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排序方式: 共有168条查询结果,搜索用时 31 毫秒
1.
A pharmacological approach to thromboxane receptor antagonism 总被引:3,自引:0,他引:3
Thromboxane A2 (TxA2) appears to be an important mediator of ischemia and hypoxia. Despite its short half-life and the fact that it may not circulate in the blood until its values become quite high, TxA2 contributes to the pathogenesis of cardiopulmonary diseases (e.g., sudden death, myocardial ischemia, circulatory shock). It does so because it propagates its own formation by activating platelets and constricting blood vessels, thus activating more TxA2 and trapping it locally within an ischemic or hypoxic region. TxA2 concentrations in the extracellular fluid of lymph of ischemic regions may be much higher than that occurring in nonischemic, normally perfused regions. Specific and potent Tx receptor antagonists (TxRA) have recently become available for study. The TxRA are useful tools in the study of the pathophysiology of Tx-dependent disease processes and have been found to be effective in a variety of ischemic disorders including circulatory shock, myocardial ischemia, and sudden cardiopulmonary death. Moreover, inasmuch as early work indicates that these agents are both safe and effective in humans, Tx receptor antagonists may be employed as therapeutic agents in several cardiovascular disease states. Further investigation is necessary to clarify the role of TxRA as therapeutic agents. 相似文献
2.
Thromboxane A2 in health and disease 总被引:2,自引:0,他引:2
3.
Anti-shock effects of human superoxide dismutase in splanchnic artery occlusion (SAO) shock 总被引:2,自引:0,他引:2
H Bitterman N Aoki A M Lefer 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1988,188(3):265-271
We studied the effects of human superoxide dismutase (h-SOD) in splanchnic artery occlusion (SAO) shock. Pentobarbital anesthetized rats subjected to total occlusion of the superior mesenteric and the celiac arteries for 40 min developed a severe shock state usually resulting in a fatal outcome within 20 min after the release of the occlusion. h-SOD (10 mg/kg) was infused intravenously starting at reperfusion and lasting for 10 min. SAO shock rats treated with h-SOD maintained postreperfusion MABP at significantly higher values compared to rats receiving the vehicle (final MABP 84 +/- 6 vs 46 +/- 1 mm Hg, P less than 0.01, respectively). Treatment with h-SOD attenuated the plasma accumulation of free amino-nitrogen compounds (P less than 0.01 from vehicle) as well as the activity of the lysosomal protease cathepsin D (P less than 0.05 from vehicle). Furthermore, the plasma activity of a myocardial depressant factor was significantly lower in h-SOD-treated rats than in SAO rats receiving only the vehicle (27 +/- 1 vs 64 +/- 3 U/ml, P less than 0.01). SAO shock rats treated with h-SOD also exhibited a significantly higher survival rate than the SAO shock +/- vehicle group (88% vs 11%, P less than 0.01, respectively). These results support the role of oxygen-derived radicals in the pathophysiology of SAO shock, and indicate that h-SOD effectively ameliorates the deleterious effects of oxygen radicals in this severe model of ischemia and reperfusion. 相似文献
4.
A new antagonist of the vasoconstrictor eicosanoids, L-640,035, was studied in a standardized model of myocardial ischemia (MI) in anesthetized cats. This eicosanoid antagonist was not found to exert any overt hemodynamic action in cats subjected to a sham myocardial ischemia protocol. However, the antagonist markedly reduced the S-T segment of the electrocardiogram when administered 30 min after permanent occlusion of the left coronary artery. Moreover, circulating activities of the marker enzyme creatine kinase (CK) were markedly attenuated by L-640,035 3-5 h after the onset of MI. This was verified by cardiac biopsies 5 h post-MI since myocardial CK activities decreased much less in treated MI cats than in MI cats receiving only the vehicle for L-640,035 (i.e., ethanol). The active metabolite of the antagonist in biological fluids (i.e., L-636,499) markedly antagonized the vasoconstrictor actions of endoperoxide and thromboxane analogs, but not of noneicosanoids in isolated perfused coronary arteries. 相似文献
5.
6.
N Aoki M Siegfried P Tsao A M Lefer 《Prostaglandins, leukotrienes, and essential fatty acids》1989,37(2):89-95
Diets enriched with omega-3 unsaturated fatty acids are associated with decreased hypercholesterolemia and decreased risk of ischemic and atherosclerotic diseases. We studied the acute intravascular effects of some of these unsaturated fatty acids (i.e., eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) along with omega-6 unsaturated fatty acids, (i.e., linoleic and linolenic acid) in splanchnic artery occlusion (SAO) shock in rats. Anesthetized rats subjected to total occlusion of the celiac and superior mesenteric arteries for 40 minutes followed by reperfusion usually resulted in a fatal outcome 90-120 minutes after releasing the clamps. SAO shock rats treated with the omega-3 unsaturated fatty acid, EPA, exhibited an improved survival time and rate (p less than 0.05 from vehicle) compared to those receiving only vehicle (i.e., 50% ethanol). EPA and DHA treated SAO rats also exhibited lower plasma activities of the lysosomal protease, cathepsin D, free amino-nitrogen compounds, and the cardiotoxic peptide, myocardial depressant factor. These results indicate that omega-3 unsaturated fatty acids, especially EPA, have some acute beneficial effects in SAO shock in rats. 相似文献
7.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
8.
K.C. Nicolaou W.E. Barnette R.L. Magolda Paul A. Grieco W. Owens C.-L.J. Wang J.B. Smith M. Ogletree A.M. Lefer 《Prostaglandins & other lipid mediators》1978,16(5):789-794
The synthesis of the sodium salts of enantiomerically pure 12-fluoroPGI2 (9), (±)-12-fluoroPGI2 (9), (±)-15-epi-12-fluoroPGI2 (10), (±)-12-fluoro-13,14-dihydroPGI2 (11), (±)-12-fluoro-4(E)-isoPGI2 (12), and (±)-5,6-dihydro-12-fluoroPGI2 (13) is detailed starting from the corresponding derivatives of 12-fluoroPGF2α methyl ester. Prostacyclins 9, (±)-9, (±)-10, (±)-11, (±)-12, and (±)-13 have been evaluated for their ability to inhibit human platelet aggregation and their effect on smooth muscle (isolated cat coronary artery). 相似文献
9.
A new analog of prostacyclin, 6,9-Thiaprostacyclin was infused intravenously in pentobarbital anesthetized cats in order to determine its hemodynamic and anti-platelet aggregating properties. At an infusion rate of 0.01 μmoles/kg/min, PGI2-S moderately decreased arterial blood pressure without altering heart rate of superior mesenteric artery flow or platelet aggregation responses to ADP. However, at 0.05 μmoles/kg/min, PGI2-S significantly reduced arterial blood pressure and significantly increased heart rate, and superior mesenteric artery flow. Moreover, at 0.05 μmoles/kg/min, PGI2-S inhibited ADP platelet aggregation by 80%. PGI2-S may be a useful agent in circulatory shock. 相似文献
10.