Apolipoprotein C-III(Lys58----Glu). Identification of an apolipoprotein C-III variant in a family with hyperalphalipoproteinemia.

Apolipoprotein C-III is a major protein constituent of triglyceride rich lipoproteins and HDL. It occurs in plasma in three isoforms differing by their sialic acid content. Apo C-III putatively inhibits lipolysis and the apo E mediated hepatic uptake of remnants from triglyceride rich particles. We identified a heterozygous carrier of an apolipoprotein C-III variant by the presence of additional bands after isoelectric focusing (IEF) of VLDL. Structural analysis of the variant protein by HPLC, time-of-flight secondary ion mass spectrometry, and automated gas phase sequencing revealed a lysine to glutamic acid replacement in position 58. The underlying A to G exchange was verified by direct sequencing subsequent to amplification by polymerase chain reaction of exon 4 of the apo C-III gene. Family studies revealed vertical transmission of this defect. The two variant carriers exhibited plasma concentrations of HDL cholesterol and apo A-I above the 95th percentiles of sex matched controls whereas the unaffected father and sister showed normal values. The plasma concentrations of apo C-III in the two variant carriers were decreased by 30-40% compared with those of the two unaffected family members and to random controls. Using two-dimensional immunoelectrophoresis as well as IEF and subsequent scanning densitometry, we found that the low serum concentration of apo C-III was a consequence of diminished concentrations of the variant apo C-III isoproteins in both VLDL (15% of normal) and HDL (25% of normal). Apo C-III(Lys58----Glu) heterozygotes possessed unusual HDL as demonstrated by nondenaturing gradient gel electrophoresis. They consisted mainly of HDL2b and contained a proportion of atypically large particles, enriched in apo E, with a Stokes diameter of 13-18 nm and resembling HDLc. In conclusion, heterozygosity for a structural apo C-III variant--apo C-III(Lys58----Glu)--was identified in two hyperalphalipoproteinemic subjects characterized by the presence of low plasma apo C-III concentrations and atypically large HDL.

Comparative effects of a recommended lipid-lowering diet vs a diet rich in monounsaturated fatty acids on serum lipid profiles in healthy young adults.

This crossover study investigated the effects of two fat-reduced diets, one rich in monounsaturated fatty acids (MUFAs), the other rich in polyunsaturated fatty acids (PUFAs), on serum lipid profiles in 38 healthy young adults initially on a typical western diet. After being randomly assigned to two groups, the subjects received the MUFA or PUFA diet for 3-wk and then the other diet for 3 wk. Both test diets led to significant reductions in serum cholesterol, LDL cholesterol, and HDL cholesterol (P less than 0.001). Both reduced apolipoprotein B (P less than 0.001) and apolipoprotein A-I concentrations (P less than 0.01 for the MUFA, P less than 0.001 for the PUFA diet). Apolipoprotein A-I was significantly higher on the MUFA than on the PUFA diet. The ratio of apolipoprotein A-I to B significantly increased on both diets. Thus, a low-fat, MUFA-rich diet is as effective as a low-fat, PUFA-rich diet in lowering total and LDL cholesterol, but both also lowered HDL cholesterol concentrations. The MUFA-rich diet may be more advantageous than the PUFA-rich one because it does not lower apolipoprotein A-I concentrations as much as the PUFA-rich diet.

Simplified turbidimetric determination of apolipoproteins A-I, A-II and B using a microtitre method.

A turbidimetric method is described for the determination of apolipoproteins A-I, A-II and B on microtitre plates. Regression analysis of the resulting values showed a good correlation to apolipoprotein values determined turbidimetrically on Cobas Bio (apolipoprotein A-I, A-II), and those determined by means of radial immuno diffusion (RID) (apolipoprotein A-I: r = 0.93, y = 1.02 x - 5.0, n = 63; apolipoprotein A-II: r = 0.90, y = 1.07 x - 5.6, n = 44; apolipoprotein B: r = 0.92, y = 0.95 x + 9.0, n = 58). The variation coefficient in the series was 3.5% (apolipoprotein A-I, n = 21), 2.5% (apolipoprotein A-II, n = 20) and 3.6% (apolipoprotein B, n = 19); and the variation coefficient from day to day 3.1% (apolipoprotein A-I, n = 45), 4.2% (apolipoprotein A-II, n = 39) and 5.3% (apolipoprotein B (n = 48).

Determination of apolipoprotein B in apolipoprotein CII/CIII-containing lipoproteins by an immunoenzymmetric assay.

