Renal disease as a determinant of increased lipoprotein(a) concentrations in diabetic patients

OBJECTIVE: This study examined the hypothesis that kidney function is an independent determinant of lipoprotein(a) [Lp(a)] concentrations in people with diabetes. RESEARCH DESIGN AND METHODS: Lp(a) concentrations were measured in plasma samples from 273 type 2 and 223 type 1 diabetic patients recruited from a diabetes clinic. Kidney function was categorized as normal or pathological according to plasma creatinine levels and creatinine clearance rates. RESULTS: Macroalbuminuria was uniformly associated with significantly raised plasma concentrations of Lp(a) regardless of the marker used to identify kidney dysfunction. In contrast, in patients with microalbuminuria, significantly raised plasma Lp(a) levels were observed only when creatinine clearance rates or plasma creatinine levels indicated pathological kidney function. These conclusions were independent of diabetes type. CONCLUSIONS: In microalbuminuria and apparently in normoalbuminuria, altered kidney function determined by creatinine clearance rates or creatinine levels appears to be a major determinant of raised Lp(a) levels in both type 1 and type 2 diabetic patients. In contrast, Lp(a) concentrations were uniformly raised in patients with macroalbuminuria.     

Three different LDL apheresis columns efficiently and equally reduce lipoprotein(a) concentrations in patients with familial hypercholesterolemia and small apolipoprotein(a) particles

Introduction

High levels of lipoprotein(a) [Lp(a)] and apolipoprotein(a) [apo(a)] are associated with cardiovascular disease. In this study we determined apo(a) particle size and compared the Lp(a) reducing efficacy of three different LDL apheresis columns; DL-75, LA-15 and EC-50W in patients with familial hypercholesterolemia (FH).

Results

Average Lp(a) concentration was reduced by 70%, 74% and 75% (all p < 0.0001) for DL-75, LA-15 and EC-50W, respectively. No significant changes in the relative proportion of the isoforms of 14 and 32 K 4 domains were observed after apheresis.

Conclusion

Three different LDL apheresis columns reduced Lp(a) efficiently with preserved ratio between apo(a) isoforms.     

Plasma PCSK9 concentrations correlate with LDL and total cholesterol in diabetic patients and are decreased by fenofibrate treatment

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes the degradation of the LDL receptor (LDLr) in hepatocytes, and its expression in mouse liver has been shown to decrease with fenofibrate treatment. METHODS: We developed a sandwich ELISA using recombinant human PCSK9 protein and 2 affinity-purified polyclonal antibodies directed against human PCSK9. We measured circulating PCSK9 concentrations in 115 diabetic patients from the FIELD (Fenofibrate Intervention and Event Lowering in Diabetes) study before and after fenofibrate treatment. RESULTS: We found that plasma PCSK9 concentrations correlate with total (r = 0.45, P = 0.006) and LDL (r = 0.54, P = 0.001) cholesterol but not with triglycerides or HDL cholesterol concentrations in that cohort. After 6 weeks of treatment with comicronized fenofibrate (200 mg/day), plasma PCSK9 concentrations decreased by 8.5% (P = 0.041 vs pretreatment). This decrease correlated with the efficacy of fenofibrate, as judged by a parallel reduction in plasma triglycerides (r = 0.31, P = 0.015) and LDL cholesterol concentrations (r = 0.27, P = 0.048). CONCLUSIONS: We conclude that this decrease in PCSK9 explains at least in part the LDL cholesterol-lowering effects of fenofibrate. Fenofibrate might be of interest to further reduce cardiovascular risk in patients already treated with a statin.     

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.     

Impact of postprandial lipaemia on low-density lipoprotein (LDL) size and oxidized LDL in patients with coronary artery disease

