Intra-urban variability of long-term exposure to PM2.5 and NO2 in five cities in Colombia.

Rapidly urbanizing cities in Latin America experience high levels of air pollution which are known risk factors for population health. However, the estimates of long-term exposure to air pollution are scarce in the region. We developed intraurban land use regression (LUR) models to map long-term exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) in the five largest cities in Colombia. We conducted air pollution measurement campaigns using gravimetric PM2.5 and passive NO2 sensors for 2 weeks during both the dry and rainy seasons in 2021 in the cities of Barranquilla, Bucaramanga, Bogotá, Cali, and Medellín, and combined these data with geospatial and meteorological variables. Annual models were developed using multivariable spatial regression models. The city annual PM2.5 mean concentrations measured ranged between 12.32 and 15.99 µg/m3 while NO2 concentrations ranged between 24.92 and 49.15 µg/m3. The PM2.5 annual models explained 82% of the variance (R2) in Medellín, 77% in Bucaramanga, 73% in Barranquilla, 70% in Cali, and 44% in Bogotá. The NO2 models explained 65% of the variance in Bucaramanga, 57% in Medellín, 44% in Cali, 40% in Bogotá, and 30% in Barranquilla. Most of the predictor variables included in the models were a combination of specific land use characteristics and roadway variables. Cross-validation suggests that PM2.5 outperformed NO2 models. The developed models can be used as exposure estimate in epidemiological studies, as input in hybrid models to improve personal exposure assessment, and for policy evaluation.

COVID-19 and public transport: an overview and recommendations applicable to Latin America / COVID-19 y transporte público: una revisión y recomendaciones aplicables a América Latina

Abstract The article presents a general overview on COVID-19 transmission in the context of public transport, particularly applicable to decision making in Latin America. Based on recent findings on COVID-19 transmission and the relative importance of each factor (droplets, fomites, and aerosol routes) in such transmission, we seek to update the discussion on the topic that has generally been based on social distance as the only parameter for reducing the risk of transmission and broadens the vision to integrate ventilation, users' behavior (mask and eye protection use, silence while in the transport system) and travel distance. Recommendations to improve mobility conditions reducing the risk of COVID-19 contagion are provided.

Resumen El artículo presenta una revisión de transmisión de COVID-19 en el contexto de transporte público, con aplicación particular para toma de decisiones en América Latina. Con base en los hallazgos recientes sobre transmisión de Covid-19 y la importancia relativa de cada factor (gotículas, fómites y rutas de aerosoles) en dicha transmisión, buscamos actualizar la discusión sobre el tema que generalmente se ha basado en la "distancia social" como parámetro único de reducción de riesgo de transmisión y amplía esta visión para integrar la ventilación, el comportamiento de usuarios (uso de mascarilla, protección ocular, silencio), y la distancia de viaje. Se indican al final recomendaciones para mejorar las condiciones de movilidad en general sin aumentar el riesgo de contagio de Covid-19.

Effects of fuel change to electricity on PM2.5 local levels in the Bus Rapid Transit System of Bogota.

The TransMilenio (TM) is a transport system. Twenty-year-old TM is a fast, highly efficient, and self-sufficient mode of passenger transport. This work aims to evaluate the effects of changing current TM diesel buses by electricity-powered buses (battery, wire-based), on the PM2.5 concentrations at surface level. Emissions calculations considering combustions and resuspension of TM and Non-TM were performed. A CFD model was implemented to estimate current PM2.5 concentrations at the roadside level, and the CFD results were validated using the statistic parameters: MB, RMSE, r, and IOA. Results from the emission calculations indicate that TM buses (30-50%) are one of the main sources of primary PM2.5 in all the considered urban sites in this study. Non-exhaust emissions from most vehicle categories were also identified as an important source of primary PM2.5 (40% of total emissions). The CFD model reproduced closely the trends and levels of PM2.5 concentrations measured at the roadside level in all the locations. Replacing TM diesel vehicles with electric vehicles reduces PM2.5 concentrations between 10 and 30% according to the CFD results obtained. Higher reductions can be achieved if policies are adopted to control other types of vehicles and non-exhaust emissions since they have a contribution of about 60%. Finally, this study shows that the combined use of emission calculations and advanced near-road dispersion models are useful tools to study and manage air quality in large cities.

Air quality variations in Northern South America during the COVID-19 lockdown.

