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排序方式: 共有465条查询结果,搜索用时 15 毫秒
1.
Activation of the phosphatidylinositol cycle in spreading cells 总被引:4,自引:0,他引:4
Metabolites of the phosphatidylinositol cycle were analyzed in BHK-21 (C13) cells spreading on fibronectin-coated culture plates in comparison with attached nonspreading cells 45 min after plating. Among the water-soluble metabolites (glycerophosphoinositol, inositol, inositol monophosphate, inositol bisphosphate, inositol trisphosphate, and inositol tetrakisphosphate), significant elevations were found for inositol monophosphate, inositol bisphosphate, and inositol tetrakisphosphate. In the lipid fraction, phosphatidylinositol 4-monophosphate and phosphatidylinositol 4,5-bisphosphate were significantly elevated. The activation of the phosphatidylinositol cycle in spreading versus nonspreading attached BHK-21 (C13) cells may be involved in the permissive effect of the extracellular matrix on cell proliferation. 相似文献
2.
M. Breuer 《Radiation and environmental biophysics》1991,30(3):181-183
Summary The development of cancer has long been perceived to be a complex and multistep process in which a normal cell progresses to a fully malignant tumor cell in a step-by-step fashion. At the molecular level it is believed that these steps correspond to the acquisition of activated oncogenes or alternatively the inactivation of tumor suppressor genes. With the ability to stably transfer foreign genetic information into the germ line of animals a new powerful tool to study oncogenes became available. 相似文献
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Abstract: Rats were treated with reserpine, desmethylimipramine, or carrier, either alone or in combination with tropolone. Either 10 min (t1) or 1 h (t2) after intraventricular injection of [3H]noradrenaline, they were decapitated. The total 3H activity and the recovery of [3H]noradrenaline were determined in tissue extracts from various brain regions. Maximum total 3H activity was measured at t1 in all tropolone-treated rats; the mean sum of these results served as an estimate of the initial tissue concentration of [3H]noradrenaline. At t1, 40–50% of the sum of [3H]noradrenaline and its metabolites was recovered unchanged in normal rats; reserpine and DMI reduced the recovery to 18–27%. In all groups, the decline of [3H]noradrenaline was retarded after t1. Inhibition of catechol-O-methyltransferase by tropolone caused consistently elevated [3H]noradrenaline levels, but did not affect the metabolic rate after t1 when compared with similarly pretreated, but tropolone-free rats. Thus, if catechol-O-methyltransferase was inhibited during the injection of [3H]noradrenaline, a higher percentage of the amine had been taken up into spaces with a slow noradrenaline turnover. The maximum increase was seen when the neuronal uptake, was inhibited by desmethylimipramine. This supported the hypothesis that an additional extraneuronal space exists, in addition to the known intraneuronal and extraneuronal compartments, which has a slow noradrenaline turnover. The tropolone effect on the noradrenaline recovery possibly shows that there might be a saturable “methylating system,” similar to that described for the periphery, in which catechol-O-methyltransferase is linked to the extraneuronal uptake2. By affecting the access of noradrenaline to non-neuronal cells it might influence the rate of noradrenaline elimination from the intercellular space. 相似文献
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Saul Ship Yehezkel Shami William Breuer Aser Rothstein 《The Journal of membrane biology》1977,33(1):311-323
Summary The potent and specific inhibitor of anion permeability, 4,4-diisothicyanostilbene-2,2-disulfonic acid (DIDS) was synthesized in tritiated form ([3H]DIDS) from tritiated 5-nitrotoluene-o-sulfonic acid. Its reactions with and effects on red blood cells were compared with those of a reduced form ([3H]H2DIDS), previously used as a tracer for DIDS. The rate of covalent reaction of [3H]DIDS was substantially faster than that of [3H]H2DIDS at all temperatures tested. With both agents, the rate of reaction was increased in alkaline media, although the response occurred at a lower pH with [3H]DIDS. On the other hand, the relationship of irreversible membrane binding to the degree of inhibition of sulfate fluxes was linear and virtually the same for both agents, with 100% inhibition associated with the binding of approximately 1.2×106 molecules per cell. About 90% of the binding for each probe was to a particular membrane protein, known as band 3, equivalent to about 1 mole of agent per mole of protein. 相似文献
8.
K Fotherby R J Warren K Shrimanker L Siekmann A Siekmann H Breuer 《Journal of steroid biochemistry》1979,10(1):121-122
Assays designed to quantitate the plasma levels of norethisterone (NET) are compared. Results from radioimmunoassay were compared with those from gas chromatography-mass fragmentography which were established in 5 subjects after a 1-mg oral dose of the steroid. In general, the levels of steroid measured by radioimmunoassay were usually higher than those measured by gas chromatography-mass fragmentography; there was however a correlation coefficient of .96 (P .001). For concentrations of the steroid above 500 pg/ml, the mean overestimate by radioimmunoassay was less than 30%. 相似文献
9.
Noemi Luknar-Gabor Ursula Fenger Christoph Wagener Heinz Breuer 《Biochemical and biophysical research communications》1982,109(4):1270-1275
A variant of the carcinoembryonic antigen (CEA) with lower molecular weight than a CEA reference preparation has been separated from CEA. Using a polyclonal, spleen absorbed anti-CEA antiserum, the variant crossreacts with reference CEA in immunodiffusion. The CEA-activity of the variant has been demonstrated using an enzyme-immunoassay with monoclonal CEA specific antibodies. There is sufficient immunological evidence that this variant is a distinct antigen different from the crossreactive antigens described so far. The reactivity of the polyclonal anti-CEA antiserum with the CEA variant was abolished by absorption against the immobilized variant. 相似文献
10.
V Faber E Quentin-Hoffmann B Breuer J Schittny W V?lker H Kresse 《European journal of cell biology》1992,59(1):37-46
A novel large heterodimeric dermatan sulfate proteoglycan with core proteins of 460 and 300 kDa, respectively, had been described as a secretory product of human fetal skin fibroblasts (Breuer et al., J. Biol. Chem. 266, 13224-13232 (1991)). Pulse-chase experiments showed a preferential association of the proteoglycan with the cell membrane. Immunogold labeling indicated its localization in fibrils on the cell surface as well as in fibrillar extensions from the cell body. Immunofluorescence studies yielded a fibrillar and punctate staining pattern which was also seen in cultured human and porcine endothelial cells. Dot-like structures were observed in transformed human keratinocytes. Various immunocytochemical double-labeling experiments indicated a remarkable colocalization of the proteoglycan with fibronectin, laminin, perlecan, and type IV collagen whereas only occasionally a colocalization with chondroitin-6-sulfate was found. No evidence for an enrichment of the proteoglycan in vinculin-containing structures was obtained. These results suggest that the proteoglycan is a widely distributed macromolecule which can associate with basement membrane components. Preliminary findings in rat cornea supported this conclusion. 相似文献