[Taurolidine for the prevention of catheter-related infections in children with intestinal insufficiency: preliminary experience in a Chilean tertiary hospital]. / Taurolidina para prevenir infecciones asociadas a catéter venoso central en niños con insuficiencia intestinal: experiencia preliminar en un hospital terciario chileno.

BACKGROUND: Taurolidine is a molecule with anti-endotoxic, anti-microbial and anti-inflammatory properties that inhibits bacterial adhesion, allowing for its use as lock therapy for the prevention of catheter-related bloodstream infections (CRBSI) in long-term central venous catheters (CVC). AIM: To report a preliminary experience, the first one in Chile, using lock therapy with taurolidine for the prevention of CRBSI and to report its efficacy. METHOD: A taurolidine-based solution was instilled in the CVC of three children with intestinal insufficiency dependent on parenteral nutrition, attended in a Chilean tertiary hospital, and the rate of CRBSI before and after its use was compared in retrospect. RESULTS: In the two patients who started lock therapy immediately after the installation of their CVC, the rate of CRBSI was brought to zero, whereas in the third patient, who had a 9 months-old CVC with a recurrent CRBSI history, an intercurrent CRBSI forced discontinuation of the prophylaxis. CONCLUSIONS: Lock therapy with a taurolidine-based solution prevented CRBSIs when it was begun immediately after installing the CVC, in contrast with an old CVC with a history of recurrent CRBSIs.

Taurolidina para prevenir infecciones asociadas a catéter venoso central en niños con insuficiencia intestinal: experiencia preliminar en un hospital terciario chileno / Taurolidine for the prevention of catheter-related infections in children with intestinal insufficiency: preliminary experience in a Chilean tertiary hospital

INTRODUCCIÓN: Taurolidina es una molécula con propiedades anti-endotóxicas, antimicrobianas y anti-inflamatorias, que inhibe la adhesión bacteriana, lo que ha permitido usarla como terapia de sellado en catéter venoso central de larga duración (CVC) para prevenir infecciones del torrente sanguíneo asociadas a CVC (ITS-CVC). OBJETIVO: Dar a conocer una experiencia preliminar, la primera en Chile, con taurolidina como terapia de sellado para prevenir ITS-CVC y reportar su eficacia. MÉTODO: Se instiló una solución en base a taurolidina en el CVC de tres niños con insuficiencia intestinal, dependientes de alimentación parenteral, atendidos en un hospital terciario de la Región de Valparaíso, y se comparó la tasa de ITS-CVC antes y después de su uso mediante un análisis retrospectivo. RESULTADOS: en los dos pacientes que iniciaron terapia de sellado inmediatamente después de instalado el CVC, la tasa de ITS-CVC se logró llevar a cero, mientras que, en el tercero, portador de un CVC instalado 9 meses antes, con ITS-CVC recurrentes, un nuevo episodio de ITS-CVC obligó a suspender la profilaxis. CONCLUSIONES: La terapia de sellado con solución en base a taurolidina previno las ITS-CVC cuando ésta se inició al momento de instalarse el CVC, no así en un CVC antiguo con ITS-CVC recurrentes.

BACKGROUND: Taurolidine is a molecule with anti-endotoxic, anti-microbial and anti-inflammatory properties that inhibits bacterial adhesion, allowing for its use as lock therapy for the prevention of catheter-related bloodstream infections (CRBSI) in long-term central venous catheters (CVC). AIM: To report a preliminary experience, the first one in Chile, using lock therapy with taurolidine for the prevention of CRBSI and to report its efficacy. METHOD: A taurolidine-based solution was instilled in the CVC of three children with intestinal insufficiency dependent on parenteral nutrition, attended in a Chilean tertiary hospital, and the rate of CRBSI before and after its use was compared in retrospect. RESULTS: In the two patients who started lock therapy immediately after the installation of their CVC, the rate of CRBSI was brought to zero, whereas in the third patient, who had a 9 months-old CVC with a recurrent CRBSI history, an intercurrent CRBSI forced discontinuation of the prophylaxis. CONCLUSIONS: Lock therapy with a taurolidine-based solution prevented CRBSIs when it was begun immediately after installing the CVC, in contrast with an old CVC with a history of recurrent CRBSIs.

