Secondary Succession under invasive species (Pteridium aquilinum) conditions in a seasonal dry tropical forest in southeastern Mexico.

The role of invasive species in ecosystem functioning represents one of the main challenges in ecology. Pteridium aquilinum is a successful cosmopolitan invasive species with negative effects on the ecological mechanisms that allow secondary succession. In this study, we evaluated the influence of P. aquilinumon secondary succession under different disturbances in a seasonal dry forest of the Yucatán Peninsula. We determined species richness, composition and the relative importance value in four sampling units. Fabaceae followed by Asteraceae, Meliaceae, Rubiaceae, Sapindaceae and Verbenaceae were the most species rich families. A dissimilarity analysis determined significant differences in beta diversity between sampling units. With a generalized linear model we found that species richness was best explained by site conditions, followed by calcium and soil organic matter. Also, the generalized linear model showed that abundance resulted in a strong correlation with site conditions and soil characteristics. Specific soil conditions related to phosphoro and calcium were also detected as beneficiary to the successional processes. Our results suggest that applying fire restriction and periodic cutting of the bracken fern, this can increase a higher diversity of species.

ß-Diversity of functional groups of woody plants in a tropical dry forest in Yucatan.

Two main theories have attempted to explain variation in plant species composition (ß-diversity). Niche theory proposes that most of the variation is related to environment (environmental filtering), whereas neutral theory posits that dispersal limitation is the main driver of ß-diversity. In this study, we first explored how α- and ß-diversity of plant functional groups defined by growth form (trees, shrubs and lianas, which represent different strategies of resource partitioning), and dispersal syndrome (autochory, anemochory and zoochory, which represent differences in dispersal limitation) vary with successional age and topographic position in a tropical dry forest. Second, we examined the effects of environmental, spatial, and spatially-structured environmental factors on ß-diversity of functional groups; we used the spatial structure of sampling sites as a proxy for dispersal limitation, and elevation, soil properties and forest stand age as indicators of environmental filtering. We recorded 200 species and 22,245 individuals in 276 plots; 120 species were trees, 41 shrubs and 39 lianas. We found that ß-diversity was highest for shrubs, intermediate for lianas and lowest for trees, and was slightly higher for zoochorous than for autochorous and anemochorous species. All three dispersal syndromes, trees and shrubs varied in composition among vegetation classes (successional age and topographic position), whilst lianas did not. ß-diversity was influenced mostly by proxies of environmental filtering, except for shrubs, for which the influence of dispersal limitation was more important. Stand age and topography significantly influenced α-diversity across functional groups, but showed a low influence on ß-diversity -possibly due to the counterbalancing effect of resprouting on plant distribution and composition. Our results show that considering different plant functional groups reveals important differences in both α- and ß-diversity patterns and correlates that are not apparent when focusing on overall woody plant diversity, and that have important implications for ecological theory and biodiversity conservation.

Effect of an enteral diet enriched with eicosapentaenoic acid, gamma-linolenic acid and anti-oxidants on the outcome of mechanically ventilated, critically ill, septic patients.

BACKGROUND & AIMS: To assess the effect of an enteral diet enriched with eicosapentaenoic acid (EPA), gamma-linolenic acid (GLA), and anti-oxidants on the incidence of organ dysfunction and nosocomial infections in septic patients with acute lung injury or acute respiratory distress syndrome (ARDS) compared with a standard enteral diet. METHODS: This prospective, randomized, open-label study was performed in 11 Spanish intensive care units (ICU). Adult patients with sepsis and acute lung injury or ARDS were randomly allocated to receive either an EPA-GLA diet or a control diet. RESULTS: Of the 198 patients that were eligible, 160 were randomized and 132 were studied. Patient demographics, APACHE II and SOFA scores, and nutritional variables on admission were similar between the EPA-GLA diet and control diet groups. The EPA-GLA diet group showed a trend toward a decreased SOFA score, but it was not significant. No differences were observed in the PaO(2)/FiO(2) ratio or the days on mechanical ventilation between the groups. Incidence of infections was similar in the groups. The control group stayed longer in the ICU than the EPA-GLA diet group (16 vs. 18; p = 0.02). CONCLUSIONS: A diet enriched with EPA, GLA, and anti-oxidants does not improve gas exchange or decrease the incidence of novel organ failures in critically ill septic patients with acute lung injury or ARDS. Patients treated with the EPA-GLA diet stayed in the ICU for less time, but we did not find any differences in infectious complications.

Family perception of the process of organ donation. Qualitative psychosocial analysis of the subjective interpretation of donor and nondonor families.

