Phytosterol-Enriched Yogurt Increases LDL Affinity and Reduces CD36 Expression in Polygenic Hypercholesterolemia

Dietary enrichment with phytosterols (plant sterols similar to cholesterol) is able to reduce plasma cholesterol levels due to reduced intestinal absorption. The aim of this study was to investigate the effect of phytosterol-enriched yogurt consumption on the major serum lipid parameters, low density lipoprotein (LDL) receptor activity, LDL-receptor affinity, and CD36 expression in hypercholesterolemic subjects. Fifteen patients affected by polygenic hypercholesterolemia were evaluated in a single-blind randomized crossover study after a 4 weeks treatment with a phytosterol-enriched yogurt containing 1.6 g esterefied phytosterols (equivalent to 1.0 g free phytosterol). Lipid parameters were compared with a phytosterol-free placebo-controlled diet. The effect of the two treatments on each variable, measured as percentage change, was compared by paired samples t test and covariance analysis. The treatment induced a modest but significant decrease in LDL-cholesterol levels (4.3%, P = 0.03) and a significant increase in high density lipoprotein (HDL) 3-cholesterol (17.1%, P = 0.01). Phytosterol consumption had no effect on LDL-receptor activity whereas patient LDL-receptor affinity significantly increased (9.7%, P = 0.01) and CD36 expression showed a marked significant decrease (18.2%, P = 0.01) in the phytosterol-enriched yoghurt patients. Our data show that the oral administration of a phytosterol-enriched yogurt has modest but significant effects on commonly measured lipid parameters. The improvement of LDL-receptor affinity and the reduction in CD36 expression may reflect an important antiatherogenic effect.     

A Green Tea Catechin Extract Upregulates the Hepatic Low-Density Lipoprotein Receptor in Rats

Green tea extracts have hypocholesterolaemic properties in epidemiological and animal intervention studies. Upregulation of the low-density lipoprotein (LDL) receptor may be one mechanism to explain this as it is the main way cholesterol is removed from the circulation. This study aimed to determine if a green tea extract could upregulate the hepatic LDL receptor in vivo in the rat. A green tea extract (GTE) enriched in its anti-oxidant constituents, the catechins, was fed to rats (n = 6) at concentrations of either 0, 0.5, 1.0 or 2.0% (w/w) mixed in with their normal chow along with 0.25% (w/w) cholesterol for 12 days. Administration of the GTE had no effect on plasma total or LDL cholesterol concentrations but high-density lipoprotein significantly increased (41%; p < 0.05). Interestingly, there was a significant increase in LDL receptor binding activity (2.7-fold) and LDL receptor protein (3.4-fold) in the 2% (w/w) treatment group compared to controls. There were also significant reductions in liver total and unesterified cholesterol (40%). Administration of the GTE significantly reduced cholesterol absorption (24%) but did not affect cholesterol synthesis. These results show that, despite no effect on plasma cholesterol, the GTE upregulated the LDL receptor in vivo. This appears to be via a reduction in liver cholesterol concentration and suggests that the green tea extract was able to increase the efflux of cholesterol from liver cells.     

Identification of Correlative Shifts in Indices of Brain Cholesterol Metabolism in the C57BL6/Mecp2tm1.1Bird Mouse,a Model for Rett Syndrome

