Cobalamin cbiP mutant shows decreased tolerance to low temperature and copper stress in Listeria monocytogenes.

BACKGROUND: Listeria monocytogenes is a foodborne pathogen that causes listeriosis in humans. This pathogen activates multiple regulatory mechanisms in response to stress, and cobalamin biosynthesis might have a potential role in bacterial protection. Low temperature is a strategy used in the food industry to control bacteria proliferation; however, L. monocytogenes can grow in cold temperatures and overcome different stress conditions. In this study we selected L. monocytogenes List2-2, a strain with high tolerance to the combination of low temperature + copper, to understand whether the cobalamin biosynthesis pathway is part of the tolerance mechanism to this stress condition. For this, we characterized the transcription level of three cobalamin biosynthesis-related genes (cbiP, cbiB, and cysG) and the eutV gene, a transcriptional regulator encoding gene involved in ethanolamine metabolism, in L. monocytogenes strain List2-2 growing simultaneously under two environmental stressors: low temperature (8 °C) + copper (0.5 mM of CuSO4 × 5H2O). In addition, the gene cbiP, which encodes an essential cobyric acid synthase required in the cobalamin pathway, was deleted by homologous recombination to evaluate the impact of this gene in L. monocytogenes tolerance to a low temperature (8 °C) + different copper concentrations. RESULTS: By analyzing the KEGG pathway database, twenty-two genes were involved in the cobalamin biosynthesis pathway in L. monocytogenes List2-2. The expression of genes cbiP, cbiB, and cysG, and eutV increased 6 h after the exposure to low temperature + copper. The cobalamin cbiP mutant strain List2-2ΔcbiP showed less tolerance to low temperature + copper (3 mM) than the wild-type L. monocytogenes List2-2. The addition of cyanocobalamin (5 nM) to the medium reverted the phenotype observed in List2-2ΔcbiP. CONCLUSION: These results indicate that cobalamin biosynthesis is necessary for L. monocytogenes growth under stress and that the cbiP gene may play a role in the survival and growth of L. monocytogenes List2-2 at low temperature + copper.

Cobalamin cbiP mutant shows decreased tolerance to low temperature and copper stress in Listeria monocytogenes

BACKGROUND: Listeria monocytogenes is a foodborne pathogen that causes listeriosis in humans. This pathogen activates multiple regulatory mechanisms in response to stress, and cobalamin biosynthesis might have a potential role in bacterial protection. Low temperature is a strategy used in the food industry to control bacteria proliferation; however, L. monocytogenes can grow in cold temperatures and overcome different stress conditions. In this study we selected L. monocytogenes List2-2, a strain with high tolerance to the combination of low temperature +copper, to understand whether the cobalamin biosynthesis pathway is part of the tolerance mechanism to this stress condition. For this, we characterized the transcription level of three cobalamin biosynthesis related genes ( cbiP , cbiB, and cysG ) and the eutV gene, a transcriptional regulator encoding gene involved in ethanolamine metabolism, in L. monocytogenes strain List2-2 growing simultaneously under two environmental stressors: low temperature (8 °C) +copper (0.5 mM of CuSO4 ×5H2O). In addition, the gene cbiP , which encodes an essential cobyric acid synthase required in the cobalamin pathway, was deleted by homologous recombination to evaluate the impact of this gene in L. monocytogenes tolerance to a low temperature (8 °C) +different copper concentrations. RESULTS: By analyzing the KEGG pathway database, twenty-two genes were involved in the cobalamin biosynthesis pathway in L. monocytogenes List2-2. The expression of genes cbiP , cbiB, and cysG, and eutV increased 6 h after the exposure to low temperature +copper. The cobalamin cbiP mutant strain List2-2Δ cbiP showed less tolerance to low temperature +copper (3 mM) than the wild type L. monocytogenes List2-2. The addition of cyanocobalamin (5 nM) to the medium reverted the phenotype observed in List2-2Δ cbiP . CONCLUSION: These results indicate that cobalamin biosynthesis is necessary for L. monocytogenes growth under stress and that the cbiP gene may play a role in the survival and growth of L. monocytogenes List2-2 at low temperature +copper.

