Regulation of ATP-binding cassette transporters and cholesterol efflux by glucose in primary human monocytes and murine bone marrow-derived macrophages.

Individuals with type 2 diabetes mellitus are at increased risk of developing atherosclerosis. This may be partially attributable to suppression of macrophage ATP-binding cassette (ABC) transporter mediated cholesterol efflux by sustained elevated blood glucose concentrations. 2 models were used to assess this potential relationship: human monocytes/leukocytes and murine bone marrow-derived macrophages (BMDM).10 subjects (4 F/6 M, 50-85 years, BMI 25-35 kg/m²) underwent an oral glucose challenge. Baseline and 1- and 2-h post-challenge ABC-transporter mRNA expression was determined in monocytes, leukocytes and peripheral blood mononuclear cells (PBMC). In a separate study, murine-BMDM were exposed to 5 mmol/L D-glucose (control) or additional 20 mmol/L D- or L-glucose and 25 ug/mL oxidized low density lipoprotein (oxLDL). High density lipoprotein (HDL)-mediated cholesterol efflux and ABC-transporter (ABCA1 and ABCG1) expression were determined.Baseline ABCA1and ABCG1 expression was lower (>50%) in human monocytes and PBMC than leukocytes (p<0.05). 1 h post-challenge leukocyte ABCA1 and ABCG1 expression increased by 37% and 30%, respectively (p<0.05), and began to return to baseline thereafter. There was no significant change in monocyte ABC-transporter expression. In murine BMDM, higher glucose concentrations suppressed HDL-mediated cholesterol efflux (10%; p<0.01) without significantly affecting ABCA1 and ABCG1 expression. Data demonstrate that leukocytes are not a reliable indicator of monocyte ABC-transporter expression.Human monocyte ABC-transporter gene expression was unresponsive to a glucose challenge. Correspondingly, in BMDM, hyperglycemia attenuated macrophage cholesterol efflux in the absence of altered ABC-transporter expression, suggesting that hyperglycemia, per se, suppresses cholesterol transporter activity. This glucose-related impairment in cholesterol efflux may potentially contribute to diabetes-associated atherosclerosis.

Effects of apolipoprotein A-IV genotype on glucose and plasma lipoprotein levels.

The effects of apolipoprotein (apo) A-IV genotype on serum glucose, total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglyceride and glucose concentrations were ascertained in a population of 373 men and 361 women with a mean age of about 57 years. Subjects were evaluated at entry into a lifestyle intervention program. Apolipoprotein A-IV genotype variations at residues 347 and 360 were examined, as these mutations affect the sequence of apo A-IV, a major protein constituent of intestinal triglyceride-rich lipoprotein and HDL. With regard to the apo A-IV 360 mutation, 16.4% of the females and 13.4% of the males carried the apo A-IV 2-allele, almost entirely in the heterozygous state. No effect of the apo A-IV 1/2 genotype was observed in either men or women on total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride, the total cholesterol (TC)/HDL ratio, or on A-I, A-IV and apo B levels. This was also the case for the apo A-IV 347 mutation. However, women with the apo A-IV 360 1/2 genotype had significantly (p < 0.005) higher glucose levels (105.5 mg/dl) compared with the 1/1 wild-type (94.0 mg/dl). All analyses were also adjusted for age, body mass index, medications, alcohol use and cigarette smoking. The prevalence of the 347 mutation was somewhat higher than the 360 mutation, with 29% of the females and 32.0% of the males being heterozygous for this mutation, and 3.9% of the females and 5.4% of the males being homozygous for this mutation. These data are consistent with the concept that the apo A-IV 360 and 347 genotypes have no significant effect on apo A-IV levels and other lipid parameters in either gender. However, apo A-IV 360 1/2 genotype did have a significant effect on serum glucose levels in women.

Effects of apolipoprotein A-I genetic variations on plasma apolipoprotein, serum lipoprotein and glucose levels.

