Modifying normal tissue damage postirradiation. Report of a workshop sponsored by the Radiation Research Program, National Cancer Institute, Bethesda, Maryland, September 6-8, 2000

Making connections: the scientific impact and mentoring legacy of Dr. John E. Moulder

PURPOSE

The intent of this mini review is to pay homage to Dr. John E. Moulder's long and successful career in radiation science with the Medical College of Wisconsin. This effort will be done from the perspective of his history of U.S. Government funding for research into the biological pathways involved in radiation-induced normal tissue injuries, especially damage to the kidneys and heart, and pharmacological interventions. In addition, the impact of his steady guidance and leadership in the mentoring of junior scientists, and the development of meaningful collaborations with other researchers will be highlighted.

CONCLUSION

Dr. John E. Moulder's contributions to the field of radiation research, through his strong character and reputation, his consistent and dedicated commitment to his colleagues and students, and his significant scientific advances, have been critical to moving the science forward, and will not be forgotten by those who knew him personally or through publications documenting his important work.

Effect of smoking on MUC1 expression in oral epithelial dysplasia, oral cancer, and irradiated oral epithelium

OBJECTIVES

The aim of this study was to assess the MUC1 expression in the oral epithelium of normal, oral epithelial dysplasia (OED), oral squamous cell carcinoma (OSCC), and irradiated oral epithelium (IROE) and its association with smoking habits in non-smokers and smokers.

DESIGN

Oral mucosal biopsies from controls, OED, OSCC, and IROE groups were obtained and categorized based on the smoking history as non-smokers, smoker I (25 pack-years), and smoker II (>25 pack-years). Immunohistochemical staining of MUC1 using human milk fat globule 1 (HMFG 1) antibody was performed, and the MUC1 score was calculated. The relation between MUC1 expression and clinicopathological findings was examined.

RESULTS

MUC1 staining of superficial oral epithelial cells with mild MUC1 score was detected in all control samples. The MUC1 staining extended from superficial to basal cell layer of oral epithelium with the increase in MUC1 score from moderate to strong in OED, OSCC, and IROE, and the difference was significant (p < 0.004, p < 0.002 and p < 0.004, respectively) compared to controls. A positive association between smoking and MUC1 score was observed within groups (p < 0.05).

CONCLUSION

The depolarization of MUC1 protein expression is associated with smoking habits in OED and OSCC. In the IROE, the radiation causes subcellular and molecular changes, observed as altered MUC1 expression and accelerated by smoking, furthermore, complicating the oral mucosal adaptation and progress to radiation-induced lesions as a delayed effect.

Irradiation of the kidneys causes pathologic remodeling in the nontargeted heart: A role for the immune system

Cardiac disease is a frequent and significant adverse event associated with radiotherapy for cancer. Identifying the underlying mechanism responsible for radiation injury to the heart will allow interventions to be developed. In the present study, we tested if local kidney irradiation results in remodeling of the shielded, nontargeted heart. One kidney, two kidneys, or the total body of male WAG and Dahl SS rats were irradiated with 10 Gy of X-rays. Local kidney irradiation resulted in systemic hypertension, increased BUN, infiltration of T lymphocytes, natural killer cells, and macrophages into the renal cortex and medulla, and renal fibrosis. Local irradiation of kidneys in WAG rats resulted in remodeling in the nontargeted heart after 120 days, manifested by perivascular fibrosis and increased interventricular septal thickness, but was not seen in Dahl SS rats due to a high baseline level of fibrosis in the sham-irradiated animals. Genetic depletion of T cells mitigated the nephropathy after local kidney irradiation, indicating a role for the immune system in mediating this outcome. Local kidney irradiation resulted in a cascade of pro-inflammatory cytokines and low-molecular weight metabolites into the circulation associated with transmission of signals resulting in pathologic remodeling in the nontargeted heart. A new model is proposed whereby radiation-induced cardiac remodeling in susceptible animals is indirect, with lower hemi body organs such as the kidney exporting factors into the circulation that cause remodeling outside of the irradiated field in the shielded, nontargeted heart. This nontargeted effect appears to be mediated, in part, by the immune system.

A Potential Biomarker for Predicting the Risk of Radiation-Induced Fibrosis in the Lung

Biomarkers could play an essential role during triage in the aftermath of a radiological event, where exposure to radiation will be heterogeneous and complicated by concurrent trauma. Used alongside biodosimetry, biomarkers can identify victims in need of treatment for acute radiation effects, and might also provide valuable information on later developing consequences that need to be addressed as part of a treatment strategy. Indeed, because the lung is particularly sensitive to radiation and resultant late effects not only affect quality of life, but can also lead to morbidity, the risk of developing downstream pulmonary complications in exposed individuals requires assessment. In this study, analyses of changes in pulmonary and circulating content of club cell secretory protein (CCSP) and surfactant protein D (SP-D), expressed by epithelial club cells and type II pneumocytes in the lung, respectively, were used to evaluate pulmonary epithelial damage in several lung injury models. Using a combined radiation exposure model, fibrosis-susceptible C57BL/6J (C57) and alveolitis-prone C3H/HeJ (C3H) mice received 5 Gy total-body irradiation plus 2.5-10 Gy whole-lung irradiation, and lung and plasma samples were collected throughout the course of the radiation response, at time points ranging from 24 h to 26 weeks postirradiation. Radiation significantly reduced bronchiole CCSP coverage in C57 mice at 26 weeks, a response that varied in extent among animals, but correlated with the severity of fibrosis in each animal. Interestingly, plasma CCSP content was elevated in C57 mice at multiple time points preceding and during the fibrotic period; this response that was not observed in C3H mice. Circulating CCSP/SP-D ratios, calculated as an index of lung integrity, were similarly increased throughout the time course in C57, but not C3H, mice. Furthermore, when the thoracic doses were reduced to subthreshold levels for fibrosis induction (2.5 or 7.5 Gy), although the CCSP/SP-D ratio in lung homogenates demonstrated dose-responsive changes, this was not reflected in the plasma ratios at acute and late time points. Importantly, plasma CCSP/SP-D ratios also were not significantly altered in C57 mice exposed to LPS, and only transiently decreased in influenza-exposed mice, demonstrating a level of specificity for radiation-induced lung injury. These results indicate that the CCSP/SP-D ratio, measured in plasma, is sensitive to individual variation in radiation sensitivity, correlates with fibrosis development, can be detected early after exposure and is specific to radiation-induced injury. This suggests that the CCSP/SP-D ratio may be useful as a biomarker of radiation-induced pulmonary fibrosis.

