Physical maps of human alpha (1,3)fucosyltransferase genes FUT3-FUT6 on chromosomes 19p13.3 and 11q21

Sialyl Lewis x and related fucosylated glycans are differentially expressed in human cells and form ligands for selectin adhesion receptors. alpha(1,3)Fucosyltransferases (FUTs) that complete their biosynthesis also show tissue specificity. We have established physical maps of the FUT3-6 loci to study regulation of this gene family. FUT4 has previously been localized to chromosome 11q21; FUT3, FUT6, and now FUT5 are localized to chromosome 19p13.3. Conventional and pulsed-field gel electrophoresis mapping of total genomic DNA and large genomic clones were used to generate a fine map of both loci, defining the order, orientation, and distances between FUTs. A P1 clone with all three 19p FUT genes in tandem orientation was isolated and used to study regions flanking FUT3, -5, and -6. Our studies provide preliminary information to study regulation of human FUT genes.

Associations of hepatic and lipoprotein lipase activities with changes in dietary composition and low density lipoprotein subclasses

To test whether lipoprotein lipase or hepatic lipase activities are associated with lipoprotein subclasses, and to assess the effects of dietary manipulations on these associations, enzyme activities were measured in postheparin plasma (75 U heparin/kg) from 43 healthy men who were randomly allocated to a low-fat (24% fat, 60% carbohydrate) and a high-fat (46% fat, 38% carbohydrate) diet for 6 weeks each in a cross-over design. The high-fat diet significantly increased both lipoprotein lipase (+20%, P = 0.02) and hepatic lipase (+8%, P = 0.007) activities. On both diets, hepatic lipase activity was significantly positively correlated (P < 0.01) with plasma apolipoprotein (apo)B concentrations, and with levels of small dense low density lipoprotein (LDL) III, measured by analytic ultracentrifugation as mass of lipoproteins of flotation rate (Sof) 3-5, while lipoprotein lipase activity was inversely associated with levels of LDL III (P < 0.05). Despite the cross-sectional correlations, increased hepatic lipase activity was not significantly correlated with the reduction in LDL III mass observed on the high-fat diet. Rather, changes in hepatic lipase were correlated inversely with changes in small very low density lipoproteins (VLDL) of Sof 20-40, and small intermediate density lipoproteins (VLDL) of Sof 10-16. Moreover, changes in lipoprotein lipase activity were not significantly correlated with changes in small LDL, but were positively associated with changes in small IDL of Sof 10-14, and large LDL I of Sof 7-10. Thus, while increased levels of small dense LDL are associated with a metabolic state characterized by relatively increased hepatic lipase and decreased lipoprotein lipase activity, changes in these enzymes do not appear to be primary determinants of diet-induced changes in levels of this LDL subfraction. On the other hand, increased lipoprotein lipase activity induced by high-fat feeding may contribute to the accumulation in plasma of both large LDL I and small IDL, whereas increased hepatic lipase may promote catabolism or clearance of triglyceride-rich lipoprotein remnants.

Dense low density lipoproteins and coronary artery disease

A common, genetically influenced lipoprotein subclass profile characterized by a predominance of small, dense low density lipoprotein (LDL) particles is associated with relative increases in plasma triglyceride and apolipoprotein (apo) B-100, and reduced levels of high density lipoprotein cholesterol and apoAI. Recently, this phenotype has also been associated with the insulin resistance syndrome and familial combined hyperlipidemia. Case-control studies of patients with myocardial infarction and angiographically documented coronary artery disease (CAD) have demonstrated that 40-50% of patients have the small, dense LDL phenotype and that this is associated with a 2- to 3-fold increase in disease risk. However, because of strong statistical correlations among the multiple features of the phenotype, it has been difficult to determine whether > or = 1 of its metabolic alterations are primarily responsible for increased CAD susceptibility. More direct evidence for enhanced atherogenicity of lipoproteins in this trait derives from a recent report that LDL-cholesterol lowering by diet and drug treatment resulted in reduced coronary angiographic progression in CAD subjects with predominantly dense LDL, but that an equivalent lowering of LDL cholesterol in subjects with more buoyant LDL was not associated with angiographic benefit. Further, in vitro findings have indicated increased susceptibility of small, dense LDL to oxidative modification and relatively greater binding of these particles to arterial wall proteoglycans. Thus, the small, dense LDL trait may underlie familial predisposition to CAD in a large proportion of the population, and its presence may indicate the potential for benefit from specific therapeutic interventions.