The present authors investigated the individual and combined associations of the apolipoprotein (apo) A-I -75 bp and +83 bp polymorphisms with plasma lipid, lipoprotein and apolipoprotein levels in 734 Caucasian men and women. The frequency of the A allele at position -75 bp (G-->A) was 0.14 in women and 0.17 in men. The frequencies for the rare M2 allele at position +83 bp and/or 84 bp (C-->T and G-->A, respectively) were 0.04 and 0.05 in women and men, respectively. In women, the A allele was associated with significantly higher levels of apo B (P = 0.016), total cholesterol (TC) (P = 0.005), low-density lipoprotein cholesterol (LDL-C) (P = 0.018) and TC:high-density lipoprotein (HDL) ratio (P = 0.026) compared to the G/G subjects. In men, no significant associations were detected between the -75 bp polymorphism and any lipid trait examined. The M2 allele for the +83 bp polymorphism was significantly associated in men with higher levels of apo A-I (P = 0.002) and TC (P = 0.046). In women, a significant effect was observed for TC (P = 0.036), with M2+/- subjects having lower levels than M2+/+ subjects. Significant linkage disequilibrium (P = 0.037) between the apo A-I -75 bp and +83 bp polymorphisms was detected. Women carrying both rare alleles (G/A M2+/-) had significantly higher TC:HDL ratios (P = 0.031) compared to the other haplotypes. In men, significant differences were observed for apo A-I (P = 0.021) and TC (P = 0.044), with carriers of the G/G M2+/- haplotype having the highest values compared to other genotype combinations. In conclusion, the -75 bp (G/A) polymorphism appears to have a significant effect on levels of apo B, plasma TC and LDL-C in women, while the +83 bp polymorphism seems to affect the apo A-I levels in men, and the plasma cholesterol levels in both genders.

Two novel mutations in the sterol 27-hydroxylase gene causing cerebrotendinous xanthomatosis.

Cerebrotendinous xanthomatosis (CTX) is a rare recessive autosomal disease caused by mutations of the sterol 27-hydroxylase gene. Clinically, CTX is characterized by tendon xanthomas, cataracts and progressive neurological deficits. Because of the disruption of the 27-hydroxylase activity, CTX patients have elevated plasma levels of cholestanol, a by-product of abnormal bile acid synthesis. The present authors describe a female patient with CTX. The proband in this study presented with elevated cholestanol levels, markedly reduced mitochondrial 27-hydroxylase activity and altered bile acid composition. The 27-hydroxylase gene was analysed for mutations by polymerase chain reaction amplification of the exons and the splice-junction regions of the gene. The proband was found to be a compound heterozygote for two different mutations which have not been previously described: (1) a G --> A transition at nucleotide 455 that is responsible for converting a glycine to a glutamic acid residue at amino acid position 112 (G112E); and (2) a five-nucleotide deletion in exon 5 (from nucleotide 965 to 969) that is responsible for a shift in the reading frame and the insertion of a premature codon at position 296, and consequently, the synthesis of a truncated protein lacking the heme-binding and andrenodoxin-binding domains. Long-term (18-year) treatment of the proband with chenodeoxycholic acid (750 mg day-1) has been effective in preventing any progression of the disease.

Complete and selective estrogenic effects on lipids and cardiovascular disease.

Observational studies have shown a protective effect of estrogen replacement on risk of cardiovascular disease in postmenopausal women. The estrogen protection is thought to be mediated by mechanisms acting at different levels, including a beneficial effect on plasma lipid concentrations. Selective estrogen receptor modulators (SERM) share with estrogen the ability to reduce plasma levels of atherogenic lipoproteins like low-density lipoproteins and lipoprotein(a). The recent publication of the first randomized, placebo-controlled trial of estrogen/progestin replacement (HERS), which failed to show a reduced number of cardiovascular events in women randomized to estrogen treatment as compared with placebo, has cast some doubts on the protective role of estrogen. Other large randomized studies on the effect of estrogen and other compounds with estrogenic activity (eg, SERM) on cardiovascular disease risk are currently underway and will provide more definite answers to both clinicians and postmenopausal women.

Genistein activates apolipoprotein A-I gene expression in the human hepatoma cell line Hep G2.

Soy phytoestrogens have been shown to increase plasma levels of HDL cholesterol and apolipoprotein (apo) A-I, its major protein component, in animal studies and in some human studies. The human hepatoma cell line Hep G2 was used to study the effect of the phytoestrogens genistein and daidzein on apo A-I secretion and gene expression in liver cells. Both genistein and daidzein increased apo A-I secretion in a dose-dependent fashion. Apo A-I concentration in the media of treated cells was increased approximately fivefold by 10 micromol/L genistein (P: < 0.001) and approximately onefold by 10 micromol/L daidzein (P: < 0.001) compared with control cells. The effect of genistein on apo A-I secretion was similar to that observed with 17-beta-estradiol. Treatment of cells with genistein for 24 h increased the transcriptional activity of the apo A-I gene as measured by nuclear run-on assay. Transfection experiments with plasmids containing regulatory regions of the apo A-I gene cloned in front of the luciferase reporter gene indicated that the 5' region of the apo A-I gene contained between nucleotides -256 and -41 is responsible for the increased expression of this gene by genistein.