The importance of the vascular endothelial barrier in the immune-inflammatory response induced by radiotherapy

Altered by ionising radiation, the vascular network is considered as a prime target to limit normal tissue damage and improve tumour control in radiotherapy (RT). Irradiation damages and/or activates endothelial cells, which then participate in the recruitment of circulating cells, especially by overexpressing cell adhesion molecules, but also by other as yet unknown mechanisms. Radiation-induced lesions are associated with infiltration of immune-inflammatory cells from the blood and/or the lymph circulation. Damaged cells from the tissues and immune-inflammatory resident cells release factors that attract cells from the circulation, leading to the restoration of tissue balance by fighting against infection, elimination of damaged cells and healing of the injured area. In normal tissues that surround the tumours, the development of an immune-inflammatory reaction in response to radiation-induced tissue injury can turn out to be chronic and deleterious for the organ concerned, potentially leading to fibrosis and/or necrosis of the irradiated area. Similarly, tumours can elicit an immune-inflammation reaction, which can be initialised and amplified by cancer therapy such as radiotherapy, although immune checkpoints often allow many cancers to be protected by inhibiting the T-cell signal. Herein, we have explored the involvement of vascular endothelium in the fate of healthy tissues and tumours undergoing radiotherapy. This review also covers current investigations that take advantage of the radiation-induced response of the vasculature to spare healthy tissue and/or target tumours better.

New perspectives on the conservative management of osteoradionecrosis of the mandible: A literature review

Over the last decades, several therapeutic options were considered in the treatment of the osteoradionecrosis (ORN) of the mandible, including supportive measures, ultrasound therapy, corticosteroids, hyperbaric oxygen, surgical resection with reconstruction, and, more recently, drugs capable of reversing the fibroatrophic process. Once established, the ORN does not spontaneously disappear and a standard treatment has not yet been defined. The clear clinical effectiveness of hyperbaric oxygen therapy (HBOT) varies according to the literature and there are some economic/logistic issues to be considered; the triplet tocopherol/pentoxifylline/clodronate demands greater evidence from randomized clinical trials and also resilience from the patient, given the long treatment duration and its possible side effects. Controversy around the ideal treatment of the initial stage ORN of the mandible persists. More rigorous randomized prospective trials are essential. The purpose of this article was to review the relevant literature on the physiopathology of ORN of the mandible and discuss the new perspectives of its conservative treatment. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1708-1716, 2016.

Cerium Oxide Nanoparticles: A Potential Medical Countermeasure to Mitigate Radiation-Induced Lung Injury in CBA/J Mice

Cerium oxide nanoparticles (CNPs) have a unique surface regenerative property and can efficiently control reactive oxygen/nitrogen species. To determine whether treatment with CNPs can mitigate the delayed effects of lung injury after acute radiation exposure, CBA/J mice were exposed to 15 Gy whole-thorax radiation. The animals were either treated with nanoparticles, CNP-18 and CNP-ME, delivered by intraperitoneal injection twice weekly for 4 weeks starting 2 h postirradiation or received radiation treatment alone. At the study's end point of 160 days, 90% of the irradiated mice treated with high-dose (10 μM) CNP-18 survived, compared to 10% of mice in the radiation-alone (P < 0.0001) and 30% in the low-dose (100 nM) CNP-18. Both low- and high-dose CNP-ME-treated irradiated mice showed increased survival rates of 40% compared to 10% in the radiation-alone group. Multiple lung functional parameters recorded by flow-ventilated whole-body plethysmography demonstrated that high-dose CNP-18 treatment had a significant radioprotective effect on lethal dose radiation-induced lung injury. Lung histology revealed a significant decrease (P < 0.0001) in structural damage and collagen deposition in mice treated with high-dose CNP-18 compared to the irradiated-alone mice. In addition, significant reductions in inflammatory response (P < 0.01) and vascular damage (P < 0.01) were observed in the high-dose CNP-18-treated group compared to irradiated-alone mice. Together, the findings from this preclinical efficacy study clearly demonstrate that CNPs have both clinically and histologically significant mitigating and protective effects on lethal dose radiation-induced lung injury.

Quiescence does not affect p53 and stress response by irradiation in human lung fibroblasts

Cells in many organs exist in both proliferating and quiescent states. Proliferating cells are more radio-sensitive, DNA damage pathways including p53 pathway are activated to undergo either G1/S or G2/M arrest to avoid entering S and M phase with DNA damage. On the other hand, quiescent cells are already arrested in G0, therefore there may be fundamental difference of irradiation response between proliferating and quiescent cells, and this difference may affect their radiosensitivity. To understand these differences, proliferating and quiescent human normal lung fibroblasts were exposed to 0.10-1 Gy of γ-radiation. The response of key proteins involved in the cell cycle, cell death, and metabolism as well as histone H2AX phosphorylation were examined. Interestingly, p53 and p53 phosphorylation (Ser-15), as well as the cyclin-dependent kinase inhibitors p21 and p27, were induced similarly in both proliferating and quiescent cells after irradiation. Furthermore, the p53 protein half-life, and expression of cyclin A, cyclin E, proliferating cell nuclear antigen (PCNA), Bax, or cytochrome c expression as well as histone H2AX phosphorylation were comparable after irradiation in both phases of cells. The effect of radioprotection by a glycogen synthase kinase 3β inhibitor on p53 pathway was also similar between proliferating and quiescent cells. Our results showed that quiescence does not affect irradiation response of key proteins involved in stress and DNA damage at least in normal fibroblasts, providing a better understanding of the radiation response in quiescent cells, which is crucial for tissue repair and regeneration.

Serum and plasma proteomics and its possible use as detector and predictor of radiation diseases

All tissues can be damaged by ionizing radiation. Early biomarkers of radiation injury are critical for triage, treatment and follow-up of large numbers of people exposed to ionizing radiation after terrorist attacks or radiological accident, and for prediction of normal tissue toxicity before, during and after a treatment by radiotherapy. The comparative proteomic approach is a promising and powerful tool for the discovery of new radiation biomarkers. In association with multivariate statistics, proteomics enables measurement of the level of hundreds or thousands of proteins at the same time and identifies set of proteins that can discriminate between different groups of individuals. Human serum and plasma are the preferred samples for the study of normal and disease-associated proteins. Extreme complexity, extensive dynamic range, genetic and physiological variations, protein modifications and incompleteness of sampling by two-dimensional electrophoresis and mass spectrometry represent key challenges to reproducible, high-resolution, and high-throughput analyses of serum and plasma proteomes. The future of radiation research will possibly lie in molecular networks that link genome, transcriptome, proteome and metabolome variations to radiation pathophysiology and serve as sensors of radiation disease. This chapter reviews recent advances in proteome analysis of serum and plasma as well as its applications to radiation biology and radiation biomarker discovery for both radiation exposure and radiation tissue toxicity.

[Dropped Head Syndrome after whiplash injury in a patient treated for a Hodgkin's lymphoma by mantle field radiotherapy]

The authors report a case of Dropped Head Syndrome with an unusually rapid onset after an accident in a patient with a history of Hodgkin's lymphoma cured by chemotherapy and mantle field radiotherapy and compare this case to the rare published cases of chronic Dropped Head Syndrome occurring after this type of treatment. A 56-year-old man was treated at the age 36 years for supra-diaphragmatic Hodgkin's lymphoma by chemotherapy and mantle field radiotherapy according to a standard technique and standard doses (40Gy, 20 fractions, 27 days). Seventeen years after the end of treatment, he experienced a violent whiplash injury, rapidly followed by a Dropped Head Syndrome, similar to the cases of chronic Dropped Head Syndrome already described in the context of Hodgkin's lymphoma (permanent flexion of the head, only reduced in the supine position). Physical and neurophysiological examination, electromyogram, and magnetic resonance imaging confirmed the diagnosis of Dropped Head Syndrome. Very few treatment options are available for the major disability related to Dropped Head Syndrome. This type of subacute onset of Dropped Head Syndrome has not been previously described. The good results of radiation therapy after chemotherapy allow a dose reduction to 30Gy in the involved regions. This, together with recent progress in treatment planning, should allow eradication of these complications.

