Pivotal role of O-antigenic polysaccharide display in the sensitivity against phage tail-like particles in environmental Pseudomonas kin competition.

Environmental pseudomonads colonize various niches including insect and plant environments. When invading these environments, bacteria are confronted with the resident microbiota. To oppose with closely related strains, they rely on narrow-spectrum weaponry such as tailocins, i.e., phage tail-like particles. Little is known about the receptors for these tailocins especially among phylogenetically closely related species. Here, we studied the interaction between an R-tailocin from Pseudomonas protegens CHA0 and a targeted kin, Pseudomonas protegens Pf-5. Using genome-wide transposon insertion sequencing, we identified that lipopolysaccharides are involved in the sensitivity of Pf-5 towards the tailocin of CHA0. By generating Pf-5 lipopolysaccharide mutants and exposing them to extracted tailocin, we specified the two O-antigenic polysaccharides (O-PS) targeted by the tailocin. We affirmed the role of these O-PS through competition assays in vitro as well as in insects. Further, we demonstrate that O-PS are double-edge swords that are responsible for the sensitivity of P. protegens towards tailocins and phages produced by their kin, but shield bacteria from the immune system of the insect. Our results shed light on the trade-off that bacteria are confronted with, where specific O-PS decorations can both be of benefit or disadvantage depending on the host environment and its bacterial inhabitants.

GDSL-domain proteins have key roles in suberin polymerization and degradation.

Plant roots acquire nutrients and water while managing interactions with the soil microbiota. The root endodermis provides an extracellular diffusion barrier through a network of lignified cell walls called Casparian strips, supported by subsequent formation of suberin lamellae. Whereas lignification is thought to be irreversible, suberin lamellae display plasticity, which is crucial for root adaptative responses. Although suberin is a major plant polymer, fundamental aspects of its biosynthesis and turnover have remained obscure. Plants shape their root system via lateral root formation, an auxin-induced process requiring local breaking and re-sealing of endodermal lignin and suberin barriers. Here, we show that differentiated endodermal cells have a specific, auxin-mediated transcriptional response dominated by cell wall remodelling genes. We identified two sets of auxin-regulated GDSL lipases. One is required for suberin synthesis, while the other can drive suberin degradation. These enzymes have key roles in suberization, driving root suberin plasticity.

Escolar con malaria por plasmodium falciparum de África: riesgo para la salud pública en Honduras / School child with Plasmodium falciparum malaria from Africa: public health risk in Honduras

Antecedentes: Los viajes a zonas endémicas con parásitos resistentes, la respuesta evolutiva de Plasmodium y los sistemas sanitarios debilitados, comprometen el control mundial y local de la malaria. Descripción del Caso clínico: Niño, 6 años, atendido en Hospital Escuela Universitario (HE), Tegucigalpa, referido desde Siguatepeque, Comayagua, por dudas en diagnóstico de laboratorio y antecedente de vivir en África y cuatro episodios de malaria por P. falciparum (2015-2017). Al ingreso presentó cuadro entérico e informe de Plasmodium spp. Se inició tratamiento con cloroquina, omitida y substituida al día siguiente por derivado de artemisinina al confirmar P. falciparum y 0.7% de eritrocitos parasitados. Presentó buena respuesta clínica y parasitológica, egresando al 7mo día intrahospitalario después de 72 horas afebril. La gota gruesa al egreso informó estadios sexuales de P. falciparum, administrándose primaquina al estar disponible 7 días después. En control ambulatorio al 5to día post-egreso, no se observaron parásitos aunque persistían leucocitos con pigmento malárico fagocitado. Cuatro familiares convivientes en África fueron examinados. El padre, que informó cefalea leve y febrícula, fue detectado con estadios asexuales de P. falciparum; presentó buena respuesta al tratamiento con derivado de artemisinina. Conclusiones: La descripción del caso y los diferentes eslabones en su manejo clínico y epidemiológico, reflejan la potencialidad de complicación de la malaria. La introducción de parásitos resistentes a la cloroquina constituye una amenaza de salud pública, principalmente ante fallas evitables en el sistema sanitario. Es necesario fortalecer el diagnóstico temprano y tratamiento oportuno especialmente en el contexto de la eliminación de malaria en Mesoamérica...(AU)

Operando spectroscopy study of the carbon dioxide electro-reduction by iron species on nitrogen-doped carbon.

