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  • 1
    ISSN: 1432-0827
    Schlagwort(e): Osteoblast-like cells ; Gap junctions ; Connexin43 ; Electrical and dye coupling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The structure of gap junctions in osteoblast-like cells (OBs) and the connexins (cx) that build up these structures were characterized by ultrastructural, immunocytochemical, and molecular techniques. Ultrastructural studies revealed numerous gap junctions which were mostly located on processes of neighboring cells. Immunofluorescence labeling using two different antibodies (specific to mouse live cx26 and cx32 and to a peptide-specific rat heart gap junction protein cx43) gave evidence that in OBs, gap junctions consist mainly of cx43. The presence of cx43 in cultured OB was also confirmed by Western blot analysis. Dye-coupling with Lucifer yellow led to a staining of up to 30 neighboring cells. Parallel intracellular recordings showed that membrane potential amplitude changes (4–5 mV) are typically related to those in the coupled cells. Thus, there is morphological and functional evidence for intercellular communication between OB in culture. OBs in culture express the same connexins as observed in vivo and may serve as a model to investigate electrophysiological events in response to different stimulation signals.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1432-0878
    Schlagwort(e): Key words Inner ear ; Gap junctions ; Connexins ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Gap junction channels which are responsible for direct intercellular communication are composed of connexin proteins. Different connexins are distributed in a tissue-specific manner. Up to now only connexin26 has been identified to be widely expressed in the inner ear. In order to investigate the role of additional gap junction proteins, the expression of connexin30 and 43 was investigated in the rat cochlea. Connexin26 and connexin30 were both expressed in the spiral limbus, the spiral ligament, the stria vascularis and between supporting cells of the organ of Corti. Double-labeling experiments suggest that both connexins are partly colocalized between cells. Weak staining of connexin43 could only be detected in the stria vascularis, the spiral ligament and between organ of Corti supporting cells. The corresponding transcripts for connexin26, 30 and 43 could be detected by Northern blot analysis. The expression of different gap junction channels in the cochlea suggests functional diversity. Gap junctions in the inner ear may control ion concentrations of cochlear fluids or act as conduits through which glucose and other metabolites diffuse.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 241 (1985), S. 325-331 
    ISSN: 1432-0878
    Schlagwort(e): Vagina ; Estrous cycle ; Tight junctions ; Tracer studies ; Freeze-fracture ; Guinea pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the present study the permeability barriers of the multilayered vaginal epithelium were examined using tracer perfusion techniques, freeze-fracture and thin sectioning. During diestrus and proestrus the upper layers of mucified epithelial cells exhibit tight-junctional belts, which restrict tracer molecules such as lanthanum and horseradish peroxidase. When the highly mucified cells begin to degenerate toward the end of proestrus the underlying epithelium is already keratinized as typical for estrus. The keratinized epithelial cells have a tight-junctional network that joins the basal plasma membranes with the apical membranes of subjacent cells and blocks paracellular diffusion of the tracer molecules. During conversion of the cornified epithelium to a mucified epithelium in metestrus the intercellular space of the epithelium is stained by tracer molecules even though tight-junctional belts can be observed. These results indicate that during cyclic changes of the vaginal epithelium tight junctions can, in general, be considered for the restriction of paracellular diffusion. In metestrus, however, junctions become functionally leaky although they remain morphologically intact. Intercellular lipids, which are normally common in cornified epithelia, are extremely rare and cannot constitute an effective barrier to diffusion in the vagina of the guinea pig. The significance of a strategy that bases the regulation of the permeability on tight junctions rather than on intercellular lipids is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 252 (1988), S. 123-132 
    ISSN: 1432-0878
