Post-heparin plasma lipoprotein lipase and hepatic lipase in normal subjects and in patients with hypertriglyceridaemia: correlations to sex, age and various parameters of triglyceride metabolism.

1. A selective immunochemical method was used to measure post-heparin plasma lipoprotein lipase and hepatic lipase activity in eighty-two normal subjects and in twenty patients with type IIb, IV or V hypertriglyceridaemia. In twenty-six normal subjects the activity of post-heparin plasma lipases was compared with the kinetic parameters of endogenous plasma triglyceride metabolism. 2. The activity of post-heparin lipoprotein lipase was significantly higher in normal females than in males, whereas the activity of hepatic lipase showed an opposite sex ratio. The activity of lipoprotein lipase decreased with age both in males and females, whereas no significant age variation was observed in the activity of hepatic lipase. 3. In normal subjects a highly significant negative correlation was present in both sexes between the activity of post-heparin plasma lipoprotein lipase and fasting serum triglyceride concentration, but not between the activity of post-heparin hepatic lipase and serum triglycerides. 4. The fractional removal rate of endogenous triglycerides was positively correlated to the activity of lipoprotein lipase but not to the activity of hepatic lipase. No relationship was found between the activities of post-heparin plasma lipases and the absolute turnover of serum triglycerides. 5. The mean activity of post-heparin plasma lipo-protein lipase was significantly lower in subjects with hyperprebetalipoproteinaemia than in normal individuals. However, many hypertriglyceridaemic patients had lipoprotein lipase within the normal range and there was no correlation between serum triglyceride concentration and the activity of post-heparin lipases. 6. All three patients with fasting chylomicronaemia had low post-heparin lipoprotein lipase activity. Several subjects with high post-heparin plasma hepatic lipase activity were present in the group with hyperprebetalipoproteinaemia, but the mean value of the hepatic lipase was not significantly different from normal.     

Serum lipids and lipoproteins in children, adolescents and young adults in 1980-1986

A multicentre study on atherosclerosis precursors in young Finns aged three to 18 years was started in 1980 (3596 subjects) serum lipid concentrations (cholesterol, HDL (high density lipoprotein) cholesterol and triglycerides) were determined (n = 3554) and the apolipoproteins A-I and B measured (n = 1355). Two follow-up studies were carried out in 1983 (n = 2851) and 1986 (n = 2489), when HDL-subfractions (HDL-2-cholesterol and HDL-3-cholesterol) were also determined. Apolipoproteins A-I and B were measured again in 1986 (n = 1202). Serum total cholesterol concentration has fallen by about 1% annually during the 1980's from 5.07 mmol/l (1980) to 4.79 mmol/l (1986) in 9- to 18-year old children and adolescents. Mean values of serum triglycerides have slightly increased during the follow-up from 0.79 mmol/l to 0.84 mmol/l, respectively. In children and young adults (3-24 years) the mean cholesterol concentration was highest at the age of six and lowest during puberty. Concentrations of serum cholesterol, LDL (low density lipoprotein) cholesterol apoprotein B and triglycerides were higher in eastern than in western Finland in 1980 and 1983, but these differences were smaller in 1986, with the exception of serum triglycerides. Both in 1983 and in 1986 HDL-2-cholesterol was lower in the west than in the east, whereas HDL-3-cholesterol was higher in the former. The favourable changes in lipid levels should be reflected in future morbidity and mortality rates from coronary heart disease in Finland.     