Apolipoprotein E isoform phenotype and LDL subclass response to a reduced-fat diet

We investigated the association of apolipoprotein (apo) E isoform phenotype with lipoprotein response to reduced dietary fat intake in 103 healthy men (apoE3/2, n = 10; apoE3/3, n = 65; and apoE4/3, 4/4, n = 28). In a randomized, crossover design, subjects consumed high-fat (46%) and low-fat (24%) diets for 6 weeks each. High-fat LDL cholesterol differed among phenotypes, with apoE4/3, 4/4 > apoE3/3 > apoE3/2. Reduction of LDL cholesterol on the low-fat diet was greater for apoE4/3, 4/4 than apoE3/3 (P < .05). There was no significant change in plasma apoB level within any of the apoE phenotype groups on the low-fat diet. This result, together with measurements of LDL subfraction mass by analytical ultracentrifugation, indicated that the primary basis for the diet-induced reduction in LDL cholesterol was not reduced LDL particle number but rather a shift from large, buoyant, cholesterol-rich LDL particles (flotation rate, 7 to 12) to smaller, denser LDL particles (flotation rate, 0 to 7). The magnitude of this effect was related to apoE phenotype, with progressively greater reductions in levels of large LDL (P < .01) from apoE3/2 to apoE3/3 to apoE4/3, 4/4. These results indicate that reduced dietary fat lowers levels of large, buoyant LDL particles by an apoE-dependent mechanism.

The associations of high-density lipoprotein subclasses with insulin and glucose levels, physical activity, resting heart rate, and regional adiposity in men with coronary artery disease: the Stanford Coronary Risk Intervention Project baseline survey

We used nondenaturing polyacrylamide gradient gel electrophoresis to examine the associations of high-density lipoprotein (HDL) subclasses with adiposity, physical activity, resting heart rate (an indicator of sympathetic drive), and plasma insulin and glucose levels in 97 men with angiographically documented coronary artery disease. These men neither smoked nor used medications known to affect lipoproteins. The absorbency of protein stain was used as an index of mass concentrations at intervals of 0.01 nm within five HDL subclasses: HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12 nm). HDL peak diameter was determined from the predominant peak of the HDL particle distribution when plotted against particle diameter. Four men who were non-insulin-dependent diabetics as defined by a fasting glucose exceeding 140 mg/dL had significantly higher plasma HDL3b levels and significantly smaller HDL peak diameters than nondiabetic men, and were therefore excluded from further analyses. In the remaining 93 nondiabetic men, plasma HDL3b levels correlated positively with indices of truncal obesity (waist to hip ratio and subscapular skinfold), whereas plasma HDL2b levels correlated negatively with indices of total adiposity (body mass index [BMI]) and truncal obesity (subscapular and abdominal skinfold). Fasting plasma insulin levels correlated negatively with HDL3a, HDL2a, and HDL2b. Obesity significantly affected the relationships of resting heart rate with insulin and HDL subclasses.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential expression of ARIA isoforms in the rat brain

ARIA, heregulin, neu differentiation factor, and glial growth factor are members of a new family of growth and differentiation factors whose effects have been assayed on Schwann cells, skeletal muscle cells, and mammary tumor cell lines. To gain insight into their roles in the CNS, we studied the expression of ARIA in the rat brain. We found ARIA mRNA in all cholinergic neurons throughout the CNS, including motor neurons and cells of the medial septal nucleus and the nucleus basalis of Meynert. We also found that ARIA induces tyrosine phosphorylation of a 185 kDa protein in central and peripheral targets of these cholinergic neurons. ARIA mRNA, however, is not restricted to cholinergic neurons, suggesting that it may also play a role at other types of synapses. Its distribution in germinal layers of the telencephalon and cerebellum suggests that it may also play a role in the proliferation and/or migration of neuronal and glial precursor cells.

