Adenosine receptor-induced cyclic AMP generation and inhibition of 5-hydroxytryptamine release in human platelets.

1. We have assessed the effects of adenosine receptor agonists and antagonists on collagen-induced 5-hydroxytryptamine (5-HT) release and cyclic AMP generation in human platelets. 2. 5'-N-ethylcarboxamidoadenosine (NECA) and CGS 21680 elicited accumulations of cyclic AMP with mean EC50 values of 2678 and 980 nM, respectively. The maximal response to CGS 21680 was approximately half that of the response to 10 microM NECA. 3. NECA and CGS 21680 inhibited collagen-induced 5-hydroxytryptamine release with mean EC50 values of 960 and 210 nM, respectively. The maximal response to CGS 21680 was approximately 25% of the response to 10 microM NECA. 4. The A1/A2a-selective adenosine receptor antagonist PD 115,199 was more potent as an inhibitor of NECA-elicited responses than the A1-selective antagonist DPCPX with calculated Ki values of 22-32 nM and > 10 microM, respectively. 5. In the presence of a cyclic AMP phosphodiesterase inhibitor, the effects of CGS 21680 on cyclic AMP accumulation and 5-HT release were enhanced to levels similar to those elicited by 10 microM NECA. In the absence of phosphodiesterase inhibition, CGS 21680 did not antagonise the effects of NECA. Furthermore, endogenous adenosine did not contribute to the effects of CGS 21680 when phosphodiesterase was inhibited. 6. We conclude that an A2a adenosine receptor appears to be involved in the NECA-elicited increases in cyclic AMP levels and inhibition of 5-HT release in human platelets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alcohol and Platelet Function

Epidemiological studies have shown that moderate consumption of alcoholic beverages is inversely related to the incidence of the complications of coronary artery disease. The protective effect of ethanol may be partially attributable to an inhibitory effect of ethanol on platelets. This article summarizes the experimental observations that ethanol inhibits platelet responses to specific physiological agonists. In alcoholics, various platelet defects have been observed, but these may be influenced by metabolic factors rather than the presence of ethanol alone. The acute effects of ethanol on platelet functions both in vivo and ex vivo will be reviewed. Evidence will be presented demonstrating that ethanol added acutely in vitro inhibits phospholipase A₂ in stimulated platelets. The interaction of ethanol with other signal transduction pathways will also be discussed.     

Effects of Ethanol on the Contractile Function of the Heart: A Review

Chronic ethanol consumption leads to a number of alterations in the contractile function of the heart and is a leading cause of cardiomyopathy. Ethanol also has an acute negative inotropic effect mediated by direct interaction with cardiac muscle cells, although this action is often masked by indirect actions resulting from enhanced release of catecholamines in vivo. This article reviews the effects of ethanol on the contractile function of the heart. The specific targets affected by ethanol in cardiac muscle cells are discussed in terms of potential mechanisms underlying the depressions of contractility resulting from both acute and chronic actions of ethanol.     

The functional properties of the erythrocyte membranes in patients with chronic glomerulonephritis]

Mg-, Ca-, Na-, K-ATPase, acetylcholine esterase and sulfhydryl groups of red blood cell membranes were evaluated in 40 patients with chronic glomerulonephritis in preazotemia stage versus 34 healthy controls. In chronic glomerulonephritis there was a significant fall in Ca-ATPase activity irrespective of the disease pattern. Na, K-ATPase tended tot a decrease contrary to sulfhydryl groups levels and acetylcholine esterase activity. In the nephrotic variant of the disease Na, K-ATPase, Ca-ATPase activity dropped and came to increase due to glucocorticosteroid treatment. The changes are attributed to modification of the lipid bilayer of the red blood cell membranes.     

Pulmonary function, nutrition, and self-concept in cystic fibrosis summer campers

Children with cystic fibrosis (CF) often attend special summer camps. We postulated that beyond the simple fun of camp, attendance at camp might improve the clinical status and self-image of the campers. We therefore studied lung function, nutrition, and self-image in 45 children between the ages 6 and 12 years after a two-week CF summer camp. Although there was a 10 percent fall in respiratory rate during camp, spirometry did not change significantly. There were, however, significant gains in weight, skin fold thickness, and midarm circumference after two weeks at camp, and these increases were positively correlated with the number of pancreatic enzymes taken daily by the child. The Primary Self-Concept Inventory test was completed by each camper on the first and last days of camp. Although there was a trend toward increasing self-concept during camp, this did not reach statistical significance. Two weeks' attendance at summer camp appears to be associated with improved nutrition in children with CF. This may be due to increased emphasis on weight gain and appropriate use of pancreatic enzymes or to other factors, like avoidance of tobacco smoke exposure, that are unique to the summer camp setting.     

鳖血清抑癌活性的研究

采用同位素掺入法,以同位素标记物掺入速率为指标,观察了鳖血清对艾氏腹水癌细胞和正常小鼠骨髓细胞的DNA、RNA和蛋白质生物合成的影响,结果表明鳖血清可强烈地抑制~3H-TdR、~3H-UR和~3H-Leu掺入癌细胞,其抑制率分别为96.8％、94.8％和91.9％,而对~3H-TdR和~3H-UR掺入骨髓细胞的抑制率为39.4％和37.3％。将鳖血清在50℃加热十分钟,其抑制同位素标记物掺入靶细胞的活性几乎全部丢失。但鳖血清在生理盐水中透析不影响它的抑制活性。这些结果提示,鳖血清中存在某种不耐热的组份,可强烈抑制癌细胞生长,同时对正常骨髓细胞也有一定抑制作用。     

Pleomorphic adenoma arising in a salivary rest in childhood.

Two children with pleomorphic adenomas developing in heterotopic salivary tissue are presented. These are unusual lesions, rarely seen in adults and not previously described in the pediatric age group.