Diabetes mellitus and associated hypertension, vascular disease, and nephropathy. An update

Glucose, insulin, and incident hypertension in the multi-ethnic study of atherosclerosis

Diabetes mellitus and hypertension commonly coexist, but the nature of this link is not well understood. The authors tested whether diabetes and higher concentrations of fasting serum glucose and insulin are associated with increased risk of developing incident hypertension in the community-based Multi-Ethnic Study of Atherosclerosis. At baseline, 3,513 participants were free of hypertension, defined as systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or use of antihypertensive medications to treat high blood pressure. Of these, 965 participants (27%) developed incident hypertension over 4.7 years' median follow-up between 2002 and 2007. Compared with participants with normal baseline fasting glucose, those with impaired fasting glucose and diabetes had adjusted relative risks of hypertension of 1.16 (95% confidence interval (CI): 0.96, 1.40) and 1.41 (95% CI: 1.17, 1.71), respectively (P = 0.0015). The adjusted relative risk of incident hypertension was 1.08 (95% CI: 1.04, 1.13) for each mmol/L higher glucose (P < 0.0001) and 1.15 (95% CI: 1.05, 1.25) for each doubling of insulin (P = 0.0016). Further adjustment for serum cystatin C, urinary albumin/creatinine ratio, and arterial elasticity measured by tonometry substantially reduced the magnitudes of these associations. In conclusion, diabetes and higher concentrations of glucose and insulin may contribute to the development of hypertension, in part through kidney disease and arterial stiffness.

Effect of type 2 diabetes on plasma kallikrein activity after physical exercise and its relationship to post-exercise hypotension

AIM

The present study was undertaken to determine the effects of type 2 diabetes (T2D) on plasma kallikrein activity (PKA) and postexercise hypotension (PEH).

METHODS

Ten T2D patients (age: 53.6±1.3 years; body mass index: 30.6±1.0kg/m(2); resting blood glucose: 157.8±40.2mgdL(-1)) and 10 non-diabetic (ND) volunteers (age: 47.5±1.0 years; body mass index: 28.3±0.9kg/m(2); resting blood glucose: 91.2±10.5mgdL(-1)) underwent two experimental sessions, consisting of 20min of rest plus 20min of exercise (EXE) at an intensity corresponding to 90% of their lactate threshold (90LT) and a non-exercise control (CON) session. Blood pressure (BP; Microlife BP 3AC1-1 monitor) and PKA were measured during rest and every 15min for 135min of the postexercise recovery period (RP).

RESULTS

During the RP, the ND individuals presented with PEH at 30, 45 and 120min (P<0.05) while, in the T2D patients, PEH was not observed at any time. PKA increased at 15min postexercise in the ND (P<0.05), but not in the T2D patients.

CONCLUSION

T2D individuals have a lower PKA response to exercise, which probably suppresses its hypotensive effect, thus reinforcing the possible role of PKA on PEH.

Gene therapy in diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease, whereby auto-reactive cytotoxic T cells target and destroy insulin-secreting β-cells in pancreatic islets leading to insulin deficiency and subsequent hyperglycemia. These individuals require multiple daily insulin injections every day of their life without which they will develop life-threatening diabetic ketoacidosis (DKA) and die. Gene therapy by viral vector and non-viral transduction may be useful techniques to treat T1D as it can be applied from many different angles; such as the suppression of autoreactive T cells to prevent islet destruction (prophylactic) or the replacement of the insulin gene (post-disease). The need for a better method for providing euglycemia arose from insufficient numbers of cadaver islets for transplantation and the immunosuppression required post-transplant. Ectopic expression of insulin or islet modification have been examined, but not perfected. This review examines the various gene transfer methods, gene therapy techniques used to date and promising novel techniques for the maintenance of euglycemia in the treatment of T1D.

Evidence-based approach for managing hypertension in type 2 diabetes

Blood pressure (BP) control is a critical part of managing patients with type 2 diabetes. Perhaps it is the single most important aspect of diabetes care, which unlike hyperglycemia and dyslipidemia can reduce both micro- and macrovascular complications. Hypertension is more prevalent in individuals with diabetes than general population, and in most cases its treatment requires two or more pharmacological agents (about 30% of individuals with diabetes need 3 or more medications to control BP). In this article we describe the key evidence that has contributed to our understanding that reduced BP translates into positive micro- and macrovascular outcomes. We review the data supporting current recommendation for BP target < 130/80 mmHg. Two studies suggest that a lower BP goal could be even more beneficial. We also present the comparative benefits of various antihypertensive drugs in reducing diabetes-related micro- and macrovascular complications. Finally we propose an evidence-based algorithm of how to initiate and titrate antihypertensive pharmacotherapy in affected individuals. Overall, achieving BP < 130/80 mmHg is more important than searching for the “best” antihypertensive agent in patients with diabetes.

Involvement of ERK1/2 kinase in insulin-and thrombin-stimulated vascular smooth muscle cell proliferation

It is well recognized that the proliferation of vascular smooth muscle cells (VSMCs) is a key event in the pathogenesis of various vascular diseases, including atherosclerosis and hypertension. We have previously shown that among extracellular signal-regulated protein kinases (ERKs), the 42- and 44-kDa isoforms (ERK1/2) participate in the cellular mitogenic machinery triggered by several VSMCs activators, including insulin (INS) and thrombin (Thr). However, understanding of the intracellular signal transduction pathways involved is incomplete. This review considers the recent findings in INS and Thr signaling mechanisms that modulate the proliferation of VSMCs with particular emphasis on the ERK1/2 signaling pathway, an important mediator of VSMCs hypertrophy and vascular disease. Moreover, because the ERK1/2 pathway have been acknowledged as an important mediator of VSMCs hypertrophy, ERK1/2 is identified as a key target for novel therapeutic interventions to minimize irreversible tissue damage associated with hypertension and atherosclerosis.

Central blood pressure and pulse wave velocity: relationship to target organ damage and cardiovascular morbidity-mortality in diabetic patients or metabolic syndrome. An observational prospective study. LOD-DIABETES study protocol

Background

Diabetic patients show an increased prevalence of non-dipping arterial pressure pattern, target organ damage and elevated arterial stiffness. These alterations are associated with increased cardiovascular risk.

The objectives of this study are the following: to evaluate the prognostic value of central arterial pressure and pulse wave velocity in relation to the incidence and outcome of target organ damage and the appearance of cardiovascular episodes (cardiovascular mortality, myocardial infarction, chest pain and stroke) in patients with type 2 diabetes mellitus or metabolic syndrome.

Methods/Design

Design: This is an observational prospective study with 5 years duration, of which the first year corresponds to patient inclusion and initial evaluation, and the remaining four years to follow-up.

Setting: The study will be carried out in the urban primary care setting.

Study population: Consecutive sampling will be used to include patients diagnosed with type 2 diabetes between 20-80 years of age. A total of 110 patients meeting all the inclusion criteria and none of the exclusion criteria will be included.

Measurements: Patient age and sex, family and personal history of cardiovascular disease, and cardiovascular risk factors. Height, weight, heart rate and abdominal circumference. Laboratory tests: hemoglobin, lipid profile, creatinine, microalbuminuria, glomerular filtration rate, blood glucose, glycosylated hemoglobin, blood insulin, fibrinogen and high sensitivity C-reactive protein. Clinical and 24-hour ambulatory (home) blood pressure monitoring and self-measured blood pressure. Common carotid artery ultrasound for the determination of mean carotid intima-media thickness. Electrocardiogram for assessing left ventricular hypertrophy. Ankle-brachial index. Retinal vascular study based on funduscopy with non-mydriatic retinography and evaluation of pulse wave morphology and pulse wave velocity using the SphygmoCor system. The medication used for diabetes, arterial hypertension and hyperlipidemia will be registered, together with antiplatelet drugs.

