Antonín Jindra

Circulating intercellular cell adhesion molecule-1, endothelin-1 and von Willebrand factor-markers of endothelial dysfunction in uncomplicated essential hypertension: the effect of treatment with ACE inhibitors.

The aim of the study was to examine whether the circulating cell adhesion molecules, von Willebrand factor (vWf) and endothelin-1, are elevated in patients with essential hypertension with no other risk factors for atherosclerosis and thus may serve as a markers of endothelial dysfunction in uncomplicated hypertension. Furthermore, the effect of treatment with the ACE inhibitor, quinapril, on levels of endothelial dysfunction markers were studied. The levels of adhesion molecules (intercellular cell adhesion molecule-1 [ICAM-1], E-selectin, P-selectin), von Wilebrand factor (vWf) and endothelin-1 were measured in patients with hypertension without any other risk factors of atherosclerosis before and after treatment with quinapril (n = 22) and in normotensive controls (n = 22). Compared with normotensive subjects, the hypertensive patients had significantly higher levels of ICAM-1 (238 vs 208 ng/ml, P = 0.02), vWf (119 vs 105 IU/dl, P < 0.05) and endothelin-1 (5.76 vs 5.14 fmol/ml, P < 0.05). Three-month treatment of hypertensive patients with quinapril led to a significant decrease in the levels of endothelin-1 (5.76 vs 5.28 fmol/ml, P < 0.01). We did not observe significant changes in the levels of adhesion molecules and vWf after ACE inhibitor treatment, although a trend toward a decrease was apparent with all these parameters. Patients with uncomplicated hypertension with no other risk factors of atherosclerosis had significantly elevated levels of ICAM-1, vWf, and endothelin-1. Our data suggest that these factors may serve as markers of endothelial damage even in uncomplicated hypertension. In hypertensive patients, treatment with the ACE inhibitor quinapril resulted in a significant decrease in endothelin-1 levels. These findings indicate a beneficial effect of ACE inhibitors on endothelial dysfunction in hypertensive patients.

Purification of pepsins and cathepsin D by affinity chromatography on Sepharose 4B with an immobilized synthetic inhibitor.

Val-D-Leu-Pro-Phe-Phe-Val-D-Leu, a specific inhibitor of aspartate proteinases of the pepsin type, was synthesized. Its bonding to activated 6-aminohexanoic acid-Sepharose 4B afforded an affinity support suitable for the purification of human, porcine, and chicken pepsin, human gastricsin, and bovine cathepsin D. These enzymes bind to the support over the pH range 2-5 at 0-1.5 M concentration of NaCl. A buffer at pH greater than or equal to 6, low ionic strength, and containing 20% dioxane can serve as a general desorption agent. The proteinases were isolated from the crude extracts by a single-step procedure in a high degree of purity and in yields exceeding 70%; human pepsin, however, was not separated from human gastricsin. The support does not show any binding capacity for rat plasma renin at pH 7.4 and for some cysteine endopeptidases (cathepsin B, H, and L) at pH 3-5. The cathepsin D preparations isolated by affinity chromatography on the new support and on pepstatin-Sepharose were of the same degree of purity as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal amino acid sequences, and specific activity.

Lack of Association of Angiotensin-converting Enzyme and Angiotensinogen Genes Polymorphisms with Left Ventricular Structure in Young Normotensive Men

Left ventricular (LV) hypertrophy is a strong predictive factor for cardiovascular morbidity and mortality. LV structure and function are influenced by many variables, including genetic background. The potential role of gene polymorphisms of different components of the renin angiotensin system remains controversial. The aim of this study was to determine the influence of deletion/insertion (D/I) polymorphism of the angiotensin-converting enzyme (ACE) gene and M235-->T polymorphism of the angiotensinogen (AG) gene on left ventricular morphology and function in young normotensive men. The study included 110 normotensive healthy males (mean age 24 +/- 4 years, age range 18 to 34 years) who were assessed by echocardiography for LV structure and function. In all subjects ACE D/I polymorphism was evaluated using a polymerase chain reaction (PCR) method. M235-->T polymorphism assessment was available in 98 individuals. Significant differences between groups according to ACE I/D or AG M235-->T polymorphisms were not found for parameters of LV morphology or for parameters of systolic and diastolic function. When subjects with DD or ID genotypes were grouped, their LV mass index was higher than that in subjects with II genotypes (86 +/- 14 vs 79 +/- 15, r = 0.033, p = 0.05). There were no significant differences among other variables. In a population of young normotensive men where the influence of confounding variables such as age, gender and associated pathological conditions is minimized, the gene polymorphisms of ACE I/D and AG M235-->T are not important determinants of LV structure and function.

