biblioteca virtual en salud

BVS - Literatura Cientifica y Técnica


Historico de búsqueda  ()

Su selección  ()

Collapse All  Ocultar
Expand All  Mostrar
Texto completo (5295)
  • 1 (1186)
  • 1 (70)
Aspecto clínico
Resultados  1-10 de 13.364
Enviar resultado
adicionar en sua lista

Linking global climate change to local water availability: Limitations and prospects for a tropical mountain watershed.

González-Zeas, D; Erazo, B; Lloret, P; De Bièvre, B; Steinschneider, S; Dangles, O
| Idioma(s): Inglés
Bridging the gap between the predictions of coarse-scale climate models and the fine-scale climatic reality is a key issue of hydrological research and water management. While many advances have been realized in developed countries, the situation is contrastingly different in most tropical regions where we still lack information on potential discrepancies between measured and modeled climatic conditions. Consequently, water managers in these regions often rely on non-academic expertise to help them plan their future strategies. This issue is particularly alarming in tropical mountainous areas where water demand is increasing rapidly and climate change is expected to have severe impacts. In this article, we addressed this issue by evaluating the limitations and prospects in using regional climate models for evaluating the impact of climate change on water availability in a watershed that provides Quito, the capital of Ecuador, with about 30% of its current water needs. In particular, we quantified the temporal and spatial discrepancies between predicted and observed precipitation and temperature, and explored underlying mechanisms at play. Our results provide a strong critique of the inappropriate use of regional models to inform water planning with regard to adaptation strategies to face climate change. As a multidisciplinary group composed of hydrologists, ecologists and water managers, we then propose a framework to guide future climate change impact studies in tropical mountain watersheds where hydro-climatological data are scarce.
adicionar en sua lista

Distribution of agricultural pesticides in the freshwater environment of the Guayas river basin (Ecuador).

Deknock, Arne; De Troyer, Niels; Houbraken, Michael; Dominguez-Granda, Luis; Nolivos, Indira; Van Echelpoel, Wout; Forio, Marie Anne Eurie; Spanoghe, Pieter; Goethals, Peter
| Idioma(s): Inglés
The rapid increase and transition to more intensive agricultural activities in developing nations are often leading to misuse and overuse of pesticides, making their environment vulnerable for pesticide accumulation. In the present study, the Guayas river basin was taken as a representative case study to evaluate pesticide contamination of the Ecuadorean freshwater environment. Pesticide contamination was determined at 181 sampling sites by a multi-residue method using solid phase extraction (SPE) and pesticide residues were linked with agricultural land use activities to identify the main pollution sources. Moreover, the biological water quality status based on macroinvertebrate communities was determined at every location and the relation with the occurrence of pesticide residues was further investigated. Results showed that pesticide contamination of the freshwater environment was widely present in the Guayas river basin with detections at 108 sampling sites (60%). A total of 26 pesticide products were identified. Most frequently detected pesticides included cadusafos (62 locations), butachlor (21 locations) and pendimethalin (21 locations), with concentrations up to 0.081, 2.006 and 0.557 µg·L respectively. Pesticide residues detected in this study did not significantly influence the biological water quality (p = 0.69), but were observed to be positively correlated with ammonium concentrations, supporting the assumed combined application of chemical fertilizers and pesticides in agriculture. These pesticide residues were also associated with one or more agricultural crops, with in particular the banana and rice industries identified as major pollution sources. Both high consumption rates and non-specific application methods, such as aerial spraying of banana plantations and application directly into the water layer of irrigated rice fields, may attribute to pesticide contamination of the freshwater environment of the Guayas river basin. It is therefore suggested that measures, e.g. legal regulations and awareness campaigns, taken to prevent environmental pollution and accumulation of pesticides primarily focus on these industries.
adicionar en sua lista

Soil properties and agronomic factors affecting cadmium concentrations in cacao beans: A nationwide survey in Ecuador.

