Myocardial alterations in diabetes and hypertension

Knockout of farnesoid X receptor aggravates process of diabetic cardiomyopathy

Previous studies have shown that FXR is involved in glycolipid metabolism, tissue inflammation and regeneration in organs such as the liver, intestines and kidneys. Although FXR has been reported in cardiac tissue, its function in diabetic cardiomyopathy has not been reported. Here, we successfully constructed a diabetic mouse model of FXR^-/- and evaluated the effects of FXR knockout on cardiac function in mice by measuring various indicators. We demonstrated that blood glucose levels in diabetic mice are significantly elevated in the case of FXR knockout. Our findings from cardiac ultrasound and tissue HE staining supported that FXR knockout aggravates diabetic cardiomyopathy. Masson staining of myocardial tissue and quantitative detection of α-SMA by qPCR suggest that FXR knockout exacerbates cardiac fibrosis in diabetic cardiomyopathy. Combined with the results of Oil Red staining and quantitative detection of triglycerides in fresh tissue blocks, we hypothesized that FXR knockout aggravates diabetes-induced cardiac lipid accumulation. Altogether our results revealed a role of the FXR in the diabetic cardiomyopathy, suggesting a possible novel target for the treatment of diabetic cardiomyopathy.

The effects of dipeptidyl peptidase-4 inhibition on microvascular diabetes complications

We performed a review of the literature to determine whether the dipeptidyl peptidase-4 inhibitors (DPP4-I) may have the capability to directly and positively influence diabetic microvascular complications. The literature was scanned to identify experimental and clinical evidence that DPP4-I can ameliorate diabetic microangiopathy. We retrieved articles published between 1 January 1980 and 1 March 2014 in English-language peer-reviewed journals using the following terms: ("diabetes" OR "diabetic") AND ("retinopathy" OR "retinal" OR "nephropathy" OR "renal" OR "albuminuria" OR "microalbuminuria" OR "neuropathy" OR "ulcer" OR "wound" OR "bone marrow"); ("dipeptidyl peptidase-4" OR "dipeptidyl peptidase-IV" OR "DPP-4" OR "DPP-IV"); and ("inhibition" OR "inhibitor"). Experimentally, DPP4-I appears to improve inflammation, endothelial function, blood pressure, lipid metabolism, and bone marrow function. Several experimental studies report direct potential beneficial effects of DPP4-I on all microvascular diabetes-related complications. These drugs have the ability to act either directly or indirectly via improved glucose control, GLP-1 bioavailability, and modifying nonincretin substrates. Although preliminary clinical data support that DPP4-I therapy can protect from microangiopathy, insufficient evidence is available to conclude that this class of drugs directly prevents or decreases microangiopathy in humans independently from improved glucose control. Experimental findings and preliminary clinical data suggest that DPP4-I, in addition to improving metabolic control, have the potential to interfere with the onset and progression of diabetic microangiopathy. Further evidence is needed to confirm these effects in patients with diabetes.

Metformin in Diabetic Patients with Heart Failure: Safe and Effective?

Management of diabetic patients with heart failure is a complex endeavor. The initial reluctance to use metformin in these patients has given way to a broader acceptance after clinical trials and meta-analyses have revealed that some of the insulin-sensitizing agents lead to adverse cardiovascular events. We have proposed that an increase of substrate uptake by the insulin-resistant heart is detrimental because the heart is already flooded with fuel. In light of this evidence, metformin offers a unique safety profile in the patient with diabetes and heart failure. Our article expands on the use of metformin in patients with heart failure. We propose that the drug targets both the source as well as the destination (in this case the heart) of excess fuel. We consider treatment of diabetic heart failure patients with metformin both safe and effective.

The limited clinical value of a specific diabetic cardiomyopathy

AIMS

Diabetic patients show a higher likelihood of developing heart failure (HF), independently of the atherosclerotic process, than their nondiabetic counterparts. This suggests the presence of an intrinsic vulnerability of the heart in patients with diabetes mellitus.

DATA SYNTHESIS

A cardiomyopathy specific to the diabetic patient was first hypothesized by Rubler and co-workers, in 1972 and recognized as a nosologic entity by the World Health Organization (WHO) in 1995. All patients falling under Rubler's definition had ascertained diabetic glomerusclerosis, but were unaffected by major coronary artery disease (CAD). Notably, the mean plasma glucose in those patients was 417 ± 209 mg/dl. Since then, several studies conducted in both animals and in humans have focused on pathogenetic mechanisms, clinical manifestations, diagnostic as well as therapeutic approaches utilized for the treatment of diabetic cardiomyopathy (DCM). Despite the large body of literature available, the clinical entity and significance of this diabetic complication continue to be elusive.

CONCLUSIONS

In the present report, recent pathophysiological findings and diagnostic strategies to treat DCM are reviewed. Particular attention is dedicated to the clinical manifestation of DCM, that is to heart failure (HF), and to the implications of co-morbidities and metabolic control on its evolution.

