Расчет ГИН по схеме Аркадьева-Маркса

Объектом исследования является генератор импульсного напряжения по схеме Аркадьева-Маркса. Цель работы: спроектировать и рассчитать генератор импульсных напряжений. В процессе работы рассчитаны количественные значения элементов ГИНа: значения коэффициентов использования разрядной схемы и волны; емкость и индуктивность конденсатора; количество ступеней; фронтовое и разрядное сопротивления. Был выполнен расчет ресурсов, ставки налогов, отчислений. Так же было описаны рабочее место и законодательные и нормативные документы.The object of study is the generator of pulse voltage according to the scheme Arkadiev-Marx. Objective: to design and calculate the voltage impulse generator. In the process, the calculated quantitative values of the elements of a Hin: the coefficients of use of the discharge circuit and wave; the capacitance and inductance of the capacitor; number of steps; the front and discharge resistors. Calculated resources, tax rates, deductions. As described workplace and legislative and regulatory documents

Mesodermal fate decisions of a stem cell: the Wnt switch

Stem cells are a powerful resource for cell-based transplantation therapies in osteodegenerative disorders, but before some kinds of stem cells can be applied clinically, several aspects of their expansion and differentiation need to be better controlled. Wnt molecules and members of the Wnt signaling cascade have been ascribed a role in both these processes in vitro as well as normal development in vivo. However some results are controversial. In this review we will present the hypothesis that both canonical and non-canonical signaling are involved in mesenchymal cell fate regulation, such as adipogenesis, chondrogenesis and osteogenesis, and that in vitro it is a timely switch between the two that specifies the identity of the differentiating cell. We will specifically focus on the in vitro differentiation of adipocytes, chondrocytes and osteoblasts contrasting embryonic and mesenchymal stem cells as well as the role of Wnts in mesenchymal fate specification during embryogenesis

Ca2+-induced exocytosis in individual human neutrophils: high- and low-affinity granule populations and submaximal responses.

We have investigated Ca2+-induced exocytosis from human neutrophils using the whole cell patch-clamp capacitance technique. Microperfusion of Ca2+ buffer solutions (<30 nM to 5 mM free Ca2+) through the patch-clamp pipette revealed a biphasic activation of exocytosis by Ca2+. The first phase was characterized by high affinity (1.5-5 microM) and low apparent cooperativity (<=2) for Ca2+, and the second phase by low affinity (approximately 100 microM) and high cooperativity (>6). Only the second phase was accompanied by loss of myeloperoxidase, suggesting that the low-affinity exocytosis reflected release of peroxidase-positive (primary) granules, while the high-affinity exocytosis reflected release of peroxidase-negative (secondary and tertiary) granules. At submaximal Ca2+ concentrations, only a fraction of a given granule population was released. This submaximal release cannot simply be explained by Ca2+ modulation of the rate of exocytosis, and it suggests that the secretory response of individual cells is adjusted to the strength of the stimulus. The Ca2+ dependence of the high- and low-affinity phases of neutrophil exocytosis bears a resemblance to endocrine and neuronal exocytosis, respectively. The occurrence of such high- and low-affinity exocytosis in the same cell is novel, and suggests that the Ca2+ sensitivity of secretion is granule-, rather than cell-specific

Micronuclei containing whole chromosomes harbouring the selectable gene do not lead to mutagenesis.

Loss of heterozygosity is one genetic change observed in many tumours. We do not know whether the loss of chromosomal material through micronucleus formation is a viable mechanism associated with, and possibly leading to, genetic disease. Previously, we treated L5178Y mouse lymphoma cells with four aneugens. Although these aneugens induced micronuclei containing predominantly whole chromosomes, they did not induce mutations at Tk1, the selectable gene, under the same non-toxic conditions in which they induced micronuclei. This suggested that the induction of micronuclei containing whole chromosomes was not an early event leading to phenotypically expressed mutations in these cells under the conditions used. However, it is possible that chromosome 11, on which Tk1 resides, may be under-represented in the micronucleus population. To find out the frequency of induction of micronuclei containing chromosome 11, we applied fluorescence in situ hybridization using a chromosome 11 paint to micronuclei induced by colcemid and vinblastine. We found that the numbers of micronuclei containing chromosome 11 are more than sufficient to be detectable as mutations if these micronuclei lead to viable mutants. We conclude that the formation of micronuclei containing whole chromosomes does not lead to viable, dividing mutants in this system

Chemoattractant-induced respiratory burst: increases in cytosolic Ca2+ concentrations are essential and synergize with a kinetically distinct second signal.

The role of the cytosolic free Ca2+ concentration ([Ca2+]c) and its relationship to other second messengers in the signalling between chemoattractant [e.g. N-formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLP)] receptors and the NADPH oxidase is still poorly understood. In this study, we have used thapsigargin, an inhibitor of the Ca2+-ATPase of intracellular stores, as a tool to selectively manipulate Ca2+ release from intracellular stores and Ca2+ influx across the plasma membrane. We thereby temporarily separated the Ca2+ signal from other signals generated by fMLP and analysed the consequences on the respiratory burst. Under all conditions investigated, the extent of fMLP-induced respiratory burst activation was critically determined by [Ca2+]c elevation. fMLP was unable to activate the respiratory burst without [Ca2+]c elevation. Thapsigargin-induced Ca2+ influx activated the respiratory burst in the absence of fMLP, but only to approx. 20% of the values observed in the presence of fMLP. The second signal generated by fMLP did not activate the respiratory burst by itself, but acted in synergy with [Ca2+]c elevation. The second signal was long lasting (>15 min) provided that there was no rise in [Ca2+]c and that the receptor was continuously occupied. The second signal was inactivated by high [Ca2+]c elevation. Our results demonstrate that [Ca2+]c elevations are an essential step in the signalling between the fMLP receptor and NADPH oxidase. They also provide novel information about the properties of the second Ca2+-independent signal that activates the respiratory burst in synergy with [Ca2+]c

Parallel Acquisition of Plasma Membrane Ultrastructure and Cytosolic Protein Localisation in Cultured Cells via Correlated Immunogold SEM

Scanning electron microscopy (SEM) takes advantage of distinct detectors to visualise secondary and back-scattering electrons. Here, we report an integrated approach that relies on these two detection methods to simultaneously acquire correlated information on plasma membrane topography and curvature-sensitive cytosolic protein localization in intact cell samples. We further provide detailed preparation and staining protocols, as well as a thorough example-based discussion for imaging optimisation. Collectively, the presented method enables rapid and precise analysis of cytosolic proteins adjacent to cellular membranes with a resolution of ~100 nm, without time-consuming preparations or errors induced by sequential visualisation present in fluorescence-based correlative approaches