Cholesterol Absorption and Synthesis in Vegetarians and Omnivores.

SCOPE: Vegetarian diets are considered health-promoting; however, a plasma cholesterol lowering effect is not always observed. We investigate the link between vegetarian-diet-induced alterations in cholesterol metabolism. METHODS AND RESULTS: We study male and female omnivores, lacto-ovo vegetarians, lacto vegetarians, and vegans. Cholesterol intake, absorption, and fecal sterol excretion are measured as well as plasma concentrations of cholesterol and noncholesterol sterols. These serve as markers for cholesterol absorption, synthesis, and catabolism. The biliary cholesterol secretion rate is estimated. Flux data are related to body weight. Individual vegetarian diet groups are statistically compared to the omnivore group. Lacto vegetarians absorb 44% less dietary cholesterol, synthesized 22% more cholesterol, and show no differences in plasma total and LDL cholesterol. Vegan subjects absorb 90% less dietary cholesterol, synthesized 35% more cholesterol, and have a similar plasma total cholesterol, but a 13% lower plasma LDL cholesterol. No diet-related differences in biliary cholesterol secretion and absorption are observed. Total cholesterol absorption is lower only in vegans. Total cholesterol input is similar under all vegetarian diets. CONCLUSIONS: Unaltered biliary cholesterol secretion and higher cholesterol synthesis blunt the lowered dietary cholesterol intake in vegetarians. LDL cholesterol is significantly lower only in vegans.

The value of surrogate markers to monitor cholesterol absorption, synthesis and bioconversion to bile acids under lipid lowering therapies.

INTRODUCTION: Regulation of cholesterol (Chol) homeostasis is controlled by three main fluxes, i.e. intestinal absorption, de novo synthesis (ChS) and catabolism, predominantly as bile acid synthesis (BAS). High serum total Chol and LDL-Chol concentrations in particular are considered risk factors and markers for the development of atherosclerosis. Pharmaceutical treatments to lower serum Chol have focused on reducing absorption or ChS and increasing BAS. Monitoring of these three parameters is complex involving isotope techniques, cholesterol balance experiments and advanced mass spectrometry based analysis methods. Surrogate markers were explored that require only one single fasting blood sample collection. These markers were validated in specific, mostly physiological conditions and during statin treatment to inhibit ChS. They were also applied under cholesterol absorption restriction, but were not validated in this condition. We retrospectively evaluated the use of serum campesterol (Camp), sitosterol (Sit) and cholestanol (Cholol) as markers for cholesterol absorption, lathosterol (Lath) as marker for ChS and 7α-hydroxycholesterol (7α-OH-Ch) and 27-hydroxycholesterol (27-OH-Ch) as markers for BAS under conditions of Chol absorption restriction. Additionally, their values were corrected for Chol concentration (R_sterol or oxysterols). METHODS: Thirty-seven healthy male omnivore subjects were studied under treatments with placebo (PLAC), ezetimibe (EZE) to inhibit cholesterol absorption, simvastatin (SIMVA) to reduce cholesterol synthesis and a combination of both (EZE+SIMVA). Results were compared to those obtained in 18 pure vegetarian subjects (vegans) whose dietary Chol intake is extremely low. Relative or fractional Chol absorption (FrChA) was measured with the continuous feeding stable isotope procedure, ChS and BAS with the cholesterol balance method. The daily Chol intake (DICh) was inventoried and the daily Chol absorption (DACh) calculated. RESULTS: Monitoring cholesterol absorption, R_Camp, R_Sit and R_Cholol responded sensitively to changes in FrChA. R_Camp correlated well with FrChA in all omnivore treatment groups and in the vegan group. R_Camp confirmed reduced FrChA under EZE treatment and reduced DACh in the vegan subjects. R_Sit and R_Cholol did not accurately reflect FrChA or DACh in all situations. Monitoring endogenous cholesterol synthesis, R_Lath correlated with ChS in the vegan group, but in none of the omnivore treatment groups. R_Lath confirmed increased ChS under EZE treatment and was reduced under SIMVA treatment, while ChS was not. An increased ChS under EZE+SIMVA treatment could not be confirmed with R_Lath. R_Lath responded very insensitively to a change in ChS. Monitoring BAS, R_7α-OH-Ch but not R_27-OH-Ch correlated with BAS during PLAC, EZE and SIMVA treatments. In line with BAS, R_7α-OH-Ch did not differ in any of the omnivore treatment groups. R_7α-OH-Ch responded insensitively to a change in BAS. CONCLUSIONS: Under Chol absorption restriction, serum R_Camp is a sensitive and valid marker to monitor FrChA in a population with a normal DICh. Also, major changes in DACh can be detected in vegans. Serum R_Lath does not reflect ChS measured with the cholesterol balance method during EZE treatment. This result initiates the question whether the measured ChS reflects pure de novo synthesis. Serum R_7α-OH-Ch appears to be a valid but insensitive marker for BAS.