Lockdown measures led to air pollution decrease in several countries around the world such as China and India, whereas other regions experimented an increase in pollutant concentrations. Northern South America (NSA) was one of those areas where pollution changed during lockdown due to high fire activity. This study aims to analyze, for the first time in NSA, the behavior of selected criteria air pollutants during the implementation of the SARS-CoV-2 lockdown in two high populated cities of the region: Bogotá and Medellín in Colombia. A set of tools including surface measurements, as well as satellite and modeled data were used. 24-hour average concentrations of PM10, PM2.5, and NO2 were collected from air quality stations for the lockdown period ranging from February 21 to June 30, 2020. The Copernicus Atmosphere Monitoring Service (CAMS) was used to analyze the fire flux OC as a biomass burning (BB) indicator, and tropospheric NO2 concentrations were retrieved from TROPOMI. The HYSPLIT model was used to analyze back trajectories and fire data were obtained from MODIS sensor measurements. Our analysis shows short-term background NO2, PM10, and PM2.5 concentration reductions of 60%, 44%, and 40%, respectively, for the strict lockdown; and 62%, 58%, and 69% for the relaxed lockdown. Corresponding long-term reductions were of 50%, 32%, and 9% for the strict lockdown; and 37%, 29%, and 19% for the relaxed lockdown. Regional BB increased PM2.5 concentrations by 20 µg/m3 during the strict lockdown, and the Saharan dust event increased PM10 concentrations up to 168 µg/m3 in Bogotá, and 104 µg/m3 in Medellín, bringing an additional risk of morbidity and mortality for population. Regional BB has several causes that need to be properly managed to benefit local air quality improvement plans. Future cleaner transport policies equivalent to reduced lockdown mobility could bring pollution close to WHO guidelines.

GAPS-megacities: A new global platform for investigating persistent organic pollutants and chemicals of emerging concern in urban air.

A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∼3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m3, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2-5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a 'reference city' for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.

Air pollution emission effects of changes in transport supply: the case of Bogotá, Colombia.

Transportation policy and planning decisions, including decisions on new infrastructure and public transport improvements, affect local and global environmental conditions. This work studies the effect of increased road capacity on traffic-related emissions in Bogotá using a tool that couples a transportation model with emission factors from COPERT IV. We followed a parametric approach varying transport supply and demand, comparing three scenarios: a baseline scenario that represents the transportation system in Bogota in 2015; scenario 1 incorporates five highway capacity-enhancement projects in Bogotá and assumes insensitive travel demand; scenario 2 incorporates the new highway projects but assumes a demand increase of 13% in vehicle trips with private cars. Results include daily and annual values of traffic-related emissions of five air pollutant criteria: CO, NOx, PM10, SO2, and VOC for the baseline scenario, scenario 1, and scenario 2. We found a reduction in emissions after adding highway capacity and assuming inelastic demand (scenario 1). Scenario 1 results in a 15% reduction in PM10 emissions and a 10% reduction in NOx emissions. In contrast, results for scenario 2 suggest increased emissions for all air pollutant criteria (e.g., VOC and CO emissions increase by 21% and 22% compared with the baseline scenario). Therefore, new traffic demand would eliminate the emission savings observed in scenario 1 and could potentially further degrade air quality in Bogotá. While an exact estimate of induced demand that may result from highway expansion in Bogotá is not available, this analysis highlights that such projects could lead to an increase in emissions unless there is a combined effort to managing demand of private vehicle trips.

Development of a high-resolution traffic emission model: Lessons and key insights from the case of Bogotá, Colombia.

This paper presents a traffic-related air emissions inventory of a developing megacity using a traffic assignment model that results in a detailed temporal and spatial emission representation, disaggregating emissions sources by vehicle type and hour of the day, for five criteria air pollutants.

Chemical composition and source apportionment of PM10 at an urban background site in a high-altitude Latin American megacity (Bogota, Colombia).

