808 research outputs found

    Larval drift of of sábalo, Prochilodus lineatus (Valenciennes, 1847) and other fish species with commercial value, in the lower Paraná river

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    Entre 1990 y 1997 se realizaron diversos muestreos para el estudio de la deriva delarvas de sábalo Prochilodus lineatus y otros peces de interés comercial en el río Paraná Inferior, a la altura del límite con el río Paraná Medio (ciudad de Diamante) yel rio Paraná de Las Palmas (ciudad de Zárate). Se observaron diferencias en la composición especifica y Ia densidad de larvas. Noobstante, el sábalo fue la especie más abundante en ambos sitios, donde representómás del 40 % del ictioplancton. La presencia de huevos de peces, así como deestadios muytempranos de sábalo solamente en Diamante, al norte, sugiere que losdesoves de los stocks meridionales de ésta, y otras especies migratorias, tienenlugar principalmente en el tramo medio del río Paraná. El sábalo se reprodujo activamente al final de la primavera y en el verano contemperaturas del agua entre 22 °C y 27 °C. Los datos sugieren que el ciclo demaduración podría ser controlado por el fotoperíodo y/o la temperatura, mientras quelos ascensos sostenidos del nivel de las aguas dispararían Ia actividad reproductivamasiva. Estas investigaciones apoyan la hipótesis de que el sábalo, en el curso de suevolución, ha desarrollado una estrategia reproductiva compleja, que involucradesplazamientos ascendentes, desoves en el canal asociados a las crecientes, ydispersión de los estadios de desarrollo tempranos en una extensa área de críaaguas abajo. Esta es una de las características biológicas que explicarían laabundancia de la especie, pero, al mismo tiempo, la hacen particularmentevulnerable a las transformaciones ambientales, como las producidas por laconstrucción de represasDuring 1990 to 1997, several sampling programs to study the larval fish drift of the "sábalo" Prochilodus lineatus, were carried out in the limit between the middle andthe lower Paraná river (Diamante City) and southwards in Paraná de Las Palmasriver (Zárate City). There were differences in the species composition and densitiesof larval fish between sites. However, the "sábalo" Prochilodus lineatus, was the mostabundant species, reaching more than 40 % in both cases. Presence of fish eggs and newly hatched larvae of sábalo only at the northern site,suggests that the spawning areas of the meridional stocks of these and othermigratory species are located in the Middle Paraná river. Sábalo actively spawned in late spring and summer with water temperatures between 22 °C and 27 °C. Data suggest that the maturation cycle could be overly controlled byfactors as photoperiod and/or water temperature, while raising water levels maytrigger massive spawning activity. These studies support the hypothesis that sábalo has evolved a complexreproductive strategy, involving upstream migrations, channel spawning during risingwaters, and a wide dispersion of larvae in extensive downstream nursery areas. Thismay be one of the biological features that explain the great abundance of thisspecies, but at the same time makes it particularly vulnerable to environmentaltransformations, as those produced by damming.Fil: Fuentes, Carlos Mariano. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

    Ontogenetic changes in DNA and RNA content of laboratory-reared Prochilodus lineatus larvae: use of RNA/DNA ratios as indicators of nutritional condition

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    The aims of the present study were to describe the ontogenetic performance of DNA and RNA content, as well as to assess the nutritional condition of Prochilodus lineatus larvae reared under different feeding treatments. The experiment consisted of two parts, the first 6-14 days after hatching (DAH) and the second 15-21 DAH. In the first part of the experiment, larvae were kept under one of two feeding treatments: fed or starved. During the second part of the experiment, larvae were kept under one of four treatments: fed, fed until 14 DAH and later starved, starved until 14 DAH and fed later or starved. It is of note that the size and weight reached of larvae that were starved during early development and later received food were higher than those of than larvae in the other feeding treatments. In addition, instantaneous growth rates were higher and nutritional condition was better in larvae that were initially starved and fed later. The availability of food following a period of starvation seems to trigger larval metabolism and cellular division. Consequently, we recommend maintaining appropriate food provision in the aquaculture of P. lineatus larvae, especially in advanced developmental stages. We verified that RNA/DNA ratio is affected by the feeding condition and that it is sensitive enough to promptly reflect changes in feeding conditions of P. lineatus larvae. Thus, the RNA/DNA ratio could be used to assess nutritional condition of both wild and cultured P. lineatus larvae.Fil: Diaz, Marina Vera. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Gómez, M. I.. Dirección de Pesca Continental; ArgentinaFil: Sánchez, S.. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Instituto de Ictiología del Nordeste; ArgentinaFil: Fuentes, Carlos Mariano. Dirección de Pesca Continental; Argentin