Discussion

The results of this study will help to know and quantify the prognostic value of central arterial pressure and pulse wave velocity in relation to the evolution of the subclinical target organ damage markers and the possible incidence of cardiovascular events in patients with type 2 diabetes mellitus.

Trial Registration

ClinicalTrials.gov Identifier: NCT01065155

Diabetes, vascular complications and antiplatelet therapy: open problems

Diabetes mellitus is commonly associated with both microvascular and macrovascular complications (coronary artery disease, cerebrovascular events, severe peripheral vascular disease, nephropathy and retinopathy). There is wide evidence demonstrating that platelet degranulation and synthesis of TxA2 are increased in diabetic patients. For this reason, many studies on anti-platelet therapy have been made to reduce thrombotic complication of diabetes mellitus. Some diabetic patients, although treated with ASA, have a high prevalence of recurrent thrombotic events, which may presumably be due to an "ASA resistance". Nevertheless, this drug remains the one with the greatest benefit. To optimize its function, we should try to understand the causes of "aspirin resistance", try to find the most suitable dosage, recommending patients to comply constantly with the prescription given and to avoid interactions with other drugs. "Clopidogrel resistance" is a term not clearly defined. The clinical implications of "clopidogrel resistance" are unknown. An important consideration affecting the use of aspirin in diabetic patients is its interaction with ACE-inhibitors. Another question is antiplatelet therapy in nephropathic diabetic patients. Although these patients are at high thrombotic and haemorrhagic risk, they should nevertheless be considered eligible to undergo antithrombotic therapy, taking into account the individual's haemorrhagic risk.

Insulin glargine reduces carotid intimal hyperplasia after balloon catheter injury in Zucker fatty rats possibly by reduction in oxidative stress

Diabetes and impaired glucose tolerance are associated with increased cardiovascular disease morbidity and mortality particularly after vascular injury. Since insulin is frequently used in such patients, the effect of glulisine (short acting) and glargine (long acting) were tested in Zucker fatty rat carotid artery subjected to balloon catheter injury. Insulin-resistant Zucker fatty rats were sc injected 0.45 mg/kg/d of glargine (once) or glulisine (twice) for 1 week before, and 3 weeks after balloon injury. Fasting and postprandial glucose was measured twice weekly. Injured and uninjured carotid arteries, liver, and aorta were harvested after 3 weeks of injury. Carotid sections were H&E stained for measuring intima/media ratio or immunostained for nitrotyrosine. Serum and aortic protein were analyzed for IGF-1 and 8-isoprostane, respectively. Carotid intima/media ratio was significantly reduced in the glargine group [0.9 +/- 0.1-control; 0.6 +/- 0.1-glulisine; 0.4 +/- 0.1-glargine, P < 0.05]. Serum IGF-1 levels were higher in both insulins, but significant only in glargine group [567 +/- 121 (ng/ml)-control; 1059 +/- 150 (ng/ml)-glargine; P < 0.05]. The aortic 8-isoprostane levels decreased significantly in the glargine group [(921 vs. 2566 pg/mg protein; P < 0.05]. Compared to control nitrotyrosine staining intensity was significantly lower in both groups of insulin-treated rats; the lowest level was in the glargine group. Insulin glargine attenuates carotid intimal hyperplasia in nondiabetic Zucker fatty rat independent of glucose levels and support a valuable function for insulin in vascular disease that merits additional investigations.

Safety and tolerability of duloxetine treatment of diabetic peripheral neuropathic pain between patients with and without cardiovascular conditions

BACKGROUND

Diabetic patients are predisposed to cardiovascular (CV) disease and other chronic medical conditions. We compared the safety of duloxetine in patients with (CV-positive) and without (CV-negative) historical/comorbid cardiovascular conditions at study entry.

METHODS

Data were pooled from three double-blind studies in which patients (age > or =18 years) with diabetic peripheral neuropathic pain (DPNP) were randomized to 12 weeks of duloxetine (DLX) 60 mg qd (n=344), 60 mg bid (n=341), or placebo (PBO, n=339). Safety assessments included discontinuation rates, spontaneously reported treatment-emergent adverse events (TEAEs), changes in vital signs, and changes in lab analytes.

RESULTS

Mean age of CV-positive patients (n=762) vs. CV-negative patients (n=262) was 61.1 vs. 56.1 years. The most common historical or comorbid CV conditions were hypertension, coronary artery disease, and myocardial infarction. Discontinuation due to adverse events was higher for DLX than for PBO in both CV-positive and CV-negative patients (13.5% DLX, 6.0% PBO, and 14.3% DLX, 3.4% PBO, respectively). Rates of CV-related TEAEs in CV-positive (8.4% DLX; 9.9% PBO) and CV-negative (8.6% DLX; 5.7% PBO) patients were similar (P>.1). Mean changes in blood pressure for each DLX dose vs. PBO between CV-positive and CV-negative patients were not statistically significant (P>.1), nor were sustained hypertension rates between CV-positive (2.4% DLX; 2.8% PBO) and CV-negative (2.9% DLX; 4.7% PBO) patients.

CONCLUSIONS

In this analysis, the safety of duloxetine in patients with DPNP was not found to be significantly different between patients with and without historical or comorbid CV conditions.

Improving microvascular outcomes in patients with diabetes through management of hypertension

Diabetes mellitus is an independent risk factor for cardiovascular disease (CVD) and current opinion holds that hyperglycemia directly damages smaller blood vessels, resulting in microvascular complications of nephropathy, retinopathy, and neuropathy. In a patient with diabetes, hypertension compounds and greatly increases the risk of microvascular complications, and thus the risk of end-stage kidney disease, vision loss, and nontraumatic limb amputations. Hypertension and hyperglycemia directly damage the microvasculature, leading to small vessel dysfunction that manifests as the clinical disease states of diabetic retinopathy and nephropathy. Early recognition and treatment of both hyperglycemia and hypertension may prevent vision loss and chronic kidney disease, the devastating outcomes of these microvascular complications. One of the pathogenic mechanisms for microvascular dysfunction is upregulation of the angiotensin II type 1 receptor, the most physiologically common receptor for the vasoconstrictor properties of angiotensin II. In patients with diabetic retinopathy and nephropathy, tight control of blood pressure (BP) (< 130/80 mm Hg) delays the progression of retinopathy and nephropathy in addition to reducing cardiovascular morbidity and mortality. Aggressive treatment with 2 or more antihypertensive agents, selected from different drug classes, is often needed to reach the optimal BP target level. A PubMed search was conducted to identify randomized controlled trials that evaluated hypertension control and microvascular outcomes in patients with diabetes. Several clinical trials have yielded promising data with renin-angiotensin-aldosterone system (RAAS) inhibitors (the direct renin inhibitor aliskiren, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers). Attainment of BP control with RAAS inhibitors reduces the risk for CVD, nephropathy, and retinopathy. In addition, RAAS inhibitors have demonstrated renoprotective effectiveness independent of the BP reduction achieved. This review will examine the results of clinical trials in the context of BP control, diabetes, and the microvascular complications of retinopathy and nephropathy.

Characteristics of patients with type 2 diabetes mellitus initiating insulin therapy: baseline data from the INSTIGATE study

OBJECTIVE

To describe the characteristics at baseline of patients with type 2 diabetes mellitus who are initiating insulin.

METHODS

Prospective, observational multi-centre, open-label study in five European countries of patients with type 2 diabetes who were initiating insulin as part of their usual care.