Bogota registers frequent episodes of poor air quality from high PM10 concentrations. It is one of the main Latin American megacities, located at 2600 m in the tropical Andes, but there is insufficient data on PM10 source contribution. A characterization of the chemical composition and the source apportionment of PM10 at an urban background site in Bogota was carried out in this study. Daily samples were collected from June 2015 to May 2016 (a total of 311 samples). Organic carbon (OC), elemental carbon (EC), water soluble compounds (SO42-, Cl-, NO3-, NH4+), major elements (Al, Fe, Mg, Ca, Na, K, P) and trace metals (V, Cd, Pb, Sr, Ba, among others) were analyzed. The results were interpreted in terms of their variability during the rainy season (RS) and the dry season (DS). The data obtained revealed that the carbonaceous fraction (∼51%) and mineral dust (23%) were the main PM10 components, followed by others (15%), Secondary Inorganic Compounds (SIC) (11%) and sea salt (0.4%). The average concentrations of soil, SIC and OC were higher during RS than DS. However, peak values were observed during the DS due to photochemical activity and forest fires. Although trace metals represented <1% of PM10, high concentrations of toxic elements such as Pb and Sb on RS, and Cu on DS, were obtained. By using a PMF model, six factors were identified (∼96% PM10) including fugitive dust, road dust, metal processing, secondary PM, vehicles exhaust and industrial emissions. Traffic (exhaust emissions + road dust) was the major PM10 source, accounting for ∼50% of the PM10. The results provided novel data about PM10 chemical composition, its sources and its seasonal variability during the year, which can help the local government to define control strategies for the main emission sources during the most critical periods.

Structural signatures of water-soluble organic aerosols in contrasting environments in South America and Western Europe.

This study describes and compares the key structural units present in water-soluble organic carbon (WSOC) fraction of atmospheric aerosols collected in different South American (Colombia - Medellín and Bogotá, Peru - Lima, Argentina - Buenos Aires, and Brazil - Rio de Janeiro, São Paulo, and Porto Velho, during moderate (MBB) and intense (IBB) biomass burning) and Western European (Portugal - Aveiro and Lisbon) locations. Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to assess the relative distribution of non-exchangeable proton functional groups in aerosol WSOC of diverse origin, for the first time to the authors' knowledge in South America. The relative contribution of the proton functional groups was in the order H-C > H-C-C= > H-C-O > Ar-H, except in Porto Velho during MBB, Medellín, Bogotá, and Buenos Aires, for which the relative contribution of H-C-O was higher than that of H-C-C=. The 1H NMR source attribution confirmed differences in aging processes or regional sources between the two geographic regions, allowing the differentiation between urban combustion-related aerosol and biological particles. The aerosol WSOC in Aveiro, Lisbon, and Rio de Janeiro during summer are more oxidized than those from the remaining locations, indicating the predominance of secondary organic aerosols. Fresh emissions, namely of smoke particles, becomes important during winter in Aveiro and São Paulo, and in Porto Velho during IBB. The biosphere is an important source altering the chemical composition of aerosol WSOC in South America locations. The source attribution in Medellín, Bogotá, Buenos Aires, and Lima confirmed the mixed contributions of biological material, secondary formation, as well as urban and biomass burning emissions. Overall, the information and knowledge acquired in this study provide important diagnostic tools for future studies aiming at understanding the water-soluble organic aerosol problem, their sources and impact at a wider geographic scale.

Retroneumoperitoneo y celulitis retroperitoneal: complicaciones inusuales de la enfermedad diverticular del colon / Pneumoretroperitoneum and retroperitoneal cellulitis: unusual complications of colonic diverticular disease

Se reporta dos casos de retroneumoperitoneo con neumo-mediastino, consecuencias de perforaciones diverticulares en el espacio retroperitoneal, en pacientes portadores de diverticulitis aguda y septicemia. En ambos casos no se comprobó contaminación peritoneal alguna, siendo sometidos a Colectomia parcial tipo Hartmann con buena evolución; al momento del reporte ambos han sido sometidos al restablecimiento del tránsito colo-rectal. Se discuten los problemas diagnósticos y los posibles mecanis-mos del paso del aire - y gérmenes bacterianos - al mediastino.

We report two cases of retropneumoperitoneum with pneumomediastinum, as a result of diverticular perforations in the retroperitoneal space, in patients with acute diverticulitis and septicemia. In both cases the patients underwent partial colectomy (Hartmann procedure) with good evolution, and no sign of peritoneal contamination was found. Currently both patients have undergone colorectal transit restoration. We discuss problems with the diagnosis and possible mechanism of the air and bacterial germ passage to the mediastinum.

