Serum apolipoprotein levels of psoriatic patients with normal serum lipid levels

OBJECTIVE

Recent studies indicated that incidence of occlusive cardiovascular diseases increased in psoriasis. Changes of serum lipid metabolism may be the cause. Apolipoproteins play a central role in lipoprotein metabolism in serum. The measurement of serum apo levels may reveal the characteristics of lipoprotein metabolism in serum in patients with psoriasis and may help to find an answer to the cause of the high incidence of occlusive cardiovascular diseases in psoriasis.

METHOD

The apo levels of 31 patients with psoriasis vulgaris and 31 sex- and age-matched healthy individuals with normal serum lipid levels were measured by radial immunodiffusion assay.

RESULTS

The apo C III (t = 2.44, P < 0.05) and apo E (t = 2.12, P < 0.05) of psoriatic group elevated significantly. The apo C III (t = 2.77, P < 0.01) of patients less than 40-year-old and apoE (t = 2.91, P < 0.01) of male patients elevated significantly.

CONCLUSION

Abnormal metabolism of lipoprotein in serum exist in psoriasis, especially in male patients and/or patients less than 40 years old.

Abnormalities of apolipoprotein E in the acquired immunodeficiency syndrome

Given the important role of apolipoprotein E (apoE) in triglyceride metabolism, we analyzed plasma levels and degree of sialylation of apoE in subjects with the acquired immunodeficiency syndrome (AIDS), a disorder accompanied by hypertriglyceridemia. Levels of apoE were significantly increased (1.84-fold) and correlated with plasma triglycerides (r = .663, P < .001) in AIDS. Subjects with AIDS and the apoE3/E2 phenotype showed the most prominent increases in both plasma triglyceride and apoE levels (3.4 and 2.2-fold over controls). Additionally, apoE from subjects with AIDS showed an increased amount of sialylation, compared with controls (34% increase in apoE3/E3 subjects). Increased sialylation correlated with the increase in apoE levels. In contrast, there was no increase in sialylation of apo C-III in AIDS. Thus, triglyceride levels in AIDS are influenced by apoE subtype and subjects with AIDS show changes in apoE structure.

Guinea pig apolipoprotein C-II: expression in E. coli, functional studies of recombinant wild-type and mutated variants, and distribution on plasma lipoproteins

Guinea pig apolipoprotein C-II (apoC-II) lacks four amino acid residues in the amino-terminal, lipid-binding part compared to apoC-II from other mammalian species (Andersson et al. 1991. J. Biol. Chem. 266: 4074-4080). To explore whether this structural difference explains the low ability of guinea pig plasma to activate lipoprotein lipase in vitro, we have expressed guinea pig apoC-II in Escherichia coli and have constructed an insertion mutant with the four missing amino acid residues compared to human apoC-II. With a synthetic emulsion of long-chain triacylglycerols, both the wild-type guinea pig apoC-II and the insertion mutant stimulated lipoprotein lipase similar to human apoC-II, but with chylomicrons from an apoC-II-deficient patient, 5- to 10-fold more of both wild-type guinea pig apoC-II and the insertion mutant were needed. Studies of tryptophane fluorescence indicated a slight difference in how guinea pig apoC-II interacted with liposomes, and presumably with lipoproteins, as compared to human apoC-II. The level of apoC-II (11.5 +/- 5.4 microg/ml) was lower in guinea pig compared to human plasma, and most of guinea pig apoC-II was on HDL-like particles. These had decreased ability to donate apoC-II to lipid emulsions compared to human HDL. Some guinea pig apoC-II was associated with LDL which, as demonstrated by surface plasmon resonance, had higher affinity for lipoprotein lipase than human LDL, and inhibited rather than stimulated the lipase reaction in vitro. We conclude that while guinea pig apoC-II is fully competent to stimulate lipoprotein lipase, the sum of several different factors explains the low ability of guinea pig plasma to accomplish stimulation.