Interferometric broadband Fourier spectroscopy with a partially coherent gas-discharge extreme ultraviolet light source.

Extreme ultraviolet (EUV) spectroscopy is a powerful tool for studying fundamental processes in plasmas as well as for spectral characterization of EUV light sources and EUV optics. However, a simultaneous measurement covering a broadband spectral range is difficult to realize. Here, we propose a method for interferometric broadband Fourier spectroscopy connecting soft x ray and visible spectral ranges with moderate spectral resolution. We present an analytical model to recover the spectrum from a double-slit interferogram. We apply our model for spectral characterization of a partially coherent gas-discharge EUV light source operated with different gases in the spectral range between 10 and 110 nm wavelengths. Our approach allows a simple and fast broadband spectroscopy with fully or partially spatially coherent light sources, for instance, to characterize out-of-band radiation in EUV lithography applications.

Generation of circularly polarized radiation from a compact plasma-based extreme ultraviolet light source for tabletop X-ray magnetic circular dichroism studies.

Generation of circularly polarized light in the extreme ultraviolet (EUV) spectral region (about 25 eV-250 eV) is highly desirable for applications in spectroscopy and microscopy but very challenging to achieve in a small-scale laboratory. We present a compact apparatus for generation of linearly and circularly polarized EUV radiation from a gas-discharge plasma light source between 50 eV and 70 eV photon energy. In this spectral range, the 3p absorption edges of Fe (54 eV), Co (60 eV), and Ni (67 eV) offer a high magnetic contrast often employed for magneto-optical and electron spectroscopy as well as for magnetic imaging. We simulated and designed an instrument for generation of linearly and circularly polarized EUV radiation and performed polarimetric measurements of the degree of linear and circular polarization. Furthermore, we demonstrate first measurements of the X-ray magnetic circular dichroism at the Co 3p absorption edge with a plasma-based EUV light source. Our approach opens the door for laboratory-based, element-selective spectroscopy of magnetic materials and spectro-microscopy of ferromagnetic domains.

The ABCG8 G574R variant, serum plant sterol levels, and cardiovascular disease risk in the Old Order Amish.

OBJECTIVE: To determine whether long-term exposure to moderate elevations in plasma plant sterol levels increases risk for atherosclerosis. METHODS AND RESULTS: In Old Order Amish participants aged 18 to 85 years, with (n=110) and without (n=181) 1 copy of the ABCG8 G574R variant, we compared mean plasma levels of plant sterols and cholesterol precursors and carotid intima-media wall thickness. Carriers of a single 574R allele had increased plant sterol levels (eg, 35%-37% higher plasma levels of sitosterol, campesterol, and stigmasterol) and increased plant sterol/cholesterol ratios (P<0.001 for all). 574R carriers had significantly decreased levels of lathosterol and lanosterol, precursors in a pathway for endogenous cholesterol synthesis, suggesting that plant sterols may alter regulation of genes involved in cholesterol synthesis. The G574R variant was not associated with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol levels. Compared with noncarriers, 574R carriers had decreased carotid intima-media wall thickness (0.62 versus 0.66 mm; age- and sex-adjusted P=0.03). Adjustment for body weight, blood pressure, and standard lipid measures (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides) did not alter this association. CONCLUSIONS: Although the G574R variant is associated with moderately elevated plant sterol levels, carriers of the 574R allele had modestly lower levels of carotid wall thickness compared with noncarriers.

