Does the evolution of ontogenetic niche shifts favour species coexistence? An empirical test in Trinidadian streams.

A major question in ecology is how often competing species evolve to reduce competitive interactions and facilitate coexistence. One untested route for a reduction in competitive interactions is through ontogenetic changes in the trophic niche of one or more of the interacting species. In such cases, theory predicts that two species can coexist if the weaker competitor changes its resource niche to a greater degree with increased body size than the superior competitor. We tested this prediction using stable isotopes that yield information about the trophic position (δ15 N) and carbon source (δ13 C) of two coexisting fish species: Trinidadian guppies Poecilia reticulata and killifish Rivulus hartii. We examined fish from locations representing three natural community types: (1) where killifish and guppies live with predators, (2) where killifish and guppies live without predators and (3) where killifish are the only fish species. We also examined killifish from communities in which we had introduced guppies, providing a temporal sequence of the community changes following the transition from a killifish only to a killifish-guppy community. We found that killifish, which are the weaker competitor, had a much larger ontogenetic niche shift in trophic position than guppies in the community where competition is most intense (killifish-guppy only). This result is consistent with theory for size-structured populations, which predicts that these results should lead to stable coexistence of the two species. Comparisons with other communities containing guppies, killifish and predators and ones where killifish live by themselves revealed that these results are caused primarily by a loss of ontogenetic niche changes in guppies, even though they are the stronger competitor. Comparisons of these natural communities with communities in which guppies were translocated into sites containing only killifish showed that the experimental communities were intermediate between the natural killifish-guppy community and the killifish-guppy-predator community, suggesting contemporary evolution in these ontogenetic trophic differences. These results provide comparative evidence for ontogenetic niche shifts in contributing to species coexistence and comparative and experimental evidence for evolutionary or plastic changes in ontogenetic niche shifts following the formation of new communities.

The evolution of size-dependent competitive interactions promotes species coexistence.

Theory indicates that competing species coexist in a community when intraspecific competition is stronger than interspecific competition. When body size determines the outcome of competitive interactions between individuals, coexistence depends also on how resource use and the ability to compete for these resources change with body size. Testing coexistence theory in size-structured communities, therefore, requires disentangling the effects of size-dependent competitive abilities and niche shifts. Here, we tested the hypothesis that the evolution of species- and size-dependent competitive asymmetries increased the likelihood of coexistence between interacting species. We experimentally estimated the effects of size-dependent competitive interactions on somatic growth rates of two interacting fish species, Trinidadian guppies Poecilia reticulata and killifish Rivulus hartii. We controlled for the effects of size-dependent changes in the niche at two competitive settings representing the early (allopatric) and late (sympatric) evolutionary stages of a killifish-guppy community. We fitted the growth data to a model that incorporates species- and size-dependent competitive asymmetries to test whether changes in the competitive interactions across sizes increased the likelihood of species coexistence from allopatry to sympatry. We found that guppies are competitively superior to killifish but were less so in sympatric populations. The decrease in the effects of interspecific competition on the fitness of killifish and increase in the interspecific effect on guppies' fitness increased the likelihood that sympatric guppies and killifish will coexist. However, while the competitive asymmetries between the species changed consistently between allopatry and sympatry between drainages, the magnitude of the size-dependent competitive asymmetries varied between drainages. These results demonstrate the importance of integrating evolution and trait-based interactions into the research on how species coexist.

Morfometría y biotipo de futbolistas varones categorías sub 15 y sub 16 pertenecientes a una escuela deportiva / Morphometry and biotype of male soccer players categories under 15 and under 16 from a sports school

RESUMEN: En las categorías deportivas juveniles, los parámetros morfológicos y biotipológicos son difíciles de determinar ya que es complejo separar los cambios propios de la formación deportiva, de los asociados al crecimiento y la maduración. El objetivo de esta investigación fue establecer características antropométricas y perfiles somatotípicos de adolescentes varones futbolistas chilenos de una escuela deportiva. La muestra estuvo compuesta por 23 jóvenes categoría sub 15 y 30 jóvenes sub 16. Se registraron el peso (kg), estatura (cm), seis pliegues cutáneos, dos diámetros y cinco perímetros. El índice de masa muscular (IMC) se calculó según fórmula de Quetelet. El fraccionamiento de la masa corporal se estimó según la masa grasa (MG), masa muscular (MM), masa residual (MR) y masa ósea (MO). Se describió el somatotipo utilizando el método de Heath & Carter. Los datos fueron analizados en estadístico para tendencia central, porcentajes y significancia según prueba t(p<0,05). Los resultados no muestran diferencias significativas en los patrones antropométricos y biotipológicos entre las dos categorías. Los promedios observados fueron: peso: 60,2 ± 7,6 (kg); Talla: 169,1 ± 5,3 (cm); IMC: 21,2 ± 2,0; % MG: 24,3 ± 2,7; %MM: 45,2 ± 2,9. Somatotipo para jóvenes sub 15 fue de: 2,4 ± 0,7/ 4,5 ± 0,8 / 3,0 ± 1,1 y para sub 16 de: 2,3 ± 1,0/ 4,3 ± 0,8 / 3,0 ± 0,9. Estos resultados son similares a los observados en otras escuelas deportivas de Chile y el mundo. Se concluye que altos porcentajes de masa musculary los componentes meso-ectomórficos, serían características morfológicas en este tipo de deportistas. Se sugiere considerar estos factores, además de considerar los factores sociales y psicológicos, la maduración corporal, centrando el quehacer de los adolescentes más en favorecer un estilo de vida sana y activa que en lo competitivo.