Role of lipases, lecithin:cholesterol acyltransferase and cholesteryl ester transfer protein in abnormal high density lipoprotein metabolism in insulin resistance and type 2 diabetes mellitus

Dyslipidaemia, hallmarked by low HDL cholesterol and high plasma triglycerides, is a feature of insulin resistance and type 2 diabetes mellitus. These lipoprotein abnormalities represent major cardiovascular risk factors in these conditions. Among other factors, lipoprotein lipase (LPL), hepatic lipase (HL), lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) play an important role in an abnormal HDL metabolism in insulin resistance and type 2 diabetes mellitus. LPL hydrolyses lipoprotein triglycerides, thus providing lipids for HDL formation. In insulin resistant states, a decreased post-heparin plasma LPL activity contributes to a low HDL cholesterol, whereas an increased activity of HL reduces HDL particle size by hydrolysing its triglycerides and phospholipids. High HL activity coincides with low HDL cholesterol. The esterification of free cholesterol by LCAT increases HDL particle size. Subsequent CETP action results in transfer of cholesteryl esters from HDL towards triglyceride-rich lipoproteins. This cholesteryl ester transfer process results in lower HDL cholesterol and indirectly decreases HDL size. Plasma cholesterol esterification is unaltered or increased, whereas cholesteryl ester transfer is enhanced in type 2 diabetes mellitus, abnormalities which are probably related to the degree of hypertriglyceridaemia. It is plausible that a low LPL activity contributes to premature atherosclerosis as observed in insulin resistance and type 2 diabetes mellitus, but the effects of high HL activity and altered plasma cholesterol esterification on atherosclerosis development are uncertain. Since the cholesteryl ester transfer process between lipoproteins provides a metabolic intermediate between low HDL cholesterol and high plasma triglycerides, hypertriglyceridaemia-associated accelerated transfer of cholesteryl ester out of HDL may be pathogenetically involved in the development of cardiovascular disease in insulin resistance and type 2 diabetes mellitus.     

Common genetic variants that relate to disorders of lipid transport in Spanish subjects with premature coronary artery disease

Fifteen common polymorphic variants at six loci (apolipoproteins AI, B, CIII and E, hepatic lipase and lipoprotein lipase) involved in plasma lipid transport have been studied in 210 northern Spanish men, of whom 98 had proven coronary artery disease. The other 112 men were clinically free from coronary artery disease and acted as controls. The genotypes were investigated for relationships with plasma lipid and lipoprotein levels, as well as for the presence of coronary artery disease. As expected, the mean levels of plasma triacylglycerols (triglycerides) and lipoprotein (a) and the number of smokers were significantly higher in the disease group, and high-density lipoprotein (HDL)-cholesterol was significantly lower. Surprisingly, plasma cholesterol and low-density lipoprotein cholesterol were not different between the two groups. With regard to the common mutations, plasma triacylglycerol levels were related to the HindIII variants of lipoprotein lipase (P<0.05), to the apolipoprotein CIII variant (C3175G in exon 4) and to the apolipoprotein AI XmnI polymorphisms (P<0.05 and P<0.02 respectively). The apolipoprotein E variants were related to plasma cholesterol (P<0.05), HDL-cholesterol (P<0.02), plasma triacylglycerols (P<0.05) and the triacylglycerol/HDL ratio (P<0.01). Only the three-codon insertion/deletion variants of the apolipoprotein B signal peptide region discriminated between the two groups with or without arterial disease (P=0.02). The possible functional effects of these common mutations are discussed.     

In vivo platelet activity and lipoprotein patterns in coronary artery disease

In order to determine the effect of hyperlipoproteinemia on the in vivo formation of circulating platelet aggregates (CPA) in patients with coronary artery disease, CPA ratios, lipoprotein pattern, serum cholesterol and triglycerides were determinated in 80 male patients with stable coronary artery disease and hyperlipoproteinemia. Similar studies were performed in 30 male age-matched patients with stable coronary artery disease without hyperlipoproteinemia and 60 male age-matched healthy volunteers; the latter group served as controls. CPA ratios were significantly lowered; i.e. an increase was observed in circulating platelet aggregates in 24 patients without hyperlipoproteinemia as compared with the values in the control group. All the cardiac patients with hyperlipoproteinemia had a significantly lower CPA ratio than the patients without hyperlipoproteinemia. Moreover, the lowering in CPA ratio was more marked among patients with type II a hyperlipoproteinemia than in those with type IV. We think that this in vivo test for platelet function may throw more light on the effect of hyperlipoproteinemia on the in vivo aggregation of circulating platelets in patients with coronary artery disease.     