Cuantificación de hidrocarburos policíclicos aromáticos urinarios en policías de tránsito del área metropolitana de Bogotá / Quantifying polycyclic aromatichydrocarbons in urine samples taken from traffic police working in Bogota's metropolitan area

Objetivos Cuantificar niveles urinarios de 1-hidroxipireno (1-OHP) y 3-hidroxibenzo [a] pireno (3-BAP) metabolitos de hidrocarburos policíclicos aromáticos (HAP) de interés toxicológico y relacionar su detección con el grado de exposición a material particulado de tamaño menor a 10 micras (PM10) u otros factores, en una población de Policías de Tránsito ocupacionalmente expuestos en el área metropolitana de Bogotá D.C. Métodos Se realizó un estudio de corte transversal en 524 Policías de Tránsito de los cuales 413 desarrollaban funciones operativas y 111 administrativas. Se tomaron muestras de orina de todos los individuos incluidos, para la determinación de metabolitos de HAP mediante cromatografía de gases con detección de masas. Se analizó la presencia de factores asociados con la detección de los metabolitos como tabaquismo, consumo de alimentos asados, lugar de residencia y exposición a PM10. Como medida de asociación se calcularon Odds Ratio (OR). Resultados Se encontraron niveles de 1-OHP y 3-BAP superiores en los individuos expuestos con OR significativos para detección de los metabolitos de 6,3 (IC 95% (3,6-11,1)) y 15,6 (IC 95% (6,2-39)), respectivamente. Se hallaron OR significativos para detección de metabolitos de HAP y exposición a PM10, tabaquismo y consumo de alimentos asados. Discusión Existe una asociación importante y significativa entre la exposición laboral a contaminación ambiental y la detección de metabolitos de HAP de importancia toxicológica en muestras de orina. Factores tales como tabaquismo, consumo de alimentos asados recientemente y exposición a PM10 también se encontraron asociados positivamente con la detección de dichos metabolitos pero en menor proporción.(AU)

Objective Quantifying polycyclic aromatic hydrocarbon levels in urine samples taken from a population of traffic police working in the metropolitan area of Bogotá who were occupationally exposed to 1-hydroxypyrene (1-OHP) and 3-hydroxy-benzo [a] pyrene (3-BaP) metabolites from polycyclic aromatic hydrocarbons (PAH) having toxicological interest, related to their detection, and a degree of exposure to particulate material having a size less than 10 micrometres (PM10) and/or other factors. Methods A cross-sectional study was made of 524 traffic police, 413 of whom were engaged in operational and 111 in administrative functions. Urine samples were taken from all the individuals included in the study for determining PAH metabolites by gas chromatography/mass spectrometry (GC/MS). The presence of factors associated with the detection of metabolites was analysed, such as smoking, consuming roasted/grilled food, place of residence and exposure to PM10. The odds ratio (OR) was calculated as a measure of association. Results Higher 1-OHP and 3-BaP levels were found in exposed individuals, having a significant OR for detecting 6.3 ((3.6-11.1) 95 % CI) and 15.6 ((6.2-39) 95 % CI) metabolites, respectively. Significant OR were found for detecting PAH metabolites and exposure to PM10, smoking and consuming roasted/grilled food. Discussion There was an important and significant association between work-related exposure to environmental contamination and detecting toxicologically important PAH metabolites in urine samples. Factors such as smoking, consuming freshly grilled/roasted food and exposure to PM10 were also found to be positively associated with detecting such metabolites, but to a lesser extent.(AU)

[Quantifying polycyclic aromatic hydrocarbons in urine samples taken from traffic police working in Bogota's metropolitan area]. / Cuantificación de hidrocarburos policíclicos aromáticos urinarios en policías de tránsito del área metropolitana de Bogotá

