Effects of PCSK9 variants on common carotid artery intima media thickness and relation to ApoE alleles.

BACKGROUND: PCSK9 plays a key role in plasma cholesterol metabolism by modulating the expression of LDL receptors. OBJECTIVE AND METHODS: In this study we investigated the effects of two common polymorphism of the PCSK9 gene (E670G and I474V) on the intima media thickness of the common carotid artery and the possible relation with polymorphisms of apolipoprotein E in 1541 middle aged subjects selected from the general population enrolled in the PLIC study and confirmed the major findings in a second free-living population enrolled in the Ventimiglia study. RESULTS: 670G carriers showed significantly increased plasma total cholesterol, LDL-cholesterol, and Apo levels B while no significant differences were observed between carriers of the I474V SNP. IMT was significantly increased in 670G carriers compared to individuals homozygous for the E allele (0.640+/-0.102mm vs. 0.652+/-0.092mm, P<0.05). The presence of the 670G allele was also significantly associated with a greater progression of IMT compared to 670EE subjects. Plasma total cholesterol, LDL-cholesterol, apolipoprotein B, and IMT significantly increased from ApoE2;PCSK9-670EE carriers to ApoE4-PCSK9-670G carriers, while no significant differences were observed when the presence of the ApoE alleles was combined with that of the PCSK9 I474V SNP. In silico analysis on wild type and 670G variant showed several structural differences on the interactions of the loops of the "V" domain. CONCLUSIONS: The E670G polymorphism of the PCSK9 gene is associated with increased IMT progression in the general population. When the presence of 670G allele is stratified according to the ApoE gene alleles, ApoE2;PCSK9-670EE carriers show a more favorable plasma lipid profile and decreased IMT compared to ApoE4-PCSK9-670G carriers.

Behaviour of regional adrenergic outflow in mild-to-moderate renal failure.

OBJECTIVES: Chronic renal failure is characterized by a marked sympathetic activation. No information exists, however, as to whether the adrenergic overdrive is confined to selected vascular districts or is rather generalized to the whole cardiovascular system. METHODS: In 15 patients aged 60.5 +/- 2.0 years (mean +/- SEM) with stable chronic renal failure belonging to stage 2-3 of the Kidney Foundation classification and in 12 age-matched healthy controls, we measured arterial blood pressure (Finapres), heart rate (ECG), venous plasma norepinephrine (high-performance liquid chromatography) and postganglionic sympathetic nerve traffic in skeletal muscle and skin areas (microneurography). Muscle and skin nerve traffic measurements were made in a randomized sequence over two periods of 30 min each, spaced by a 20-30-min interval. Measurements also included evaluation of skin sympathetic responses to emotional stimuli. RESULTS: Muscle sympathetic nerve traffic was markedly and significantly greater in renal failure patients compared with controls (58.2 +/- 3.6 vs. 36.8 +/- 5.7 bursts/100 heart beats, P < 0.01), with this also being the case for plasma norepinephrine (380.6 +/- 63 vs. 210.8 +/- 29 pg/ml, P < 0.05). By contrast, skin sympathetic nerve traffic was superimposable in the two groups (11.5 +/- 0.8 vs. 12.7 +/- 1.7 bursts/minute, P = not significant), this being the case also for the responses to emotional arousal. CONCLUSION: These data provide the first evidence that the sympathetic activation characterizing renal failure is not generalized to the entire cardiovascular system. This may depend on the fact that the two sympathetic districts are governed by mechanisms that are differently affected by the chronic uraemic state.

Circulating soluble receptor for advanced glycation end products is inversely associated with body mass index and waist/hip ratio in the general population.

Advanced glycation end products, AGEs, and its specific receptor, RAGE, are involved in vascular complications. A role for the soluble form of RAGE (sRAGE), which acts as a decoy for AGE, has been documented in patients with diabetes but no information is available in non-diabetic subjects. The aim of this study was to investigate the association of plasma levels of sRAGE with cardiometabolic risk factors in the general population. In addition we evaluated the relation of the common -374A/T polymorphism of RAGE with plasma levels of sRAGE. One hundred and seventy-six healthy subjects free of diabetes or coronary artery disease untreated for hypertension, dyslipidemia or cardiometabolic related diseases were randomly selected for this study from the general population. Plasma sRAGE were negatively and significantly correlated with BMI, waist/hip circumference ratio and fasting glycemia, while a positive correlation was observed with apolipoprotein A-I. These correlations were observed mainly in women who showed significantly higher sRAGE levels (1744+/-660 pg/mL vs 1414+/-649 pg/mL; P<0.05). In a stepwise regression analysis waist circumference was independently associated with sRAGE and, when waist circumference was excluded, BMI was independently associated with sRAGE. Finally in overweight subjects (BMI>25 kg/m(2)) plasma sRAGE was significantly lower compared to lean subjects (1460+/-640 pg/mL vs 1710+/-693 pg/mL; P<0.05). In healthy subjects plasma levels of sRAGE were negatively correlated with BMI and waist/hip ratio supporting a possible protective role for these proteins before any evidence of diabetic or vascular complications.

