Menopausal Status and Abdominal Obesity Are Significant Determinants of Hepatic Lipid Metabolism in Women.

BACKGROUND: Android fat distribution (abdominal obesity) is associated with insulin resistance, hepatic steatosis, and greater secretion of large very low-density lipoprotein (VLDL) particles in men. Since abdominal obesity is becoming increasingly prevalent in women, we aimed to investigate the relationship between android fat and hepatic lipid metabolism in pre- and postmenopausal women. METHODS AND RESULTS: We used a combination of stable isotope tracer techniques to investigate intrahepatic fatty acid synthesis and partitioning in 29 lean and 29 abdominally obese women (android fat/total fat 0.065 [0.02 to 0.08] and 0.095 [0.08 to 0.11], respectively). Thirty women were premenopausal aged 35 to 45 and they were matched for abdominal obesity with 28 postmenopausal women aged 55 to 65. As anticipated, abdominal obese women were more insulin resistant with enhanced hepatic secretion of large (404±30 versus 268±26 mg/kg lean mass, P<0.001) but not small VLDL (160±11 versus 142±13). However, postmenopausal status had a pronounced effect on the characteristics of small VLDL particles, which were considerably triglyceride-enriched (production ratio of VLDL2- triglyceride:apolipoprotein B 30±5.3 versus 19±1.6, P<0.05). In contrast to postmenopausal women, there was a tight control of hepatic fatty acid metabolism and triglyceride production in premenopausal women, whereby oxidation (rs=-0.49, P=0.006), de novo lipogenesis (rs=0.55, P=0.003), and desaturation (rs=0.48, P=0.012) were closely correlated with abdominal obesity-driven large VLDL-triglyceride secretion rate. CONCLUSIONS: In women, abdominal obesity is a major driver of hepatic large VLDL particle secretion, whereas postmenopausal status was characterized by increased small VLDL particle size. These data provide a mechanistic basis for the hyperlipidemia observed in postmenopausal obesity.

LRP5 regulates human body fat distribution by modulating adipose progenitor biology in a dose- and depot-specific fashion.

Common variants in WNT pathway genes have been associated with bone mass and fat distribution, the latter predicting diabetes and cardiovascular disease risk. Rare mutations in the WNT co-receptors LRP5 and LRP6 are similarly associated with bone and cardiometabolic disorders. We investigated the role of LRP5 in human adipose tissue. Subjects with gain-of-function LRP5 mutations and high bone mass had enhanced lower-body fat accumulation. Reciprocally, a low bone mineral density-associated common LRP5 allele correlated with increased abdominal adiposity. Ex vivo LRP5 expression was higher in abdominal versus gluteal adipocyte progenitors. Equivalent knockdown of LRP5 in both progenitor types dose-dependently impaired ß-catenin signaling and led to distinct biological outcomes: diminished gluteal and enhanced abdominal adipogenesis. These data highlight how depot differences in WNT/ß-catenin pathway activity modulate human fat distribution via effects on adipocyte progenitor biology. They also identify LRP5 as a potential pharmacologic target for the treatment of cardiometabolic disorders.

Lower resting and total energy expenditure in postmenopausal compared with premenopausal women matched for abdominal obesity.

The menopause is accompanied by increased risk of obesity, altered body fat distribution and decreased skeletal muscle mass. The resulting decrease in RMR should be accompanied by a compensatory change in energy balance to avoid weight gain. We aimed to investigate habitual energy intake and expenditure in pre- and postmenopausal women matched for abdominal obesity. We recruited fifty-one healthy Caucasian women, BMI > 18·5 and <35 kg/m(2), aged 35-45 years (premenopausal, n 26) and 55-65 years (postmenopausal, n 25). Energy intake was measured using 3 d diet diaries and dietary fat quality assessed using adipose tissue fatty acid biomarkers. RMR was measured using indirect calorimetry, and total energy expenditure (TEE) and activity energy expenditure using a combined accelerometer and heart rate monitor. Postmenopausal women had lower RMR and TEE and spent significantly less time undertaking moderate exercise than premenopausal women. Postmenopausal women had a tendency for a lower energy intake, and a similar macronutrient intake but a significantly lower adipose tissue n-6:n-3 ratio (24·6 (se 1·6) v. 37·7 (se 3·1); P < 0·001). The main lifestyle determinant of bone mineral density (which was significantly lower in postmenopausal women) was TEE for premenopausal women, and dietary n-6:n-3 ratio for postmenopausal women. The present results suggest that weight maintenance is achieved in the post- compared with premenopausal status through a combination of reduced energy intake and reduced TEE in a regimen that compromises micronutrient intake and has a negative impact on lean tissue mass. However, lower n-6:n-3 fatty acid intake in postmenopausal women is associated with greater bone mineral density.

