Pikeperch (Sander lucioperca) spermatozoa motility and volume regulation under different osmotic and ionic conditions.

Pikeperch (Sander lucioperca) is a highly profitable commercial species whose economic value has greatly increased in the last decade. As in other species, the quality of spermatozoa in this species is a principal feature inherent in fertilization success and efficient natural and artificial reproduction. The capacity of fish spermatozoa to be activated and tolerate environmental changes (in osmolality, ion composition, external pH, temperature, etc.) during the motility period contributes to fertilization success. In this study, we investigated the effects of environmental osmolality and ion composition on spermatozoa motility. To determine if the activation mechanism is affected by sperm quality parameters, we measured semen characteristics such as semen volume, spermatozoa concentration, seminal fluid osmolality and ion composition, and spermatozoa lipid composition. An additional parameter of sperm quality reflecting spermatozoa osmoresistance, the swelling rate, was measured by the nephelometry method. We detected that sperm samples with the highest content of palmitic (C16:0) and palmitoleic (C16:1) acids showed the lowest motility activation under the studied conditions, suggesting that these fatty acids are possible markers for the determination of spermatozoa quality in fish. Our results show that pikeperch spermatozoa can be activated under different osmotic conditions and that cell swelling always accompanies motility. However, spermatozoa sustain their volume under hypotonic conditions when motility is not initiated, suggesting that pikeperch spermatozoa activation is mainly controlled by ion composition rather than the osmolarity of the surrounding medium.

Osmoregulation in fish sperm.

In most fish exhibiting external fertilization, spermatozoa become motile after release into water, triggered by differences between intracellular and extracellular conditions such as osmotic pressure, ion composition, and pH. The rapid change in osmolarity initiating spermatozoon motility induces osmotic pressure, resulting in active water movement across the cell membrane. Mechanisms of ion and water transport across the plasma membrane and cell volume regulation are important in maintaining structure and functional integrity of the cell. The capacity of the fish spermatozoon plasma membrane to adapt to dramatic environmental changes is an essential prerequisite for motility and successful fertilization. Adaptation to change in external osmolality may be the basis of spermatozoon function and an indicator of sperm quality. The involvement of specific water channels (aquaporins) in cell volume regulation and motility is highly likely. The goal of this review is to describe basic mechanisms of water transport and their role in fish spermatozoon physiology, focusing on osmoresistance, cell volume regulation, motility, and survival.

Hemocultivos en el Hospital Nacional de Niños. Experiencia de 9 años 1995-2003 / Hemoculture in the Hospital Nacional de Niños. Experience of 9 years 1995-2003

El presente informe, muestra los agentes bacterianos aislados en cultivos de sangre por un periodo de 9 años y en donde se empleó el sistema automatizado Vital de la Casa bioMerieux. Se presenta la información desglosado por agentes Gram positivo y Gram negativo, anaeróbios y levaduras.

Evolución del tratamiento de la tuberculosis en Colombia / Evolution of the treatment of tuberculosis in Colombia

Con base en los artículos escritos por autores colombianos entre 1.901 y 1.976, se persiguió identificar el concepto de la Tuberculosis y su correlación con el tratamiento dado en cada una de las diferentes etapas de su evolución. Para ello, cada uno de los artículos fue reseñado y clasificado de acuerdo a su contenido en categorias así: diagnóstico, tratamiento, enfermedad general o mixto, para luego reclasificarlos según sus aportes, dando así las herramientas al análisis final. Durante el análisis se identificaron varios periodos internos no siempre hallándose correlación entre el concepto y el tratamiento antituberculoso. Además se encontró que el tratamiento es un reflejo del avance médico extranjero, el cual se copia y aplica en el medio colombiano