Subclinical hypothyroidism (sHT) is associated with dyslipidemia and enhanced cardiovascular risk. We assessed carotid artery intima-media thickness (IMT, high-resolution ultrasonography) and lipoprotein profile in 45 sHT patients (aged 37 +/- 11 yr) at baseline and after 6 months of randomized, placebo-controlled L-T(4) replacement. In comparison with 32 age- and sex-matched controls, sHT patients had elevated total and low-density lipoprotein (LDL) cholesterol and ApoB levels (P = 0.002, P = 0.0007, and P = 0.01, respectively) and higher mean-IMT values (P < 0.0001). In stepwise regression analysis, mean-IMT was positively related (r(2) = 0.71, P < 0.0001) to age, TSH, and LDL cholesterol. L-T(4) replacement significantly reduced both total and LDL cholesterol (P < 0.0001 for both) and mean-IMT (by 11%, P < 0.0001). The decrement in IMT was directly related to the decrements of both total cholesterol and TSH (P = 0.02 and P = 0.0001, respectively). We conclude that early carotid artery wall alterations are present in sHT patients. Whether such IMT increase is related to an early atherosclerotic involvement of the arterial wall cannot be clearly decided on the basis of the present results. However, the fact that L-T(4) replacement therapy was able to improve both the atherogenic lipoprotein profile and intima-media thickening suggests that lipid infiltration of arterial wall may represent a major mechanism underlying IMT increase in subclinical hypothyroidism.

Our results are consistent with the hypothesis of a generalized remodelling of small arteries in the body, including the coronary circulation; this remodelling may play an important role in the reduction of coronary vasodilator capacity in patients with mild to moderate essential hypertension.

Aims/hypothesis Inhibitors of dipeptidyl peptidase-IV (DPP-IV), such as sitagliptin, increase glucagon-like peptide-1 (GLP-1) concentrations and are current treatment options for patients with type 2 diabetes mellitus. As patients with diabetes exhibit a high risk of developing severe atherosclerosis, we investigated the effect of sitagliptin on atherogenesis in Apoe −/− mice. Methods Apoe−/− mice were fed a high-fat diet and treated with either sitagliptin or placebo for 12 weeks. Plaque size and plaque composition were analysed using Oil Red O staining and immunohistochemistry. Furthermore, in vitro experiments with the modified Boyden chamber and with gelatine zymography were performed to analyse the effects of GLP-1 on isolated human monocyte migration and metalloproteinase-9 (MMP-9) release.Results Treatment of Apoe −/− mice with sitagliptin significantly reduced plaque macrophage infiltration (the aortic root and aortic arch both showing a 67% decrease; p<0.05) and plaque MMP-9 levels (aortic root showing a 69% and aortic arch a 58% reduction; both p<0.01) compared with controls. Moreover, sitagliptin significantly increased plaque collagen content more than twofold (aortic root showing an increase of 58% and aortic arch an increase of 73%; both p<0.05) compared with controls but did not change overall lesion size (8.1 ± 3.5% vs 5.1 ± 2.5% for sitagliptin vs controls; p0NS). In vitro, pretreatment of isolated human monocytes with GLP-1 significantly decreased cell migration induced by both monocyte chemotactic protein-1 and by the protein known as regulated on activation, normal T cell expressed and secreted (RANTES) in a concentration-dependent manner. Furthermore, GLP-1 significantly decreased MMP-9 release from isolated human monocyte-derived macrophages. Conclusions/interpretation Sitagliptin reduces plaque inflammation and increases plaque stability, potentially by GLP-1-mediated inhibition of chemokine-induced monocyte migration and macrophage MMP-9 release. The effects observed may provide potential mechanisms for how DPP-IV inhibitors could modulate vascular disease in high-risk patients with type 2 diabetes mellitus.

