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Background: Most primary severe hypertriglyceridemias (HTGs) are diagnosed in adults, but their molecular foundations have not been completely elucidated., Objective: We aimed to identify rare dysfunctional mutations in genes encoding regulators of lipoprotein lipase (LPL) function in patients with familial and non-familial primary HTG., Methods: We sequenced promoters, exons, and exon-intron boundaries of LPL, APOA5, LMF1, and GPIHBP1 in 118 patients with severe primary HTG (triglycerides >500 mg/dL) and 53 normolipidemic controls. Variant functionality was analyzed using predictive software and functional assays for mutations in regulatory regions., Results: We identified 29 rare variants, 10 of which had not been previously described: c.(-16A>G), c.(1018+2G>A), and p.(His80Arg) in LPL; p.(Arg143Alafs*57) in APOA5; p.(Val140Ile), p.(Leu235Ile), p.(Lys520*), and p.(Leu552Arg) in LMF1; and c.(-83G>A) and c.(-192A>G) in GPIHBP1. The c.(1018+2G>A) variant led to deletion of exon 6 in LPL cDNA, whereas the c.(-16A>G) analysis showed differences in the affinity for nuclear proteins. Overall, 20 (17.0%) of the patients carried at least one allele with a rare pathogenic variant in LPL, APOA5, LMF1, or GPIHBP1. The presence of a rare pathogenic variant was not associated with lipid values, family history of HTG, clinical diagnosis, or previous pancreatitis., Conclusions: Less than one in five subjects with triglycerides >500 mg/dL and no major secondary cause for HTG may carry a rare pathogenic mutation in LPL, APOA5, LMF1, or GPIHBP1. The presence of a rare pathogenic variant is not associated with a differential phenotype., (Copyright © 2016 National Lipid Association. Published by Elsevier Inc. All rights reserved.)

Familial hypertriglyceridemia is a rare autosomal recessive inborn error of metabolism. Mutation within the LPL gene constitutes the first cause of monogenic etiology. Lipoprotein lipase (LPL) is the key enzyme in triglyceride-rich lipoproteins catabolism. Familial LPL deficiency is expressed by eruptive xanthomatosis and acute pancreatitis. We report a Moroccan case with a monstrous hypertriglyceridemia caused by LPL gene mutation. We discuss pathophysiology aspects according to available investigations data and the relevance of familial screening. The proband is a 19-year-old woman originating from the village of Taourirt (South of Morocco). She was admitted in emergency for diabetic ketoacidosis. Clinical investigations and routine laboratory tests were performed upon admission. Then lipoprotein electrophoresis and sequencing of the LPL gene were practiced. A monstrous hypertriglyceridemia up to 199 mmol/L was found. Lipoprotein electrophoresis has objectified profound disturbances on chylomicrons, VLDL and IDL. The sequencing detected a missense mutation p.S286R at homozygous state in a consanguinity context. Discovery of this LPL gene mutation is the first indigenous and documented case, never related in any other ethnic group. It constitutes a novel proof of a founder effect in the south Moroccan population. Prevalence studies with familial screening should be done for preventative action which is the only acceptable way to limit the cardiovascular and pancreatitis risks in this population where inbreeding is a general rule.

Significant resources have been invested in sequencing studies to investigate the role of rare variants in complex disease etiology. However, the diagnostic interpretation of individual rare variants remains a major challenge, and may require accurate variant functional classification and the collection of large numbers of variant carriers. Utilizing sequence data from 458 individuals with hypertriglyceridemia and 333 controls with normal plasma triglyceride levels, we investigated these issues using GCKR, encoding glucokinase regulatory protein. Eighteen rare non-synonymous GCKR variants identified in these 791 individuals were comprehensively characterized by a range of biochemical and cell biological assays, including a novel high-throughput-screening-based approach capable of measuring all variant proteins simultaneously. Functionally deleterious variants were collectively associated with hypertriglyceridemia, but a range of in silico prediction algorithms showed little consistency between algorithms and poor agreement with functional data. We extended our study by obtaining sequence data on family members; however, functional variants did not co-segregate with triglyceride levels. Therefore, despite evidence for their collective functional and clinical relevance, our results emphasize the low predictive value of rare GCKR variants in individuals and the complex heritability of lipid traits., (© The Author 2014. Published by Oxford University Press.)

Familial severe hypertriglyceridemia (levels greater than 1000 mg/dL) is a known cause of acute pancreatitis. Pregnancy can dysregulate controlled lipid levels in women with familial hypertriglyceridemia and lead to acute pancreatitis and significant morbidity in both mother and fetus. We report a case of hypertriglyceridemia-induced pancreatitis during pregnancy that was successfully treated using therapeutic plasma exchange, resulting in delivery of a healthy preterm infant. Therapeutic plasma exchange is an effective approach to treat gestational hypertriglyceridemia-induced pancreatitis. Other treatment options include combined heparin and insulin infusion. Moreover, particular caution should be applied when interpreting the results of prothrombin time in the setting of severe hypertriglyceridemia as false elevation with testing methods could happen.

Introduction: Plasma triglycerides (TG) and HDL-C are inversely related in Metabolic Syndrome (MetS), due to exchange of VLDL-TG for HDL-cholesteryl esters catalyzed by cholesteryl ester transfer protein (CETP). We investigated the relationship of TG to HDL-C in highly-active antiretroviral drug (HAART)-treated HIV patients., Methods: Fasting plasma TG and HDL-C levels were compared in 179 hypertriglyceridemic HIV/HAART patients and 71 HIV-negative persons (31 normotriglyceridemic (NL) and 40 hypertriglyceridemic due to type IV hyperlipidemia (HTG)). CETP mass and activity were compared in 19 NL and 87 HIV/HAART subjects., Results: Among the three groups, a plot of HDL-C vs. TG gave similar slopes but significantly different y-intercepts (9.24±0.45, 8.16±0.54, 6.70±0.65, sqrt(HDL-C) for NL, HIV and HTG respectively; P<0.001); this difference persisted after adjusting HDL-C for TG, age, BMI, gender, glucose, CD4 count, viral load and HAART strata (7.18±0.20, 6.20±0.05 and 4.55±0.15 sqrt(HDL-C) for NL, HIV and HTG, respectively, P<0.001). CETP activity was not different between NL and HIV, but CETP mass was significantly higher in HIV (1.47±0.53 compared to 0.93±0.27μg/mL, P<0.0001), hence CETP specific activity was lower in HIV (22.67±13.46 compared to 28.46±8.24nmol/μg/h, P=0.001)., Conclusions: Dyslipidemic HIV/HAART patients have a distinctive HDL-C plasma concentration adjusted for TG. The weak inverse relationship between HDL-C and TG is not explained by altered total CETP activity; it could result from a non-CETP-dependent mechanism or a decrease in CETP function due to inhibitors of CETP activity in HIV patients' plasma., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: Earlier studies have suggested that a common genetic architecture underlies the clinically heterogeneous polygenic Fredrickson hyperlipoproteinemia (HLP) phenotypes defined by hypertriglyceridemia (HTG). Here, we comprehensively analyzed 504 HLP-HTG patients and 1213 normotriglyceridemic controls and confirmed that a spectrum of common and rare lipid-associated variants underlies this heterogeneity., Methods and Results: First, we demonstrated that genetic determinants of plasma lipids and lipoproteins, including common variants associated with plasma triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) from the Global Lipids Genetics Consortium were associated with multiple HLP-HTG phenotypes. Second, we demonstrated that weighted risk scores composed of common TG-associated variants were distinctly increased across all HLP-HTG phenotypes compared with controls; weighted HDL-C and LDL-C risk scores were also increased, although to a less pronounced degree with some HLP-HTG phenotypes. Interestingly, decomposition of HDL-C and LDL-C risk scores revealed that pleiotropic variants (those jointly associated with TG) accounted for the greatest difference in HDL-C and LDL-C risk scores. The APOE E2/E2 genotype was significantly overrepresented in HLP type 3 versus other phenotypes. Finally, rare variants in 4 genes accumulated equally across HLP-HTG phenotypes., Conclusions: HTG susceptibility and phenotypic heterogeneity are both influenced by accumulation of common and rare TG-associated variants.