Multivariate analysis of the insulin resistance syndrome in women

The insulin resistance syndrome (IRS) is characterized by a constellation of interrelated coronary heart disease (CHD) risk factors, including dyslipidemia, obesity, central obesity, elevated systolic blood pressure, and hyperinsulinemia. Factor analysis was used to investigate the clustering of these risk factors in individuals by examining the correlational structure among these variables. Data from 281 genetically unrelated nondiabetic women who participated in exam 2 (1979 to 1980) of the Kaiser Permanente Women Twins Study were used. Factor analysis reduced 10 correlated risk factors to 3 uncorrelated factors, each reflecting a different aspect of the IRS: factor 1 (increased body weight, waist circumference, fasting insulin, and glucose), factor 2 (increased postload and fasting glucose and insulin and systolic blood pressure), and factor 3 (larger low-density lipoprotein particles, decreased plasma triglycerides, and increased high-density lipoprotein). Together, the factors explained nearly 66% of the total variance in the data. Thus, factor analysis defined three distinct aspects of the IRS in this sample of nondiabetic women. These factors may reflect separate underlying mechanisms of the syndrome, each of which may also be involved in CHD risk.

Variations in high-density lipoprotein subclasses during the menstrual cycle

In a study of 41 healthy premenopausal women, plasma high-density lipoprotein-2a (HDL2a) levels (ie, HDL of diameter 8.8 to 9.7 nm) were significantly higher during the luteal phase than during the follicular phase of the cycle. There was no significant variation in HDL2b or any of the HDL3 subclasses.

Genetic predictors of FCHL in four large pedigrees. Influence of ApoB level major locus predicted genotype and LDL subclass phenotype

The genetic basis of familial combined hyperlipidemia (FCHL) has eluded investigators for 20 years, despite the apparent segregation of FCHL as an autosomal dominant disorder affecting 1% to 2% of individuals. Etiologic heterogeneity and additive effects of traits controlled by other genetic loci have been suggested. Two traits have been implicated in FCHL. The first is the predominance of a small, dense low-density lipoprotein (LDL), LDL subclass phenotype B, which segregates as a mendelian trait. The second is a mendelian locus with large effects on apolipoprotein (apo) B levels that is defined by complex segregation analysis (predicted apoB level genotype). This study shows that these factors appear to be separate genetic effects, both of which aid in the prediction of FCHL in four large pedigrees. The results suggest that FCHL may be best predicted by a threshold model in which apoB level genotype and LDL subclass phenotype each act to increase the risk of FCHL. Heterogeneity in the transmission of apoB levels among families is suggested, supporting the etiologic heterogeneity of FCHL. These results emphasize the advantages inherent in the study of large pedigrees when disease heterogeneity is suspected.

Heterogeneity of plasma low-density lipoproteins and atherosclerosis risk

Increased levels of IDL and small, dense LDL are associated with the risk of coronary artery disease. Possible mechanisms include increased susceptibility of small, dense LDL to oxidation, and to other pathologic effects, such as increased retention in the arterial wall. Beneficial effects of a low-fat diet and certain lipid-lowering therapies on the levels and properties of small, dense LDL or their precursors may contribute substantially to the reductions in coronary atherosclerosis observed in several lipid-lowering trials.

Coronary artery disease regression. Convincing evidence for the benefit of aggressive lipoprotein management

BACKGROUND

Numerous reports suggest that coronary artery disease can regress with lipoprotein manipulation. Many of these reports lack control groups and contain relatively small numbers.

METHODS AND RESULTS

Ten randomized controlled clinical trials using coronary arteriography to assess the effect of lipoprotein manipulation on the rate of progression and regression of atherosclerosis have been either published or reported as an abstract at a national meeting. These studies were critically reviewed for individual differences and combined clinically applicable lessons. These trials involved a total of 2095 subjects and have consistently reported reduction in the percentage of patients arteriographically defined as progressing (mean, 23.6%) and an increase in the percentage regressing (mean, 20.0%) compared with control groups. Compared with large clinical trials using clinical end points, lipoprotein change was greater, achieving on average a 28% reduction in low-density lipoprotein cholesterol, 11% reduction in triglycerides, and 11% increase in high-density lipoprotein cholesterol compared with control groups. Four investigations used a nonpharmacological approach, and seven used single and multiple drug therapy combined with diet. Despite the relatively brief treatment time of often 2 to 4 years, clinical events were fewer in the treatment groups; within some studies, this reached statistical significance. Side effects from the different therapies were tolerated by most patients, and severe adverse clinical events were few.