Development of a lipoprotein profile using capillary electrophoresis and mass spectrometry

A new program for lipoprotein characterization is outlined where capillary electrophoresis (CE) plays a central role in the analysis of intact lipoprotein serum components and the apoprotein domains. The first characterization step involves separation and particle density analysis of very low-, low-, and high-density lipoprotein fractions (VLDL, LDL, HDL) by ultracentrifugation and image analysis. VLDL, HDL, and LDL fractions are analyzed by capillary electrophoresis. Sodium dodecyl sulfate (SDS) at low concentrations in the background electrolyte used in the CE analysis is incorporated into the lipoprotein particle without appreciable delipidation, as determined by ultracentrifuge particle density analysis. Increasing the concentration of SDS results in extensive delipidation, resulting in the release of apoproteins (apo) which are detected as components of the electropherogram. Apo B-100 is detected in the delipidated VLDL and LDL fractions along with micelles of the lipids. Micelles from LDL delipidation have uniform charge densities. Apo A-I and A-II are detected in the HDL fraction. A new method for lipoprotein delipidation is introduced where the lipoprotein fraction is adsorbed on a reversed-phase hydrophobic cartridge. Delipidation and recovery of the apoprotein fractions is made by serial elutions with acetonitrile. CE of the lipid-free apoprotein mixture shows the presence of apoC-I,II,III and apoE in the VLDL fraction, and apoA-I,II apoC-I and apoE in the HDL fraction. Electrospray ionization mass spectrometry analysis gives the isoform distribution for each apoprotein. The identification of the apoproteins in the electropherograms is the first step in developing a CE-based quantitation method for measuring serum levels of these apoproteins and their distribution between the lipoprotein fractions. The assay described in this paper is being used as a level 2 and 3 cardiac risk profile analysis for individuals with normal lipid profiles who have a documented or family history of cardiovascular disease.

Characterization of hypertriglyceridemia induced by L-asparaginase therapy for acute lymphoblastic leukemia and malignant lymphoma

Plasma lipids and apolipoproteins were determined in 19 children with acute lymphoblastic leukemia (ALL) or malignant lymphoma (ML) who were treated by L-asparaginase with prednisolone and vincristine. Extreme hypertriglyceridemia, i.e., over 10,000 mg/l of the maximum serum triglyceride concentration, was induced in 8 patients; these concentrations were not over 10,000 mg/l in the remaining 11 patients. The possibility was raised that the apolipoprotein E (apoE) isoform apoE4 (epsilon 4) participated in the induction of extreme hypertriglyceridemia, since the frequency of the apoE4/E3 phenotype in the patients with extreme hypertriglyceridemia was higher compared to those in the patients without extreme hypertriglyceridemia and control subjects (n = 248). The acute and severe hypertriglyceridemia was induced at 8 to 14 days after the end of the L-asparaginase therapy, with an earlier remarkable increase in the apoCIII/apoCII ratio and an extreme decrease of fibrinogen concentrations (a marker of the protein productivity of the liver). It is well known that apoCII and apoCIII have possible functions as an activator and an inhibitor of lipoprotein lipase (LPL), respectively. The extreme increase in the apoCIII/apoCII ratio could be one of the reasons for the accumulation of triglyceride-rich lipoproteins in plasma.

Lipid binding of apolipoprotein CII is required for stimulation of lipoprotein lipase activity against apolipoprotein CII-deficient chylomicrons

Human apolipoprotein CII (apo CII) consists of 79 amino acid residues. The amino-terminal two thirds of the molecule binds to lipid through the formation of amphipathic helixes, while the carboxy-terminal third is engaged in activation of lipoprotein lipase (LPL). On the basis of studies in model systems, it was previously concluded that fragments of apo CII spanning residues 51-79 were sufficient for activation, although they do not bind to lipid. In the present study, we used chylomicrons from an apo CII-deficient patient to reinvestigate this possibility, with a physiologically relevant substrate. Human LPL expressed very low activity against these chylomicrons. Addition of apo CII caused an immediate > 100-fold increase in lipase activity. The apo CII fragment 50-79 caused very little stimulation, though with some synthetic lipid substrates, this fragment was fully effective. LPL bound to the chylomicrons even in the absence of apo CII but apparently in a nonproductive manner. In accord with this finding, the main effect of apo CII was on the VMAX for the reaction, with little or no change in the apparent K(M). We conclude that the lipid-binding part of apo CII is needed for activity of LPL against chylomicrons. This idea is in accord with previous studies with lipid monolayers, which showed that the lipid-binding part is necessary for activation of the enzyme at high surface pressures.

