Cholesterol metabolism. Its regulation at the hepatic and intestinal level

Aunque todas las células del organismo tienen capacidad para sintetizar colesterol, la mayor parte de la síntesis de éste, que da lugar a lo que se conoce como colesterol endógeno, se realiza en el hígado. El hepatocito tiene además capacidad de captar colesterol de las lipoproteínas circulantes, y a la vez de excretarlo formando parte de nuevas lipoproteínas de origen hepático o transformado en ácidos biliares. El colesterol de origen extrahepático procede principalmente de la mucosa intestinal. Aquí se realiza la absorción del colesterol de la dieta (colesterol exógeno), la biosíntesis de nuevo colesterol y la esterificación para ser almacenado en la célula o secretado a sangre en las lipoproteínas de origen intestinal. A nivel celular, la importancia del colesterol radica en que forma parte de la mayoría de las estructuras membranosas de todas las células del organismo. En este artículo se revisan algunos de estos aspectos del metabolismo del colesterol, y se analiza la influencia de la composición lipídica de un tipo de membranas celulares, las membranas microsomales, en la actividad de los enzimas reguladores del metabolismo de colesterol.Although all the cells in the body are able to form cholesterol, most part of this synthesis, leading to which is called endogenous cholesterol, occurs in the liver. Hepatocytes can also obtain cholesterol from the plasma lipoproteins. At the same time, cholesterol is either secreted from the liver in new plasma lipoproteins or transformed in bile acids. The extrahepatic cholesterol is mainly produced in the intestinal mucosa. In the site, it takes place the absorption of cholesterol from the diet (exogenous cholesterol), along with the biosynthesis of new cholesterol and the esterification of the molecule to be stored in the cell or secreted as plasma lipoproteins. At the cellular level, the importance of cholesterol comes from the fact that many of the membranous structures of all cells are partially composed of these substance. In this article some of these aspects of the colesterol metabolism are reviewed. We also describe the influence of lipid composition of microsomal membranes on the activity of colesterol metabolism regulating enzymes

Taurocholate transport by brush border membrane vesicles from different regions of chicken intestine

Taurocholate transport was studied in brush border membrane vesicles (BBMV) isolated from chicken small (duodenum, jejunum, and ileum) and large (proximal cecum and rectum) intestines, using a rapid filtration technique. The purity of the BBMV was verified by the finding that the specific activity of sucrase (a brush border membrane enzyme marker) was severalfold greater in vesicles than corresponding values in mucosal homogenate. The functional integrity of isolated BBMV was evaluated by the uptake of D-glucose, which showed a transient increase in the presence of Na+. A Na+-dependence of taurocholate uptake was shown in BBMV prepared from ileum, cecum, and rectum, as taurocholate transport was transiently increased (accumulation) in the presence of a Na+ gradient between the external medium and intravesicular medium. The magnitude of the accumulation was similar among ileum, cecum, and rectum. In contrast, BBMV prepared from duodenum and jejunum did not show any Na+-dependent taurocholate transport, as the taurocholate uptake was not affected when a Na+ gradient was replaced by a K+ gradient. The use of taurochenodeoxycholate in the incubation medium inhibited Na+-dependent taurocholate transport in the ileum, cecum, and rectum. This study is the first to show the presence of a Na+-dependent bile salt transport in BBMV obtained from chicken ileum, proximal cecum, and rectum

Lipid Composition and Fluidity in the Jejunal Brush-Border Membrane of Spontaneously Hypertensive Rats. Effects on Activities of Membrane- Bound Proteins