Structural and functional properties of deep abdominal subcutaneous adipose tissue explain its association with insulin resistance and cardiovascular risk in men.

OBJECTIVE: Fat distribution is an important variable explaining metabolic heterogeneity of obesity. Abdominal subcutaneous adipose tissue (SAT) is divided by the Scarpa's fascia into a deep subcutaneous adipose tissue (dSAT) and a superficial subcutaneous adipose tissue (sSAT) layer. This study sought to characterize functional differences between the two SAT layers to explore their relative contribution to metabolic traits and cardiovascular risk (CVR) profile. RESEARCH DESIGN AND METHODS: We recruited 371 Caucasians consecutively from a local random, population-based screening project in Oxford and 25 Asian Indians from the local community. The depth of the SAT layers was determined by ultrasound (US), and adipose tissue (AT) biopsies were performed under US guidance in a subgroup of 43 Caucasians. Visceral adipose tissue (VAT) mass was quantified by dual-energy X-ray absorptiometry scan. RESULTS: Male adiposity in both ethnic groups was characterized by a disproportionate expansion of dSAT, which was strongly correlated with VAT mass. dSAT depth was a strong predictor of global insulin resistance (IR; homeostatic model assessment of IR), liver-specific IR (insulin-like growth factor binding protein-1), and Framingham risk score independently of other measures of adiposity in men. Moreover, dSAT had higher expression of proinflammatory, lipogenic, and lipolytic genes and contained higher proportions of saturated fatty acids. There was increased proportion of small adipocytes in dSAT. CONCLUSIONS: SAT is heterogeneous; dSAT expands disproportionally more than sSAT with increasing obesity in Caucasian males (confirmed also in Asian Indians). Its expansion is related to increased CVR independent of other adiposity measures, and it has biological properties suggestive of higher metabolic activity contributing to global IR.

Correlation of arm position and exercise test interpretation.

ST-segment changes during exercise testing can be attributed mainly to ischemia, but also, in some patients, to other physiological parameters, such as body position or hyperventilation, making ECG exercise test interpretation more complex. Here we describe the case of a patient who had an electrocardiographically positive exercise test, in order to illustrate the correlation between arm position and ST changes during exercise testing.

The role of adiponectin in human vascular physiology.

Adiponectin (ApN) is an adipose tissue-derived hormone which is involved in a wide variety of physiological processes including energy metabolism, inflammation, and vascular physiology via actions on a broad spectrum of target organs including liver, skeletal muscle, and vascular endothelium. Besides possessing insulin sensitizing and anti-inflammatory properties ApN also exerts a pivotal role in vascular protection through activation of multiple intracellular signaling cascades. Enhancement of nitric oxide generation and attenuation of reactive oxygen species production in endothelial cells along with reduced vascular smooth muscle cell proliferation and migration constitute some of ApN's vasoprotective actions. Additionally, recent data indicate that ApN has direct myocardio-protective effects. Decreased plasma ApN levels are implicated in the pathogenesis of the metabolic syndrome and atherosclerosis and may serve as a diagnostic and prognostic biomarker as well as a rational pharmaco-therapeutic target to treat these disorders. This review article summarizes recent work on the cardiovascular actions of ApN.

Myocardial redox state predicts in-hospital clinical outcome after cardiac surgery effects of short-term pre-operative statin treatment.

