Changes of the surface cell of the Atlantic and Indian Meridional overturning circulations

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Current and future variations of nutrient depositions and influences on tree growth

Current nutrient deposition shows episodic variations which likely may impact the local nutrient cycle at the RBSF. Comparing analyses of deposition data during present-day atmospheric circulation and phases of high biomass burning in the Amazon, characteristic relationships between remote emissions and local deposition are determined. By using projections drawn from the special report on emission scenarios (SRES) in combination with a trajectory modeling tool, future nutrient deposition conditions of the mountain ecosystem are assessed. Observations of relations between climatic variables, current time series of nutrient deposition, and tree growth point to an impact of the remote fertilization effect of atmospheric matters, emitted primarily by human activities like biomass burning and agricultural and industrial sources. The increasing emissions in the future may have adverse effects on the ecosystem in the long run.

Dissemination of methicillin-resistant Staphylococcus aureus USA300 sequence type 8 lineage in Latin America.

BACKGROUND: Methicillin-resistant Staphylococus aureus (MRSA) is an important nosocomial and community-associated (CA) pathogen. Recently, a variant of the MRSA USA300 clone emerged and disseminated in South America, causing important clinical problems. METHODS: S. aureus isolates were prospectively collected (2006-2008) from 32 tertiary hospitals in Colombia, Ecuador, Peru, and Venezuela. MRSA isolates were subjected to antimicrobial susceptibility testing and pulsed-field gel electrophoresis and were categorized as health care-associated (HA)-like or CA-like clones on the basis of genotypic characteristics and detection of genes encoding Panton-Valentine leukocidin and staphylococcal cassette chromosome (SCC) mec IV. In addition, multilocus sequence typing of representative isolates of each major CA-MRSA pulsotype was performed, and the presence of USA300-associated toxins and the arcA gene was investigated for all isolates categorized as CA-MRSA. RESULTS: A total of 1570 S. aureus were included; 651 were MRSA (41%)--with the highest rate of MRSA isolation in Peru (62%) and the lowest in Venezuela (26%)--and 71%, 27%, and 2% were classified as HA-like, CA-like, and non-CA/HA-like clones, respectively. Only 9 MRSA isolates were confirmed to have reduced susceptibility to glycopeptides (glycopeptide-intermediate S. aureus phenotype). The most common pulsotype (designated ComA) among the CA-like MRSA strains was found in 96% of isolates, with the majority (81%) having a < or =6-band difference with the USA300-0114 strain. Representative isolates of this clone were sequence type 8; however, unlike the USA300-0114 strain, they harbored a different SCCmec IV subtype and lacked arcA (an indicator of the arginine catabolic mobile element). CONCLUSION: A variant CA-MRSA USA300 clone has become established in South America and, in some countries, is endemic in hospital settings.

Molecular epidemiology of vancomycin-resistant Enterococcus faecium: a prospective, multicenter study in South American hospitals.

Enterococcus faecium has emerged as an important nosocomial pathogen worldwide, and this trend has been associated with the dissemination of a genetic lineage designated clonal cluster 17 (CC17). Enterococcal isolates were collected prospectively (2006 to 2008) from 32 hospitals in Colombia, Ecuador, Perú, and Venezuela and subjected to antimicrobial susceptibility testing. Genotyping was performed with all vancomycin-resistant E. faecium (VREfm) isolates by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. All VREfm isolates were evaluated for the presence of 16 putative virulence genes (14 fms genes, the esp gene of E. faecium [espEfm], and the hyl gene of E. faecium [hylEfm]) and plasmids carrying the fms20-fms21 (pilA), hylEfm, and vanA genes. Of 723 enterococcal isolates recovered, E. faecalis was the most common (78%). Vancomycin resistance was detected in 6% of the isolates (74% of which were E. faecium). Eleven distinct PFGE types were found among the VREfm isolates, with most belonging to sequence types 412 and 18. The ebpAEfm-ebpBEfm-ebpCEfm (pilB) and fms11-fms19-fms16 clusters were detected in all VREfm isolates from the region, whereas espEfm and hylEfm were detected in 69% and 23% of the isolates, respectively. The fms20-fms21 (pilA) cluster, which encodes a putative pilus-like protein, was found on plasmids from almost all VREfm isolates and was sometimes found to coexist with hylEfm and the vanA gene cluster. The population genetics of VREfm in South America appear to resemble those of such strains in the United States in the early years of the CC17 epidemic. The overwhelming presence of plasmids encoding putative virulence factors and vanA genes suggests that E. faecium from the CC17 genogroup may disseminate in the region in the coming years.

