Search PubMed⌕ Search

Biomedical subjects

Subodh Verma

Publications and source records attributed to Subodh Verma.

At least 37 records · Page 2Linked to original sources
PubMed2006

The vascular biology of peroxisome proliferator-activated receptors: modulation of atherosclerosis.

Accumulating evidence suggests that peroxisome proliferator-activated receptor (PPAR) agonists possess powerful antiatherosclerotic properties, by both directly affecting the vascular wall and indirectly affecting systemic inflammation and insulin sensitivity. The PPARs are ligand-activated transcription factors, which play a number of important physiological roles in lipid and glucose homeostasis. Activation of PPARgamma appears to exert a vasculoprotective effect by limiting endothelial dysfunction, impairing atherogenesis and preventing restenosis, while simultaneously and favourably modulating adipokine expression and lipid metabolism. Several experimental and clinical studies have demonstrated the potential of the PPAR agonist drug class in terms of treating atherosclerotic disease. In the present review, the vascular biology of PPARs, and how the modulation of these molecular pathways may serve as a therapeutic strategy to prevent atherosclerosis, vascular inflammation and restenosis are discussed.

Adiponectin↗
PubMed2006

Cardioprotective c-kit+ cells are from the bone marrow and regulate the myocardial balance of angiogenic cytokines.

Clinical trials of bone marrow stem/progenitor cell therapy after myocardial infarction (MI) have shown promising results, but the mechanism of benefit is unclear. We examined the nature of endogenous myocardial repair that is dependent on the function of the c-kit receptor, which is expressed on bone marrow stem/progenitor cells and on recently identified cardiac stem cells. MI increased the number of c-kit+ cells in the heart. These cells were traced back to a bone marrow origin, using genetic tagging in bone marrow chimeric mice. The recruited c-kit+ cells established a proangiogenic milieu in the infarct border zone by increasing VEGF and by reversing the cardiac ratio of angiopoietin-1 to angiopoietin-2. These oscillations potentiated endothelial mitogenesis and were associated with the establishment of an extensive myofibroblast-rich repair tissue. Mutations in the c-kit receptor interfered with the mobilization of the cells to the heart, prevented angiogenesis, diminished myofibroblast-rich repair tissue formation, and led to precipitous cardiac failure and death. Replacement of the mutant bone marrow with wild-type cells rescued the cardiomyopathic phenotype. We conclude that, consistent with their documented role in tumorigenesis, bone marrow c-kit+ cells act as key regulators of the angiogenic switch in infarcted myocardium, thereby driving efficient cardiac repair.

Animals↗
PubMed2006

The effect of iron status on vascular health.

The effect of increased iron stores on the progression of atherosclerosis and endothelial health remains inconclusive. This study was designed to evaluate the relationship between hemochromatosis genotypes, serum ferritin levels and presymptomatic vascular abnormalities in a cohort of healthy subjects. Carotid intima-media thickness (CIMT) and brachial flow-mediated vasodilation (FMD) were assessed by high-resolution ultrasound in 907 male (47 +/- 10 years) participants enrolled in the Firefighters and their Endothelium (FATE) study. Analyses of the hemochromatosis C282Y, H63D and S65C alleles were simultaneously determined by a single nucleotide polymorphism (SNP) primer extension method. It was found that brachial FMD was not related to serum ferritin or hemochromatosis genotype status. The presence of a hemochromatosis-associated genotype (n = 18) or heterozygosity for the C282Y genotype (n = 98) was not associated with an increased mean CIMT. After adjustment for conventional risk factors, serum ferritin was also not associated with mean CIMT. In conclusion, neither ferritin nor a hemochromatosis genotype was related to brachial endothelial function or carotid atherosclerosis. The present study does not support the hypothesis that mild to moderately increased iron stores are associated with enhanced atherosclerosis risk.

Adult↗
PubMed2005

Cell transplantation preserves matrix homeostasis: a novel paracrine mechanism.

