Browsing by Author "Álvarez Millán, Juan José"

The apolipoprotein (apo) E phenotype and its influence on plasma lipid and apolipoprotein levels were determined in men and women from a working population of Madrid, Spain. The relative frequencies of alleles i:2, d and i:4 for the study population (n = 614) were 0.080, 0.842 and 0.078, respectively. In men, apo E polymorphism was associated with variations in plasma triglyceride and very low-density lipoprotein (VLDL) lipid levels. lt was associated with the proportion of apo C-II in VLDL, and explained 5.5% of the variability in the latter parameter. In women apo E polymorphism was associated with the concentrations of plasma cholesterol and low-density Iipoprotein (LDL) and high-density lipoprotein (HDL) related variables. The allelic effects were examined taking allele c3 homozygosity as reference. In men, allele i:2 significantly increased VLDL triglyceride and VLDL cholesterol concentrations, and this was accompanied by an increase of the apo C-II content in these particles. Allele i:4 did not show any significant influence on men's lipoproteins. In women, allele i:2 lowered LDL cholesterol and apo B levels, while allele i:4 increased LDL cholesterol and decreased the concentrations of HDL cholesterol, HDL phospholipid and apo A-1. These effects were essentially maintained after excluding postmenopausal women and oral contraceptive users from the analysis. In conclusion: (1) the population of Madrid, similar to other Mediterranean populations, exhibits an underexpression of apo E4 compared to the average prevalence in Caucasians, (2) gender interacts with the effects of apo E polymorphism: in women, it influenced LDL and HDL levels, whereas in men it preferentially affected VLDL, and (3) allele i:2 decreased LDL levels in women, while it increased both VLDL lipid levels and apo C-II content in men, but, in contrast to allele i:4, it did not show an impact on HDL in either sex.

El embarazo modifica de una forma continua y dinámica el metabolismo de la madre, que ha de garantizar el aporte ininterrumpido de nutrientes al feto, a fin de sostener su crecimiento, que es exponencial y especialmente rápido en el último tercio. Para lograr un adecuado diagnóstico y tratamiento de la situación patológica de la gestante que pueda coexistir con su embarazo, o incluso ser potenciada por éste, es necesario conocer los cambios metabólicos que tienen lugar normalmente en ella, como consecuencia de la propia gestación. Entre los nutrientes que la madre tiene que aportar continuamente al feto a través de la placenta, la glucosa es cuantitativamente la más importante, seguida de los aminoácidos, y el metabolismo y desarrollo del feto dependen directamente de estos nutrientes que le llegan de la madre. Esto fuerza a la madre a desarrollar hipoglucemia e hipoaminoacidemia. En este capítulo se revisan los principales cambios metabólicos que tienen lugar a lo largo de la gestación, y que afectan al perfil bioquímico de la madre, con especial atención a las interacciones de hidratos de carbono y lípidos, analizando también su relación con las variaciones hormonales que se producen y que afectan a los parámetros de diagnóstico bioquímico más usuales en el embarazo.

Liver disease is accompanied by major qualitative and quantitative disturbances in plasma lipoprotein metabolism, the extent and intensity of which depend on the degree of parenchymal damage, cholestasis, or both. The main objective of this study was to determine the cholesteryl ester transfer CETP activity and its association with the lipoprotein neutral lipid composition in patients with either liver cirrhosis or cholestasis, as compared to normal controls. Lipoproteins were isolated by ultracentrifugation, lipids and apolipoproteins were measured by conventional methods, and the fatty acid composition was established by gas chromotography; CETP activity in lipoprotein-deficient plasma was measured by determining the transfer of [3H]cholesteryl esters from HDL to VLDL. Lipoprotein lipase and hepatic lipase activities were measured in post-heparin plasma by radiochemical methods. In patients with liver cirrhosis, low levels of VLDL, HDL, apo B, and Lp(a) were observed, as well as a change in the composition of HDL particles, with increases in the relative proportion of triglyceride and free cholesterol. Respectively, the last two changes could be attributed in part to the low hepatic lipase activity observed in this study, and to the low lecithin:cholesterol acyltransferase activity previously observed by others. In patients with cholestasis, a moderate hyperlipidemia due to the elevation of LDL was found. In contrast, HDL and apo A-I levels were very low reflecting a low number of HDL particles, which also had altered compositions with increases in the triglyceride and free cholesterol contents relative to apo A-I and esterified cholesterol, respectively. As regards the fatty acid composition of lipoprotein lipids, the two groups of patients showed, in general, a lower proportion of linoleic acid and a compensating higher proportion of oleic acid as compared to the controls, changes that were observed in both cholesteryl esters and triglycerides. In contrast, the proportions of oleic and palmitoleic acids in phospholipids were increased, whereas that of stearic acid was decreased in patients as compared to controls. In patients with liver cirrhosis, as well as in controls, no changes were observed in the fatty acid compositions of cholesteryl ester, triglycerides, or phospholipids among the different lipoproteins, which probably reflects the equilibration reached by the action of CETP. In patients with cholestasis, no differences were observed in fatty acid composition among the lipoprotein phospholipids but, interestingly, cholesteryl esters from VLDL had a significantly lower linoleic acid content than those from HDL, whereas triglycerides from VLDL had significantly higher oleic acid and lower linoleic acid contents than those from HDL. This distinct fatty acid composition of the neutral lipids between lipoproteins was associated with a significant decrease (25%) in the cholesteryl ester transfer activity in patients with cholestasis. We suggest that fat malabsorption due to the biliary defect may induce a decrease in cholesteryl ester transfer protein synthesis or secretion, which in turn would slow the equilibration of the neutral lipids among plasma lipoproteins.