Generation of endoplasmic reticulum stress and inhibition of autophagy by plitidepsin induces proteotoxic apoptosis in cancer cells.

Plitidepsin (PLD, Aplidin®), a cyclic depsipeptide originally isolated from the marine tunicate Aplidium albicans, has been recently approved by Australian regulatory authorities for the treatment of multiple myeloma patients. Plitidepsin binds to eEF1A2 and induces oxidative stress, Rac1 activation and JNK1 phosphorylation, triggering a rapid apoptotic program in tumor cells. Since oxidative stress is one of the known sources of endoplasmic reticulum stress, we investigated whether PLD was inducing a bona fide ER stress in HeLa cells and whether this process was essential in the mechanism of action of the compound. Indeed, PLD activated an ER stress-induced unfolded protein response (UPR), including the alternative splicing of XBP1, the proteolytic processing of ATF6 and the phosphorylation of eIF2α and JNK. Interestingly, though PLD induced a strong phosphorylation of eIF2α in all the analyzed cell lines, it did not elicit an increased expression of ATF4 and CHOP, a transcription factor involved in launching UPR-mediated apoptosis. On the contrary, a clear reduction of CHOP protein levels was observed after PLD treatment, most probably due to both the lack of transactivation by ATF4 and its rapid degradation by the ubiquitin/proteasome machinery. Using fibroblasts devoid of each one of the four possible kinases involved in eIF2α phosphorylation, we observed that only PKR was involved in the response to PLD treatment and, accordingly, PKR-/- fibroblasts are shown to be resistant to the apoptogenic activity of the compound. Furthermore, eIF2α phosphorylation itself was shown to be irrelevant for the induction of cell death by PLD. Instead, we reveal that PLD induces an increase in the levels of misfolded proteins while simultaneously inhibiting the autophagic flux. These two effects combined prevent PLD-treated cells from reducing proteotoxic stress and lead to apoptosis. Other anti-myeloma drugs like bortezomib, which target the proteasome, also inhibit the degradation of misfolded proteins through alternate pathways and a synergistic anticancer effect of the PLD plus bortezomib combination has been previously disclosed. The present results extend this synergy to in vivo experiments and provide a mechanistic rationale for this synergy.

[Taurolidine, an antiseptic for the prevention of central venous catheter-related infections]. / Taurolidina, un antiséptico para la prevención de infecciones asociadas a catéter venoso central.

Taurolidine is a broad-spectrum antiseptic used as lock therapy solution in adult and pediatric patients with long term central venous catheters (CVC) for the prevention of catheter related bloodstream infections (CRBSI). Taurolidine doesn't induce the resistant development and has only minor and brief side effects, which makes it an alternative both as a lock therapy and for the prevention of CRBSI in this group of patients.

Taurolidina, un antiséptico para la prevención de infecciones asociadas a catéter venoso central / Taurolidine, an antiseptic for the prevention of central venous catheter-related infections

Resumen Taurolidina es un antiséptico de amplio espectro usado como solución de terapia de sellado (lock therapy) en adultos y niños portadores de catéter venoso central de larga duración (CVC) para prevenir las infecciones asociadas a CVC (IACVC). No induce desarrollo de resistencia y tiene efectos adversos leves y fugaces, lo que lo convierte en una alternativa, tanto como terapia de sellado como para la profilaxis de las IACVC, en este grupo de pacientes.

Taurolidine is a broad-spectrum antiseptic used as lock therapy solution in adult and pediatric patients with long term central venous catheters (CVC) for the prevention of catheter related bloodstream infections (CRBSI). Taurolidine doesn't induce the resistant development and has only minor and brief side effects, which makes it an alternative both as a lock therapy and for the prevention of CRBSI in this group of patients.

