-2 and COX-1 in cardiovascular diseases may bring more light and facilitate developing newer agents to control conditions of inflammation and anti-inflammatory effects of ASA (Hasan et al. 2013).

Protection by ASA against irradiation injury may be mediated in part by the inhibition of COX–-2. ASA also increases plaque stability but diddoes not reduce the number or size of endothelial lesions of some ateriesarteries in irradiated mice (Hoving et al. 2008). However, anti-inflammatory and anticoagulant therapies werehave less effective in inhibiting radiation-induced atherosclerosis than age-related atherosclerosis, suggesting more complex underlying mechanistic pathways leading to the development of the irradiationinduced lesions.


Antibiotics, tetracyclines, and fluoroquinolones, which share a common planar ring moiety, werehave also been shown to be radioprotective. Furthermore, tetracycline protectedhas been shown to protect murine hematopoietic stem cells/progenitor cell populations from radiation damage. The choice of antibiotics in such emergencies, as well as in cancer patients receiving radiotherapy, could benefit from consideration of more than purely microbiological criteria, since not all classes of antibiotics are active. Although tetracyline and ciprofloxacin have long been utilized in the clinic and there is no evidence of long-term deleterious effects, their ability to inhibit or enhance radiation carcinogenesis should be investigated (Kim et al. 2009).

Mice pretreated with a high dose of Astragalus polysaccharide (APS) pretreatment led to remarkably less morphologicdemonstrated significantly fewer of the

characteristic morphological features of IRionizing-radiation-induced hepatic and pulmonary injury. Thus, APS exerts protective effects against IRionizing-radiationinduced liver and lung injury in liver in mice, and the related molecular mechanism may involve suppressing the radiation-induced oxidative stress reaction (Liu et al. 2014).

Septilin exhibitedhas been shown to demonstrate potential antioxidant activity and showed radioprotective effecteffects against gamma-radiation by preventing oxidative stress and scavenging free radicals (Mansour et al. 2014). The effect of sSeptilin in an Ayurvedic polymulti-herbal formulation exhibited potential antioxidant activity and showed radioprotective effecteffects against -gamma-radiation by preventing oxidative stress and

scavenging free radicals. Administration of septilin for 5 days (100 mg/kg) prior to radiation resulted in a significant increase in both superoxide dismutase (SOD) activity and total glutathione (GSH) level levels in hepatic and brain tissues (Mansour et al. 2014).

Hydrogen (H2) has a potential as an antioxidant in preventive and therapeutic applications. H2 selectively reduced the hydroxyl radical, the most cytotoxic of reactive oxygen species (ROS),, and effectively protected the cells; however, H2 did

not react with the other ROS, which that mediatesmediate physiological roles. H2 can be used as an effective antioxidant therapy; dueowing to its ability to rapidly diffuse across membranes, it can reach and react with cytotoxic ROS and thus protect against oxidative damage (Ohsawa et al. 2007). Consumption of hydrogen-rich water reduces the biological reaction to radiationinduced oxidative stress without compromising anti-tumor effects. These

Comment [JD55]: Author: does the change preserve your meaning?

encouraging results suggested that H2 represents a potentially novel preventive strategy for radiation-induced oxidative injuries (;???>Chuai et al. 2012; Qian et al. 2013). Chuai et al. (2012) found that pre-treatment with H2 prior to IR (ionizing radiation) significantly suppressed the reaction of OH •OH and the cellular macromolecules whichthat caused lipid peroxidation, increases in protein carbonyl levels, and

oxidatively damaged DNA.

Comment [ON56]: Please add a (ref. 25) or b (ref. 26) to publication year to match reference list. Comment [ON57]: Please add a (ref. 25) or b (ref. 26) to publication year to match reference list. Comment [JD58]: Author: change correct?

ON56: Correct is the ref. no. 25 (a). ON57: Correct is the ref. no. 26 (b).

The role of the renin–angiotensin system (RAS) in normal tissue radiation injury has been well-defined (Robbins and Diz 2006). Inhibitors of angiotensin-converting enzyme (ACE) and antagonists of angiotensin type 1 receptors reduce injury in some animal models of irradiation (Robbins et al. 2009). Inhibition

of ACE is considered to be cardioprotective, in part by suppressing

the breakdown of bradykinin by ACE (Fleming 2006).

New treatments for IHDinduced heart disease are being developed. Various types of stem cells are being studied to determine whether and how they diferentiatedifferentiate into new cardiomyocytes (Bearzi et al. 2007; Wang and Li 2007). Another approach is to inject mesenchymal stem cells overexpressing hepatocyte growth factor (HGF) (Duan et al. 2003), or application-deffcientdeficient adenovirus carrying the HGF gene to stimulate the regeneration of cardiomyocytes.


Preliminary data show that HGF gene transfer and expression can improve myocardial perfusion of locally irradiated rat hearts. SPK1 (Sphingosine kinase 1, (SPK1; a downstream signal molecule involved in HGF signal cascades) gene transfer also induces neovascularisation, inhibits fibrosis, and improves ischemic heart function (Duan et al. 2007). Stem

cell and gene therapy both need further research to establish whether

they have the potential to be safe and effective treatments for radiation-induced heart disease.

Normal tissue injury remains an important limiting factor in the treatment of malignancies by radiotherapy. To deliver a radiation dose sufficient to eradicate a localised tumour, the normal tissues need to be protected. A number of pharmacological agents has been used experimentally, and some clinically, to minimize radiation damage to normal tissues. The limited evidence available suggests that radiation insult, like many other tissue injuries, is amenable to pharmacological intervention (Rezvani 2008; Guha and Kavanagh 2011).

The knowledge of molecular mechanisms involved in endothelium dysfunction following radiation is needed to identify therapeutic targets and develop strategies to prevent and /(or) reduce the side-effects offrom radiation therapy (Milliat et al. 2008).

Conclusions

While modern sofisticatedsophisticated radio-therapeutic techniques have reduced radiation exposure of the heart to radiation, they have not eliminated the side effect-effects of radiation. Radiation effects may occur directly as direct ionizationsionization damage of organic molecules or indirectly via free radical

processes,; events that occur after radiation and that are responsible for the injury to the normal tissue.

This review briefly summarizes the multiple damaging effects of free radicals, ROS, and reactive oxygen and nitrogen speciesRNS to the heart, resulting in radiation induced heart disease (RIHD).. Despite studies aimed to elucidate the

molecular and cellular mechanisms of RIHD, the pathogenesis of RIHD is largely unknown, and treatment is not available. Antioxidants are commonly employed to combat molecular damage mediated by oxygenROS and nitrogen-based reactants.RNS. Agents used to minimize toxicity as radioprotectors, mitigators, and therapeutics oftherapies for radiation-induced injury to normal tissue injury are reviewed in this

article.


Further work is needed to studyelucidate detailed molecular mechanisms of radiation-induced cardiac injury and, to develop methods attenuatingto attenuate the adverse effects of radiation on normal healthy tissue, and to help to improve the quality of life of oncologicalcancer patients.

Acknowledgements

This work was supported by the grant No. APVV–-0241–-11.

References

Adams, M.J., Lipshultz, S.E., Schwartz, C., Fajardo, L.F., Coen, V., and Constine, L.S. 2003. Radiation-associated cardiovascular disease: manifestations and management. Semin. Radiat. Oncol. 13(3): 345-356. doi:10.1016/S1053-4296(03)00026-2. PMID:12903022.

Allport, V.C., Slater, D.M., Newton, R., and Bennett, P.R. 2000. NF-kappaB and AP-1 are required for cyclo-oxygenase 2 gene expression in amnion epithelial cell line (WISH). Mol. Hum. Reprod. 6(6): 561-565. doi:10.1093/molehr/6.6.561. PMID:10825375.

Comment [JD61]: Author; who provided this grant?

Andratschke, N., Maurer, J., Molls, M., and Trott, K.R. 2011. Late radiation-induced heart disease after radiotherapy. Clinical importance, radiobiological mechanisms and strategies of prevention. Radiother. Oncol. 100(2): 160-166. doi:10.1016/j.radonc.2010.08.010. PMID:20826032.

Bacq, Z.M. 1954. The amines and particularly cysteamine as protectors against roentgen rays. Acta Radiol. 41(1): 47-55. doi:10.3109/00016925409175832. PMID:13138293.

Baeuerle, P.A., and Henkel, T. 1994. Function and activation of NF-kappa B in the immune system. Annu. Rev. Immunol. 12: 141-179. doi:10.1146/annurev.immunol.12.1.141. PMID:8011280.

Baker, E., Fish, B.L., Su, J., Haworth, S.T., Strande, J.L., Komorowski, R.A., et al. 2009. 10 Gy total body irradiation increases risk of coronary sclerosis, degeneration of heart structure and function in a rat model. Int. J. Radiat. Biol. 85(12): 1089-1100. doi:10.3109/09553000903264473. PMID:19995235.

