Incorporation of an Intermediate Polyelectrolyte Layer for Improved Interfacial Polymerization on PAI Hollow Fiber Membranes.

In a single-step spinning process, we create a thin-walled, robust hollow fiber support made of Torlon® polyamide-imide featuring an intermediate polyethyleneimine (PEI) lumen layer to facilitate the integration and covalent attachment of a dense selective layer. Subsequently, interfacial polymerization of m-phenylenediamine and trimesoyl chloride forms a dense selective polyamide (PA) layer on the inside of the hollow fiber. The resulting thin-film composite hollow fiber membranes show high NaCl rejections of around 96% with a pure water permeability of 1.2 LMH/bar. The high success rate of fabricating the thin-film composite hollow fiber membrane proves our hypothesis of a supporting effect of the intermediate PEI layer on separation layer formation. This work marks a step towards the development of a robust method for the large-scale manufacturing of thin-film composite hollow fiber membranes for reverse osmosis and nanofiltration.

Molecular characterization of Marek's disease virus in a poultry layer farm from Colombia.

Marek's disease (MD) is a lymphoproliferative disease caused by an Alphaherpesvirus, genus Mardivirus, serotype 1 (Gallid Herpesvirus 2, GaHV-2) that includes all known pathogenic strains. In addition to Marek's disease virus (MDV) serotype 1, the genus includes 2 distinct nonpathogenic serotypes: serotype 2 (GaHV-3) and serotype 3 (Meleagridis Herpesvirus 1, MeHV-1) which are used in commercially available vaccines against MD. As a result of vaccination, clinical signs are not commonly observed, and new cases are usually associated with emerging variant strains against which the vaccines are less effective. In this study, a commercial layer farm showing clinical signs compatible with MDV infection was evaluated. Histological lesions and positive immunohistochemistry in the sciatic nerve and thymus were compatible with cytolytic phase of MD. GaHV-2, GaHV-3 and MeHV-1 were identified by PCR and qPCR in blood samples from 17 birds with suspected MD. Analysis of the Meq gene of the Colombian GaHV-2 isolate revealed a 99% sequence identity with Asian strains, and in the phylogenetic analysis clustered with vv+ MDV. The analysis of amino acid alignments demonstrated an interruption of the proline rich region in P176A, P217A and P233L positions, which are generally associated with vv+ strains. Some of these changes, such as P233L and L258S positions have not been reported previously. In addition, primary cell cultures inoculated with lymphocytes isolated from the spleen showed typical cytopathic effect of GaHV-2 at 5 d post infection. Based on the molecular analysis, the results from this study indicate the presence of vv+ MDV infection in commercial birds for the first time in Colombia. It is recommended to perform further assays in order to demonstrate the pathotype characteristics in vivo.

Expresión diferencial durante la interacción Solanum tuberosum - Phytophthora infestans / Differential expression during Solanum tuberosum- Phytophthora infestans interaction

La papa (Solanum tuberosum L.) es el cuarto cultivo más importante a nivel mundial y es el producto agrícola con mayor demanda de fungicidas, insecticidas y fertilizantes quí­micos. Las pérdidas mundiales ocasionadas por Phytophthora infestans (Mont.) de Bary en este cultivo, ascienden a 6,7 billones de dólares al año y su control quí­mico genera un aumento en los costos, perjudica la salud humana y el ambiente. Todo esto justifica la búsqueda constante de mecanismos alternativos para el control de la enfermedad, entre ellos la obtención de variedades resistentes mediante cisgenesis usando genotipos silvestres. Como un aporte en este sentido, y dada la falta de conocimiento de lo que controla y constituye la diferencia entre una respuesta compatible e incompatible, en el presente estudio se compararon los perfiles de expresión génica obtenidos mediante Despliegue Diferencial de variedades resistentes y susceptibles durante su interacción con P. infestans. Los resultados evidenciaron diferencias en la expresión génica, tanto a distintos tiempos post-inoculación como en el tipo de cambio de expresión, incluyendo la presencia y ausencia de bandas diferenciales y el aumento o disminución en su intensidad. Al analizar las secuencias de fragmentos diferencialmente expresados, se encontró que algunos fragmentos sobre-expresados en las variedades susceptibles, tení­an homología con secuencias que codifican para una serina-acetiltranferasa y para la subunidad Β de la RNA polimerasa. Por su parte, fragmentos sobre-expresados en la variedad resistente, tení­an homología con una secuencia codificante para un dominio transmembranal.

