[Endothelial and metabolic effects of perindopril in patients with essential hypertension].

OBJECTIVE: To elucidate endothelial and metabolic effects of perindopril and their interaction in patients with uncomplicated essential hypertension. METHODS: The study involved 30 patients treated with perindopril (5-10 mg/day) for 3 months. The following parameters were registered at baseline and at the end of the study: body mass index, waist circumference, blood lipids and glucose, flow-mediated vasodilation (FMVD) of brachial artery assessed by ultrasound. RESULTS: Treatment with perindopril was associated with significant improvement of FMVD (6.7 ± 4.1% versus 8.7 ± 5.4% at the end of the study, p<0.05) as well as decrease of blood triglycerides (-18%, p<0.05) and glucose (-9%, p<0.01) with no significant changes of other metabolic parameters. Correlation analysis showed no relationship between changes of FMVD and blood pressure during the study (r= -0.14, p=0.42 r= -0.13, p=0.46 for systolic and diastolic blood pressure, respectively) whereas inverse association was observed with changes of blood glucose (r= -0.50, p<0.01). CONCLUSIONS: Thus our data confirm the ability of perindopril to restore impaired endothelial function in patients with essential hypertension independently of blood pressure reduction and make possible to propose its positive metabolic effect relative to changes associated with insulin resistance. It seems that endothelial effect of perindopril may in part be related to diminished adverse influence of metabolic changes on vascular wall.

[Detection of structural changes of large arteries by characteristics of peripheral pulse wave: comparison with high resolution ultrasonic investigation].

AIM: To compare high-resolution ultrasound of major arteries and the method of vascular stiffness evaluation by digital volume pulse photoplethysmography after sublingual nitroglycerin in diagnosis of structural vascular changes. MATERIAL AND METHODS: The comparison of the two methods was made in 110 volunteers (mean age 31.9 +/- 11.5 years). The study protocol included measurement of blood pressure (BP), blood lipids and glucose, evaluation of IMT of the carotid arteries by ultrasonography, baseline stiffness index (SIbl) and after sublingual nitroglycerin (SIng) by photoplethysmography. Reproducibility of photoplethysmography was evaluated in 20 volunteers (mean age 20.3 +/- 1.4 years) with repeated measurement after 1 week. The results were tested in 40 volunteers of different age groups. RESULTS: There were significant correlations of IMT, SIbl and SIng with risk factors and close interrelations of these parameters. SIng better explained variability of IMT compared to SIbl (r = 0.79, R2 = 0.62, p < 0.001 versus r = 0.67, R2 = 0.45, p < 0.001, respectively). Relations of IMT with risk factors were lost after correction for SIng. Reproducibility of SIng was higher than SIbl (+/- 5.1% versus +/- 10.9%, respectively) and than those for IMT found in the literature. Mean IMT values for random sample evaluated by ultrasonography and calculated by estimated equation of linear regression for SIng and IMT did not differ significantly (0.576 +/- 0.087 mm versus 0.570 +/- 0.074 mm, p = 0.44; r = 0.71, p < 0.001, mean difference 0.007 +/- 0.051 mm). CONCLUSION: The method of vascular stiffness measurement is comparable with ultrasonography in terms of vessel structure evaluation and possesses higher reproducibility. The test with nitroglycerin substantially increases its diagnostic potential and reproducibility.

[Comparative assessment of hypotensive, metabolic, and endothelial effects of indapamide-retard and hydrochlorothiazide in patients with essential hypertension].

AIM: To compare hypotensive, metabolic, and endothelial effects of indapamide-retard and hydrochlorothiazide. MATERIAL AND METHODS: Patients (n=50) with essential hypertension were given either indapamide-retard (1.5 mg/day, n=25) or hydrochlorothiazide (25 mg/day, n=25) for 12 weeks. Dynamics of the following parameters were studied: blood pressure, blood lipids and glucose, total coronary risk, carotid artery intima-media thickness, reaction of brachial artery to endothelium-dependent and endothelium-independent stimuli registered by high resolution ultrasound. RESULTS: Indapamide-retard and hydrochlorothiazide demonstrated similar hypotensive efficacy. Indapamide-retard turned out to be metabolically neutral while in patients receiving hydrochlorothiazide we observed significant elevation of triglycerides (+15.3%, p<0.05) and glucose (+12.2%, p<0.05). This resulted in the lack of lowering of total coronary risk during treatment with hydrochlorothiazide. Significant intergroup differences were revealed in effects on endothelium-dependent vasodilation with tendency to improvement and to significant worsening (-17%, p<0.05) in indapamide and hydrochlorothiazide treated patients, respectively. CONCLUSION: Despite similar hypotensive efficacy there were significant differences in metabolic and endothelial effects of 2 diuretics in favor of indapamide. This could potentially matter for long term cardiovascular prognosis.

