Search

Fire has been an integral part of ecosystem functioning in many biomes for a long time, but the increased intensity and frequency of wildfires often affect plant diversity and carbon storage. Prescribed burning is one of the alternatives to forest fuel management where the fire is controlled and carried out under a determined set of weather conditions and objectives. The effect of prescribed burning on plant diversity and carbon (C) storage has not been studied widely. The objective of this study was to evaluate the effect of prescribed burning on plant diversity indices, biomass stocks, and soil C storage in the tropical highland forests of Southern Mexico. We assessed plant diversity and carbon stocks at 21 sampling sites: seven with prescribed burning, seven non-burning, and seven with wildfires. We calculated tree biodiversity indices, stand structural properties, and species composition among burning treatments. We quantified C stocks in vegetation biomass by using an allometric equation and forest litter by direct sampling. We analyzed 252 soil samples for soil organic C content and other properties. The results showed that the biodiversity index was higher in sites with prescribed burning (Shannon index, H = 1.26) and non-burning (H = 1.14) than in wildfire sites (H = 0.36). There was a greater similarity in plant species composition between non-burning and prescribed burning sites compared to wildfire sites. Prescribed burning showed a positive effect on soil carbon storage (183.9 Mg C ha−1) when compared to wildfire (144.3 Mg C ha−1), but the difference was not statistically significant (p > 0.05) in biomass stocks. Prescribed burning in this study conserved plant diversity as well as soil carbon stocks compared to non-burning, the opposite of what we found in wildfires. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the corn green matter production at different sowing densities, in Valle del Mezquital, Hidalgo, Mexico. Design/Methodology/Approach: The DK-4018 hybrid corn was sown in the spring-summer 2021 cycle. The treatments (T) were different sowing densities: (T1) 112,500, (T2) 120,000, and (T3) 136,000 plants per hectare. The experimental design was completely randomized. The evaluated variables were: plant height at 30, 60, and 76 days after sowing (cm); final stem diameter at ground level (cm); fresh weight (g); and green matter yield (ton ha-1). The results were analyzed with the SAS program (2001) and the means were compared with the Tukey test (p-0.05). Results: The highest green matter production of the DK-4018 hybrid corn was obtained with a sowing density of 136,000 plants per hectare, with an estimated yield of 114.6 ton. Study Limitations/Implications: No scientific publications about the DK-4018 hybrid corn green matter production were found. Findings/Conclusions: With a population density of 136,000 corn plants per hectare, 114.6 ton of DK-4018 corn green matter yield is estimated. [ABSTRACT FROM AUTHOR]

Featured Application: The present study shows the importance of determining the climate change scenario from Representative Concentration Pathways for the study of impacts on ecosystems and social systems (ecosocial systems). In addition, the study investigates the influence of climate drivers and climate change and brings these to bear on the local and regional impacts in the study region. This study analyzes the mean, maximum, and minimum temperatures and precipitation trends in southeast Mexico-Yucatan Peninsula, Central America and the Caribbean regions. The Climate Research Unit (CRU) TS 4.01, with a spatial resolution of 0.5° × 0.5°, was the database used in this research. The trends of the four selected climate variables cover the period from 1960 to 2016. The results obtained show a clear and consistent warming trend, at a rate of about 0.01 °C/year for the entire study region. These results are consistent with some previous studies and the IPCC reports. While the trends of precipitation anomalies are slightly positive (~0.1 mm/year) for southeast Mexico-Yucatan Peninsula and almost the entire Caribbean, for Central America (CA) the trends are negative. The study also presents the correlation between temperatures and precipitation versus El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) drivers, indicating global warming and frequency signals from the climate drivers. In terms of the near future (2015–2039), three Representative Concentration Pathways (RPC) show the same trend of temperature increase as the historical record. The RCP 6.0 has trends similar to the historical records for CA and southeast Mexico-Yucatan Peninsula, while the Caribbean corresponds to RCP 4.5. In terms of the far-future (2075–2099), RCP 6.0 is more ad-hoc for southeastern Mexico-Yucatan Peninsula, and RCP 8.5 corresponds to Central America. These results could help to focus actions and measures against the impacts of climate change in the entire study region. [ABSTRACT FROM AUTHOR]