Contrasting evolutionary responses in two co-distributed species of Galaxias (Pisces, Galaxiidae) in a river from the glaciated range in Southern Chile.

Life-history traits are among the most important factors affecting population abundance and genetic diversity of species. Here, we analysed the genetic patterns of two Galaxias species with different life-history traits to investigate how these biological differences impacted their evolution in the Valdivia River basin, Southern Chile. We analysed mitochondrial DNA (mtDNA) sequences from 225 individuals of Galaxias maculatus and 136 of G. platei to compare patterns of genetic diversity, structure and demographic growth across the basin. Galaxias maculatus presented higher genetic diversity and higher genetic structure than G. platei. Demographic analyses showed G. maculatus kept a higher population size over time, with a signal of demographic expansion in the last 250 kyr. Whereas Galaxias platei, exhibited lower, but constant population size over time. Furthermore, haplotype networks revealed higher lineage diversity in G. maculatus with a tendency to occupy different areas of the basin. Coalescent simulations ruled out that genetic differences between species could be explained by stochastic processes (genetic drift), suggesting species-specific biological differences as responsible for the observed genetic differences. We discuss how differences in life-history traits and past glaciations interact to shape the evolutionary history of the two Galaxias species.

Evaluación del efecto acaricida de Momordica charantia, Megaskepasma erythrochlamys y Gliricidia sepium sobre Rhipicephalus microplus / Acaricidal effect of Momordica charantia, Megaskepasma erythrochlamys and Gliricidia sepiumon the Rhipicephalus microplus

RESUMEN Objetivo. Se evaluó la actividad acaricida de Momordica charantia (Mc), Megaskepasma erythrochlamys (Me) y Gliricidia sepium (Gs) sobre Rhipicephalus microplus (Rm). Materiales y métodos. Se realizó la marcha fitoquímica preliminar de hojas del extracto metanólico de Mc (EMc), del extracto etanólico de Me (EMe) y del extracto acetónico de Gs (EGs) a través de la técnica de colorimetría y cromatografía en capa delgada (CCD). La actividad acaricida se realizó a través de pruebas in-vitro utilizando la prueba de inmersión de larvas (LIT) y la prueba de inmersión de adultos (AIT). Para las pruebas in-situ se usaron bovinos en pastoreo infestados naturalmente con garrapatas, utilizando las CL50 obtenidas en las pruebas in-vitro AIT; posteriormente las teleoginas se llevaron a incubación para evaluar su capacidad reproductiva. Resultados. Se determinó la presencia de varios grupos de metabolitos secundarios de interés acaricida. Se demostró el efecto acaricida de los extractos de las plantas sobre teleoginas; aunque sólo EGs mostró actividad larvicida. Los extractos a 160 mg/mL afectaron el ciclo de vida de Rm inhibiendo la ovoposición en un 46.9%, 66.1% y 84.03% (p<0.05) para EGs, EMc y EMe, respectivamente. Por otro lado, en las pruebas in situ se observó diferencia significativa (p<0.05) entre el tratamiento de EMc y EMe respecto a los grupos controles. Conclusiones. Los resultados obtenidos son prometedores para fortalecer la posibilidad de vinculación de los extractos de estas plantas dentro de planes integrados de control de garrapatas en sistemas de producción de bovinos.

