Early determinants of acute kidney injury during experimental intra-abdominal sepsis

Indexación: Web of Science; Scielo.Background: Sepsis-induced acute kidney injury (AKI) is an early and frequent organ dysfunction, associated with increased mortality. Aim: To evaluate the impact of macrohemodynamic and microcirculatory changes on renal function and histology during an experimental model of intra-abdominal sepsis. Material and Methods: In 18 anaesthetized pigs, catheters were installed to measure hemodynamic parameters in the carotid, right renal and pulmonary arteries. After baseline assessment and stabilization, animals were randomly divided to receive and intra-abdominal infusion of autologous feces or saline. Animals were observed for 18 hours thereafter. Results: In all septic animals, serum lactate levels increased, but only eight developed AKI (66%). These animals had higher creatinine and interleukin-6 levels, lower inulin and paraaminohippurate clearance (decreased glomerular filtration and renal plasma flow), and a negative lactate uptake. Septic animals with AKI had lower values of mean end arterial pressure, renal blood flow and kidney perfusion pressure, with an associated increase in kidney oxygen extraction. No tubular necrosis was observed in kidney histology. Conclusions: The reduction in renal blood flow and renal perfusion pressure were the main mechanisms associated with AKI, but were not associated with necrosis. Probably other mechanisms, such as microcirculatory vasoconstriction and inflammation also contributes to AKI development. (Rev Med Chile 2014; 142: 551-558) Key words: Acute kidney injury; Renal circulation; Sepsis

Forty years of meteorological records at the Fabio Baudrit Experimental Station

Se examinó el registro histórico de la información meteorológica recolectada en la Estación Experimental por un período de 40 años. La característica más sobresaliente del clima fue la marcada estacionalidad en la distribución de las lluvias durante el ciclo anual, que resultó en el desarrollo de una estación lluviosa y una estación seca bien definidas, diferentes en su patrón de radiación solar, horas de brillo solar, temperatura y humedad relativa del aire, y de evaporación potencial. La velocidad y la dirección del viento también mostraron marcadas diferencias entre la estación seca y la estación lluviosa, influenciadas predominantemente por los vientos alisios de alta velocidad (20 km/h) y los vientos moderados del suroeste, respectivamente. El patrón climático imperante permitió clasificar la EEFBM dentro de la zona de vida correspondiente al bosque húmedo premontano con un clima subhúmedo caliente y una estación seca bien definida (más de 70 días sin lluvia al año) (HOLDRIDGE, 1982).Historical records of meteorological information, collected over a period of 40 years at Fabio Baudrit Experiment Station, were examined. A marked seasonality in rainfall distribution during the annual cycle was the most outstanding feature of climate, which resulted in the development of well defined rainy and dry seasons. These differed in their patterns of solar radiation, hours of sunshine, air temperature and relative humidity, and potential evaporation. Wind velocity and direction also exhibited marked differences between the rainy and dry seasons. The dry season was predominantly influenced by high-velocity trade winds blowing from the northeast, while the rainy season was mostly affected by southern winds blowing at moderate velocities. According to the climatic pattern observed at the Fabio Baudrit Experiment Station, it is classified in the life zone corresponding to the wet, hot, pre-montane forest with a well defined dry season (sensu Holdridge, 1982).UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

The climate at the Fraijanes Experiment Station, in a low and humid montane ecosystem