Barancik, M., Okruhlicova, L., Fogarassyova, M., Bartekova, M., and Slezak, J. 2013. Mediastinal irradiation modulates myocardial and circulating matrix metalloproteinases. Exp. Clin. Cardiol. 18(Suppl. A): 37A-40A.

Barlic, J., Zhang, Y., and Murphy, P.M. 2007. Atherogenic lipids induce adhesion of human coronary artery smooth muscle cells to macrophages by upregulating chemokine CX3CL1 on smooth muscle cells in a TNFalphaNFkappaB-dependent manner. J. Biol. Chem. 282: 19167-19176. doi:10.1074/jbc.M701642200. PMID:17456471.

Basavaraju, S.R., and Easterly, C.E. 2002. Pathophysiological effects of radiation on atherosclerosis development and progression, and the incidence of cardiovascular complications. Med. Phys. 29(10): 2391-2403. doi:10.1118/1.1509442. PMID:12408314.

Bates, D.O. 2010. Vascular endothelial growth factors and vascular permeability. Cardiovasc. Res. 87(2): 262-271. doi:10.1093/cvr/cvq105. PMID:20400620.

Bearzi, C., Rota, M., Hosoda, T., Tillmanns, J., Nascimbene, A., De Angelis, A., et al. 2007. Human cardiac stem cells. Proc. Natl. Acad. Sci. U.S.A. 104(35): 14068-14073. doi:10.1073/pnas.0706760104. PMID:17709737.

Bentzen, S.M. 2006. Preventing or reducing late side effects of radiation therapy: Radiobiology meets molecular pathology. Nat. Rev. Cancer, 6(9): 702-713. doi:10.1038/nrc1950. PMID:16929324.

Berbée, M., Fu, Q., Garg, S., Kulkarni, S., Kumar, K.S., and Hauer-Jensen, M. 2011. Pentoxifylline enhances the radioprotective properties of -tocotrienol: differential effects on the hematopoietic, gastrointestinal and vascular systems. Radiat. Res. 175(3): 297-306. doi:10.1667/RR2399.1. PMID:21388273.

Boerma, M., and Hauer-Jensen, M. 2010. Preclinical research into basic mechanisms of radiation-induced heart disease. Cardiol. Res. Pract. 2011: 8p2011: 820953374p. doi:10.4061/2011/858262. PMID:20953374.

Boerma, M., Kruse, J.J.C.M., van Loenen, M.M., Klein, H.R., Bart, C.I., Zurcher, C., et al. 2004. Increased deposition of von Willebrand factor

in the rat heart after local ionizing irradiation. Strahlenther. Onkol. 180(2): 109116. doi:10.1007/s00066-004-1138-0. PMID:14762664.

Boerma, M., Roberto, K.A., and Hauer-Jensen, M. 2008. Prevention and treatment of functional and structural radiation injury in the rat heart by pentoxifylline and alpha-tocopherol. Int. J. Radiat. Oncol. Biol. Phys. 72(1): 170-177. doi:10.1016/j.ijrobp.2008.04.042. PMID:18632215.

Bourgier, C., Levy, A., Vozenin, M.C., and Deutsch, E. 2012. Pharmacological strategies to spare normal tissues from radiation damage: useless or overlooked therapeutics? Cancer Metastasis Rev. 31(3-–4): 699-712. doi:10.1007/s10555-012-9381-9. PMID:22706781.

Brand, K., Page, S., Walli, A.K., Neumeier, D., and Baeuerle, P.A. 1997. Role of nuclear factor-kappaB in atherogenesis. Exp. Physiol. 82: 297304. doi:10.1113/expphysiol.1997.sp004025. PMID:9129944.

Burger, A., Loffler, H., Bamberg, M., and Rodermann, H.P. 1998. Molecular and cellular basis of radiation fibrosis. Int. J. Radiat. Biol. 73(4): 401408. doi:10.1080/095530098142239. PMID:9587078.

Carnicka, S., Murarikova, M., Ferko, M., Lazou, A., Kukreja, R.C., Ziegelhöffer, A., et al. 2013a. The effects of chest irradiation on myocardial function and response to ischemia in isolated rat hearts. Cardiologa Hungarica, 43(Suppl. G): G11.

Carnicka, S., Slezak, J., Murarikova, M., Ferko, M., Lazou, A., Kukreja, R.C., et al. 2013b. The effects of chest irradiation on rat heart function and ischemic tolerance. In Proceedings of Advacesfrom the International Symposium on Advances in Cardiovascular Research: From Bench to Bedside. International symposium23–26 May 2013, Smolenice Castle – Congress Center of the

Slovak Academy of Sciences, Bratislava, Slovakia, May 23-26, 2013.,. International Academy of Cardiovascular Sciences. p.. 56.

Castillo, J., Benavente-Garcia, O., Lorente, J., Alcaraz, M., Redondo, A., Ortuno, J.A., et al. 2000. Antioxidant activity and radioprotective effects against chromosomal damage induced in vivo by X-rays of flavan-3-ols (procyanidins) from grape seeds (Vitis vinifera): comparative study versus other phenolic and organic compounds. J. Agric. Food Chem. 48(5): 1738-1745. doi:10.1021/jf990665o. PMID:10820088.

Chello, M., Mastroroberto, P., Romano, R., Zofrea, S., Bevacqua, I., and Marchese, A.R. 1996. Changes in the proportion of types I and III collagen in the left ventricular wall of patients with post-irradiative pericarditis. Cardiovasc. Surg. 4(2): 222-226. doi:10.1016/0967-2109(96)82320-9. PMID:8861442.

Christofidou-Solomidou, M., Pietrofesa, R., Arguiri, E., McAlexander, M.A., and Witwer, K.W. 2014. Dietary flaxseed modulates the miRNA profile in irradiated and non-irradiated murine lungs: a novel mechanism of tissue radioprotection by flaxseed. Cancer Biol. Ther. 15(7): 930-937. doi:10.4161/cbt.28905. PMID:24755684.

Chuai, Y., Gao, F., Li, B., Zhao, L., Qian, L., Cao, F., et al. 20122012a. Hydrogen-rich saline attenuates radiation-induced male germ cell loss

Comment [ON62]: Change correct?

Change is correct. in mice through reducing hydroxyl radicals. Biochem. J. 442(1): 49-56. doi:10.1042/BJ20111786. PMID:22077489.

Chuai, Y., Qian, L., Sun, X., and Cai, J. 20122012b. Molecular


Change is correct. hydrogen and radiation protection. Free Radic. Res. 46(9): 1061-1067. doi:10.3109/10715762.2012.689429. PMID:22537465.

Citrin, D., Cotrim, A.P., Hyodo, F., Baum, B.J., Krishna, M.C., and Mitchell, J.B. 2010. Radioprotectors and mitigators of radiation-induced normal tissue injury. Oncologist, 15(4): 360-371. doi:10.1634/theoncologist.2009S104. PMID:20413641.

Corn, B.W., Trock, B.J., and Goodman, R.L. 1990. Irradiation – related ischemic heart disease. J. Clin. Oncol. 8(4): 741-750. PMID:2179483.

Darby, S.C., McGale, P., Taylor, C.W., and Peto, R. 2005. Longterm mortality from heart disease and lung cancer after radiotherapy for early breast cancer: prospective cohort study of about 300,000 women in US SEER cancer registries. Lancet Oncol. 6(8): 557-565. doi:10.1016/S14702045(05)70251-5. PMID:16054566.

Darby, S.C., Cutter, D.J., Boerma, M., Constine, L.S., Fajardo, L.F., Kodama, K., et al. 2010. Radiation-related heart disease: current knowledge and future prospects. Int. J. Radiat. Oncol. Biol. Phys. 76(3): 656-665. doi:10.1016/j.ijrobp.2009.09.064. PMID:20159360.

Dobrzy[acute]nska, M.M. 2013. Resveratrol as promising natural radioprotector. Rocz. Panstw. Zakl. Hig. 64(4): 255-262. PMID:24693709.

Dröge, W. 2002. Free radicals in the physiological control of cell function. Physiol. Rev. 82(1): 47-95. doi:10.1152/physrev.00018.2001. PMID:11773609.

Duan, H.F., Wu, C.T., Wu, D.L., Lu, Y., Liu, H.J., Ha, X.Q., et al. 2003. Treatment of myocardial ischemia with bone marrow-derived mesenchymal stem cells over-expressing hepatocyte growth factor. Mol. Ther. 8(3): 467-474. doi:10.1016/S1525-0016(03)00186-2. PMID:12946320.

Duan, H.F., Wang, H., Yi, J., Liu, H.J., Zhang, Q.W., Li, L.B., et al. 2007. Adenoviral gene transfer of sphingosine kinase 1 protects heart against ischemia/reperfusion-induced injury and attenuates its postischemic failure. Hum. Gene. Ther. 18(11): 1119-1128. doi:10.1089/hum.2007.036. PMID:17939750.

Elahi, M.M., and Matata, B.M. 2006. Free radicals in blood: evolving concepts in the mechanism of ischemic heart disease. Arch. Biochem. Biophys. 450(1): 78-88. doi:10.1016/j.abb.2006.03.011. PMID:16620764.