A solid phase sandwich immunoenzymmetric assay is described for the determination of apolipoprotein B in apolipoprotein CII- and/or CIII-containing lipoproteins (chylomicron remnants, VLDL, IDL). During a first incubation step the particles containing apolipoproteins CII and/or CIII are bound to antibodies against these components, while the antibodies are immobilised on microtitre plate wells. After washing, anti-apolipoprotein B is added in a second incubation step. Finally peroxidase-labelled anti-sheep IgG reacts with the bound anti-apolipoprotein B, thus allowing the quantification of complexes containing both B and CII/CIII apolipoproteins. The amounts of these complexes were correlated with total cholesterol, triacylglycerols, HDL- and LDL-cholesterol, apolipoproteins AI and B, as well as with age and sex of the subject. A total of 258 individuals was studied, including patients with lipid metabolism disorders, patients with manifest coronary heart disease, and healthy controls. The assay described in this article was compared with radial immunodiffusion after pretreatment of samples. The immunoenzymmetric assay was easier and faster to perform and had a lower detection limit than the classical VLDL apolipoprotein B determination using ultracentrifugation. Furthermore, it could be performed directly on native serum. Most importantly, the study revealed elevated apolipoprotein CII/CIII-B levels in coronary heart disease patients of both sexes compared with normal subjects. Furthermore, in male coronary heart disease patients a negative correlation was found between the concentrations of apolipoprotein CII/CIII-B and HDL-cholesterol. These results suggest a delayed VLDL-HDL exchange of lipids and proteins in these patients which results in an accumulation of atherogenic apolipoprotein B-containing VLDL and IDL.

The relationship of lipoprotein (a) (Lp(a)) to risk factors of coronary heart disease: initial results of the prospective epidemiological study on company employees in Westfalia.

Lp(a) concentrations were determined in 987 male and 477 female company employees in Westfalia, in the age range 17-70 years. These values were then related to age and to the following risk factors: obesity, smoking, hypertension, hypertriglyceridaemia, hypercholesterolaemia, hyperbetalipoproteinaemia, hypoalphalipoproteinaemia, hyperglycaemia and hyperuricaemia. The Lp(a) values showed a similar markedly skewed distribution for both men and women. The median for men was 0.039 g/l, for women 0.050 g/l. In both sexes only about 25% of all Lp(a) values were above 0.10 g/l. Raised Lp(a) values (greater than 0.30 g/l) were found in 6.5% of males and in 6.1% of females. A significantly higher frequency of raised Lp(a) values (greater than 0.30 g/l) was found in: post-menopausal women (11.3% as against 4.1%, p less than 0.01); females with hypercholesterolaemia (19.0% when cholesterol values were greater than or equal to 6.73 mmol/l, 10.8% when cholesterol values were between 5.70-6.72 mmol/l, 3.0% when cholesterol values were less than 5.70 mmol/l, p less than 0.001); and females with hyperbetalipoproteinaemia (22.6% when LDL cholesterol values were greater than or equal to 4.92 mmol/l, 5.0% when LDL cholesterol values were less than 4.92 mmol/l, p less than 0.001). 12.0% of men with hypoalphalipoproteinaemia (HDL cholesterol values less than 0.907 mmol/l) had Lp(a) values greater than 0.30 g/l, as against 5.5% of men with HDL cholesterol values greater than or equal to 0.907 mmol/l (p less than 0.01). This percentage rate increased to 16.9% when hypertriglyceridaemia (greater than or equal to 2.28 mmol/l triglycerides) was also present. All other risk factors which were examined and their combinations had no significant influence on the prevalence of raised Lp(a) concentrations.

Relationship of lipoprotein(a) to variables of coagulation and fibrinolysis in a healthy population.

In the Prospective Cardiovascular Münster (PROCAM) study, serum lipoprotein(a) [Lp(a)] and its relationship to pro- and anticoagulatory as well as fibrinolytic indices were determined in a large group of employees: 864 men (m) and 373 women (f), ages 16-65 years. Univariate statistical analysis showed Lp(a) concentration to be associated with fibrinogen concentrations in both sexes (m: r = 0.08, P less than 0.05; f: r = 0.20, P less than 0.001), but not with euglobulin fibrinolysis activity, tissue-type plasminogen activator, plasminogen activator inhibitor type 1 (PAI-1), or the split products of cross-linked fibrin (d-dimer). In women only, Lp(a) was significantly correlated with antithrombin III (r = 0.15, P less than 0.01) and Protein C (r = 0.17, P less than 0.01). Further sex-related differences were seen in the relationship between Lp(a) and age (m: r = 0.05; f: r = 0.23, P less than 0.001) and body mass index (m: r = 0.01; f: r = 0.19, P less than 0.001), primarily as a consequence of remarkable differences of Lp(a) concentrations between postmenopausal (mean = 79.4 mg/L) and premenopausal women (mean = 51.5 mg/L, P = 0.001). Multiple-regression analysis demonstrated a significant negative correlation of Lp(a) to PAI-1 (m: beta = -0.12, P less than 0.01; f: beta = -0.14, P less than 0.05) and a positive correlation to cholesterol (m: beta = 0.18, P less than 0.001; f: beta = 0.17, P less than 0.01) and systolic blood pressure (m: beta = 0.08, P less than 0.05; f: beta = 0.11, P less than 0.05).

