Genetic variation screening of TNNT2 gene in a cohort of patients with hypertrophic and dilated cardiomyopathy.

Mutations in troponin T (TNNT2) gene represent the important part of currently identified disease-causing mutations in hypertrophic (HCM) and dilated (DCM) cardiomyopathy. The aim of this study was to analyze TNNT2 gene exons in patients with HCM and DCM diagnosis to improve diagnostic and genetic consultancy in affected families. All 15 exons and their flanking regions of the TNNT2 gene were analyzed by DNA sequence analysis in 174 patients with HCM and DCM diagnosis. We identified genetic variations in TNNT2 exon regions in 56 patients and genetic variations in TNNT2 intron regions in 164 patients. Two patients were found to carry unique mutations in the TNNT2 gene. Limited genetic screening analysis is not suitable for routine testing of disease-causing mutations in patients with HCM and DCM as only individual mutation-positive cases may be identified. Therefore, this approach cannot be recommended for daily clinical practice even though, due to financial constraints, it currently represents the only available strategy in a majority of cardio-centers.

[Aldosterone as an endogenous cardiovascular toxin and the options for its therapeutic management]. / Aldosteron jako endogenní kardiovaskulární toxin a moznosti jeho terapeutického ovlivnení.

In physiological, as well as pathological situations, aldosterone significantly influences volume, pressure and electrolyte balance. Primary hyperaldosteronism is caused by autonomous over-production, most frequently due to adrenal adenoma. Patients with primary hyperaldosteronism (Conn's syndrome) have more pronounced left ventricular hypertrophy and higher frequency of cardiovascular events than patients with essential hypertension (EH) with comparable blood pressure values. Consequently, there is an increased interest in the role ofaldosterone tissue function in cardiovascular disease. The aim of the present paper is to emphasise the pleiotropic actions of aldosterone on cardiovascular system and the options for their therapeutic management. Apart from the effects of circulating aldosterone on BP and its renal actions on water and electrolyte excretion, extra-renal effects are also been explored; paracrine affects through tissue mineralocorticoid receptors (MR) may impact on endothelial dysfunction, vascular elasticity, inflammatory changes in the myocardium, vessels and kidneys. Initial oxidative stress due to increased aldosterone concentrations may initiate subclinical endothelial changes and subsequent myocardial fibrosis. The effects on all three layers of vascular wall, together with increased blood coagulation and vascular thrombogenicity increases likelihood of microthrombosis and tissue microinfarctions. Slight increase in aldosterone concentrations in cardiac tissue adversely affects myofibrils as well as coronary artery function. Similar to peripheral vessels, it increases collagen content and changes vascular rigidity and the velocity of pulse wave and facilitates development of perivascular fibrosis. Higher salt intake may potentiate these pathophysiological effects of aldosterone, while higher intake of potassium may restrict them. Aldosterone vasculopathy together with perivascular fibrosis occurring at aldosterone concentrations seen with heart failure contributes to manifestation of heart failure. Consequently, aldosterone may rightly be called "cardiovascular toxin". The adverse effects of aldosterone in patients on long-term ACEI therapy are further facilitated by the aldosterone's ability to evade inhibitory effects of ACEI and parallel activation of renin-angiotensin system. To manage these situations, receptors of mineralcorticoids or direct renin inhibitor aliskiren are used. The positive effect of MR blockade is based on an increased release of nitric oxide (NO) with further improvement in endothelial functions. Detailed review of pleotropic effects of aldosterone helps to clarify a number of pathophysiological situations in essential hypertension, supports the view ofaldosterone as a potential cardiovascular toxin and indicates the use of mineralocorticoid receptor blockers in resistant hypertension and patients with cardiovascular or renal organ damage.

[Reducing food salt content--a neglected approach to hypertension prevention and treatment in the population]. / Snízení obsahu soli v potrave--opomíjený postup v prevenci a lécbe hypertenze v populaci.

Long-term dietary salt supply, disproportional to the high metabolic requirements, plays an important role in pathogenesis of arterial hypertension. BP, its rise with age and hypertension prevalence in the population are directly proportional to sodium supply. Consistent effect of salt supply on the BP values is documented from observational as well as randomised controlled studies. It is, therefore, possible to assume that decrease in salt intake in the population could positively affect population BP mean, age-related increase in BP as well as a range of cardiovascular complications of hypertension and could thus contribute to improving the course and prognosis of this "non-infectious epidemy", the incidence of which exceeds 30% in the adult population and increases continually with age. Based on a review of published population-based observations and clinical studies, the paper summarizes briefly the opinions on the impact of the sodium chloride dietary intake modifications on BP, outcomes of these modifications within various historical, ethnic, experimental and clinical contexts, impact on BP morbidity and mortality, population-based importance of the current high salt supply decrease on these indicators and possible utilization in the primary prevention of hypertension.