Lifibrol as a model compound for a novel lipid-lowering mechanism of action.

Lifibrol is a potent lipid-lowering drug with an unknown mechanism of action. We investigated its effects on lipoprotein and sterol metabolism in normocholesterolemic male participants. Seven participants were treated for 4 weeks with 600 mg/d lifibrol and 9 with 40 mg/d pravastatin in a double-blind randomized parallel-group trial. Kinetic studies were performed at baseline and under acute and chronic treatment. Turnover of apolipoprotein B-100 was investigated with endogenous stable-isotope labeling, and kinetic parameters were derived by multicompartmental modeling. Lathosterol and cholesterol metabolism were investigated using mass isotopomer distribution analysis (MIDA) after [1-(13)C]acetate labeling. Carbon metabolism was investigated by calculating the total isotope incorporation into newly formed sterols and measuring the disposal of acetate by (13)CO(2) breath analysis. Total- and low-density lipoprotein (LDL) cholesterol decreased by 18% and 27% under lifibrol and by 17% and 28% under pravastatin, respectively, whereas very-low-density lipoprotein (VLDL) cholesterol, triglycerides, and high-density lipoprotein (HDL) cholesterol did not change. Very-low-density lipoprotein apoB fractional synthesis and production increased under lifibrol but remained unchanged under pravastatin. Low-density lipoprotein apoB fractional synthesis and production increased under pravastatin but remained unchanged under lifibrol. Mass isotopomer distribution analysis indicated that both drugs decrease endogenous sterol synthesis after acute administration, but pravastatin had more powerful effects. Carbon-13 appearance in breath was higher during pravastatin than during lifibrol treatment. Mass isotopomer distribution analysis and carbon metabolism analysis indicated compartmentalization at the site of sterol synthesis, thus suggesting differential effects of the 2 drugs. Although having comparable lipid-lowering properties, lifibrol seems to have a mechanism of action distinct from that of statins. Lifibrol could serve as a model compound for the development of new lipid-lowering agents.

Influence of simvastatin on apoB-100 secretion in non-obese subjects with mild hypercholesterolemia.

Statins decrease apoB-100-containing lipoproteins by increasing their fractional catabolic rates through LDL receptor-mediated uptake. Their influence on hepatic secretion of these lipoproteins is controversial. The objective of the study was to examine the influence of simvastatin on the secretion of apoB-100-containing lipoproteins in fasting non-obese subjects. Turnover of apoB-100-containing lipoproteins was investigated using stable isotope-labeled tracers. Multicompartmental modeling was used to derive kinetic parameters. Eight male subjects (BMI 25 +/- 3 kg/m(2)) with mild hypercholesterolemia (LDL cholesterol 135 +/- 30 mg/dL) and normal triglycerides (111 +/- 44 mg/dL) were examined under no treatment (A), under chronic treatment with simvastatin 40 mg/day (B) and after an acute-on-chronic dosage of 80 mg simvastatin under chronic simvastatin treatment (C). Lipoprotein concentrations changed as expected under 40 mg/day simvastatin. Fractional catabolic rates increased in IDL and LDL but not in VLDL fractions versus control [VLDL +35% in B (n.s.) and +21% in C (n.s.); IDL +169% in B (P = 0.08) and +187% in C (P = 0.032); LDL +87% in B (P = 0.025) and +133% in C (P = 0.025)]. Chronic (B) and acute-on-chronic simvastatin treatment (C) did not affect lipoprotein production rates [VLDL -8 and -13%, IDL +47 and +38%, and LDL +19 and +30% in B and C, respectively (all comparisons n.s.)]. The data indicate that simvastatin does not influence the secretion of apoB-100-containing lipoproteins in non-obese subjects with near-normal LDL cholesterol concentrations.