RESULTS

A total of 1172 patients were enrolled, with mean age 63.3 years and body mass index 29.9 kg/m(2). The majority (90%) of patients were taking one or more oral anti-diabetic agents; the percentage not taking anti-diabetic medication in the previous four weeks was highest in Germany (23.4%) and Spain (15.1%). The prevalence of microvascular diseases (range: 16.1%-36.1%) varied considerably between countries but for macrovascular (30.4%-38.6%) and other diabetes-related diagnoses (72.6%-76.6%) such as hypertension and dyslipidaemia the differences were less pronounced. In Germany, reported use of lipid-lowering (26.7%) and anti-platelet (27.1%) therapies was much less than in other countries (ranges: 53.2%-78.1% and 48.3%-61.1%, respectively). The majority of evaluable patients in each country had demonstrated poor control over a long period of time. Prior to initiating insulin, the most recent mean (+/-SD) HbA1(c) was 9.58 +/- 1.81%, fasting plasma glucose was 12.18 +/- 4.32 mmol/L and 78.5% had metabolic syndrome. IDF targets for HDL- and LDL-cholesterol, and blood pressure were met in 76.8%, 33.1% and 18.9% of patients, respectively.

CONCLUSIONS

Insulin treatment was only initiated after HbA1(c) values were considerably higher than recommended in treatment guidelines for a sustained period of time.

Administration of a substituted adamantyl urea inhibitor of soluble epoxide hydrolase protects the kidney from damage in hypertensive Goto-Kakizaki rats

Hypertension and Type 2 diabetes are co-morbid diseases that lead to the development of nephropathy. sEH (soluble epoxide hydrolase) inhibitors are reported to provide protection from renal injury. We hypothesized that the sEH inhibitor AUDA [12-(3-adamantan-1-yl-ureido)-dodecanoic acid] protects the kidney from the development of nephropathy associated with hypertension and Type 2 diabetes. Hypertension was induced in spontaneously diabetic GK (Goto-Kakizaki) rats using AngII (angiotensin II) and a high-salt diet. Hypertensive GK rats were treated for 2 weeks with either AUDA or its vehicle added to drinking water. MAP (mean arterial pressure) increased from 118+/-2 mmHg to 182+/-20 and 187+/-6 mmHg for vehicle and AUDA-treated hypertensive GK rats respectively. AUDA treatment did not alter blood glucose. Hypertension in GK rats resulted in a 17-fold increase in urinary albumin excretion, which was decreased with AUDA treatment. Renal histological evaluation determined that AUDA treatment decreased glomerular and tubular damage. In addition, AUDA treatment attenuated macrophage infiltration and inhibited urinary excretion of MCP-1 (monocyte chemoattractant protein-1) and kidney cortex MCP-1 gene expression. Taken together, these results provide evidence that sEH inhibition with AUDA attenuates the progression of renal damage associated with hypertension and Type 2 diabetes.

Proteomic Analysis of Vascular Endothelial Cells-Effects of Laminar Shear Stress and High Glucose

This study directly measured the relative protein levels in bovine aortic endothelial cells (BAEC) that were cultured for two weeks in normal (5 mM, NG) or high (22 mM, HG) glucose and then were subjected to laminar shear stress at 0 or 15 dynes/cm(2). Membrane preparations were labeled with one of the four isobaric tagging reagents (iTRAQ), followed by LC-MS/MS analysis. The results showed that HG and/or shear stress induced alterations in various membrane associated proteins involving many signaling pathways. While shear stress induced an increase in heat shock proteins and protein ubiquitination, which remained enhanced in HG, the effects of shear stress on the mechanosensing and protein phosphorylation pathways were altered by HG. These results were validated by Western blot analysis, suggesting that HG importantly modulates shear stress-mediated endothelial function.

Prevalence of type 2 diabetes among patients with hypertension under the care of 30 Italian clinics of hypertension: results of the (Iper)tensione and (dia)bete study

BACKGROUND AND PURPOSE

Hypertension is known to be highly prevalent among patients with diabetes and associated with an increased risk of cardiovascular damage. In contrast, relatively few investigations have addressed the prevalence of diabetes among patients with hypertension. The purpose of the present study was to examine the prevalence of type 2 diabetes, the effectiveness of hypertension and diabetes control and the association with other cardiovascular risk factors and previous cardiovascular diseases in a cohort of patients with hypertension referred to 30 hospital outpatient clinics for the treatment of hypertension.

METHODS AND PATIENTS

Patients were considered as having diabetes if they were already on an antidiabetic treatment either with diet or medications. All other patients had fasting plasma glucose measured on two separate occasions and were classified as having diabetes if both values were at least 140 mg/dl (7.8 mmol/l) and as not having diabetes if both values were less than 110 mg/dl (6.1 mmol/l). In patients with a single determination of at least 110 mg/dl, the final diagnosis of diabetes was established according to the result of an oral glucose tolerance test. A secondary definition of diabetes was also used, that is two fasting plasma glucose values of at least 126 mg/dl (7.0 mmol/l). In all patients, serum total, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol, fasting serum triglycerides, serum creatinine and urinary albumin were also evaluated.

RESULTS AND CONCLUSION

Among the 1397 recruited patients, 242 (17.3%) were diagnosed as having diabetes according to the primary definition and 244 (17.5%) according to the secondary definition. In 195 out of the 242 (14%), the diagnosis was already known whereas, in the remaining 47 (3.3%), it was made de novo. In 61.4% of those already having diabetes, plasma glucose was at least 140 mg/dl (7.8 mmol/l), whereas only in 8.4% of them was it less than 110 mg/dl (6.1 mmol/l). Patients with diabetes were older, heavier and with a greater familiar predisposition. Patients with diabetes had higher values of systolic blood pressure than individuals without diabetes (150 +/- 17 vs. 144 +/- 16 mmHg, respectively; P < 0.001), lower high-density lipoprotein cholesterol and higher triglycerides and microalbuminuria. Overall, among patients with hypertension and diabetes, only 3% had blood pressure and HbA1c within the recommended limits. The prevalence of previous cardiovascular disorders was two to three times higher than among individuals without diabetes.

High glucose increases the expression of Gq/11alpha and PLC-beta proteins and associated signaling in vascular smooth muscle cells

The levels and activity of protein kinase C and diacylglycerol were shown to be upregulated in diabetes/hyperglycemia; however, studies on the expression of upstream signaling molecules of phosphatidylinositol turnover were lacking. The present study was therefore undertaken to examine whether hyperglycemia/diabetes could also modulate the expression of Gqalpha and phospholipase C-beta (PLC-beta) proteins and associated phosphatidylinositol turnover signaling in aortic vascular smooth muscle cells (VSMCs) and A10 VSMCs exposed to high glucose. Aortic VSMCs from streptozotocin-diabetic rats exhibited an increased expression of Gqalpha and PLC-beta1 proteins (60% and 30%, respectively) compared with control cells as determined by Western blot analysis. The pretreatment of A10 VSMCs with high glucose (26 mM) for 3 days also augmented the levels of Gqalpha, G11alpha, PLC-beta1 and -beta2 proteins by about 50, 35, 30, and 30%, respectively, compared with control cells that were restored to control levels by endothelin-1 (ET-1), ET types A and B (ET(A) and ET(B)) receptors, and angiotensin II type 1 (AT1) receptor antagonists. In addition, ET-1-stimulated inositol triphosphate formation was also significantly higher in VSMCs exposed to high glucose, whereas the basal levels of inositol triphosphate were not different between the two groups. Furthermore, the treatment of A10 VSMCs with angiotensin II and ET-1 also significantly increased the levels of Gq/11alpha and PLC-beta proteins that were restored toward control levels by ET(A)/ET(B) and AT1 receptor antagonists. These results suggest that high glucose augments the expression of Gq/11alpha, PLC-beta, and mediated signaling in VSMCs, which may be attributed to AT1, ET(A), and ET(B) receptors.

Insulin therapy, hyperglycemia, and hypertension in type 1 diabetes mellitus

BACKGROUND

Diabetes mellitus and hypertension are closely linked, but the long-term blood pressure effects of glucose-lowering therapy and hyperglycemia are not clear.