OBJECTIVES: The purpose of this study was to evaluate the role of the myocardial redox state in the development of in-hospital complications after cardiac surgery and the effect of statins on the myocardial redox state. BACKGROUND: Statins improve clinical outcome after cardiac surgery, but it is unclear whether they exert their effects by modifying the myocardial redox state. METHODS: We quantified myocardial superoxide anion (O(2)(-)) and peroxynitrite (ONOO(-)) and their enzymatic sources in samples of the right atrial appendage (RAA) from 303 patients undergoing cardiac surgery who were followed up until discharge, and in 42 patients who were randomized to receive 3-day treatment with atorvastatin 40 mg/d or placebo before surgery. The mechanisms by which atorvastatin modifies myocardial redox state were investigated in 26 RAA samples that were exposed to atorvastatin ex vivo. RESULTS: Atrial O(2)(-) (derived mainly from nicotinamide adenine dinucleotide phosphate [NADPH] oxidases) and ONOO(-) were independently associated with increased risk of atrial fibrillation, the need for post-operative inotropic support, and the length of hospital stay. Pre-operative atorvastatin treatment suppressed atrial NADPH oxidase activity and myocardial O(2)(-) and ONOO(-) production. Ex vivo incubation of RAA samples with atorvastatin induced a mevalonate-reversible and Rac1-mediated inhibition of NADPH oxidase. CONCLUSIONS: There is a strong independent association between myocardial O(2)(-)/ONOO(-) and in-hospital complications after cardiac surgery. Both myocardial O(2)(-) and ONOO(-) are reduced by pre-operative statin treatment, through a Rac1-mediated suppression of NADPH oxidase activity. These findings suggest that inhibition of myocardial NADPH oxidases may contribute to the beneficial effect of statins in patients undergoing cardiac surgery. (Effects of Atorvastatin on Endothelial Function, Vascular and Myocardial Redox State in High Cardiovascular Risk Patients; NCT01013103).

Induction of vascular GTP-cyclohydrolase I and endogenous tetrahydrobiopterin synthesis protect against inflammation-induced endothelial dysfunction in human atherosclerosis.

BACKGROUND: The endothelial nitric oxide synthase cofactor tetrahydrobiopterin (BH4) is essential for maintenance of enzymatic function. We hypothesized that induction of BH4 synthesis might be an endothelial defense mechanism against inflammation in vascular disease states. METHODS AND RESULTS: In Study 1, 20 healthy individuals were randomized to receive Salmonella typhi vaccine (a model of acute inflammation) or placebo in a double-blind study. Vaccination increased circulating BH4 and interleukin 6 and induced endothelial dysfunction (as evaluated by brachial artery flow-mediated dilation) after 8 hours. In Study 2, a functional haplotype (X haplotype) in the GCH1 gene, encoding GTP-cyclohydrolase I, the rate-limiting enzyme in biopterin biosynthesis, was associated with endothelial dysfunction in the presence of high-sensitivity C-reactive protein in 440 coronary artery disease patients. In Study 3, 10 patients with coronary artery disease homozygotes for the GCH1 X haplotype (XX) and 40 without the haplotype (OO) underwent S Typhi vaccination. XX patients were unable to increase plasma BH4 and had a greater reduction of flow-mediated dilation than OO patients. In Study 4, vessel segments from 19 patients undergoing coronary bypass surgery were incubated with or without cytokines (interleukin-6/tumor necrosis factor-α/lipopolysaccharide) for 24 hours. Cytokine stimulation upregulated GCH1 expression, increased vascular BH4, and improved vasorelaxation in response to acetylcholine, which was inhibited by the GTP-cyclohydrolase inhibitor 2,4-diamino-6-hydroxypyrimidine. CONCLUSIONS: The ability to increase vascular GCH1 expression and BH4 synthesis in response to inflammation preserves endothelial function in inflammatory states. These novel findings identify BH4 as a vascular defense mechanism against inflammation-induced endothelial dysfunction.

Rapid, direct effects of statin treatment on arterial redox state and nitric oxide bioavailability in human atherosclerosis via tetrahydrobiopterin-mediated endothelial nitric oxide synthase coupling.