Apolipoprotein A-I and A-II kinetic parameters as assessed by endogenous labeling with [(2)H(3)]leucine in middle-aged and elderly men and women.

The purpose of our study was to investigate high density lipoprotein (HDL) apolipoprotein (apo) A-I and apoA-II kinetics in a state of constant feeding after a primed-constant infusion of [5,5, 5-(2)H(3)]L-leucine in 32 normolipidemic older men and postmenopausal women (aged 41 to 79 years). ApoA-I and apoA-II were isolated from plasma HDL, and enrichment was determined by gas chromatography/mass spectrometry. The fractional secretion rate was obtained by using a monoexponential equation calculated with the SAAM II program (Department of Bioengineering, University of Washington, Seattle). Mean HDL cholesterol (HDL-C) and total triglyceride levels were 23% higher and 27% lower, respectively, in women than in men. Mean plasma apoA-I levels were 10% greater in women than in men, whereas mean apoA-II levels were similar. HDL size, estimated by gradient-sizing gels and by the HDL-C/apoA-I+apoA-II ratio, was significantly higher in women than in men. Mean apoA-I secretion rates (SRs) were similar in men and women (12.28+/-3.64 versus 11.96+/-2.92 mg/kg per day), whereas there was a trend toward a lower (-13%) apoA-I fractional catabolic rate (FCR) in women compared with men (0.199+/-0.037 versus 0. 225+/-0.062 pools per day, P=0.11). Mean apoA-II SRs (2.21+/-0.57 versus 2.27+/-0.91 mg/kg per day) and FCRs (0.179+/-0.034 versus 0. 181+/-0.068 pools per day) were similar in men and women. For the group as a whole, there was an inverse association between the HDL-C/apoA-I+apoA-II ratio and apoA-I FCR and between the ratio and triglyceride levels. Plasma levels of apoA-I and apoA-II were correlated with their respective SRs but not FCRs. These data suggest a major role for apoA-I and apoA-II SRs in regulating the plasma levels of these proteins, whereas apoA-I FCR might be an important factor contributing to the differences in apoA-I levels between men and postmenopausal women. Moreover, plasma triglyceride levels are important determinants of HDL size and apoA-I catabolism.

Estrogen increases apolipoprotein (apo) A-I secretion in hep G2 cells by modulating transcription of the apo A-I gene promoter.

Estrogen administration to postmenopausal women has been shown to increase plasma levels of apolipoprotein (apo) A-I. A human hepatoma cell line, Hep G2, was used to test the hypothesis that estrogen increases the hepatic production of apo A-I by modulating gene expression. When Hep G2 cells were treated for 24 hours with E(2), the apo A-I content in the medium increased 4.3+/-1.0-fold at 10 micromol/L E(2) and 1.8+/-0.4-fold at 1 micromol/L E(2) compared with untreated cells. A time-course experiment indicated that there was no E(2)-dependent (10 micromol/L) increase in apo A-I medium content at 1 hour and 2 hours and that apo A-I was 165% of controls at 6 hours and 440% at 24 hours. Hep G2 cells were transfected, by the cationic lipid method, with constructs containing serial deletions of the 5' region of the apo A-I gene (-41/+397, -256/+397, and -2500/+397) cloned in front of the luciferase gene and with or without a 7-kb region spanning the apo C-III/A-IV intergenic region, which has been shown to contain regulatory elements for the expression of the apo A-I gene. With the exception of the construct containing only the basal promoter (-41/+397), the expression of all constructs was 2- to 3-fold greater in the presence of E(2). The smallest construct that maintained E(2) responsiveness, the -256/+397 construct, does not contain a typical estrogen-responsive element. In the same transfection experiments, the 4-fold increase in apo A-I in the culture medium was preserved. However, when the same set of transfections was performed by the calcium phosphate precipitation method, the E(2) effect on the apo A-I content in the culture medium and on transcription activation was nearly abolished. This effect was probably mediated by Ca(2+), because incubation of cells with 20 mmol/L CaCl(2) abolished the E(2) response. In conclusion, E(2) increases apo A-I production in hepatic cells by increasing the transcription of the apo A-I gene.