Plasma lipoprotein distribution of apoC-III in normolipidemic and hypertriglyceridemic subjects: comparison of the apoC-III to apoE ratio in different lipoprotein fractions

In order to assess the relationship between plasma accumulation of triglyceride-rich lipoproteins (TRL) and lipoprotein levels of apoC-III and apoE, we have measured apoC-III and apoE in lipoproteins separated according to size (by automated gel filtration chromatography) from plasma of normolipidemic subjects (plasma triglyceride (TG): 0.84 +/- 0.10 mmol/l; mean +/- SE, n = 8), and from type III (n = 8) and type IV (n = 8) hyperlipoproteinemic patients, matched for plasma TG (5.76 +/- 0.62 v 5.55 +/- 0.45 mmol/l, resp.). Total plasma apoC-III concentration was similar in type III and type IV patients (33.1 +/- 3.4 v 37.6 +/- 4.4 mg/dl, respectively), but was significantly increased compared to normolipidemic controls (10.0 +/- 1.0 mg/dl, P < 0.001). TRL apoC-III was lower and high density lipoprotein (HDL) apoC-III was significantly higher in type III versus type IV subjects (14.8 +/- 3.2 vs. 22.8 +/- 3.0 mg/dl, P < 0.05; 8.3 +/- 1.0 vs. 5.2 +/- 0.5 mg/dl, P < 0.05). Plasma concentration of apoC-III in lipoproteins that eluted between TRL and HDL (intermediate-sized lipoproteins, ISL) was similar in the two hypertriglyceridemic groups (10.1 +/- 1.3 vs. 9.7 +/- 1.6 mg/dl), but was significantly higher (P< 0.05) than controls (2.2 +/- 0.3 mg/dl). TRL, ISL, and HDL apoE concentrations were significantly higher in type III versus type IV subjects (P < 0.05). All lipoprotein fractions in type III patients were characterized by lower apoC-III to apoE ratios. In contrast, the TRL apoC-III to apoE ratio of type IV patients was similar and the ISL apoC-III to apoE ratio was significantly higher, compared to normolipidemic individuals. These results indicate that compared to normolipidemic individuals, remnant-like lipoproteins in the ISL fraction of type IV patients are enriched in apoC-III relative to apoE, whereas those of type III patients are enriched in apoE relative to apoC-III.

A variation in the apolipoprotein C-III gene is associated with an increased number of circulating VLDL and IDL particles in familial combined hyperlipidemia

Detailed plasma lipoprotein analyses were conducted on 16 familial combined hyperlipidemic (FCHL) probands, all their available family members (n = 106) together with 12 normolipidemic control families (n = 68), and the results were assessed in relation to a C1100-T polymorphism in exon 3 of the apoC-III gene. The frequency of the T1100 genotype (CT+TT) was significantly elevated in the probands relative to control subjects (0.64 vs. 0.36; P < 0.01) and was associated with elevated concentrations of plasma triglyceride (P < 0.02) and apoC-III (P < 0.03), VLDL cholesterol (P < 0.005), VLDL triglyceride (P < 0.009), IDL cholesterol (P < 0.01). and IDL triglyceride (P < 0.007). The T1100 genotype was also associated with elevations in VLDL-apoB (P < 0.005) and IDL-apoB (P < 0.04) indicating a relationship between this variation and an increased number of triglyceride-rich particles. These findings were confined to the hyperlipidemic members of the FCHL families and showed a strong genotype-status interaction (P < 0.001). It is considerable clinical relevance that the apoC-III gene may be acting as a modifier gene that is only expressed in the presence of other factors (e.g., increased VLDL flux, low LPL activity) and therefore may predispose those members of FCHL families carrying the T1100 allele to express the FCHL phenotype.

Gallstones and their chemical types in relation to serum lipids and apolipoprotein levels

OBJECTIVE

To determine the profile of lipidemia in patients with gallstones and the characteristics of lipidemia in different kinds of gallstone in gallbladder for predicting high risk subjects predisposed to gallstone formation by means of some serum parameters.

METHODS

Serum lipids and apolipoproteins levels in 47 patients with stone in gallbladder (stone group) were compared with those in 19 inpatients without stone (control group). The characteristics of lipidemia in different kinds of gallbladder stones were also compared.

RESULTS

Serum apolipoprotein (Apo) A1, C2 and E levels in the stone group significantly increased as compared with the control group (P < 0.01), but there were no statistically significant differences in TC, TG, LDL-C, HDL-C, HDL-C/TC, LDL-C/HDL-C, Apo A2, B and C3 and Apo A1/Apo B levels between the stone and control groups (P > 0.05). Increased levels of serum LDL-C and Apo B and the LDL-C/HDL-C ratio (P < 0.05) were characterized as an index of cholesterol stones, while elevated levels of serum TG and Apo C2 (P < 0.05) as an index of pigment stones.

CONCLUSIONS

Serum apolipoproteins might be more sensitive parameters as compared with serum lipids in distinguishing patients with stones from subjects without stones. There are different profiles of serum lipids and apolipoproteins in different chemical types of gallbladder stones.

