Biophysics最新文献

Using an experimental model of dysbiosis caused by the antibiotic gentamicin sulfate, the effect of low-intensity electromagnetic radiation of extremely high frequencies (42.2 GHz, 100 µW/cm², pulse modulation by a meander with a frequency of 1 Hz, exposure for 30 min per day for 10 consecutive days, starting from the 4th day after induction of dysbiosis) on the fatty acid composition of the thymus, blood plasma, activity of antioxidant enzymes, the content of malondialdehyde and lactate in the blood of laboratory rats was studied. A significant decrease in the content of myristic, palmitic, stearic, palmitoleic, oleic and linoleic fatty acids in the thymus of animals was shown. The activity of antioxidant enzymes, the content of fatty acids and malonic dialdehyde in the blood did not change. The content of lactate in the blood plasma decreased. Irradiation of animals with dysbiosis normalized the fatty acid composition of the thymus and the content of lactate in plasma. The high efficiency of low-intensity extremely-high-frequency electromagnetic radiation with certain parameters in dysbiosis opens up fundamentally new possibilities for using radiation in this range for the prevention and treatment of a number of pathological conditions associated with dysbiosis.

Cryopreservation of biological material is an important issue in many fields of biology and medicine, especially for assisted reproductive technologies. Cryoprotective media, including cell-permeating and non-permeating components, are used for effective cryopreservation of cells. Glycerol at various concentrations is often used as a permeating component. However, elucidating the mechanisms of the cryoprotective effect of these compounds, as well as increasing the proportion of surviving cells after cryopreservation, remain urgent tasks of cryobiology. In this study, the mechanism of glycerol transfer through sperm membranes with the participation of aquaporins was investigated by mathematical modeling. The presented model describes the dynamics of changes in sperm volume depending on the concentration of glycerol and sucrose in a cryoprotective medium. As a result of the analysis, the characteristic time for establishing equilibrium between the cryoprotective medium under study and the cells was calculated, which was t = 80 s in the presence of 12 vol. % of glycerol. The sucrose concentration (0.16 M) was determined at which the cell returns to its original volume after incubation in the cryoprotective medium. It has been shown that the human sperm can contain 6750 aquaporins of the 7th type with a permeability P_AQP7= 0.00366 µm³/s. The experiments performed showed an increase in the sperm motility index after adjusting the sucrose concentration in the solution in accordance with the simulation results.

There was no noticeable change in the antiviral effect of inhalation of solutions of binuclear dinitrozyl iron complexes with glutathione (B-DNIC-GSH) and sodium diethyldithiocarbamate (DETC) to Syrian hamsters infected with the SARS-CoV-2 virus when they were successively administered to animals in a “nose-only” chamber or a “whole-body” chamber. Inhalation in the “whole-body” chamber, which led to wetting of the animals’ bodies, led only to a decrease in the level of mononuclear dinitrosyl iron complexes with thiol groups of proteins recorded by the EPR method in the lungs, without changing the total content of the binuclear and mononuclear forms of dinitrosyl iron complexes. It is assumed that the antiviral effect of B-DNIC-GSH + DETC against the SARS-CoV-2 virus was due to nitrosonium (NO⁺) cations released from B-DNIC-GSH as a result of its destruction by DETC molecules. A similar antiviral effect on the Syrian hamster models was exerted by a less stable than B-DNIC-GSH complex with mercaptosuccinate, without additional aerosol treatment of animals with a solution of DETC.

The origin of diabetes mellitus, one of the most common metabolic diseases in the developed world, is associated with impaired insulin secretion or cell resistance to the effect of this hormone (type I and type II diabetes, respectively). In both cases, a common pathological change is an increase in blood glucose level, hyperglycemia, which can eventually lead to serious damage to organs and tissues of the body. Mitochondria are believed to be one of the main targets of diabetes at the intracellular level. In this study, we investigated the functional state of the mitochondria of the heart of inbred mice of the C57BL/Ks–db+/+m line carrying the recessive diabetes-db gene (diabetic mice). Histological analysis of the left ventricle of the heart of diabetic and control mice was performed. In the heart tissue samples of diabetic mice, an increase in the intensity of eosin staining was observed, which implies damage to the structure of cytoplasmic proteins. In addition, it was shown that respiratory control and Ca²⁺ capacity in the mitochondria of diabetic mice decreased compared to controls. Changes in mitochondrial dynamics and mitophagy under these conditions were investigated.

