Influence of whole-body gamma-irradiation upon rat erythrocyte: lipid peroxidation and osmotic fragility

Effects of Very Low Dose Fast Neutrons on Cell Membrane And Secondary Protein Structure in Rat Erythrocytes

The effects of ionizing radiation on biological cells have been reported in several literatures. Most of them were mainly concerned with doses greater than 0.01 Gy and were also concerned with gamma rays. On the other hand, the studies on very low dose fast neutrons (VLDFN) are rare. In this study, we have investigated the effects of VLDFN on cell membrane and protein secondary structure of rat erythrocytes. Twelve female Wistar rats were irradiated with neutrons of total dose 0.009 Gy (²⁴¹Am-Be, 0.2 mGy/h) and twelve others were used as control. Blood samples were taken at the 0, 4th, 8th, and 12th days postirradiation. Fourier transform infrared (FTIR) spectra of rat erythrocytes were recorded. Second derivative and curve fitting were used to analysis FTIR spectra. Hierarchical cluster analysis (HCA) was used to classify group spectra. The second derivative and curve fitting of FTIR spectra revealed that the most significant alterations in the cell membrane and protein secondary structure upon neutron irradiation were detected after 4 days postirradiation. The increase in membrane polarity, phospholipids chain length, packing, and unsaturation were noticed from the corresponding measured FTIR area ratios. This may be due to the membrane lipid peroxidation. The observed band shift in the CH₂ stretching bands toward the lower frequencies may be associated with the decrease in membrane fluidity. The curve fitting of the amide I revealed an increase in the percentage area of α-helix opposing a decrease in the β-structure protein secondary structure, which may be attributed to protein denaturation. The results provide detailed insights into the VLDFN effects on erythrocytes. VLDFN can cause an oxidative stress to the irradiated erythrocytes, which appears clearly after 4 days postirradiation.

The effect of radiotherapy and chemotherapy on osmotic fragility of red blood cells and plasma levels of malondialdehyde in patients with breast cancer

BACKGROUND

Gamma radiation effects on the erythrocyte membrane from three different functional parts, lipid bilayer, cytoskeleton and protein components. When the red cell membrane is exposed to radiation, it loses its integrity and hemoglobin leaks out. In addition, irradiation leads to lipid peroxidation and the products of this process, leading to hemolysis. The aim of the present study was to measure osmotic fragility (OF) of red blood cells and malondialdehyde (MDA) levels as a marker of oxidative injury in breast cancer patients treated with radiation and chemotherapy.

MATERIALS AND METHODS

The OF test was performed using different concentrations of a salt solution. The measurement of MDA was done with chemical methods.(11) The sampling was taken during three stages of treatment: first sample was taken before starting chemotherapy, the second sample was taken before radiation therapy and the third sample was taken after radiotherapy.

RESULTS

No statistically significant differences between levels of MDA in these three stages of treatment were observed. However, the comparison of mean levels of MDA showed an increase after radiotherapy. The OF rate did not show significant difference (P > 0.05) during the stages of treatment.

CONCLUSION

In a standard treatment program of radiotherapy and chemotherapy lipid peroxidation level and OF do not significantly increase.

The effects of exogenous glutathione on reduced glutathione level, glutathione peroxidase and glutathione reductase activities of rats with different ages and gender after whole-body Γ-irradiation

Age-and gender-related changes on reduced glutathione (GSH) level, glutathione peroxidase (GPx) and glutathione reductase (GR) activities in the liver of rat exposed to different dose of whole-body g-ray irradiation were determined. In addition, the effect of administration of exogenous GSH on endogenous GSH levels, GPx and GR activities was investigated. For this aim, male and female rats aged 1 and 5 moths were divided into two groups as g-ray and g-ray+GSH. Both groups were again divided into four groups as irradiated with 2, 4, 6 and 8 Gy doses. GSH level and GPx activity did not change with age while GR activity was decreased with age. Gender-dependent changes in GPx and GR activities were observed, but GSH values were not affect by sex. GSH levels, GPx and GR activities were not observed dose-associated changes of g-irradiation. GSH level and GPx activity in the 8Gy group were increased by GSH. GR activities of old male rats were found to be increased by glutathione in the 6 and 8Gy groups. These results indicate that radiation and administration of exogenous GSH affect gender-and age-dependent GSH level, GPx and GR activities in the rats.

