98 research outputs found

    Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter

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    Context: Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles and their perturbations alter the line centroids creating a radial velocity jitter that might contaminate" the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims: We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d < 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e, CaII H & K lines, to others that hold noteworthy advantages. Methods: We used high resolution (~50000) echelle optical spectra. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R'_HK index. Results: We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity to estimate the expected RV jitter for the active stars in the sample.Comment: Accepted for publication in Astronomy & Astrophysic

    Plaguicidas en la agricultura mexicana y potenciales alternativas sustentables para su sustitución

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    La demanda de alimentos a nivel mundial se duplicará para el año 2050, para lo cual se deberá incrementar la productividad agrícola. Esta acción sugiere el uso excesivo de insumos agrícolas sintéticos, tales como los plaguicidas, con el objetivo de garantizar la producción y calidad de los alimentos. Los plaguicidas son sustancias o mezcla de sustancias que son utilizados de manera intensiva para plagas y enfermedades agrícolas; sin embargo, diversos aspectos se deben considerar para su uso extensivo. El presente trabajo muestra una revisión crítica y propositiva sobre los diferentes tipos de plaguicidas empleados en la agricultura nacional para la producción de granos y hortalizas. Además, se analiza de forma detallada la contribución de estos fungicidas a la contaminación del suelo, y las repercusiones a la salud humana. Por otra parte, se discute la legislación mexicana y la posición actual de nuestro país ante esta problemática, integrando recomendaciones y alternativas sostenibles para contribuir de forma positiva al control de plagas, mitigando los efectos al ambiente y a la salud generados por el uso de los plaguicidas empleados actualmente

    Measuring Vitamin D3 Metabolic Status, Comparison between Vitamin D Deficient and Sufficient Individuals

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    The main branch of vitamin D3 metabolism involves several hydroxylation reactions to obtain mono-, di- and trihydroxylated metabolites, including the circulating and active forms—25(OH)D3 and 1,25(OH)2D3, respectively. However, most clinical trials strictly target the determination of 25(OH)D3 to offer a view of the metabolic status of vitamin D3. Due to the growing interest in expanding this restricted view, we have developed a method for measuring vitamin D3 metabolism by determination of vitamin D3, 25(OH)D3, 24,25(OH)2D3, 1,25(OH)2D3 and 1,24,25(OH)3D3 in human plasma. The method was based on SPE–LC–MS/MS with a large volume injection of human plasma (240 µL). Detection of di- and trihydroxymetabolites, found at the picogram per milliliter level, was attained by the combined action of high preconcentration and clean-up effects. The method allows obtaining information about ratios such as the known vitamin D metabolite ratio (24,25(OH)2D3/25(OH)D3), which can provide complementary views of vitamin D3 metabolic status. The method was applied to a cohort of obese patients and a reference cohort of healthy volunteers to find metabolic correlations between target analytes as well as differences as a function of vitamin D levels within and between cohorts

    A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups

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    Nearby late-type stars are excellent targets for seeking young objects in stellar associations and moving groups. The origin of these structures is still misunderstood, and lists of moving group members often change with time and also from author to author. Most members of these groups have been identified by means of kinematic criteria, leading to an important contamination of previous lists by old field stars. We attempt to identify unambiguous moving group members among a sample of nearby-late type stars by studying their kinematics, lithium abundance, chromospheric activity, and other age-related properties. High-resolution echelle spectra (R57000R \sim 57000) of a sample of nearby late-type stars are used to derive accurate radial velocities that are combined with the precise Hipparcos parallaxes and proper motions to compute galactic-spatial velocity components. Stars are classified as possible members of the classical moving groups according to their kinematics. The spectra are also used to study several age-related properties for young late-type stars, i.e., the equivalent width of the lithium Li~{\sc i} \space 6707.8 \space \AA \space line or the RHKR'_{\rm HK} index. Additional information like X-ray fluxes from the ROSAT All-Sky Survey or the presence of debris discs is also taken into account. The different age estimators are compared and the moving group membership of the kinematically selected candidates are discussed. From a total list of 405 nearby stars, 102 have been classified as moving group candidates according to their kinematics. i.e., only \sim 25.2 \% of the sample. The number reduces when age estimates are considered, and only 26 moving group candidates (25.5\% of the 102 candidates) have ages in agreement with the star having the same age as an MG memberComment: 39 pages, 11 figures. Accepted for publication in Astronomy \& Astrophysic

    Multiplicación in vitro de ‘FHIA-25’ (Musa spp., AAB) en Sistemas de Inmersión Temporal

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    Necessity to produce high quality planting material has required searching new alternatives to increase the efficiency of in vitro propagation methods and their automation, as in Temporary Immersion Systems (TIS). This work was aimed to multiply the hybrid ‘FHIA-25’ (Musa spp. AAB) in TIS. The effect of different culture medium volumes per explant and densities of planting materials per culture flask at the same immersion frequency was determined. These two factors showed influence on the evaluated variables. A volume of 40 ml of culture medium per explant and densities of 80 explants per flask were selected to multiply this cultivar in TIS. These results permitted to increase in vitro production of high-quality plants for rooting stage.Key words: multiplication coefficient, culture flasks, liquid culture mediumLa necesidad de producir material vegetal de plantación de alta calidad, ha requerido de la búsqueda de alternativas que garanticen el incremento de la eficiencia en los métodos de propagación in vitro y su automatización, como el uso del Sistema de Inmersión Temporal (SIT). El presente trabajo fue desarrollado con el objetivo de multiplicar en SIT cultivar híbrido ‘FHIA-25’ (Musa spp., AAB). Se determinó el efecto de diferentes volúmenes de medio de cultivo por explante y densidades de material vegetal por frasco de cultivo a una misma frecuencia de inmersión. Se comprobó que estos dos factores tuvieron influencia sobre las variables evaluadas. Se seleccionaron 40 ml de volumen de medio de cultivo por explante y una densidad de 80 explantes/frasco para multiplicar este cultivar en SIT. Estos resultados permitieron incrementar la producción de plantas in vitro de mayor calidad para la fase de enraizamiento.Palabras clave: coeficiente de multiplicación, frasco de cultivo, medio de cultivo líquid