SUMMARY: In youth sports categories, morphological and biotypological parameters are difficult to determine since it is complex to separate the changes inherent to sports training from those associated with growth and maturation. The objective of this research was to establish anthropometric characteristics and somatotypic profiles of adolescent Chilean male soccer players from a sports training school. The sample consisted of 23 young people under 15 and 30 young people under 16. Weight (kg), height (cm), six skin folds, two diameters and five perimeters were recorded. The muscle mass index (BMI) was calculated according to the Quetelet formula. The fractionation of body mass was estimated according to fat mass (FM), muscle mass (MM), residual mass (RM), and bone mass (BM). The somatotype was described using the Heath & Carter method. The data were analyzed statistically for central tendency, percentages and significance according to the t test (p <0.05). The results show anthropometric and biotypological patterns without significant differences between the two categories. The averages observed werefor: weight: 60.2 ± 7.6 (kg); Size: 169.1 ± 5.3 (cm); BMI: 21.2 ± 2.0; % FM: 24.3 ± 2.7; % MM: 45.2 ± 2.9; % RM:12,0 ± 0.7; % BM: 12,9 ± 1,0. Somatotype for youth 15 years was: 2.4 ± 0.7 / 4.5 ± 0.8 / 3.0 ± 1.1 and for 16 years it was: 2.3 ± 1.0 / 4.3 ± 0, 8 / 3.0 ± 0.9. These results are similar to those observed in other sports schools in Chile and the world. It is concluded that high percentages of muscle mass and meso- ectomorphic components would be morphological characteristics in this type of athlete. It is suggested to consider these factors, in addition to considering social and psychological factors, body maturation, focusing the work of adolescents more on promoting a healthy and active lifestyle than on the competitive aspect.

Medición objetiva del comportamiento sedentario y la actividad física, y de sus efectos en la variabilidad de la frecuencia cardiaca, en adultos jóvenes que residen en una altitud moderada / Objective measurement of sedentary behavior and physical activity, and their effects on heart rate variability, in young adults that live in a moderate altitude

Resumen Antecedentes: El ejercicio físico y el entrenamiento de resistencia aeróbica se han asociado con un aumento de la variabilidad de la frecuencia cardiaca, mientras que el tiempo sedentario se ha asociado con una disminución de la variabilidad de la frecuencia cardiaca. Objetivo: Determinar si la variabilidad de la frecuencia cardiaca medida durante el reposo se relaciona con el tiempo sedentario y el tiempo utilizado en diferentes intensidades de actividad física, determinadas a través de un método objetivo (acelerometría), en un grupo de adultos sanos que residen a una altura de 2600 metros sobre el nivel del mar (m.s.n.m.). Método: Se realizaron mediciones de acelerometría a 99 individuos durante una semana y una medición de variabilidad de la frecuencia cardiaca en reposo. De acuerdo con la acelerometría, se realizó una división en tiempo sedentario y tiempo de actividad física de intensidad ligera, moderada y vigorosa. Para analizar la variabilidad de la frecuencia cardiaca se utilizaron parámetros en el dominio del tiempo (intervalos normales [NN], desviación estándar de los intervalos normales [SDNN], raíz cuadrada del promedio de las diferencias al cuadrado entre intervalos normales adyacentes [RMSSD]) y de la frecuencia (potencia de la baja frecuencia [LF], potencia de la alta frecuencia [HF], LF/HF) para analizar la variabilidad de la frecuencia cardiaca. Mediante de modelos de regresión se buscó la asociación entre las variables de actividad física y de variabilidad de la frecuencia cardiaca. Resultados: Se presentó una asociación negativa entre los intervalos NN, la SDNN y el tiempo sedentario, así como asociaciones positivas entre el intervalo NN y la actividad física ligera, moderada y vigorosa, al igual que entre la actividad física vigorosa y las potencias de LF y HF. Todas las asociaciones anteriores fueron significativas (p< 0.05). Conclusiones: En adultos jóvenes que residen a 2600 m.s.n.m., el tiempo sedentario reduce la variabilidad de la frecuencia cardiaca, mientras que la actividad física vigorosa aumenta dicha variabilidad.

