Effect of intracoronary estrogen on coronary collateral blood flow velocity

The effect of estrogen on collateral circulation has not been previously investigated. We assessed the acute effect of estradiol on collateral blood flow velocity with the Flowire during percutaneous transluminal coronary angioplasty and found that intracoronary estradiol decreased collateral blood flow velocity compared with controls.     

Adventitial expression of recombinant eNOS gene restores NO production in arteries without endothelium

The current study was designed to determine the effect of recombinant endothelial nitric oxide synthase (eNOS) gene expression on endothelium-dependent relaxations to bradykinin in isolated canine basilar, coronary, or femoral arteries. Arterial rings were exposed ex vivo (30 minutes at 37 degrees C) to an adenoviral vector encoding either the eNOS gene (AdCMVeNOS) or the beta-galactosidase reporter gene (AdCMVbeta-Gal). Twenty-four hours after transduction, transgene expression was evident mainly in the adventitia. Expression of recombinant proteins was much higher in basilar arteries than in coronary or femoral arteries. Rings of control, AdCMVbeta-Gal, and AdCMVeNOS arteries with and without endothelium were suspended for isometric tension recording. Levels of cGMP were measured by radioimmunoassay. In AdCMVeNOS basilar arteries with endothelium, relaxations to low concentrations of bradykinin (3 x 10(-11) to 10(-9) mol/L) were significantly augmented. In contrast, in coronary and femoral arteries with endothelium, AdCMVeNOS transduction did not affect relaxations to bradykinin. Removal of the endothelium abolished bradykinin-induced relaxations in control and AdCMVbeta-Gal basilar arteries. However, in basilar arteries transduced with AdCMVeNOS even when the endothelium was removed, stimulation with bradykinin (3 x 10(-11) to 10(-9) mol/L) caused relaxations as well as increases in cGMP production. The relaxations to bradykinin were completely blocked by an NOS inhibitor, NG-nitro-L-arginine methyl ester. Electron microscopic analysis revealed that recombinant eNOS protein was expressed in fibroblasts of the basilar artery adventitia. These results suggest that genetically modified adventitial fibroblasts may restore production of NO in cerebral arteries without endothelium. Our findings support a novel concept in vascular biology that fibroblasts in the adventitia may play a role in the regulation of vascular tone after successful transfer and expression of recombinant eNOS gene.     

Use of elimination of plasma phospholipid membranes for detection of "lupus anticoagulant" effects

The coagulation activity of plasma phospholipid membranes (PM) was measured in plasma depleted for platelets (PDP) in 50 normal subjects and 33 patients with the antiphospholipid syndrome (APS) and the "lupus anticoagulant" in the plasma. The normal value for phospholipid activation of clotting was 99.8 +/- 3.5% (from 75 to 125%), whereas in patients with APS and lupus anticoagulant it was 42.1 +/- 8.2% (p < 0.001). Addition of PM from patients' PDP to normal plasma free from PM did not normalize clotting. Addition of PM from normal plasma to patients' PDP normalized the clotting time. Therapy with discrete plasmapheresis increased the phospholipid activation value in the patients from 42.1 to 73.3% (p < 0.01), which was due to removal of the PM-antiphospholipid antibody complex from PDP. The proposed microfiltration method can be used in the complex of tests for detecting the lupus anticoagulant in patient's plasma.     

数字信号处理(上)

实际上,最简单的数字信号处理系统仅仅包括一个模数转换器(A/D)和一个数模转换器(D/A),但是,在数字领域方面的信号处理部分却需要进行认真的考虑(如图1所示).     

米其林低滚动阻力绿色环保轮胎

世界著名轮胎制造商米其林呼吁全欧洲的汽车都改用绿色环保轮胎。米其林称．如果欧洲所有的汽车都装备低滚动阻力的绿色环保轮胎，每年将节省45亿升柴油和15亿升汽油．同时每年将减少二氧化碳排放1500万吨．相当于6亿棵树1年吸收的二氧化碳的总和。     

Stability analysis of the FitzHugh-Nagumo differential equations driven by impulses: applied to the electrical firing of magnocellular neurons

A stability analysis is carried out for a mathematical model which describes the electrical firing of a single vasopressin neuron. The model used in a FitzHugh-Nagumo-type system which is driven by impulses. The analysis is based on recent developments in the stability theory of impulsive differential equations. Conditions are derived under which the system of differential equations is stable at two of its equilibrium points. Biologically this bistability represents the cell alternating between periods of electrical activity and silence. The conditions for stability are specified in terms of the amplitude and frequency of the impulses perturbing the system. Both stochastic and deterministic impulses are considered.