CONCLUSIONS

These trials present convincing evidence that aggressive lipoprotein manipulation can result in improved arteriographic measurements and fewer cardiovascular events in a relatively short period of time of 2 to 4 years. Extrapolation of this information to the larger population with known coronary artery disease suggests that directed lipoprotein manipulation can reduce clinical events in a cost-effective manner.

Isolation of allele-specific, receptor-binding-defective low density lipoproteins from familial defective apolipoprotein B-100 subjects

Familial defective apolipoprotein B-100 (FDB) is a genetic disorder apparently caused by a single amino acid substitution (Arg3500-->Gln) that disrupts the binding of low density lipoproteins (LDL) to the LDL receptor. The plasma of FDB heterozygotes contains a mixture of normal LDL and LDL that is defective in binding to the LDL receptor. In this study, the monoclonal antibody MB19 (which recognizes an immunogenetic polymorphism in apolipoprotein B-100) was used to determine the percentage of defective LDL in the plasma of FDB heterozygotes and to isolate allele-specific receptor-binding-defective LDL. Several FDB heterozygotes were identified who were heterozygous for the MB19 polymorphism: one apolipoprotein B allotype in each of these individuals bound with low affinity to MB19 and possessed the Arg3500-->Gln mutation, whereas the other apolipoprotein B allotype bound with high affinity to MB19 and normally to the LDL receptor. Using MB19 radio-immunoassay, we determined that an average of 73% (range 65-87) of the total LDL from FDB heterozygotes contained the Arg3500-->Gln mutation. Antibody MB19-Sepharose immuno-affinity chromatography was used to separate the receptor-binding-defective LDL from the normal LDL. The isolated LDL contained primarily the Arg3500-->Gln mutation and had only about 9% of normal LDL receptor-binding ability. Finally, the MB19-Sepharose chromatography procedure may be useful for isolating other allele-specific LDL that have functionally significant mutations.

Relations of plasma TG and HDL-C concentrations to body composition and plasma insulin levels are altered in men with small LDL particles

Low-density lipoprotein (LDL) subclass pattern B is characterized by a predominance of small, dense LDL particles (LDL peak particle size < or = 255 A), increased plasma triglyceride (TG) levels, reduced high-density lipoprotein (HDL) cholesterol levels, and glucose intolerance. This study tested the hypothesis that there are differences in the regulation of TG and HDL metabolism by insulin in patients with LDL pattern B. The study group comprised 160 healthy older (60 +/- 8 years, mean +/- SD) men. Forty-nine of the men (31%) had LDL pattern B. These men had a higher waist-to-hip ratio (WHR) (0.98 +/- 0.06 versus 0.95 +/- 0.06, P < .005) and lower maximal aerobic capacity (VO2max) (P < .005) than the 111 men of comparable age with a predominance of larger LDL particles (LDL peak particle size > 255 A, LDL pattern A). Men with LDL pattern B also had higher TG (1.76 +/- 0.60 versus 1.03 +/- 0.41 mmol/L, P < .0001) and lower HDL cholesterol (0.83 +/- 0.13 versus 1.06 +/- 0.29 mmol/L, P < .0001) and percent HDL2 subspecies (by gradient gel electrophoresis) (31 +/- 4 versus 43 +/- 6, P < .0001) levels than men with LDL pattern A, but the total cholesterol and LDL cholesterol levels did not differ between groups. Fasting glucose and insulin levels also did not differ between groups, but plasma glucose and insulin levels measured at 90 and 120 minutes during an oral glucose tolerance test were significantly higher in men with LDL pattern B.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of low-fat diet, calorie restriction, and running on lipoprotein subfraction concentrations in moderately overweight men

We studied the effects of exercise (primarily running), calorie restriction (dieting), and a low-fat, high-carbohydrate diet on changes in lipoprotein subfractions in moderately overweight men in a randomized controlled clinical trial. After 1 year, complete data were obtained for 39 men assigned to lose weight through dieting without exercise, 37 men assigned to lose weight through dieting with exercise (primarily running), and 40 nondieting sedentary controls. We instructed both diet groups to consume no more than 30% total fat, 10% saturated fat, and 300 mg/d of cholesterol, and at least 55% carbohydrates, and the controls were instructed to maintain their usual food choices. Analytic ultracentrifugation was used to measure changes in plasma lipoprotein mass concentrations. In addition, the absorbance of protein-stained polyacrylamide gradient gels was used as an index of concentrations for five high-density lipoprotein (HDL) subclasses that have been identified by their particle sizes, ie, HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12 nm). Relative to controls, weight decreased significantly in men who dieted with exercise (net difference +/- SE, -3.3 +/- 0.4 kg/m2) and in men who dieted without exercise (-2.0 +/- 0.4 kg/m2). Dieting with exercise significantly decreased very-low-density lipoprotein (VLDL)-mass concentrations and significantly increased plasma HDL2-mass, HDL3a, HDL2a, and HDL2b relative to both control and dieting without exercise. There were no significant changes in lipoprotein mass and HDL protein for dieters who did not run.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intensive multiple risk factor reduction on coronary atherosclerosis and clinical cardiac events in men and women with coronary artery disease. The Stanford Coronary Risk Intervention Project (SCRIP)