Complex genetic contribution of the Apo AI-CIII-AIV gene cluster to familial combined hyperlipidemia. Identification of different susceptibility haplotypes

Familial combined hyperlipidemia (FCH) is a common genetic lipid disorder in Western societies. In a recent report (Dallinga-Thie, G.M., X.D. Bu, M. van Linde-Sibenius Trip, J.I. Rotter, A.J. Lusis, and T.W.A. de Bruin. J. Lipid Res., 1996, 36:136-147) we have studied three restriction enzyme polymorphisms: XmnI, and MspI sites 5' of the apo AI gene and SstI site in the 3' untranslated region of exon 4 of the apo CIII gene in 18 FCH pedigrees, including 18 probands, 178 hyperlipidemic relatives, 210 normolipidemic relatives, and 176 spouses. DNA variations in the apo AI-CIII-AIV gene cluster had a modifying effect on plasma triglycerides, LDL cholesterol, and apolipoprotein CIII levels. In this study, combinations of haplotypes were analyzed to further characterize their interactions and effect on the expression of severe hyperlipidemia in FCH subjects. A specific combination of haplotypes with one chromosome carrying the X1M1S2 (1-1-2) haplotype and the other the X2M2S1 haplotype (2-2-1) was significantly more frequent in hyperlipidemic relatives (6%) than in normolipidemic relatives (3%) and spouses (0.5%). Associated with this combination of haplotypes were significantly elevated plasma cholesterol (P < 0.0001), triglycerides (P < 0.0001), and apo CIII (P < 0.001) levels when compared to the wild type combination of haplotypes 1-1-1/1-1-1. The only spouse with this specific combination of haplotypes showed a severe hyperlipidemic phenotype, similar to FCH. Furthermore, nonparametric sibpair linkage analysis revealed significant linkage between these markers in the gene cluster and the FCH phenotype (MspI P = 0.0088, SstI P = 0.044, and XMS haplotype P = 0.037). The present findings confirm that the apo AI-CIII-IV gene cluster contributes to the FCH phenotype, but this contribution is genetically complex. An epistatic interaction between different haplotypes of the gene cluster was demonstrated. The S2 allele on one haplotype was synergistic to the X2M2 allele on the other haplotype in its hyperlipidemic effect. Therefore, two different susceptibility loci exist in the gene cluster, demonstrating the paradigm of complex genetic contribution to FCH.

[The serum lipid and apolipoprotein levels of middle-aged male hyperlipidemics in Chengdu district]

It has been evidenced that cardiovascular diseases (CVD) relate with many risk factors and serum lipids play and essential role in the development of CVD. In order to further study hyperlipidemia (HL) in the middle-aged males, we analysed the body mass index (BMI), fast blood sugar (FBS), serum lipids and apolipoproteins A I, A II, B100, C II, C III and E in 223 male HL patients aged 41-60 and 349 normal male subjects who matched the HL patients in age. The result showed that the increase of serum triglycerids (TG), was as might be expected, the major characteristic of the middle-aged male HL patients in Chengdu District. Besides the serum lipid and apolipoprotein B100, C II, C III and E levels, the BMI and FBS levels in the IIb, IV and V types of HL patients were significantly higher than those in the normal subjects. It also showed that in TG increased patients the increased percentages of serum lipids were significantly higher than those of apolipoproteins. The age distribution in HL patients revealed that only 25% of the HL patients were between 41 to 50 years old, while 50% in the 56-60 year-old group. The relationship between apolipoprotein levels and serum lipid metabolism is also discussed. The results suggest that the 51-60 year-old males should pay attention to diet and increase physical activities to reduce incidence of HL which is directly associated with CVD.

[Serum apolipoprotein C II, C III and E levels in 437 male healthy subjects aged 40-70 in Chengdu area]

Apolipoprotein (apo) C II, C III and E levels of 437 male healthy subjects aged 40-70 [with fasting serum triglyceride (TG levels < 2.26 mmol/L, total cholesterol (TC) levels < 6.21 mmol/L and plasma glucose levels < 6.10 mmol/L] in Changdu area were determined by radial immunodiffusion assay (RID). The results showed that the concentrations of apoC II, C III and E were 41.6 +/- 13.1, 112.8 +/- 31.0 and 38.7 +/- 8.2 mg/L (mean +/- s) respectively. No difference in the serum levels of apoC II, C III and E was noted between the men of different ages. The results of the linear correlation showed that there was a positive correlation of apoC II, C III, E with TG, TC, LDL-C; of apoC II, C III with BMI; and of apoE with ages.