Endoplasmic reticulum (ER) homeostasis is crucial to appropriate cell functioning, and when disturbed, a safeguard system called unfolded protein response (UPR) is activated. Fructose consumption modifies ER homeostasis and has been related to metabolic syndrome. However, fructose sweetened beverages intake is allowed during gestation. Therefore, we investigate whether maternal fructose intake affects the ER status and induces UPR. Thus, administrating liquid fructose (10% w/v) to pregnant rats partially activated the ER-stress in maternal and fetal liver and placenta. In fact, a fructose-induced increase in the levels of pIRE1 (phosphorylated inositol requiring enzyme-1) and its downstream effector, X-box binding protein-1 spliced form (XBP1s), was observed. XBP1s is a key transcription factor, however, XBP1s nuclear translocation and the expression of its target genes were reduced in the liver of the carbohydrate-fed mothers, and specifically diminished in the fetal liver and placenta in the fructose-fed mothers. These XBP1s target genes belong to the ER-associated protein degradation (ERAD) system, used to buffer ER-stress and to restore ER-homeostasis. It is known that XBP1s needs to form a complex with diverse proteins to migrate into the nucleus. Since methylglyoxal (MGO) content, a precursor of advanced glycation endproducts (AGE), was augmented in the three tissues in the fructose-fed mothers and has been related to interfere with the functioning of many proteins, the role of MGO in XBP1s migration should not be discarded. In conclusion, maternal fructose intake produces ER-stress, but without XBP1s nuclear migration. Therefore, a complete activation of UPR that would resolve ER-stress is lacking. A state of fructose-induced oxidative stress is probably involved.

H2S, a gasotransmitter that can be produced both via the transsulfuration pathway and non-enzymatically, plays a key role in vasodilation and angiogenesis during pregnancy. In fact, the involvement of H2S production on plasma levels of sFLT1, PGF, and other molecules related to preeclampsia has been demonstrated. Interestingly, we have found that maternal fructose intake (a common component of the Western diet) affects tissular H2S production. However, its consumption is allowed during pregnancy. Thus, (1) to study whether maternal fructose intake affects placental production of H2S in the offspring, when pregnant; and (2) to study if fructose consumption during pregnancy can increase the risk of preeclampsia, pregnant rats from fructose-fed mothers (10% w/v) subjected (FF) or not (FC) to a fructose supplementation were studied and compared to pregnant control rats (CC). Placental gene expression, H2S production, plasma sFLT1, and PGF were determined. Descendants of fructose-fed mothers (FC) presented an increase in H2S production. However, if they consumed fructose during their own gestation (FF), this effect was reversed so that the increase disappeared. Curiously, placental synthesis of H2S was mainly non-enzymatic. Related to this, placental expression of Cys dioxygenase, an enzyme involved in Cys catabolism (a molecule required for non-enzymatic H2S synthesis), was significantly decreased in FC rats. Related to preeclampsia, gene expression of sFLT1 (a molecule with antiangiogenic properties) was augmented in both FF and FC dams, although these differences were not reflected in their plasma levels. Furthermore, placental expression of PGF (a molecule with angiogenic properties) was decreased in both FC and FF dams, becoming significantly diminished in plasma of FC versus control dams. Both fructose consumption and maternal fructose intake induce changes in molecules that contribute to increasing the risk of preeclampsia, and these effects are not always mediated by changes in H2S production.

