Adipokines and insulin resistance

Obesity is associated with an array of health problems in adult and pediatric populations. Understanding the pathogenesis of obesity and its metabolic sequelae has advanced rapidly over the past decades. Adipose tissue represents an active endocrine organ that, in addition to regulating fat mass and nutrient homeostasis, releases a large number of bioactive mediators (adipokines) that signal to organs of metabolic importance including brain, liver, skeletal muscle, and the immune system--thereby modulating hemostasis, blood pressure, lipid and glucose metabolism, inflammation, and atherosclerosis. In the present review, we summarize current data on the effect of the adipose tissue-derived hormones adiponectin, chemerin, leptin, omentin, resistin, retinol binding protein 4, tumor necrosis factor-alpha and interleukin-6, vaspin, and visfatin on insulin resistance.

CXCL16 is a surrogate marker of inflammatory bowel disease

OBJECTIVE

Impaired barrier function of the gut and inadequate immunological response to intestinal pathogens are the cornerstones in the pathogenesis of inflammatory bowel disease (IBD). CXCL16 is a protein which shares pattern recognition receptor functions, relevant for adhesion and phagocytosis of bacterial products, with the properties of an adhesion molecule and inflammatory chemokine. The relevance of CXCL16 in IBD has so far been elusive. This objective of this study was to determine the association between CXCL16 and IBD.

MATERIAL AND METHODS

Soluble CXCL16 (sol-CXCL16) serum levels in a cohort of 239 patients with Crohn's disease were measured, 114 patients with ulcerative colitis and 144 controls.

RESULTS

In a univariate analysis, sol-CXCL16 was found to be markedly increased in patients with Crohn's disease or ulcerative colitis compared with that in controls (p < 0.001). This was significantly associated with an increase of the inflammatory marker C-reactive protein (CRP) (p < 0.01). In the multivariate analysis (adjusted for age, gender, body mass index (BMI), white blood cell (WBC) count, resistin and CRP) sol-CXCL16 was associated with Crohn's disease above versus below the median (OR 10.53 (3.97-27.78) p < 0.001) and ulcerative colitis (OR 3.46 (1.40-8.55) p < 0.01).

CONCLUSION

Our findings suggest that CXCL16 may play a pro-inflammatory role in IBD, particularly Crohn's disease.

Effect of the angiotensin receptor blocker irbesartan on metabolic parameters in clinical practice: the DO-IT prospective observational study

Aims

A number of intervention studies have shown that therapy with angiotensin receptor blockers, such as irbesartan, can improve metabolic parameters and reduce the incidence of diabetes mellitus. It is unknown whether this observation also holds true in routine clinical settings.

Methods

We evaluated the effect of irbesartan (150 mg or 300 mg/d) together with or without hydrochlorothiazide (12.5 mg/d) in 3259 German patients. A total of 750 primary care physicians evaluated up to 5 subsequent patients with metabolic syndrome (58.9% diabetic), in whom irbesartan therapy was newly initiated (87%) or continued (13%).

Results

Six months of irbesartan therapy decreased systolic blood pressure by 14% (157.4 ± 14.7 vs. 135.0 ± 10.7 mmHg) and diastolic blood pressure by 13% (92.9 ± 9.2 vs. 80.8 ± 6.8 mmHg). This was associated with a decrease in body weight (-2.3%), fasting glucose (-9.5%), HbA1c (-4.6%), LDL-cholesterol (-11%), triglycerides (-16%) and gamma-GT (-12%) and an increase in HDL-cholesterol (+5%). These changes were somewhat more pronounced in male than in female patients and in obese than in lean patients. Changes in glucose concentration and HbA1c were much more prominent in diabetic patients.

Conclusion

Irbesartan therapy improves metabolic parameters in routine clinical settings. Thus, our study confirms previously published results from large intervention trials and extends the findings to routine clinical practice.