METHODS

We examined the effects of intensive insulin therapy and hyperglycemia on the development of hypertension in the Diabetes Control and Complications Trial (DCCT) and its observational follow-up, the Epidemiology of Diabetes Intervention and Complications (EDIC) study. Incident hypertension was defined as 2 consecutive study visits with a systolic blood pressure of 140 mm Hg or higher, a diastolic blood pressure of 90 mm Hg or higher, or use of antihypertensive medications to treat high blood pressure.

RESULTS

Participants were enrolled from August 23, 1983, through June 30, 1989. During a 15.8-year median follow-up, 630 of 1441 participants developed hypertension. During the DCCT, the incidence of hypertension was similar comparing participants assigned to intensive vs conventional therapy. However, intensive therapy during the DCCT reduced the risk of incident hypertension by 24% during EDIC study follow-up (hazard ratio, 0.76; 95% confidence interval [CI], 0.64-0.92). A higher hemoglobin A(1c) level, measured at baseline or throughout follow-up, was associated with increased risk for incident hypertension (adjusted hazard ratios, 1.11 [95% CI, 1.06-1.17] and 1.25 [95% CI, 1.14-1.37], respectively, for each 1% higher hemoglobin A(1c) level), and glycemic control appeared to mediate the antihypertensive benefit of intensive therapy. Older age, male sex, family history of hypertension, greater baseline body mass index, weight gain, and greater albumin excretion rate were independently associated with increased risk of hypertension.

CONCLUSIONS

Hyperglycemia is a risk factor for incident hypertension in type 1 diabetes, and intensive insulin therapy reduces the long-term risk of developing hypertension.

Effect of pressure overload on cardioprotection of mitochondrial KATP channels and GSK-3beta: interaction with the MPT pore

BACKGROUND

The mitochondrial permeability transition (MPT) pore may serve as the end-effector of cardioprotective mechanisms, namely the mitochondrial K(ATP) channels and glycogen synthase kinase-3beta (GSK-3beta). We recently showed that augmented MPT pore induction contributes to pressure overload-induced exacerbation of infarct size. This study tests the hypotheses that (i) elevation in perfusion pressure attenuates cardioprotection associated with activation of mitochondrial KATP channels or inhibition of GSK-3beta and (ii) perfusion pressure modulates the regulation of the MPT pore by mitochondrial KATP channels and/or GSK-3beta.

METHODS

Langendorff-perfused hearts were subjected to a regional ischemia-reperfusion insult at a perfusion pressure of either 80 or 160 cm H2O. The perfusion medium contained no drug, diazoxide (80 micromol/l; mitochondrial KATP channel opener), lithium chloride (LiCl, 1 mmol/l; nonselective inhibitor of GSK-3beta), SB-216763 (3 micromol/l; selective inhibitor of GSK-3beta), cyclosporine A (0.2 micromol/l; inhibitor of MPT pore induction), glibenclamide (50 micromol/l; inhibitor of KATP channels), and the combination of cyclosporine A and glibenclamide or the combination of glibenclamide and LiCl.

RESULTS

The increase in perfusion pressure in the absence of a drug caused larger infarcts, an effect associated with poorer recovery of function following ischemia reperfusion. Treatment with either diazoxide or cyclosporine A reduced infarct size at both perfusion pressures but in contrast to diazoxide, cyclosporine A was more protective at the higher pressure. On the other hand, LiCl and SB-216763 reduced infarct size at both pressures, with the effect more marked at the higher perfusion pressure. Glibenclamide did not affect infarct size but eliminated the cardioprotective effect of cyclosporine A while having no effect on LiCl-induced cardioprotection.

CONCLUSION

Perfusion pressure primarily affects GSK-3beta-mediated regulation of MPT pore formation in the ischemic reperfused heart.

[Diabetes mellitus in hypertensive population attended in Primary Care in Spain. Blood pressure and lipid control rates]

OBJECTIVES AND METHODS

The aim of this study was to determine the blood pressure and LDL-cholesterol (LDL-c) control rates of hypertensive patients with diabetes mellitus attended in primary care setting in Spain, and to compare the data with those of the hypertensive population without diabetes. For this purpose, we analyzed the subset of diabetic patients of those included in the PRESCOT study (a cross-sectional survey of hypertensive subjects > 18 years attended in primary care). 12,954 patients (49.9% females; 62.1 +/- 10.7 years) were included in the PRESCOT study. Good controls were considered blood pressure < 130/80 mmHg (according to European Society of Hypertension-European Society of Cardiology [ESH-ESC] guidelines) and LDL-c < 100 mg/dl (National Cholesterol Education Program-Adult Treatment Panel III [NCEP-ATP III]).

RESULTS

Overall, 3868 (29.9%) of PRESCOT patients were diabetics (mean age 64.2 +/- 9.8 years; 47.5% males). Almost all the diabetic patients (98.5%) were taking some drug besides the antidiabetic treatment and 84.9% were taking at least 2 drugs. Although diabetic patients were treated with more antihypertensive medication than those without diabetes (48.75% vs 40.85% were on > 2 drugs, p < 0.001), blood pressure control was much lower in diabetics (6.3% vs 32.7%, p < 0.0001). In the same way, LDL-c control was also lower in these patients (12.0% vs 31.9%, p < 0.0001). Only 1.0% of diabetic hypertensives were well controlled for both risk factors (vs 11.9% of non-diabetics, p < 0.0001). Predictors of bad blood pressure control were sedentarism and presence of associated clinical conditions, and for lipid control the younger age, female gender, overweight, alcoholism and non-use of lipid-lowering agents.

CONCLUSIONS

The presence of diabetes in hypertensive population attended in Spanish primary health care is frequent. One out of every three hypertensives who attend the outpatient clinic daily is diabetic. Even though more drugs are prescribed in these patients, blood pressure and LDL-c control rates are significantly lower than in patients without diabetes. In the daily practice of primary care setting, almost no diabetic hypertensive subject is well controlled for blood pressure and LDL-c.

Alterations in myocardial metabolism in the diabetic myocardium

Free fatty acids are the preferred substrate for the myocardium. However, under conditions of ischemia, glucose becomes the primary myocardial energy source. Its metabolism avoids the toxic end-products of free fatty acids, which include oxygen free radicals. Patients with diabetes mellitus have impaired uptake of glucose. As a consequence the diabetic myocardium relies heavily on free fatty acid metabolism as its energy source. The results of these alterations in myocardial metabolism ultimately contribute to changes in endothelial function, inflammation, and oxidative stress. This review describes the defects in diabetic myocardial metabolism and how they contribute to cardiovascular dysfunction. The mechanisms by which intravenous insulin infusions can be used to modulate these changes in myocardial metabolism to improve clinical outcomes are discussed.

The endothelium and vascular inflammation in diabetes

The endothelium releases multiple mediators, not only regulators of vasomotor function but also important physiological and pathophysiological inflammatory mediators. Endothelial dysfunction is caused by chronic exposure to various stressors such as oxidative stress and modified low-density lipoprotein (LDL) cholesterol, resulting in impaired nitric oxide (NO) production and chronic inflammation. Biomechanical forces on the endothelium, including low shear stress from disturbed blood flow and hypertension, are also important causes of endothelial dysfunction. These processes seem to be augmented in patients with diabetes. In states of insulin resistance and in type 2 diabetes insulin signalling is impaired. Increased vascular inflammation, including enhanced expression of interleukin- 6 (IL-6), vascular cellular adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein (MCP- 1) are observed, as is a marked decrease in NO bioavailability. Furthermore, hyperglycaemia leads to increased formation of advanced glycation end products (AGE), which quench NO and impair endothelial function. In summary, during the development of diabetes a number of biochemical and mechanical factors converge on the endothelium, resulting in endothelial dysfunction and vascular inflammation. In the presence of insulin resistance, these processes are potentiated and they provide a basis for the macrovascular disease seen in diabetes.

