An Experimental Technique for Accurate Measurement of the Freezing Point of Solutions and Ice Melting in the Presence of Biological Objects on the Examples of P. Syringae and E. Coli
Pseudomonas syringae is a widely distributed bacterial epiphyte of plants. When the temperature of the environment drops below zero, P. syringae can serve as biological ice nuclei due to the presence of specialized ice-nucleating proteins. This property has found application in various fields, but despite its evident importance, the molecular mechanisms behind protein-induced freezing have remained largely elusive. One of the problems in the study of the ice-nucleating process is the difficulty of carrying out experiments with freezing/melting solutions at near-zero temperatures. The experimental design implies special requirements for the equipment used and measurement technique. In this work, we used an experimental setup assembled from a dry thermostat that maintains a constant temperature and an accurate digital thermometer. We experimentally tested the possible sources of errors of the setup. As a result, we have shown that the accuracy of determining the freezing temperature of liquids and the coexistence of ice and water is mainly determined by the accuracy of the thermometer. The accuracy of determining the melting point of ice depends on the volume of the sample and is systematically underestimated in our setup. Using the proposed experimental technique, we performed a comparative study of P. syringae and E. coli cells, which revealed that P. syringae cells affect not only the freezing point of the solution but also the temperature of the coexistence of ice and water. The observed effect can be explained by the binding of P. syringae cells to the ice surface.
|3 AN EXPERIMENTAL TECHNIQUE FOR ACCURATE MEASUREMENT.pdf||1.94 MB|
In this study, we investigated the toxic properties of synthesized immunomagnetoliposomes of the following composition: phosphatidylcholine - cholesterol - disteroylphosphoethanolamine-polyethylene glycol (2000) - magnetite - antibodies to histone H3. Their dimensional characteristics were studied by the dynamic light scattering method. It was revealed that liposomal nanoparticles have dimensions of 176.4 ± 12.9 nm. Data on the toxicity of the synthesized nanoparticles in relation to human blood cells: liposomes in cells to liposomes ratio from 1/1 to 1/1000 have no toxic effect on lymphocytes; lactate dehydrogenase (LDH) release from human blood erythrocytes has been observed in the case of cells/liposomes ratio 1/100-1/1000 after the incubation with liposomes containing sodium azide (0.03%).
|2 STUDY OF THE IMMUNOMAGNETOLIPOSOMES’ CYTOTOXICITY.pdf||494.87 KB|
The widespread occurrence of drug-resistant urogenital mycoplasmas and the high rate of their genetic variability make it possible to consider Mycoplasma hominis as a natural reservoir of antibiotic resistance determinants. Multiple drug resistance of many bacterial types is due to the active elimination of the antibiotic from the cell through various efflux systems. The genome structure of ten clinical isolates Mycoplasma hominis was studied using next-generation sequencing. The molecular genetic characterization family MATE proteins of Russian isolates M. hominis genes using bioinformatics analysis was obtained in the first. It has been established that proteins of the transport systems (ABC-transporters) and MATE play an important role in the formation of antibiotic resistance in urogenital mycoplasmas. The activity and functioning of transport systems are associated with the presence of mutations in the genes encoding regulatory proteins. Efflux systems should be considered as promising potential targets in the creation of new generation antibacterial drugs.
|1 MOLECULAR-GENETIC CHARACTERISTICS.pdf||638.4 KB|
Cognitive Rehabilitation of Patients with Acute Cerebrovascular Accident Using EEG-Guided Adaptive Neurostimulation
The methodology of digital psychophysiological mapping was used in a group of 18 stroke patients and a matched group of healthy controls to reveal possible markers of acute cerebrovascular accident. The patients were found to have a number of indicators that were significantly different from the norm and could claim the role of stroke biomarkers. Among them there are lowered values of the power and peak frequency of the EEG alpha rhythm, significantly lowered HRV indices, as well as a significantly higher levels of emotional disadaptation. Stroke patients participated in a treatment session, in which they were exposed to EEG-based bimodal (light-musical) adaptive neurostimulation, in which some EEG characteristics (EEG oscillators) control sound (musical) stimulation, and other EEG characteristics (native EEG) simultaneously control light stimulation. As a result of the treatment, patients demonstrated a normalization of all the described indicators of the functional state: the values of a power and frequency of the EEG alpha rhythm significantly increased and approached the norm, as well as the parameters of the cardiovascular system and the cognitive-emotional sphere of stroke patients. The method of EEG-guided adaptive neurostimulation used in this work demonstrates the possibility of effective cognitive rehabilitation of stroke patients even with a single application.