OBJECTIVES: Cell transplantation prevents chamber dilatation, but the underlying molecular mechanisms remain undefined. Structural cardiac remodeling involves matrix degradation from an imbalance of matrix metalloproteinases (MMP) relative to endogenous tissue inhibitors of metalloproteinases (TIMP). We aimed to determine the capacity of cell transplantation to alter extracellular matrix in the failing heart and, in so doing, identify novel paracrine molecular mediators underlying the beneficial effects of cell transplantation on chamber dilatation. METHODS: Smooth muscle cells were transplanted to the dilating left ventricle of cardiomyopathic hamsters (CTX, n = 15) compared with age-matched media-injected cardiomyopathic (CON, n = 15) and normal hamsters (n = 7). After 5 weeks, left ventricular volume was measured by computerized planimetry. Fibrillar collagen was examined by confocal microscopy. Matrix homeostasis was quantified by measuring MMP/TIMP expression/activity relative to myocardial collagen synthesis (14C-proline uptake). RESULTS: Left ventricular dilatation was attenuated in CTX hearts (P = .02). CTX restored perimysial collagen fiber content and architecture to normal levels. TIMP-2 and TIMP-3 expression were enhanced in CTX (TIMP-2, 195% +/- 42% of CON, P = .02; TIMP-3, 118% +/- 3% of CON, P = .002), and correspondingly, gelatinase MMP-2 activity was reduced (P < .05). The TIMP:MMP ratio was increased in CTX hearts (TIMP-2 to MMP-2, 410% +/- 134% of CON, P = .04, and TIMP-3 to MMP-9, 205% +/- 47% of CON, P = .03), reflecting a reduced capacity for matrix degradation. Collagen synthesis was equivalent (CTX vs CON), suggesting that restored matrix architecture was a function of attenuated matrix degradation. CONCLUSIONS: These data provide the first evidence that cell transplantation limits ventricular dilatation in the failing heart through a paracrine-mediated mechanism that preserves extracellular matrix homeostasis.

Animals↗
PubMed2005

Relationship between carotid artery intima-media thickness and brachial artery flow-mediated dilation in middle-aged healthy men.

OBJECTIVES: We aimed to determine the relationship between carotid intima-media thickness (IMT) and brachial artery flow-mediated dilation (FMD) in healthy middle-age men. BACKGROUND: Carotid IMT and brachial artery FMD are frequently used as surrogate measures of subclinical atherosclerosis. Whereas carotid IMT identifies early structural abnormalities, brachial artery FMD, considered a bioassay of endothelial function, measures functional vascular integrity. The relationship between carotid IMT and brachial artery FMD has not been well studied. METHODS: We measured traditional risk factors, carotid IMT, and brachial artery FMD in 1,578 middle-aged men without known cardiovascular disease and analyzed the relationship between carotid IMT and brachial FMD. RESULTS: Carotid IMT correlated with age, systolic blood pressure, body mass index, fasting glucose, total and low-density lipoprotein (LDL) cholesterol, and with the overall Framingham risk score (p < 0.001 for all), whereas impaired brachial artery FMD correlated with systolic and diastolic blood pressure (p < 0.01). No relationship was observed between carotid IMT and brachial artery FMD for the entire cohort (r = -0.006, p = 0.82) and in subgroups defined by traditional risk factors or by quintiles of carotid IMT and brachial FMD. CONCLUSIONS: In middle-aged healthy men, there is no significant correlation between carotid IMT and brachial artery FMD. This finding suggests that these are unique, independent surrogates that measure different aspects and stages of early atherosclerosis. Further studies are needed to define their role in clinical research and in cardiovascular risk assessment.

Adult↗
PubMed2005

Nocturnal hemodialysis is associated with restoration of impaired endothelial progenitor cell biology in end-stage renal disease.

