Effect of various dietary fructose concentrations on the gallstone formation process in mice / Efecto de diversas concentraciones de fructosa dietética en el proceso de formación de cálculos biliares en ratones

Background: little information is availaible on the effect of fructose on bile lipids. The first stage in the formation of gallstones corresponds tobiliary cholesterol crystallization, derived from the vesicular transporters. The aim of this study was to investigate the influence of consumingdiets with different fructose concentrations on serum lipids and their implications on gallstones formation. Methods: BALB/c mice divided into a control group as well as groups were treated with different fructose concentrations (10 %, 30 %, 50 % or70 %) for different periods (1, 2 or 5 months). Blood, liver and bile samples were obtained. In bile samples, cholesterol and phospholipids levelswere analyzed, and cholesterol transporters (vesicles and micelles) were separated by gel filtration chromatography. Results: treated animals showed: 1) increases in body weight similar to the control group; 2) a significant increase in plasma triglycerides only atvery high fructose concentrations; 3) a significant increase in total serum cholesterol in the treatment for 1 month; 4) no variations in HDL-cho-lesterol; 5) a significant increase in serum glucose only at very high fructose concentrations in the second month of treatment; 6) no differencesin the plasma alanine-aminotransferase activity; 7) a significant increase in liver triglyceride levels only at very high fructose concentrations; 8)no change in biliary lipid concentrations or in micellar and vesicular phospholipids.Conclusion: changes in plasma, liver and bile lipids were only observed at very high fructose concentrations diets. We conclude that fructoseapparently does not alter the gallstone formation process in our experimental model.(AU)

Introducción: se dispone de escasa información sobre el efecto de la fructosa sobre los lípidos biliares. La primera etapa en la formación decálculos biliares corresponde a la cristalización del colesterol biliar, derivado de los transportadores vesiculares. El objetivo de este estudio fueinvestigar la influencia del consumo de dietas con diferentes concentraciones de fructosa en los lípidos séricos y sus implicaciones en el procesode formación de cálculos biliares.Métodos: ratones BALB/c fueron tratados con diferentes concentraciones de fructosa (10 %, 30 %, 50 % o 70 %) durante diferentes períodos(1, 2 o 5 meses). Se obtuvieron muestras de sangre, hígado y bilis. En muestras de bilis se analizaron los niveles de colesterol y fosfolípidos, ylos transportadores de colesterol (vesículas y micelas) se separaron mediante cromatografía de filtración en gel.Resultados: los animales tratados mostraron: 1) aumentos en el peso corporal similares al grupo de control; 2) aumento significativo en lostriglicéridos plasmáticos sólo a concentraciones muy altas de fructosa; 3) aumento significativo del colesterol sérico total en el tratamientodurante 1 mes; 4) ninguna variación en los niveles de HDL-colesterol; 5) aumento significativo en glucosa sérica solo a concentraciones muyaltas de fructosa; 6) ninguna diferencia en la actividad de la alanina-aminotransferasa plasmática; 7) aumento significativo en los niveles detriglicéridos hepáticos sólo a concentraciones muy altas de fructosa; 8) ningún cambio en las concentraciones de lípidos biliares o en los fos-folípidos micelares y vesiculares.Conclusión: se observaron cambios en los lípidos plasmáticos, hígado y bilis sólo en dietas con concentraciones muy altas de fructosa. Con-cluimos que la fructosa aparentemente no altera el proceso de formación de cálculos biliares en nuestro modelo experimental.(AU)

Effect of various dietary fructose concentrations on the gallstone formation process in mice.

