Effect of water-soluble antioxidants on the permeability of lysosomal membranes and on the structure of the liver in rats with thermal burns

Experiments on rats were made to study the effect of water-soluble antioxidants on the permeability of lysosomal membranes of liver cells and liver structure under burn. Antioxidants were injected intraperitoneally shortly after burn, whereas examination was performed after one day. It has been discovered that one day after burn there takes place an appreciable destabilization of lysosomal membranes with the release of a lysosomal matrix enzyme, cathepsin D to the cytoplasm. Liver structure had undergone substantial changes by that time. After administration of water-soluble antioxidants lysosomal membranes got stabilized while liver structure manifested but insignificant disorders.     

Fatty acid composition of Escherichia coli cells and their viability in air

Experiments on E. coli used as a model have revealed that fatty-acid composition is one of the characteristics which determine the viability of bacteria in the air. The viability of microbial cells in the air has been shown to increase with the increase of the pool of cyclopropane acids and the palmitic acid/palmitoleic acid ratio in the cells, irrespective of their genotype and the phase of their growth.     

Study of total activity of natural lipid antioxidants by chemiluminescence method

The total antiradical activity of lipid antioxidants extracted from organs and tissues of fish Coregonus peled (Gmelin) was investigated using chemiluminescence method. It has been established that lipids contain antioxidants of two types. The bioantioxidants of the first type have a comparatively high efficiency constant K7eff. = (2.4-3.2) 10(6) M-1.s-1, whose value is 100 times more than that of the constant of the second type inhibitors K7eff. = (3.5-5.0) 10(4) M-1.s-1. Using the method of thin-layer chromatography such individual antioxidants of lipids as tocopherol, ubiquinon, ubichromenol were separated and quantitatively studied, as well as recorded in the presence of vitamin K, A, cholesterol. It is shown that the quantitative content of high-activity antioxidants in lipid of different kinds substantially varies (0.5-17.1) 10(-4) M; the low level of their content has been recorded for internal fat and brain lipids, the high one--for the lipids present in immature eggs, red muscles and liver.     

Thermoinduced structural changes in the membranes of animal organs following administration of antioxidants and during growth of malignancies

By means of weak-bound spin probes--stable iminoxyl free radicals differing in the level of hydrophobity there were studied thermoinduced structural transitions in the membranes of cell organells of animal liver after intraperitoneal injection of antioxidants and in the course of malignant growth, and in the nuclear membranes of Ehrlich ascite carcinoma as well. It has been found that during the growth of Ehrlich ascite carcinoma changes in rotationary mobility of probes in cell nuclei isolated from the liver of tumour-carrying animal are similar to the changes observed after antiocidants injection. A different pattern is observed in tumour cells. The membranes of ascite cell nuclei are characterized by a weak dependence of tau c on temperature for both probes. Within the temperature range studied no characteristic structural transitions proceeding in the nuclei of intact animals are observed.     

Lake morphometry determines Dreissena invasion dynamics

Predicting the ecosystem effects of invasive species and the best control strategies requires understanding population dynamics and population regulation. Invasive bivalves zebra and quagga mussels (Dreissena spp.) are considered the most aggressive invaders in freshwaters and have become major drivers of ecosystem processes in the Laurentian Great Lakes. Combining all lake-wide studies of Dreissena spp. conducted in the Great Lakes, we found that invasion dynamics are largely governed by lake morphometry. Where both species are present, quagga mussels generally become dominant in 8–13 years. Thereafter, zebra mussels remain common in shallow lakes and embayments and lake-wide Dreissena density may remain similar, while in deep lakes quagga led to a near-complete displacement of zebra mussels and an ensuing dramatic increase in overall dreissenid density. In deep lakes, overall Dreissena biomass peaked later and achieved?~?threefold higher levels than in shallow lakes. Comparison with 21 waterbodies in North America and Europe colonized by both dreissenids confirmed that patterns of invasion dynamics found in the Great Lakes are very consistent with other waterbodies, and thus can be generalized to other lakes. Our biophysical model predicted that the long-term reduction in primary producers by mussel grazing may be fourfold less in deep compared to shallow lakes due to thermal stratification and a smaller proportion of the epilimnion in contact with the bottom. While this impact remains greatest in shallow areas, we show that when lakes are vertically well-mixed, dreissenid grazing impact may be greatest offshore, revealing a potentially strong offshore carbon and phosphorus sink.

