Tissue-specific control of midbody microtubule stability by Citron kinase through modulation of TUBB3 phosphorylation.

Cytokinesis, the physical separation of daughter cells at the end of cell cycle, is commonly considered a highly stereotyped phenomenon. However, in some specialized cells this process may involve specific molecular events that are still largely unknown. In mammals, loss of Citron-kinase (CIT-K) leads to massive cytokinesis failure and apoptosis only in neuronal progenitors and in male germ cells, resulting in severe microcephaly and testicular hypoplasia, but the reasons for this specificity are unknown. In this report we show that CIT-K modulates the stability of midbody microtubules and that the expression of tubulin ß-III (TUBB3) is crucial for this phenotype. We observed that TUBB3 is expressed in proliferating CNS progenitors, with a pattern correlating with the susceptibility to CIT-K loss. More importantly, depletion of TUBB3 in CIT-K-dependent cells makes them resistant to CIT-K loss, whereas TUBB3 overexpression increases their sensitivity to CIT-K knockdown. The loss of CIT-K leads to a strong decrease in the phosphorylation of S444 on TUBB3, a post-translational modification associated with microtubule stabilization. CIT-K may promote this event by interacting with TUBB3 and by recruiting at the midbody casein kinase-2α (CK2α) that has previously been reported to phosphorylate the S444 residue. Indeed, CK2α is lost from the midbody in CIT-K-depleted cells. Moreover, expression of the nonphosphorylatable TUBB3 mutant S444A induces cytokinesis failure, whereas expression of the phospho-mimetic mutant S444D rescues the cytokinesis failure induced by both CIT-K and CK2α loss. Altogether, our findings reveal that expression of relatively low levels of TUBB3 in mitotic cells can be detrimental for their cytokinesis and underscore the importance of CIT-K in counteracting this event.

Evidencias actuales de la influencia de los videojuegos en salud mental / Current evidences of videogames influence on mental health

Introducción: En el mundo se ha masificado el uso de Videojuegos (VJs) en la última década, alcanzando en adolescentes de países desarrollados, un uso promedio de 1 hora diaria. La mayoría de los VJs catalogados apropiados para niños y adolescentes, incluyen contenidos violentos. En esas edades e incluso en adultos, se han publicado efectos deletéreos para su salud física y mental. Materiales y Métodos: Con estos antecedentes, revisamos 36 publicaciones sobre videojuegos y salud mental entre los años 2001 y abril de 2009, mediante los buscadores PubMed y LILACS. Además, se incluyeron trabajos publicados por el Nacional Institute on Media and the Family U.S., y disponibles en línea a través de la página Web http://www.mediafamily.org/research/.Resultados: Las investigaciones abordan el tema desde distintas perspectivas. Entre los hallazgos más relevantes encontramos que: Los jugadores pueden presentar síntomas afectivos, cognitivos y conductuales, además de cambios desfavorables, sean éstos familiares, sociales o en su desempeño académico. Tienen mayor agresividad y menor conducta prosocial asociada al uso de VJs violentos. Incluso un porcentaje de los jugadores alcanza un patrón de uso tipo adictivo. Concluimos dados estos resultados preocupantes, que los profesionales de la salud mental deben ser informados en este tema, para orientar el uso de VJs en las personas.

Background: In the last time, the Videogames have grown around the world. There are controversial evidence about the effects of videogames on the people and its possible addictive role. Objective: to assess the research evidence about of the main behavioral, cognitive and affective effects of the videogames on the people. Methods: We searched scientific literature related to videogames by means of the electronic searchers MedLine PubMed and LILACS; we selected and evaluated the papers showing results about aspects of mental health. Results: We found 36 scientific articles and only one Chilean paper. We found that the players may have addictive behavior; aggressiveness related to violent videogames; changes in their social and academic performances, and associationwith pathologies. Discussion: Overall, the published surveys were observational, descriptive According to the available evidence it’s not possible to assess causality in the showed associations. Must be recommended controlled time use and content of videogames in childrens, adolescents and adults. More and better surveys, and Chilean surveys, are required in order to improve the evidence of the videogames influences on mental health.

Mimotopes and proteome analyses using human genomic and cDNA epitope phage display.