Angiotensin II and endothelin-1 augment the vascular complications of diabetes via JAK2 activation

The JAK/STAT pathway is activated in vitro by angiotensin II (ANG II) and endothelin-1 (ET-1), which are implicated in the development of diabetic complications. We hypothesized that ANG II and ET-1 activate the JAK/STAT pathway in vivo to participate in the development of diabetic vascular complications. Using male Sprague-Dawley rats, we performed a time course study [days 7, 14, and 28 after streptozotocin (STZ) injection] to determine changes in phosphorylation of JAK2, STAT1, and STAT3 in thoracic aorta using standard Western blot techniques. On day 7 there was no change in phosphorylation of JAK2, STAT1, and STAT3. Phosphorylation of JAK2, STAT1, and STAT3 was significantly increased on days 14 and 28 and was inhibited by treatment with candesartan (AT(1) receptor antagonist, 10 mg x kg(-1) x day(-1) orally in drinking water), atrasentan (ET(A) receptor antagonist, 10 mg x kg(-1) x day(-1) orally in drinking water), and AG-490 (JAK2 inhibitor, 5 mg x kg(-1) x day(-1) intraperitoneally). On day 28, treatment with all inhibitors prevented the significant increase in systolic blood pressure (SBP; tail cuff) of STZ-induced diabetic rats (SBP: 157 +/- 9.0, 130 +/- 3.3, 128 +/- 6.8, and 131 +/- 10.4 mmHg in STZ, STZ-candesartan, STZ-atrasentan, and STZ-AG-490 rats, respectively). In isolated tissue bath studies, diabetic rats displayed impaired endothelium-dependent relaxation in aorta (maximal relaxation: 95.3 +/- 3.0, 92.6 +/- 7.4, 76.9 +/- 12.1, and 38.3 +/- 13.1% in sham, sham + AG-490, STZ + AG-490, and STZ rats, respectively). Treatment of rats with AG-490 restored endothelium-dependent relaxation in aorta from diabetic rats at 14 and 28 days of treatment. These results demonstrate that JAK2 activation in vivo participates in the development of vascular complications associated with STZ-induced diabetes.

Diabetes and Hypertension: Epidemiology of the Relationship and Pathophysiology of Factors Associated With These Comorbid Conditions

Diabetes and hypertension frequently coexist, leading to additive increases in the risk of life-threatening cardiovascular events. Hypertension is a common comorbid condition in patients with type 1 or type 2 diabetes when compared with the general population and occurs in 75% of patients with the more prevalent form of diabetes, type 2. Arterial blood pressure plays an important role in the development of renal damage and presents a complex relationship. It is well-known that hypertension accelerates the course of microvascular and macrovascular complications of diabetes and that hypertension often precedes type 2 diabetes and vice versa. Patients with type 1 and 2 diabetes and nephropathy frequently have circadian changes in blood pressure that correlate to nephropathy risk. Early detection of nocturnal hypertension and early intervention with angiotensin blockade may delay progression of diabetic nephropathy.

A pilot study of open label sesame oil in hypertensive diabetics

The objective of this study was to investigate the effect of sesame oil in hypertensive diabetics medicated with atenolol (beta-blocker) and glibenclamide (sulfonylurea). This open label trial with two intervention periods comprised 22 male and 18 female patients, 45-65 years old, with mild to moderate hypertension and diabetes. Sesame oil (Idhayam Gingelly oil, V.V.V. & Sons, Virudhunagar, Tamilnadu, India) was supplied to the patients, who were instructed to use it in place of other cooking oils for 45 days. Blood pressure (BP), anthropometric measurements, plasma glucose, glycated hemoglobin (HbA1c), lipid profiles [total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol, and triglycerides (TG)], lipid peroxidation [thiobarbituric acid-reactive substances (TBARS)], electrolytes (sodium, potassium, and chloride), and enzymic (superoxide dismutase, glutathione peroxidase, and catalase) and nonenzymic (vitamin C, vitamin E, beta-carotene, and reduced glutathione) antioxidants were measured at baseline and after 45 days of sesame oil substitution. The same patients were then switched over to other oils like palm or groundnut oils as their regular oils at random for another 45 days, and the investigations were carried out again at the end. Systolic and diastolic BP decreased remarkably. When oil substitution was withdrawn, BP values rose again. Body weight, body mass index, girth of waist, girth of hip, and waist:hip ratio were reduced upon substitution of sesame oil. Plasma glucose, HbA1c, TC, LDL-C, and TG were decreased. TBARS level was reduced, while the activities of enzymic and the levels of nonenzymic antioxidants were increased. Plasma sodium levels were reduced, while potassium levels were elevated. These results indicate that substitution of sesame oil as the sole edible oil has an additive effect in further lowering BP and plasma glucose in hypertensive diabetics.

Augmentation of insulin-stimulated ANP release through tyrosine kinase and PI 3-kinase in diabetic rats

The aim of present study was to define the effects of insulin on atrial dynamics and ANP release and its modification in diabetic rats. An isolated perfused beating atrial model was used from control and diabetic rats. Insulin was perfused with and without an inhibitor for tyrosine kinase or phosphatidylinositol 3-kinase (PI 3-kinase). Insulin increased the release of ANP and decreased atrial contractility in a dose-dependent manner. During the perfusion of 10(-10)M insulin, the release of ANP abruptly increased within 8min by approximately 40% and then decreased with time despite of continuous perfusion. In terms of increasing the dose of insulin, the time to reach the peak effect became faster and the slope to decrease became slower. In contrast, atrial contractility was gradually decreased with time. These effects were independent upon extracellular glucose. Genistein (10(-5)M) or lavendustin C (10(-5)M), a tyrosine kinase inhibitor, attenuated the release of ANP stimulated by insulin (10(-8)M). Wortmannin (10(-7)M) or LY294002 (10(-5)M), a PI 3-kinase inhibitor, also attenuated insulin-stimulated ANP release. However, both inhibitors for PI 3-kinase and tyrosine kinase did not cause any significant effects on negative inotropism by insulin. Insulin-stimulated ANP release was augmented in streptozotocin-treated rat atria. The density of insulin receptor markedly increased in diabetic hearts. These results suggest that insulin stimulates the release of ANP through PI 3-kinase and tyrosine kinase, and augmentation of insulin-stimulated ANP release in diabetic rat atria may be partly due to an upregulation of insulin receptor.

Stroke prevention in diabetes and obesity

Stroke is an important cause of morbidity and mortality, and is an economic burden. Diabetes and obesity are two important modifiable risk factors for stroke. Patients with diabetes have a higher incidence of stroke and a poorer prognosis after stroke. Risk-factor modification is the most important aspect of prevention of stroke in diabetes and obesity. This includes lifestyle modifications and different therapeutic modalities to control conditions, such as diabetes, hypertension, dyslipidemia and arrhythmia. Recent landmark studies have shown the beneficial effects of statins in diabetic patients even with close to normal or normal low-density lipoprotein cholesterol. Obesity, which is a risk factor for diabetes, hypertension and hyperlipidemia has been shown to be an independent risk factor for stroke. Increased leptin, dysregulation of adipocyte proteins, increased insulin resistance and C-reactive protein may be factors involved in the increased incidence of cardiovascular morbidity and mortality directly related to obesity. Visceral fat is a much bigger health risk than subcutaneous fat. Lifestyle interventions and pharmacotherapeutic agents have been used to manage obesity. In morbidly obese patients, surgical intervention seems to be the best method of treatment with a long-lasting favorable metabolic outcome. In the 21st Century, with the advanced medical knowledge and the therapeutic modalities available, it should be possible to reduce the incidence of stroke associated with diabetes and obesity.

