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排序方式: 共有666条查询结果,搜索用时 15 毫秒
1.
2.
H G Giles S Sandrin B M Kapur J J Thiessen 《Canadian journal of physiology and pharmacology》1987,65(12):2491-2493
Ethanol was administered intravenously to rabbits. The concentration of ethanol, determined by gas chromatographic analysis, in lacrimal fluid was shown to reflect the concentration in plasma. The vapour above lacrimal fluid was analyzed in situ by the use of a small resistivity sensor that measures ethanol vapours. After a dose of approximately 750 mg/kg, the metabolic rates of ethanol determined by gas chromatographic analysis of plasma (226 +/- 13 mg.kg-1.h-1) and by eye ethanol vapour analysis (210 +/- 8 mg.kg-1.h-1) were virtually identical. The data suggest that ethanol eye vapour analysis may be an attractive, noninvasive method for the determination of ethanol in animals. 相似文献
3.
Immunocytochemical localization of hexosaminidase activity in human males revealed that the enzyme activity is localized mainly in the Sertoli cells and interstitial tissue of the testis and in the columnar cells of the epididymis. In seminal vesicles, activity was observed around the glandular epithelium in the form of fine granules. 相似文献
4.
Sandip M. Kanse Christine Kost Olaf G. Wilhelm Peter A. Andreasen Klaus T. Preissner 《Experimental cell research》1996,224(2):344
We have previously demonstrated that vitronectin (VN), a morphoregulatory protein in the vessel wall, is internalized and translocated to the subendothelial matrix by an integrin-independent mechanism (J. Histochem. Cytochem.41, 1823–1832, 1993). The cell surface component which mediates the initial contact of VN with endothelial cells is defined here. The specific binding of VN to endothelial cells demonstrated the following properties: a threefold increase after phorbol ester treatment; 85% inhibition by pretreatment of cells with phosphatidylinositol–phospholipase C to release glycolipid-anchored surface proteins; a 90% inhibition by urokinase (u-PA) receptor blocking antibody. u-PA increased VN binding to cells due to an eightfold increase in the affinity of VN for the u-PA receptor. Structure–function studies showed that the amino-terminal fragment of u-PA, devoid of any proteolytic activity, mediated this effect. Active plasminogen activator inhibitor-1 (PAI-1), but not inactivated PAI-1, inhibited VN binding to cells and displaced VN that was prebound to endothelial cell monolayers. Similarly, VN binding to purified (immobilized) u-PA receptor, but not to integrin, was enhanced by u-PA and inhibited by PAI-1. Hence, the binding of soluble VN to endothelial cell surfaces is mediated by the u-PA receptor, and the relative concentrations of u-PA and PAI-1 are able to regulate the strength of this interaction. Endothelial cell adhesion to immobilized VN was found to be integrin-mediated without any involvement of the VN–uPA-receptor system. Hence, the interaction of VN with the u-PA receptor may be involved in the regulation of cellular processes necessary for endothelial cell invasion and migration at VN-rich extracellular matrix sites. 相似文献
5.
Sajal Chakraborti Sandip K. Batabyal John R. Michael Tapati Sanyal 《Molecular and cellular biochemistry》1994,130(2):121-127
Exposure of rabbit pulmonary arterial smooth muscle cells to 10 M of the calcium ionophore A23187 dramatically stimulates cell membrane-associated phospholipase A2 activity and arachidonic acid release. In addition, A23187 also enhances cell membrane-associated serine esterase activity. Serine esterase inhibitors phenylmethylsulfonylfuoride and diisopropyl fluorophosphate prevent the increase in serine esterase and phospholipase A2 activities and arachidonic acid release caused by A23187. A23187 still stimulated serine esterase and phospholipase A2 activities and arachidonic acid release in cells pretreated with nominal Ca2+ free buffer. Treatment of the cell membrane with A23187 does not cause any appreciable change in serine esterase and phospholipase A2 activities. Pretreatment of the cells with actinomycin D or cycloheximide did not prevent the increase in the cell membrane associated serine esterase and phospholipase A2 activities, and arachidonic acid release caused by A23187. These results suggest that (i) a membrane-associated serine esterase plays an important role in stimulating the smooth muscle cell membrane associated phospholipase A2 activity (ii) in addition to the presence of extracellular Ca2+, release of Ca2+ from intracellular storage site(s) by A23187 also appears to play a role in stimulating the cell membrane-associated serine esterase and phospholipase A2 activities, and (iii) the increase in the cell membrane-associated serine esterase and phospholipase A2 activities does not appear to require new RNA or protein synthesis.Abbreviations A23187
calcium ionophore
- AA
arachidonic acid
- PMSF
phenylmethyl sulfonylfuoride
- DFP
diisopropyl-fluorophosphate
- DMEM
Dulbecco's modified Eagles medium
- FCS
fetal calf serum
- PBS
phosphate buffered saline
- HBPS
Hank's buffered physiological saline
- PLA2
phospholipase A2 相似文献
6.