Pharmacogenetic analysis has generated translational data that could be applied to guide treatments according to individual genetic variations. However, pharmacogenetic counseling in some mestizo (admixed) populations may require tailoring to different patterns of admixture. The identification and clustering of individuals with related admixture patterns in such populations could help to refine the practice of pharmacogenetic counseling. This study identifies related groups in a highly admixed population-based sample from Mexico, and analyzes the differential distribution of actionable pharmacogenetic variants. A subsample of 1728 individuals from the Mexican Genomic Database for Addiction Research (MxGDAR/Encodat) was analyzed. Genotyping was performed with the commercial PsychArray BeadChip, genome-wide ancestry was estimated using EIGENSOFT, and model-based clustering was applied to defined admixture groups. Actionable pharmacogenetic variants were identified with a query to the Pharmacogenomics Knowledge Base (PharmGKB) database, and functional prediction using the Variant Effect Predictor (VEP). Allele frequencies were compared with chi-square tests and differentiation was estimated by FST. Seven admixture groups were identified in Mexico. Some, like Group 1, Group 4, and Group 5, were found exclusively in certain geographic areas. More than 90% of the individuals, in some groups (Group 1, Group 4 and Group 5) were found in the Central-East and Southeast region of the country. MTRR p.I49M, ABCG2 p.Q141K , CHRNA5 p.D398N, SLCO2B1 rs2851069 show a low degree of differentiation between admixture groups. ANKK1 p.G318R and p.H90R, had the lowest allele frequency of Group 1. The reduction in these alleles reduces the risk of toxicity from anticancer and antihypercholesterolemic drugs. Our analysis identified different admixture patterns and described how they could be used to refine the practice of pharmacogenetic counseling for this admixed population. [ABSTRACT FROM AUTHOR]

Objective: To determine the prevalence of Kawasaki disease in a secondary hospital. Materials and methods: A retrospective, descriptive, observational, study was conducted over a period of five years. We reviewed a total of 3,561 hospital discharges from the Department of Pediatrics and selected 15 patients diagnosed with Kawasaki disease. Results: The prevalence of Kawasaki disease was 4.2% as the diagnosis of hospital discharge. The average age was 35 months, with a predominance of male and a ratio of 2.7:1. All expressed a fever and rash. Fourteen patients (93%) had conjunctival injection, changes in lips, mouth and limbs. The less frequent clinical manifestation was the cervical lymph nodes (33%). The sedimentation rate was elevated and C-reactive protein was reported positive. Hematologic abnormalities such as anemia, thrombocytosis and fever occurred in more than 90% of patients. The initial echocardiogram showed coronary ectasia in two patients, with regression of the same in the stage of convalescence. All patients received aspirin and 10 were administered intravenous immunoglobulin. There were no complications during follow-up. Conclusions: Although the frequency of this type of vasculitis in Mexico is lower in comparison with other populations in the world, is the most common cause of acquired heart disease in our hospital, going far beyond the prevalence of rheumatic fever. [ABSTRACT FROM AUTHOR]

Ground-source heat pumps are widely used around the world because of their capacity to provide renewable and emissions-free energy for residential use. A vertical ground-source heat pump in an air conditioner mode is studied experimentally and numerically. The geothermal heat pump is located in Mexico, and consists of a single U-tube of 100 m depth, with 41.16 m3 of conditioned space. A computational fluid dynamics analysis of the geothermal heat exchanger and a thermoeconomic analysis of the heat pump are developed to evaluate the thermal performance of the system under the weather conditions of Mexico, and to know the cost allocation per equipment of the system. Results show that the geothermal heat pump provides a comfort temperature with the minimum value of a comfort relative humidity; the most important temperature changes for the geothermal heat exchanger are present during the first 10 m depth; the system decreases its performance when operating in cities with hot ambient temperatures; the irreversibilities present in the system are small, and the cost of the components depends mainly on the capital investment. In addition, the coefficient of performance of the system is of 3.3–3.6. • A vertical ground-source geothermal heat pump is studied in Mexico. • Experimental, CFD, and thermoeconomic studies are developed for the heat pump. • The most important temperature changes of the soil are present during the first 10 m. • The HP provides a comfort temperature with the minimum of a comfort relative humidity. • The system's performance decreases when operating in hot ambient temperatures. [ABSTRACT FROM AUTHOR]

