Inhibition of thromboxane formation in vivo and ex vivo: implications for therapy with platelet inhibitory drugs

The capacity of platelets to generate thromboxane A2, reflected by measurement of serum thromboxane B2 (TxB2), greatly exceeds the systemic production of thromboxane in vivo. Thus, it is possible that substantial but incomplete inhibition of thromboxane formation ex vivo would still allow marked augmentation of thromboxane production in vivo. To address this hypothesis, we administered aspirin 120 mg, a selective inhibitor of thromboxane synthase (TxSl), 3-(1H-imidazol-1-yl- methyl)-2-methyl-1H-indole-1-propanoic acid (UK-38, 485) 200 mg, and a combination of both drugs to 12 healthy volunteers and measured the effects on serum TxB2 and urinary 2,3-dinor-thromboxane B2 (Tx-M), an index of endogenous thromboxane biosynthesis. Although serum TxB2 was maximally inhibited by 94 +/- 1% after aspirin and 96 +/- 2% after the TxSl, maximal depression of Tx-M was only 28 +/- 8% and 37 +/- 9%, respectively. Combination of aspirin with the TxSl resulted in a small but significant increase in inhibition of thromboxane generation ex vivo (98 +/- 1% v 94 +/- 1%; P less than 0.05), but a disproportionately greater fall in thromboxane synthesis in vivo (58 +/- 7%; P less than 0.01). Consistent with further inhibition of platelet thromboxane synthesis, addition of the TxSl abolished the transient decline in prostacyclin formation after aspirin alone. Administration of a lower dose of aspirin (20 mg) to 6 healthy subjects caused a small reduction in Tx-M (12 +/- 4%; P less than 0.05) and inhibited serum TxB2 by 48 +/- 2%. The relationship between inhibition of platelet capacity to form thromboxane ex vivo (serum TxB2) and synthesis in vivo (Tx-M) departed markedly from the line of identity. When total blockade of the capacity of platelets to generate thromboxane is approached, minor decrements in capacity result in a disproportionate depression of actual thromboxane biosynthesis. These results imply that pharmacologic inhibition of serum TxB2 must be virtually complete before thromboxane- dependent platelet activation is influenced in vivo.     

Comparative efficacy and safety of contemporary Angiotensin converting enzyme inhibitors moexipril and spirapril in women with postmenopausal metabolic syndrome

Moexipril (7.4-15 mg/day) was given to 34, spirapril (3-6 mg/day) -- to 18 postmenopausal women with hypertension and metabolic syndrome for 16 weeks. Hydrochlorthiazide was added when therapy was not sufficiently effective. Both angiotensin converting enzyme inhibitors had similar hypotensive activity: blood pressure normalized in 71 and 61% of moexipril and spirapril treated women, respectively. Both drugs promoted normalization of metabolism of lipid (lowering of levels of cholesterol, atherogenic lipoproteins and triglycerides) and carbohydrates (lowering of hyperinsulinemia). Patients with postmenopausal metabolic syndrome had elevation of leptin level up to 27.5+/-5.5 pg/ml. Moexipril and spirapril caused lowering of elevated levels of leptin. These drugs did not affect levels of sex hormones. They exerted vasoprotective (normalization of endothelium dependent and independent vasodilatation) and nephroprotective (attenuation and normalization of microalbuminuria) effects. Thus spirapril and moexipril are effective in treatment of hypertension in patients with postmenopausal metabolic syndrome.     

Phosphoinositide 3-kinase is involved in the induction of the human sperm acrosome reaction downstream of tyrosine phosphorylation

In somatic cells phosphoinositide 3-kinase (PI 3-kinase) is activated upon interaction with both receptor tyrosine kinases (RTK) and G- proteins resulting in the production of moieties involved in the inositol phospholipid signalling pathway. As G proteins, RTK and the inositol phospholipids have all been implicated in the human sperm acrosome reaction, experiments were carried out to determine whether PI 3-kinase was also involved in this phenomenon. Wortmannin is a selective inhibitor of PI 3-kinase and was shown to significantly inhibit the acrosome reaction induced by both mannose-bovine serum albumin (mannose-BSA) (10, 50 and 100 nM) and a polyclonal antibody raised against an extracellular region of the sperm zona receptor kinase (ZRK, at 100 nM only). Wortmannin did not inhibit the A23187- or progesterone-induced acrosome reaction. These results suggest that PI 3- kinase is involved in the human sperm acrosome reaction. The levels of tyrosine phosphorylation of sperm proteins as detected by Western blotting using antiphosphotyrosine antibodies was not affected by wortmannin in agonist (A23187 and mannose-BSA)-stimulated spermatozoa. This indicated that PI 3-kinase operates downstream of tyrosine phosphorylation in the signal transduction cascade which leads to the human sperm acrosome reaction.      

Evaluation of dipyridamole efficacy as an agent for preventing acute respiratory viral diseases

The epidemiological effectiveness of a low molecular interferon inducer, dipyridamole, as a means of prevention of influenza and ARD was studied in a double-blind epidemiological trial in a period of seasonal rise of ARD (Dec., 26, 1984-March 13, 1985). A statistically significant decrease of ARD incidence (1.91-fold) in the experimental group was confirmed by the results of serological studies and titrations of serum interferon in paired sera collected before the prevention and 10 days after its termination in selected subgroups from the experimental and control groups. The results indicate that the use of dipyridamole may be effective for mass prevention of influenza and ARD.     

CN80-2对鼠肝匀浆SOD,GSH-PX 的影响

本文给小鼠 CN80-2灌胃(3g/kg)14天,及鼠肝组织中加入 CN80-2(0.3g/ml)温育2h,均可提高鼠肝组织中超氧化物歧化酶含量(P<0.01,P<0.05),其抑制脂质过氧化物的作用与冬虫夏草相近(P<0.05),CN80-2还可提高谷胱甘肽过氧化物酶的含量。