Background Plasma concentrations of vitamins A and E are positively correlated with those of concurrent lipids and, on the other hand, lipid levels are influenced by apolipoprotein E polymorphism. Therefore, the effect of this polymorphism on both vitamins was analysed in an adult population. Materials and methods Subjects were recruited from a working population. Their anthropometric, lifestyle and dietary intake variables and menopausal status were recorded. Their apolipoprotein E phenotype and their plasma vitamins A and E (by high-performance liquid chromatography) and lipid (enzymatically) concentrations were determined after an overnight fast. The associations of the phenotype with vitamins and lipids were studied in men and women separately and controlling for significant covariates. Results The apolipoprotein E phenotype was associated with the concentrations of total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol in women, whereas no associations with lipids were found in men. Vitamin A and vitamin E levels were higher in men than in women, but only the difference in the former persisted after lipid adjustment. Apolipoprotein E2 slightly increased vitamin A levels in women, an effect which was still evident with lipid adjustment. Actually, both the apolipoprotein E phenotype and triglyceride were selected as significant predictors of this vitamin by multiple regression. This phenotype did not affect vitamin E levels in either sex. Conclusions Lipids do not mediate the effect of gender on vitamin A levels. Apolipoprotein E polymorphism is an independent determinant of vitamin A levels in women. Pending confirmation by others, we propose that enhancement of this vitamin may contribute to the beneficial impact of the E2 allele on human ageing and health.

Se ha determinado la influencia de la presencia de la Lp (a) en el plasma sobre el valor de colesterol HDL. El plasma de 604 sujetos, seleccionados sin atender a ningún criterio restrictivo de edad, sexo o enfermedad, se procesó para la determinación de la concentración de colesterol y triglicéridos en HDL, que fueron separados tanto por precipitación con fosfotungstato-MgCl 2 como por ultracentrifugación diferencial secuencial en el límite de densidad 1,063-1,21 kg/1. La presencia de Lp (a) se determinó atendiendo a la aparición, en electroforesis en gel de agarosa, de una banda con movilidad pre-p ("pre-~-oculta") en el infranadante del plasma de densidad superior a 1,006 kg/1 (libre de VLDL) y las muestras se clasificaron en pre-P,oculta ( +) y pre-p-oculta (-), respectivamente. La Lp (a) también se cuantificó en el plasma mediante enzimoinmunoanálisis y se observó una estrecha corresoondencia entre la aparición de pre-P-oculta y ~na concentración plasmática de Lp (a) superior a 300 mg/1. En las muestras pre-P-oculta ( +), pero no en las pre-P-oculta (-), el valor de cHDL obtenido por ultracentrifugación fue significativamente superior al obtenido por precipitación y existía una correlación lineal y positiva entre la diferencia de ambos y la concentración de Lp (aj en el plasma. Una concentración de Lp (a) de 300 mg/1 (que presenta más del 27 % de la población estudiada) determina un valor de cHDL por ultracentrifugación superior al de precipitación en 0,129 mmol/1, aproximadamente. La diferencia entre ambos valores se atribuye a que la Lp (a) precipita junto con las LDL bajo la acción de los polianiones mientras que, por ultracentrifugación, se separa parcialmente junto con las HDL.

In order to evaluate cardiovascular risk, we analyzed the lipid composition of HDL and the presence of lipoprotein(a) [Lp(a)] by both agarose gel electrophoresis and enzyme-linked immunoassay (ELISA). In 681 plasmas we found a close correspondence between the existence of a visible sinking pre-~ lipoprotein band and a concentration of Lp(a) higher than 300 mg/L. In the sinking pre-~(+) samples, the HDL-cholesterol level obtained by differential ultracentrifugation was significantly higher than that obtained by precipitation with the MgCl 2-phosphotungstic acid reagent; and the difference between these HDL-cholesterol values was linearly correlated with plasma Lp(a) concentration. Moreover, the other HDL lipid components and the lipid mass ratios of HDL isolated by ultracentrifugation were significantly different from those of HDL isolated by precipitation, and these changes were also correlated with plasma Lp(a). These differences are attributed to Lp(a) because it was detected in the 1 .063-1.21 kg/L plasma fractions, whereas it was absent in the plasma supernates after precipitation with MgCl2- phosphotungstic acid. Although to a lesser extent, Lp(a) was also present in the LDL and VLDL density ranges and it directly depended on both the Lp(a) and the triglyceride plasma concentrations. The proportion of Lp(a) in HDL as related to that in LDL density fractions decreased as Lp(a) plasma levels increased, reflecting an interindividual variation of Lp(a) density species. Since 90% of our study population had detectable Lp(a) in plasma, the results reinforce the concept that the ultracentrifugation method is not equivalent to precipitation in most samples, and the contaminant effect of Lp(a) cannot be predicted because of Lp(a) partition into the different lipoprotein fractions.

