Determinación de los cambios bioquímicos para predecir el desarrollo de escaldadura superficial en peras

Durante la postcosecha de peras, se pueden expresar una serie de desórdenes fisiológicos tales como escaldado superficial (ES), pardeamiento interno, escaldadura por sol, bitter pit, entre otros. Poder determinar la susceptibilidad o riesgo que presentarían los lotes a estos desórdenes permitiría la segregación de fruta, optimizar las condiciones de almacenamiento y minimizar la incidencia no sólo durante su conservación, sino también en mercados de destino. Esto último es de gran relevancia, ya que los costos de reembalaje en destino son muy elevados y la pérdida de confianza de los compradores son determinantes para el negocio. El ES es uno de los principales desórdenes fisiológicos en peras y genera grandes pérdidas económicas a nivel mundial. Esta fisiopatía es el resultado de un proceso oxidativo, siendo la severidad proporcional al grado de oxidación del α-farneseno (AF), un tipo de trieno conjugado (TC). El objetivo de este trabajo fue comprender los cambios bioquímicos que subyacen el desarrollo del ES durante el almacenamiento y determinar los valores de umbral critico de TC en peras ‘Beurré D´Anjou (BD)’, ‘Packhams Triumph’(PT), ‘Abate Fetel’ (AF), ‘Rocha’(R) y ‘Williams’ (W). Los frutos de cada variedad se conservaron en frío convencional durante 240 días. Se realizaron determinaciones cada 30 días de: producción de etileno, parámetros de madurez, incidencia de escaldado superficial, contenido de AF, TC, ácido ascórbico (AA), polifenoles (PF) y capacidad antioxidante total (DPPH). Los cultivares presentaron diferente susceptibilidad al escaldado y un patrón de manifestación distinto, que se correlacionó con el patrón de acumulación de TC. Las peras BD fueron las más sensibles a la escaldadura y exhibieron los niveles más altos de TC durante el almacenamiento, con una acumulación significativamente mayor al resto de los cultivares. Se pudo establecer el nivel crítico de TC necesario para desencadenar la escaldadura en las variedades evaluadas. En BD el umbral fue significativamente más alto, observándose los valores más bajos en W, R y AF y valores intermedios en PT. Los niveles críticos de TC se pueden considerar como una determinación rápida para predecir la “situación de riesgo” a mediano plazo (30-45 días) de un lote de fruta. La capacidad antioxidante de los frutos resultó clave en la prevención de la escaldadura superficial, siendo que BD fue la que tuvo los menores valores de DPPH, AA y PF al momento de la cosecha y menores valores de DPPH y PF durante el almacenamiento. Los resultados obtenidos en este trabajo han permitido aportar nuevos conocimientos sobre las bases bioquímicas del escaldado superficial en peras, estableciendo el rol del etileno, de los TC y de los antioxidantes endógenos en el desarrollo de esta fisiopatía. Los sistemas de predicción no reemplazan los sistemas de control, pero pueden permitir utilizar sistemas alternativos no químicos, discriminar lotes sensibles, así como adoptar soluciones correctoras antes de la aparición de los síntomas

Proportion of extended-spectrum ß-lactamase-producing Enterobacteriaceae in community setting in Ngaoundere, Cameroon

BACKGROUND: There is no information regarding the resistance mechanisms of extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae in community setting in Cameroon. The current study aimed to determine the proportion of ESBLs in Enterobacteriaceae isolated in the community and to analyse some risk factors associated with ESBL carriage. METHODS: Faecal samples were collected from 208 different outpatients and 150 healthy student volunteers between 3 January and 3 April 2009. Enterobacterial isolates resistant to third-generation cephalosporins were screened for ESBL production by the double-disk synergy test. Presumptive ESBL-producing isolates with positive synergy test were identified by Mass Spectrometry using the BioTyper MALDI-TOF. For such ESBL positive isolates, antibiotic susceptibility was determined by the Vitek 2 system. PCR and sequencing were performed for the detection of different types of ESBL genes in presumptive ESBL-producing isolates. Statistical methods were used for the univariate calculation of risk factors. RESULTS: During the study period, a total of 358 faecal samples were analysed; 58 of such samples (16%) showed an ESBL phenotype and were confirmed by PCR. The proportion of ESBL producers in faecal carriage was statistically different between outpatients and student volunteers (23.1% vs. 6.7%: p < 0.000). According to a univariate analysis, previous use of antibiotics (ciprofloxacin) appeared to be a risk factor for ESBL carriage (p < 0.05).Escherichia coli was the species most frequently isolated among the ESBL producers in outpatients (66.7%) and student volunteers (90%). Isolates showed additional resistance to gentamicin, ciprofloxacin and trimethoprim/sulfamethoxazole but none of them was resistant to temocillin, amikacin or meropenem. Most of the strains (97%) produced a CTX-M group 1 enzymes [CTX-M-15 (98%) or CTX-M-1 (2%)] and the remaining strains produced SHV-12 enzyme (3%). CONCLUSIONS: The use of drugs such as amoxicillin, ciprofloxacin and trimethoprim/sulfamethoxazole does not seem appropriate for empirical treatment because of emerging resistance. The implementation in Cameroon or in other African countries of methods of screening ESBL-producing organisms in routine laboratories is of great importance in order for us to offer patients appropriate treatment and for infection control efforts to succeed