     

The sensitivity of experimental tumor systems to ultra low doses of doxorubicin

Biological effect of doxorubycin in standard (10(-3) mol/l) and ultra low doses (10(-5)-10(-20) mol/l) against some "signal" animal tumor systems--Lewis lung carcinoma, 755 adenocarcinoma, B-16 melanoma, Ehrlich carcinoma and L1210 leukemia was studied. The all models were very sensitive to the action of the drug in standard dose. Solid tumors' growth inhibition by 80-95% as well as increasing in life span of mice with L1210 leukemia by 86% in comparison with control and surviving of animals with Ehrlich carcinoma had been revealed. It had been shown that the drug in the area of ultra low doses occurred the following effects: inhibition of Lewis lung carcinoma growth by 80-95% compared to control after administration of the all tested ultra low doses; increasing of the life span of the animals with Ehrlich carcinoma and L1210 leukemia by 86-123% and 6-23%, correspondingly, upon the action of all tested ultra low doses; inhibition of B-16 melanoma growth by 50 and 70% after administration of the drug in doses 10(-20) mol/l and 10(-5) mol/l, correspondingly as well as deceleration of 755 carcinoma growth by 40% compared to control after action of the drug in the dose 10(-20) mol/l; stimulation of the B-16 melanoma growth by 20% relative to control after 10(-10) mol/l dose injection and enhancement of tumors sizes by 20-60% above control levels as a result of treatment of mice with 755 carcinoma by the drug in such ultra low doses as 10(-5) and 10(-15) mol/l. So, it was found that all tested tumor systems revealed certain sensitivity to the some ultra low doses of the drug. At the same time it was shown that doxorubycin in ultra low doses displayed alternative character of its biological effect, directivity of which varied according with the dose level and tumor strain.     

Mechanism of polymorphic transformations in phosphatidylcholine membranes

Based on the 31P NMR, PMR, and EPR data on the thermally induced behavior of water dispersions of natural and synthetic phospholipids in the presence of membranotropic agents: the neuropeptide adrenocorticotropic hormone and beta-(4-oxy,3,5-ditretbutyl-phenylpropionic acid), a new mechanism of the interaction of membranotropic substances with the molecules of hydrate shells of membrane phospholipids was proposed, which underlies polymorphic transitions in phosphatidylcholine membranes.     

Late consequences of action of low doses of ionizing radiation on human enzymatic antioxidant system

Age-related changes in the activity of superoxide dismutase and glutathione peroxidase in the blood of participants of the Chernobyl accident liquidation were studied. According to our findings the people under 30 years old are the most sensitive to irratiation.     

Signal function of the reactive oxygen species in regulatory networks of the cell reaction to damaging effects: contribution of radiosensitivity and genome instability

Reactive oxygen species (ROS) have a few possible effects, such as metabolic (participation in regulation of protein functions), damaging (oxidative damage to proteins, lipids and nucleic acids) and signal; the latter is reviewed in the article. Superoxide anion-radical (O2-.), hydroperoxide (HO2) and nitroxide (NO) are capable to act as signal substances in the cell regulatory network, which determines a mode of cell response to disturbance: proliferation pace, a course of differentiation or a start of the apoptosis program. A role of ROS in the reaction network is reviewed: importance of their content in a cell; ROS-bound signal pathways, which trigger the programs of cell reactions to stimuli; initiations of the regulatory network, which determine a content of ROS in a cell; ROS reactions with network components, which influence its functioning. A significance of the ROS-bound segment of the network, which realizes regulatory signals of the damage, in formation of radiobiological effect is estimated. The data obtained by the authors are submitted; the prospects of studing substances (such as phenozan etc.), which can actively influence redox processes, as means of modification of radiation-induced genome instability and prevention of oncogenic transformation are considered.