In the post-genomic era, validation of candidate gene targets frequently requires proteinbased strategies. Phage display is a powerful tool to define protein-protein interactions by generating peptide binders against target antigens. Epitope phage display libraries have the potential to enrich coding exon sequences from human genomic loci. We evaluated genomic and cDNA phage display strategies to identify genes in the 5q31 Interleukin gene cluster and to enrich cell surface receptor tyrosine kinase genes from a breast cancer cDNA library. A genomic display library containing 2 x 106 clones with exon-sized inserts was selected with antibodies specific for human Interleukin-4 (IL-4) and Interleukin-13. The library was enriched significantly after two selection rounds and DNA sequencing revealed unique clones. One clone matched a cognate IL-4 epitope; however, the majority of clone insert sequences corresponded to E. coli genomic DNA. These bacterial sequences act as 'mimotopes' (mimetic sequences of the true epitope), correspond to open reading frames, generate displayed peptides, and compete for binding during phage selection. The specificity of these mimotopes for IL-4 was confirmed by competition ELISA. Other E. coli mimotopes were generated using additional antibodies. Mimotopes for a receptor tyrosine kinase gene were also selected using a breast cancer SKBR-3 cDNA phage display library, screened against an anti-erbB2 monoclonal antibody. Identification of mimotopes in genomic and cDNA phage libraries is essential for phage display-based protein validation assays and two-hybrid phage approaches that examine protein-protein interactions. The predominance of E. coli mimotopes suggests that the E. coli genome may be useful to generate peptide diversity biased towards protein coding sequences.

Alcoholismo y personalidad: una actualización crítica / Alcoholism and personality: a critical review

Las relaciones entre la dependencia y/o abuso de alcohol y trastornos de la personalidad, han sido motivo de profundas controversias entre los investigadores. Con el propósito de actualizar este tema, revisamos la bibliografía pertinente publicada entre enero de 1990 y junio de 1995. Los datos encontrados en esta revisión, sólo permiten sostener que en los dependientes y/o abusadores de alcohol, la comorbilidad psiquiátrica es alta, especialmente los trastornos de perosonalidad (TP). No se encuentra un tipo de TP específico de estos pacientes. Descubrir la interrelación entre ambos cuadros es difícil, porque a las complejidades inherentes a cada uno de ellos, se agrega que algunos síntomas propios de estas enfermedades se superponen. Además, la metodología empleada en los trabajos fue dispar en cuanto a selección de muestras, criterios diagnósticos y evaluación de personalidad. Creemos que el obstáculo principal para aclarar dichas relaciones es la falta de un estudio clínico fenomenológico de la personalidad, y que sea mantenido a lo largo del tiempo.

Alcoholismo y personalidad: una actualización crítica / Alcoholism and personality: a critical review

Las relaciones entre la dependencia y/o abuso de alcohol y trastornos de la personalidad, han sido motivo de profundas controversias entre los investigadores. Con el propósito de actualizar este tema, revisamos la bibliografía pertinente publicada entre enero de 1990 y junio de 1995. Los datos encontrados en esta revisión, sólo permiten sostener que en los dependientes y/o abusadores de alcohol, la comorbilidad psiquiátrica es alta, especialmente los trastornos de perosonalidad (TP). No se encuentra un tipo de TP específico de estos pacientes. Descubrir la interrelación entre ambos cuadros es difícil, porque a las complejidades inherentes a cada uno de ellos, se agrega que algunos síntomas propios de estas enfermedades se superponen. Además, la metodología empleada en los trabajos fue dispar en cuanto a selección de muestras, criterios diagnósticos y evaluación de personalidad. Creemos que el obstáculo principal para aclarar dichas relaciones es la falta de un estudio clínico fenomenológico de la personalidad, y que sea mantenido a lo largo del tiempo. (AU)

Proteoglycan alterations in skin fibroblast cultures from patients affected with pseudoxanthoma elasticum.

Proteoglycans (PGs) were investigated in fibroblast cultures from both apparently normal and involved areas of skin from two patients affected with Pseudoxanthoma elasticum (PXE) and compared to control normal cells. Biochemical analysis showed that cells from the PXE-affected patients produced a PG population with stronger polyanion properties, as well as a markedly increased amount of high hydrodynamic-size PGs. Moreover, PGs from PXE-affected cells showed abnormal hydrophobic interaction properties when examined under associative conditions and included heparan sulphate (HS)-containing populations with anomalous electrophoretic mobility. These phenomena were particularly evident in the case of PGs secreted into the growth medium. In agreement with these findings immunohistochemical study showed alterations affecting decorin and biglycan, as well as a different content and distribution of HS-PGs in PXE-affected cells. The same biochemical and morphological alterations were confirmed for both patients on different cell cultures and were present in cells from both apparently normal and affected skin areas, being more pronounced in the latter. Our results indicate that PXE-affected fibroblasts in culture exhibit an abnormal PG metabolism, which could affect the normal assembly of extracellular matrix.

Heparin protection against Fe2+ -and Cu2+ -mediated oxidation of liposomes.