Action of bis(betachloroethyl)sulphide (BCES) on human epidermis reconstituted in culture: Morphological alterations and biochemical depletion of glutathione

Human keratinocyte cultures were treated with bis(betachloroethyl)sulphide (BCES), an alkylating and vesicant agent. At concentrations of 5 x 10(-4) to 5 x 10(-3)m, spontaneous detachment of the epithelium from the culture plate was observed, reproducing in vitro the cutaneous vesication observed in vivo. Progressive cellular alterations were shown with increasing concentrations of BCES (5 x 10(-5) to 5 x 10(-3)m). At low concentrations (5 x 10(-5)m), lesions of the nucleus, a significant target for BCES, were observed, along with lesions in the cytoplasmic organelles. An acute, dose-dependent depletion of cellular glutathione was observed, which occurred within 1 hr of treatment. Mechlorethamine, an analogue of BCES, induced at equivalent doses the same glutathione depletion and similar spontaneous detachment in vitro. We suggest that BCES, in addition to its genetic effects, acts by direct metabolic toxicity and induces glutathione depletion by direct conjugation. The lesions obtained in vitro reproduced those observed in vivo. Human keratinocyte cultures can be proposed as a good model for the study of the mechanisms of action of BCES.

Photoprotective effect of sesamol on UVB-radiation induced oxidative stress in human blood lymphocytes in vitro

Normal lymphocytes are highly sensitive to the damaging effect of radiation and undergo cell death. In the present study, the photoprotective effect of sesamol, a constituent of sesame oil, has been examined in the UVB-(280-320nm) irradiated human blood lymphocytes. Lymphocytes pretreated with increasing concentrations of sesamol (1, 5 and 10μg/ml) for 30min, were irradiated and lipid peroxidation and antioxidant defense were examined. UVB-irradiated lymphocytes exhibited increased levels of lipid peroxidation and disturbances in antioxidant defense. Sesamol pretreatment resulted in significant reduction in lipid peroxidation marker, thiobarbituric acid reactive substances (TBARS). Further, antioxidants like reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) increased, in a dose-dependent manner, in sesamol pretreated and UVB-irradiated lymphocytes. The maximum dose of sesamol (10μg/ml) normalized the UVB induced lipid peroxidation, indicating the photoprotective effect of sesamol in irradiated lymphocytes.

Radioprotective effect of sesamol on γ-radiation induced DNA damage, lipid peroxidation and antioxidants levels in cultured human lymphocytes

Sesamol pretreated (1, 5 and 10 microg/ml) lymphocytes were exposed to different doses of gamma-radiation, i.e., 1, 2 and 4 Gray (Gy) and the cellular changes were estimated by using cytokinesis blocked micronucleus assay (MN), dicentric aberration (DC), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Radiation significantly increased MN, DC frequencies, TBARS levels and decreased GSH and antioxidant enzyme levels in a dose dependent manner. The highest damage to lymphocytes was observed at 4 Gy irradiation. On the other hand, sesamol pretreatment significantly decreased MN, DC frequencies, TBARS levels and increased GSH levels and SOD, CAT and GPx activities in a concentration dependent manner. At 1 Gy irradiation all concentrations of sesamol (1, 5 and 10 microg/ml) significantly protects the lymphocytes from radiation damage. At 2 Gy irradiation 5 and 10 microg/ml of sesamol shows significant radioprotection. Since the highest damage was observed at 4 Gy irradiation both 1 and 5 microg/ml of sesamol pretreatment were not sufficient to protect the lymphocytes from radiation damage but 10 microg/ml of sesamol significantly (p<0.05) protects the lymphocytes from radiation effect. Thus, sesamol pretreatment gives significant protection to cultured human lymphocytes against gamma-radiation induced cellular damage. The possible mechanism involved in the radioprotective influence of sesamol is discussed.