BACKGROUND

Recent clinical trials have shown that modification of plasma lipoprotein concentrations can favorably alter progression of coronary atherosclerosis, but no data exist on the effects of a comprehensive program of risk reduction involving both changes in lifestyle and medications. This study tested the hypothesis that intensive multiple risk factor reduction over 4 years would significantly reduce the rate of progression of atherosclerosis in the coronary arteries of men and women compared with subjects randomly assigned to the usual care of their physician.

METHODS AND RESULTS

Three hundred men (n = 259) and women (n = 41) (mean age, 56 +/- 7.4 years) with angiographically defined coronary atherosclerosis were randomly assigned to usual care (n = 155) or multifactor risk reduction (n = 145). Patients assigned to risk reduction were provided individualized programs involving a low-fat and -cholesterol diet, exercise, weight loss, smoking cessation, and medications to favorably alter lipoprotein profiles. Computer-assisted quantitative coronary arteriography was performed at baseline and after 4 years. The main angiographic outcome was the rate of change in the minimal diameter of diseased segments. All subjects underwent medical and risk factor evaluations at baseline and yearly for 4 years, and reasons for all hospitalizations and deaths were documented. Of the 300 subjects randomized, 274 (91.3%) completed a follow-up arteriogram, and 246 (82%) had comparative measurements of segments with visible disease at baseline and follow-up. Intensive risk reduction resulted in highly significant improvements in various risk factors, including low-density lipoprotein cholesterol and apolipoprotein B (both, 22%), high-density lipoprotein cholesterol (+12%), plasma triglycerides (-20%), body weight (-4%), exercise capacity (+20%), and intake of dietary fat (-24%) and cholesterol (-40%) compared with relatively small changes in the usual-care group. No change was observed in lipoprotein(a) in either group. The risk-reduction group showed a rate of narrowing of diseased coronary artery segments that was 47% less than that for subjects in the usual-care group (change in minimal diameter, -0.024 +/- 0.066 mm/y versus -0.045 +/- 0.073 mm/y; P < .02, two-tailed). Three deaths occurred in each group. There were 25 hospitalizations in the risk-reduction group initiated by clinical cardiac events compared with 44 in the usual-care group (rate ratio, 0.61; P = .05; 95% confidence interval, 0.4 to 0.9).

CONCLUSIONS

Intensive multifactor risk reduction conducted over 4 years favorably altered the rate of luminal narrowing in coronary arteries of men and women with coronary artery disease and decreased hospitalizations for clinical cardiac events.

OmniMed II: a new system for use with the emphasis erodible mask

Clinical experience has shown the emphasis erodible mask to be an effective method for performing photorefractive keratectomy (PRK) using an eyecup placed in contact with the corneal surface. A new system (OmniMed II) which incorporates the erodible mask as an element in the optical delivery system has been developed for performing photorefractive keratectomy. With this new configuration the eyecup is no longer used. We describe in detail the advantages of the erodible mask, the associated hardware of the optical delivery system, and the mask shape transfer process.