BACKGROUND: Treatment with statins improves clinical outcome, but the exact mechanisms of pleiotropic statin effects on vascular function in human atherosclerosis remain unclear. We examined the direct effects of atorvastatin on tetrahydrobiopterin-mediated endothelial nitric oxide (NO) synthase coupling in patients with coronary artery disease. METHODS AND RESULTS: We first examined the association of statin treatment with vascular NO bioavailability and arterial superoxide (O(2)(·-)) in 492 patients undergoing coronary artery bypass graft surgery. Then, 42 statin-naïve patients undergoing elective coronary artery bypass graft surgery were randomized to atorvastatin 40 mg/d or placebo for 3 days before surgery to examine the impact of atorvastatin on endothelial function and O(2)(·-) generation in internal mammary arteries. Finally, segments of internal mammary arteries from 26 patients were used in ex vivo experiments to evaluate the statin-dependent mechanisms regulating the vascular redox state. Statin treatment was associated with improved vascular NO bioavailability and reduced O(2)(·-) generation in internal mammary arteries. Oral atorvastatin increased vascular tetrahydrobiopterin bioavailability and reduced basal and N-nitro-l-arginine methyl ester-inhibitable O(2)(·-) in internal mammary arteries independently of low-density lipoprotein lowering. In ex vivo experiments, atorvastatin rapidly improved vascular tetrahydrobiopterin bioavailability by upregulating GTP-cyclohydrolase I gene expression and activity, resulting in improved endothelial NO synthase coupling and reduced vascular O(2)(·-). These effects were reversed by mevalonate, indicating a direct effect of vascular hydroxymethylglutaryl-coenzyme A reductase inhibition. CONCLUSIONS: This study demonstrates for the first time in humans the direct effects of statin treatment on the vascular wall, supporting the notion that this effect is independent of low-density lipoprotein lowering. Atorvastatin directly improves vascular NO bioavailability and reduces vascular O(2)(·-) through tetrahydrobiopterin-mediated endothelial NO synthase coupling. These findings provide new insights into the mechanisms mediating the beneficial vascular effects of statins in humans. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01013103.

Role of asymmetrical dimethylarginine in inflammation-induced endothelial dysfunction in human atherosclerosis.

We explored the role of asymmetrical dimethylarginine (ADMA) as a cause of endothelial dysfunction induced by systemic inflammation. In vitro data suggest that ADMA bioavailability is regulated by proinflammatory stimuli, but it is unclear whether ADMA is a link between inflammation and endothelial dysfunction in humans. In study 1 we recruited 351 patients with coronary artery disease (CAD) and 87 healthy controls. In study 2 we recruited 69 CAD, 69 healthy, and 10 patients with rheumatoid arthritis, whereas in study 3, 22 healthy and 70 CAD subjects were randomly assigned to Salmonella typhii vaccination (n=11 healthy and n=60 CAD) or placebo (n=11 healthy and n=10 CAD). Circulating interleukin 6/ADMA and flow-mediated dilation (FMD) were measured at 0 and 8 hours. In study 1, ADMA was inversely correlated with FMD in healthy individuals and CAD patients (P<0.0001 for both). However, interleukin 6 was inversely correlated with FMD (P<0.0001) in healthy subjects but not in CAD patients. The positive correlation between ADMA and interleukin 6 was stronger in healthy (r=0.515; P<0.0001) compared with CAD (r=0.289; P=0.0001) subjects. In study 2, both patients with rheumatoid arthritis and CAD had higher interleukin 6 (P<0.0001) and ADMA (P=0.004) but lower FMD (P=0.001) versus healthy subjects. In study 3, vaccination increased interleukin 6 in healthy (P<0.001) and CAD (P<0.001) subjects. FMD was reduced in healthy subjects (P<0.05), but its reduction in CAD was borderline. Vaccination increased ADMA only in healthy subjects (P<0.001). Systemic, low-grade inflammation leads to increased ADMA that may induce endothelial dysfunction. This study demonstrated that ADMA may be a link between inflammation and endothelial dysfunction in humans.

Methionine-induced homocysteinemia impairs endothelial function in hypertensives: the role of asymmetrical dimethylarginine and antioxidant vitamins.

