***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Patients with heart failure have reduced peripheral blood flow at rest , during exercise , and in response to endothelium-dependent vasodilators . Nitric oxide formed from L-arginine metabolism in endothelial cells contributes to regulation of blood flow under these conditions . A r and omized , double-blind crossover study design was used to determine whether supplemental oral L-arginine can augment peripheral blood flow and improve functional status in patients with moderate to severe heart failure . METHODS AND RESULTS Fifteen subjects were given 6 weeks of oral L-arginine hydrochloride ( 5.6 to 12.6 g/d ) and 6 weeks of matched placebo capsules in r and om sequence . Compared with placebo , supplemental oral L-arginine significantly increased forearm blood flow during forearm exercise , on average from 5.1 + /- 2.8 to 6.6 + /- 3.4 mL. min-1 . dL-1 ( P < .05 ) . Furthermore , functional status was significantly better on L-arginine compared with placebo , as indicated by increased distances during a 6-minute walk test ( 390 + /- 91 versus 422 + /- 86 m , P < .05 ) and lower scores on the Living With Heart Failure question naire ( 55 + /- 28 versus 42 + /- 26 , P < .05 ) . Oral L-arginine also improved arterial compliance from 1.99 + /- 0.38 to 2.36 + /- 0.30 mL/mm Hg ( P < .001 ) and reduced circulating levels of endothelin from 1.9 + /- 1.1 to 1.5 + /- 1.1 pmol/L ( P < .05 ) . CONCLUSIONS Supplemental oral L-arginine had beneficial effects in patients with heart failure . Further studies are needed to confirm the therapeutic potential of supplemental oral L-arginine and to identify mechanisms of action in patients with heart failure UNLABELLED The aim of this study was to evaluate whether long-term administration of arginine acting through a normalization of NO/cyclic-guanosine-3 ' 5'-cyclic monophosphate ( cGMP ) pathway was able to ameliorate peripheral and hepatic insulin sensitivity in 12 lean type 2 diabetic patients . RESEARCH DESIGN AND METHODS A double-blind study was performed for 3 months . In the first month , patients were treated with their usual diet . Then they were r and omly allocated into to groups . In group 1 , patients were treated with diet plus placebo ( orally three times per day ) for 2 months . In group 2 patients were treated for 1 month with diet plus placebo orally , three times per day ) and then for 1 month with diet plus L-arginine ( 3 g three times per day ) . At the end of the first and the second month of therapy , patients underwent a euglycemic-hyperinsulinemic clamp combined with [ 6,6 - 2H2 ] glucose infusion . A total of 10 normal subjects underwent the same test as control subjects . RESULTS In group 1 , no changes in basal cGMP levels , systolic blood pressure , forearm blood flow , glucose disposal , and endogenous glucose production were observed throughout . In group 2 , L-arginine normalized basal cGMP levels and significantly increased forearm blood flow by 36 % and glucose disposal during the clamp by 34 % whereas it decreased systolic blood pressure and endogenous glucose production by 14 and 29 % , respectively . However , compared with normal subjects , L-arginine treatment was not able to completely overcome the defect in glucose disposal . CONCLUSIONS L-Arginine treatment significantly improves but does not completely normalizc peripheral and hepatic insulin sensitivity in type 2 diabetic patients Background : Recently , the potential of L-arginine supplementation as a novel and effective strategy for weight loss and improving biochemical parameters in obese patients has been under consideration . Objectives : To evaluate the influence of 8-week oral L-arginine supplementation on body mass index ( BMI ) , waist circumference ( WC ) , triceps skinfold ( TS ) , subscapular skinfold ( SS ) , systolic blood pressure ( SBP ) , diastolic blood pressure ( DBP ) , plasma fasting blood sugar ( FBS ) , glycated hemoglobin ( HbA1c ) , triglyceride ( TG ) , total cholesterol ( TC ) , low-density lipoprotein ( LDL ) , high-density