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  • 1
    Electronic Resource
    Electronic Resource
    Osmotic reversal induces assembly of tight junction strands at the basal pole of toad bladder epithelial cells but does not reverse cell polarity (1987)
    Springer
    The journal of membrane biology 95 (1987), S. 199-208 
    Details
    ISSN: 1432-1424
    Keywords: tight junctions ; freeze fracture ; transporting epithelia ; water permeability ; membrane structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary This paper reports the effect of reversing the osmotic environment between luminal and serosal compartments of a toad urinary bladder on the polarity of assembly of tight junction strands. Toad bladders were filled with Ringer's solution (220 mOsm) and were immersed in distilled water at room temperature or at 37°C. Within two minutes, new tight junction strands are assembled. The new tight junctional strands unite the basal pole of epithelial cells with the apical side of basal cells. Physiological studies show that oxytocin, a synthetic analog of antidiuretic hormone, is still capable of inducing increases in water transport in epithelia which were osmotically reversed. This capacity decreases significantly for longer periods of osmotic reversal. Osmotic reversal does not alter the original polarity of epithelial cells: 1) the apical tight junction belt, at the apical pole, is not displaced; 2) the freeze-fracture morphology typical of apical plasma membrane (particle-rich E faces; particle-poor P faces) is not altered; 3) oxytocin and cyclic AMP induce aggregates which are observed only at the apical plasma membrane. Massive assembly of junctional elements occurs even in epithelia preincubated in the presence of cycloheximide (an inhibitor of protein synthesis) or of cytoskeleton perturbers. Our experiments show that the polarity of assembly of tight junction strands depends on the vectorial orientation of the osmotic environment of the epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869482
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  • 2
    Electronic Resource
    Electronic Resource
    Study of Abrasion Resistance of Steels by Micro-Scale Tests (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 514-516 (May 2006), p. 544-548 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Steels continue to have a preponderant role in mechanical components under all type of wear solicitations namely, abrasion. The ability of micro-scale abrasion test for evaluating the properties of bulk materials has been widely demonstrated. However, only recently this technique was especially developed to characterize thin-coated materials. This study presents results obtained in micro-scale abrasion tests performed on different low and high alloy steels. These steel samplesunderwent thermal and chemical (nitriding) treatments with the aim of enhancing their surface hardness. Nitriding parameters were varied so as to obtain different structures (with and without formation of a “white layer” of iron nitrides (ε-Fe2-3N or γ’-Fe4N compound layer). Test conditions such as normal load and concentration of the abrasive medium (SiC particles in distilled water)were changed in order to obtain a 2 or 3 body wear contact type. Results obtained allowed to compare the specific wear rate ks for the different steels and treatments tested as well as to relate the influence of surface hardness and test parameters on the wear mechanisms
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/12/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.514-516.544.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Localization of A Antigen Sites on Human Erythrocyte Ghosts (1971)
    [s.l.] : Nature Publishing Group
    Nature 232 (1971), S. 194-196 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We have demonstrated a new method for the study of the topochemistry of membrane surfaces6 which utilizes freeze-etching, a technique involving fracture, which splits the membrane and exposes its inner, hydrophobic matrix6'7 (Fig. 1, left), followed by etching, which exposes the membrane surface by ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/232194a0
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  • 4
    Electronic Resource
    Electronic Resource
    Induced redistribution of membrane particles, anionic sites and con A receptors in Entamoeba histolytica (1974)
    [s.l.] : Nature Publishing Group
    Nature 249 (1974), S. 170-171 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Trophozoites of E. histolytica, a pathogenic strain cultured under axenic conditions5, were washed with phosphate-buffered saline (PBS). Aggregation of membrane particles was induced by gradual impregnation with 25% glycerol m PBS, incubation for 30 min at 34° C and 30 min more at 24° C. Cell ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/249170a0
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  • 5
    Electronic Resource
    Electronic Resource
    On the prosthetic groups of the NiFe sulfhydrogenase from Pyrococcus furiosus: topology, structure, and temperature-dependent redox chemistry (1999)
    Springer
    JBIC 4 (1999), S. 284-291 
    Details
    ISSN: 1432-1327
    Keywords: Key words Hydrogenase ; Nickel ; Iron-sulfur ; Hyperthermophilic organisms ; Electron paramagnetic resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The sulfhydrogenase complex of Pyrococcus furiosus is an αβγδ heterotetramer with both hydrogenase activity (borne by the αδ subunits) and sulfur reductase activity (carried by the βγ subunits). The β-subunit contains at least two [4Fe-4S] cubanes and the γ-subunit contains one [2Fe-2S] cluster and one FAD molecule. The δ-subunit contains three [4Fe-4S] cubanes and the α-subunit carries the NiFe dinuclear center. Only three Fe/S signals are observed in EPR-monitored reduction by dithionite, NADPH, or internal substrate upon heating. All other clusters presumably have reduction potentials well below that of the H+/H2 couple. Heat-induced reduction by internal substrate allows, for the first time, EPR monitoring of the NiFe center in a hyperthermophilic hydrogenase, which passes through a number of states, some of which are similar to states previously defined for mesophilic hydrogenases. The complexity of the observed transitions reflects a combination of temperature-dependent activation and temperature-dependent reduction potentials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050314
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of glucose-6-phosphate isomerase genotype onin vitro specific activity andin vivo flux inMytilus edulis (1989)