Absence of ApoE upregulates murine brain ApoD and ABCA1 levels, but does not affect brain sterol levels, while human ApoE3 and human ApoE4 upregulate brain cholesterol precursor levels.

Apolipoprotein E (apoE) is a regulator of peripheral cholesterol homeostasis, and the apoE-isoform E4 is a major risk factor for the development of Alzheimer's disease (AD). Accumulating evidence suggests a key role for aberrant cholesterol metabolism in AD. We hypothesized that apoE-deficiency in mice not only affects cholesterol homeostasis in the periphery, but also in the brain, and that this can be restored by astrocyte-specific expression of human apoE3, but not apoE4. Using gas-chromatography mass-spectrometry, we found that absence of apoE in mice does not affect brain cholesterol homeostasis although serum sterol levels increase dramatically, especially when the apoE-knockout mice are fed a high fat diet. We provide evidence suggesting that apoD and the ATP-binding Cassette Transporter A1 (ABCA1) play a compensatory role in the apoE-deficient brain. Surprisingly, astrocyte-specific expression of human apoE3 or apoE4 in brains of apoE-knockout mice significantly increases brain levels of cholesterol and its precursors compared to control mice, indicative of an increased cholesterol synthesis rate in the brain. This increase is independent of the apoE-isoform, suggesting that the detrimental effect of apoE4 on the pathogenesis of AD is unlikely to be due to an apoE-isoform effect on brain cholesterol homeostasis.

Adaptive spatially resolving detector for the extreme ultraviolet with absolute measuring capability.

A spatially resolving detector for the extreme ultraviolet (XUV) and soft x-ray spectral region is presented. Principle of operation is conversion of XUV radiation to visible light by a scintillator crystal. Luminescence is detected using charge coupled device camera and imaging optics. Single layer and multilayer coatings are applied to match the system to different spectral regions of interest. Field of view and spatial resolution can be adapted to the application. Calibration of the system enables to absolutely measure in-band radiation flux on the scintillator. The setup is designed for the characterization and optimization of XUV sources and XUV optical systems. Measurements, carried out to characterize the focus in a soft x-ray microscope, are presented as an application example.

Changes in cholesterol absorption and cholesterol synthesis caused by ezetimibe and/or simvastatin in men.

This study evaluates changes in cholesterol balance in hypercholesterolemic subjects following treatment with an inhibitor of cholesterol absorption or cholesterol synthesis or coadministration of both agents. This was a randomized, double blind, placebo-controlled, four-period crossover study to evaluate the effects of coadministering 10 mg ezetimibe with 20 mg simvastatin (ezetimibe/simvastatin) on cholesterol absorption and synthesis relative to either drug alone or placebo in 41 subjects. Each treatment period lasted 7 weeks. Ezetimibe and ezetimibe/simvastatin decreased fractional cholesterol absorption by 65% and 59%, respectively (P < 0.001 for both relative to placebo). Simvastatin did not significantly affect cholesterol absorption. Ezetimibe and ezetimibe/simvastatin increased fecal sterol excretion (corrected for dietary cholesterol), which also represents net steady state cholesterol synthesis, by 109% and 79%, respectively (P < 0.001). Ezetimibe, simvastatin, and ezetimibe/simvastatin decreased plasma LDL-cholesterol by 20, 38, and 55%, respectively. The coadministered therapy was well tolerated. The decreases in net cholesterol synthesis and increased fecal sterol excretion yielded nearly additive reductions in LDL-cholesterol for the coadministration of ezetimibe and simvastatin.

Compact soft x-ray microscope using a gas-discharge light source.