Probable fungemia por Rhodotorula mucilaginosa asociada a catéter venoso central en un paciente pediátrico: presentación de un caso / Probable fungemia by rhodotorula mucilaginosa associated to a central venous catheter in a pediatric pacient: a case report

Las levaduras del género Rhodotorula son patógenos oportunistas emergentes, especialmente en pacientes inmunocomprometidos. Se presenta el caso de un niño de 9 años con sarcoma de Ewing en tratamiento con quimioterapia que cursó con una probable fungemia por Rhodotorula mucilaginosa. Se identificaron varios factores de riesgo tales como la presencia de un catéter venoso central (CVC) y una neoplasia maligna sólida. El diagnóstico se realizó a través de un hemocultivo de una rama del CVC. Nuestra cepa fue identificada como R. Mucilaginosa por morfofisiología y pruebas bioquimicas. El éxito terapeutico se basó en el retiro del CVC y en el tratamiento con anfotericina B desoxicolato como primera alternativa.

Yeasts from Rhodotorula genus are opportunistic pathogen that emerge especially in immunocompromised patients. We report a case of a 9-years-old boy, he developed an Ewing’s sarcoma that was treated with chemotherapy an underwent with problable fungemia by Rhodotorula mucilaginosa. Several risk factors were identified such as presence of a central venous catheter (CVC) and a solid malignant neoplasm. The diagnosis was made by blood culture of a branch of the CVC. Our isolated was identified as R. mucilaginosa by morphofisiology and biochemical test. The therapy did success based on withdrawal of CVC and treatment with amphotericin B deoxycholate as the first alternative.

New roles of the fission yeast eIF2α kinases Hri1 and Gcn2 in response to nutritional stress.

In fission yeast, three distinct eukaryotic initiation factor 2α (eIF2α) kinases (Hri1, Hri2 and Gcn2), regulate protein synthesis in response to various environmental stresses. Thus, Gcn2 is activated early after exposure to hydrogen peroxide (H2O2) and methyl methanesulfonate (MMS), whereas Hri2 is the primary activated eIF2α kinase in response to heat shock. The function of Hri1 is still not completely understood. It is also known that the mitogen-activated protein kinase Sty1 negatively regulates Gcn2 and Hri2 activities under oxidative stress. In this study, we demonstrate that Hri1 is mainly activated, and its expression upregulated, during transition from exponential growth to the stationary phase in response to nutritional limitation. Accordingly, both Hri1 and Gcn2, but not Hri2, are activated upon nitrogen source deprivation. In contrast, Hri2 is stimulated early during glucose starvation. We also found that Gcn2 is implicated in nitrogen starvation-induced growth arrest in the cell cycle G1 phase as well as in the non-selective protein degradation process caused upon this particular cellular stress. Moreover, Gcn2, but not Hri1 or Hri2, is essential for survival of cells growing in minimal medium, upon oxidative stress or glucose limitation. We further show that eIF2α phosphorylation at serine 52 by the eIF2α kinases is necessary for efficient cell cycle arrest in the G1 phase, for the consequent protein degradation and for sexual differentiation, under nitrogen starvation. Therefore, the eIF2α kinase signalling pathway modulates G1 phase cell cycle arrest, cell survival and mating under nutritional stress in the fission yeast Schizosaccharomyces pombe.

GCN2 has inhibitory effect on human immunodeficiency virus-1 protein synthesis and is cleaved upon viral infection.

The reversible phosphorylation of the alpha-subunit of eukaryotic translation initiation factor 2 (eIF2alpha) is a well-characterized mechanism of translational control in response to a wide variety of cellular stresses, including viral infection. Beside PKR, the eIF2alpha kinase GCN2 participates in the cellular response against viral infection by RNA viruses with central nervous system tropism. PKR has also been involved in the antiviral response against HIV-1, although this antiviral effect is very limited due to the distinct mechanisms evolved by the virus to counteract PKR action. Here we report that infection of human cells with HIV-1 conveys the proteolytic cleavage of GCN2 and that purified HIV-1 and HIV-2 proteases produce direct proteolysis of GCN2 in vitro, abrogating the activation of GCN2 by HIV-1 RNA. Transfection of distinct cell lines with a plasmid encoding an HIV-1 cDNA clone competent for a single round of replication resulted in the activation of GCN2 and the subsequent eIF2alpha phosphorylation. Moreover, transfection of GCN2 knockout cells or cells with low levels of phosphorylated eIF2alpha with the same HIV-1 cDNA clone resulted in a marked increase of HIV-1 protein synthesis. Also, the over-expression of GCN2 in cells led to a diminished viral protein synthesis. These findings suggest that viral RNA produced during HIV-1 infection activates GCN2 leading to inhibition of viral RNA translation, and that HIV-1 protease cleaves GCN2 to overcome its antiviral effect.

