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1.  Silent coronary artery disease in type 2 diabetes mellitus: the role of Lipoprotein(a), homocysteine and apo(a) polymorphism 
Background
There is little data on the relationship between novel cardiovascular risk factors and silent coronary artery disease (CAD) in diabetic patients. We investigated whether Lipoprotein(a), homocysteine and apolipoprotein(a) polymorphism are associated with angiographically assessed asymptomatic coronary artery disease (CAD) in diabetic patients.
Methods
1,971 type 2 diabetic patients without clinical signs of cardiovascular diseases and with a negative history of CAD were consecutively evaluated. Among them, 179 patients showed electrocardiographic abnormalities suggestive of ischemia or previous asymptomatic myocardial infarction. These 179 patients were subjected to a non-invasive test for CAD (ECG stress testing and/or scintigraphy). Among patients with a highly positive stress testing (n = 19) or a positive scintigraphy (n = 74), 75 showed an angiographically documented CAD (CAD group). Seventy-five patients without CAD (NO CAD group) were matched by age, sex and duration of diabetes to CAD patients. In NO CAD patients an exercise ECG test, a 48-hour ambulatory ECG and a stress echocardiogram were negative for CAD.
Results
Lipoprotein(a) levels (22.0 ± 18.9 versus 16.0 ± 19.4 mg/dl; p < 0.05), homocysteine levels (13.6 ± 6.6 versus 11.4 ± 4.9 mmol/l; p < 0.05) and the percentage of subjects with at least one small apolipoprotein(a) isoform (70.7% versus 29.3%; p < 0.0001) were higher in CAD than NO CAD group. Logistic regression analysis showed that apolipoprotein(a) polymorphism (OR:8.65; 95%CI:3.05–24.55), microalbuminuria (OR:6.16; 95%CI:2.21–17.18), smoking (OR:2.53; 95%CI:1.05–6.08), HDL (OR:3.16; 95%CI:1.28–7.81), homocysteine (OR:2.25; 95%CI:1.14–4.43) and Lipoprotein(a) (OR:2.62; 95%CI:1.01–6.79) were independent predictors of asymptomatic CAD.
Conclusions
The present investigation shows an independent association of Lipoprotein(a), homocysteine and apo(a) polymorphism with silent CAD. Other studies are needed to establish whether these parameters are suitable for CAD screening in diabetic patients.
doi:10.1186/1475-2840-1-5
PMCID: PMC149426  PMID: 12473160
2.  Gender differences in factors influencing insulin resistance in elderly hyperlipemic non-diabetic subjects 
Background
The increase in the prevalence of insulin resistance-related metabolic syndrome, a disorder that greatly increases the risk of diabetes, heart attack and stroke, is alarming. One of the most frequent and early symptoms of metabolic syndrome is hypertriglyceridemia. We examined the gender differences between various metabolic factors related to insulin resistance in elderly non-diabetic men and postmenopausal women of comparable age suffering from hypertriglyceridemia, and compared them with healthy subjects of equal age.
Results
The indexes of insulin resistance HOMA IR and QUICKI were significantly higher in both hyperlipemic men and women than in controls; 95% confidence limits of hyperlipemic subjects did not overlap with controls. In both normolipemic and hyperlipemic men and women serum leptin correlated significantly with insulin resistance, while HDL-cholesterol correlated inversely with HOMA-IR only in women (both normo- and hyperlipemic), and serum tumor necrosis factor α (TNFα) only in hyperlipemic women. According to results of multiple regression analysis with HOMA-IR as a dependent variable, leptin played a significant role in determining insulin resistance in both genders, but – aside from leptin – triglycerides, TNFα and decreased HDL-cholesterol were significant determinants in women, while body mass index and decreased HDL-cholesterol were significant determinants in men. The coefficient of determination (R2) of HOMA IR by above mentioned metabolic variables was in women above 60%, in men only about 40%.
