David Playford

Coenzyme Q10 improves endothelial dysfunction of the brachial artery in Type II diabetes mellitus

Abstract.Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of 40 patients with Type II diabetes and dyslipidaemia were randomized to receive 200 mg of coenzyme Q10 or placebo orally for 12 weeks. Endothelium-dependent and independent function of the brachial artery was measured as flow-mediated dilatation and glyceryl-trinitrate-mediated dilatation, respectively. A computerized system was used to quantitate vessel diameter changes before and after intervention. Arterial function was compared with 18 non-diabetic subjects. Oxidative stress was assessed by measuring plasma F2-isoprostane concentrations, and plasma antioxidant status by oxygen radical absorbance capacity. Results: The diabetic patients had impaired flow-mediated dilation [3.8 % (SEM 0.5) vs 6.4 % (SEM 1.0), p = 0.016], but preserved glyceryl-trinitrate-mediated dilation, of the brachial artery compared with non-diabetic subjects. Flow-mediated dilation of the brachial artery increased by 1.6 % (SEM 0.3) with coenzyme Q10 and decreased by –0.4 % (SEM 0.5) with placebo (p = 0.005); there were no group differences in the changes in pre-stimulatory arterial diameter, post-ischaemic hyperaemia or glyceryl-trinitrate-mediated dilation response. Coenzyme Q10 treatment resulted in a threefold increase in plasma coenzyme Q10 (p < 0.001) but did not alter plasma F2-isoprostanes, oxygen radical absorbance capacity, lipid concentrations, glycaemic control or blood pressure. Conclusion/interpretation: Coenzyme Q10 supplementation improves endothelial function of conduit arteries of the peripheral circulation in dyslipidaemic patients with Type II diabetes. The mechanism could involve increased endothelial release and/or activity of nitric oxide due to improvement in vascular oxidative stress, an effect that might not be reflected by changes in plasma F2-isoprostane concentrations. [Diabetologia (2002) 45: 420–426]

Dyslipoproteinaemia and hyperoxidative stress in the pathogenesis of endothelial dysfunction in non-insulin dependent diabetes mellitus: an hypothesis

Endothelial dysfunction in non-insulin dependent (Type 2) diabetes mellitus (NIDDM) has implications for the pathogenesis of the two major complications, macrovascular disease and microangiopathy. Endothelial dysfunction is a consequence of a disturbance in the L-arginine/nitric oxide pathway. Its occurrence in NIDDM is well supported by both in vitro and in vivo studies. NIDDM results in diverse abnormalities in lipoprotein metabolism, the most significant being hypertriglyceridaemia which is associated with increased plasma concentrations of small dense LDL and low levels of HDL. Dysglycaemia results in hyperoxidative stress and increased formation of advanced-glycosylation endproducts, both of which enhance the oxidative modification of lipoprotein particles. Based on extensive in vitro studies and on human data, we generate the hypothesis that the development of endothelial dysfunction in NIDDM is a consequence of the effect of dyslipoproteinaemia, in particular increased circulatory concentrations of modified small dense LDL and of hyperoxidative stress on the formation, action and disposal of nitric oxide, by diverse molecular mechanisms; HDL is proposed to have a protective effect on these processes through its enzymic antioxidant properties. The hypothesis proposed is simple, testable and consistent with wide sources of evidence. The practical implications of the hypothesis and the existing opportunities for the prevention and reversal of endothelial dysfunction in NIDDM are also reviewed and discussed.

Combined effect of coenzyme Q10 and fenofibrate on forearm microcirculatory function in type 2 diabetes

Arteriopathy is the principal complication of type 2 diabetes mellitus. It develops from endothelial dysfunction, which we have hypothesised occurs in diabetes primarily as a consequence of dyslipidaemia and oxidative stress. Fenofibrate and CoQ may improve endothelial function by regulating dyslipidaemia and oxidative stress, respectively. We therefore aimed to assess the independent and combined effects of fenofibrate and coenzyme Q(10) (CoQ) on endothelium-dependent and endothelium-independent vasodilator function of the forearm microcirculation in type 2 diabetes. Eighty dyslipidaemic type 2 diabetics were randomized to receive fenofibrate (200 mg/daily), CoQ (200 mg/daily), fenofibrate plus CoQ (200+200 mg daily), or placebo for 12 weeks. Forearm microcirculatory function was assessed with venous occlusion plethysmography during the infusion of acetylcholine (ACh), bradykinin (BK), sodium nitroprusside (SNP) and N(G)-monomethyl-L-arginine (L-NMMA) into the brachial artery. Blood flow responses were calculated as area under the curve (AUC). Fenofibrate significantly lowered plasma cholesterol, triglyceride and fibrinogen (P<0.001), and elevated HDL-cholesterol and homocysteine (P<0.001). CoQ did not change plasma isoprostanes, but significantly lowered systolic blood pressure and HbA(1c) (P<0.05). Fenofibrate plus CoQ significantly improved (P<0.05) the AUC for ACh, BK and SNP without significantly altering basal responses to L-NMMA. Fenofibrate or CoQ alone did not significantly alter blood flow responses. Improvements in blood flow were independent of changes in plasma lipids, blood pressure, homocysteine and isoprostanes, but were correlated (P=0.013) with HbA(1c). In conclusion, in this factorial trial we found that only the combination of fenofibrate and CoQ markedly improved endothelial and non-endothelial forearm vasodilator function in dyslipidemic type 2 diabetic patients. The favourable vascular effect of this therapeutic combination could be due to increase in the bioactivity of and/or responses to endothelium-derived relaxing factors, including nitric oxide, and this may entail synergistic stimulation of peroxisome proliferator-activated receptors.

