Adenylyl cyclase types I and VI but not II and V are selectively inhibited by nitric oxide

Adenylyl cyclase (AC) isoforms catalyze the synthesis of 3',5'-cyclic AMP from ATP. These isoforms are critically involved in the regulation of gene transcription, metabolism, and ion channel activity among others. Nitric oxide (NO) is a gaseous product whose synthesis from L-arginine is catalyzed by the enzyme NO synthase. It has been well established that NO activates the enzyme guanylyl cyclase, but little has been reported on the effects of NO on other important second messengers, such as AC. In the present study, the effects of sodium nitroprusside (SNP), a nitric oxide-releasing compound, on COS-7 cells transfected with plasmids containing AC types I, II, V and VI were evaluated. Total inhibition (98.5 percent) of cAMP production was observed in COS-7 cells transfected with the AC I isoform and previously treated with SNP (10 mM) for 30 min, when stimulated with ionomycin. A high inhibition (76 percent) of cAMP production was also observed in COS-7 cells transfected with the AC VI isoform and previously treated with SNP (10 mM) for 30 min, when stimulated with forskolin. No effect on cAMP production was observed in cells transfected with AC isoforms II and V

Immuno and cytochemical localization of Trypanosoma cruzi nitric oxide synthase

The localization and subcellular distribution of Trypanosoma cruzi nitric oxide synthase was investigated in epimastigote cells by immunocytochemistry at electron and light microscope level, using a polyclonal antibody to neuronal nitric oxide synthase, and also, at light microscope level, by the nicotinamide adenine dinucleotide phosphate-diaphorase histochemical reaction. The immunoreactivity was ultrastructurally localized by electron microscopy in the inner surface of cell membranes and in free cytosolic clusters in the body, flagellum and apical extreme. Light microscopy showed that immunoprecipitates, specific for the Trypanosoma cruzi nitric oxide synthase, co-localized with the formazan precipitates generated by the diaphorase reaction in the same areas identified by electron microscopy. These results, taken together with previous finding from our laboratory could help to explain the involvement of the nitric oxide transduction pathway in T. cruzi epimastigote motility.

Distribution of GABA in the golden hamster retina: An immunocytochemical study

Distribution of the inhibitory neurotransmitter GABA was studied in the golden hamster retina using immunocytochemistry at cellular and subcellular levels. GABA-immunoreactivity was observed in somata of amacrine, displaced amacrine and horizontal cells. GABA immunoreactive fibers were abundant in the inner plexiform layer. Ultrastructural analysis exhibited dense GABA-immunoreactive deposits in amacrine cell somata, processes and terminals. Immunolabelling was also observed in the cytoplasm of horizontal or interplexiform cells and displaced amacrine cells. In every case DAB deposits were observed in the cytosolic compartment, attached to the inner surface of cell membranes and to outer mitochondrial membranes. Immunolabeled terminals predominated in the inner plexiform layer and immunoprecipitates were also observed attached to the outer face of vesicle membranes as well as completely filling synaptic vesicles. Both clear and dense core vesicles were observed. The present results are similar to those obtained in other mammalian species showing GABA immunoreactivity in amacrine, displaced amacrine and horizontal cells

Resección de colon con invasión mínima: colectomía laparoscópica / Colonic resection with minimal invasive technique: laparoscopic coletomy

El éxito de la aplicación de la cirugia laparoscópica en enfermedades de la vesicula y en la apendicitis aguda, ha estimulado a los investigadores a desarrollar avances tecnológicos en un intento para tratar otro tipo de patologias del tracto digestivo. Despues de adquirir experiencia con diversas formas de laparoscopia, y mientras que se perfeccionaba la cirugia clinica del tracto blliar y del apendice y se adelantaban trabajos controlados en animales de laboratorio, se inició un programa piloto para cirugia laparoscópica del colon. Veinte pacientes con rango de edad entre 43 y 88 años, para una edad promedio de 57 años, se sometieron a resección del colon por laparoscopia. En 9 pacientes se realizó hemicolectomía derecha y en 8, sigmoidectomia. El procedimiento de Hartman (resección antero-inferior), y la resección perineoabdominal, fueron realizadas cada una en 1 paciente. Las indicaciones de la cirugia fueron los adenomas vellosos de gran tamaño o adenocarcinoma del colon, en 12 pacientes; enfermedad diverticular, en 5; endometrioma del sigmoide en 1; volvulus cecal en 1 y enfermedad inflamatoria intestinal en 1. El 80 por ciento de los pacientes toleraron dieta liquida en el primer dia posoperatorio y el 70 por ciento fueron dados de alta a las 96 horas con dieta corriente y deposición normal. Se presentaron tres complicaciones quirurgicas: 1) Un paciente presento sangrado posoperatorio que requirió 3 unidades de sangre, tratado sin cirugia. 2) Un paciente desarrolló un edema marcado de la anastomosis rectosigmoidea que requirió descompresion con sonda rectal. 3) Un paciente con cancer metastasico del colon presentó una obstruccion mecánica del intestino delgado 7 dias despues de la cirugia laparoscopica del colon. Aunque la cirugia laparoscopica esta considerada como un procedimiento en evolucion, se piensa que en el future sera potencialmente popular tanto como la colecistectomia laparoscopica.