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排序方式: 共有72条查询结果,搜索用时 15 毫秒
1.
An electron-microscopic study of the topography of carbohydrate residues on the surface of the cell body membrane of cultured spinal neurons was carried out using lectins from wheat (WGA) and snail (HPL), labeled with colloidal gold, as specific molecular probes. Mathematical methods of analysis suggested a set of surface markers, from the distribution of particles observed in electron micrographs of random sections, corresponding to two random functions. Analysis of these functions allows the required quantitative characteristics to be obtained. The Monte Carlo reconstructing model is described, and results of its use (based on the aforementioned experimental data) are demonstrated in the form of "averaged" surface topography of the studied markers in a limited section of the membrane. The results obtained are discussed in connection with cooperative properties of the membrane.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 595–603, September–October, 1991. 相似文献
2.
Models have been developed for the interaction of the pyrrolo[1,2-a]benzimidazole (PBI) antitumor agents with the two-electron activating enzyme DT-diaphorase and the DNA major groove. The DT-diaphorase model and experimental results indicate that the S-enantiomer of 3-carbamido PBI can enantioselect ovarian cancers. The reduced PBI interacts with the DNA major groove at AT base pairs by forming Hoogsteen-like hydrogen bonds. The reduced 3-amino PBI forms three hydrogen bonds in the major groove with the amino group acting as an H-bond donor to the thymine carbonyl. The DNA-binding model will permit the design of major groove recognition agents. 相似文献
3.
L. P. Voytenko I. V. Lushnikova M. V. Skok O. Yu. Lykhmus J. Deuchars G. G. Skibo 《Neurophysiology》2012,43(5):394-396
As is known, hippocampal pyramidal neurons are highly sensitive to cerebral ischemia, while some other hippocampal neurons
(particularly, interneurons) survive and keep their functional activity under these conditions for a longer time. We studied
interneurons of the rat hippocampal organotypic culture after 30-min-long oxygen-glucose deprivation (OGD) using immunohistochemical
approaches. Four and 24 h after OGD, the somata of interneurons with no signs of degeneration (revealed by propidium iodide,
PI, staining) were immunopositive to antibodies against glutamic acid decarboxylase isoform 67 (GAD67) and to an extracellular
domain of a7 nicotinic acetylcholine receptor (nAChR) but negative with respect to choline acetyltransferase (ChAT). GAD67/nAChR-positive
interneurons were abundant within all layers of the hippocampal CA1-CA4 zones and also in the dentate gyrus. Co-localized GAD67/nAChR immunopositivity was also observed on numerous punctuate terminals
close to the somata of pyramidal neurons stained by PI. After OGD followed by incubation with a blocker of gap junctions,
carbenoxolone, only single PI-stained units were revealed in the pyramidal layer. In experiments with connexin 36 cyan fluorescent
protein (Cx36-CFP) on gene-reporter mice, we have found that the combination of GAD67/nAChR immunopositivity and ChAT negativity
in the hippocampus is specific for the interneuronal somata expressing Cx36-CFP, a component of electrotonic gap contacts
in the neuronal networks. Our results indicate that OGD-resistant hippocampal interneurons display co-localization of GAD67,
a7 nAChR, and Cx36-CFP. By these neurochemical features, OGD-resistant neurons can be classified as inhibitory GABA-ergic
acetylcholine-sensitive interneurons able to couple electrotonically with other hippocampal units through Cx36-CFP-containing
gap junctions. The existence of hippocampal interneurons coexpressing the above factors shows that further investigations
towards elucidation of cooperative endogenic mechanisms responsible for cerebral neuroresistance are expedient. 相似文献
4.
Pivneva T Haas B Reyes-Haro D Laube G Veh RW Nolte C Skibo G Kettenmann H 《Cell calcium》2008,43(6):591-601
Ca(2+) signaling is the astrocyte form of excitability and the endoplasmic reticulum (ER) plays an important role as an intracellular Ca(2+) store. Since the subcellular distribution of the ER influences Ca(2+) signaling, we compared the arrangement of ER in astrocytes of hippocampus tissue and astrocytes in cell culture by electron microscopy. While the ER was usually located in close apposition to the plasma membrane in astrocytes in situ, the ER in cultured astrocytes was close to the nuclear membrane. Activation of metabotropic receptors linked to release of Ca(2+) from ER stores triggered distinct responses in cultured and in situ astrocytes. In culture, Ca(2+) signals were commonly first recorded close to the nucleus and with a delay at peripheral regions of the cells. Store-operated Ca(2+) entry (SOC) as a route to refill the Ca(2+) stores could be easily identified in cultured astrocytes as the Zn(2+)-sensitive component of the Ca(2+) signal. In contrast, such a Zn(2+)-sensitive component was not recorded in astrocytes from hippocampal slices despite of evidence for SOC. Our data indicate that both, astrocytes in situ and in vitro express SOC necessary to refill stores, but that a SOC-related signal is not recorded in the cytoplasm of astrocytes in situ since the stores are close to the plasma membrane and the refill does not affect cytoplasmic Ca(2+) levels. 相似文献
5.