    Cuajado y Desarrollo de los Frutos Cítricos

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    El fruto de los cítricos es una baya típica llamada hesperidio. En él se pueden distinguir las siguientes partes (Foto 1) (González-Sicilia, 1968; Schneider, 1968): - Exocarpo o flavedo, que es la región más externa y constituye la parte visible de la corteza, formada por células epidérmicas de color verde cuando el fruto es inmaduro y naranja o amarillo, según la especie, en la madurez. - Mesocarpo o albedo, que es la región situada debajo del exocarpo, formado por un tejido blanco esponjoso de células parenquimáticas. - Endocarpo, que es la región más interna y está constituido por los lóculos o gajos. Los lóculos contienen las vesículas de zumo, formadas por un cuerpo de células completamente vacuolizadas y un pedúnculo que las mantiene unidas a la epidermis dorsal de los carpelos y limitadas lateralmente por los septos. El exocarpo y mesocarpo constituyen la corteza del fruto propiamente dicha. Dentro de los lóculos del endocarpo se encuentran las semillas

    Respuesta funcional de diferentes instares larvales de Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) sobre ninfas de Bactericera cockerelli (Sulc) (Homoptera: Psyllidae)

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    Bactericera cockerelli (Sulc) (Homoptera: Psyllidae) es una plaga importante de solanaceas en México; para su control, la utilización de plaguicidas es el principal método, por lo que el uso de enemigos naturales bajo un sistema de manejo integrado, ha sido poco utilizado. Tal es el caso de Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), agente de control biológico reportado para esta plaga; sin embargo, se carece de estudios para conocer su potencial. El objetivo del presente trabajo consistió en determinar el tipo y los parámetros de respuesta funcional de C. carnea sobre ninfas de B. cockerelli. El análisis de regresión logística reveló que la respuesta funcional de los tres instares larvales de C. carnea sobre ninfas de B. cockerelli fue de tipo II. Los tres instares consumieron ninfas de B. cockerelli, sin embargo el tercer instar tuvo mayor consumo, menor tiempo de manipuleo y mayor coeficiente de ataque. Estos resultados demostraron que C. carnea fue voraz y su capacidad depredadora está en función de su estado de desarrollo. El tercer instar reveló altas posibilidades para reducir las poblaciones de esta plaga, lo que sugiere que puede ser incluido en sistemas de manejo integrado de plagas basados en el control biológico aumentativo.Bactericera cockerelli (Sulc) (Homoptera: Psyllidae) es una plaga importante de solanaceas en México; para su control, la utilización de plaguicidas es el principal método, por lo que el uso de enemigos naturales bajo un sistema de manejo integrado, ha sido poco utilizado. Tal es el caso de Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), agente de control biológico reportado para esta plaga; sin embargo, se carece de estudios para conocer su potencial. El objetivo del presente trabajo consistió en determinar el tipo y los parámetros de respuesta funcional de C. carnea sobre ninfas de B. cockerelli. El análisis de regresión logística reveló que la respuesta funcional de los tres instares larvales de C. carnea sobre ninfas de B. cockerelli fue de tipo II. Los tres instares consumieron ninfas de B. cockerelli, sin embargo el tercer instar tuvo mayor consumo, menor tiempo de manipuleo y mayor coeficiente de ataque. Estos resultados demostraron que C. carnea fue voraz y su capacidad depredadora está en función de su estado de desarrollo. El tercer instar reveló altas posibilidades para reducir las poblaciones de esta plaga, lo que sugiere que puede ser incluido en sistemas de manejo integrado de plagas basados en el control biológico aumentativo

    Aging and Brain Deterioration

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    Carlos Dotti and Vicente Rodríguez (coordinators).Advanced age significantly increases the risk of developing chronic diseases such as cancer, diabetes, cardiovascular, immune and mental disease. Regarding the latter, advanced age is a necessary factor for the development of non-hereditary forms of neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Despite years of intense research, we still do not know how these diseases occur, this being one of the main reasons for the lack of adequate interventions to prevent or cure these pathologies. To overcome the current limitations in the field, we plan to: 1) generate basic knowledge on the mechanisms responsible for cognitive, behavioral, motor, metabolic and sociability disorders that occur with age, 2) define the mechanisms that determine individual susceptibility to neurodegeneration, 3) design and develop strategies to improve brain aging, and 4) explore social and environmental conditions of the older population to know their influence in brain degeneration. Individual, social and policy interventions must be considered for future research.Peer reviewe

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

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    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

    RICORS2040 : The need for collaborative research in chronic kidney disease

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    Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is 'solved' by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true

    Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

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    Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

    Robust estimation of bacterial cell count from optical density

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    Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
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