Elahi, M.M., Naseem, K.M., and Matata, B.M. 2007. Nitric oxide in blood. The nitrosative-–oxidative disequilibrium hypothesis on the pathogenesis of cardiovascular disease. FEBS. J. 274(4): 906-923. doi:10.1111/j.17424658.2007.05660.x. PMID:17244198.

Elahi, M.M., Kong, Y.X., and Matata, B.M. 2009. Oxidative stress as a mediator of cardiovascular disease. Oxid. Med. Cell. Longev. 2(5): 259269. doi:10.4161/oxim.2.5.9441. PMID:20716913.

El-Missiry, M.A., Fayed, T.A., El-Sawy, M.R., and El-Sayed, A.A. 2007. Ameliorative effect of melatonin against gamma-irradiation-induced oxidative stress and tissue injury. Ecotoxicol. Environ. Saf. 66(2): 278-286. doi:10.1016/j.ecoenv.2006.03.008. PMID:16793135.

Epperly, M.W., Sikora, C.A., Defilippi, S.J., Gretton, J.E., BarSagi, D., Archer, H., et al. 2002. Pulmonary irradiation-induced expression of VCAM-I and ICAM-I is decreased by manganese superoxide dismutaseplasmid/liposome (MnSOD-PL) gene therapy. Biol. Blood Marrow Transplant. 8(4): 175-187. doi:10.1053/bbmt.2002.v8.pm12014807. PMID:12014807.

Epperly, M.W., Wegner, R., Kanai, A.J., Kagan, V., Greenberger, E.E., Nie, S., et al. 2007. Effects of MnSOD-plasmid liposome gene therapy on antioxidant levels in irradiated murine oral cavity orthotopic tumors. Radiat. Res. 167(3): 289-297. doi:10.1667/RR0761.1. PMID:17316075.

Fajardo, L.F., and Stewart, J.R. 1971. Capillary injury preceding radiation-induced myocardial fibrosis. Radiology., 101(2): 429-433. doi:10.1148/101.2.429. PMID:5114783.

Fei, P., and El-Deiry, W.S. 2003. P53 and radiation responses. Oncogene., 22(37): 5774-5783. doi:10.1038/sj.onc.1206677. PMID:12947385.

Ferreira, S.M., Lerner, S.F., Brunzini, R., Evelson, P.A., and Llesuy, S.F. 2004. Oxidative stress markers in aqueous humor of glaucoma patients. Am. J. Ophthalmol. 137(1): 62-69. doi:10.1016/S0002-9394(03)00788-8. PMID:14700645.

Finch, P.W., and Rubin, J.S. 2004. Keratinocyte growth factor/fibroblast growth factor 7, a homeostatic factor with therapeutic potential for

epithelial protection and repair. Adv. Cancer. Res. 91: 69-136. doi:10.1016/S0065230X(04)91003-2. PMID:15327889.

Fleming, I. 2006. Signaling by the angiotensin-converting enzyme. Circ. Res. 98(1): 887-896. doi:10.1161/01.RES.0000217340.40936.53. PMID:16614314.

Frei, B., and Higdon, J.V. 2003. Antioxidant activity of tea polyphenols in vivo: evidence from animal studies. J. NutNutr. 133(10): 3275S3284S. PMID:14519826.

Gabriels, K., Hoving, S., Seemann, I., Visser, N.L., Gijbels, M.J., Pol, J.F., et al. 2012. Local heart irradiation of ApoE(-/-)(–/–) mice induces microvascular and endocardial damage and accelerates coronary atherosclerosis. Radiother. Oncol. 105(3): 358-364. doi:10.1016/j.radonc.2012.08.002. PMID:22959484.

Gagliardi, G., Lax, I., and Rutqvist, L.E. 2001. Partial irradiation of the heart. Semin. Radiat. Oncol. 11(3): 224-233. doi:10.1053/srao.2001.23483. PMID:11447579.

Gaya, A.M., and Ashford, R.F. 2005. Cardiac complications of radiation therapy. Clin. Oncol. (R. Coll. Radiol.).), 17(3): 153-159. doi:10.1016/j.clon.2004.09.016. PMID:15900998.

Ghosh, S., Wu, Q., Mäder, M., Fish, B.L., Moulder, J.E., Jacobs, E.R., et al. 2009. Vascular injury following whole thoracic X-ray irradiation in the rat. Int. J. Radiat. Oncol. Biol. Phys. 74(1): 192-199. doi:10.1016/j.ijrobp.2009.01.006. PMID:19362237.

Giannessi, D., Del Ry, S., and Vitale, R.L. 2001. The role of endothelins and their receptors in heart failure. Pharmacol. Res. 43(2): 111-126. doi:10.1006/phrs.2000.0758. PMID:11243712.

Greenberger, J.S., and Epperly, M.W. 2007. Antioxidant gene therapeutic approaches to normal tissue radioprotection and tumor radiosensitization. In Vivo, 21(2): 141-146. PMID:17436562.

Guha, C., and Kavanagh, B.D. 2011. Hepatic radiation toxicity: avoidance and amelioration. Semin. Radiat. Oncol. 21(4): 256-263. doi:10.1016/j.semradonc.2011.05.003. PMID:21939854.

Gutteridge, J.M., and Halliwell, B. 2000. Free radicals and antioxidants in the year 2000. A historical look to the future. Ann. N.Y. Acad. Sci. 899: 136-147. PMID:10863535.

Gyenes, G. 1998. Radiation-induced ischemic heart disease in breast cancer –: a review. Acta Oncol. 37(3): 241-246. doi:10.1080/028418698429522. PMID:9677094.

Gyenes, G., Fornander, T., Carlens, P., Glas, U., and Rutqvist, L.E. 1996. Myocardial damage in breast cancer patients treated with adjuvant radiotherapy: a prospective study. Int. J. Radiat. Oncol. Biol. Phys. 36(4): 899-905. doi:10.1016/S0360-3016(96)00125-3. PMID:8960519.

Haimovitz-Friedman, A., Kan, C.C., Ehleiter, D., Persaud, R.S., McLoughlin, M., Fuks, Z., et al. 1994. Ionizing radiation acts on cellular

membranes to generate ceramide and initiate apoptosis. J. Exp. Med. 180(2): 525535. doi:10.1084/jem.180.2.525. PMID:8046331.

Hallahan, D.E. 1996. Radiation-mediated gene expression in the pathogenesis of the clinical radiation response. Semin. Radiat. Oncol. 6(4): 250267. doi:10.1016/S1053-4296(96)80021-X. PMID:10717183.

Halle, M., and Tornvall, P. 2011. Beyond nuclear factor kappaB in cardiovascular disease induced by radiotherapy. J. Intern. Med. 270(5): 486. doi:10.1111/j.1365-2796.2011.02439.x. PMID:21848917.

Han, W., and Yu, K.N. 2009. Response of cells to ionizing radiation. In Advances in biomedical sciences and engineering. Edited by S.C. Tjong. Bentham Science Publishers, Ltd., Hong Kong, China. pp.. 204-–262.

Hasan, D.M., Chalouhi, N., Jabbour, P., Dumont, A.S., Kung, D.K., Magnotta, V.A., et al. 2013. Evidence that acetylsalicylic acid attenuates inflammation in the walls of human cerebral aneurysms: preliminary results. J. Am. Heart Assoc. 2(1): e000019. doi:10.1161/JAHA.112.000019. PMID:23525414.

Hatoum, O.A., Otterson, M.F., Kopelman, D., Miura, H., Sukhotnik, I., Larsen, B.T., et al. 2006. Radiation induces endothelial dysfunction in murine intestinal arterioles via enhanced production of reactive oxygen species. Arterioscler. Thromb. Vasc. Biol. 26(2): 287-294. doi:10.1161/01.ATV.0000198399.40584.8c. PMID:16322529.

Held, K.D. 1988. Models for thiol protection of DNA in cells. Pharmacol. Ther. 39(1-–3): 123-131. doi:10.1016/0163-7258(88)90050-2. PMID:3059362.

Hendry, J.H., Akahoshi, M., Wang, L.S., Lipshultz, S.E., Stewart, F.A., and Trott, K.R. 2008. Radiation-induced cardiovascular injury. Radiat. Environ. Biophys. 47(2): 189-193. doi:10.1007/s00411-007-0155-7. PMID:18193445.

Hong, J.H., Chiang, C.S., Campbell, I.L., Sun, J.R., Withers, H.R., and McBride, W.H. 1995. Induction of acute phase gene expression by brain irradiation. Int. J. Radiat. Oncol. Biol. Phys. 33(3): 619-626. doi:10.1016/03603016(95)00279-8. PMID:7558951.

Hoving, S., Heeneman, S., Gijbels, M.J., te Poele, J.A., Russell, N.S., Daemen, M.J., et al. 2008. Single-dose and fractionated irradiation promote initiation and progression of atherosclerosis and induce an inflammatory plaque phenotype in ApoE(-/-)(–/–) mice. Int. J. Radiat. Oncol. Biol. Phys. 71(3): 848-857. doi:10.1016/j.ijrobp.2008.02.031. PMID:18514779.

