Evaluation of wound healing effect of alginate film containing Aloe vera gel and cross-linked with zinc chloride

Abstract Purpose To develop a new wound dressing composed of alginate and Aloe vera gel and cross-linked with zinc ions. Methods The aloe-alginate film was characterized using scanning electron microscopy (SEM), swelling profile, mechanical properties, polysaccharide content and X-ray diffraction (XRD). Thirty Wistar rats were divided in two groups a) treated with aloe-alginate film and b) control (treated with sterile gauze). Wound contraction measurements and hystological analysis were performed on 7th, 14th and 21st days after wound surgery. Results The aloe-alginate film presented adequated mechanical resistance and malleability for application as wound dressing. There was no statistical difference in wound contraction between two groups. Histological assay demonstrated that aloe-alginate film presented anti-inflammatory activity, stimulated angiogenesis on proliferative phase and a more significant increased in collagen type I fibers and decreased type III fibers which promoted a mature scar formation when compared to control. Conclusions The aloe-alginate film showed adequate physicochemical characteristics for wound dressing applications. The in vivo assay demonstrated that aloe-alginate film enhanced the healing process of incisional skin wounds.

La Escuela de Salud Pública de México: innovación educativa y tecnológica en el nuevo milenio / School of Public Health of Mexico: Educational and technological innovation in the new millennium

Este artículo fue concebido para analizar la función de la Escuela de Salud Pública de México (ESPM) desde el año 2000 hasta el presente. Uno de sus puntos centrales es el análisis del proceso de reorientación de la labor educativa de la escuela con la finalidad de responder a los retos en materia de salud y educación surgidos a finales del siglo XX. Para exponer cómo ha evolucionado dicho proceso, retomamos tres ejes rectores que caracterizan la labor de la escuela en la actualidad: el cambio de modelo pedagógico, la incorporación de las tecnologías de la información y las comunicaciones, y la profesionalización de la docencia. Con la exposición de este tema, y a través del contraste entre el pasado y el presente, buscamos completar la historia de trabajo ininterrumpido de la Escuela durante sus 92 años de existencia, que ha trascendido los confines del país.

This article was conceived to analyze the work of the School of Public Health of Mexico (ESPM for is acronym in Spanish) from the year 2000 to the present day. One of the highlights that we will examine is the reorientation of the educational work of the school in order to meet the challenges in health and education that emerged during the end of the twentieth century. In order to explain the evolution of this process, we will describe the three main guiding principles that characterize the present work of the school: the pedagogical model's change, the incorporation of the information and communication technologies, and the professionalization in teaching. The purpose of this work is to define those guiding principles, and to expose, through the contrast between past and present, the complete history of uninterrupted work of the School of Public Health of Mexico during its ninety-two years of existence, that has gone beyond the boundaries of the country.

In vitro effects of three metallic salts and soot on the growth of five species of the dermatophytes.

The antifungal effects of zinc chloride (znCl), Calcium chloride (CaCl), magnesium chloride (MgCl) as well as soot collected from a local kitchens were tested on five isolated species of the dermatophytes from cases of human dermatophytoses. Of these three metallic salts, ZnCl showed the highest inhibitory effect on the dermatophytes. At a concentration of 0.01 M it showed 100% inhibition on these fungi. Although the other two metallic salts showed some inhibitory effect CaCl at concentration between 0.01 M and 1 M showed only 50% inhibitory effect while MgCl at concentration between 0.1 M and 1 M showed less than 50% inhibitory effect on the fungi. Also soot inhibited the growth of all the dermatophytes tested at concentration between 0.1 and 2%. Trichophyton rubrum and Microspum audouinii appeared to be most sensitive to these compounds compared to the other three species which include T. mentagrophytes, T. tonsurans and M. gypseum.

Specific and reversible inhibition of entamoeba histolytica cysteine proteinase activities by Zn²+: Implications for adhersion and cell damage1

Background. Cysteine-proteinases are thought to play an important role in E. histolytica pathogenicity. Although effective blockage of proteolytic activities can be obtained with sereveral known inhibitors, the high cellular toxicity of most of the inhibitors precludes experimentation with live cells or animal models. Specific cysteine-proteinase inhibitors that could be utilized in studies of virulence are of great need in the field of amebiasis. Methods. Cysteine-proteinase activities were determined in trophozoit lysates by azocasein degradation and after PAGE and gelatin zymograms. Inhibition of the activities was assessed in the presence of 0.01-2.5 mM concentrations of fivalent cations of the IIB and VIII series such as Zn, Cd, Hg, Ni, and Co. Reversibility was induced with 25 mM L-cysteine or 50 mM L-histidine and by metal chelation with 5 mM phenantroline. The inhibitory effect of ZnCI2 was tested with live cells in fibronectin-biding and cytotoxicity assays. Results. ZnCI2 specifically inhibited cysteine-proteinase activities in trophozoite lysates in a concentration-dependent manner. Additionally, 1.0-2.5 mM ZnCI2 bloked proteolysis in more than 70 percent. This inhibition was completely reverted by L-cysteine, L-histidine, or phenantroline. Similar results were obtained by analyzing indivual cysteine-proteinase activities separated in gelatin zymograms. At these concentrations, ZnCI2 significanty interfered with trophozoit adhesion, thus making amebas deficient in substrate degradation and cell damage. Conclusions. ZnCI2 is effective inhibitor of amebic cysteine-proteinases. Its low toxicity at relative high concentrations, high solubility, and low cost make it adequate for live cell experimentation and animal models of amebic virulence

