Comparison of the biochemical properties, regulation and function of ATP-diphosphohydrolase from human placenta and rat kidney

ATP-diphosphohydrolase (apyrase, EC 3.6.1.5) has both ATPase and ADPase activity that are stimulated by bivalent metais, with Ca2+ being the most effective. The possible physiological function of this enzyme, associated with placental and renal microvilli, is related to the extracellular metabolism of nucleotides. A comparison of the biochemical properties of human placenta and rat kidney apyrase is presented, showing similaiities in Mr, bivalent metal stimulation, nucleotide nonspecificity, insensitivity towards specifjc ATPase inhibitors, and lack of essential sulfhydryl and aliphatic hydroxyl groups. We describe the treatment of membrane preparations from both tissues with different detergents and the isoelectric focusing of the solubilized proteins to partially purify apyrase. An ectoenzyme localization is assigned both in microvillus membranes and in the vasculature on the basis of organ perfusion experiments with nucleotides in the presence of antibodies. Placental and kidney microvillus membranes inhibited ADP-induced platelet aggregation, in agreement with an extracellular role. Initial studies on enzyme regulation suggested the existence of at least two types of modulatory proteins: an activating protein in the cytosol of both tissues, and an inhibitory protein associated with placental microsomes. Possible hormonal regulation was investigated in kidneys using in vivo estradiol treatment, but only slight changes in total apyrase activity were observed.

Alternativas en el tratamiento de la extrofia vesical. / Alternatives in the treatment of bladder extrophy

La extrofia vesical es una de las entidades donde mas controversia hay en cuanto a su tratamiento. Sabemos que actualmente se efectua el cierre primario y plastia del cuello y/o colocacion de un esfinter, pero esto no es aplicable en nuestro medio. Por esta razon empleamos la derivacion urinaria a colon, que nos ha dado buenos resultados. Sabemos que podria presentarse en el futuro una probable neoplasia. Sin embargo, la calidad de vida que brindamos a nuestros pacientes es muy aceptable

Accion clastogenica de un compuesto antraquinonico en linfocitos humanos. / Clastogenic action of an anthraquinone compound in human lymphocytes

Algunos autores han senalado una accion mutagenica para los compuestos antraquinonicos en sistemas microbianos, ya sea en forma directa o por activacion metabolica por sistema microsomal. Los compuestos mencionados tienen una amplia difusion como colarantes alimenticios, cosmeticos, farmacos y laxantes. En el presente trabajo se realizo un estudio in vitro del efecto clastogenico de un derivado antraquinonico sintetico, la l-8 Dihidroxiantraquinona y el solvente en el que se solubiliza la droga, el Dimetilsulfoxido, en cultivo de linfocitos de sangre periferica humanos Los resultados obtenidos permiten concluir que la droga ensayada presenta accion clastogenica en el sistema de ensayo aqui utilizad