Internet addiction among Czech adolescents.

Our study estimates the prevalence of Internet addiction in Czech adolescents as well as differences by gender and school type. A total of 3,950 adolescents (n = 1,940 boys, n = 2,010 girls) from 11 to 19 years of age (M = 15.73, SD = 1.

Nitrate reductase from Triticum aestivum leaves: regulation of activity and possible role in production of nitric oxide.

Nitrate reductase (NR) and peroxidase (POX) are important enzymes involved in the metabolism of reactive oxygen (ROS) and nitrogen species in leaves of wheat (Triticum aestivum L.) seedlings. It has been confirmed that NR activity in wheat leaves depends on the light conditions and the presence of nitrates during the cultivation of the seedlings, and it is regulated by the molybdenum cofactor and phosphorylation.

Production of hydrogen peroxide and nitric oxide following introduction of nitrate and nitrite into wheat leaf apoplast.

Infiltration of wheat (Triticum aestivum L.) seedling leaves with excess of nitrate, nitrite, or the NO donor sodium nitroprusside leads to increase both in content of hydroperoxide and activity of peroxidase and decrease in superoxide dismutase (SOD) activity in the leaf apoplast. Polymorphism of extracellular peroxidases and the presence of Cu/Zn-SOD have been shown in apoplast.

[Isosteric triphosphonate analogues of dNTP: synthesis and substrate properties toward various DNA polymerases].

Isosteric triphosphonate derivatives of 2',3'-dideoxy-2',3'-didehydroadenosine and 3'-deoxy-2',3'-didehydrothymidine and their beta,gamma-substituted analogues were synthesized. Their substrate properties toward a number of reverse transcriptases of the human immunodeficiency and bird myeloblastosis viruses, human DNA polymerases alpha and beta, and the Klenow fragment of Escherichia coli DNA polymerase I were studied.