Biophysics最新文献

Determination of the interaction parameters of low-molecular-weight compounds with DNA is difficult in cases where the compounds do not exhibit appreciable fluorescence or their spectral changes are difficult to interpret. To solve this problem, an approach involving the use of known fluorescent dyes competitively binding on DNA is proposed. This approach uses a model describing the competitive binding of two extended ligands on a linear DNA matrix. This model allows approximation of experimental data and determination of binding parameters corresponding to two nonfluorescent types of ligands. The first type of ligand exhibits intercalation binding to DNA and competes with ethidium bromide, while the second type binds along the narrow groove and competes with Hoechst 33258 dye.

Changes in the qualitative composition and quantitative content of phosphoinositide cycle metabolites and their involvement in the process of excitation along nerve s have been studied; regeneration of injured somatic nerves under the action of insulin-like growth factor-1 has been established. It was shown that when the nerve is excited, there is a decrease in the level of phosphatidylinositol and phosphatidylinositol-4,5-diphosphate and an increase in the content of phosphatidylinositol-4-monophosphate and phosphatidylinositol-3,4,5-triphosphate, which indicates an intensification of phosphoinositide metabolism under conditions of depolarization of the nerve fiber membrane, as well as a redistribution of fatty acids in the phosphatidylinositol fractions, diacylglycerol and free fatty acids. Nerve incision is accompanied by the accumulation of all forms of phosphoinositides and a decrease in the level of diacylglycerol in both the proximal and distal segments of the nerve, apparently as a result of inactivation of phosphoinositide-specific phospholipase C. Upon intramuscular administration of insulin-like growth factor-1 at a dose of 100 ng/kg, there is an intensification of phosphoinositide metabolism, accumulation of diacylglycerol and a decrease in free fatty acids. Using Raman spectroscopy, recording of action potentials and growth of cones, restoration of the physico-chemical state of the lipid bilayer and functional activity in the proximal segment of somatic nerves was revealed when insulin-like growth factor-1 was used, which correlates with our data on changes in the composition of the lipid fraction of injured nerves in the presence of the drug. We believe that insulin-like growth factor-1 is one of the factors of axonal regeneration and restoration of functioning of injured nerves, exerting its effect as a result of activation of phosphoinositide-specific phospholipase C and phosphatidylinositol-3-kinase signaling pathways.

Using the methods of computational chemistry, quantum-chemical methods and flexible docking, the peculiarities of the spatial organization of protein-ligand complexes formed as a result of binding of the H1-histamine receptor to a set of drugs were investigated. Representatives of antihistamine drugs of different generations, a drug belonging to the group of antiemetics, as well as several representatives of the class of tricyclic antidepressants with a pronounced antihistamine effect were chosen for the study. The results of the study can potentially be used for the development of new-generation antihistamines.

The dual role of the ATP molecule, a macroergic compound and a neurotransmitter, is considered. As a signaling molecule, ATP is involved in the formation of the visual system and the development of the inner ear of the embryo; it is involved in the mediation of pain and taste sensations. In cardiovascular diseases, the release of ATP into the intercellular medium serves as a signal for the body to activate repair mechanisms. ATP is involved in maintaining the normal functioning of many organs and tissues. This suggests the possibility of its use for the treatment of a number of disorders: diseases of the kidneys, bones, bladder, skin, neurological and mental pathologies, as well as cardiovascular diseases. Some new trends in the creation of new drugs have been identified, based on the growing knowledge about the functions of ATP in the body. Tetranitrosyl iron complexes, NO donors, are a new class of potential anticancer and cardioprotective drugs. Their reaction rates with ATP and products formed are considered in detail. It is concluded that the interaction of these NO donor iron complexes with the glycolytic ATP and/or the neurotransmitter ATP makes a significant contribution to the therapeutic effects of these compounds.

Light-induced redox transformations of P₇₀₀, the reaction center of photosystem I, were studied using the EPR method depending on the illumination conditions of plant leaves (intensity and spectral composition of the active light). Within the framework of a mathematical model, the key stages of electron transfer along the noncyclic electron transport chain containing photosystems I and II and mobile transporters (plastoquinone, plastocyanin, and ferredoxin) and the processes of trans-thylakoid proton transfer associated with ATP synthesis were considered. The mechanisms of pH-dependent regulation of electron transport in chloroplasts at the acceptor and donor sites of photosystem I have been analyzed. The modeling results are in agreement with experimental data on the kinetics of light-induced transformations of P₇₀₀ in chloroplasts of higher plants. The results are discussed in the context of “short-term” pH-dependent mechanisms of electron transport regulation in chloroplasts in situ.

Improving the effectiveness of early rehabilitation of elderly patients after hip arthroplasty remains an urgent task. The aim of the study was to evaluate the effectiveness of isometric exercises in early (2 weeks) rehabilitation of elderly patients after hip replacement using blood parameters. The randomized study included ten elderly patients in the control (n = 5) and experimental (n = 5) groups with isometric exercises and rehabilitation techniques that were performed daily from 1 to 12 days after total cement hip arthroplasty. The effectiveness of rehabilitation was assessed by the indices of muscle traumatization (myoglobin, creatine phosphokinase, aspartate aminotransferase, and lactate dehydrogenase concentrations) and systemic inflammation (erythrocyte sedimentation rate, CRP concentrations, and interleukins IL-6, IL-8, and IL-1β) in the blood of patients on the 12th day after surgery. The indices of muscle traumatization and the concentrations of C-reactive protein and leukocytes in blood, as well as the erythrocyte sedimentation rate did not reveal any significant difference between the groups of patients. The difference between the control and experimental groups in terms of restoration of interleukin IL-6, IL-8, and IL-1β concentrations in the blood to the normal range was statistically significant according to Fisher’s exact test (p = 0.042). In general, these results showed that additional isometric exercises provided more effective early rehabilitation of elderly patients after endoprosthesis in comparison with the standard set of exercises and that normalization of the concentration of proinflammatory interleukins, primarily IL-6 and IL-8, can be considered as an objective indicator in assessing the effectiveness of methods of early rehabilitation of elderly patients after hip arthroplasty.

The lifetime of the triplet state of the carotenoid, spheroiden (^TCar) in the photosynthetic reaction center of the purple bacteria Cereibacter (Rhodobacter) sphaeroides in the temperature range from 0 to 45°C and the effect of the concentration of molecular oxygen in the medium on this time was studied. O-phenanthroline (10^–2 M), which partially displaces the primary quinone acceptor from the structure of the reaction center, was added to the preparations to form ^TCar upon light excitation of the reaction center. The activation energies of the ^TCar quenching process were determined under normal aerobic conditions and during partial degassing of the studied preparations.