Chronic type 1 diabetes in spontaneously hypertensive rats leads to exacerbated cardiac fibrosis

INTRODUCTION

Diabetes in human subjects is often associated with hypertension. The aim of this study was to examine the development of cardiac fibrosis following induction of type 1 diabetes in genetically hypertensive rats.

METHODS

Diabetes was induced by streptozotocin (STZ) injection in 8-week-old normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) for a duration of 16 or 24 weeks. Aged-matched, nondiabetic WKY and SHRs were used as controls. At termination of treatment, the rats were anaesthetized, hearts arrested in diastole and perfusion fixed. A comprehensive examination of cardiac fibrosis throughout the right and left ventricles was undertaken in picrosirius red-stained sections, using image analysis and by undertaking collagen type I and type III immunohistochemistry.

RESULTS

Induction of diabetes in the SHRs led to a marked increase in the levels of interstitial fibrosis in the left ventricle plus septum (LV+S) at both 16 and 24 weeks duration (59% and 43% increase, respectively) and also in the right ventricle after 24 weeks duration of diabetes (35% increase compared to the nondiabetic SHR). Exacerbated perivascular fibrosis was also observed in the LV+S in the diabetic-hypertensive rats at the later time point. These effects of induction of diabetes were not observed in the normotensive strain.

CONCLUSIONS/INTERPRETATION

Our findings clearly demonstrate elevations in cardiac fibrosis when type 1 diabetes is combined with hypertension. Our findings thus stress the importance of closely monitoring both blood pressure and glucose levels in type 1 diabetic patients in order to prevent myocardial collagen deposition.

Association between diabetes mellitus and left ventricular hypertrophy in a multiethnic population

It is still controversial whether type 2 diabetes mellitus (T2DM) is associated with increased left ventricular (LV) mass independent of body size. We tested the hypothesis that T2DM is independently associated with LV mass in a multiethnic cohort. In the Northern Manhattan Study (NOMAS) cohort sample, a total of 1,932 subjects (67.9+/-9.6 years, 769 men and 1,163 women, 443 with DM and 1,489 without DM) were studied by transthoracic echocardiography, and LV mass was calculated. LV hypertrophy was defined as the upper quartile of LV mass. Multivariable models were used to assess the association of T2DM with LV mass after adjusting for age, gender, race, body mass index (BMI), systolic blood pressure, education, history of coronary artery disease, physical activity, and alcohol consumption. LV mass (189+/-60 vs 174+/-59 g, p<0.0001), BMI, and systolic blood pressure were higher in the DM group than in the non-DM group, whereas age and gender distributions were similar between groups. In multivariable analysis, T2DM was independently associated with increased LV mass (p=0.03). Presence of T2DM was associated with increased risk of LV hypertrophy (adjusted odds ratio 1.46, 95% confidence interval 1.13 to 1.88, p=0.004). Although no interactions were observed between T2DM and BMI on LV hypertrophy (p=0.6), there was a significant interaction between T2DM and waist circumference on LV hypertrophy (p=0.01). In conclusion, T2DM was independently associated with increased LV hypertrophy independent of various covariates in this multiethnic sample. Presence of T2DM increased the risk of LV hypertrophy by about 1.5-fold, and it possibly interacted with central obesity.

Left ventricular diastolic dysfunction in normotensive diabetic patients in various age strata

Although patients with type 2 diabetes demonstrate cardiac diastolic dysfunction, it is well known that cardiac diastolic dysfunction is produced by hypertension and aging. The purpose of the present study was to elucidate the cardiac structure and function in normotensive patients with type 2 diabetes in various age strata in order to assess the effect of diabetes mellitus itself on cardiac function. Echocardiographic examination was performed in 77 normotensive patients with type 2 diabetes (age: 63+/-11 years) and 76 healthy control subjects (age: 60+/-11 years) who were in their forties, fifties, sixties, and seventies. The left ventricular (LV) wall thickness and dimension were measured by M-mode echocardiography. The relative wall thickness, LV mass index, and LV ejection fraction (LVEF) were calculated. LV diastolic function was assessed by the peak velocity of early rapid filling (E velocity) and the peak velocity of atrial filling (A velocity), and the ratio of E to A (E/A) using the transmitral flow velocity, which were obtained by Doppler echocardiography. No difference was observed in the relative wall thickness, LV mass index, or LVEF between the diabetic patients and control subjects in any of the age strata. The E/A ratio in the patients with type 2 diabetes was not different from that in the control subjects in their 40s (1.17+/-0.35 versus 1.20+/-0.36). However, E/A was significantly lower in the diabetic patients than in the control subjects in their 50s (0.87+/-0.28 versus 1.14+/-0.24), 60s (0.78+/-0.22 versus 0.97+/-0.27), and 70s (0.66+/-0.19 versus 0.84+/-0.21) (p<0.05). The duration of type 2 diabetes was significantly longer in patients in their 50s (7.0+/-2.5 years), 60s (8.0+/-3.2 years), and 70s (10.4+/-3.2 years) than in patients in their 40s (3.3+/-1.9 years) (p<0.001). The value of E/A in the diabetic patients correlated with the duration of type 2 diabetes (r=-0.62, p<0.001). These results indicate that cardiac diastolic dysfunction without LV systolic dysfunction in patients with well-controlled type 2 diabetes is related neither to hypertension nor LV hypertrophy, but rather to aging and the duration of type 2 diabetes.

