In-vitro analysis of venous blood taken from rats irradiated by 300 and 5,000 J/m2 of UV showed no effect on metabolism and, therefore, energy and recovery systems of erythrocytes. Concentrations of 2,3-diphosphoglycerate and reduced glutathione were increased after irradiation by 5,000 J/m2. UV-irradiation at 10,000 J/m2 decreased adenosine triphosphate and phospholipids in blood and impaired the functional stability of erythrocyte membranes. Recovery of the membrane structure in 24 hrs. after irradiation suggests extended photochemical processes in cells and is consistent with the literary data about indirect effects of plasma proteins on the red cell function.

The hypoxic and euoxic radiation response for Chinese hamster lung and A549 human lung carcinoma cells was obtained under conditions where their nonprotein thiols, consisting primarily of glutathione (GSH), were depleted by different mechanisms. The GSH conjugating reagent diethylmaleate (DEM) was compared to DL-buthionine-S,R-sulfoximine (BSO), an inhibitor of glutathionine biosynthesis. Each reagent depleted cellular GSH to less than 5% of control values. A 2-hr exposure to 0.5 mM DEM or a 4- or 24-hr exposure to BSO at 10 or 1 mM, respectively, depleted cellular GSH to less than 5% of control values. Both agents sensitized cells irradiated under air or hypoxic conditions. When GSH levels are lowered to less than 5% by both agents, hypoxic DEM-treated cells exhibited slightly greater X-ray sensitization than hypoxic BSO-treated cells. The D0's for hypoxic survival curves were as follows: control, 4.87 Gy; DEM, 3.22 Gy; and BSO, 4.30 Gy for the V79 cells and 5.00 Gy versus 4.02 Gy for BSO-treated A549 cells. The D0's for aerobic V79 cells were 1.70 Gy versus 1.13 Gy, DEM, and 1.43 Gy for BSO-treated cells. The D0's for the aerobic A549 were 1.70 and 1.20 for BSO-treated cells. The aerobic and anoxic sensitization of the cells results in the OER's of 2.8 and 3.0 for the DEM- and BSO-treated cells compared to 2.9 for the V79 control A549. BSO-treated cells showed an OER of 3.3 versus 3 for the control. Our results suggest that GSH depletion by either BSO or DEM sensitizes aerobic cells to radiation but does not appreciably alter the OER.

A pulse radiolysis study of glutathione in aqueous solution at pH 5.5 containing N2O/O2 mixtures at various ratios indicates that oxygen rapidly adds to the thiyl glutathione radical yielding a transient absorption, with a maximum at 540 nm, whose characteristics appear to be compatible with assignment to the GSOO. radical. The reaction (Formula: see text) appears to be an equilibrium whose kinetic constants have been estimated (kf = 2.0 X 10(9) dm3 mol-1, kb = 6.2 X 10(5) s-1). Evidence for electron transfer from ascorbate to the GSOO. radical has been obtained and the respective rate constant has been determined to be 1.75 +/- 0.15 X 10(8) dm3 mol-1 s-1.

In this series of experiments the protective action of reduced glutathion due to ionizing radiation has been studied. In the experimental group 18 guinea pigs were exposed to successive radiations of 150 rad 3 or 4 days apart. Total dose given amounted to 750 rad which is the LD50 for guinea pigs. Blood samples were taken 30 min after each exposure. The control series were sham radiated but otherwise treated identically. The cells of the removed blood samples were separated by centrifugation and were subjected to the reduced glutathion stability test. GSSGR, GPer, and LDH enzyme activities were also measured of which the latter served as a marked enzyme. It was found that LDH did not show any alteration after radiation. The reduced glutathion stability test showed a consistent but minor reduction (P greater than 0.05), in the experimental group. GSSGR enzyme activity on the other hand was reduced significantly (from 176.48 +/- 11.32 to 41.34 +/- 1.17 IU/ml of packed erythrocytes, P less than 0.001) in the same group. GPer activity showed a consistent but minor elevation during the early phase of the experimental group. It was later increased significantly beginning after 600 rad total radiation on the fourth session (P less than 0.050).

We studied the thermal and photolytic decomposition of two S-nitrosothiols, S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylpenicillamine (SNAP), in water or propanol solutions. A "concentration clamp"(relatively constant concentration of NO as a function of time) could be implemented in a closed volume by varying the pH, concentration of nitrovasodilator and intensity of the light source. Depending on the conditions, the light either stimulated NO release or sharply decreased NO concentration in the test solutions. Changes in the absorption spectra of GSNO solutions were monitored as a function of light exposure. Generation of superoxide as a product of a photolytic decomposition reaction of S-nitrosothiols and further oxidation of NO is the most likely mechanism for light suppression of NO concentration.

Rats were exposed to gamma radiation from a 60Co source, receiving 0.25 Gy at weekly intervals. During 2 d before each irradiation, the animals received daily intragastric doses of 26 mg pantothenol or 15 mg beta-carotene per kg body weight. One hour after the third irradiation session, the animals were killed and their livers were analyzed. In animals not supplied with pantothenol, the irradiation resulted in a significant decrease of total liver lipids and a 50% decrease in phospholipids. Liver cholesterol was decreased by about 20%. Irradiation produced lipid peroxidation as expressed by doubling of the amounts of conjugated dienes and ketone dienes and of thiobarbituric acid reactive compounds. The amount of CoA in liver was decreased by 24% and that of reduced glutathione by 40%. The NAD+/NADH ratio was increased by 60% and the activity of NADP-dependent malate dehydrogenase (decarboxylating) was decreased by 26%. The amount of pantothenic acid and its derivatives (expressed as pantolactone-generating compounds) in blood decreased by about 80%. In rats to which pantothenol was administered, the content of pantothenic acid in blood was tripled compared to nonirradiated (control) rats, and all the biochemical parameters measured in liver were the same as in nonirradiated animals.

