Unraveling the factors that determine variation of diversity in tropical mountain systems is a topic for debate in plant ecology. This is especially true in areas where topography is complex due to ...volcano elevational gradients and where forests are vulnerable to human activity. In this study we used a set of climatic (temperature, rainfall, and radiation solar), topographic (elevation, slope aspect, and slope orientation) and human disturbance variables to determine their effect on diversity and composition patterns of a tree community, considering three slope aspects of a tropical volcano in southeastern Mexico. We sampled trees in seventy 0.1-ha plots distributed on three slope aspects of the Tacaná volcano along an elevational gradient of 1500 to 2500 m. We determined diversity patterns (general tree richness, exponential of Shannon index, and pioneer species richness) with linear regression models, and for beta diversity, we used a dissimilarity index (within and between elevational bands 100 m wide). The effect of a set of environmental and human disturbance variables on tree diversity and community composition was analyzed with general linear models and multivariate analyses, respectively. We registered 2,949 individual trees belonging to 176 species and 58 families. The average species richness and alpha diversity per plot were 13 (standard deviation ±6) and 9 (±5), respectively. General tree richness and alpha diversity increased in the middle part (unimodal patterns) of the elevational gradient, but pioneer species richness decreased linearly with elevation. The variance explained by general linear models was greater in richness (32%) than in alpha diversity (25.3%). The most important predictor variables were temperature (elevational gradient), which explained the unimodal pattern (richness and alpha diversity increase at intermediate levels of temperature), and slope orientation, which explained the increase in richness and alpha diversity toward the geographic north. Only temperature had a significant effect on pioneer species diversity (22%). For community composition, all the predictor variables evaluated had a significant effect, but the most important were slope aspect and temperature. Assemblages were almost completely different in plots that were farther apart along the elevation gradient and had different slope aspects. Finally, the forests at lower elevations (1500–1900 m) were those that had the most human disturbance. Our study reveals the importance of considering a set of environmental variables related to climate, topography (e.g., slope aspect), and human disturbance to understand variation in diversity and composition of a tree community on a tropical volcano. With this information, we believe that it is important to implement conservation and restoration measures in the forests of the lower parts of the Tacaná volcano, complemented by studies that contribute to designing better conservation strategies.
La migración venezolana a Colombia ha movilizado alrededor de 1,8 millones de venezolanos y colombianos retornados a Colombia. Mediante un panel de datos, empleando efectos fijos, estimamos la ...diferencia del aporte a la productividad de la población migrante con la no migrante para dos periodos, 2013-2019 y 2015-2019, considerando nivel educativo, departamento y sector. Durante 2015-2019 la población migrante con nivel educativo alto tendría mayores contribuciones a la productividad que la población no migrante con nivel educativo bajo. Existe un sesgo de autoselección dado que los migrantes buscaron ocuparse en departamentos con mayor productividad. Este sesgo se corrige con una variable instrumental que explota la variación regional de las redes de migrantes existentes en 2005 y el momento e intensidad de la crisis económica venezolana. Este análisis evidencia que la migración venezolana afecta positivamente la productividad laboral colombiana a corto plazo y sirve como insumo para estructurar políticas migratorias.
La migración venezolana a Colombia ha movilizado alrededor de 1,8 millones de venezolanos y colombianos retornados a Colombia. Mediante un panel de datos, empleando efectos fijos, estimamos la ...diferencia del aporte a la productividad de la población migrante con la no migrante para dos periodos, 2013-2019 y 2015-2019, considerando nivel educativo, departamento y sector. Durante 2015-2019 la población migrante con nivel educativo alto tendría mayores contribuciones a la productividad que la población no migrante con nivel educativo bajo. Existe un sesgo de autoselección dado que los migrantes buscaron ocuparse en departamentos con mayor productividad. Este sesgo se corrige con una variable instrumental que explota la variación regional de las redes de migrantes existentes en 2005 y el momento e intensidad de la crisis económica venezolana. Este análisis evidencia que la migración venezolana afecta positivamente la productividad laboral colombiana a corto plazo y sirve como insumo para estructurar políticas migratorias.