Aluminum toxicity in a tropical montane forest ecosystem in southern Ecuador

Aluminum phytotoxicity frequently occurs in acid soils (pH < 5.5) and was therefore discussed to affect ecosystem functioning of tropical montane forests. The susceptibility to Al toxicity depends on the sensitivity of the plant species and the Al speciation in soil solution, which can vary highly depending e.g., on pH, ionic strength, and dissolved organic matter. An acidification of the ecosystem and periodic base metal deposition from Saharan dust may control plant available Al concentrations in the soil solutions of tropical montane rainforests in south Ecuador. The overall objective of my study was to assess a potential Al phytotoxicity in the tropical montane forests in south Ecuador. For this purpose, I exposed three native Al non-accumulating tree species (Cedrela odorata L., Heliocarpus americanus L., and Tabebuia chrysantha (Jacq.) G. Nicholson) to increased Al concentrations (0 – 2400 μM Al) in a hydroponic experiment, I established dose-response curves to estimate the sensitivity of the tree species to increased Al concentrations, and I investigated the mechanisms behind the observed effects induced by elevated Al concentrations. Furthermore, the response of Al concentrations and the speciation in soil solution to Ca amendment in the study area were determined. In a final step, I assessed all major Al fluxes, drivers of Al concentrations in ecosystem solutions, and indicators of Al toxicity in the tropical montane rainforest in Ecuador in order to test for indications of Al toxicity. In the hydroponic experiment, a 10 % reduction in aboveground biomass production occurred at 126 to 376 μM Al (EC10 values), probably attributable to decreased Mg concentrations in leaves and reduced potosynthesis. At 300 μM Al, increased root biomass production of T. chrysantha was observed. Phosphorus concentrations in roots of C. odorata and T. chrysantha were significantly highest in the treatment with 300 μM Al and correlated significantly with root biomass, being a likely reason for stimulated root biomass production. The degree of organic complexation of Al in the organic layer leachate, which is central to plant nutrition because of the high root density, and soil solution from the study area was very high (mean > 99 %). The resulting low free Al concentrations are not likely to affect plant growth, although the concentrations of potentially toxic Al3+ increased with soil depth due to higher total Al and lower dissolved organic matter concentrations in soil solutions. The Ca additions caused an increase of Al in the organic layer leachate, probably because Al3+ was exchanged against the added Ca2+ ions while pH remained constant. The free ion molar ratios of Ca2+:Al3+ (mean ratio ca. 400) were far above the threshold (≤ 1) for Al toxicity, because of a much higher degree of organo-complexation of Al than Ca. High Al fluxes in litterfall (8.8 – 14.2 kg ha−1 yr−1) indicate a high Al circulation through the ecosystem. The Al concentrations in the organic layer leachate were driven by the acidification of the ecosystem and increased significantly between 1999 and 2008. However, the Ca:Al molar ratios in organic layer leachate and all aboveground ecosystem solutions were above the threshold for Al toxicity. Except for two Al accumulating and one non-accumulating tree species, the Ca:Al molar ratios in tree leaves from the study area were above the Al toxicity threshold of 12.5. I conclude that toxic effects in the hydroponic experiment occurred at Al concentrations far above those in native organic layer leachate, shoot biomass production was likely inhibited by reduced Mg uptake, impairing photosynthesis, and the stimulation of root growth at low Al concentrations can be possibly attributed to improved P uptake. Dissolved organic matter in soil solutions detoxifies Al in acidic tropical forest soils and a wide distribution of Al accumulating tree species and high Al fluxes in the ecosystem do not necessarily imply a general Al phytotoxicity.