Glutathione is present in both the reduced and oxidized form in the cornea, aqueous humor, ocular lens and retina. In these tissues it serves a variety of functions including maintaining normal tissue hydration (in the cornea) detoxifying peroxides and electrophilic compounds via enzymatic pathways and acting as a free radical scavenger to protect against photoinduced damage. In the ocular lens, glutathione levels decrease with aging and cataract formation. Recent evidence which may account in part for this phenomenon suggests that glutathione is altered when subjected to UV radiation in the presence of H2O2. Analyses employing fluorescence, phosphorescence, UV absorption and proton mode NMR spectroscopy demonstrate that UV exposure does alter both the reduced and oxidized forms of glutathione, producing the same final products. Moreover, while H2O2 speeds up the process, it is not essential to the reaction.

The objective of this study was to examine the potential radioprotective properties of pharmacological doses of melatonin on corpus cavernosum and bladder tissues of whole-body irradiated (IR) rats. A total of 32 male Sprague-Dawley rats were exposed to irradiation performed with a LINAC which produced 6 MV photons at a focus 100 cm distant from the skin. Under ketamine anesthesia, each rat received a single whole-body dose of 800 cGy. Immediately before and after IR, rats were treated with either saline or melatonin (20 and 10 mg/kg, i.p.) and decapitated at 12 hr after exposure to irradiation. Another group of rats was followed for 72 hr after IR, where melatonin injections were repeated once daily. Tissue levels of malondialdehyde (MDA), an index of lipid peroxidation, and glutathione (GSH), a key antioxidant, were estimated in corpus cavernosum and urinary bladder. Tissues were also examined microscopically. The results demonstrate that both 12 and 72 hr following IR, tissue levels of MDA were elevated (P < 0.001), while GSH levels were reduced (P < 0.01) in both tissues. On the other hand, melatonin reversed these changes significantly (P < 0.05-0.01), concomitant with the improvement in histological appearances. Our results show that whole-body irradiation causes oxidative damage in the tissues of the genitourinary system. As melatonin administration reversed oxidative organ injury, as assessed by biochemical and histopathological findings, it is suggested that supplementing cancer patients with adjuvant therapy of melatonin may have some benefit for successful radiotherapy.

PURPOSE: To see if changes in tumor/blood glutathione (GSH) levels after one fraction of radiotherapy can be correlated with the treatment response in patients with carcinoma of the uterine cervix. METHODS AND MATERIALS: The study was done on 45 patients with squamous cell carcinoma of the uterine cervix, FIGO Stages IIB (17 patients) and IIIB (28 patients). Stage IIB patients received 35 Gy of cobalt-60 external radiotherapy (RT) in 16 fractions over 4 weeks with a concurrent high-dose-rate intracavitary dose of 8.5 Gy to point A once a week. Stage IIIB patients were given 45 Gy of RT in 20 fractions over 5 weeks, followed by two doses of intracavitary therapy once a week. Blood and tumor samples were collected before and after one dose of RT and GSH was estimated. Tumor response was assessed clinically at 1 month after treatment. RESULTS: Glutathione levels in both blood and tumor showed a significant decrease after one fraction of RT, but the degree of decrease varied among patients. There was a good correlation between the extent of GSH decrease and the tumor response. All patients who had complete response (CR)(seven Stage IIB and eight Stage IIIB) showed > or =70% decrease in both tumor and blood GSH, while those who had <50% regression (NR)(five Stage IIB and 13 Stage IIIB) showed <50% decrease in GSH. The partial responders recorded an intermediate level (50-70%) of depletion in blood and tumor GSH. CONCLUSIONS: The results indicate that the changes in tumor/blood GSH levels after one fraction of RT could serve as an index of tumor response to therapy and may help in identifying radioresistant tumors, at least in the case of cervix carcinoma.

BACKGROUND AND PURPOSE: Both infrared and low-power laser have been applied to improve circulation, wound repair, and pain control. Infrared and low-power laser therapies have the potential for stimulating enzyme activities which might contribute to increased glutathione (GSH) concentration and provide protection against oxidative damage. This study investigated cell viability, and GSH and its related enzyme activities in rat hepatocytes after irradiation. METHODS: Hepatocytes were isolated from 8-week-old male Sprague-Dawley rats and the cultures were divided into infrared, laser, and control groups. The cells were treated with infrared and low-power laser at a distance of 35 cm for 20 minutes. The cell morphology, lactate dehydrogenase (LDH) leakage, lipid peroxidation, GSH concentration, GSH peroxidase, GSH reductase (GRd), and GSH S-transferase activities were measured after irradiation. RESULTS: The morphology and LDH leakage of hepatocytes in the irradiation groups did not differ significantly from those of the control group. After infrared irradiation, a significant decrease in thiobarbituric acid-reactive substances and an increase in GSH concentration were found after 48 hours of incubation compared to the control group (p < 0.05). Furthermore, laser irradiation resulted in a significant increase in GRd activity after 48 hours of incubation compared to the control group (p < 0.05). A 48-hour incubation period produced greater GRd activity in all groups compared to a 24-hour period (p < 0.05). CONCLUSIONS: Irradiation did not damage rat hepatocytes in this study. Infrared was shown to stimulate GSH production, while laser irradiation increased GRd activity.