lipoprotein ( HDL ) , and malondialdehyde ( MDA ) in patients with BMI values > 29.9 or visceral obesity ( WC > 102 cm in men or > 88 cm in women ) . Patients and Methods : Ninety obese patients were included in a single-blind r and omized controlled trial . Patients were r and omized to receive either L-arginine ( 3 or 6 g thrice daily ) or placebo for 8 weeks . Anthropometric and biochemical indices , dietary intake , and blood pressure values were measured at the baseline and after the 8-week intervention . Results : Significant decreases in anthropometric parameters , blood pressure ( SBP , DBP ) , FBS , HbA1c , LDL , MDA ( P < 0.001 ) , TG ( P = 0.02 ) , and TC ( P = 0.002 ) and a significant increase in HDL ( P < 0.001 ) were observed in the intervention group , compared to the control group . In the control group , no significant differences were found between the baseline and end-of-intervention measurements . Conclusions : In conclusion , oral L-Arginine supplementation appears to improve anthropometric parameters , blood pressure values , and some blood biochemical indices associated with cardiovascular disease prevention BACKGROUND Vascular nitric oxide ( NO ) bioavailability is reduced in patients with coronary artery disease ( CAD ) . We investigated whether oral L-arginine , the substrate for NO synthesis , improves homeostatic functions of the vascular endothelium in patients maintained on appropriate medical therapy and thus might be useful as adjunctive therapy . METHODS AND RESULTS Thirty CAD patients ( 29 men ; age , 67+/-8 years ) on appropriate medical management were r and omly assigned to L-arginine ( 9 g ) or placebo daily for 1 month , with crossover to the alternate therapy after 1 month off therapy , in a double-blind study . Nitrogen oxides in serum ( as an index of endothelial NO release ) , flow-mediated brachial artery dilation ( as an index of vascular NO bioactivity ) , and serum cell adhesion molecules ( as an index of NO-regulated markers of inflammation ) were measured at the end of each treatment period . L-Arginine significantly increased arginine levels in plasma ( 130+/-53 versus 70+/-17 micromol/L , P<0.001 ) compared with placebo . However , there was no effect of L-arginine on nitrogen oxides ( 19.3+/-7.9 versus 18 . 6+/-6.7 micromol/L , P=0.546 ) , on flow-mediated dilation of the brachial artery ( 11.9+/-6.3 % versus 11.4+/-7.9 % , P=0.742 ) , or on the cell adhesion molecules E-selectin ( 47.8+/-15.2 versus 47.2+/-14.4 ng/mL , P=0.601 ) , intercellular adhesion molecule-1 ( 250+/-57 versus 249+/-57 ng/mL , P=0.862 ) , and vascular cell adhesion molecule-1 ( 567+/-124 versus 574+/-135 ng/mL , P=0.473 ) . CONCLUSIONS Oral L-arginine therapy does not improve NO bioavailability in CAD patients on appropriate medical management and thus may not benefit this group of patients BACKGROUND Coronary endothelial dysfunction is characterized by an imbalance between endothelium-derived vasodilating and vasoconstricting factors and coronary vasoconstriction in response to the endothelium-dependent vasodilator acetylcholine . Thus , the present double-blind , r and omized study was design ed to test the hypothesis that long-term , 6-month supplementation of L-arginine , the precursor of the endothelium-derived vasodilator NO , reverses coronary endothelial dysfunction to acetylcholine in humans with nonobstructive coronary artery disease . METHODS AND RESULTS Twenty-six patients without significant coronary artery disease on coronary angiography and intravascular ultrasound were blindly r and omized to either oral L-arginine or placebo , 3 g TID . Endothelium-dependent coronary blood flow reserve to acetylcholine ( 10(-6 ) to 10(-4 ) mol/L ) was assessed at baseline and after 6 months of therapy . There was no difference between the two study groups in clinical characteristics or in the coronary blood flow in the response to acetylcholine at baseline . After 6 months , the coronary blood flow in response to acetylcholine in the subjects who were taking L-arginine increased compared with the placebo group ( 149 + /- 20 % versus 6 + /- 9 % , P < 0.05 ) . This was associated with a decrease in plasma endothelin concentrations and an improvement in patients ' symptoms scores in the L-arginine treatment group compared with the placebo group . CONCLUSIONS Long-term oral L-arginine supplementation for 6 months in humans improves coronary small-vessel endothelial function in association with a significant improvement in symptoms and a decrease in plasma endothelin concentrations . This study proposes a role for L-arginine as a therapeutic option for patients with coronary endothelial dysfunction and nonobstructive coronary artery disease BACKGROUND Providing L-arginine as a precursor for nitric oxide has been proposed to improve endothelial function in population s at high risk for cardiovascular events . We studied the effects of dietary L-arginine supplementation with HeartBars ( a medical food rich in L-arginine , Cooke Pharma , Belmont , Calif ) on flow-mediated dilation and markers of endothelial function in subjects with hypercholesterolemia . METHODS We r and omly assigned 47 subjects with hypercholesterolemia to receive one HeartBar containing 3.3 g L-arginine each , or a placebo bar , consumed twice daily for 2 weeks . Flow-mediated dilation , platelet aggregation studies , and soluble levels of endothelial and platelet adhesion molecules were obtained before and after the 2-week treatment period . RESULTS Baseline and follow-up levels of L-arginine were 78.5 + /- 28.2 micromol/L and 80.7 + /- 26.7 micromol/L , respectively ( P = .54 ) . The HeartBar group had no improvement in flow-mediated dilation ; changes in brachial artery diameter at baseline and follow-up were 5.52 % + /- 3.32 % and 4.96 % + /- 2.39 % , respectively . There were also no changes in the soluble levels of E-selectin and P-selectin by treatment group . CONCLUSIONS In our study , 2 weeks of HeartBar supplementation in subjects with hypercholesterolemia showed no favorable effects on endothelial or platelet function Background / Aims : We aim ed to discover if L-arginine and selenium alone or together can increase the effect of a hypocaloric diet enriched in legumes ( HDEL ) on central obesity and cardiovascular risk factors in women with central obesity . Methods : This r and omized , double-blind , placebo-controlled trial was undertaken in 84 premenopausal women with central obesity . After a 2-week run-in period on an isocaloric diet , participants were r and omly assigned to a control diet ( HDEL ) , L-arginine ( 5 g/day ) and HDEL , selenium ( 200 µg/day ) and HDEL or L-arginine , selenium and HDEL for 6 weeks . Cardiovascular risk factors were assessed before intervention and 3 and 6 weeks afterwards . Results : After 6 weeks , L-arginine had significantly reduced waist circumference ( WC ) ; selenium had significantly lowered fasting concentrations of serum insulin and the homeostasis model assessment of insulin resistance index ; the interaction between L-arginine and selenium significantly reduced the fasting concentration of nitric oxides ( NOx ) , and HDEL lowered triglycerides ( TG ) and WC and significantly increased the fasting concentration of NOx . HDEL  reduced high-sensitivity C-reactive protein levels in the first half of the study and returned them to basal levels in the second half . Conclusion : These data indicate the beneficial effects of L-arginine on central obesity , selenium on insulin resistance and HDEL on serum concentrations of NOx and TG OBJECTIVES We determined the electrocardiographic , vascular and clinical effects of a medical food bar enriched with L-arginine and a combination of other nutrients known to enhance endothelium-derived nitric oxide ( NO ) in patients with stable angina . BACKGROUND Enhancement of vascular NO by supplementation with L-arginine and other nutrients has been shown to have clinical benefits in patients with angina secondary to atherosclerotic coronary artery disease 
    Output:
    
No difference was found in meta-analytical estimates of NOx and ADMA responses between arginine or placebo treatments .