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2006年10月2日,瑞典卡罗琳斯卡研究院宣布,2006年诺贝尔生理学或医学奖颁发给2位美国科学家:Andrew Z.F ire和Craig C.M ello,以表彰其在RNA干扰双链RNA引发的基因沉默领域所做出的杰出贡献。本文从2位获奖科学家的简介,主要贡献,RNA干扰发现的意义以及该奖项存在的遗憾等方面进行综述。 相似文献
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The food-calcium (Ca) interaction was examined in 12 healthy women (mean age 38 years) maintained on a constant metabolic diet. They underwent three phases of study, comprised of control (no Ca), Ca citrate (1 g Ca/day) during meals, and Ca citrate separately from meals. Each phase was 7 days in length and two 24-hour urine samples were collected on days 6 and 7. The rise from the control phase in urinary Ca was slightly more prominent when Ca citrate was given with meals than without (68 and 62%, respectively). The fall in urinary phosphorus was equivalent at about 25% between Ca citrate phases. The rise in urinary citrate and pH and the decline in urinary ammonium were more prominent when Ca citrate was given with meals; however, the changes were small or nonsignificant. The urinary saturation of Ca oxalate, brushite or monosodium urate did not differ between the two Ca citrate phases. There was a nonsignificant rise in serum iron during Ca citrate phases. The results suggest that: 1) dissolution and absorption of Ca citrate might be slightly greater when given with food than without; 2) that the ability of Ca citrate to attenuate crystallization of stone-forming Ca salts in urine is not modified by food; and 3) that Ca citrate may not impair iron absorption from food. 相似文献
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The effects of acetylcholine on the spontaneous activity of the AV node of dog hearts were studied by recording transmembrane potentials of its fibers. Action potentials of most nodal fibers were characterized by prominent phase 4 depolarization and a smooth transition from phases 4 to 0. On the isolated AV nodes, acetylcholine at 1.0 μg/m1 suppressed the rate of phase 4 depolarization and increased the amplitude of the maximum diastolic potential, resulting in a slowing of spontaneous activity. At 2.0 μg/m1, spontaneous activity was completely suppressed. In comparison, spontaneous activity of the isolated His bundle was relatively insensitive to the suppressive effect of acetylcholine at the same concentrations. In the AV node-His bundle preparations in which the AV node was the pacemaker, acetylcholine decreased spontaneous activity by suppressing the phase 4 depolarization of the nodal fibers and shifted the pacemaker of the preparation to the His bundle. The findings provide a basis for predicting that under strong vagal influence, the automaticity of the AV node will be suppressed and the pacemaker of the junctional rhythm will be located at the His bundle. 相似文献
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Raffaele De Caterina Daniela Giannessi Filippo Crea Sergio Chierchia Walter Bernini Paolo Gazzetti Antonio Labbate 《The American journal of cardiology》1984,53(11):1683-1687
The possibility that isosorbide dinitrate (ISDN) inhibits platelet function in humans has been explored in vitro and in vivo. Incubation of citrated plateletrich plasma from healthy subjects with scalar concentrations (1.25, 12.5 and 125 μg/ml) of ISDN for 5 and 10 minutes resulted in a decrease in platelet aggregation after ADP, adrenaline, and arachidonic acid at the highest drug concentration (mean decrease: 72% [p < 0.01], 56% [p < 0.05] and 62% [p < 0.05], respectively, with the 10-minute incubation). Also, a significant reduction (30%) in generated thromboxane (TX)B2 levels was observed after arachidonic acid (p < 0.01). ISDN was then infused at rate of 4 mg/hour for 30 minutes in 11 patients with angina and at a rate of 30 mg/hour for 20 minutes in 8. The smaller dose, which caused minor changes in arterial pressure and heart rate, was accompanied by a marked, significant decrease in ADP- and adrenaline-induced aggregation, with a nadir at 60 minutes from the infusion stop (decreases of 40% and 51% respectively). Circulating platelet aggregates also decreased, with a minimum (? 41%, p < 0.05) at the end of the infusion. The higher infusion rate, causing marked hemodynamic effects, was not accompanied by the occurrence of clear antiplatelet effects. Thus, ISDN can affect platelet function both in vitro and in vivo. The in vivo effect occurs at lower concentrations than in vitro but is blunted when a marked hemodynamic response occurs. 相似文献
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