Rett syndrome (RS) is a pervasive neurodevelopmental disorder resulting from loss‐of‐function mutations in the X‐linked gene methyl‐Cpg‐binding protein 2 (MECP2). Using a well‐defined model for RS, the C57BL6/Mecp2^tm1.1Bird mouse, we have previously found a moderate but persistently lower rate of cholesterol synthesis, measured in vivo, in the brains of Mecp2^?/y mice, starting from about the third week after birth. There was no genotypic difference in the total cholesterol concentration throughout the brain at any age. This raised the question of whether the lower rate of cholesterol synthesis in the mutants was balanced by a fall in the rate at which cholesterol was converted via cholesterol 24‐hydroxylase (Cyp46A1) to 24S‐hydroxycholesterol (24S‐OHC), the principal route through which cholesterol is ordinarily removed from the brain. Here, we show that while there were no genotypic differences in the concentrations in plasma and liver of three cholesterol precursors (lanosterol, lathosterol, and desmosterol), two plant sterols (sitosterol and campesterol), and two oxysterols (27‐hydroxycholesterol [27‐OHC] and 24S‐OHC), the brains of the Mecp2 ^?/y mice had significantly lower concentrations of all three cholesterol precursors, campesterol, and both oxysterols, with the level of 24S‐OHC being ~20% less than in their Mecp2 ^+/y controls. Together, these data suggest that coordinated regulation of cholesterol synthesis and catabolism in the central nervous system is maintained in this model for RS. Furthermore, we speculate that the adaptive changes in these two pathways conceivably resulted from a shift in the permeability of the blood–brain barrier as implied by the significantly lower campesterol and 27‐OHC concentrations in the brains of the Mecp2^?/y mice.     

Respective Hydrolysis and Esterification of Esterified and Free Plant Stanols Occur Rapidly in Human Intestine After Their Duodenal Infusion in Triacyl- or Diacylglycerol

Esterification of dietary phytosterols and glycerols may affect intestinal absorption of cholesterol and non-cholesterol sterols. We infused plant stanol esters in triacylglycerol (TAG) (F1) and diacylglycerol (DG) (F2) oils, and free plant stanols in F1 and F2 (F3) to the duodenum of healthy human subjects and sampled the contents from the proximal jejunum (PJ). Free and ester sterols were analysed from the infusates, and intestinal contents before and after ultracentrifuge separation of oil, micelle and sediment phases. During the 60-cm intestinal passage, over 40% of plant stanol esters were hydrolysed (P < 0.05) but around 30% of the infused free plant stanols (P < 0.05) and up to 40% of cholesterol (P < 0.05) were esterified in PJ after infusions. TAG in F1 favoured accumulation of plant stanol esters in the oil phase of the PJ aspirates as compared with respective values of F2 and F3 (P < 0.05 for both). About one third of free plant stanols of F3 had been esterified (P < 0.05) and 17% precipitated mainly in free form in the PJ aspirates (P < 0.05 compared with F1 and F2). In conclusion, DG- and TAG-oils had no profound superiority over each other as intestinal carriers regarding hydrolysis/esterification of administered plant stanol esters and cholesterol and their partition in oil, micellar and sediment phases in the PJ. The unesterified plant stanols experienced partial esterification and sedimentation during their intestinal passage, which might influence their biochemical properties in that segment of the gut where cholesterol is absorbed.     

The HMG-CoA Reductase Gene and Lipid and Lipoprotein Levels: the Multi-Ethnic Study of Atherosclerosis

HMG-CoA reductase (HMGCR) is an enzyme involved in cholesterol synthesis. To investigate the contribution of the HMGCR gene to lipids and lipoprotein subfractions in different ethnicities, we performed an association study in the Multi-Ethnic Study of Atherosclerosis (MESA). In total, 2,444 MESA subjects [597 African-Americans (AA), 627 Chinese-Americans (CHA), 612 European-Americans (EA), and 608 Hispanic-Americans (HA)] without statin use were included. Participants had measurements of blood pressure, anthropometry, and fasting blood samples. Subjects were genotyped for 10 single nucleotide polymorphisms (SNPs). After excluding SNPs with minor allele frequency <5%, a single block was constructed. The most frequent haplotype was H1 (41–56%) in all ethnic groups except AA (H2a, 44.9%). Lower triglyceride level was associated with the H2a haplotype in AA and H2 in HA. In HA, H4 carriers had higher levels of triglyceride and small low-density lipoprotein (s-LDL), and lower high-density lipoprotein cholesterol (HDL-c), while carriers with H7 or H8 had associations with these traits in the opposite direction. No significant association was discovered in both CHA and EA. The total variation for triglyceride that could be explained by H2 alone was 2.6% in HA and 1.4% in AA. In conclusion, HMGCR gene variation is associated with multiple lipid/lipoprotein traits, especially with triglyceride, s-LDL, and HDL-c. The impact of the genetic variance is modest and differs greatly among ethnicities.     