Fenofibrate for the treatment of type IV and V hyperlipoproteinemias: a double-blind, placebo-controlled multicenter US study

The results of a randomized, double-blind, placebo-controlled multicenter trial of fenofibrate in the treatment of type IV/V hyperlipoproteinemia are reported. Ten study centers in the United States recruited 147 adults with a history of type IV or V hyperlipoproteinemia. After a six- to 12-week dietary stabilization period and a four-week placebo period, patients whose 12-hour fasting total plasma triglyceride levels ranged from 350 to 1,500 mg/dl were continued in the study; 55 patients with levels of 350 to 499 mg/dl were placed in group A and 92 with levels of 500 to 1,500 mg/dl in group B. Patients in each group were randomly assigned to receive 100 mg of fenofibrate or placebo three times daily for eight weeks. In both groups A and B fenofibrate-treated patients showed statistically significant reductions in levels of total cholesterol, very-low-density lipoprotein cholesterol, total triglycerides, and very-low-density lipoprotein triglycerides, and significant increases in high-density lipoprotein cholesterol; patients in group B also showed a significant increase in low-density lipoprotein cholesterol levels. Sixteen of the 75 fenofibrate-treated patients and 11 of the 72 placebo patients reported adverse events that were potentially drug related; most of these were gastrointestinal and a few reported musculoskeletal and skin reactions. It is concluded that fenofibrate is an effective and safe agent in the treatment of type IV/V hyperlipoproteinemia.     

Plasma concentrations of apolipoprotein A-I containing particles in normolipidaemic young men

Low levels of plasma high-density lipoprotein (HDL)-cholesterol and apolipoprotein (apo)-A-I are associated with premature coronary heart disease. However, particles in the density range of HDL are heterogeneous. Two main types of apo A-I-containing particles can be identified, one species containing both apo A-I and apo A-II (Lp A-I:A-II) and the other apo A-I but no apo-A-II (Lp A-I). This study was designed to measure HDL cholesterol, apo A-I, and, using a new procedure, Lp A-I in 233 healthy normolipidaemic young men (cholesterol less than 250 mg dl-1 and triglycerides less than 200 mg dl-1). Among these subjects, the composition of HDL was very variable as indicated by the 10th and the 90th percentiles of the HDL-cholesterol/apo A-I ratios which were 0.32 and 0.49, respectively. The 10th and 90th percentiles of apo A-I and Lp A-I:A-II were 126 and 167 mg dl-1 and 83 and 116 mg dl-1, respectively. On the other hand, Lp A-I showed a much larger variation, the 10th and 90th percentiles being at 33 and 62 mg dl-1, respectively. The distribution of individual values of Lp A-I showed that this fraction of apo A-I-containing particles was very variable among subjects, the Lp A-I/apo A-I ratio extending from 0.18 to 0.58. Triglycerides, Lp A-I and Lp A-I:A-II were correlated with HDL cholesterol, but no correlation between apo A-I containing subfractions and plasma triglycerides was noticed. Since preliminary results from angiographic and clinical studies show that Lp A-I could exert a protective role for atherosclerosis, it would seem that the measurement of Lp A-I might help in the future to characterize better the individual's risk for atherosclerosis.     

In vitro remodelling of plasma lipoproteins in whole plasma by lipoprotein lipase in primary and secondary hypertriglyceridaemia