Low-density lipoprotein size, high-density lipoprotein concentration, and endothelial dysfunction in non-insulin-dependent diabetes

We examined endothelial function (nitric‐oxide mediated) in 29 men with diet‐treated non‐insulin‐dependent (Type 2) diabetes mellitus (NIDDM) and 18 male age‐matched controls. Forearm blood flow was measured by venous occlusive plethysmography during intra‐arterial administration of acetylcholine (ACh, 7.5 and 15 μg min−1) and sodium nitroprusside (SNP, 3 and 10 μg min−1). LDL particle size was estimated by non‐denaturing gel electrophoresis. Serum lipids, blood pressure, and glycated haemoglobin were also measured. LDL particle size was smaller (p = 0.048) in the diabetic patients than controls. In the diabetic patients, LDL particle size was a significant positive predictor (p = 0.01) of the area under the dose–response curve for ACh, after adjusting for age, HbA1c, systolic BP, and cholesterol (R2 0.20). In stepwise regression including serum lipid and lipoprotein concentrations and LDL particle size, decreased HDL cholesterol was the best predictor of an impaired vasodilatory response to ACh. Vasodilatory responses to sodium nitroprusside were not significantly correlated with LDL particle size or serum lipid and lipoprotein concentrations. We conclude that in men with NIDDM, small, dense LDL particle size is associated with abnormal endogenous release of nitric oxide. The contribution of small, dense LDL particles to the development of endothelial dysfunction and early diabetic vasculopathy may not, however, be as great as decreased HDL cholesterol.

Effect of Fenofibrate on Brachial Artery Flow-Mediated Dilatation in Type 2 Diabetes Mellitus

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Oxidized LDL and small LDL particle size are independently predictive of a selective defect in microcirculatory endothelial function in type 2 diabetes

Aim:  To explore the associations of LDL (low‐density lipoprotein) particle size and oxidized LDL with endothelium‐dependent function of the forearm microcirculation in diabetes.

Management of Lipid Disorders in the Elderly

SummaryCardiovascular disease has been inseparable from aging in developed societies and, as a result, it is the commonest cause of mortality in elderly populations. Atherosclerosis is associated with the progressive vascular accumulation of cholesterol-laden lipoproteins, and is linearly associated with the plasma level of low density lipoprotein (LDL) cholesterol. Clinical trials in patients aged <65 years have conclusively shown that treatment of hypercholesterolaemia decreases the incidence of cardiovascular events and total mortality. However, few conclusive data are available regarding the treatment of hypercholesterolaemia in elderly patients. Extrapolation from clinical trials suggests that lipid lowering treatment in well selected elderly patients is effective in preventing cardiovascular events and is an efficient use of healthcare resources. In addition to cholesterol, high triglyceride and low high-density lipoprotein levels appear to be significant predictors of coronary artery disease in elderly patients.We do not advocate the indiscriminate screening of healthy elderly patients who have no other cardiovascular risk factors, because the marginal overall benefits are probably small and the costs of widespread screening and treatment high. On the other hand, chronological age itself cannot be considered a barrier to the screening and treatment of patients who have a good quality of life but have other cardiovascular risk factors and/or definite cardiovascular disease. Subgroup analysis of major clinical trials suggests that the aims of treatment should be to lower the LDL cholesterol level to 3.2 mmol/L ( 125 mg/dl), or the total cholesterol level to 5.2 mmol/L (200 mg/dl). Occasionally, multiple drug therapy is required to achieve this target, but statins (HMG-CoA reductase inhibitors) are the most commonly used first-line agents. With aggressive lowering of plasma lipid levels in this way, a reduction in clinical events is paralleled by regression of atheroma detectable by angiography, and an improvement in endothelial function.Global reduction of risk factors in elderly patients should always be undertaken, including dietary therapy, weight reduction in viscerally obese patients, postmenopausal estrogen replacement, smoking cessation, treatment of hypertension and control of diabetes mellitus. A secondary cause of dyslipidaemia should also be sought. The role of antioxidants is still not clear, but they are probably of little benefit in elderly patients.With the widespread use of effective, well tolerated treatments for lipid disorders in younger patients, significant improvements have already been attained in the morbidity and mortality associated with coronary artery disease. Since the current life expectancy at age 65 years is nearly 20 years in most Western countries, secondary prevention may increase the quality of life and the independent lifespan, even if eventual mortality is not delayed.

Intra-ureteric capsaicin in loin pain haematuria syndrome: efficacy and complications.

Objective  To evaluate the safety and efficacy of intra‐ureteric capsaicin for loin pain haematuria syndrome (LPHS).

A framework for bridging the gap in the care of familial hypercholesterolaemia in the community: pragmatic and economic perspectives

Objective:To analyze various business models for improving the diagnosis and treatment of familial hypercholesterolaemia. Methods:Five different strategies were analyzed and data were collected through documentary analysis and structured interviews. Interviewees included professionals from universities, Western Australia Department of Health, private medical practitioners and not-for-profit organizations. Results:Two business models are recommended: alliance with general practitioners and primary health care organizations and a joint venture model between private cardiology clinics and lipid disorder clinics in the public sector. Primary care providers are in a good position to co-ordinate across the multi-disciplinary health services required to treat familial hypercholesterolaemia within the population. Conclusions:Devolution of knowledge on treatment of familial hypercholesterolaemia from centralized specialist hospital clinics to primary care services is required to improve the rate of detection of this condition in the community. An International Classification of Disease (ICD)-10 and/or a Diagnosis-Related Group (DRG) code is required to codify, catalogue and document new cases and treatment, as well as to facilitate research and re-imbursement strategies. Primary Health Care Organizations can usefully facilitate the transfer of knowledge on best standard of care to general practice, but the best model of care will require close integration of care with specialist and academic centres.