Introduction: Background: little information is availaible on the effect of fructose on bile lipids. The first stage in the formation of gallstones corresponds to biliary cholesterol crystallization, derived from the vesicular transporters. The aim of this study was to investigate the influence of consuming diets with different fructose concentrations on serum lipids and their implications on gallstones formation. Methods: BALB/c mice divided into a control group as well as groups were treated with different fructose concentrations (10 %, 30 %, 50 % or 70 %) for different periods (1, 2 or 5 months). Blood, liver and bile samples were obtained. In bile samples, cholesterol and phospholipids levels were analyzed, and cholesterol transporters (vesicles and micelles) were separated by gel filtration chromatography. Results: treated animals showed: 1) increases in body weight similar to the control group; 2) a significant increase in plasma triglycerides only at very high fructose concentrations; 3) a significant increase in total serum cholesterol in the treatment for 1 month; 4) no variations in HDL-cholesterol; 5) a significant increase in serum glucose only at very high fructose concentrations in the second month of treatment; 6) no differences in the plasma alanine-aminotransferase activity; 7) a significant increase in liver triglyceride levels only at very high fructose concentrations; 8) no change in biliary lipid concentrations or in micellar and vesicular phospholipids. Conclusion: changes in plasma, liver and bile lipids were only observed at very high fructose concentrations diets. We conclude that fructose apparently does not alter the gallstone formation process in our experimental model.

Introducción: Introducción: se dispone de escasa información sobre el efecto de la fructosa sobre los lípidos biliares. La primera etapa en la formación de cálculos biliares corresponde a la cristalización del colesterol biliar, derivado de los transportadores vesiculares. El objetivo de este estudio fue investigar la influencia del consumo de dietas con diferentes concentraciones de fructosa en los lípidos séricos y sus implicaciones en el proceso de formación de cálculos biliares. Métodos: ratones BALB/c fueron tratados con diferentes concentraciones de fructosa (10 %, 30 %, 50 % o 70 %) durante diferentes períodos (1, 2 o 5 meses). Se obtuvieron muestras de sangre, hígado y bilis. En muestras de bilis se analizaron los niveles de colesterol y fosfolípidos, y los transportadores de colesterol (vesículas y micelas) se separaron mediante cromatografía de filtración en gel. Resultados: los animales tratados mostraron: 1) aumentos en el peso corporal similares al grupo de control; 2) aumento significativo en los triglicéridos plasmáticos sólo a concentraciones muy altas de fructosa; 3) aumento significativo del colesterol sérico total en el tratamiento durante 1 mes; 4) ninguna variación en los niveles de HDL-colesterol; 5) aumento significativo en glucosa sérica solo a concentraciones muy altas de fructosa; 6) ninguna diferencia en la actividad de la alanina-aminotransferasa plasmática; 7) aumento significativo en los niveles de triglicéridos hepáticos sólo a concentraciones muy altas de fructosa; 8) ningún cambio en las concentraciones de lípidos biliares o en los fosfolípidos micelares y vesiculares. Conclusión: se observaron cambios en los lípidos plasmáticos, hígado y bilis sólo en dietas con concentraciones muy altas de fructosa. Concluimos que la fructosa aparentemente no altera el proceso de formación de cálculos biliares en nuestro modelo experimental.

Sublethal effect of the toxic dinoflagellate Karlodinium veneficum on early life stages of zebrafish (Danio rerio).

Dinoflagellates of the genus Karlodinium are ichthyotoxic species that produce toxins including karlotoxins and karmitoxins. Karlotoxins show hemolytic and cytotoxic activities and have been associated with fish mortality. This study evaluated the effect of toxins released into the environment of Karlodinium veneficum strain K10 (Ebro Delta, NW Mediterranean) on the early stages of Danio rerio (zebrafish). Extracts of the supernatant of K10 contained the mono-sulfated KmTx-10, KmTx-11, KmTx-12, KmTx-13, and a di-sulfated form of KmTx-10. Total egg mortality was observed for karlotoxin concentration higher than 2.69 µg L-1. For 1.35 µg L-1, 87% of development anomalies were evidenced (all concentrations were expressed as KmTx-2 equivalent). Larvae of 8 days postfertilization exposed to 1.35 µg L-1 presented epithelial damage with 80% of cells in the early apoptotic stage. Our results indicate that supernatants with low concentration of KmTxs produce both lethal and sublethal effects in early fish stages. Moreover, apoptosis was induced at concentrations as low as 0.01 µg L-1. This is of great relevance since detrimental long-term effects due to exposure to low concentrations of these substances could affect wild and cultured fish.

