Association between ENOS gene polymorphism and cardiovascular events in nondiabetic hemodialysis patients: a prospective study.

BACKGROUND: Synthesis of nitric oxide by endothelial nitric oxide synthase (ENOS) plays a key role in the atherosclerotic process. Several polymorphisms of the gene encoding ENOS are now known and have been investigated with respect to their influence on cardiovascular disease risk in the general population. The authors prospectively investigated whether ENOS gene polymorphisms determined the risk of cardiovascular complications in a cohort of hemodialysis patients. METHODS: A total of 335 nondiabetic hemodialysis patients were genotyped for 3 ENOS polymorphisms (T-786-->C, intron 4, and Glu298Asp polymorphism) and were followed up prospectively for a mean of 44.2 +/- 9.0 months. The end-points of the study were major cardiac, cerebrovascular, or peripheral vascular events. RESULTS: Two ENOS polymorphisms were associated with cardiovascular events: a T to C substitution at position -786 of the promoter and a deletion-insertion in intron 4 (the a allele having 4 repeats of a consensus sequence and the b allele having 5 repeats). A total of 84 subjects were -786C carriers (CC+TC), and 15 (18%) suffered from cardiovascular events compared with only 13 of 251 TT patients (5%). The relative risk of cardiovascular events was higher for -786C carriers compared with noncarriers (relative risk: 2.05, P = 0.0003). It was also higher for a allele carriers (intron 4 polymorphism) compared with noncarriers (relative risk: 1.97, P = 0.0005). CONCLUSION: T-786-->C polymorphism and intron 4 polymorphism, but not Glu298Asp polymorphism, of the ENOS gene can influence the risk of cardiovascular events in Japanese nondiabetic hemodialysis patients.

Different risk factors for the maximum and the mean carotid intima-media thickness in hemodialysis patients.

OBJECTIVE: High-resolution B-mode ultrasonography has been widely used for the noninvasive assessment of atherosclerosis in hemodialysis patients. But, there are two major methods of carotid ultrasonography: one including plaque and the other excluding plaque. METHODS: The subjects were 112 hemodialysis patients (58 men and 54 women) with a mean age of 55.8 +/- 13.0 years. The maximum intima-media thickness (IMT) of the carotid artery (including plaque) was measured as an index of arterial wall thickening and atheroma formation, while the mean IMT (without plaque) was measured as an index of arterial wall thickening. In addition the value of (maximum-mean) IMT was calculated as an index of atheroma formation. Therefore, the independent risk factors associated with the maximum IMT, mean IMT, and (maximum-mean) IMT were investigated by stepwise multiple regression analysis. RESULTS: The independent risk factors associated with the maximum IMT were age, diabetes mellitus, smoking, and intact parathyroid hormone (PTH) (R = 0.569, p < 0.0001), while factors associated with the mean IMT were age, hypertension, dyslipidemia, intact PTH, and lipoprotein (a) (R = 0.602, p < 0.0001). The independent risk factors associated with the (maximum-mean) IMT were age, diabetes mellitus, smoking, and intact PTH (R = 0.515, p < 0.0001). CONCLUSION: These findings suggest that risk factors for the maximum IMT and mean IMT are somewhat different in hemodialysis patients.

Bone mineral density may be related to atherosclerosis in hemodialysis patients.

Biological interactions between the bone and the blood vessels are gradually being clarified. To investigate the relationship between bone mineral density and atherosclerosis in hemodialysis patients, we examined the bone mineral density and the intima-media thickness of the carotid artery in 83 dialysis patients with non-diabetic nephropathy (44 men and 39 women) aged from 23 to 83 years. The duration of hemodialysis ranged from 2 to 344 months. The bone mineral density of the radius was measured by dual-energy X-ray adsorptiometry, and the ratio of this value to the standard value for the same age and gender was calculated ( Z-score). As an index of atherosclerosis, the intima-media thickness of the carotid artery was measured by high resolution B-mode ultrasonography. Then the relationship between the Z-score and various factors was examined using Spearman's rank correlation analysis and multiple regression analysis. The Z-score showed a negative correlation with the duration of hemodialysis, the carotid intima-media thickness, and the levels of alkaline phosphatase, intact parathyroid hormone, and low-density lipoprotein cholesterol by Spearman's rank correlation analysis. In addition, the Z-score showed a positive correlation with the lipoprotein (a) level and a negative correlation with the duration of hemodialysis, intima-media thickness, intact parathyroid hormone, and low-density lipoprotein cholesterol by multiple regression analysis. These findings suggest that the decrease of bone mineral density in hemodialysis patients is correlated with secondary hyperparathyroidism and hyperlipidemia, which are factors known to promote atherosclerosis, and thus bone density changes might be related to the progression of atherosclerosis, or vice versa.