We report on a soft x-ray microscope using a gas-discharge plasma with pseudo spark-like electrode geometry as a light source. The source produces a radiant intensity of 4 x 10(13) photons/(sr pulse) for the 2.88 nm emission line of helium-like nitrogen. At a demonstrated 1 kHz repetition rate a brilliance of 4.3 x 10(9) photons/(microm2 sr s) is obtained for the 2.88 nm line. Ray-tracing simulations show that, employing an adequate grazing incidence collector, a photon flux of 1 x 10(7) photons/(microm2 s) can be achieved with the current source. The applicability of the presented pinch plasma concept to soft x-ray microscopy is demonstrated in a proof-of-principle experiment.

Vascular effects of diet supplementation with plant sterols.

OBJECTIVES: The purpose of this study was to evaluate vascular effects of diet supplementation with plant sterol esters (PSE). BACKGROUND: Plant sterol esters are used as food supplements to reduce cholesterol levels. Their effects on endothelial function, stroke, or atherogenesis are not known. METHODS: In mice, plasma sterol concentrations were correlated with endothelial function, cerebral lesion size, and atherosclerosis. Plasma and tissue sterol concentrations were measured by gas-liquid chromatography-mass spectrometry in 82 consecutive patients with aortic stenosis. RESULTS: Compared with those fed with normal chow (NC), wild-type mice fed with NC supplemented with 2% PSE showed increased plant sterol but equal cholesterol plasma concentrations. The PSE supplementation impaired endothelium-dependent vasorelaxation and increased cerebral lesion size after middle cerebral artery occlusion. To test the effects of cholesterol-lowering by PSE, apolipoprotein E (ApoE)-/- mice were randomized to Western-type diet (WTD) with the addition of PSE or ezetimibe (EZE). Compared with WTD, both interventions reduced plaque sizes; however, WTD + PSE showed larger plaques compared with WTD + EZE (20.4 +/- 2.1% vs. 10.0 +/- 1.5%). Plant sterol plasma concentration strongly correlated with increased atherosclerotic lesion formation (r = 0.50). Furthermore, we examined plasma and aortic valve concentrations of plant sterol in 82 consecutive patients with aortic stenosis. Patients eating PSE-supplemented margarine (n = 10) showed increased plasma concentrations and 5-fold higher sterol concentrations in aortic valve tissue. CONCLUSIONS: Food supplementation with PSE impairs endothelial function, aggravates ischemic brain injury, effects atherogenesis in mice, and leads to increased tissue sterol concentrations in humans. Therefore, prospective studies are warranted that evaluate not only effects on cholesterol reduction, but also on clinical endpoints.

Moderately elevated plant sterol levels are associated with reduced cardiovascular risk--the LASA study.

Functional foods with supplementation of plant sterols are already used by millions of people. However, at the same time it is current scientific thinking that elevation of plant sterols in the circulation causes coronary heart disease. Therefore, this study aimed to define the risk for coronary heart disease associated with moderately high plant sterol plasma levels in a cohort of elderly. In this study, we evaluated the association between plant sterols and coronary heart disease in a cohort of 1242 subjects older than 65 years, participating at the Longitudinal Aging Study Amsterdam (LASA). Concentrations of sitosterol, campesterol, brassicasterol and stigmasterol were assessed using highly sensitive and specific gas chromatography-mass spectrometry-selected ion-monitoring. Plant sterol concentrations (and their ratios to cholesterol) were slightly, however, significantly lower in patients with coronary heart disease. Moreover, high plasma concentrations of a marker plant sterol, sitosterol, were associated with a markedly reduced risk for coronary heart disease (OR 0.78, CI 0.62-0.98, p<0.05). In contrast neither plant stanols (sitostanol or campestanol) nor the cholesterol synthesis markers (lathosterol, lanosterol and desmosterol) nor their ratios to cholesterol were significantly different in the study groups. These data suggest that plant sterols could have neutral or even protective effects on development of coronary heart disease, which have to be confirmed in interventional trials.

Increased plant sterol and stanol levels in brain of Watanabe rabbits fed rapeseed oil derived plant sterol or stanol esters.