Role of mitogen-activated protein kinase Sty1 in regulation of eukaryotic initiation factor 2alpha kinases in response to environmental stress in Schizosaccharomyces pombe.

The mitogen-activated protein kinase (MAPK) Sty1 is essential for the regulation of transcriptional responses that promote cell survival in response to different types of environmental stimuli in Schizosaccharomyces pombe. In fission yeast, three distinct eukaryotic initiation factor 2alpha (eIF2alpha) kinases, two mammalian HRI-related protein kinases (Hri1 and Hri2) and the Gcn2 ortholog, regulate protein synthesis in response to cellular stress conditions. In this study, we demonstrate that both Hri1 and Hri2 exhibited an autokinase activity, specifically phosphorylated eIF2alpha, and functionally replaced the endogenous Saccharomyces cerevisiae Gcn2. We further show that Gcn2, but not Hri1 or Hri2, is activated early after exposure to hydrogen peroxide and methyl methanesulfonate (MMS). Cells lacking Gcn2 exhibit a later activation of Hri2. The activated MAPK Sty1 negatively regulates Gcn2 and Hri2 activities under oxidative stress but not in response to MMS. In contrast, Hri2 is the primary activated eIF2alpha kinase in response to heat shock. In this case, the activation of Sty1 appears to be transitory and does not contribute to the modulation of the eIF2alpha kinase stress pathway. In strains lacking Hri2, a type 2A protein phosphatase is activated soon after heat shock to reduce eIF2alpha phosphorylation. Finally, the MAPK Sty1, but not the eIF2alpha kinases, is essential for survival upon oxidative stress or heat shock, but not upon MMS treatment. These findings point to a regulatory coordination between the Sty1 MAPK and eIF2alpha kinase pathways for a particular range of stress responses.

Heme responsiveness in vitro is a common feature shared by the eukaryotic initiation factor 2á kinase family

Four distinct eukaryotic initiation factor 2á (eIF2á) kinases phosphorylate eIF2á at Ser-51 and regulate protein synthesis in response to cellular stress conditions. This kinase family includes the hemin-regulated inhibitor (HRI); the doublestranded RNA-dependent kinase (PKR); the GCN2 protein kinase; and the endoplasmic reticulum-resident kinase (PERK). HRI mediates protein synthesis inhibition in heme-deficient reticulocyte lysates. Although HRI contains two putative heme regulatory motifs (HRMs) that are not present in other eIF2á kinases, the significance of these motifs in heme regulation is not clear. In fact, it had been characterized two novel eIF2á kinases from Schizosaccharomyces pombe that lacked any of the HRMs, but were sensitive to heme regulation in vitro. To investigate the importance of different regions in the regulation of HRI by heme, specific HRI mutants were generated, and kinase activities and heme responsiveness were analyzed in vitro. Mutational analysis indicated that the heme regulatory motifs were spread around some regions in the HRI catalytic domain, outside of the HRMs. In accordance with these results, both the autokinase and the eIF2á kinase activities of three distinct eIF2á kinases, including the human PKR, the mouse GCN2 and the Drosophila PERK were inhibited in vitro by hemin. Although the known regulatory mechanisms of these eIF2á kinases are very different, the data reported here indicate that all known eIF2á kinases are regulated in vitro by hemin. This finding provides evidence that hemin represents a regulatory mechanism unique to eIF2á kinases and underscores the role of hemin in the translational regulation of eukaryotic cells

