Marie Jáchymová

Genetics of Cd36 and the clustering of multiple cardiovascular risk factors in spontaneous hypertension

Disorders of carbohydrate and lipid metabolism have been reported to cluster in patients with essential hypertension and in spontaneously hypertensive rats (SHRs). A deletion in the Cd36 gene on chromosome 4 has recently been implicated in defective carbohydrate and lipid metabolism in isolated adipocytes from SHRs. However, the role of Cd36 and chromosome 4 in the control of blood pressure and systemic cardiovascular risk factors in SHRs is unknown. In the SHR. BN-Il6/Npy congenic strain, we have found that transfer of a segment of chromosome 4 (including Cd36) from the Brown Norway (BN) rat onto the SHR background induces reductions in blood pressure and ameliorates dietary-induced glucose intolerance, hyperinsulinemia, and hypertriglyceridemia. These results demonstrate that a single chromosome region can influence a broad spectrum of cardiovascular risk factors involved in the hypertension metabolic syndrome. However, analysis of Cd36 genotypes in the SHR and stroke-prone SHR strains indicates that the deletion variant of Cd36 was not critical to the initial selection for hypertension in the SHR model. Thus, the ability of chromosome 4 to influence multiple cardiovascular risk factors, including hypertension, may depend on linkage of Cd36 to other genes trapped within the differential segment of the SHR. BN-Il6/Npy strain.

Receptor for advanced glycation end products (RAGE)--soluble form (sRAGE) and gene polymorphisms in patients with breast cancer.

Receptor for advanced glycation end products (RAGE) may be involved in the pathogenesis of the cancer progression and metastasis. Pathological effects mediated via RAGE are physiologically inhibited by soluble RAGE (sRAGE), so the higher sRAGE levels may confer the patients with cancer with better outcome. The aim was to study sRAGE and RAGE gene polymorphisms in patients with breast cancer. The authors studied sRAGE and RAGE polymorphisms in 120 patients with breast cancer (subdivided based on the clinical stage, histologic grading, expression of hormonal and Her2/neu receptors) and in 92 healthy controls. Despite higher serum concentrations of AGEs, serum concentrations of sRAGE were lower in patients with breast cancer compared to healthy controls (1581 ± 777 versus 1803 ± 632 ng/mL, p < 0.05). Serum levels of sRAGE were higher in patients with advanced breast cancer (stage III), lower grade and positive estrogen receptors, and intermediate positivity of Her2/neu receptors and were also influenced genetically (Gly82Ser and 2184 AG polymorphisms of the RAGE gene). Decreased sRAGE levels in patients with breast cancer may contribute to the progression of the disease. Patients with better outcome (low grade and positive estrogen receptors) have higher sRAGE levels. Progression of the disease, may, however, increase sRAGE levels, possibly as a compensatory mechanism to counteract further progression.

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.

Soluble receptor for advanced glycation end-products (sRAGE) and polymorphisms of RAGE and glyoxalase I genes in patients with pancreas cancer.

OBJECTIVES The receptor for advanced glycation end-products (RAGE) takes part in the pathogenesis of many diseases, including diabetes mellitus and cancer. AGE-precursors are detoxified by glyoxalase (GLO). sRAGE, soluble RAGE, is an inhibitor of pathological effects mediated via RAGE. The aim was to study sRAGE and polymorphisms of RAGE (AGER) and GLO genes in patients with pancreas cancer (PC). DESIGN AND METHODS The studied group consisted of 51 patients with PC (34 with impaired glucose tolerance-IGT, 17 without IGT), 34 type 2 DM and 154 controls. For genetic analysis, the number of patients was increased to 170. Serum sRAGE was measured by ELISA and all polymorphisms (RAGE -429T/C, -374T/A, 2184A/G, Gly82Ser and GLO A419C) were determined by PCR-RFLP and confirmed by sequencing. RESULTS Soluble RAGE is decreased in patients with PC compared to patients with DM and controls (975+/-532 vs. 1416+/-868 vs. 1723+/-643pg/mL, p<0.001). Patients with PC and IGT have lower sRAGE levels compared to patients with PC without IGT (886+/-470 vs. 1153+/-616pg/mL, p<0.05). No relationship of sRAGE to the stage was found. We did not show any difference in allelic and genotype frequencies in all RAGE and GLO polymorphisms among the studied groups. CONCLUSION This is the first study demonstrating decreased sRAGE in patients with pancreas cancer. Its levels are even lower than in diabetics and are lowest in patients with PC and IGT. Our study supports the role of glucose metabolism disorder in cancerogenesis. Further studies are clearly warranted, especially with respect to potential preventive and therapeutic implications.

Y-Chromosome Transfer Induces Changes in Blood Pressure and Blood Lipids in SHR

Abstract—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.