Hussein, M.R., Abu-Dief, E.E., Kamel, E., Abou-El-Ghait, A.T., Abdulwahed, S.R., and Ahmad, M.H. 2008. Melatonin and roentgen irradiationinduced acute radiation enteritis in Albino rats: An animal model. Cell Biol. Int. 32(11): 1353-1361. doi:10.1016/j.cellbi.2008.08.001. PMID:18762261.

Imbert, V., Rupec, R.A., Livolsi, A., Pahl, H.L., Traenckner, E.B., Mueller-Dieckmann, C., et al. 1996. Tyrosine phosphorylation of I kappa B-alpha activates NF-kappa B without proteolytic degradation of I kappa B-alpha. Cell., 86(5): 787-798. doi:10.1016/S0092-8674(00)80153-1. PMID:8797825.

Ivanov, V.K., Maksioutov, M.A., Chekin, S.Y., Petrov, A.V., Biryukov, A.P., Kruglova, Z.G., et al. 2006. The risk of radiation-induced

cerebrovascular disease in Chernobyl emergency workers. Health Phys. 90(3): 199-207. doi:10.1097/01.HP.0000175835.31663.ea. PMID:16505616.

Janicki, J.S., Brower, G.L., Gardner, J.D., Forman, M.F., Stewart, J.A., Murray, D.B., et al. 2006. Cardiac mast cell regulation of matrix metalloproteinase-related ventricular remodeling in chronic pressure or volume overload. Cardiovasc. Res. 69(3): 657-665. doi:10.1016/j.cardiores.2005.10.020. PMID:16376324.

Jaworski, C., Mariani, J.A., Wheeler, G., and Kaye, D.M. 2013. Cardiac complications of thoracic irradiation. J. Am. Coll. Cardiol. 61(23): 23192328. doi:10.1016/j.jacc.2013.01.090. PMID:23583253.

Kang, C.M., Park, K.P., Cho, C.K., Seo, J.S., Park, W.Y., Lee, S.J., et al. 2002. Hspa4 (HSP70) is involved in the radioadaptive response: results from mouse splenocytes. Radiat. Res. 157(6): 650-655. doi:10.1667/00337587(2002)157[0650:HHIIIT]2.0.CO;2. PMID:12005543.

Kawano, S., Kubota, T., Monden, Y., Tsutsumi, T., Inoue, T., Kawamura, N., et al. 2006. Blockade of NF-kappaB improves cardiac function and

survival after myocardial infarction. Am. J. Physiol. Heart Circ. Physiol. 291(3): 1337-1344. doi:10.1152/ajpheart.01175.2005. PMID:16632551.

Khan, H.A., and Alhomida, A.S. 2011. A review of the logistic role of L-carnitine in the management of radiation toxicity and radiotherapy side effects. J. Appl. Toxicol. 31(8): 707-713. doi:10.1002/jat.1716. PMID:21818761.

Kim, I., Moon, S.O., Kim, S.H., Kim, H.J., Koh, Y.S., and Koh, G.Y. 2001. Vascular endothelial growth factor expression of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and Eselectin through nuclear factor-kappa B activation in endothelial cells. J. Biol. Chem. 276(10): 7614-7620. doi:10.1074/jbc.M009705200. PMID:11108718.

Kim, K., Pollard, J.M., Norris, A.J., McDonnald, J.T., Sun, Y., Micewicz, E., et al. 2009. High throughput screening identifies two classes of antibiotics as radioprotectors: tetracyclines and fluoroquinolones. Clin. Cancer Res. 15(23): 7238-7245. doi:10.1158/1078-0432.CCR-09-1964. PMID:19920105.

Kitahara, T., Liu, K., Solanki, K., and Trott, K.R. 1993. Functional and morphological damage after local heart irradiation and/or

adriamycin in Wistar rats. Radiat. Oncol. Investig. 1(4): 198-205. doi:10.1002/roi.2970010403.

Konings, A.W., Smit Sibinga, C.T., Aarnoudse, M.W., de Witt, S.S., and Lamberts, H.B. 1978. Initial events in radiation-induced atheromatosis. Damage to intimal cells. Strahlentherapie., 154(11): 795-800. PMID:715813.

Kruse, J.J., Strootman, E.G., and Wondergem, J. 2003. Effects of amifostine on radiation-induced cardiac damage. Acta Oncol. 42(1): 4-9. doi:10.1080/0891060310002168. PMID:12665324.

Kruse, J.J.C.M., Floot, B.G.J., te Poele, J.A.M., Russell, N.S., and Stewart, F.A. 2009. Radiation-induced activation of TGF- signaling pathways in relation to vascular damage in mouse kidneys. Radiat. Res. 171(2): 188-197. doi:10.1667/RR1526.1. PMID:19267544.

Kubes, P., Suzuki, M., and Granger, D.N. 1991. Nitric oxide: an endogenous modulator of leukocyte adhesion. Proc. Natl. Acad. Sci. U.S.A. 88(11): 4651-4655. doi:10.1073/pnas.88.11.4651. PMID:1675786.

Kumar, S.S., Devasagayam, T.P., Jayashree, B., and Kesavan, P.C. 2001. Mechanism of protection against radiation-induced DNA damage in plasmid pBR322 by caffeine. Int. J. Radiat. Biol. 77(5): 617-623. doi:10.1080/09553000110034649. PMID:11382340.

Kyrkanides, S., Moore, A.H., Olschowka, J.A., Daeschner, J.C., Williams, J.P., Hansen, J.T., et al. 2002. Cyclooxygenase-2 modulates brain inflammation-related gene expression in central nervous system radiation injury. Brain Res. Mol. Brain Res. 104(2): 159-169. doi:10.1016/S0169-328X(02)003534. PMID:12225870.

Lacher, M. 1990. The consequences of survival: cardiovascular complications of the treatment of Hodgkins Disease. In Hodgkins Disease. Edited by M. Lacher, and J. Redman. Lea & Febiger, Philadelphia, Pa. pp.. 267-–284.

Landry, D.B., Couper, L.L., Bryant, S.R., and Lindner, V. 1997. Activation of the NF-kappa B and I kappa B system in smooth muscle cells after rat arterial injury. Induction of vascular cell adhesion molecule-1 and monocytes chemoattractant protein-1. Am. J. Pathol. 151(4): 1085-1095. PMID:9327742.

Lauk, S. 1987. Endothelial alkaline phosphatase activity loss as an early stage in the development of radiation-induced heart disease in rat. Radiat. Res. 110(1): 118-128. doi:10.2307/3576889. PMID:3562789.

Lauk, S., and Trott, K.R. 1988. Radiation induced heart disease in hypertensive rats. Int. J. Radiat. Oncol. Biol. Phys. 14(1): 109-114. doi:10.1016/0360-3016(88)90058-2. PMID:3335446.

Lauk, S., and Trott, K.R. 1990. Endothelial proliferation in the rat heart following local heart irradiation. Int. J. Radiat. Biol. 57(5): 1017-1030. doi:10.1080/09553009014551131. PMID:1970990.

Lawrence, D.A. 1996. Transforming growth factor-beta: a general review. Eur. Cytokine. Netw. 7(3): 363-374. PMID:8954178.

Lee, M.S., Finch, W., and Mahmud, E. 2013. Cardiovascular complications of radiotherapy. Am. J. Cardiol. 112(10): 1688-1696. doi:10.1016/j.amjcard.2013.07.031. PMID:24012026.

Ley, K. 2003. The role of selectins in inflammation and disease. Trends Mol. Med. 9(6): 263-268. doi:10.1016/S1471-4914(03)00071-6. PMID:12829015.

Liu, Y., Liu, F., Yang, Y., Li, D., Lv., J., Ou, Y., et al. 2014. Astralagus polysaccharide ameliorates ionizing radiation-induced oxidative stress in mice. Int. J. Biol. Macromol. 68: 209-214. doi:10.1016/j.ijbiomac.2014.05.001. PMID:24820157.

Lopez-Burillo, S., Tan, D.X., Mayo, J.C., Sainz, R.M., Manchester, L.C., and Reiter, R.J. 2003. Melatonin, xanthurenic acid, resveratrol, EGCG, vitamin C and alpha-lipoic acid differentially reduce oxidative DNA damage induced by Fenton reagents: A study of their individual and synergistic actions. J. Pineal. Res. 34(4): 269-277. doi:10.1034/j.1600-079X.2003.00041.x. PMID:12662349.

Lundequist, A., Åbrink, M., and Pejler, G. 2006. Mast celldependent activation of pro matrix metalloprotease 2: a role for serglycin proteoglycan-dependent mast cell proteases. Biol. Chem. 387(10-–11): 1513-1519. doi:10.1515/BC.2006.189. PMID:17081126.