Dose-response relationships of serum lipid measurements with the extent of coronary stenosis. Strong, independent, and comprehensive. ECAT Angina Pectoris Study Group.

Serum lipids, lipoproteins, and more recently apolipoproteins and lipoprotein(a) [Lp(a)] have been shown to be independent risk factors for coronary vessel disease and its prognosis. However, the relationships between serum lipid levels and the extent of coronary artery disease (CAD) have not been consistently shown. Twenty-five hundred male and female patients with suspected angina pectoris were recruited from 18 European medical centers. The independent relations of total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, apo A-I and B, and Lp(a) with the presence and extent of CAD, as assessed by coronary angiography, were investigated. All of the lipid measures showed strong relations P < .0001) with the presence of CAD, defined by the existence of at least one > or = 50% coronary vessel stenosis. Total cholesterol, LDL cholesterol, apo B, triglycerides, and Lp(a) were substantially higher and HDL cholesterol and apo A-I lower in patients with CAD. The odds ratio of CAD, in the high-risk tertile of each lipid's distribution compared with the low-risk tertile, was in the range 1.5 to 2.3. Each of total cholesterol (or LDL cholesterol or apo B), HDL cholesterol (or apo A), and Lp(a) had an independent effect in predicting the presence of CAD. In addition, all lipids showed a strong association (P = .0006 for triglycerides, P < .0001 otherwise) with the extent of CAD as defined by the number of stenosed coronary vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipoprotein(a) is an independent risk factor for myocardial infarction at a young age.

We quantified lipoprotein(a) [Lp(a)] immunochemically in young (less than 46 y) male survivors of myocardial infarction and in age-matched controls recruited from participants of the Prospective Cardiovascular Münster (PROCAM) study. We further determined apolipoprotein E polymorphism and measured triglycerides, total cholesterol, high- and low-density lipoprotein cholesterol (HDL and LDL), and apolipoproteins AI, AII, and B in the serum of these subjects. Lp(a) concentrations in serum were not correlated with other well-recognized risk factors for early myocardial infarction such as apolipoproteins AI and B, LDL cholesterol, and HDL cholesterol. Apolipoprotein E polymorphism did not affect Lp(a) concentrations, but had a major influence on apolipoprotein B concentration. Lp(a) concentrations were not influenced by age. Our data suggest that (a) an increased concentration of Lp(a) constitutes an independent risk factor for early myocardial infarction and (b) the concentrations of Lp(a) and LDL cholesterol (apolipoprotein B) in serum are under separate metabolic control.

[Relationship between lipid metabolism disorders and age of first manifestations of coronary heart disease]. / Untersuchungen zur Beziehung zwischen Lipidstoffwechselstörungen und Erstmanifestationsalter der koronaren Herzkrankheit (KHK).

In 509 male patients, age less than 45 years, with angiographically documented coronary artery disease (CHD) we found (in contrast to age-matched controls: 459 participants of the PROCAM study) an increased amount of total cholesterol (259 vs. 221 mg/dl), LDL-cholesterol (185 vs. 142 mg/dl), Apo-B (138 vs. 118 mg/dl), lipoprotein(a) (12 vs. 5 mg/dl) and uric acid (6.4 vs. 5.8 mg/dl); HDL-cholesterol (40.5 vs. 46.8 mg/dl), Apo-A-I (122 vs. 143 mg/dl) and Apo-A-II (38 vs. 43 mg/dl) were significantly lower. These differences in lipid-metabolism between CHD-patients and controls in the younger group were essentially more pronounced than in older individuals of a group of 423 male patients over the age of 45 years who suffered from CHD and 545 age-matched PRO-CAM participants. Among the extent of the disorder in lipid metabolism, the apolipoprotein E-polymorphism, and the age of onset of CHD there exists a significant correlation which proves the special importance to therapeutically influence disorders of lipid metabolism especially in younger patients.