BACKGROUND: Remnant lipoprotein particles (RLPs) and oxidative stress are components of postprandial state. We investigated the concentrations of triglyceride-rich lipoproteins (TRLs), RLPs, low-density lipoprotein (LDL) size, and oxidized LDL (oxLDL) during alimentary lipaemia, and evaluated whether changes among these variables could be associated with the severity and extent of coronary artery disease (CAD). MATERIALS AND METHODS: Eighty men and 27 women with clinically suspected CAD underwent quantitative coronary angiography (QCA). TRLs were isolated by density gradient ultracentrifugation before and 6 h after an oral fat load. RLPs were measured by an immunoseparation method, oxLDL by ELISA, and LDL size by gradient gel electrophoresis. RESULTS: Triglycerides, apolipoprotein (apo) B-48, and apoB-100 concentration in Swedberg flotation units (Sf) > 400 and in Sf 12-400 fractions were markedly increased at 6 h. Postprandial cholesterol content of RLPs (RLP-C) correlated with respective triglycerides in Sf > 400 (r = 0.737) and Sf 12-400 (r = 0.857), apoB-48 in Sf > 400 (r = 0.710) and Sf 12-400 (r = 0.664), apoB-100 in Sf > 400 (r = 0.812) and Sf 12-400 (r = 0.533). RLP-C correlated with oxLDL both in fasting and in fed state (r = 0.482 and r = 0.543, respectively) and inversely with LDL size (r = -0.459 and r = -0.442, respectively). (P < 0.001 for all). OxLDL was elevated postprandially (P < 0.001). In multivariate analysis, oxLDL was a determinant of severity and extent of CAD. CONCLUSION: Postprandial state is associated with oxidative stress. The magnitude of oxLDL increases during alimentary lipaemia and is associated with coronary atherosclerosis.     

Regional interlaboratory standardization of determinations of cholesterol, high-density lipoprotein cholesterol, and triglycerides

The Clinical Chemistry Forum of Central Virginia initiated a lipid standardization program to help ensure that its members meet the current National Cholesterol Education Program guidelines for cholesterol testing, and to standardize assays of high-density lipoprotein (HDL) cholesterol and triglycerides so as to provide accurate lipid profiles. We found that freshly collected, never-frozen human sera must be used to assess interlaboratory accuracy for cholesterol, HDL cholesterol, and triglycerides assays, and that at least 23 samples are required to detect a 3% bias with 90% power when the between-laboratory imprecision (CV) is 3%. After recalibration, all 12 laboratories had a mean HDL cholesterol bias less than or equal to 5%, nine of 10 laboratories had a mean HDL cholesterol bias less than or equal to 40 mg/L for samples with values less than or equal to 570 mg/L, and 10 of 12 laboratories had a mean triglycerides bias less than or equal to 10% for fresh human sera split between participants and the Centers for Disease Control. Pools of frozen human sera were shown to have matrix biases greater than 3% for cholesterol in seven of 11 laboratories, and greater than 40 mg/L for HDL cholesterol in six of nine laboratories.     

Normal lipoprotein(a) concentrations and apolipoprotein(a) isoforms in patients with insulin-dependent diabetes mellitus

Lipoprotein(a) [Lp(a)] is an LDL particle in which apoliporotein B-100 is attached to a large plasminogen-like protein called apolipoprotein(a) [apo(a)]. Apo(a) has several genetically determined phenotypes differing in molecular weight, to which Lp(a) concentrations in plasma are inversely correlated, and plasma Lp(a) concentrations above 20-30 mg dl-1 are an independant risk factor for ischaemic heart disease (IHD). To investigate whether Lp(a) could be important for the high cardiovascular mortality rate in patients with insulin dependent diabetes mellitus (IDDM), we determined Lp(a) concentrations and phenotypes in a group of 108 men (median age 32 years) with IDDM without nephropathy. A group of 40-year-old men (n = 466) served as controls. The median Lp(a) concentration was 7.4 mg dl-1 [95% CI 4.9 to 11.7] in the diabetic patients and 6.3 mg dl-1 [95% CI 5.2 to 7.0] in controls. The Lp(a) concentration exceeded 30 mg dl-1 in 22% of IDDM patients and in 20% of controls (P = 0.13). Moreover, the distribution of apo(a) phenotypes did not differ between patients and control. Lp(a) levels and apo(a) phenotypes are thus apparently the same in IDDM patients without nephropathy and controls. These findings do not exclude the possibility that Lp(a) may be increased in patients with nephropathy in whom coronary artery disease frequently co-exist or that Lp(a) in a given concentration is more atherogenic in IDDM patients than in persons without IDDM.     