Potato (Solanum tuberosum L.) is the fourth most important crop worldwide; also, is the agriculture product with most fungicides, insecticides and chemical fertilizers requirement. Worldwide losses caused by Phytophthora infestans (Mont.) de Bary in this crop, amount to 6,7 billion dollars per year and its chemical control increase production costs, harming human health and environment. For these reasons, is necessary constant research for alternative mechanisms to control disease, including development of resistant varieties using cis-genesis from wild genotypes. As a contribution in this way, and the lack of knowledge of what controls and is the difference between compatible and incompatible interaction, in this study we compared gene expression profiles obtained by Differential Display from resistant and susceptible varieties, during their interaction with P. infestans. The results showed differences in gene expression between resistant and susceptible varieties, at different times post-inoculation as well as exchange expression rate, including the presence and absence of differential bands and increase or decrease in their intensity. After analyzing the sequences of differential expressed fragments, we found that some overexpressed fragments from susceptible varieties had homology with an encoded sequence for a serine-acetyltransferase and for a RNA Polymerase Β subunit. On the other hand, overexpressed fragments from resistant variety, had homology with an encoded sequence for a transmembrane domain.

The insulin gradient phenomenon: a manifestation of the effects of body weight on blood pressure and insulin resistance.

The relationship between hyperinsulinemia and hypertension is frequently observed in overweight patients; however, population studies have not confirmed an independent association. A population study was conducted to assess whether differences in body mass index and levels of insulinemia modify cardiovascular hemodynamics and arterial pressure. In all, 322 healthy adults underwent a medical evaluation including insulin sensitivity and cardiac performance assessment with echocardiography. A direct relationship between body mass index and blood pressure (r=0.36; P<.01) was shown along with increments in fasting insulin levels. The underlying and progressive rise in insulin levels during blood pressure increase is named the insulin gradient. Left ventricular systolic indexes were significantly greater in the higher-insulin quartile. These findings suggest that body weight increases accompany a rise in systolic pressure and a drop in insulin sensitivity related to the insulin gradient. Increments in ejection fraction and cardiac output with normal total peripheral resistance are related to the blood pressure shift in these persons.

Screening for conduct disorder in an adolescent male sample from Colombia.

This study assessed the validity, reliability, and utility of a screening measure for detecting the signs or symptoms of Conduct Disorder in male adolescents from schools in Medellín, Colombia. A first study examined the differences between 70 male offender adolescents (aged 12-16 years) attending alternative education institutions, and 68 (sex, age, and socioeconomic status (SES)-matched) adolescent controls attending regular schools. A CD checklist (CD-CL) was constructed to be used by mothers (CD-CL-M) and for self-report by adolescents (CD-CL-SR). The validity of the screener for CD diagnosis was supported by significant differences between groups (ANOVA, p<.001). The CD-CL-SR had better sensitivity/specificity with a diagnostic cut-off point of 5 (sensitivity=95.3% and specificity=90.5%) than the CD-CL-M. A second study used the CD-CLSR with a random sample of 190 male adolescents (aged 12 to 16 years) from schools of low, middle and high SES. Reliability as assessed by Cronbach's alpha was 0.86. An epidemiological cut point of 5 classified 35.5% of the adolescents assessed as probable CD cases. A psychometric cut point at T score>59 (85th percentile) estimated 16.8% of the sample as probable CD cases. A psychometric cut point at T score>64 (90th percentile) revealed that 10.5% of the sample would be severe CD cases. Some significant differences (p<0.001) in proportions of CD adolescents were found between age and SES groups. It was concluded that such a high frequency of conduct problems in adolescence argues for the need for preventive programs in Colombian schools.