Mach, F., Schonbeck, U., and Libby, P. 1998. CD40 signaling in vascular cells: A key role in atherosclerosis? Atherosclerosis., 137(Suppl. 1): 8995. doi:10.1016/S0021-9150(97)00309-2. PMID:9694547.

Manda, K., Anzai, K., Kumari, S., and Bhatia, A.L. 2007. Melatonin attenuates radiation-induced learning deficit and brain oxidative stress in mice. Acta Neurobiol. Exp. (Wars)..), 67(1): 63-70. PMID:17474322.

Mansour, H.H., Ismael, Nel-S., and Hafez, H.F. 2014. Ameliorative effect of septilin, an ayurvedic preparation against gammairradiation-induced oxidative stress and tissue injury in rats. Indian J. Biochem. Biophys. 51(2): 135-141. PMID:24980017.

Matsumoto, H., Takahashi, A., and Ohnishi, T. 2004. Radiationinduced adaptive responses and bystander effects. Biol. Sci. Space., 18(4): 247254. doi:10.2187/bss.18.247. PMID:15858392.

Maurer, M., Wedemeyer, J., Metz, M., Piliponsky, A.M., Weller, K., Chatterjea, D., et al. 2004. Mast cells promote homeostasis by limiting

endothelin-1-induced toxicity. Nature, 432(7016): 512-516. doi:10.1038/nature03085. PMID:15543132.

McClain, D.E., Kalinich, J.F., and Ramakrishnan, N. 1995. Trolox inhibits apoptosis in irradiated MOLT-4 lymphocytes. FASEB. J. 9(13): 1345-1354. PMID:7557025.

Mège, A., Ziouèche, A., Pourel, N., and Chauvet, B. 2011. Radiation-related heart toxicity. Cancer Radiother. 15(6-–7): 495-503. doi:10.1016/j.canrad.2011.06.003. PMID:21885320.

Metsärinne, K.P., Vehmaan-Kreula, P., Kovanen, P.T., Saijonmaa, O., Baumann, M., Wang, Y., et al. 2002. Activated mast cells increase the level of endothelin-1 mRNA in cocultured endothelial cells and degrade the secreted peptide. Arterioscler. Thromb. Vasc. Biol. 22(2): 268-273. doi:10.1161/hq0202.103994. PMID:11834527.

Mezesova, L., Vlkovicova, J., Kalocayova, B., Jendruchova, V., Barancik, M., Fulop. M., et al. 2014. Effects of -irradiation on Na, K-ATPase in

cardiac sarcolemma. Mol. Cell. Biochem. 388(1-–2): 241-247. doi:10.1007/s11010-013-1915-0. PMID:24347175.

Milliat, F., François, A., Tamarat, R., and Benderitter, M. 2008. Role of endothelium in radiation-induced normal tissue damages. Ann. Cardiol. Angeiol. (Paris)), 57(3): 139-148. doi:10.1016/j.ancard.2008.02.015. PMID:18579118.

Moore, A.H., Olschowka, J.A., Williams, J.P., Paige, S.L., and OBanion, M.K. 2004. Radiation-induced edema is dependent on cyclooxygenase 2 activity in mouse brain. Radiat. Res. 161(2): 153-160. doi:10.1667/RR3116. PMID:14731075.

Mothersill, C., and Seymour, C. 2001. Radiation-induced bystander effects: Past history and future directions. Radiat. Res. 155(6): 759-767. doi:10.1667/0033-7587(2001)155[0759:RIBEPH]2.0.CO;2. PMID:11352757.

Murley, J.S., Kataoka, Y., Cao, D., Li, J.J., Oberley, L.W., and Grdina, D.J. 2004. Delayed radioprotection by NFkappaB-mediated induction of Sod2 (MnSOD) in SA-NH tumor cells after exposure to clinically used thiol-

containing drugs. Radiat. Res. 162(5): 536-546. doi:10.1667/RR3256. PMID:15624308.

Murley, J.S., Kataoka, Y., Weydert, C.J., Oberley, L.W., and Grdina, D.J. 2006. Delayed radioprotection by nuclear transcription factor kappaBmediated induction of manganese superoxide dismutase in human microvascular endothelial cells after exposure to the free radical scavenger WR1065. Free Radic. Biol. Med. 40(6): 1004-1016. doi:10.1016/j.freeradbiomed.2005.10.060. PMID:16540396.

Murley, J.S., Kataoka, Y., Baker, K.L., Diamond, A.M., Morgan, W.F., and Grdina, D.J. 2007. Manganese superoxide dismutase (SOD2)-mediated delayed radioprotection induced by the free thiol form of amifostine and tumor necrosis factor alpha. Radiat. Res. 167(4): 465-474. doi:10.1667/RR0758.1. PMID:17388698.

Murray, D. and McBride, W.H. 2000. Radioprotective Agents. Kirk-Othmer Encyclopedia of Chemical Technology. Wiley. doi: 10.1002/0471238961.1801040913211818.a01

Niu, X.F., Smith, C.W., and Kubes, P. 1994. Intracellular oxidative stress induced by nitric oxide synthesis inhibition increases endothelial cell adhesion to neutrophils. Circ. Res. 74(6): 1133-1140. doi:10.1161/01.RES.74.6.1133. PMID:7910528.

Ohsawa, I., Ishikawa, M., Takahashi, K., Watanabe, M., Nishimaki, K., Yamagata, K., et al. 2007. Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals. Nat. Med. 13(6): 688-694. doi:10.1038/nm1577. PMID:17486089.

Okatani, Y., Wakatsuki, A., Shinohara, K., Kaneda, C., and Fukaya, T. 2001. Melatonin stimulates glutathione peroxidase activity in human chorion. J. Pineal. Res. 30(4): 199-205. doi:10.1034/j.1600-079X.2001.300402.x. PMID:11339508.

Okruhlicova, L., Knezl, V., Navarova, J., Sotnikova, R., Bernatova, I., Frimmel, K., et al. 2012. Inflammation-induced structural alterations of endothelium contribute to increased susceptibility of the heart to ischemia/reperfusion injury. Acta Physiol. 206(Suppl. 693): 208.

Okunieff, P., Swarts, S., Keng, P., Sun, W., Wang, W., Kim, J., et al. 2008. Antioxidants reduce consequences of radiation exposure. Adv. Exp. Med. Biol. 614: 165-178. doi:10.1007/978-0-387-74911-2_20. PMID:18290327.

Pacher, P., and Szabo, C. 2008. Role of the peroxynitritepoly(ADP-ribose) polymerase pathway in human disease. Am. J. Pathol. 173(1): 2-13. doi:10.2353/ajpath.2008.080019. PMID:18535182.

Paris, F., Fuks, Z., Kang, A., Capodieci, P., Juan, G., Ehleiter, D., et al. 2001. Endothelial apoptosis as the primary lesion initiating intestinal radiation damage in mice. Science., 293(5528): 293-297. doi:10.1126/science.1060191. PMID:11452123.

Patt, H.M., Tyree, E.B., Straube, R.L., and Smith, D.E. 1949. Cysteine protection against X irradiation. Science, 110(2852): 213-214. doi:10.1126/science.110.2852.213. PMID:17811258.

Pearlstein, R.D., Higuchi, Y., Moldovan, M., Johnson, K., Fukuda, S., Gridley, D.S., et al. 2010. Metalloporphyrin antioxidants ameliorate

normal tissue radiation damage in rat brain. Int. J. Radiat. Biol. 86(2): 145-163. doi:10.3109/09553000903419965. PMID:20148700.

Peng, H.B., Libby, P., and Liao, J.K. 1995. Induction and stabilization of I B by nitric oxide mediates inhibition of NF-B. J. Biol. Chem. 270(23): 14214-14219. doi:10.1074/jbc.270.23.14214. PMID:7775482.

Pietrofesa, R., Turowski, J., Tyagi, S., Dukes, F., Arguiri, E., Busch, T.M., et al. 2013. Radiation mitigating properties of the lignan component in flaxseed. BMC Cancer 13:179, 13: 179. doi:10.1186/1471-2407-13-179. PMID:23557217.

Qian, L., Shen, J., Chuai, Y., and Cai, J. 2013. Hydrogen as a new class of radioprotective agent. Int. J. Biol. Sci. 9(9): 887-894. doi:10.7150/ijbs.7220. PMID:24155664.

Qin, Y., Yu, Y., Dong, H., Bian, X., Guo, X., and Dong, S. 2012. MicroRNA 21 inhibits left ventricular remodeling in the early phase of rat model with ischemia-–reperfusion injury by suppressing cell apoptosis. Int. J. Med. Sci. 9(6): 413-423. doi:10.7150/ijms.4514. PMID:22859901.

Radosinska, J., Knezl, V., Benova, T., Urban, L, Tribulova, N., and Slezak, J. 2011. Alterations of the intercellular coupling protein, connexin-43, during ventricular fibrillation and sinus rhythm restoration demonstrated in male and female rat hearts: a pilot study. Exp. Clin. Cardiol. 16(4): 116-120. PMID:22131853.