BACKGROUND: Nitric oxide synthase (NOS) inhibitor asymmetrical dimethylarginine (ADMA) is synthesized by the methylation of arginine as part of the methionine/homocysteine cycle. However, the mechanisms regulating ADMA synthesis in hypertension are unclear. METHODS: We investigated the role of ADMA and antioxidants in endothelial dysfunction during methionine-induced homocysteinemia in hypertensives. Thirty-nine hypertensives and forty-nine normotensive controls underwent methionine loading (100 mg methionine/kg BW), after being randomized to receive vitamin C (2 g) and E (800 IU) or placebo. Endothelium-dependent dilation (EDD) was evaluated by plethysmography (baseline and 4-h post-methionine loading (4-h PML)). RESULTS: Hypertensives had higher homocysteine at baseline (P < 0.001) and 4-h PML (P < 0.05), whereas methionine increased homocysteine in all groups. EDD was decreased in both vitamins and placebo groups in controls (P < 0.01 for both) and vitamins- and placebo-treated hypertensives (P < 0.05 and P < 0.01, respectively). In controls, ADMA was increased in both vitamin- and placebo groups (P < 0.01 for both) at 4-h PML. Hypertensives had higher ADMA at baseline (P < 0.01 vs. normotensive) and remained unchanged at 4-h PML (P = NS in placebo and vitamins treated). CONCLUSIONS: ADMA is elevated in hypertensives but remains unchanged after methionine loading, suggesting that ADMA plays an important role in endothelial dysfunction in hypertensives, but it is not responsible for homocysteine-induced endothelial dysfunction in these patients.

Young women partition fatty acids towards ketone body production rather than VLDL-TAG synthesis, compared with young men.

Before the menopause, women are relatively protected against CVD compared with men. The reasons for this sex difference are not completely understood, but hepatic fatty acid metabolism may play a role. The present study aimed to investigate the utilisation of plasma NEFA by the liver and to determine whether they are partitioned differently into ketone bodies and VLDL-TAG in healthy, lean young men and women. Volunteers were studied during a prolonged overnight fast (12-19 h) using an intravenous infusion of [U-¹³C]palmitate. After 12 h fasting, the women had a more advantageous metabolic profile with lower plasma glucose (P < 0·05) and TAG (P < 0·05) but higher plasma NEFA (P < 0·05) concentrations. Plasma 3-hydroxybutyrate (3-OHB) concentrations rose more in women than in men, and the transfer of ¹³C from [U-¹³C]palmitate to plasma [¹³C]3-OHB reached a plateau 6-7 h after the start of the infusion in women but was still increasing at 6 h in men. This implies a slower 3-OHB production rate and/or dilution by other precursor pools in men. In women, the high isotopic enrichment of plasma 3-OHB suggested that systemic plasma fatty acids were the major source of 3-OHB production. However, in men, this was not observed during the course of the study (P < 0·01). There were no sex differences for the incorporation of ¹³C into VLDL1- or VLDL2-TAG. The ability of young women to partition fatty acids towards ketone body production rather than VLDL-TAG may contribute to their more advantageous metabolic profile compared with young men.

Combined effects of atorvastatin and metformin on glucose-induced variations of inflammatory process in patients with diabetes mellitus.

BACKGROUND: Statin treatment improves survival in patients with atherosclerosis, but their effect on the glucose-induced variations of inflammatory markers, is unknown. We examined the effect of combined therapy with atorvastatin and metformin on glucose-induced variations of inflammatory molecules in patients with newly diagnosed diabetes mellitus type 2 (DM). METHODS: Thirty five subjects with newly diagnosed DM were randomized to receive metformin 850 mg/d (M, n=17) or metformin 850 mg/d+atorvastatin 10mg (n=18). All subjects underwent glucose loading (75 g oral glucose) at baseline and after 12 weeks of treatment. Blood samples were obtained at baseline and 3h post-loading, while serum tumor necrosis factor alpha (TNF-α) levels were determined at baseline and at 3h. RESULTS: Serum TNF-α remained unchanged in metformin at baseline (1.36±0.18 to 1.47±0.21 pg/ml p=NS) and after treatment (1.44±0.71 to 1.31±0.17 pg/ml, p=NS), while it was reduced in metformin+atorvastatin (2.3±0.3 to 2.0±0.4 pg/ml, p=NS at baseline and 1.80±0.2 to 1.65±0.2 pg/ml, p=0.03 after treatment). CONCLUSIONS: Interestingly, the combination of metformin and atorvastatin partly prevents the glucose-loading induced elevation of glucose levels (at 1 h), suggesting a better response to glucose intake than monotherapy with metformin. In addition, combined treatment with atorvastatin and metformin reduces the post-glucose loading levels of TNF-α compared to metformin monotherapy.