The carbon-carbon coupling via electrochemical reduction of carbon dioxide represents the biggest challenge for using this route as platform for chemicals synthesis. Here we show that nanostructured iron (III) oxyhydroxide on nitrogen-doped carbon enables high Faraday efficiency (97.4%) and selectivity to acetic acid (61%) at very-low potential (-0.5 V vs silver/silver chloride). Using a combination of electron microscopy, operando X-ray spectroscopy techniques and density functional theory simulations, we correlate the activity to acetic acid at this potential to the formation of nitrogen-coordinated iron (II) sites as single atoms or polyatomic species at the interface between iron oxyhydroxide and the nitrogen-doped carbon. The evolution of hydrogen is correlated to the formation of metallic iron and observed as dominant reaction path over iron oxyhydroxide on oxygen-doped carbon in the overall range of negative potential investigated, whereas over iron oxyhydroxide on nitrogen-doped carbon it becomes important only at more negative potentials.

Low number of fixed somatic mutations in a long-lived oak tree.

Because plants do not possess a defined germline, deleterious somatic mutations can be passed to gametes, and a large number of cell divisions separating zygote from gamete formation may lead to many mutations in long-lived plants. We sequenced the genome of two terminal branches of a 234-year-old oak tree and found several fixed somatic single-nucleotide variants whose sequential appearance in the tree could be traced along nested sectors of younger branches. Our data suggest that stem cells of shoot meristems in trees are robustly protected from the accumulation of mutations.

Síndrome hemofagocítico secundario a leishmaniasis visceral en un lactante mayor: reporte de caso / Hemophagocytic síndrome secondary to visceral leishmaniasis in a toddler: report of a case

El síndrome hemofagocítico está caracterizado por la activación anómala del sistema inmune. De etiología primaria o secundaria a enfermedades infecciosas, metabólicas, inmunitarias o neoplásicas. Con incidencia de 0,12 a 1 casos por cada 100 000 niños y una sobrevida de dos meses de no recibir tratamiento. Se diagnostica con 5 de 8 criterios propuestos por la Asociación Internacional de Histocitosis, y tratamiento según etiología. . Se presenta el caso de un paciente masculino de 15 meses de edad, procedente una zona endémica de leishmaniasis (Choluteca, Honduras), que ingresó al Hospital Escuela Universitario con cuadro clínico de fiebre prolongada y hepatoesplenomegalia. En los exámenes auxiliares de detectó: pancitopenia, serología positiva para leishmania, hipertrigliceridemia y valor de ferritina aumentada. Se hizo el diagnóstico de leishmaniasis visceral y síndrome hemofagocítico. Se trató con antimoniato de meglumina por 28 días, metilprednisolona y prednisona; con evolución favorable. El síndrome hem ofagocítico podría ocurrir secundario a leishmaniasis visceral por lo que su diagnóstico debería sospecharse tempranamente para un tratamiento oportuno y mejor pronóstico

The hemophagocytic syndrome is characterized by an abnormal activation of the immune system. This condition may be primary or secondary to infectious, metabolic, immunological, or malignant conditions. Its incidence is 0.12 to 1 case per 100,000 children, and the survival time is around two months with no therapy. The condition is diagnosed with the occurrence of 5 of 8 criteria proposed by the International Histiocytosis Association, and its therapy is according the original etiology. We present the case of a 15-month old male patient, who was brought from Choluteca (an endemic area for leishmaniasis), who was admitted to the University Hospital with prolonged fever and hepatosplenomegaly. Laboratory tests showed pancytopenia, positive serology for Leishmania, hypertriglyceridemia, and increased ferritin levels. Visceral leishmaniasis and hemophagocytic syndrome were diagnosed. The patient received meglumine antimoniate for 28 days, and also methylprednisolone and prednisone; and he had a favorable outcome. The hemophagocytic syndrome may be secondary to visceral leishmaniasis, and its diagnosis should be promptly suspected in order to have timely therapy and a better prognosis

Spectroscopic Observation and Molecular Dynamics Simulation of Ga Surface Segregation in Liquid Pd-Ga Alloys.

Liquid binary Pd-Ga alloys with low Pd contents of 0.8, 1.8, and 4.7 at % of Pd were examined as a function of sample temperature in ultra-high vacuum by using angle-resolved XPS. Upon cooling from 750 to 400 K, a pronounced temperature-dependence of the Pd concentration in the liquid phase was observed, which was explained by the transition from the pure liquid phase to a two-phase system, consisting of a solid Ga5 Pd phase and a Pd-depleted liquid Pd-Ga alloy. In the liquid Pd-Ga alloy, Pd is always depleted from the topmost interface layer, as deduced from angle-resolved XPS at 0 and 80° emission, independent of temperature and Pd concentration. This observation is interpreted as an inhomogeneous depth distribution function of Pd, that is, the segregation of Ga to the surface of the liquid phase. The results of a DFT-based molecular dynamics simulation (MD) independently show interfacial stratification of Ga and an inhomogeneous Pd distribution along the surface normal. The evaluation of the experimental data with a rigid layer model based on the MD calculations leads to excellent agreement with the simulation.