Family perception of organ donation has been explored by numerous authors using statements by the people who decided whether or not to donate the organs of a relative in a situation of brain death. Within this tradition, in this work, we analyze the discourse of six families who granted permission for organ donation and three who refused. We describe the process-based interpretation of this experience and identify psychosocial variables and processes that further our understanding of the decision finally adopted. We have identified two heuristics that guide family decision when organ donation is requested: the explicit or inferred will of the deceased and family attitudes to organ donation and transplant. It is postulated that the interaction of these two factors explains a large amount of the decisions made. We also hypothesize that a marked discrepancy between these two factors increases the importance of other aspects, especially the role of the transplant coordinator and of other healthcare personnel. These results support, at a social level, the implementation of transplant promotion programs; and at a healthcare level, the combined use of techniques of crisis intervention and attitude change.

Family Perception of the Process of Organ Donation. Qualitative Psychosocial Analysis of the Subjective Interpretation of Donor and Nondonor Families

Family perception of organ donation has been explored by numerous authors using statements by the people who decided whether or not to donate the organs of a relative in a situation of brain death. Within this tradition, in this work, we analyze the discourse of six families who granted permission for organ donation and three who refused. We describe the process-based interpretation of this experience and identify psychosocial variables and processes that further our understanding of the decision finally adopted. We have identified two heuristics that guide family decision when organ donation is requested: the explicit or inferred will of the deceased and family attitudes to organ donation and transplant. It is postulated that the interaction of these two factors explains a large amount of the decisions made. We also hypothesize that a marked discrepancy between these two factors increases the importance of other aspects, especially the role of the transplant coordinator and of other healthcare personnel. These results support, at a social level, the implementation of transplant promotion programs; and at a healthcare level, the combined use of techniques of crisis intervention and attitude change (AU)

El estudio de la percepción familiar sobre donación de órganos ha sido abordado por numerosos autores partiendo de declaraciones de personas que habían decidido si donaban los órganos de un familiar en situación de muerte cerebral. Inserto en esta tradición, este trabajo analiza cualitativamente el discurso de seis familias que concedieron la donación de órganos y de tres que la denegaron. Describe la interpretación procesal de esta experiencia e identifica variables y procesos psicosociales que permitan comprender la decisión adoptada. Se identifican dos heurísticos que orientan la decisión familiar ante la petición de donación de órganos: la voluntad manifestada o inferida del fallecido y las actitudes familiares hacia la donación y el trasplante de órganos de los decisores; se postula que la interacción de ambos explica una parte significativa de las decisiones adoptadas. También se hipotetiza que una fuerte discrepancia entre estos dos procesos favorece que otros factores (especialmente la actuación del coordinador de trasplantes y del personal sanitario) adquieran mayor importancia en la decisión familiar. Los resultados apoyan, a nivel social, la aplicación de programas de promoción del trasplante y, a nivel hospitalario, la aplicación de intervenciones que integren técnicas de intervención en crisis y de persuasión y cambio de actitudes (AU)

La Teoría de la Identidad Social: una síntesis crítica de sus fundamentos, evidencias y controversias / Social Identity Theory: A critical synthesis of its bases, evidence and controversies

La Teoría de la Identidad Social (TIS) y la Teoría de la Auto-Categorización del Yo han tenido gran influencia en la Psicología Social contemporánea, proporcionando reseñables contribuciones a la comprensión de la dimensión social de la conducta. En este trabajo se sintetizan los fundamentos de dichas teorías y se revisan críticamente los elementos más controvertidos de la TIS, examinando sus límites y potencialidades. Se muestra que la literatura ofrece un panorama heterogéneo que reúne, junto a notables esfuerzos de síntesis e integración, numerosos trabajos fragmentarios e interpretaciones descontextualizadas que han generado visiones distorsionadas del comportamiento grupal. Tomando en consideración el carácter multidimensional, contextualmente mediado, dinámico y funcional de los procesos identitarios, patente ya en los trabajos más cualificados, se hace necesario revisar las herramientas epistemológicas y metodológicas al uso dentro del área y evolucionar hacia prácticas que permitan estudiar los fenómenos grupales en modo más acorde a su complejidad (AU)

The social identity theory (SIT) and the self-categorization theory have had considerable influence on contemporary Social Psychology, making notable contributions to our understanding of the social dimension of behaviour. In the present work, we summarise the bases of these theories and critically review the most controversial elements of SIT, exploring its limits and potential. As shown here, the literature offers a heterogeneous body of research that includes outstanding efforts of synthesis and integration, but also numerous fragmentary studies and decontextualized interpretations that have generated distorted views of group behaviour. Taking into account the multidimensional, contextually mediated, dynamic and functional nature of identitary processes, which clearly emerge in the most serious works in the field, there is obviously a need to review the epistemological and methodological tools currently employed, with a view to developing practices that allow the study of group phenomena in a manner more suited to their complexity (AU)

[Social Identity Theory: a critical synthesis of its bases, evidence and controversies]. / La Teoría de la Identidad Social: una síntesis crítica de sus fundamentos, evidencias y controversias.