Novel methodology for the detection of exercise-induced myocardial wall motion abnormalities by surface electrocardiogram during exercise test.

BACKGROUND: We investigated whether ischemia-induced wall motion abnormalities during exercise test modify electrical vector variation. METHODS: We performed treadmill exercise test and thallium 201 scintigraphy in 150 normotensives. Beat-to-beat change of direction of S wave in V(1) (reference lead) was compared with that of R wave in V(5) and aVF, representative of anterior and inferior walls, respectively. The percentage of neighboring QRS couples where S wave in V(1) and R wave in V(5) or aVF change toward the same direction (increase or decrease) constitutes V1-V5 and V1-aVF indexes. RESULTS: V1-V5 and V1-aVF indexes were significantly decreased in subjects with reversible anterior or inferior ischemia, respectively. A decrease in V1-V5 index ≥0.14 defines those with anterior wall ischemia (sensitivity, 100%; specificity, 75.5%), whereas a decrease in V1-aVF index ≥0.05 defines those with inferior wall ischemia (sensitivity, 92.3%; specificity, 61.5%). CONCLUSIONS: These novel electrocardiographic exercise test indexes improved significantly their sensitivities.

Preoperative atorvastatin treatment in CABG patients rapidly improves vein graft redox state by inhibition of Rac1 and NADPH-oxidase activity.

BACKGROUND: Statins improve clinical outcome of patients with atherosclerosis, but their perioperative role in patients undergoing coronary artery bypass grafting (CABG) is unclear. We hypothesized that short-term treatment with atorvastatin before CABG would improve the redox state in saphenous vein grafts (SVGs), independently of low-density lipoprotein cholesterol (LDL)-lowering. METHODS AND RESULTS: In a randomized, double-blind controlled trial, 42 statin-naïve patients undergoing elective CABG received atorvastatin 40 mg/d or placebo for 3 days before surgery. Circulating inflammatory markers and malondialdehyde (MDA) were measured before and after treatment. SVG segments were used to determine vascular superoxide (O(2)(*-)) and Rac1 activation. For ex vivo studies, SVG segments from 24 patients were incubated for 6 hours with atorvastatin 0, 5, or 50 µmol/L. Oral atorvastatin reduced vascular basal and NADPH-stimulated O(2)(*-) in SVGs (P<0.05 for all versus placebo) and reduced plasma MDA (P<0.05), independently of LDL-lowering and of changes in inflammatory markers. In SVGs exposed to atorvastatin ex vivo, without exposure to LDL, basal and NADPH-stimulated O(2)(·-) were significantly reduced (P<0.01 for both concentrations versus 0 µmol/L) in association with a striking reduction in Rac1 activation and 1 membrane-bound Rac1 and p67(phox) subunit. The antioxidant effects of atorvastatin were reversed by mevalonate, implying a dependence on vascular HMG-CoA reductase inhibition. CONCLUSIONS: Short-term treatment with atorvastatin 40 mg/d before CABG improves redox state in SVGs, by inhibiting vascular Rac1-mediated activation of NADPH-oxidase. These novel findings suggest that statin therapy should be maintained or initiated in patients undergoing CABG, independently of LDL levels. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01013103.

Platelet activation in atherogenesis associated with low-grade inflammation.

Further to the established role of platelets in thrombosis and hemostasis, increasing evidence suggests that they also play a crucial role in atherogenesis. Platelets produce a number of agents contributing to the systemic low-grade inflammation implicated in atherogenesis. Platelet activation following inflammatory stimulus leads to the expression of surface receptors such as GPIb/IX/V, P-selectin, CD40, and to the release of several pro-inflammatory agents. Platelet receptors and released molecules play a critical role during the initiation and the progression of atherosclerosis by mediating leukocytes recruitment and adhesion to the vascular wall. Endothelial dysfunction, an early feature in atherosclerosis, is associated with low-grade inflammation within the vascular wall, and it leads to the reduced bioavailability of nitric oxide. Dysfunctional endothelium itself releases inflammatory molecules leading toward platelets activation and adhesion to the vascular wall. Platelets are no longer considered simply as cells participating in thrombosis. They are regulators of multiple processes in the human body, including inflammation, regulation of endothelial physiology and atherogenesis. The design of new therapeutic strategies targeting platelets and their impact in atherosclerosis-related low-grade inflammation are in the center of current cardiovascular research.