In patients with familial lipoprotein lipase deficiency (FLPL-d) and glycogen storage disease type I (GSD-I), hypertriglyceridaemia (1445 +/- 247 and 1082 +/- 312 mg dl-1, n = 5 per group) was associated primarily with reduced extrahepatic lipoprotein lipase (LPL) activity (0.33 +/- 0.33 and 1.69 +/- 0.38 mumol FFA ml-1 h-1) when compared with controls (4.83 +/- 0.90). Hypercholesterolaemia was characterized by elevated LDL cholesterol (191 +/- 30 and 344 +/- 34 vs. 115 +/- 5 mg dl-1 in controls P less than 0.01) and low HDL cholesterol (12 +/- 2 and 22 +/- 2 vs. 56 +/- 3 in controls, P less than 0.001). In order to ascertain the role of LPL in the interconversion and remodelling of lipoproteins in these disorders, we analysed lipid and lipoprotein profiles before and following in vitro incubation of patient plasma with purified milk LPL (EC 3.1.1.34) for 6 h at 37 degrees C. The efficiency of exogenous LPL in vitro was demonstrated by the extent of hydrolysis of chylomicrons and of VLDL-TG in both groups. Concomitant with the disappearance of TG-rich lipoprotein particles, a consistent per cent increment of IDL (99.2 +/- 30.8 and 43.9 +/- 70.5), LDL (152.8 +/- 36.2 and 137.0 +/- 36.1) and of HDL2 (144.8 +/- 29.4 and 99.8 +/- 18.7) was observed in both groups of patients. The enhancement of the latter fractions contrasted with the decline of HDL3 mass concentration (25.4 +/- 7.7 and 51.4 +/- 5.8%), suggesting that a major shift of HDL3----HDL2 occurs following in vitro lipolysis by LDL. Simultaneous compositional and morphological changes of individual lipoprotein particles were noted, confirming the dynamic movement and exchange of neutral lipids and proteins. Specificity of LPL results was demonstrated by experiments in which incubation of the whole plasma at 37 degrees C without exogenous lipolytic enzyme did not cause any substantial changes. The present study, therefore, demonstrates a correction of the major lipoprotein abnormalities associated with FLPL-d and GSD-I by exogenous LPL. No substantial difference was noted between primary (FLPL-d) and secondary (GSD-I) hyperlipidaemias. These studies allow us to conclude that a simple in vitro system, utilizing an exogenous source of LPL and plasma from patients, may serve as a suitable model for the study of the metabolic relationships of lipoproteins. However, in view of the fact that the extent of lipolysis achieved in vitro did not differ between FLPL-d and GSD-I, it may not be able to separate primary from secondary hyperlipaemias.     

Apolipoprotein E polymorphisms in Mexican patients with coronary artery disease.

BACKGROUND: Apolipoprotein E polymorphisms have important effects on plasma lipid levels and in the genetic susceptibility to development of cardiovascular diseases. Thus, the purpose of this study was to investigate the association of apolipoprotein E polymorphisms with coronary artery disease and with plasma lipid levels in a group of Mexican Mestizo patients. METHODS: Apolipoprotein E polymorphisms were determined in 156 Mexican patients with coronary artery disease and 200 non-related healthy controls using the restriction fragment length polymorphism technique. The correlation of these polymorphisms with lipid profile (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides) in the patient group was determined. RESULTS: A similar distribution of allele and genotype frequencies in coronary artery disease patients and healthy controls was found. Higher serum levels of high-density lipoprotein cholesterol and lower levels of low-density lipoprotein cholesterol, triglycerides and glucose were found in patients with the APOE*2/3 genotype when compared to patients with the APOE*3/4 and APOE*3/3 genotypes, although these differences were not significant. CONCLUSIONS: Our data suggest that genetic variation at the APOE is not a genetic factor related to the genetic susceptibility to coronary artery disease in Mexican individuals, but the role of this polymorphism in determining the lipid profile cannot be excluded.     