The Use of ELISA to Monitor Amplified Hemolysis by the Combined Action of Osmotic Stress and Radiation: Potential Applications

A new assay has been developed to study the osmotic fragility of red blood cells (RBCs) and the involvement of oxygen-derived free radicals and other oxidant species in causing human red blood cell hemolysis. The amount of hemoglobin released into the supernatant, which is a measure of human red blood cell hemolysis, is monitored using an ELISA reader. This ELISA-based osmotic fragility test compared well with the established osmotic fragility test, with the added advantage of significantly reduced time and the requirement of only 60 mul of blood. This small amount of blood was collected fresh by finger puncture and was immediately diluted 50 times with PBS, thus eliminating the use of anticoagulants and the subsequent washings. Since exposure of RBCs to 400 Gy gamma radiation caused less than 5% hemolysis 24 h after irradiation, the RBC hemolysis induced by gamma radiation was amplified by irradiating the cell in hypotonic saline. The method was validated by examining the protective effect of Trolox, an analog of vitamin E and reduced glutathione (GSH), a well-known radioprotector, against human RBC hemolysis caused by the combined action of radiation and osmotic stress. Trolox, a known membrane stabilizer and an antioxidant, and GSH offered significant protection. This new method, which is simple and requires significantly less time and fewer RBCs, may offer the ability to study the effects of antioxidants and membrane stabilizers on human red blood cell hemolysis induced by radiation and oxidative stress and assess the osmotic fragility of erythrocytes.

The cell membrane as a biosensor of oxidative stress induced by radiation exposure: a multiparameter investigation

The role of biological membranes as a target in biological radiation damage remains unclear. The present study investigates how the biochemical and biophysical properties of a simple biological model, i.e. human erythrocyte membranes, are altered after exposure to relatively low doses of (60)Co gamma rays. Lipid peroxidation increased in the hours after radiation exposure, based on measurements of MDA and on the lipid peroxidation index after parinaric acid incorporation. Protein carbonyl content also increased rapidly after radiation exposure. An imbalance between the radiation-mediated oxidative damages and the antioxidant capacity of the erythrocytes was observed in the hours after radiation exposure. Antioxidant enzyme activities, mainly catalase and glutathione peroxidase, were found to decrease after irradiation. The development of a radiation-induced oxidative stress probably explains the reorganization of the fatty acid pattern 72 h after radiation exposure. The phosphatidylethanolamine (PE) fatty acids of the (n-3) and (n-6) series decreased, while the PE saturated fatty acid content increased. All these modifications may be involved in the variation of the biophysical properties of the membranes that we noted after radiation exposure. Specifically, we observed that the lipid compartment of the membrane became more fluid while the lipid-protein membrane interface became more rigid. Taken together, these findings reinforce our understanding that the cell membrane is a significant biological target of radiation. Thus the role of the biological membrane in the expression and course of cell damage after radiation exposure must be considered.

Comparison of hypoxic cell radiosensitizers, KIN-804, KIN-844, KIN-806 and TX-1877, on brain and liver metabolizing capacities in mice bearing Ehrlich ascites carcinoma

The biochemical effects of the 2-nitroimidazole hypoxic cell radiosensitizers KIN-804, KIN-806, and their analogues KIN-844 and TX-1877 on brain acetylcholinesterase (AChE) and hepatic free radical scavenging systems, such as reduced glutathione (GSH) and glucose-6-phosphate dehydrogenase (G-6-PDH) levels, and hepatic antioxidants, such as superoxide dismutase (SOD) and catalase, were evaluated in Ehrlich ascites carcinoma (EAC)-bearing Swiss albino mice. The assay of brain AChE revealed nonsignificant changes with all drugs examined. To evaluate the hepatic metabolic capacity, groups of mice were divided into control, EAC-inoculated, 10-Gy local gamma-irradiated, and KIN-804, KIN-844, KIN-806, or TX-1877 (50 mg/kg body weight, i.p.) groups, and gamma-irradiation was combined with each drug. EAC inoculation markedly suppressed GSH, G-6-PDH, SOD, and catalase levels. On the other hand, treatment with gamma-irradiation significantly enhanced them. The treatment of EAC-bearing mice with each drug alone in the absence of gamma-irradiation revealed that KIN-806 and its derivative TX-1877 showed antitumor activity through their significant recovery of GSH and SOD levels, respectively, in the EAC-bearing mice group. Similarly, the combined treatment of EAC-bearing mice with gamma-irradiation with each of the drugs tested showed that KIN-806 and TX-1877 significantly increased GSH and SOD, and to a lesser extent G-6-PDH and catalase levels. On the other hand, KIN-804 and KIN-844 had only a nonsignificant effect on all parameters examined. In conclusion, these data reveal that the administration of KIN-806 and TX-1877 with or without subsequent gamma-irradiation, resulted in significant recovery of GSH and SOD activities that were inhibited by EAC inoculation.