Impaired L-arginine metabolism marks endothelial dysfunction in CD73-deficient mice.

Changes in the ecto-5'-nucleotidase activity-an extracellular nucleotide catabolic enzyme may lead to the inflammation and endothelial dysfunction. We investigated the effect of CD73 deletion on the endothelial function and L-arginine metabolism in various age groups of mice. 1-,3-,6-, and 12-month-old, male C57BL/6 J wild type (WT) and C57BL/6 J CD73-/- (CD73-/-) mice were used. Blood samples were used for the analysis of adenine nucleotide concentrations. Serum samples were analyzed for the concentration of amino acids, Interleukin 6 (IL-6), Intercellular Adhesion Molecule 1 (ICAM-1), Vascular Cell Adhesion Molecule 1 (VCAM-1), and endothelial nitric oxide synthase (eNOS) level. Serum and aortic nitrate/nitrite, as well as aortic arginase and NOS activity in endothelial cells (EC) were evaluated. CD73 deletion led to age-dependent increase in IL-6, ICAM-1, and VCAM-1 concentration compared to WT. All CD73-/- mice age groups were characterized by reduced L-Arginine concentration and eNOS level. Significantly lower NOS activity was noticed in EC isolated from CD73-/- mice lungs in comparison to EC isolated from WT lungs. The L-Arginine/ADMA ratio in the CD73-/- decreased in age-dependent manner in comparison to WT. The nitrate/nitrite ratio was reduced in serum and in aortas of 6-month-old CD73-/- mice as compared to WT. The ornithine/arginine and ornithine/citrulline ratios were increased in CD73-/- compared to controls. Blood (erythrocyte) Adenosine-5'-triphosphate and Adenosine-5'-diphosphate levels were reduced in favor to higher blood Adenosine-5'-monophosphate concentration in CD73-/- mice in comparison to WT. The CD73 deletion leads to the development of age-dependent endothelial dysfunction in mice, associated with impaired L-arginine metabolism. CD73 activity seems to protect endothelium.

Nonlinear methods of vehicle velocity determination based on inverse systems and tensor products of Legendre polynomials in compact car class.

The article presents research on the methods of crash velocity determination based on the Compact car class. The database used in the research is provided by the NHTSA (National Highway Traffic Safety Administration) and includes numerous frontal crash tests, which allowed the determination of the mathematical model parameters. Two methods are presented that enable the determination of vehicle velocity before the collision. The first researched method is the so-called inversed system method and is based on the assumption that the relationship between bk coefficient Cs is an inverse function. The second line of research focuses on the tensor product method, which is grounded in the Legendre polynomials, orthogonal on the interval [-1, 1] (Axler, 1997; Cheney and Kincaid, 2002). The article presents the calculation algorithm for both cases and the results with reference to the NHTSA database (Sharma et al., 2007; Siddall and Day, 1996). The application of the least square method provides more precise results in both cases than in previously researched solutions, with a slight advantage of the tensor product method. The obtained mean relative error of the velocity determination using the inverse system method is approximately 16,22% for the linear model and 10,58% for the nonlinear model. In the case of the tensor product method the errors for linear and nonlinear models are respectively 6,74% and 6,3%.