Differential impact of left ventricular mass and relative wall thickness on cardiovascular prognosis in diabetic and nondiabetic hypertensive subjects

BACKGROUND

Cardiovascular prognostic significance of relative wall thickness (RWT) in patients with diabetes has not been reported although concentric hypertrophy is common in diabetic patients.

PURPOSE

This study was conducted to test the hypothesis that the prognostic significance of different measures of left ventricular (LV) geometric change, principally LV mass index (LVMI) and RWT, would be different in diabetic patients compared with nondiabetic individuals among Japanese hypertensive subjects.

METHODS

Ambulatory blood pressure monitoring and echocardiography were performed in 400 uncomplicated hypertensive individuals at baseline, of whom 379 (157 with diabetes and 222 without diabetes; mean age 67.8 +/- 8.8 years) were successfully followed up for 63 +/- 26 months to document cardiovascular events. We dichotomized LVMI and RWT to the highest quartile vs other 3 quartiles for further categoric analyses in diabetic and nondiabetic patients.

RESULTS

Fifty-three cardiovascular events occurred during the follow-up period. With Kaplan-Meier analysis, both diabetic and nondiabetic patients with the highest quartile of LVMI showed a significantly higher incidence of cardiovascular vents. However, the highest quartile of RWT was associated with cardiovascular events only in diabetic subjects. With Cox regression analyses controlling for age, sex, body mass index, serum creatinine, triglycerides, and clinic systolic blood pressure, RWT (per 0.01 change), but not LVMI, was associated with cardiovascular events in diabetic patients (relative risk: 1.06, 95% confidence interval 1.02-1.11; P = .008), whereas LVMI (g/m2), but not RWT, was associated with cardiovascular events in nondiabetic patients (relative risk: 1.02, 95% confidence interval 1.01-1.03; P = .005).

CONCLUSION

In hypertensive subjects with type 2 diabetes mellitus, echocardiographic LV RWT is a predictor of cardiovascular events independent of LV mass and other confounders.

Early alterations in myocardia and vessels of the diabetic rat heart: an FTIR microspectroscopic study

Diabetes mellitus is associated with a high incidence and poor prognosis of cardiovascular disease. The aim of the present study was to examine the effect of relatively short-term (5 weeks) Type I diabetes on the left ventricle, the right ventricle and the vessel (vein) on the left ventricle of the myocardium at molecular level by FTIR (Fourier-transform infrared) microspectroscopy. The rats were categorized into two groups: control group (for the left ventricle myocardium, n=8; for the right ventricle myocardium, n=9; for the vein, n=9) and streptozotocin-induced diabetic group (for the left ventricle myocardium, n=7; for the right ventricle myocardium, n=9; for the vein, n=8). Two adjacent cross-sections of 9 microm thickness were taken from the ventricles of the hearts in two groups of rats by using a cryotome. The first sections were used for FTIR microspectroscopy measurements. The second serial sections were stained by haematoxylin/eosin for comparative purposes. Diabetes caused an increase in the content of lipids, an alteration in protein profile with a decrease in alpha-helix and an increase in beta-sheet structure as well as an increase in glycogen and glycolipid contents in both ventricles and the vein. Additionally, the collagen content was found to be increased in the vein of the diabetic group. The present study demonstrated that diabetes-induced alterations in the rat heart can be detected by correlating the IR spectral changes with biochemical profiles in detail. The present study for the first time demonstrated the diabetes-induced alterations at molecular level in both ventricle myocardia and the veins in relatively short-term diabetes.

Disparate effects of 12-lipoxygenase and 12-hydroxyeicosatetraenoic acid in vascular endothelial and smooth muscle cells and in cardiomyocytes

The expression and activity of the arachidonic acid-metabolizing enzyme leukocyte-type 12-lipoxygenase (12-LO) are augmented in cultured vascular endothelial and smooth muscle cells exposed to high glucose concentrations and in blood vessels of diabetic animals. The product of this enzyme, 12-hydroxyeicosatetraenoic acid (12-HETE), evokes two types of interactions in these cells: on one hand it acts as a pro-inflammatory factor that contributes to the initiation and progression of atherosclerotic lesions. Yet on the other, it protects the same cells against deleterious effects of high levels of intracellular glucose by downregulating the glucose transport system in the cells. In addition, it has been shown that 12-LO and 12-HETE support insulin-dependent glucose transporter-4 translocation to the plasma membrane by maintaining intact actin fiber network in the cardiomyocytes. Here we focus on the disparate cellular interactions by which 12-LO and 12-HETE affect the glucose transport system in vascular endothelial and smooth muscle cells and in cardiomyocytes.

Diabetes mellitus is a strong, independent risk for atrial fibrillation and flutter in addition to other cardiovascular disease

BACKGROUND

Diabetes mellitus (DM) is a major risk factor for atherosclerosis. There is a controversy in literature about correlation between DM and atrial fibrillation. The goal of this study was to evaluate DM as a risk factor for atrial fibrillation or flutter using a very large database.