Cell-specific expression of functional glucose transporter 8 in mammary gland.

Differentiated mammary epithelial cells are responsible for milk synthesis during lactation, supporting early postnatal life in mammals. These cells are found in the terminal alveoli of a secretory epithelium, which is surrounded by myoepithelial cells and a stroma rich in fatty tissue. The aim of this study was to explore the cell-specific expression of the glucose transporter GLUT8 in mammary gland and evaluate its functionality for glucose transport, in order to confirm its role in lactose synthesis. Our histological results revealed that GLUT8 is expressed in adipocytes and the epithelial and myoepithelial cells in mammary gland, with a predominant intracellular granular pattern. Colocalization studies of endogenous and green fluorescent protein fused GLUT8 revealed their expressions in lysosome and Golgi, respectively, with Pearson's coefficient correlations of 0.82 ± 0.05 and 0.68 ± 0.16. Functional studies of dileucine to dialanine mutant of GLUT8 showed a fructose-sensitive 2-deoxy glucose uptake at a rate of 83.3 pmoles/(min∗106 cells), 7 folds over empty vector, with a 60 ± 4 and 72 ± 6% decline in 2-deoxy glucose in the presence of 20 and 50 mM fructose, respectively. We concluded that functional GLUT8 is expressed in mammary gland, localizing in mammary epithelial and myoepithelial cells, and adipocytes. In lactation, GLUT8 is expressed mainly in luminal epithelial cells, at the compartments of the endomembrane system. It is necessary to explore the physiological/pathological functions of GLUT8 in mammary gland, including its role in lactation.

Efecto de una dieta alta en grasas en el proceso de formación de cálculos biliares de colesterol / Effect of a high-fat diet on cholesterol gallstone formation

Background: It is known that some nutrients play an important role in the development of cholelithiasis. Cholesterol is carried by micelles and vesicles in the bile. During the first stage of gallstone formation, cholesterol crystals derive from thermodynamically unstable vesicles. Aim: To determine the effect of a high fat diet on blood lipids and bile composition, and its implication in the formation of gallstones. Material and Methods: Two groups of 15 BALB/c mice each, coming from the same litter, were treated with a control or with a high-fat diet (64% fat and 0.14% cholesterol). After two months, the animals were sacrificed, blood and bile samples were obtained. Serum glucose and the corresponding lipid profiles were measured. In bile samples, cholesterol and phospholipid levels were analyzed, and cholesterol transporters (vesicles and micelles) were separated by gel filtration chromatography. Results: Treated animals showed an 87% increase in serum total cholesterol (p < 0.01), a 97% increase in HDL-cholesterol (p < 0.05) and a 140% increase in LDL-cholesterol (p < 0.05). No changes in serum triglycerides or glucose were observed. In bile, a 13% increase in biliary cholesterol (p < 0.05) was observed but no change in biliary phospholipids. Also, an increase in biliary vesicular transporters and an increase of cholesterol/phospholipid ratio in vesicular transporters were observed. Conclusions: A high fat diet may contribute to the formation of gallstones in our experimental model.

[Effect of a high-fat diet on cholesterol gallstone formation]. / Efecto de una dieta alta en grasas en el proceso de formación de cálculos biliares de colesterol.