Se analizó el comportamiento de las principales variables que describen el clima con base en el registro de los datos meteorológicos colectados en la Estación Experimental de Fraijanes (EEF) de la Universidad de Costa Rica, ubicada en la falda sureste del Volcán Poás a una elevación de 1500 msnm. El clima de la EEF se caracteriza por una marcada estacionalidad en la distribución de los 3150 ± 577mm anuales de lluvia, que determina en gran medida el patrón anual de otras variables ambientales importantes para el desarrollo de las plantas y de las actividades agrícolas, tales como la radiación solar, la temperatura y la humedad relativa del aire. La estación seca se extiende de enero a marzo y la lluviosa de mayo a noviembre; abril y diciembre son meses de transición. La estación seca recibe mayor radiación (cerca de 18 MJ día-1) y experimenta más horas de brillo solar diarias (más de 8) y menor humedad atmosférica (cerca del 80%). En contraste, los meses lluviosos reciben menos de 12 MJ diarios de radiación solar, experimentan menos de 4 horas de brillo solar diarias y mayor humedad atmosférica (cerca del 90%). La temperatura promedio del aire es de 16,1 ± 1,1 °C y muestra una escasa variación anual que contrasta con las marcadas fluctuaciones diarias entre un mínimo promedio de 12,9°C y un máximo promedio de 21,4°C. La velocidad del viento también muestra una marcada estacionalidad determinada por la migración anual de la Zona de Convergencia Intertropical. Enero, febrero y marzo son los meses más ventosos en los que la velocidad del viento supera los 10 km h-1, mientras que ésta no sobrepasa los 6 km h-1 durante la estación lluviosa. Las características bioclimáticas descritas anteriormente permiten clasificar la EEF dentro de la zona de vida del bosque húmedo montano bajo, de acuerdo al sistema de clasificación de Holdridge.The meteorological record of climatic data collected at Fraijanes Experiment Station, University of Costa Rica, was examined. The Fraijanes Experiment Station is located on the south-eastern slope of the Poas Volcano, at 1,500 masl. The climate at the Fraijanes Experiment Station is characterized by a strong seasonality in the distribution of 3,150 ± 577 mm of annual rainfall, a pattern that largely determines the annual trend of other environmental variables such as solar radiation and air temperature and humidity, important for the development of plants and agriculture. The dry season spans from Jan. to April, and the rainy season from May to November; April and December are transition months. The dry season receives a higher radiation (ca. 18 MJ day-1), and experiences more daily sunshine hours (over 8) and lower atmospheric humidity (ca. 80%). In contrast, the rainy months receive less than 12 MJ day-1 of solar radiation, and experience less than 4 hours of daily sunshine and higher atmospheric humidity (ca. 90%). Average air temperature is 16.1±1.1°C and exhibits a slight annual variation, which contrasts with the sharp daily fluctuations between a minimum of 12.9 °C and a maximum of 21.4 °C. Wind speed also shows strong seasonality, largely determined by the annual migration of the Inter-Tropical Convergence Zone. January, February and March are windy months in which its speed surpasses 10 Km h-1. In contrast, wind speed does not exceed 6 Km h-1 during the rainy season. The bio-climatic characteristics described above place the Fraijanes Experiment Station within the wet and lower montane forest life zone, according to the Holdridge’s classification scheme.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Validación de un protocolo fotográfico para la digitalización de muestras de herbario de especies tropicales

The study was validated of a photographic protocol for the digitalization of herbarium samples from digital colorimetry analysis. For which ten tree species were used in herbarium condition and belt types of shutter speed, objective aperture and ISO were evaluated in order to identify better fit and then identify the best photographic protocol from the variables L *, a *, b *, color differential (ΔE *) and chroma (ΔC *). The results showed that the shutter speeds of 1/3 ”, 1/5” and 1 ”showed ΔE * less than 5, considered as visible, the aperture of objective f / 5.6 and f / 7.1 showed ΔE * values ​​less than 5 , 5 being better adapted, while in ISO, values ​​100, 200 and 320 showed visible ΔE * values ​​and less than 5.3. As soon as the determination of the best protocol for the 10 species was CP1 with a speed of 1/3 ”, with an aperture of f / 5.5 and ISO 100 that presented an average ΔE * of 4.1 considered as visible and significantly lower than the rest of treatments that varied from 5.1 to 29.8, being changes from visible to total color and evidencing with color accumulations of 6 to 12 (ΔC *). Finally, IRF showed the users perceived that CP1 showed a better fit to the physical material (0.95) with respect to the other protocols (average 0.71).El estudio se validó de un protocolo fotográfico para la digitalización de muestras de herbario a partir de análisis de colorimetría digital. Para lo cual se utilizaron diez especies arbóreas en condición de herbario y se evaluó cinto tipos de velocidad de obturación, apertura de objetivo e ISO con fin identificar mejor ajuste y luego identificar el mejor protocolo fotográfico a partir de las variables L*, a *, b*, diferencial de color (ΔE*) y chroma (ΔC*). Los resultados mostraron que las velocidades de obturación de 1/3”, 1/5” y 1” mostraron ΔE* inferiores a 5, considerados como visibles, la a apertura de objetivo f/ 5.6 y f/7.1 mostraron valores ΔE* menores a 5,5 siendo mejor se adaptaron, mientras en ISO, los valores 100, 200 y 320 presentaron valores ΔE* visibles y menores a 5,3. En cuanto la determinación del mejor protocolo para las 10 especies fue CP1 con una velocidad de 1/3”, con apertura de f/5.5 e ISO 100 que presentó un ΔE* promedio de 4,1 considerado como visible y significativamente menor al resto de los tratamientos que variaron de 5,1 a 29,8, siendo cambios de visibles a totales de color y evidenciando con acumulaciones de color de 6 a 12 (ΔC*). Finalmente, IRF mostró los usuarios percibieron que CP1 mostró mejor ajuste al material físico (0,95) con respeto a los demás protocolos (promedio 0,71)