ABSTRACT Objective. The acaricidal activity of Momordica charantia (Mc), Megaskepasma erythrochlamys (Me) and Gliricidia sepium (Gs) on Rhipicephalus microplus (Rm) was evaluated. Materials and methods. Preliminary phytochemical analysis of leaves of the methanolic extract of Mc (EMc), the ethanolic extract of Me (EMe) and the acetone extract of Gs (EGs) were carried out through the technique of colorimetry and thin layer chromatography (CCD). The acaricidal activity was performed through in-vitro tests using the larval immersion test (LIT) and the adult immersion test (AIT). For in-situ tests, grazing cattle naturally infested with ticks were used, using the LC50 obtained from the in-vitro AIT tests; later the teleogines were taken to incubation to evaluate their reproductive capacity. Results. The presence of several groups of secondary metabolites of acaricidal interest was determined. The acaricidal effect of the extracts of the plants on teleogines was demonstrated; although only EGs showed larvicidal activity. Extracts at 160 mg/mL affected the life cycle of Rm by inhibiting ovoposition in 46.9%, 66.1% and 84.03% (p<0.05) for EGs, EMc and EMe, respectively. On the other hand, the in-situ tests showed a significant difference (p<0.05) between the treatment of EMc and EMe with respect to the control groups. Conclusions. The results obtained are promising to strengthen the possibility of linking the extracts of these plants into integrated plans for the control of ticks in cattle systems.

[Kinematic gait pattern with silicone ankle-foot ortesis in patients with drop foot]. / Patrón cinemático de la marcha con ortesis de tobillo-pie de silicón en pacientes con pie caído.

INTRODUCTION: The Drop foot is a condition that is usually handled with short orthosis, usually made of polypropylene. It has also been described as being treated with silicon orthosis, little studied but which seem to improve the kinematic pattern of gait and, given its comfort, be more accepted by patients. Our study describes the kinematic characteristics of gait and patient satisfaction when using a silicon foot ankle orthosis, and compares this pattern to the non-use of the orthosis, in patients with a drop foot. MATERIAL AND METHODS: Pseudo-experimental descriptive study in patients with dropped feet from 2010 to 2012, in which the kinematic variables of the gait pattern were evaluated from gait laboratories and in addition to the satisfaction of subjects with silicon orthosis and non-use of them. RESULTS: Five patients with a drop foot were the subject of the study. Gait analysis of patients using the orthosis found an improvement in ankle position at initial contact, average walking speed and step length, as well as increased cadence. However, in terms of comfort compared to the non-use of the orthosis, the result was meager. CONCLUSIONS: Silicon foot ankle orthosis improve the position of the ankle in the initial contact, as well as the temporo-spatial parameters of the gait.

INTRODUCCIÓN: El pie caído es una condición que suele manejarse con ortesis cortas, normalmente fabricadas en polipropileno. Se ha descrito también su tratamiento con ortesis de silicón, poco estudiadas pero que parecen mejorar el patrón cinemático de la marcha y, dada su comodidad, ser más aceptadas por los pacientes. Nuestro estudio describe cuáles son las características cinemáticas de la marcha y la satisfacción referida por los pacientes al usar una ortesis tobillo pie de silicón y compara dicho patrón con el no uso de la ortesis en casos con pie caído. MATERIAL Y MÉTODOS: Estudio seudoexperimental descriptivo en pacientes con pie caído desde el año 2010 al 2012, en el que se evaluaron las variables cinemáticas del patrón de marcha a partir de laboratorios de marcha y además de la satisfacción de los sujetos con las ortesis de silicón y con el no uso de las mismas. RESULTADOS: Cinco casos con pie caído fueron objeto del estudio. El análisis de marcha de los pacientes que usaron la ortesis constató una mejora de la posición del tobillo en el contacto inicial, en la velocidad promedio de marcha y en la longitud del paso, así como un aumento de la cadencia. Sin embargo, en términos de comodidad en comparación con el no uso de la ortesis, el resultado fue exiguo. CONCLUSIONES: Las ortesis tobillo pie de silicón mejoran la posición del tobillo en el contacto inicial, así como los parámetros temporoespaciales de la marcha.

Giant nonlinear damping in nanoscale ferromagnets.