[Cushing's syndrome with bilateral nodular adrenal enlargement]

ACTH-independent macronodular bilateral adrenal hyperplasia (AIMAH) is a rare cause of endogenous Cushing's syndrome. Here, massive bilateral adrenal enlargement is accompanied by ACTH-independent hypercortisolism. The detection of ectopic hormone receptors which, according to a new concept, control the cortisol production in AIMAH, offers the opportunity of normalizing the hypercortisolism by pharmacologically influencing the receptor or its ligand. We here present the case of a 46 year old male patient. Using clinical and pharmacological tests we found evidence of ectopic receptors in the AIMAH. After suspicion was erroneously raised that a malignant lesion could be inside of the right adrenal mass, the decision was made to resect both adrenals instead of trying to treat the hypercortisolism by pharmacological means. This surgical approach (bilateral adrenalectomy) has been the standard way of treatment for AIMAH until the new concept of the ectopic receptors was developed.

[Glucagon-like peptide 1 (GLP-1)]

GLP-1 receptor agonists such as exenatide are a group of new therapeutic agents that mimic the gut-derived incretin hormone GLP-1. These drugs stimulate insulin secretion while suppressing glucagon secretion, inhibit gastric motility, reduce appetite and hence, food intake. This group of drugs also induce reduction in fasting and postprandial glucose concentrations, HbA1c and ultimately lead to weight loss. The drugs are administered subcutaneously (exenatide twice daily). The most common side effect is mild nausea. Although short-term studies are promising, long-term clinical studies are needed to determine the benefits of this approach for the treatment of type 2 diabetes.

Short-term therapy with atorvastatin or fenofibrate does not affect plasma ghrelin, resistin or adiponectin levels in type 2 diabetic patients with mixed hyperlipoproteinaemia

Lipid-lowering therapy is associated with reduced cardiovascular risk. The aim of the present study was to investigate whether lipid-lowering therapy might be associated with changes in the concentrations of metabolically important hormone concentrations. We performed a randomised cross-over open-label trial with atorvastatin (10 mg/day) and fenofibrate (200 mg/day), each for 6 weeks separated by a 6-week washout period in 13 patients (5 men, 8 women, age 60.0+/-6.8 years, body mass index 30.0+/-3.0 kg/m2) with type 2 diabetes mellitus and mixed hyperlipoproteinaemia. Plasma ghrelin (RIA, Phoenix Pharmaceuticals, Mountain View, CA, USA), adiponectin (ELISA, Biovendor, Heidelberg, Germany) as well as resistin (ELISA, Linco Research, St. Charles, MO, USA) concentrations were measured before and after atorvastatin as well as before and after fenofibrate. Ghrelin (462+/-84 pg/ml before vs. 464+/-102 pg/ml after atorvastatin, n.s.; 454+/-85 pg/ml before vs. 529+/-266 pg/ml after fenofibrate, n.s.), resistin (24.4+/-7.4 pg/ml before vs. 23.7+/-9.1 pg/ml after atorvastatin, n.s.; 23.4+/-8.2 pg/ml before vs. 19.9+/-5.5 pg/ml after fenofibrate, n.s.), adiponectin (10.89+/-5.33 pg/ml before vs. 12.41+/-5.75 pg/ml after atorvastatin, n.s.; 12.58+/-9.87 pg/ml before vs. 10.27+/-5.23 pg/ml after fenofibrate, n.s.) and insulin levels did not change significantly during lipid-lowering therapy. In patients with type 2 diabetes and mixed hyperlipoproteinaemia, short-term atorvastatin as well as fenofibrate therapy had no significant effects on adiponectin, ghrelin or resistin levels.

Apolipoprotein A-IV is an independent predictor of disease activity in patients with inflammatory bowel disease

BACKGROUND

ApoA-IV, an apolipoprotein (apo) with antioxidant, antiatherogenic, and antiinflammatory properties, was recently demonstrated to inhibit dextran sulfate sodium (DSS)-induced experimental colitis in mice. We therefore hypothesized that apoA-IV may be associated with disease activity in patients with inflammatory bowel disease (IBD).

METHODS

We addressed this question by testing for associations between apoA-IV genotypes, apoA-IV plasma levels, inflammatory parameters, and clinical disease activity in 206 patients with Crohn's disease (CD), 95 subjects with ulcerative colitis (UC), and 157 healthy controls.

