We observed that a relationship between serum ferritin levels and insulin resistance exists in women but not in men. This sexual dimorphism merits further investigation.

The feasibility of large-scale genome-wide association studies of complex human disorders depends on the availability of accurate and efficient genotyping methods for single nucleotide polymorphisms (SNPs). We describe a new platform of the invader assay, a biplex assay, where both alleles are interrogated in a single reaction tube. The assay was evaluated on over 50 different SNPs, with over 20 SNPs genotyped in study cohorts of over 1500 individuals. We assessed the usefulness of the new platform in high-throughput genotyping and compared its accuracy to genotyping results obtained by the traditional monoplex invader assay, TaqMan genotyping and sequencing data. We present representative data for two SNPs in different genes (CD36 and protein tyrosine phosphatase 1beta) from a study cohort comprising over 1500 individuals with high or low-normal blood pressure. In this high-throughput application, the biplex invader assay is very accurate, with an error rate of <0.3% and a failure rate of 1.64%. The set-up of the assay is highly automated, facilitating the processing of large numbers of samples simultaneously. We present new analysis tools for the assignment of genotypes that further improve genotyping success. The biplex invader assay with its automated set-up and analysis offers a new efficient high-throughput genotyping platform that is suitable for association studies in large study cohorts.

The increased inhomogenity in atrial electrophysiological properties during atrial dilatation contributed to the inducibility of AF.

Vascular smooth muscle cell (SMC) proliferation plays an important role in the pathogenesis of atherosclerosis and post-angioplasty restenosis. Berberine is a well-known component of the Chinese herb medicine Huanglian (Coptis chinensis), and is capable of inhibiting SMC contraction and proliferation, yet the exact mechanism is unknown. We therefore investigated the effect of berberine on SMC growth after mechanic injury in vitro. DNA synthesis and cell proliferation assay were performed to show that berberine inhibited serum-stimulated rat aortic SMC growth in a concentration-dependent manner. Mechanical injury with sterile pipette tip stimulated the regrowth of SMCs. Treatment with berberine prevented the regrowth and migration of SMCs into the denuded trauma zone. Western blot analysis showed that activation of the MEK1/2 (mitogen-activated protein kinase kinase 1/2), extracellular signal-regulated kinase (ERK), and up-regulation of early growth response gene (Egr-1), c-Fos and Cyclin D1 were observed sequentially after mechanic injury in vitro. Semi-quantitative reverse-transcription PCR assay further confirmed the increase of Egr-1, cFos, platelet-derived growth factor (PDGF) and Cyclin D1 expression in a transcriptional level. However, berberine significantly attenuated MEK/ERK activation and downstream target (Egr-1, cFos, Cyclin D1 and PDGF-A) expression after mechanic injury in vitro. Our study showed that berberine blocked injury-induced SMC regrowth by inactivation of ERK/Egr-1 signaling pathway thereby preventing early signaling induced by injury in vitro. The anti-proliferative properties of berberine may be useful in treating disorders due to inappropriate SMC growth.

Recent studies have found the tryptophan allele of a glycine to tryptophan polymorphism at position 460 (G460W) of the alpha-adducin protein to be associated with essential hypertension in European populations. We examined whether the tryptophan allele is associated with hypertension in a different population, comprised of subjects of Chinese origin from Taiwan, and Chinese and Japanese origin from the San Francisco Bay area and Hawaii. We adapted the 5' allelic discrimination assay or TaqMan to type individuals for the G460W polymorphism, and using this method we typed more than 1000 individuals. The frequency of the W allele was slightly increased in the treated subjects in the Chinese population (0.458 v 0.423) but not the Japanese population (0.549 v 0.558). We considered dominant, recessive, and additive models in our analysis. There was a significant result for a recessive model for systolic blood pressure in the Chinese population (chi2 6.84, df = 2, P < .05), but only suggestive evidence for diastolic blood pressure (chi2 3.30). In contrast, in the Japanese population, there was no evidence for a positive association under any model. For the combined Chinese and Japanese samples, the evidence for association with alpha-adducin was not significant.

