University of Costa Rica
  • San José, Costa Rica
Recent publications
Leucine is an essential branched-chain amino acid required for skeletal muscle protein synthesis as a substrate and as a key anabolic signaling molecule primarily via activation of the mTORC1. Leucine supplementation has been proposed to enhance muscle adaptations, with some studies showing improvements in muscle growth. However, results from randomized controlled trials (RCTs) have been inconclusive, potentially due to variations in resistance exercise protocols and Leu dose or duration of supplementation. This systematic review explores the effects of leucine supplementation on resistance-training-induced muscle growth, strength, and recovery in healthy individuals. A systematic literature search was conducted across multiple databases (MedLine, EMBASE, PubMed, Science Direct, Scopus, and Cochrane) to identify RCTs investigating the effect of leucine intake on markers of muscle growth, strength, and recovery in trained adults aged 18 to 40 years old. A total of 14 RCTs were identified including acute (n = 5) and chronic leucine (n = 9) supplementation. A total of 13 studies did not find significant differences in muscle mass, strength, or recovery between leucine-supplemented and placebo groups. The evidence from this systematic review suggests that leucine supplementation does not confer significant benefits in muscle growth, strength, or recovery in healthy, trained young adults.
Many Drosophila species coexist by sharing their feeding and breeding sites, which may influence their oviposition choices in an interspecies social context. Whether and where to lay eggs is a crucial decision for female flies as it influences the success of their offspring, by minimizing the risk of predation, competition, or cannibalism. Significant gaps exist in our understanding of Drosophila oviposition dynamics in co-occurring species. Here we tested oviposition strategies of Drosophila melanogaster and its close relative Drosophila simulans under different conditions, to assess whether a single female would prefer to oviposit separately or together with another female, be it a conspecific or not. We find that ovipositing females, regardless whether they are conspecifics or not, prefer to oviposit at the same site. This might suggest that the flies regard the benefits of sharing oviposition sites as higher than the potential risks of competition or cannibalism. The willingness to share oviposition sites was lower when the nutritional value of the medium was increased by adding yeast, and was lost when flies were allowed to lay the eggs consecutively, instead of being tested together. The latter might be explained by our additional finding that females become attracted by the presence of other females on oviposition substrates and that this attraction is partly driven by visual cues. Ovipositing in groups might facilitate intra- and interspecific social feeding of same age offspring, as well as enrichment of microbes. However, this cooperation dynamic might change if another female’s offspring is already present, as it might be perceived as danger of competition or cannibalism.
Urban green spaces (UGS) provide essential ecosystem services (ES), for example, precipitation infiltration for flood mitigation, transpiration (Tr) for local atmosphere cooling and groundwater recharge (Gr) for drinking water provision. However, vegetation type impacts the ecohydrological partitioning of incoming precipitation and therefore ES provision, whilst flux rate potential is different in disparate hydroclimates. Consequently, paired studies in different hydroclimates are useful to understand similarities and differences in vegetation controlled ecohydrological partitioning to effectively guide UGS management. We simultaneously undertook sub‐daily soil moisture measurements beneath three contrasting urban vegetation types (grass, shrub, mature tree) between 01/01/2021 and 31/12/2023 for an inter‐comparison of an energy‐limited Scottish and a moisture‐limited region of Germany. These data were integrated with hydroclimatic and sapflux data in the EcoHydroPlot model to constrain estimates of ecohydrological fluxes. Soil moisture data showed clear effects of the contrasting hydroclimates, with high and low VWC values in Scotland and Germany, respectively, whilst evapotranspiration potential was ~50% greater in Germany. Consequently, ecohydrological functioning and flux rates were fundamentally different, with Tr dominant in Germany and Gr dominant in Scotland. However, vegetation cover was shown in both countries to be a key control on urban ecohydrological partitioning with grass encouraging Gr, contrasting to evergreen shrubs in Scotland and mature trees in Germany elevating Tr. In Germany, impacts to hydrological functioning due to low soil VWC were marked with the mature trees high Tr rate shutting down Gr for the majority of the study period. The German site also showed greater hydrological functioning susceptibility to inter‐annual hydroclimatic variability with all fluxes heavily suppressed during the 2022 drought. In contrast, the high VWC in Scotland provided some buffer against ongoing negative rainfall anomalies. Overall, the study indicated the importance of diverse UGS vegetation cover to encourage contrasting ecohydrological fluxes.