RESULTS

In CD patients, apoA-IV plasma levels were inversely associated with C-reactive protein (CRP) (P = 0.005) and disease activity (P = 0.01) in univariate analysis. In multiple logistic regression analysis, apoA-IV levels were identified as an independent predictor of elevated CRP (odds ratio [OR] 0.956, 95% confidence interval [CI]: 0.916-0.998, P = 0.04) and active disease (OR 0.957, 95% CI: 0.918-0.998, P = 0.04). In UC patients the apoA-IV gene variant 360 His (P = 0.03) but not apoA-IV levels (P = 0.15) were associated with increased disease activity in univariate analysis. This association, however, was lost in multiple logistic regression analysis (OR 3.435, 95% CI 0.995-11.853, P = 0.05).

CONCLUSIONS

To our knowledge, this is the first study to demonstrate an association of apoA-IV with disease activity in patients with CD. Further studies are needed to define the relationship of apoA-IV to IBD.

Postprandial lipoprotein metabolism in familial hypobetalipoproteinemia

OBJECTIVE

Familial hypobetalipoproteinemia (FHBL) is an autosomal codominantly inherited disorder of lipoprotein metabolism characterized by decreased plasma concentrations of low-density lipoprotein-cholesterol and apolipoprotein (apo) B. We examined the effect of truncated apoB variants (<apoB-48) causing FHBL on postprandial triglyceride-rich lipoprotein (TRL) metabolism.

METHODS AND RESULTS

A standardized oral fat load was given after a 12-h fast to six heterozygous [apoB-6.9 (n=3), apoB-25.8 (n=1), apoB-40.3 (n=2)] FHBL subjects and 10 normolipidemic controls. Plasma was obtained every 2 h for 10 h. Large TRLs [containing chylomicrons (CM)] and small TRLs (containing CM remnants) were isolated by ultracentrifugation. Compared with controls, FHBL subjects had significantly decreased fasting plasma cholesterol (2.3+/-0.5 vs. 4.8+/-0.5 mmol/liter), triglyceride (0.4+/-0.3 vs. 1.5+/-0.5 mmol/liter), low-density lipoprotein-cholesterol (0.6+/-0.4 vs. 3.0+/-0.5 mmol/liter), and apoB (0.22+/-0.05 vs. 0.95+/-0.14 g/liter) concentrations (all P<0.001). The postprandial incremental area under the curve in FHBL subjects was decreased for large TRL-triglyceride (-61%; P<0.005), small TRL-cholesterol (-86%; P<0.001), and small TRL-triglyceride (-86%; P<0.001) relative to controls. Multicompartmental modeling analysis showed that the delay time of apoB-48 was shorter and that apoB-48 production was decreased in FHBL subjects compared with controls.

CONCLUSIONS

We have demonstrated that heterozygous FHBL subjects with apoB truncations shorter than apoB-48, and therefore only a single fully-functional apoB-48 allele, have decreased TRL production but normal postprandial TRL particle clearance.

Dextran-sulfate-adsorption of atherosclerotic lipoproteins from whole blood or separated plasma for lipid-apheresis—Comparison of performance characteristics with DALI and lipidfiltration

For many years dextran sulfate adsorption (DSA) treatment of separated plasma has been an established technology for low-density lipoprotein (LDL)-elimination. Recently a system for the treatment of whole blood based on DSA was introduced into clinical practice. To further characterize DSA treatment of whole blood, the performance characteristics of both DSA modalities were compared at two investigational sites with two alternative LDL apheresis systems being already in routine clinical use. In prospective cross-over design, DSA whole blood treatment was compared with a whole blood polyacrylate LDL adsorption system (DALI) in one study group. DSA for plasma treatment was compared with Lipidfiltration in cross-over design in a second study group. In total, 12 patients on chronic LDL apheresis received 169 treatments. Six patients were treated twice with whole blood polyacrylate adsorption and twice with whole blood DSA. LDL-cholesterol (74.9-78.0%) and lipoprotein (a) (72.1-73.3%) were reduced by both with equal efficacy. DSA achieved a significantly higher reduction rate of fibrinogen. Another six patients were treated eight times with DSA plasma adsorption followed by 16 Lipidfiltration treatments. LDL-cholesterol (67.0-70.2%) and lipoprotein (a) (69.2-73.7%) were reduced by both with equal efficacy. Fibrinogen was eliminated more efficiently by Lipidfiltration (50.2 vs. 38.5%). DSA proved to be a safe and effective in both treatment modes, for plasma as well as for whole blood. At the discretion of the apheresis specialist, depending upon the status of national approval, DSA of whole blood complements the armamentarium of powerful modalities for extracorporeal elimination of atherosclerotic lipoproteins to meet specific individual, medical, or logistic needs.