|11_COGNITIVE REHABILITATION OF PATIENTS WITH ACUTE CEREBROVASCULAR ACCIDENT.pdf||611.99 KB|
X-Ray Endovascular Treatment of “Critical” Thromboembolism of the Pulmonary Artery in Patients with Acute Cerebral Blood Circulation by Hemorrhagic Type
Purpose of the study: substantiation of indications and assessment of results X-ray endovascular treatment of "critical" PE in patients with acute hemorrhagic cerebrovascular accident. Material and methods: the study included 47 patients with acute violation of cerebral circulation for hemorrhagic and mixed types complicated by massive pulmonary thromboembolism of high risk, with "critical" manifestations of right ventricular failure. Depending on the method of PE treatment used, the patients were divided into 2 groups: the study group (17 people), in which endovascular mechanical fragmentation of thromboembols was performed, and the control group (30 people), in which only basic intensive therapy was used. Results: patients of the study group underwent thromboembolic fragmentation in order to transfer embolism of the trunk and the main branches into embolism of smaller branches of the pulmonary artery. Technical success of the procedure (destruction of the central thromboembolus) was achieved in 100% of the cases. 14 patients (82.4%) showed positive clinical dynamics in the form of an improvement in the general condition, a decrease in pressure in the pulmonary artery, and a decrease in the volume of the lesion of the pulmonary bed according to CT angiography. Three patients (17.6%) died in the early postoperative period. In the control group of 30 patients, 25 patients died, hospital mortality was 83.3%. Conclusion: the method of catheter endovascular fragmentation of thrombi for the treatment of "critical" pulmonary embolism in patients with acute hemorrhagic cerebrovascular accident leads to a rapid and safe decrease in pulmonary artery pressure.
|10_X-RAY ENDOVASCULAR TREATMENT OF CRITICAL THROMBOEMBOLISM.pdf||923.72 KB|
Objectives: to evaluate the efficacy and safety of circular radiofrequency ablation of the pulmonary trunk and main pulmonary arteries in patients with severe pulmonary hypertension using a histological study. Materials and methods: for the analysis of autopsy material from non-operated patients, three study groups were identified. Experimental – with chronic pulmonary hypertension with mitral disease and radiofrequency ablation. Comparisons – with severe pulmonary hypertension and without radiofrequency ablation. Control – without pulmonary hypertension and radiofrequency ablation, who died from causes not associated with cardiovascular diseases. Hematoxylin and eosin staining according to Van Gieson was used to visualize the damage to the tissue samples of the vascular wall. The technique of impregnation with silver staining was used to determine the damage to the nerve plexuses and endings. Results: analysis of the results of optical density and the relative average area of argentophilic fibers revealed a decrease in these parameters in the ablation group. In patients of the comparison group, where a high level of pulmonary hypertension was also observed, there was a significant accumulation of argentophilic fibers. Conclusion: histological examination showed an increase in the formation of sympathetic nerves in the adventitia of the pulmonary arteries in severe pulmonary hypertension. The same pulmonary arteries denervation procedure is an effective and safe way of denervation of the sympathetic plexuses located in the adventitia layer of the pulmonary arteries, which is confirmed by histological studies.
|9_HISTOLOGICAL STUDY OF PULMONARY ARTERY DENERVATION.pdf||776.75 KB|
Evaluation of the Features of Microcirculatory Reactions under the Action of Dinitrosyl Iron Complexes in the Norm and on the Model of Thermal Trauma
The actuality of the problem of thermal trauma is determined by its high prevalence. Severe disorders of central, regional and peripheral hemodynamics are developing with a predominant violation of microcirculation and metabolic processes in the body during burn disease. Promising NO donors suitable for biomedical use are dinitrosyl iron complexes (DNIC). The aim of the study was to evaluate the effect of DNIC on the state of microcirculation in normal conditions and on the model of combined thermal trauma (CTT). The experiments were carried out on white male rats of the Wistar line. CTT (contact burn on the area of 20% of the body surface and thermal inhalation exposure to hot air and combustion products for 20-30 seconds) was applied under anesthesia. Animals with CTT were treated daily with intraperitoneal injections of a 10% DNIC solution (1 ml; 0.3 micromol/l). Laser Doppler flowmetry was used to assess the dynamics of the microcirculation state. The physiological and biochemical mechanisms of microcirculation disorders in CTT are revealed in the work. There was an increase in the endothelial, neurogenic and respiratory components of microcirculation, microhemodynamics of the border area of the burn, and the index of the microcirculation bypass. It was shown that when using 0.3 micromol/l of DNIC in rats under normal conditions, there is a decrease in the neurogenic and respiratory components, an increase in perfusion and the myogenic component of the microcirculatory channel. The role of 0.3 micromol/l of DNIC in the normalization of microcirculation in CTT was established.