Foods containing plant sterol or stanol esters can be beneficial in lowering LDL-cholesterol concentration, a major risk factor for CVD. The present study examined whether high dietary intake of rapeseed oil (RSO) derived plant sterol and stanol esters is associated with increased levels of these components in brain tissue of homozygous and heterozygous Watanabe rabbits, an animal model for familial hypercholesterolemia. Homozygous animals received either a standard diet, RSO stanol or RSO sterol ester while heterozygous animals were additionally fed with 2 g cholesterol/kg to the respective diet form for 120 d (n 9 for each group). Concentrations of cholesterol, its precursor lathosterol, plant sterols and stanols in brain and additionally in liver and plasma were determined by highly sensitive GC-MS. High-dose intake of RSO derived plant sterols and stanols resulted in increased levels of these components in plasma and liver. In brain a limited uptake of plant sterols and stanols was proven, indicating that these compounds passed the blood-brain barrier and may be retained in the brain tissue of Watanabe rabbits. Plant stanol ester feeding lowered plant sterol levels in brain, liver, and plasma. Cholesterol synthesis in brain, indicated by lathosterol, a local surrogate cholesterol synthesis marker, does not seem to be affected by plant sterol or stanol ester feeding. We conclude that high dose intake of plant sterol and stanol esters in Watanabe rabbits results in elevated concentrations of these components not only in the periphery but also in the central nervous system.

Customary use of plant sterol and plant stanol enriched margarine is associated with changes in serum plant sterol and stanol concentrations in humans.

The consumption of products enriched with plant sterol or stanol esters lowers serum total and LDL-cholesterol concentrations, thereby most likely reducing the risk of coronary heart disease. However, using plant sterol (not plant stanol) enriched products elevates serum plant sterol concentrations in humans. This may be unwanted because health effects of elevated serum plant sterol concentrations are still controversial. Within postlaunch monitoring of functional foods, we compared serum plant sterol and plant stanol concentrations among users of plant sterol (n = 67) or plant stanol (n = 13) enriched margarines with those of matched nonusers (n = 81) in the ongoing Dutch Doetinchem cohort study. Subjects (aged 29-67 y) were examined in 1994-1998 (before the introduction of enriched margarines) and re-examined in 1999-2003. Serum concentrations of plant sterols and stanols were measured in samples from nonfasting subjects by GLC-MS. Intake of plant sterols was 1.1 +/- 0.6 g/d and was associated with a decrease of serum total cholesterol concentration of 0.25 +/- 0.91 mmol/L (4%, P < 0.05), a change that differed (P < 0.05) from the nonsignificant increase in nonusers (+2%, 0.12 +/- 0.78 mmol/L, P = 0.16). Cholesterol-standardized serum sitosterol and campesterol increased in plant sterol users by 22% (P < 0.0001) and 103% (P < 0.0001), respectively. Cholesterol-standardized serum sitostanol and campestanol increased in plant stanol users by 197% (P = 0.02) and 196% (P = 0.01). To our knowledge, these data are the first to show changes in serum cholesterol, plant sterol, and plant stanol concentrations after (long-term) consumption of plant sterol and stanol enriched margarines in a free-living population in a nonexperimental setting. Whether the increased serum sterol concentrations result in adverse side effects needs to be investigated in future postlaunch monitoring studies.

Plasma levels of plant sterols and the risk of coronary artery disease: the prospective EPIC-Norfolk Population Study.

Some studies have suggested that a modest increase of plant sterol levels is a risk factor for coronary artery disease (CAD). We studied the relationship between plant sterol levels and CAD risk in a prospective nested case-control study consisting of 373 cases and 758 controls. Sitosterol and campesterol concentrations did not differ between cases and controls [sitosterol, 0.21 vs. 0.21 mg/dl (P = 0.1); campesterol, 0.31 vs. 0.32 mg/dl (P = 0.5)]. The sitosterol-to-cholesterol ratio was significantly lower in cases than in controls (1.19 vs. 1.29 microg/mg; P = 0.008), whereas the campesterol-to-cholesterol ratio did not differ significantly (1.78 vs. 1.88 microg/mg; P = 0.1). Plant sterol concentrations correlated positively with cholesterol levels and inversely with body mass index and triglyceride and lathosterol concentrations. Among individuals in the highest tertile of the sitosterol concentration, the unadjusted odds ratio (OR) for future CAD was 0.75 [95% confidence interval (CI) = 0.56-1.01]. After adjustment for traditional risk factors, the OR was 0.79 (95% CI = 0.56-1.13). For the campesterol concentration, the unadjusted OR was 0.95 (95% CI = 0.71-1.29) and the adjusted OR was 0.97 (95% CI = 0.68-1.39). In this large prospective study, higher levels of plant sterols, at least in the physiological range, do not appear to be adversely related to CAD in apparently healthy individuals.

