Hans Kaffarnik

Apolipoprotein E phenotypes and hyperlipidemia

SummaryApolipoprotein E phenotypes were determined in 361 patients with hyperlipidemia and in controls. The E2 isoform was significantly more frequent in the group of hyperlipidemics (P<0.0005). This was not due to a higher frequency of E-2/2 homozygotes with type III hyperlipoproteinemia, but rather to a significantly higher frequency of E2 heterozygotes (P<0.0005). Subgrouping of hyperlipidemics into patients with a) hypertriglyceridemia, b) hypercholesterolemia and c) mixed hyperlipidemia revealed i) that isoform E2 was significantly more frequent in patients with hypertriglyceridemia (0.001>P>0.005), ii) that isoform E4 was significantly more frequent in patients with hypercholesterolemia (0.01>P>0.005) and iii) that isoforms E2 (P>0.005) and E4 (0.05>P>0.025) were both more frequent in patients with mixed hyperlipidemia. Roughly 20% of patients with mixed hyperlipidemia had one of the rare phenotypes E-4/4,-4/2 or-2/2. We conclude that alleles ε2 and ε4 both contribute to the susceptibility for, and/or phenotypic expression of hyperlipidemia. Whereas the gene ε2 seems to exert its influence on plasma lipoproteins by an abnormal gene product (E2) that has reduced binding activity to lipoprotein receptors, the mechanism underlying the association of the ε4 gene with hyperlipidemia is presently unclear.

Differential distribution of apolipoprotein E isoforms in human plasma lipoproteins.

The polymorphism of apolipoprotein E (apo E) accounts for a substantial amount of the genetic variance of cholesterol levels In man. The e-2 allele lowers and the e-4 allele raises plasma and low density llpoproteln cholesterol levels as compared to the e-3 allele. Whereas the lower cholesterol levels in carriers of the e-2 allele can, at least In part, be attributed to the grossly deficient binding of apo E-2 to the apo B,E receptor, apo E-3 and E-4 bind to the same degree. We used gel filtration and uttracentrlfugatlon to separate lipoproteins and subsequent Immunoblottlng analysis to study the apo E Isoform distribution. We always found lipoproteins of lower density relatively enriched in apo E-4 and high density lipoproteins relatively depleted of apo E-4 as compared to apo E-3. This was also seen In plasma of heterozygous subjects that simultaneously express two apo E Isoforms. Also, the apo E-A-ll complex was directly shown by Immunoblottlng. Furthermore, when purified lodlnated apo E was incubated with plasma In vitro, apo E-4 also reassociated more with lipoproteins of lower density than apo E-3. We conclude that apo E-3 and apo E-4 have a different llpoprotein particle distribution in vivo. This differential llpoproteln distribution may account for differences In the metabolism between apo E-3 and E-4.

Multicenter Comparison of Micronized Fenofibrate and Simvastatin in Patients with Primary Type IIA or IIB Hyperlipoproteinemia

In 12 weeks of active treatment, we compared the efficacy and safety of a new (micronized) formulation of fenofibrate (F) (200 mg/day) with that of simvastatin (S) (20 mg/day), an inhibitor of hydroxy-methyl-glutaryl coenzyme A (HMG-CoA)-reductase. Men and women with primary hyperlipoproteinemia (HLP) with low-density lipoprotein (LDL) cholesterol level 180-300 mg/dl and triglyceride level < 500 mg/dl had dietary treatment for 8 weeks, and 133 (2 of 3 type IIa, 1 of 3 type IIb HLP) were randomized. The decrease in total cholesterol differed between type IIa patients (F - 17.9 vs. S - 25.8%), the decrease in triglyceride levels between the type II b groups (F - 52.8 vs. S - 14%), whereas the degree of decrease in LDL cholesterol (F - 20.9 vs. S - 34.9%) differed among all patients. Despite the difference in LDL cholesterol decrease, no difference was noted in total apolipoprotein (apo) B lowering (F - 20.8 and S - 26.5%). Increases in high-density lipoprotein (HDL) cholesterol (F + 18.5 vs. S + 15%) differed specifically in type IIb patients (F + 33.6 vs. S + 11.4%), accompanied by a more pronounced increase in apo AI with fenofibrate (F + 10.5% vs. S no change). Improvement in the ratios of total cholesterol/HDL cholesterol and apo AI/apo B occurred similarly with both drugs. Only fenofibrate, not simvastatin, decreased both fibrinogen (-10.3 vs. + 3.6%) and uric acid (-25% vs. no change) in type IIa and type IIb patients. Safety parameters reflected drug-specific known side effects, underscoring the safety of both drugs in addition to their efficacy in lipid lowering. Besides its advantages in type IIb hyperlipidemia, micronized fenofibrate proved a potent drug in decreasing total and LDL cholesterol and in very effectively decreasing apo B-containing lipoproteins, which is a recommendation for its use in primary hypercholesterolemia.

