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Familial combined hyperlipidemia (FCHL) is characterized by elevated levels of serum total cholesterol (TC), triglyceride (TG), or both. The increased incidence of coronary artery diseases (CAD) in the patients with FCHL is believed to be caused by circulating atherogenic lipoproteins associated with the complex phenotype. Recent establishment of sensitive detection system for malondialdehyde-modified (MDA)-LDL, which is one of oxidized lipoproteins, showed its increased circulating level in the patients with CAD. In order to know the atherogenic lipoproteins resulted from the dyslipidemia observed in FCHL, we measured the serum MDA-LDL level in the patients. The circulating MDA-LDL level and the ratio of MDA-LDL and LDL-C in FCHL were significantly higher (P

Patients with heterozygous familial hypercholesterolemia (FH) were examined with B-mode ultrasound in order to determine intima-media thickness (IMT) in the common carotid artery, and to uncover potential risk factors responsible for the development of IMT. Ninety seven FH subjects and 132 non FH type IIa hyperlipidemic subjects were involved in the present study. Age was found to correlate positively with IMT in both FH and non FH groups. FH individuals showed a higher IMT, along with elevated low density lipoprotein (LDL) cholesterol levels, compared with age-matched non FH individuals. To clarify potential factors contributing to the formation and development of carotid atherosclerosis, we divided the FH subjects into two subgroups, namely FH with high IMT group (HIG), and those with low IMT group (LIG). We investigated those two subgroups on the presence of angiographically documented coronary heart disease (CHD), of family history of CHD and of ‘midband lipoproteins’ by polyacrylamide gel electrophoresis (PAGE) analysis, by matching for age and LDL-cholesterol (LDL-C) level. Fifty percent of FH men in HIG was found to have CHD, whereas only 14% of those in LIG had CHD (P

In a previous study it was shown that postprandial lipid metabolism is delayed in individuals with intra-abdominal visceral fat accumulation. Population studies have shown that as compared with individuals with apolipoprotein (apo) E3/3, those with phenotype apo E3/4 phenotype have higher plasma and low density lipoprotein (LDL)-cholesterol (C) concentration and increased susceptibility to coronary heart disease. The aim of the present study is to determine how apo E4 affects postprandial lipid metabolism by comparing individuals with apo E3/4 to those with apo E3/3 phenotype matched for abdominal visceral fat. Sixty-two Japanese subjects (41 male, 21 female) [average age 48+/-14 years; mean body mass index (BMI) 25+/-5.6 kg/m2] were recruited for this study. The subjects were divided into two groups: those with apo E3/3 (n=43) and those with apo E3/4 phenotype (n=19), as determined by isoelectric focusing (IEF). Visceral fat accumulation was analyzed as area of fat deposition by computerized tomography at the umbilicus level. After a 12-h overnight fasting, an oral vitamin A and a fatty meal were administered to these subjects. The plasma triglyceride (TG) increased significantly hours after fat loading in both groups but the levels of TG were significantly higher in apo E3/4 than in apo E3/3 phenotype at 2, 4 and 6 h after fat loading. Plasma retinyl palmitate (RP) levels were also significantly higher in individuals with apo E3/4 than in those with apo E3/3 phenotype at 2, 4 and 6 h after fat loading. This investigation was then conducted in both genders separately, and found that these associations were statistically significant in men. Furthermore, after matching men for fasting TG levels, these associations did not persist for plasma TG levels at any time point, while plasma RP levels were still significantly higher in apo E3/4 group at 2 and 6 h after fat loading. These results indicate that in Japanese population especially for men apo E phenotype E3/4 is associated with an impaired postprandial TG-rich lipoprotein metabolism relative to apo E3/3 phenotype when matched for intra-abdominal visceral fat accumulation, which has a substantial effect on the metabolism of plasma TG-rich lipoproteins.

The subject was a 57-year-old Japanese woman with a body mass index of 21.2 kgm(-2). Her serum total cholesterol (TC), triglycerides (TG) and HDL-cholesterol levels were 7.11 mmoll(-1), 0.53 mmoll(-1) and 2.05 mmoll(-1), respectively. She had a marked increase of serum apolipoprotein (Apo) E concentration of 25 mgdl(-1) with normal concentrations of serum Apo A-I, A-II, B, C-II and C-III. Polymerase chain reaction-restriction fragments length polymorphism analysis of the cholesteryl ester transfer protein (CETP) gene from this subject revealed the heterozygous nucleotide change causing a Asp442 to Gly substitution (D442G) in the CETP protein. For comparison, 11 unrelated female subjects with this mutation (age, 57+/-5.1 years; BMI, 22+/-1.5 kgm(-2); TC, 7.23+/-1.16 mmoll(-1); TG, 1.44+/-0.80 mmoll(-1); HDL-C, 2.47+/-0.53 mmoll(-1)) were found to have a serum Apo E concentration of 7+/-1.5 mgdl(-1), about a third of the patient's concentration. The lipoprotein profile of the proband's serum analyzed by disk polyacrylamide gel electrophoresis showed a trace amount of VLDL. A vitamin A fat-loading test showed little increase in serum triglycerides and retinyl palmitate levels compared with control subjects at 2, 4 and 6 h after fat loading. Ultracentrifugation analysis of her serum revealed no detectable Apo E in the VLDL fraction but showed a large amount of Apo E in the HDL fraction, in contrast to a normal control, who had Apo E in the VLDL fraction as well as in the HDL fraction. Sequence analysis of the Apo E gene from the subject showed no nucleotide changes in exon 3 and exon 4, which code the mature Apo E protein, indicating there is no structural abnormality in the Apo E protein. Direct sequence analysis of the LDL receptor gene also did not show any nucleotide change. Based on these findings, it was hypothesized that the marked increase of Apo E in the patient's serum was caused by a decreased transfer of Apo E from HDL particles to TG-rich lipoproteins or impaired uptake of Apo E-containing HDL by LDL receptor or remnant receptor, due presumably to a dysfunction of these receptors in the patient.

