Structure-resistive property relationships in thin ferroelectric BaTiO[Formula: see text] films.

A combined study of local structural, electric and ferroelectric properties of SrTiO[Formula: see text]/La[Formula: see text]Sr[Formula: see text]MnO[Formula: see text]/BaTiO[Formula: see text] heterostructures was performed by Piezoresponse Force Microscopy, tunneling Atomic Force Microscopy and Scanning Tunneling Microscopy in the temperature range 30-295 K. The direct correlation of film structure (epitaxial, nanocrystalline or polycrystalline) with local electric and ferroelectric properties was observed. For polycrystalline ferroelectric films the predominant polarization state is defined by the peculiarity of screening the built-in field by positively charged point defects. Based on Scanning Tunneling Spectroscopy results, it was found that a sequent voltage application provokes the modification of local resistive properties related to the redistribution of point defects in thin ferroelectric films. A qualitative analysis of acquired Piezoresponse Force Microscopy, tunneling Atomic Force Microscopy and Scanning Tunneling Microscopy images together with Scanning Tunneling Spectroscopy measurements enabled us to conclude that in the presence of structural defects the competing processes of electron injection, trap filling and the drift of positively charged point defects drives the change of resistive properties of thin films under applied electric field. In this paper, we propose a new approach based on Scanning Tunneling Microscopy/Spectroscopy under ultrahigh vacuum conditions to clarify the influence of point defects on local resistive properties of nanometer-thick ferroelectric films.

[Hydrogen Sulfide Donor NaHS Protects Mesenchymal Stem and Melanoma Cells from the Negative Effects of Infrared Laser Irradiation].

We have established earlier that 835-nm infrared laser irradiation results in a dose-dependent growth inhibition of human mesenchymal stem and melanoma cells and is able to induce cell death. In this work we have demonstrated that hydrogen sulfide donor NaHS is able to protect both cell types from the negative action of laser irradiation and the magnitude of protection depends on NaHS concentration. The mechanism of cell protection by NaHS is primarily attributable to its effects on intracellular processes occurring after irradiation, since the protective effect does not depend on whether NaHS is added before or after irradiation. Moreover, NaHS is able to exert its protective effect even when added 6 hours post irradiation.

[Effect of Myocardial Reperfusion on Ischemic Mitral Regurgitation in Patients with Acute Myocardial Infarction].

BACKGROUND: During the restoration of blood flow in the ischemic area of the myocardium, viable cardiomyocytes are damaged over a few minutes of tissue reperfusion (reperfusion myocardial damage). It is known that ischemic mitral regurgitation (IMR) develops in 11-19 % of patients who have undergoing percutaneous coronary intervention (PCI) in symptomatic coronary heart disease (CHD). To present day, the influence of myocardial reperfusion on IMR in patients with acute myocardial infarction (AMI) is not fully understood. OBJECTIVE: To study dynamics of quantitative indicators of IMR in patients with AMI after myocardial reperfusion. MATERIALS AND METHODS: We included in this study 68 patients with AMI and IMR aged 36-79 years, who were hospitalized in cardiac intensive care unit of the Moscow S. S. Yudin hospital in 2016. All patients before and on the 7th day after PCI underwent doppler echocardiography study with calculation of quantitative parameters of IMR and index of local contractility (ILC) of the left ventricle (LV). RESULTS: Three groups of patients were identified based on the analysis of the dynamics of quantitative parameters of IMR after myocardial reperfusion: group 1 - patients who had a decrease in IMR (n=23, 33.8 %), group 2 - patients with increase of IMR (n=28, 41.1 %), group 3 - patients with unchanged IMR (n=17, 25.1 %). The study of systolicLV function in all patients before PCI revealed moderately decreased ejection fraction (EF) (mean 49.05±1.19 %). On day 7 after myocardial reperfusion in group 2 we detected significant increases of end-diastolic volume (EDV), end-systolic volume (ESV), and the volume of the left atrium (LA), while in groups 1 and 3 these indexes remained unchanged. LV ILC did not differ between three groups, both at admission and on day 7 after reperfusion (p>0.05). There was no correlation between severity of IMR and ILC (correlation coefficient 0.24). CONCLUSION: Dynamics of quantitative parameters of IMR in 7 days after myocardial reperfusion in patients with AMI without endogenous and drug protection of the myocardium from reperfusion injury was multidirectional. IMR decreased in 33.8, increased in 41.1 and did not change in 25.1 % of patients. Systolic function and LV ILC underwent no significant dynamics.