Heparin (HE) exhibited a protective effect on liposome peroxidation induced by Fe2+ and Cu2+, decreasing the formation of both conjugated dienes and thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. The antioxidant activity was more relevant in the oxidizing system employing Fe2+ and H2O2 and generating the highly reactive OH radical. The analysis of liposome size distribution by quasielastic laser light scattering showed that: (1) the native structure of the particles was completely lost after exposure to Fenton reagent; (2) the presence of HE in the reaction mixture completely prevented the peroxidative damage on liposomes. Thus, HE acts as an antioxidant factor on membrane lipid bilayer. This suggests that HE, released from mast-cell granules during inflammatory processes, might locally protect the cell membrane from the oxidative injuries.

The effect of cornea proteoglycans on liposome peroxidation.

Proteoglycans (PGs) from bovine cornea showed a protective effect on liposome peroxidation induced by Fe2+. Both chondroitin sulfate, dermatan sulfate-containing PG (CS,DS-PG) and keratan sulfate-containing PG (KS-PG) inhibited thiobarbituric acid-reactive substance formation when incubated with liposomes and Fe2+, CS,DS-PG being more effective than KS-PG. The native structure of PGs contributed markedly to antioxidant activity. Papain digestion of core protein reduced the protective effect of CS,DS-PG, whereas it abolished completely that of KS-PG. Apparently only hexuronate-containing glycosaminoglycan (GAG) chains may exert a significant antioxidant activity and this was confirmed using standard GAGs. Quasielastic laser light scattering was used to evaluate the structural consequence of peroxidative damage induced by Fenton reagent on liposomes. After exposure to the free-radical-generating system, a bimodal distribution of liposomes was observed, probably depending on the loss of native structure and fragmentation. Both CS,DS-PG and KS-PG prevented liposome breakdown. Again, free KS chains were ineffective against liposome damage, whereas DS and CS maintained the normal distribution of liposome size. These data support the hypothesis that PGs may represent part of the antioxidant mechanisms of organisms and suggest that modifications of PG content and/or composition might affect tissue sensitivity to oxidative stress.

The effect of heparin on Cu(2+)-mediated oxidation of human low-density lipoproteins.

The effect of heparin (HE) on the susceptibility of human low-density lipoprotein (LDL) to Cu(2+)-induced oxidation was investigated by monitoring conjugated diene formation. HE did not modify the maximum formation of conjugated diene, but increased markedly the lag phase. The plot of change in oxidation rate vs. time showed that the absolute value of Vmax was dependent on Cu2+ concentration and that HE increased the time necessary to reach Vmax. The value of constant K (the Cu2+ concentration producing a tlag of twice the minimum value) increased in the presence of HE, whereas the value of tmin (the time theoretically required for LDL oxidation at an infinite Cu2+ concentration) was not substantially affected. These results indicate that HE might play a protective antioxidant effect on LDL, probably affecting both the structural properties of the particle and the amount of Cu2+ available for the oxidation.

Collagenase-extractable proteoglycans from lesion-free areas of human aorta.

Different proteoglycan (PG) populations were isolated from normal human aorta by extraction of minced tissue with 4M GuHCl and by further digestion of the residue with collagenase. Dissociative extraction induced a complete disappearance of Alcian Blue positive material, which was demonstrable by transmission electron microscopy before the treatment around collagen fibrils and in pericellular areas. However, 4M GuHCl extraction solubilized only an average of 60% of aorta total hexuronate content. Collagenase treatment of the residue resulted in a complete loss of collagen fibril organization, which was coupled with a further hexuronate recovery, accounting for about one third of total tissue content. The bulk of PGs obtained in collagenase digest was retained by Sepharose CL-4B column. Their sulphated glycosaminoglycan (GAG) composition differed from PGs extracted with 4M GuHCl, containing only chondroitin sulphate (CS) and heparan sulphate (HS), without detectable traces of dermatan sulphate (DS). Moreover, they contained hyaluronic acid. The results obtained by agarose polyacrylamide gel electrophoresis (APGE) and Octyl-Sepharose chromatography, followed by further APGE and Sepharose CL-4B gel-filtration, carried out before and after treatment with Chondroitinase ABC and AC and Heparinase I and III, suggested that collagenase digest contained different PG populations, carrying mainly either CS or HS chains. Moreover, HS containing PGs showed higher hydrodynamic size and stronger properties of hydrophobic interactions than CS containing PGs.

Modifications of proteoglycans produced by human skin fibroblast cultures during replicative senescence.