Magnetic damping is a key metric for emerging technologies based on magnetic nanoparticles, such as spin torque memory and high-resolution biomagnetic imaging. Despite its importance, understanding of magnetic dissipation in nanoscale ferromagnets remains elusive, and the damping is often treated as a phenomenological constant. Here, we report the discovery of a giant frequency-dependent nonlinear damping that strongly alters the response of a nanoscale ferromagnet to spin torque and microwave magnetic field. This damping mechanism originates from three-magnon scattering that is strongly enhanced by geometric confinement of magnons in the nanomagnet. We show that the giant nonlinear damping can invert the effect of spin torque on a nanomagnet, leading to an unexpected current-induced enhancement of damping by an antidamping torque. Our work advances the understanding of magnetic dynamics in nanoscale ferromagnets and spin torque devices.

Melorreostosis: displasia ósea esclerosante infrecuente. Utilidad de la gammagrafía ósea / Melorheostosis: a rare sclerosing bone dysplasia. Usefulness of bone scintigraphy

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Increased Glucosinolate Production in Brassica oleracea var. italica Cell Cultures Due to Coronatine Activated Genes Involved in Glucosinolate Biosynthesis.

In this work, the effect of different elicitors and culture conditions on the production of glucosinolates in broccoli cell cultures was studied. The results showed that 0.5 µM coronatine was the best elicitor for increasing glucosinolate production (205-fold increase over untreated cells after 72 h of treatment). Furthermore, the expression levels of some genes related to the biosynthetic pathway of glucosinolates as well as three Myb transcription factors also have been studied. The highest glucosinolate levels found in coronatine-treated cells were closely correlated with the highest gene expression levels of Cyp79b2, Cyp83b1, St5a, Myb51, and Myb122 after 6 h of treatment. The data shown in this study provide new insight into the key metabolic steps involved in the biosynthesis of glucosinolates, which will be of use for future applications of metabolic engineering techniques in broccoli.

Spin caloritronic nano-oscillator.

Energy loss due to ohmic heating is a major bottleneck limiting down-scaling and speed of nano-electronic devices, and harvesting ohmic heat for signal processing is a major challenge in modern electronics. Here, we demonstrate that thermal gradients arising from ohmic heating can be utilized for excitation of coherent auto-oscillations of magnetization and for generation of tunable microwave signals. The heat-driven dynamics is observed in Y3Fe5O12/Pt bilayer nanowires where ohmic heating of the Pt layer results in injection of pure spin current into the Y3Fe5O12 layer. This leads to excitation of auto-oscillations of the Y3Fe5O12 magnetization and generation of coherent microwave radiation. Our work paves the way towards spin caloritronic devices for microwave and magnonic applications.Harvesting ohmic heat for signal processing is one of major challenges in modern electronics and spin caloritronics, but not yet well accomplished. Here the authors demonstrate a spin torque oscillator device driven by pure spin current arising from thermal gradient across an Y3Fe5O12/Pt interface.

Cambios morfométricos de las células del endotelio corneal en el síndrome pseudoexfoliativo y glaucoma pseudoexfoliativo / Morphometric changes of corneal endothelial cells in pseudoexfoliation syndrome and pseudoexfoliation glaucoma

Objetivo: Analizar el patrón morfométrico de las células endoteliales de la córnea y el espesor corneal central (ECC) en los ojos con pseudoexfoliativo (PEX) con y sin glaucoma, y compararlos con ojos normales y con glaucoma primario de ángulo abierto (GPAA). Método: Se incluyeron 166 pacientes en el estudio: 36 sujetos con síndrome seudoexfoliativo, 30 con glaucoma seudoexfoliativo (GPEX), 40 con GPAA y 60 pacientes normales. Los parámetros evaluados con el microscopio especular de no contacto fueron la densidad de células endoteliales (DCE), el coeficiente de variación ( CV ) del tamaño celular y el porcentaje de hexagonalidad. El ECC se midió con paquimetría de contacto. Resultados: La DCE y el porcentaje de hexagonalidad celular fueron menores en los sujetos con PEX y GPAA respecto al grupo control, mientras que el CV del tamaño celular fue mayor. Considerando los 2 grupos de ojos con PEX, se observó una tendencia hacia una mayor pérdida de células endoteliales y de modificaciones en los parámetros morfométricos en los ojos con GPEX. Las alteraciones en el patrón especular aumentaron progresivamente con la edad. No hubo diferencias significativas en el valor medio de ECC entre los 4 grupos. Conclusión: La densidad de células endoteliales está significativamente disminuida y el pleomorfismo y polimegatismo celular incrementado en los ojos con PEX, especialmente cuando la presión intraocular es alta (AU)