Postprandial hyperlipidemia is frequently accompanied with intra-abdominal visceral accumulation in human subjects. We have found that the decreased lipoprotein lipase (LPL) mass and activity is negatively associated with the amount of visceral fat accumulation. Here, we studied the postprandial hyperlipidemia using the OLETF rat, a model with visceral obesity, in order to clarify the molecular mechanism causing postprandial hyperlipidemia accompanied with visceral obesity. At the same age of 32 weeks, the OLETF rats showed obviously higher plasma leptin, total cholesterol, triglyceride, and HDL-cholesterol levels than the control LETO rats, although the plasma glucose level was not significantly different. Fat-loading test revealed the delayed metabolism of exogenous fat in the OLETF rats compared to the LETO rats, similar to human subjects with visceral obesity. In the obese rats, plasma levels of LPL mass and activities were 60 and 49% of control rats. The expression of LPL gene was decreased in subcutaneous adipose tissues and skeletal muscle of OLETF rats to 40 and 52% compared to those of LETO rats. In OLETF rats, plasma tumor necrosis factor-alpha (TNF-alpha) and insulin levels were increased to 2.0- and 2.3-folds compared to those in control rats. Furthermore, plasma insulin and TNF-alpha levels in OLETF rats were negatively correlated with the expression levels of LPL gene in subcutaneous fat and muscle. These results indicate that decreased LPL mass and activity in the animal model with visceral obesity is possibly caused by decreased expression of LPL gene in tissues mediated by the increased levels of insulin and TNF-alpha. The different expression of LPL gene in tissues associated with the increased levels of insulin and TNF-alpha possibly elucidate the underlying mechanisms involving the postprandial hyperlipidemia observed in visceral obesity.

A 61-year-old Japanese woman with heterozygous familial hypercholesterolemia (FH), type 2 diabetes mellitus and coronary artery disease underwent coronary artery bypass grafting (CABG) utilizing a saphenous vein graft at the age of 46, in June 1984, 6 months before low density lipoprotein (LDL) apheresis was started. She had received LDL apheresis every two weeks, along with combined drug treatment since the age of 47 (December 1984). She had bilateral xanthelasma and Achilles tendon xanthomas. Her fasting baseline serum total cholesterol and triglyceride level were 464 mg/dl and 57 mg/dl, respectively at the age of 47 when she visited our hospital for the first time. Analysis of the genomic DNA from the patient revealed heterozygous amino acid substitution of Leu for Pro664 in the LDL receptor gene. She was diagnosed as type 2 diabetes mellitus at the age of 53. Combined treatment in the steady state yielded a pretreatment LDL cholesterol level of 230+/-14 mg/dl and a posttreatment level of 57+/-7.6. All grafts were widely patent after as long as 14 years since CABG, suggesting that LDL apheresis combined with drug therapy is highly effective in preventing the occlusion of bypass grafts in a patient with heterozygous FH and type 2 diabetes mellitus.

A new heterozygous lipoprotein lipase gene defect has been identified in a type I hyperlipidemic patient at the position of notable amino acid Asn 291. The patient is a 33-year-old male. His body mass index (BMI) was 18.5 kg/m2. The total cholesterol (TC), triglycerides (TG) and high density lipoprotein-cholesterol (HDL-C) concentration from his fasting plasma were 4.8, 11.9 and 0.4 mmol/l, respectively. The lipoprotein lipase (LPL) activity and mass in the postheparin plasma (PHP) from the patient were 0.58 mmol/ml/h (normal range: 7.7±2.6) and 244 ng/ml (normal range: 192±30), respectively. The hepatic lipase activity of the PHP from the patient was 10.6 mmol/ml/h (normal range: 9.9±3.6). DNA analysis of the LPL gene revealed that this patient had a heterozygous one nucleotide deletion of A coding Asn 291, resulting in a premature termination of the LPL protein at amino acid residue 303. The other abnormality in the LPL gene of the proband was an amino acid residue 194 defect (Ile194→Thr), which is known to cause a defective enzyme. A medium-chain triglyceride (MCT) loading test was conducted to find how this triglyceride affects plasma lipoprotein metabolism in this patient in a short term ( Fig. 3 ). The plasma total cholesterol (TC) or high density lipoprotein (HDL)-C levels did not change significantly after oral administration of a fatty meal containing long chain triglycerides (LCT) or MCT. The plasma TG level, on the other hand, increased from 11.9 to 19.2 mmol/l (+61%) at 6 h after loading a fatty meal containing LCT, whereas the plasma TG levels tended to even decrease at 6 h after oral administration of an MCT, tricaprin (from 11.6 to 10.5 mmol/l (−9.4%)). These results suggest that MCT, as opposed to LCT, is useful for treatment of type I hyperlipidemia with a novel mutation at the notable amino acid Asn 291 of the LPL gene.