BACKGROUND: Metabolic syndrome, insulin resistance and diabetes are associated with an increased risk of cardiovascular disease. Niacin is known to increase insulin resistance, and have adverse effects on blood glucose levels, but to have beneficial effects on plasma lipids and lipoproteins. We therefore aimed to determine whether intensive lipid therapy with a niacin-containing regimen would have a beneficial effect on cardiovascular disease, despite an expected increase in plasma glucose and insulin resistance in subjects with the metabolic syndrome, insulin resistance or abnormal fasting plasma glucose levels. METHODS: The effect of three years' treatment with niacin plus simvastatin (N+S) on both angiographic and clinical outcomes were analyzed in the 160 subjects with coronary artery disease (CAD) and low levels of high density lipoproteins (HDL) from the HDL-Atherosclerosis Treatment Study (HATS). A subgroup analysis was performed on the basis of: (1) the presence or absence of the metabolic syndrome, (2) higher or lower insulin resistance, and (3) the presence or absence of impaired fasting glucose or diabetes (dysglycemia). Individuals classified as having the MS, increased insulin resistance or dysglycemia would be expected to have increased cardiovascular risk. RESULTS: N+S reduced the change in mean proximal percent stenosis (Δ%S) compared to placebo (PL) in subjects with the metabolic syndrome (Δ%Sprox 0.3 vs 3.0, p=0.003) and in the more insulin resistant group of subjects (Δ%Sprox 0.5 vs 2.7, p=0.001), while subjects with dysglycemia (impaired fasting glucose or diabetes) showed a lesser benefit (Δ%Sprox 1 vs 3.2, p=0.13). These changes occurred despite increased in-treatment fasting glucose levels (3%), fasting insulin (19%) and decreased insulin sensitivity (-10%). Overall primary clinical events were reduced by 60% with N+S compared to PL (p=0.02). A similar reduction of the rate of primary events was seen in patients with metabolic syndrome, insulin resistance, and to a lesser extent in patients with dysglycemia in the N+S group compared to PL. CONCLUSIONS: These data indicate that, in CAD patients with low HDL, treating the atherogenic dyslipidemia with a combination of N+S leads to substantial benefits in terms of stenosis progression and clinical events, independently of whether the patient has the metabolic syndrome or is insulin resistant. Over a 3 year period, the beneficial effect of niacin in combination with simvastatin appears to offset the modest adverse effect of niacin on glucose metabolism and insulin resistance in at higher risk patients, as long as careful attention is paid to glycemic control.

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Aims/hypothesis Hyperglycaemia and hyperinsulinaemia have opposite effects on endothelium-dependent vasodilatation in microcirculation, but the net effect elicited by glucose ingestion and the separate influence of glucose tolerance are unknown. Methods In participants with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) or diabetic glucose tolerance, multiple plasma markers of both oxidative stress and endothelial activation, and forearm vascular responses (plethysmography) to intra-arterial acetylcholine (ACh) and sodium nitroprusside (SNP) infusions were measured before and after glucose ingestion. In another IGT group, we evaluated the time-course of the skin vascular responses (laser Doppler) to ACh and SNP (by iontophoresis) 1, 2 and 3 h into the OGTT; the plasma glucose profile was then reproduced by means of a variable intravenous glucose infusion and the vascular measurements repeated. Results Following oral glucose, plasma antioxidants were reduced by 5% to 10% (p<0.01) in all patient groups. The response to acetylcholine was not affected by glucose ingestion in any group, while the response to SNP was attenuated, particularly in the IGT group. The ACh:SNP ratio was slightly improved therefore in all groups, even in diabetic participants, in whom it was impaired basally. A time-dependent improvement in ACh:SNP ratio was also observed in skin microcirculation following oral glucose; this improvement was blunted when matched hyperglycaemia was coupled with lower hyperinsulinaemia (intravenous glucose). Conclusions/interpretation Regardless of glucose tolerance, oral glucose does not impair endothelium-dependent vasodilatation either in resistance arteries or in the microcirculation, despite causing increased oxidative stress; the endogenous insulin response is probably responsible for countering any inhibitory effect on vascular function.

We present a versatile scenario to introduce students to statistics: the test that spaghetti sticks only if sufficiently done. The statistical analyses can be performed at different levels of complexity and formal correctness, adapting it to the students' age.