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Background Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase (NOS). Increased levels of ADMA cause impaired vasodilation, leading to endothelial dysfunction and a higher risk for cardiovascular events. In patients with a chronic kidney disease, increased ADMA levels are reported to play a role in the pathogenesis of accelerated atherosclerosis and are an independent risk marker leading to end-stage renal disease and mortality. Circulating ADMA is metabolized by the action of dimethylarginine dimethylamino hydrolase (DDAH) and DDAH2 isoform is the most prevalent in tissues expressing endothelial NOS. DDAH and NOS are co-expressed in the same kidney regional sites supporting the hypothesis that a strict and specific regulation of intracellular ADMA levels is crucial for NO generation in the kidney. Starting from these findings, the study aims to investigate the role of DDAH2 gene promoter polymorphism at position -1151 A/C in determining the levels of ADMA in type 2 diabetic patients (T2DM) with chronic renal impairment. Methods Three groups of carefully selected subjects of both sexes were enrolled and compared. The first group (control subjects) comprised 286 non-diabetic subjects (mean age 55.8 ± 11.4 years), the second group (T2DM uncomplicated subjects) was made up of 322 T2DM subjects without complications (mean age 64.9 ± 9.6 years) whereas the third group (T2DM CRF subjects) included 110 T2DM patients with chronic renal impairment. The rs805304 DDAH2-1151 A/C promoter polymorphism was determined by a polymerase chain reaction–restriction fragment length polymorphism approach. Results T2DM CRF subjects showed significant increased plasma levels of ADMA with respect to those of T2DM uncomplicated subjects and control subjects (0.51 versus 0.39 versus 0.37 μmol/L, P = 0.002, respectively). Analysis of variance showed an interaction between DDAH2-1151 C carrier and groups on ADMA plasma levels (F = 4.36; P < 0.05). ADMA plasma levels were also dependent on groups (F = 4.96; P < 0.01). Conclusions Our work demonstrates that rs805304 DDAH2-1151 polymorphism plays a central role in determining ADMA in diabetic renal impairment, where patients with DDAH2-1151 C carriers showed the highest ADMA levels. This unfavourable genetic profile is highlighted by pathological kidney conditions such as diabetic CRF. These findings could open new insights on the pathways involving ADMA/DDAH/NOS in the development and progression of chronic renal impairment and therefore of the other micro– macrovascular diabetic complications. [ABSTRACT FROM PUBLISHER]

Background. Chronic infections have been demonstrated to be early factors of atherosclerosis and cardiovascular diseases, and their relevance increases when they are caused by agents with extremely broad spectrum of disease outcome such as Helicobacter pylori. The consequent endothelial impairment leads to a reduced bioavailability of nitric oxide. Increasing evidences have pointed out that the endogenous inhibitor of nitric oxide synthase, asymmetric dimethylarginine, defined as a risk factor for cardiovascular disease, may increase in infections and plays an important role impairing the vascular functions of the endothelium. Starting from these findings, we aim to investigate whether H. pylori may affect asymmetric dimethylarginine levels. Materials and Methods. The study was carried out on a group of 186 subjects (age 46.2 ± 14.9 years). We evaluated asymmetric dimethylarginine, symmetric dimethylarginine, L-arginine, presence of H. pylori by 13C-urea breath test, and the main parameters of glyco and lipo metabolic balance. Results. Increased levels of asymmetric dimethylarginine were found in H. pylori-positive subjects with respect to H. pylori-negative subjects (0.46 ×/÷ 1.13 versus 0.42 ×/÷ 1.23 mol/l, p < .001, respectively). No differences were detected in L-arginine levels between the two groups. Multiple regression analysis performed in H. pylori-positive subjects and H. pylori-negative subjects showed profound differences in the variables related to asymmetric dimethylarginine ( R2 = 66.9%, p < .01 versus 34.3%, p < .01, respectively) and symmetric dimethylarginine ( R2 = 39.2%, p < .01 versus 20.6%, p = .09, respectively) levels. Conclusions. Our data clearly demonstrate that H. pylori infection increases asymmetric dimethylarginine levels. Moreover, this infection causes a profound metabolic modification that alters the role of the known determinants of asymmetric dimethylarginine levels. We conclude that H. pylori infection must be taken into account as a cause of increased asymmetric dimethylarginine levels and that the eradication of H. pylori may therefore lead to a decrease in asymmetric dimethylarginine levels, which is a further reason for the reduction of the risk for cardiovascular disease in this large portion of population. [ABSTRACT FROM AUTHOR]