Cardiovascular disease is the principal cause of death in end-stage renal disease (ESRD) patients. Endothelial progenitor cells (EPCs) play a critical role in vascular repair, and improving EPC biology represents a novel therapeutic target. Three groups of age- and gender-matched patients were studied: 1) 10 healthy control, 2) 12 conventional hemodialysis (CHD) patients, and 3) 10 nocturnal hemodialysis (NHD) patients. EPC number and migratory function were assessed. Left ventricular mass index (LVMI) was derived, and correlations between EPC biology, uremic clearance, and LVMI were made. Compared with controls, EPC number and function were markedly impaired in CHD patients [(3.48 +/- 1.2 vs. 0.86 +/- 0.20%/50,000 cells, P < 0.05) and (18.8 +/- 2.64 vs. 3.75 +/- 0.34 cells/high-power field, P < 0.05), respectively]. In contrast, EPC number and function were normal in NHD patients [(3.48 +/- 1.17 vs. 3.83 +/- 0.77%/50,000 cells) and (18.8 +/- 2.6 vs. 22.2 +/- 2.4 cells/high-power field), respectively]. Among ESRD patients, EPC number and function inversely correlated with predialysis urea concentration (r = -0.40; r = -0.57), LVMI (r = -0.41; -0.46) and systolic BP (r = -0.58; r = -0.44). We demonstrate that NHD is associated with restoration of abnormal EPC biology in ESRD. Given the increasing importance of EPCs in the repair and restoration of cardiovascular function, these data have important clinical implications for vascular risk in ESRD patients.

Blood Pressure↗
PubMed2005

The relationship between soluble CD40 ligand levels and Framingham coronary heart disease risk score in healthy volunteers.

Elevated soluble CD40 ligand (sCD40L) levels are associated with an increased risk of cardiovascular events in patients with acute coronary syndromes and in middle-aged healthy women. However, the relationship between sCD40L and global risk assessment remains unclear. The present study was designed to examine the relationship between sCD40L and Framingham Coronary Heart Disease Risk Scores (FCRS) in healthy middle-aged men. The study population consisted of 400 active and retired male firefighters, with no previous history of cardiovascular disease, as part of the Firefighters and Their Endothelium (FATE) study. FCRS correlated poorly with sCD40L levels (p=0.14). Soluble CD40L concentrations correlated only with total (r=0.105; p=0.035) and LDL cholesterol (r=0.104; p=0.039), and CRP levels (r=0.11; p=0.03). Compared with participants with sCD40L levels <4.36 ng/mL (75th percentile), participants with sCD40L levels >4.36 ng/mL had higher total (p=0.016) and LDL cholesterol (p=0.018), CRP levels (p=0.034) and FCRS (p=0.012). Multivariate analysis revealed that CRP level was the only parameter that independently correlated with the sCD40L levels (p=0.032). This is the first study to evaluate the relationship between sCD40L levels and Framingham global risk assessment in a large cohort of otherwise healthy individuals. We demonstrate that sCD40L levels poorly correlate with both the individual components and the calculated FCRS. Long-term follow-up of the FATE study will shed light on whether the predictive value of sCD40L is independent of Framingham based global risk assessment.

Adult↗
PubMed2005

Tetrahydrobiopterin deficiency exaggerates intimal hyperplasia after vascular injury.