The social identity theory (SIT) and the self-categorization theory have had considerable influence on contemporary Social Psychology, making notable contributions to our understanding of the social dimension of behaviour. In the present work, we summarise the bases of these theories and critically review the most controversial elements of SIT, exploring its limits and potential. As shown here, the literature offers a heterogeneous body of research that includes outstanding efforts of synthesis and integration, but also numerous fragmentary studies and decontextualized interpretations that have generated distorted views of group behaviour. Taking into account the multidimensional, contextually mediated, dynamic and functional nature of identitary processes, which clearly emerge in the most serious works in the field, there is obviously a need to review the epistemological and methodological tools currently employed, with a view to developing practices that allow the study of group phenomena in a manner more suited to their complexity.

Clinical evidence for enteral nutritional support with glutamine: a systematic review.

OBJECTIVE: The purpose of this systematic review was to locate and assess the quality of scientific evidence to establish a graded recommendation based on the effectiveness of glutamine-enriched enteral nutrition in different medical and surgical conditions. We were concerned with the following topics: 1) benefits of enteral administration of glutamine in different pathologic conditions, and 2) dose, duration, and time of initiation of glutamine-enriched diets. METHODS: The sources consulted for the search were MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Healthstar and HSTAT. Ninety-one studies were assessed; after a methodologic review (primary review), only 16 studies met the inclusion criteria for analysis by a group of experts (secondary review). The coordinators supervised all data, and a final consensus was reached among the coordinators, experts, and methodologists. RESULTS AND CONCLUSIONS: Glutamine-enriched diets showed good overall tolerance, improvement of immunologic aspects in multiple trauma patients, cost reduction in critically ill patients, and improvement of mucositis in post-chemotherapy patients (grade B recommendations). The doses given and the duration of therapy varied widely depending on the pathologic condition. Intake of 20 to 30 g/d, early initiation of diet, and maintenance for 5 d or longer are recommended (grade C recommendations).

Immunonutrition in the intensive care unit. A systematic review and consensus statement.

OBJECTIVE: To systematically review the effects of enteral nutrition with pharmaconutrients-enriched diets in critically ill patients and to establish recommendations for their use. DATA SOURCES: Computerized bibliographic search of published research and citation review of relevant articles. STUDY SELECTION: Randomized clinical trials of critically ill patients treated with enteral nutrition comparing diets enriched with pharmaconutrients vs not enriched diets were included. Infectious complications and outcome variables (days on mechanical ventilation, ICU and hospital length of stay and mortality) were evaluated. Studies were classified in four subgroups according to the patient's primary diagnosis: surgical, trauma, burned or medical. DATA EXTRACTION: A group of experts in methodology performed data extraction and statistical processes. A global analysis of the studies was done and also a separate study for each subgroup. Results of the meta-analysis were discussed within a 'clinical group' of clinicians with experience in the nutritional support of ICU patients, in order to find agreement about recommendations for the use of pharmaconutrients-enriched diets in critically ill patients. RESULTS: Independent review of 267 articles identified 26 relevant primary studies. Global results indicate that there was a reduction in infection rate in the pharmaconutrition group, considering the appreciated lower incidence in abdominal abscesses (OR: 0.26, CI: 0.12-0.55) (P=0.005), nosocomial pneumonia (OR: 0.54, CI: 0.35-0.84) (P=0.007) and bacteremia (OR: 0.45, CI: 0.35-0.84) (P=0.0002). Also, patients treated with pharmaconutrition diets have a reduction in time on mechanical ventilation (mean 2.25 days, CI: 0.5-3.9) (P=0.009), ICU length of stay (mean reduction of 1.6 days, CI: 1.9-1.2) (P<0.0001) and hospital length of stay (mean reduction of 3.4 days, CI: 4.0-2.7) (P<0.0001). No effects were appreciated on mortality (OR: 1.10, CI: 0.85-1.42) (P=0.5). Nevertheless, the separate analysis for each subgroup showed that the reported beneficial effects were not the same for each patient population. Also, the clinician panel of experts identifies several problems in the published data about enteral pharmaconutrition in critically ill patients. In spite of the subgroup differences and of the problems detected, the clinician group considered that the appreciated results could support a Grade B recommendation for the use of these formulas in ICU patients. CONCLUSIONS: Considering the beneficial effects and the absence of detrimental ones, the use of diets enriched with pharmaconutrients could be recommended in ICU patients requiring enteral feeding. Nevertheless, more investigation is needed in this field in order to find the more appropriate population of patients that can benefit from this nutritional therapy.

Safety and metabolic tolerance of a concentrated long-chain triglyceride lipid emulsion in critically ill septic and trauma patients.