OBJECTIVE: Quantifying polycyclic aromatic hydrocarbon levels in urine samples taken from a population of traffic police working in the metropolitan area of Bogotá who were occupationally exposed to 1-hydroxypyrene (1-OHP) and 3-hydroxy-benzo[a]pyrene (3-BaP) metabolites from polycyclic aromatic hydrocarbons (PAH) having toxicological interest, related to their detection, and a degree of exposure to particulate material having a size less than 10 micrometres (PM10) and/or other factors. METHODS: A cross-sectional study was made of 524 traffic police, 413 of whom were engaged in operational and 111 in administrative functions. Urine samples were taken from all the individuals included in the study for determining PAH metabolites by gas chromatography/mass spectrometry (GC/MS). The presence of factors associated with the detection of metabolites was analysed, such as smoking, consuming roasted/grilled food, place of residence and exposure to PM10. The odds ratio (OR) was calculated as a measure of association. RESULTS: Higher 1-OHP and 3-BaP levels were found in exposed individuals, having a significant OR for detecting 6.3 ((3.6-11.1) 95 % CI) and 15.6 ((6.2-39) 95 % CI) metabolites, respectively. Significant OR were found for detecting PAH metabolites and exposure to PM10, smoking and consuming roasted/grilled food. DISCUSSION: There was an important and significant association between work-related exposure to environmental contamination and detecting toxicologically important PAH metabolites in urine samples. Factors such as smoking, consuming freshly grilled/roasted food and exposure to PM10 were also found to be positively associated with detecting such metabolites, but to a lesser extent.

Should they play outside? Cardiorespiratory fitness and air pollution among schoolchildren in Bogotá / ¿Deberían los niños jugar al aire libre? Acondicionamiento cardiorespiratorio y contaminación del aire en Bogotá

Objective: This study was aimed at comparing cardiorespiratory fitness (CF), measured as VO2 max, amongst school children exposed to varying levels of particulate matter (PM10), and air pollution in Bogotá, Colombia. Methods: This was a cross-sectional study; it involved 1,045 children aged 7-12 attending four public schools served by different public transit routes and systems. Three schools were classified as being highly polluted (HP) and one slightly polluted (SP). The children and their parents were surveyed to collect data regarding their socio-demographic characteristics, physical activity habits and respiratory disease background. Objective measurements of weight and height were used to calculate the body mass index. VO2max was estimated using the 20-meter shuttle-run test, previously validated for Bogotá. Spirometry was performed on 435 children. Results: After adjustment for covariates, no difference was found in VO2max between children attending SP or HP schools (girls SP 45.8 ml/kg/min vs HP 44.6 ml/kg/min, p=0.11; boys SP 47.2 ml/kg/min cf HP 48.2 ml/kg/min, p=0.41). Conclusions: VO2max levels did not differ amongst children attending schools exposed to high compared to low levels of air pollution and PM. A longitudinal study assessing children’s VO2max levels in relation to exposure to highly-polluted areas is warranted.

Objetivo: Comparar el acondicionamiento cardiorespiratorio medido como VO2 máximo en niños escolarizados expuestos a diferentes niveles de PM10 en Bogotá. Métodos: Estudio de corte transversal. Se incluyeron 1045 niños de 7-12 años de 4 colegios públicos con diferentes corredores viales y sistemas de transporte público. Tres colegios tenían alta contaminación (AC) y uno baja contaminación (BC). Se aplicó una encuesta a niños y padres sobre características sociodemográficas, actividad física, antecedentes de enfermedades respiratorias y salud. Se midió objetivamente peso y talla para calcular el índice masa corporal. El VO2 máximo se estimó con la prueba de Leger validada para Bogotá. Se realizaron espirometrias en 435 niños. Resultados: Después de ajustar por covariables, no se encontraron diferencias significativas en el VO2 máximo de los niños en colegios con BC ò AC. (Niñas BC: 45,8ml/kg/min vs. AC: 44,6ml/kg/min; p=0,11, niños BC: 47,2ml/kg/min vs. AC: 48,2ml/kg/min; p=0,41). Conclusión: No se encontraron diferencias en el VO2 máximo de los niños que asistían a los colegios de AC ó BC. Se recomienda un estudio longitudinal que evalúe los niveles de VO2 máximo en los niños expuestos a áreas altamente contaminadas.

Should they play outside? Cardiorespiratory fitness and air pollution among schoolchildren in Bogotá.

OBJECTIVE: This study was aimed at comparing cardiorespiratory fitness (CF), measured as VO2 max, amongst school children exposed to varying levels of particulate matter (PM10), and air pollution in Bogotá, Colombia. METHODS: This was a cross-sectional study; it involved 1,045 children aged 7-12 attending four public schools served by different public transit routes and systems. Three schools were classified as being highly polluted (HP) and one slightly polluted (SP). The children and their parents were surveyed to collect data regarding their socio-demographic characteristics, physical activity habits and respiratory disease background. Objective measurements of weight and height were used to calculate the body mass index. VO2max was estimated using the 20-meter shuttle-run test, previously validated for Bogotá. Spirometry was performed on 435 children. RESULTS: After adjustment for covariates, no difference was found in VO2max between children attending SP or HP schools (girls SP 45.8 ml/kg/min vs HP 44.6 ml/kg/min, p=0.11; boys SP 47.2 ml/kg/min cf HP 48.2 ml/kg/min, p=0.41). CONCLUSIONS: VO2max levels did not differ amongst children attending schools exposed to high compared to low levels of air pollution and PM. A longitudinal study assessing children's VO2max levels in relation to exposure to highly-polluted areas is warranted.