Comparison of automated insulin assays

A number of clinically important conditions is associated with insulin resistance and compensatory hyperinsulinemia. Since there is growing evidence that serum insulin measurement can be useful for the individual characterization of the metabolic situation, we aimed to study the agreement of serum insulin results obtained with different widely used immunoassay systems. Comparative measurement of 100 serum samples was performed with three systems (Abbott AxSYM; Bayer Centaur; and Roche Elecsys). Close correlation of the results was found with Kendall's Tau > 0.95 for all three comparisons. Between the Abbott and the Bayer assay, and between the Abbott and the Roche assay, a slope of approximately 10% was observed. Mean concentrations found were 29.2 microU/mL, 30.0 microU/mL, 27.1 microU/mL with Abbott, Bayer, and Roche, respectively. It is concluded that the three assay systems studied offer a good agreement of results with only minor systematic bias.

Plasma separation and anion adsorption transiently relieve intractable pruritus in primary biliary cirrhosis

BACKGROUND/AIMS

Pruritus can be a severely disabling symptom in patients with primary biliary cirrhosis who do not respond to treatment with ursodeoxycholic acid, anion exchangers, enzyme inducers, or opiate antagonists. The aim of this study was to assess the clinical efficacy of plasma separation and anion adsorption in the treatment of intractable pruritus of cholestasis.

METHODS

Three patients with primary biliary cirrhosis and intractable pruritus defined by severity of pruritus 7 on a rating scale between 0 (no pruritus) and 10 (maximal pruritus) on at least 4 of 7 days despite medical treatment were treated with plasma separation and anion adsorption on three consecutive days. Fatigue was assessed using the Fisk Fatigue Severity Score and quality of life was assessed by the PBC-40, a disease specific health related quality of life measure.

RESULTS

Improvement in pruritus, fatigue, and quality of life was transiently observed in all patients. Serum bile acid levels showed no association with intensity of pruritus, and the bile acid pattern was not altered. The treatment was well tolerated by all patients.

CONCLUSIONS

Plasma separation and anion adsorption seem to be a safe and effective therapeutic option for patients with primary biliary cirrhosis suffering from intractable pruritus.

The effect of telmisartan on glucose and lipid metabolism in nondiabetic, insulin-resistant subjects

Intervention studies have shown that angiotensin receptor blocker therapy may reduce the incidence of type 2 diabetes mellitus. It is unknown whether short-term angiotensin receptor blocker therapy can improve glucose and lipid metabolism in insulin-resistant subjects. We evaluated the effect of telmisartan (40 mg/d, 12 weeks) in 20 subjects with insulin resistance (body mass index, 31.8 +/- 3.31 kg/m(2); triglycerides, 179 +/- 98 mg/dL; glucose, 104 +/- 9 mg/dL; homeostasis model assessment index, 3.78 +/- 1.52) in a randomized, placebo-controlled, double-blind, cross-over study. At the end of each treatment phase, oral and intravenous glucose tolerance tests including C-peptide and insulin measurements were performed, and fasting and postprandial lipids were determined. Compared to placebo, telmisartan resulted in a reduction in homeostasis model assessment index (-11%, P = .06) and glucose area under the curve during intravenous glucose tolerance (-11%, P = .04). We observed an increase (+32%, P = .05) in the insulinogenic index indicating an improved beta-cell function. Fasting and postprandial lipid parameters did not change. We observed an increase in adiponectin (6%, P = .09), whereas IL-6, high-sensitivity C-reactive protein, fibrinogen, and free fatty acid concentrations did not change. This indicates that the improvement in glucose metabolism is rather mediated by direct effects, such as activation of PPARgamma. Our data indicate that in insulin-resistant persons 12 weeks of telmisartan result in a significant improvement in glucose metabolism with a predominant improvement in beta-cell function.