Radiation-induced toxicity in cancer patients with low plasma fibronectin levels

The present study was carried out to evaluate the levels of plasma fibronectin (Fn) in cancer patients undergoing radiation therapy (RT) in correlation with outcomes in terms of radiation toxicity. A total of 26 patients with lung and gastrointestinal (GI) cancer, treated with RT were enrolled in this study. Plasma Fn levels were determined before and following a course of RT. The Radiation Therapy Oncology Group (RTOG) criteria were used to determine the grade of RT toxicity. Statistical analysis utilised the nonparametric Mann–Whitney U-test as well as bivariate linear regression. Pre-RT Fn levels were significantly higher in cancer patients without toxicity (median ± SE) (485.0 ± 87 μg/ml) as compared with the levels of plasma Fn in patients with grade I–II RTOG acute toxicity (354.0 ± 74 μg/ml, p = 0.01). No significant difference in Fn levels was found in patients with grade I toxicity compared with patients with grade II toxicity. In addition, low baseline Fn levels (148 and 299 μg/ml) were observed in two lung cancer patients who developed symptomatic pneumonitis during the first 2 months after RT. These preliminary results suggest that low baseline Fn may have potential as a predictive marker for development of RT-induced toxicity.

Radiation-induced liver fibrosis is mitigated by gene therapy inhibiting transforming growth factor-β signaling in the rat

PURPOSE

We determined whether anti-transforming growth factor-β (TGF-β) intervention could halt the progression of established radiation-induced liver fibrosis (RILF).

METHODS AND MATERIALS

A replication-defective adenoviral vector expressing the extracellular portion of human TβRII and the Fc portion of immunoglobulin G fusion protein (AdTβRIIFc) was produced. The entire rat liver was exposed to 30 Gy irradiation to generate a RILF model (RILFM). Then, RILFM animals were treated with AdTβRIIFc (1 × 10(11) plaque-forming units [PFU] of TβRII), control virus (1 × 10(11) PFU of AdGFP), or saline. Delayed radiation liver injury was assessed by histology and immunohistochemistry. Chronic oxidative stress damage, hepatic stellate cell activation, and hepatocyte regeneration were also analyzed.

RESULTS

In rats infected with AdTβRIIFc, fibrosis was significantly improved compared with rats treated with AdGFP or saline, as assessed by histology, hydroxyproline content, and serum level of hyaluronic acid. Compared with AdGFP rats, AdTβRIIFc-treated rats exhibited decreased oxidative stress damage and hepatic stellate cell activation and preserved liver function.

CONCLUSIONS

Our results demonstrate that TGF-β plays a critical role in the progression of liver fibrosis and suggest that anti-TGF-β intervention is feasible and ameliorates established liver fibrosis. In addition, chronic oxidative stress may be involved in the progression of RILF.

Differential effects of radiation and age on diffusion tensor imaging in rats

Greater than 50% of adults and approximately 100% of children who survive >6 months after fractionated partial or whole-brain radiotherapy develop cognitive impairments. Noninvasive methods are needed for detecting and tracking the radiation-induced brain injury associated with these impairments. Using magnetic resonance imaging, we sought to detect structural changes associated with brain injury in our rodent model of fractionated whole-brain irradiation (fWBI) induced cognitive impairment and to compare those changes with alterations that occur during the aging process. Middle aged rats were given a clinically relevant dose of fWBI (40 Gy: two 5 Gy fractions/week for 4 weeks) and scanned approximately 1 year post-irradiation to obtain whole-brain T2 and diffusion tensor images (DTI); control groups of sham-irradiated age-matched and young rats were also scanned. No gross structural changes were evident in the T2 structural images, and no detectable fWBI-induced DTI changes in fractional anisotropy (FA) were found in heavily myelinated white matter (corpus callosum, cingulum, and deep cortical white matter). However, significant fWBI-induced variability in FA distribution was present in the superficial parietal cortex due to an fWBI-induced decline in FA in the more anterior slices through parietal cortex. Young rats had significantly lower FA values relative to both groups of older rats, but only within the corpus callosum. These findings suggest that targets of the fWBI-induced change in this model may be the less myelinated or unmyelinated axons, extracellular matrix, or synaptic fields rather than heavily myelinated tracts.

Early alterations in cytokine expression in adult compared to developing lung in mice after radiation exposure

To assess early changes in the lung after low-dose radiation exposure that may serve as targets for mitigation of lung injury in the aftermath of a terrorist event, we analyzed cytokine expression after irradiation. Adult mice were studied after whole-lung or total-body irradiation. Mouse pups of different ages were also investigated after total-body irradiation. mRNA abundance was analyzed in tissue and plasma, and pathological changes were assessed. In lung tissue, dose-related changes were seen in IL1B, IL1R2 and CXCR2 mRNA expression at 1 and 6 h after irradiation, concurrent with increases in plasma protein levels of KC/CXCL1 and IL6. However, in the pups, changes in IL1 abundance were not detected until 28 days of age, coincident with the end of postnatal lung growth, although apoptosis was detected at all ages. In conclusion, although cytokines were expressed after low doses of radiation, their role in the progression of tissue response is yet to be determined. They may be candidates for use in marker-based biodosimetry. However, the lack of cytokine induction in early life suggests that different end points (and mitigating treatments) may be required for children.

Single-dose gamma-irradiation induces up-regulation of chemokine gene expression and recruitment of granulocytes into the portal area but not into other regions of rat hepatic tissue

Liver damage is a serious clinical complication of gamma-irradiation. We therefore exposed rats to single-dose gamma-irradiation (25 Gy) that was focused on the liver. Three to six hours after irradiation, an increased number of neutrophils (but not mononuclear phagocytes) was observed by immunohistochemistry to be attached to portal vessels between and around the portal (myo)fibroblasts (smooth muscle actin and Thy-1(+) cells). MCP-1/CCL2 staining was also detected in the portal vessel walls, including some cells of the portal area. CC-chemokine (MCP-1/CCL2 and MCP-3/CCL7) and CXC-chemokine (KC/CXCL1, MIP-2/CXCL2, and LIX/CXCL5) gene expression was significantly induced in total RNA from irradiated livers. In laser capture microdissected samples, an early (1 to 3 hours) up-regulation of CCL2, CXCL1, CXCL8, and CXCR2 gene expression was detected in the portal area but not in the parenchyma; with the exception of CXCL1 gene expression. In addition, treatment with an antibody against MCP-1/CCL2 before irradiation led to an increase in gene expression of interferon-gamma and IP-10/CXCL10 in liver tissue without influencing the recruitment of granulocytes. Indeed, the CCL2, CXCL1, CXCL2, and CXCL5 genes were strongly expressed and further up-regulated in liver (myo)fibroblasts after irradiation (8 Gy). Taken together, these results suggest that gamma-irradiation of the liver induces a transient accumulation of granulocytes within the portal area and that (myo)fibroblasts of the portal vessels may be one of the major sources of the chemokines involved in neutrophil recruitment. Moreover, inhibition of more than one chemokine (eg, CXCL1 and CXCL8) may be necessary to reduce leukocytes recruitment.