[Relation of serum apolipoprotein B100 levels to lipids and apolipoproteins A I, A II, C II, C III and E levels in the middle and old age normal males in Chengdu area]

This study was conducted in 438 normal men aged 40-70. The age groups were: 40-44, 45-49, 50-54, 55-59, 60-64, and 65-70. The results showed that the serum apolipoproteins levels (mean+/- s, mg/L) were: B100 levels 742.5 +/- 165.8, A I 1301.2 +/- 219.9, A II 299.4 +/- 49.0, C II 42.7 +/- 21.4, C III 113.3 +/- 34.0 and E 38.7 +/- 8.2. The levels of serum apoB100 increased with age. The serum apoB100 levels in the 5th and 6th age groups were significantly higher as compared with the groups 1, 2, 3 and 4 (P < 0.05 and P < 0.05). The fasting serum mean TG (1.39 +/- 0.45 mmol/L), TC(4.79 +/- 0.82 mmol/L) and LDC-C(1.62 +/- 0.40 mmol/L levels in the groups 5 and 6 were significantly higher as compared with the groups 1, 2, 3 and 4 (P < 0.01). Serum apoC II, C III and E levels were significantly increased in the groups 5, 6 (P < 0.05). The correlation analysis indicated that there was a positive correlation of apoB100 with serum TG, TC, LDL-C, apoC II, C III and E respectively (P < 0.01); and a negative correlation with HDL-C levels (r = 0.1312); and apoB100 correlated negatively with apoA I (r = -0.0706). The results suggest that serum TG, TC, LDL-C, apoC II, C III and E are the main factors related with the serum apoB100 levels.

Alterations of VLDL composition during alimentary lipemia

Apoliprotein (apo) B-100-containing very low density lipoprotein (VLDL) particles secreted from the liver accumulate in plasma during alimentary lipemia. To determine whether changes of VLDL composition occur in the postprandial state that may render these lipoproteins more atherogenic, apoE, C-I, C-II, and C-III, and lipids (triglycerides, phospholipids, and cholesterol) were measured in Svedberg flotation (Sf) 60-400 (large) and Sf 20-60 (small) VLDL before and after an oral fat load. Ten normotriglyceridemic (NTG) and three hypertriglyceridemic (HTG) healthy men were given a fat-rich mixed meal (1,000 kCal with 60.2 E% from fat). Triglyceride-rich lipoproteins were isolated by density gradient ultracentrifugation from plasma samples obtained before (fasting) and at 2-h intervals after the meal. VLDL was then separated from chylomicrons and their remnants by immunoaffinity chromatography using monoclonal antibodies 4G3 and 5E11, recognizing apoB-100, but not apoB-48 epitopes. Large and small VLDL isolated from the NTG group were enriched with apoE and C-I, and cholesterol, but depleted of apoC-II in the postprandial state, whereas the apoC-III, triglyceride, and phospholipid contents were essentially unchanged. The compositional changes of VLDL in HTG subjects were similar but more pronounced compared with NTG subjects. We conclude that postprandial lipemia in healthy men induces transient compositional alterations of VLDL that link these lipoprotein species to the formation of atherosclerosis.

Reduced very-low-density lipoprotein fractional catabolic rate in apolipoprotein C1-deficient mice

