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Treatment of hyperlipidemic patients with the thiol compound N-acetylcysteine (NAC) was previously shown to cause a significant dose-related increase in the high-density lipoprotein (HDL)-cholesterol serum level, suggesting the possibility that its disease-related decrease may result from a diminished thiol concentration and/or thiol/disulfide redox status (REDST) in the plasma. We therefore investigated plasma thiol levels and REDST in normo-/hyperlipidemic subjects with and without coronary heart disease (CHD). The thiol level, REDST, and amino acid concentrations in the plasma and intracellular REDST of peripheral blood mononuclear cells (PBMC) have been determined in 62 normo- and hyperlipidemic subjects. Thirty-three of these subjects underwent coronary angiography, because of clinical symptoms of CHD. All groups of hyperlipidemic patients under test and those normolipidemic individuals with documented coronary stenoses showed a marked decrease in plasma thiol concentrations, plasma and intracellular REDST of PBMCs, and a marked increase in plasma taurine levels. Individual plasma thiol concentrations and plasma REDST were strongly negatively correlated with the serum LDL-cholesterol and positively correlated with the serum HDL-cholesterol level. Together with the earlier report about the effect of NAC on the HDL-cholesterol serum level, our findings suggest strongly that lower HDL-cholesterol serum levels may result from a decrease in plasma thiol level and/or REDST possibly through an excessive cysteine catabolism into taurine.

The purpose of this study was to investigate the effects of apolipoprotein (apo) E genotype on plasma apo E levels as well as serum total, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, and glucose values in 734 middle-aged and elderly, female and male subjects. Apo E allele frequencies were similar to those reported in other Caucasian populations. After adjustment for medications, alcohol use, smoking, age, and body mass index, apo E genotype was noted to have significant effects on apo E, total cholesterol, LDL cholesterol, and glucose levels in females, and on apo E, LDL cholesterol, and HDL cholesterol levels, as well as the total cholesterol (TC)/HDL cholesterol ratio in males. Female and male subjects with the apo E4 allele had significantly (P<0.05) lower plasma apo E (25 and 15%) and higher LDL cholesterol levels (5 and 2%), while those with the apo E2 allele had significantly (P<0.05) higher apo E (32 and 27%) and lower LDL cholesterol levels (10 and 10%) than the apo E3/3 group. Moreover, female apo E4 carriers had significantly (P<0.05) lower glucose values (11%) than the apo E3/3 group. These data are consistent with the concept that, in addition to the well known effects of apo E genotype on LDL-C values, this locus plays a very significant role in modulating plasma apo E levels.

A simple method of obtaining semiquantitative and reliable data on apolipoprotein (apo) sigma gene expression is described. We detected apo sigma specific sequences by reverse transcription (rT)-PCR. For quantitative measurement, an apo sigma DNA standard was produced allowing the development of a competitive PCR-method. The efficiency of RNA extraction and cDNA synthesis was controlled by quantitation of a housekeeping gene (glyceraldehyde-3-phosphatedehydrogenase, G3PDH) in separate reactions. To imitate a defined induction of apo sigma gene expression, serial twofold dilutions of total RNA were reversely transcribed and the respective cDNAs used to perform a competitive apo sigma and G3PDH PCR. The change in apo sigma cDNA and G3PDH cDNA was 1.7-2.3-fold with an expected value of 2.0-fold. Standard deviations in three independently performed experiments were within a range of < 15% of the mean, indicating low intra-assay variation and high reproducibility. To illustrate this method, apo sigma gene expression was measured in a patient with complete lack of functional active apo E in comparison to healthy controls. The method presented here might be valuable in assessment of apo sigma gene expression in human disease.

We developed a rapid and simple competitive reverse transcription-polymerase chain reaction for the quantification of apo epsilon mRNA in human monocyte-derived macrophages. The method was applied, and its reliability was shown in patients with the familial lipoprotein disorder, type III hyperlipoproteinemia. Type III hyperlipoproteinemic patients express markedly higher concentrations of apo epsilon mRNA when compared with healthy controls. Patients with this disease are usually (>90%) homozygous for a receptor binding-defective isoform of apolipoprotein apo E (apo E2). The higher expression of apo epsilon mRNA in the patients could, therefore, be a physiological mechanism to compensate for functionally defective apo E. The developed procedure might be valuable in assessment of apo epsilon gene expression in human disease.

Type III hyperlipoproteinemia (HLP) is usually associated with homozygosity for apolipoprotein (apo) E2 (Arg112 --> Cys, Arg158 --> Cys). This common apo E isoform is defective in its binding to lipoprotein receptors. However, other rare mutations in the apo epsilon gene may also, in part dominantly, predispose to the disease. In order to assess the prevalence of rare apo E variants and mutations in the apo epsilon gene in Germany, we examined apo epsilon genotypes by restriction isotyping (RI) and apo E phenotypes by isoelectric focusing (IEF) in 107 German patients with type III HLP. Concordance between apo epsilon genotype and apo E phenotype was observed in 101 subjects (94.4%). Six individuals (5.6%) had genotypes and phenotypes other than E2/2. One subject was apparently homozygous for apo E2 by IEF, but heterozygous for epsilon3/2 by RI. Sequencing of the apo epsilon gene disclosed a hitherto undescribed point mutation (TGG --> TGA) at the third position of the codon for amino acid 20 (Trp), introducing a premature termination codon. This is the first study demonstrating that in the German population type III HLP is mainly associated with homozygosity for apo E2 (Arg112 --> Cys, Arg158 --> Cys) and that discrepancies between apo epsilon genotype and apo E phenotype are rare in this genetic condition.

Type III hyperlipoproteinemia (HLP) is characterized by elevated concentrations of plasma cholesterol and triglycerides due to an increase in atherogenic beta-very low density lipoproteins (beta-VLDL). As a consequence, affected individuals develop premature and accelerated atherosclerosis. Fibrates have been shown to be most effective in treatment of the dyslipidemia in type III HLP. However, comparative data on the efficacy of different fibrates in this disorder are very limited; to assess this further we have compared in a prospective study the hypolipidemic effects of bezafibrate (400 mg once daily) and micronised fenofibrate (200 mg once daily) in 23 patients with well-characterized type III HLP. Baseline values were obtained after 4 weeks on diet and treatment values were obtained after 12 weeks of treatment with each drug. Treatment with bezafibrate and micronised fenofibrate both resulted in significant reductions in the serum concentrations of total cholesterol (26.0% and 38.7%), VLDL cholesterol (41.5% and 54.1%) and total triglycerides (27.5% and 39.1%), as well as a significant increase in high density lipoprotein (HDL) cholesterol (15.0% and 27. 8%). Micronised fenofibrate was, however, significantly (P < 0.05) more effective in reducing serum concentrations of total cholesterol and VLDL cholesterol and increasing HDL cholesterol than was bezafibrate in the same patients.