Role of PPARs in Radiation-Induced Brain Injury

Whole-brain irradiation (WBI) represents the primary mode of treatment for brain metastases; about 200 000 patients receive WBI each year in the USA. Up to 50% of adult and 100% of pediatric brain cancer patients who survive >6 months post-WBI will suffer from a progressive, cognitive impairment. At present, there are no proven long-term treatments or preventive strategies for this significant radiation-induced late effect. Recent studies suggest that the pathogenesis of radiation-induced brain injury involves WBI-mediated increases in oxidative stress and/or inflammatory responses in the brain. Therefore, anti-inflammatory strategies can be employed to modulate radiation-induced brain injury. Peroxisomal proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the steroid/thyroid hormone nuclear receptor superfamily. Although traditionally known to play a role in metabolism, increasing evidence suggests a role for PPARs in regulating the response to inflammation and oxidative injury. PPAR agonists have been shown to cross the blood-brain barrier and confer neuroprotection in animal models of CNS disorders such as stroke, multiple sclerosis and Parkinson's disease. However, the role of PPARs in radiation-induced brain injury is unclear. In this manuscript, we review the current knowledge and the emerging insights about the role of PPARs in modulating radiation-induced brain injury.

Repopulation in radiation oncology: perspectives of clinical research

Cellular repopulation is one of the most important biological determinants of the clinical outcome of fractionated radiation therapy. A number of randomized controlled trials of altered dose-fractionation have been conducted in patients with squamous cell carcinoma of the head and neck (HNSCC) and the main biological lessons from these are summarised. Data for other tumour histologies are relatively sparse. Further progress in radiotherapy for HNSCC is unlikely to result from altered fractionation alone, but a number of novel strategies for overcoming or exploiting repopulation are being researched. In the next 5 years, the top priorities for clinical and translational research in this field should be the development of clinically applicable predictive assays, functional imaging as an aid to optimize the dose distribution, optimization of combined modality therapies and novel biological strategies specifically targeting tumour cell proliferation.

Inhibition of transforming growth factor-beta, hypoxia-inducible factor-1alpha and vascular endothelial growth factor reduced late rectal injury induced by irradiation

Tumor hypoxia and angiogenesis associated with malignant progression have been studied widely. The efficacy of angiogenesis inhibition combined with radiotherapy has been demonstrated in cancer treatment. Here, we studied the effect of hypoxia and angiogenesis inhibition on radiation-induced late rectal injury. The rectum of C57BL/6N mice was irradiated locally with a single dose of 25 Gy. Radiation-induced histological changes were examined at 90 days after irradiation by hematoxylin-eosin (H.E.) staining and azan staining. Pimonidazole was administered and its distribution was assayed by immunohistochemistry staining. Expression of transforming growth factor beta1 (TGF-beta1), hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) was assessed on the fibrotic region using real-time PCR and immunohistochemistry. In addition, the effects of TGF-beta, VEGF and HIF-1alpha on radiation-induced injury were investigated by the administration of neutralizing antibody of TGF-beta, antibody of VEGF or YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole) which was developed as an agent for inhibiting HIF-1 expression after irradiation respectively. Fibrosis and uptake of pimonidazole were found 90 days after irradiation. The expression of TGF-beta1, HIF-1alpha and VEGF significantly increased with the formation of fibrosis induced by irradiation compared with unirradiated controls. In addition, treatment of neutralizing antibody of TGF-beta, antibody of VEGF or YC-1 reduced the development of radiation-induced injury. Our results suggested that radiation-induced hypoxia may play an important role in late rectal injury. Although the inhibition of HIF-1alpha and VEGF reduced the radiation induced late injury, the precise mechanism is still unclear.

Oxidative damage pathways in relation to normal tissue injury

Given the increasing population of long-term cancer survivors, the need to mitigate or treat late effects has emerged as a primary area of radiation biology research. Once thought to be irreversible, radiation-induced late effects are now viewed as dynamic multicellular interactions between multiple cell types within a particular program that can be modulated. The molecular, cellular and biochemical pathways responsible for radiation-induced late morbidity remain ill-defined. This review provides data in support of the hypothesis that these late effects are driven, in part, by a chronic oxidative stress. Irradiating late responding normal tissues leads to chronic increases in reactive oxygen/reactive nitrogen oxide species that serve as intracellular signaling species to alter cell function/phenotype, resulting in chronic inflammation, organ dysfunction, and ultimate fibrosis and/or necrosis. Furthermore, we hypothesize that the effectiveness of renin-angiotensin system blockers in preventing or mitigating the severity of radiation-induced late effects reflects, in part, inhibition of reactive oxygen species generation and the resultant chronic oxidative stress. These findings provide a robust rationale for anti-inflammatory-based interventional therapies in the treatment of late normal tissue injury.

Future strategies for mitigation and treatment of chronic radiation-induced normal tissue injury

Until the mid-1990s, radiation-induced normal-tissue injury was generally assumed to be solely caused by the delayed mitotic death of parenchymal or vascular cells, and these injuries were held to be progressive and untreatable. From this assumption, it followed that postirradiation interventions would be unlikely to reduce either the incidence or the severity of radiation-induced normal tissue injury. It is now clear that parenchymal and vascular cells are active participants in the response to radiation injury, an observation that allows for the possibility of pharmacologic mitigation and/or treatment of these injuries. Mitigation or treatment of chronic radiation injuries has now been experimentally shown in multiple organ systems (eg, lung, kidney, and brain), with different pharmacologic agents (eg, angiotensin-converting enzyme inhibitors, pentoxifylline, and superoxide dismutase mimetics) and with seemingly different mechanisms (eg, suppression of the renin-angiotensin system and suppression of chronic oxidative stress). Unfortunately, the mechanistic basis for most of the experimental successes has not been established, and assessment of the utility of these agents for clinical use has been slow. Clinical development of pharmacologic approaches to mitigation or treatment of chronic radiation injuries could lead to significant improvement in survival and quality of life for radiotherapy patients and for victims of radiation accidents or nuclear terrorism.

Long-term administration of a small molecular weight catalytic metalloporphyrin antioxidant, AEOL 10150, protects lungs from radiation-induced injury

PURPOSE

To determine whether administration of a catalytic antioxidant, Mn(III) tetrakis(N,N'-diethylimidazolium-2-yl) porphyrin, AEOL 10150, with superoxide dismutase (SOD) mimetic properties, reduces the severity of radiation-induced injury to the lung from single-dose irradiation (RT) of 28 Gy.

