Biophysics最新文献

It has been shown that nicotinamide coenzymes (NADPH, NADH, NADP⁺, and NAD⁺) are capable of generating superoxide anions (({text{O}}_{2}^{{ - ,bullet }})) in an alkaline environment. The superoxide-generating activity of the coenzymes is associated with high pH values and is sensitive to SOD. However, nicotinamide itself, being a functional part of coenzyme molecules, does not have this property. Polarographic studies showed that in the presence of coenzymes, molecular oxygen is consumed from the buffer, namely oxygen activation occurs due to the formation of ({text{O}}_{2}^{{ - ,bullet }}). Based on the obtained results and in accordance with the literature, our observations suggest that the formation of adducts of nicotinamide, which is part of the coenzyme molecule, and hydroxyl anions (OH^–) may lead to the formation of ({text{O}}_{2}^{{ - ,bullet }}). Under mild conditions in the organism, the studied coenzymes, while performing their main functions, are expected to generate superoxide, meaning that they can be signaling molecules.

The planarian nervous system is represented by a cephalic ganglion in the anterior part of the body and a pair of well-defined ventral nerve trunks extending along the entire body of the animal. The serotoninergic components of the nervous system are determined by the indirect immunocytochemical staining of the total preparations of the planarian Schmidtea mediterranea tissues, followed by analysis by fluorescent microscopy. The presence of serotoninergic components is found in the central and peripheral parts of the nervous system of the planarian S. mediterranea. The morphological parameters of serotonin-immunopositive structures are measured and the number of neurons in the cerebral ganglion is counted. The measurements are carried out on micrographs from stained total preparations obtained using a digital camera. The size of serotonin neurons in three areas of the body, the thickness of nerve trunks and cerebral ganglion, and the distance between nerve trunks and commissures are considered. For the first time, new quantitative data characterizing the morphological properties of the nervous system of the planarian S. mediterranea have been obtained. The regeneration of planarian eyes after decapitation and serotonin exposure is also studied. It is found that exogenous serotonin at a concentration of 0.01–1 μM accelerated eye differentiation during regeneration of the head end of S. mediterranea.

The formation of a hemostatic thrombus is a key response of the hemostatic system to a wide range of possible vascular damage. The main mechanism of thrombus growth in conditions of high shear rates is platelet adhesion and aggregation. It is known that arterial thrombi have significant spatial heterogeneity, which is associated with the heterogeneity of the distribution of platelet activators in the thrombus structure. The spatiotemporal dynamics of the molecules involved in thrombosis depends on the parameters of the transfer of these substances in the thrombus. To study the dynamics of arterial blood thrombi formation, continuum models representing a blood thrombus as a porous medium are actively used today. However, when choosing the parameters of such models, researchers face significant uncertainty caused by conflicting experimental data. This review analyzes the published data on the physical parameters of an arterial thrombus as a porous medium. Special attention is paid to the analysis of parameters for the external part of the thrombus, the so-called shell, which is generally characterized by higher values of porosity and permeability.

Using the Fenton reaction, a system has been modeled in which particles similar to those formed during the radiolysis of water were generated. The suppression of reactions caused by hydroxyl radicals formed in the system under the action of chlorophyllin is evaluated by the chemiluminescence method. It has been shown that sodium-copper chlorophyllin dose-dependently inhibits the chemiluminescence accompanying the phosphatidic acid peroxidation induced by the Fenton reaction. Based on this, it is concluded that copper chlorophyllin can inhibit the metabolism of lipid radiotoxins, lipid peroxidation (LP), caused by the attack of water radiolysis products on lipid molecules.

This study continues our previous research aimed at investigating changes in the pools of amino acids in the myocardium of the ground squirrel during winter torpor. Neurochemical profiles of amino acids and the secondary metabolites (taurine, phosphoserine, and cysteic acid) were explored in the neocortex of the ground squirrel at different stages of torpor: in the beginning of torpor (2–3 days) and during prolonged torpor (9–10 days), as well as during short-term winter arousal (winter activity, euthermia). Reduced excitatory neurotransmitter levels (glutamate by 7% and 14%; aspartate by 25% and 52% in a coordinated manner and the increased level of GABA, the main transmission inhibitor (by 50% and 67%) were observed from the onset of the torpor entry and at the end of the torpor arousal, respectively. Alanine, which was formed in negligible amounts in the neocortex in the summer season, increased at the initial stage of hibernation and after multiday torpor bout (by 98% and 126%, respectively), indicating a partial switch to anaerobic glycolysis. Short-term interbout euthermia returned levels of these substances back to normal. The behavior of glutamate and aspartate, the anaplerotic substrates, that supported cycling of the tricarboxylic acid cycle during torpor and winter activity periods was like their responses in the myocardium, though differed quantitatively. The responses of the neuromodulators such as glycine, threonine, and lysine differed radically when compared to their responses in the myocardium. No changes in taurine and phosphoserine pools were detected, but the level of cysteic acid decreased compared to the summer control from 0.51 ± 0.06 μmol/g to 0.07 ± 0.01 μmol/g at the end of torpor, while during winter euthermia it became 2 times lower than the summer level. Our data suggest that metabolic pathways involving anaplerotic amino acids of the neocortex are more active than the myocardium during winter torpor, while the pools of neuromodulators that regulate inhibition processes, increase.