GPIHBP1, a glycosylphosphatidylinositol-anchored protein of capillary endothelial cells, shuttles lipoprotein lipase (LPL) from subendothelial spaces to the capillary lumen. An absence of GPIHBP1 prevents the entry of LPL into capillaries, blocking LPL-mediated triglyceride hydrolysis and leading to markedly elevated triglyceride levels in the plasma (i.e., chylomicronemia). Earlier studies have established that chylomicronemia can be caused by LPL mutations that interfere with catalytic activity. We hypothesized that some cases of chylomicronemia might be caused by LPL mutations that interfere with LPL's ability to bind to GPIHBP1. Any such mutation would provide insights into LPL sequences required for GPIHBP1 binding. Here, we report that two LPL missense mutations initially identified in patients with chylomicronemia, C418Y and E421K, abolish LPL's ability to bind to GPIHBP1 without interfering with LPL catalytic activity or binding to heparin. Both mutations abolish LPL transport across endothelial cells by GPIHBP1. These findings suggest that sequences downstream from LPL's principal heparin-binding domain (amino acids 403-407) are important for GPIHBP1 binding. In support of this idea, a chicken LPL (cLPL)-specific monoclonal antibody, xCAL 1-11 (epitope, cLPL amino acids 416-435), blocks cLPL binding to GPIHBP1 but not to heparin. Also, changing cLPL residues 421 to 425, 426 to 430, and 431 to 435 to alanine blocks cLPL binding to GPIHBP1 without inhibiting catalytic activity. Together, these data define a mechanism by which LPL mutations could elicit disease and provide insights into LPL sequences required for binding to GPIHBP1.

Iron deposits are associated with lipid phenotype in familial hypertriglyceridemias, mainly familial combined hyperlipidemia (FCH) and familial hypertriglyceridemia (FHTG). In turn, diet plays an important role in hypertriglyceridemias although it is not known if dietary patterns are associated with iron concentration in these disorders. The objective was to determine the relationship between diet and iron deposits, measured through serum ferritin concentration, in patients with FCH and FHTG. The study was composed of 140 patients, 107 with FCH and 33 with FHTG. Subjects completed a validated 137-item food frequency questionnaire. Dividing subjects by ferritin tertiles adjusted by sex, there were no significant differences in dietary patterns except in dairy products consumption which was lower in the highest ferritin tertile. Subjects were also divided by triglycerides tertiles adjusted by sex. Those subjects in the highest tertile had lower HDL cholesterol and higher ferritin concentrations. Regarding to dietary parameters, there were significant differences in marine omega three fatty acids and vegetables presenting higher and lower consumption, respectively, those patients in the highest tertile of triglycerides. Moreover, there was not a significant correlation between dietary iron intake and any parameter, both biochemical and dietary, including ferritin concentrations. In conclusion, in patients with primary hypertriglyceridemia, triglycerides are associated with ferritin concentrations but dietary patterns are not related to iron deposits. Our results highly support the concept that the genetic mechanisms driven to hypertriglyceridemia also favor iron overload.

Familial combined hyperlipidemia (FCH) and familial hypertriglyceridemia (FHTG) share pathogenic mechanisms and a high interaction with components of the metabolic syndrome. The metabolic syndrome associates increased serum ferritin concentration and high cardiovascular risk. The objective was to describe the frequency of iron overload and the relationship between serum ferritin and the phenotype in patients with FCH and FHTG. The study was composed of 211 consecutive unrelated patients aged at least 18 years with primary hypertriglyceridemia, 149 with FCH, and 62 with FHTG. The prevalence of the metabolic syndrome and hyperferritinemia was very high in both hypertriglyceridemic groups (51.7% and 20.1% in FCH and 62.9% and 16.1% in FHTG, respectively), without significant statistical differences between them. Serum ferritin concentration did not show any significant association with the number of metabolic syndrome criteria. Subjects in the highest tertile of ferritin concentration (ferritin >200 mug/L) presented higher concentrations of triglycerides and liver enzymes than subjects in the first tertile of ferritin concentration (ferritin <90 mug/L). The highest positive correlation coefficient for triglycerides was found with ferritin in FCH and in FHTG subjects (R = 0.317 [P < .001] when combined). Ferritin was also the covariate that showed the highest independent association with triglycerides in FCH and FHTG. In contrast, ferritin was not associated with carotid intima-media thickness. In summary, serum ferritin is commonly increased in FCH and in FHTG, it is not related with the presence of metabolic syndrome, and it is highly correlated with liver enzymes., (Copyright 2010 Elsevier Inc. All rights reserved.)

The increased risk of cardiovascular mortality in patients with inflammatory joint disease indicates a need for routine investigations to detect conventional cardiovascular risk factors. These investigations may provide the classification of the disease. We report a case of oligoarticular arthritis with type IV hyperlipoproteinemia, a condition of which only 15 cases are described in the literature. The patient had oligoarthritis, laboratory signs of severe inflammation, and type IV hyperlipoproteinemia (triglycerides, 24.6 mmol/L; and total cholesterol, 10.7 mmol/L). The clinical and laboratory test abnormalities resolved under fenofibrate therapy.

Objectives: Hypertriglyceridaemia has been recognized as an independent risk factor for the development of coronary heart disease. Apolipoprotein A-IV (apo A-IV) plays an important role in the metabolism of TG-rich lipoproteins and HDL. However, the role of the polymorphism of the apo A-IV gene in hyperlipidaemia remains to be fully determined. The impact of the genetic variant in the apolipoprotein A-IV gene on lipid risk factor profiles for coronary heart disease was examined in Chinese patients with type-IV hyperlipoproteinaemia (HTG) and in healthy control individuals., Methods: We genotyped five polymorphisms in the apo A-IV gene (codon 9, codon 347, codon 360, 3'end VNTR and Msp I sites) by direct sequencing or RFLP analysis in a Chinese population., Results: The genotype frequencies in our results were significantly different from those reported in Caucasians. The polymorphic sites of codon 347 and codon 360, that have been widely studied in Western populations, were not observed in our population. The frequency of the G allele at codon 9 in HTG subjects was higher than that in healthy controls (P < 0.05). Serum apolipoprotein A-I (apo A-I), triglyceride (TG) and low-density lipoprotein cholesterol (LDLC) levels were affected by genotypes of codon 9, Msp I and VNTR polymorphisms, respectively, with some sex-specific effects in the control or HTG group., Conclusion: These results suggest that codon 9, Msp I and VNTR polymorphisms in the apo A-IV gene are associated with type-IV hyperlipoproteinaemia in a Chinese population.

Increased low-density lipoprotein (LDL) and decreased high-density lipoprotein cholesterol (HDL-C) predict premature coronary artery disease, as do elevated levels of apolipoprotein B or reduced levels of apolipoprotein AI. Probands were studied of families with common genetic forms of dyslipidaemia to determine if apo B or apo AI define genetic groups and if apo B or apo AI levels relate to premature coronary artery disease risk. Elevated apo B was characteristic of familial hypercholesterolaemia, familial combined hyperlipidaemia (FCHL), and was seen in individuals with elevated Lp(a). Normal apo B levels were seen in familial hypertriglyceridaemia and in 'coronary artery disease with low-HDL cholesterol'. Apo AI levels tended to be low in FCHL and were decreased in 'coronary disease with low-HDL cholesterol'. In familial hypertriglyceraemia, even though HDL-C levels were low, normal apo AI and apo B levels were seen in the absence of premature coronary artery disease. Therefore, in genetic dyslipidaemias elevated apo B levels and reduced apo AI levels (or increased apo B/AI ratio) differ and predict premature coronary artery disease.

