Within-individual variation of trunk and branch xylem density in tropical trees

Premise of the study: Wood density correlates with mechanical and physiological strategies of trees and is important for estimating global carbon stocks. Nonetheless, the relationship between branch and trunk xylem density has been poorly explored in neotropical trees. Here, we examine this relationship in trees from French Guiana and its variation among different families and sites, to improve the understanding of wood density in neotropical forests. Methods: Trunk and branch xylem densities were measured for 1909 trees in seven sites across French Guiana. A major-axis fit was performed to explore their general allometric relationship and its variation among different families and sites. Key results: Trunk xylem and branch xylem densities were significantly positively correlated, and their relationship explained 47% of the total variance. Trunk xylem was on average 9% denser than branch xylem. Family-level differences and interactions between family and site accounted for more than 40% of the total variance, whereas differences among sites explained little variation. Conclusions: Variation in xylem density within individual trees can be substantial, and the relationship between branch xylem and trunk xylem densities varies considerably among families and sites. As such, whole-tree biomass estimates based on non- destructive branch sampling should correct for both taxonomic and environmental factors. Furthermore, detailed estimates of the vertical distribution of wood density within individual trees are needed to determine the extent to which relying solely upon measures of trunk wood density may cause carbon stocks in tropical forests to be overestimated

Prevalence of rheumatic disease in a cohort of patients with human immunodeficiency virus infection

Objetivo: Describir la prevalencia de enfermedades reumáticas en una cohorte de pacientes con infección por VIH y sus características demográficas y clínicas. Pacientes y métodos: Estudio descriptivo de corte transversal de una cohorte de 1.712 pacientes con infección por VIH, en un hospital universitario, seguidos desde enero del 2005 hasta septiembre del 2013. Resultados: Se encontró una prevalencia de enfermedades reumáticas del 5,2% (n= 89 casos), el 24% de sexo femenino y el 76% de sexo masculino. Edad promedio ± desviación estándar 45 ± 11 anos. ˜ Las enfermedades encontradas fueron: artritis reactiva 15% (n= 14), artrosis 15% (n= 14), púrpura trombocitopénica inmune 11% (n= 10), otras 59% (n= 53). El tiempo promedio entre el diagnóstico de VIH y la condición reumática fue de 73 ± 66 meses. Dentro de las comorbilidades se encontraron: dislipidemia 39% (n= 43), hepatitis B 17% (n= 19), lipodistrofia 11% (n= 12), herpes zóster 10% (n= 11) e hipotiroidismo 9% (n= 10). Conclusiones: Se presenta información respecto a las comorbilidades reumáticas en una cohorte de pacientes con infección por VIH. Como se ha documentado en otras series, la artritis reactiva fue la enfermedad reumática más frecuente junto con osteoartrosis. Nuestro estudio evidencia una tendencia hacia el envejecimiento de los pacientes con VIH gracias a un mejor control de la enfermedad, con el uso de terapia antirretroviral, lo cual aumenta la prevalencia de osteoartrosis. © 2014 Asociación Colombiana de Reumatología. Publicado por Elsevier España, S.L.U. Todos los derechos reservados.Artículo original79-83Objective: To describe the prevalence of rheumatic diseases in a cohort of patients with HIV infection attending a university hospital, along with their demographic and clinicalfeatures. Patients and methods: Cross-sectional study of 1712 outpatients with HIV infection treated at a university hospital between January 2005 and September 2013. Results: There was a prevalence of rheumatic diseases of 5.2% (n=89) in the patients studies, with 76% being male patients. The mean age of onset was 45 ± 11 years. Fourteen patients had reactive arthritis (15%), 14 had osteoarthritis (15%), 10 had immune thrombocytopenic purpura (11%), and 53 had other conditions (59%). The mean time between HIV diagnosis and rheumatic condition onset was 73 ± 66 months. The most prevalent comorbidities were dyslipidemia in 12 patients (11%), hepatitis B in 19 (17%), lipodystrophy in 12 (11%), herpes zoster in 11 (10%) and hypothyroidism in 10 (9%). Conclusions: A description is presented on the rheumatic diseases found in a cohort of patients with HIV infection. As reported in previous series, reactive arthritis is the most frequent rheumatic condition along with osteoarthritis. This study shows a trend towards successful aging of HIV patients due to a better control of the disease with the use of antiretroviral therapy, but with an increasing prevalence of osteoarthritis. © 2014 Asociación Colombiana de Reumatología. Published by Elsevier España, S.L.U. All rights reserved

Shift in epitope dominance of IgM and IgG responses to Plasmodium falciparum MSP1 block 4

<p>Abstract</p> <p>Background</p> <p><it>Plasmodium falciparum </it>merozoite surface protein-1 (MSP1) has been extensively studied as a blood-stage malaria vaccine candidate, with most work focused on the conserved 19 kDa and semi-conserved 42 kDa C-terminal regions (blocks 16-17) and the hypervariable N-terminal repeat region (block 2). However, recent genotyping studies suggest that additional regions of MSP1 may be under selective pressure, including a locus of intragenic recombination designated as block 4 within the 3' region of the gene.</p> <p>Methods</p> <p>The current study examined the antibody response to the two parental and two recombinant forms of block 4 and to blocks 16-17 (3D7) in study populations from Colombia, Papua New Guinea and Cameroon that differ in malaria transmission intensity and ethnic composition.</p> <p>Results</p> <p>IgM and IgG antibodies were detected against parental and recombinant MSP1 block 4 peptides in all three populations. Overall, 32-44% of the individuals produced IgM to one or more of the peptides, with most individuals having IgM antibodies reactive with both parental and recombinant forms. In contrast, IgG seropositivity to block 4 varied among populations (range 15-65%), with the majority of antibodies showing specificity for one or a pair of block 4 peptides. The IgG response to block 4 was significantly lower than that to blocks 16-17, indicating block 4 is subdominant. Antibodies to block 4 and blocks 16-17 displayed distinct IgG subclass biases, with block 4 responses biased toward IgG3 and blocks 16-17 toward IgG1. These patterns of responsiveness were consistently observed in the three study populations.</p> <p>Conclusions</p> <p>Production of antibodies specific for each parental and recombinant MSP1 block 4 allele in different populations exposed to <it>P. falciparum </it>is consistent with balancing selection of the MSP1 block 4 region by the immune response of individuals in areas of both low and high malaria transmission. MSP1 block 4 determinants may be important in isolate-specific immunity to <it>P. falciparum</it>.</p