Abstract Background: Physical exercise and aerobic resistance training have been associated with increased heart rate variability, while sedentary time has been associated with decreased heart rate variability. Objective: To determine if heart rate variability measured at rest is related to sedentary time and time used in various intensities of physical activity, established through an objective method (accelerometry), in a group of healthy adults who live 2,600 meters above sea level. Method: Accelerometer measurements were taken in 99 individuals during one week along with one measurement of heart rate variability at rest. Time was divided into sedentary time and time spent in light, moderate and vigorous physical activity. Time (NN interval, SDNN, RMSSD) and frequency (LF, HF, LF/HF) domain parameters were used to analyze heart rate variability. Using regression models, an association was sought between the physical activity and heart rate variability variables. Results: There was a negative association between NN intervals, SDNN and sedentary time, as well as positive associations between the NN interval and light, moderate and vigorous physical activity, and between vigorous physical activity and LF and HF power. All the foregoing associations were significant (p< 0.05). Conclusions: In young adults living 2,600 meters above sea level, sedentary time reduces heart rate variability, while vigorous physical activity increases this variability.

Stages of change in the purchase of ultra-processed snacks among university students after the implementation of the chilean food law; a multi-center study

The Objective is to determine the stages of change in the behavior of university students regarding the purchase of ultra-processed snacks consumed. Multi-center study (14 Chilean universities). The participants (4,807 students)evaluated were applied a survey to determine the stage of change of behavior regarding the purchase of foods with warning signs. The students were evaluated and classified as (a) Nutrition Students, (b) Healthcare-related Students and (c) Other degree Students. More than 90% of the students were aware of the food regulation and knew the warning signs. More than 60% of Healthcare-related and Other degree students are in the stage of pre-contemplation or contemplation regarding purchase intent of sugary drinks, juices, cookies, sweet snacks and potato chips; this value is twice the percentage of Nutrition students in this stages ( Chi2, p<0.001). In conclusion there is a high proportion of pre-contemplation and contemplation with respect to purchase intent among the students(AU)

Determinar las etapas de cambio en el comportamiento de los estudiantes universitarios con respecto a la compra de colaciones ultraprocesadas. Estudio Multicéntrico (14 universidades chilenas). A los participantes (4.807 estudiantes) se les aplicó una encuesta para determinar el cambio en el comportamiento con respecto a la compra de alimentos con sellos de advertencia. Los estudiantes se clasificaron como (a) estudiantes de nutrición, (b) estudiantes del área de la salud y (c) estudiantes de otras carreras. Se evaluaron. Más del 90% de los estudiantes conocían la regulación alimentaria y conocían las señales de advertencia. Más del 60% de los estudiantes de la salud y de otras carreras se encuentran en la etapa de pre-contemplación o contemplación con respecto a la intención de compra de bebidas azucaradas, jugos, galletas, bocadillos dulces y papas fritas; Este valor es el doble del porcentaje de estudiantes de nutrición en estas etapas ( Chi2, p <0,001). Se concluye que existe una alta proporción de pre-contemplación y contemplación con respecto a la intención de compra entre los estudiantes universitarios(AU)

Fifty years of capacity building in the search for new marine natural products.

The Convention on Biological Diversity, and the Nagoya Protocol in particular, provide a framework for the fair and equitable sharing of benefits arising from the utilization of biological resources and traditional knowledge, and ultimately aim to promote capacity-building in the developing world. However, measuring capacity-building is a challenging task due to its intangible nature. By compiling and analyzing a database of scientific peer-reviewed publications over a period of 50 y (1965 to 2015), we investigated capacity-building in global marine natural product discovery. We used publication and authorship metrics to assess how the capacity to become scientifically proficient, prolific, and independent has changed in bioprospecting countries. Our results show that marine bioprospecting is a dynamically growing field of research with continuously increasing numbers of participating countries, publications, and scientists. Yet despite longstanding efforts to promote equitability and scientific independence, not all countries have similarly increased their capacity to explore marine biodiversity within their national jurisdiction areas. Although developing countries show an increasing trend in the number of publications, a few developed countries still account for almost one-half of all publications in the field. Multiple lines of evidence suggest that economic capacity affects how well countries with species-rich marine ecosystems can scientifically explore those resources. Overall, the capacity-building data analyzed here provides a timely contribution to the ongoing international debate about access to and benefit-sharing of biological resources for countries exploring biodiversity within and outside their national jurisdiction areas.