Marked reduction in serum high-density lipoprotein cholesterol concentrations in a woman with acute inflammation due to diabetic gangrene

BACKGROUND: C-reactive protein (CRP) is a well-established, sensitive marker of systemic inflammation and the risk of cardiovascular disease. High-density lipoprotein (HDL) is an anti-atherogenic lipoprotein known to be regulated by genetic and acquired factors. METHODS: The patient was a 77-year-old Japanese woman, who was diagnosed with type 2 diabetes mellitus (DM), with a body height of 152 cm and a weight of 65 kg (body mass index 28.1 kg/m2). She suffered from diabetic foot gangrene in her right foot with high-grade fever when she visited our hospital. Her plasma glucose (PG) concentration and serum CRP were markedly elevated being 21.6 mmol/l and 370 mg/l, respectively, while her serum HDL-C concentrations were markedly low being 0.13 mmol/l. She was immediately admitted to our hospital and received intensive insulin treatment, along with intravenous-administration of antibiotics. Her general conditions were gradually improved and the high-grade fever disappeared, with concentrations of plasma PG and serum CRP being reduced, and concurrent reciprocal increase in her serum HDL-C concentrations. RESULTS: To determine the potential causative factors responsible for the drastic change in serum HDL-C concentrations, we investigated the relationship of serum HDL-C to serum CRP, serum total protein (TP) and PG. Serum CRP and PG showed inverse relationships with serum HDL-C, while serum TP concentrations showed a positive association with HDL-C. After multivariate analyses with CRP, TP and PG as independent variables and serum HDL-C as dependent variable, CRP maintained its independent association with serum HDL-C. CRP also showed inverse correlations with lipoprotein lipase (LPL) mass and cholesteryl ester transfer protein mass. CONCLUSIONS: In acute inflammation and poorly controlled diabetes, CRP is suggested to be inversely associated with serum HDL-C, independent of PG and TP.     

Effect of hypertriglyceridaemia on lipoprotein (a) serum concentrations

Abstract. Numerous studies have shown lipoprotein (a) [Lp(a)] serum levels above 0.3 gL^-1to be a genetically determined and independent risk factor for atherosclerotic vascular disease. In this study of sera from 1009 patients attending our lipid clinics, multivariate regression analysis revealed an inverse correlation between the serum concentrations of triglycerides (TG) and Lp(a) ( r =—0.31; P < 0.001) as determined by electroimmunodiffusion. This was not observed in 1237 controls from a random population. Detailed analysis of the frequency distribution of Lp(a) levels at different degrees of hypertriglyceridaemia (HTG) revealed a decreasing dosage effect of HTG on Lp(a) serum levels. In 60% of patients with TG > 9.12mmolL^-1, this effect led to undetectable serum Lp(a) levels. Dilution of hypertriglyceridaemic samples with normotriglyceridaemic sera containing high levels of Lp(a) revealed that analytical interference in part accounts for the decreasing effect of TG-rich lipoproteins on Lp(a). Re-evaluation of 45 hypertriglyceridaemic samples by enzyme immuno-assay and immunoblotting revealed the presence of small amounts of Lp(a) in several samples which were considered to be free of Lp(a) upon electroimmunodiffusion. We conclude that TG-rich lipoproteins interfere with the quantification of Lp(a), at least by electroimmunodiffusion. However, HTG may also decrease Lp(a) plasma concentrations in vivo , possibly by increased clearance of TG-rich Lp(a).     

Comparison of ultracentrifugation and a precipitation method for high-density lipoprotein cholesterol quantitation in insulin-dependent diabetic patients

We compared sodium phosphotungstic acid and magnesium chloride precipitation method for high-density lipoprotein (HDL) cholesterol quantitation with the ultracentrifugation method in 64 insulin-dependent diabetic patients with plasma triglyceride less than 3 mmol/l. The cholesterol content of HDL after precipitation of very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) was 86% +/- 3% of the cholesterol content of HDL (q greater than 1.063) determined after ultracentrifugation at q = 1.063 (1.33 +/- 0.05 mmol/l vs 1.55 +/- 0.06 mmol/l; p less than 0.001). HDL cholesterol determined after precipitation closely correlated to HDL cholesterol determined after ultracentrifugation (r = 0.97; p less than 0.001). The absolute difference between the HDL cholesterol values obtained by the two methods was correlated to HDL cholesterol (ultracentrifugation) (r = 0.75; p less than 0.001), but it was not correlated to VLDL cholesterol, LDL cholesterol, triglyceride, HbA1c, blood glucose or serum albumin. LDL cholesterol calculated by use of Friedewald's formula was 108% +/- 4% of the cholesterol content of LDL (q = 1.019 to 1.063), determined after ultracentrifugation, but the calculated and the ultracentrifugally determined LDL cholesterol values were closely correlated (r = 0.98; p less than 0.001). These results suggest that during sodium phosphotungstic acid and magnesium chloride precipitation of plasma from diabetic patients, a constant fraction of HDL cholesterol is co-precipitated, resulting in a systematic difference in HDL cholesterol quantitation when compared with the ultracentrifugation method.     