Dietary restriction of saturated fat and cholesterol decreases HDL ApoA-I secretion.

We examined the mechanisms responsible for the decrease in HDL cholesterol (HDL-C) levels after the consumption of a diet low in total fat, saturated fat, and cholesterol. Twenty-one subjects with a mean age of 58+/-12 years were placed on a baseline isocaloric diet (15% protein, 49% carbohydrate, 36% fat, and 150 mg/1000 kcals of cholesterol) and then switched to an NCEP Step 2 diet (15% protein, 60% carbohydrate, 25% fat, and 45 mg/1000 kcals of cholesterol). After 6 or 24 weeks on each diet, subjects received a 15-hour primed-constant infusion of [5,5,5-2H3]-L-leucine. HDL apoA-I and apoA-II tracer curves were determined by gas chromatography-mass spectrometry and fitted to a monoexponential equation. Compared with the baseline diet, consumption of the Step 2 diet lowered HDL-C mean levels by 15% (1.03+/-0.23 to 0.88+/-0.16 mmol/L, P<0.001), apoA-I by 12% (1.25+/-0.15 to 1.10+/-0.13 g/L, P<0. 001) and the TC/HDL-C ratio by 5% (0.145+/-0.04 to 0.137+/-0.03). No significant changes were observed in apoA-II levels and HDL particle size with diet. HDL apoA-I fractional catabolic rate did not change (0.219+/-0.052 to 0.220+/-0.043 pools/day, P=0.91) but HDL apoA-I secretion rate decreased by 8% (12.26+/-3.07 to 10.84+/-2.11 mg. kg-1. day-1, P=0.03) during consumption of the Step 2 diet. There was no effect of diet on apoA-II fractional catabolic rate or secretion rate. Our results indicate that the decrease in HDL-C and apoA-I levels during the isocaloric consumption of a Step 2 diet paralleled the reductions in apoA-I secretion rate.

Comparison of the effects of pravastatin and lovastatin on sleep disturbance in hypercholesterolemic subjects.

We have studied the effects of two cholesterol-lowering medications, lovastatin and pravastatin, on different sleep parameters in hypercholesterolemic subjects. These medications are 3-hydroxy-methylglutaryl coenzyme A inhibitors. Only subjects who had complained of sleep disturbance while on previous treatment with lovastatin were enrolled. Sixteen subjects (11 men and 5 women) underwent a randomized, double-blind, three-way crossover treatment with lovastatin, pravastatin, and placebo. Each phase of the study lasted 4 weeks. A placebo wash-out period of 4 weeks separated each treatment phase. At the end of each treatment phase, subjects were admitted to the sleep laboratory for 2 consecutive nights. No statistical differences were detected during treatment with lovastatin, pravastatin, and placebo for sleep parameters such as total sleep time, total awake time, wake time after sleep onset, efficiency of sleep, and percent of different phases of sleep. Our study suggests that lovastatin and pravastatin do not have a significant effect on sleep parameters in hypercholesterolemic subjects that could explain their complaints of insomnia. Nevertheless, the subjects did have moderate sleep disturbances that could account for insomnia and most likely predate the use of HMG-CoA reductase inhibitors.

Plasma lipoproteins as carriers of phylloquinone (vitamin K1) in humans.

The purpose of this study was to characterize the absorption and transport of phylloquinone (vitamin K1) by plasma lipoproteins. Twenty-six healthy subjects (11 men and 15 women) aged 20-78 y received phylloquinone in the amount of either 1.43 or 50 microg/kg body wt orally with a fat-rich meal containing 1.0 g/kg body wt of fat, carbohydrate, and protein and 7.0 mg cholesterol/kg body wt. Blood was obtained at baseline (0 h) and 3, 6, 9, and 12 h after the meal for the measurement of plasma lipid and phylloquinone concentrations in plasma and lipoprotein subfractions. In both groups of subjects, triacylglycerol concentrations peaked after 3 h in plasma and in the triacylglycerol-rich lipoprotein fraction, composed of chylomicrons and VLDLs. Plasma phylloquinone concentrations peaked at 6 h. At baseline and during the postprandial phase, > 53% of plasma phylloquinone was carried by the triacylglycerol-rich lipoprotein fraction. In 9 of the 11 subjects supplemented with 50 microg phylloquinone/kg, plasma lipoproteins were isolated by sequential ultracentrifugation. In these subjects the fraction of plasma phylloquinone carried by LDLs and by HDLs increased progressively from 3% and 4% at 3 h to 14% and 11% at 12 h, respectively. Our data indicate that whereas triacylglycerol-rich lipoproteins are the major carriers of phylloquinone, LDL and HDL may carry small fractions of this vitamin.