Detección de transmisión transplacentaria de Anaplasma Marginale en bovinos asintomáticos / Detection of Anaplasma marginale Transplacental Transmission in Asymptomatic Cattle / The presence of Anaplasma marginale in calves descendants from cows with asymptomatic infections, was detected. Polymerase chain reaction (PCR) assays carried out in blood samples from 31 healthy cows and their respective calves, revealed the presence of A. marginale-specific DNA in 70 and 40% of them, respectively. The detection of a portion of A. marginale genome in newborn calves, suggests a transplacental mother-offspring transmission. The epizootiological implications of A. marginale-infection in asymptomatic animals and the potential of transplacental transmission in the maintenance of A. marginale were considered. Results lead to conclude that A. marginale transplacental transmission might be of frequent occurrence in the study area, so more specific techniques, such as PCR, are suggested for a more thorough diagnosis.

Se detecta la presencia de Anaplasma marginale en becerros hijos de vacas con infección asintomática. Ensayos de reacción en cadena de la polimerasa (PCR) llevados a cabo en muestras de sangre de 31 vacas lactantes, en aparente buen estado físico y sus respectivas crías, revelaron la presencia de ADN específico de A. marginale en el 70 y 40%, respectivamente. La detección de parte del genoma de A. marginale en becerros recién nacidos, hijos de vacas asintomáticas PCR positivas, sugiere la transmisión de la infección madre-hijo por vía transplacentaria. Se discute las implicaciones epizootiológicas de la infección por A. marginale en animales asintomáticos y se advierte sobre la potencialidad de esta forma de transmisión en el mantenimiento del ciclo de este organismo. Se concluye que la transmisión por vía transplacentaria podría ser un evento de frecuente ocurrencia en el área de estudio y se sugiere la utilización de técnicas producto de la nueva biotecnología como la PCR para incrementar la especificidad en el diagnóstico.

Genetic typing of Trypanosoma cruzi isolates from different hosts and geographical areas of western Venezuela / Tipaje genético de aislados de Trypanosoma cruzi de diferentes hospedadores y áreas geográficas del occidente de Venezuela

A total of 72 Trypanosoma cruzi isolates from different hosts and geographical regions of western Venezuela, where Chagas disease is endemic, were typed using ribosomal and mini-exon gene markers. The isolates were obtained from wild, peridomestic and domestic sources including triatomine-bugs, human acute chagasic patients and other mammals. Results showed that T. cruzi two major phylogenetic lineages, T. cruzi I and T. cruzi II were present. However, a remarkable predominance of T. cruzi I (96%) over T. cruzi II (4%) was observed. The present results suggest that in western Venezuela circulation of both T. cruzi I and T. cruzi II isolates is independent from the source of isolation and the geographical area where they occur, with predominance of T. cruzi I. The epidemiological significance of the present results is discussed

Un total de 72 aislados de Trypanosoma cruzi obtenidos de diferentes hospedadores y regiones geográficas del occidente de Venezuela, donde la enfermedad de Chagas es endémica, fueron caracterizados genéticamente utilizando marcadores moleculares de los genes ribosomales y del mini-exón. Los aislados fueron obtenidos de fuentes silvestres y domésticas, incluyendo triatominos-vectores, pacientes chagásicos agudos y otros mamiferos. Los resultados mostraron la presencia de los dos linajes reconocidos para T. cruzi (TcI y TcII) en la mayoría de los aislados provenientes de los diferentes hospedadores estudiados. Sin embargo, fue observada una marcada predominancia de T. cruzi I (96%) sobre T. cruzi II (4%). Los presentes resultados sugieren que en el occidente de Venezuela la circulación de aislados de los linajes TcI y TcII es independiente de la fuente biológica de aislamiento y del área geográfica de procedencia, siendo predominante los aislados TcI. Se discute la significación epidemiológica de los presentes resultados

[Inflammatory bowel diseases: an immunological approach]. / Enfermedad inflamatoria intestinal: Una mirada inmunológica.

