Accurate quantitation of JAK2 V617F allele burden by array-based digital PCR.

INTRODUCTION: The JAK2 V617F mutation is highly prevalent in patients with myeloproliferative neoplasms (MPN). Several studies have shown that allele burden correlates with hematologic characteristics and clinical end-points in patients with MPN. Allele-specific real-time quantitative polymerase chain reaction (RQ-PCR) is probably the most commonly used technique for detection and quantitation of the JAK2 V617F mutation. Alternatively, digital PCR is an emerging technology for absolute DNA quantitation, which is based on dilution and high-grade partitioning of a sample. METHODS: We compared array-based digital PCR using the QuantStudio(™) 3D Digital PCR System platform with a RQ-PCR assay, CE-registered for in vitro diagnostic use, regarding JAK2 V617F allele quantitation. This study included 30 samples positive for the JAK2 V617F mutation and additionally 13 samples without the mutation. RESULTS: JAK2 V617F allele burden of samples ranged between well below 1% and more than 90%. Linear regression analysis showed a high correlation between the results obtained from the two techniques (r(2) = 0.9983). Thirteen samples tested negatively for the JAK2 V617F mutation with RQ-PCR were also found negative with digital PCR. CONCLUSION: We conclude that array-based digital PCR is an appropriate method for the quantitation of JAK2 V617F allele burden demonstrating highest correlation with allele-specific RQ-PCR.

Hypoxia induces apelin expression in human adipocytes.

Adipokines play a central role in the development of diseases associated with insulin resistance and obesity. Hypoxia in adipose tissue leads to a dysregulation of the expression of adipokines. The effect of hypoxia on the more recently identified adipokine apelin in human adipocytes is unclear. Therefore, we aimed at investigating the role of hypoxia on the expression of the adipokine apelin. Differentiated human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were cultured under hypoxic conditions for varying time periods. A modular incubator chamber was used to create a hypoxic tissue culture environment (defined as 1% O(2), 94% N, and 5% CO(2)). In addition, hypoxic conditions were mimicked by using CoCl(2). The effect of hypoxia on the expression of the investigated adipokines was measured by real-time PCR and the secretion of apelin was quantified by ELISA. Induction of hypoxia significantly induced mRNA expression of leptin and apelin in differentiated SGBS adipocytes compared with the normoxic control condition. Expression of adiponectin was significantly decreased by hypoxia. In addition, the amount of secreted apelin protein in response to hypoxia was elevated compared to untreated cells. Furthermore, we could demonstrate that the observed hypoxia-induced induction of apelin mRNA expression is in the first phase dependent on HIF-1α. In our study, we could demonstrate for the first time that apelin expression and secretion by human adipocytes are strongly induced under hypoxic conditions and that the early response on hypoxia with apelin induction is dependent on HIF-1α.

Low bone mineral density is not associated with angiographically determined coronary atherosclerosis in men.

UNLABELLED: This study for the first time investigates the association of bone mineral density (BMD) with angiographically determined coronary atherosclerosis in men. Our data show that the prevalence of low BMD is very high in men undergoing coronary angiography. However, neither osteopenia nor osteoporosis is associated with an increased prevalence of angiographically determined coronary atherosclerosis. INTRODUCTION: The association of low BMD with angiographically determined coronary atherosclerosis in men is unknown. METHODS: We enrolled 623 consecutive men undergoing coronary angiography for the evaluation of established or suspected coronary artery disease (CAD). BMD was assessed by dual X-ray absorptiometry. CAD was diagnosed in the presence of any coronary artery lumen narrowing at angiography; coronary stenoses with lumen narrowing > or =50% were considered significant. RESULTS: From the total study cohort (mean age of 64 +/- 11 years), 207 patients (33.2%) had osteopenia and 65 (10.4%) had osteoporosis; at angiography, CAD was diagnosed in 558 patients (89.6%) and 403 (64.7%) had significant coronary stenoses. In multivariate logistic regression analysis neither osteopenia nor osteoporosis was associated with an increased prevalence of CAD (adjusted odds ratios (ORs) = 0.71 [95% confidence interval 0.40-1.23]; p = 0.222 and 1.03 [0.38-2.80]; p = 0.955, respectively) or with significant coronary stenoses (OR 0.74 [0.52-1.07], p = 0.112 and 0.72 [0.41-1.26]; p = 0.251, respectively). Also, as a continuous variable, BMD was not associated with angiographically diagnosed CAD. CONCLUSIONS: The prevalence of low BMD is very high in men undergoing coronary angiography. However, low BMD is not associated with angiographically determined coronary atherosclerosis in men.