Individual variability in lipoprotein cholesterol response to National Cholesterol Education Program Step 2 diets.

The effects of National Cholesterol Education Program (NCEP) Step 2 diets on plasma lipoprotein profiles in 72 men [mean (+/- SD) age: 44 +/- 15 y, range: 19-81 y] and 48 women (mean age: 50 +/- 21 y, range: 21-78 y) participating in five previously published studies were examined. Subjects were placed on a baseline diet similar to an average American diet (35-41% total fat, 13-16% saturated fat, 31-45 mg cholesterol/MJ) and then on an NCEP Step 2 diet (18-29% total fat, 4-7% saturated fat, 11-20 mg cholesterol/MJ) under isoenergetic conditions. All food and drink were provided. Compared with the baseline diet, consumption of the NCEP Step 2 diets was associated with significant decreases in concentrations of low-density-lipoprotein (LDL) cholesterol (-18.9% and -15.6%, respectively) and high-density-lipoprotein (HDL) cholesterol (-17.0% and -11.2%, respectively) in both men and women. Men with the apolipoprotein (apo) E 3,4 phenotype had a significantly greater decrease in LDL cholesterol (-24.2%) with the NCEP Step 2 diets than men with the apo E 3,3 phenotype (-17.7%). Men with the apo A-IV 1,2 phenotype tended to have less LDL cholesterol lowering (-12.8%) than men with the apo A-IV 1,1 phenotype (-19.6%), but this difference was not significant. No differences were seen by apo E and A-IV phenotype in women. A large variability in lipid response to the diet was observed, with changes in LDL cholesterol ranging from +3% to -55% in men and and from +13% to -39% in women. Forty-eight percent of the variability in LDL-cholesterol response (in mmol/L) to the diet could be accounted for by baseline LDL concentrations and age in men, and 13% by age in women.

Impact of body mass index on coronary heart disease risk factors in men and women. The Framingham Offspring Study.

Increased body weight has been associated with an increased risk of morbidity and mortality from coronary heart disease (CHD) in several populations. We studied the distribution of body mass index (BMI, kg/m2) in men (n = 1566; mean age, 49 +/- 10 years) and women (n = 1627; mean age, 49 +/- 10 years) participating in the third examination cycle of the Framingham Offspring Study and the association of BMI with known CHD risk factors. In men, BMI increased with age until age 50 years, when it reached a plateau. In women, there was a trend toward an increase in BMI with age up to the seventh decade of life. Seventy-two percent of men and 42% of women had a BMI > or = 25.00, the cutoff point for the definition of overweight. In age-adjusted analyses, BMI was significantly and linearly associated with systolic blood pressure, fasting glucose levels, plasma total cholesterol, VLDL cholesterol, and LDL cholesterol levels and was inversely and linearly associated with HDL cholesterol levels (P < .001) in nonsmoking men and women. The association between BMI and apolipoprotein B and A-I was similar to that of LDL and HDL cholesterol, respectively. LDL size was also linearly associated with BMI: subjects with higher BMI had smaller LDL particles. Lipoprotein(a) levels were not associated with BMI in this population. Of all these risk factors for CHD, reduced HDL cholesterol levels and hypertension were those more strongly associated with higher BMI in both men and women. Elevated triglyceride levels and small LDL particles, and diabetes in women, were also strongly associated with higher BMI values in this population. Our results indicate that a high prevalence of adult Americans are overweight and support the concept that increased BMI is associated with an adverse effect on all major CHD risk factors. These results emphasize the importance of excess body fat as a public health issue.

Effects of regular and extended-release gemfibrozil on plasma lipoproteins and apolipoproteins in hypercholesterolemic patients with decreased HDL cholesterol levels.