Argüello, David; Chavez, Eduardo; Lauryssen, Florian; Vanderschueren, Ruth; Smolders, Erik; Montalvo, Daniela
| Idioma(s): Inglés
Recent cadmium (Cd) regulation in chocolate threatens the sustainability of cacao production in Southwest America. Cadmium contamination in cacao beans has not been assessed at a country level. A nationwide survey was conducted in Ecuador to identify the spatial distribution of Cd in cacao beans, as well as soil and agronomic factors involved. Paired soil and plant samples (pods and leaves) were collected at 560 locations. Information on agronomic practices was obtained through a prepared questionnaire for farmers. Total soil Cd averaged 0.44 mg kg which is typical for young and non-polluted soils. Mean Cd concentration in peeled beans was 0.90 mg kg and 45% of samples exceeded the 0.60 mg kg threshold. Bean Cd hotspots were identified in some areas in seven provinces. Multivariate regression analysis showed that bean Cd concentrations increased with increasing total soil Cd and with decreasing soil pH, oxalate-extractable manganese (Mn ) and organic carbon (OC) (R = 0.65), suggesting that Cd solubility in soil mainly affects Cd uptake. Bean Cd concentration decreased a factor of 1.4 as the age of the orchard increased from 4 to 40 years. Bean Cd concentration was inconsistently affected by genotype (CCN-51 vs. Nacional), pruning or application of fertilizers. It is concluded that the relatively larger bean Cd concentrations in Ecuador are related to the high Cd uptake capacity of the plants combined with their cultivation on young soils, instead of Cd depleted weathered soils. Mitigation strategies should consider the application of amendments to modify such soil properties to lower soil Cd availability. There is scope for genetic mitigation strategy to reduce bean Cd, but this needs to be properly investigated.
adicionar en sua lista

Mercury assessment, macrobenthos diversity and environmental quality conditions in the Salado Estuary (Gulf of Guayaquil, Ecuador) impacted by anthropogenic influences.

Calle, Paola; Monserrate, Lorena; Medina, Francisco; Calle Delgado, Madeleine; Tirapé, Ana; Montiel, Marynes; Ruiz Barzola, Omar; Cadena, Omar Alvarado; Dominguez, Gustavo A; Alava, Juan José
| Idioma(s): Inglés
Water and sediment quality, macrobenthos diversity and mercury levels were assessed in the Salado Estuary, Gulf of Guayaquil (Ecuador) during 2008, 2009 and 2014. Severe hypoxia, anoxia and large fluctuations of salinity occurred in an impacted sector within Guayaquil city relative to a mangrove area within the Salado Mangroves Faunal Production Reserve. Significant inter-site and temporal differences were observed for dissolved oxygen, salinity, total dissolved solids, percentage of silts and clays, and species diversity. Macrobenthos' species richness for both sectors was greater during 2008. Sediments revealed high concentrations of total mercury (THg) (1.20-2.76 mg kg dw), exceeding Ecuador's SQG (0.1 mg kg dw). Sediment THg were significantly lower in 2014 than 2008/09. Biota sediment sccumulation factor values for mussels (3.0 to 34), indicate high bioaccumulation potential from mercury-contaminated sediments. This work highlights the need to develop stronger environmental policies to protect the Salado Estuary from anthropogenic stressors.
adicionar en sua lista

Access and benefit sharing--The perspective of basic research.

Beck, Erwin
| Idioma(s): Inglés
BACKGROUND: With the adoption of the Convention on Biological Diversity (CBD) the 196 member countries have agreed that organisms and their derivatives are the property of the country of their origin (CBD Art.3, Art 15). While the spirit of the CBD is generally acknowledged, the ownership causes considerable problems, last not least for research which by the CBD is considered as "use of genetic (=biological) resources" (GR). Such resources include all kinds of material which might contain functional genetic units while the derivatives consist of other materials of biological origin. HYPOTHESIS: Recently, many member countries claim the right of disposal also for digital sequence information about their GR. The Nagoya Protocol (NP) to the CBD regulates access to GR in exchange for sharing benefits arising from their use. Although the main focus of the NP is on "Research and Development" for commercial purposes, many of the issues and regulations apply also to basic, non-profit oriented biodiversity research. RESULTS: According to the NP (Art. 8a), simplified access to GR shall be granted by the provider countries for non-commercial biodiversity research, and a simple research permit may thus be sufficient for research projects not requiring transfer of GR. Nevertheless, there is not yet consensus about the interpretation of the terms "simplified measures" and "basic, academic, non-profit research". Thus negotiations about access to GR for basic research are still an ad-hoc issue at the discretion of a country's relevant authority, termed "Focal Point". Because basic research is mostly financed by public money, compliance of the researcher with the international regulations is of public interest, and in the EU, additional regulations shall make this sure on the part of the researcher by an obligatory declaration of "due diligence". CONCLUSION: Apart from all legal uncertainties on both sides the provider country and the researcher, respect of legal commitments and mutual trust are indispensable for overcoming ABS-difficulties in basic research.
adicionar en sua lista

Different responses of taxonomic and functional bird diversity to forest fragmentation across an elevational gradient.