Metformin-induced changes in serum lipids, lipoproteins, and apoproteins in non-insulin-dependent diabetes mellitus

Forty patients with NIDDM and hyperlipoproteinemia were selected for a 12-week double-blind placebo-controlled trial to study the effects of metformin on lipoprotein concentration and composition. A significant decrease occurred in VLDL-apo B and all lipid components of VLDL, indicating a decreased number of circulating VLDL, while LDL-apo B was unchanged. Moreover in VLDL the relative TG content increased, the cholesterol content decreased, while in LDL the TG content decreased and the cholesterol content increased, indicating a change in the particle distribution over the spectrum VLDL-IDL-LDL. The initially enhanced TG-content in HDL was reduced. While a reduction in VLDL is observed together with improving glucose control irrespective of the applied method, the observed compositional changes in VLDL and LDL have not been described before and seem to be metformin-specific.

Changes of apolipoprotein A-IV in the human neonate: evidence for different inductions of apolipoproteins A-IV and A-I in the postpartum period

The levels, isoforms and distribution of apolipoprotein A-IV (apo A-IV) were investigated in 127 term human umbilical cord sera. In addition, apo A-IV levels and isoforms were determined on the 3rd (n = 82) and 6th (n = 68) day following parturition and compared to apo A-I concentrations. Levels of apo A-IV were low in umbilical cord serum (5.7 +/- 1.9 mg/dl) as compared to adult serum (17.6 +/- 4.8 mg/dl). No difference was found between male and female neonates. The serum distribution of apo A-IV closely resembled that seen in the adult human. Apo A-IV concentrations dramatically increased during the first week of life reaching levels of 13.4 +/- 4.1 mg/dl on day 3 and 16.7 +/- 3.4 mg/dl on day 6 post-partum. During this time apo A-I levels did not change significantly (81.0 +/- 16.5 mg/dl in cord serum, 75.3 +/- 10.6 mg/dl and 84.2 +/- 14.5 mg/dl on day 3 and 6, respectively). Cord serum already exhibited the major serum apo A-IV isoforms seen in the adult. Isofocusing of apo A-IV also identified the known genetic polymorphism of apo A-IV. Among 127 cord sera studied we identified 109 homozygote normal patterns, apo A-IV (1-1), 16 heterozygotes, apo A-IV (1-2) and 2 individuals homozygote for the variant peptide, apo A-IV (2-2). We provide evidence that apo A-IV and apo A-I are differently induced in the human neonate during the beginning of the feeding period.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasonography of achilles tendons in primary hypercholesterolemia: Comparison with computed tomography