The lipid compositíon and fluidity of jejunal brush-border membrane vesicles (BBMV) have been studied in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats. The activities of both Na+-dependent D-glucose cotransport and Na+-H antiport have also been determined. A significan! increase in the level of free cholesterol was observed in jejunal BBMV from SHR compared to WKY rats. Since phospholipid values did not change in either group of animals, a significan! enhancement in the free cholesterol/phospholipid ratio was observed in SHR. A decrease in the levels of phosphatidylethanolamine together with an increase in the values of phos­ phatidylserine was observed in hypertensive rats. Although the content of phosphatidylcholine (PC) and sphingomyelin (SM) was not singificantly altered in SHR, the ratio PC/SM significantly increased in these animals when compared to WKY rats. The majar fatty acids present in bursh-border membranes prepared from SHR and WKY rats were palmitic (16:0), stearic (18:0), oleic (18:1, n-9) and linoleic (18:2, n-6), and the fatty acid composition was not modified by the hypertension. A decreased fluorescence polarization, i.e., increased membrane ftuidity, was observed in SHR, which was not correlated to the increased ratio of cholesterol/phospholipid found in the brush-border membrane isolated from these animals. These structural changes found in SHR were associated to an enhancement in both Na+ -dependent D-glucose transport and Na+-H+ antiport activíty in the jejunal BBMVof SHR

Effects of two highly monounsaturated oils on lipid composition and enzyme activities in rat jejunum

The effects of two monounsaturated fatty acid (MUFA) oils, olive oil (OO)and high-oleic sunflower oil (HOSO), with high content in oleic acid butdiffering in their non-fatty acid fraction, on brush-border membrane(BBM) lipid composition and fluidity and on mucosal enzyme activitiesof rat jejunum were studied. Animals were given semipurified diet withlinoleic acid to prevent essential fatty acid deficiency (control group)or semipurified diet containing 10% of either OO or HOSO for 12weeks. There was a significant decrease in the content of jejunalBBM phospholipids together with an increase in the level of freecholesterol in both oil-fed rats, when compared to controlgroup. Although the increase in the BBM free cholesterol levelwas not statistically significant in HOSO-fed rats, a significantdecrease in the phospholipid/free cholesterol ratio was found inboth OO and HOSO-fed animals compared to control group. Rat jejunalBBM had a high level of free fatty acids which was increased in BBMisolated from OO and HOSO-fed animals. There was no statisticalsignificant difference in the phospholipid distribution between thecontrol and the OO group. However, HOSO-fed animals showed the lowestlevel of phosphatidylethanolamine together with the highestphosphatidylcholine content and the phosphatidylcholine/sphingomyelinratio. The fatty acid pattern of jejunal BBM lipids was modifiedaccording to the major fatty acids in the oils. There was a decreasein both stearic acid (18:0) and linoleic acid (18:2 n-6), togetherwith an increase in oleic acid (18:1 n-9) in jenunal BBM isolatedfrom both oil experimental groups. All these results were accompaniedby a significant increase in the BBM fluidity (as assessed bysteady-state fluorescence polarization of diphenylhexatriene) isolatedfrom oil-fed rat, when compared to control group. OO and HOSO-fedanimals had the lowest activities of sucrase and maltase, whilealkaline phosphatase activity only was decreased in HOSO-fedanimals. The specific activity of maltase was not modified in anyexperimental rats. In summary, both MUFA oils induced similar effectson jejunal BBM lipid composition, fluidity, sucrase, maltase andlactase activities. Furthermore, HOSO intake resulted in a lowestalkaline phosphatase activity which was accompanied by changes inindividual phospholipid composition. All these results suggest thateffects of MUFA oils on jejunal BBM lipid composition and hydrolaseactivities are most likely due to the presence of high content ofoleic acid rather than other components contained in the non-fattyacid of olive oil

Incorporación de casos clínicos para la mejora de la enseñanza de Fisiopatología.

El objetivo de este proyecto ha sido analizar los resultados obtenidos en el desarrollo de una nueva metodología docente en la enseñanza de Fisiopatología, asignatura troncal impartida en tercer curso de la Licenciatura de Farmacia de la Universidad de Sevilla. El número de estudiantes es de 548 repartidos en 4 grupos. El proyecto implica la resolución de casos clínicos como nuevo método de enseñanza. Con esta actividad conseguimos que el alumno realice un análisis intensivo y completo de un problema real, con la finalidad de interpretarlo, resolverlo, contrastar datos, reflexionar e interrelacionar conocimientos. El resultado de la innovación muestra que la incorporación de casos clínicos a la enseñanza de Fisiopatología beneficia al alumnado, no solo en su participación y conocimiento de la materia, sino además, en la obtención de mejores calificaciones. Por otro lado, los alumnos han mostrado su satisfacción con la nueva metodología implantada, valorando positivamente la experiencia. Palabras clave: innovación docente, Fisiopatología, casos clínicos, metodología docente.The aim of this project is to analyze the results obtained in the development of a new educational methodology in the teaching of Physiopathology (a subject included in the third year of the Bachelor Degree in Pharmacy, at the University of Seville). The number of students is 548, divided into 4 groups. The project involves the resolution of clinical cases as a new teaching method. With this activity the students carry out a full and intensive analysis of a real problem in order to interpret, solve, compare data, reflect, and interrelate knowledge. The result of this new methodology shows that the incorporation of clinical cases into the teaching of Physiopathology benefits students not only in improving the participation in class and knowledge of the material, but also in achieving better marks. Furthermore, students have shown their satisfaction with the new implemented methodology, and appreciate the experience