The concentration of plasma homocysteine was diminished by the oral use of vitamins B6 (300 mg/day), B12 (250 microg/day) and folic acid (10 mg/day), and the effect was studied in the lipids of patient with hiperlipoproteinemia secondary type IV, during 120 days, in 30 patients, 45 to 70 years old, with myocardial heart attack. They were divided in group A (n=15) without treatment with Lovastatin and group B (n=15) with Lovastatin. Basal homocysteine concentration was 17.4 +/- 1.0 micromol/L and 16.7 +/- 1.0 micromol/L for the groups A and B respectively, diminishing 24% at the end of the experimental time, in both groups. Total cholesterol decreased below 220 mg/dl, while the triglycerides diminished 25.4 mg/dl and 27.0 mg/dl in groups A and B respectively, by each micromol/L of homocysteine catabolissed. Low density lipoproteins (LDL) and very low density (VLDL) diminished significantly (p < 0.005), while the high-density (HDL) increased 1.0 mg/dl in group A and 1.15 mg/dl in group B, for each micromol/L of homocysteine metabolized, lowering the coronary risk factor in 28.5% group A and 35.9% group B. We concluded that these vitamins decreased plasma homocysteine concentration, promoting the lowering of lipids and lipoprotein concentratation in this type of patients; while Lovastatin doesn't reduce homocysteine, but it had a synergic effect with the vitamins, dicreasing the lipid concentration, in group B.

Background: The potency and usefulness of capillary isotachophoresis (cITP) for assessing whole-serum lipoprotein profiles and quantifying electronegative low-density lipoprotein (LDL) has been previously reported., Methods and Results: A new cITP method to measure electronegative LDL in the small dense LDL fraction has been established. Both electronegative LDL and electronegative LDL in the small dense LDL fraction decreased after treatment with fenofibrate., Conclusions: This method appears to be useful for analyzing a marker of coronary heart disease risk and may be suitable for evaluating the effects of hypolipidemic agents.

The cases of hyperlipoproteinemic secondary type IV are manifested by elevation of triglycerides, with normal or high cholesterol and lightly high homocysteine. The effect of vitamins B12, B6 and folic acid, on homocysteine and lipids, in 24 male patients, 35-68 years, with hiperlipoproteinemia secondary type IV with myocardial isquemic, and without previous treatment of hipolipemiant, was investigated. The patients were supplemented with therapeutic doses tablets of vitamin B12, 500 (microg/day); B6, (600 mg/day) and folic acid (20 mg/ day), during 120 days. Homocysteine, triglycerides, total and fractional cholesterol, at (basal), 30, 60, 90 and 120 days, were determined. Descriptive statistical analyses were applied, coefficient of correlation of Pearson and proves of "t", with a p < 0.005; the data were processed by statistical program SPSS version 8.0. The results showed a decrease in the levels of homocysteine from basal 17.1 +/- 0.7 micromol/L to 13.18 +/- 0.83 micromol/L, at the end of experimental period. The triglycerides (TG), total cholesterol (TC), low density lipoprotein (LDL), very low density lipoprotein (VLDL) showed a reduction of (21.8 mg/dl; 8.5 mg/dl; 5.87 mg/dl; respectively) for every pmol/L of reduced homocysteine, with (p < 0.001) for triglycerides. High density lipoprotein (HDL) increased 1.1 mg/dl and coronary risk descent in 24%. We concluded that therapeutic doses of vitamins B12, B6 and folic acid, may is effective in decreased plasmatic homocysteine levels and lipids, mainly triglycerides, with a reduction of coronary risk, to these type of patients, with not collateral effects of neuropathy

Objective: The aim of the study was to investigate apolipoprotein(apo) E polymorphism and its relationship with serum lipids and apolipoprotein, serum high density lipoprotein(HDL) subclasses in patients with type IV hyperlipidemia., Methods: apoE genotype was assayed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The subclasses of serum HDL in 103 patients with type IV hyperlipidemia and 146 normolipidemic subjects were determined by two-dimensional gel electrophoresis in conjunction with immunodetection method., Results: The apoE3/3 genotype frequency and allele epsilon 3 frequency were both the highest in the frequency distribution profiles of the type IV hyperlipidemia group and the control group. In type IV hyperlipidemia group, the genotype of apoE2 had higher serum HDL-C,apoE, HDL(2a) apoE/apoCIII ratio but lower TG/HDL-C,apoCIII, HDL(3c) levels when compared with the genotype of apoE(3) (P<0.05). In control group, the genotype of apoE(2) had higher serum TG, apoE levels and apoE/aopCIII ratio but lower HDL (3a) level when compared with the genotype of apoE(3) (P<0.05)., Conclusion: An association of allele epsilon 2 of apoE gene with the maturation of HDL in type IV hyperlipidemia was noted in the study.

Objective: Mutations in LPL or APOC2 genes are recognized causes of inherited forms of severe hypertriglyceridemia. However, some hypertrigliceridemic patients do not have mutations in either of these genes. Because inactivation or hyperexpression of APOA5 gene, encoding apolipoprotein A-V (apoA-V), causes a marked increase or decrease of plasma triglycerides in mice, and because some common polymorphisms of this gene affect plasma triglycerides in humans, we have hypothesized that loss of function mutations in APOA5 gene might cause hypertriglyceridemia., Methods and Results: We sequenced APOA5 gene in 10 hypertriglyceridemic patients in whom mutations in LPL and APOC2 genes had been excluded. One of them was found to be homozygous for a mutation in APOA5 gene (c.433 C>T, Q145X), predicted to generate a truncated apoA-V devoid of key functional domains. The plasma of this patient was found to activate LPL in vitro less efficiently than control plasma, thus suggesting that apoA-V might be an activator of LPL. Ten carriers of Q145X mutation were found in the patient's family; 5 of them had mild hypertriglyceridemia., Conclusions: As predicted from animal studies, apoA-V deficiency is associated with severe hypertriglyceridemia in humans. This observation suggests that apoA-V regulates the secretion and/or catabolism of triglyceride-rich lipoproteins. Mutations in APOA5 gene might be the cause of severe hypertriglyceridemia in subjects in whom mutations in LPL or APOC2 genes have been excluded. We detected a nonsense mutation in APOA5 gene (Q145X) in a boy with hyperchylomicronemia syndrome. This is the first observation of a complete apoA-V deficiency in humans.

Unlabelled: A 32-day-old girl with massive hypertriglyceridaemia and clinical signs of chylomicronaemia syndrome is described. Genetic study of the patient revealed compound heterozygosity for a common lipoprotein lipase gene mutation (G188E) and a novel missense mutation (M301R), consistent with reduced post-heparin plasma lipoprotein lipase immunoreactive mass observed., Conclusion: to the best of our knowledge, this is the first description of a patient with a M301R mutation in the lipoprotein lipase gene. In addition, dietary therapy with medium-chain triglycerides was successful supporting the effectiveness of this therapeutic approach in familial chylomicronaemia syndrome., (Copyright 2004 Springer-Verlag)

Objective: To investigate the effect of complement deficiency on atherogenesis and lipidemia, we used mice deficient in the third complement component (C3-/-) or factor B (FB-/-)., Methods and Results: Complement-deficient mice were crossed with mice deficient in both apolipoprotein E and the low-density lipoprotein receptor (Apoe-/- LDLR-/-). The percent lesion area in the aorta at 16 weeks, determined by en face analysis, was 84% higher in C3-/- mice than in controls (11.8%+/-0.4% versus 6.4%+/-0.8%, mean+/-SEM, P<0.00005). The C3-/- mice also had 58% higher serum triglyceride levels (P<0.05) and a more proatherogenic lipoprotein profile, with significantly more low-density lipoprotein cholesterol and very-low-density lipoprotein triglycerides than control mice. The C3-/- mice weighed 13% less (P<0.01) and had a lower body fat content (3.5%+/-1.0% versus 13.1%+/-3.0%, P<0.01). There were no differences between FB-/- mice and controls., Conclusions: Complement activation by the classical or lectin pathway exerts atheroprotective effects, possibly through the regulation of lipid metabolism.