尿毒症非透析患者的微炎症状态及对脂蛋白(a)的影响

目的　通过测定尿毒症非透析患者慢性炎症指标并分析其与脂蛋白 (a) [Lp(a) ]的关系 ,探讨非透析的尿毒症患者微炎症状态及其影响心血管系统的途径。方法　测定 5 5例尿毒症患者慢性炎症指标血C 反应蛋白(CRP)、白细胞介素 6 (IL 6 )、肿瘤坏死因子α(TNF α)及Lp(a) ,分析它们之间的关系 ,并与 30例正常人比较。结果　尿毒症组血CRP、IL 6、TNF α及Lp(a)分别为 (4 .0 6± 4 .0 2 )mg/L、(10 8.3± 88.3)ng/L、(1.4 1± 0 .5 3) μg/L和 (5 5 0± 4 31)mg/L ,均高于对照组 ,其中CRP、TNF α及Lp(a)与正常组比较差异有统计学意义 ;尿毒症患者血Lp(a)与CRP、TNF α、IL 6呈明显正相关 (r值分别为 0 .6 32、0 .4 2 5、0 .4 0 5 ,均P <0 .0 1)。结论　尿毒症患者存在微炎症状态 ;炎症可能通过引起Lp(a)代谢紊乱 ,对心血管系统产生不利影响     

Cord blood cholesterol,triglycerides and lipoprotein electrophoresis in 124 Italian infants

Summary Total cholesterol (TC), triglycerides (TG), and lipoproteins (by electrophoresis on agarose gel) were determined in the cord blood of 124 Italian infants (Verona area). The mean TC and TG values, when compared with the values reported in other studies, turned out to be remarkably uniform, suggesting common genetic determinants in the modulation of blood lipids; no sex differences were observed. The TG distribution curve was skewed, overlapping the adult pattern. Cord blood TC and TG were not modified by the presence of perinatal factors. Both β and α bands (on agarose gel electrophoresis) were present in all the cases. The pre-β band was clearly detectable in 90 % of the cases; it was barely visible for TG values below 20 mg/100 ml; occasionally a discrepancy between the intensity of the pre-β band and the cord blood TG was observed, indicating a variable lipid composition of very low density lipoproteins (VLDL). In 4 % of the cases a small band at the origin of the electrophoretic run was observed, consistent with the presence of chylomicrons. In the serum of both a newborn infant and its mother we detected a double band migrating in the pre-β region. This finding confirms the hypothesis of a familial transmission of this abnormality.     

Low-density lipoprotein (LDL) receptor/transferrin fusion protein: in vivo production and functional evaluation as a potential therapeutic tool for lowering plasma LDL cholesterol

A soluble form of human low-density lipoprotein receptor (LDL-R) fused in frame with rabbit transferrin (LDL-Rs(hu)/Tf(rab)) is assessed in vivo as a therapeutic tool for lowering plasma LDL cholesterol. The cDNA encoding LDL-Rs(hu)/Tf(rab) is expressed in mice, using a hydrodynamics-based gene transfer procedure. The transgene is transcribed in the liver of transduced animals and the corresponding protein is secreted into the bloodstream. Circulating LDL-Rs(hu)/Tf(rab) binds LDL specifically, thus indicating that it is correctly processed through the cellular compartments in vivo. More importantly, the expression of LDL-Rs(hu)/Tf(rab) allows the removal of injected human (125)I-labeled LDL ((123)I-LDL) from the bloodstream of transduced CD1 mice, which show faster LDL plasma clearance, anticipating by approximately 90 min the same clearance value observed in control animals. A similar effect is observed in transduced LDL-R(-/-) mice, in which the clearance of injected human LDL depends solely on the presence of circulating LDL-Rs(hu) /Tf(rab). In these animals the extent of plasma LDL clearance is directly related to the concentration of LDL-Rs(hu)/Tf(rab) in the blood. Finally, LDL-Rs(hu)/Tf(rab) does not alter the pattern of LDL organ distribution: in transduced animals, as well as in control animals, liver and bladder are the predominantly labeled organs after (123)I-LDL injection. However, LDL-Rs(hu)/Tf(rab) has a quantitative effect on LDL tissue deposition: in treated animals LDL-Rs(hu)/Tf(rab) determines an increase in radioactivity in the liver at early times after (123)I-LDL injection and a progressive labeling of the bladder, starting 20 min after injection.     