Elaboración de los materiales didácticos necesarios para la adaptación de la enseñanza de hematología al Espacio Europeo de Educación Superior

Con el fin de adaptarnos al Espacio Europeo de Educación Superior, este Proyecto de Innovación Docente, plantea como objetivo principal la creación, por parte del alumno, de material de autoaprendizaje basado en pruebas objetivas. La materia elegida, Hematología, forma parte de la Licenciatura de Farmacia. El proyecto, realizado sobre 400 alumnos distribuidos en 4 grupos, ha pretendido darles las bases metodológicas suficientes para elaborar preguntas de elección múltiple similares a las del sistema de evaluación del alumnado. Con esta actividad conseguimos que el alumno enfoque su aprendizaje hacia pruebas objetivas, concretando la información, distinguiendo lo más importante de cada tema, participando en el desarrollo continuo de la materia, y mejorando sus calificaciones y autoaprendizaje. El resultado de la innovación muestra un elevado grado de participación en la actividad por parte de los alumnos (incluso mayor que con otras actividades de innovación), los cuales han valorado muy positivamente la experiencia. Además, los resultados académicos han mejorado sustancialmente, como muestra la tasa de rendimiento respecto a años anteriores.In order to comply with the European Space of Higher Educational, the main aim of this Teaching Innovation Project is to encourage students to produce self-learning materials based on multiple-choice tests. The course subject under consideration is Haematology, which is studied in Pharmacy at university level. The project was carried out with 400 students distributed in 4 groups, and it aimed at providing students with enough methodological grounding, so that they could produce multiple-choice questions similar to those used in student assessment processes. By doing this, we managed to make students focus their learning on multiple-choice tests, thus defining information; distinguishing the most important areas in each subject; participating in the continuous development of the subject, and improving their marks and self-learning. The results of this innovative process show students’ high level of participation in the activity (even higher than in previous years), and that the students rated the experience very positively. Furthermore, academic results improved significantly compared to previous years, as shown by the performance rate

Regional differences in transport, lipid composition, and fluidity of apical membranes of small intestine of chicken

Na+-dependent D-glucose transport was studied in brush-border membrane vesicles from duodenum, jejunum, and ileum of 5- to 6-wk-old chickens. Regional differences were found, and both initial rates and accumulation ratio of D-glucose were higher in the proximal part of the small intestine than in the ileum. To establish the mechanism(s) underlying these differences we have studied the density of Na+-dependent D-glucose cotransporter (SGLT1) as well as lipid composition and fluidity. Phlorizin-specific binding and Western blot analysis indicated a decrease in the amount of SGLT1 in the ileum when compared to the duodenum and jejunum. The distal part of the small intestine also showed a decrease in free cholesterol content and saturated-to-unsaturated fatty acid ratio together with an increase in lipid content and phosphatidylcholine-to-sphingomyelin ratio. These results were associated with a decrease in the diphenylhextriene fluorescence polarization found in brush-border membranes of the ileum. We can conclude that the decrease in the apical D-glucose transport found in the ileum is primarily due to a reduction in the amount of SGLT1 present in the brush-border membrane rather than the differences in the lipid composition and fluidity.Ministerio de Educación y Cultura de España. PB96/1255Generalitat de Catalunya.1999-SGR-0027

Retinoprotective Effect of Wild Olive (Acebuche) Oil-Enriched Diet against Ocular Oxidative Stress Induced by Arterial Hypertension