Current structure and organization for renal patient assistance in Italy.

BACKGROUND: Given the public health challenge and burden of chronic kidney disease, the Italian Society of Nephrology (SIN) has compiled a national census of Renal Units (RU) existing in the twenty Italian regions related to the year 2004. METHODS: An on-line questionnaire including 158 items explored structural and human resources, organization aspects, activities and epidemiological data in SIN, 2004. RESULTS: The census identified 363 public RU, 303 satellite Dialysis Centres (DC) and 295 private DC totalling 961 DC [16.4 per million population (pmp)]. The inpatient renal beds were 2742 (47 pmp). Renal and dialysis activity was performed by 3728 physicians (64 pmp), of whom 2964 (80%) were nephrologists. There was no permanent medical assistance in 41% of satellite DC. There were 1802 renal admissions pmp and 99 renal biopsies pmp. The management of acute renal failure (13 456 cases; 230 pmp) represented a relevant proportion of the activities conducted in public RU. In 2004 there were 9858 new cases of end-stage kidney disease requiring renal replacement therapy (RRT) (169 pmp). On 31 December 2004, 60 058 patients were on RRT (1027 pmp), 43 293 of which (740 pmp) were on dialysis and 16 765 (287 pmp) with renal graft. CONCLUSIONS: This census of the Italian RU and DC in 2004 provides decision makers and healthcare stakeholders with detailed data for benchmarking and has financial implications for the public health system. Similar analyses may be conducted in other countries permitting standardization of medical and cost-related aspects of renal care.

Improvement of endothelial function in uraemic patients on peritoneal dialysis: a possible role for 5-MTHF administration.

BACKGROUND: Hyperhomocysteinaemia is an independent risk factor for the development of atherosclerosis. Furthermore, homocysteine induces endothelial dysfunction by an increased inactivation of nitric oxide. In patients with chronic renal failure, the administration of folic acid or its metabolites reduces but does not normalize plasma homocysteine concentrations. METHODS: We examined the effect of oral treatment with 15 mg/daily of 5-methyltetrahydrofolate (5-MTHF) for 12 weeks, on homocysteinaemia and endothelial function in 19 patients undergoing peritoneal dialysis and compared them, for the same period of time, to a control group of patients on peritoneal dialysis. Endothelial function was evaluated by B-mode ultrasonography on the brachial artery. Flow-mediated dilation (FMD) was recorded during reactive hyperaemia produced by the inflation of a pneumatic tourniquet. Nitroglycerine-mediated dilation (NMD) was recorded after sublingual administration of glyceryl trinitrate. Finally, oxidative stress was assessed by evaluating the conjugated dienes plasma levels. RESULTS: Plasma homocysteine concentrations fell by 30% after oral treatment with 5-MTHF. Endothelial function improved significantly after oral 5-MTHF treatment (13.8 +/- 1.2% vs 11.4 +/- 1.4%; P < 0.02) while in the control group we observed a worsening of basal values from 12.1 +/- 2.66% to 8.7 +/- 2.90% (P < 0.02). The conjugated dienes plasma levels did not change either. CONCLUSIONS: Our study demonstrated that 5-MTHF administration improves endothelial dysfunction in patients undergoing peritoneal dialysis. This effect appears to be independent of the reduction in homocysteine plasma levels.

Prevalence of atrial fibrillation and associated factors in a population of long-term hemodialysis patients.