Objective: The present study addresses the presence of distinct metabolic phenotypes in familial combined hyperlipidemia (FCHL) in relation to small dense low-density lipoprotein (sd LDL) and very low-density lipoprotein (VLDL) subclasses., Methods and Results: Hyperlipidemic FCHL relatives (n=72) were analyzed for LDL size by gradient gel electrophoresis. Pattern B LDL (sd LDL, particle size <258 A) and pattern A LDL (buoyant LDL, particle size > or =258 A) were defined. Analyses showed bimodal distribution of LDL size associated with distinct phenotypes. Subjects with predominantly large, buoyant LDL showed a hypercholesterolemic phenotype and the highest apo B levels. Subjects with predominantly sd LDL showed a hypertriglyceridemic, low high-density lipoprotein (HDL) cholesterol phenotype, with moderately elevated apoB, total cholesterol level, and LDL cholesterol level. Subjects with both buoyant LDL and sd LDL (pattern AB, n=7) showed an intermediate phenotype, with high normal plasma triglycerides. VLDL subfraction analysis showed that the sd LDL phenotype was associated with a 10-times higher number of VLDL1 particles of relatively lower apo AI and apo E content, as well as smaller VLDL2 particles, in combination with increased plasma insulin concentration in comparison to pattern A., Conclusions: The present observations underscore the importance of the VLDL triglyceride metabolic pathway in FCHL as an important determinant of the phenotypic heterogeneity of the disorder.

We measured lipid peroxidation and antioxidant enzymes in erythrocytes of types IIb and IV hyperlipoproteinemic (HLP) human subjects in comparison with age-matched controls. Thiobarbituric acid-reactive substances (TBARS), a measure of lipid peroxidation, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), glutathione reductase (GR), and catalase (CAT) were determined in erythrocytes. We also measured lipid parameters including triglycerides (TG), total cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), apolipoprotein AI, and apolipoprotein B, and antioxidant related substances such as serum albumin, free iron, ferritin, ceruloplasmin. Thirty-two subjects (females 15, males 17) with type IIb (the mean age 45.6+/-8 [S.E.]), 34 with type IV (females 16, males 18) (the mean age 47+/-10 [S.E.]), and 36 normolipidemic voluntary subjects (females 18, males 18) (the mean age 46+/-8 [S.E.]) were included in the study. Erythrocytes were prepared by classical washing method (0.9% NaCl) from venous blood samples. The mean TBARS levels in plasma and erythrocyte suspensions were found to be significantly higher in both types IIb and IV hyperlipoproteinemics. Erythrocyte SOD and GSH-Px activities were decreased but erythrocyte GR activity did not change in both types IIb and IV hyperlipoproteinemics. Erythrocyte CAT activity was decreased in type IIb, but it was increased in type IV hyperlipoproteinemics. Erythrocyte SOD activity was negatively correlated with plasma TG level, whereas plasma free iron was positively correlated with plasma TBARS level in type IV hyperlipoproteinemics. These results suggest the presence of oxidative injury in patients with type IIb or IV hyperlipoproteinemia, and that the responses of erythrocyte antioxidant enzymes to oxidant stress are different in these conditions.

Laboratory-based coronary heart disease risk assessment classically involves measurement of lipids and lipoproteins. In this review, information is provided on the methods commonly used in laboratories for the diagnosis of hyperlipidemia, including aspects of precision and accuracy. The latter, when fulfilled, allows the use of uniform reference values. Special attention is paid to the risk estimation using apolipoprotein B and lipoprotein(a) measurement. The overall aim of this review is to simplify the laboratory-based risk estimation for coronary heart disease and to provide help in interpreting the results for effective prevention and treatment of this complex disease.

Small, dense LDLs and hypertriglyceridemia, two highly correlated and genetically influenced risk factors, are known to predict for risk of coronary heart disease. The objective of this study was to perform a whole-genome scan for linkage to LDL size and triglyceride (TG) levels in 26 kindreds with familial hypertriglyceridemia (FHTG). LDL size was estimated using gradient gel electrophoresis, and genotyping was performed for 355 autosomal markers with an average heterozygosity of 76% and an average spacing of 10.2 centimorgans (cMs). Using variance components linkage analysis, one possible linkage was found for LDL size [logarithm of odds (LOD) = 2.1] on chromosome 6, peak at 140 cM distal to marker F13A1 (closest marker D6S2436). With adjustment for TG and/or HDL cholesterol, the LOD scores were reduced, but remained in exactly the same location. For TG, LOD scores of 2.56 and 2.44 were observed at two locations on chromosome 15, with peaks at 29 and 61 cM distal to marker D15S822 (closest markers D15S643 and D15S211, respectively). These peaks were retained with adjustment for LDL size and/or HDL cholesterol. These findings, if confirmed, suggest that LDL particle size and plasma TG levels could be caused by two different genetic loci in FHTG.

Background: We previously reported that the tamoxifen treatment caused a decrease in lipoprotein lipase (LPL) activity and an increase in LPL mass. We hypothesized that tamoxifen may increase the quantity of inactive LPL., Methods: Lipoprotein lipase in post-heparin plasma usually exists in both monomeric and dimeric forms, which may be separated on a heparin-Sepharose column with different salt concentrations. Lipoprotein lipase in post-heparin plasma from postmenopausal patients with hypertriglyceridemia treated with or without tamoxifen was incubated with or without 4-hydroxy-tamoxifen (4-OHT), the monomers and dimers were separated on a heparin-Sepharose column and their masses were measured., Results: The masses of total LPL and dimeric LPL of tamoxifen-treated patients were significantly higher than those of control subjects. Monomeric LPL of tamoxifen-treated patients passed more slowly through the heparin-Sepharose column compared with that of control subjects. The ratio of monomeric LPL to dimeric LPL of tamoxifen-treated patients was 0.61, significantly lower than that of control subjects, which was 1.45 (p<0.01). In addition, monomeric LPL incubated with 4-OHT passed more slowly through the heparin-Sepharose column compared with that incubated without 4-OHT., Conclusion: Tamoxifen influences the affinity of LPL for heparin.

The unique inborn hypertriglyceridemia seen in FLS (fatty liver Shionogi) mice was relieved by the administration of purified apolipoprotein (apo) C-II. Lipoprotein lipase (LPL) and its cofactor, apoC-II, play a pivotal role in VLDL metabolism. Therefore, we investigated the genetic background involved in this hypertriglyceridemia. Plasma levels of TG and total cholesterol as well as LPL activity were measured in male FLS mice and C57/BL6J mice. Agarose gel electrophoresis and fast protein liquid chromatography were used to analyze the lipoprotein profile. A cross experiment was done to determine the genetic background of hypertriglyceridemia observed in FLS mice. cDNA sequences of apoC-II and apoC-III of FLS mice were determined. Prealpha-lipoprotein was the predominant lipoprotein class in FLS mouse plasma. LPL activity remained in the range observed in C57/BL6J mice, and purified apoC-II transiently relieved FLS mice from hypertriglyceridemia. Prealpha-lipoproteinemia was inherited in an autosomal recessive manner. ApoC-III appeared to be a causal factor for this unique hypertriglyceridemia. Microsatellite analysis, however, revealed that the responsible chromosome was not 7; rather, apoC-III mapped onto chromosome 9. Therefore, we suggest apoC-III as a candidate causative factor for the hypertriglyceridemia observed in FLS mice because an excessive amount of apoC-III attenuates LPL activity in vivo and in vitro.

