Relationships between synoptic-scale transport and interannual variability of inorganic cations in surface snow at Summit, Greenland: 1992-1996

Version of RecordTo fully utilize the long-term chemical records retrieved from central Greenland ice cores, specific relationships between atmospheric circulation and the variability of chemical species in the records need to be better understood. This research examines associations between the variability of surface snow inorganic cation chemistry at Summit, Greenland (collected during 1992-1996 summer field seasons) and changes in air mass transport pathways and source regions, as well as variations in aerosol source strength. Transport patterns and source regions are determined through 10-day isentropic backward air mass trajectories during a 1 month (late May to late June) common season over the 5 years. Changes in the extent of exposed continental surfaces in source regions are evaluated to estimate aerosol-associated calcium and magnesium ion source strength, while forest fire activity in the circumpolar north is investigated to estimate aerosol ammonium ion source strength. During the 1995 common season, 3 times more calcium and magnesium accumulated in the snowpack than the other study years. Also, an increasing trend of ammonium concentration was noted throughout the 5 years. Anomalous transport pathways and velocities were observed during 1995, which likely contributed to the high levels of calcium and magnesium. Increased forest fire activity in North America was concurrent with increased levels of ammonium and potassium, except for 1996, when ion levels were above average and forest fire activity was below average. Because of the ubiquitous nature of soluble ions, we conclude that it is very difficult to establish a quantitative link between the ion content of snow and firn at Summit and changes in aerosol source regions and source strength.Slater, J. F., Dibb, J. E., Keim, B. D., & Kahl, J. D. w. (2001). Relationships between synoptic-scale transport and interannual variability of inorganic cations in surface snow at Summit, Greenland: 1992-1996. Journal of Geophysical Research 106(D18), 20,897-20,91

Humo de Capsicum baccatum L. var. baccatum (Solanaceae) repele las ninfas de Triatoma infestans (Klug) (Hemiptera: Reduviidae)

Control of the Chagas disease vector, Triatoma infestans (Klug) (Hemiptera: Reduviidae) with synthetic pesticides in Bolivia has become increasingly inefficient due to the development of resistance in the insects. In the Chaco region of Bolivia, guaraní populations have approached the problem by fumigating their houses with the smoke of native plants. Through interviews and field work with local guides, the main plant used by the guaraníes was collected and later identified as Capsicum baccatum L. var. baccatum (Solanaceae). In choice bioassays, filter papers exposed to the smoke of the plant repelled nymphs of T. infestans. Activity remained significant after storing the exposed filter papers for 9 days. Chemical analysis of smoke and literature data suggested that capsaicinoids present in the smoke were responsible for the repellent effect. The data presented provide a rationale for the use of C. baccatum var. baccatum to control the Chagas vector bythe guaraní populations.El control del vector de la enfermedad de Chagas, Triatoma infestans (Klug) (Hemiptera: Reduviidae) con plaguicidas sintéticos en Bolivia se ha vuelto cada vez más ineficiente debido al desarrollo de resistencias en los insectos. En la región del Chaco de Bolivia, las poblaciones guaraníes han abordado el problema fumigando sus casas con el humo de las plantas nativas. A través de entrevistas y trabajo de campo con guías locales, se recogió la principal planta utilizada por los guaraníes y posteriormente se identificó como Capsicum baccatum L. var. baccatum (Solanaceae). En bioensayos selectos, los papeles de filtro expuestos al humo de la planta repelieron a las ninfas de T. infestans. La actividad siguió siendo significativa después de almacenar los papeles de filtro expuestos durante 9 días. El análisis químico del humo y los datos de la literatura sugieren que los capsaicinoides presentes en el humo eran responsables del efecto repelente. Los datos presentados proporcionan una justificación para el uso de C. baccatum var. baccatum para el control del vector Chagas por las poblaciones guaraníes

Age-related anomalies of electrocardiograms in patients from areas with differential Seroprevalence of Chagas disease in Southern Bolivia