A Multicenter Study Evaluating the Stages of Change in Food Consumption with Warning Labels among Chilean University Students.

OBJECTIVE: To analyze the stage of change in food consumption with warning labels among Chilean university students. MATERIALS AND METHODS: Cross-sectional study which applied surveys in universities from all over the country. Study included 4807 participants of 18 to 40 years of both sexes who were asked about the level of knowledge of the new food law and food consumption with warning signals, including questions regarding their willingness to behavior change according to Prochaska's transtheoretical model. To compare continuous variables, Student's t-test was used in the statistical package SPSS 22.0, and p <0.05 was considered a significant difference. RESULTS: Of the total number of respondents, 99.3% of the students indicated that they know about the food law, classifying foods with signals in the precontemplation stage. Compared by sex, we observed that women give greater importance to behavior change in all of foods (p <0.001). Underweight students give less importance to change in unhealthy foods, while obesity students give more importance but do not show more confidence in behavior change (p <0.05). CONCLUSION: The university students show a low importance and confidence to make behavior change, aspects associated with sex and nutritional status. It is necessary to strengthen nutritional food education and not just talk about structural measures.

Early life history of the Caribbean coral Orbicella faveolata (Scleractinia: Merulinidae)

Introduction: Rehabilitation of hermatypic coral species that have declined in the Caribbean in recent decades is a priority. Production of sexual recruits is considered the best restoration method to aid affected populations. Objective: To gain knowledge of early life stages of Orbicella faveolata and to enhance production of new sexual recruits. Methods: Gamete bundles from the coral species O. faveolata were collected over two years (2018 and 2019) from Los Corales del Rosario y de San Bernardo Natural National Park, Cartagena, Colombia. Assisted fertilization, larval rearing, settlement (onto crustose coralline algae, CCA) and post settlement survival in laboratory conditions were monitored. Results: Embryonic and larval development were documented over 55 hours after the first cleavage, when larvae were fully developed and started pre-settlement behavior. Settlement began 7 days after first cleavage and after 37 days polyps had acquired zooxanthellae. Larval settlement was higher on Lythophyllum congestum and Titanoderma prototypum than in response to Porolithon pachydermum, Neogoniolithon sp., Hydrolithon sp., and Lythophyllum sp. Larvae did not settle on dead coral or on the negative control (sterilized seawater). After the first week post settlement survival was 59 % amongst O. faveolata recruits. During the second week, survival dropped to 42 %, and was further reduced to 0 % at the end of the third week. Conclusions: O. faveolata larvae require cues from certain CCA species to settle, they do not settle in absence of CCA. Increased larvae availability is possible through assisted fertilization in the laboratory, however, due to the high mortality in early post-settlement phases, additional research needs to be conducted in order to scale up larvae production and improve understanding of the cues that enhance settlement and the factors which cause post-settlement mortality.

Introducción: La rehabilitación de las especies de corales hermatípicos del Caribe que han disminuido en las últimas décadas es una prioridad. La producción de reclutas sexuales se considera el mejor método de restauración para ayudar a las poblaciones afectadas. Objetivo: Obtener conocimiento de las primeras etapas de la vida de O. faveolata y mejorar la producción de nuevos reclutas sexuales. Métodos: Por dos años (2018 y 2019), seis días después de luna llena en septiembre, se recolectaron paquetes gaméticos en arrecifes del Parque Nacional Natural Los Corales del Rosario y de San Bernardo, Cartagena, Colombia. Se siguió la fertilización asistida, la cría de larvas, el asentamiento y la supervivencia posterior al asentamiento en algas coralinas costrosas (ACC) en condiciones de laboratorio. Resultados: El desarrollo de embriones y larvas se documenta a lo largo de 55 h después del primer clivaje, cuando la larva está desarrollada completamente y comenzó el comportamiento previo al asentamiento. El asentamiento comienza 7 días después del primer clivaje y 37 días después, la mayoría de los pólipos presentan zooxantelas. El asentamiento larval fue más alto en Lythophyllum congestum y Titanoderma prototypum que en respuesta a Porolithon pachydermum, Neogoniolithon sp., Hydrolithon sp., y Lythophyllum sp. No hubo asentamiento sobre coral muerto ni en el control negativo (agua de mar esterilizada). La supervivencia bajó de un 59 % en la primera semana después del asentamiento, a 42 % durante la segunda semana y 0 % para el final de la tercera semana. Conclusiones: Las larvas de O. faveolata requieren señales de ciertas especies de ACC para asentarse, ellas no se asientan en ausencia de ACC. La disponibilidad de larvas es posible mediante la fertilización asistida en laboratorio. Sin embargo, debido a la alta mortalidad en las primeras fases posteriores al asentamiento, queda mucho por hacer para aumentar la producción de larvas y mejorar nuestro conocimiento y comprensión de las señales que mejoran el asentamiento y las que previenen o inhiben la supervivencia del recluta.