Reversible and irreversible alterations of the optical thickness of PQ/PMMA volume recording media samples. Part 2: mathematical modeling.

A theoretical study of phenanthrenequinone-doped polymethyl methacrylate (PQ/PMMA) samples parameter changes during irradiation is presented. The research has been carried out on the basis of the experimental study (Part 1, [Appl. Opt.56, 7351 (2017)APOPAI0003-693510.1364/AO.56.007351]) and a mathematical model that describes space-time reversible and irreversible light-induced changes of the PQ/PMMA sample parameters during exposition. Based on the numerical modeling results and the use of analytical dependencies, a number of practically important characteristics of the PQ/PMMA sample-exposure process are considered: conversion-induction period of phenanthrenequinone into a photoproduct, Δtind; bleaching time of a sample, tbl; and thermal nonlocality of photoresponse, δlT. It is shown that the values Δtind and tbl are on the order of tens and hundreds of seconds, respectively, and can be comparable to the exposure time. It is established that temperature increase leads to δlT value change by hundreds of nanometers and can cause considerable deformation of the interference structure under recording. The sample heating during exposition is considered in detail, and an algorithm for estimation of the maximum temperature increase to be used in experiments is proposed. Recommendations are made for the reduction of negative influence of sample heating on the parameters of recorded holograms.

[Cytotoxic Effect of Low-Intensity Infrared Laser Irradiation on Human Melanoma Cells].

Continuous low-intensity laser irradiation (LILI) affects the state of cells in culture, including their proliferation rate. Data collected with various cell models vary significantly, but most studies have reported positive effects of LILI on cell proliferation. The effects of continuous infrared LILI (835 nm) was studied using three independent different melanoma cell lines. The LILI effect was shown to strongly depend on the irradiation dose. Higher doses (230 kJ/m^(2)) significantly suppressed the cell growth. A further increase in LILI dose led to a significant cytotoxic effect, which increased disproportionately quickly with the increasing light intensity. Human mesenchymal stem cells (MSCs) were found to be significantly more resistant to the cytotoxic effect of higher-dose LILI. Importantly, the effects were not due to the difference in culture conditions. Control experiments showed that 15 non-melanoma tumor cell lines were more resistant to LILI than melanoma cells. Selective sensitivity of melanoma cells to LILI in vitro was assumed to provide a basis for LILI-based approaches to melanoma treatment.

Reversible and irreversible alterations of the optical thickness of PQ/PMMA volume recording media samples. Part I: Experiment.

Experimental research into changes of the optical thickness of phenanthrenequinone-doped polymethyl methacrylate samples in the process of irradiation by a 473 nm laser is presented. It was demonstrated that heating-induced reversible changes lead to a decrease in the optical thickness. The temperature coefficient of the relative changes of the optical thickness was measured to be -1.40×10-5 К-1, which matches the data published by other authors. It is also established that the irreversible changes induced by the photochemical transformation lead to an increase in the optical thickness outside of the absorption band of the samples (λ>530 nm), where the relative change of which at λ=532 nm is +3.7×10-5. It was demonstrated that the reversible and irreversible changes do not compensate for each other in the process of sample exposure.

Controlled formaldehyde fixation of fibronectin layers for expansion of mesenchymal stem cells.

Extracellular cell matrices deposited by cells stimulate cell proliferation. However, their generation is cumbersome and time consuming. We show here that controlled fixation of fibronectin layers after coating culture vessels significantly enhances expansion of murine and human mesenchymal stem cells (MSCs) and, to a lesser extent, primary fibroblasts. In contrast, fibronection fixation did not stimulate proliferation of established cancer cell lines. Fixed vitronectin or collagen IV layers also enhanced proliferation of murine MSCs. Thus, controlled formaldehyde fixation of layers formed by fibronectin or some other extracellular matrix components represents a simple and reproducible way to enhance proliferation of primary cells.

Recombinant HSP70 and mild heat shock stimulate growth of aged mesenchymal stem cells.