Perfil cinético, aspectos farmacológicos e lesÝo gástrica do piroxicam-zinco em ratos / Kinetic profile, pharmacological aspects and gastri lesion of the zinc-piroxicam in rats

O perfil plasmático do piroxicam em ratos Wistar machos (180+- 20g) foi analisado, após administraçÝo do complexo piroxicam-zinco e do piroxicam livre. Os parâmetros farmacocinéticos obtidos mostraram que a complexaçÝo do piroxicam com o zinco prolonga o tempo de absorçÝo. O 'T IND. MAX' do piroxicam no grupo do complexo foi de 5,27 h e de 2,56 h para o piroxicam livre. Os demais parâmetros farmacocinéticos foram semelhantes, na comparaçÝo dos dois. Na avaliaçÝo farmacológica, utilizando modelos de inflamaçÝo experimental - edema agudo de pata induzido pela carragenina (processo agudo), formaçÝo do tecido granulomatoso pela implantaçÝo de discos de algodÝo (processo subcrônico), artrite induzida pelo adjuvante Completo de Freund (processo crônico) e inibiçÝo da dor causada por pressÝo - nÝo houve diferença estatisticamente significante entre o piroxicam livre e seu derivado. A diferença observada nesses experimentos ocorreu somente em relaçÝo ao início da atividade do piroxicam, na inibiçÝo do edema de pata e na analgesia, onde a instalaçÝo do efeito é retardada com o complexo, provavelmente, face à absorçÝo mais lenta. Com relaçÝo ao efeito irritante do piroxicam na mucosa gástrica, a administraçào do piroxicam-zinco determinou menor açÝo gastrotóxica com diferença estatísticamente significante quando comparado à do piroxicam livre

Changes induced by zinc on thyroxine deiodination by rat liver in vivo and in vitro

Se estudió el efecto de la administración in vivo o del agregado in vitro de zinc sobre la deiodinación 5'de la tiroxina (T4) por el hígado de rata y sobre la concentración hepática de grupos sulfhidrilos libres (NPSH). Se usaron ratas Wistar macho de 200-240g de peso corporal. A un grupo de 12 ratas se les inyectó i.p. sulfato de zinc 2mg/Kg de peso, 24h antes de iniciar el estudio. Se sacrificaron los animales por dislocación cervical y el hígado fue inmediatamente homogeneizado. Se agregó a los homogenatos dithithreitol (DTT) (0,2.5,5 o 10mM concentración final) y 1µCi de 125I-T4. Para los estudios in vitro en animales sin tratar, se agregó al homogenato de hígado sulfato de zinc o cloruro de cadmio (2.5 o 5mM) más DTT y T4 marcada. Todos los homogenatos fueron incubados durante 90 min a 37ºC y luego cromatografiados en papel Whatman 1. Las ratas inyectadas con zinc tuvieron una disminución significativa (p<0.01) de la deiodinación de T4, de la producción de 125 iodo (P<0.02) y de triiodotironina (T3) (P<0.05). En los estudios in vitro, el agregado de zinc o cadmio disminuyó significativamente la degradación de T4 (P<0.02) y la producción de iodo (P<0.02 para el zinc y P<0.05 para el cadmio) y de T3 (P<0.05). La concentración hepática de NPSH en los animales inyectados con zinc fue normal. La concentración sérica de T4 y T3 en los animales inyectados con zinc fue normal pero en los inyectados con cadmio se redujo significativamente (P<0.01 para T4 y P<0.02 para T3). Los resultados indican que el zinc inhibe la actividad de la 5'-deioidnasa hepática, por um mecanismo probablemente relacionado con la unión del metal a los grupos sulfhidrilos de la enzima

Kinetic studies on the membrane form of intestinal alkaline phosphatase

We have purified different membrane and soluble forms of alkaline phosphatase from human placenta and bovine intestine. The enzymes will be used as markers in immunoconjugates and/or as model for membrane enzyme studies. The membrane formof alkaline phosphatase extracted from bovine intestine was purified on Q-Sepharose and on L-histidyldiazobenzylphosphonic acid-agarose columns to remove phosphodiesterase activity. The purified enzyme had a molecular mass of 61 kDa, Km of 1208 µM, and Vmax 240 µmol pNP/min when assayed in 1 M diethanolamine, 0.5 mM MgCl2 buffer, pH 9.8, containing 10 to 2250 µM of pNPP at 37§C. In the present investigation we studied the effect of salts and inositol derivatives on this enzyme activity, which was found to depend on 0.5 mM Mg2+, and to be fully inhibited by 1.2 mM Hg2+. Vanadate (0.5 mM) and Zn2+ (0.5 mM) reduced the Km value by 43 percent and 84 percent, respectively. Inositol (2 mM) and inositol-2-monophosphate (2 mM) reduced the activity by 23 percent and 17 percent. Inositol-1-monophosphate (0.5 mM) and cyclic-inositol-(1:2)-monophosphate (0.5 mM) enhanced their Km value by at least 30 percent compared to p-nitrophenylphosphate