Background: We assessed severe hypertriglyceridemia, hypertriglyceridemic acute pancreatitis, and failure of triglyceride-lowering therapy when estrogens were given to 56 women with and without familial hypertriglyceridemia. The 56 women had been consecutively referred to our center over a 3-year period because of triglycerides >400 mg/dl despite diet-drug treatment and/or a history of hypertriglyceridemic acute pancreatitis (AP). Of the 56 women, 17 had received estrogen replacement therapy (ERT), hormone replacement (HRT, n=6), or selective estrogen receptor modulators (SERM, n=1)., Methods: After study at entry, in 56 women (median age, 52 years), 36 with familial hypertriglyceridemia, to lower triglycerides, estrogens and SERMs (hormone treatment, HT) were stopped; a very low fat diet (<15% of calories), gemfibrozil (1.2-1.5 mg/day), and omega-3-fatty acid (4-12 g/day) were started, with restudy 2-4 weeks later., Results: Of the 56 women, 24 (43%) were taking HT at entry, with median fasting triglycerides 1270 mg/dl in the HT group and 1087 mg/dl in the no-HT group. Seventeen women (30%) had a history of AP, nine of whom (53%) were/had been on HT at the development of AP. Significant positive correlates of triglycerides at entry in a stepwise regression model were hemoglobin A(1C) (partial r(2)=10.7%, p<0.05) and an interaction between estrogen use and familial hypertriglyceridemia (partial r(2)=15%, p=0.017). After 2-4 weeks on therapy, median triglycerides in the previous-HT group fell from 1270 to 284 mg/dl (p<0.0001) and in the no-HT group from 1087 to 326 mg/dl (p<0.0001)., Conclusions: Before starting HT, to avoid HT induced hypertriglyceridemic AP and exacerbation of overt or covert familial hypertriglyceridemia, triglycerides must be measured. HT is contraindicated in women with preexisting hypertriglyceridemia (triglycerides> or =500 mg/dl). Triglyceride-lowering diets and drugs often fail in the presence of HT and/or poorly controlled diabetes mellitus, but commonly succeed when HT is stopped and diabetes mellitus is tightly controlled.

Case Report: A 24-year-old woman in her 13th gestational was admitted to our department with acute retrosternal and epigastric pain. She had been transferred from the gynecologic department where she was treated for vaginal bleeding because of abortus imminens. A cardiac cause was excluded by ECG and echo. Clinical chemistry and abdominal ultrasound confirmed the diagnosis of acute pancreatitis. The woman was known in our outpatient department for hyperchylomicronemia and had already had an earlier episode of acute pancreatitis under oral contraception years ago. At current admission, triglycerides were 11,500 mg/dl. To reduce plasma triglycerides, selective lipid apheresis was performed. Apheresis was well tolerated, and the patient became free of pain within the first 30 min of treatment. Triglycerides decreased to 6,600 mg/dl at this session. Keeping to a low-fat diet (< 30 g fat per day), the patient remained healthy and completed pregnancy with the delivery of a healthy girl in her 39th week of pregnancy., Conclusion: Selective lipid apheresis is a safe and effective option in the treatment of hyperlipidemic pancreatitis, even in pregnant patients.

Background: The purpose of our study was to assess the effect of hypolipidemiant drugs on serum markers of vascular inflammation (E-Selectin, VCAM-1 and MCP-1) in dyslipidemic men without cardiovascular disease., Material/methods: 84 dyslipidemic men were consecutively recruited from the Lipid Unit of a tertiary hospital. The patients were placed on statins (n=44) or fibrates (n=22), depending on the lipid profile, for 4 months. In the control group (n=18), a hypolipidemiant diet alone was indicated., Results: Baseline levels of VCAM-1 and MCP-1 were not correlated with the lipid profile. By contrast, baseline E-Selectin levels correlated directly with glucose and triglyceride levels, and negatively with HDL-C. In multiple regression analysis, HDL-C and glucose concentrations independently influenced E-selectin levels. After treatment, we observed a significant decrease of E-Selectin levels in patients treated with statins, and the changes in E-Selectin levels were inversely associated with HDL-C variations. We did not observe any changes in VCAM-1 levels after the treatment regime we used. Regarding MCP-1, a significant increase was detected in the patients receiving fibrates. In addition, the percentage increment of MCP-1 was higher in patients treated with gemfibrozil than in patients who received bezafibrate., Conclusions: We observed a reduction in E-Selectin levels after statin therapy. This finding was associated with increased HDL-C. Fibrates, especially gemfibrozil, increased MCP-1 concentrations. This deleterious effect was unrelated to changes in lipid profile, and may help explain why fibrates have less impact than statins in reducing cardiovascular disease.

Background: Hyperlipidaemia associated with antiretroviral treatment has led to concerns for an increased cardiovascular risk in HIV-infected patients., Objective: To assess this cardiovascular risk by comparing the lipoprotein pattern of antiretroviral-treated and untreated HIV-positive patients with patients with familial combined hyperlipidaemia (high cardiovascular risk) or familial hypertriglyceridaemia (low cardiovascular risk)., Methods: Fasting serum samples were drawn from consecutive patients with HIV infection or lipoprotein disorders. Total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides, apolipoprotein A1 and B were determined in serum. Very low density lipoprotein (VLDL) was prepared by ultracentrifugation and analysed for cholesterol, triglycerides and apolipoprotein B., Results: Lipoprotein disorders were found in 114/187 HIV-positive patients (61%). Of these, according to the Fredrickson classification, 10% were type IIa (elevated LDL-cholesterol), 14% type IIb (elevated LDL- and VLDL-cholesterol) and 76% were type IV (elevated VLDL-cholesterol). VLDL composition was analysed in 34 HIV-positive patients with type IV hyperlipidaemia. The ratio of VLDL-triglycerides to VLDL-apolipoprotein B in these patients was 16.2 +/- 6.0. This ratio was not different from 14 patients with famlial hypertriglyceridaemia (16.9 +/- 6.0; = 0.61), but differed substantially from 10 patients with familial combined hyperlipidaemia (6.8 +/- 1.0; < 0.0001)., Conclusions: In HIV-infected patients with high VLDL, large VLDL particles were found with no increase in number. This pattern resembles familial hypertriglyceridaemia. It is different from familial combined hyperlipidaemia, where an increase in number of small-sized VLDL particles occurs. Further research is needed to assess the contribution of VLDL-associated hypercholesterolaemia in those taking antiretroviral drugs to the cardiovascular risk profile of HIV-positive patients.

Background: Most cases of dyslipidemia found in adults are non-familial. However, in children, especially young children, dyslipidemias other than familial hypercholesterolemia (FH) have not yet been characterized., Methods: From April 1990 to March 1999, 56 181 children were screened, and 1380 showed abnormal levels of apolipoprotein B (more than 2.5 standard deviations above the mean). Among these, 1198 were re-examined and further characterized by measuring lipids and apolipoproteins, and by their familial histories., Results: Seventy-seven percent of the children (928 of 1198) recalled were diagnosed as being dyslipidemic. Ninety-one children were FH, 423 were type IIa, 128 were type IIb, 98 were type IV, and 188 were hypoalphalipoproteinemia. The presumed incidence of FH was 0.19%, IIa 0.87%, IIb 0.26%, IV 0.20%, and hypoalphalipoproteinemia 0.39%, taking into account the percentage of subjects who refused recall. At regular follow-ups, in many children with type IIb, the phenotypic expression changes from type IIb to IIa or IV. Thus, lipid and apolipoprotein levels were determined in 77 family members in 34 families of children with type IIb. Forty-five family members were dyslipidemic (type IIa 18, type IIb 11, type IV 16). As a result, 27 children (79%) with type IIb met the criteria for familial combined hyperlipidemia., Conclusions: Children with dyslipidemia had more family or genetic background than adults. Unexpectedly, children with type IIb were mostly familial combined hyperlipidemia. Thus, setting appropriate eating patterns during childhood might be important for normalizing risk factors for atherosclerotic coronary heart disease, especially in children with FH or type IIb.

Adult dyslipidemias may reveal familial and, therefore, offspring dyslipidemias. We evaluated the prevalences of the adult-offspring dyslipidemias in 441 general population families composed of both parents and one 5-year-old child. Family members were classified using the 90th or 10th percentiles for hypercholesterolemia (IIA), hypertriglyceridemia (IV), combined hyperlipidemia (IIB), and low high density lipoprotein cholesterol concentration without hyperlipidemia (hypoHDL). In familial combined hyperlipidemia (FCHL), the IIB-phenotype was in one generation and one of the three hyperlipidemias in the other generation. Finally, the parental dyslipidemia phenotypes and elevated lipids (>80th percentile) that reveal offspring dyslipidemia were selected by stepwise logistic regression. Either the IIA-, IV- or hypoHDL phenotype was found in both generations in 2.8, 2.0 and 1.4% of the families, respectively. FCHL was seen in 1.8% of the families, which confirms the earlier views. The predictive values of the elevated parental cholesterol, type IV or hypoHDL parents to find type IIA, IV and hypoHDL children were low for systematic screening: 16, 13 and 15%, respectively. However, 44% of the children of IIB parents expressed hyperlipidemia (odds ratio 4.7, P=0.006). The IIB phenotype of the parent is a good predictor of the child's hyperlipidemia, and when encountered, it indicates that the lipids of the child should be studied. This would be as important as selective screening of familial hypercholesterolemia.