Oxidative susceptibility of low density lipoprotein subfractions is related to their ubiquinol-10 and alpha-tocopherol content

The conjugated polyene fatty acid parinaric acid (PnA) undergoes a stoichiometric loss in fluorescence upon oxidation and can be used to directly monitor peroxidative stress within lipid environments. We evaluated the course of potentially atherogenic oxidative changes in low density lipoproteins (LDL) by monitoring the oxidation of PnA following its incorporation into buoyant (p = 1.026-1.032 g/ml) and dense (p = 1.040-1.054 g/ml) LDL subfractions. Copper-induced oxidation of LDL-associated PnA exhibited an initial lag phase followed by an increased rate of loss until depletion. Increased PnA oxidation occurred immediately after the antioxidants ubiquinol-10 and alpha-tocopherol were consumed but before there were marked elevations in conjugated dienes. Despite differences in sensitivity to early oxidation events, PnA oxidation and conjugated diene lag times were correlated (r = 0.582; P = 0.03), and both indicated a greater susceptibility of dense than buoyant LDL in accordance with previous reports. The greater susceptibility of PnA in dense LDL was attributed to reduced levels of ubiquinol-10 and alpha-tocopherol, which were approximately 50% lower than in buoyant LDL (mol of antioxidant/mol of LDL) and together accounted for 80% of the variation in PnA oxidation lag times. These results suggest that PnA is a useful probe of LDL oxidative susceptibility and may be superior to conjugated dienes for monitoring the initial stages of LDL lipid peroxidation. Differences in oxidative susceptibility among LDL density subfractions are detected by the PnA assay and are due in large part to differences in their antioxidant content.

Reduced adipose tissue lipoprotein lipase responses, postprandial lipemia, and low high-density lipoprotein-2 subspecies levels in older athletes with silent myocardial ischemia

Healthy older (64 +/- 1 years, mean +/- SEM) athletic (maximal oxygen consumption [VO2max] > 40 mL/kg/min) normocholesterolemic men with no prior history of coronary artery disease (CAD) were recruited for cardiovascular and metabolic studies. Thirty-three percent had asymptomatic exercise-induced ST segment depression on their exercise electrocardiogram (ECG), consistent with silent myocardial ischemia (SI). We hypothesized that abnormalities in high-density lipoprotein (HDL) and postprandial triglyceride (TG) metabolism may increase their risk for CAD. Compared with 12 nonischemic controls of comparable age, percent body fat, and VO2max, the 13 men with SI had decreased fasting HDL cholesterol ([HDL-C] 41 +/- 2 v 50 +/- 2 mg/dL, P < .001) and %HDL2b subspecies levels as measured by gradient gel electrophoresis (22 +/- 2 v 34 +/- 3, P < .001). Fasting plasma TG and low-density lipoprotein cholesterol (LDL-C) levels were the same in both groups. Although plasma glucose levels during an oral glucose tolerance test (OGTT) were similar in both groups, the total insulin area was higher in men with SI (P < .05). After consumption of a standard high-fat meal (680 kcal/m2 body surface area of a formula in which 86% of the calories were derived from fat), postprandial plasma TG, chylomicron-TG, and very-low-density lipoprotein (VLDL)-TG levels and postprandial areas were higher in men with SI (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of LCAT activity and HDL structure. New links between cigarette smoke and coronary heart disease risk

The mechanism(s) through which smoking influences the progression of atherosclerosis is poorly understood. Recent evidence suggests that oxidants present in the gas phase of cigarette smoke are involved. We exposed human plasma to the filtered gas phase of cigarette smoke to assess its effects on plasma components involved in the antiatherogenic reverse cholesterol transport pathway. In our model, freshly isolated plasma (24 mL) was exposed to filtered air or gas-phase cigarette smoke for up to 6 hours at 37 degrees C. Lecithin-cholesterol acyltransferase (LCAT) activity was dramatically inhibited by cigarette smoke. A single 15-minute exposure to the smoke from an eighth of a cigarette was sufficient to reduce LCAT activity by 7%; additional exposures resulted in further decreases in activity. At 6 hours, only 22% of control LCAT activity remained in plasma exposed to smoke. Compared with control, gas-phase cigarette smoke-exposed plasma possessed high-density lipoprotein (HDL) with increased (16%) negative charge and with cross-linked apolipoproteins AI and AII. These data demonstrate that gas-phase cigarette smoke can inhibit a key enzyme (LCAT) and modify an integral lipid transport particle (HDL) that are essential components for the normal function of the reverse cholesterol transport pathway. Gas-phase cigarette smoke-induced modification of the reverse cholesterol transport pathway may provide a new mechanistic link between cigarette smoke and coronary heart disease risk.