BACKGROUND: Hemodialysis (HD) is associated with cardiovascular structural modifications; moreover, during HD, rapid electrolytic changes occur. Both factors may favor the onset of atrial fibrillation. METHODS: To define the prevalence of atrial fibrillation and identify associated factors, 488 patients on long-term HD therapy (age, 66.6 +/- 13.4 years; men, 58.0%; duration of HD, 76.5 +/- 84.3 months) were studied. RESULTS: Atrial fibrillation was reported in 27.0% of patients; paroxysmal in 3.5%, persistent in 9.6%, and permanent in 13.9%. Clinical and echocardiographic variables were considered: patients with atrial fibrillation were older (71.8 +/- 9.3 versus 64.7 +/- 14.2 years; P < 0.01), and its prevalence increased with age. Patients with arrhythmia had a longer duration of dialysis therapy (93.2 +/- 100.5 versus 70.2 +/- 76.7 months; P = 0.02). Atrial fibrillation was associated significantly with ischemic heart disease (P < 0.01), dilated cardiomyopathy (P < 0.01), acute pulmonary edema (P < 0.05), valvular disease (P < 0.05), cerebrovascular accidents (P < 0.05), and predialytic hyperkalemia (P < 0.05). Patients with atrial fibrillation more frequently showed left atrial dilatation (59.8% versus 34.5%; P < 0.0001), and in these subjects, left ventricular ejection fraction was significantly lower (53.9% versus 57.4%; P = 0.029). No association was found between arrhythmia and hypertension or diabetes. Multivariate analysis confirmed that patient age (P < 0.001), duration of HD therapy (P = 0.001), and left atrial dilatation (P < 0.001) were associated with atrial fibrillation. CONCLUSION: Atrial fibrillation is much more frequent in HD patients than in the general population; age, duration of HD history, presence of some heart diseases, and left atrial dilatation are associated with the arrhythmia.

Erythrocyte ferritin concentration: analytical performance of the immunoenzymatic IMx-Ferritin (Abbott) assay.

Together with serum ferritin, erythrocyte ferritincan be a valuable diagnostic tool for evaluating the degree of impaired iron metabolism in different diseases. We collected peripheral blood samples from 64 subjects (22 healthy volunteers, 20 patients with hereditary hemochromatosis, and 22 patients on regular hemodialysis with secondary anemia) to evaluate whether an immunoenzymatic method generally used for serum ferritin can also be used to determine erythrocyte ferritin levels under various conditions of body iron status. Serum and erythrocyte ferritin levels were assayed in parallel using a microparticle enzyme immunoassay (MEIA) IMx-Ferritin kit and an IMx analyzer. The inter-assay imprecision of the serum and erythrocyte ferritin assays was 4.9% and 5.05%, the intra-assay imprecision was 2.2% and 2.3%, and the mean recovery was 102% (range 96-105%) and 101% (range 99-105%), respectively. Both serum and erythrocyte ferritin assays showed a detection limit of 1 microg/L and good linearity (R(2) = 0.99) in the intervals 13.9-443 and 3.9-135.6 microg/L, respectively. Our findings demonstrate that the IMx-Ferritin assay currently used to measure serum ferritin levels can also be adopted to measure erythrocyte ferritin insofar as it clearly discriminates high and low erythrocyte ferritin levels in cases of both iron overload and deficiency.

Plasma homocysteine levels and cardiovascular mortality in patients with end-stage renal disease.

Hyperhomocysteinemia is considered an independent risk factor for atherosclerosis in patients with normal renal function. Plasma homocysteine (Hcy) is increased in patients with chronic renal failure (CRF) and could be linked to their high cardiovascular (CV) morbidity and mortality. We prospectively studied 77 patients (47 males and 30 females aged 62.85 +/- 1.53 yrs) who had been on maintenance hemodialysis (HD) (4 hr/x3/week) for 65.5 +/- 7.23 months. Patients were followed-up for 44 months. At baseline, blood samples were taken for hemoglobin (Hb), total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, serum calcium, serum phosphates, parathyroid hormone (PTH), Hcy, vitamin B12, serum and erythrocyte folate and methylentetrahydrofolate-reductase (t-MTH-FR) genotype determination. Plasma Hcy levels of patients were divided into four quartiles. The univariate analysis demonstrated a significant relationship between Hcy and diastolic blood pressure (BP) (r=0.45; p=0.003), and both plasma (r=-0.30; p=0.03) and erythrocyte (r=-0.48; p=0.01) folate levels and CV score (r=0.39; p=0.007). Kaplan-Meier analysis showed that the mortality rate due to CV events was statistically significantly higher in the 4th Hcy quartile (68%; 12 patients) vs. the 3rd quartile (12%; two patients), the 2nd quartile (28%; four patients) and the 1st quartile (14%; two patients) (log-rank test p=0.02). Cox's regression analysis for CV survival showed that Hcy was a positive CV mortality predictor (beta=0.02; hazard ratio=1.031; 95% confidence interval (95% CI): 1.013-1.050; p=0.001), while LDL cholesterol and albumin related negatively to CV mortality (LDL cholesterol: beta=-0.02; hazard ratio=0.095; 95% CI: 0.0957-0.0997; p=0.035; albumin: beta=-2.35; hazard ratio=0.097; 95% CI: 0.011-0.847; p=0.026). Our results show that Hcy is a strong independent mortality predictor in HD patients with a 3% increase in mortality for each 1 micromol/L increase in plasma Hcy concentration. This agrees with previous findings confirming the role of Hcy in predicting CV risk factors in uremic patients.