Conclusion
The significant role of serum leptin in determination of insulin resistance in both elderly men and postmenopausal women of equal age was confirmed. However, the study also revealed significant gender differences : in women a strong influence of triglycerides, TNFα and decreased HDL-cholesterol, in men only a mild role of BMI and decreased HDL-cholesterol.
doi:10.1186/1475-2840-1-4
PMCID: PMC140144  PMID: 12423554
3.  Intimal redox stress: Accelerated atherosclerosis in metabolic syndrome and type 2 diabetes mellitus. Atheroscleropathy 
Metabolic syndrome, insulin resistance, prediabetes, and overt type 2 diabetes mellitus are associated with an accelerated atherosclerosis (atheroscleropathy). This quartet is also associated with multiple metabolic toxicities resulting in the production of reactive oxygen species. The redox stress associated with these reactive oxygen species contribute to the development, progression, and the final fate of the arterial vessel wall in prediabetic and diabetic atheroscleropathy. The prevention of morbidity and mortality of these intersecting metabolic diseases can be approached through comprehensive global risk reduction.
doi:10.1186/1475-2840-1-3
PMCID: PMC140143  PMID: 12392600
Atherosclerosis; Atheroscleropathy; Oxidative stress; ROS (reactive oxygen species); RNS (reactive nitrogen species); Reductive stress
4.  Losartan and diabetic nephropathy: commentaries on the RENAAL study 
The RENAAL (Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan) study is a multinational, double-blind, randomized, placebo controlled trial which was recently published. It was aimed to evaluate the effect of the angiotensin receptor blocker losartan in patients with diabetic nephropathy. The primary efficacy measure was the time to the first event of the composite end point of a doubling of serum creatinine, end-stage renal disease, or death. The conclusion was that losartan led to significant improvement in renal outcomes, that was beyond that attributable to blood pressure control in patients with type 2 diabetes and nephropathy.
The perusal of the report raises concern, regarding to both the patient population as well as the outcome measures. At randomization, the placebo group included more patients with angina, myocardial infarction and lipid disorders than the losartan group. Information on glucose metabolism was disregarded, and data on antihyperglycemic therapy – which may have undesirable influences on cardiac performance – were not included in a multivariate analysis. In addition, only data on first hospitalization were reported, whilst information on total specific-cause hospitalizations was disregarded, thus potentially masking further unfavorable events. Furthermore, creatinine seems not to be a reliable surrogate end point. Based on its mechanism of action, losartan may possess favorable renoprotective properties. However, due to the methodological flaws and the incomplete data in the RENAAL study, the question of the effectiveness and safety of this drug in diabetic nephropathy remains yet unanswered.
doi:10.1186/1475-2840-1-2
PMCID: PMC116616  PMID: 12119058
Angiotensin receptor blockers; Clinical trials; Diabetes mellitus; Losartan; Nephropathy; RENAAL study
5.  How hyperglycemia promotes atherosclerosis: molecular mechanisms 
Both type I and type II diabetes are powerful and independent risk factors for coronary artery disease (CAD), stroke, and peripheral arterial disease. Atherosclerosis accounts for virtually 80% of all deaths among diabetic patients. Prolonged exposure to hyperglycemia is now recognized a major factor in the pathogenesis of atherosclerosis in diabetes. Hyperglycemia induces a large number of alterations at the cellular level of vascular tissue that potentially accelerate the atherosclerotic process. Animal and human studies have elucidated three major mechanisms that encompass most of the pathological alterations observed in the diabetic vasculature: 1) Nonenzymatic glycosylation of proteins and lipids which can interfere with their normal function by disrupting molecular conformation, alter enzymatic activity, reduce degradative capacity, and interfere with receptor recognition. In addition, glycosylated proteins interact with a specific receptor present on all cells relevant to the atherosclerotic process, including monocyte-derived macrophages, endothelial cells, and smooth muscle cells. The interaction of glycosylated proteins with their receptor results in the induction of oxidative stress and proinflammatory responses 2) oxidative stress 3) protein kinase C (PKC) activation with subsequent alteration in growth factor expression. Importantly, these mechanisms may be interrelated. For example, hyperglycemia-induced oxidative stress promotes both the formation of advanced glycosylation end products and PKC activation.
doi:10.1186/1475-2840-1-1
PMCID: PMC116615  PMID: 12119059

Results 1-5 (5)