Lipid evaluation in HIV-1-positive patients treated with protease inhibitors

There is accumulating evidence that human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) can induce hyperlipidaemia. To evaluate the frequency and type of hyperlipidaemia in PI-treated patients, 98 outpatients were prospectively analysed for their lipoprotein characteristics at the Medizinische Hochschule in Hannover, Germany. Fifty-seven percent of the patients studied presented with hyperlipidaemia. Both hypertrigylceridaemia (type IV and V hyperlipoproteinaemia, 33%) and hypercholesterolaemia (type IIa hyperlipoproteinaemia, 6%) were detectable. The remaining 18% had a type IIb hyperlipoproteinaemia. Increased lipid levels were highly statistically significant compared to a control group of PI-naive HIV-1-infected patients [low-density lipoprotein (LDL) 146 mg/dl (range, 53-274 mg/dl) versus 105 mg/dl (range, 22-188 mg/dl; P=0.0006); very-low-density lipoprotein (VLDL) 35.5 mg/dl (5-253 mg/dl) versus 18 mg/dl (range, 3-94 mg/dl; P=0.0002)]. All PIs used (saquinavir, indinavir, nelfinavir and ritonavir) were associated with this variable form of hyperlipidaemia according to the Fredrickson classification. There was no significant correlation of any determined lipid value with the duration of treatment. A higher frequency of the apolipoprotein E2 allele and E4 allele was observed in the hyperlipidaemic subjects. Patients with excessive hypertriglyceridaemia showed a reduced lipoprotein lipase activity. Lipodystrophy was observed especially in hyperlipidaemic patients and to a lesser extent in normolipidaemic subjects. The frequency of hyperlipidaemic risk factors was surprisingly high in the group studied, which in turn may explain the proposed increased risk of atherogenesis in HIV-1 PI-treated patients. Therefore, PI-treated subjects should also be evaluated for their lipoprotein pattern, which may require antihyperlipidaemic interventions.     

LDL-apheresis: indications and clinical experience in a tertiary cardiac centre

OBJECTIVE: To determine the efficacy and safety of liposorber D low-density lipoprotein (LDL) apheresis system in high-risk cardiac patients. DESIGN: Retrospective analysis of 466 treatments undertaken in eight patients with coronary heart disease. Five patients had severe heterozygous familial hypercholesterolaemia (FH), one had severe hypertriglyceridaemia and two were cardiac transplant recipients with FH intolerant to statins. Acute reductions during single sessions and preprocedural long-term changes in lipoprotein subfractions, laboratory safety parameters, adverse events and clinical outcome were recorded. RESULTS: In 352 treatments performed in seven patients, acute reductions averaged 52.8% (standard deviation: 8.61%) for total cholesterol (TC), 61.8% (10.13%) for LDL-cholesterol (LDL-C), 21.1% (9.66%) for high-density lipoprotein cholesterol (HDL-C), 71.1% (median) for lipoprotein (a) [Lp(a)] and 44.5% (14.42%) for triglycerides (p < 0.05). Long-term reductions of TC, LDL-C, Lp(a) and triglycerides by 18.1%, 21.7%, 9.4% (median) and 19.8%, respectively, were achieved. HDL-C was increased by 7.5%. Results from the patient with severe hypertriglyceridaemia were analysed separately because of markedly elevated TC and triglycerides. Technical and clinical complications were mild and showed an incidence of 16.65% and 12.45% respectively. The most common clinical event was transient hypotension (5.8%), whereas vascular access difficulties (11.3%) represented a common technical problem. All patients demonstrated clinical improvement. However, two patients treated via a central line developed septicaemia, resulting in endocarditis in one of them. CONCLUSION: Liposorber D is a simple, safe and effective modality in reducing atherogenic lipoproteins in dyslipidaemic high-risk cardiac patients. The treatment via an arteriovenous fistula is the preferred vascular access in this type of patient.     

Efficacy of ciprofibrate in primary type II and IV hyperlipidemia: the Italian multicenter study

The 127 diet-resistant primary hyperlipidemic patients received 100 mg of ciprofibrate daily for 12 weeks. In the 63 patients with type IIa hyperlipidemia and 41 patients with type IIb hyperlipidemia, serum levels of total cholesterol, very-low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, very-low-density lipoprotein triglycerides, and apolipoprotein (apo) B decreased significantly and levels of high-density lipoprotein cholesterol and apo A-I increased significantly. Similar changes occurred in the 23 type IV patients, except that high-density lipoprotein cholesterol levels increased significantly and apo B levels did not change. No clinically significant side effects or drug-related abnormal laboratory test results were noted. It is concluded that ciprofibrate is a safe and potent hypolipidemic agent.     