METHODS AND MATERIALS

Rats were randomly divided into four different dose groups (0, 1, 10, and 30 mg/kg/day of AEOL 10150), receiving either short-term (1 week) or long-term (10 weeks) drug administration via osmotic pumps. Rats received single-dose irradiation (RT) of 28 Gy to the right hemithorax. Breathing rates, body weights, blood samples, histopathology, and immunohistochemistry were used to assess lung damage.

RESULTS

There was no significant difference in any of the study endpoints between the irradiated controls and the three groups receiving RT and short-term administration of AEOL 10150. For the long-term administration, functional determinants of lung damage 20 weeks postradiation were significantly worse for RT + phosphate-buffered saline (PBS) and RT + 1 mg/kg/day of AEOL 10150 as compared with the irradiated groups treated with higher doses of AEOL 10150 (10 or 30 mg/kg/day). Lung histology at 20 weeks revealed a significant decrease in structural damage and collagen deposition in rats receiving 10 or 30 mg/kg/day after radiation in comparison to the RT + PBS and 1 mg/kg/day groups. Immunohistochemistry demonstrated a significant reduction in macrophage accumulation, oxidative stress, and hypoxia in rats receiving AEOL 10150 (10 or 30 mg/kg/day) after lung irradiation compared with the RT + PBS and 1 mg/kg/day groups.

CONCLUSIONS

The chronic administration of a novel catalytic antioxidant, AEOL 10150, demonstrates a significant protective effect from radiation-induced lung injury. AEOL 10150 has its primary impact on the cascade of events after irradiation, and adding the drug before irradiation and its short-term administration have no significant additional benefits.

Anti-TNFA (TNF-alpha) treatment abrogates radiation-induced changes in vacular density and tissue oxygenation

Ionizing radiation significantly alters the structure and function of microvasculature, which regulates delivery of oxygen to brain tissue. Previous experimental and modeling studies have shown that tissue oxygenation patterns are significantly different in irradiated normal tissue compared to age-matched controls, and the differences are apparent as early as 3 days postirradiation. However, oxygen delivery to irradiated tissue recovers within 6 months postirradiation. Changes in perfusion and oxygenation were studied in a bilaterally (both cerebral hemispheres) and unilaterally (only one hemisphere) irradiated mouse brain model at 6 and 24 h as well as 3, 7, 30, 60 and 120 days postirradiation. The results indicate that significant changes in the number of perfused vessels (as measured by fluorescent DiOC(7) staining) and anatomical vessels (as indicated by CD31 immunohistochemical staining) and tissue oxygenation (by immunohistochemical detection of a fluorescently conjugated monoclonal antibody to EF5) are most pronounced at 3 days postirradiation, while a degree of recovery is observed at later times. However, in the unilaterally irradiated animals, both irradiated and unirradiated (out-of-field) cerebral hemispheres showed similarly significant changes in oxygenation and/or perfusion compared to unirradiated controls. Anti-TNFA treatment inhibited radiation-induced local as well as abscopal effects in the brain tissue.

Radiation-induced peripheral neuropathies: Etiopathogenesis, risk factors, differential diagnostics, symptoms and treatment

The success of radiation oncology has lead to longer patient survival. This provides a greater opportunity for radiation injuries of the peripheral nerves to develop. Peripheral neuropathy in cancer patients may result from either tumor recurrence or as a consequence of radiation therapy. Distinguishing between radiation injury and cancer disease recurrence as a cause of nerve dysfunction may be difficult. In this article the etiopathogenesis of radiation-induced peripheral neuropathies has been discussed as well as main risk factors, symptoms and method of treatment.

Effects of fractionated radiation on the brain vasculature in a murine model: Blood–brain barrier permeability, astrocyte proliferation, and ultrastructural changes

PURPOSE

Radiation therapy of CNS tumors damages the blood-brain barrier (BBB) and normal brain tissue. Our aims were to characterize the short- and long-term effects of fractionated radiotherapy (FRT) on cerebral microvasculature in mice and to investigate the mechanism of change in BBB permeability in mice.

METHODS AND MATERIALS

Intravital microscopy and a cranial window technique were used to measure BBB permeability to fluorescein isothiocyanate (FITC)-dextran and leukocyte endothelial interactions before and after cranial irradiation. Daily doses of 2 Gy were delivered 5 days/week (total, 40 Gy). We immunostained the molecules to detect the expression of glial fibrillary acidic protein and to demonstrate astrocyte activity in brain parenchyma. To relate the permeability changes to endothelial ultrastructural changes, we used electron microscopy.

RESULTS

Blood-brain barrier permeability did not increase significantly until 90 days after FRT, at which point it increased continuously until 180 days post-FRT. The number of adherent leukocytes did not increase during the study. The number of astrocytes in the cerebral cortex increased significantly; vesicular activity in endothelial cells increased beginning 90 days after irradiation, and most tight junctions stayed intact, although some were shorter and less dense at 120 and 180 days.

CONCLUSIONS

The cellular and microvasculature response of the brain to FRT is mediated through astrogliosis and ultrastructural changes, accompanied by an increase in BBB permeability. The response to FRT is delayed as compared with single-dose irradiation treatment, and does not involve leukocyte adhesion. However, FRT induces an increase in the BBB permeability, as in the case of single-dose irradiation.

Distinct effects of ionizing radiation on in vivo murine kidney and brain normal tissue gene expression

PURPOSE

There is a growing awareness that radiation-induced normal tissue injury in late-responding organs, such as the brain, kidney, and lung, involves complex and dynamic responses between multiple cell types that not only lead to targeted cell death but also acute and chronic alterations in cell function. The specific genes involved in the acute and chronic responses of these late-responding normal tissues remain ill defined; understanding these changes is critical to understanding the mechanism of organ damage. As such, the aim of the present study was to identify candidate genes involved in the development of radiation injury in the murine kidney and brain using microarray analysis.

EXPERIMENTAL DESIGN

A multimodality experimental approach combined with a comprehensive expression analysis was done to determine changes in normal murine tissue gene expression at 8 and 24 hours after irradiation.

RESULTS

A comparison of the gene expression patterns in normal mouse kidney and brain was strikingly different. This observation was surprising because it has been long assumed that the changes in irradiation-induced gene expression in normal tissues are preprogrammed genetic changes that are not affected by tissue-specific origin.

CONCLUSIONS

This study shows the potential of microarray analysis to identify gene expression changes in irradiated normal tissue cells and suggests how normal cells respond to the damaging effects of ionizing radiation is complex and markedly different in cells of differing origin.