The function of apolipoprotein (apo) C1 in vivo is not clearly defined. Because transgenic mice overexpressing human apoC1 show elevated triacylglycerol (TG) levels [Simonet, Bucay, Pitas, Lauer and Taylor (1991) J. Biol. Chem. 266, 8651-8654], an as yet unknown role for apoC1 in TG metabolism has been suggested. Here we investigated directly the effect of the complete absence of apoC1 on very-low-density lipoprotein (VLDL)-TG lipolysis, clearance and production, by performing studies with the previously generated apoC1-deficient mice. On a sucrose-rich, low fat/low cholesterol (LFC) diet, apoC1-deficient mice accumulate in their circulation VLDL particles, which contain relatively lower amounts of lipids when compared with VLDL isolated from control mice. Lipolysis assays in vitro on VLDL from apoC1-deficient and control mice showed no differences in apparent K(m) and Vmax values (0.27 +/- 0.06 versus 0.24 +/- 0.03 mmol of TG/litre and 0.40 +/- 0.03 versus 0.36 +/- 0.03 mmol of non-esterified fatty acid (NEFA)/min per litre respectively). To correct for potential differences in the size of the VLDL particles, the resulting K(m) values were also expressed relative to apoB concentration. Under these conditions apoC1-deficient VLDL displayed a lower, but not significant, K(m) value when compared with control VLDL (3.44 +/- 0.71 versus 4.44 +/- 0.52 mmol of TG2/g apoB per litre). VLDL turnover studies with autologous injections of [3H]TG-VLDL in vivo showed that the VLDL fractional catabolic rate (FCR) was decreased by up to 50% in the apoC1-deficient mice when compared with control mice (10.5 +/- 3.4 versus 21.0 +/- 1.2/h of pool TG). No significant differences between apoC1-deficient and control mice were observed in the hepatic VLDL production estimated by Triton WR139 injections (0.19 +/- 0.02 versus 0.21 +/- 0.05 mmol/h of TG per kg) and in the extra-hepatic lipolysis of VLDL-TG (4.99 +/- 1.62 versus 3.46 +/- 1.52/h of pool TG) in vivo. Furthermore, [125I]VLDL-apoB turnover experiments in vivo also showed a 50% decrease in the FCR of VLDL in apoC1-deficient mice when compared with control mice on the LFC diet (1.1 +/- 0.3 versus 2.1 +/- 0.1/h of pool apoB). When mice were fed a very high fat/high cholesterol (HFC) diet, the VLDL-apoB FCR was further decreased in apoC1-deficient mice (0.4 +/- 0.1 versus 1.4 +/- 0.4/h of pool apoB). We conclude that, in apoC1-deficient mice, the FCR of VLDL is reduced because of impaired uptake of VLDL remnants by hepatic receptors, whereas the production and lipolysis of VLDL-TG is not affected.

Post-prandial metabolism of triglyceride-rich lipoproteins in non-insulin-dependent diabetic patients before and after bezafibrate treatment

Retarded post-prandial (pp) lipid clearance is potentially a major component of the increased cardiovascular risk incurred by hypertriglyceridaemic non-insulin-dependent diabetic mellitus (NIDDM) patients. The effect of bezafibrate (Bz, 400 mg per day for 5 weeks on chylomicron (CM) and remnant clearance after loads of 100 g of fat and vitamin A was therefore explored in 10 male patients (glycaemia 11.9 +/- 3.3 TG 4.5 +/- 2.4 mmol L(-1)). In all subjects CM-TG and retinyl palmitate (RP) were reduced by 50%, but 8-h non-CM (remnant) RP decreased only in initially mildly hypertriglyceridaemic subjects (-35%, P < 0.05), while in three patients with very elevated initial TG (epsilon3/3, epsilon3/2 and epsilon2/2 genotypes) 8-h remnant RP increased by 100%. The decrease in pp CM-TG correlated with that of fasting Sf 20-400 (r = 0.686, P = 0.026), suggesting that improved lipolysis was a major determinant of hypolipidaemic effect. Apo CIII synthesis is known to be depressed by Bz: concentrations were lower under Bz (P < 0.05). A positive correlation (r = 0.880, P < 0.001) with fasting TG before treatment and its disappearance after treatment suggested an involvement of high concentrations with hypertriglyceridaemia. Post-prandial non-esterified fatty acids were decreased by 35 in correlation with a significant (-19%, P < 0.05) improvement in fasting glycaemia (r = 0.801, P < 0.005). These results suggest that Bz acts both on lipolysis and on removal of CM remnants, but that removal can become saturated when lipolysis is massively improved.

Changes in serum apolipoprotein and lipoprotein profile induced by chronic alcohol consumption and withdrawal: determinant effect on heart disease?