Low-density lipoprotein subclass patterns and lipoprotein response to a reduced-fat diet in men

Low-density lipoprotein (LDL) subclass pattern B is a common genetically influenced lipoprotein profile characterized by a predominance of small, dense LDL particles, and associated with increased levels of triglyceride-rich lipoproteins, reductions in high-density lipoprotein cholesterol (HDL-C), and increased risk of coronary artery disease compared to individuals with a predominance of larger LDL (pattern A). We sought to determine whether LDL subclass patterns are associated with response of plasma lipoprotein levels to changes in dietary fat and carbohydrate content. In a randomized cross-over study, 105 men consumed, for six weeks each, high-fat (46%) and low-fat (24%) solid food diets, with replacement of fat by carbohydrate. Diet-induced changes in subjects who exhibited pattern B (n = 18) following the high-fat diet differed significantly from those in subjects with pattern A (n = 87): in pattern B subjects LDL cholesterol (LDL-C) reductions were two-fold greater and plasma apolipoprotein (apo) B levels decreased significantly. These differences remained significant after adjustment for levels of plasma LDL-C, apo B, HDL-C, and body mass index. Thus, LDL subclass pattern is a factor that contributes significantly to interindividual variation of plasma lipoprotein response to a low-fat, high-carbohydrate diet.

Associations of age, adiposity, alcohol intake, menstrual status, and estrogen therapy with high-density lipoprotein subclasses

We used nondenaturing polyacrylamide gradient gel electrophoresis to examine the associations of age, adiposity, alcohol intake, and exogenous estrogen with high-density lipoprotein (HDL) subclasses in 427 members of 51 principally Mormon kindreds. The absorbency of protein stain was used as an index of mass concentrations at intervals of 0.01 nm within five HDL subclasses: HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12 mm). Age and alcohol intake were obtained from questionnaires, and body mass index was computed from clinic measurements as weight (kg)/height (m)2. The results suggest that HDL3b concentrations were higher after menopause than before. Adult men (> or = 18 years old) had significantly higher HDL3c and HDL3b and significantly lower HDL2b and HDL2a levels than younger boys. Compared with the women, adult men had higher levels of HDL3c and HDL3b and lower levels of HDL2b, HDL2a, and larger-diameter HDL3a particles. There were no significant differences between the HDL profiles of women and younger boys, suggesting that divergence in HDL occurs during puberty. Eighty-eight percent of the increase in HDL associated with estrogen replacement in postmenopausal women occurred within HDL3a and HDL2a. Reported alcohol intake in adult men correlated with two HDL regions: one within the HDL2b region and a second within the HDL3a/2a region, whereas in women the positive correlation between alcohol and HDL levels was within the HDL2b region only. In both men and premenopausal adult women, increasing levels of body mass index were associated with higher levels of HDL3b and lower levels of HDL2b.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of estrogen on low-density lipoprotein subclasses in healthy postmenopausal women

The use of estrogen by postmenopausal women decreases plasma low-density lipoprotein (LDL) cholesterol levels. To determine whether LDL subclass profiles influence this response, we studied 31 healthy postmenopausal women who were administered two doses (0.625 and 1.25 mg/d) of conjugated equine estrogen in a placebo-controlled double-blind crossover study. Lipid-stained gradient gels were used to categorize LDL subclass patterns. All women were classified as LDL subclass pattern A (predominant LDL peak > or = 260 A). Within the pattern A classification, there were 12 women during placebo treatment with LDL subclass I pattern (predominant LDL peak > 271 A) and 19 women with LDL subclass II pattern (predominant LDL peak < or = 271 and > or = 260 A). Postmenopausal women with LDL subclass I on placebo treatment had significantly lower LDL cholesterol levels compared with women having LDL subclass II (126 +/- 28 v 147 +/- 23 mg/dL, P < .03). Postmenopausal women with LDL subclass I also had significantly (P < .05) lower very-low-density lipoprotein (VLDL) cholesterol, VLDL triglyceride, and VLDL apo B levels and significantly higher (P < .05) high-density lipoprotein 2 (HDL2) cholesterol, HDL3 cholesterol, and HDL2 apo A-I levels. Estrogen replacement significantly (P < .05) decreased LDL cholesterol levels and increased VLDL and LDL triglyceride, HDL2 and HDL3 cholesterol and apo A-I, and HDL2 apo A-II levels to a similar extent in postmenopausal women with LDL I or II subclass patterns.(ABSTRACT TRUNCATED AT 250 WORDS)