The impact of city-wide deployment of Wolbachia-carrying mosquitoes on arboviral disease incidence in Medellín and Bello, Colombia: study protocol for an interrupted time-series analysis and a test-negative design study.

Background: Dengue, chikungunya and Zika are viral infections transmitted by Aedes aegypti mosquitoes, and present major public health challenges in tropical regions. Traditional vector control methods have been ineffective at halting disease transmission. The World Mosquito Program has developed a novel approach to arbovirus control using Ae. aegypti stably transfected with the Wolbachia bacterium, which have significantly reduced ability to transmit dengue, Zika and chikungunya in laboratory experiments. Field releases in eight countries have demonstrated Wolbachia establishment in local Ae. aegypti populations. Methods: We describe a pragmatic approach to measuring the epidemiological impact of city-wide Wolbachia deployments in Bello and Medellín, Colombia. First, an interrupted time-series analysis will compare the incidence of dengue, chikungunya and Zika case notifications before and after Wolbachia releases, across the two municipalities. Second, a prospective case-control study using a test-negative design will be conducted in one quadrant of Medellín. Three of the six contiguous release zones in the case-control area were allocated to receive the first Wolbachia deployments in the city and three to be treated last, approximating a parallel two-arm trial for the >12-month period during which Wolbachia exposure remains discordant. Allocation, although non-random, aimed to maximise balance between arms in historical dengue incidence and demographics. Arboviral disease cases and arbovirus-negative controls will be enrolled concurrently from febrile patients presenting to primary care, with case/control status classified retrospectively following laboratory diagnostic testing. Intervention effect is estimated from an aggregate odds ratio comparing Wolbachia-exposure odds among test-positive cases versus test-negative controls. Discussion: The study findings will add to an accumulating body of evidence from global field sites on the efficacy of the Wolbachia method in reducing arboviral disease incidence, and can inform decisions on wider public health implementation of this intervention in the Americas and beyond. Trial registration: ClinicalTrials.gov: NCT03631719. Registered on 15 August 2018

The cooling of convolvulaceous flowers in a tropical environment

The temperatures of flowers of Ipomoea pes-caprae ssp. brasilensis, Ipomoea aquatica and Merremia borneensis in bright sunshine, were studied to determine the role of corollas and sepals in cooling the gynoecium. The corollas and sepals were prevented from transpiring by greasing, to investigate the extent of evaporative cooling. In the exposed natural habitats of these flowers the maximum temperatures of air and soil were high (32 and 42degreesC, respectively) and corolla, sepal and gynoecium temperatures were often intermediate. Despite being almost astomatous, significant evaporative cooling was observed in the corolla. Between 20 and 80% of the energy absorbed by the corollas was dissipated as evaporation. The sepals were stomatous and their evaporative cooling was very important in reducing the temperature of the gynoecium. The temperatures of the non-transpiring gynoecia and corollas were Significantly higher than the temperatures of the normally transpiring corollas and gynoecia. Furthermore, the gynoecia temperatures were significantly higher with non-transpiring corollas than with normally transpiring corollas, suggesting that the corollas alone play a role in maintaining the gynoecium within optimal temperatures levels. It was shown in an incubation experiment that temperatures exceeding 32degreesC may damage the carpels, and temperatures exceeding 42degreesC may damage sepals. Pollen grains were killed after 200 min of exposure to temperatures in the range 32 to 47degreesC. It is concluded that the cooling mechanisms (evaporation and self-shading) are critical for the reproductive success of these flowers in their natura environment

Diseño de una metodología para orientar el proceso de capacitación que realiza la Registraduria Nacional del estado civil a través de un ambiente virtual

Este proyecto de Investigación se centra en la implementación de una metodología educativa para la realización de las capacitaciones virtuales para jurados de votación por parte de la Registraduria Nacional del Estado Civil. Se realizó una revisión de la herramienta de capacitación que se ha venido utilizando en las jornadas electorales; Este material en la actualidad, es una cartilla virtual la cual se enfoca en el correcto diligenciamiento de los formularios por parte de los jurados el día de las elecciones. Esta herramienta no cuenta con la metodología ni la estructura de un ambiente de Aprendizaje; Cualquier ciudadano mayor de edad puede ser elegido por sorteo como jurado, dando como resultado que sea una actividad obligatoria con sanciones por su incumplimiento. Se busca rediseñar la herramienta de capacitación haciéndola de fácil manejo, interactiva, incluyendo material de apoyo, buscando que el ciudadano tome esta actividad como una oportunidad de ser un actor de un proceso electoral. Se aplicó una encuesta a funcionarios y a potenciales ciudadanos los cuales participaron en la prueba piloto del AVA, con el objeto de conocer sus apreciaciones y viabilidad del ambiente de aprendizaje propuesto dando como resultado que puede ser una alternativa viable para remplazar las capacitaciones presenciales y contiene toda la información necesaria para ejercer correctamente su función como Jurado de Votació