METHOD

Patient treatment files (PTF) containing discharge diagnoses were utilized using ICD-9 codes of inpatient treatment from Veterans Health Administration Hospitals (VAH). Patients with type II DM (ICD-9 code 250.0) (293,124) discharged from the VAH between 1990 and 2000. Non-matched controls without DM but with hypertension (552,624) were selected from the same PTF. By using multi-variate logistic regressions, the occurrence of atrial fibrillation, atrial flutter, CHF, CAD and LVH was compared.

RESULTS

Atrial fibrillations occurred in 43,674 (14.9%) DM patients vs. 57,077 (10.3%) in the control group (p<0.0001). Atrial flutter occurred in 11,852 (4%) of DM patients vs. 13,554 (2.5%) of the control group (p<0.0001). Using multi-variant analysis, DM remained independently associated with atrial fibrillation with an OR of 2.13, (95% CI: 2.10 to 2.16; p<0.0001) and flutter (OR 2.20, CI: 2.15 to 2.26; p<0.0001). Furthermore, CHF (OR 3.12, CI: 3.09 to 3.16; p<0.0001), LVH (OR 1.85, CI: 1.77 to 1.92; p<0.0001) and CAD (OR 2.39, CI: 2.34 to 2.44; p<0.0001) were also independently associated with DM.

CONCLUSION

This is the first large-scale study finding DM as a strong, independent risk for the occurrence of atrial fibrillation and flutter and other cardiovascular disease.

Ultrastructure and histochemistry of rat myocardial capillary endothelial cells in response to diabetes and hypertension

Insufficient growth and rarefaction of capillaries, followed by endothelial dysfunction may represent one of the most critical mechanisms involved in heart damage. In this study we examined histochemical and ultrastructural changes in myocardial capillary endothelium in two models of heart failure streptozotocin-induced diabetes mellitus (STZ) and NO-deficient hypertension in male Wistar rats. Diabetes was induced by a single i.v. dose of STZ (45 mg/kg) and chronic 9-week stage was analysed. To induce NO-deficient hypertension, animals were treated with inhibitor of NO synthase L-nitroarginine methylester (L-NAME) (40 mg/kg) for 4 weeks. Left ventricular tissue was processed for enzyme catalytic histochemistry of capillary alkaline phosphatase (AlPh), dipeptidyl peptidase IV (DPP IV), and endothelial NO synthase/NADPH-diaphorase (NOS) and for ultrastructural analysis. In diabetic and hypertensive rats, lower/absent AlPh and DPP IV activities were found in focal micro-areas. NOS activity was significantly reduced and persisted only locally. Quantitative evaluation demonstrated reduction of reaction product intensity of AlPh, DPP and NOS by 49.50%, 74.36%, 20.05% in diabetic and 62.93%, 82.71%, 37.65% in hypertensive rats. Subcellular alterations of endothelial cells were found in heart of both groups suggesting injury of capillary function as well as compensatory processes. Endothelial injury was more significant in diabetic animals, in contrast the adaptation was more evident in hypertensive ones. CONCLUDING: both STZ-induced diabetes- and NO-deficient hypertension-related cardiomyopathy were accompanied by similar features of structural remodelling of cardiac capillary network manifested as angiogenesis and angiopathy. The latter was however, predominant and may accelerate disappearance of capillary endothelium contributing to myocardial dysfunction.

Diabetes mellitus and heart failure: basic mechanisms, clinical features, and therapeutic considerations

Diabetic cardiomyopathy encompasses the spectrum from subclinical disease to the full-blown syndrome of congestive heart failure. The prevalence of type 2 diabetes mellitus is increasing at an alarming rate in the western world. and with it, the frequency of diabetes-related heart failure. There is at least early suggestion that target-driven, long-term, intensified intervention that is aimed at multiple risk factors in patients who have type 2 diabetes and microalbuminuria may reduce the risk of macrovascular (cardiovascular) and micro-vascular complications by approximately 50%. Thus, it is imperative that patients, particularly those who are at risk for the cardiovascular dysmetabolic syndrome, be screened aggressively for the presence of glucose intolerance and diabetes. When detected, all metabolic and cardio-vascular parameters should be evaluated and treated aggressively to reach currently recommended clinical targets. Such action will result in great benefit for patients by reducing morbidity and mortality and improving quality of life and will reduce the financial burden that is associated with this epidemic disease.

Noninvasive Characterization of Myocardial Blood Flow in Diabetic, Hypertensive, and Diabetic–Hypertensive Rats Using Spin-Labeling MRI

OBJECTIVE

Microvascular alterations in the diabetic and hypertensive heart are likely to contribute to heart failure. In this work, myocardial blood flow and left ventricular function were measured in vivo in diabetic, hypertensive, and diabetic-hypertensive rats using MRI methods.