Oxidative stress plays an important role in the pathogenesis of ocular diseases, including hypertensive eye diseases. The beneficial effects of olive oil on cardiovascular diseases might rely on minor constituents. Currently, very little is known about the chemical composition and/or therapeutic effects of the cultivated olive tree’s counterpart, wild olive (also known in Spain as acebuche—ACE). Here, we aimed to analyze the antioxidant and retinoprotective effects of ACE oil on the eye of hypertensive mice made hypertensive via administration of NG-nitro-L-arginine-methyl-ester (L-NAME), which were subjected to a dietary supplementation with either ACE oil or extra virgin olive oil (EVOO) for comparison purposes. Deep analyses of major and minor compounds present in both oils was accompanied by blood pressure monitoring, morphometric analyses, as well as different determinations of oxidative stress-related parameters in retinal layers. Aside from its antihypertensive effect, an ACE oil-enriched diet reduced NADPH (nicotinamide adenine dinucleotide phosphate) oxidase activity/gene/protein expression (with a major implication of NADPH oxidase (NOX)2 isoform) in the retinas of hypertensive mice. Supplementation with ACE oil in hypertensive animals also improved alterations in nitric oxide bioavailability and in antioxidant enzyme profile. Interestingly, our findings show that the use of ACE oil resulted in better outcomes, compared with reference EVOO, against hypertension-related oxidative retinal damage.Consejería de Economía, Conocimiento, Empresas y Universidad, Junta de Andalucía (2017/440; 2020/275; CTS-584)Ministerio de Ciencia e Innovación, Gobierno de España (Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020Programa Estatal de I+D+I PID2019-109002RB-I0

Endothelium-dependent vasorelaxation induced by L-carnitine in isolated aorta from normotensive and hypertensive rats

The aim of this work was to investigate the mechanism of the vasodilatory effect induced by L- carnitine. Relaxation produced by L-carnitine was studied in rat aortic rings with and without functional endothelium, pre-contracted with phenylephrine by adding cumulative doses of L- carnitine (10-7 to 10-3 M). The relaxation evoked by L-carnitine reached higher values in aortic rings from spontaneously hypertensive rats than those obtained in arteries from normotensive rats; no relaxation was produced in de-endothelialized arteries. However, in the presence of NG-nitro-L- arginine (3¬10-5 M, a nitric oxide synthase inhibitor), Ro 68070 (10-4 M, a thromboxane synthetase inhibitor–thromboxane A2/prostaglandin H2 receptor antagonist) or ICI 192605 (10- M, a thromboxane A2 receptor antagonist) the relaxant response to L-carnitine was signiicantly inhibited. These results show that L-carnitine induced endothelium-dependent relaxation in the rat aorta and the mechanism of this relaxation appeared to be mostly mediated by endothelial production of nitric oxide but also could involve prevention of the action of cyclooxygenase endothelial products acting on the thromboxane A2/prostaglandin H2 receptor

Folate transport by prawn hepatopancreas brush-border membrane vesicles.

The transport system of folic acid (Pte-Glu) b y brush-borde r membrane vesicles (BBMV ) isolated from prawn (Penaeus japonicm) hepatopancreas , was studied by measuring the uptake of Pte-Glu . This uptake was found to have two components , intravesicular transport and membrane binding . Membrane binding was not affected by the presence of a trans - membrane pH-gradient at a short incubation period . However , a transmembrane pH - gradient increased membrane binding at 6 0 min. The transpor to f Pte-Glu appeared to be carrier-mediated , was stimulated by an inwardly proton gradient (p H 5. 5 outside , 7. 4 inside ) and was unaffected by a sodium-gradient . The relationship between pH gradient-driven Pte-Glu uptake and medium Pte-Glu concentration followed saturating Michaelis-Menten kinetics . Eadie-Hofste e representation of the pH gradient-driven Pte-Glu uptake indicated a single transport system with a Km of 0.3 7 ^ Man d Vmax of 1.06pmol/mg protein/15s . These findings indicate that BBM V isolated from prawn hepatopancreas possesses a Pte - Glu transport system similar to that described in mammalian intestine