Triglyceride lipase activity in postheparin plasma and plasma lipoproteins in liver disease.

Hepatic lipase activity and lipoprotein lipase activity were studied in postheparin plasma from 14 patients with various liver disorders. Plasma lecithin: cholesterol acyltransferase (LCAT) activity and lipoprotein composition and structure were also estimated. Five patients had lower hepatic lipase activity than the lowest control value, and in three of these no hepatic lipase activity was detected. Lipoprotein lipase was low in 5 patients, but in only one of them was hepatic lipase activity also low. Hepatic lipase was not significantly correlated to the concentration of plasma triglycerides, either in controls or in patients, whereas lipoprotein lipase was negatively correlated with plasma triglycerides both in controls and patients. Lipoprotein lipase and LCAT activity, but not hepatic lipase, was negatively correlated to the triglyceride content of the low density lipoproteins (density 1.019-1.063 g/ml) from the patients. No specific lipid or lipoprotein pattern was found in plasma from the patients with a low or without any hepatic lipase activity. The results suggest an important role of lipoprotein lipase and LCAT, for the increased content of triglycerides in the low density lipoproteins in patients with liver disease. The role of hepatic lipase remains unclear.     

Ciprofibrate treatment decreases non-high density lipoprotein cholesterol and triglycerides and increases high density lipoprotein cholesterol in patients with Frederickson type IV dyslipidemia phenotype

OBJECTIVE: The combination of hypertriglyceridemia and low high density lipoprotein (HDL) cholesterol is one of the most common lipid abnormalities. Thus, the aim of this study was to determine the effects of ciprofibrate on lipid profile in patients with Frederickson's type IV dyslipidemia phenotype. RESEARCH DESIGN AND METHODS: Seventy-five patients with type IV dyslipidemia were assigned at random to 1 of 2 therapeutic options: group A (control), American Heart Association (AHA) Step II diet and physical activity; and group B, AHA diet, physical activity, and ciprofibrate 100 mg daily for 8 weeks. The lipid profile of all patients was determined at baseline and after therapeutic intervention. RESULTS: Patients in group B (treated with ciprofibrate) compared with group A (control) had significantly higher reductions in total cholesterol (downward arrow 14.2% vs. downward arrow 4.8%; P < 0.02), triglycerides (downward arrow 38.0% vs. downward arrow 21.6%; P < 0.007), very low density lipoprotein cholesterol (downward arrow 38.0% vs. downward arrow 21.6%; P < 0.007), non-HDL cholesterol (downward arrow 20.5% vs. downward arrow 7.1%; P < 0.007), and total cholesterol/high density cholesterol ratio (downward arrow 25.6% vs. downward arrow 9.4%; P < 0.01). The ciprofibrate group had a significantly higher increase in HDL cholesterol levels compared with the other group (upward arrow 25.0% vs. upward arrow 9.6%, P < 0.02). CONCLUSIONS: Ciprofibrate treatment effectively reduced triglyceride-rich particles and non-HDL cholesterol, and significantly increased HDL cholesterol, proving its effectiveness in patients with low HDL cholesterol and type IV Frederickson's hyperlipidemia.     

Change in very low-, low-, and high-density lipoproteins during lipid lowering (bezafibrate) therapy: studies in type IIA and type IIb hyperlipoproteinaemia

