Recurrent decreases of erythrocyte electrophoretic mobility in rats exposed to 1.0 R whole-body X-radiation

Circulating erythrocytes from rats were examined up to 30 weeks post whole-body exposures of 1.0 R for alterations in the expression of net negative surface charge as measured by whole-cell microelectrophoresis in saline sorbitol. Erythrocyte electrophoretic mobility was determined in an apparatus composed of a horizontal transilluminated cylindrical chamber, equipped with a reversible, blacked platinum electrode, immersed in a water bath maintained at 25.0±0.1°C (Rank Brothers). In two separate experiments, recurrent decreases in the expression of net negative surface charge occurred at 10, 17, and 30 weeks post-irradiation. At these times distribution analyses of recorded erythrocyte electrophoretic mobility (EEPM) values revealed a skewing of the normally distributed EEPM population values to lower EEPM. Total sialic acid content released from hydrolyzed erythrocyte membrane preparations revealed no significant differences between erythrocytes from sham and irradiated animals. In vivo post-irradiation labeling of erythrocytes with diisopropyl-[³²P] phosphorofluoridate at 4 and 33 weeks (separate experiments) indicated only a minor abbreviated erythrocyte life span at 33 weeks. Therefore, effects from low dose (1.0 R) whole-body irradiation would appear to include a recurrent defect in the expression of the net negative surface charge.     

Study of lymphocyte and erythrocyte electrophoretic mobility by laser doppler spectroscopy

Laser Doppler spectroscopy, a technique that permits rapid and precise measurement of the distribution of electrophoretic mobilities in a population of suspended particles, has been applied to blood cells by using suspending medium of low ionic strength made isoosmotic with sucrose. Data on the mobilities of erythrocytes and lymphocytes, and the pH dependencies of these mobilities, appear in good agreement with those determined by classical procedures.     

Xanthine oxidase activity of thymocytes exposed to x-radiation

Xanthine oxidase activity in thymocytes was studied at different time intervals after X-irradiation with doses of 0.5, 2 and 8 Gy. It was shown that 3 h and later after irradiation, dehydrogenase activity of the enzyme was converted into oxidase one. In the case of arresting the proteolysis by the effect of low doses (up to 0.5 Gy) and at early times the possibility of conversion of the enzyme into the dehydrogenase form was retained. The hyperactivity of the oxidase form of xanthine oxidase was probably a factor of expressing the proteolysis response and cell lysis.     

Developmental changes of erythrocyte catalase activity in rats exposed to acute hypoxia

The erythrocytes represent an important source of antioxidant capacity of the blood. Catalase (EC 1.11.1.6.) is one of the enzymatic components of their antioxidant defense system. The objective of this study was to follow erythrocyte catalase (CAT) in 7-, 15-, 21-, 35-, 60- and 90-day-old Wistar rats of both sexes in normoxia and after exposure to intensive acute hypobaric hypoxia. During the development CAT activity increases in both sexes, but the rise was usually higher in females. Hypobaric hypoxia increased CAT activity in all studied age groups of both sexes. However, higher CAT activity in females was less affected by hypoxia than the lower activity in males. This was true for nearly all age groups studied. It can be concluded that both ontogenetic aspects and sex differences play a major role in establishing the activity of CAT, which is an important part of the antioxidant defense of the organism.     

Endothelin receptor blockade decreases lung water in young rats exposed to viral infection and hypoxia

Viral respiratory infections may increase the susceptibility of young animals to hypoxia-induced pulmonary edema. Because hypoxia stimulates endothelin production, we hypothesized that an increase in lung endothelin contributes to these alterations in lung water. Weanling rats were infected with Sendai virus, causing a mild respiratory infection. At day 7 after infection, animals were exposed to hypoxia (inspired O(2) fraction = 0.1) for 24 h. Exposure to virus plus hypoxia led to increases in lung water compared with control groups (P < 0.001). Lung endothelin levels were significantly higher in the virus plus hypoxia group than in control groups (P < 0.001). A second group of infected animals received bosentan, a nonselective endothelin receptor antagonist, during exposure to hypoxia. Bosentan-treated animals showed less lung water accumulation, less lung lavage fluid protein, and less perivascular fluid cuffing than untreated animals (P < 0.01). We conclude that the combination of a recent viral respiratory infection and exposure to moderate hypoxia led to increases in endothelin in the lungs of young rats and that endothelin receptor blockade ameliorates the hypoxia-induced increases in lung water found in these animals.     

Significance of electrophoretic mobility distribution to bacterial transport in granular porous media

A method is developed to obtain the electrophoretic mobility distribution of colloidal particles by microelectrophoresis. The results demonstrate that for small particles (< 1 microm), the experimental mobility distribution must be deconvoluted to remove the effect of the random Brownian motion so that the electrophoretic mobility distribution can be obtained. For bacteria-sized particles (on the order of 1 microm or larger), the random Brownian motion is not significant, and the experimental mobility distribution represents the electrophoretic mobility distribution. The significance of the electrophoretic mobility distribution to bacterial transport is demonstrated through comparison between experimental and theoretical values of collision efficiency. Using the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the electrophoretic mobility distribution of bacteria is transformed to the distribution of collision efficiencies. For strain Comamonas sp. DA001, the predicted collision efficiency values span orders of magnitude, indicating that variation of surface charge density in a monoclonal bacterial population is a cause for the orders of magnitude variation of experimentally determined collision efficiencies. However, despite the fact that the predicted and experimental alpha distributions overlap, the match is not adequate. This inadequacy is ascribed to inability to probe heterogeneity of bacterial surface hydrophobicity, and the inability of the DLVO theory to quantitatively model particle deposition.     

Long-term effects of negative pions in female mice exposed to whole-body irradiation

Summary Long-term effects, especially the incidence of tumors, of whole-body exposure of female NMRI mice with either negative pions (peak or plateau region) or X rays have been studied in comparison to controls. Animals were irradiated at the age of 10 days after birth. The mice were then regularly examined for deaths and signs of severe disease, moribund animals being killed. A detailed histopathological work-up has been performed. The data show that the survival as defined by death or the time of autopsy is significantly lower in irradiated mice in comparison to controls, that there is no difference in reduction of survival between groups treated either with X rays or pions at peak region, but that a difference can be seen when comparing X rays with pions at plateau region. The incidence of ovarian tumors at any particular age is higher in mice treated with X rays or pions than in control groups, but significantly lower in animals exposed to plateau pions than in those treated with peak pions or X rays.     

State of the antioxidative activity of erythrocyte membranes in rats exposed to x-rays after administration of alpha-tocopherol acetate

Injection of alpha-tocopherol acetate to albino mongrel rats potentiates antioxidant activity (AOA) that involves water-soluble factors of the antioxidant system in erythrocyte membranes. The activation of AOA by alpha-tocopherol takes place immediately after irradiation and drug injection and persists during the first 24 h following irradiation.