Growth of Stable Surface Oxides on Pt(111) at Near-Ambient Pressures.

Detailed knowledge of the structure and degree of oxidation of platinum surfaces under operando conditions is essential for understanding catalytic performance. However, experimental investigations of platinum surface oxides have been hampered by technical limitations, preventing in situ investigations at relevant pressures. As a result, the time-dependent evolution of oxide formation has only received superficial treatment. In addition, the amorphous structures of many surface oxides have hindered realistic theoretical studies. Using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) we show that a time scale of hours (t≥4 h) is required for the formation of platinum surface oxides. These experimental observations are consistent with ReaxFF grand canonical Monte Carlo (ReaxFF-GCMC) calculations, predicting the structures and coverages of stable, amorphous surface oxides at temperatures between 430-680 K and an O2 partial pressure of 1 mbar.

The synthesis of nanostructured Ni5 P4 films and their use as a non-noble bifunctional electrocatalyst for full water splitting.

The investigation of nickel phosphide (Ni5 P4 ) as a catalyst for the hydrogen (HER) and oxygen evolution reaction (OER) in strong acidic and alkaline environment is described. The catalyst can be grown in a 3D hierarchical structure directly on a nickel substrate, thus making it an ideal candidate for practical water splitting devices. The activity of the catalyst towards the HER, together with its high stability especially in acidic solution, makes it one of the best non-noble materials described to date. Furthermore, Ni5 P4 was investigated in the OER and showed activity superior to pristine nickel or platinum. The practical relevance of Ni5 P4 as a bifunctional catalyst for the overall water splitting reaction was demonstrated, with 10 mA cm(-2) achieved below 1.7 V.

Carbon dioxide capture by an amine functionalized ionic liquid: fundamental differences of surface and bulk behavior.

Carbon dioxide (CO2) absorption by the amine-functionalized ionic liquid (IL) dihydroxyethyldimethylammonium taurinate at 310 K was studied using surface- and bulk-sensitive experimental techniques. From near-ambient pressure X-ray photoelectron spectroscopy at 0.9 mbar CO2, the amount of captured CO2 per mole of IL in the near-surface region is quantified to ~0.58 mol, with ~0.15 mol in form of carbamate dianions and ~0.43 mol in form of carbamic acid. From isothermal uptake experiments combined with infrared spectroscopy, CO2 is found to be bound in the bulk as carbamate (with nominally 0.5 mol of CO2 bound per 1 mol of IL) up to ~2.5 bar CO2, and as carbamic acid (with nominally 1 mol CO2 bound per 1 mol IL) at higher pressures. We attribute the fact that at low pressures carbamic acid is the dominating species in the near-surface region, while only carbamate is formed in the bulk, to differences in solvation in the outermost IL layers as compared to the bulk situation.

Synthesis, characterization, and photoinduced energy and electron transfer in a supramolecular tetrakis (ruthenium(II) phthalocyanine) perylenediimide pentad.

Metal coordination was probed as a versatile approach for designing a novel electron donor/acceptor hybrid [PDIpy(4){Ru(CO)Pc}(4)] (1), in which four pyridines placed at the bay region of a perylenediimides (PDIpy(4)) coordinate with four ruthenium phthalocyanine units [Ru(CO)Pc]. This structural motif was expected to promote strong electronic coupling between the electron donors and the electron acceptor, a hypothesis that was confirmed in a full-fledged physicochemical investigation focusing on the ground and excited state reactivities. As far as the ground state is concerned, absorption and electrochemical assays indeed reveal a notable redistribution of electron density, that is, from the electron-donating [Ru(CO)Pc] to the electron-accepting PDIpy(4). The most important thing to note in this context is that both the [Ru(CO)Pc] oxidation and the PDIpy(4) reduction are rendered more difficult in 1 than in the individual building blocks. Likewise, in the excited state, strong electronic communication is the inception for a rapid charge-transfer process in photoexcited 1. Regardless of exciting [Ru(CO)Pc] or PDIpy(4), spectral characteristics of the [RuPc] radical cation (broad absorptive features from 425 to 600 nm with a maximum at 575 nm, as well as a band centered at 725 nm) and of the PDI radical anion (780 nm maximum) emerge. The correspondingly formed radical ion pair state lasts for up to several hundred picoseconds in toluene, for example. On the other hand, employing more polar solvents, such as dichloromethane, destabilizes the radical ion pair state.

