Anatomía e histología de los ciegos pilóricos en cinco especies de peces de la familia characidae / Anatomy and histology of the pyloric caeca in five species of fish of the characidae family

Se realizaron análisis macro y microscópicos de los ciegos pilóricos en las especies Mylossoma acanthogaster, M. duriventre, M. aureum, Pygocentrus cariba y Cynopotamus venezuelae, procedentes de los ríos Catatumbo, Orinoco, Apure y Cunaviche en Venezuela. P. cariba presentó mayor número ciegos pilóricos oscilando entre 14 a 34. Las especies de Mylossoma mostraron un número intermedio, mientras que el menor número se observó en C. venezuelae, con 9 a 11 ciegos. Partiendo desde el lumen hacia la capa más externa, la mucosa está constituida por pliegues largos y profundos revestidos de tejido epitelial cilíndrico simple con células caliciformes y chapa estriada; la submucosa está conformada por tejido conjuntivo laxo; la muscular está dispuesta en tres estratos de fibras musculares, excepto en M. aureum, la cual posee dos estratos y la serosa por un epitelio plano simple. La histomorfología de los ciegos pilóricos de estas especies es similar a la de la mayoría de los peces teleósteos.

Macro and microscopy analyzes on the pyloric caeca of the species Mylossoma acanthogaster, M. duriventre, M. aureum, Pygocentrus cariba and Cynopotamus venezuelae were performed. The specimens were captured in locations of the Catatumbo, Orinoco, Apure and Cunaviche rivers in Venezuela. P. cariba showed the bigger number of pyloric caeca varying with number from 14 to 34; the other studied species had a number in between, while C. venezuelae showed the smaller number varying from 9 to 11 caeca. Histologically from the lumen to the most external layer, the mucosa is formed by long and deep folds covered by single cylindrical epithelial tissue with caliciform cells, striated sheets; the submucosa is conformed by lax conjunctive tissue; the musculature consists of three strata of muscular fibers, except in M. aureum which has only two strata and the serous formed by a simple epithelial plane. The histomorphology of the pyloric caeca of these species is similar to that of the majority of teleosts.

Ca2+-activated K+ Current in Freshly Isolated c-Kit Positive Cells in Guinea-pig Stomach

This study was designed to isolate Ca2+-activated K+ current (IKCa) and elucidate its physiological significance in freshly isolated interstitial cells of Cajal (ICCs) of guinea-pig stomach. Single ICC was freshly isolated by enzymatically dissociating from myenteric border of gastric antrum free of circular muscles, and conventional whole-cell voltage clamp technique including immunohistochemical techniques were employed to characterize the cells: In myenteric border of gastric antrum, ICC-MY (ICCs from myenteric border) were detected by immunohistochemical reactivity, and single ICC-MY which has many branches was immunohistochemically c-Kit positive. Under K+-rich and 0.1 mM ethylene glycol-bis (2-aminoethyl ether)-N,N,N',N'-tetraacetic acid pipette solution, ICC produced spontaneous inward current (-256+/-92.2 pA). When step-depolarizing pulse from -80 to +80 mV was applied at holding potential (Vh) of -80 mV, voltage-dependent outward currents were recorded with superimposed spontaneous transient outward currents (STOCs). Both STOCs and outward currents were reversibly affected by tetraethylammonium chloride (TEA) and iberiotoxin (IbTX); 2 mM TEA and 200 nM IbTX completely abolished STOCs and significantly inhibited outward K+ current over the whole potential range tested for current/voltage (I/V) relationship. In addition, TEA delayed repolarization phase of spontaneous inward current. The present results indicate the presence of IKCa in a single ICC, and it might be involved in regulation of repolarizing phase of spontaneous inward current in guinea-pig stomach.

Prevalencia de Helicobacter pylori en pacientes atendidos en el Hospital San Juan de Dios, San José, Costa Rica / Prevalence and ultrastructure of Helicobacter pylori in patients attended at the hospital San Juan de Dios, San José, Costa Rica

Introducción. La prevalencia de Helicobacter pylori en población de países en desarrollo se describe como superior a la de países industrializados, por lo que es importante documentar estos datos en diferentes áreas geográficas.Material y Métodos. Se estudió su prevalencia en 236 pacientes costarricenses, de cada uno se tomó un mínimo de dos biopsias de antro, una para cultivo, frotis de aposición y una prueba de ureasa rápida; la otra para estudio histológico.Resultados. La bacteria se aisló de 121 pacientes; además se identificaron 15 más como positivos por tinción y la prueba de ureasa. El 54 por ciento presentaron algún grado de gastritis y el 81 por ciento úlceras pépticas. Discusión. La prevalencia de Helicobacter pylori en la población analizada fue del 54 por ciento lo que resulta relativamente bajo para población de un país en desarrollo. En tanto, la distribución etaria de la infección muestra un perfil típico de infección temprana en la vida con cronicidad, dado que su prevalencia aumenta con la edad.

Na+i, K+i and Cl-i regulation of exocytosis in guinea-pig antral mucous cells

Effects of intracellular Na+, K+ and Cl- on Ca(2+)-regulated exocytosis activated by 10 microM acetylcholine (ACh) were studied in guinea-pig antral mucous cells which are permeabilized by nystatin treatment. Ca(2+)-regulated exocytotic events were modulated by [Na+]i, [K+]i and [Cl-]i via mediation of PTX-sensitive G proteins. Increases in [Na+]i and PTX inhibit G protein (G(Na)), which suppressed the exocytosis. Increases in [K+]i caused the exchange of G proteins (from G(Na) to G(K)) to increase, and GK evoked activation of the exocytosis and was inhibited by PTX. Increases in [Cl-]i and PTX inhibit G protein (G(Cl)), which stimulates exocytotic events. Based on these observations, the exocytosis in antral mucous cells were modulated by intracellular ions, concentration of which were increased or decreased by cell volume changes caused by Ach.

Immunohistochemical localization of insulin-like materials in antral gastric mucosa and intestinal epithelial cells of the turtles Chrysemys dorbigni and Phrynopshilarii

Immunoreactive insulinwas demonstrated immunohistochemically with antibodies to human and porcine insulin by the avidin-biotin-peroxidase complex method in open-type gastrointestinal cells from sections of the antral stomach and of the upper, midle and lower intestine of the turtles Chrysemys dorbigni and Phrynops hilarii.In both species the concentration of cells positive for insulin-like material was higher in the gastric antrummthan in the gut.The localization of insulin-like material in gastrointestinal mucosal cells of turtles is an unusual finding among vertebrates, because the insulin-containing cells migrate from the mucosal epithelium of the intestine early in vertebrate evolution to the acinar pancreas.The chemical nature of the gastrointestinal insulin-like material and its physiological role remainm to be determined