Rainsford, K.D. 2007. Anti-inflammatory drugs in the 21st century. Subcell. Biochem. 42: 3-27. doi:10.1007/1-4020-5688-5_1. PMID:17612044.

Ran, X.Z., Ran, X., Zong, Z.W., Liu, D.Q., Xiang, G.M., Su, Y.P., et al. 2010. Protective effect of atorvastatin on radiation-induced vascular endothelial cell injury in vitro. J. Radiat. Res. 51(5): 527-533. doi:10.1269/jrr.09119. PMID:20921821.

Ravingerova, T., Bernatova, I., Matejikova, J., Ledvenyiova, V., Nemcekova, M., Pechanova, O., et al. 2011. Impaired cardiac ischaemic tolerance in spontaneously hypertensive rats is attenuated by adaptation to chronic and acute stress. Exp. Clin. Cardiol. 16(3): e23-e29. PMID:22065943.

Reeves, W.C., Cunningham, D., Schwiter, E.J., Abt, A., Skarlatos, S., Wood, M.A., et al. 1982. Myocardial hydroxyproline reduced by early administration of methylprednisolone or ibuprofen to rabbits with radiationinduced heart disease. Circulation., 65(5): 924-927. doi:10.1161/01.CIR.65.5.924. PMID:7074754.

Reiter, R.J., and Tan, D.X. 2002. Melatonin: an antioxidant in edible plants. Ann. N.Y. Acad. Sci. 957: 341-344. doi:10.1111/j.17496632.2002.tb02938.x. PMID:12074994.

Reiter, R.J., Tan, D.X., Manchester, L.C., Lopez-Burillo, S., Sainz, R.M., and Mayo, J.C. 20032003a. Melatonin: detoxification of oxygen and nitrogen-based toxic reactants. Adv. Exp. Med. Biol. 527: 539-548.


Change is correct.

doi:10.1007/978-1-4615-0135-0_62. PMID:15206772.

Reiter, R.J., Tan, D.X., Mayo, J.C., Sainz, R.M., Leon, J., and Czarnocki, Z. 20032003b. Melatonin as an antioxidant: biochemical mechanisms


Change is correct. and pathophysiological implications in humans. Acta Biochim. Pol. 50(4): 11291146. PMID:14740000.

Rezvani, M.U. 2008. Amelioration of the pathological changes induced by radiotherapy in normal tissues. Amelioration of the pathological changes induced by radiotherapy in normal tissues. J. Pharm. Pharmacol. 60(8): 1037-1048.

doi:10.1211/jpp.60.8.0010. PMID:18644196.

Ridnour, L.A., Thomas, D.D., Mancardi, D., Espey, M.G., Miranda, K.M., Paolocci, N., et al. 2004. The chemistry of nitrosative stress induced by nitric oxide and reactive nitrogen oxide species. Putting perspective on stressful biological situations. Biol. Chem. 385(1): 1-10. doi:10.1515/BC.2004.001. PMID:14977040.

Rieber, P., and Baeuerle, P.A. 1991. Reactive oxygen intermediates as apparently widely used messengers in the activation of the NFkappaB transcription factor and HIV-1. EMBO. J. 10(8): 2247-2258. PMID:2065663.

Robbins, M.E., and Diz, D.I. 2006. Pathogenic role of the reninangiotensin system in modulating radiation-induced late effects. Int. J. Radiat. Oncol. Biol. Phys. 64(1): 6-12. doi:10.1016/j.ijrobp.2005.08.033. PMID:16377409.

Robbins, M.E., Payne, V., Tommasi, E., Diz, D.I., Hsu, F.C., Brown, W.R., et al. 2009. The AT1 receptor antagonist, L-158,809, prevents or ameliorates fractionated whole-brain irradiation-induced cognitive impairment. Int. J. Radiat. Oncol. Biol. Phys. 73(2): 499-505. doi:10.1016/j.ijrobp.2008.09.058. PMID:19084353.

Rutqvist, L.E., Lax, I., Fornander, T., and Johansson, H. 1992. Cardiovascular mortality in a randomized trial of adjuvant radiation therapy versus surgery alone in primary breast cancer. Int. J. Radiat. Oncol. Biol. Phys. 22(5): 887-896. doi:10.1016/0360-3016(92)90784-F. PMID:1555981.

Salameh, A., and Dhein, S. 2005. Pharmacology of gap junctions .. New pharmacological targets for treatment of arrhythmia, seizure and cancer?

Biochim. Biophys. Acta, 1719(1-–2): 36-58. doi:10.1016/j.bbamem.2005.09.007. PMID:16216217.

Salganik, R.I. 2001. The benefits and hazards of antioxidants: controlling apoptosis and other protective mechanisms in cancer patients and the

human population. J. Am. Coll. Nutr. 20(5 Suppl.): 464S-472S; discussion 473S475S. doi:10.1080/07315724.2001.10719185. PMID:11603657.

Sasaki, M.S., Ejima, Y., Tachibana, A., Yamada, T., Ishizaki, K, Shimizu, T., et al. 2002. DNA damage response pathway in radioadaptive response. Mutat. Res. 504(1-–2): 101-118. doi:10.1016/S0027-5107(02)00084-2. PMID:12106651.

Sayed, D., He, M., Hong, C., Gao, S., Rane, S., Yang, Z., et al. 2010. MicroRNA-21 is a downstream effector of AKT that mediates its antiapoptotic effects via suppression of Fas ligand. J. Biol. Chem. 285(26): 2028120290. doi:10.1074/jbc.M110.109207. PMID:20404348.

Schultz-Hector, S. 1992. Radiation-induced heart disease: review of experimental data on dose reponse and pathogenesis. Int. J. Radiat. Biol. 61(2): 149-160. doi:10.1080/09553009214550761. PMID:1351901.

Schultz-Hector, S., and Balz, K. 1994. Radiation-induced loss of endothelial alkaline phosphatase activity and development of myocardial

degeneration: an ultrastructural study. Lab. Invest. 71(2): 252-260. PMID:8078304.

Schultz-Hector, S., and Trott, K.R. 2007. Radiation-induced cardiovascular disease: is the epidemiologic evidence compatible with the radiobiologic data? Int. Radiat. Oncol. Biol. Phys. 67(1): 10-18. doi:10.1016/j.ijrobp.2006.08.071. PMID:17189062.

Schultz-Hector, S., Bohm, M., Blochel, A., Dominiak, P., Erdmann, E., Muller-Schauenburg, W., et al. 1992. Radiation-induced heart disease: morphology, changes in catecholamine synthesis and content, betaadrenoceptor density, and hemodynamic function in an experimental model. Radiat. Res. 129(3): 281-289. doi:10.2307/3578027. PMID:1311862.

Schultz-Hector, S., Sund, M., and Thames, H.D. 1992. Fractionation response and repair kinetics of radiation-induced heart failure in the rat. Radiother. Oncol. 23(1): 33-40. doi:10.1016/0167-8140(92)90303-C. PMID:1736330.

Schultz-Hector, S., Balz, K., Bohm, M., Ikehara, Y., and Rieke, L. 1993. Cellular localization of endothelial alkaline phosphatase reaction product and enzyme protein in the myocardium. J. Histochem. Cytochem. 41(12): 18131821. doi:10.1177/41.12.8245430. PMID:8245430.

Seddon, B., Cook, A., Gothard, L., Salmon, E., Latus, K., Underwood, S.R., et al. 2002. Detection of defects in myocardial perfusion imaging in patients with early breast cancer treated with radiotherapy. Radiother. Oncol. 64(1): 53-63. doi:10.1016/S0167-8140(02)00133-0. PMID:12208576.

Seed, T.M. 2005. Radiation protectants: current status and future prospects. Health Phys. 89(5): 531-545. doi:10.1097/01.HP.0000175153.19745.25. PMID:16217197.

Seifter, E., Mendecki, J., Holtzman, S., Kanofsky, J.D., Friedenthal, E., Davis, L., et al. 1988. Role of vitamin A and beta carotene in radiation protection: relation to antioxidant properties. Pharmacol. Ther. 39(1-–3): 357-365. doi:10.1016/0163-7258(88)90083-6. PMID:3059375.

Senkus-Konefka, E., and Jassem, J. 2007. Cardiovascular effects of breast cancer radiotherapy. Cancer Treat. Rev. 33(6): 578-593. doi:10.1016/j.ctrv.2007.07.011. PMID:17764850.

Severs, N.J., Dupont, E., Coppen, S.R., Halliday, D., Inett, E., Baylis, D., et al. 2004. Remodelling of gap junctions and connexin expression in heart disease. Biochim Biophys. Acta, 1662(1-–2): 138-148. doi:10.1016/j.bbamem.2003.10.019. PMID:15033584.

Shimoi, K., Masuda, S., Furogori, M., Esaki, S., and Kinae, N. 1994. Radioprotective effect of antioxidative flavonoids in gamma-ray irradiated mice. Carcinogenesis, 15(11): 2669-2672. doi:10.1093/carcin/15.11.2669. PMID:7955124.

