Radiation chronic

Studies from our laboratoiy (Challa et al., 1998) have recently shown that GTP treatment amehorated UVB-induced oxidative burst as measured by H2O2 and myeloperoxidase production. GTP treatment to mice also partially blocked UVB-induced infiltration of leukocytes and appeared to inhibit lL-10 production in skin, as shown by immunohistochemistiy. In this study, GTP apphcation to mice prior to UVB irradiation was found to result in complete reversal of UVB-induced inhibition of contact hypersensitivity, but showed only partial reversal of induction of tolerance to 2,4-dinitrofluorobenzene. These data suggested that green tea, and the polyphenols present therein, might be useM against inflammatory dermatoses and immunosuppression caused by solar radiation in humans. The validation of these studies to human population exposed to low levels of UV radiation chronically through solar radiation is an area for further study. 

A number of studies have shown that vitamins moderate the induction of chromosomal aberrations by radiation. Vitamins C and E given orally to mice either 2 h before, immediately after, or 2 h after 1 Gy (100 rad) of y-ray TBI significantly reduce the frequencies of micronuclei and chromosomal aberrations in BM cells. Vitamin E is the more effective (95). Administration of vitamins C and E within 5 min of irradiation is as effective as pretreatment. Protection by vitamin C has also been shown in humans. Whereas chronic treatment of rats using vitamin C (100 or 300 mg/(kg/d)) for six months prior to TBI protects against chromosomal aberrations, vitamin E is not radioprotective in this setting (96). 

The reader should note tliat since many risk assessments have been conducted on the basis of fatal effects, there are also uncertainties on precisely what constitutes a fatal dose of thennal radiation, blast effect, or a toxic chemical. Where it is desired to estimate injuries as well as fatalities, tlie consequence calculation can be repeated using lower intensities of exposure leading to injury rather titan dcatli. In addition, if the adverse healtli effect (e.g. associated with a chemical release) is delayed, the cause may not be obvious. Tliis applies to both chronic and acute emissions and exposures. 

Bissett DL, Chatterjee R, Hannon DP (1990) Photoprotective effect of superoxide-scavenging antioxidants against ultraviolet radiation-induced chronic skin damage in the hairless mouse. Photodermatol Photoimmunol Photomed 7 56-62... 

Positive for sharp right upper quadrant abdominal pain radiating to the back, nausea, vomiting, recent unintentional weight loss (although patient is still obese) and chronic cough negative for chest pain or shortness of breath... 

There is clear evidence linking defects of the immune system to the development of NMSC. For example, it is observed that patients receiving chronic immunosuppressant therapy for organ transplantation have a 50% risk of developing SCC within 20 years of transplantation, and 30% of these cancers are highly aggressive.21 Additionally, patients with human immunodeficiency virus (HIV) infection are predisposed to melanoma.18 Data also support the idea that UV radiation... 

Miettinen JK, Mussalo H, Hakanen M, et al. 1980. Distribution of plutonium and americium in human and animal tissues after chronic exposures. In International Radiation Protection Society, ed. Radiation protection A systemic approach to safety Proceedings of the 5th congress of the International Radiation Protection Society, Jerusalem, March 1980. New York Pergamon Press, 1049-1052. 

Diarrheal conditions may decrease drug absorption as a result of reduced intestinal residence time. The absorption of several drugs was decreased in response to lactose- and saline-induced diarrhea [145]. Digoxin absorption from tablets was impaired in one subject who developed chronic diarrhea as a result of x-ray treatment [146]. Abdominal radiation or the underlying disease has been shown to reduce digoxin and clorazepate absorption [147]. A dosage form that provides rapid drug dissolution (e.g., solution) may partially resolve this problem. 

Individual dose assessment requires radiological data on all external and internal sources contributing to occupational and non-occupational radiation exposure (Steinhausler and Pohl, 1983). This is of particular importance in the case of low level Rn-d exposure, as man is always exposed to Rn-d at varying levels through all stages of life, e.g. at school, home or work. The resulting lifetime risk from this chronic exposure is influenced by the latent... 

Kilibarda, M., B. Marcovic, and D. Panov, Studies of Chromosome Aberrations in Persons Chronically Exposed to Radiation (X, Ra 226, and Rn 222), Studies Biophysics 6 179-186 (1968). 

Radiation causes dominant lethal mutations in the medaka (Oryzias latipes) (Shima and Shimada 1991). Mosquitofish (Gambusia spp.) from radionuclide-contaminated ponds in South Carolina differed from conspecifics in reference ponds, as judged by the frequency of DNA markers, and this is consistent with the hypothesis that these DNA markers may originate from genetic elements that provide a selective advantage in contaminated habitats (Theodorakis et al. 1998). Ionizing radiation at low-level chronic exposure reportedly has no deleterious genetic effects on aquatic populations because exposure is compensated by density-dependent responses in fecundity (IAEA 1976). However, this needs verification. 

The incidence of ovarian tumors in mice, guinea pigs, and rabbits increased after 3 years of chronic irradiation at doses as low as 1.1 mGy daily (Lorenz et al. 1954). Unlike other tumors, the induction of ovarian tumors depended on a minimum total dose and seemed to be independent of a daily dose (Lorenz et al. 1954). Radiation-induced neoplastic transformation of hamster cells may be associated initially with changes in expression of the genes modifying cytoskeletal elements (Woloschak et al. 1990b). 

The most common osteoporosis-related fractures involve the vertebrae, proximal femur, and distal radius (wrist or Colies fracture). Two-thirds of patients with vertebral fractures are asymptomatic the remainder present with moderate to severe back pain that radiates down a leg after a new vertebral fracture. The pain usually subsides significantly after 2 to 4 weeks, but residual, chronic, low-back pain may persist. Multiple vertebral fractures decrease height and sometimes curve the spine (kyphosis or lordosis) with or without significant back pain. 

Chronic complications of radiation therapy include proctitis, diarrhea, cystitis, enteritis, impotence, urethral stricture, and incontinence. 

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