BACKGROUND: A concentrated fat emulsion (Intralipid 30%) with a phospholipid/triglyceride ratio of 0.04 was tested for clinical tolerance and metabolic effects in the short-term parenteral nutrition of septic and trauma critically ill patients and compared with Intralipid 20% (phospholipid/triglyceride ratio of 0.06). METHODS: This was a prospective, randomized, multicenter study in the intensive care units in 10 university hospitals, including 90 adult patients in 2 groups: 55 septic and 35 trauma patients. Patients in each group were randomly divided into 2 subgroups according to the fat emulsions administered (1.4 g/kg per day) as part of the calories for at least 6 days of continuous total parenteral nutrition (TPN). One subgroup was treated with 30% long-chain triglycerides (phospholipid/ triglyceride ratio: 0.04) and the other with 20% long-chain triglycerides (phospholipid/triglyceride ratio: 0.06). The parenteral nutrition formula was isocaloric and isonitrogenous with 0.25 g of nitrogen/kg per day and 40% of the nonprotein calories as fat. Clinical tolerance was assessed during the study. At baseline and after 3 and 6 days of TPN, the following biochemical parameters were measured: prealbumin, retinol-binding protein, serum albumin, hematologic, hepatic and renal function variables, triglycerides, phospholipids, total and free cholesterol, nonesterified cholesterol, nonesterified fatty acids, and lipoproteins. RESULTS: At baseline, no differences in age, gender, severity of the condition [Acute Physiology and Chronic Health Evaluation (APACHE II) score], or clinical chemistry were found between the subgroups. The levels of plasma proteins studied and the renal, hematologic, or hepatic function variables did not vary during the study period. Total cholesterol increased significantly, owing to esterified cholesterol, with 20% long-chain triglyceride in septic patients (baseline: 2.1 +/- 0.8 mmol/L, day 6: 2.8 +/- 0.6 mmol/L, p = .026). In septic patients receiving 20% long-chain triglycerides, plasma triglycerides had a similar behavior (baseline: 1.4 +/- 0.6 mmol/L, day 3: 2.2 +/- 0.8 mmol/L, p < .05). The very-low-density lipoprotein content of cholesterol, triglycerides, and phospholipids showed a tendency to decrease in septic patients treated with 30% long-chain triglycerides (NS). None of the emulsions induced the synthesis of lipoprotein X. CONCLUSIONS: Our results indicate that while both fat emulsions used in the TPN of critically ill patients are clinically safe, the 30% long-chain triglyceride fat emulsion with a phospholipid/triglyceride ratio of 0.04 causes fewer lipid metabolic disturbances.

Multicenter, prospective, randomized, single-blind study comparing the efficacy and gastrointestinal complications of early jejunal feeding with early gastric feeding in critically ill patients.

OBJECTIVE: To compare the incidence of enteral nutrition-related gastrointestinal complications, the efficacy of diet administration, and the incidence of nosocomial pneumonia in patients fed in the stomach or in the jejunum. DESIGN: Prospective, randomized multicenter study. SETTING: Intensive care units (ICUs) in 11 teaching hospitals. PATIENTS: Critically ill patients who could receive early enteral nutrition more than 5 days. INTERVENTIONS: Enteral nutrition was started in the first 36 hrs after admission. One group was fed with a nasogastric tube (GEN group) and the other in the jejunum through a dual-lumen nasogastrojejunal tube (JEN group). MEASUREMENTS AND MAIN RESULTS: Gastrointestinal complications were previously defined. The efficacy of diet administration was calculated using the volume ratio (expressed as the ratio between administered and prescribed volumes). Nosocomial pneumonia was defined according the Centers for Disease Control and Prevention's definitions. One hundred ten patients were included (GEN: 51, JEN: 50). Both groups were comparable in age, gender, Acute Physiology and Chronic Health Evaluation II, and Multiple Organ Dysfunction Score. There were no differences in feeding duration, ICU length of stay, or mortality (43% vs. 38%). The JEN group had lesser gastrointestinal complications (57% vs. 24%, p <.001), mainly because of a lesser incidence of increased gastric residuals (49% vs. 2%, p <.001). Volume ratio was similar in both groups. A post hoc analysis showed that the JEN group had a higher volume ratio at day 7 than the GEN group (68% vs. 82%, p <.03) in patients from ICUs with previous experience in jejunal feeding. Both groups had a similar incidence of nosocomial pneumonia (40% vs. 32%). CONCLUSIONS: Gastrointestinal complications are less frequent in ICU patients fed in the jejunum. Nevertheless, it seems to be a necessary learning curve to achieve better results with a postpyloric access. Early enteral nutrition using a nasojejunal route seems not to be an efficacious measure to decrease nosocomial pneumonia in critically ill patients.