Prognostic value of interleukin 6, procalcitonin, and C-reactive protein levels in intensive care unit patients during first increase of fever

To investigate the prognostic value of interleukin 6 (IL-6), procalcitonin (PCT), and C-reactive protein (CRP) in critically ill patients during the first increase of fever, serum levels were measured in 38 patients admitted to intensive care unit of the Department of Medicine, Klinikum Grosshadern, University of Munich, immediately after increase of body temperature more than 38.3 degrees C. Ten healthy controls were also included for comparison. The onset of fever was accompanied by elevated circulating levels of all the 3 markers in comparison with healthy controls. However, only IL-6 levels were significantly higher (P < 0.05) in nonsurvivors (n = 21) compared with survivors. Sensitivity, specificity, positive, and negative predictive values calculated from median levels was higher for IL-6 compared with PCT and CRP. Areas under receiver characteristic operating curves revealed the highest area under the curve for IL-6 in contrast to PCT and CRP. These data suggest that IL-6 rather than PCT or CRP may be an early predictor of mortality in patients with onset of fever and identify patients, who need intensive monitoring to initiate appropriate therapy at an early stage.

Defining high-fat-diet rat models: metabolic and molecular effects of different fat types

High-fat (HF)-diet rodent models have contributed significantly to the analysis of the pathophysiology of the insulin resistance syndrome, but their phenotype varies distinctly between different studies. Here, we have systematically compared the metabolic and molecular effects of different HF with varying fatty acid compositions. Male Wistar rats were fed HF diets (42% energy; fat sources: HF-L - lard; HF-O - olive oil; HF-C - coconut fat; HF-F - fish oil). Weight, food intake, whole-body insulin tolerance and plasma parameters of glucose and lipid metabolism were measured during a 12-week diet course. Liver histologies and hepatic gene expression profiles, using Affymetrix GeneChips, were obtained. HF-L and HF-O fed rats showed the most pronounced obesity and insulin resistance; insulin sensitivity in HF-C and HF-F was close to normal. Plasma omega-3 polyunsaturated fatty acid (omega-3-PUFA) and saturated fatty acid (C(12)-C(14), SFA) levels were elevated in HF-F and HF-C animals respectively. The liver histologies showed hepatic steatosis in HF-L, HF-O and HF-C without major inflammation. Hepatic SREBP1c-dependent genes were upregulated in these diets, whereas PPARalpha-dependent genes were predominantly upregulated in HF-F fed rats. We detected classical HF effects only in diets based on lard and olive oil (mainly long-chain, saturated (LC-SFA) and monounsaturated fatty acids (MUFA)). PUFA- or MC-SFA-rich diets did not induce insulin resistance. Diets based on LC-SFA and MUFA induced hepatic steatosis with SREBP1c activation. This points to an intact transcriptional hepatic insulin effect despite resistance to insulin's metabolic actions.

Thematic review series: patient-oriented research. What we have learned about VLDL and LDL metabolism from human kinetics studies

Lipoprotein metabolism is the result of a complex network of many individual components. Abnormal lipoprotein concentrations can result from changes in the production, conversion, or catabolism of lipoprotein particles. Studies in hypolipoproteinemia and hyperlipoproteinemia have elucidated the processes that control VLDL secretion as well as VLDL and LDL catabolism. Here, we review the current knowledge regarding apolipoprotein B (apoB) metabolism, focusing on selected clinically relevant conditions. In hypobetalipoproteinemia attributable to truncations in apoB, the rate of secretion is closely linked to the length of apoB. On the other hand, in patients with the metabolic syndrome, it appears that substrate, in the form of free fatty acids, coupled to the state of insulin resistance can induce hypersecretion of VLDL-apoB. Studies in patients with familial hypercholesterolemia, familial defective apoB, and mutant forms of proprotein convertase subtilisin/kexin type 9 show that mutations in the LDL receptor, the ligand for the receptor, or an intracellular chaperone for the receptor are the most important determinants in regulating LDL catabolism. This review also demonstrates the variance of results within similar, or even the same, phenotypic conditions. This underscores the sensitivity of metabolic studies to methodological aspects and thus the importance of the inclusion of adequate controls in studies.