Preventing or reducing late side effects of radiation therapy: radiobiology meets molecular pathology

Radiation therapy has curative or palliative potential in roughly half of all incident solid tumours, and offers organ and function preservation in most cases. Unfortunately, early and late toxicity limits the deliverable intensity of radiotherapy, and might affect the long-term health-related quality of life of the patient. Recent progress in molecular pathology and normal-tissue radiobiology has improved the mechanistic understanding of late normal-tissue effects and shifted the focus from initial-damage induction to damage recognition and tissue remodelling. This stimulates research into new pharmacological strategies for preventing or reducing the side effects of radiation therapy.

The vitamin-like dietary supplement para-aminobenzoic acid enhances the antitumor activity of ionizing radiation

PURPOSE

To determine whether para-aminobenzoic acid (PABA) alters the sensitivity of tumor cells to ionizing radiation in vitro and in vivo.

METHODS AND MATERIALS

Cellular proliferation was assessed by WST-1 assays. The effects of PABA and radiation on tumor growth were examined with chick embryo and murine models. Real-time reverse transcriptase-polymerase chain reaction and Western blotting were used to quantify p21CIP1 and CDC25A levels.

RESULTS

Para-aminobenzoic acid enhanced (by 50%) the growth inhibitory activity of radiation on B16F10 cells, whereas it had no effect on melanocytes. Para-aminobenzoic acid enhanced (50-80%) the antitumor activity of radiation on B16F10 and 4T1 tumors in vivo. The combination of PABA and radiation therapy increased tumor apoptosis. Treatment of tumor cells with PABA increased expression of CDC25A and decreased levels of p21CIP1.

CONCLUSIONS

Our findings suggest that PABA might represent a compound capable of enhancing the antitumor activity of ionizing radiation by a mechanism involving altered expression of proteins known to regulate cell cycle arrest.

Adverse event reporting and developments in radiation biology after normal tissue injury: International Atomic Energy Agency consultation

PURPOSE

Recent research has enhanced our understanding of radiation injury at the molecular-cellular and tissue levels; significant strides have occurred in standardization of adverse event reporting in clinical trials. In response, the International Atomic Energy Agency, through its Division of Human Health and its section for Applied Radiation Biology and Radiotherapy, organized a consultation meeting in Atlanta (October 2, 2004) to discuss developments in radiobiology, normal tissue reactions, and adverse event reporting.

METHODS AND MATERIALS

Representatives from cooperative groups of African Radiation Oncology Group, Curriculo Radioterapeutica Ibero Latino Americana, European Organization for Research and Treatment of Cancer, National Cancer Institute of Canada Clinical Trials Group, Radiation Therapy Oncology Group, and Trans-Tasman Radiation Oncology Group held the meeting discussion.

RESULTS

Representatives of major radiotherapy groups/organizations and prominent leaders in radiotherapy discussed current understanding of normal tissue radiobiologic effects, the design and implementation of future clinical and translational projects for normal tissue injury, and the standardization of adverse-event reporting worldwide.

CONCLUSIONS

The consensus was to adopt NCI comprehensive adverse event reporting terminology and grading system (CTCAE v3.0) as the new standard for all cooperative group trials. Future plans included the implementation of coordinated research projects focusing on normal tissue biomarkers and data collection methods.

Carnosine may reduce lung injury caused by radiation therapy

Ionising radiation is known one of the most effective tools in the therapy of cancer but in many thoracic cancers, the total prescribed dose of radiation that can be safely administered to the target volume is limited by the risk of complications arising in the normal lung tissue. One of the major reasons for cellular injury after radiation is the formation of reactive oxygen species (ROS). Radiation pneumonitis is an acute phase side-effect which generally subsides after a few weeks and is followed by a chronic phase characterized by inflammation and fibrosis, that can develop months or years after irradiation. Carnosine is a dipeptide composed by the amino acids beta-histidine and l-alanine. The exact biological role of carnosine is not totally understood, but several studies have demonstrated that it possesses strong and specific antioxidant properties, protects against radiation damage,and promotes wound healing. The antioxidant mechanism of carnosine is attributed to its chelating effect against metal ions, superoxide dismutase (SOD)-like activity, ROS and free radicals scavenging ability . Either its antioxidant or anti-inflammatuar properties, we propose that carnosine ameliorates irradiation-induced lung injury. Thus, supplementing cancer patients to whom applied radiation therapy with carnosine, may provide an alleviation of the symptoms due to radiation-induced lung injury. This issue warrants further studies.

Kinetics of response to long-term treatment combining pentoxifylline and tocopherol in patients with superficial radiation-induced fibrosis

PURPOSE

Significant regression of radiation (RT) -induced fibrosis (RIF) has been achieved after treatment combining pentoxifylline (PTX) and alpha-tocopherol (vitE). In this study, we focus on the maximum response, how long it takes to achieve response, and changes after treatment discontinuation.

PATIENTS AND METHODS

Measurable superficial RIF was assessed in patients treated by RT for breast cancer in a long-treatment (24 to 48 months) PTX-vitE (LPE) group of 37 patients (47 RIFs) and in a short-treatment (6 to 12 months) PTX-vitE (SPE) group of seven patients (eight RIFs). Between April 1995 and April 2000, women were treated with a daily combination of PTX (800 mg) and VitE (1,000 IU).

RESULTS

Combined PTX-vitE was continuously effective and resulted in exponential RIF surface area regression (-46% for LPE and -68% for SPE at 6 months, -58% for LPE and -69% for SPE at 12 months, -63% for LPE and -62% for SPE at 18 months, and -68% for LPE at 24 and 36 months). The mean estimated maximal treatment effect was 68% RIF surface area regression. The mean time to this effect was 24 months and was shorter (16 months) in more recent RIF (< 6 years since RT) than in older RIF (28 months; P = .0003). Symptom severity (Subjective Objective Medical Management and Analytic Evaluation score) was halved in both groups. After treatment discontinuation, mean RIF surface area at 1 year had increased by +40% in the SPE group (rebound) and +8.5% in the LPE group.

CONCLUSION

Under combined PTX-vitE treatment, RIF regression was exponential, with a two-thirds maximum response after a mean of 2 years. There was a risk of a rebound effect if treatment was too short. Long treatment (>/= 3 years) is recommended in patients with severe RIF.

Modulation of DNA Damage by Pentoxifylline and α-Tocopherol in Skin Fibroblasts Exposed to Gamma Rays

Previous in vivo studies showed the combination pentoxifylline (PTX) and alpha-tocopherol was highly efficient in reducing late radiation-induced skin damage. The present work aimed at investigating the molecular and cellular mechanisms involved in the effects of this combination. Primary cultures of confluent dermal fibroblasts were gamma-irradiated in the presence of PTX and trolox (Tx), the water-soluble analogue of alpha-tocopherol. Drugs were added either before or after radiation exposure and were maintained over time. Their antioxidant capacity and their effect on radiation-induced ROS production was assessed together with cell viability and clonogenicity. DNA damage formation was assessed by the alkaline comet assay and by the micronucleus (MN) test. Cell cycle distribution was also determined. The combination of PTX/ Tx was shown to reduce both immediate and late ROS formation observed in cells after irradiation. Surprisingly, decrease in DNA strand breaks measured by the comet assay was observed any time drugs were added. In addition, the micronucleus test revealed that for cells irradiated with 10 Gy, a late significant increase in MN formation occurred. The combination of PTX/Tx was shown to be antioxidant and to decrease radiation-induced ROS production. The observed effects on DNA damage at any time the drugs were added suggest that PTX/Tx could interfere with the DNA repair process.