Objective: Pharmacogenetic studies have identified genetic variants associated with fluoxetine response in patients with major depression disorder (MDD). The serotonin transporter gene is the principal site of action of selective serotonin reuptake inhibitors. Previous studies analyzing SLC6A4 gene variants are inconsistent and differ among populations. The aim of the present study was to analyze the association between 5-HTTLPR/rs24531 triallelic polymorphism and fluoxetine response in Mexican patients with MDD., Methods: We analyzed a sample of 150 patients with MDD. Fluoxetine response was assessed according to a reduction in the Hamilton Depression Rating Scale and Montgomery Depression Rating Scale scores of 50% or more at 8 weeks from baseline. In addition, we analyzed the genotype and allele distribution between responder and nonresponder patients in a subgroup of very severe depression patients., Results: We did not find association between fluoxetine responders and 5-HTTLPR/rs25531 variants (P = 0.0637). However, in the analysis of severe depression at baseline (Hamilton Depression Rating Scale ≥ 25), we observed a high frequency of low activity alleles (S/LG) in nonresponders patients (P = 0.0102)., Conclusions: Our findings showed an association between low activity alleles of SLC6A4 gene and fluoxetine nonresponse in patients with severe depression.

Some environmental variables determining seasonal reproduction in mammals are temperature, humidity, food availability, and photoperiod. Among these, photoperiod is considered the main regulator of primates' seasonal reproduction, thus the latitudinal distribution of primate populations is a key factor determining the appearance of seasonal reproduction. The present work presents supporting discrete seasonality in male stump-tailed macaques (Macaca arctoides). We investigated whether semen quality and testosterone covaried with Mexico City's photoperiod and relative humidity by analyzing variations in the portions that form the ejaculate: the seminal liquid, the seminal coagulum, and the copulatory plug. Five male adult stump-tailed macaques were electroejaculated once a month, obtaining three semen samples per male, from August 2011 to July 2012 (except for December 2011) (n = 165). Our results showed that stump-tailed macaque sperm counts were significantly different between the portions of the ejaculate. The seminal coagulum contained the significantly largest number of spermatozoids, followed by the copulatory plug and the seminal fluid. Photoperiod and relative humidity had major influence on the sperm count in the seminal coagulum and the testosterone concentrations. Testosterone reached its highest values around the time when days and nights lasted the same hours, decreasing when days either grew longer or became shorter. Concerning relative humidity, sperm counts in the seminal coagulum were highly variable on dry days, but decreased as the relative humidity increased. We conclude that stump-tailed macaques have a discrete seasonality, occurring in spring and fall when macaques' reproductive condition and readiness for postcopulatory intrasexual competition increase.

Schizophrenia is a heritable, complex mental disorder. We analysed the DRD3 gene as a candidate to be related to schizophrenia and clinical features in affected sib-pairs. A positive association with the -250A/Ser9 haplotype and a trend toward an association with formal thought disorder were observed. A synergic effect of DRD3 polymorphisms on schizophrenia susceptibility is suggested., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Pharmacological and neuroanatomical evidence suggest the involvement of the dopaminergic system in obsessive-compulsive disorder (OCD). Analysis of the 48-bp dopamine receptor D(4) (DRD4) gene polymorphism in a sample of 210 OCD patients and 202 healthy control subjects showed a significant association (chi(2)=27.5, df=6, p=0.0003). This difference was attributable to a lower frequency of allele 4R in OCD patients compared with the control group (chi(2)=9.33, p=0.0027). However, we did not replicate previous findings of an association between the 7R allele and OCD patients with tics. Finally, we analyzed a sub-sample of 86 OCD families. E-TDT analysis in 70 informative parents did not confirm the association observed in our case-control analysis. In conclusion, the current study cannot exclude an association between DRD4 gene and OCD in the largest sample analyzed. However, further studies will be required to confirm if the DRD4 gene is involved in the pathogenesis of this disorder.

Pharmacological studies have shown that sumatriptan, a selective ligand of the serotonin 5-HT-1Dbeta autoreceptor, modifies obsessive-compulsive disorder (OCD) symptoms. The current study analysed the G861C polymorphism of the 5-HT-1Dbeta gene in a sample of 72 trios. Genotyping data were analysed using the Family-Based Association Test (FBAT). We did not replicate the previously reported linkage disequilibrium between the G861 variant and OCD. However, a quantitative trait analysis, assessing severity of OCD symptoms and defined as YBOCS score, confirmed the finding that subjects with a preferential transmission of the G861 variant showed higher YBOCS Obsession scores compared to patients carrying the C861 allele. These preliminary findings may indicate that the 5-HT-1Dbeta receptor gene could be involved in the severity of obsession symptoms in OCD. However, it is important to perform the replication of these findings in larger sample sizes of informative families.