|8_EVALUATION OF THE FEATURES OF MICROCIRCULATORY REACTIONS.pdf||824.2 KB|
Comparative Evaluation of the Effect of Low-Intensity Electromagnetic Noise Signals in the Microwave Range on the Induction of Metabolic and Vascular Adaptation Reactions in Experimental Thermal Burns
Currently, we continue to actively develop a high-tech rehabilitation method of microwave therapy using sub- and millimeter-wave radiation sources. However, the question of the feasibility of its use in the rehabilitation of patients with burn injuries is not sufficiently studied. In this connection, the works analyzing the effectiveness of the influence of different micro-wave ranges on the nature and degree of development of adaptive metabolic and vascular reactions in the early period of trauma, which affect the outcome of the burn, become particularly relevant. The study was carried out on male rats of the Wistar line under conditions of experimental contact thermal burn of the IIIА degree on an area of 20% of the dorsal surface of the body. A 7-day course of point non-contact exposure to broadband microwave emitters of various ranges with a radiation power of 10 µW on the occipital protuberance area was started after the rats were released from anesthesia when the contact burn was applied. The vascular status, the state of oxidative stress and energy homeostasis were assessed by the intensity of oxidative processes, antioxidant protection, and the total microcirculation index with a wavelet analysis. The obtained data reliably revealed a more pronounced favorable effect on the level of adaptive reactions in the range of 150,179-150.664 GHz, which contains the frequencies of radiation and absorption of nitric oxide. This should be taken into account when choosing frequency-energy parameters and developing a potential method of rehabilitation in the acute period of burn injury.
|7_COMPARATIVE EVALUATION OF THE EFFECT OF LOW-INTENSITY ELECTROMAGNETIC NOISE SIGNALS.pdf||627.07 KB|
Morphological and Functional Properties of Erythrocytes under Stress and Exposure to Low-Intensity Laser Radiation
The work aimed to study the protein spectrum, morpho-functional state of erythrocyte membranes under stress and correction by low-intensity laser radiation. The experiments were carried out in vitro. Low-intensity laser radiation with a wavelength of 830 nm and a power of 90 mw was used for irradiation. Laser therapy was performed using an autonomous laser shower "MarsIK" (NPO "Petrolaser", St. Petersburg). The protein fractions of red blood cells were analyzed by electrophoresis, the morphology of red blood cells by laser interference microscopy, the еletrophoretic mobility of erythrocytes was measured by microelectrophoresis in our modification and the concentration of malondialdehyde in red blood cells by reaction with thiobarbituric acid spectrophotometrically. It is proved that the change of protein fractions in the erythrocyte membrane under stress, a decrease in the amount of spectrin, band 3 protein, glycophorin and ankirin. The stress is characterized by an increase in the number of echinocytes, stomatocytes and degenerative-altered red blood cells. Exposure to LLLT on blood samples determined the recovery of the studied parameters to the control group values (physiological norm). The role of the discovered metabolic changes in RBC in stress and their correction by LLLT is under discussion.
|6_MORPHOLOGICAL AND FUNCTIONAL PROPERTIES.pdf||445.3 KB|
Psychophysiological Markers of Epistemic Evaluation: Evidence from Eye Tracking in Reading Familiar and Unfamiliar Words
The article focuses on identifying specific eye movement parameters during reading unfamiliar words to study the formation of epistemic evaluation. The sample consisted of 40 students. 240 eye-tracking records were registered while the participants were reading 6 texts in Russian. The study revealed that the speed of saccades decreased, and the duration of fixations increased while reading an unknown word. Eye movements at first encounter of a new term may be an indicator of epistemic evaluation formation.
|5_PSYCHOPHYSIOLOGICAL MARKERS OF EPISTEMIC EVALUATION.pdf||467.09 KB|