Effect of endogenous L-arginine on the measurement of nitric oxide synthase activity in the rat kidney

The endogenous level of L-arginine in renal cortex, outer medulla, and inner medulla and its effect on the measurement of nitric oxide synthase (NOS) activity in these regions was determined. L-Arginine was measured with an amino acid analyzer and total NOS activity was measured as the rate of formation of radiolabeled L-citrulline from L-[14C]arginine. Total NOS activity was that activity inhibited by NG-nitromonomethyl-L-arginine (300 microM). The endogenous L-arginine concentration was 452 +/- 45 (mean +/- SEM), 313 +/- 25, and 95 +/- 8 pmol/mg wet weight in the cortex, outer medulla, and inner medulla, respectively (n = 12). Total NOS activity was 61 +/- 19, 709 +/- 94, and 1347 +/- 76 pmol.h-1.mg protein-1 in the cortex, outer medulla, and inner medulla, respectively, when endogenous L-arginine was not considered in the calculation. Correcting for endogenous L-arginine gave values of 185 +/- 61, 1714 +/- 239, and 1707 +/- 104 pmol.h-1.mg protein-1, respectively. Dowex extraction to remove endogenous L-arginine from samples also increased NOS activity in cortex and medulla. The data indicate that there is a differential distribution of endogenous L-arginine in the kidney and that these levels must be taken into account when measuring NOS activity. NOS activity is also distributed differentially, with activity in the medulla being nearly 10-fold higher than in the cortex.     

Analysis of heart rate dynamics based on nonlinear lagged returned map for sudden cardiac death prediction in cardiovascular patients

Multidimensional Systems and Signal Processing - Sudden cardiac death (SCD) generally applied to an unpredicted death from a cardiovascular cause in a subject with or without preexisting heart...     

Influence of geometry on legibility: An explanatory design study of visitors at the Kuala Lumpur City Center

Legibility is based on landmarks and geometry. Visitors in a space learn to “read” an area by using three-and two-dimensional cues. This research aimed to determine the responses of visitors to the influence of geometry on the legibility at Kuala Lumpur City Center (KLCC). The relationship between geometry and space legibility can affect visitors' wayfinding. In this study, visitors, including 86 respondents and 8 individuals who participated in a focus group, were surveyed through questionnaires and interviews during daytime. Results show that legibility was moderately and positively correlated with regular geometry, but legibility was negligibly affected by existing geometry. Regression analysis, t-test, ANOVA, and scheme coding of qualitative data suggested that regular geometry used in urban spaces might strongly improve legibility. For urban designers, regular geometry associated with landmarks enhances legibility.