Bone-like apatite coating on Mg-PSZ/Al2O3 composites using bioactive systems.

A biomimetic method was used to promote bioactivity on zirconia/alumina composites. The composites were composed of 80 vol% Mg-PSZ and 20 vol% Al2O3. Samples of these bioinert materials were immersed in simulated body fluid (SBF) for 7 days on either a bed of wollastonite ceramics or bioactive glass. After those 7 days, the samples were immersed in a more concentrated solution (1.4 SBF) for 14 days. Experiments were also performed without using a bioactive system during the first stage of immersion. A bone-like apatite layer was formed on the surface of all the materials tested, using wollastonite the bioactive layer was thicker and its morphology was close to that observed on the existing bioactive systems. A thinner apatite layer consisting of small agglomerates was obtained using bioactive glass. The thickness of the ceramic layers was within the range of 15 to 30 microm.

Bioactivation of a cobalt alloy by coating with wollastonite during investment casting.

Cobalt alloy samples were bioactivated during investment casting. The cavities of the investment mold were previously coated with wollastonite. Additionally, before coating with wollastonite, some mold cavities were filled out with graphite rods to avoid a chemical reaction between the wollastonite powder and the investment material. Half of the cast samples were heat treated at 1220 degrees C for 1 h. To perform the in vitro bioactivity assessment, the cast and heat-treated samples were immersed in a simulated body fluid solution (SBF) for a period of 21 days. The surface of the samples before and after immersion in SBF was characterized by SEM, EDX, and XRD analyses. During the casting, particles of pseudowollastonite were embedded on the metallic surface. After immersion of the samples in SBF, a ceramic layer was formed on both the alloy obtained by using the investment mold and the alloy obtained by using the graphite-filled cavity. The ceramic layer was thicker on the alloy cast in the investment mold. The layer was identified as hydroxyapatite by XRD analysis, in all the cases. The heat-treated samples after immersion in SBF showed the formation of a thin homogeneous layer consisting of fine grains of apatite.

Effect of wollastonite ceramics and bioactive glass on the formation of a bonelike apatite layer on a cobalt base alloy.

A biomimetic method was used to promote a bioactive surface on a cobalt base alloy (ASTM F-75). The metallic substrates were alkali treated and some of the samples were subsequently heat treated. The treated samples were immersed in simulated body fluid (SBF) on granular particles of either bioactive glass or wollastonite. For comparative purposes, no bioactive system was used in some tests. Three different methods were used for the immersion of the samples in SBF: 1) 21 days in SBF, 2) 21 days in 1.5 SBF, and 3) 7 days in SBF followed by 14 days in 1.5 SBF (re-immersion method). A bonelike apatite layer was formed on all the samples placed on wollastonite and bioactive glass particles. The morphology of the apatite layer formed by using the re-immersion method and wollastonite closely resembled the existing bioactive systems. No apatite layer was observed on the samples treated without bioactive material and soaked for 21 days in SBF or 1.5 SBF, apart from the substrates treated by using the re-immersion method. The heat treatment delayed the apatite formation in all the cases studied.

Genetic-environment analysis of sensitivity and acute tolerance to ethanol in mice.

The purpose of this study was to characterize initial sensitivity (IS), acute functional tolerance (AFT), and rate of tolerance development to ethanol in lines of mice selected for aggression mice as well as to investigate the impact of isolate housing on these phenotypes. The results showed that for IS, there were no differences among treatment groups. For acute tolerance and rate of tolerance development, a Line x Sex x Housing interaction was present, with the response to housing being more pronounced in the low aggressive line than the high aggressive line, and the females being more affected than the males. Correlational analysis showed low to moderate associations between rate of tolerance development and IS, as well as between rate of tolerance and AFT. Housing condition significantly influenced female expression of ethanol phenotypes as compared to males. The line of the subject also influenced the magnitude of expression of these phenotypes. These findings suggest that environmental and genetic influences interact to influence acute tolerance and rate of tolerance development.

Estudios preliminares de la actividad citotóxica de muérdagos mexicanos: Cladocolea grahami, Phoradendron reichenbachianum y Phoradendron galeottii (Loranthaceace) / Preliminary studies on the cytitixic activity of Mexican muérdagos: cladocolea grahamani, phoradendron reichenbachianum and phoradendron galeotti (Loranthaceae)

Algunas de las especies vegetales conocidas comúnmente como muérdagos han sido utilizadas popularmente en México para tratar diversas afecciones entre las que figura el Cáncer. Con el propósito de investigar experimentalmente y en forma preliminar la posible acción antitumoral de las tres especies de muérdagos mexicanos: Cladocolea grahami, Phoradendron reichenbachianum y Phoradendron galeottii, en el presente trabajo se determinaron actividades citotóxicas de los extractos hexánicos y metanólicos de diferentes órganos (tallo, inflorescencia y hoja) de estas plantas, sobre cultivos de cuatro líneas celulares provenientes de cánceres humanos: OVCAR-5 (carcinoma de ovario), KB (carcinoma nasofaríngeo), UISO-SQC-1 (células escamosas de carcinoma de cérvix) y HCT-15 COLADCAR (carcinoma de colon), así como de una leucemia murina P388. Los resultados obtenidos se expresan como las dosis de los extractor vegetales que inhibieron el 50 por ciento del crecimiento celular respecto a cultivos control durante las fases de crecimiento celular exponencial (ED50); y muestran que las tres especies presentaron actividades en dos o más de los órganos analizados contra los cultivos OVCAR, P388 Y UISO; ninguna presentó actividad importante contra el cáncer de colon HCT-15 y sólo P. reichenbachianum fue activa contra las células KB