Computational modeling of three-dimensional microwave tomography of breast cancer.

Microwave tomographic approach is proposed to detect and image breast cancers. Taking into account the big difference in dielectrical properties between normal and malignant tissues, we have proposed using the microwave tomographic method to image a human breast. Because of the anatomical features of the objects, this case has to be referred to the tomography with a limited angle of observation. As a result of computer experiments we have established that multiview cylindrical configurations are able to provide microwave tomograms of the breast with a small size tumor inside. Using the gradient method, we have developed a computer code to create images of the three-dimensional objects in dielectrical properties on microwave frequencies.

Dielectrical model of cellular structures in radio frequency and microwave spectrum. Electrically interacting versus noninteracting cells.

A model of dielectrical properties of cellular structures of a tissue has been proposed. Cellular structures were presented as a composition of membrane covered spheres and cylinders that do not interact with each other. No restrictions were applied to the thickness of cellular membranes. The model was further generalized into a case of electrically interacting cells. The difference in dielectrical properties calculated with the model of electrically noninteracting versus interacting cells is inversely dependent on frequency. At biological values of cellular volume fraction near 0.7 (packed configuration) the difference is about 10%-15% in resistance and in epsilon' for frequencies near 0.1 MHz. Experimental data for myocardial tissue and theoretical data, for both interacting and noninteracting models, reasonably agree at frequencies of 1-100 MHz.

[Effect of enalapril maleate on vascular endothelial function and platelet-endothelial interactions in patients with essential hypertension]. / Vliianie terapii énalaprila maleatom na funktsiiu sosudistogo éndoteliia i trombotsitarno-éndotelial'nye vzaimosviazi u bol'nykh gipertonicheskoi bolezn'iu.

AIM: Evaluation of endothelial function and platelet-endothelial interactions in patients with essential hypertension and dynamics of these changes in the course of treatment with enalapril maleate. MATERIALS AND METHODS: The study included 37 patients with essential hypertension and 22 normotensive volunteers. 17 of hypertensive patients received enalapril maleate (enap, KRKA) 5-20 mg/day during the period of 1.5 months. The complex of investigations included: measurement of total plasma cholesteroi, 12-lead ECG, echocardiography, high-resolution ultrasound investigation of brachio-cephalic arteries, evaluation of flow-mediated dilation, measurement of von Willebrand's factor, spontaneous and induced platelet aggregation. RESULTS: Patients with essential hypertension exhibited higher levels of von Willebrand's factor in plasma and degree of spontaneous and induced platelet aggregation as well as lower responses of vessel wall to hemodynamic stimuli compared to normotensive healthy individuals. There was a strong correlation between endothelial function markers and CAD risk factors, elevation of platelet activity. Treatment with enalapril maleate led to a statistically significant decrease of von Willebrand's factor in plasma and ex vivo platelet aggregation whereas flow-mediated dilatation increased. Values of endothelial function markers and platelet activity approached to those of normotensive subjects and these changes were accompanied by a decrease of ECG signs of left ventricular hypertrophy. CONCLUSION: Patients with essential hypertension were found to have compromised endothelial function. However, the degree of endothelial dysfunction depends not on hemodynamic parameters, but on the cumulative effect of CAD risk factors. Treatment with enalapril maleate may lead to normalisation of endothelial function and decrease of platelet activity.

Microwave spectroscopy of myocardial ischemia and infarction. 2. Biophysical reconstruction.

The proposed dielectrical relaxation model of the myocardium in the microwave spectrum has been verified both on test solutions and on normal canine myocardium. Furthermore, the model was utilized to reconstruct the changes in tissue properties (including myocardial bulk resistance and water content) following myocardial acute ischemia and chronic infarction. It was shown that the reconstructed myocardial resistance and water content correlate dynamically with the process of the development of acute myocardial ischemic injury. In chronic cases the reconstructed resistance and water content of infarcted myocardium are significantly different from that of normal myocardium: the resistance is lower and water content is higher than in normal myocardium.

Three-dimensional microwave tomography: experimental prototype of the system and vector born reconstruction method.

A method of image reconstruction in three-dimensional (3-D) microwave tomography in a weak dielectric contrast case has been developed. By utilizing only one component of the vector electromagnetic field this method allows successful reconstruction of images of 3-D mathematical phantoms. A prototype of the 3-D microwave tomographic system capable of imaging 3-D objects has been constructed. The system operates at a frequency of 2.36 GHz and utilizes a code-division technique. With dimensions of the cylindrical working chamber z = 40 cm and d = 60 cm, the system allows measurement of an attenuation up to 120 dB having signal-to-noise ratio about 30 dB. The direct problem solutions for different mathematical approaches were compared with an experimentally measured field distribution inside the working chamber. The tomographic system and the reconstruction method were tested in simple experimental imaging.