An experimental test of how parasites of predators can influence trophic cascades and ecosystem functioning.

Parasites can shape the structure and function of ecosystems by influencing both the density and traits of their hosts. Such changes in ecosystems are particularly likely when the host is a predator that mediates the dynamics of trophic cascades. Here, we experimentally tested how parasite load of a small predatory fish, the threespine stickleback, can affect the occurrence and strength of trophic cascades and ecosystem functioning. In a factorial mesocosm experiment, we manipulated the density of stickleback (low vs. high), and the level of parasite load (natural vs. reduced). In addition, we used two stickleback populations from different lineages: an eastern European lineage with a more pelagic phenotype (Lake Constance) and a western European lineage with a more benthic phenotype (Lake Geneva). We found that stickleback caused trophic cascades in the pelagic but not the benthic food chain. Evidence for pelagic trophic cascades was stronger in treatments where parasite load of stickleback was reduced with an antihelmintic medication, and where fish originated from Lake Constance (i.e., the more pelagic lineage). A structural equation model revealed that differences in stickleback lineage and parasite load were most likely to impact trophic cascades via changes in the composition, rather than overall biomass, of zooplankton communities. Overall, our results provide experimental evidence that parasites of predators can influence the cascading effects of fish on lower trophic levels with consequences on ecosystem functioning.

[Photographic documentation during safe laparoscopic cholecystectomy]. / Documentación fotográfica durante la colecistectomía laparoscópica segura.

INTRODUCTION: Laparoscopic cholecystectomy is the most frequent procedure for the general surgeon. Biliary injury is a concern that must be addressed with the purpose of lowering the rate. The critical view of safety (CVS) is a target of dissection that impulses safety during the procedure. OBJECTIVE: Determine by an ambispective analysis the safety during dissection of laparoscopic cholecystectomy in Hospital Civil de Culiacán (México). METHODS: Descriptive, ambispective, observational, cross-sectional. Patients admitted to the operating room for a laparoscopic cholecystectomy were scored with Doublet photography rating criteria from January 1st 2015 to January 31, 2017. RESULTS: 321 patients were evaluated, 77.9% were female and 22.1% male. The mean age was 45.57 ± 16.17 years. 65.4% had admission diagnosis of cholelithiasis, 24.3% acute cholecystitis, 5.9% chronic cholecystitis, 3.7% hydrocolecist and 0.6% pyocolecist. Surgeries were scored with Doublet photography. The CVS was obtained in 41.4% of the procedures with a statistical significance between a HPB surgeon and a general surgery resident (p ≤ 0.05). CONCLUSION: Recording Doublet photography provides a reliable CVS dissection criterion. It can be easily reproduced during laparoscopic cholecystectomy. The identification of cystic structures adds to the culture of safety during laparoscopic cholecystectomy.

INTRODUCCIÓN: La colecistectomía laparoscópica es la cirugía realizada con más frecuencia. La tasa de lesión en la vía biliar impulsa para implementar métodos de seguridad, como la visión crítica de seguridad (VCS). OBJETIVO: Determinar la documentación fotográfica ambispectiva durante la colecistectomía laparoscópica segura en el Hospital Civil de Culiacán. MÉTODO: Estudio descriptivo, observacional, ambispectivo, transversal, de pacientes sometidos a colecistectomía laparoscópica en el Hospital Civil de Culiacán, evaluados con criterios fotográficos de Doublet para asegurar si la VCS se obtuvo de manera satisfactoria, del 1 de enero de 2015 al 31 de enero de 2017. RESULTADOS: Se analizaron 321 pacientes (77.9% del sexo femenino y 22.1% del sexo masculino), con una edad promedio de 45.57 ± 16.17 años, y diagnóstico de colelitiasis (65.4%), colecistitis aguda (24.3%), colecistitis crónica (5.9%), hidrocolecisto (3.7%) o piocolecisto (0.6%). Los cirujanos realizaron la calificación de las fotografías otorgando puntajes en la vista anterior, posterior y Doublet. Se determinó un 41.4% de VCS satisfactoria mediante análisis Doublet, con diferencia estadísticamente significativa entre las calificaciones del cirujano hepatobiliar y el médico residente (p ≤ 0.05). CONCLUSIONES: La realización de las fotografías en pacientes con registros confiables de la VCS es ideal para la colecistectomía laparoscópica, permitiendo identificar adecuadamente las estructuras císticas y evitar la lesión de vía biliar.

[Comparative analysis of diagnostic scales of acute appendicitis: Alvarado, RIPASA and AIR]. / ARTÍCULO ORIGINAL Análisis comparativo de escalas diagnósticas de apendicitis aguda: Alvarado, RIPASA y AIR.