Las cuatro eIF2á quinasas eucarióticas fosforilan el residuo Ser-51 de la subunidad alfa del factor de iniciación 2 y regulan la síntesis de proteínas en respuesta a situaciones de estrés celular. Esta familia de proteínas quinasas está formada por el inhibidor regulado por hemina (HRI); la quinasa dependiente de RNA de doble cadena (PKR); la proteína quinasa GCN2 y la quinasa residente en el retículo endoplásmico (PERK). El HRI inhibe la síntesis de proteínas en lisados de reticulocitos de conejo deficientes de hemina. Aunque el HRI contiene dos supuestos motivos reguladores de hemina (HRMs), que no están presentes en las otras eIF2á quinasas, no está claro aún el papel de estos motivos en la regulación por hemina. De hecho, se han caracterizado dos nuevas eIF2á quinasas de Schizosaccharomyces pombe que carecen de dichos HRMs, pero son sensibles a la regulación por hemina in vitro. Un análisis mutacional indicó que los motivos reguladores de hemina estaban dispersos a lo largo del dominio catalítico, fuera de los HRMs. De acuerdo con estos resultados, las actividades autoquinasa y eIF2á quinasa de tres eIF2á quinasas distintas, la PKR humana, la GCN2 de ratón y la PERK de Drosophila, se inhibían por hemina in vitro. Aunque los mecanismos de regulación de todas estas eIF2á quinasas son muy diferentes, nuestros resultados indican que todas las eIF2á quinasas se regulan por hemina in vitro. Este descubrimiento soporta la evidencia de que la hemina representa un mecanismo de regulación específico de las eIF2á quinasas, y subraya su papel en la regulación de la traducción de células eucarióticas

Antiviral effect of the mammalian translation initiation factor 2alpha kinase GCN2 against RNA viruses.

In mammals, four different protein kinases, heme-regulated inhibitor, double-stranded RNA-dependent protein kinase (PKR), general control non-derepressible-2 (GCN2) and PKR-like endoplasmic reticulum kinase, regulate protein synthesis in response to environmental stresses by phosphorylating the alpha-subunit of the initiation factor 2 (eIF2alpha). We now report that mammalian GCN2 is specifically activated in vitro upon binding of two nonadjacent regions of the Sindbis virus (SV) genomic RNA to its histidyl-tRNA synthetase-related domain. Moreover, endogenous GCN2 is activated in cells upon SV infection. Strikingly, fibroblasts derived from GCN2-/- mice possess an increased permissiveness to SV or vesicular stomatitis virus infection. We further show that mice lacking GCN2 are extremely susceptible to intranasal SV infection, demonstrating high virus titers in the brain compared to similarly infected control animals. The overexpression of wild-type GCN2, but not the catalytically inactive GCN2-K618R variant, in NIH 3T3 cells impaired the replication of a number of RNA viruses. We determined that GCN2 inhibits SV replication by blocking early viral translation of genomic SV RNA. These findings point to a hitherto unrecognized role of GCN2 as an early mediator in the cellular response to RNA viruses.

Functional characterization of Drosophila melanogaster PERK eukaryotic initiation factor 2alpha (eIF2alpha) kinase.

Four distinct eukaryotic initiation factor 2alpha (eIF2alpha) kinases phosphorylate eIF2alpha at S51 and regulate protein synthesis in response to various environmental stresses. These are the hemin-regulated inhibitor (HRI), the interferon-inducible dsRNA-dependent kinase (PKR), the endoplasmic reticulum (ER)-resident kinase (PERK) and the GCN2 protein kinase. Whereas HRI and PKR appear to be restricted to mammalian cells, GCN2 and PERK seem to be widely distributed in eukaryotes. In this study, we have characterized the second eIF2alpha kinase found in Drosophila, a PERK homologue (DPERK). Expression of DPERK is developmentally regulated. During embryogenesis, DPERK expression becomes concentrated in the endodermal cells of the gut and in the germ line precursor cells. Recombinant wild-type DPERK, but not the inactive DPERK-K671R mutant, exhibited an autokinase activity, specifically phosphorylated Drosophila eIF2alpha at S50, and functionally replaced the endogenous Saccharomyces cerevisiae GCN2. The full length protein, when expressed in 293T cells, located in the ER-enriched fraction, and its subcellular localization changed with deletion of different N-terminal fragments. Kinase activity assays with these DPERK deletion mutants suggested that DPERK localization facilitates its in vivo function. Similar to mammalian PERK, DPERK forms oligomers in vivo and DPERK activity appears to be regulated by ER stress. Furthermore, the stable complexes between wild-type DPERK and DPERK-K671R mutant were mediated through the N terminus of the proteins and exhibited an in vitro eIF2alpha kinase activity.