Inflammatory bowel diseases (IBD) are inflammatory diseases with a multifactorial component that involve the intestinal tract. The two relevant IBD syndromes are Crohn's disease (CD) and ulcerative colitis (UC). One factor involved in IBD development is a genetic predisposition, associated to NOD2/CARD15 and Toll-like receptor 4 (TLR4) polymorphisms that might favor infectious enterocolitis that is possibly associated to the development of IBD. The identification of specific immunologic alterations in IBD and their relationship to the etiology of the disease is a relevant research topic. The role of intra and extracellular molecules, such as transcription factors and cytokines that are involved in the inflammatory response, needs to be understood. The relevance of immunologic molecules that might drive the immune response to a T helper (Th) 1, Th 2 or the recently described Th 17 phenotype, has been demonstrated in animal models and clinical studies with IBD patients. CD and UC predominantly behave with a Th 1 and Th 2 immune phenotype, respectively. Recently, an association between CD and Th 17 has been reported. The knowledge acquired from immunologic and molecular research will help to develop accurate diagnostic methods and efficient therapies.

Enfermedad inflamatoria intestinal: Una mirada inmunológica: [revisión] / Inflammatory bowel diseases: An immunological approach: [review]

Inflammatory bowel diseases (IBD) are inflammatory diseases with a multifactorial component that involve the intestinal tract. The two relevant IBD syndromes are Crohn's disease (CD) and ulcerative colitis (UC). One factor involved in IBD development is a genetic predisposition, associated to NOD2/CARD15 and Toll-like receptor 4 (TLR4) polymorphisms that might favor infectious enterocolitis that is possibly associated to the development of IBD. The identification of specific immunologic alterations in IBD and their relationship to the etiology of the disease is a relevant research topic. The role of intra and extracellular molecules, such as transcription factors and cytokines that are involved in the inflammatory response, needs to be understood. The relevance of immunologic molecules that might drive the immune response to a T helper (Th) 1, Th 2 or the recently described Th 17 phenotype, has been demonstrated in animal models and clinical studies with IBD patients. CD and UC predominantly behave with a Th 1 and Th 2 immune phenotype, respectively. Recently, an association between CD and Th 17 has been reported. The knowledge acquired from immunologic and molecular research will help to develop accurate diagnostic methods and efficient therapies.

Isolation, purification, characterization and antigenic evaluation of GPI-anchored membrane proteins from Leishmania (Viannia) braziliensis.

GPI-anchored proteins from the plasma membrane of Leishmania (Viannia) braziliensis promastigotes were isolated, characterized and their migration pattern compared with those from other Leishmania species. In all cases the SDS-PAGE migration patterns were obtained under reducing and non-reducing conditions, using DL-dithiothreitol (DTT) as a reducer agent. Our results reveal that under reducing conditions the SDS-PAGE migration pattern is modified as a consequence of the disruption of disulphur-bonds and protein transformation. This is demonstrated when in non-reducing conditions the L. (V.) braziliensis-GPI-anchored proteins pattern showed a group of bands over the 100kDa, and two more bands of 52kDa and 50kDa in four different isolates, whereas under reducing conditions the major GPI-anchored protein fractions were detected as bands of 63kDa, 50kDa and an increase of peptides between 34kDa and 22kDa. Similar modifications were detected in the SDS-PAGE migration patterns of GPI-anchored protein fractions from L. (Leishmania) donovani, L. (L.) mexicana and L. (L.) amazonensis run under the same reducing conditions. Antigenic evaluation carried out by Western blot revealed the presence of two very specific L. (V.) braziliensis-GPI-anchored protein bands of 50kDa and 28kDa. These bands were specifically recognized by anti-L. (V.) braziliensis-GPI-anchored protein serum from experimentally immunized animals. These two peptides were not detected when GPI-anchored protein fractions from L. (L.) donovani, L. (L.) mexicana and L. (L.) amazonensis, were challenged with the same anti-serum. The present results lead us to suggest the use of these two peptides as biochemical markers to identify and differentiate leishmaniasis caused by L. (V.) braziliensis. The lack of immunogenicity observed here with the peptide gp63, a very common protein detected in Leishmania species, is considered.