Heat shock proteins including the major stress protein HSP70 support intracellular homeostasis and prevent protein damage after a temperature increase and other stressful environmental stimuli, as well as during aging. We have shown earlier that prolonged administration of recombinant human HSP70 to mice exhibiting Alzheimer's-like neurodegeneration as well as during sepsis reduces the clinical manifestations of these pathologies. Herein, we studied the action of recombinant human HSP70 on young and aged mouse mesenchymal stem cells (MSCs) in culture. The results obtained indicate that HSP70 at concentrations of 2 µg/ml and higher significantly stimulates growth of aged but not young MSCs. A similar effect is produced by application of a mild heat shock (42 °C 5 min) to the cells. Importantly, responses of young and aged MSCs to heat shock treatment of various durations differed drastically, and aged MSCs were significantly more sensitive to higher heat stress exposures than the young cells. Western blotting and protein labeling experiments demonstrated that neither mild heat shock nor exogenous HSP70 administration resulted in significant endogenous HSP70 induction in young and aged MSCs, whereas mild heat shock increased HSC70 levels in aged MSCs. The results of this study suggest that the administration of exogenous HSP70 and the application of mild heat stress may produce a certain "rejuvenating" effect on MSCs and possibly other cell types in vivo, and these interventions may potentially be used for life extension by delaying various manifestations of aging at the molecular and cellular level.

[Development and preclinical studies of insulating membranes based on poly-3-hydroxybutyrate-co-3-hydroxyvalerate for guided bone regeneration].

Bone tissue damages are one of the dominant causes of temporary disability and developmental disability. Currently, there are some methods of guided bone regeneration employing different osteoplastic materials and insulation membranes used in surgery. In this study, we have developed a method of preparation of porous membranes from the biopolymer poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), produced by a strain of Azotobacter chroococcum 7B. The biocompatibility of the porous membranes was investigated in vitro using mesenchymal stem cells (MSCs) and in vivo on laboratory animals. The cytotoxicity test showed the possibility of cell attachment on membrane and histological studies confirmed good insulating properties the material. The data obtained demonstrate the high biocompatibility and the potential application of insulating membranes based on PHBV in bone tissue engineering.

[CONTENT OF OXIDATIVE STRESS MARKERS IN BLOOD PLASMA UNDER THE ACTION OF EXTRACTS OF GRATIOLA OFFICINALIS L., HELICHRYSUM ARENARIUM (L.) MOENCH, AND ANTHOCYANIN FORMS OF ZEA MAYS L].

The effect of aqueous solutions of dry ethanol extracts of Gratiola officinalis L., Helichrysum arenarium (L.) Moench, and anthocyanin forms of Zea mays L. on the dioxidin-induced lipid peroxidation in blood has been studied on rats. It is established that all these extracts are capable of reducing the amount of avera- ge-mass (AM) molecules and malonic dialdehyde (MDA) in rat blood plasma. The extract of Gratiola officinalis L. reduces the concentration of AM and MDA moleules by 43%. The extract of Helichrysum arenarium (L.) Moench reduces the concentration of AM molecules on the average by 18.66% (within 9.22 -34.81%) and MDA by 49.36% (within 34.12-79.75%). The Extract of anthocyanin forms of Zea mays L. does not reduce the concentration of AM mo- lecules, but reduces the amount of MDA in the blood of rats on average by 27.88% (within 21.58-37.82%) (p < 0.01).

Culturing of Mouse Mesenchymal Stem Cells on Poly-3-Hydroxybutyrate Scaffolds.

We studied the possibility of long-term culturing of mouse mesenchymal stem cells on a porous scaffold made of biocompatible polymer poly-3-hydroxybutyrate. The cells remained viable for at least 2 months and passed more than 65 population doublings in culture. Culturing on the scaffold did not change surface phenotype of cells. 3D poly-3-hydroxybutyrate scaffolds are appropriate substrate for long-term culturing of mesenchymal stem cells.

[Biocompatibility of electrospun poly(3-hydroxybutyrate) and its composites scaffolds for tissue engineering].

