Relación entre conciencia fonológica y el nivel de decodificación lectora en estudiantes educación primaria de la Institución Educativa 4004 San Martín de Porres, La Perla - Callao

La presente investigación tuvo como objetivo general Establecer la relación que existe entre la conciencia fonológica y el nivel de decodificación lectora en estudiantes educación primaria de la Institución Educativa 4004 San Martín de Porres. La Perla – Callao. El enfoque de la investigación fue cuantitativo y como diseño utilizó el diseño descriptivo correlacional, el tamaño de la muestra estuvo constituida por 20 estudiantes del tercer grado de educación primaria de la Institución Educativa 4004, el tipo de muestreo que se aplicó fue por conveniencia, los instrumentos que se aplicaron fueron: la prueba exploratoria de dislexia específica de Condemarín y Blomquist, así como test de habilidades metalingüísticas de P. Gómez; J. Valero; R. Buades y A. Pérez. Los resultados de la investigación demostraron que existe evidencia para afirmar que existe relación entre la conciencia fonológica y el nivel de decodificación lectora en estudiantes del 3er grado de educación primaria de la Institución Educativa 4004 San Martín de Porres. La Perla – Callao.The general objective of this research was to establish the relationship between phonological awareness and the level of reading decoding in primary education students of the Educational Institution 4004 San Martín de Porres. La Perla - Callao. The research approach was quantitative and as a design it used the correlational descriptive design, the sample size consisted of 20 students of the third grade of primary education of the Educational Institution 4004, the type of sampling that was applied was for convenience, the Instruments that were applied were: the exploratory test for specific dyslexia by Condemarín and Blomquist, as well as the metalinguistic skills test by P. Gómez; J. Valero; R. Buades and A. Pérez. The results of the research showed that there is evidence to affirm that there is a relationship between phonological awareness and the level of reading decoding in students of the 3rd grade of primary education of the Educational Institution 4004 San Martín de Porres. La Perla - Callao

Hysteretic behavior of methionine adenosyltransferase III. Methionine switches between two conformations of the enzyme with different specific activity

Methionine adenosyltransferase III (MATIII) catalyzes S-adenosylmethionine (AdoMet) synthesis and, as part of its reaction mechanism, it also hydrolyzes tripolyphosphate. Tripolyphosphatase activity was linear over time and had a slightly sigmoidal behavior with an affinity in the low micromolar range. On the contrary, AdoMet synthetase activity showed a lag phase that was independent of protein concentration but decreased at increasing substrate concentrations. Tripolyphosphatase activity, which appeared to be slower than AdoMet synthesis, was stimulated by preincubation with ATP and methionine so that it matched AdoMet synthetase activity. This stimulation process, which is probably the origin of the lag phase, represents the slow transition between two conformations of the enzyme that could be distinguished by their different tripolyphosphatase activity and sensitivity to S-nitrosylation. Tripolyphosphatase activity appeared to be the rate-determining reaction in AdoMet synthesis and the one inhibited by S-nitrosylation. The methionine concentration necessary to obtain half-maximal stimulation was in the range of physiological methionine fluctuations. Moreover, stimulation of MAT activity by methionine was demonstrated in vivo. We propose that the hysteretic behavior of MATIII, in which methionine induces the transition to a higher specific activity conformation, can be considered as an adaptation to the specific functional requirements of the liver

Sexuality and Religious Ethics: Analysis in a Multicultural University Context

Sexuality is still perceived by some cultures as a taboo subject. Although there is now a more open attitude towards sexuality, the maintenance of virginity is one of the most concerning issues in some religions. The aim of this research is to investigate the sexual behavior of university students and analyze how culture and religion influence the beliefs and maintenance of virginity in women and men. A mixed methodology was used, involving 355 students in the quantitative design and 18 informants for the qualitative study who took part in two focus groups. The results indicate that religion and the degree of religious practice are predictor variables for the decision to have penetrative sex, with Muslim women and men giving more importance to the maintenance of a woman’s virginity. However, this hymen-centric view does not prevent other sexual practices, such as oral and/or anal sex, among young people who wish to maintain their virginity until marriage. Religious ethics continue to influence the sexual behavior of young people today. Therefore, nursing education must address these issues to improve the affective sexual health of the population.Partial funding for open access charge: Universidad de Málag

Folding of dimeric methionine adenosyltransferase III: identification of two folding intermediates