The properties of proteoglycans (PGs) produced by normal human skin fibroblasts were investigated with increasing passage. The increase of subculture number was associated with a constant increase in PG molecular size, which was particularly evident in cell layer extracts. In the cell layer, the ratio of DS-PGs/HS-PGs was markedly higher in early passage cultures. Moreover, the cell layer from young cells contained lower amounts of radioactivity incorporated into the most hydrophobic PG populations, suggesting that the PG core protein might also undergo significant modification with increasing subcultures. There was no significant difference in energy charge value between early and late passage cultures, whereas the NAD/NADH ratio was found to decrease markedly in senescent cells.

Influencia de España en la psiquiatría chilena / Spain influence in chilean psychiatry

En el siglo XV, se crearon en España los primeros hospitales para enfermos mentales. En ellos, los pacientes fueron tratados humanitariamente a diferencia de lo que ocurría en el resto de Europa. Como procedimiento de rehabilitación terapéutica realizaban trabajos manuales y agrícolas. Siglos después, P. Pinel introdujo el modelo español de asistencia en Francia. A través de la influencia de la psiquiatría francesa se extendió por todo el mundo y llegó a Chile. En nuestro país, las comunidades de religiosos, atendieron en la Casa de Orates y otros lugares. Así, las ideas de caridad cristiana y rehabilitación de los enfermos que eran tradicionales en ellos fueron también aplicadas en nuestro medio

Influencia de España en la psiquiatría chilena / Spain influence in Chilean psychiatry

En el siglo XV, se crearon en España los primeros hospitales para enfermos mentales. En ellos, los pacientes fueron tratados humanitariamente a diferencia de lo que ocurría en el resto de Europa. Como procedimiento de rehabilitación terapéutica realizaban trabajos manuales y agrícolas. Siglos después, P. Pinel introdujo el modelo español de asistencia en Francia. A través de la influencia de la psiquiatría francesa se extendió por todo el mundo y llegó a Chile. En nuestro país, las comunidades de religiosos, atendieron en la Casa de Orates y otros lugares. Así, las ideas de caridad cristiana y rehabilitación de los enfermos que eran tradicionales en ellos fueron también aplicadas en nuestro medio (AU)

Modifications of adhesion properties and proteoglycan structure in rat embryo fibroblast cultures with increasing passages.

Adhesion properties of rat embryo fibroblast cultures and proteoglycans (PGs) produced both in the growth medium and in the cell layer were investigated with increasing passages. Both cell-cell and cell-substrate adhesion increased with increasing subculture number. Cell adhesion properties were improved by cell treatment with chondroitinase ABC. The increase in subculture number was coupled with a constant increase of PG molecular size, which was particularly evident in cell layer extracts. The ratio HS-PGs/DS-PGs increased with increasing passages. PG modifications are likely to represent evidence of changes in extracellular matrix organization and could play a role in the increase of cell adhesion properties.

Evolución de un grupo de pacientes alcohólicos después de diez años / Evolution after 10 years of a group of alcoholic patients

Se estudia la evolución a 10 años plazo de un grupo de 26 pacientes alcohólicos, hospitalizados en 1978, en la Clínica Psiquiátrica Universitaria. En el transcurso del tiempo se perfilaron dos grupos, uno de buena y otro de mala evolución. Fueron similares en cuanto a: edad promedio, estado civil, cuadro clínico y tratamiento recibido. Encontramos que el grupo de mala evolución era claramente mayoritario y estaba formado principalmente por varones inactivos o jubilados y tenían mejor nivel educacional. Finalmente el hecho más inquietante fue mortalidad encontrada, que alcanzó al 38,5% de los sujetos y con edad promedio de 53 años, datos que ilustran la gravedad de la enfermedad

Síndrome de tensión premenstrual y trastorno bipolar / Premenstrual tension syndrome and bipolar disorder

Se presenta el caso clínico de una enferma de 50 años, que padecía de una Depresión Bipolar y un SPM producido por patología ginecológica. Diagnosticada como cicladora rápida, se había agravado con los años, no respondiendo a ningún tratamiento farmacológico de regla en estos casos. Fue tratada desde el punto de vista ginecológico, con procedimientos microquirúrgico, criocirugía, electrocirugía, terapia antibiótica, antiinflamatoria y medicamentos para mejorar el SPM, como en otros casos que hemos atendido. Su evolución posterior ha mostrado que al ser tratada de sus patologías ginecológicas responsables del SPM, hace casi un año, fue posible reducir considerablemente el número de fármacos y las dosis empleadas para compensar su Trastorno Bipolar. En la actualidad se encuentra claramente compensada. Se expone esta experiencia porque plantea nuevas posibilidades terapéuticas en el tratamiento del SPM y el Trastorno Bipolar