Clinical profiles of patients colonized or infected with extended-spectrum beta-lactamase producing Enterobacteriaceae isolates: a 20 month retrospective study at a Belgian University Hospital

<p>Abstract</p> <p>Background</p> <p>Description of the clinical pictures of patients colonized or infected by ESBL-producing <it>Enterobacteriaceae </it>isolates and admitted to hospital are rather scarce in Europe. However, a better delineation of the clinical patterns associated with the carriage of ESBL-producing isolates may allow healthcare providers to identify more rapidly at risk patients. This matter is of particular concern because of the growing proportion of ESBL-producing <it>Enterobacteriaceae </it>species isolates worldwide.</p> <p>Methods</p> <p>We undertook a descriptive analysis of 114 consecutive patients in whom ESBL-producing <it>Enterobacteriaceae </it>isolates were collected from clinical specimens over a 20-month period. Clinical data were obtained through retrospective analysis of medical record charts. Microbiological cultures were carried out by standard laboratory methods.</p> <p>Results</p> <p>The proportion of ESBL-producing <it>Enterobacteriaceae </it>strains after exclusion of duplicate isolates was 4.5% and the incidence rate was 4.3 cases/1000 patients admitted. Healthcare-associated acquisition was important (n = 104) while community-acquisition was less frequently found (n = 10). Among the former group, two-thirds of the patients were aged over 65 years and 24% of these were living in nursing homes. Sixty-eight (65%) of the patients with healthcare-associated ESBL, were considered clinically infected. In this group, the number and severity of co-morbidities was high, particularly including diabetes mellitus and chronic renal insufficiency. Other known risk factors for ESBL colonization or infection such as prior antibiotic exposure, urinary catheter or previous hospitalisation were also often found. The four main diagnostic categories were: urinary tract infections, lower respiratory tract infections, septicaemia and intra-abdominal infections. For hospitalized patients, the median hospital length of stay was 23 days and the average mortality rate during hospitalization was 13% (Confidence Interval 95%: 7-19). <it>Escherichia coli</it>, by far, accounted as the most common ESBL-producing <it>Enterobacteriaceae </it>species (77/114; [68%]) while CTX-M-1 group was by far the most prevalent ESBL enzyme (n = 56).</p> <p>Conclusion</p> <p>In this retrospective study, the clinical profiles of patients carrying healthcare-associated ESBL-producing <it>Enterobacteriacae </it>is characterized by a high prevalence rate of several major co-morbidities and potential known risk factors. Both, the length of hospital stay and overall hospital mortality rates were particularly high. A prospective case-control matched study should be designed and performed in order to control for possible inclusion bias.</p

Targeted Ablation of Oligodendrocytes Triggers Axonal Damage

Glial dysfunction has been implicated in a number of neurodegenerative diseases. In this study we investigated the consequences of glial and oligodendrocyte ablation on neuronal integrity and survival in Drosophila and adult mice, respectively. Targeted genetic ablation of glia was achieved in the adult Drosophila nervous system using the GAL80-GAL4 system. In mice, oligodendrocytes were depleted by the injection of diphtheria toxin in MOGi-Cre/iDTR double transgenic animals. Acute depletion of oligodendrocytes induced axonal injury, but did not cause neuronal cell death in mice. Ablation of glia in adult flies triggered neuronal apoptosis and resulted in a marked reduction in motor performance and lifespan. Our study shows that the targeted depletion of glia triggers secondary neurotoxicity and underscores the central contribution of glia to neuronal homeostasis. The models used in this study provide valuable systems for the investigation of therapeutic strategies to prevent axonal or neuronal damage

Astrocytes: biology and pathology

Astrocytes are specialized glial cells that outnumber neurons by over fivefold. They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS. Astrocytes respond to all forms of CNS insults through a process referred to as reactive astrogliosis, which has become a pathological hallmark of CNS structural lesions. Substantial progress has been made recently in determining functions and mechanisms of reactive astrogliosis and in identifying roles of astrocytes in CNS disorders and pathologies. A vast molecular arsenal at the disposal of reactive astrocytes is being defined. Transgenic mouse models are dissecting specific aspects of reactive astrocytosis and glial scar formation in vivo. Astrocyte involvement in specific clinicopathological entities is being defined. It is now clear that reactive astrogliosis is not a simple all-or-none phenomenon but is a finely gradated continuum of changes that occur in context-dependent manners regulated by specific signaling events. These changes range from reversible alterations in gene expression and cell hypertrophy with preservation of cellular domains and tissue structure, to long-lasting scar formation with rearrangement of tissue structure. Increasing evidence points towards the potential of reactive astrogliosis to play either primary or contributing roles in CNS disorders via loss of normal astrocyte functions or gain of abnormal effects. This article reviews (1) astrocyte functions in healthy CNS, (2) mechanisms and functions of reactive astrogliosis and glial scar formation, and (3) ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions

Uncoupling neuronal death and dysfunction in Drosophila models of neurodegenerative disease

Common neurodegenerative proteinopathies, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), are characterized by the misfolding and aggregation of toxic protein species, including the amyloid beta (Aß) peptide, microtubule-associated protein Tau (Tau), and alpha-synuclein (αSyn) protein. These factors also show toxicity in Drosophila; however, potential limitations of prior studies include poor discrimination between effects on the adult versus developing nervous system and neuronal versus glial cell types. In addition, variable expression paradigms and outcomes hinder systematic comparison of toxicity profiles. Using standardized conditions and medium-throughput assays, we express human Tau, Aß or αSyn selectively in neurons of the adult Drosophila retina and monitor age-dependent changes in both structure and function, based on tissue histology and recordings of the electroretinogram (ERG), respectively. We find that each protein causes a unique profile of neurodegenerative pathology, demonstrating distinct and separable impacts on neuronal death and dysfunction. Strikingly, expression of Tau leads to progressive loss of ERG responses whereas retinal architecture and neuronal numbers are largely preserved. By contrast, Aß induces modest, age-dependent neuronal loss without degrading the retinal ERG. αSyn expression, using a codon-optimized transgene, is characterized by marked retinal vacuolar change, progressive photoreceptor cell death, and delayed-onset but modest ERG changes. Lastly, to address potential mechanisms, we perform transmission electron microscopy (TEM) to reveal potential degenerative changes at the ultrastructural level. Surprisingly, Tau and αSyn each cause prominent but distinct synaptotoxic profiles, including disorganization or enlargement of photoreceptor terminals, respectively. Our findings highlight variable and dynamic properties of neurodegeneration triggered by these disease-relevant proteins in vivo, and suggest that Drosophila may be useful for revealing determinants of neuronal dysfunction that precede cell loss, including synaptic changes, in the adult nervous system

Effect of pre and postharvest application of fungicides on postharvest decay of Bosc pear caused by Alternaria—Cladosporium complex in North Patagonia, Argentina

In recent years, decays by Alternaria spp. and Cladosporium spp. constituted a hazard to “Bosc” pear fruit during cold storage with significant economic losses (about 50%) in the Rio Negro and Neuquen Valleys. Studies with new fungicides that potentially have good activity against these key pathogens of “Bosc” pears were carried out. During the years 2011, 2012 and 2013, commercial formulations of pyraclostrobin + boscalid (Pyr + Bosc), cyprodinil + fludioxonil (Cyp + Flu), fludioxonil (Flu), pyrimetanil (PyrM) and myclobutanil (Myc) were studied by in vitro and in vivo tests. Commercial formulations of Flu, PyrM and Myc were added to the study to be used and have a use register for pome fruits in Argentina. In vivo tests were applied postharvest on laboratory and semicommercial scale, and, preharvest, to orchard. In vitro tests showed high percentages of inhibition of mycelial growth and conidia germination of both Alternaria and Cladosporium, however Flu was highlighted in the inhibition of Alternaria (EC50 = 0.0014) and Pyr + Bosc to Cladosporium (EC50 = 1.14 × 10−8 ). In vivo assays on semi-commercial scale, showed that fungicides evaluated (Pyr + Bosc, Cyp + Flu, Flu and Pyr) applied postharvest only reduced the natural incidence of Alternaria-Cladosporium complex (4 months at −1/0 °C), between 24 and 35%, while on wounds artificially inoculated, the reduction achieved was between 91 and 98%. These results suggest that for the control of Alternaria-Cladosporium complex in Bosc pears, postharvest interventions are insufficient. In this sense, the results obtained of preharvest application of Pyr + Bosc showed that the control of the incidence of this decay after 4 months of cold storage was 44.6% of Alternaria-Cladosporium and 95% of B. cinerea. The results of this study indicate that preharvest applications, with the fungicide Pyr + Bosc, reduce the incidence of decay in postharvest, so this might be an important strategy to reduce postharvest losses in the irrigated valleys of Rio Negro y Neuquen.Fil: Lutz, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Instituto de Biotecnología Agropecuaria del Comahue; ArgentinaFil: Sosa, María Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Instituto de Biotecnología Agropecuaria del Comahue; ArgentinaFil: Colodner, Adrian D.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria Alto Valle; Argentin