[A transcultural study on stirred strawberry yogurt: consumer acceptability versus sensory quality with trained panel]. / Un estudio transcultural de yogurt batido de fresa: aceptabilidad con consumidores versus calidad sensorial con paneles entrenados.

The present work was designed in order to obtain the cut off point, to be used in a shelf life study on whole stirred strawberry yogurt. The study was simultaneously carried out in Argentina, Chile and Costa Rica, assaying the same kind of product, elaborated in each one of the countries. The sensory quality parameters obtained from trained panelists and the consumers acceptability, were correlated by using the cut off point methodology through a quality evaluation by the Karlsruhe scale. According to preliminary studies, the storage at 42 degrees C produced considerable damage on parameters such as pH, acidity (volumetric assay), viscosity and sensory quality. For each sample, the cut off point was determined. This value corresponds to the threshold score for the sensory quality, where the consumer starts to perceive negative changes in the product, when comparing with the fresh product. The rejection percentage was also calculated according to the cut off point. The cut off points and the percentage of rejection obtained by the three participating countries were similar. Data obtained from Costa Rica showed changes in color, acidity and rancidity. Argentinean yogurts developed acidity that had a negative effect on texture, appearance and residual flavors. Chilean samples presented a sensory quality that remains almost without change through the studied time. The differences of the deterioration pattern amongst the three countries, demonstrates that the products are different in formulation and elaboration process, in spite of been the same kind of yogurt. This could be explained by differences specified in the regulation of each country.

Un estudio transcultural de yogurt batido de fresa: aceptabilidad con consumidores versus calidad sensorial con paneles entrenados / A transcultural study on stirred strawberry yogurt: consumer acceptability versus sensory quality with trained panel

Con el fin de estimar el punto de corte, para luego ser empleado en un estudio de vida útil de yogurt batido de fresa, se diseñó un estudio simultáneo, a ser realizado en Argentina, Chile y Costa Rica, con un mismo tipo de yogurt, elaborado en los respectivos países de origen, relacionándose los parámetros de calidad sensorial, determinados con un panel entrenado, y la aceptabilidad, determinada con consumidores. Para ello se empleó la metodología de punto de corte utilizando la valoración de calidad mediante el método de Karlsruhe. Estudios preliminares realizados a 42º C indicaron que los parámetros de calidad más sensibles al deterioro por efecto del almacenamiento eran: pH, acidez titulable, viscosidad y la calidad sensorial. En cada caso se determinó el punto de corte que representa el puntaje de calidad sensorial a partir del cual el consumidor comienza a percibir un cambio en el producto, en relación al producto fresco y también se calculó el porcentaje de rechazo en función del punto de corte. Los puntos de corte y los porcentajes de rechazo obtenidos para los tres países fueron similares, pero a nivel de calidad sensorial, las muestras de yogurt costarricenses modificaron sus características de coloración y sabores ácido y rancio, las muestras de yogurt argentino desarrollaron acidez que influenció cambios en la textura, apariencia y sabores residuales y las muestras de yogures chilenos fueron las que se mantuvieron más estables en su calidad sensorial, a través del tiempo. Esta disparidad en el comportamiento de las muestras evidencia que los productos, a pesar de tener una misma denominación, corresponden a productos diferentes en su formulación y elaboración, la cual está supeditada a la diferente reglamentación vigente en cada país. Así por ejemplo, las condiciones de comercialización son también diferentes, por lo que la industria local debe satisfacer las necesidades de esa población y considerar las variables que definen la aceptación del producto en cada mercado objetivo

Nivel de conocimiento y medidas de protección en la aplicación de quimioterapia que tiene el personal de enfermería, que labora en el servicio de lactantes y oncología Hospital de Niños Baca Otíz. Quito 1993 / Level of knowledge and measures of protection in the application of chemotherapy that has the infirmary personnel, that toils in the service of suckling babies and oncología Hospital of Children Baca Otíz

Se ha establecido que la quimioterapia es una terapia curativa sumamente agresiva que requiere de adiestramiento previo del personal responsable de su manejo, y de una adecuación de la planta fija o instalaciones que permitan aplicar las precausiones para evitar efectos indeseados en el personal de salud. Por esta razón el trabajo de investigación contiene lo siguiente: nivel de conocimiento, aplicación y precausiones que las deben tener cuando preparan y administran medicación quimioterapia y factores que interviene, en el personal de enfermería los aplique o no los aplique...