Aim: To investigate correlations between composition of plasmic lipid fractions in patients with ischemic heart disease (IHD) and those with cerebrovascular insufficiency (CVI) caused by atherosclerosis., Material and Methods: 75 patients were divided into three groups; 26 patients with IHD free of CVI (group 1), 22 patients with CVI free of IHD (group 2), 27 patients with IHD and CVI (group 3). Blood lipids were measured by a standard mesiautomatic method using Technicon-AA-2 unit (USA)., Results: Hyperlipidemia (HLE) type II was most frequent in group 1 while HLE type IV or hypoalphalipoproteinemia without rise in cholesterol or triglycerides--in groups 2 and 3., Conclusion: In IHD without CVI dyslipidemia in most cases was associated with one of the additional risk factors (hypertension, smoking, diabetes mellitus) while in CVI it combined with two or three additional risk factors.

Overexpression of human apolipoprotein A-II (apo A-II) in mice induced postprandial hypertriglyceridemia and marked reduction in plasma HDL concentration and particle size [Boisfer et al. (1999) J. Biol. Chem. 274, 11564-11572]. We presently compared lipoprotein metabolism in three transgenic lines displaying plasma concentrations of human apo A-II ranging from normal to 4 times higher, under ad libitum feeding and after an overnight fast. Fasting dramatically decreased VLDL and lowered circulating human apo A-II in transgenic mice; conversely, plasma HDL levels increased in all genotypes. The apo A-I content of HDL was inversely related to the expression of human apo A-II, probably reflecting displacement of apo A-I by an excess of apo A-II. Thus, the molar ratios of apo A-II/A-I in HDL were significantly higher in fed as compared with fasted animals of the same transgenic line, while endogenous LCAT activity concomitantly decreased. The number and size of HDL particles decreased in direct proportion to the level of human apo A-II expression. Apo A-II was abundantly present in all HDL particles, in contrast to apo A-I mainly present in large ones. Two novel findings were the presence of pre-beta migrating HDL transporting only human apo A-II in the higher-expressing mice and the increase of plasma HDL concentrations by fasting in control and transgenic mice. These findings highlight the reciprocal modifications of VLDL and HDL induced by the feeding-fasting transition and the key role of the molar ratio of apo A-II/A-I as a determinant of HDL particle metabolism and pre-beta HDL formation.

Objective: To develop an assay for high density lipoprotein phospholipids in human serum based on ascorbutate reduction method., Methods: HDLs were separated from apolipoprotein B-containing lipoproteins by precipitation of phosphotungstic acid and magnesium chloride. Phospholipids of HDL were extracted by ethanol/ether, and dried. After the dried phospholipids were digested by sulphuric acid and perchloric acid, the color was developed by adding ammonium molybdate in ascorbutate. The levels of high density lipoprotein phospholipids (HDL-PL) were measured by spectrophotometry at 700 nm., Results: The coefficients of variation (CV) were 3.6% and 3.7% within two batches of assays. Recovery of isolated HDL-PL added to serum ranged from 98% to 107%, averagely 103%. The established assay for human serum HDL-PL was used to measure the serum levels of 30 hypercholesterolemic subjects, 30 hypertriglyceridemic subjects, 30 combined hyperlipidemic subjects, and 30 normolipidemic subjects. The hypertriglyceridemic subjects had lower HDL-PL level than normolipidemic subjects and hypercholesterolemic subjects (The P values are 0.005 and 0.007 respectively)., Conclusion: A simple and specific method for assay of HDL-phos-pholipids in human serum has been developed. The above data collected by the use of this method demonstrate the closer relationship between human HDL-PL metabolism and triglyceride metabolism, suggesting that lower HDL-PL level might serve as an index in the assay for type IV hyperlipidemia.

Objective: To investigate the apoC III gene Sst I polymorphism and its relationship with serum lipids and apolipoproteins (apo) levels in patients with endogenous hypertriglyceridemia in Chinese population., Methods: The genotype and allele frequency of apoC III gene Sst I polymorphism was assayed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Serum lipids were measured by enzymatic kits and apolipoproteins A I, A II, B100, C II, C III and E were measured by RID kits developed by Apolipoprotein Research Unit of WCUMS in 176 HTG patients whose fasting serum TG levels were > or = 2.26 mmol/L and in 199 healthy subjects whose fasting serum TG levels were < 1.82 mmol/L and TC levels < 6.2 mmol/L from a population of Chinese Han nationality in Chengdu area., Results: In both HTG group and control group, S1 allele was the major allele and homozygous S1S1 genotype was the most frequent one. The frequency of S2 allele was significantly higher than that reported in Caucasians (0.289 vs 0.06-0.16, P < 0.05). No differences were found in apoC III gene Sst I polymophism in the HTG group when compared with the control group (0.287 vs 0.289, P > 0.05). The genotype of S2S2 was not associated with higher TG and apolipoproteins levels when compared with the genotypes of S1S1 and S1S2 (P > 0.05)., Conclusion: These results suggest that the Sst I polymorphism of the apoC III gene was not associated with endogenoushypertriglyceridemica in Chinese population.

Dyslipoproteinemias are associated with hemorrheologic abnormalities (elevated fibrinogen concentration, higher viscosity of plasma and blood). Epidemiologic data suggest that not only elevated lipoprotein concentrations (eg, low-density lipoprotein [LDL] cholesterol), but also hemorrheologic abnormalities could causally be involved in the atherosclerotic process. To elucidate potential effects of hemorrheological disturbances, we investigated patients suffering from primary hyperlipoproteinemias with both low (familial hypertriglyceridemia, n = 25) and high (type III hyperlipoproteinemia, n = 21; familial hypercholesterolemia, n = 19; mixed hyperlipoproteinemia, n = 19) atherosclerotic risk, as well as healthy controls (n = 49) in a cross-sectional design. Dyslipoproteinemias were classified by lipoprotein measurements (using ultracentrifugation), family history, and apolipoprotein E phenotype. Hemorrheology was characterized by the measurement of fibrinogen concentration, viscosity of plasma and blood at different shear rates, and red cell aggregation (RCA) at stasis and low shear. Fibrinogen concentration was lower in controls (2.38 +/- 0.09 g/L) compared with familial hypercholesterolemia (3.19 +/- 0.19 g/L), to type III hyperlipoproteinemia (3.02 +/- 0.12 g/L), to familial hypertriglyceridemia (2.95 +/- 0.21 g/L) and to mixed hyperlipoproteinemia (3.01 +/- 0.12 g/L) (P < .05, respectively) without differences between dyslipoproteinemia groups. Plasma viscosity was higher in patients with type III hyperlipoproteinemia (1.42 +/- 0.03 mPas), with familial hypertriglyceridemia (1.47 +/- 0.04 mPas), and with mixed hyperlipoproteinemia (1.43 +/- 0.02 mPas) compared with controls (1.29 +/- 0.01 mPas) (P < .05, respectively). After including 6 lipoprotein parameters in a general linear model, plasma viscosity, blood viscosity, and RCA were higher in familial hypertriglyceridemia compared with healthy controls and familial hypercholesterolemia (P < .05, respectively). As most of the hemorrheologic abnormalities were still significant after adjusting for lipoprotein concentrations, they seem to be at least partly independent from direct lipoprotein effects. Hemorrheologic abnormalities in familial hypertriglyceridemia (low atherosclerotic risk) were at least as marked as in dyslipoproteinemias with high atherosclerotic risk, suggesting that it might be most important to determine lipoprotein concentrations and to define exactly the type of dyslipoproteinemia for estimating the individual cardiovascular risk in these patients.