Association of the -344T/C aldosterone synthase gene variant with essential hypertension.

The aldosterone synthase gene (CYP11B2) is an important candidate gene region in essential hypertension. We therefore studied the association of -344T/C polymorphism of the CYP11B2 gene with the presence and severity of hypertension in a case-control study. We studied 369 individuals, of whom 213 were hypertensive patients (139 controlled hypertensive, 74 resistant hypertensive) and 156 were healthy normotensive subjects. The -344T/C polymorphism of the CYP11B2 gene was determined using polymerase chain reaction - restriction fragment length polymorphism analysis. The distribution of genotypes in normotensive controls and hypertensive subjects were: TT 25.6 vs. 31.9 %, TC 51.9 vs. 57.3 % and CC 22.4 vs. 10.8 %. The -344T/C variant was associated with hypertension. Subjects carrying the -344T allele had a greater risk of hypertension compared to those having C allele (chi(2)=5.89, p<0.05). The frequency of CC genotype was significantly lower in hypertensive patients than in normotensive controls (chi(2)=9.44, p<0.01). A stepwise logistic regression analysis confirmed these findings. We did not find an association of -344T/C variant with the resistance of hypertensive patients to combination therapy, but we observed an association of -344T/C polymorphism of aldosterone synthase gene with increased risk of hypertension. These results support a potential role of -344T/C CYP11B2 gene polymorphism in genetic predisposition to develop hypertension.

[Does the rennin inhibitor aliskiren offer promising novel opportunities in the treatment of cardiovascular diseases?]. / Predstavuje inhibitor reninu aliskiren nové výhledové moznosti v lécbe kardiovaskulárních onemocnení!

The renin-angiotensin-aldosterone system (RAAS) plays an important part in the pathogenesis of arterial hypertension and the complications it causes in organs (the heart, the circulatory system, the brain, the kidneys), heart failure and kidney diseases. Materials that block the most upstream point of the RAAS cascade (ACE inhibitors - ACEI, AT1,-receptor (AT1R) blockers, aldosterone receptor blockers) have greatly expanded our options in the treatment and primary and secondary prevention of cardiovascular and renal diseases. ACEI and AT1R blockers interrupt the normal feedback provided by the release of renin into the circulatory system from the kidneys. After they are applied the reactive increase in active circulating renin leads to increased creation of angiotensin I and angiotensin II and the subsequent return of aldosterone secretions to pre-treatment values ("escape" phenomenon). The possible negative effect of these intermediary products of an incomplete blockade of RAAS on organ complications lead to an effort to develop a material that could block the renin-angiotensin cascade at its first stage--i.e. a renin blocker. The first efforts with renin antibodies or peptide analogues of renin prosegments failed to satisify the basic requirements for long-term medication--effectiveness when used orally. In recent years the first non-peptidic, oral renin ihibitor providing sustained effects has been developed, aliskiren fumarate. Aliskiren reduces BP depending on the dose (50-300 mg/day) in monotherapy or in combination with hydrochlorothiazide. Aliskiren lowers plasma renin activity (PRA) and neutralises the activation of the RAAS triggered by hydrochlorothiazide. Ambulatory BP monitoring has shown that taking the medicine once a day has a 24-hour effect and its continued residence in the kidneys suggests renoprotective effects. The compound is in the third stage of clinical tests as a monotherapy or in combination for the treatment of hypertension. It has also been shown to have an influence on the regression of cardiac hypertrophy (Aliskiren in Left-Ventricular Hypertrophy trial - ALLAY), the treatment of heart failure (Aliskiren Observation of Heart Failure Treatment trial - ALOFT) and diabetic (Aliskiren in the Evaluation of Proteinuria in Diabetes trial - AVOID). In April 206, the FDA permitted the use of aliskiren in the USA for the treatment of high BP and it is currently undergoing testing in Europe. The renin inhibitor has minimal undesirable side effects, like AT1-receptor blockers. The slightly lower effectiveness ofaliskiren than AT1-receptor blockers in reducing BP is caused by the fact that it does not block bradykinins. It is recommended as a monotherapy for clinical use or in combination with other antihypertensive medicines for conditions with high levels of PRA including its rise after diuretics, ACEI and AT1-receptor blockers. Aliskiren could therefore be used primarily with young patients, Caucasians, persons with ACEI intolerance, and also in diseases where angiotensin II is involved in the pathogenesis and the secondary prevention of cardiovascular disease. It is also safe for persons with concurrent renal problems, because it is mainly removed by the liver without great interference with other materials. Like ACEI, the renin inhibitor has a vasodilatory effect which could potentially improve the elasticity of arteries. The medicine has the same limitations and contraindications as ACEI and AT1R blockers, such as pregnancy and bilateral renal artery stenosis. A definitive assessment of the benefit of this new class of medicines and its broad application in the treatment of cardiovascular and other diseases will require demonstration of its long-term effect on morbidity and mortality, as well as comparison with other RAAS blockers in long clinical studies, which represent research programmes lasting another 7 to 8 years.