The activation of endothelin-1 pathway during methionine-induced homocysteinemia mediates endothelial dysfunction in hypertensive individuals.

OBJECTIVES: Endothelin-1 (ET-1) is a key regulator of arterial blood pressure in humans, and homocysteinemia is associated with increased oxidative stress. It is still unclear whether homocysteine-induced oxidative stress is implicated in the regulation of ET-1 expression. We examined the impact of acute homocysteinemia on endothelial function in hypertensive patients and healthy individuals, and the potential role of ET-1. METHODS: In this double-blind, placebo-controlled study, 39 hypertensive and 49 healthy individuals were randomized to receive high-dose vitamins (2 g vitamin C and 800IU vitamin E) or placebo followed by methionine loading 100 mg/kg body weight. Endothelium-dependent dilation (EDD) and endothelium-independent dilation (EID) of the brachial artery were evaluated by plethysmography, at baseline and 4 h postloading (4 h PML). ET-1 was measured by ELISA, whereas total lipid hydroperoxides (per-ox) levels were measured by a commercially available photometric technique. RESULTS: Acute, methionine-induced homocysteinemia decreased EDD in all study groups (P < 0.001 for all), whereas vitamins pretreatment failed to prevent this effect, despite the vitamins-induced reduction of peroxidation in the hypertensives group (P < 0.05). On the contrary, methionine loading significantly increased plasma ET-1 levels only in hypertensives (P < 0.05), an effect which was not prevented by antioxidant vitamins (P < 0.05). EID remained unchanged after methionine loading, in all study groups (P = NS for all groups). CONCLUSION: Experimental homocysteinemia rapidly blunts endothelial function in both hypertensive individuals and healthy individuals. The rapid elevation of ET-1 levels observed only in hypertensives, suggests that ET-1 may be the key mediator of homocysteine-induced endothelial dysfunction, independently of oxidative stress.

Moisture status of the skin of the feet assessed by the visual test neuropad correlates with foot ulceration in diabetes.

OBJECTIVE: To examine the association between the moisture status of the skin of the feet with foot ulceration in subjects with diabetes. RESEARCH DESIGN AND METHODS: A total of 379 subjects with diabetes were examined. Assessment of peripheral neuropathy was based on neuropathy symptom score, neuropathy disability score, vibration perception threshold, and the 10-g monofilament perception. The moisture status of the skin of the feet was assessed using the visual test Neuropad. RESULTS: Patients with foot ulceration had more severe peripheral neuropathy and more often an abnormal Neuropad response. Multivariate logistic regression analysis demonstrated that the odds of foot ulceration increased with measures of neuropathy but increased also with an abnormal Neuropad response. CONCLUSIONS: An abnormal Neuropad response correlates with foot ulceration in subjects with diabetes. This finding, if confirmed prospectively, suggests that the Neuropad test may be included in the screening tests for the prediction of foot ulceration.

Impact of 6 weeks of treatment with low-dose metformin and atorvastatin on glucose-induced changes of endothelial function in adults with newly diagnosed type 2 diabetes mellitus: A single-blind study.