Background Snakebite (SB) envenoming is an acute emergency requiring early care delivery. However, sometimes, patients can take several hours before receiving antivenom (AV). We conducted this study to assess the effectiveness of antivenom in the recovery of clotting parameters in patients consulting tardily after SB envenoming in French Guiana. The primary endpoint of our study was to investigate the time needed from SB to recovery from SB-induced coagulopathy. The secondary endpoint was to investigate the time needed from AV administration to recovery from SB-induced coagulopathy in patients receiving AV (late or very late administration). Methods This prospective observational study was conducted in the Intensive Care Unit (ICU) of Cayenne General Hospital between January 2016 and September 2023. We included all patients hospitalized for SB envenoming who either did not receive AV or received it more than 6 h after SB. We excluded patients who received antivenom in less than 6 h from the SB and those who received incomplete AV doses. Findings We included 58 patients in the No AV group, 51 in the late AV group (6 h ≤ AV < 12 h), and 50 in the very late AV group (AV≥12 h). The median age of patients was 42 years (IQR: 29–53), 65.4% were male and 34.6% were female (104 and 55 out of 159 patients) without difference regarding the demographic parameters between groups. Data regarding ethnicity was not available. The median time from SB to AV was 8.5 h (IQR: 6.9–10) in the late AV group and 21.1 h (IQR: 16.7–27.4) in the very late AV group (p < 0.001). The time from SB to normal clotting parameters was shorter in patients receiving late AV than in those receiving very late AV and those not receiving AV. No differences were observed in the time from SB and recovery of fibrinogen and activated partial thromboplastin time (aPTT) between very late AV and no AV. However, the International Normalized Ratio (INR) recovery was shorter in the very late AV group than in the no AV group. On the other hand, the time from AV to normal fibrinogen was shorter in patients receiving very late AV than in patients receiving late AV (Log-Rank = 0.020). Meanwhile, the time from AV to normal INR or normal aPTT was similar in patients receiving very late AV compared to patients receiving late AV (Log-Rank = 0.722 and 0.740, respectively). Interpretation Late AV administration effectively reverses coagulopathic manifestations after SB envenoming. However, very late AV administration did not improve the correction of some clotting parameters when compared to patients not receiving AV. Our findings could be explained by the combination of venom toxicokinetics and the kinetics of the synthesis of clotting factors. Funding No funding.
Background: Several studies have shown that tranexamic acid (TXA), an anti-fibrinolytic agent, may reduce hematoma expansion (HE) in intracerebral hemorrhage (ICH), but its therapeutic time window is unclear. We analyzed the efficacy and safety of TXA based on its time of administration after hemorrhage onset. Methods: We searched PubMed, Embase and Cochrane databases for randomized controlled trials (RCTs) published up to July 27, 2024 comparing TXA with placebo in ICH. We excluded trials that used TXA for longer than 3 days which causes delayed vasospasm, increasing the risk of cerebral ischemia. The primary outcomes were HE, 24-hour hemorrhagic volume change, 90-day mortality and poor functional outcome. We grouped the trials into 2 hours, 8 hours or 24 hours of TXA administration after hemorrhage onset. We pooled odds ratios (OR) and mean differences (MD) with 95% confidence intervals (CI) using Rstudio. Heterogeneity was examined with the I2 test. Results: We included 12 studies with 3,567 patients. Most of the studies used 1 g TXA in patients with Glasgow Coma Scale score ranging from 13-15. TXA reduced HE risk (OR 0.85; 95% CI 0.73 to 0.98; p= 0.03; I2= 0%). This reduction was observed in studies that administered TXA within 8 hours of ICH onset (OR 0.82; 95% CI 0.70 to 0.97; p= 0.02; I2= 0%). TXA slightly reduced 24-hour hemorrhagic volume (MD -1.30 mL; 95% CI -2.51; -0.09; p= 0.04; I2= 47%). This reduction was mainly seen in patients who were administered TXA within 8 hours of hemorrhage onset (MD -1.86 mL; 95% CI -3.15 to -0.58; p< 0.01; I2= 35%). There were no significant differences in poor functional outcome (OR 0.87; 95% CI 0.67 to 1.15; p= 0.34; I2= 24%), 90-day mortality (OR 1.00; 95% CI 0.84 to 1.19; p= 0.96; I2= 0%), major thromboembolic events (OR 1.22; 95% CI 0.82 to 1.82; p= 0.33; I2= 0%), neurosurgical intervention (OR 0.94; 95% CI 0.61-1.45; p= 0.78; I2= 0%) or length of hospital stay (MD -0.49 days; 95% CI -3.27 to 2.29; p= 0.73; I2= 0%). Conclusion: TXA reduced the risk of HE and slightly reduced 24-hour hemorrhagic volume in patients with ICH within 8 hours. Larger RCTs stratifying administration timing are required to establish these findings.