Development of biodegradable polymers-based scaffolds for tissue engineering is a promising trend in bioengineering. The electrospun scaffolds from poly(3-hydroxybutyrate) (PHB) were produced using different additives that changed the physical and chemical characteristics of the products. As a result, the construct consisting of interwoven threads of different diameter (0.8-3.4 mm) were obtained, the smallest diameter was observed in the threads from the PHB using tetrabutilammonium iodide (TBAI) and titanium oxide II (TiO2) as additives. Mesenchymal stem cells (MSC) were cultivated on the scaffolds for the biocompatibility evaluation of obtained materials. Cells viability was determined by the XTT assay test. It was shown that the scaffold from the interwoven threads of lowest diameter is most favorable for MSC growth in comparison with the polymer film and scaffolds from the threads of larger diameter. Thus, it was shown that the biocompatibility of electrospun PHB scaffolds depended on their microstructure. The obtained data can be used for development of scaffolds for tissue engineering.

Effect of galectin-1 on apoptosis of CD4(+) lymphocytes differentiated in vitro towards regulatory T cells.

We studied the effect of galectin-1 on apoptosis of CD4(+) lymphocytes intact and in vitro differentiated towards regulatory T cells. An increase in the content of apoptotic CD4(+) lymphocytes was observed after exposure of intact cells with 15 ng/ml galectin-1 and after exposure of regulatory T cells with 10 and 15 ng/ml galectin-1. Apoptosis of regulatory T cells induced by galectin-1 was accompanied by an increase in the content of proapoptotic protein Bad.

[The effect of poly(3-hydroxybutyrate) modification by poly(ethylene glycol) on the viability of cells grown on the polymer films].

A biodegradable polymer of bacterial origin, poly(3-hydroxybutyrate) (PHB), is intensively studied as biomaterial for tissue engineering. However, factors determining its biocompatibility still require better understanding. To analyze the PHB films biocompatibility, the polymer material was modified by hydrophilic polymer, poly(ethylene glycol) 300 (PEG). The blends PHB/PEG with different PEG content (10, 20, 30 and 50%) were produced by subsequent incubation in water resulted in removal of 95% PEG. The surface roughness and hydrophilicity were studied by atomic force microscopy (AFM) and contact angle "water-polymer" measurement, respectively. The film biocompatibility on cell culture of COS-1 fibroblasts was studied in vitro. It was shown that both roughness and hydrophobicity are directly proportional to initial PEG content in the PHB/PEG blends. The growth rate of COS-1 fibroblasts on polymer films is determined by combination of two basic physicochemical properties of the polymer surface: the roughness and hydrophilicity. The optimal roughness requred for COS-1 cells growth is the average roughness more than 25 nm, whereas the limit values of the contact angle "water-polymer" that was responsible for relatively high cell viability were not found. These data indicate that the film surface roughness had the greatest effect on the cell growth, whereas the increase in the polymer surface hydrophilicity caused the additional positive effect on viability of attached cells. Thus, the modification of PHB polymer material by PEG resulted in the improved viability of cells cultivated on the polymer films in vitro. The obtained data can be used for development of such medical devices as surgeon patches and periodontal membranes.

[Mitral valve remodeling in patients with acute myocardial infarction and ischemic mitral regurgitation].

We have studied alterations of mitral valve geometry and quantitative parameters of mitral regurgitation in 130 patients with acute myocardial infarction in acute and subacute stages of the disease. Quantitative data of mitral regurgitation have been assessed using two quantitative Doppler techniques--proximal isovelocity surface area method (PISA-method) and quantitative Doppler technique (Q-DE-method). As a result of the research we have received data showing that in patients with acute myocardial infarction and ischemic mitral regurgitation mitral valve remodeling occurs with deformation of mitral structures inducing mitral regurgitation. We have observed correlation between degree of ischemic mitral regurgitation and structural valve alteration in patients with acute myocardial infarction.

[Bioelectrical activity and automatic properties of different parts of a two-chambered heart]. / Issledovanie bioélektricheskoi aktivnosti i avtomaticheskikh svoistv razlichnykh otdelov dvukhkamernogo serdtsa

Two pacemakers localized in sinoatrial and atrioventricular valves were revealed in the tench heart. In their absence, the ventricular and sometimes the atrial myocardium are capable of initiating the automaticity. Pacemaker's cells of the sinoatrial valve are surrounded by specific area similar to sinoauricular ring in amphibia or sino-caval region in mammals. Characteristics of the action potential in different parts of the tench heart are presented.