[Nitric oxide synthase, typical flavohemoproteins and their complicated enzymology]. / Syntázy oxidu dusnatého, typické hemoflavoproteiny a jejich komplikovaná enzymologie.

Nitric oxide is a diatomic gaseous molecule with unpaired electron in the molecule. Physical properties such as solubility, diffusibility and half-life decide the chemical reactivity of nitric oxide. Nitric oxide is the unstable free radical in vessels, immune system and central nervous system. The reactivity of nitric oxide under physiological and pathological conditions depends upon its concentration and site of production. Nitric oxide is thought to play a role in many pathological situations: septic shock, cardiovascular diseases, arthritis, diabetes, multiple sclerosis, asthma, and hypertension. Nitric oxide synthase is a self-sufficient flavohemoprotein capable of producing nitric oxide from L-arginine by two successive monooxygenation steps. Although the N-terminal heme domain functionally resembles cytochromes P450, no structural similarities exist between cytochrome P450 and nitric oxide synthases heme domains. The C-terminal domain of nitric oxide synthases containing flavin adenine dinucleotide and flavin mononucleotide as cofactors exhibits a high degree of sequence similarity with NADPH-cytocrome P450 reductase. The reductase domains serve as an intermediary for the transfer of electrons from NADPH for the catalytic reaction. The connecting domain between the oxygenase and the reductase domains of nitric oxide synthase isoforms binds calmodulin in the presence of calcium. The binding of calmodulin to all nitric oxide synthase isoforms is obligatory for the production of nitric oxide. At the same time, the presence of one or more phosphorylation sites in nitric oxide synthase puts them among the kinase-mediated signaling pathways. This also means that nitric oxide synthases are regulated indirectly by the events that regulate kinases. This field of research of nitric oxide synthase regulation has become one of the most actively pursued and much has been learned from basic biochemical mechanisms to physiological processes and to medical applications, but many more questions still remain to be answered.

[Recommendations for the treatment of tobacco dependence]. / Doporucení pro lécbu závislosti na tabáku.

This first Czech version of guidelines formulated by the working group of mentioned medical associations is based on current literature and international guidelines. They are aimed mainly on clinical medicine and on incorporation of this treatment into the health care system according to WHO recommendations. They should serve to the treatment of tobacco dependence at any level: during any contact with the smoking patient (short intervention), in specialised centres or for the health care providers or health system itself.

[Is mild essential hypertension without obvious organ complications and risk factors associated with increased levels of circulating markers of endothelial dysfunction? Effect of ACE inhibitor therapy]. / Je mírná esenciální hypertenze bez zrejmých orgánových komplikací a rizikových faktoru provázena zvýsenými hladinami cirkulujících markeru endoteliální dysfunkce? Vliv lécby ACE-inhibitory.

The objective of the investigation was to assess whether circulating adhesion molecules, von Willebrand factor (vWf) and endothelin-1 are elevated in patients with mild uncomplicated essential hypertension without further risk factors of atherosclerosis and whether they could serve as indicators of endothelial dysfunction in this form of hypertension. Furthermore the authors investigated the effect of ACE inhibitor treatment (ACEI), quinapril, on the level of these markers of endothelial dysfunction. The level of adhesion molecules [intercellular cytoadhesion molecule-1 (ICAM-1), E-selectin, P-selectin], von Willebrand s factor (vWf) and endothelin-1 were assessed in patients with mild essential hypertension without further cardiovascular risk factors or clinical manifestations of atherosclerosis before and after quinapril treatment (n = 25) and compared with normotensive controls (n = 29). The results of the examinations provided evidence that contrary to controls the hypertensive subjects had significantly higher ICAM-1 levels (237.8 vs. 207.8 ng/ml, P = 0.02) vWf (118 vs. 106 IU/dl, p < 0.05) and endothelin-1 (5.81 vs. 5.15 fmol/ml, p < 0.05). Three-month treatment of hypertensive patients with ACEI led to a significant drop of endothelin-1 levels (5.81 vs. 5.26 fmol/ml, p = 0.01). The authors proved also an unequivocal declining trend of other cytoadhesion molecules and vWf after ACEI treatment, the changes however were not statistically significant. From the investigation it may be concluded that also patients with uncomplicated essential hypertension without other cardiovascular risk factors or clinical manifestations of atherosclerosis have significantly elevated plasma levels of ICAM-1, vWf and endothelin-1. Higher concentrations of these factors suggest endothelial dysfunction already in mild forms of essential hypertension without further risk factors or cardiovascular complications. A significant drop of endothelin-1 and declining trend of the other investigated indicators suggest that ACEI treatment can favourably influence endothelial dysfunction in hypertensive patients also independently on reduction of the BP.