Time course of endothelin-1 plasma level in patients with acute coronary syndromes.

An elevated plasma level of endothelin-1 was reported in several cardiovascular conditions including unstable angina pectoris and myocardial infarction. The present study was designed to evaluate the time course of the endothelin-1 release in unstable angina pectoris and to assess its relationship to the development of myocardial infarction and coronary vessel occlusion. The cohort studied included 32 patients with the clinical diagnosis of unstable angina pectoris who had been admitted to the coronary care unit and subsequently underwent coronary angiography (group A). Fourteen patients with chronic stable angina pectoris referred to routine diagnostic coronary angiography served as the control group (group B). A significant difference in the endothelin-1 plasma level was found between both groups, the values being 10.2 ± 5.3 and 6.0 ± 3.1 pg/ml (p < 0.01), respectively. There were, however, no significant differences between the following subdivisions of group A: patients with and without subsequent myocardial infarction; those with angiographically documented occlusion of at least one major branch of the coronary artery and no occlusion; and finally, those with persisting symptoms of angina pectoris and with favorable response to treatment. Neither was there any difference found among the subgroups differing in the time interval between the onset of chest pain and blood sampling. The time course of endothelin plasma concentrations showed elevated values lasting for more than 96 h after the index episode of prolonged chest pain. No correlation with the subsequent clinical course could be inferred. Thus, plasma endothelin level was elevated in patients with unstable angina pectoris and myocardial infarction and the increase persisted for several days after the onset of symptoms.

Association of 344/T/C Aldosterone Synthase Polymorphism (CYP11B2) with Left Ventricular Structure and Humoral Parameters in Young Normotensive Men

Background: Aldosterone plays an important role in development of left ventricular (LV) hypertrophy and myocardial fibrosis. We assessed the influence of the T‐344C polymorphism of aldosterone synthase – the rate‐limiting enzyme in aldosterone biosynthesis – on the structure of the left ventricle in young normotensive men. Design and methods: The population included 113 normotensive mid‐European Caucasian men aged 18–40 years (mean 27 ± 5 years). The genotype was assessed using polymerase chain reaction with subsequent cleavage with restriction enzyme HAEIII (restriction fragment length polymorphism method) and visualization with ethidium bromide. Plasma renin activity (PRA) and plasma aldosterone were measured. All subjects were examined by echocardiography and LV mass was assessed by using M‐mode based ASE formula. Results: The distribution of the genotypes was TT 23%:TC 55%:CC 22%. There were no differences in blood pressure among the groups. Men with the TT genotype had significantly higher levels of PRA (2.7 ± 1.7 vs 1.8 ± 1.0 vs 1.8 ± 1.1 ng/ml/h, p < 0.01) and slightly higher plasma levels of aldosterone (113 ± 64 vs 93 ± 43 vs 87 ± 39 pg/ml, p = 0,12). In the whole population, LV mass index (LVMI) did not differ significantly among the genotypes (92 ± 16 vs 86 ± 18 vs 84 ± 16 g/m 2 , p = 0.20). In the population divided according to PRA, subjects with high renin had significantly higher LVMI in presence of the TT genotype (95 ± 17 vs 84 ± 16 vs 81 ± 15 g/m 2 , p < 0.05). Conclusions: In agreement with previous studies, we found that the TT genotype of T‐344C polymorphism of aldosterone synthase gene was associated with significantly higher levels of PRA in normotensive men. In subjects with high PRA, the TT genotype was associated with higher values of the LVMI.