Effect of polymorphism of the endothelial nitric oxide synthase and apolipoprotein E genes on carotid atherosclerosis in hemodialysis patients.

BACKGROUND: Decreased synthesis of nitric oxide (NO) and dyslipidemia are implicated in the development of atherosclerosis. METHODS: We investigated the relationship between endothelial NO synthase (eNOS) gene polymorphism, apolipoprotein E (apoE) polymorphism, and carotid atherosclerosis in 163 hemodialysis patients with nondiabetic nephropathy. Intima media thickness of the carotid artery was measured by ultrasonography, and subjects were classified according to the presence or absence of carotid plaque. Multivariate odds ratios were calculated to assess the combined influence of several variables on the existence of carotid plaque, with clinical factors, the intron 4 polymorphism, T(-786)-->C polymorphism, and Glu298Asp polymorphism of eNOS and the apoE polymorphism tested as independent predictors. We also investigated the combined effect of these polymorphisms on risk for plaque. RESULTS: The odds ratio for carotid plaque positivity was increased to 3.72 by the a allele of the intron 4 polymorphism and increased to 3.36 by the C allele of the T(-786)-->C polymorphism, but was not increased in subjects with the T allele of the Glu298Asp polymorphism or those with the epsilon4 allele of the apoE polymorphism. However, the odds ratio for plaque positivity was significantly increased to 4.00 by possession of the a allele and/or epsilon4 allele and also increased to 4.04 by the C allele and/or epsilon4 allele. CONCLUSION: This cross-sectional study showed a synergistic effect between the intron 4 polymorphism or T(-786)-->C polymorphism of the eNOS gene and the apoE polymorphism with respect to risk for carotid atherosclerosis in nondiabetic hemodialysis patients.

Effect of glucose polymer on the intercellular junctions of cultured human peritoneal mesothelial cells.

BACKGROUND: Glucose polymer is an active osmotic agent that is increasingly used as an alternative to glucose in peritoneal dialysis fluids. It was recently reported that the duration of peritoneal dialysis can be extended by using glucose polymer in patients with poor ultrafiltration. We previously demonstrated that high glucose levels damage the intercellular junctions of cultured human peritoneal mesothelial cells (HPMC), but little is known about the influence of glucose polymer. Therefore, we investigated the effects of glucose polymer on the intercellular junctions of HPMC. METHODS: HPMC were isolated, cultured, and identified according to the modified method of Stylianou. M199 medium was supplemented with peritoneal dialysis solutions containing 7.5% glucose polymer or 1.5, 2.5, and 4.25% glucose. After 6 h, cell viability was assessed, intercellular junction proteins were examined by immunofluorescence techniques, and the concentration of transforming growth factor-beta1 in the culture supernatant was determined. RESULTS: Glucose significantly suppressed cell viability and significantly increased transforming growth factor-beta1 production when compared with control or glucose polymer cultures. Peritoneal dialysis solutions containing 4.25% glucose caused the detachment of HPMC. Immunofluorescence of intercellular junction proteins (tight junctions: ZO-1, occludin, and claudin-1; adherens junctions: beta-catenin) became weak and uneven after culture with glucose. On the other hand, glucose polymer caused little change in the immunofluorescence of these proteins when compared with control cultures. CONCLUSIONS: Glucose polymer seems to be less toxic to HPMC than glucose itself, suggesting that the glucose polymer may be better for peritoneal dialysis.

T(-786)-->C polymorphism of the endothelial nitric oxide synthase gene influences the progression of renal disease.

BACKGROUND/AIMS: Polymorphism of the endothelial nitric oxide synthase (ecNOS) gene may be involved in renal disease. Recently, T(-786)-->C polymorphism affecting ecNOS gene transcription has been reported. To clarify the role of T(-786)-->C polymorphism in renal disease, we investigated hemodialysis patients and healthy controls for this polymorphism and we compared its frequency with that of intron 4 polymorphism in the hemodialysis patients. METHODS: The subjects were 252 patients who had been on hemodialysis for less than 2 years (168 with nondiabetic nephropathy and 84 with diabetic nephropathy) and 187 healthy controls. T(-786)-->C polymorphism was detected using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: The frequencies of the T/C and C/C genotypes were significantly higher in the nondiabetic hemodialysis patients than in the controls (odds ratio 1.41; 95% Cl 1.03-2.00), and were also significantly higher in the diabetic hemodialysis patients than in the controls (odds ratio 1.56; 95% Cl 1.02-2.41). In addition, T(-786)-->C polymorphism and intron 4 polymorphism showed strong linkage disequilibrium. CONCLUSION: T(-786)-->C polymorphism may be involved in the progression of both nondiabetic and diabetic nephropathy, along with intron 4 polymorphism.