    Schlagwort(e): Uterine epithelium ; Cell culture ; Proteins ; Ultrastructure ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Morphological and biochemical changes occurring in rabbit endometrial epithelial cells when placed in culture were investigated. Cells were examined by scanning- and transmission electron microscopy and freeze-fracture. Morphologically, cultured cells are shorter and broader than the columnar epithelial cells in vivo, but retain their polarity as indicated by the presence of apical microvilli and a well-developed junctional belt. To study changes in biochemical function, proteins synthesized by cells in primary culture were analyzed by two-dimensional gel electrophoresis. Proteins were labeled during a 24-h incubation with 35S-methionine and gels examined by fluorography. The pattern of proteins changed after cells had been in culture for 48 h. On day 3 new proteins were synthesized and several protein species labeled during days 1 or 2 of culture, including uteroglobin, no longer appeared. On days 3–8 of culture the protein patterns were similar. Addition of progesterone, estradiol, prolactin, or combinations of these hormones to the culture medium for 24–144 h failed to elicit consistent changes in the pattern of labeled proteins established after 3 days of culture. Minor differences in protein patterns among unrelated cultures appear to have been derived from the original cells of the culture. These results indicate that after 48 h in primary culture, cells grown in vitro resemble endometrial epithelial cells morphologically, but no longer reflect functionally the character of epithelial cells in the uterus.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1432-0878
    Schlagwort(e): Harderian gland ; Rabbit ; Exocytosis ; Junctions ; Freezefracture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Membrane specializations of the cells of the red and white lobe of the Harderian gland, especially membrane differentiations involved in exocytosis, as well as granule interactions were investigated by means of the freeze-fracture and thin-section techniques. Gap junctions are numerous between both types of glandular cells. Tight junctions consist of about five strands, loosely arranged and often fragmented. Large secretion droplets of both cell types containing different kinds of lipids are formed by fusion. The adjacent granule bilayers are devoid of intramembrane particles (IMP) at the fusion site. During exocytosis the large secretion droplets of the red-lobe cells often cause the plasma membrane to bulge out extensively into the lumen. The overlying plasmalemma as well as the granule membrane show IMP-free patches. Secretion granules of the white-lobe cells, smaller in volume, deform the plasma membrane only slightly when lying in close apposition. The distribution of IMP on the plasmalemma of the white-lobe cells remains random at the side of impending fusion. Thin sections sometimes reveal, in this stage of exocytosis, a single unit membrane but never a pentalaminar structure. Both cellular components of the Harderian gland, when pretreated identically, show different membrane reactions with respect to IMP-clearing during exocytosis. This leads to the conclusion that IMP-clearing may not be responsible for membrane fusion but for other complex events in the regulation of membrane to-membrane interactions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 517-526 
    ISSN: 1432-0878
    Schlagwort(e): Uterine epithelium ; Preimplantation phase ; Tight junctions ; Gap junctions ; Freeze-fracture ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the rabbit, the pseudopregnant uterus has been used as a model for studying alterations characteristic of the preimplantation phase. Alterations in intercellular junctions of the uterine epithelium were investigated during early pseudopregnancy (day 0 to day 6) by means of the freeze-fracture technique. In the uterine epithelium of oestrous females the zonula occludens belongs to the “tight” type of tight junctions. During pseudopregnancy an impressive proliferation of tight junctional belts can be observed. The basal strands proliferate, forming loops perpendicular to the luminal surface, whereas the more or less parallel arrangement of the luminal strands is maintained. At day 4 of pseudopregnancy macular tight junctions begin to develop on the lower portions of the lateral plasmalemma and are extensive by day 6 post hCG. Small gap junctions are infrequent between cells of the uterine epithelium and show no significant changes during the preimplantation phase. The physiological significance of the present morphological observations is discussed in the light of changes occurring during the preimplantation period.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 1998-11-03
    Print ISSN: 0302-766X
    Digitale ISSN: 1432-0878
    Thema: Biologie , Medizin
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 1988-04-01
    Print ISSN: 0302-766X
    Digitale ISSN: 1432-0878
    Thema: Biologie , Medizin
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 1983-06-01
    Print ISSN: 0302-766X
    Digitale ISSN: 1432-0878
    Thema: Biologie , Medizin
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 1985-08-01
    Print ISSN: 0302-766X
    Digitale ISSN: 1432-0878
    Thema: Biologie , Medizin
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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