Extracorporeal membrane oxygenation improves survival in a novel 24-hour pig model of severe acute respiratory distress syndrome

Indexación: Web of Science; Pub Med CentralExtracorporeal membrane oxygenation (ECMO) is increasingly being used to treat severe acute respiratory distress syndrome (ARDS). However, there is limited clinical evidence about how to optimize the technique. Experimental research can provide an alternative to fill the actual knowledge gap. The purpose of the present study was to develop and validate an animal model of acute lung injury (ALI) which resembled severe ARDS, and which could be successfully supported with ECMO. Eighteen pigs were randomly allocated into three groups: sham, ALI, and ALI + ECMO. ALI was induced by a double-hit consisting in repeated saline lavage followed by a 2-hour period of injurious ventilation. All animals were followed up to 24 hours while being ventilated with conventional ventilation (tidal volume 10 ml/kg). The lung injury model resulted in severe hypoxemia, increased airway pressures, pulmonary hypertension, and altered alveolar membrane barrier function, as indicated by an increased protein concentration in bronchoalveolar fluid, and increased wet/dry lung weight ratio. Histologic examination revealed severe diffuse alveolar damage, characteristic of ARDS. Veno-venous ECMO was started at the end of lung injury induction with a flow > 60 ml/kg/min resulting in rapid reversal of hypoxemia and pulmonary hypertension. Mortality was 0, 66.6 and 16.6% in the SHAM, ALI and ALI + ECMO groups, respectively (p < 0.05). This is a novel clinically relevant animal model that can be used to optimize the approach to ECMO and foster translational research in extracorporeal lung support.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4931177

The microclimate of a shadehouse: palms and Zamia as indicators of acclimation to light

Se compararon algunas variables microclimáticas medidas simultáneamente en el interior y en el exterior de una casa de sombra de 720 m2, ubicada en la Estación Experimental Fabio Baudrit Moreno en Barrio San José de Alajuela (840 msnm), construida con un techo compuesto de materiales de sarán que generaron seis regímenes de luz en el interior (40% a 80%). Se utilizaron además nueve especies de palmas y una especie de Zamia como indicadores biológicos de aclimatación a la luz, a las que se les midió el área, el grosor y el contenido foliar de Nitrógeno. Los materiales de sarán cumplieron solo parcialmente con las especificaciones descritas por los fabricantes en cuanto a sus propiedades de intercepción de luz. La temperatura y la humedad relativa del aire en el interior de la casa de sombra no difirieron de los valores registrados en el exterior, lo que sugiere que la modificación de estas variables microclimáticas es importante solo en casas de sarán grandes. En contraste, la temperatura del suelo fue significativamente afectada por el régimen de sombra, lo que resultó en mayores temperaturas absolutas y mayores fluctuaciones diurnas en el suelo expuesto a 40% de intercepción de luz comparado con el de 80%. La distribución espacial de la lluvia también fue alterada significativamente en el interior de la casa de sombra como resultado de la orientación cóncava de la mayoría de los techos. Cuatro de las 10 especies vegetales utilizadas como indicadores de aclimatación a la luz no se establecieron a plena exposición solar, y la mayoría de las especies alcanzaron mayor área foliar a porcentajes de intercepción de luz menores a 70-80%. Se discuten las causas y las implicaciones de los cambios microclimáticos encontrados en las casas de sombra pequeñas, y se recomiendan modificaciones arquitectónicas de las casas de sombra en función de los propósitos del ambiente protegido.Shadehouses are one of the most common types of sheltered environments employed in tropical regions. The microclimatic modifications induced by these structures inside the shadehouse, their effects on the plants grown, and the relation between the architectural and functional characteristics of the shadehouses, remain unexplored. We measured the microclimate inside and out of a shadehouse of 720 m2, built at the Fabio Baudrit Experiment Station, University of Costa Rica. The roof designed with different shade materials created six light regimes inside the tent. We measured specifically: solar radiation, air temperature and humidity, rainfall spatial distribution, and soil temperature at 5, 10 and 15 cm depth. In addition, we evaluated plant acclimation to different light regimes by growing nine palm and a Zamia species under seven light regimes, including the control. The saran materials evaluated in this study complied only partially with the specifications provided by the manufacturers. Air temperature and relative humidity inside the shadehouse did not differ from the outside values, supporting early indications that changes in those variables are important only in large shadehouses. In contrast, soil temperature was significantly affected by the light regimes imposed. Higher values and larger fluctuations of soil temperature were observed at 40% than at 80% shade. Rainfall distribution inside the shadehouse was also significantly modified as a result of the predominantly concave orientation of the saran panels employed in shadehouse construction. Four out of the 10 species used as indicators of acclimation to light were not establish under full sun exposure, and most of the species exhibited their larger leaf area under shade regimes lower than 70-80%. The causes and implications of the environmental features observed inside small shadehouses are discussed, and modifications of the architectural design of shadehouses are proposed.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Cameraria caryaefoliella (Clemens) (Lepidoptera: Gracillariidae) pecan leafminer moth in North of Coahuila, Mexico: Cameraria caryaefoliella (Clemens) (Lepidoptera: Gracillariidae) mineiro de folhas de nogueira no norte de Coahuila, Mexico