Objetive: To evaluate the corneal endothelial morphometry and central corneal thickness (CCT) in pseudoexfoliative (PEX) eyes with and without glaucoma and to compare with normal eyes and eyes with primary open-angle glaucoma (POAG).Method: A total of 166 patients were included in this study: 36 eyes with pseudoexfoliation syndrome (PXS), 30 eyes with pseudoexfoliation glaucoma (PXG), 40 eyes with POAG, and 60normal eyes. Corneal endothelial cell density (ECD), coefficient of variation (CV) in cell size, and percentage of hexagonal cells, were measured using a non-contact specular microscope, whereas CCT was measured with an ultrasonic pachymeter. Results: ECD and percentage of hexagonal cells were lower in PEX groups and in the POAG group compared with normal eyes, while the CV in cell size was greater. There was a tendency for greater cell loss and morphological abnormalities of the corneal endothelial cells in PXG eyes compared to PXS eyes, when all pseudoexfoliative eyes were analyzed together. Changes in endothelial cells increased with age. There were no significant differences in mean CCT between the four groups. Conclusion: Endothelial cell density is significantly decreased, and pleomorphism and polymegathism of cells are increased in PEX eyes, particularly when intraocular pressure is high (AU)

[Morphometric changes of corneal endothelial cells in pseudoexfoliation syndrome and pseudoexfoliation glaucoma]. / Cambios morfométricos de las células del endotelio corneal en el síndrome pseudoexfoliativo y glaucoma pseudoexfoliativo.

OBJECTIVE: To evaluate the corneal endothelial morphometry and central corneal thickness (CCT) in pseudoexfoliative (PEX) eyes with and without glaucoma and to compare with normal eyes and eyes with primary open-angle glaucoma (POAG). METHOD: A total of 166 patients were included in this study: 36 eyes with pseudoexfoliation syndrome (PXS), 30 eyes with pseudoexfoliation glaucoma (PXG), 40 eyes with POAG, and 60 normal eyes. Corneal endothelial cell density (ECD), coefficient of variation (CV) in cell size, and percentage of hexagonal cells, were measured using a non-contact specular microscope, whereas CCT was measured with an ultrasonic pachymeter. RESULTS: ECD and percentage of hexagonal cells were lower in PEX groups and in the POAG group compared with normal eyes, while the CV in cell size was greater. There was a tendency for greater cell loss and morphological abnormalities of the corneal endothelial cells in PXG eyes compared to PXS eyes, when all pseudoexfoliative eyes were analyzed together. Changes in endothelial cells increased with age. There were no significant differences in mean CCT between the four groups. CONCLUSION: Endothelial cell density is significantly decreased, and pleomorphism and polymegathism of cells are increased in PEX eyes, particularly when intraocular pressure is high.

Proteómica: una aproximación integral / Proteomics: a comprehensive approach

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The effects of weight cycling on lifespan in male C57BL/6J mice.