The ATP cassette-binding (ABC) gene superfamily contains more than 40 members, many of which are involved in cellular lipid transport. The most prominent example is ABCA1, mutations in which affect plasma high-density lipoprotein (HDL) cholesterol concentration. ABCC6 is another member of the ABC gene family, and mutations in ABCC6 were recently shown to cause pseudoxanthoma elasticum (PXE). A Canadian patient with PXE was referred for assessment of moderately severe type IV hyperlipoproteinemia with hypoalphalipoproteinemia, which was refractory to pharmacological treatment. We identified intron-exon boundaries of ABCC6 to sequence genomic DNA from this patient to find the disease mutation. We report (1) identification of a set of amplification primers for the 31 exons of ABCC6; (2) identification of the ABCC6 R>X1164 nonsense mutation in the PXE subject with dyslipidemia; (3) identification of common amino acid variants and silent nucleotide variants in ABCC6, with a range of allele frequencies across ethnic groups; (4) evidence consistent with a possible pseudogene encoding 9 exons with sequence homology to ABCC6; and (5) association of the ABCC6 R>Q1268 variant with plasma triglyceride and HDL cholesterol. The results suggest that ABCC6 may be a determinant of plasma lipoproteins.

We evaluated platelet function in patients with familial hypertriglyceridemia (FHTG). Compared with healthy gender-matched controls, platelets from patients showed lower aggregation (P < .01) and thromboxane formation (P < .01) in response to collagen. Very-low-density lipoprotein (VLDL) particles obtained from the patients inhibited collagen-induced aggregation, whereas VLDL particles from controls had opposite effects. The VLDL-induced effect was regulated by its apolipoprotein E (apoE) content. Indeed, apoE-VLDL-rich fractions caused antiaggregative effects, whereas apoE-VLDL-poor fractions produced a strong proaggregative response. Since we have recently demonstrated that VLDL particles may regulate the activity of platelet low-density lipoprotein (LDL) receptor by a phenomenon of downregulation and desensitization, in this study, we have investigated the effect of prolonged exposure to circulating VLDL levels on the activity of platelet LDL receptor by a double-blind controlled study with gemfibrozil (600 mg twice daily) in 18 subjects with FHTG. Platelets from patients exhibited fewer platelet LDL receptors and 125I-LDL binding was saturable at a lower protein concentration. After 6 months, gemfibrozil therapy versus placebo had a marked lipid-lowering effect, significantly decreased triglycerides (61%), VLDL cholesterol (72%), apoB (28%), and apoE (55%), and increased high-density lipoprotein (44%) and apoA-I (18%). Furthermore, gemfibrozil affected the apoprotein composition of VLDL: total protein increased by 28%, the molar ratio of apoE to apoB decreased 64%, and apoE content decreased 55%. However, no differences in phospholipid, triglyceride, or total cholesterol were detected. Moreover, platelet function was markedly altered by gemfibrozil therapy. Collagen-induced aggregation and thromboxane formation were significantly enhanced (P < .01). The initial antiaggregative pattern of VLDL particles was changed to a significant proaggregative effect (P < .01), and the number of LDL binding sites was markedly upregulated (P < .001). Both receptor upregulation and the change in the aggregative effect of VLDL particles were associated with the reduction of apoE content in VLDL particles (P < .05). The overall results indicate that in the regulation of platelet reactivity in hypertriglyceridemic patients, apoE content of VLDL particles and their interaction with the platelet LDL receptor are involved.

Background: The basal lipid peroxide concentration in the plasma of patients with hyperlipidemia may be related to atherosclerosis. Quantitative determination of lipid peroxides in the plasma is an important step in the overall evaluation of the biochemical processes leading to oxidative injury. Unfortunately, the currently available methods for lipid peroxidation lack specificity and sensitivity., Methods: Hyperlipidemic patients (44 males and 50 females), ages 12-82 years (mean +/- SE, 53 +/- 2.3 years for males, 58 +/- 2.0 years for females, and 56 +/- 14 years for total cases), and normolipidemic volunteers (controls, 32 males and 15 females), ages 13-90 years (49 +/- 4 years for males, 65 +/- 4 years for females, and 55 +/- 24 years for total cases), were recruited in the present study. Plasma phosphatidylcholine hydroperoxide (PCOOH) was determined by chemiluminescence-HPLC (CL-HPLC)., Results: Plasma PCOOH concentrations increased with age in both controls and hyperlipidemic patients. However, the mean plasma PCOOH concentration in patients with hyperlipidemia (331 +/- 19 nmol/L; n = 94) was significantly (P <0.001) higher than in the controls (160 +/- 65 nmol/L; n = 47). Plasma PCOOH concentrations were similar in three hyperlipidemic phenotypes: hypercholesterolemia (IIa), hypertriglyceridemia (IV), and combined hyperlipidemia (IIb). The mean plasma PCOOH in patients with treatment-induced normalized plasma lipids was 202 +/- 17 nmol/L. There was no significant correlation between plasma PCOOH concentration and total cholesterol, triglycerides, or phospholipids in hyperlipidemic patients. For all subjects, there was a significantly positive correlation between plasma PCOOH and each lipid (total cholesterol, P = 0.0002; triglycerides, P = 0.0137; and phospholipids, P <0.0001). Analysis of fatty acids composition of plasma phosphatidylcholine showed significantly low concentrations of n-6 fatty acids moieties (linoleic acid and arachidonic acid) in patients compared with controls., Conclusions: Our results suggest that an increase in plasma PCOOH in patients with hyperlipidemia may be related to the development and progression of atherosclerosis, particularly in the elderly. Measurement of plasma PCOOH is useful for in vivo evaluation of oxidative stress.

Remnant-Like Particles (RLP) isolated by an immunoseparation method are heterogeneous in their physical and biochemical properties. The objective of this study was to examine the relation between RLP-triglyceride (RLP-TG) to RLP-cholesterol (RLP-C) ratio and particle size distribution in RLP-C profiles from patients with hyperlipoproteinemia by HPLC. RLP were isolated from serum samples from 147 subjects. RLP-C and RLP-TG were quantified by respective enzymatic methods. Particle sizes of the RLP were measured using HPLC with 4 connected TSKgel LipopropakXL columns. Based on HPLC profiles of RLP-C from individual subjects, three different types were classified: predominantly LDL, predominantly VLDL, and mostly VLDL types. All patients with type III hyperlipidemia were mostly VLDL type but with smaller particle size of VLDL (32 nm) than other subjects. Severe hypertriglyceridemic (TG>4.52 mmoll(-1)) subjects were mostly VLDL type with large particle size (41 nm). As for all subjects (n=105) without predominantly LDL type, a significant correlation between RLP particle size and RLP-TG to RLP-C ratio (r=0. 432, P<0.001) was obtained, but not in case of serum TG to RLP-C ratio (r=0.062). It suggests that RLP-TG to RLP-C ratio might be used for discrimination of atherogenic smaller-sized lipoprotein from larger-sized TG-rich lipoprotein remnants.

The effects of bezafibrate treatment on lipoprotein metabolism were investigated in hypertriglyceridemic subjects. Bezafibrate, a fibric acid derivative, was administered at 200-400 mg/day to 8 patients with hyperlipoproteinemia (type IIb and IV) for 3-6 months. We evaluated the effects of bezafibrate on the plasma levels of total cholesterol(chol), triglyceride(TG), and apoB. In addition, the lipid and apoB contents were also analyzed in VLDL, IDL, LDL and HDL fractions before and after the treatment. It was revealed that plasma levels of chol, TG and apoB significantly decreased after the treatment, 236.3 vs 210.9,192.4 vs 90.2 (p< 0.01) and 129.8 vs 116.2 (p<0.05) mg/dl respectively. VLDL-chol, VLDL-TG and VLDL-apoB dropped from 26.5,127.6 and 11.1 mg/dl to 9.1, 49.5 and 6.7 mg/dl respectively after the treatment. Regarding qualitative alterations of VLDL, TG/apoB, chol/apoB and TG + chol/apoB ratios in VLDL were significantly reduced, indicating that the size of VLDL was diminished by the treatment. In addition, HDL-chol increased from 40.4 to 60.8 mg/dl after the treatment. Consequently LDL-chol/HDL-chol significantly decreased. In conclusion, bezafibrate administration decreased the TG, chol and apoB content in VLDL, suggesting a reduced number of VLDL. Significant rise of HDL-chol and decrease of LDL-chol/HDL-chol are additional beneficial effects following bezafibrate treatment.