3,4-Dihydroxyphenyl ethanol, known as hydroxytyrosol (HTy), is a phenylpropanoid found in diverse vegetable species. Several studies have demonstrated that HTy is a potent antioxidant. Thus, our ...study is aimed to evaluate the antioxidant effect of HTy and its derivatives, hydroxytyrosol acetate (HTyA) and nitrohydroxytyrosol (HTyN), in a model of oxidative stress induced by 1-methyl-4-phenylpyridinium (MPP
+
) in rats. Rats were administered intravenously (i.v.) in the tail with 1 mL saline solution or polyphenol compound (1.5 mg/kg) 5 min before intrastriatal infusion of 10 µg MPP
+
/8 µL. We found that rats injured with MPP
+
, pretreatment with HTy, HTyA or HTyN significantly decreased ipsilateral turns. This result was consistent with a significant preservation of striatal dopamine levels and decreased lipid fluorescence products (LFP), a marker of oxidative stress. Brain GSH/GSSG ratio, from rats pretreated with HTy or HTyN showed a significant preservation of that marker, decreased as a consequence of MPP
+
-induced oxidative damage. These results show an antioxidant effect of HTy, HTyA and HTyN in the MPP
+
model of Parkinson’s disease in the rat.
The study of human-nature relationship has made possible to understand the life dynamics of the communities and the biodiversity with which they cohabit. Although there has been a rise of ...ethnobiological studies over the last decade, little is known about human interaction with herpetofauna in South America and Colombia. In this work, we analyzed the knowledge, perception, and interaction of a local community located in the forest reserve of Quininí (RFPCQ) in Cundinamarca (Colombia), concerning to the herpetofauna that inhabits the area.
We performed semi-structured surveys containing 30 questions categorized into three groups: academic knowledge (1), use and cultural beliefs (2), and interactions (3) related to the herpetofauna that occurs in the region. The obtained data in question groups 1 and 2 are presented as a qualitative summary. For the question group 3, we assigned the answers to a hostility value according to the possible reaction of each individual interviewed in a hypothetical encounter with the herpetofauna and built tendency charts in order to see the positive or negative reactions due to the birthplace (urban/rural) and gender (male/female).
The community recognized the presence of amphibians and reptiles that cohabit their space, as well as their potential habitats. Besides, the role of herpetofauna was recognized in the magical/religious traditions for some inhabitants of the region, mainly associated with the fate and cure of chronic diseases. In general, the perception of amphibians and reptiles varied according to the origin and gender of the people, which tend to have a more positive perception of reptiles than compared to amphibians in most cases.
Although there was a general lack of knowledge on the part of the inhabitants of the RFPCQ about the biological and ecological aspects of herpetofauna, the population recognized the basic information about the habitats of these animals within the reserve area. There is a wide variety of uses of amphibians and reptiles in traditional medicine. Greater efforts should be made in the transmission and dissemination of knowledge about the ecological functions of herpetofauna.
Rationale
Dyskinesias induced by L-3,4-dihydroxyphenylalanine, L-Dopa (LIDs), are the major complication in the pharmacological treatment of Parkinson’s disease. LIDs induce overactivity of the ...glutamatergic cortico-striatal projections, and drugs that reduce glutamatergic overactivity exert antidyskinetic actions. Chronic administration of immepip, agonist at histamine H
3
receptors (H
3
R), reduces LIDs and diminishes GABA and glutamate content in striatal dialysates (Avila-Luna et al., Psychopharmacology 236: 1937-1948, 2019).
Objectives and methods
In rats unilaterally lesioned with 6-hydroxydopamine in the substantia nigra
pars compacta
(SNc), we examined whether the chronic administration of immepip and their withdrawal modify LIDs, the effect of L-Dopa on glutamate and GABA content, and mRNA levels of dopamine D
1
receptors (D
1
Rs) and H
3
Rs in the cerebral cortex and striatum.
Results
The administration of L-Dopa for 21 days induced LIDs. This effect was accompanied by increased GABA and glutamate levels in the cerebral cortex ipsi and contralateral to the lesioned SNc, and immepip administration prevented (GABA) or reduced (glutamate) these actions. In the striatum, GABA content increased in the ipsilateral nucleus, an effect prevented by immepip. L-Dopa administration had no significant effects on striatal glutamate levels. In lesioned and L-Dopa-treated animals, D
1
R mRNA decreased in the ipsilateral striatum, an effect prevented by immepip administration.