The aim of this study was an attempt to prevent the decrease in sperm motility of the fruit fly Drosophila melanogaster that occurs in the early period of readaptation after space flight by adding phospholipids with polyunsaturated fatty acids in the tail groups (essential phospholipids) to the nutrient medium. The study was carried out as part of space flights on board the Russian segment of the ISS during the periods of September 15, 2023–September 27, 2023 (ISS-69) and March 23, 2024–April 6, 2024 (ISS-70). The content of cytoskeletal proteins in the testes was determined by Western blotting and sperm motility by video recording and subsequent analysis. The results of the study show that modification of the nutrient medium by adding essential phospholipids leads to a decrease in cholesterol content and an increase in actin content, which prevents a decrease in tubulin content and a decrease in the speed of movement of fruit fly sperm in the early period of readaptation (up to 16 hours) after space flight. The data we obtained, on the one hand, demonstrate a possible mechanism for triggering mechanotransduction, and on the other, allow us to propose essential phospholipids as one of the means of protection against negative changes associated with changes in the gravity field acting on the cell.

A decrease in the intensity of the processes of apoptotic and necrotic death of human peripheral blood lymphocytes was found after exposure to UV light (254 nm, 1510 J/m²) and hydrogen peroxide (10^–5 mol/L) in the presence of resveratrol (10^–7, 10^–6, 10^–5 mol/L). It was revealed that the cytoprotective effect of resveratrol on lymphocytes is due to a decrease in the level of production of intracellular reactive oxygen species and calcium ions, an increase in the activity of antioxidant enzymes, that is, catalase and glutathione reductase, an increase in peroxide resistance of plasma membranes, and interaction with DNA. Possible mechanisms of action of resveratrol as a regulator of the processes of apoptotic and necrotic death of lymphocytes induced by exposure to hydrogen peroxide and UV radiation are discussed.

The search for effective and safe radio-modulating compounds that reduce cancer cell radioresistance and/or the concomitant damage to normal tissues caused by radiation remains a significant challenge in radiation therapy. Peroxiredoxin 6, a member of the thiol-specific peroxidase family, is a promising candidate to solve this problem. However, often in studies, insufficient attention is paid to radiation parameters and there is no information about how different radiation parameters influence the radioprotective effect of exogenous peroxiredoxin 6. This article shows the peculiarities of the radioprotective effects of intravenous peroxiredoxin 6 at a concentration of 20 μg/g body weight and its mutant form Prx6-C47S (without peroxidase activity) administered shortly before X-ray or γ-irradiation with different dose rates and exposure times. Survival rates of the 10 Gy γ-irradiation 0.125 Gy/min and 7 Gy X-ray irradiation 1 Gy/min animal groups (an 8-fold difference in dose rate and exposure time) were correlated both for control and experimental animals.

A study of the cytotoxic activities of two polyacrylic acid-based compounds containing gold (aurumacryl) and silver (argacryl) against a panel of human tumor cell cultures (769-P, Caki-2, SK-RC-1 renal carcinoma lines, BT-474 breast carcinoma, and NCI-H211 small cell lung carcinoma) was carried out in vitro. The results we obtained were analyzed in comparison with the data established earlier for other cell cultures (MCF-7 breast carcinoma, A-549 lung carcinoma, HCT116 colon carcinoma, and Mel Me melanoma). The IC₅₀ cytotoxic index of drugs for the nine tested tumor cell lines ranged from 0.8 to 5.2 μg/mL for aurumacryl and from 0.2 to 14.4 μg/mL for argacryl (in terms of gold and silver content, respectively), depending on the type of tumor. Significant differences were found in the spectra of the lethal effects of aurumacryl and argacryl against tumor cells of various types.

The RPS12 gene in the mitochondrial genome encodes an important protein from the small ribosomal subunit. The transcript of this gene can undergo RNA editing in a number of organisms, for instance it is edited actively in all tripanosomatida. In this study, a comparison between the sequences of edited mRNA and tertiary structures of the proteins when mRNA were translated from some of the members of Tripanosomatidae family showed that tertiary structures of the RPS12 gene remained unchanged in all species while only two short conserved regions were found in the primary structure of the gene. Using computer modeling it was demonstrated that these regions encode amino acids that are turned in the decoding center of the ribosome. The nature of editing patterns demonstrates that evolutionary conservation of these regions is independent of the editing process; moreover, an evolutionary tendency to reduction of editing process in a number of sites was seen within the conserved sites of the RPS12 gene.

Radiation therapy occupies one of the key places in the arsenal of cancer treatment methods. This non-invasive method has been actively used for many decades and has demonstrated high effectiveness in combating various types of malignant neoplasms. Despite significant progress in ionizing radiation delivery technologies and the introduction of targeted radiosensitizers and immunotherapy, classical radiation therapy faces limitations related to radioresistance of tumor cells. This is due to a variety of factors, such as genetic mutations, metabolic features of cancer cells, their ability to repair DNA, the presence of a tumor microenvironment, and many others. Radioresistance of tumors reduces the success of treatment, which makes it necessary to search for new approaches to improve the effectiveness of radiation therapy. This review discusses the basic principles of radiation therapy and the properties of cancer cells that affect their radiosensitivity. Both the existing methods of overcoming cancer cell radioresistance and the prospects for their further development are being considered, which can significantly improve the effectiveness of cancer treatment.