Decreased levels of tetrahydrobiopterin (BH4), an absolute cofactor for nitric oxide synthase (NOS), lead to uncoupling of NOS into a superoxide v. nitric oxide producing enzyme, and it is this uncoupling that links it to the development of vascular disease. However, the effects of in vivo deficiency of BH4 on neointimal formation after vascular injury have not been previously investigated. Hph-1 mice, which display 90% deficiency in guanine triphosphate cyclohydrolase I, the rate limiting enzyme in BH4 synthesis, were used. Hph-1 and wild-type mice, treated with either vehicle or BH4 (n = 15 per group), were subjected to wire-induced femoral artery injury, and NOS expression and activity, inflammation, cell proliferation, superoxide production, and neointimal formation were assessed. The major form of NOS expressed over vessel wall after vascular injury was endothelial NOS. Hph-1 mice exhibited lower NOS activity (2.8 +/- 0.3 vs. 4.5 +/- 0.4 pmol/min/mg protein, P < 0.01), and higher aortic superoxide content (5.2 +/- 2.0 x 10(5) cpm vs. 1.6 +/- 0.7 x 10(5) cpm, P < 0.01) compared with wild-type controls, indicating uncoupling of NOS. Treatment of hph-1 mice with BH4 significantly increased NOS activity (from 2.8 +/- 0.3 to 4.1 +/- 0.4 pmol.min(-1).mg protein(-1), P < 0.05), and attenuated superoxide production (from 5.2 +/- 2.0 x 10(5) cpm to 0.8 +/- 0.7 x 10(5) cpm, P < 0.05). Hph-1 mice also had higher inflammatory reactions and more cell proliferation after vascular injury. Furthermore, hph-1 mice responded by a marked increase in neointimal formation at 4 wk after vascular injury, compared with wild-type controls (intima:media ratio: 4.5 +/- 0.5 vs. wild-type 0.7 +/- 0.1, P < 0.001). Treatment of hph-1 mice with BH4 prevented vascular injury-induced increase in neointimal formation (intima:media ratio: 1.4 +/- 0.1 vs. hph-1, P < 0.001). Treatment had no effect on wild-type controls. In summary, we describe, for the first time, that in vivo BH4 deficiency facilitates neointimal formation after vascular injury. Modulation of BH4 bioavailability is an important therapeutic target for restenosis.

Animals↗
PubMed2005

Antiatherogenic potential of red wine: clinician update.

Complications of atherosclerosis remain the leading cause of morbidity and mortality in industrialized countries. Epidemiological studies have repeatedly demonstrated that moderate alcohol intake has a beneficial effect on cardiovascular disease. The purpose of this review is to examine the epidemiological and biological evidence supporting the intake of red wine as a means of reducing atherosclerosis. On the basis of epidemiological studies, moderate intake of alcoholic beverages, including red wine, reduces the risk of cardiovascular, cerebrovascular, and peripheral vascular disease in populations. In addition to the favorable biological effects of alcohol on the lipid profile, on hemostatic factors, and in reducing insulin resistance, the phenolic compounds in red wine appear to interfere with the molecular processes underlying the initiation, progression, and rupture of atherosclerotic plaques. Whether red wine is more beneficial than other types of alcohol remains unclear. Definitive data from a large-scale, randomized clinical end-point trial of red wine intake would be required before physicians can advise patients to use wine as part of preventative or medical therapies.

Alcohol Drinking↗
PubMed2005

Adipokines: molecular links between obesity and atheroslcerosis.

Atherosclerotic disease remains the leading cause of death in industrialized nations despite major advances in its diagnosis, treatment, and prevention. The increasing epidemic of obesity, insulin resistance, and diabetes will likely add to this burden. Increasingly, it is becoming apparent that adipose tissue is an active endocrine and paracrine organ that releases several bioactive mediators that influence not only body weight homeostasis but also inflammation, coagulation, fibrinolysis, insulin resistance, diabetes, and atherosclerosis. The cellular mechanisms linking obesity and atherosclerosis are complex and have not been fully elucidated. This review summarizes the experimental and clinical evidence on how excess body fat influences cardiovascular health through multiple yet converging pathways. The role of adipose tissue in the development of obesity-linked insulin resistance, metabolic syndrome, and diabetes will be reviewed, including an examination of the molecular links between obesity and atherosclerosis, namely, the effects of fat-derived adipokines. Finally, we will discuss how these new insights may provide us with innovative therapeutic strategies to improve cardiovascular health.

Adipose Tissue↗