The lipid-lowering effect of ezetimibe in pure vegetarians.

Results of previous studies have shown that ezetimibe (10 mg/day) reduces LDL cholesterol in patients with mild hypercholesterolemia on a normal-cholesterol diet (dietary intake of 200-500 mg/day) by 16-22%. However, the LDL cholesterol-lowering effect of ezetimibe in subjects with an extremely low dietary cholesterol intake (vegetarians) has not been studied. We conducted a randomized, double-blind, placebo-controlled, two-phase crossover study in 18 healthy pure vegetarians to assess the effect of ezetimibe (10 mg/day) on plasma lipids, cholesterol absorption, and its synthesis. Treatment periods lasted 2 weeks each, with an intervening 2 week washout period. Fractional cholesterol absorption was determined using the continuous dual stable isotope feeding method. Mean dietary cholesterol intake in the pure vegetarians was extremely low and averaged 29.4 +/- 16.8 and 31.4 +/- 14.4 mg/day during the placebo and ezetimibe administration phases, respectively. Fractional cholesterol absorption during the placebo phase was 48.2 +/- 8.2% and was decreased by 58% during ezetimibe treatment to 20.2 +/- 6.2% (P < 0.001). This change in intestinal cholesterol absorption was followed by a significant reduction in LDL cholesterol of 17.3%. In individuals with extremely low dietary cholesterol intake, treatment with ezetimibe (10 mg/day) leads to a significant reduction of cholesterol absorption and a clinically relevant decrease of plasma LDL cholesterol, comparable to that of subjects with a normal dietary cholesterol intake. Thus, the lipid-lowering effect of ezetimibe is mediated mainly through a reduction of the absorption of endogenous (biliary) cholesterol.

Serum leptin and cytokines in whole blood in relation to clinical and nutritional status in cystic fibrosis.

OBJECTIVES: Leptin plays an important role in the energy balance and may be affected by hormonal and metabolic derangement associated with chronic disease. The aim of this study was to assess the correlation between leptin, proinflammatory cytokines and nutritional status with regard to clinical status in homozygous delta F 508 cystic fibrosis patients. METHODS: Patients with mild (Shwachman score 71-100 points, group A) disease were compared with those with moderate disease (Shwachman score 41-55 points, group B) and age-matched controls (group C, n = 22). Leptin was assessed by enzyme-linked immunosorbent assay and cytokines (interleukin-8, tumor necrosis factor alpha) before and after stimulation with 5 ng lipopolysaccharide by a chemiluminescent immunometric assay. RESULTS: Twenty-two patients were recruited for each group (median A/B/C forced expiratory volume in 1 second 80%/59%/-; median age 12/13.5/12.5 years). Leptin (median 3.25/2.65/3.3 pg/mL; P = 0.083) and body mass index were lower (group A/B/C 18.55/16.75/20.5 kg/m(2); P = 0.023), but dietary intake was significantly higher (group A/B/C 50.5/68/43 kcal/kg body weight; P = 0.026) in moderate disease. Cytokines before stimulation with lipopolysaccharide were highest in moderate disease, but there was no significant difference after stimulation (interleukin-8 median A/B/C before--15/25.1/8.0 pg/mL, P < 0.005; after--570.5/573.5/415.5 pg/mL, not significant; tumor necrosis factor alpha median A/B/C 43/56/30 pg/mL, P < 0.0001; 580/427/720.5 pg/mL, not significant.). CONCLUSIONS: There is a physiological regulation of leptin even in more advanced states of disease with significantly lower body mass index than controls. However, our data do not support the idea of elevated cytokine levels inducing anorexia in homozygous delta F 508 cystic fibrosis patients.