Tendon xanthoma are a hallmark of familial hypercholesterolemia and are among its earliest clinical manifestations. Achilles tendon size, advanced to a generally accepted marker, is virtually specific for the disease and easily accessible for measurement. Hypercholesterolemic patients with coronary heart disease have been reported to have larger diameters of the Achilles tendons than patients without coronary problems. Furthermore, Achilles tendon xanthomas have been shown to regress with treatment of the lipid disorder. Mainly radiological procedures were applied in the past to evaluate the diameters of the Achilles tendon but their use is limited by radiation protection. We have used real-time ultrasonography to evaluate the Achilles tendons of 38 patients with primary hypercholesterolemia and 32 normocholesterolemic controls. The anterior posterior diameter in the patients was 13.4 +/- 5.9 mm (range 6-20 mm) and 5.7 +/- 0.7 mm (range 5-8 mm) in the control group. In 8 patients with newly diagnosed and previously untreated hypercholesterolemia the thickness correlated highly with their age. The Achilles tendons in about half of the patients (n = 21) showed a homogeneous thickening, whereas the others revealed an inhomogeneous thickening indicating the presence of circumscribed xanthoma. Upon comparison of the ultrasonographic procedure with an established method (computed tomography) in 18 patients and 8 normal volunteers a highly significant correlation (r = 0.96) proved the validity of the sonography. We show that real time ultrasonography is a valid procedure to assess Achilles tendon diameters in patients with primary hypercholesterolemia. It can be applied frequently and may be useful to follow xanthoma regression during lipid lowering treatment.

Polymorphism of apolipoprotein E influences levels of serum apolipoproteins E and B in the human neonate

Abstract. To gain more insight into the genetic vs. environmental influence of the apoE phenotypes on plasma lipoprotein variation we studied human umbilical cord sera at birth. Apolipoprotein E genetic phenotypes were determined in 110 individuals by immunoblottrag and shown to be identical to the adult human isoforms with six phenotypes present and occurring at a similar frequency as reported previously for the adult population in the same area. Total serum cholesterol and triglyceride levels were low in the neonates and did not differ significantly between apoE phenotypes. On the other hand as in the aduit, levels of apoE and B differed significantly between the phenotypes. ApoE was highest in individuals with the 62 allele and lowest in individuals expressing apoE4, and vice versa for apoB.

Impotence in patients treated with clofibrate

Three of our regularly controlled patients suffering from Type IV hyperlipoproteinemia and treated with clofibrate complained of impotence within one year after commencement of treatment with this drug. Two of the patients had previously suffered from myocardial infarction. Two patients observed improvement of the symptom 3 and 4 weeks after interruption of clofibrate therapy; one patient again complained of impotence when clofibrate therapy was resumed. The third patient continued intake of the drug up to the present day, and still complains of impotence.

Plasma lipids, triglyceride/fatty acid pattern, and plasma insulin in fasted healthy volunteers during continuous ingestion of ethanol: Influence of lipolysis inhibited by Nicotinic Acid

Healthy fasted volunteers were subjected to an acute oral ethanol load over 12 h after a diet of 3 days with high linolenic acid content. Free fatty acids, triglycerides, glycerol, phospholipids, cholesterol and insulin, as well as the fatty acid pattern of triglycerides in the plasma, were determined during the test. The test was repeated with nicotinic acid added. The lipid values obtained and the comparisons of fatty acid composition both indicate that the predominant role of peripheral lipolysis in the genesis of acute ethanol-induced hypertriglyceridemia, in spite of the possibility of enhanced synthesis of palmitic acid in the liver.

Purification of human serum amyloid A by anion-exchange fast protein liquid chromatography.

The plasma concentration of serum amyloid A (SAA), a plasma apolipoprotein mainly associated with high-density lipoproteins (HDL ), is increased by up to lOOO-fold as a response to certain acute phase reactions. This enormous increase can be used in the diagnosis of acute allograft rejection [l-3]. SAA, which consists of 104 amino acids, is also believed to be the precursor of the 76-amino-acid amyloid A (AA) protein found in tissue deposits of patients with secondary amyloidosis [4,5]. SAA exists in plasma in several isoforms [6-g]. Two of them, named SAA1 and SAA2 by Benditt and Eriksen [lo], represent the prominent forms. SAA, and SAA, differ in their aminoterminal arginine residue, which is missing in SAA*, giving rise to a p1 value of 0.5 lower than that of SAA,. We have developed a rapid method to isolate both SAA, and SAA, isoforms from human plasma by a combination of ultracentrifugation and fast protein liquid chromatography (FPLC ), using a Mono Q HR lO/lO preparative anionexchange column.