BACKGROUND: It is known that some nutrients play an important role in the development of cholelithiasis. Cholesterol is carried by micelles and vesicles in the bile. During the first stage of gallstone formation, cholesterol crystals derive from thermodynamically unstable vesicles. AIM: To determine the effect of a high fat diet on blood lipids and bile composition, and its implication in the formation of gallstones. MATERIAL AND METHODS: Two groups of 15 BALB/c mice each, coming from the same litter, were treated with a control or with a high-fat diet (64% fat and 0.14% cholesterol). After two months, the animals were sacrificed, blood and bile samples were obtained. Serum glucose and the corresponding lipid profiles were measured. In bile samples, cholesterol and phospholipid levels were analyzed, and cholesterol transporters (vesicles and micelles) were separated by gel filtration chromatography. RESULTS: Treated animals showed an 87% increase in serum total cholesterol (p < 0.01), a 97% increase in HDL-cholesterol (p < 0.05) and a 140% increase in LDL-cholesterol (p < 0.05). No changes in serum triglycerides or glucose were observed. In bile, a 13% increase in biliary cholesterol (p < 0.05) was observed but no change in biliary phospholipids. Also, an increase in biliary vesicular transporters and an increase of cholesterol/phospholipid ratio in vesicular transporters were observed. CONCLUSIONS: A high fat diet may contribute to the formation of gallstones in our experimental model.

[Effects of vitamin C administration on cholesterol gallstone formation]. / Efecto de la ingesta de vitamina C en el proceso de formación de cálculos biliares de colesterol.

BACKGROUND: Biliary cholesterol is transported by vesicles and micelles. Cholesterol microcrystals are derived from thermodynamically unstable vesicles. In experimental animals vitamin C deficiency leads to a super-saturation of biliary cholesterol and to the formation of gallstones. AIM: To search for a possible relationship between serum levels of vitamin C and the formation of cholesterol gallstones in patients with cholelithiasis. MATERIAL AND METHODS: Thirteen patients with cholelithiasis and a programmed surgical intervention were treated with 2 g/day of vitamin C per os for two weeks before surgery. Forty nine patients subjected to a cholecystectomy not supplemented with vitamin C were studied as controls. Plasma concentrations of vitamin C and lipid profiles were measured. The cholesterol saturation index, crystallization time, cholesterol and phospholipid content in vesicles and micelles, separated by gel filtration chromatography, were studied in bile samples obtained from the gallbladder. RESULTS: Vitamin C supplementation did not change significantly plasma lipids and bile lipid concentrations. However, in supplemented patients, significant reductions in vesicular cholesterol content (6.5 ± 4.8% compared to 17.9 ± 14.0% in the control group; p < 0.05) and vesicular cholesterol/phospholipid ratio (0.71 ± 0.53 compared to 1.36 ± 1.15 in controls; p < 0.05), were observed. CONCLUSIONS: Vitamin C administration may modify bile cholesterol crystallization process, the first step in cholesterol gallstone formation.

Efecto de la ingesta de vitamina C en el proceso de formación de cálculos biliares de colesterol / Effects of vitamin C administration on cholesterol gallstone formation

Background: Biliary cholesterol is transported by vesicles and micelles. Cholesterol microcrystals are derived from thermodynamically unstable vesicles. In experimental animals vitamin C deficiency leads to a super-saturation of biliary cholesterol and to the formation of gallstones. Aim: To search for a possible relationship between serum levels of vitamin C and the formation of cholesterol gallstones in patients with cholelithiasis. Material and Methods: Thirteen patients with cholelithiasis and a programmed surgical intervention were treated with 2 g/day of vitamin C per os for two weeks before surgery. Forty nine patients subjected to a cholecystectomy not supplemented with vitamin C were studied as controls. Plasma concentrations of vitamin C and lipid profiles were measured. The cholesterol saturation index, crystallization time, cholesterol and phospholipid content in vesicles and micelles, separated by gel filtration chromatography, were studied in bile samples obtained from the gallbladder. Results: Vitamin C supplementation did not change significantly plasma lipids and bile lipid concentrations. However, in supplemented patients, significant reductions in vesicular cholesterol content (6.5 ± 4.8% compared to 17.9 ± 14.0% in the control group; p < 0.05) and vesicular cholesterol/phospholipid ratio (0.71 ± 0.53 compared to 1.36 ± 1.15 in controls; p < 0.05), were observed. Conclusions: Vitamin C administration may modify bile cholesterol crystallization process, the first step in cholesterol gallstone formation.