The effects of alcohol consumption on serum concentrations of apolipoproteins (apo) A-I, C-III, B, and E and of lipoproteins (Lp) A-I, A-I:A-II, C-III, C-III:B, and (a) were studied in 132 healthy subjects, including 55 low drinkers of alcohol (<20 g/day), 36 moderate drinkers (20-50 g/day), and 41 heavy drinkers (>50 g/day), and in 97 hospitalized alcoholic patients (> 100 g/day) without severe liver disease (especially functional insufficiency), before and after 21 days of withdrawal treatment. Serum concentrations of apo A-I, LpA-I, LpA-I:A-II, apo C-III, and LpC-III significantly (P </= 0.01) increased with alcohol intake (mean +/- SE in low drinkers vs in alcoholics)--1.45 +/- 0.03 vs 1.78 +/- 0.05 g/L; 0.45 +/- 0.02 vs 0.56 +/- 0.02 g/L; 0.99 +/- 0.02 vs 1.22 +/- 0.04 g/L; 27.6 +/- 1.5 vs 39.7 +/- 1.7 mg/L; and 8.4 +/- 0.9 vs 24.7 +/- 1.7 mg/L, respectively-whereas apo B and LpC-III:B concentrations tended to decrease--1.20 +/- 0.04 vs 1.06 +/- 0.04 g/L and 19.3 +/- 1.2 vs 14.9 +/- 1.0 mg/L, respectively. No significant difference between these four types of alcohol consumption was noticed for cholesterol, triglycerides, apo E, and Lp(a). After withdrawal, the concentrations of serum apo A-I, apo C-III, LpA-I, LpA-I:A-II, and LpC-III decreased significantly (P </= 0.01), reaching values comparable with those in low drinkers; concentrations of triglycerides, apo B, apo E, and Lp(a) rose; and cholesterol concentration was unaffected. In multiple regression analysis, after adjustment for serum concentrations of albumin, aspartate aminotransferase, and gamma-glutamyltransferase and for the Quetelet index, alcohol consumption remained positively correlated to apo A-I, LpA-I:A-II, apo C-III, and LpC-III concentrations. Study of other determinants of serum apo and lipoprotein concentrations suggests that alcohol-related variations in some of them, especially apo A-I, might depend on the metabolic ability of the liver to synthesize proteins and on induction phenomena. Finally, although the increase of antiatherogenic apo- and lipoproteins and the decrease of those known to be atherogenic were generally marked in alcoholics, alcohol-related modifications of these markers were very limited in our sample of French healthy men. We conclude, therefore, that moderate alcohol consumption (20-50 g/day) is unlikely to protect against ischemic heart disease through an effect on the proteins measured in this study.

Effects of gemfibrozil or simvastatin on apolipoprotein-B-containing lipoproteins, apolipoprotein-CIII and lipoprotein(a) in familial combined hyperlipidaemia

BACKGROUND

Familial combined hyperlipidaemia (FCH), characterized by elevated very-low-density lipoprotein (VLDL) and/or low-density lipoprotein (LDL), is associated with an increased prevalence of premature cardiovascular disease. Therefore, lipid-lowering is frequently indicated.

METHODS

We evaluated in a parallel, double-blind randomized fashion the effect of gemfibrozil (1200 mg/day) (n = 40) or simvastatin (20 mg/day) (n = 41) on lipids, apolipoprotein-B (apo-B)-containing lipoproteins, apo-CIII and lipoprotein(a) [Lp(a)], in 81 well-defined FCH patients.

RESULTS

While both drugs lowered plasma cholesterol and triglyceride levels, gemfibrozil lowered plasma triglycerides more effectively by reduction of triglycerides in VLDL and LDL, whereas simvastatin was more effective in its reduction of total plasma cholesterol by exclusively decreasing LDL cholesterol. High-density lipoprotein (HDL) increased to an equal extent on both therapies. Total serum apo-B levels were reduced with both drugs; however, gemfibrozil decreased apo-B only in VLDL + IDL, whereas simvastatin decreased apo-B in both VLDL + IDL and LDL. In keeping with a more effective reduction of VLDL particles, a more pronounced reduction of apo-CIII also was observed after gemfibrozil, which correlated with the reduction in plasma triglycerides. Baseline concentrations of Lp(a) showed a wide range in both treatment groups. Median Lp(a) levels increased after simvastatin, but were not affected by gemfibrozil.

CONCLUSION

Both therapies exhibited their specific effects, although none of the drugs alone completely normalized the lipid profiles of these patients with FCH. Therefore, the choice of treatment should be based on the most elevated lipoprotein fraction, and in some cases a combination of the two drugs may be indicated.

Expression of a novel human apolipoprotein (apoC-IV) causes hypertriglyceridemia in transgenic mice

The human apolipoprotein (apo) C-IV gene has been recently identified: it is closely linked to the promoter region of the apoC-II gene (Allan, C.M., D. Walker, J. Segrest, and J. M. Taylor. 1995. Genomics. 28: 291-300). To determine the effect of apoC-IV gene expression on lipoprotein metabolism, transgenic mice were generated using a human apoC-IV cDNA construct. Human apoC-IV was found associated with plasma lipoproteins (d < 1.21 g/ml), mainly in very low density lipoproteins (VLDL), and higher molecular mass isoforms were present, due to N-linked glycosylation and variable sialylation of apoC-IV. Human apoC-IV transgenic mice were hypertriglyceridemic compared to nontransgenic controls; the accumulated plasma triglycerides were present mainly in VLDL. There was little change in plasma cholesterol levels, although apoC-IV expression redistributed cholesterol to VLDL and larger particles in low density lipoprotein/large high density lipoprotein fractions. By immunoblot analysis, apoC-IV was not detected in normal adult human plasma or isolated plasma lipoproteins, a finding consistent with our previous observation of very low levels of human apoC-IV mRNA in human liver. However, our analysis of transgenic mice provides unequivocal evidence that human apoC-IV is a lipid-binding protein belonging to the apolipoprotein family and that it has the potential to alter lipoprotein metabolism.