Determination of sterols, oxysterols, and fatty acids of phospholipids in cells and lipoproteins: A one-sample method

In addition to fatty acids, especially polyunsaturated species, cholesterol oxidizes and leads to various oxygenated derivatives, named oxysterols. They display a wide range of adverse biological properties. Monitoring oxysterols is important in the evaluation of the potential risks associated with lipid oxidation. In the present study, a quick and reliable method was developed for analysis of oxysterols, sterols, and fatty acid composition of phospholipids in the same biological sample. Total lipid extraction was determined after addition of several internal standards (epicoprostanol for sterols, 19-hydroxy-cholesterol for oxysterol and di-heptadecanoyl-phosphatidylcholine for phospholipid fatty acids). Cold acetone-mediated precipitation was then used to fractionate sterols from phospholipids. The phospholipid-containing precipitate was transmethylated for fatty acid analysis by gas chromatography. The sterol- and oxysterol-containing phase was saponified under mild conditions to avoid artificial oxysterol generation and was analyzed by gas chromatography after derivatization into trimethylsilyl ethers. The overall procedure was found to be specific with good recovery and reproducibility for sterols, oxysterols [mean coefficient of variation in percent (CV), 11.3%] as well as phospholipid fatty acids (CV, 5.6%). This procedure has been used to document in vitro free radical treated-human low-density lipoproteins and erythrocytes. Results demonstrated that this method is a useful tool in assessing qualitative and quantitative differences in oxysterols and phospholipid fatty acid patterns attributed to lipid oxidation.     

Lipid transfers to HDL are diminished in long-term bedridden patients: association with low HDL-cholesterol and increased inflammatory markers

Plasma lipids have been extensively studied in sedentary and in subjects practicing exercise training, but not in extreme inactivity as occurs in bedridden patients. This is important for the care of bedridden patients and understanding the overall plasma lipid regulation. Here, we investigated plasma lipids, lipid transfers to HDL and inflammatory markers in bedridden patients. Fasting blood samples were collected from 23 clinically stable bedridden patients under long‐term care (>90 days) and 26 normolipidemic sedentary subjects, paired for age and gender. In vitro transfer of four lipids to HDL was performed by incubating plasma with donor nanoparticles containing radioactive lipids. Total (193 ± 36 vs 160 ± 43, p = 0.005), LDL (124 ± 3 vs 96 ± 33 p = 0.003) and HDL‐cholesterol (45 ± 10 vs 36 ± 13, p = 0.008), apolipoprotein A‐I (134 ± 20 vs 111 ± 24, p = 0.001) and oxidized LDL (53 ± 13 vs 43 ± 12, p = 0.011) were lower in bedridden patients, whereas triglycerides, apolipoprotein B, CETP and LCAT were equal in both groups. Transfers of all lipids, namely unesterified cholesterol, cholesterol esters, triglycerides and phospholipids, to HDL were lower in bedridden patients, probably due to their lower HDL‐cholesterol levels. Concentrations of IL‐1β, IL‐6, IL‐8, HGF and NGF were higher in bedridden patients compared to sedentary subjects. In conclusion, inactivity had great impact on HDL, by lowering HDL‐cholesterol, apolipoprotein A‐I and thereby cholesterol transfers to the lipoprotein, which suggests that inactivity may deteriorate HDL protection beyond the ordinary sedentary condition.     