Introduction: Chagas disease currently affects some 6 million people around the world. At the chronic stage, cardiomyopathy occurs in about 20–30% of infested people. Most prevalence studies have focused on young to adult people due to the drastic consequences of acquiring the pathogen and the possibility to cure the disease at this age; the prevalence of this disease, the effect of patients' sex and the consequences to senescent people have been largely neglected. This study looks to characterize the seroprevalence of Chagas disease and its relation with occurrence of electrocardiographic anomalies associated with sex and age, and to compare rural and urban populations in Bolivia. Methodology: Seroprevalence of Chagas disease was determined in blood samples and electrocardiograms were performed on seropositive individuals. Results: The rural population showed higher seroprevalence than the urban population (92% and 40%, respectively). The proportion of Chagasic cardiac anomalies in seropositive persons was highest in patients of the 50–59 age group (36%) as compared with the 40–49 (8%) and the ≥60 (17%) age groups. Conclusions: Higher seroprevalence in rural population was attributable to a higher probability to encounter the vector in rural areas. Increased exposure to infection and to development of the disease symptoms together with increased lethality of the disease as patients age explains the age-related Chagasic electrocardiographic anomalies. Since rural and urban populations showed different reactions under Chagas disease and the rural population was mainly of guaraní stock, the genetic and environmental determinants of the results should be further explored.Universidad Mayor Real y Pontificia de San Francisco Xavier de Chuquisaca Guarani Council of Chuquisaca Captains Latin American Network for Research in Bioactive Natural Products (LANBIO) International Foundation for Science D/5472-1 International Science Programme at Uppsala University (ISP) BOL-01Versión publicada - versión final del edito

Hypoglycemia and the Origin of Hypoxia-Induced Reduction in Human Fetal Growth

The most well known reproductive consequence of residence at high altitude (HA >2700 m) is reduction in fetal growth. Reduced fetoplacental oxygenation is an underlying cause of pregnancy pathologies, including intrauterine growth restriction and preeclampsia, which are more common at HA. Therefore, altitude is a natural experimental model to study the etiology of pregnancy pathophysiologies. We have shown that the proximate cause of decreased fetal growth is not reduced oxygen availability, delivery, or consumption. We therefore asked whether glucose, the primary substrate for fetal growth, might be decreased and/or whether altered fetoplacental glucose metabolism might account for reduced fetal growth at HA.Doppler and ultrasound were used to measure maternal uterine and fetal umbilical blood flows in 69 and 58 residents of 400 vs 3600 m. Arterial and venous blood samples from mother and fetus were collected at elective cesarean delivery and analyzed for glucose, lactate and insulin. Maternal delivery and fetal uptakes for oxygen and glucose were calculated.The maternal arterial – venous glucose concentration difference was greater at HA. However, umbilical venous and arterial glucose concentrations were markedly decreased, resulting in lower glucose delivery at 3600 m. Fetal glucose consumption was reduced by >28%, but strongly correlated with glucose delivery, highlighting the relevance of glucose concentration to fetal uptake. At altitude, fetal lactate levels were increased, insulin concentrations decreased, and the expression of GLUT1 glucose transporter protein in the placental basal membrane was reduced.Our results support that preferential anaerobic consumption of glucose by the placenta at high altitude spares oxygen for fetal use, but limits glucose availability for fetal growth. Thus reduced fetal growth at high altitude is associated with fetal hypoglycemia, hypoinsulinemia and a trend towards lactacidemia. Our data support that placentally-mediated reduction in glucose transport is an initiating factor for reduced fetal growth under conditions of chronic hypoxemia

Aerosol emissions by tropical forest and savanna biomass burning: characteristic trace elements and fluxes

International audienceAerosol particles were collected during the dry season in the amazonian forest and in African and Brazilian savannas. Sampling was performed inside the plumes of vegetation fires and in the local background atmosphere. Samples were analysed for their elemental composition by Particle Induced X-Ray Emission (PIXE). Enrichment factors relative to the local background were calculated. Savanna fire aerosols are characterised by enrichments in elements like K, P, CI, Zn, and Br, whereas forest fire emissions are enriched in Si and Ca. The unexpected low potassium enrichment factor for the forest fires could be due to the prevailing smoldering conditions, whereas the high values of potassium enrichment factor during savanna fires could be associated with the predominant flaming conditions. This result indicates that potassium may be considered a good tracer of the flaming phase of fires only. Emission factors of P, S, C1, K, Ca, Mn, Zn, Br and total particulate matter were calculated for African savanna fires. Our estimates of the annual potassium and zinc emissions by tropical savanna fires indicate that the contribution of this source should be taken into account to understand the biogeochemical cycle of these elements

Données isoenzymatiques pour 11 souches boliviennes de Trypanosoma cruzi: interprétation génétique et calcul des distances

info:eu-repo/semantics/publishe