    Springer
    Biochemical genetics 27 (1989), S. 451-467 
    Details
    ISSN: 1573-4927
    Keywords: glucose-6-phosphate isomerase ; in vitro specific activity ; in vivo flux ; Mytilus edulis ; selection for biochemical intermediacy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained. GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%) genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399674
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of glucose-6-phosphate isomerase genotype onin vitro specific activity andin vivo flux inMytilus edulis (1989)
    Springer
    Biochemical genetics 27 (1989), S. 451-467 
    Details
    ISSN: 1573-4927
    Keywords: glucose-6-phosphate isomerase ; in vitro specific activity ; in vivo flux ; Mytilus edulis ; selection for biochemical intermediacy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained. GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%) genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553912
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  • 8
    Electronic Resource
    Electronic Resource
    Numerous cell targets for gastrin in the guinea pig stomach revealed by gastrin/CCKB receptor localization (1995)
    Springer
    Cell & tissue research 283 (1995), S. 1-6 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Parietal cells ; Gastric mucosa ; Secretion ; Receptor ; Gastrin ; Gastrointestinal hormones ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The localization of the gastrin/CCKB receptor (GR) has recently become a subject of debate, especially since the publication of evidence for its presence in an unsuspected location, namely in the lamina propria, the submucosal layer of the stomach lining. Knowledge of the receptor localization is important because of the critical role of gastrin secretion and its trophic effects on the gastric epithelium. The present study, which utilizes immunohistochemistry and electron microscopy as primary tools, provides unequivocal data concerning the localization of GR in the guinea pig stomach. GR is expressed in parietal cells, on chief cells, and in previously unreported endocrine cells of the stomach. It is not found in the lamina propria. The predominant localization of the receptor in the endocrine cells is on the membranes of cytoplasmic electron-dense secretory granules. The positioning of these cells in the gastric glands suggests that they may be involved in the uptake of gastrin from the circulation. The distribution of GR implies that it may be involved in the regulation of various processes and may mediate various effects of gastrin in the stomach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050506
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  • 9
    Electronic Resource
    Electronic Resource
    Cellular functions during activation and damage by pathogens: Immunogold studies of the interaction of bacterial endotoxins with target cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 31 (1995), S. 141-158 
    Details
    ISSN: 1059-910X
    Keywords: Immunocytochemistry ; Lipopolysaccharide ; Pneumocyte ; Macrophage ; Microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Bacterial endotoxins (lipopolysaccharides or LPS) are active components of Gramnegative bacteria that act on numerous cellular functions through the processes of cell activation and damage. The molecular mechanisms involved in the “endotoxic phenomenon” are not defined yet, although extensive studies have been carried out. Immunogold and electron microscopy (EM) have contributed to identify the primary target cells of endotoxins and the subcellular systems that receive the direct action of these bacterial agents. Here, we review our studies on immunogold detection of endotoxins in cellular and subcellular systems. The analysis of the interaction between endotoxins and cells was focussed on the following aspects: (1) morphological characteristics of the LPS aqueous suspensions used in experimental work; (2) binding of endotoxins to the plasma membrane of type II pneumocytes and alveolar macrophages (two of their cellular targets), and influence of the state of aggregation of the LPS; (3) movement and distribution of endotoxins inside the cell, from the plasma membrane to the nucleoplasm; and (4) interaction of LPS with microtubules and its effects on the integrity of the microtubular network. These approaches provide information at the molecular level as well as data for the establishment of physiological models of endotoxicity. © 1995 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070310206
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  • 10
    Electronic Resource
    Electronic Resource
    Immunogold labeling of oncogenic and tumor related proteins (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 31 (1995), S. 159-173 
    Details
    ISSN: 1059-910X
    Keywords: Immunogold ; Electron microscopy (EM) ; Oncogene ; Mos ; Met ; Ski ; Muc1 ; Mucin ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Immunogold labeling electron microscopy technique has been used to study the ultrastructural localization of oncogenic proteins: Mos, Met, Ski, and the tumor-associated protein, Muc1, as well as their relationship with other tumor-related proteins. By pre- and postembedding immunogold labeling electron microscopy techniques, we showed that the Mos protein pp39mos colocalized with microtubule bundles, suggesting that microtubulin or microtubule-associated protein(s) may be the substrate of Mos. Met protein was labeled at the microvilli of the lumen that are formed in cultured T47D cells, implying its potential involvement in lumen formation. Ski localization experiments revealed a unique globular structure “Ski body” that is present inside the nucleus of interphase chicken embryo fibroblast infected with Ski cDNA FB29 and FB2-29. Ski bodies were also found scattered in the cytoplasm of metaphase FB29 and FB2-29 Ski expressing chicken embryo fibroblasts. In T47D cells, tumor-associated protein Muc1 was associated with both the plasma membrane and the membranes of secretory vesicles in the cytoplasm. In MUC1 infected NIH3T3 cells, however, labeling showed that in addition to the plasma membrane and the membranes of secretory vesicles, some Muc1 gold spheres were seen inside the secretory vesicles, suggesting that the subcellular localization of the protein may vary in different cell types. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070310207
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