Methionine adenosyl transferase (MAT) is an essential enzyme that synthesizes AdoMet. The liver-specific MAT isoform, MAT III, is a homodimer of a 43.7-kDa subunit that organizes in three nonsequential alpha-beta domains. Although MAT III structure has been recently resolved, little is known about its folding mechanism. Equilibrium unfolding and refolding of MAT III, and the monomeric mutant R265H, have been monitored using different physical parameters. Tryptophanyl fluorescence showed a three-state folding mechanism. The first unfolding step was a folding/association process as indicated by its dependence on protein concentration. The monomeric folding intermediate produced was the predominant species between 1.5 and 3 m urea. It had a relatively compact conformation with tryptophan residues and hydrophobic surfaces occluded from the solvent, although its N-terminal region may be very unstructured. The second unfolding step monitored the denaturation of the intermediate. Refolding of the intermediate showed first order kinetics, indicating the presence of a kinetic intermediate within the folding/association transition. Its presence was confirmed by measuring the 1,8-anilinonaphtalene-8-sulfonic acid binding in the presence of tripolyphosphate. We propose that the folding rate-limiting step is the formation of an intermediate, probably a structured monomer with exposed hydrophobic surfaces, that rapidly associates to form dimeric MAT III

Biochemical basis for the dominant inheritance of hypermethioninemia associated with the R264H mutation of the MAT1A gene. A monomeric methionine adenosyltransferase with tripolyphosphatase activity

Methionine adenosyltransferase (MAT) catalyzes the synthesis of S-adenosylmethionine (AdoMet), the main alkylating agent in living cells. Additionally, in the liver, MAT is also responsible for up to 50% of methionine catabolism. Humans with mutations in the gene MAT1A, the gene that encodes the catalytic subunit of MAT I and III, have decreased MAT activity in liver, which results in a persistent hypermethioninemia without homocystinuria. The hypermethioninemic phenotype associated with these mutations is inherited as an autosomal recessive trait. The only exception is the dominant mild hypermethioninemia associated with a G-A transition at nucleotide 791 of exon VII. This change yields a MAT1A-encoded subunit in which arginine 264 is replaced by histidine. Our results indicate that in the homologous rat enzyme, replacement of the equivalent arginine 265 by histidine (R265H) results in a monomeric MAT with only 0.37% of the AdoMet synthetic activity. However the tripolyphosphatase activity is similar to that found in the wild type (WT) MAT and is inhibited by PP(i). Our in vivo studies demonstrate that the R265H MAT I/III mutant associates with the WT subunit resulting in a dimeric R265H-WT MAT unable to synthesize AdoMet. Tripolyphosphatase activity is maintained in the hybrid MAT, but is not stimulated by methionine and ATP, indicating a deficient binding of the substrates. Our data indicate that the active site for tripolyphosphatase activity is functionally active in the monomeric R265H MAT I/III mutant. Moreover, our results provide a molecular mechanism that might explain the dominant inheritance of the hypermethioninemia associated with the R264H mutation of human MAT I/III

Diferencias por sexo del síndrome coronario agudo sin elevación del segmento ST en la Unidad de Cuidados Coronarios

Introducción: La Cardiopatía Isquémica constituye la principal causa de mortalidad en la mayoría de los países industrializados.  La influencia del sexo en el resultado clínico y en la respuesta al tratamiento de los pacientes con síndrome coronario agudo no está bien determinada. En el presente trabajo nos propusimos describir las diferencias que el sexo aporta en los pacientes con Síndrome coronario agudo sin elevación del segmento ST ingresados en la Unidad de Cuidados Intensivos Coronarios. Método: Se realizó un estudio retrospectivo, descriptivo, de 495 pacientes ingresados en la Unidad de Cuidados Intensivos Coronarios del Instituto de Cardiología y Cirugía Cardiovascular de Cuba con diagnóstico de Síndrome Coronario Agudo sin Elevación del Segmento ST en el período del 1ro de  enero del 2005 al 31 de Diciembre del 2008, con el objetivo de determinar las diferencias entre hombres y mujeres con Síndromes Coronarios Agudos sin elevación del segmento ST. Se extrajeron las características demográficas, el diagnóstico definitivo al egreso, las características angiográficas de los pacientes sometidos a coronariografía, la necesidad de revascularización y sus resultados inmediatos. Se determinó la presencia de eventos clínicos mayores a corto y mediano plazo. Resultados: La sexta década de la vida, el sexo masculino y el color de la piel blanca fueron las más afectadas por SCASEST. El tabaquismo fue  prevalente en mujeres.  La Angina Inestable se presentó con una incidencia  superior a lo reportado sin diferencias en relación al sexo. Los eventos clínicos fueron escasos al mes y a los 180 días sin diferencias entre hombres y mujeres. Conclusiones: Existieron diferencias significativas en el comportamiento del síndrome coronario agudo sin elevación del segmento ST entre los sexos.    