Recent studies have shown that tumor necrosis factor-alpha (TNFalpha), secreted by macrophage, adipocyte and muscle cells, are associated with insulin resistance syndrome i.e., hyperinsulinemia, hypertriglyceridemia and decreased high density lipoprotein (HDL) cholesterol levels. However, it is unclear whether plasma TNFalpha levels relate to insulin resistance syndrome in subjects with essential hypertension who are also characterized by an insulin resistance state. We recruited 85 nondiabetic subjects (45 men and 40 women) with essential hypertension and 85 nondiabetic subjects who were matched for age, sex and body mass index (BMI) to determine their fasting plasma glucose, insulin and lipoprotein concentrations, their glucose and insulin responses to an oral glucose challenge, and their degrees of insulin resistance. Fasting plasma leptin and TNFalpha levels were measured by radioimmunoassay and chemiluminescent enzyme immunometric assay respectively. Total body fat mass was assessed by the bioelectrical impedance method. The results showed that fasting plasma leptin levels were similar between hypertensive and normotensive subjects (7.9 +/- 0.6 vs 7.4 +/- 0.7 ng/ml, p=0.190). Fasting plasma TNFalpha concentrations were not different between subjects with hypertension and normotension (10.5 +/- 0.5 vs 9.8 +/- 0.4 pg/ml, p=0.360). Fasting plasma TNFalpha concentrations were not different across three subgroups of the insulin resistance both in hypertensive patients (8.4 +/- 0.4 vs. 10.9 +/- 1.6 vs. 9.9 +/- 1.0 pg/ml, p=0.297) and normotensive subjects (9.2 +/- 0.7 vs. 9.3 +/- 0.9 vs. 9.7 +/- 0.9 pg/ml, p=0.875). Fasting plasma TNFalpha values showed significantly positive correlations with triglyceride concentrations (p<0.03) but negative correlation with HDL cholesterol concentrations (p<0.04) in normotensive but not in hypertensive individuals. These relations persisted even after adjustment for BMI and total fat mass. In conclusion, our data indicated that circulating levels of TNFalpha did not differ between hypertensive subjects and normotensive controls. Plasma TNFalpha concentrations correlated positively with fasting plasma triglyceride levels and negatively with HDL cholesterol concentrations in normotensive but not in hypertensive subjects. The influence of TNFalpha on carbohydrate and lipoprotein metabolism in hypertensive patients deserves further investigations.

In acute atrial dilatation, the percentage of the low-voltage zones increased, especially in the LA posterior wall, which correlated with the regional splitting of the AF wavefronts. The increase in the splitting facilitated the formation of new wavefronts and resulted in a higher max DF during acute atrial dilatation.

Hyperhomocysteinemia is associated with several cardiovascular disease risk factors including endothelial dysfunction and abnormalities of clotting functions, which are also common features of insulin resistance syndrome observed in hypertensive patients. Recent study has shown that acute hyperinsulinemia can lower plasma homocysteine concentrations in nondiabetic but not in type 2 diabetic individuals, indicating that insulin may regulate homocysteine metabolism. To investigate the relationships between plasma homocysteine concentration and insulin sensitivity, we studied 90 Chinese hypertensive patients and a group of control subjects (n = 86) matched for age, gender, and body mass index. Fasting plasma homocysteine levels, plasma lipoprotein concentrations, plasma glucose, and insulin responses to oral glucose tolerance tests (OGTT) were determined. The results showed that fasting plasma homocysteine concentrations were significantly higher in subjects with hypertension than in those with normotension (mean +/- SEM, 8.1 +/- 0.6 v 6.8 +/- 0.2 micromol/L; P < .05). Fasting plasma homocysteine levels correlated significantly with insulin secretion in response to OGTT even after adjustment for body mass index (P < .05) in hypertensive patients but not in normotensive individuals. However, fasting plasma homocysteine concentrations showed no correlations with steady-state plasma glucose concentration, a measurement of insulin sensitivity, during an insulin suppression test in groups of hypertensive (n = 42) and normotensive (n = 37) subjects. When the steady-state plasma glucose concentrations were divided into three tertiles, fasting plasma homocysteine concentrations showed no difference across these three groups in either hypertensive patients (8.6 +/- 0.5 v 7.2 +/- 0.5 v 8.4 +/- 0.6 micromol/L; P = .148) or normotensive subjects (6.3 +/- 0.4 v 8.0 +/- 0.8 v 7.0 +/- 0.8 micromol/L; P = .199). In conclusion, hypertensive Chinese subjects had higher fasting plasma homocysteine concentrations and a higher degree of insulin resistance when compared to a group of age-, gender-, and body mass index-matched normotensive individuals. Fasting plasma homocysteine levels were associated with insulin response to OGTT in hypertensives but not in normotensives. No correlation was observed between the degree of insulin resistance and plasma homocysteine levels in either the hypertensive or the normotensive group. The role of insulin in homocysteine metabolism deserves further investigation.