    HCV-coinfection is related to an increased HIV-1 reservoir size in cART-treated HIV patients: a cross-sectional study

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    In HIV-1/HCV-coinfected patients, chronic HCV infection leads to an increased T-lymphocyte immune activation compared to HIV-monoinfected patients, thereby likely contributing to increase HIV-1 reservoir that is the major barrier for its eradication. Our objective was to evaluate the influence of HCV coinfection in HIV-1 viral reservoir size in resting (r) CD4+ T-cells (CD25-CD69-HLADR-). Multicenter cross-sectional study of 97 cART-treated HIV-1 patients, including 36 patients with HIV and HCV-chronic co-infection without anti-HCV treatment, 32 HIV patients with HCV spontaneous clearance and 29 HIV-monoinfected patients. rCD4+ T-cells were isolated and total DNA was extracted. HIV viral reservoir was measured by Alu-LTR qPCR. Differences between groups were calculated with a generalized linear model. Overall, 63.9% were men, median age of 41 years and Caucasian. Median CD4+ and CD8+ T-lymphocytes were 725 and 858 cells/mm 3 , respectively. CD4+ T nadir cells was 305 cells/mm 3 . Proviral HIV-1 DNA size was significantly increased in chronic HIV/HCV-coinfected compared to HIV-monoinfected patients (206.21 ± 47.38 vs. 87.34 ± 22.46, respectively; P = 0.009), as well as in spontaneously clarified HCV co-infected patients when compared to HIV-monoinfected individuals (136.20 ± 33.20; P = 0.009). HIV-1/HCV co-infected patients showed a larger HIV-1 reservoir size in comparison to HIV-monoinfected individuals. This increase could lead to a greater complexity in the elimination of HIV-1 reservoir in HIV-1/HCV-coinfected individuals, which should be considered in the current strategies for the elimination of HIV-1 reservoir.Financial support was provided by the Instituto de Salud Carlos III to VB (PI15CIII/00031), by the Spanish Ministry of Economy and Competitiveness to MC (SAF2016–78480-R) and The SPANISH AIDS Research Network RD16CIII/0002/0001, RD16CIII/0002/0002 and RD16/0025/0013 - ISCIII – FEDER. MRLP is supported by ISCIII - Subdirección General de Evaluacion and European Funding for Regional Development (FEDER) (PIE 13/00040 and RD12/0017/0017 RETIC de SIDA). C.P. is supported by the Portuguese Fundação para a Ciência e Tecnologia (FCT) (grant number SFRH/ BPD/77448/2011 is part of the EDCTP2 programme supported by the European Union). V.B., A.F.R. and N.R. are supported by the Miguel Servet programme from Fondo de Investigación Sanitaria (ISCIII) (grant number CP13/00098, CP14/CIII/00010 and CP14/00198, respectively)

    Compromising between European and US allergen immunotherapy schools: Discussions from GUIMIT, the Mexican immunotherapy guidelines

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    Background: Allergen immunotherapy (AIT) has a longstanding history and still remains the only disease-changing treatment for allergic rhinitis and asthma. Over the years 2 different schools have developed their strategies: the United States (US) and the European. Allergen extracts available in these regions are adapted to local practice. In other parts of the world, extracts from both regions and local ones are commercialized, as in Mexico. Here, local experts developed a national AIT guideline (GUIMIT 2019) searching for compromises between both schools. Methods: Using ADAPTE methodology for transculturizing guidelines and AGREE-II for evaluating guideline quality, GUIMIT selected 3 high-quality Main Reference Guidelines (MRGs): the European Academy of Allergy, Asthma and Immunology (EAACI) guideines, the S2k guideline of various German-speaking medical societies (2014), and the US Practice Parameters on Allergen Immunotherapy 2011. We formulated clinical questions and based responses on the fused evidence available in the MRGs, combined with local possibilities, patient's preference, and costs. We came across several issues on which the MRGs disagreed. These are presented here along with arguments of GUIMIT members to resolve them. GUIMIT (for a complete English version, see Supplementary data) concluded the following: Results: Related to the diagnosis of IgE-mediated respiratory allergy, apart from skin prick testing complementary tests (challenges, in vitro testing and molecular such as species-specific allergens) might be useful in selected cases to inform AIT composition. AIT is indicated in allergic rhinitis and suggested in allergic asthma (once controlled) and IgE-mediated atopic dermatitis. Concerning the correct subcutaneous AIT dose for compounding vials according to the US school: dosing tables and formula are given; up to 4 non-related allergens can be mixed, refraining from mixing high with low protease extracts. When using European extracts: the manufacturer's indications should be followed; in multi-allergic patients 2 simultaneous injections can be given (100% consensus); mixing is discouraged. In Mexico only allergoid tablets are available; based on doses used in all sublingual immunotherapy (SLIT) publications referenced in MRGs, GUIMIT suggests a probable effective dose related to subcutaneous immunotherapy (SCIT) might be: 50–200% of the monthly SCIT dose given daily, maximum mixing 4 allergens. Also, a table with practical suggestions on non-evidence-existing issues, developed with a simplified Delphi method, is added. Finally, dissemination and implementation of guidelines is briefly discussed, explaining how we used online tools for this in Mexico. Conclusions: Countries where European and American AIT extracts are available should adjust AIT according to which school is followed

    Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

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    Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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