METHODS

An 8-week-duration type 1 diabetes was induced by streptozotocin (STZ) in 8 Wistar-Kyoto (WKY) rats (STZ) and in 11 spontaneously hypertensive (SHR) rats (STZ-SHR). Fourteen WKY and 12 SHR served as control and hypertensive groups. Myocardial blood flow quantification was performed using an arterial spin-labeling MRI method. Left ventricular morphology and function were assessed during the same experiment using cine-MRI.

RESULTS

Respective myocardial blood flow values for each group were 6.4 +/- 1.1 (WKY), 6.0 +/- 1.9 (STZ), 5.5 +/- 1.3 (SHR), and 4.3 +/- 0.9 mL. g(-1). min(-1) (STZ-SHR). Myocardial blood flow was significantly decreased in STZ-SHR rats compared with the other groups (p <.05, STZ-SHR vs. all groups). Cine-MRI showed morphological alterations in all pathological groups. No alteration of the ejection fraction was observed in the pathological groups.

CONCLUSION

Myocardial blood flow is altered in vivo before any sign of heart failure when rats have type 1 diabetes and hypertension simultaneously. When only one of the pathologies occurs, MBF does not vary significantly.

Comparison of baseline characteristics and one-year outcomes between African-Americans and Caucasians undergoing percutaneous coronary intervention

The objectives of this study were to determine whether there are race-based differences in baseline characteristics and in short- or long-term outcomes after percutaneous coronary intervention (PCI). African-Americans have a higher incidence of coronary artery disease but are less likely to undergo coronary revascularization than Caucasians. Little is known about the profiles and outcomes of African-Americans who undergo PCI. Consecutive series of 1,268 African-Americans and 10,561 Caucasians with symptomatic coronary artery disease who underwent PCI between January 1994 and June 2001 were analyzed. Patients hospitalized for acute myocardial infarction were excluded. African-Americans were older, were more likely to be women, and had more co-morbid baseline conditions compared with Caucasians. Preprocedure lesion characteristics were similar with regard to vessel size, length, and complexity. The rate of clinical success did not differ between the groups. African-Americans experienced more in-hospital combined events of death and Q-wave myocardial infarction (p = 0.03). After propensity score adjustment, African-American race was not an independent predictor for in-hospital events. At 1 year, African-Americans had a slightly lower rate of target lesion revascularization and a 50% higher rate of death (9.8% vs. 6.4%, p <0.001), with a relative risk of 1.52 (95% confidence interval 1.22 to 1.89). In multivariate analysis, African-American race remained a significant predictor of increased 1-year mortality (hazard ratio 1.35, 95% confidence interval 1.06 to 1.71, p = 0.01). African-Americans undergoing angioplasty have more co-morbid baseline conditions than Caucasians. Despite similar clinical success, 1-year outcomes are impaired in African-Americans.

Left ventricular mass increases with deteriorating glucose tolerance, especially in women: independence of increased arterial stiffness or decreased flow-mediated dilation: the Hoorn study

OBJECTIVE

Type 2 diabetes and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease (CVD) risk. Increased left ventricular mass (LVM) is thought to increase CVD risk through several unfavorable cardiac changes. Type 2 diabetes and IGM are associated with increased LVM, but the underlying mechanism is unclear. We investigated the association between glucose tolerance status (GTS) and LVM and explored whether any such association could be mediated through increased arterial stiffness, impaired endothelial function, or the presence of atherosclerosis.

RESEARCH DESIGN AND METHODS

We used ultrasound to measure LVM, carotid and femoral stiffness, carotid-femoral transit time, and flow-mediated vasodilation (FMD) and tonometry to estimate compliance and augmentation index. The study population (n = 780) consisted of 287 individuals with normal glucose metabolism (NGM), 179 with IGM, and 314 with type 2 diabetes, and the mean age was 68.4 years.

RESULTS

In women, after adjusting for age, height, BMI, and mean arterial pressure, LVM increased significantly with deteriorating GTS (LVM 157 g in NGM, 155 g in IGM, and 169 g in type 2 diabetes; P for trend <0.018). Additional adjustment for arterial stiffness, FMD, or the presence of atherosclerosis did not materially alter the results, even though these variables were significantly associated with both GTS and LVM. Indexes of hyperglycemia/-insulinemia or insulin resistance explained at most 7% of the association between GTS and LVM. In men, no statistically significant associations were observed.

CONCLUSIONS

Our data expand the conceptual view of the pathogenesis of GTS-related changes in LVM because we show that the increase in LVM in women is independent of increased arterial stiffness, impaired FMD, or the presence of atherosclerosis. In addition, we show that this increase in LVM is only minimally explained by indexes of hyperglycemia/-insulinemia or insulin resistance. Our data may, in part, explain the increased CVD risk seen in women with deteriorating GTS.

