Global data set of long-term summertime vertical temperature profiles in 153 lakes.

Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of lake thermal structure in a time of rapid global and ecological change.

Deeper waters are changing less consistently than surface waters in a global analysis of 102 lakes.

Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970-2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade-1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m-3 decade-1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade-1), but had high variability across lakes, with trends in individual lakes ranging from - 0.68 °C decade-1 to + 0.65 °C decade-1. The variability in deepwater temperature trends was not explained by trends in either surface water temperatures or thermal stability within lakes, and only 8.4% was explained by lake thermal region or local lake characteristics in a random forest analysis. These findings suggest that external drivers beyond our tested lake characteristics are important in explaining long-term trends in thermal structure, such as local to regional climate patterns or additional external anthropogenic influences.

Ecology under lake ice.

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

Pancreatitis post CPRE: efectividad de un bolo de somatostatina en la prevención de pancreatitis después de pancreatografía endoscópica: resultados de un estudio aleatorizado

El objetivo del presente estudio fue demostrar si un bolo único de somatostatina natural a una dosis de 4 mg/kg de peso corporal es útil en prevenir la aparición de pancreatitis clínicamente significativa después de la obtención de un pancreatograma endoscópico. Basados en que la somatostatina inhibe la secreción exocrina pancreática por suprimir la liberación de secretina y colecistokinina, además de reducir la presión pancreática intraductal por reducir la motilidad del esfínter de Oddi. El deseño del estudio fue aleatorizado, y doble ciego controlado con placebo. Se estudiaron 192 pacientes de los cuales 160 se consiguió una opacificación completa del ducto pancreático; 80 recibieron placebo y 80 con somatostatina. La somatostatina fue administrada por vía IV al tener la papila enfrente e inmediatamente antes de iniciar el proceso de canulación. Los grupos fueron comparables en edad, sexo, diagnóstico final, peso corporal, duración total del procedimiento y tiempo de canulación y opacificación del ducto después de la inyección del bolo de somatostatina o placebo. Se presentaron 10 episodios de pancreatitis clínicamente significativa definida por la aparición simultánea de dolor abdominal superior, náuseas y/o vómito, íleo de al menos 18 horas e hiperamilasemía/hiperlipasemia de al menos 3 veces el límite superior normal, requiriendo una prolongación en la estancia hospitalaria, 8 en el grupo placebo y 2 en el somatostatina (p<0.05). Un total de 105 procedimientos fueron diagnósticos y en este subgrupo de pacientes no hubo diferencias significativas en la ocurrencia de pancreatitis (2 en los que recibieron somatostatina y 3 en el grupo placebo). De los 55 pacientes en quien se realizó una esfinterotomía hubo 5 episodios de pancreatitis en el grupo placebo (27 ptes) comparado con ninguno en el grupo de somatotatina (p<0.05). Los autores concluyen que la administración de un solo bolo de somatostatina natural justo antes de canular la papila puede ser útil en prevenir la ocurrencia de pancreatitis en pacientes sometidos a papilotomía endoscópica; se requieren estudios adicionales para determinar si esta droga es útil en casos canulación difícil o cuando hay una prolongada y vigorosa manipulación de la papila