Plasma Phytosterol Half‐Life and Levels Are Increased in Very Low Birth Weight Preterm Infants with Parenteral Nutrition‐Associated Cholestasis

Parenteral nutrition‐associated cholestasis (PNAC) has been linked to plasma accumulation of phytosterols in infants receiving vegetable‐oil‐based lipid emulsions (LE). To date, information on the ability of infants with PNAC to metabolize intravenous (IV) phytosterols has been very limited. We characterized plasma phytosterol half‐life in very low birth weight (VLBW) preterm infants with PNAC. As part of a prospective cohort study, VLBW infants with PNAC underwent serial blood sample measurements of sitosterol (Sito), campesterol (Camp), and stigmasterol (Stigma). Infants without PNAC served as controls (CTRL, control infants). Thirty‐seven PNAC infants and 14 CTRL were studied. On PN day 7 and PN day 14, PNAC infants had higher plasma phytosterol concentrations compared to those of CTRL (p < 0.05). A significant and positive correlation was found between plasma Camp, Stigma, Sito concentrations, and IV phytosterol intake from birth to PN day 7 (p = 0.001, p = 0.001, and p = 0.005, respectively). Stigma concentration was positively correlated with conjugated bilirubin on PN day 7 (p = 0.012). After stopping IV LE, half‐lives of Camp, Stigma, and Sito became significantly longer in PNAC infants than in CTRL (Camp: 18.8 ±6.2 vs 11.8 ±3.0 days, p = 0.001; Stigma: 13.8 ±5.8 vs 9.4 ±3.4 days, p = 0.023; Sito: 15.3 ±5.0 vs 9.8 ±3.0 days, p = 0.002). In conclusion, phytosterols increased earlier during PN and were eliminated slowly after stopping IV LE in PNAC infants than in CTRL. The Stigma concentration on PN day 7 could represent an early marker of cholestasis. Our results provide additional evidence on the relationship between IV phytosterols and PNAC.     

心血管病治疗中的联合用药问题分析

目的研究探讨心血管病治疗中的临床联合用药情况。方法对心血管住院病人的临床用药情况采取合理用药监测系统进行连续监测,并进行数据分析。结果对心血管住院病人的296条临床用药医嘱单进行监测。286条药物相互作用合理,10条存在不合理配伍情况。结论对心脑血管疾病治疗中的联合用药问题要加强重视,监测观察药物之间的相互作用,制定安全有效地联合用药方案及措施。     

Circulating Levels of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 are Associated with Inflammatory Markers

Lectin-like oxidized-low-density lipoprotein receptor-1 (LOX-1) is increasingly linked to atherosclerotic plaque formation and the soluble form of this receptor may reflect activities of disease. We investigated the associations among levels of sLOX-1, oxidized-low-density lipoprotein (ox-LDL), cytokines and the extension of atherosclerosis in patients with coronary artery disease (CAD). Lipid, TNF-alpha, IL-6, C reactive protein (CRP), ox-LDL, peroxy radical and sLOX-1 levels were measured in 29 controls and 60 patients with CAD, 30 of which with one or two vessels involved (group 1), and 30 patients with three or four vessels involved (group 2). The serum levels of sLOX-1 were significantly and progressively higher in group 1 [611 (346-1,313) pg/ml, median (interquartile range)] and in group 2 [2,143 (824-3,201) pg/ml] than in control subjects [268 (111-767) pg/ml]. LOX-1 levels positively correlated with IL-6 (r = 0.38, P = 0.0042), TNF-alpha (r = 0.38, P = 0.0037), CRP levels (r = 0.32, P = 0.027) and age (r = 0.25, P = 0.048). In the multivariate analysis TNF-alpha resulted the only independent determinant of LOX-1 serum levels (beta-value = 0.304, P = 0.017). These findings suggest that sLOX-1 levels are up-regulated during CAD progression and are associated with inflammatory markers. The measurement of the circulating soluble form of this receptor may be potentially useful in predicting CAD progression in humans.