The oscillatory course of the electroreduction of thiocyanate complexes of nickel(II) at mercury electrodes — experiment and simulation

Following our previous studies confirming the role of adsorbed electrocatalytic SCN^? ions in the formation of negative polarisation resistance in the electroreduction of the Ni(II)SCN^? complexes at the mercury electrode, we present further experimental and theoretical investigations of the oscillatory behaviour of this process. Examples of current oscillations collected for various experimental conditions are shown. A numerical model involving partial differential equations of diffusion transport is constructed for simulations of reported oscillations. Comparison of experimental and theoretical oscillations confirms both the electrochemical source of oscillations and the validity of the numerical approach proposed. With this approach it was possible to explain the effect of a side formation of the inhibitory layer of NiS on the shapes of oscillations.     

Effect of tobacco smoking on endothelial function in patients with coronary arteriosclerosis

Smoking is one of the most important risk factors of atherosclerosis and ischaemic heart disease. Endothelial dysfunction is a pathological result of smoking. The aim of the study was to examine the influence of cigarette smoking on biochemical parameters of endothelial function in persons with angiographically confirmed coronary arteries atherosclerosis. The study group included 117 men: 55 patients (mean age 58.8 +/- 10.4) with ischaemic heart disease and 62 healthy subjects (mean age 47.1 +/- 9.3) of control group. In all patients blood lipid concentrations, biochemical parameters of endothelial function (nitric oxide, endothelin-1, sICAM, selectin-E), and inflammation parameters (interleukin-1 beta, interleukin-6) were measured. In a group of smoking patients both: with atherosclerosis and in control subjects nitric oxide (NO) concentrations in serum were decreased in comparison to nonsmokers. In patients with diagnosed coronary arteries atherosclerosis interleukin-6 and sICAM concentrations were increased in comparison to non-smokers. It is concluded that cigarette smoking activates or maintains inflammatory reaction in vessels with atherosclerotic changes.     

Percutaneous procedures for the repair of iatrogenic occlusion or stenosis of peripheral vessels in children--report of 5 cases

Invasive percutaneous diagnostic or therapeutic procedures are associated with the risk of thrombosis and occlusion of peripheral vessels which are used for vascular access. Data on the transcatheter therapy of vascular complications in children are scarce. We described five children in four of whom percutaneous transluminal balloon angioplasty of occluded peripheral vessels was successfully performed. Technical aspects of this treatment and indications are discussed.     

The Effect of Verapamil on Response of Coronary Vasomotion to Handgrip Exercise in Symptomatic Patients with Hypertrophic Cardiomyopathy

Objectives. To assess the effect of verapamil on the response of diastolic coronary blood flow velocity (CBFV) and coronary vascular resistance index to handgrip exercise in symptomatic HCM patients. Design. In 13 patients with HCM, the CBFV was detected in the distal portion of left anterior descending coronary artery using high-sensitivity transthoracic Doppler echocardiography. The peak diastolic CBFV and coronary vascular resistance index (calculated as the ratio of mean aortic pressure to CBFV) was measured at baseline and during handgrip exercise. Changes of these parameters induced by the exercise (expressed as the percentage of baseline values) were compared on verapamil treatment and after verapamil withdrawal. The same measurements were obtained in 10 healthy control subject. Results. In HCM patients, the increase in CBFV during exercise was significantly higher on than off verapamil therapy (16.2 ± 5% versus 6.8 ± 3.8%, p < 0.001). In healthy controls, exercise-induced increase in CBFV was comparable to CBFV changes in HCM patients receiving verapamil (17.4 ± 5.7 versus 16.2 ± 5%, p < 0.05) and was significantly greater than the CBFV response in HCM patients off verapamil (17.4 ± 5.7% versus 6.8 ± 3.8 % p < 0.005). During exercise the coronary vascular resistance index decreased on verapamil and increased after drug withdrawal (–5.8 ± 5.6% versus 1.1 ± 5.1%, p < 0.001). In healthy controls the coronary vascular resistance index decreased during exercise –8.5 ± 4.5% to similar extent as in HCM patients on verapamil. Conclusion. In HCM symptomatic patients, verapamil improved coronary vasomotor response to physical stress. Verapamil was able to restore adequate vasodilator response to handgrip exercise.     

Peroxynitrite-induced changes of thiol groups in human blood platelets

In this study we investigated sulfhydryl and disulfide metabolism in blood platelets treated with peroxynitrite (ONOO-) at concentrations of 10, 100, and 1000 microM. In platelets incubated with peroxynitrite, a decrease of both protein and low molecular weight thiols (glutathione, cysteine and cysteinylglycine) was observed. The reduction of platelet free thiols caused by ONOO- was dose dependent. We found that peroxynitrite induces the oxidation of platelet free SH-groups. Platelets contain a large fraction of glutathione in reduced form (GSH). We showed that after ONOO- treatment, GSH/GSSG ratio in platelets was distinctly decreased. The presented results suggest that oxidation of thiols and depletion of GSH in platelets caused by peroxynitrite may be responsible for cytotoxic effects of this compound.     

Influence of insertion-deletion polymorphism of the angiotensin converting enzyme gene on left ventricular hypertrophy in patients with aortic stenosis--differences in men and women

The role of different parameters (including genetic factors) on the timing and extend of left ventricle hypertrophy in patients with aortic stenosis is not defined. In our study we analyze the influence of clinical, echocardiographic parameters and I/D polymorphism of the angiotensin converting enzyme gene on the left ventricle hypertrophy (left ventricle mass index) in this group of patients. The study was done with the group of 302 pts with aortic stenosis--120 women and 182 men; mean age 58 +/- 11 yrs. Stepwise (backward) regression was used to assess the influence of the analyzed parameters (age, gender, history of hypertension, EF, MGA, presence of significant coronary artery disease and I/D ACE polymorphism) on the LVH in the all pts and in the women and the men separately. In the whole group the LVMI depends on EF (t = -6.5; p = 0.0001--higher LVMI in lower EF), MGA (t = 3.9; p = 0.0001--higher LVMI in higher MGA) and gender (t = 2.8; p = 0.005--higher LVMI in men). In women LVMI was related with EF (t = -3.6; p = 0.001--higher LVMI in lower EF), age (t = 2.9; p = 0.004--higher LVMI in older pts) and MGA (t = 2.5; p = 0.013--higher LVMI in higher MGA). In men the LVMI depends on EF (t = -4.8; p = 0.0001--higher LVMI in lower EF) and MGA (t = 1.98; p = 0.049--higher LVMI in higher MGA). Significant relationship between LVMI and results of I/D ACE polymorphism was observed both in women and men. I/D polymorphism relationship with LVMI was divergent in these 2 groups--association of higher LVMI with lack of DD type of polymorphism in women and presence of DD polymorphism in men. CONCLUSIONS: 1. Left ventricle hypertrophy in pts aortic stenosis is higher in men than in women. 2. In women left ventricle hypertrophy is related with ejection fraction, maximal aortic gradient, age and I/D ACE polymorphism; in men it is related to EF, MGA and I/D ACE polymorphism. 3. The influence of I/D ACE polymorphism on the left ventricle hypertrophy is divergent in women and men--in women related to the lack of DD polymorphism, in men related to the presence of DD polymorphism.