Energy poverty remains a critical challenge in Central America, where significant disparities in access to modern energy services persist. These disparities are closely linked to income inequality and are more pronounced in rural areas than in urban centers. In 2014, Guatemala had the highest level of unequal access to electricity across all income levels, while Costa Rica had the best access. Despite improvements in countries such as Panama, Costa Rica, and El Salvador between 2016 and 2022, many households, particularly in economically disadvantaged regions, still rely on low-quality energy sources such as firewood and charcoal for cooking. Indigenous populations in Guatemala, Nicaragua, and Panama face severe ethnic segregation in access to electricity, although access among these communities is gradually increasing. This chapter explores the multifaceted issue of energy poverty in Central America, examining its social, economic, and geographic dimensions. It highlights key challenges, including limited electricity infrastructure, high energy costs, political instability, and climate vulnerability. It also discusses potential solutions and initiatives, such as the development of renewable energy, the implementation of energy efficiency measures, policy and regulatory reforms, and improved access to financing. It also reviews government efforts to promote an integrated energy policy agenda focused on renewable energy, energy transition and energy security. These challenges can be addressed through comprehensive and sustainable strategies, the region can work towards equitable access to modern energy services for all its inhabitants.
As scientists, change is the only constant in our journey. We often find ourselves in transition from one laboratory to another, and during our training we are fortunate to experience the excitement of pursuing postgraduate studies abroad in well‐funded, high‐level research centers. However, after completing doctoral or postdoctoral training, we are frequently drawn to return to our home countries, where funding and support for science are significantly more limited. In this brief commentary, first, I would like to highlight the challenges faced by scientists from developing countries who have had the opportunity to train internationally and then choose to return home, driven both by personal motivations (e.g., family) and by the desire to contribute to the scientific advancement of their regions. Second, I would like to share some advice that has been especially useful to me in establishing my laboratory, defining research topics, and maintaining academic productivity. I hope these insights can be useful to colleagues in similar situations across different regions. Although starting a research group in regions with less investment in Research and Development is challenging, it is achievable with perseverance and the implementation of concrete actions.
The highly electrophilic 1,4‐di‐t‐butyl‐2,2,3,3‐tetramethyl‐1,4‐diphenyltetrasilane‐1,4‐diyl bis(trifluoromethanesulfonate) (11) reacts with water to yield the cis/trans isomer mixture of 2,5‐di‐t‐butyl‐3,3,4,4‐tetramethyl‐2,5‐diphenyl‐1‐oxa‐2,3,4,5‐tetrasilacyclopentane (12). Cis‐12 and trans‐12 were separated and fully characterized by structural, spectroscopic and theoretical means. Remarkably, cis‐12 is preferably formed in the reaction mixtures, and the calculations reveal that this isomer is slightly more stable than trans‐12. This is due to the torsional distortion established in the crystal structure of the former isomer. Additionally, the electronic transitions between silicon backbone, the Ph substituents and the oxygen atoms are accounted for the main absorptions observed in the UV spectra of cis‐12 and trans‐12.
Among the five MLST clades encompassing the known global population of the bacterial pathogen Clostridioides difficile, strains from Clade 2 have been given special attention due to the worldwide spread, disease presentation, and prevalence in hospital settings of ST01 strains. We aimed to compare multiple phenotypic properties of clinical Clade 2 ST01 and non-ST01 strains from ST41, ST47, ST67, ST154, and ST638 to identify factors contributing to the higher virulence and epidemic potential that has been historically attributed to the former group of strains. We did not find significant differences in virulence markers such as spore adherence, motility, biofilm formation, and spore disinfectant resistance. Instead, the tested ST01 strains exhibited distinctive surface layer protein A (SlpA) and toxin B (TcdB) profiles that triggered unique immune and cytotoxic responses. These insights challenge the prevailing notion that all Clade 2 strains are highly virulent and inform Public Health strategies for ST01 strain management.