A procedure for computer simulation is proposed, which allows one to quantitatively characterize the spatial distribution
of synaptic vesicles in presynaptic terminals (PST) using ultrathin sections of such terminals. The procedure includes three
stages: simulation, topographical analysis, and comparison. At the first stage, the spatial distribution of vesicles within
a PST and the process of random sectioning of it are simulated using the corresponding mathematical model. At the second stage,
the topographical distribution of vesicle profiles within the plane of PST section is estimated; three respective approaches
have been used: (i) nearest neighbor distance distribution; (ii) minimal spanning tree; and (iii) Voronoi paving. At the third
stage, the simulated parameters are compared with the parameters of native terminal sections; when the coincidence of these
two parameter groups is satisfactory, we believe that the simulated spatial distribution agrees with the real distribution.
The software for the procedure is written in C++ programing langage. The results of a pilot study on ultrathin sections of
cultured rat hippocampal neurons showed that the method offers broad possibilities for spatial interpretation and quantitative
characterization of distributions of synaptic vesicles. 相似文献
6.
A morphometric electron microscope study was carried out on the ultrastructure of 140 presynaptic terminals (PT) in the dorsal horn of the cat spinal cord. Some spatial characteristics of mitochondria and active zones (AZ) for these PT were examined using statistical stereological analysis techniques. The distribution of 3-dimensional mitochondrial radii was determined, together with average mitochondrial volume, mean area of the external membrane, and average numbers of the test population falling within the PT. Distribution of diameters and estimates of mean area of AZ were obtained, as well as of mean value of synaptic clefts. The relationship between findings from morphometric research and parameters of processes underlying ionic transmembrane diffusion and accumulation is discussed.Dnepopetrovsk State University. A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR. Translated from Neirofiziologiya, Vol. 21, No. 6, pp. 741–747, November–December, 1989. 相似文献
7.
Statistical parameters characterizing the structure of the vesicular apparatus of presynaptic endings (PE) were determined from the findings of ultrastructural morphometric analysis of 135 synapses in the dorsal horn of the cat spinal cord. Quantitative estimates of vesicles in the PE (averaging about 470) were obtained, based on stereometric principles. The bimodal pattern of distribution of distances from the center of each vesicle to the nearest portion of the active zone was demonstrated — viewed as the structural correlate of the two-pool model of transmitter storage. The possibility of classifying PE according to the sign of vesicle spatial distribution is discussed as well as the relationship between this distribution and parameters of transmitter mobilization and synaptic release.Dnepropetrovsk State University. A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 5, pp. 597–605, September–October, 1989. 相似文献
8.
Rational Design of Pyrrolo[1,2-a]benzimidazole-Based Antitumor Agents Targeting the DNA Major Groove
Models have been developed for the interaction of the pyrrolo[1,2-a]benzimidazole (PBI) antitumor agents with the two-electron activating enzyme DT-diaphorase and the DNA major groove. The DT-diaphorase model and experimental results indicate that the S-enantiomer of 3-carbamido PBI can enantioselect ovarian cancers. The reduced PBI interacts with the DNA major groove at AT base pairs by forming Hoogsteen-like hydrogen bonds. The reduced 3-amino PBI forms three hydrogen bonds in the major groove with the amino group acting as an H-bond donor to the thymine carbonyl. The DNA-binding model will permit the design of major groove recognition agents. 相似文献
9.
We analyzed structural rearrangements of synaptic contacts in the stratum radiatum of the CA1 area of cultured rat hippocampal slices under conditions of the development of potentiation of synaptic transmission induced
by short-term (10 min) oxygen-glucose deprivation (OGD). Studies were carried out using electron microscopy and 3D reconstruction
of cellular compartments. Within the 1st h after OGD, we observed increases in the volume of pre-synaptic terminals and post-synaptic
spines and also in the area of postsynaptic densities (PSDs) in both asymmetric excitatory and symmetric inhibitory synapses,
especially in the case were the PSD was perforated. We also observed significant activation of glial cells (increases in their
volume and area of contacts of their processes with the components of synapses). Therefore, OGD results in activationassociated
structural rearrangements of both excitatory and inhibitory synapses of the hippocampal CA1 area. Such rearrangements are accompanied by a clearly pronounced reaction of the glia, which correlates with an important
role of the latter in modulation of the functioning of neurons. 相似文献
10.
Reactions of microglia and astrocytes in the sensorimotor cortex of the rat resulting from a cortex tissue lesion made by
a free-electron laser were studied with immunohistochemical techniques. Lipocortin-1 (LC1) was used as a microglia marker,
while S100-β glycoprotein was used to identify astrocytes. Three days after laser exposure, the quantity of LC1-positive microglial
cells observed in the cortex along the edge of the laser lesion was 30% larger than that in the control. There was no reaction
of S100-β-positive astrocytes observed within this time interval. Six days after laser exposure, the density of LC1-positive
activated microglia along the edge of the laser lesion further increased (210% of the above index), and the density of S100-β-positive
astrocytes also slightly increased (by 30%, compared with the control). The data provide evidence that LC1-positive microglia
react to a laser-made cortex injury more rapidly and intensively than astrocytes. It can be supposed that namely LC1 plays
the role of an anti-inflammatory messenger in cortex microglial cells after laser exposure. In general, the pattern of microglia
and astrocyte reactions is indicative of comparatively mild traumatization of the cortex tissue after laser irradiation. 相似文献