DETERMINATION OF L-ARGININE CONTENT IN SCOTS PINE NEEDLES USING THE SAKAGUCHI TEST

Arginine can be accumulated in substantial amounts in coniferous plants whose mineral nutrition is regulated. A simple, quick, accurate and inexpensive method for determining the amino acid in coniferous plant organs is needed to improve the technique of raising the arginine level in the plants and making arginine-rich products of their needles. The aim of this study was to modificate a spectrophotometric method for determining arginine in Pinus sylvestris L. needles containing low or abnormally high levels of the amino acid using the Sakaguchi test. Our studies revealed the agents providing for maximum extraction of arginine from needles. Techniques for stripping the extract of organic compounds and chromogenic reagents for the Sakaguchi test were tested, and the wavelengths of maximum optical absorption of solvents in needle arginine content spectrophotometric analysis were determined. This method is simple, reproducible, accurate, and can be employed to quickly analyze pine needles for arginine content, in particular when developing techniques for augmenting it in coniferous plants and making arginine-rich products of coniferous needles.

Role of plasma asymmetric dimethyl-L-arginine levels in detection of pulmonary hypertension in children with CHD

ObjectivesThe objectives of this study were to evaluate the plasma levels of asymmetric dimethyl-L-arginine in children with pulmonary hypertension due to CHD before and after treatment with sildenafil and to evaluate its diagnostic and prognostic value as a biomarker in such children.MethodsA total of 60 children with CHD and 30 healthy control children matched for age and sex were recruited. Children with CHD were divided into two equal groups: the normal pulmonary pressure group (n=30) and the pulmonary hypertension group (n=30). Children with pulmonary hypertension were treated with sildenafil and were followed up for 6 months. Clinical data, haemodynamic parameters, echocardiographic examination, and asymmetric dimethyl-L-arginine levels were evaluated before and after treatment.ResultsAsymmetric dimethyl-L-arginine levels were significantly higher in patients with pulmonary hypertension than in those with CHD-only or the control group, and this increase was positively correlated with increased severity of pulmonary hypertension. Asymmetric dimethyl-L-arginine levels, mean pulmonary artery pressure, and pulmonary vascular resistance were significantly decreased after treatment with sildenafil. Moreover, asymmetric dimethyl-L-arginine level was significantly lower in patients who responded to sildenafil treatment compared with those who did not. At a cut-off point of more than 0.85 nmol/ml, asymmetric dimethyl-L-arginine has a sensitivity of 83% and a specificity of 80% to diagnose pulmonary hypertension-CHD. Asymmetric dimethyl-L-arginine has a sensitivity of 100% and a specificity of 94% to predict poor prognosis in pulmonary hypertension-CHD children at a cut-off point of 1.3 nmol/ml.ConclusionAsymmetric dimethyl-L-arginine level has a good diagnostic and prognostic value as a biomarker in children with pulmonary hypertension-CHD and can be used for following up patients with pulmonary hypertension and predicting response to treatment.

Nitric Oxide–Dependent Endothelial Dysfunction and Reduced Arginine Bioavailability in Plasmodium vivax Malaria but No Greater Increase in Intravascular Hemolysis in Severe Disease

Background Pathogenesis of severe Plasmodium vivax malaria is poorly understood. Endothelial dysfunction and reduced nitric oxide (NO) bioavailability characterize severe falciparum malaria, but have not been assessed in severe vivax malaria. Methods In patients with severe vivax malaria (n = 9), patients with nonsevere vivax malaria (n = 58), and healthy controls (n = 79), we measured NO-dependent endothelial function by using reactive hyperemia–peripheral arterial tonometry (RH-PAT) and assessed associations with arginine, asymmetric dimethylarginine (ADMA), and hemolysis. Results The L-arginine level and the L-arginine to ADMA ratio (a measure of L-arginine bioavailability) were reduced in patients with severe vivax malaria and those with nonsevere vivax malaria, compared with healthy controls (median L-arginine level, 65, 66, and 98 µmol/mL, respectively [P = .0001]; median L-arginine to ADMA ratio, 115, 125, and 187, respectively [P = .0001]). Endothelial function was impaired in proportion to disease severity (median RH-PAT index, 1.49, 1.73, and 1.97 in patients with severe vivax malaria, those with nonsevere vivax malaria, and healthy controls, respectively; P = .018) and was associated with the L-arginine to ADMA ratio. While the posttreatment fall in hemoglobin level was greater in severe vivax malaria as compared to nonsevere vivax malaria (2.5 vs 1 g/dL; P = .0001), markers of intravascular hemolysis were not higher in severe disease. Conclusions Endothelial function is impaired in nonsevere and severe vivax malaria, is associated with reduced L-arginine bioavailability, and may contribute to microvascular pathogenesis. Severe disease appears to be more associated with extravascular hemolysis than with intravascular hemolysis.