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1.
Summary— To investigate if the functional alterations observed in resistance arteries of spontaneously hypertensive rats (SHRs) were also present at the coronary level, in vitro experiments were performed in mesenteric resistance arteries (MRA) and in right (RIC) and left interventricular coronary (LIC) arteries taken from 15–25-week-old SHR and age-matched Wistar Kyoto rats WKYs. Using a passive extension protocol, internal diameters corresponding to 100 mmHg intraluminal pressure (D100) were determined and vessels were set up to a normalized internal diameter (0.9 D100). SHR mesenteric resistance arteries had a significantly smaller diameter compared to WKY arteries, whereas both types of SHR coronary arteries had a greater diameter compared to those of WKY rats. In arteries in the absence of contracting agonist, nitro-L-arginine (NOLA, 100 μM) induced a progressive rise in basal tone, which could be reversed by subsequent addition of L-arginine (100 μM) but not D-arginine (100 μM). When expressed as percent of maximal contractions induced by agonists (noradrenaline, NA [10 μM] in MRA; serotonin, 5-HT [10 μM], in RIC and LIC), these contractions were significantly stronger in WKY compared to SHR coronary and mesenteric resistance arteries. In NA-precontracted MRA and 5HT-precontracted coronary arteries in the presence of indomethacin (10 μM), the magnitude of acetylcholine-induced maximal relaxations (expressed as percent of maximal contractions induced by agonists) was greater in WKY compared to SHR arteries. After a 30-min incubation period, NOLA (100 μM) completely inhibited relaxations induced by acetylcholine (0.01–10 μM) in all types of precontracted arteries. Subsequent additions of sodium nitroprusside, (SNP, 10 μM) induced complete relaxations in all preparations. These results show that a basal release of NO or NO-like compound by endothelial cells is present in isolated mesenteric resistance and coronary arteries of WKY rats and SHRs. The contribution of endothelium-derived relaxing factor-nitric oxide (EDRF-NO) to arterial tone was lower in MRA compared to coronary arteries in both strains and in SHR compared to WKY arteries. In the SHR preparations, the impaired relaxation induced by acetylcholine appeared to be due to a functional alteration of the endothelium in the presence of normal reactivity of the smooth muscle cells. 相似文献
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Faced with a rapidly changing market, increased legislation and intense competition, mental health service providers must
be sophisticated planners and position themselves advantageously in the marketplace. They can effectively position themselves
to be profitable and sustaining through market segmentation and sensitivity. The following article will address one concept
of marketing that has received less attention but is of critical importance: positioning. As the market environment becomes
increasingly competitive, positioning will be the key to success for mental health programs and institutions.
LINDA A. LENNOX, M.S.N., CMHA, has extensive experience in mental health administration. She currently resides in the Washington,
DC area.
DAVID AMBROSE, D.B.A., is the Lucas Professor of Business Administration, University of Nebraska at Omaha, Omaha, NE. 相似文献
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表小檗碱对α受体的作用 总被引:2,自引:0,他引:2
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择 相似文献
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Measurements by scanning electron microscopy (SEM) of femoral hemisections confirmed and amplified results by single-photon absorptiometry that had shown a marked increase in lactation osteopenia in rats fed a low-calcium diet (LCD, 0.04% Ca) as compared with a medium-(adequate) calcium diet (ACD, 0.4% Ca). SEM of bones from rats at the end of lactation on either diet showed a large loss of trabecular bone, increased porosity of endosteal surfaces, and cortical thinning. These changes were much more striking in LCD rats than in ACD rats. Backscattered electron imaging of cross sections of the femora revealed marked cortical thinning at midshaft after lactation, especially in rats on the LCD; this method also showed a marked increase in newly formed, less dense diaphyseal bone on the endosteal surface when dietary calcium had been made available to the LCD rats after lactation ceased. Unlike the rats fed the ACD after lactation, the rats continued on the LCD for the first 3 weeks postlactation failed to recover bone mineral, even though there was a marked decrease in resorbing surfaces of the femora as revealed by morphologic examination. When the diet was changed from the LCD to the ACD for the second 3 weeks postlactation (week 4-6), the bone mineral increased substantially. Overall, these results demonstrate the marked loss of bone during lactation, especially severe in rats fed a low-calcium diet, and the rapid postlactational recovery of bone when adequate dietary calcium was made available, even if the recovery had been delayed for the first 3 weeks by feeding a diet very low in calcium. 相似文献
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Based on reports describing their broad antiviral activity, the toxicity and antiviral efficacy of papaverine hydrochloride and pyrazofurin against respiratory syncytial virus (RSV) infection were tested in vitro in tissue culture cells and in vivo in cotton rats. Papaverine inhibited RSV replication in vitro; however, the median minimal toxic dose-median minimal inhibitory concentration ratios (MTD50:MIC50) in vitro and in vivo for papaverine were less than 4. Further work with this compound was discontinued. In contrast, pyrazofurin inhibited RSV replication in vitro (a mean MIC50 of 0.04 microgram/ml was obtained) and in vivo (RSV pulmonary titers were significantly reduced consistently in cotton rats given daily 10 mg/kg doses compared to untreated control animals). However, some toxic effects were observed in both the in vitro and in vivo tests of this compound. The remaining potential of pyrazofurin as an anti-RSV compound is discussed. 相似文献