Endothelial dysfunction and its role in diabetic vascular disease

When normal endothelial function is shifted to a pathological degree, the foundation is laid for possibly following diseases. This endothelial dysfunction is characterized by a proinflammatory state, reduced vasodilation, and a prothrombotic state. In the continuation this dysfunction is strongly associated cardiovascular morbidity and mortality. Endothelial dysfunction is markedly enhanced in type 2 diabetes providing a major pathophysiological cause for the massively increased cardiovascular risk of diabetic patients. Subsequently future therapeutic approaches for the treatment of diabetic cardiovascular disease should target the dysfunctional endothelium first.

Treatment of isolated systolic hypertension in diabetes mellitus type 2

Age-related arterial stiffness is more pronounced in diabetics compared to non-diabetics, which could explain the prevalence of isolated systolic hypertension (ISH, systolic blood pressure > or =140 mmHg and diastolic blood pressure <90 mmHg) being approximately twice that of the general population without diabetes. Large-scale interventional outcome trials have also shown that diabetics usually have higher pulse pressure and higher systolic blood pressure than non-diabetics. Advanced glycation end-product formation has been implicated in vascular and cardiac complications of diabetes including loss of arterial elasticity, suggesting possibilities for new therapeutic options. With increasing age, there is a shift to from diastolic to systolic blood pressure and pulse pressure as predictors of cardiovascular disease. This may affect drug treatment as different antihypertensive drugs may have differential effects on arterial stiffness that can be dissociated from their effects on blood pressure. While thiazide diuretics are associated with little or no change in arterial stiffness despite a robust antihypertensive effect, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers and calcium-channel blockers have been shown to reduce arterial stiffness. However, combination therapy is nearly always necessary to obtain adequate blood pressure control in diabetics. There are no randomized controlled trials looking specifically at treatment of ISH in diabetics. Recommendations regarding treatment of ISH in diabetes mellitus type 2 are based on extrapolation from studies in non-diabetics, post-hoc analyses and prespecified subgroup analysis in large-scale studies, and metaanalysis. These analyses have clearly demonstrated that blood pressure lowering in ISH confers improved prognosis and reduced cardiovascular and renal outcomes in both diabetics and non-diabetics.

Eicosanoids and renal vascular function in diseases

Arachidonic acid metabolites are vital for the proper control of renal haemodynamics and, when not properly controlled, can contribute to renal vascular injury and end-stage renal disease. Three major enzymatic pathways, COX (cyclo-oxygenase), CYP450 (cytochrome P450) and LOX (lipoxygenase), are responsible for the metabolism of arachidonic acid metabolites to bioactive eicosanoids. These eicosanoids can dilate or constrict the renal vasculature and maintain vascular resistance in the face of changing vasoactive hormones. Renal vascular generation of eicosanoids is altered in pathophysiological conditions such as hypertension, diabetes, metabolic syndrome and acute renal failure. Experimental evidence supports the concept that altered eicosanoid metabolism contributes to renal haemodynamic alterations and the development and progression of nephropathy. The possible beneficial renal vascular actions of enzymatic inhibitors, eicosanoid analogues and receptor antagonists have been examined in hypertension, diabetes and metabolic syndrome. This review highlights the roles of renal vascular eicosanoids in the pathogenesis of nephropathy and therapeutic targets for renal disease related to hypertension, diabetes, metabolic syndrome and acute renal failure.

Managing hypertension in high-risk patients: lessons and promises from the STRATHE and ADVANCE trials

Pharmacological treatment of hypertension represents a cost-effective way of preventing cardiovascular and renal complications. To benefit maximally from antihypertensive treatment, blood pressure should be brought to below 140/90 mmHg in every hypertensive patient, and even lower (< 130/80 mmHg) if diabetes or renal disease co-exists. Such targets cannot usually be reached using monotherapies. This is especially true in patients who present with a high cardiovascular risk. The co-administration of two agents acting by different mechanisms considerably increases the blood pressure control rate. Such combinations are not only efficacious, but are also well tolerated, and some fixed low-dose combinations even have a placebo-like tolerability. This is the case for the preparation containing the angiotensin-converting enzyme inhibitor perindopril (2 mg) and the diuretic indapamide (0.625 mg), a fixed low-dose combination that has been shown in controlled trials to be more effective than monotherapies in reducing albuminuria, regressing cardiac hypertrophy and improving the stiffness of large arteries. Using this combination to initiate antihypertensive therapy has been shown in a double-blind trial (Strategies of Treatment in Hypertension: Evaluation; STRATHE) to normalize blood pressure (< 140/90 mmHg) in significantly more patients (62%) than a sequential monotherapy approach based on atenolol, losartan and amlodipine (49%) and a stepped-care strategy based on valsartan and hydrochlorothiazide (47%), with no difference between the three arm groups in terms of tolerability. An ongoing randomized trial (Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; ADVANCE) is a study with a 2 x 2 factorial design assessing the effects of the fixed-dose perindopril-indapamide combination and of the intensive gliclazide modified release-based glucose control regimen in type 2 diabetic patients, with or without hypertension. A total of 11 140 patients were randomly selected. Within the first 6 weeks of treatment (run-in phase), the perindopril-indapamide combination lowered blood pressure from 145/81 +/- 22/11 mmHg (mean +/- SD) to 137/78 +/- 20/10 mmHg. Fixed-dose combinations are becoming more and more popular for the management of hypertension, and are even proposed by hypertension guidelines as a first-line option to treat hypertensive patients.

Role of the JAK/STAT signaling pathway in diabetic nephropathy

Excessive cellular growth is a major contributor to pathological changes associated with diabetic nephropathy. In particular, high glucose-induced growth of glomerular mesangial cells is a characteristic feature of diabetes-induced renal complications. Glomerular mesangial cells respond to traditional growth factors, although in diabetes this occurs in the context of an environment enriched in both circulating vasoactive mediators and high glucose. For example, the vasoactive peptide ANG II has been implicated in the pathogenesis of diabetic renal disease, and recent findings suggest that high glucose and ANG II activate intracellular signaling processes, including the polyol pathway and generation of reactive oxygen species. These pathways activate the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling cascades in glomerular mesangial cells. Activation of the JAK/STAT signaling cascade can stimulate excessive proliferation and growth of glomerular mesangial cells, contributing to diabetic nephropathy. This review focuses on some of the key elements in the diabetic microenvironment, especially high glucose and the accumulation of advanced glycoxidation end products and considers their impact on ANG II and other vasoactive peptide-mediated signaling events in vitro and in vivo.

High glucose enhances inducible nitric oxide synthase expression. Role of protein kinase C-betaII

The aim was to determine whether high glucose levels interfere with nitric oxide (NO) production and inducible NO synthase (iNOS) protein expression in interleukin-1beta-stimulated vascular smooth muscle cells from normotensive Wistar Kyoto and spontaneously hypertensive rats. Cells were incubated with either normal (5.5 mM) or high (22 mM) d-glucose for 72 h and with interleukin-1beta (10 ng/ml) for the last 24 h. High glucose increased nitrite levels, iNOS expression and protein kinase C activity in cells from normotensive rats and had no effect in cells from hypertensive rats. High glucose effects on nitrite production and iNOS expression was abolished by the selective inhibitor for the protein kinase C-betaII, 5,21:12,17-dimetheno-18H-dibenzo[i,o]pyrrolo[3,4-1] [1,8]diacyclohexadecine-18,20 (19H)-dione, 8-[(dimethylamino) methyl]-6,7,8,9,10,11-hexahydro-monomethanesulfonate (LY379196, 30 nM). Calphostin C (1 microM) and LY379196 (10 microM) reduced nitrite levels and iNOS expression only in cells from normotensive rats treated with both media. These results suggest that high glucose increases inducible nitric oxide synthase induction and subsequent NO production by activating the protein kinase C-betaII; this mechanism seems to be altered in hypertension.