Association Analysis of Arg16Gly Polymorphism of the β 2 -Adrenergic Receptor Gene in Offspring from Hypertensive and Normotensive Families

Objective: Since g 2 -adrenergic receptors ( g 2 AR) can influence blood pressure not only by vasodilation, but also participate in noradrenaline release from sympathetic nerve endings, we have studied whether Arg16Gly polymorphism of the g 2 AR gene is associated with predisposition to essential hypertension and increased plasma noradrenaline concentration in offspring from normotensive (SN) and hypertensive parents (SH). Design and methods: The study population consisted of 105 young SN and 101 SH subjects matched for age and body mass index. Arg16Gly polymorphism of the g 2 AR gene was determined by polymerase chain reaction (PCR) technique and subsequent incubation with NcoI restriction enzyme. Resulting fragments were separated using electrophoresis on a 4.2% Metaphor agarose gel. Results: SH already had significantly higher systolic BP, and a tendency to higher diastolic BP than the SN group. The frequency of Arg/Arg homozygotes was significantly increased in SH when compared to SN (25% vs 15%). Results of logistic regression analysis showed the highest relative risk for the Arg/Arg genotype and suggested a recessive action of the Arg16 variant. There was an increased diastolic BP in Arg/Arg homozygotes of the SN group ( p = 0.029). This genotype also had a tendency to increased heart rate in both groups ( p = 0.049). There was no relationship of this polymorphism with plasma noradrenaline concentration. Conclusion: Our findings suggest that genetic variability of the g 2 AR gene is implicated in predisposition to essential hypertension. However, the contradictory results between individual studies indicate that the action of the g 2 AR gene is indirect, through multiple intermediate phenotypes and gene interactions.

Association between tyrosine hydroxylase polymorphisms and left ventricular structure in young normotensive men.

Abstract Tyrosine hydroxylase (TH) is a rate-limiting enzyme for catecholamine biosynthesis. Increased sympathetic activity is associated with an increased left ventricular (LV) mass. However, the influence of TH gene polymorphisms on LV structure and function has yet to be investigated. Here, we analyse the association of Val-81-Met and tetranucleotide TCAT repeat TH polymorphisms with LV structure and function (assessed by echocardiography) in 108 normotensive men aged ≤ 35 years (mean age: 25±4 years) with body mass index (BMI) ≤ 30 kg/m2 (mean BMI: 23±3 kg/m2). The distribution of genotypes was VV homozygotes (n=42), VM heterozygotes (n=49) and MM homozygotes (n=17). The Val-81-Met polymorphism showed significant linkage disequilibrium with the TCAT polymorphism (P<0.0001). No differences were seen between the subgroups with respect to age, BMI and blood pressure. Compared with the VV and VM genotypes, subjects with the MM genotype showed significantly (all P<0.05) increased LV cavity diameter (VV: 52.8±3.9 mm, VM: 52.9±3.6 mm, MM: 56.1±3.2 mm), global LV mass (VV: 159±31 g, VM: 165±36 g, MM: 187±30 g) and LV mass index (VV: 81±14 g/m2, VM: 84±17 g/m2, MM: 93±12 g/m2). No differences were seen between the subgroups in parameters of LV function. In addition, plasma epinephrine and norepinephrine levels were comparable in the three subgroups. The results suggest an important association between the MM genotype of Val-81-Met TH gene polymorphism and increased LV cavity dimension and mass in a young normotensive male population, indicating an important role for genetic determination of the sympathetic system in LV growth.

Blood pressure, endothelial function and circulating endothelin concentrations in liver transplant recipients.

Objectives To study candidates for liver transplant before and 6 weeks after transplant, and to elucidate the role of endothelial dysfunction and plasma endothelin concentrations in the development of hypertension. Design Prospective follow-up study. Setting Institutional, outpatient. Patients and controls Fifteen patients (11 men, four women, mean age 46.7 ± 13.2 years) with end-stage liver disease (ESLD) and healthy volunteers of comparable age and sex. Methods We performed office blood pressure readings and 24 h ambulatory blood pressure monitoring (ABPM), measurements of endothelial-dependent vasodilatation using high-resolution ultrasound in the brachial artery at rest and during reactive hyperemia, and plasma endothelin-1 assays 3 months before and 6 weeks after the transplant. Results Office systolic and diastolic blood pressures increased significantly 6 weeks after liver transplantation (from 116.6 ± 14.1 to 139.9 ± 19.5 mmHg and from 68.6 ± 9.5 to 84.1 ± 9.8 mmHg, respectively; both P < 0.001). Hypertension based on office blood pressure readings increased from 6.7 to 40% (P < 0.05). Mean 24 h systolic blood pressure increased from 118.7 ± 10.3 to 140.0 ± 19.0 mmHg (P < 0.001), mean 24 h diastolic blood pressure increased from 86.0 ± 7.7 to 104.8 ± 13.9 mmHg (P < 0.001) and heart rate increased from 74.8 ± 10.2 to 80.2 ± 8.2 beats/min (P < 0.05). Brachial artery flow-mediated dilatation did not change throughout the study (before transplant: 4.2 ± 4.0%; after transplant: 6.3 ± 5.4%; NS) and did not differ from that in controls (5.2 ± 3.8%). Plasma endothelin-1 was increased in patients with ESLD (15.3 ± 2.6 pg/ml) compared with controls (5.6 ± 0.4 pg/ml; P < 0.001) and remained unchanged 6 weeks after liver transplantation (14.1 ± 3.7 pg/ml). Conclusion Our results show increased blood pressure with suppressed circadian blood pressure variability in liver graft recipients 6 weeks after transplant and no change in endothelial function and plasma endothelin concentrations. Therefore, the blood pressure increase documented in our study cannot be explained by endothelial dysfunction. Twenty-four hour ABPM should be performed routinely in patients who have undergone liver transplant.