Diabetes Mellitus and Heart Failure

The metabolic abnormalities associated with diabetes mellitus result in macrovascular and microvascular complications in multiple organ systems; it is the cardiovascular impact that accounts for the greatest morbidity and mortality associated with this disease. Heart failure, both with reduced and preserved systolic function, is a major complication, arising from the frequent associations with coronary atherosclerosis, hypertension, and a specific heart muscle dysfunction (cardiomyopathy) that occurs independently of coronary artery disease. Hyperglycemia, insulin resistance, and hypertension, together with activation of both the circulating and the tissue renin-angiotensin-aldosterone systems, contribute to structural fibrosis and autonomic neuropathy. Thus, it becomes imperative to identify cardiac abnormalities early in the course of both type 1 and type 2 diabetes to allow early and aggressive intervention to control glucose and blood pressure and to normalize blood lipid profiles. Patients with diabetes should be treated to secondary prevention targets, including blood pressure less than 130/80 mm Hg and low-density lipoprotein cholesterol level less than 100 mg/dL. Angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers,beta blockers, calcium channel-blockers, statins, and aspirin have all been demonstrated to significantly reduce cardiovascular morbidity and mortality in patients with diabetes.

Protein kinase C-delta modulates apoptosis induced by hyperglycemia in adult ventricular myocytes

We evaluated the direct effect of hyperglycemia on apoptosis of adult rat ventricular myocytes (ARVM) in vitro. Hyperglycemia (16.5 mM) for 24 h increased apoptosis by greater than threefold (48.2 +/- 4.4%, by the TdT-mediated dUTP nick-end labeling method) compared with baseline (14.7 +/- 2.5%). Hyperosmolarity with mannitol (11.0 mM) in the presence of 5.5 mM glucose also increased apoptosis by approximately twofold of baseline. Both glucose and mannitol treatment resulted in the membrane translocation of protein kinase C (PKC)-delta, and the activation of PKC-delta was confirmed by immune complex kinase assay. PKC-delta-specific translocation inhibitor peptide (deltaV1-1) attenuated only apoptosis induced by hyperglycemia but not by mannitol. A PKC-epsilon-specific translocation inhibitor peptide (epsilonV1-1) affected neither type of apoptosis. Moderate overexpression of PKC-delta by adenovirus gene transfer prevented the antiapoptotic effect of deltaV1-1. Furthermore, deltaV1-1 attenuated the production of reactive oxygen species (ROS) by glucose. Taken together, our results indicate that increased ROS production regulated by PKC-delta is in part responsible for the induction of apoptosis by hyperglycemia and that apoptosis by hyperglycemia is mechanistically different from that by hyperosmolarity.

Treatment of heart failure in patients with diabetes mellitus

Patients with diabetes mellitus have an increased morbidity and mortality from cardiovascular disease. Both coronary artery disease and congestive heart failure (CHF) are largely responsible for the increased cardiovascular adverse events in patients with diabetes. This review discusses the pathophysiology of CHF, the mechanisms of left ventricular (LV) dysfunction and the neurohormonal mechanisms involved in both LV dysfunction and CHF. Diabetes with and without hypertension is an important cause of LV dysfunction and CHF. Diabetes may be responsible for the metabolic and ultrastructural causes of LV dysfunction, while hypertension may be responsible for the marked fibrotic changes that are found. Experimental induction of diabetes in animals has shed light on the biochemical and ultrastructural changes seen. The role of insulin to reverse both metabolic and structural changes is reviewed both from experimental data and with the limited amount of clinical data available. The therapy of CHF in patients with diabetes is similar to that of patients without diabetes, with therapy directed toward the use of beta-blockers and angiotensin converting enzyme (ACE) inhibitors. As the morbidity and mortality are higher in patients with diabetes, several studies have pointed out the importance of this subgroup where the opportunity to make a significant clinical impact exists. A significant opportunity exists to reduce morbidity and mortality with beta-blockers and ACE inhibitors when ischaemia and CHF are both present. However, studies in patients diabetes have been limited to post hoc subgroup analyses and rarely as predefined subgroups. Clinical trials involving patients with diabetes with and without hypertension and LV dysfunction are clearly needed in the future to adequately address the needs of this high risk subgroup.

Cardiomyopathy and heart failure in diabetes

Patients with insulin resistance or type 2 diabetes have a particularly high risk for heart failure and a poor prognosis once they develop heart failure. The choice of drugs for the management of heart failure in these patients should be directed at changing the natural history of the disease. The various drugs available for the treatment of heart failure, including ACE inhibitors and beta-adrenergic blockers, are known to be beneficial and should be given as first-line agents. Aggressive risk-factor modification and tight blood pressure and glycemic control are crucial. Much work is needed to establish the safety and efficacy of various oral antidiabetic agents, especially the TZDs, for which the theoretic benefits are substantial and overall morbidity and mortality impact remain ill-defined.