We have studied, in a prospective blinded fashion, the effects of regular and extended-release gemfibrozil on plasma lipoprotein and apolipoprotein (apo) levels in hypercholesterolemic subjects with decreased high density lipoprotein (HDL) cholesterol (C) levels. Study participants were men and women 19 to 80 years of age with baseline plasma low density lipoprotein (LDL) C levels > or = 4.5 mmol/l (175 mg/dl), HDL-C levels < or = 1.2 mmol/l (45 mg/dl), and triglyceride levels < or = 3.4 mmol/L (300 mg/dl). All subjects were stabilized on a diet for eight weeks prior to entry into two different protocols. In the first protocol 229 subjects were randomized to placebo or extended-release gemfibrozil (1200 mg/day) for 3 months (placebo trial). In the second protocol 655 subjects were randomized to regular or extended-release gemfibrozil (1200 mg/day) for 6 months (equivalency trial). Changes in lipids and apos were stratified by baseline HDL-C levels (< 0.9 mmol/l, and 0.9-12.2 mmol/l). In both studies, treatment with gemfibrozil, either regular or extended-release, was associated with significant (P < 0.05) decreases in plasma very low density lipoprotein (VLDL) C and triglyceride levels of 42-45% and 33-37%, respectively, in subjects with HDL-C level < 0.9 mmol/l, and of 38-47% and 32-39%, respectively, in patients with HDL-C levels of 0.9-1.2 mmol/l. Modest reductions from baseline in directly measured LDL-C levels were observed in both groups (3-6% and 8-9%, respectively). These reductions were less than those observed for calculated LDL-C (7-10% and 11%, respectively). For apo B, reductions were 11-14% and 16-17% in the two groups. HDL-C, apo A-I, and apo A-II levels increased by 15-16%, 5-6%, and 21-25%, respectively, in patients with HDL-C < 0.9 mmol/l, and by 6-7%, 2-3%, and 19-22%, respectively, in patients with HDL-C of 0.9-1.2 mmol/l. These differences in HDL-C levels reached statistical significance in the equivalency trial (P < 0.0001) and were independent of baseline triglyceride levels. Our data indicate that gemfibrozil, either regular or extended-release, is highly effective in lowering plasma triglyceride levels and increases HDL-C levels by approximately 15% in hypercholesterolemic patients with low HDL-C levels (< 0.9 mmol/l). Moreover, this agent lowers VLDL-C somewhat more than triglyceride, resulting in an underestimation of calculated VLDL-C reductions and in an overestimation of calculated LDL-C reductions. This agent also raises apo A-II levels much more than apo A-I levels.

Effects of National Cholesterol Education Program Step 2 diets relatively high or relatively low in fish-derived fatty acids on plasma lipoproteins in middle-aged and elderly subjects.

The effects of two National Cholesterol Education Program (NCEP) Step 2 diets (< or = 30% of energy as total fat, < 7% of energy as saturated fat, and < 200 mg cholesterol/d), one relatively high and the other relatively low in fish-derived fatty acids, on plasma lipoprotein concentrations and blood pressure were compared in 22 men and women with a mean (+/- SD) age of 63 +/- 10 y. Subjects were placed on a baseline diet similar to the diet currently consumed in the United States (35% of energy as total fat, 14% of energy as saturated fat, 35 mg cholesterol/MJ) for 6 wk and then on either an NCEP Step 2 diet relatively high in fish (Step 2 high-fish, n = 11) or relatively low in fish (Step 2 low-fish, n = 11) for 24 wk. All food and drinks were provided. Compared with baseline values, consumption of both the Step 2 high-fish and the Step 2 low-fish diets under weight-stable conditions was associated with significant decreases in plasma concentrations of total cholesterol (-14% and -19%, respectively), low-density-lipoprotein (LDL) cholesterol (-15% and -20%, respectively), and high-density-lipoprotein (HDL) cholesterol (-11% and -17%, respectively). Postprandial, but not fasting, triacylglycerol concentrations were significantly reduced during consumption of the Step 2 high-fish diet. There were no significant changes in these indexes after consumption of the Step 2 low-fish diet compared with the baseline diet. LDL particle size decreased significantly (-12%) only in subjects on the Step 2 low-fish diet. Both Step 2 diets caused small but significant reductions in diastolic blood pressure. Our results indicate that NCEP Step 2 diets relatively high or relatively low in fish are both effective in significantly reducing total and LDL-cholesterol concentrations without changes in the ratio of total cholesterol to HDL cholesterol under controlled weight-stable conditions in middle-aged and elderly subjects. A beneficial effect on diastolic blood pressure was also observed.