Aim: To examine antithrombogenic activity of the vascular wall, some hemostatic and rheological properties of blood in patients with unstable angina (UA) and various types of hyperlipoproteinemia (HLP)., Material and Methods: 102 UA patients were divided into groups by HLP types according to D. S. Frideriksen. Antithrombogenic properties of blood vessel wall were examined with the cuff test, blood rheology--with AKP-2 analyser, hemostasis and lipid metabolism--with standard test., Results: UA patients with HLP have low antithrombogenic activity of vascular wall. The most noticeable shifts to hypercoagulation were found in patients with HLP types 2a and 2b. Blood rheology was abnormal (high red cell aggregation in low deformability) in patients with HLP types 2a, 2b and 4., Conclusion: Patients with UA demonstrate relationships between antithrombogenic activity of vascular wall, intensity of lipid metabolism, hemostasis and blood rheology.

Contents of serum HDL subclasses in normolipidemics (n = 24) and type IV hyperlipidemics (n = 24) were determined using two-dimensional gel electrophoresis associated with immunodetection method. The results showed that the contents of pre-beta 1 HDL (P < 0.001) and HDL3a (P < 0.05) increased significantly and that of HDL2b (P < 0.001) decreased significantly in hyperlipidemics, compared with normolipidemics. Serum TG concentrations of hyperlipidemics showed positive correlation with pre-beta 1 HDL (r = 0.582) and HDL3a (r = 0.692) and negative correlation with HDL2b (r = -0.506) and HDL2a (r = -0.552). These results indicated that the maturation of HDL could be abnormal in type IV hyperlipidemics.

Serum triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) concentrations are inversely correlated and mechanistically linked by means of lipid transfer activities. Phospholipid transfer activity (PLTA) moves phospholipids among serum lipoproteins; cholesteryl ester transfer activity (CETA), which exchanges cholesteryl esters (CE) and TG among lipoproteins, is stimulated by nonesterified fatty acids (NEFA). The aims of this study were (a) to develop a quantitative model that correlates the neutral lipid (NL = CE + TG) compositions of HDL and LDL with serum TG concentration; (b) identify the serum lipid determinants of CETA and PLTA, and; (c) identify the effects of serum TG reductions on the neutral lipid compositions of HDL and LDL, serum NEFA concentrations, and on PLTA and CETA. These aims were addressed in 40 hypertriglyceridemic subjects before and after treatment with an 85% concentrate of omega-3 fatty acids (Omacor) and in 16 untreated normolipidemic subjects. In vivo, the NL compositions of LDL and HDL were described by a mathematical model having the form of adsorption isotherms: HDL - (TG/NL) = (0.90 +/- 0.07) serum TG/(7.0 +/- 1.2 mmol/l + serum TG) and LDL - (TG/NL) = (0.65 +/- 0.08) serum TG/(4.9 +/- 1.5 mmol/l + serum TG). Reduction of serum TG was associated with reductions in HDL - (TG/NL), serum NEFA concentration, and serum CETA but not PLTA. These data suggest that both hypertriglyceridemia and the attendant elevated serum CETA but not PLTA are determinants of HDL and LDL composition and structure and that serum TG concentrations are good predictors of the NL compositions of HDL and LDL.

Previous studies have investigated the potential atherogenicity and thrombogenicity of triglyceride-rich lipoprotein (TRL) remnants by isolating them from plasma within a remnant-like particle (RLP) fraction, using an immunoaffinity gel containing specific anti-apoB-100 and anti-apoA-I antibodies. In order to characterize lipoproteins in this RLP fraction and to determine to what extent their composition varies from one individual to another, we have used automated gel filtration chromatography to determine the size heterogeneity of RLP isolated from normolipidemic control subjects (n = 8), and from type III (n = 6) and type IV (n = 9) hyperlipoproteinemic patients, who by selection had similarly elevated levels of plasma triglyceride (406 +/- 43 and 397 +/- 35 mg/dl, respectively). Plasma RLP triglyceride, cholesterol, apoB, apoC-III, and apoE concentrations were elevated 2- to 6-fold (P < 0. 05) in hyperlipoproteinemic patients compared to controls. RLP fractions of type III patients were enriched in cholesterol and apoE compared to those of type IV patients, and RLP of type IV patients were enriched in triglyceride and apoC-III relative to those of normolipidemic subjects. In normolipidemic subjects, the majority of RLP had a size similar to LDL or HDL. The RLP of hyperlipoproteinemic patients were, however, larger and were similar in size to TRL, or were intermediate in size (i.e., ISL) between that of TRL and LDL. Compared to controls, ISL in the RLP fraction of type III patients were enriched in apoE relative to apoC-III, whereas in type IV patients they were enriched in apoC-III relative to apoE. These results demonstrate that: 1) RLP are heterogeneous in size and composition in both normolipidemic and hypertriglyceridemic subjects, and 2) the apoE and apoC-III composition of RLP is different in type III compared to type IV hyperlipoproteinemic patients.

Familial apolipoprotein (apo) CII deficiency is a rare autosomal recessive inborn error of metabolism clinically resembling lipoprotein lipase deficiency. A number of mutations of the apo CII gene are known to date; they are located in the promoter region, the coding exons, or in the splice junctions. We present a simple assay based on PCR and denaturing gradient gel electrophoresis, which allows scanning of the promoter, the entire coding sequence, and the splice junctions of the apo CII gene for sequence variants. All gene fragments are amplified using a common PCR protocol and are examined for mutations on a single gradient gel. Using this method and direct sequencing, we identified homozygosity for a donor splice-site mutation in the second intron, previously designated apo CII-Hamburg, as the genetic cause of apo CII deficiency in a 9-year-old boy presenting with chylomicronemia, eruptive xanthoma, and pancreatitis. In addition, the method allowed us to detect all of six different other known mutations of the apo CII gene. We conclude, therefore, that our assay is highly sensitive; in addition, it is easy to perform and may facilitate the differential diagnosis of disorders of lipoprotein metabolism at the genetic level.

Familial combined hyperlipidaemia (FCH) is not a single entity with a clearly defined cause but can occur through an increased fatty acid flux from adipose cells, lipoprotein lipase dysfunction or apolipoprotein CIII abnormalities. A dynamic model of the metabolic processes of FCH has been used to describe how lipolysis of adipose cells may ultimately contribute to the formation of atherosclerotic plaques. Elevated circulating levels of chylomicrons are broken down to produce atherogenic remnants. One of the roles of lipoprotein lipase is in the low density lipoprotein (LDL) receptor-like protein-mediated uptake of lipoprotein remnants in the liver and up to 20% of FCH patients show a genetic abnormality of this enzyme. Vitamin A loading and measurement of chylomicron retinyl palmitate levels has further demonstrated impaired chylomicron remnant metabolism in these patients. Macrophages located in the vascular walls engulf remnants but are unable to metabolize their cholesterol. These cells contribute to atherosclerotic plaques. In terms of atherogenic potential, triglyceride levels are found to be higher and the hypertriglyceridaemia more severe in fed than in fasted patients. A case study of a patient with abetalipoproteinaemia suggests that the hypertriglyceridaemia seen in patients with FCH may be the result of an abnormality in microsomal triglyceride transport protein function. Studies also suggest a direct relationship between the post-prandial triglyceride levels and LDL cholesterol levels in the fasting state of patients with FCH and sporadic hypercholesterolaemia.