INTRODUCTION: Acute appendicitis is the most common surgical disease in emergency surgery, however, it remains a diagnostic problem and represents a challenge despite the experience and the different clinical and paraclinical diagnostic methods. OBJECTIVE: To evaluate in a comparative way the scale of Alvarado, AIR and RIPASA to determine which one is best as a diagnostic test of acute appendicitis in our population in order to arrive to an accurate diagnosis in the shortest possible time and cost. METHOD: Observational, prospective, transversal and comparative study of 137 patients to whom the scale of Alvarado, AIR and RIPASA was applied, who entered the emergency service of the Civil Hospital of Culiacán (México) with abdominal pain syndrome suggestive of acute appendicitis. RESULTS: The Alvarado scale presented sensitivity 97.2% and specificity of 27.6%. AIR presented sensitivity of 81.9% and specificity of 89.5%. RIPASA showed the same results as Alvarado. All tests showed diagnostic accuracy above 80. CONCLUSIONS: Alvarado and RIPASA presented good sensitivity, however, AIR is more specific, and has better accuracy for the diagnosis of acute appendicitis, making a better screening and thus reducing unnecessary surgeries. Therefore, it is recommended to use more AIR than Alvarado and RIPASA.

INTRODUCCIÓN: La apendicitis aguda es la enfermedad quirúrgica más común en cirugía de urgencia; sin embargo, sigue siendo un problema diagnóstico y representa un reto a pesar de la experiencia y los diferentes métodos de diagnóstico clínicos y paraclínicos. OBJETIVO: Evaluar en forma comparativa las escalas de Alvarado, AIR y RIPASA para determinar cuál es superior como prueba diagnóstica de apendicitis aguda en nuestra población, llegando a un diagnóstico preciso en el menor tiempo y costo posibles. MÉTODO: Estudio observacional, prospectivo, transversal y comparativo de 137 pacientes a quienes se aplicó las escalas de Alvarado, AIR y RIPASA, que ingresaron al servicio de urgencias del Hospital Civil de Culiacán (México) con síndrome doloroso abdominal sugestivo de apendicitis aguda. RESULTADOS: La escala de Alvarado presentó una sensibilidad del 97.2% y una especificidad del 27.6%. AIR tuvo una sensibilidad del 81.9% y una especificidad del 89.5%. RIPASA arrojó los mismos resultados que Alvarado. Todas las pruebas tuvieron una exactitud diagnóstica por arriba del 80. CONCLUSIONES: Alvarado y RIPASA presentaron buena sensibilidad, mientras que AIR es más específica y tiene mayor exactitud diagnóstica de apendicitis aguda, realizando un mejor tamizaje y permitiendo disminuir las cirugías innecesarias, por lo que se recomienda usar más AIR que Alvarado y RIPASA.

Transgenerational selection driven by divergent ecological impacts of hybridizing lineages.

Dynamic interactions between ecological conditions and the phenotypic composition of populations likely play an important role in evolution, but the direction and strength of these feedbacks remain difficult to characterize. We investigated these dynamics across two generations of threespine sticklebacks from two evolutionary lineages undergoing secondary contact and hybridization. Independently manipulating the density and lineage of adults in experimental mesocosms led to contrasting ecosystem conditions with strong effects on total survival in a subsequent generation of juveniles. Ecosystem modifications by adults also varied the strength of selection on competing hybrid and non-hybrid juveniles. This variation in selection indicated (1) a negative eco-evolutionary feedback driven by lineage-specific resource depletion and dependence and (2) a large performance advantage of hybrid juveniles in depleted environments. This work illustrates the importance of interactions between phenotype, population density and the environment in shaping selection and evolutionary trajectories, especially in the context of range expansion with secondary contact and hybridization.

Trophic and stoichiometric consequences of nutrification for the intertidal tropical zoanthid Zoanthus sociatus.

Zoanthids are conspicuous and abundant members of intertidal environments, where they are exposed to large environmental fluctuations and subject to increasing loads of anthropogenic nutrients. Here we assess the trophic ecology and stoichiometric consequences of nutrient loading for symbiotic zoanthids inhabiting different intertidal habitats. More specifically, we analysed the stable isotope signature (δ13C and δ15N), elemental composition (C, N and P) and stoichiometry (C:N, C:P, N:P) of Zoanthus sociatus differently exposed to nutrification. Results suggest that autotrophy is the main feeding mode of zoanthids and that the effect water nutrient content differently affects the elemental phenotype of zoanthids depending on tidal habitat. Additionally, habitat effects on Z. sociatus P-related stoichiometric traits highlight functional differences likely associated with variation in Symbiodinium density. These findings provide an innovative approach to assess how cnidarian-dinoflagellate symbioses response to ecosystem changes in environmentally dynamic reef flats, particularly nutrient loading.