Raman Kapur Mohammed Saleem Bryan L. Harvey Adrian J. Cutler 《In vitro cellular & developmental biology. Plant》1993,29(4):200-206
Summary Barley leaf blade protoplasts accumulate malonaldehyde, a product of lipid peroxidation, during culture. In addition, glutathione
levels fall after protoplast isolation and the proportion of glutathione in the oxidized state rises. These data indicate
oxidative stress after protoplast isolation and during culture. The cause of this phenomenon is revealed by data showing that
the activities of enzymes associated with antioxidative processes including glutathione reductase and ascorbate peroxidase
decrease after barley protoplast isolation. In contrast, protoplasts isolated from suspension cultured cells of bromegrass
and soybean exhibit little evidence for oxidative stress and increased activities of glutathione reductase and ascorbate peroxidase.
We suggest that an antioxidative response is associated with mitosis and colony formation from protoplasts, as exhibited by
bromegrass and soybean. Conversely, failure of an antioxidative response is associated with low viability and absence of mitosis,
as in barley. Increased viability of barley leaf protoplasts cultured on feeder layer cells is correlated with increased glutathione
content and higher glutathione reductase activity. 相似文献
7.
David A. Watson Vivek Kapur Daniel M. Musher James W. Jacobson James M. Musser 《Current microbiology》1995,31(4):251-259
This paper reports the cloning and sequencing of a region of DNA from Streptococcus pneumoniae serotype 3 surrounding transposon Tn916, insertion of which was previously shown to result in lack of expression of the extracellular capsule. Sequence analysis revealed that the transposon inserted into a consensus insertion site 71 bp from the 5 end of the cloned fragment. Within the clone, 3 downstream regions from two different pneumococcal lytA genes were identified, as well as a putative 194 AA open reading frame (ORF1). Moreover, two copies of the repeat element BOX, oriented in opposite directions, were located immediately 3 of orf1. Within the region bounded by the first pair of internal sequencing primers, analysis revealed that the fragment amplified by PCR was always of the same size. Moreover, Southern blotting showed that for all serotypes examined to date, homology exists with the cloned fragment. These results indicate that this region of the chromosome is highly conserved and, taken together with other independently derived data, suggest that interruptions or deletions within this DNA lead to unencapsulation. 相似文献
8.
In vivo and in vitro activities of nitrate reductase were assayedin Crotalaria juncea pollen suspension cultures. This enzymewas found to be substrate-inducible and enhanced activity wasobserved when it was extracted with cysteine buffer or incubatedwith NADH (0.6 mM) at 25?C or when the germinated pollen grainswere treated with red light for 10 min. Enzymes of ammonia assimilation,glutamate dehydrogenase and glutamate synthetase, and also thepentose phosphate-shunt enzyme, glucose-6-phosphate dehydrogenase,which catalyzes the step that provides reducing power to thesystem, are described. (Received October 20, 1977; ) 相似文献
9.
R S Sharma S Mokkapati M Rajalakshmi M M Kapur 《Indian journal of experimental biology》1992,30(11):1079-1083
Attempts were made to validate RIA for prolactin (PRL), LH and FSH in semen from normospermic, oligospermic and azoospermic subjects. The RIA used to measure PRL and LH in semen fulfilled the criteria of reliability, whereas low levels of FSH in semen precluded the validation of FSH assay in semen. Semen levels of PRL and LH were significantly (P < 0.05) higher than serum levels in all groups of subjects investigated. Semen levels of FSH in azoospermic men after vasoepididymostomy (VEA), were significantly (P < 0.05) higher compared to azoospermic men prior to surgery. Serum levels of PRL were significantly higher (P < 0.05) in normospermic men compared to oligospermic and azoospermic men prior to and after surgery. Semen levels of PRL in normospermic men were comparable with oligospermic and azoospermic subjects prior to and after surgery. Serum levels of LH in oligospermic and azoospermic men who did not undergo surgery and in men reporting oligospermia after VEA were comparable to normospermic subjects but in men showing azoospermia post surgically, serum LH levels were significantly (P < 0.005) elevated. Semen levels of LH in men reporting azoospermia before surgery and in subjects showing oligospermia or azoospermia post surgically were significantly lower (P < 0.05) compared to men with normal sperm count. Serum levels of FSH were significantly elevated (P < 0.05) compared to semen levels in oligospermic men prior to surgery but this increase was not seen in post VEA subjects. These results were discussed. 相似文献
10.
The 5' flanking region from the human dopamine beta-hydroxylase gene directs expression of bacterial beta-galactosidase reporter genes to a subset of adult neurons and adrenal chromaffin cells of transgenic mice. In this paper, we examine the spatial and temporal patterns of expression of these transgenes during embryogenesis. Expression begins at embryonic day 9 in the developing central and peripheral nervous systems and persists in cell populations in which expression is observed in adult transgenic mice. However, transient embryonic expression occurs in presumptive neuroblasts in developing sensory ganglia and ventrolateral neural tube that are destined to synthesize neurotransmitters other than catecholamines. These observations support the concept that some cells fated to become "non-catecholaminergic" neurons exhibit transient catecholaminergic features during their differentiation. 相似文献