Birth prevalence of isolated congenital limb reduction defects in Texas 1999--2001

Objective. Congenital limb defects are common birth defects occurring in approximately 2-7/10,000 live births. Because congenital limb defects are pervasive throughout all populations, and the conditions profoundly affect quality of life, they represent a significant public health concern. Currently there is a paucity of etiologic information in the literature regarding congenital limb reduction defects which represents a major limitation in developing treatment strategies as well as identifying high risk pregnancies. ^ Additionally, despite the fact that the majority of congenital limb reduction defects are isolated, most previous studies have not separated them from those occurring as part of a known syndrome or with multiple additional congenital anomalies of unknown etiology. It stands to reason that factors responsible for multiple congenital anomalies that happen to include congenital limb reduction defects may be quite different from those factors leading to an isolated congenital limb reduction defect. ^ As a first step toward gaining etiologic understanding, this cross-sectional study was undertaken to determine the birth prevalence and obtain demographic information about non-syndromic (isolated) congenital limb reduction defects that occurred in Texas from 1999-2001. ^ Methods. The study population included all infants/fetuses with isolated congenital limb reduction defects born in Texas during 1999-2001; the comparison population was all infants who were born to mothers who were residents of Texas during the same period of time. The overall birth prevalence of limb reduction defects was determined and adjusted for ethnicity, gender, site of defect (upper limb versus lower limb), county of residence, maternal age and maternal education. ^ Results. In Texas, the overall birth prevalence of isolated CLRDs was 2.1/10,000 live births (1.5 and 0.6/10,000 live births for upper limb and lower limb, respectively). ^ The risk of isolated lower limb CLRDs in Texas was significantly lower in females when gender was examined individually (crude prevalence odds ratio of 0.57, 95% CI of 0.36-0.91) as well as in relation to all other variables used in the analysis (adjusted prevalence odds ratio of 0.58, 95% CI of 0.36-0.93). ^ Harris County (which includes the Houston metropolitan area) had significantly lower risks of all (upper limb and lower limb combined) isolated CLRDs when examined in relation to other counties in Texas, with a crude prevalence odds ratio of 0.4 (95% CI: 0.29-0.72) and an adjusted prevalence odds ratio of 0.50 (95% CI: 0.31-0.80). The risk of isolated upper limb CLRDs was significantly lower in Harris County (crude prevalence odds ratio of 0.45, CI of 0.26-0.76 and adjusted prevalence odds ratio of 0.49, CI of 0.28-0.84). This trend toward decreased risk in Harris County was not observed for isolated lower limb reduction defects (adjusted prevalence odds ratio of 0.50, 95% confidence interval: 0.22-1.12). ^ Conclusions. The birth prevalence of isolated congenital limb reduction defects in Texas is in the lower limits of the range of rates that have been reported by other authors for other states (Alabama, Arkansas, California, Georgia, Hawaii, Iowa, Maryland, Massachusetts, North Carolina, Oklahoma, Utah, Washington) and other countries (Argentina, Australia, Austria, Bolivia, Brazil, Canada, Chile, China, Colombia, Costa Rica, Croatia, Denmark, Ecuador, England, Finland, France, Germany, Hungary, Ireland, Israel, Italy, Lithuania, Mexico, Norway, Paraguay, Peru, Spain, Scotland, Sweden, Switzerland, Uruguay, and Venezuela). In Texas, the birth prevalence of isolated congenital lower limb reduction defects was greater for males than females, while the birth prevalence of isolated congenital upper limb reduction defects was not significantly different between males and females. The reduced rates of limb reduction defects in Harris County warrant further investigation. This study has provided an important first step toward gaining etiologic understanding in the study of isolated congenital limb reduction defects. ^