Skommer, J., Rana, I., Marques, F.Z., Zhu, W., Du, Z., and Charchar, F.J. 2014. Small molecules, big effects: the role of microRNAs in regulation of cardiomyocyte death. Cell Death. Dis. 5(7): e1325. doi:10.1038/cddis.2014.287. PMID:25032848.

Slezak, J., Tribulova, N., Ivanova, M., Styk, J., Frimmel, K., Ravingerova, T., et al. 2011. Proton radiation-induced cardiovascular toxicity: pathology and prevention. Exp. Clin. Cardiol. 16(Suppl. A): 28A.

Slezak, J., Tribulova, N., Ivanova, M., Styk, J., Frimmel, K., Ravingerova, T., et al. 2012. Chronic ischemic cardiomyopathy induced by mediastinal irradiation: pathology and prevention. Proceedings offrom the conference and advanced research workshop on “Sudden Cardiac Death & cardioprotection,and Cardioprotection.” Timisoara, Rom.,Romania, 6–9 September 69, 2012. p.. 52.

Slezak, J., Barancik, M., Ravingerova, T., Carnicka, S., Frimmel, K., Ferko, M., et al. 2013. Novel mechanisms involved in early phase of cardiovascular injury after mediastinal region irradiation. Cardiologia Hungarica, 43(Suppl. G): G24-G25.

Slezak, J., Barancik, M., Ravingerova, T., Carnicka, S., Frimmel, K., Ferko, M., et al. 2013. Mechanisms of early cardiac dysfunction after mediastinal irradiation. In Proceedings of Advacesfrom the International Symposium on Advances in Cardiovascular Research: From Bench to Bedside. International

symposiumSmolenice Castle – Congress Center of the Slovak Academy of Sciences,

Bratislava, Slovakia, May 23-26, 2013.,. International Academy of Cardiovascular Sciences. p.. 26.

Slezak, J., Fogarassyova, M., and Barancik, M. 2013. The role of matrix metalloproteinases in responses of rat hearts after mediastinal irradiation. In Proceedings of Advacesfrom the International Symposium on Advances in Cardiovascular Research: From Bench to Bedside. International symposiumSmolenice Castle – Congress Center of the Slovak Academy of Sciences, Bratislava, Slovakia, May 23-26, 2013.,. International Academy of Cardiovascular Sciences. p.. 72.

Slezak, J., Barancik, M., Ravingerova, T., Tribulova, N., Kura, B., Lazou, A., et al. 2014. Molecular mechanisms of myocardial irradiation injury and potential prevention targets. In Proceedings of New Frontiers in Basic Cardiovascular Research 2014: 11th Meeting of France -– New EU Members, Smolenice, Slovakia, 15–18 June 15-18, 2014. p.. 29.

Somers, W.S., Tang, J., Shaw, G.D., and Camphausen, R.T. 2000. Insights into the molecular basis of leukocyte tethering and rolling revealed

by structures of P- and E-selectin bound to SLe(X) and PSGL-1. Cell., 103(3): 467-479. doi:10.1016/S0092-8674(00)00138-0. PMID:11081633.

Sridharan, V., Tripathi, P., Sharma, S., Corry, P.M., Moros, E.G., Singh, A., et al. 2013. Effects of late administration of pentoxifylline and tocotrienols in an image-guided rat model of localized heart irradiation. PLoS One, 8(7): e68762. doi:10.1371/journal.pone.0068762. PMID:23894340.

Stancevic, B., and Kolesnick, R. 2010. Ceramide-rich platforms in transmembrane signaling. FEBS Lett. 584(9): 1728-1740. doi:10.1016/j.febslet.2010.02.026. PMID:20178791.

Stewart, F.A., Heeneman, J., te Poele, J., Kruse, J., Russell, N.S., Gijbels, M., et al. 2006. Ionizing radiation accelerates the development of atherosclerotic lesions in ApoE mice and predisposes to an inflammatory plaque phenotype prone to hemorrhage. Am. J. Pathol. 168(2): 649-658. doi:10.2353/ajpath.2006.050409. PMID:16436678.

Stewart, F.A., Hoving, S., and Russell, N.S. 2010. Vascular damage as an underlying mechanism of cardiac and cerebral toxicity in irradiated

cancer patients. Radiat. Res. 174(6): 865-869. doi:10.1667/RR1862.1. PMID:21128810.

Stewart, F.A., Seemann, I., Hoving, S., and Russell, N.S. 2013. Understanding radiation-induced cardiovascular damage and strategies for intervention. Clin. Oncol. 25(10): 617-624. doi:10.1016/j.clon.2013.06.012. PMID:23876528.

Stewart, J.R., and Fajardo, L.F. 1984. Radiation-induced heart disease: an update. Prog. Cardiovasc. Dis. 27(3): 173-194. doi:10.1016/00330620(84)90003-3. PMID:6387801.

Stewart, J.R., Fajardo, L.F., Gilletee, S.M., and Constine, L.S. 1995. Radiation injury to the heart. Int. J. Radiat. Oncol. Biol. Phys. 31(5): 12051211. doi:10.1016/0360-3016(94)00656-6. PMID:7713783.

Stone, H., Coleman, C.N., Anscher, M.S., and McBride, W.H. 2003. Effects of radiation on normal tissue: consequences and mechanisms. Lancet Oncol. 4(9): 529-536. doi:10.1016/S1470-2045(03)01191-4. PMID:12965273.

Stone, H.B., Moulder, J.E., Coleman, C.N., Ang, K.K., Anscher, M.S., Barcellos-Hoff, M.H., et al. 2004. Models for evaluating agents intended for the prophylaxis, mitigation and treatment of radiation injuries. Report of an NCI Workshop, 3–4 December 3-4, 2003. Radiat. Res. 162(6): 711-728. PMID:15548121.

Takahashi, A. 2001. Different inducibility of radiation- or heatinduced p53-dependent apoptosis after acute or chronic irradiation in human cultured squamous cell carcinoma cells. Int. J. Radiat. Biol. 77(2): 215-224. doi:10.1080/09553000010009495. PMID:11236928.

Tatton, W., Chalmers-Redman, R., and Tatton, N. 2003. Neuroprotection by deprenyl and other propargylamines: glyceraldehyde-3phosphate dehydrogenase rather than monoamine oxidase. J. Neural. Transm. 110(5): 509-515. doi:10.1007/s00702-002-0827-z. PMID:12721812.

Touyz, R.M., and Schiffrin, E.L. 2006. Peroxisome proliferatoractivated receptors in vascular biology-molecular mechanisms and clinical implications. Vascul. Pharmacol. 45(1): 19-28. doi:10.1016/j.vph.2005.11.014. PMID:16782410.

Trajkovi[acute]c, S., Dobri[acute]c, S., Ja[acute]cevi[acute]c, V., Dragojevi[acute]c-Simi[acute]c, V., Milovanovi[acute]c, Z., and Dordevi[acute]c, A. 2007. Tissue-protective effects of fullerenol C60(OH)24 and amifostine in irradiated rats. Colloids Surf. B Biointerfaces., 58(1): 39-43. doi:10.1016/j.colsurfb.2007.01.005. PMID:17317115.

Tribble, D.L., Barcellos-Hoff, M.H., Chu, B.M., and Gong, E.L. 1999. Ionizing radiation accelerates aortic lesion formation in fat-fed mice via SOD-inhibitable process. Arterioscler. Thromb. Vasc. Biol. 19(6): 1387-1392. doi:10.1161/01.ATV.19.6.1387. PMID:10364068.

Tribulova, N., Knezl. V., Okruhlicova, L., and Slezak, J. 2008. Myocardial gap junctions: targets for novel approaches in the prevention of lifethreatening cardiac arrhythmias. Physiol. Res. 57(Suppl. 2): S1-S13. PMID:18373398.

Triggle, C.R., Samuel, S.M., Ravishankar, S., Marei, I., Arunachalam, G., and Ding, H. 2012. The endothelium: influencing vascular

smooth muscle in many ways. Can. J. Physiol. Pharmacol. 90(6): 713-738. doi:10.1139/y2012-073. PMID:22625870.

Tsutsui, H., Kinugawa, S., and Matsushima, S. 2009. Mitochondrial oxidative stress and dysfunction in myocardial remodelling. Cardiovasc. Res. 81(3): 449-456. doi:10.1093/cvr/cvn280. PMID:18854381.

Valko, M., Morris, H., and Cronin, M.T. 2005. Metals, toxicity and oxidative stress. Curr. Med. Chem. 12(12): 1161-1208. doi:10.2174/0929867053764635. PMID:15892631.