Synergistic effects of the apolipoprotein E epsilon3/epsilon2/epsilon4, the cholesteryl ester transfer protein TaqIB, and the apolipoprotein C3 -482 C>T polymorphisms on their association with coronary artery disease.

The single nucleotide polymorphisms (SNPs) apolipoprotein E (APOE) epsilon3/epsilon2/epsilon4, cholesteryl ester transfer protein (CETP) TaqIB, and apolipoprotein C3 (APOC3) -482 C>T have been associated with an atherogenic lipid profile and, in some studies, with increased cardiovascular risk. However, no data exist on their combined impact on atherosclerotic disease. We therefore aimed at investigating the combined impact of these SNPs on the presence of angiographically determined coronary artery disease (CAD). Genotyping was performed in 557 consecutive Caucasian patients undergoing coronary angiography for the evaluation of CAD. From the individual SNPs, only the APOE epsilon3epsilon4/epsilon4epsilon4 genotype was significantly associated with an increased risk of significant coronary stenoses with lumen narrowing >or=50% (odds ratio (OR)=1.77 [1.16-2.71]; p=0.008). However, the risk of CAD strongly increased when more than one of the analysed genetic variants was present: ORs were 2.74 [1.29-5.83]; p=0.009 for patients with both the APOE epsilon3epsilon4/epsilon4epsilon4 and the CETP B1B1 genotype, 1.97 [1.06-3.66]; p=0.031 for patients with both the APOE epsilon3epsilon4/epsilon4epsilon4 genotype and the APOC3 -482T allele, 2.12 [1.31-3.44]; p=0.002 for patients with both the CETP B1B1 genotype and the APOC3 -482T allele, and 3.99 [1.57-13.79]; p=0.029 for patients with all three variants. Multivariate analyses confirmed these results. We conclude that there are strong synergistic effects of the APOE epsilon3/epsilon2/epsilon4, the CETP TaqIB, and the APOC3 -482 C>T polymorphisms on their association with CAD.

Estrogen-metabolizing gene polymorphisms and age at natural menopause in Caucasian women.

BACKGROUND: Lifestyle parameters, personal history and genetic factors are thought to affect the timing of natural menopause in humans. Based on their biological function, estrogen-metabolizing gene polymorphisms have been regarded as candidate genes for early menopause. METHODS: In the present cross-sectional, multi-centre study, we analysed nine single nucleotide polymorphisms of six estrogen-metabolizing genes [three estrogen-synthesizing genes, i.e. 17-beta-hydroxysteroid dehydrogenase type 1 (17-beta HSD), cytochrome P-450 (CYP) 17 and CYP19; and three estrogen-inactivating genes, i.e. catechol-O-methyltransferase (COMT), CYP1A1 and CYP1B1] by sequencing-on-chip-technology in 1360 Caucasian women with natural menopause. Women's lifestyle parameters, reproductive and personal histories were ascertained. RESULTS: Carriage of at least one mutant allele of the CYP1B1-4 Asn453Ser A--> G polymorphism (P = 0.004) and the number of full-term pregnancies (P < 0.001) were found to be independently associated with age at natural menopause. Women with at least one polymorphic allele of CYP1B1-4 experienced natural menopause earlier than non-carriers of the polymorphism [mean (SD) 48.6 (5.0) versus 49.4 (4.3) years]. Women with no, one, two and three or more full-term pregnancies experienced natural menopause at 48.5 (5.0), 48.8 (4.8), 49.5 (4.2) and 49.6 (4.6) years, respectively. CONCLUSION: We present the most comprehensive data on estrogen-metabolizing gene polymorphisms and timing of natural menopause to date. The number of full-term pregnancies and the CYP1B1-4 polymorphism are significant predictors of timing of natural menopause in Caucasian women.