Experimental evidence that parasites drive eco-evolutionary feedbacks.

Host resistance to parasites is a rapidly evolving trait that can influence how hosts modify ecosystems. Eco-evolutionary feedbacks may develop if the ecosystem effects of host resistance influence selection on subsequent host generations. In a mesocosm experiment, using a recently diverged (<100 generations) pair of lake and stream three-spined sticklebacks, we tested how experimental exposure to a common fish parasite (Gyrodactylus spp.) affects interactions between hosts and their ecosystems in two environmental conditions (low and high nutrients). In both environments, we found that stream sticklebacks were more resistant to Gyrodactylus and had different gene expression profiles than lake sticklebacks. This differential infection led to contrasting effects of sticklebacks on a broad range of ecosystem properties, including zooplankton community structure and nutrient cycling. These ecosystem modifications affected the survival, body condition, and gene expression profiles of a subsequent fish generation. In particular, lake juvenile fish suffered increased mortality in ecosystems previously modified by lake adults, whereas stream fish showed decreased body condition in stream fish-modified ecosystems. Parasites reinforced selection against lake juveniles in lake fish-modified ecosystems, but only under oligotrophic conditions. Overall, our results highlight the overlapping timescales and the interplay of host-parasite and host-ecosystem interactions. We provide experimental evidence that parasites influence host-mediated effects on ecosystems and, thereby, change the likelihood and strength of eco-evolutionary feedbacks.

The association of feeding behaviour with the resistance and tolerance to parasites in recently diverged sticklebacks.

Divergent natural selection regimes can contribute to adaptive population divergence, but can be sensitive to human-mediated environmental change. Nutrient loading of aquatic ecosystems, for example, might modify selection pressures by altering the abundance and distribution of resources and the prevalence and infectivity of parasites. Here, we used a mesocosm experiment to test for interactive effects of nutrient loading and parasitism on host condition and feeding ecology. Specifically, we investigated whether the common fish parasite Gyrodactylus sp. differentially affected recently diverged lake and stream ecotypes of three-spined stickleback (Gasterosteus aculeatus). We found that the stream ecotype had a higher resistance to Gyrodactylus sp. infections than the lake ecotype, and that both ecotypes experienced a cost of parasitism, indicated by negative relationships between parasite load and both stomach fullness and body condition. Overall, our results suggest that in the early stages of adaptive population divergence of hosts, parasites can affect host resistance, body condition and diet.

Differences in the variability of cerebral proton magnetic resonance spectroscopy (1H-MRS) measurements within three HIV-infected cohorts.

INTRODUCTION: Cerebral functional impairment remains prevalent in effectively treated HIV-infected subjects. As the results of formal cognitive testing are highly variable, surrogate markers to accurately measure cerebral function parameters are needed. Such markers include measurement of cerebral metabolite ratios (CMR) using proton magnetic resonance spectroscopy (1H-MRS). However, data on the inter-subject variability of CMR are sparse. Our aim was to assess inter-subject variability in CMRs within three different HIV-infected cohorts. METHODS: Cerebral 1H-MRS was performed using a Phillips Achieva™ 1.5 Tesla magnetic resonance scanner in HIV-infected subjects as follows: 12 subjects before (group 1) and after intensification of antiretroviral therapy with maraviroc (group 2) and 13 subjects with acute viral hepatitis C (HCV) co-infection (group 3). The coefficients of variation (CV) for CMRs in each group were determined and compared using non-parametric tests to determine whether the inter-subject variability differed significantly. All baseline characteristics between the groups were similar. RESULTS: Overall CVs for all CMRs in groups 1, 2 and 3 were 32.3%, 33.2% and 23.4%, respectively (group 1 vs. 2, p=0.863; group 1 vs. 3, p=0.076). On testing for differences in variability between individual CMRs, two metabolites in the right basal ganglia (RBG) had statistically significantly different CVs when comparing group 1 with group 3: N-acetyl aspartate/creatine (NAA/Cr), p=0.029 and myo-Inositol/creatine (mI/Cr), p=0.016. CONCLUSION: The variability of 1H MRS-measurable CMRs in HIV-infected individuals was lower in those with acute HCV co-infection (group 3).We can conclude that the use of these CMRs in 1H MRS imaging in patients with HIV/acute HCV co-infection is more reliable to assess cerebral function than in patients with HIV infection alone. This has implications for future sample size estimations.

Kinship reinforces cooperative predator inspection in a cichlid fish.