La lipoproteína(a) o Lp(a) es una partícula plasmática intrigante, por cuanto su significado fisiológico y su papel en la aterotrombosis son todavía inciertos; a pesar de ello, su carácter de factor de riesgo cardiovascular está ampliamente aceptado1·2. El descubrimiento de la homología entre la apoproteína característica de la Lp(a), la apo(a), con el plasminógeno alumbró la conexión que establecía la Lp(a) entre la aterosclerosis y la trombosis3. La interferencia en el proceso fibrinolítico que produce la Lp(a) tiene indeseables consecuencias cuando la aterosclerosis está avanzada y extendida; paradójicamente, puede haber sido la función por la cual ha sido preservada en la evolución. Su concentración plasmática está determinada genéticamente y no se dispone de tratamientos no invasivos eficaces para su control; no obstante, el análisis de la Lp(a) permite aquilatar la situación de riesgo del paciente y emprender otras medidas terapéuticas. Al margen de su trascendencia, la aparición de la Lp(a) en el escenario de la interacción de las lipoproteínas con la pared vascular ha motivado el interés y el encuentro de los lipidólogos con la hematología y viceversa.

Dada la doble condición aterogénlca y antilibrinolltica de la lipoprotelna (1) (o Lp (al) y su carácter de factor de riesgo cardiovascular, se ha analizado 11 evolución de la concentración plasmática de esta lipoprotelna durante el tratamiento con aféresis de LOL en un paciente con hi~rcoleslerolt'mia familiar homocigólica. Mí 1000s: Varón de 9 a/los con déficit funcional de receptor LOL tratado con aféresis de LOL mediante columnas de sulfato de dextrán, semanalmente a lo largo de un ano. Se tomaron muestras de suero en condiciones basales y después de cada sesión de aféresis, asl como muestras de plasma del propio sistema de perfusión para analizar la capacidad de retención de lipoprotelnas por aquellas columnas. las muestras se procesaron para la valoración de Lp (al mediante ELISA con anticuerpo policlonal. RJ su, tAoos: Al inicio del tratamiento, la concentración sérica de Lp (al en el paciente era muy alta (997 mgll), que se ha reducido progresivamente con las sucesivas sesiones de aféresis. Actualmente, la concentración máxima de lp (al que alcanza el paciente es ~ 1igeramente superior a 400 mgll y la mlnima (postaléresis) es inferior a 50 mg/1. las columnas de sulfato de dextrán retienen con alta afinidad y capacidad todas las lipoprotelnas que contienen apo B. incluidas las LOL y la lp (al, de manera que en cada sesión, mediante el tratamiento de tres veces el volumen plasmático del paciente, se reduce la concentración shlc:1 de lp (a) en un 85 %. Tras la aféresis se produce un progresivo ascenso en su concentración 'J el análisis cinético de estos datos ha permitido estimar la tasa catabólica lraccional de la Lp (al en este paciente en 0,08 acervos/dla. El tratamiento con lovastatina no modificó ni este parámetro ni la concentración circulante de lp (al. . CoNcLus1QNES: Al cabo de un allo de sesiones semanales continuadas de aféresis, la · concentración media de lp (al del paciente es menor de 300 mg/1, que puede considerarse fuera de riesgo. Por lo tanto, la aféresis con columnas de sulfato de dextrán es un tratamiento sumamente eficaz para la reducción de las concentraciones séricas tanto de LDL como de Lp (1) en la hipercolesterolemia familiar homocigótica.