A419C (E111A) Polymorphism of the Glyoxalase I Gene and Vascular Complications in Chronic Hemodialysis Patients

Advanced glycation end products (AGEs) take part in the pathogenesis of vascular, diabetic, and uremic complications. Their precursors are detoxified by the glyoxalase system. Our aim was to study A419C (E111A) single nucleotide polymorphism (SNP) of the glyoxalase I gene in hemodialysis (HD) patients. A419C SNP, several laboratory parameters including soluble receptor for AGEs (sRAGE), and clinical data were studied in 214 HD patients and 89 controls. Allelic and genotypic frequencies did not differ between HD patients and controls. A419C SNP was significantly linked with serum sRAGE, which sensitively reflects the AGE burden of the organism (3986 ± 1638 pg/mL in the CC variant versus 3277 ± 1398 pg/mL in the AC variant and 3297 ± 1445 pg/mL in the AA variant, P < 0.01). In the CC variant, significantly higher prevalence of cardiovascular disease and peripheral vascular disease was found, while the prevalence of hypertension, diabetes mellitus, and dyslipidemia did not differ between genotypes. In summary, in this study we demonstrate for the first time the association of A419C polymorphism of the glyoxalase I gene with sRAGE levels and show the genetic predisposition to vascular complications in HD patients.

The influence of polymorphism of −493G/T MTP gene promoter and metabolic syndrome on lipids, fatty acids and oxidative stress

The aim of this study was to investigate the effect of the microsomal triglyceride transfer protein (MTP) -493G/T polymorphism on clinical and biochemical parameters in relation to the presence of metabolic syndrome (MS). A group of 270 participants, 143 men and 127 women [50 men/36 women fulfilled the International Diabetes Federation (IDF) criteria of MS], was categorized on the basis of the MTP -493G/T polymorphism: GG homozygotes (Group GG) and carriers of the T allele (Group TT+TG). In men with MS, the presence of the T allele was associated with elevated concentrations of plasma insulin (by 48%, P<.01) and nonesterified fatty acids (by 49%, P<.05); homeostasis model assessment for insulin resistance index was higher by 64% (P<.05). Carriers of the T allele were further characterized by elevated plasma concentrations of total cholesterol (by 14%, P<.05) and by increased triglycerides in plasma (by 95%, P<.01) and in very low-density lipoprotein (by 106%, P<.01). They also had lower concentrations of n-6 polyunsaturated fatty acids in plasma phospholipids (by 3.5%, P<.05), lower Delta5-desaturase activities (by 18%, P<.05) and elevated concentrations of conjugated dienes in low-density lipoprotein (by 29%, P<.01). No significant differences between Groups GG and TT+TG were found in men without MS and in women with and without MS. Our results imply evidence for interactive effects of genetic, metabolic and gender-specific factors on several components of metabolic syndrome, which can increase the risk for cardiovascular disease.

Effect of carvedilol on portal hypertension depends on the degree of endothelial activation and inflammatory changes.

Objective. Bleeding from esophageal varices is a major complication of liver cirrhosis. Non-selective beta-blockers exert an influence on the functional part of portal hypertension, thereby reducing the risk of bleeding. Direct measurement of this functional part is not possible; nevertheless, pro-inflammatory markers as well as parameters of endothelial dysfunction might serve as surrogate markers. The aim of study was to assess the correlation between the therapeutic efficacy of carvedilol and markers of endothelial dysfunction and systemic inflammation in patients with liver cirrhosis and portal hypertension. Material and methods. Thirty-six patients with cirrhosis and portal hypertension were given carvedilol, 25 mg q.i.d. for 30 days. Hepatic venous pressure gradient (HVPG) and biochemical determinations were performed prior to and after the treatment. Eight healthy individuals served as controls for comparison of biochemical markers. Results. In the whole group of cirrhotic patients, HVPG decreased from 17.7±3.8 to 14.9±4.8 mmHg (p<0.001). Complete response was seen in 15 patients (42%). Baseline serum levels of E-selectin were significantly higher in responders than in non-responders (119.8±70.6 versus 52.6±25.7 ng/ml; p=0.023) and in controls (28.8±22.2 ng/ml; p=0.004). Furthermore, baseline TNF-α levels were significantly higher in responders than in non-responders (22.8±15.7 versus 7±8.9; p=0.047) and in controls (5.5±5.9 pg/ml; p=0.005). Serum levels of ICAM-1 showed the same trend (4360±2870 versus 2861±1577 versus 651±196 ng/ml), although differences did not reach statistical significance. Conclusions. Markers of systemic inflammation and endothelial dysfunction seem to predict the hypotensive effect of carvedilol on portal hypertension in patients with liver cirrhosis and may be useful in the assessment of the efficacy of the therapy.

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.