Kin selection theory predicts that cooperation is facilitated between genetic relatives, as by cooperating with kin an individual might increase its inclusive fitness. Although numerous theoretical papers support Hamilton's inclusive fitness theory, experimental evidence is still underrepresented, in particular in noncooperative breeders. Cooperative predator inspection is one of the most intriguing antipredator strategies, as it implies high costs on inspectors. During an inspection event, one or more individuals leave the safety of a group and approach a potential predator to gather information about the current predation risk. We investigated the effect of genetic relatedness on cooperative predator inspection in juveniles of the cichlid fish Pelvicachromis taeniatus, a species in which juveniles live in shoals under natural conditions. We show that relatedness significantly influenced predator inspection behaviour with kin dyads being significantly more cooperative. Thus, our results indicate a higher disposition for cooperative antipredator behaviour among kin as predicted by kin selection theory.

Social deprivation affects cooperative predator inspection in a cichlid fish.

The social environment individuals are exposed to during ontogeny shapes social skills and social competence in group-living animals. Consequently, social deprivation has serious effects on behaviour and development in animals but little is known about its impact on cooperation. In this study, we examined the effect of social environment on cooperative predator inspection. Predator inspection behaviour is a complex behaviour, which is present in a variety of shoaling fish species. Often, two fish leave the safety of the group and inspect a potentially dangerous predator in order to gather information about the current predation risk. As predator inspection is highly risky, it is prone to conflicts and cheating. However, cooperation among individuals may reduce the individual predation risk. We investigated this complex social behaviour in juveniles of the cichlid fish Pelvicachromis taeniatus that were reared in two different social environments throughout development. Fish reared in a group inspected more often than isolation-reared fish and were more likely to cooperate, i.e. they conducted conjoint inspection of a predator. By contrast, isolation-reared fish were more likely to perform a single inspection without a companion. These results suggest an impairment of cooperative behaviour in isolation-reared fish most probably due to lack of social experience and resulting in lowered social skills needed in coordinated behaviour.

Patogenia, diagnóstico y tratamiento de la disfunción renal en cirrosis / Pathogenesis, Diagnosis and Treatment of Renal Dysfunction in Cirrhosis

Los pacientes con cirrosis hepática son susceptibles a presentar un deterioro de la función renal que puede ser de naturaleza funcional y/o estructural. La insuficiencia renal aguda (IRA) prerrenal representa la forma más frecuente en el 68% de los casos, e incluye un tipo especial de insuficiencia renal funcional conocida como síndrome hepatorrenal (SHR). La creatinina sérica permanece como el mejor biomarcador de IRA en cirrosis a pesar de sus reconocidas limitaciones. La diferenciación entre necrosis tubular aguda (NTA) y SHR se puede establecer con el uso de biomarcadores urinarios como la uNGAL. Los factores de riesgo de IRA en cirrosis incluyen las infecciones bacterianas, la hemorragia digestiva, las pérdidas de líquidos gastrointestinales y renales, la paracentesis sin albúmina y los agentes nefrotóxicos, entre otros. Los nuevos criterios por estadios de la AKI-IAC para el diagnóstico de IRA en cirrosis, que inician por un aumento de la creatinina sérica ≥0,3 mg/dL en menos de 48 horas, mejoran el pronóstico de los pacientes al permitir una intervención más temprana. El diagnóstico del SHR se establece al excluir las causas de azoemia prerrenal, NTA y expandir el volumen con albúmina. El uso de vasoconstrictores esplácnicos, como la terlipresina junto con la albúmina, permite revertir hasta el 40% de los casos de SHR. El trasplante hepático representa el tratamiento definitivo en pacientes con SHR.

Patients with cirrhosis of the liver are susceptible to deterioration of renal function which may be functional or structural. Prerenal acute renal failure which occurs in 68% of these cases is the most common form. It includes a special type of functional renal failure known as hepatorenal syndrome (HRS). Serum creatinine remains the best biomarker for acute renal failure in cirrhosis despite its recognized limitations. Acute tubular necrosis and HRS can be differentiated by using urinary biomarkers such as urinary neutrophil gelatinase-associated lipocalin (uNGAL). Risk factors for acute renal failure in cirrhosis include bacterial infections, gastrointestinal bleeding, loss of gastrointestinal and renal fluids, paracentesis without albumin, and nephrotoxic agents. The new criteria for staging acute kidney injury (AKI) in cirrhosis have improved patient outcomes by enabling earlier interventions by starting when serum creatinine increases above 0.3 mg/dl in less than 48 hours. The diagnosis of HRS is established by excluding causes of pre-renal azotemia, acute tubular necrosis and volume expansion with albumin. The use of splanchnic vasoconstrictors such as terlipressin together with albumin can reverse up to 40% of cases of SHR. Liver transplantation is the definitive treatment for patients with hepatorenal syndrome.