Additive effects of Simvastatin beyond its effects on LDL cholesterol in hypertensive type 2 diabetic patients

BACKGROUND: Experimental evidence indicates that statins might have direct vascular effects independently from low-density lipoprotein (LDL) cholesterol reduction and we reported that the reduction in urinary albumin excretion rate during Simvastatin treatment in type 2 diabetic patients was not correlated with LDL-cholesterol decrease. However in humans there are no data regarding possible additional effects of Simvastatin on blood pressure and urinary albumin excretion beyond its capacity to lower serum cholesterol. PATIENTS AND METHODS: Twenty-six microalbuminuric hypertensive type 2 diabetic patients (diastolic blood pressure - after four months wash-out from the previous antihypertensive therapy - consistently > 90 and < 100 mmHg; plasma LDL-cholesterol > 3.9 and < 6.5 mmol L-1) were enrolled in the study. In random order, these patients received Simvastatin (20 mg day-1) or Cholestyramine (6 g three times a day) for a period of 10 months and after three months of wash-out (cross-over) the sequence was reversed for an additional 10 months. Blood pressure, lipid parameters, glycated haemoglobin and urinary albumin excretion were measured during the study. Additionally, in eight patients, urinary glycosaminoglycan excretion (GAG) was also measured during the study. RESULTS: Simvastatin and Cholestyramine were equally effective in reducing total and LDL cholesterol. Only during Simvastatin treatment a significant reduction in diastolic blood pressure and both 24 h urinary albumin and GAG excretion rates were observed, while no significant changes were seen with Cholestyramine treatment. CONCLUSIONS: Our results clearly show for the first time that the reduction of blood pressure, together with 24 h urinary albumin excretion rate - two established cardiovascular risk factors, obtained during Simvastatin therapy in hypertensive type 2 diabetic patients - is in large part independent from the reduction of LDL Cholesterol.     

Serum concentrations of small dense low‐density lipoprotein cholesterol and lipoprotein(a) are related to coronary arteriostenosis in Takayasu arteritis

BackgroundSerum small dense low‐density lipoprotein cholesterol (sdLDL‐C) and lipoprotein(a) [Lp(a)] levels are related to coronary disease, but their specific associations with coronary arteriostenosis in Takayasu arteritis (TA) have not been ascertained. This study explored the correlations between serum sdLDL‐C and Lp(a) levels and coronary arteriostenosis in TA patients as well as the degree of artery stenosis.MethodsThis retrospective study included 190 TA patients and 154 healthy subjects. TA patients were divided into three categories based on the degree of coronary stenosis: Group I, stenosis >50%; Group II, stenosis 1%–50%; and Group III, stenosis 0%. Independent risk factors for coronary arteriostenosis in TA were identified by logistic regression, followed by receiver operating characteristic curve analysis to determine the specificity and sensitivity of risk factors and Youden''s Index score calculation to determine the cutoff points.ResultsTakayasu arteritis patients had significantly higher serum levels of sdLDL‐C and Lp(a) than healthy controls (p < 0.0001). The total cholesterol, triglyceride, LDL‐C, sdLDL‐C, and Lp(a) levels and the sdLDL‐C/LDL‐C ratio in Group I were significantly higher than those in Groups II and III (p < 0.05). An elevated serum sdLDL‐C level elevated the risk of coronary arteriostenosis by 5‐fold (cutoff value, 0.605 mmol/l). An increased serum Lp(a) level increased the risk of coronary arteriostenosis by 3.9‐fold (cutoff value, 0.045 g/l). An elevated sdLDL‐C/LDL‐C ratio increased the risk of coronary arteriostenosis by 2.1‐fold (cutoff value, 0.258).ConclusionsSerum sdLDL‐C and Lp(a) levels and sdLDL‐C/LDL‐C ratio may be used as diagnostic factors for coronary arteriostenosis in TA patients.     