OBJECTIVE: With the increasing rates of obesity, many people diet in an attempt to lose weight. As weight loss is seldom maintained in a single effort, weight cycling is a common occurrence. Unfortunately, reports from clinical studies that have attempted to determine the effect of weight cycling on mortality are in disagreement, and to date, no controlled animal study has been performed to assess the impact of weight cycling on longevity. Therefore, our objective was to determine whether weight cycling altered lifespan in mice that experienced repeated weight gain and weight loss throughout their lives. METHODS: Male C57BL/6J mice were placed on one of three lifelong diets: a low-fat (LF) diet, a high-fat (HF) diet or a cycled diet in which the mice alternated between 4 weeks on the LF diet and 4 weeks on the HF diet. Body weight, body composition, several blood parameters and lifespan were assessed. RESULTS: Cycling between the HF and LF diet resulted in large fluctuations in body weight and fat mass. These gains and losses corresponded to significant increases and decreases, respectively, in leptin, resistin, GIP, IGF-1, glucose, insulin and glucose tolerance. Surprisingly, weight cycled mice had no significant difference in lifespan (801±45 days) as compared to LF-fed controls (828±74 days), despite being overweight and eating a HF diet for half of their lives. In contrast, the HF-fed group experienced a significant decrease in lifespan (544±73 days) compared with LF-fed controls and cycled mice. CONCLUSIONS: This is the first controlled mouse study to demonstrate the effect of lifelong weight cycling on longevity. The act of repeatedly gaining and losing weight, in itself, did not decrease lifespan and was more beneficial than remaining obese.

Prevalencia de psoriasis en la población infantil de la Región Metropolitana de Chile / Prevalence of psoriasis in children in the Metropolitan Region of Chile

INTRODUCCIÓN: El Carcinoma basocelular (CBC) es la neoplasia más frecuente en la población humana. Se ha observado un aumento de su incidencia en todos los países, incluyendo a Chile. CBC es un tumor heterogéneo clínica e histológicamente. Entre sus factores de riesgo, destaca la exposición a la radiación ultravioleta. En Chile, en la última década se han realizado numerosas campañas de prevención del cáncer cutáneo y de detección precoz de esta neoplasia. El propósito de este trabajo es comparar el comportamiento del CBC en relación a parámetros demográficos, clínicos e histológicos en dos periodos de tiempo, 1995-1999 y 2005-2009 en la población de cuatro hospitales públicos de Santiago de Chile...

INTRODUCTION: Basal cell carcinoma (BCC) is the most common malignancy in the human population. There has been an increased incidence in all countries, including Chile. BCC is a clinically and histologically heterogeneous tumor. The main risk factor of BCC is the ultraviolet radiation exposure. In Chile, in the last decade, there have been numerous campaigns of skin cancer prevention and early detection of this neoplasm. The purpose of this paper is to compare the behavior of BCC in relation to demographic, clinical and histological parameters in two periods, 1995-1999 and 2005-2009 in the population of four hospitals in Santiago de Chile…

Foco pulmonar facticio con 18F-FDG: posible error en la interpretación de la PET-CT / Lung hot spot as pitfall in PET-CT interpretation: focal lung uptake of 18F-fluorodeoxyglucose

Aportamos dos casos de pacientes oncológicos en seguimiento rutinario con este tipo de artefacto, sin correlato morfológico en la TAC. Se procedió a la repetición del estudio en uno de ellos, lo que permitió comprobar una normalización de dicha hipercaptación, orientando a un posible artefacto. La PET-TAC con FDG se ha convertido en una herramienta imprescindible en el manejo del paciente oncológico. La distribución normal de la FDG y los posibles artefactos (pitfalls), incluidos aquéllos derivados de la corrección de atenuación basada en la TAC, han sido descritos en diversas revisiones. Sin embargo, sólo recientemente se ha publicado algún caso de falso positivo en forma de captación focal pulmonar de FDG(AU)

18F-FDG PET-CT has become an essential tool in oncology patient management. The normal distribution of the FDG and the possible artifacts (pitfalls), including those from CT-based attenuation correction, have already been described in several reviews. However, only a few cases of FDG focal lung uptake have been reported recently. We present two cases of oncology patients during a routine follow-up with this type of pitfall, without morphological correlation in the CT scan. We repeated the study in one of them, which made it possible to verify normalization of the hyperuptake, orienting us towards a possible pitfall(AU)