Basal production of nitric oxide (NO) and non-NO vasodilators in the forearm microcirculation in Type 2 diabetes: associations with blood pressure and HDL cholesterol

We examined basal forearm microcirculatory blood flow (FBF) using venous occlusive strain-gauge plethysmography in 47 middle-aged men and women [55+/-1 years] with Type 2 diabetes and 15 age-matched healthy individuals [52+/-3 years], all receiving aspirin. Blood flow was also measured following infusion of N(G)-monomethyl-L-arginine into the brachial artery to inhibit basal NO release (FBF+L-NMMA). Acetylcholine (ACh) and sodium nitroprusside (SNP) were administered to assess endothelium-dependent and endothelium-independent functions. Compared with controls, diabetic subjects had significantly lower vasodilatory responses to ACh and SNP (p<0.05 for each). Basal FBF and FBF+L-NMMA were increased in diabetic subjects compared with controls (2.4+/-0.2 ml/100ml/min versus 1.7+/-0.2 ml/100ml/min, p=0.02 and 1.9+/-0.1 ml/100ml/min versus 1.2+0.1 ml/100ml/min, p=0.01, respectively) whereas the change in FBF following L-NMMA was greater in the controls (-27% versus -19%, p=0.05). Amongst the diabetic subjects, pulse pressure and HDL cholesterol were independent predictors of FBF (b=0.04+/-0.01, adjusted r2=0.21 and p=0.001, and b=3.3+/-1.2, adjusted r2=0.12 and p=0.007, respectively) and FBF+L-NMMA (b=0.03+/-0.01, adjusted r2=0.20, p=0.002 and b=2.1+/-0.9, adjusted r2=0.09 and p=0.02, respectively). Diastolic blood pressure predicted the change in FBF with L-NMMA (b=-1.02+/-0.32, adjusted r2=0.20 and p=0.003). Our findings suggest that well controlled T2DM patients have impaired agonist-mediated vasodilatation of the forearm resistance arteries that is associated with impaired basal release of nitric oxide but an increase in the release of non-NO vasodilators. The latter may be a compensatory response to increased arterial stiffness and may be facilitated by an effect of HDL.

Melatonin restores endothelium-dependent relaxation in aortic rings of pancreatectomized rats

In rats turned hyperglycemic by a subtotal pancreatectomy, a decreased relaxation response of aortic rings to acetylcholine (ACh) was found; this effect was amplified by preincubation in a high glucose medium (44 mmol/L). The relaxation response to ACh did not occur in endothelium-denuded rings or after the aortic rings were exposed to l-nitro-arginine methyl ester [L-NAME, a nitric oxide (NO) synthase inhibitor]. Incubation with the NO donor sodium nitroprusside (SNP) restored the impaired relaxation response seen in endothelium-denuded or L-NAME-treated aortic rings. Pancreatectomy decreased the vasorelaxation of aortic rings caused by SNP. Only in pancreatectomized rats, incubation in a high glucose medium impaired the relaxation effect of SNP. To assess whether melatonin preincubation reversed the impaired relaxation response to ACh (intact endothelium aortic rings) or to SNP (endothelium-denuded or L-NAME-treated rings) in hyperglycemic rats, cumulative dose-response curves were performed in the presence of 10(-5) mol/L melatonin. Melatonin preincubation did not modify ACh-induced relaxation of aortic rings in a normal glucose concentration but was highly effective in preventing the impairment of relaxation caused by a high glucose solution. Melatonin was also effective in restoring the impaired SNP-induced vasorelaxation seen in endothelium-denuded or L-NAME-treated aortic rings from hyperglycemic rats. The results further support the improvement by melatonin of the endothelial-mediated relaxation in blood vessels of diabetic rats.

Effect of diabetes on aortic nitric oxide synthesis in spontaneously hypertensive rats; does captopril modulate this effect?

Nitric oxide (NO) is a potent regulator in the cardiovascular system; it is generated by the nitric oxide synthase (NOS) family of proteins. NO produced in endothelial cells plays a crucial role in vascular functions. The aim of this study was to clarify the effect of diabetes on aortic NO synthesis in a model of genetic hypertension and determine whether captopril modulates this effect. Diabetes was induced in ten weeks old spontaneously hypertensive rats (SHR) by streptozotocin injection. The rats were allocated into 3 groups: control group 1, non-diabetic SHR; group 2, diabetic SHR; group 3, diabetic SHR group receiving captopril at 80 mg/kg in drinking water for 4 weeks. Mean blood pressure (MBP) was measured once a week by tail-cuff method. Aortic NO metabolities (nitrite/nitrate) and endothelial NOS (NOS-3) were assayed by Griess reaction and by immunoblotting and immunohistochemistry, respectively. There was a significant decrease in nitrite/nitrate (NOx) in aortas of diabetic SHR compared with controls. The decrease of aortic NOx in diabetic SHR was accompanied by a decrease in NOS-3 expression. Captopril treatment reduced MBP without affecting either NOx level or NOS-3 expression in aortas of diabetic SHR. We conclude that STZ-induced diabetes decreased NO in aortas of SHR that may reflect endothelial cell dysfunction; captopril administration decreased MBP without affecting NO level in aortas of diabetic SHR which suggest that the blood pressure-lowering effects of captopril were independent of NO.

Short-term oral ingestion of Ginkgo biloba extract (EGb 761) reduces malondialdehyde levels in washed platelets of type 2 diabetic subjects

We have recently reported that ingestion of Ginkgo biloba extract (EGb 761) (a) significantly reduced collagen-induced platelet aggregation and thromboxane B2 (TXB2) production in both non-diabetic individuals as well as those with type 2 diabetes mellitus (T2DM), (b) significantly reduced platelet malondialdehyde (MDA), an index of lipid peroxidation, in non-diabetic subjects. In the present study we report that ingestion of EGb 761 (120 mg daily for 3 months), significantly decreased platelet MDA-thiobarbituric acid reacting substances (TBARS) (41 +/- 9 pmol/10(7) platelets versus 30 +/- 11 pmol/10(7) platelets) (p < 0.005) in T2DM subjects with normal cholesterol levels (total cholesterol, 164 +/- 22 mg/dl; age, 54 +/- 9 years; BMI, 35.0 +/- 8.8 kg/m2, n = 12). In T2DM subjects with high cholesterol (total cholesterol, 218 +/- 15 mg/dl; age, 52 +/- 5 years; BMI, 36.2 +/- 6.6 kg/m2, n = 7), EGb 761 ingestion reduced the platelet TBARS from 29 +/- 9 to 22 +/- 9 pmol/10(7) platelets (p < 0.04). Because ingestion of EGb 761 did not alter platelet counts it is concluded that EGb 761, probably due to the flavonoid fraction, reduced the TBARS by inhibiting cyclooxygenase (COX)-1-mediated arachidonic acid oxygenation or by reducing the arachidonic acid pool. This is likely to lead to a reduction of platelet hyperactivity, a significant contributor to the development of cardiovascular disease in T2DM patients. Because of other reported beneficial properties of EGb 761, such as stimulation of pancreatic beta-cell function in T2DM subjects with pancreatic exhaustion, it appears that T2DM subjects might benefit from ingesting EGb 761 as a dietary supplement.