Recent progress in defining mechanisms and potential targets for prevention of normal tissue injury after radiation therapy

The ability to optimize treatments for cancer on the basis of relative risks for normal tissue injury has important implications in oncology, because higher doses of radiation might, in some diseases, improve both local control and survival. To achieve this goal, a thorough understanding of the molecular mechanisms responsible for radiation-induced toxicity will be essential. Recent research has demonstrated that ionizing radiation triggers a series of genetic and molecular events, which might lead to chronic persistent alterations in the microenvironment and an aberrant wound-healing response. Disrupted epithelial-stromal cell communication might also be important. With the application of a better understanding of fundamental biology to clinical practice, new approaches to treating and preventing normal tissue injury can focus on correcting these disturbed molecular processes.

Mechanisms and Potential Targets for Prevention and Treatment of Normal Tissue Injury After Radiation Therapy

The ability to optimize treatment for cancer based on individual risk assessment for normal tissue injury has important implications in oncology because more aggressive therapy may improve outcome in the treatment of advanced non-small cell lung cancer. To achieve this goal, a thorough understanding of the molecular mechanisms responsible for radiation-induced toxicity will be essential. Recent research has shown that ionizing radiation triggers a series of genetic and molecular events that may lead to chronic, persistent alterations in the microenvironment, producing an aberrant wound healing response. Disrupted epithelial-stromal cell communication may also contribute to impaired wound healing. As a result of an improved understanding of these fundamental biologic responses to radiation, new approaches to the treatment and prevention of normal tissue injury will focus on correcting these disturbed molecular processes. Herein, we will summarize recent developments in this field, with an emphasis on the lung.

The radiation-induced fibroatrophic process: therapeutic perspective via the antioxidant pathway

The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a matrix densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a 'gravitational effect' exerted by the couple ROS (reactive oxygen species)--fibroblasts, and partly mediated by TGF-beta1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline-tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline-tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis. Mechanistic studies are always necessary to improve understanding of the RIF process and the antifibrotic drug action.

Priority list of research areas for radiological nuclear threat countermeasures

To help the nation prepare for the possibility of a terrorist attack using radiological and nuclear devices, the Office of Science and Technology Policy and the Homeland Security Council established an interagency working group. The working group deliberated on the research needs for radiological/ nuclear threat countermeasures and identified and prioritized 18 areas for further attention. The highest priorities were given to research on (1) radioprotectors for use prior to exposure; (2) therapeutic agents for postexposure treatment; (3) antimicrobial therapy for infections associated with radiation exposure; (4) cytokines and growth factors; (5) mechanisms of radiation injury at the molecular, cellular, tissue and organism levels; and (6) automation of biodosimetric assays. High priority was given to (1) developing biomarkers for biodosimetry; (2) enhancing training in the radiation sciences; (3) exploring the consequences of combined injury; (4) establishing a repository of information regarding investigational countermeasures; and (5) following the health of an exposed population to better prepare for subsequent events. The research areas that the committee felt required the attention of the radiation research community are described in this report in an effort to inform this community about the needs of the nation and to encourage researchers to address these critical issues.

Effects of Hypoxia on Radiation-Responsive Stress-Activated Protein Kinase, p53, and Caspase 3 Signals in TK6 Human Lymphoblastoid Cells

Despite significant evidence of a role of hypoxia in cellular resistance to ionizing radiation–induced toxicity, the underlying molecular mechanisms remain unclear. This study focused on the influence of hypoxia on radiation-induced signals in TK6 human lymphoblastoid cells. Hypoxic (&lt;10 ppm oxygen) and aerobic cells were exposed to equilethal doses of ionizing radiation, radiation dose ratio, 3:1 (hypoxia:air). Hypoxia alone or radiation treatment under aerobic or hypoxic conditions led to increased levels of phospho-p44/42 mitogen-activated protein kinase. Levels of phospho-p38 mitogen-activated protein kinase did not change as a result of either hypoxia or irradiation. Hypoxia alone had no effect on expression of phospho-stress-activated protein kinase (SAPK), wild-type p53, or cleaved caspase 3. Irradiation under aerobic conditions resulted in an increase in the phospho-SAPK signal, whereas hypoxia suppressed the irradiation-induced increase in the level of phospho-SAPK. Both hypoxic and aerobic cells showed increases in p53 levels in response to radiation. Hypoxia blocked radiation-induced cleavage of caspase 3 and poly-ADP-ribose polymerase. Irradiation of aerobic and hypoxic TK6 cells using 6 and 18 Gy, respectively, resulted in a similar and significant increase in fraction of apoptotic cells within 24 hours postirradiation. In contrast, basal levels of apoptosis were observed at 24 hours postirradiation in aerobic and hypoxic NH32 cells, a p53 null derivative of TK6 cells. These results suggest that radiation-induced apoptosis under hypoxia occurs independent of phospho-SAPK and caspase 3, and the p53 response is an obligatory apoptotic signal in TK6 cells.

Chronic oxidative stress and radiation-induced late normal tissue injury: a review

PURPOSE

It is proposed that the development and progression of radiation-induced late effects are driven, in part, by chronic oxidative stress. This mini-review presents data to support this hypothesis and provides the foundation for antioxidant-based interventional approaches directed at modulating late normal tissue injury.

CONCLUSIONS

Although a causal link between chronic oxidative stress and radiation-induced late normal tissue injury remains to be established, a growing body of evidence appears to support the hypothesis that chronic oxidative stress might serve to drive the progression of radiation-induced late effects. The similarity between chronic tissue injury, chronic inflammation and fibrosis observed in a variety of disease states, including radiation late effects, is provocative and offers the opportunity to apply antioxidant-based therapies to mitigate and/or treat late radiation-induced normal tissue injury.

Use of the Leksell Gamma Knife for localized small field lens irradiation in rodents

For most basic radiobiological research applications involving irradiation of small animals, it is difficult to achieve the same high precision dose distribution realized with human radiotherapy. The precision for irradiations performed with standard radiotherapy equipment is +/-2 mm in each dimension, and is adequate for most human treatment applications. For small animals such as rodents, whose organs and tissue structures may be an order of magnitude smaller than those of humans, the corresponding precision required is closer to +/-0.2 mm, if comparisons or extrapolations are to be made to human data. The Leksell Gamma Knife is a high precision radiosurgery irradiator, with precision in each dimension not exceeding 0.5 mm, and overall precision of 0.7 mm. It has recently been utilized to treat ocular melanoma and induce targeted lesions in the brains of small animals. This paper describes the dosimetry and a technique for performing irradiation of a single rat eye and lens with the Gamma Knife while allowing the contralateral eye and lens of the same rat to serve as the "control". The dosimetry was performed with a phantom in vitro utilizing a pinpoint ion chamber and thermoluminescent dosimeters, and verified by Monte Carlo simulations. We found that the contralateral eye received less than 5% of the administered dose for a 15 Gy exposure to the targeted eye. In addition, after 15 Gy irradiation 15 out of 16 animals developed cataracts in the irradiated target eyes, while 0 out of 16 contralateral eyes developed cataracts over a 6-month period of observation. Experiments at 5 and 10 Gy also confirmed the lack of cataractogenesis in the contralateral eye. Our results validate the use of the Gamma Knife for cataract studies in rodents, and confirmed the precision and utility of the instrument as a small animal irradiator for translational radiobiology experiments.