A complex plasma plant sterol locus on mouse chromosome 14 has at least two genes regulating intestinal sterol absorption.

We previously identified two inbred mouse strains, C57BL/6J and CASA/Rk, with different plasma plant sterol levels. An intercross between these strains revealed a broad plasma plant sterol locus on chromosome 14, which peaked at 17 centimorgan (cM) with a maximum logarithm of the odds score of 9.9. Studies in a chromosome 14 congenic strain, 14KK, with a 4-60 cM CASA/Rk interval on the C57BL/6J background revealed that males, but not females, had decreased plasma plant sterol levels and intestinal cholesterol absorption. In two subcongenic strains, 14PKK and 14DKK, with 4-19.5 and 19.5-60 cM CASA/Rk intervals, respectively, both males and females had decreased plasma plant sterol levels and decreased intestinal cholesterol absorption. Compatible with the decreased plasma plant sterol phenotype, 14PKK mice had increased biliary plant sterol excretion, whereas 14DKK mice did not. Therefore, gender-dependent interactions of genes at the 14PKK and 14DKK intervals are likely to underlie the 14KK interval effect on plasma plant sterol levels and sterol absorption from the intestine. These studies confirm the plasma plant sterol locus on mouse chromosome 14 and provide evidence that there are at least two sets of genes operating: one set affecting intestinal sterol absorption and biliary excretion, and the other set mainly affecting intestinal sterol absorption.

Impact of the SLCO1B1 polymorphism on the pharmacokinetics and lipid-lowering efficacy of multiple-dose pravastatin.

BACKGROUND AND OBJECTIVE: The polymorphism of SLCO1B1 (solute carrier organic anion transporter family, member 1B1), encoding the hepatic uptake transporter organic anion transporting polypeptide 1B1, has been associated with increased pravastatin concentrations in single-dose studies. We have investigated whether this polymorphism influences the pharmacokinetics and lipid-lowering efficacy of multiple-dose pravastatin. METHODS: A prospective, parallel-group study of 16 healthy volunteers, including 8 carriers of an SLCO1B1 variant haplotype and 8 control subjects, was carried out. Pravastatin pharmacokinetics and reduction in total and low-density lipoprotein (LDL) cholesterol concentrations were analyzed after treatment with 40 mg pravastatin daily for 3 weeks. RESULTS: The mean area under the plasma concentration-time curve of pravastatin was 110% higher (305.0 +/- 149.4 ng . h/mL [mean +/- SD] versus 144.9 +/- 48.2 ng . h/mL, P = .012) and the mean peak concentration in plasma was 231% higher (174.5 +/- 98.6 ng/mL versus 52.7 +/- 22.1 ng/mL, P = .0042) in the SLCO1B1 variant haplotype group than in the control group. Pravastatin significantly reduced the concentrations of total and LDL cholesterol in both groups. The mean percentage reduction in total cholesterol concentration was 13.1% +/- 9.1% and 19.1% +/- 8.3% in the variant and control groups, respectively (P = .19; 95% confidence interval of difference between groups, -15.3% to 3.3%). The mean percentage reduction in LDL cholesterol concentration was 27.7% +/- 8.3% in the variant group and 32.3% +/- 11.2% in the control group (P = .37; 95% confidence interval for difference, -15.1% to 6.0%). CONCLUSIONS: Despite considerably higher plasma pravastatin concentrations in carriers of an SLCO1B1 variant haplotype, there was no significant difference in the lipid-lowering efficacy of pravastatin between the variant haplotype and control groups. However, this pilot study had sufficient statistical power to detect only a large difference in lipid response between the 2 groups. Further clinical studies are warranted to characterize the impact of the SLCO1B1 polymorphism on the lipid response to pravastatin.