Body weight and low-density lipoprotein cholesterol changes after consumption of a low-fat ad libitum diet.

OBJECTIVE: To assess the effects of a diet restricted in fat, saturated fat, and cholesterol, under weight-maintenance and ad libitum conditions on body weight and plasma lipid levels in hypercholesterolemic subjects. DESIGN: Dietary intervention study. SETTING AND PARTICIPANTS: Twenty-seven free-living, healthy middle-aged and elderly men (n = 13, age range, 41 to 81 years) and women (n = 14, age range, 52 to 79 years) with moderate hypercholesterolemia (low-density lipoprotein cholesterol [LDL-C] > or = 3.36 mmol/L [130 mg/dL]) participated in the study. INTERVENTION: Subjects underwent three dietary phases. First, subjects were provided with a diet similar to the average US diet (baseline diet; 35.4% total fat, 13.8% to 14.1% saturated fat, and 30 to 35 mg/1000 kJ [128 to 147 mg/1000 kcal] cholesterol). During the second dietary phase, subjects consumed a low-fat diet (15.1% total fat, 5.0% saturated fat, 17 mg/1000 kJ [73 mg/1000 kcal] cholesterol). During the baseline and low-fat diet phases, which lasted 5 to 6 weeks each, the energy intake was adjusted to keep body weight constant. During the third diet phase (low-fat ad libitum diet) subjects were given the same low-fat diet for 10 to 12 weeks, but could adjust their intake between 66% and 133% of the energy required to maintain body weight. MAIN OUTCOME MEASURES: Body weight and plasma lipid levels. RESULTS: Consumption of the low-fat diet under weight-maintenance conditions had significant lowering effects on plasma total cholesterol (TC), LDL-C, and high-density lipoprotein cholesterol (HDL-C) levels (mean change, -12.5%, -17.1%, and -22.8%, respectively). This diet significantly increased plasma triglyceride levels (+47.3%) and the TC/HDL-C ratio (+14.6%). In contrast, consumption of the low-fat ad libitum diet was accompanied by significant weight loss (3.63 kg), by a mean decrease in LDL-C (124.3%), and by mean triglyceride levels and TC/HDL-C ratio that were not significantly different from values obtained at baseline. CONCLUSIONS: Our results indicate that a low-fat ad libitum diet promotes weight loss and LDL-C lowering without adverse effects on triglycerides or the TC/HDL-C ratio in middle-aged and elderly men and women with moderate hypercholesterolemia.

Efficacy of a National Cholesterol Education Program Step 2 diet in normolipidemic and hypercholesterolemic middle-aged and elderly men and women.

We tested the effects of a National Cholesterol Education Program (NCEP) Step 2 diet (30% of calories or less as total fat, less than 7% saturated fat, and less than 200 mg cholesterol per day) on plasma lipid levels in normocholesterolemic and hypercholesterolemic middle-aged and elderly men and women. Thirty-two subjects were studied. Eight normolipidemic subjects (6 men and 2 women, mean age 56 +/- 13 years) with LDL cholesterol levels of less than 4.14 mmol/L (160 mg/dL) were given a baseline diet similar in composition to the diet currently consumed in the United States (35% of calories as total fat and 14% as saturated fat, with 147 mg cholesterol per 1000 kcal) for 6 weeks. Subjects were then placed on an NCEP Step 2 diet (26% total fat, 4% saturated fat, 45 mg cholesterol per 1000 kcal) for 24 weeks. In addition, 24 subjects (12 men and 12 women, mean age 62 +/- 12 years) with moderate hypercholesterolemia (LDL cholesterol levels of 4.14 mmol/L or above) were given a baseline diet for 6 weeks and then the NCEP Step 2 diet for 6 weeks. Energy intakes were adjusted to keep body weight constant throughout the study. In both normolipidemic and hypercholesterolemic subjects, consumption of the NCEP Step 2 diet was associated with significant changes in levels of total cholesterol (-20% and -16%, respectively), LDL cholesterol (-21% and -18%, respectively), and HDL cholesterol (-16% and -15%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in plasma lipoprotein concentrations and composition in response to a low-fat, high-fiber diet are associated with changes in serum estrogen concentrations in premenopausal women.

