Biophysics最新文献

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.

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.

This study aimed to investigate myoneural transmission in the presence of capsaicin, which acts as an integrator of pain stimuli and causes heat sensation. The effects of purines that participate in synaptic transmission, such as ATP and adenosine, in the presence of capsaicin were explored. When the neuromuscular preparation of frog was perfused with solution containing capsaicin, the inhibitory effects of both purines were significantly reduced. A reduction of the depressant effects of adenosine is associated with the inhibition of A₁ signaling, since the A_2A receptor agonist CGS21680 showed a pronounced potentiating effect in the presence of capsaicin, which was almost completely hidden in the control. Our findings suggest that the known neuroprotective effect of capsaicin is primarily due to elimination of inhibition by endogenous purines of the induced quantum output of the neurotransmitter.

The study of potential-dependent calcium channels sheds light on the formation of systems responsible for the coupling of sensors and actuators in a living cell. Based on data on the potential-sensitive calcium channel TCa_v3 (2063 amino acid residues) from Trichoplax adhaerens cells, homologues of 2090 amino acid residues in the scaffold of Trichoplax sp. H2 and an incomplete polypeptide with a length of 1510 amino acid residues in the scaffold of Trichoplax adhaerens are identified. The latter hypothetical protein is annotated as a Ca_v3 channel. An EEDD selective filter is found for all three proteins and the core structure of the calcium channel consisting of 24 transmembrane α-helices is reconstructed. Nevertheless, the studied proteins differ in cytoplasmic domains, which indicates a different specialization of Ca_v3 channels when conducting a signal into the cell. For example, part of the AID motif (alpha-interacting domain) and the adjacent potential sensor from the annotated channel have homology in 25 species of bony fish, and the corresponding region from other channels in 41 species of bony fish and in 4 species of snakes. Significantly, a highly conserved IIS1-S2 loop with the IEHHNQP sequence is found below the AID motif of bony fish, as in trichoplax; while a homologous IEHHEQP sequence is found in snakes, characterized by a negative glutamic acid residue, which is also present in the corresponding rat and human proteins. Based on the analysis of primary transcripts and mature polypeptides, a modular mechanism for the evolution of Ca_v3 channels is proposed by inserting and combining protein domains performing various regulatory functions.

Mitochondria are involved in diseases of various etiologies. The use of drugs aimed at improving the functional state of mitochondria may be a promising therapeutic approach to diseases of various etiologies. Astaxanthin is a keto-carotenoid (xanthophyll) of predominantly marine origin. It has both lipophilic and hydrophilic properties and can penetrate through the cell membrane, localizing in the mitochondria and preventing mitochondrial dysfunction. In this paper, the effect of astaxanthin on the functional state of rat brain mitochondria, changes in mitochondrial dynamics and mitophagy in isoproterenol-induced damage is studied. Under the action of astaxanthin, mitochondria are more resistant to the Ca²⁺-induced opening of a nonspecific pore and the activity of complexes I, IV, and V of the respiratory chain increases. Moreover, astaxanthin alters the level of markers of mitochondrial fission and fusion, as well as mitophagy in isoproterenol-induced mitochondrial dysfunction, which probably leads to an increase in the number of functional mitochondria of the rat brain and improved their condition. Astaxanthin can be considered as a mitochondria-directed agent in the therapy for pathological conditions associated with oxidative damage and mitochondrial dysfunction caused by heart failure. As a dietary supplement, astaxanthin has the potential for the antioxidant protection of cells in cardiovascular diseases.

A bulk segregant analysis (BSA) was used to analyze the F₂ population from crossing two flax varieties that differ in fusarium wilt resistance genes. The causative agent of this disease, the fungus Fusarium oxysporum f. sp. lini is one of the main pathogens of flax, causing huge economic damage to its global production. Sequencing of DNA pools of highly resistant and sensitive to fusarium wilt F₂ plants and their subsequent analysis identified two regions on chromosomes 9 and 13 that caused resistance to fusarium wilt. Candidate genes for subsequent analysis are selected by functional gene annotation and analysis of gene expression of QTL regions in the transcriptomic data obtained as a result of the infection of the fusarium-resistant Atalante variety. As a result of combining the two approaches, three genes are identified in each of the QTL regions, which, according to the published data, are involved in the plant’s response to infection and are differentially expressed in the transcriptome experiment.