Santillán, Vinicio; Quitián, Marta; Tinoco, Boris A; Zárate, Edwin; Schleuning, Matthias; Böhning-Gaese, Katrin; Neuschulz, Eike Lena
| Idioma(s): Inglés
Many studies have investigated how habitat fragmentation affects the taxonomic and functional diversity of species assemblages. However, the joint effects of habitat fragmentation and environmental conditions on taxonomic and functional diversity, for instance across elevational gradients, have largely been neglected so far. In this study, we compare whether taxonomic and functional indicators show similar or distinct responses to forest fragmentation across an elevational gradient. We based our analysis on a comprehensive data set of species-rich bird assemblages from tropical montane forest in the Southern Andes of Ecuador. We monitored birds over 2 years in two habitat types (continuous and fragmented forest) at three elevations (i.e., 1000, 2000, and 3000 m a.s.l) and measured nine morphological traits for each bird species on museum specimens. Bird species richness and abundance were significantly higher in fragmented compared to continuous forests and decreased towards high elevations. In contrast, functional diversity was significantly reduced in fragmented compared to continuous forests at low elevations, but fragmentation effects on functional diversity tended to be reversed at high elevations. Our results demonstrate that taxonomic and functional indicators can show decoupled responses to forest fragmentation and that these effects are highly variable across elevations. Our findings reveal that functional homogenization in bird communities in response to fragmentation can be masked by apparent increases in taxonomic diversity, particularly in diverse communities at low elevations.
adicionar en sua lista

Presence of anisakid larvae in commercial fishes landed in the Pacific coast of Ecuador and Colombia/ Presencia de larvas de anisakidos en peces comercializados y desembarcados en la costa del Pacífico de Ecuador y Colombia

Castellanos, Jenniffer Alejandra; Santana-Piñeros, Ana María; Mercado, Rubén; Peña, Sebastián; Pustovrh, Carolina; Cruz-Quintana, Yanis
| Idioma(s): Inglés
Abstract Introduction: Anisakidosis is a zoonotic disease caused by the consumption of raw or undercooked fish or crustaceans parasitized by nematode larvae of the Anisakidae family. In this study, the presence of anisakid larvae was identified in fish species of consumer of the Pacific coast in Ecuador and Colombia. Methods: We obtained 438 samples grouped into twenty species of fish caught in the fishing ports of Manta, Santa Rosa, Buenaventura and Tumaco. The morphological identification of the larvae was made by taxonomy and the percentage of infection, were calculated. For the identification of species, a multiplex PCR was carried. Results: The taxonomic review identified eight species of fish as hosts of the genders Anisakis and Pseudoterranova. The larvae were isolated mainly from the intestine with a percentage of infection between 18 and 100%. The percentage of infection and identification of anisakids in these fish will aid in the prevention and control of anisakiasis as a possible emerging disease for this area of the Pacific. With the multiplex PCR, A. pegreffii, A. physeteris, and P. decipiens were identified. Conclusion: The identification of these species is reported for the first time in this geographical area, providing the basis for future research into the Anisakidae family. Resumen Introducción: La anisakidosis es una enfermedad zoonótica causada por el consumo de pescado o crustáceos crudos o poco cocinados parasitados por las larvas de nematodos de la familia Anisakidae. En este estudio, se identificó la presencia de larvas de anisakidos en especies de peces de consumo de la costa del Pacífico en Ecuador y Colombia. Métodos: Obtuvimos 438 muestras agrupadas en veinte especies de peces capturados en los puertos pesqueros de Manta, Santa Rosa, Buenaventura y Tumaco. La identificación morfológica de las larvas se realizó por taxonomía y se calculó el porcentaje de infección. Para la identificación de las especies, se llevó a cabo una PCR múltiplex. Resultados: La revisión taxonómica identificó ocho especies de peces como huéspedes de los géneros Anisakis y Pseudoterranova. Las larvas se aislaron principalmente del intestino con un porcentaje de infección entre 18 y 100%. El porcentaje de infección e identificación de anisakidos en estos peces ayudará a prevenir y controlar la anisakiasis como una posible enfermedad emergente en esta área del Pacífico. Con la PCR múltiplex, se identifico A. pegreffii, A. physeteris y P. decipiens. Conclusión: La identificación de estas especies se informa por primera vez en esta área geográfica, proporcionando la base para futuras investigaciones sobre la familia Anisakidae.
adicionar en sua lista

Gender differences in cardiovascular risk assessment in elderly adults in Ecuador: evidence from a national survey.