We have investigated the effects of a low-fat, high-fiber diet on plasma lipid and lipoprotein levels and serum sex hormone concentrations in 22 normal premenopausal women (mean age, 25.8 +/- 3.8 years). Participants consumed a baseline diet for 4 weeks (40% of calories as fat, 16% as saturated fatty acids, 8% as polyunsaturated fatty acids, 400 mg/d cholesterol, and 12 g/d dietary fiber) and then a low-fat, high-fiber diet for 8 to 10 weeks (16% to 18% of calories as fat, 4% as saturated fatty acids, 4% as polyunsaturated fatty acids, 150 mg/d cholesterol, and 40 g/d fiber). Blood samples for determination of plasma lipids and serum hormones were obtained during the follicular and luteal phases of the menstrual cycle during both diets. Compared with the baseline diet, the low-fat, high-fiber diet resulted in significant decreases in total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol concentrations during both the follicular and luteal phases (TC, -14% and -16%; LDL cholesterol, -14% and -17%; and HDL cholesterol, -15% and -18%, respectively). During the follicular phase but not the luteal phase on the low-fat, high-fiber diet, women exhibited significant increases in plasma triglyceride ([TG] 22%) and very-low-density lipoprotein (VLDL)-TG (36%) concentrations. During the follicular phase, serum estrone sulfate concentrations decreased by 25% (P < .0001) when subjects were fed the low-fat, high-fiber diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipoproteins, nutrition, aging, and atherosclerosis.

Coronary heart disease (CHD) risk increases markedly with age in both men and women. Major risk factors for CHD in addition to diet and lifestyle factors include age, family history of CHD, cigarette smoking, hypertension, diabetes, elevated low-density-lipoprotein (LDL) cholesterol (> or = 4.1 mmol/L, or 160 mg/dL), and decreased high-density-lipoprotein (HDL) cholesterol (< 0.09 mmol/L, or 35 mg/dL). A diet containing < or = 30% of energy from fat, < 10% from saturated fat, and < 300 mg cholesterol/d for the general population for CHD risk reduction, and a further restriction of < 7% of energy from saturated fat and < 200 mg cholesterol/d for hypercholesterolemic subjects has been recommended. Such diets have been shown to reduce CHD risk. Age-adjusted CHD mortality rates have declined by 50% over the past four decades, probably because of decreases in animal fats in the diet, better control of hypertension, and efforts at smoking cessation.

Effects of gender and menopausal status on the association of apolipoprotein E phenotype with plasma lipoprotein levels. Results from the Framingham Offspring Study.

Apolipoprotein (apo) E phenotype is an important genetic determinant of plasma low-density lipoprotein (LDL) cholesterol and apo B levels. We have determined apo E phenotype by isoelectric focusing and plasma lipid, lipoprotein cholesterol, apo A-I, apo B, and lipoprotein(a) levels, as well as LDL particle size, in 2258 men and women participating in the Framingham Offspring Study. Apo E phenotype (E2/2, E2/4, E3/2, E3/3, E3/4, and E4/4) was not associated with plasma lipoprotein(a) levels but was associated with plasma LDL cholesterol levels, apo B levels, and LDL size in men and with plasma total cholesterol, LDL cholesterol, and apo B levels in women. The average effect of the epsilon 2 allele was to lower plasma LDL cholesterol levels by 9.2 mg/dL in men and by 13.7 mg/dL in women, while the average effect of the epsilon 4 allele was to increase LDL cholesterol levels by 2.6 mg/dL in men and by 5.4 mg/dL in women. When men were divided into two groups according to their age (< 50 and > or = 50 years old), the average effect of the epsilon 2 allele was to lower plasma levels of LDL cholesterol by 10.2 mg/dL in younger men and by 7.5 mg/dL in older men. In premenopausal women, the average effect of the epsilon 2 allele was to lower LDL cholesterol by 8.2 mg/dL and, in postmenopausal women, by 20.4 mg/dL. An opposite effect of the epsilon 4 allele was observed: the epsilon 4 allele was associated with increases in plasma LDL cholesterol levels of 4.0 mg/dL in younger men and of 1.0 mg/dL in older men.(ABSTRACT TRUNCATED AT 250 WORDS)