Redox regulation of methylthioadenosine phosphorylase in liver cells: molecular mechanism and functional implications

MTAP (5'-methylthioadenosine phosphorylase) catalyses the reversible phosphorolytic cleavage of methylthioadenosine leading to the production of methylthioribose-1-phosphate and adenine. Deficient MTAP activity has been correlated with human diseases including cirrhosis and hepatocellular carcinoma. In the present study we have investigated the regulation of MTAP by ROS (reactive oxygen species). The results of the present study support the inactivation of MTAP in the liver of bacterial LPS (lipopolysaccharide)-challenged mice as well as in HepG2 cells after exposure to t-butyl hydroperoxide. Reversible inactivation of purified MTAP by hydrogen peroxide results from a reduction of V(max) and involves the specific oxidation of Cys(136) and Cys(223) thiols to sulfenic acid that may be further stabilized to sulfenyl amide intermediates. Additionally, we found that Cys(145) and Cys(211) were disulfide bonded upon hydrogen peroxide exposure. However, this modification is not relevant to the mediation of the loss of MTAP activity as assessed by site-directed mutagenesis. Regulation of MTAP by ROS might participate in the redox regulation of the methionine catabolic pathway in the liver. Reduced MTA (5'-deoxy-5'-methylthioadenosine)-degrading activity may compensate for the deficient production of the precursor S-adenosylmethionine, allowing maintenance of intracellular MTA levels that may be critical to ensure cellular adaptation to physiopathological conditions such as inflammation

Creation of a functional S-nitrosylation site in vitro by single point mutation

Here we show that in extrahepatic methionine adenosyltransferase replacement of a single amino acid (glycine 120) by cysteine is sufficient to create a functional nitric oxide binding site without affecting the kinetic properties of the enzyme. When wild-type and mutant methionine adenosyltransferase were incubated with S-nitrosoglutathione the activity of the wild-type remained unchanged whereas the activity of the mutant enzyme decreased markedly. The mutant enzyme was found to be S-nitrosylated upon incubation with the nitric oxide donor. Treatment of the S-nitrosylated mutant enzyme with glutathione removed most of the S-nitrosothiol groups and restored the activity to control values. In conclusion, our results suggest that functional S-nitrosylation sites can develop from existing structures without drastic or large-scale amino acid replacement

Importance of a deficiency in S-adenosyl-L-methionine synthesis in the pathogenesis of liver injury

One of the features of liver cirrhosis is an abnormal metabolism of methionine--a characteristic that was described more than a half a century ago. Thus, after an oral load of methionine, the rate of clearance of this amino acid from the blood is markedly impaired in cirrhotic patients compared with that in control subjects. Almost 15 y ago we observed that the failure to metabolize methionine in cirrhosis was due to an abnormally low activity of the enzyme methionine adenosyltransferase (EC 2.5.1.6). This enzyme converts methionine, in the presence of ATP, to S-adenosyl-L-methionine (SAMe), the main biological methyl donor. Since then, it has been suspected that a deficiency in hepatic SAMe may contribute to the pathogenesis of the liver in cirrhosis. The studies reviewed here are consistent with this hypothesis

S-Adenosylmethionine revisited: its essential role in the regulation of liver function

Dietary methionine is mainly metabolized in the liver where it is converted into S-adenosylmethionine (AdoMet), the main biologic methyl donor. This reaction is catalyzed by methionine adenosyltransferase I/III (MAT I/III), the product of MAT1A gene, which is exclusively expressed in this organ. It was first observed that serum methionine levels were elevated in experimental models of liver damage and in liver cirrhosis in human beings. Results of further studies showed that this pathological alteration was due to reduced MAT1A gene expression and MAT I/III enzyme inactivation associated with liver injury. Synthesis of AdoMet is essential to all cells in the organism, but it is in the liver where most of the methylation reactions take place. The central role played by AdoMet in cellular function, together with the observation that AdoMet administration reduces liver damage caused by different agents and improves survival of alcohol-dependent patients with cirrhosis, led us to propose that alterations in methionine metabolism could play a role in the onset of liver disease and not just be a consequence of it. In the present work, we review the recent findings that support this hypothesis and highlight the mechanisms behind the hepatoprotective role of AdoMet