Evaluation of double filtration plasmapheresis, thermofiltration, and low-density lipoprotein adsorptive methods by crossover test in the treatment of familial hypercholesterolemia patients

A comparative assessment has been made regarding efficacy and safety of the double filtration plasmapheresis (DFPP), thermofiltration (TFPP), and low-density lipoprotein (LDL) adsorptive (PA) methods by making a crossover test on heterozygous familial hypercholesterolemia patients. Treatments by DFPP, TFPP (secondary membrane Evalux 5A), and PA (Liposorber LA-40) were carried out 5 times each, with a 2-week interval, in 5 patients with heterozygous familial hypercholesterolemia. The same plasma separator (Plasmacure PS-60, polysulfone) was used in all cases, and the volume of plasma processed was set at 4 L. High removal rates were obtained of total cholesterol, LDL cholesterol, triglycerides TG, and apolipoprotein B (apoB) by all three methods, and no differences were observed. Lipoprotein (a), apoA-2, apoC-3, fibrinogen, and immunoglobulin M (IgM) showed significantly high removal rates by the DFPP and TFPP methods compared with the PA method. The sieving coefficient of albumin and high-density lipoprotein (HDL) cholesterol at 2 and 4 L of plasma processed exhibited high permeabilities using all three methods. Supplementing albumin was not necessary. An increase of the transmembrane pressure was observed in 1 case treated by DFPP but was not observed when using the TFPP or PA method. No changes were observed in serum interleukin 1beta (IL-1beta) or tumor necrosis factor-alpha (TNF-alpha) before and after treatment by any of the three methods. No remarkable side effects were observed using either the DFPP or TFPP method. The DFPP and TFPP methods showed efficacy and safety that was not inferior to the PA method in conventional LDL apheresis, and the dead-end method of the filter operation without the discarding of plasma was shown to be possible.

Apolipoproteins C-III and E in apoB- and non-apoB-containing lipoproteins in two populations at contrasting risk for myocardial infarction: the ECTIM study. Etude Cas Témoins sur 'Infarctus du Myocarde

Apolipoprotein (apo) C-III and apoE are components of two major classes of plasma lipoproteins, i.e., apoB- and non-apoB-containing lipoproteins. To analyze the relationship between the distribution of apoC-III and apoE among lipoproteins and coronary heart disease, we compared the distribution of these two apolipoproteins in survivors of myocardial infarction (MI) and control subjects, within and between populations at contrasting risk for MI. ApoC-III and apoE concentrations were determined in plasma devoid of apoB-containing lipoproteins by immunoprecipitation using a specific anti-apoB antiserum. These assays referred to apoC-III-Lp non-B and apoE-Lp non-B, respectively. By examining the difference with total plasma apoC-III and apoE levels, we calculated apoC-III and apoE in apoB-containing lipoproteins (apoCIII-LpB and apoE-LpB, respectively). These determinations were performed in control subjects and in survivors of MI, all males aged 25 to 64 years. They were recruited in Northern Ireland and France, countries characterized by a large difference in the incidence of coronary heart disease. In univariate analysis, apoCIII-LpB appeared significantly higher and the apoC-III ratio (apoC-III-Lp non-B/apoC-III-LpB) significantly lower in MI survivors than in control subjects in both countries. ApoE-LpB was higher in MI survivors than in control subjects in Northern Ireland but not in France. The two French and Irish control populations differed for apoC-ILL-Lp non-B, apoC-III ratio, and apoE ratio, which were higher in France than in Northern Ireland, and for apoC-III-LpB, apoE, and apoE-LpB, which were lower. Multivariate analysis showed that no parameter involving apoC-III and apoE was more discriminatory than HDL-cholesterol, cholesterol, and triglycerides or apoA-I, apoB, and triglycerides between controls and MI subjects. In contrast, the apoC-III ratio was a better discriminatory parameter between the two control populations than the listed parameters. The differences between the two control populations are of particular interest because they are not biased by the presence of disease or the large difference of the incidence in coronary heart disease between the two countries. It is suggested that the distribution of apoC-III among lipoproteins may play a role in the different susceptibility of the two populations to the atherogenic process.