Increased blood pressure in the offspring of diabetic mothers

Studies were conducted in rats to determine the effect of maternal diabetes and the consequent hyperglycemia on cardiovascular function in the offspring. Diabetes was induced in pregnant Wistar rats through streptozotocin injection (50 mg/kg). Cardiovascular parameters were measured in 2-mo-old offspring animals of diabetic (OD, n=12) and control rats (OC, n=8). Arterial pressure (AP), heart rate (HR), baroreflex sensitivity, and vascular responsiveness to phenylephrine (PH) and sodium nitroprusside (SN) were measured. Angiotensin-converting enzyme (ACE) activity in heart, kidney, and lung was determined. OD rats exhibited increases in systolic AP (138+/-8 vs. 119+/-6 mmHg, OD vs. OC), with no change in HR (342+/-21 vs. 364+/-39 beats per minute (bpm), OD vs. OC). The reflex tachycardia elicited by SN was reduced in OD rats, as indicated by the slope of the linear regression (-2.2+/-0.4 vs. -3.6+/-0.8 bpm/mmHg, OD vs. OC). Vascular responsiveness to PH was increased 63% in OD rats compared with OC. OD rats showed increases in ACE activity in heart, kidney, and lung (1.13+/-0.24, 3.04+/-0.86, 40.8+/-8.9 vs. 0.73+/-0.19, 1.7+/-0.45, 28.1+/-6 nmol His-Leu.min-1 mg protein-1, OD vs. OC). Results suggest that diabetes during pregnancy affects cardiovascular function in offspring, seen as hypertension, baroreflex dysfunction, and activation of tissue renin-angiotensin system.

Impaired glucose metabolism in patients with heart failure: pathophysiology and possible treatment strategies

The firm association of diabetes mellitus with congestive heart failure (CHF) has been undoubtedly established. Recent reports support the presence of the reciprocal interrelationships between CHF and glucose abnormalities. The present review provides an overview of some aspects of the multifactorial interrelationships between heart failure and diabetes mellitus. Patients with heart failure are generally at higher risk of developing type 2 diabetes mellitus. Several factors may be involved, such as a lack of physical activity, hypermetabolic state, intracellular metabolic defects, poor muscle perfusion, and poor nutrition. Serum levels of inflammatory cytokines and leptin are elevated in patients with heart failure. Activation of the sympathetic system in CHF not only increases insulin resistance but also decreases the release of insulin from the pancreatic beta cells, increases hepatic glucose production by stimulating both gluconeogenesis and glycogenolysis, and increases glucagon production and lipolysis. People who develop type 2 diabetes mellitus usually pass through the phases of nuclear peroxisome proliferator-activated receptor modulation, insulin resistance, hyperinsulinemia, pancreatic beta-cell stress and damage leading to progressively decreasing insulin secretion, and impaired fasting and postprandial blood glucose levels. Once hyperglycemia ensues, the risk of metabolic and cardiovascular complications also increases. It is possible that the cornerstone of diabetes mellitus prevention in patients with CHF could be controlled by increased physical activity in a cardiac rehabilitation framework. Pharmacologic interventions by some medications (metformin, orlistat, ramipril and acarbose) can also effectively delay progression to type 2 diabetes mellitus in general high risk populations, but the magnitude of the benefit in patients with CHF is unknown. In patients with CHF and overt diabetes mellitus, ACE inhibitors may provide a special advantage and should be the first-line agent. Recent reports have suggested that angiotensin receptor antagonists (angiotensin receptor blockers), similar to ACE inhibitors, provide beneficial effects in patients with diabetes mellitus and should be the second-line agent if ACE inhibitors are contraindicated. Treatment with HMG-CoA reductase inhibitors should probably now be considered routinely for all diabetic patients with CHF, irrespective of their initial serum cholesterol levels, unless there is a contraindication.

Cardiovascular risk profile and blood pressure control in Italian hypertensive patients under specialist care

BACKGROUND

Information on the association between high hypertension and metabolic risk factors in Italy is limited. Furthermore, data on the rate of blood pressure control in the Italian hypertensive population are restricted to some Italian regions only, and refer usually to surveys performed, in most instances, several years ago.

METHODS

In the present study, a total of 4059 essential hypertensive patients were examined consecutively from March to June 2000 by 450 cardiovascular specialists (cardiologists, internists and diabetologists) operating throughout the Italian territory. Analysable data were obtained in 3812 patients.

RESULTS

Blood pressure control by treatment (< 140/90 mmHg) was infrequent (11.9%), this being particularly the case for systolic as compared to diastolic blood pressure (15.1 versus 33.7%). Hypertension was the only risk factor in only 13.7% of the patients, the association with diabetes, hypercholesterolaemia or obesity characterizing the remaining cases. About 60% of the patients fell into the high or very high cardiovascular risk category of the World Health Organization/International Society of Hypertension (WHO/ISH) Guidelines. Compared to low or moderate cardiovascular risk, multiple antihypertensive drug treatment was more frequently used in individuals at high or very high risk. These conditions were frequently underdiagnosed by physicians.

CONCLUSIONS

Thus, in Italy, hypertension continues to be a poorly controlled condition. Despite being a Mediterranean country, the occurrence of hypertension is commonly associated with metabolic risk factors and often with a high or very high cardiovascular risk profile. This is not properly identified by specialist physicians.

Cardiac dysfunction in the euglycemic diabetic-prone BB Wor rat

The purpose of this study was to examine cardiac function in the diabetic-prone BB Wor rat. The study involved 2 groups: diabetic resistant control littermates of BB rats and diabetic-prone BB rats that had yet to demonstrate overt signs of diabetes. Hearts from these animals were isolated and cardiac function examined in response to incremental increases in left atrial filling pressure. Hearts were also perfused at an increased aortic afterload resistance with buffer consisting of glucose alone or glucose in the presence of palmitate. Hearts from diabetic-prone rats exhibited depressed contractility and ventricular relaxation at high filling pressures. Ventricular function, expressed as cardiac output, was also depressed in diabetic-prone rats perfused at increased afterload resistance, but only in the presence of palmitate. Our results indicate that hearts from diabetic-prone BB Wor rats demonstrate abnormalities in contractile performance and thus may be a useful model for the study of cardiac function in the prediabetic state.

Mortality in patients with microvascular disease

Patients with chest pain/ischemic cardiac disease and normal coronary arteriography are thought to have a benign prognosis despite diminished quality of life. Many patients with hypertension fall into this group, at least in the early stage of their disease. Whether abnormalities in coronary flow reserve in these patients are associated with increased morbidity and mortality is unknown. One hundred sixty-eight patients with chest pain/ischemic cardiac disease and normal coronary angiograms who underwent invasive measures of coronary flow reserve were followed longitudinally. Mortality and quality of life were ascertained by query of the national death index and telephone administration of standardized questionnaires. Patient follow-up occurred at a mean of 8.5 years. In the abnormal coronary flow reserve group, 12 deaths (20%) were documented in 60 patients compared with eight out of 108 patients (7%; p=0.016) with normal coronary flow reserve. Coronary flow reserve did not predict impairment in functional health status in long-term follow-up. Thus, invasive measures of coronary flow reserve in patients with chest pain/ischemic cardiac disease and normal coronary angiograms predicted increased mortality. Surviving patients with chest pain/ischemic cardiac disease and normal coronary angiograms have significant morbidity.

Enhanced Platelet Activation in Patients with Atopic Eczema/Dermatitis Syndrome

Data gathered prove that circulating platelets are activated upon human allergic inflammation, partly as a result of direct IgE-mediated process. It has been indicated that platelets may contribute to pathogenesis of atopic eczema/dermatitis syndrome (AEDS). Authors of the recent study have investigated systemic platelet activation in patients with AEDS on the basis of blood level of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4), which are recognized markers of platelet activation, also belonging to C-X-C chemokine family. Plasma levels of beta-TG and PF4 were measured by enzyme-linked immunoassay (ELISA) in 18 AEDS patients with moderate disease activity and 23 healthy, nonatopic individuals. No differences in peripheral platelet count of the two groups were noted. Only four (33.3%) AEDS patients represented beta-TG and PF4 within the control range; plasma beta-TG and PF4 were significantly increased (p < 0.001) in the AEDS group compared as a whole with the control subjects. No association between circulating concentrations of beta-TG or PF4 and total IgE levels in AEDS patients was proved. The results suggest that some patients with AEDS may have enhanced blood platelet activity as expressed by beta-TG and PF4 level.