To understand the mechanism responsible for maternal hyperlipidemia, 25 healthy pregnant women were studied longitudinally during the three trimesters of gestation and at post-partum, and 11 were studied again at post-lactation. Triglyceride and cholesterol levels increased with gestation in all the lipoprotein fractions. However, the greatest change appeared in low density (LDL) and high density (HDL) lipoproteins, both of which showed an increase in their triglyceride/ cholesterol ratio. The proportional distribution of HDL subfractions showed that the HDL2b fraction was the only one that increased with gestation, whereas both HDL.sa and HDLsb had the greatest decrease. Cholesteryl ester transfer protein activity increased during the second trimester of gestation. While postheparin lipoprotein lipase activity decreased during the third trimester, postheparin hepatic lipase activity progressively decreased from the first trimester. The 17J3-estradiol, progesterone, and prolactin hormones progressively increased from the first trimester of gestation. The lipoprotein-triglyceride values correlated linearly and negatively with the logarithm of either postheparin lipase activities, HDlrtriglycerides showing the highest correlation coefficient when plotted against the hepatic lipase values (r = -0.757). It appeared that the highest correlation between any of the HDL subclasses and the activity of the enzymes was for hepatic lipase activity versus HDL2b (r = -0.456) or HDLsa (r = 0.519). A significant lineal correlation also appeared between the postheparin hepatic lipase activity and the logarithm of any of the sex hormones studied, the highest value corresponding to estradiol (r = -0.783). Ill Therefore, during gestation, the effect of estrogen in enhancing very low density lipoprotein (VLDL) production and decreasing hepatic lipase activity plays a key role in the accumulation of triglycerides in lipoproteins of density higher than VLDL.

Fructose-rich beverages and foods consumption correlates with the epidemic rise in cardiovascular disease, diabetes and obesity. Severity of COVID-19 has been related to these metabolic diseases. Fructose-rich foods could place people at an increased risk for severe COVID-19. We investigated whether maternal fructose intake in offspring affects hepatic and ileal gene expression of proteins that permit SARS-CoV2 entry to the cell. Carbohydrates were supplied to pregnant rats in drinking water. Adult and young male descendants subjected to water, liquid fructose alone or as a part of a Western diet, were studied. Maternal fructose reduced hepatic SARS-CoV2 entry factors expression in older offspring. On the contrary, maternal fructose boosted the Western diet-induced increase in viral entry factors expression in ileum of young descendants. Maternal fructose intake produced a fetal programming that increases hepatic viral protection and, in contrast, exacerbates fructose plus cholesterolinduced diminution in SARS-CoV2 protection in small intestine of progeny.

In this study we have determined how lipoprotein( a) (Lp(a)) influences the HDL-cholesterol ' lewel when present in human plasma. Six hundred : and eighty one individuals were chosen for the : study disregarding age, sex or illness criteria. '. Their plasma was processed in order to assess the cholesterol and triglyceride concentrations in . HDL particles isolated both by MgCl2- Phospho''. tungstic acid precipitation and differential ultra' centrifugation in the density range of 1.063-1.21 I , kg/L. The presence of Lp(a) was identified noting I · the presence or not of a band with a pre-f3 elec- ' .rophoretic mobility ("sinking pre-f3" lipoprotein) i in agarose gel electrophoresis of VLDL-free pla: sma (plasma infranatant at d> 1.006 kg/L). On •r·· this basis, the samples were classified as sinking pre-f3( +) and sinking pre-f3(-), respectively. Lp(a) j was also quantified in plasma by means of an 1 enzyme-linked immunoassay and a close corre\ spondence between the existence of "sinking pre~ f3" lipoprotein, and a plasmatic concentration of ! Lp(a) 'higher than 300 mg/L was observed. The : HDL-cholesterol level obtained by ultracentrifu. g~tion was higher than the one assessed by preci, pitation in the sinking pre-f3( +) samples, but not in the sinking pre-f3(-). There was a positive lineal correlation between the difference of such HDL-cholesterol levels and plasma Lp(a) concentration. A Lp(a) concentration of 300 mg/L (value found in more than 27% of the population study) · settles an ultracentrifugation HDL-cholesterol value that was 0.097 mmol/L higher than the precipitation HDL-cholesterol level. The presence of Lp(a) in the lipoprotein fractions prepared by ultracentrifugation was determined. Lp(a) was mostly detected in the HDL fraction. This latter result together with the observation that Lp(a) precipitates along with LDL under the action of the MgCl2-Losphotungstic acid reagent, explains the discrepancy between HDL-cholesterol values commented above. The proportion of Lp(a) present in the LDL fraction (density range: 1.006-1.063 kg/L) was in av~-- rage one thire of that in HDL. Lp(a) in the VLDL fraction was detectable in plasma with a high concentration of Lp(a); in these samples, Lp(a) in VLDL was positively correlated with VLDL-triglycerides. In conclusion, Lp(a) is mostly separated along with HDL, but also LDL and even VLDL particles from ultracentrifuged plasma. This means a Lp(a) interference in the quantification of HDL-cholesterol by ultracentrifugation that is proportional to plasma Lp(a) concentration.