Endoscopia con toma de biopsia esofágica en niños con enfermedad por reflujo gastroesofágico con un año o más de tratamiento / Endoscopy with wsophagical biopsy in childrens

Se estudiaron 30 niños con diagnóstico clínico de enfermedad por reflujo gastroesofágico, (ERGE) tratados con anácidos, con bloqueadores H21 con procinéticos, o con todos estos fármacos, durante un año o más. Al cabo de ese periodo presentaban remisión clínica y radiológica y crecimiento pondoestatural adecuado. Se practicó endoscopia y estudio histológico del esófago a todos un año después del tratamiento. Nueve de los 29 tuvieron esofagitis diagnosticada por endoscopia; en un niño no se describieron los hallazgos endoscópicos, y en 11 de 30 el diagnóstico fue por estudio histológico. No hubo diferencias estadísticamente significativas entre el grupo de pacientes con esofagitis en cuanto a edad de principio del tratamiento, edad al final del mismo, ni tiempo de tratamiento, de acuerdo con el análisis de varianza. A pesar de estos resultados, y de que el consenso general señala dar tratamiento médico a los niños con ERGE por un año, surge la duda sobre el tiempo que debe durar dicho tratamiento y cuándo deben considerarse curados estos pacientes.

Fisiopatología de la colestasis neonatal / Physiopathology of neonatl choletasis

Se hace una revisión de la fisiología normal de la secreción biliar y de los padecimientos intra y extrahepáticos que alteran o bloquean la producción de bilis, produciendo su retención y como consecuencia colestasis.

Púrpura en el desnutrido / Purpura in the malnourished

Se revisaron los expedintes clínicos de 333 niños desnutridos que ingresaron al Servicio de Nutrición del Instituto Nacional de Pediatría, desde enero de 1985 hasta diciembre de 1988. La púrpura se presentó en 42 niños (12.6 por ciento), en una relación 1:1 con respecto al sexo. Esta fue más frecuente en los niños pequeños. El 61% cursó con niveles bajos de hemoglobina; en 26 casos se determinaron niveles de folatos y de vitamina B12; hubo deficiencia de folatos en 10 pacientes. El 38 por ciento presentó trombocitopenia; pero en ausencia de complicaciones no hubo sangrado. El 95% presentó datos clínicos de infecciones, especialmente en el tracato gastrointestinal, corroborados por cultivo en 22 casos. Se aislaron principalmente gérmentes Gram negativos y estafilococo. La mortalidad global fue de 16.5 por ciento y en los niños con púrpura de 28 por ciento, que es más baja a la obsevada por otros autores.

Correlación entre las manifestaciones clínicas y diferentes métodos diagnósticos para la evaluación del reflujo gastroesofágico / Correlation between clinical manifestation and different diagnostic methods for gastroesophageal reflux evaluation

Se hizo un estudio transversal en 100 niños con reflujo gastroesofágico (RGE), en el Servicio de Gastroenterología del Instituto Nacional de Pediatría (INP). Se seleccionaron los pacientes con las manifestaciones clínicas, en quienes se corroboró el RGE, por uno de los siguientes estudios: Serie esofagogastroduodenal (SEGD) y/o estudio radioisotópico (RI). A 36 niños se les realizó esofagoscopía y estudio histológico del tercio inferior del esófago. De los 100 niños, 88 presentaron manifestaciones clínicas de EGE asociadas a complicaciones secundarias. Se detectó RGE en 99/100 niños por SEGD y en 45/100 por estudio RI. Hubo concordancia entre los resultados de ambos estudios con 44 niños. En los 36 niños con estudios esofagoscópico y estudio histológico, hubo RGE por SEGD y hubo concordancia entre este estudio y el hallazgo endoscópico de esofagitis en 26 de 36. En relación a la esofagitis, hubo concordancia del estudio endoscópico de esofagitis en 26/36. En 4/6 los dos estudios resultaron normales, con diferencias estadísticamente significativas (p=0.01). Estos datos sugieren que la SEGD es un bien método para la detección de RGE en niños, aunque existen otros métodos que son complementarios, en el estudio integral de esta patología, tales como el estudio RI, la esofagoscopía y el estudio histológico.