[The distribution of C-14-actinomycin in rat embryos at different developmental stages (to the problem of the mechanism of the teratogenic effect of actinomycin D)].
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Biomedical subjects
Publications and source records attributed to V S Repin.
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The recent achievements in isolation, primary and long term culturing, cell Immunophenotyping, SAGE--mRNA--profiling, the clonogenic growth parameters of embryonic stem cells and mesenchymal stem cells have been outlined in connection with cell pluripotency and restricted differentiation, mediated by signals both in culture and in situ. Multidisciplinary data obtained by cell biologists, embryologists with recent functional genomic data give the new way for practical implementation of bioimplants derived from embryonic stem cell for cell-replacement therapy.
A short history of embryonic stem cell (ESC) discovery, cell line isolation, phenotyping and cell behavior both in situ and in vitro is outlined. The path of ESC differentiation into restricted specialized cell types mediated by signal network in culture and by grafting cell into recipient tissues is considered. Potentialities of ESC as the generator of spare parts of organs for regenerative medicine and related bioethical issues are briefly outlined.
We studied the behavior and differentiation of human and rat neural stem cells after transplantation in the adult rat brain without immunosuppression. The rat stem cells were isolated from the presumptive neocortex of 15-day-old embryos. The human cells were isolated from the ventricular brain zone of 9-week-old embryos and cultivated for two weeks before transplantation. The results of histomorphological studies suggest that the microenvironment factors did not suppress the growth or development of transplanted stem cells. Both rat and human embryonic multipotent neural cells showed similar behavior and differentiation into neurons and glial cells. After transplantation, they continued to mitotically divide and migrated from the graft area to the surrounding tissue of a recipient brain. The presumptive glial cells migrated preferentially along the capillaries and fibrous structures of the recipient brain. Similar behavior of the rat and human neural stem cells in the microenvironment of the recipient adult rat brain and the absence of immune reaction suggest that the transplantation into the rat brain may serve as a model for studying the developmental biology of the human stem cells.
No decrease in iron-sulphur centers was found in cultured macrophage cells (J774) after the treatment with nitric oxide (10(-7) M NO/10(7) cells) during 5 min. The center content was controlled by the electron spin resonance (ESR) method. The macrophages pretreated with dithionite + methyl viologen showed the formation of dinitrosyl iron complexes (DNIC) with a characteristic ESR signal at g approximately 2.03. The data suggest that loosely bound nonheme iron (free iron) mostly contributes to the formation of these complexes. Iron from iron-containing proteins does not release from these centers under the direct action of nitric oxide. The iron-sulphur centers can be destroyed by the products of nitric oxide oxidation (NO2, N2O3, etc.) as oxidizing and acid agents.
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Protein fractions with dissimilar electrophoretic mobility were identified in Langerhans, islands. In solitory islands, isolated from pancreas of rats with alloxan diabetes as compared with normal rats the protein composition varied distinctly: fractions of "constant" proteins and, specifically, the insulin fraction disappeared completely, total amount of identified fractions was decreased with relative alteration in their mobility. The total protein-synthesizing activity of Langerhans' islands from diabetic animals was 3-4-fold decreased as compared with that of control animals. An effect of "glucose repression" of protein synthesis was observed in isolated Langerhans' islands.
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Effects of trapidil (rocornal) on interaction of human thrombocytes, purified by gel filtration, and the surface covered with fibrillar collagen from calf skin (CCS) were studied using scanning electron microscopy. When the soluble inductors were absent, trapidil did not affect the thrombocyte adhesion. At the same time, trapidil inhibited the shape alterations of laminated thrombocytes, induced by CCS-substrate with simultaneous increase in the ratio of disc-shaped cells and a decrease in laminated thrombocytes. Soluble inductors of the thrombocyte activity (arachidonic acid, stable derivative of prostaglandin endoperoxides U46619 and thrombin) stimulated the cells mass-scale lamination as well as formation of thrombus-like aggregates bound with CCS-substrate. Trapidil prevented completely the effects of exogenous arachidonic acid and of U46619 on interaction of thrombocytes and the substrate but inhibited only by 40-50% the synthesis of thromboxane A2 in the cells induced by arachidonic acid. The drug blocked also an aggregation of thrombocytes in suspension, lamination and formation of aggregates bound with the surface, induced by low but not by high concentrations of thrombin. Possible use of trapidil is discussed.