BACKGROUND: Statin treatment has been reported to improve survival in patients with atherosclerosis, partly by improving vascular endothelial function. Elevation of blood glucose concentrations impairs endothelial function and promotes atherogenesis, but the effect of statins on glucose-induced endothelial dysfunction is unknown. Endothelium-dependent dilation (EDD) measured by gauge-strain plethysmography in the forearm is considered to be a reliable marker of endothelial function in forearm resistance vessels. OBJECTIVE: This study examined the combined effects of metformin and atorvastatin treatment on glucose-induced endothelial dysfunction (as EDD) in patients with newly diagnosed type 2 diabetes mellitus (DM). METHODS: Patients with newly diagnosed DM were recruited and were randomly assigned to receive metformin 850 mg/d or metformin 850 mg/d + atorvastatin 10 mg/d for 6 weeks in a single-blind study. All patients underwent glucose loading (75 g oral glucose after 12 hours of fasting) at baseline and at the end of the treatment period. Blood samples were obtained at baseline before glucose loading and 3 hours after loading to determine serum concentrations of cholesterol, lipoproteins, triglycerides, glucose, and glycosylated hemoglobin. EDD was evaluated at baseline and at 1, 2, and 3 hours after loading. The investigators were blinded to the treatment group assignments, and all analyses were performed in a blinded manner. Adverse events (eg, gastrointestinal disorders, myopathy, liver disorders) were monitored based on reported symptoms or signs (eg, myalgias, muscle cramps), clinical examination, and laboratory parameters (eg, increased liver and muscle enzymes). RESULTS: Thirty-two white patients with newly diagnosed type 2 DM were randomly assigned to receive metformin 850 mg/d (n = 17 [12 men]; mean [SD] age, 53.88 [45] years; body mass index [BMI], 28.7 [4.5] kg/m²) or metformin 850 mg/d + atorvastatin 10 mg/d (n = 15 [6 men]; mean age, 52.53 [37] years; BMI, 28.5 [2.1] kg/m²). At baseline, EDD was reduced 1 and 2 hours after glucose loading in both study groups (P < 0.01). Glucose loading was associated with an elevation of blood glucose concentrations at 1 and 2 hours (P < 0.01 vs resting levels before loading), and concentrations returned to resting levels at 3 hours, in both groups at baseline and after treatment. Metformin alone or in combination with atorvastatin was associated with a significant reduction in resting glucose concentrations after 6 weeks (both, P < 0.05 vs baseline), but only the combination of metformin + atorvastatin partly prevented the glucose-induced elevation of serum glucose at 1 hour after loading and the glucose-induced decrease in EDD (both, P < 0.01 vs baseline). CONCLUSIONS: Glucose loading blunted endothelial function, with a deterioration in EDD, in these patients with newly diagnosed type 2 DM. However, combined treatment with metformin and atorvastatin for 6 weeks partly prevented the glucose-induced impairment of EDD in these patients, with a significant difference compared with monotherapy with metformin.

Genetic polymorphism on type 2 receptor of angiotensin II, modifies cardiovascular risk and systemic inflammation in hypertensive males.

BACKGROUND: Angiotensin type 2 receptor (AT2R), plays a crucial role in blood pressure regulation and atherogenesis. AT2R gene is located on chromosome X and the biological effect of polymorphism A1675G in this gene needs to be further specified. We examined the impact of A1675G on the risk and the severity of coronary artery disease (CAD), and the expression of proatherogenic inflammatory molecules in hypertensive patients. METHODS: The study population consisted of 146 with CAD (102 with hypertension) and 266 age-matched individuals without CAD (114 with hypertension). The presence of A1675G polymorphism on AT2R gene was determined by PCR. Serum levels of C-reactive protein (CRP), fibrinogen, interleukin-6 (IL-6) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured in all the participants. RESULTS: The G allele was associated with decreased risk of CAD among hypertensives (odds ratio (OR) (95% confidence interval (CI))): 0.4 (0.2-0.9), P = 0.01) and less aggressive angiographic CAD (P < 0.001). The G allele was associated with lower IL-6 (median (25-75th percentile): 1.4 (0.6-3.8)), sVCAM-1 (621 (476-799)), CRP (1.2 (0.6-1.7)), and fibrinogen (369 (320-416)) vs. A allele (IL-6: 2.4 (1.1-4.5) P < 0.01, sVCAM-1: 702 (548-925) P < 0.05, CRP: 3.5 (2.0-6.1) P < 0.001, and fibrinogen: 407 (348-514) P < 0.01). The effect of A1675G on serum IL-6, sVCAM-1, and fibrinogen was driven by its effect among hypertensives (IL-6 3.1 (2.1-5.6 in A vs. 1.2 (0.3-3.4) in G P < 0.001, sVCAM-1: 890 (560-1000) in A vs. 556 (377-788) in G P < 0.01, and fibrinogen: 408 (354-510) in A vs. 369 (324-418) in G P < 0.001) whereas it had no effect among nonhypertensives. CONCLUSIONS: Genetic polymorphism A1675G on AT2R gene affects cardiovascular risk and the severity of atherosclerosis by modifying systemic inflammation, especially in hypertensive males.