Mitogen-activated protein kinases in the porcine retinal arteries and neuroretina following retinal ischemia-reperfusion.

PURPOSE: The aim of the present study was to examine changes in the expression of intracellular signal-transduction pathways, specifically mitogen-activated protein kinases, following retinal ischemia-reperfusion. METHODS: Retinal ischemia was induced by elevating the intraocular pressure in porcine eyes, followed by 5, 12, or 20 h of reperfusion. The results were compared to those of the sham- operated fellow eye. The retinal arteries and neuroretina were isolated separately and examined. Tissue morphology and DNA fragmentation were studied using histology. Extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38, c-junNH(2)-terminal kinases (JNK), and c-jun protein and mRNA expression were examined using immunofluorescence staining, western blot, and real-time PCR techniques. RESULTS: Pyknotic cell nuclei, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, and glial fibrillary acidic protein mRNA expression were increased in ischemia, suggesting injury. Phosphorylated ERK1/2 protein levels were increased in the neuroretina following ischemia, while mRNA levels were unaltered. p38 protein and mRNA levels were not affected by ischemia. Immunofluorescence staining for phosphorylated p38 was especially intense in the retinal blood vessels, while only weak in the neuroretina. Phosphorylated JNK protein and mRNA were slightly decreased in ischemia. Phosphorylated c-jun protein and mRNA levels were higher in the neuroretina after ischemia-reperfusion. CONCLUSIONS: Retinal ischemia-reperfusion alters expression of mitogen-activated protein kinases, particularly ERK1/2, in the neuroretina and retinal arteries. The development of pharmacological treatment targeting these intracellular transduction pathways may prevent injury to the eye following retinal circulatory failure.

Mapping of transcription start sites of human retina expressed genes.

BACKGROUND: The proper assembly of the transcriptional initiation machinery is a key regulatory step in the execution of the correct program of mRNA synthesis. The use of alternative transcription start sites (TSSs) provides a mechanism for cell and tissue specific gene regulation. Our knowledge of transcriptional initiation sequences in the human genome is limited despite the availability of the complete genome sequence. While genome wide experimental and bioinformatic approaches are improving our knowledge of TSSs, they lack information concerning genes expressed in a restricted manner or at very low levels, such as tissue specific genes. RESULTS: In this study we describe the mapping of TSSs of genes expressed in human retina. Genes have been selected on the basis of their physiological or developmental role in this tissue. Our work combines in silico analysis of ESTs and known algorithm predictions together with their experimental validation via Cap-finder RACE. We report here the TSSs mapping of 54 retina expressed genes: we retrieved new sequences for 41 genes, some of which contain un-annotated exons. Results can be grouped into five categories, compared to the RefSeq; (i) TSS located in new first exons, (ii) splicing variation of the second exon, (iii) extension of the annotated first exon, (iv) shortening of the annotated first exon, (v) confirmation of previously annotated TSS. CONCLUSION: In silico and experimental analysis of the transcripts proved to be essential for the ultimate mapping of TSSs. Our results highlight the necessity of a tissue specific approach to complete the existing gene annotation. The new TSSs and transcribed sequences are essential for further exploration of the promoter and other cis-regulatory sequences at the 5'end of genes.

Estudio de Factibilidad para Evaluar la Proporción de Cáncer Atribuible a Factores de Riesgo Modificables en el Perú y Latinoamérica / Feasibility Study To Evaluate The Proportion Of Cancer Attributable To Modifiable Factors Of Risk In Peru And Latin America

Objetivo: Evaluar la factibilidad y validar de la propuesta metodológica para estimar la incidencia y mortalidad por cáncer atribuible a factores de riesgo modificables para el Perú y Latinoamérica. Métodos: Estudio piloto, ecológico a partir de fuentes secundarias. Se buscó y seleccionó los factores de riesgo modificables, prevalencia de exposicion, los riesgos relativos de dichos factores (RR) o una aproximación mediante la razón de posibilidades (OR). La información fue consignada en una ficha de recolección de datos la cual fue validada mediante juicio de expertos. Para el cálculo de la Fracción Atribuible Poblacional (FAP) se ensayó la fórmula planteada por Parkin y se desarrolló un modelo de simulación estadística con el software R. Studio V. 3.6.1. Resultados: En el Perú se cuenta con estudios de prevalencia para la mayoría de factores de riesgo modificables; asimismo, se dispone en Latinoamérica de estudios con estimaciones de OR para varios de los factores; sin embargo hubo que utilizar estudios de los Estados Unidos para los factores restantes. No hallamos estudios nacionales de radiaciones ionizantes ni ultravioleta. Se ensayó la sintaxis del modelo de simulación estadística la cual mostró ser válida y consistente con los resultados de estudios internacionales de FAP encontrándose dentro de los rangos de los estudios publicados. Conclusión: Es factible y viable realizar estudios de FAP de factores de riesgo modificables para cáncer en países de Latinoamérica, particularmente en el Perú, donde se cuenta con la información requerida para su estimación.

Objective: To evaluate the feasibility of the methodological proposal to estimate the incidence and mortality due to cancer attributable to modifiable risk factors for Peru and Latin America. Methods: Pilot study, ecological from secondary sources. Modifiable risk factors, exposure prevalence, relative risks of these factors (RR) or an approximation by means of possibilities ratio (OR) were searched and selected. The information was recorded in a data collection form which was validated by expert judgment. For the calculation of the Population Attributable Fraction (FAP), the formula proposed by Parkin was tested and a statistical simulation model was developed with R. Studio V. 3.6.1 software. Results: In Peru there are prevalence studies for the majority of modifiable risk factors; Likewise, studies with OR estimates for several of the factors are available in Latin America; however, studies from the United States had to be used for the remaining factors. No national studies of ionizing or ultraviolet radiation were found. The syntax of the statistical simulation model was tested, which proved to be valid and consistent with the results of international FAP studies within the ranges of published studies. Conclusion: It is feasible and viable to carry out PAF studies of modifiable risk factors for cancer in Latin American countries, particularly in Peru, where the information required for its estimation is available.

Xenopus paraxis homologue shows novel domains of expression.

The paraxis gene encodes a basic helix-loop-helix transcription factor that is expressed in paraxial mesoderm and whose mutant displays an inability to form epithelial somites. Here, the molecular characterization of Xenopus paraxis is reported. paraxis is expressed in the paraxial mesoderm and somites but is down-regulated during muscle differentiation. In addition to its paraxial mesodermal expression, described in other organisms, two novel expression domains of paraxis were found: the neural tube and the head mesoderm. paraxis expression in the neural tube was compared with the expression of the neural markers Xash and Xiro1, and we concluded that paraxis is expressed in a broad band in the prospective sulcus limitans of the neural tube.