The effects of lipid lowering therapy (bezafibrate) on plasma lipoproteins was investigated in twelve patients with familial hypercholesterolaemia (type IIA) and eight with familial combined hyperlipidaemia (type IIB). Bezafibrate caused a decrease of plasma cholesterol, plasma triglycerides, plasma apolipoprotein B, VLDL cholesterol and LDL cholesterol and an increase of HDL cholesterol. Post-heparin plasma lipoprotein and hepatic lipase activities increased in both groups (significant only in type IIB). Lipoprotein composition showed the following changes: Increased protein and phospholipids and decreased triglycerides and cholesteryl esters in VLDL. Decreased protein and triglycerides and increased free and esterified cholesterol in LDL. Decreased triglycerides and increased phospholipids in HDL. Cholesteryl ester to protein ratios decreased in VLDL and increased in LDL. The hydrated density of LDL (both groups) and of HDL3 (type IIB) decreased following bezafibrate therapy. These changes were in general similar to those observed in hypertriglyceridaemic patients and could be ascribed, at least in part, to the increase of plasma lipase activities and the decrease of lipid transfer reactions. Comparing the present data with that previously reported, it was found that bezafibrate caused decreased LDL cholesterol in types IIA and IIB but increased levels in type IV. This change was correlated with the initial plasma triglycerides (r = 0.74, P less than 0.0001) and initial plasma LDL cholesterol (r = 0.66, P less than 0.001). It is concluded that varied response of LDL to therapy reflects a complex interaction of metabolic events, including changing rates of VLDL conversion to LDL, lipoprotein compositional changes and effects of therapy on LDL degradation rates.     

Dyslipidaemia and its management after immunosuppressive treatment

This article summarises the mechanisms responsible for the hyperlipidaemia observed after immunosuppressive treatment. Much progress has been achieved in the treatment of organ transplantation over the last 10 years, in particular because of the use of new immunosuppressive drugs with less nephrotoxicity. However, hypercholesterolaemia and hypertriglyceridaemia persist among many patients, who are thus more likely to develop cardiovascular diseases. We first reviewed the effects of immunosuppressive drugs on biliary acid biosynthesis, which is the main pathway of cholesterol degradation. The inhibition of this biosynthesis pathway, and especially of some key cytochrome P450s (CYP) such as CYP27A1, could contribute to the increased cholesterolaemia. Immunosuppressive drugs may also modify the activity of lipoprotein receptors or the expression of different apolipoproteins involved in cholesterol and triglyceride transport by lipoproteins. Finally, the fact that hypertriglyceridaemia is more frequently observed after certain immunosuppressive treatments may be partly caused by changes in the synthesis and elimination of triglycerides involving lipoprotein lipase or some apolipoproteins which serve as its cofactors (apoCII or apoCIII).     

冠心病合并2型糖尿病患者不稳定动脉粥样硬化斑块的评估及影响因素的分析

目的研究合并2型糖尿病的冠状动脉粥样硬化性心脏病（冠心病）患者与非2型糖尿病冠心病患者的不稳定动脉粥样硬化斑块的差别。方法在行冠脉造影术时,通过血管内超声（IVUS）对146例冠心病患者病变血管进行检测,测定是否有不稳定粥样硬化斑块,并评估冠脉狭窄程度。根据患者是否存在糖尿病,分为2组进行对比,同时定量分析患者相关冠心病危险因素：性别、年龄、体质指数（BMI）、高血压、甘油三酯、总胆固醇、低密度脂蛋白胆固醇水平等。结果糖尿病组的不稳定冠状动脉钙化斑块数量显著多于非糖尿病组（P〈0.05）,糖尿病组的低密度脂蛋白胆固醇水平显著大于非糖尿病组（P〈0.05）。结论合并2型糖尿病患者冠脉形成不稳定斑块较非2型糖尿病患者的风险更大,同时2型糖尿病患者的低密度脂蛋白胆固醇水平更高于非2型糖尿病患者。对于同时合并有2型糖尿病的患者在积极控制血糖水平的同时,应积极进行调整血脂治疗,使不稳定斑块向稳定型斑块转化,降低冠脉事件的发生。     

The Asn-291→Ser and Ser-477→Stop mutations of the lipoprotein lipase gene and their significance for lipid metabolism in patients with hypertriglyceridaemia