Cancers of the kidney and urinary tract in patients on dialysis for end-stage renal disease: analysis of data from the United States, Europe, and Australia and New Zealand.

Patients on maintenance dialysis have increased risk for cancer, especially in the kidney and urinary tract. In a retrospective cohort of 831,804 patients starting dialysis during 1980 to 1994 in the United States, Europe, or Australia and New Zealand, standardized incidence ratios (SIR) with 95% confidence intervals (CI) were calculated for kidney and bladder cancers. Risks for cancers of the kidney (SIR 3.6; CI 3.5 to 3.8) and bladder (SIR 1.5; CI 1.4 to 1.6) were increased, relatively more in younger than older patients and more in female patients (kidney: SIR 4.6, CI 4.3 to 4.9; bladder: SIR 2.7, CI 2.4 to 2.9) than male patients (kidney: SIR 3.2, CI 3.0 to 3.4; bladder: SIR 1.3, CI 1.2 to 1.3). SIR for kidney cancer were raised in all categories of primary renal disease, and for bladder cancer in all but diabetes and familial, hereditary diseases. Notably high SIR occurred in toxic nephropathies (chiefly analgesic nephropathy) and miscellaneous conditions (a category that includes Balkan nephropathy), the excess of kidney cancer in these conditions being urothelial in origin. SIR for kidney cancer rose significantly, and those for bladder cancer fell (not reaching significance) with time on dialysis. There was no association with type of dialysis. The pattern of increased risk for renal parenchymal cancer in dialysis patients is consistent with causation through acquired renal cystic disease and of urothelial cancers of the kidney and bladder with the carcinogenic effects of certain primary renal diseases.

5-methyltetrahydrofolate restores endothelial function in uraemic patients on convective haemodialysis.

BACKGROUND: Hyperhomocysteinaemia is an independent risk factor for the development of atherosclerosis. In patients with chronic renal failure, the administration of folic acid or its metabolites reduces but does not normalize plasma homocysteine concentrations. Furthermore, homocysteine induces endothelial dysfunction by an increased inactivation of nitric oxide. METHODS: We examined the effect of the active metabolite of folic acid, 5-methyltetrahydrofolate (5-MTHF), 45 mg/week i.v. for 10 weeks, combined during the last 2 weeks with vitamin B12, 500 microg s.c. twice weekly, on homocysteinaemia and endothelial function in 15 patients undergoing convective haemodialysis. Endothelial function was evaluated by B-mode ultrasonography on the brachial artery. Flow-mediated dilation (FMD) was recorded during reactive hyperaemia produced by inflation of a pneumatic tourniquet. Nitroglycerine-mediated dilation (NMD) was recorded after administration of isosorbide dinitrate. Finally, the presence of the thermolabile variant of methyltetrahydrofolate reductase (t-MTHFR) was assessed by genotype analysis. RESULTS: Plasma homocysteine concentrations fell by 47% after treatment with 5-MTHF alone and by a further 13.6% after the addition of vitamin B12. The reduction was more marked in homo- and heterozygous patients than in normal genotypes for t-MTHFR. Flow-mediated endothelial vasodilation, measured by ultrasonography of the brachial artery, improved after administration of 5-MTHF (12.52+/- 2.47% vs. 7.03+/-1.65%; P<0.05), but there were no further changes following the addition of vitamin B12. CONCLUSIONS: Our study demonstrated that 5-MTHF administration not only reduced plasma homocysteine but also improved endothelial function in uraemic patients undergoing convective haemodialysis.