Association analysis of Arg16Gly polymorphism of the beta2-adrenergic receptor gene in offspring from hypertensive and normotensive families.

OBJECTIVE: Since beta2-adrenergic receptors (beta2AR) 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 beta2AR 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 beta2AR 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 beta2AR gene is implicated in predisposition to essential hypertension. However, the contradictory results between individual studies indicate that the action of the beta2AR gene is indirect, through multiple intermediate phenotypes and gene interactions.

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 Willebrand 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.

[The beginnings of electrocardiography at the Prague Medical School]. / Pocátky elektrokardiografie na prazské lékarské fakulte.

The authors describe the beginnings of development of electrocardiography at the Prague Medical Faculty of Charles-Ferdinand and Charles University resp. The first results of the new method came from the physiological laboratory of Ewald Karl Konstantin Hering (1834-1918), who contributed to electrocardiography by explaining the mechanism of atrial fibrillation and to Richard Hans Kahn (1876-1941) who was the first to publish electrocardiographic changes after temporary block of coronary artery blood flow in the dog. Clinical application and the promotion of electrocardiography in this country is among others in particular from Václav Libenský (1877-1938), Klement Weber (1890-1971) and Frantisek Herles (1900-1991) whose name became for half a century the synonym for electrocardiography.

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.

Association of the Glu298Asp polymorphism in the endothelial nitric oxide synthase gene with essential hypertension resistant to conventional therapy.

Endothelial nitric oxide synthase (eNOS) produces nitric oxide (NO) which, after diffusing into vascular smooth muscle cells, activates guanylate cyclase leading to vasodilatation. A polymorphism (894G to T) in exon 7 of the eNOS gene causes the conversion of Glu to Asp in position 298. The recently described crystal structure of the heme domain of eNOS protein shows that Glu298 is fully solvent accessible and distant from regions integral to enzyme function. Searching for phenotypic expression of eNOS gene variants, we genotyped a group of patients with essential hypertension (H, n = 119) for the Glu298Asp polymorphism and compared them with age- and sex-matched healthy normals (N, n = 85). To specify phenotypic expression further, the hypertensive patients were subdivided into one group that responded well to regular antihypertensive therapy (CH, n = 45) and one group that was resistant to the therapy (RH, n = 74). Patients with BP higher than 140/90 mmHg when on adequate lifestyle modification and triple-combination therapy (including diuretics) were considered resistant. In RH and H groups, a significantly higher frequency of T alleles (P = 0.022 and P = 0.046, respectively) was found compared to normotonics (N). In well-controlled hypertonics, the same tendency was found, but did not reach statistical significance. The Glu298Asp polymorphism may contribute to the complex pathogenesis of essential hypertension and may be a factor in the resistance of these patients to conventional antihypertensive therapy. The presence of this allele may thus be predictive of the patients' therapeutic response.

Y-chromosome transfer induces changes in blood pressure and blood lipids in SHR.

Previous studies with chromosome-Y consomic strains of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats suggest that a quantitative trait locus for blood pressure regulation exists on chromosome Y. To test this hypothesis in the SHR-Brown Norway (BN) model and to study the effects of chromosome Y on lipid and carbohydrate metabolism, we produced a new consomic strain of SHR carrying the Y chromosome transferred from the BN rat. We found that replacing the SHR Y chromosome with the BN Y chromosome resulted in significant decreases in systolic and diastolic blood pressures in the SHR.BN-Y consomic strain (P<0.05). To elicit possible dietary-induced variation in lipid and glucose metabolism between the SHR progenitor and chromosome-Y consomic strains, we fed rats a high-fructose diet for 15 days in addition to the normal diet. On the high-fructose diet, the SHR.BN-Y consomic rats exhibited significantly increased levels of serum triglycerides and decreased levels of serum HDL cholesterol versus the SHR progenitor rats. Glucose tolerance and insulin/glucose ratios, however, were similar in both strains on both normal and high-fructose diets. These findings provide direct evidence that a gene or genes on chromosome Y contribute to the pathogenesis of spontaneous hypertension in the SHR-BN model. These results also indicate that transfer of the Y chromosome from the BN rat onto the SHR background exacerbates dietary-induced dyslipidemia in SHR. Thus, genetic variation in genes on the Y chromosome may contribute to variation in blood pressure and lipid levels and may influence the risk for cardiovascular disease.