We examined 99 Finnish patients whose serum fasting triglycerides (TG) had exceeded 6.0 mmol L^?1, with special interest to their lipid, lipoprotein and post-heparin plasma lipase activities. The control group consisted of 75 healthy individuals. We also determined the frequency of the Asn-291→Ser and Ser-447→Stop mutations both in hypertriglyceridaemic (HTG) subjects and in control subjects. A total of 51 of the original 99 hypertriglyceridaemic patients still had TG > 6.0 mmol L^?1 when measured a second time. They are referred to as persistently hypertriglyceridaemic subjects (pHTG). The remaining 48 subjects had TG < 6.0 mmol L^?1 in the second measurement and are referred to as sporadically hypertriglyceridaemic subjects (sHTG). The allelic frequencies of the Ser-447→Stop mutation in the total HTG and sHTG groups were similar to the frequencies present in the control group, but lower in pHTG patients compared with the control group (0.049 vs. 0.153, χ² = 6.63, P < 0.05). The Asn-291→Ser mutation was more frequent in HTG group than in the control group (0.0606 vs. 0.013, χ² = 4.86, P < 0.05). This difference was due to the higher frequency of the minor allele of Asn-291→Ser in the cohort with persistent hypertriglyceridaemia compared with the control group (0.088 vs. 0.013, χ² = 8.00, P < 0.01 ). The highest frequency (0.114) of the minor allele of Asn-291→Ser was found in type 2 diabetic patients with persistent hypertriglyceridaemia. The carrier status of Asn-291→Ser or Ser-447→Stop did not predict either post-heparin plasma lipoprotein lipase (LPL) activities or lipid and lipoprotein levels in any of the groups studied. Our data suggest that overproduction of very low-density lipoproteins (VLDL) is a more important cause of hypertriglyceridaemia in the Finns than is the LPL deficiency.     

Common variants in the lipoprotein lipase gene in Brazil: association with lipids and angiographically assessed coronary atherosclerosis.

Lipoprotein lipase is the rate-limiting enzyme in the lipolysis of plasma triglyceride-rich lipoproteins. We studied six variants (T-93G, D9N, N291S, PvuII, HindIII and S447X) in the lipoprotein lipase (LPL) gene in 309 non-diabetic patients with angiographically assessed coronary artery disease and in 197 controls in a southern Brazilian population of European descent. The HindIII H-allele was associated with lower triglycerides (p < 0.01) and higher high-density lipoprotein cholesterol (p = 0.03) levels, and the S447X mutation was associated with lower triglyceride levels (p < 0.01) in males, but not females. No other significant lipid associations were observed. Haplotypes were derived from these two sites (HindIII/S447X), and carriers of H-S and H-X haplotypes showed lower triglycerides (p < 0.01) and increased high-density lipoprotein cholesterol (p = 0.01) levels when compared to the H+S haplotype in males. In this gender, the H-X haplotype was associated with a protective effect (OR = 0.36, 95%CI = 0.13-0.97) for significant disease (> or = 60% of luminal coronary stenosis), even controlling for other classical risk factors.     

Conversion of type III hyperlipoproteinaemia to type IV hyperlipoproteinaemia by a fat-free, carbohydrate rich diet.

Hyperlipoproteinaemia type III has been considered a clear cut clinical entity characterized by the presence of cholesterol rich "floating" beta very low density lipoproteins (VLDL) after ultracentrifugation. Carbohydrate inducibility is pronounced in type III. This study was undertaken to elucidate the effect of a high carbohydrate diet in type III as an effort to clarify a suggested association between type III and IV hyperlipoproteinaemia. On an isocaloric fat free carbohydrate rich diet the lipoprotein pattern changed as the VLDL triglycerides increased 31 per cent on average and LDL and HDL cholesterol decreased by 40 and 22 per cent. The high ratio cholesterol/triglycerides in VLDL was normalized. The lipoprotein levels in serum after carbohydrate induction showed all characteristics of a type IV with high VLDL triglycerides, normal cholesterol/triglyceride ratio in VLDL, subnormal cholesterol levels in LDL and HDL with changed relation between LDL1 and LDL2. On electrophoresis the floating beta band disappeared. It is probable that depending on the nutritional situation, the metabolic defect in type III may be expressed either as a type III or a type IV. An explanation of the effects of the carbohydrate rich diet on the lipoprotein pattern is suggested.