El nogal pecanero es uno de los cultivos de gran valor económico en México, con un valor de producción de $12, 896 138 (millones de pesos) en 2022; se cultiva en 20 de los 32 estados de la República mexicana. Coahuila es el segundo estado productor de nuez con dos grandes zonas productoras, la Comarca Lagunera y la Región Norte; en esta última, las principales plagas que se presentan cada ciclo agrícola son Acrobasis nuxvorella (Neunzing) Gusano Barrenador de la Nuez, Carya caryana (Fitch) Gusano Barrenador del Ruezno y Menellia caryella (Fitch) y Monelliopsis pecanis Bissell los pulgones (negro y amarillo); sin embargo, en años recientes se han presentado de manera esporádica organismos que cada vez amplían su distribución, insectos conocidos como plagas emergente, la mayoría invasoras; en el presente trabajo se estudió al minador de la hoja (Cameraria caryaefoliella (Clemens)) plaga invasora, originaria de la Costa Este de los Estados Unidos de América

Capillary refill time response to a fluid challenge or a vasopressor test:an observational, proof-of-concept study

Background: Several studies have validated capillary refill time (CRT) as a marker of tissue hypoperfusion, and recent guidelines recommend CRT monitoring during septic shock resuscitation. Therefore, it is relevant to further explore its kinetics of response to short-term hemodynamic interventions with fluids or vasopressors. A couple of previous studies explored the impact of a fluid bolus on CRT, but little is known about the impact of norepinephrine on CRT when aiming at a higher mean arterial pressure (MAP) target in septic shock. We designed this observational study to further evaluate the effect of a fluid challenge (FC) and a vasopressor test (VPT) on CRT in septic shock patients with abnormal CRT after initial resuscitation. Our purpose was to determine the effects of a FC in fluid-responsive patients, and of a VPT aimed at a higher MAP target in chronically hypertensive fluid-unresponsive patients on the direction and magnitude of CRT response. Methods: Thirty-four septic shock patients were included. Fluid responsiveness was assessed at baseline, and a FC (500 ml/30 mins) was administered in 9 fluid-responsive patients. A VPT was performed in 25 patients by increasing norepinephrine dose to reach a MAP to 80–85 mmHg for 30 min. Patients shared a multimodal perfusion and hemodynamic monitoring protocol with assessments at at least two time-points (baseline, and at the end of interventions).Results: CRT decreased significantly with both tests (from 5 [3.5–7.6] to 4 [2.4–5.1] sec, p = 0.008 after the FC; and from 4.0 [3.3–5.6] to 3 [2.6 -5] sec, p = 0.03 after the VPT. A CRT-response was observed in 7/9 patients after the FC, and in 14/25 pts after tobjehe VPT, but CRT deteriorated in 4 patients on this latter group, all of them receiving a concomitant low-dose vasopressin. Conclusions: Our findings support that fluid boluses may improve CRT or produce neutral effects in fluid-responsive septic shock patients with persistent hypoperfusion. Conversely, raising NE doses to target a higher MAP in previously hypertensive patients elicits a more heterogeneous response, improving CRT in the majority, but deteriorating skin perfusion in some patients, a fact that deserves further research.</p