Sisa, Ivan
| Idioma(s): Inglés
The present study aimed to predict the risk of developing cardiovascular disease (CVD) over a 5-year period and how it might vary by sex in an ethnically diverse population of older adults. We used a novel CVD risk model built and validated in older adults named the Systematic Coronary Risk Evaluation in Older Persons (SCORE OP). A population-based study analyzed a total of 1307 older adults. Analyses were done by various risk categories and sex. Of the study population, 54% were female with a mean age of 75±7.1 years. According to the SCORE OP model, individuals were classified as having low (9.8%), moderate (48.1%), and high or very high risk (42.1%) of CVD-related mortality. Individuals at higher risk of CVD were more likely to be male compared with females, 53.9% vs 31.8%, respectively (p<0.01). Males were more likely to be younger, living in rural areas, had higher levels of schooling, and with the exception of smoking status and serum triglycerides, had lower values of traditional risk factors than females. In addition, males were less likely to require blood pressure-lowering therapy and statin drugs than females. This gender inequality could be driven by sociocultural determinants and a risk factor paradox in which lower levels of the cardiovascular risk factors are associated with an increase rather than a reduction in mortality. These data can be used to tailor primary prevention strategies such as lifestyle counseling and therapeutic measures in order to improve male elderly health, especially in low-resource settings.
adicionar en sua lista

A First Insight into the katG and rpoB Gene Mutations of Multidrug-Resistant Mycobacterium tuberculosis Strains from Ecuador.

Franco-Sotomayor, Greta; Garzon-Chavez, Daniel; Leon-Benitez, Margarita; de Waard, Jacobus H; Garcia-Bereguiain, Miguel Angel
| Idioma(s): Inglés
The aim of this study was to characterize the most frequent mutations associated with rifampicin (RIF) and isoniazid (INH) resistance of Mycobacterium tuberculosis isolates from Ecuador. Sequence analysis of 40 strains, resistant for the tuberculosis drugs INH, RIF, or for both showed that of the 31 strains with resistance to INH, 20 strains (64.5%) carried a mutation in the katG gene (codon 315). Eight INH-resistant strains carried a mutation in the katG gene at codon 463. This katG463 mutation, considered a phylogenetic marker, was exclusively found in INH-resistant strains and not in 121 INH-susceptible strains. Of the 35 strains resistant to RIF, 33 (93.9%) had mutations in the hot spot region of the rpoB gene, predominantly in codons 531, 516, and 526. Our results show that sequence-based detection for drug resistance of the katG will identify, respectively, 64.5% or, considering katG463 as a marker, 90.3% of the INH-resistant strains. Sequencing of the hot spot region of the rpoB gene will detect 94.3% of the RIF drug-resistant isolates in Ecuador. This is appropriate for fast screening for drug resistance with the GeneXpert MTB/RIF assay or by direct sequencing of a part of the genes katG and rpoB of PCR products obtained from DNA isolation from primary cultures.
adicionar en sua lista

Four new species of Morchella from the Americas.

Baroni, Timothy J; Beug, Michael W; Cantrell, Sharon A; Clements, Teresa A; Iturriaga, Teresa; Læssøe, Thomas; Holgado Rojas, María E; Aguilar, Frank M; Quispe, Miguel O; Lodge, D Jean; O'Donnell, Kerry
| Idioma(s): Inglés
Morphological and molecular phylogenetic studies of true morels (Morchella) in North America, the Dominican Republic, Venezuela, Ecuador, and Peru led to the discovery of four undescribed species of Morchella. Two new species in the Elata clade, one from the Dominican Republic, initially distinguished by the informal designation Mel-18, and a newly discovered sister species from northern Arizona, are now recognized. Mel-18 is described as a novel phylogenetically distinct species, M. hispaniolensis. Its sister species from Arizona is described as M. kaibabensis, also recovered as an endophyte of Rocky Mountain juniper. Two additional species in the Esculenta clade, M. peruviana discovered in Peru and M. gracilis (previously reported as Mes-14) from the Dominican Republic, Venezuela, and Ecuador, are described as new. We also demonstrate that scanning electron microscopy (SEM) imaging of ascospores using rehydration/dehydration/critical point drying preparation techniques provides for enhanced resolution of spore wall surfaces, thereby increasing the number of morphological traits available to assess differences among otherwise closely related species.
Resultados  1-10 de 13.364