Local Changes in the Plasma Endothelin Level in the Coronary Artery Immediately after Percutaneous Transluminal Coronary Angioplasty

Endothelin plays an important role in cardiovascular pathology. As one of the most important endothelium-derived vasoconstrictor substances, endothelin together with endothelium-derived vasodilating factor control vascular tone and contribute to the vasoconstrictory response if the production of endothelium-derived vasodilating factor is impaired. The aim of the study was to assess the changes of the local endothelin level in coronary circulation immediately after percutaneous transluminal coronary angioplasty (PTCA). Plasma endothelin levels were measured in blood samples from the peripheral vein and ostium of the coronary artery before the angioplasty, and from the distal coronary artery just beyond the dilated segment and the peripheral vein immediately after the procedure. The plasma endothelin level was significantly higher in the ostium of the coronary artery already prior to PTCA as compared to the peripheral vein (10.9 +/- 3.4 vs. 7.2 +/- 2.1 pg/ml, p < 0.005). There was no change in the endothelin level in the coronary artery distal to the dilated segment immediately after the procedure as compared to the initial level, although this level was higher than the postangioplasty venous level (9.8 +/- 2.9 vs. 7.7 +/- 2.0 pg/ml, p < 0.005). Individual changes in coronary-artery plasma endothelin levels as a response to coronary angioplasty were disparate. An increase and a decrease in coronary artery plasma endothelin levels by more than 2 pg/ml after coronary angioplasty were observed in 3 and 6 subjects, respectively. In conclusion, increased plasma endothelin levels were found in blood samples drawn from the coronary artery as compared to the peripheral vein. There was no further change in the plasma endothelin level in the coronary artery distal to the dilated segment after angioplasty; however, the individual responses were disparate.

Relationship Between Plasma Catecholamines and the Renin-Aldosterone System During Exercise in Normal and Essential Hypertensive Subjects

Interrelations were investigated between blood pressure, plasma epinephrine (E), norepinephrine (NE), dopamine (D), aldosterone, cortisol concentrations, active and inactive plasma renin activity (PRA), and age in 21 normotensive subjects (aged 20-60 years) and in 25 patients (aged 20-63 years) with essential hypertension (EH). These parameters were measured at rest and during exercise on a bicycle ergometer. In normotensive subjects basal and exercise-stimulated levels of plasma NE increased with age which was not observed in EH. In hypertensive patients there was a higher plasma D concentration under the exercise as compared with normotensive controls. In the normotensives, basal active PRA was inversely related to age (p less than 0.05), and during initial 8 min of exercise active PRA significantly correlated with plasma E and plasma NE. Moreover, absolute changes from basal to acutely stimulated values of active PRA were directly related to the changes of plasma E and NE (p less than 0.001). In hypertensive patients these relationships were not found. However, in the hypertensives there were significant positive correlations between the increases of active PRA, plasma E, plasma NE on the one hand and their respective basal values on the other hand. The results indicate very strong functional relationship between the sympathetic-adrenomedullary and renin-angiotensin systems during initial interval of acute stimulation in normotensive subjects. Essential hypertension is not a pathophysiologically homogenous disease with respect to reactivity and interaction of plasma catecholamines and PRA. Separate regulatory pathways exist for plasma active and inactive renin. During short-time exercise aldosterone secretion is related rather to the renin-angiotensin system than to the hypothalamic-pituitary axis.