Disputa de Proyectos en Ecuador : El Hecho Social del 30 de Septiembre de 2010

El hecho social estudiado en este trabajo es lo ocurrido el 30 de Septiembre del año 2010 en Ecuador, cuando un sector de las fuerzas armadas y de la policía realizan una protesta en contra de la Ley de Servicio Público. Esta protesta fue acompañada, entre otras, por un conjunto de acciones que incluyeron la retención del presidente Rafael Correa por más de 10 horas en el hospital policial, distintos hechos delictivos en varios puntos del país, la toma del Aeropuerto de Quito, el intento de tomar los medios de comunicación públicos. Ante esto, se produjo una importante y rápida repercusión a nivel internacional y especialmente desde Latinoamérica. A lo largo del trabajo, se analizará cómo intervienen y se posicionan ante el hecho distintos actores nacionales e internacionales, políticos, sociales, culturales y económicos, lo cual permitirá reconstruir los intereses en juego, la disputa de proyectos y los conflictos de intereses latentes no sólo en Ecuador, sino en toda la región Latinoamérica. El análisis que se realiza en este trabajo se hace a partir de la construcción de una base de datos de medios gráficos argentinos (Clarín, La Nación, Página 12, Perfil), ecuatorianos (Diario Hoy, Diario Popular, El Universo, El Telégrafo) y latinoamericanos como Telesur y con un marco teórico desarrollado a partir de la bibliografía. Desde los Medios Masivos de Comunicación, así como distintos actores, fueron considerando lo ocurrido como una sublevación policial, un intento de golpe de estado o un autogolpe. Esto es lo que se reconstruirá a lo largo del trabajo

Disputa de Proyectos en Ecuador : El Hecho Social del 30 de Septiembre de 2010

El hecho social estudiado en este trabajo es lo ocurrido el 30 de Septiembre del año 2010 en Ecuador, cuando un sector de las fuerzas armadas y de la policía realizan una protesta en contra de la Ley de Servicio Público. Esta protesta fue acompañada, entre otras, por un conjunto de acciones que incluyeron la retención del presidente Rafael Correa por más de 10 horas en el hospital policial, distintos hechos delictivos en varios puntos del país, la toma del Aeropuerto de Quito, el intento de tomar los medios de comunicación públicos. Ante esto, se produjo una importante y rápida repercusión a nivel internacional y especialmente desde Latinoamérica. A lo largo del trabajo, se analizará cómo intervienen y se posicionan ante el hecho distintos actores nacionales e internacionales, políticos, sociales, culturales y económicos, lo cual permitirá reconstruir los intereses en juego, la disputa de proyectos y los conflictos de intereses latentes no sólo en Ecuador, sino en toda la región Latinoamérica. El análisis que se realiza en este trabajo se hace a partir de la construcción de una base de datos de medios gráficos argentinos (Clarín, La Nación, Página 12, Perfil), ecuatorianos (Diario Hoy, Diario Popular, El Universo, El Telégrafo) y latinoamericanos como Telesur y con un marco teórico desarrollado a partir de la bibliografía. Desde los Medios Masivos de Comunicación, así como distintos actores, fueron considerando lo ocurrido como una sublevación policial, un intento de golpe de estado o un autogolpe. Esto es lo que se reconstruirá a lo largo del trabajo

Disputa de Proyectos en Ecuador : El Hecho Social del 30 de Septiembre de 2010

El hecho social estudiado en este trabajo es lo ocurrido el 30 de Septiembre del año 2010 en Ecuador, cuando un sector de las fuerzas armadas y de la policía realizan una protesta en contra de la Ley de Servicio Público. Esta protesta fue acompañada, entre otras, por un conjunto de acciones que incluyeron la retención del presidente Rafael Correa por más de 10 horas en el hospital policial, distintos hechos delictivos en varios puntos del país, la toma del Aeropuerto de Quito, el intento de tomar los medios de comunicación públicos. Ante esto, se produjo una importante y rápida repercusión a nivel internacional y especialmente desde Latinoamérica. A lo largo del trabajo, se analizará cómo intervienen y se posicionan ante el hecho distintos actores nacionales e internacionales, políticos, sociales, culturales y económicos, lo cual permitirá reconstruir los intereses en juego, la disputa de proyectos y los conflictos de intereses latentes no sólo en Ecuador, sino en toda la región Latinoamérica. El análisis que se realiza en este trabajo se hace a partir de la construcción de una base de datos de medios gráficos argentinos (Clarín, La Nación, Página 12, Perfil), ecuatorianos (Diario Hoy, Diario Popular, El Universo, El Telégrafo) y latinoamericanos como Telesur y con un marco teórico desarrollado a partir de la bibliografía. Desde los Medios Masivos de Comunicación, así como distintos actores, fueron considerando lo ocurrido como una sublevación policial, un intento de golpe de estado o un autogolpe. Esto es lo que se reconstruirá a lo largo del trabajo