Skates and rays (Batoidea) play a significant ecological role, contributing to ecosystem services through bioturbation and acting as vital intermediate components of the trophic chain in various aquatic environments. Despite their wide global distribution and ecological importance, batoids receive less attention than their shark relatives, resulting in substantial knowledge gaps that might impede a comprehensive understanding of their conservation status. This review addresses critical aspects of their capture, handling, tagging, and release to provide readers with crucial information needed to perform research on batoids. Protocols for analgesia, anaesthesia, and euthanasia are also discussed, taking into account the ethical and logistical considerations necessary for research involving this group of species. This information can give researchers and ethics committees the knowledge to conduct and approve studies involving batoids, thereby promoting more effective and ethical research practices.
Here we report the draft genome sequences of four Bradyrhizobium spp. isolates obtained from root nodules of the native legumes Pentaclethra macroloba, Chamaecrista nictitans, Erythrina fusca, and Zygia engelsingii in tropical forests of Costa Rica. Genomes ranged from 8.6 to 9.8 Mb with GC contents between 62.8% and 63.8%. Phylogenomic analysis, along with Average Nucleotide Identity (ANI) and digital DNA-DNA hybridization (dDDH) comparisons, confirmed these isolates represent potential new species. ANI values ranged from 88.3% to 90.3%, and dDDH values from 28.8% to 41.8%, compared to their closest Bradyrhizobium sp. references. Functional annotation revealed some genes related to nitrogen fixation (nifA, nifB, nifH) and nodulation capacity (nodB, nodC, nodJ). These results provide insights into the diversity and symbiotic capabilities of Bradyrhizobium in tropical ecosystems.
The main purpose of this study was to examine the age-related changes in inhibitory control of 450 children at the ages of 7–8, 11–12, and 14–16 when controlling for working memory capacity (WMC) and processing speed to determine whether inhibition is an independent factor far beyond its possible reliance on the other two factors. This examination is important for several reasons. First, empirical evidence about age-related changes of inhibitory control is controversial. Second, there are no studies that explore the organization of inhibitory functions by controlling for the influence of processing speed and WMC in these age groups. Third, the construct of inhibition has been questioned in recent research. Multigroup confirmatory analyses suggested that inhibition can be organized as a one-dimension factor in which processing speed and WMC modulate the variability of some inhibition tasks. The partial reliance of inhibitory processes on processing speed and WMC demonstrates that the inhibition factor partially explains the variance of inhibitory tasks even when WMC and processing speed are controlled and some methodological concerns are addressed.
Understanding tri-trophic interactions and the relationship among plants, herbivores, and their natural enemies is fundamental to advancing theoretical and practical ecology. Parasitoidism is among those interactions where tri-trophic levels are usually developed, with hyperparasitism and kleptoparasitism as examples. This study explores the interaction between fig wasps of the genera Physothorax Mayr, 1885 and Sycophila Walker, 1871 (Hymenoptera: Chalcidoidea) and the gall midge Ficiomyia brasiliensis Urso-Guimarães, 2024 (Diptera: Cecidomyiidae) associated with Ficus citrifolia Mill. in Ribeirão Preto, Brazil. Through behavioral observations and larval dissections we document the “drill on drill” strategy where Sycophila females utilize oviposition holes drilled by Physothorax females on the fig surface to access the host gall midge immatures. This behavior suggests a sophisticated adaptation for reducing oviposition time and conserving energy. Additionally, Sycophila behavior aligns with kleptoparasitic and hyperparasitic strategies, indicating a complex evolutionary history and ecological interaction. Our findings provide insight into the intricate relationships among non-pollinating fig wasps and their hosts, contributing to the broader understanding of tri-trophic interactions in fig microcosm. Keywords: Evolutionary ecology; Insect-plant interaction; Host-parasite interactions; Oviposition behavior; Parasitic wasps
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14,539 members
Mariangela Vargas
  • Instituto Clodomiro Picado (ICP)
Alejandra M. Rojas González
  • Escuela de Ingeniería de Biosistemas
Alejandro Chacon
  • Estación Experimental de Ganado Lechero Alfredo Volio Mata (EEAVM)
Ricardo Radulovich
  • Department of Biosystems Engineering
Daniel Chavarria-Bolaños
  • Departamento de Ciencias Diagnósticas y Quirúrgicas
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San José, Costa Rica
Head of institution
Carlos Araya Leandro