Characterization of contractile function in diabetic hypertensive cardiomyopathy in adult rat ventricular myocytes

Diabetes and hypertension both produce myocardial dysfunction that accelerates cardiovascular morbidity and mortality. Coexistence of the two often results in a more severe cardiomyopathy than either process alone. The purpose of this study was to characterize the contractile function of diabetic hypertensive cardiomyopathy at the single myocyte level. Adult spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were made diabetic with a single injection (55 mg/kg) of streptozotocin (STZ). Contractile properties of ventricular myocytes were evaluated, including peak shortening (PS), time-to-peak shortening (TPS), time-to-90% relengthening (TR90) and maximal velocities of shortening/relengthening (+/-dL/d t). The experimental animals exhibited enlarged heart size, elevated blood glucose and systolic blood pressure. PS was unchanged (SHR), enhanced (WKY-STZ) or depressed (SHR-STZ) compared to control (WKY). Myocytes from all experimental groups displayed prolonged TPS and TR90 compared to the WKY group, although only those from the hypertensive groups (SHR, SHR-STZ) were associated with reduced +/-dL/d t. Additionally, myocytes from the WKY-STZ but not the SHR or the SHR-STZ groups exhibited impaired responsiveness to increased extracellular Ca2+. Myocytes from the SHR-STZ group displayed a leftward shift of the stimulus frequency-peak shortening response curve compared to the WKY group. These results confirmed observations at the multicellular levels that combination of diabetes and hypertension results in a greater impairment of cardiac contractile function than is seen with either disease alone.

Alterations of cartilage and collagen expression during fracture healing in experimental diabetes

We investigated alterations in the expression of mRNA for type II and type X collagen in fracture callus of experimentally induced diabetic animals compared with controls and performed radiographic, histological, immunocytochemical and biomechanical studies. Experimentally induced diabetic rats exhibited an alteration in the temporal expression of type II and type X collagen mRNA and a decrease in type X mRNA expression as compared to controls. Radiographs showed a more intense periosteal reaction and a more rapid reconstitution of cortices in control versus diabetic animals. Histologically there was a delay in chondrocyte maturation and hypertrophy seen in diabetics. Immunolocalization of type X collagen demonstrated a delay in type X collagen expression around the hypertrophic chondrocytes. Biomechanical analysis showed a decrease in the strength of healing fractures in diabetic animals. Fracture healing in diabetic patients is compromised and may lead to delays in bone union. Though the exact mechanisms are unknown, we present evidence of decreased mechanical strength of the fracture and suggest that associated changes in collagen expression and chondrocyte maturation are mechanisms leading to delayed healing in untreated and poorly controlled diabetes.

Cardiomyocyte dysfunction in sucrose-fed rats is associated with insulin resistance

Diabetes is associated with impaired cardiac dysfunction in both humans and animals. Specific phenotypic changes-prolonged action potentials, slowed cytosolic Ca2+ clearing, and slowed relaxation-that contribute to this whole heart dysfunction occur in isolated ventricular myocytes. The present study was designed to determine whether cardiomyocyte abnormalities occur early in the development of type 2 diabetes (in this case, insulin resistance) and whether an insulin-sensitizing drug (metformin) is cardioprotective. In the study, high-sucrose feeding was used to induce whole-body insulin resistance. Wistar rats were maintained for 7-10 weeks on a starch (ST) diet, sucrose (SU) diet, or diet supplemented with metformin (SU + MET). Whole-body insulin resistance was measured in SU and SU + MET rats by performing euglycemic-hyperinsulinemic clamps. Mechanical properties of isolated ventricular myocytes were measured by high-speed video edge detection, and [Ca2+]i transients were evaluated with Fura-2 AM. Untreated SU rats were insulin-resistant (glucose infusion rate [GIR] = 14.5 +/- 1.1 mg.kg(-1).min(-1)); metformin treatment in SU + MET rats prevented this metabolic abnormality (GIR = 20.0 +/- 2.2 mg.kg(-1).min(-1)). Indexes of myocyte shortening and relengthening were significantly longer in SU rats (area under the relaxation phase [AR/peak] = 103 +/- 3 msec) when compared to ST and SU + MET rats (AR/peak = 73 +/- 2 and 80 +/- 1 msec, respectively). The rate of intracellular Ca2+ decay and the integral of the Ca2+ transient through the entire contractile cycle were significantly longer in myocytes from SU than from ST rats (Ca2+ signal normalized to peak amplitude = 152 +/- 8 vs. 135 +/- 5 msec, respectively). Collectively, our data showed the presence of cardiomyocyte abnormalities in an insulin-resistant stage that precedes frank type 2 diabetes. Furthermore, metformin prevented the development of sucrose-induced insulin resistance and the consequent cardiomyocyte dysfunction.

Transmural heterogeneity of myocardial integrated backscatter in diabetic patients without overt cardiac disease

It is important to detect early changes in diabetic myocardium, because some diabetic patients suffer from diabetic cardiomyopathy, especially those with poorer glycemic control or hypertension (HT). To clarify whether ultrasonic tissue characterization can noninvasively detect ultrastructural changes in diabetic myocardium, we analyzed the transmural heterogeneity in myocardial integrated backscatter (THIB) in 20 diabetic patients and 16 normal subjects. THIB was defined as the absolute value of difference of integrated backscatter between the endocardial and epicardial half of the myocardium. THIB in diabetic patients was significantly greater than that in normal subjects. In diabetic patients, there was a significant correlation between glycosylated hemoglobin and THIB, and the greater THIB was shown in patients with HT compared with those without HT. Early changes in the myocardium, related to increased interstitial collagen deposition or other occult cardiomyopathic changes, may be detected on the basis of quantitative analysis of THIB in diabetic patients.

