Syed M. Mohiuddin

Vitamin D deficiency induces cardiac hypertrophy and inflammation in epicardial adipose tissue in hypercholesterolemic swine

INTRODUCTIONnVitamin D is a sectosteroid that functions through Vitamin D receptor (VDR), a transcription factor, which controls the transcription of many targets genes. Vitamin D deficiency has been linked with cardiovascular diseases, including heart failure and coronary artery disease. Suppressor of cytokine signaling (SOCS)3 regulates different biological processes such as inflammation and cellular differentiation and is an endogenous negative regulator of cardiac hypertrophy.nnnOBJECTIVEnThe purpose of this study was to test the hypothesis that vitamin D deficiency causes cardiomyocyte hypertrophy and increased proinflammatory profile in epicardial adipose tissue (EAT), and this correlates with decreased expression of SOCS3 in cardiomyocytes and EAT.nnnMETHODSnEight female Yucatan miniswine were fed vitamin D-sufficient (900 IU/d) or vitamin D-deficient hypercholesterolemic diet. Lipid profile, metabolic panel, and serum 25(OH)D levels were regularly measured. After 12 months animals were euthanized and histological, immunohistochemical and qPCR studies were performed on myocardium and epicardial fat.nnnRESULTSnHistological studies showed cardiac hypertrophy, as judged by cardiac myocyte cross sectional area, in the vitamin D-deficient group. Immunohistochemical and qPCR analyses showed significantly decreased mRNA and protein expression of VDR and SOCS3 in cardiomyocytes of vitamin D-deficient animals. EAT from vitamin D-deficient group had significantly higher expression of TNF-α, IL-6, MCP-1, and decreased adiponectin in association with increased inflammatory cellular infiltrate. Interestingly, EAT from vitamin D-deficient group had significantly decreased expression of SOCS3.nnnCONCLUSIONnThese data suggest that vitamin D deficiency induces hypertrophy in cardiomyocytes which is associated with decreased expression of VDR and SOCS3. Vitamin D deficiency is also associated with increased inflammatory markers in EAT. Activity of VDR in the body is controlled through regulation of vitamin D metabolites. Therefore, restoration of VDR function by supplementation of VDR ligands in vitamin D-deficient population might be helpful in reducing inflammation and cardiovascular risk.

Fixed-dose combination vs monotherapy in hypertension: A meta-analysis evaluation

Fixed-dose combination antihypertensive therapy has received interest since the publication of the JNC-VI report. Relatively few head-to-head comparative studies between fixed-dose combinations and first-line monotherapies for hypertension have been published. The objective of this study was to conduct a meta-analysis of various first-line monotherapies and the fixed-dose combination of amlodipine/benazepril. The results of the meta-analysis were used to compare the efficacy and safety of the first-line monotherapies with amlo- dipine/benazepril. The meta-analysis included 82 studies that included 110 treatment groups (cohorts). The study compared nine different monotherapies and one combination therapy (amlodipine/benazepril). Of the 82 studies, 22 were placebo-controlled and 60 were active treatment controlled. The mean absolute decrease in supine diastolic blood pressure (BP) ranged from 9.7 to 13.3 mmu2009Hg with verapamil showing the greatest effect and captopril the least (13.3u2009±u20093.0 mmu2009Hg; 9.7u2009±u20092.9 mmu2009Hg, respectively). When studies were weighted by sample size, atenolol, verapamil, lisinopril and amlo- dipine/benazepril showed the greatest BP effect. When studies were weighted by variance, amlo- dipine/benazepril and atenolol showed the greatest BP effect. The percentage of patients controlled on therapy ranged from 54% to 79% Lisinopril and amlodipine/benazepril showed the greatest percent controlled. The overall incidence of adverse effects ranged from 12.1% to 41.8% with lisinopril having the lowest and nifedipine having the highest incidence. The overall incidence of adverse effects resulting in drug discontinuance ranged from 1.3% to 10.7%, with amlodipine/benazepril having the lowest and nifedipine having the highest incidence. The results of the meta-analysis indicate that amlodipine/benazepril produces above average reductions in BP with a lower than average incidence of overall side effects and the lowest incidence of adverse effects resulting in drug discontinuance. The fixed-dose combination of amlodipine/ benazepril achieves its goal of effective BP lowering with a minimum of significant side effects.

Fenofibric acid for hyperlipidemia

Introduction: 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (i.e., statins) are the mainstay of therapy for hyperlipidemia, as per the current National Cholesterol Education Program (NCEP) recommendation. However, the role of other agents, such as the fibrates, is continually being debated in the context of incremental risk reduction, especially in the setting of mixed dyslipidemia. Results from the ACCORD Trial have further added to the confusion. Fibrates also have a role to play in familial hyperlipidemias and in hypertriglyceridemia. Fenofibric acid is one of the newly approved forms of fenofibrate with enhanced bioavailability and was recently approved by the Food and Drug Administation (FDA) for the treatment of various types of hyperlipidemia, in conjunction with statins. Areas covered: This article reviews the role of fenofibric acid in the context of results from recent randomized trials on fenofibrate, including the ACCORD Trial. It discusses the current status of fenofibric acid in the management of dyslipidemia, especially in combination with statins, and also addresses the comparative efficacy and safety profile of this new molecule against other agents in its class. Expert opinion: fenofibric acid in combination with low- to moderate-dose statins is an effective and safe option in the treatment of mixed dyslipidemia, although the long-term effects on cardiovascular risk reduction need to be explored further.

Identification of pathogenic gene mutations in LMNA and MYBPC3 that alter RNA splicing

Significance Sequence variants that create or eliminate splice sites are often clinically classified as variants of unknown significance (VUS) due to imperfect understanding of RNA splice signals and cumbersome functional assays. In autosomal dominant disorders caused by haploinsufficiency, variants that alter normal splicing of one allele are pathogenic. We developed enhanced computational tools to prioritize potential splice-altering VUS and used a minigene assay to functionally confirm splice-altering sequence variants. In studying all reported variants across LMNA and MYBPC3, two known heart disease genes, we demonstrate that ∼5% of VUS from affected patients alter splicing and are undetected disease-causing variants. This strategy improves clinical detection of pathogenic variants and should be broadly relevant to other human disorders that are caused by haploinsufficiency. Genetic variants that cause haploinsufficiency account for many autosomal dominant (AD) disorders. Gene-based diagnosis classifies variants that alter canonical splice signals as pathogenic, but due to imperfect understanding of RNA splice signals other variants that may create or eliminate splice sites are often clinically classified as variants of unknown significance (VUS). To improve recognition of pathogenic splice-altering variants in AD disorders, we used computational tools to prioritize VUS and developed a cell-based minigene splicing assay to confirm aberrant splicing. Using this two-step procedure we evaluated all rare variants in two AD cardiomyopathy genes, lamin A/C (LMNA) and myosin binding protein C (MYBPC3). We demonstrate that 13 LMNA and 35 MYBPC3 variants identified in cardiomyopathy patients alter RNA splicing, representing a 50% increase in the numbers of established damaging splice variants in these genes. Over half of these variants are annotated as VUS by clinical diagnostic laboratories. Familial analyses of one variant, a synonymous LMNA VUS, demonstrated segregation with cardiomyopathy affection status and altered cardiac LMNA splicing. Application of this strategy should improve diagnostic accuracy and variant classification in other haploinsufficient AD disorders.