Phosphorylation and subcellular localization of Na+/H+ exchanger isoform 3 (NHE3) are associated with altered gallbladder absorptive function after formation of cholesterol gallstones

Na+/H+ exchanger isoform 3 (NHE3) dysfunction is thought to contribute to the altered gallbladder absorption that occurs in cholesterol gallstone disease, but the mechanism is unknown. The current study was undertaken to examine the expression, phosphorylation, and subcellular localization of NHE3 in gallbladder epithelium cells (GBECs) of male C57BL/6 mice on a control or lithogenic diet. Thirty-six 8-week-old male C57BL/6 mice were randomly assigned to receive a high cholesterol diet or a regular diet for 8 weeks. Gallstone formation was recorded. Gallbladder bile cholesterol, phospholipid, and total bile acids were examined. RT-PCR was used to measure NHE3 mRNA expression. NHE3 protein expression and subcellular localization were examined by Western blotting and immunofluorescence microscopy, respectively. Gallstones were formed in all mice fed the lithogenic diet. Despite higher NHE3 mRNA expression in gallbladders of the mice on the lithogenic diet than in those on the control diet, there was no significant difference in expression of total NHE3 protein. However, a higher level of NHE3 phosphorylated at serine-552 (P-NHE3) was seen on the lithogenic diet. In immunofluorescence studies, NHE3 protein was expressed both on the apical membrane and in the cytoplasm of mouse GBEC. This pattern of subcellular distribution of NHE3 strongly corroborates an exchanger trafficking mechanism in NHE3 activity regulation in mouse GBEC. We conclude that increased phosphorylation of NHE3 following gallstone formation leads to turnover of the exchanger, resulting in decreased gallbladder concentrating function (AU)

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Finding new solutions in pediatric parenteral admixtures; how to improve quality and to deal with shortages / Encontrando nuevas soluciones en las mezclas parenterales pediatricas; ¿cómo mejorar la calidad y gestionar el desabastecimiento?

Introduction: Pediatric parenteral nutrition enables normal growth even of preterm infants. Those children require, however, tailored parenteral nutrition and the creation of such can be challenging due to the risk of instability and shortages. Objective: Prototypical parenteral admixtures were created using different calcium salts (organic and inorganic) and different lipid emulsions and tested for stability. 36 of parenteral admixtures containing two types of calcium salts: chloride or gluconolactobionate and different lipid emulsions (SMOFlipid® or Lipofundin MCT/LCT®) were under investigation. Methods: Preliminary admixtures were prepared in two-chamber bags whereas lipid emulsions were placed separately in the second chamber. Pre-admixtures were stored for up to 21 days at +4ºC. Contents of the two chambers were combined at t = 0 or after 21 days of storage. Physical analysis of completed admixtures (visual inspection, microscopic observation, pH measurement and determination of the size distribution of oily droplets) was carried out after 21 days of the storage. Stability of lipid, commercial emulsions stored in ethylene vinyl acetate (EVA) bags for 42 days was also studied. Results: Irrespectively of the time of storage of preadmixtures and type of calcium salt and different lipid emulsions among 36 total parenteral admixtures only one showed signs of destabilization after preparation and one was unstable when stored for longer than 14 days. All other formulations were qualified to be stable during the study. All investigated commercial lipid emulsions were physically stable in EVA bags even when stored at room temperature. Conclusion: The study proved that it was possible to store pre-admixture in EVA bags for 21 days at 4°C as well as that CAN (critical aggregation number) and CaxP (the products of multiplication of calcium and phosphate ions concentration) should not be used as reliable indicators of admixture physical stability. No influence of the type of calcium salts on stability of admixtures was observed (AU)

Introducción: La nutrición parenteral pediátrica permite un crecimiento normal incluso en lactantes pretérmino. Sin embargo, estos niños requieren una nutrición parenteral a medida y la formulación de tal nutrición puede suponer un reto por el riesgo de inestabilidad y el desabastecimiento. Objetivo: Se crearon mezclas parenterales prototípicas utilizando diferentes sales de calcio (orgánicas e inorgánicas) y diferentes emulsiones lipídicas probando su estabilidad. Se investigaron 36 mezclas parenterales que contenían dos tipos de sales de calcio (cloruro o gluconolactobionato) y diferentes emulsiones lipídicas (SMOFlipid® o Lipofundin MCT/LCT®). Métodos: Se prepararon unas pre-mezclas en bolsas bicompartimentales mientras que las emulsiones lipídicas se colocaron de forma separada en la segunda cámara. Las pre-mezclas se almacenaron hasta 21 días a +4º C. Se combinaron los contenidos de ambas cámaras en t = 0 o después de 21 días de almacenamiento. El análisis físico de las mezclas completadas (inspección visual, observación microscópica, medición del pH y determinación de la distribución por tamaño de las gotitas lipídicas) se realizó a los 21 días de almacenamiento. También se estudió la estabilidad de las emulsiones lipídicas almacenadas en bolsas comerciales de acetato de etilen vinilo (AEV) durante 42 días. Resultados: Independientemente del tiempo de almacenamiento de las pre-mezclas y el tipo de sal de calcio y de las diferentes emulsiones lipídicas de entre el total de 36 mezclas parenterales, sólo en una se vieron signos de desestabilización tras la preparación y una fue inestable cuando se almacenó más de 14 días. El resto de las formulaciones se consideraron estables durante el estudio. Todas las emulsiones lipídicas comerciales investigadas fueron estables físicamente en las bolsas de AEV, incluso cuando se almacenaron a temperatura ambiente. Conclusión: El estudio mostró que es posible almacenar pre-mezclas en bolsas de AEV durante 21 días a 4° C. También se vio que el NAC (número de agregación crítica) y el CaxP (los productos de la multiplicación de las concentraciones de los iones calcio y fósforo) no deberían utilizarse como indicadores fiables de la estabilidad física de las mezclas. No se observó ninguna influencia del tipo de sal de calcio sobre la estabilidad de las mezclas (AU)