Conclusions
Our results indicate that chronic H
3
R activation reduces LIDs and the overactivity of glutamatergic cortico-striatal projections, providing further evidence for an interaction between D
1
Rs and H
3
Rs in the cortex and striatum under normal and pathological conditions.
Abstract Objectives Provide evidence based guidelines for tracheostomy in critically ill adult patients and identify areas needing further research. Methods A task force composed of representatives ...of 10 member countries of the Pan-American and Iberic Federation of Societies of Critical and Intensive Therapy Medicine and of the Latin American Critical Care Trial Investigators Network developed recommendations based on the Grading of Recommendations Assessment, Development and Evaluation system. Results The group identified 23 relevant questions among 87 issues that were initially identified. In the initial search, 333 relevant publications were identified of which 226 publications were chosen. The task force generated a total of 19 recommendations, 10 positive (1B = 3, 2C = 3, 2D = 4) and 9 negative (1B = 8, 2C = 1). A recommendation was not possible in 6 questions. Conclusions Percutaneous techniques are associated with a lower risk of infections compared to surgical tracheostomy. Early tracheostomy only seems to reduce the duration of ventilator use but not the incidence of pneumonia, the length of stay, or the long-term mortality rate. The evidence does not support the use of routine bronchoscopy guidance or laryngeal masks during the procedure. Finally, proper prior training is as important or even a more significant factor in reducing complications than the technique used.
Quinolinic acid (QUIN), a neuroactive metabolite of the kynurenine pathway, is normally presented in nanomolar concentrations in human brain and cerebrospinal fluid (CSF) and is often implicated in ...the pathogenesis of a variety of human neurological diseases. QUIN is an agonist of N-methyl-D-aspartate (NMDA) receptor, and it has a high in vivo potency as an excitotoxin. In fact, although QUIN has an uptake system, its neuronal degradation enzyme is rapidly saturated, and the rest of extracellular QUIN can continue stimulating the NMDA receptor. However, its toxicity cannot be fully explained by its activation of NMDA receptors it is likely that additional mechanisms may also be involved. In this review we describe some of the most relevant targets of QUIN neurotoxicity which involves presynaptic receptors, energetic dysfunction, oxidative stress, transcription factors, cytoskeletal disruption, behavior alterations, and cell death.
Rationale Dyskinesias induced by L-3,4-dihydroxyphenylalanine, L-Dopa (LIDs), are the major complication in the pharmacological treatment of Parkinson's disease. LIDs induce overactivity of the ...glutamatergic cortico-striatal projections, and drugs that reduce glutamatergic overactivity exert antidyskinetic actions. Chronic administration of immepip, agonist at histamine H.sub.3 receptors (H.sub.3R), reduces LIDs and diminishes GABA and glutamate content in striatal dialysates (Avila-Luna et al., Psychopharmacology 236: 1937-1948, 2019). Objectives and methods In rats unilaterally lesioned with 6-hydroxydopamine in the substantia nigra pars compacta (SNc), we examined whether the chronic administration of immepip and their withdrawal modify LIDs, the effect of L-Dopa on glutamate and GABA content, and mRNA levels of dopamine D.sub.1 receptors (D.sub.1Rs) and H.sub.3Rs in the cerebral cortex and striatum. Results The administration of L-Dopa for 21 days induced LIDs. This effect was accompanied by increased GABA and glutamate levels in the cerebral cortex ipsi and contralateral to the lesioned SNc, and immepip administration prevented (GABA) or reduced (glutamate) these actions. In the striatum, GABA content increased in the ipsilateral nucleus, an effect prevented by immepip. L-Dopa administration had no significant effects on striatal glutamate levels. In lesioned and L-Dopa-treated animals, D.sub.1R mRNA decreased in the ipsilateral striatum, an effect prevented by immepip administration. Conclusions Our results indicate that chronic H.sub.3R activation reduces LIDs and the overactivity of glutamatergic cortico-striatal projections, providing further evidence for an interaction between D.sub.1Rs and H.sub.3Rs in the cortex and striatum under normal and pathological conditions.
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