Silver polyacrylate (argacryl) is shown to have antitumor activity in models of solid mouse tumors in vivo and a cytotoxic effect on human tumor cells in vitro. Argacryl enhances the antitumor effect of cisplatin (Lewis lung carcinoma in mice) and does not show cross resistance with cisplatin and doxorubicin (human breast cancer MCF-7). The molecular mechanism of action of argacryl could be associated with the induction of single-strand DNA breaks in the absence of crosslinking in the DNA molecule.

A method for assessing the state of formed elements based on the dielectric characteristics of a blood suspension is considered. A design of a fluctuation dielectric Fourier spectrometer (FDFS) is proposed, with the help of which it is possible to estimate the distribution of the formed blood elements according to their membrane state. As an illustration, experiments to assess the functional state of patients with coronary heart disease and an experiment on the effect of ascitic Ehrlich carcinoma on laboratory mice are described. It is shown that by using the proposed spectrometer, it is possible to obtain express estimates of changes in blood characteristics during diseases and to identify the dynamics of pathological processes in animals with ascitic Ehrlich carcinoma.

Bioelectrochemical systems based on electroactive processes in the root environment of plants are a promising direction for the combined production of green electricity and plant products. The dynamics of the electric potential differences formation in the root environment, diffuse reflection indices, fluorescence parameters of leaves, and morphometric and biochemical characteristics of lettuce varieties Chinese curly, Chinese red-green, Ballet, Cocarde, Mercury, Dubrava, Robin, and Solos F₁ hybrid are studied. The maximum electric potential difference of 430 mV was typical for the Mercury variety, and the minimum of 352 mV for the Chinese Curly variety. According to the sum of the parameters, in addition to the electrical ones, including the morphometric, biochemical, and photosynthetic characteristics, the lettuce Ballet variety was the best. In the future, based on the data obtained, it will be possible to create agrophytocenoses, including plants capable of high and stable electricity generation together with high productivity and good quality of the plant products obtained, due to the effective assimilation and conversion of light energy.

Electron paramagnetic resonance (EPR) spectroscopy is used to determine the content of nitric oxide (NO) and copper in the hippocampus of healthy rats and rats under ischemia modeling. Ischemia is modeled by both carotid artery ligation and carotid artery ligation, followed by taking 3 mL of blood from the common carotid artery. Signals from (DETC)₂-Fe²⁺-NO and Cu(DETC)₂ complexes are recorded by EPR spectroscopy. A significant decrease in NO production in the hippocampus (on average 28% per day) is found after an ischemic stroke caused by carotid artery ligation; and by 56% after carotid artery ligation followed by 3 mL of blood taken from the common carotid artery. The copper content in the hippocampus the day after ischemia caused by carotid artery ligation significantly decreases by an average of 20%; after carotid artery ligation with blood sampling, there is a tendency for the copper content to decrease; however, due to the large scatter of values, the reliability of the changes cannot be confirmed. Thus, cerebral hypoxia caused by carotid artery ligation is accompanied by a decrease in NO production in the hippocampus and signs of weakening of the antioxidant system, which further harmed the functional state of the homeostasis system.

Plant-based protein isolates are common food ingredients. Differential scanning calorimetry of isolates is used to predict their functional properties, as well as to evaluate the propensity of these isolates to form bioplastics through the heat-induced formation of intermolecular disulfide, hydrophobic, and other types of bonds. In this study, we use differential scanning calorimetry of a suspension containing a soy protein isolate (SPI) in glycerol. It is shown that heat is released upon heating the isolate in the presence of glycerol. The preliminary thermal denaturation of a water solution of soy proteins (95°C, 30 min) increases the thermal effect, while the enzymatic hydrolysis of the protein leads to a loss of the exothermic thermal effect. The addition of β-mercaptoethanol to the SPI has no effect on the observed exothermic process, which indicates the absence of a contribution of the formation of new disulfide bonds in this case. Thus, the formation of bioplastic by an SPI does not depend on the formation of new disulfide bonds, and the use of the differential scanning calorimetry method can be considered as a method for estimating the solubility of the protein preparation.