Post-irradiation approaches to treatment of radiation injuries in the context of radiological terrorism and radiation accidents: a review

PURPOSE

Events of the recent past have focused attention on the possibility of radiological (nuclear) terrorism and on the implications of such terrorist threats for radiation accident preparedness. This review discusses recent advances in the knowledge about how radiation injuries from such events might be treated pharmacologically, and the practical barriers to clinical utilization of these approaches.

CONCLUSIONS

A wide range of pharmacological approaches are being developed in the laboratory that could greatly expand the ability to treat acute and chronic radiation injuries. However, there are currently a variety of practical and legal barriers that would prevent the actual clinical use of most of the approaches. There are also the potential weaknesses in most of the current programmes for dealing with the consequences of radiation accidents or nuclear terrorism, including the absence of widespread radiation biodosimetry capabilities and the resulting inability to triage. If a major radiation accident or terrorist event occurs, the lack of biodosimetry and treatment capabilities will be compounded by widespread public fear of 'radiation'.

International Conference on Translational Research ICTR 2003 Conference Summary: marshalling resources in a complex time

The knowledge, tools, and environment for the practice of radiation oncology are changing rapidly. The National Cancer Institute has articulated the need for a balanced portfolio, including the interrelated components of discovery, development, and delivery. Underpinning practice is the emerging knowledge from molecular, cellular, and tumor biology that is the engine of discovery. The use of high-throughput technologies to analyze biochemical and molecular profiles will ultimately enable the individualization of cancer treatment requiring the appropriate integration of radiation with a range of systemic therapies, including chemotherapy, biologic therapy, and immunotherapy. Technological advances in treatment delivery using photons, brachytherapy, particle therapy, radioisotopes, and other forms of energy require an improved ability to localize the tumor and critical subregions and to ensure necessary tissue immobilization and/or real-time target adjustment. Functional imaging is helping to define tumor characteristics and response to treatment. The development of appropriate radiation oncology treatment requires a wide range of expertise, a multimodality approach, and multi-institutional collaboration to provide improved and cost-effective outcome. The delivery of appropriate cancer care to those who need it requires biology and technology but also reaching the underserved populations worldwide. ICTR 2003 demonstrated substantial progress in translational radiation oncology. Faced with financial constraints for research and patient care, the broad field of radiation oncology must continually examine and balance its research and development portfolio and invest in its future leaders to enable it be an important contributor to the future of cancer care.

Radiation-induced changes in skin type I and III collagen synthesis during and after conventionally fractionated radiotherapy

BACKGROUND AND PURPOSE

To measure local changes of collagen metabolism in irradiated breast skin and systemic changes in serum during and after radiotherapy and correlate these changes with skin thickness, erythema and palpable subcutaneous induration.

PATIENTS AND METHODS

Aminoterminal propeptides of type I and type III procollagens (PINP and PIIINP, respectively) were measured from skin suction blister fluid (SBF) in 21 breast cancer patients with breast conserving surgery and conventionally fractionated radiotherapy (RT) to a total dose of 50Gy. Suction blisters were induced in the operated and contralateral breast skin before RT, at 2.5 weeks, at the end of RT, and at 1, 4, 7, 12 and 24 months post-treatment. Blood samples for serum were taken simultaneously with SBF induction. Skin thickness of the suction blister sites was measured with a high-frequency ultrasound device. The investigated sites were scored for erythema at the end of RT and palpable subcutaneous induration at 1 and 2 years post-treatment.

RESULTS

In SBF the mean levels of PINP and PIIINP of the operated breast before RT were about 3-4 times higher than those in the contralateral breast due to the operation-related wound healing. The synthesis of PINP in irradiated breast after RT increased 7.7-fold (P < 0.001) 4 months post-irradiation. The PIIINP synthesis was at maximum at 1 month post-irradiation (P < 0.001). Both synthesis stayed elevated until 2 years. The level of PINP correlated significantly with the palpable skin induration at 1 and 2 years (P = 0.038 and P = 0.003, respectively). The skin thickness of the irradiated breast was highest at 4 months post-treatment and significantly elevated until 1 year. The skin thickness correlated with the PINP level until 7 months and with PIIINP between 4 and 18 months. The PINP/PIIINP ratio reached the maximum at 4 months and stayed elevated until 2 years. No change in mean serum level of PINP was found during or after RT.

CONCLUSIONS

We demonstrated a maximum and elevated levels for PINP and PIIINP skin collagen metabolism determined from SBF during the 2 years' follow-up. Elevated levels of PINP and PIIINP correlated with the thickening of the skin and subcutaneous induration but not with erythema.

Education and training for radiation scientists: radiation research program and American Society of Therapeutic Radiology and Oncology Workshop, Bethesda, Maryland, May 12-14, 2003

Current and potential shortfalls in the number of radiation scientists stand in sharp contrast to the emerging scientific opportunities and the need for new knowledge to address issues of cancer survivorship and radiological and nuclear terrorism. In response to these challenges, workshops organized by the Radiation Research Program (RRP), National Cancer Institute (NCI) (Radiat. Res. 157, 204-223, 2002; Radiat. Res. 159, 812-834, 2003), and National Institute of Allergy and Infectious Diseases (NIAID) (Nature, 421, 787, 2003) have engaged experts from a range of federal agencies, academia and industry. This workshop, Education and Training for Radiation Scientists, addressed the need to establish a sustainable pool of expertise and talent for a wide range of activities and careers related to radiation biology, oncology and epidemiology. Although fundamental radiation chemistry and physics are also critical to radiation sciences, this workshop did not address workforce needs in these areas. The recommendations include: (1) Establish a National Council of Radiation Sciences to develop a strategy for increasing the number of radiation scientists. The strategy includes NIH training grants, interagency cooperation, interinstitutional collaboration among universities, and active involvement of all stakeholders. (2) Create new and expanded training programs with sustained funding. These may take the form of regional Centers of Excellence for Radiation Sciences. (3) Continue and broaden educational efforts of the American Society for Therapeutic Radiology and Oncology (ASTRO), the American Association for Cancer Research (AACR), the Radiological Society of North America (RSNA), and the Radiation Research Society (RRS). (4) Foster education and training in the radiation sciences for the range of career opportunities including radiation oncology, radiation biology, radiation epidemiology, radiation safety, health/government policy, and industrial research. (5) Educate other scientists and the general public on the quantitative, basic, molecular, translational and applied aspects of radiation sciences.