Effect of hypertension on the development of diabetic cardiomyopathy

The effect of hypertension on the progression of diabetic cardiomyopathy was examined by attempting to induce a similar level of diabetes in both spontaneously hypertensive rats (SHR) and Wistar rats. Streptozotocin (STZ) was injected into SHR (45 mg/kg) and Wistar rats (55 mg/kg) before (eight weeks of age) and after (twelve weeks of age) the development of hypertension in the SHR. For both groups of animals, induction of diabetes resulted in depressed weight gain, increased food and fluid consumption, hypoinsulinemia, hyperglycemia, and hypertriglyceridemia. For the rats injected at eight weeks of age, an oral glucose tolerance test (OGTT) demonstrated that although the SHR were significantly less diabetic than Wistar rats, the degree of cardiac dysfunction was equivalent in both strains. These results suggest that hypertension was interacting with the diabetic condition to impair cardiac performance. Injecting SHR at twelve weeks of age increased the severity of diabetes but interestingly did not depress heart function compared with the non-diabetic SHR group. Injecting Wistar rats at this age also increased the severity of diabetes, but unlike the SHR diabetic animals, these rats still had impaired cardiac performance. These results suggest that hypertension exacerbates the cardiac dysfunction seen during diabetes, especially when SHR rats are injected with STZ prior to the elevation of blood pressure. Moreover, in the SHR, the development of LV hypertrophy at the time of STZ injection may have compensated for the damaging effects of diabetes on the myocardium, thereby enabling the heart to perform normally.Key words: diabetes, hypertension, streptozotocin, cardiac dysfunction, spontaneously hypertensive rat.

Palmitate induces structural alterations in nuclei of cardiomyocytes

The objective of this study was to examine the hypothesis that the alterations of cardiac nuclei, that has been noted in some cardiomyopathies, can be produced by palmitate, a saturated fatty acid present in high circulating concentrations in patients with conditions associated with a high probability of developing cardiomyopathy. Cardiomyocytes isolated from embryonic chick ventricle were maintained in culture for 72 h and then treated with palmitate, 100 microM for 24 h. Cells were stained with acridine orange or Giemsa and examined microscopically. Cell size and nuclear size were examined by forward light scatter during flow cytometry. Cells were permeabilized and their nuclei were stained with propidium iodide and examined by flow cytometry on populations of 10,000 cells. Cardiomyocytes treated with palmitate displayed changes in nuclear appearance as nuclei were larger, relative to cell size, with more intense acridine orange staining in a peripheral location. Nucleoli were often disrupted. Palmitate produced a significant (P < 0.001) and 17% increase in nuclear size compared to untreated cells using flow cytometry analysing forward light scatter to estimate nuclear and whole cells size. There were no significant changes in the size of the whole cell and ratio of nucleus to whole cell was significantly (P < 0.01) increased compared to control cells. Fluorescent activating cell sorting analysis of propidium iodide stained nuclei demonstrated that the nuclear enlargement was not due to cell mitosis as the proportion of nuclei in Go/G1, S or M was not changed by palmitate. In summary, these studies identify that palmitate can induce structural abnormalities of cardiomyocytes nuclei by producing increased nuclear size and nucleolar destruction.

Prediction of in-hospital mortality after first-ever stroke: the Lausanne Stroke Registry

We aimed to study in-hospital mortality after a first-ever stroke (brain infarction or parenchymatous hemorrhage) and to determine its predictors using easily obtainable variables. The main outcome measure was vital status at hospital discharge. Clinical features and type of stroke, with a particular emphasis on age, stroke topography and presumed causes of stroke, were studied in 3362 consecutive patients from the Lausanne Stroke Registry. Overall mortality was 4.8%. Brain hemorrhage mortality was 14.4% (48/333) and brain infarction mortality was 3.70% (112/3029). Localizations with high mortality included infratentorial (17.5%) and deep hemispheric (15.9%) territories for brain hemorrhage and, for brain infarction, multiple localizations in the posterior circulation (18.4%) and large middle cerebral artery territory (15.5%). Presumed causes of stroke associated with high mortality included saccular aneurysm (58.3%) and hypertensive arteriopathy (13.0%) for brain hemorrhage and, for brain infarction, dissection (10.4%), arteritis (8.3%), hematologic conditions (6.7%) and coexisting arterial and cardiac sources of embolism (5.2%). Multivariate logistic analysis showed that impaired consciousness on admission and limb weakness were good predictors of mortality for brain hemorrhage, while impaired consciousness and the cumulative effect of progressive worsening, limb weakness, left ventricular hypertrophy, past history of cardiac arrhythmia and previous transient ischemic attack were predictors of mortality for brain infarction. Age was not an independent predictor of stroke mortality, but for brain infarction the number of cumulative factors considered in the model increased with age. Our study shows that several factors associated with death risk are available during the first few hours after onset of stroke. Age alone is not critical, although its interaction with other factors should be considered.