Ratio of triglycerides to HDL cholesterol is an indicator of LDL particle size in patients with type 2 diabetes and normal HDL cholesterol levels

OBJECTIVE: In patients with type 2 diabetes, a normal HDL cholesterol level does not rule out that LDL particles may be small. Although techniques for analyzing LDL subfractions are not likely to be used in clinical practice, a prediction of LDL size based on a regular lipid profile may be useful for assessment of cardiovascular risk. RESEARCH DESIGN AND METHODS: Sixty patients with type 2 diabetes with acceptable glycemic control and an HDL cholesterol level > or = 1 mmol/l were recruited after cessation of lipid-altering treatments. LDL size was determined by 2-20% PAGE; patients having small LDL (n = 30) were compared with those having intermediate or large LDL (n = 30). RESULTS: Clinical characteristics, pharmacological therapies, lifestyle, and prevalence of diabetes-related complications were similar in both patient groups. LDL size correlated negatively with plasma triglycerides (TGs) (R2 = 0.52) and positively with HDL cholesterol (R2 = 0.14). However, an inverse correlation between the TG-to-HDL cholesterol molar ratio and LDL size was even stronger (R2 = 0.59). The ratio was > 1.33 in 90% of the patients with small LDL particles (95% CI 79.3-100) and 16.5% of those with larger LDL particles. A cutoff point of 1.33 for the TG-to-HDL cholesterol ratio distinguishes between patients having small LDL values better than TG cutoff of 1.70 and 1.45 mmol/l. CONCLUSIONS: The TG-to-HDL cholesterol ratio may be related to the processes involved in LDL size pathophysiology and relevant with regard to the risk of clinical vascular disease. It may be suitable for the selection of patients needing an earlier and aggressive treatment of lipid abnormalities.     

超速离心HPLC测定血清脂蛋白亚类和脂蛋白(a)胆固醇方法的建立

目的 建立血清高密度脂蛋白（HDL）亚类、低密度脂蛋白（LDL）亚类和脂蛋白（g）[Lp（a）]胆固醇准确测定方法。方法 血清与含脯氨酸的溴化钠溶液混合，使背景密度为1，006和1．044，血清与含脯氨酸和巯基乙醇（ME）的溴化钠溶液混合，使背景密度为1，044、1．063和1．125，超速离心，用高效液相色谱测定各种超速离心底部组分胆固醇，计算HDL亚类（HDL2和HDk）、LDL亚类（LDL．和LDLb）及Lp（g）胆固醇。结果 ME使Lp（g）解离，解离前后Lp（g）存在明显密度分界点（1．044），使脂蛋白亚类和Lp（g）胆固醇测定成为可能；测定HDL2、HDL3、LDL。LDLb及Lp（g）胆固醇的总变异系数分别为0．85％～2．66％、0，87％～3．21％、0．86％～1，11％、2，59％～6．35％和4．42％～12．29％。结论 建立新的血清HDL和LDL亚类及Lp（g）胆固醇测定方法，方法可靠、精密、简便，可望在脂蛋白亚类和Lp（a）胆固醇测定标准化中发挥作用。     

High density lipoprotein cholesterol concentrations in physically active and sedentary spinal cord injured patients

Individuals with traumatic spinal cord injury (SCI) are extremely inactive yet little is known about the long-term consequences of chronic inactivity. Current research investigated the concentrations of high density lipoprotein cholesterol (HDLc) and its subfractions HDL2 and HDL3 in 66 extremely sedentary SCI admissions to a rehabilitation center. High density lipoprotein cholesterol is a primary risk factor for cardiovascular disease with decreased levels associated with increased cardiovascular risk. The concentrations of HDLc observed in the SCI sedentary population were compared with 22 olympic caliber wheelchair athletes (SCI athletes) and 126 able-bodied controls. Total HDLc, HDL2, and HDL3 was significantly lower in the male SCI sedentary population (34.2 mg/dl, 8.9 mg/dl, 25.3 mg/dl) than the male SCI athletes (42.7 mg/dl, 13.9 mg/dl, 28.8 mg/dl) or male able-bodied control populations (47.1mg/dl, 11.3mg/dl, 35.8 mg/dl). A similar pattern emerged for the female subjects. The reduction in HDLc seen in the SCI sedentary would predict over a 60% increased risk of heart attack compared to nondisabled controls. The primary difference between the two SCI groups was the level of physical activity, suggesting that this may be an important parameter for elevating total HDLc and HDL2, and presumably decreasing the risk for coronary heart disease. Therefore, physical activity positively affects total HDL and the supposedly antiatherogenic subfraction HDL2 in the SCI patient.