Equilibrium between Adenylyl Cyclase and Phosphodiesterase Patterns Adrenergic Agonist Dose-Dependent Spatiotemporal cAMP/Protein Kinase A Activities in Cardiomyocytes

ABSTRACT ␤-Adrenergic receptor induces cAMP/Protein kinase A (PKA) activation to regulate cardiac contraction. Using real-time fluorescence resonance energy transfer imaging for highly sensitive detection of cAMP and PKA activities, we show two distinct phases in isoproterenol dose-dependent responses in cardiomyocytes: a transient and dose-dependent increase in cAMP and PKA activities at lower concentrations from 10 Ϫ12 to 10 Ϫ8 M; and a saturated initial increases at higher concentrations from 10 Ϫ8 to 10 Ϫ5 M followed by a rapid decrease to different levels that were later sustained in a dose-dependent manner. The dose-dependent temporal responses are patterned by equilibrium between receptor-activated adenylyl cyclase (AC) and phosphodiesterase (PDE). At lower concentrations, cAMP is produced in an agonist dose-dependent manner with AC as a rate-limiting factor. However, the cAMP activities are confined within local domains for phosphorylation of PDE isoforms in the receptor complex but not for phosphorylation of phospholamban and troponin I. At higher concentrations, isoproterenol promotes a dose-dependent selective dissociation of PDE4D but not ACVI from the receptor complex, which shifts the equilibrium between AC and PDE. This shifted balance leads to sustained cAMP accumulation and diffusion for PKA phosphorylation of phospholamban and troponin I, and for myocyte contraction. Pharmacological inhibition or overexpression of either ACVI or PDE4D8 disrupts the balance and shapes the temporal responses in cAMP accumulation. Together, our data reveal a new paradigm for adrenergic agonist dose-dependent cAMP/PKA activities for substrate-specific phosphorylation dictated by dual regulation of AC and PDE in cardiomyocytes

Impairment of exogenous lactate clearance in experimental hyperdynamic septic shock is not related to total liver hypoperfusion

Introduction: Although the prognostic value of persistent hyperlactatemia in septic shock is unequivocal, its physiological determinants are controversial. Particularly, the role of impaired hepatic clearance has been underestimated and is only considered relevant in patients with liver ischemia or cirrhosis. Our objectives were to establish whether endotoxemia impairs whole body net lactate clearance, and to explore a potential role for total liver hypoperfusion during the early phase of septic shock. Methods: After anesthesia, 12 sheep were subjected to hemodynamic/perfusion monitoring including hepatic and portal catheterization, and a hepatic ultrasound flow probe. After stabilization (point A), sheep were alternatively assigned to lipopolysaccharide (LPS) (5 mcg/kg bolus followed by 4 mcg/kg/h) or sham for a three-hour study period. After 60 minutes of shock, animals were fluid resuscitated to normalize mean arterial pressure. Repeated series of measurements were performed immediately after fluid resuscitation (point B), and one (point C) and two hours later (point D). Monitoring included systemic and regional hemodynamics, blood gases and lactate measurements, and ex-vivo hepatic mitochondrial respiration at point D. Parallel exogenous lactate and sorbitol clearances were performed at points B and D. Both groups included an intravenous bolus followed by serial blood sampling to draw a curve using the least squares method. Results: Significant hyperlactatemia was already present in LPS as compared to sham animals at point B (4.7 (3.1 to 6.7) versus 1.8 (1.5 to 3.7) mmol/L), increasing to 10.2 (7.8 to 12.3) mmol/L at point D. A significant increase in portal and hepatic lactate levels in LPS animals was also observed. No within-group difference in hepatic DO2, VO2 or O2 extraction, total hepatic blood flow (point D: 915 (773 to 1,046) versus 655 (593 to 1,175) ml/min), mitochondrial respiration, liver enzymes or sorbitol clearance was found. However, there was a highly significant decrease in lactate clearance in LPS animals (point B: 46 (30 to 180) versus 1,212 (743 to 2,116) ml/min, P <0.01; point D: 113 (65 to 322) versus 944 (363 to 1,235) ml/min, P <0.01). Conclusions: Endotoxemia induces an early and severe impairment in lactate clearance that is not related to total liver hypoperfusion