Valko, M., Rhodes, C.J., Moncol, J., Izakovic, M., and Mazur, M. 2006. Free radicals, metals and antioxidants in oxidative stress-induced cancer. Chem. Biol. Interact. 160(1): 1-40. doi:10.1016/j.cbi.2005.12.009. PMID:16430879.

van der Meeren, A., Squiban, C., Gourmelon, P., Lafont, H., and Gaugler, M.H. 1999. Diferential regulation by IL-4 and IL-10 of radiation-induced IL-6 and IL-8 production and ICAM-1 expression by human endothelial cells. Cytokine., 11(11): 831-838. doi:10.1006/cyto.1999.0497. PMID:10547270.

van Kleef, E.M., te Poele, J.A., Oussoren, Y.G., Verheij, M., van de Pavert, I., Braunhut, S.J., et al. 1998. Increased expression of glomerular von Willebrand factor after irradiation of the mouse kidney. Radiat. Res. 150(5): 528534. doi:10.2307/3579869. PMID:9806594.

van Luijk, P., Novakova-Jiresova, A., Faber, H., Schippers, J.M., Kampinga, H.H., Meertens, H., et al. 2005. Radiation damage to the heart enhances early radiation-induced lung function loss. Cancer Res. 65(15): 6509-6511. doi:10.1158/0008-5472.CAN-05-0786. PMID:16061627.

Vassalle, C., Pratali, L., Boni, C., Mercuri, A., and Ndreu, R. 2008. An oxidative stress score as a combined measure of the pro-oxidant and antioxidant counterparts in patients with coronary artery disease. Clin. Biochem. 41(14-–15): 1162-1167. doi:10.1016/j.clinbiochem.2008.07.005. PMID:18692492.

Veldwijk, M.R., Herskind, C., Sellner, L., Radujkovic, A., Laufs, S., Fruehauf, S., et al. 2009. Normal-tissue radioprotection by overexpression of the copper-zinc and manganese superoxide dismutase genes. Strahlenther. Onkol. 185(8): 517-523. doi:10.1007/s00066-009-1973-0. PMID:19652935.

Verheij, M., Dewit, L.G., Boomgaard, M.N., Brinkman, H.J., and van Mourik, J.A. 1994. Ionizing radiation enhances platelet adhesion to the extracellular matrix of human endothelial cells by an increase in the release of von Willebrand factor. Radiat. Res. 137(2): 202-207. doi:10.2307/3578813. PMID:8134544.

Viczenczova, C., Bacova, B., Benova, T., Kura, B., Yin, C., Kukreja, R.C., et al. 20132013a. Irradiation-induced up-regulation of myocardial


Change is correct. connexin-43 is associated with repression of miR-1 in rat heart. Exp. Clin. Cardiol. 18(Suppl. A): 35A-36A.

Viczenczova, C., Bacova, B., Radosinska, J., Benova, T., Kukreja, R.C., Tribulova, N., et al. 20132013b. Single-dose irradiation up-regulates


Change is correct. myocardial connexin-43 associated with repression of miRNA-1 in rat heart. Proceeding of AdvacesIn Proceedings from the International Symposium on Advances

in Cardiovascular Research: From Bench to Bedside. International symposiumSmolenice Castle – Congress Center of the Slovak Academy of Sciences,

Bratislava, Slovakia, May 23-26, 2013.,. International Academy of Cardiovascular Sciences. p.. 73.

Viczenczova, C., Bacova, B., Kura, B., Yin, C., Kukreja, R.C., Slezak, J., et al. 2014. Post-irradiation induced myocardial changes of connexin43, PKC, mir-1 and mir-21 expression demonstrated in rats. In Proceedings of New Frontiers in Basic Cardiovascular Research 2014 :. 11th Meeting of France -– New EU Members, Smolenice, Slovakia, 15–18 June 15-18, 2014. p.. 94.

Vos, J., Aarnoudse, M.W., Dijk, F., and Lamberts, H.B. 1983. On the cellular origin and development of atheromatous plaques. A light and electron microscopic study of combined X-ray and hypercholesterolemia-induced atheromatosis in the carotid artery of the rabbit. Virchows. Arch. B Cell Pathol. Incl. Mol. Pathol. 43(1): 1-16. doi:10.1007/BF02932938. PMID:6136115.

Wang, X.J., and Li, Q.P. 2007. The roles of mesenchymal stem cells(MSCs) therapy in ischemic heart diseases. Biochem. Biophys. Res. Commun. 359(2): 189-193. doi:10.1016/j.bbrc.2007.05.112. PMID:17543286.

Weiss, J.F., and Landauer, M.R. 2003. Protection against ionizing radiation by antioxidant nutrients and phytochemicals. Toxicology, 189(1–2): 1-20. doi:10.1016/S0300-483X(03)00149-5. PMID:12821279.

Weiss, J.F., Srinivasan, V., Kumar, K.S., Landauer, M.R., and Patchen, M.L. 1994. Radioprotection by selenium compounds. In Trace elements and free radicals in oxidative diseases. Edited by A.E. Favier, J. Neve, and P. Fauve. AOCS Press, Champaign, IL,Ill. pp.. 211-–222.

Whanger, P.D. 2002. Selenocompounds in plants and animals and their biological significance. J. Am. Coll. Nutr. 21(3): 223-232. doi:10.1080/07315724.2002.10719214. PMID:12074249.

Wilson, S.H., Caplice, N.M., Simari, R.D., Holmes, D.R.., Jr., Carlson, P.J., and Lerman, A. 2000. Activated nuclear factor-B is present in the coronary vasculature in experimental hypercholesterolemia. Atherosclerosis, 148(1): 23-30. doi:10.1016/S0021-9150(99)00211-7. PMID:10580167.

Wong, C.S., and Van der Kogel, A.J. 2004. Mechanisms of radiation injury to the central nervous system: implications for neuroprotection. Mol. Interv. 4(5): 273-284. doi:10.1124/mi.4.5.7. PMID:15471910.

Yamamura, H., Nabe, T., Kohno, S., and Ohata, K. 1994. Endothelin-1 induces release of histamine and leukotriene C4 from mouse bone marrow-derived mast cells. Eur. J. Pharmacol. 257(3): 235-242. doi:10.1016/00142999(94)90134-1. PMID:7522171.

Yarom, R., Harper, I.S., Wynchank, S., van Schalkwyk, D., Madhoo, J., Williams, K., et al. 1993. Effect of captopril on changes in rats hearts induced by long-term irradiation. Radiat. Res. 133(2): 187-197. doi:10.2307/3578356. PMID:8438060.

Yeung, F., Hoberg, J.E., Ramsey, C.S., Keller, M.D., Jones, D.R., Frye, R.A., and Mayo, M.W. 2004. Modulation of NF-kappaB-dependent transcription and cell survival by the SIRT1 deacetylase. EMBO. J. 23(12): 23692380. doi:10.1038/sj.emboj.7600244. PMID:15152190.

Yin, C., Salloum, F.N., and Kukreja, R.C. 2009. A novel role of microRNA in late preconditioning upregulation of endothelial nitric oxide synthase and heat shock protein 70. Circ. Res. 104(5): 572-575. doi:10.1161/CIRCRESAHA.108.193250. PMID:19213952.

Zhong, G.Z., Chen, F.R., Bu, D.F., Wang, S.H., Pang, Y.Z., and Tang, C.S. 2004. Cobalt-60 gamma radiation increased the nitric oxide generation in cultured rat vascular smooth muscle cells. Life Sci. 74(25): 3055-3063. doi:10.1016/j.lfs.2003.08.049. PMID:15081571.

Fig. 1.Determinants of biological effects of radiation. Biological effect of radiation is influenced by many factors, including dose and rate of absorption, exposed area, cell sensitivity, and individual sensitivity.

Fig. 2.Effects of radiation on the cell. Ionizing radiation can damage several cell components. It causes alteration inchanges to the cell membrane and nuclear membrane permeability, and functional

aberrations in chromosomes and cellular organelles and can change its function, as well as functional changes.

Fig. 3.Effect of radiation on molecules. After exposure to ionizing radiation, atoms or molecules became ionized or excited and these can produce free radicals from other molecules, they can break many of chemical bonds in other chemical compounds, or they can

Comment [JD68]: Author: please check your figures carefully for conversion errors

produce a new chemical bonds from existing chemical compounds. Ionized/excited formforms of atoms/molecules can damage some important molecules, for example

DNA, RNA or, and proteins.

Fig. 4.Mechanisms of DNA damage after irradiation. The most important molecules whichthat may be affected by radiation are DNA molecules. Radiation can damage DNA in directdirectly or in indirect action.indirectly. In the first case, radiation affects DNA in direct waydirectly

by breaking chemical bonds in the DNA structure. This leadleads to the change of DNA sequence and to mutations. In the second case, DNA molecule ismolecules are indirectly affected by ROS produced from disruptingthe disruption of water molecules.

Fig. 5.Effect of radiation on the heart. Changes in the irradiated heart werehave been observed at molecular and sturctural levels. Radiation of the heart induces increased levels of ROS, which leads to DNA damage, increased levels of inflammatory cells, cytokines, macrophages, monocytes, or levels of NF-B, and TNF levels.-. Changes such as decreasingdecreased levels of capillary alkaline phosphatase or increasingincreased

von Willebrand factor levels., vascular leakage, increased fibrosis,

existancepresence of compensatory mechanisms, and final decrease in function of

the heart and heart failure are characteristic features of the heart exposed to radiation.