Genetic variants of adiponectin receptor 2 are associated with increased adiponectin levels and decreased triglyceride/VLDL levels in patients with metabolic syndrome

BACKGROUND

Adiponectin acts as an antidiabetic, antiinflammatory and antiatherogenic adipokine. These effects are assumed to be mediated by the recently discovered adiponectin receptors AdipoR1 and AdipoR2.

AIM

The purpose of this study was to determine whether variations in the AdipoR1 and AdipoR2 genes may contribute to insulin resistance, dyslipidemia and inflammation.

METHODS

We sequenced all seven coding exons of both genes in 20 unrelated German subjects with metabolic syndrome and tested genetic variants for association with glucose, lipid and inflammatory parameters.

RESULTS

We identified three AdipoR2 variants (+795G/A, +870C/A and +963C/T) in perfect linkage disequilibrium (r2 = 1) with a minor allele frequency of 0.125. This haplotype was associated with higher plasma adiponectin levels and decreased fasting triglyceride, VLDL-triglyceride and VLDL-cholesterol levels. No association, however, was observed between the AdipoR2 SNP cluster and glucose metabolism.

CONCLUSION

To our knowledge, this is the first study to identify an association between genetic variants of the adiponectin receptor genes and plasma adiponectin levels. Furthermore, our data suggest that AdipoR2 may play an important role in triglyceride/VLDL metabolism.

Effect of ezetimibe on low-density lipoprotein subtype distribution: results of a placebo-controlled, double-blind trial in patients treated by regular low-density lipoprotein apheresis and statins

Ezetimibe, a cholesterol absorption inhibitor, can be combined with statins to lower low-density lipoprotein (LDL) cholesterol. We have previously shown that ezetimibe can decrease LDL cholesterol by 16% even in patients treated by regular LDL apheresis and statins (Atherosclerosis. 2005;180:107-112). However, it is unclear whether ezetimibe decreases all LDL subfractions equally in patients with hypercholesterolemia. We therefore evaluated the effect of ezetimibe (5 weeks, 10 mg/d) on LDL subtype distribution in a placebo-controlled, double-blind randomized crossover study in 20 patients (age, 56+/-9 years; body mass index, 27.5+/-4 kg/m2) with severe hyperlipoproteinemia and coronary heart disease who are treated by statins and regular LDL apheresis. Both treatment periods (placebo and ezetimibe) were separated by a 5-week washout period. Low-density lipoprotein subtype distribution was determined at the end of each treatment period before apheresis by density gradient ultracentrifugation (LDL1, 1.020-1.024; LDL2, 1.025-1.029; LDL3, 1.030-1.034; LDL4, 1.035-1.040; LDL5, 1.041-1.047; LDL6, 1.048-1.057; LDL7, 1.058-1.066 g/mL). Overall, the LDL subtype distribution did not change significantly (large-buoyant LDL [LDL1+LDL2], 17.2%+/-6.4% vs 16.3%+/-7.1%; intermediate LDL [LDL3+LDL4], 49.3%+/-4.5% vs 48.2%+/-5.2%; small-dense LDL [LDL5+LDL6+LDL7], 33.5%+/-8.0% vs 35.5%+/-10% during placebo and ezetimibe treatments, respectively). With respect to the individual LDL subfractions, cholesterol was significantly (P<.05, Wilcoxon test) reduced by ezetimibe in LDL1 to LDL5 with a somewhat more pronounced reduction in larger LDL (mean+/-SD, -20%+/-28%, -17%+/-32%, -14%+/-25%, -13%+/-27%, -11%+/-21%, -7%+/-21%, -4%+/-19%; median, -28%, -12%, -18%, -16%, -4%, -4%, -2% for LDL subfractions 1-7, respectively). We therefore conclude that ezetimibe decreases cholesterol in nearly all LDL subfractions. Although this was established in patients concomitantly treated with statins and apheresis, this may also hold true in other clinically relevant situations.

In-vivo metabolism of VLDL-apolipoprotein-B, -CIII and -E in normolipidemic subjects

BACKGROUND AND AIM

ApoE and apoC-III are important components of lipoprotein metabolism. While the function of both apoproteins is relatively well understood, little is known about the in vivo metabolism of these proteins, partly because of the lack of a standardized method to isolate these apoproteins in large sample numbers.

METHODS AND RESULTS

We developed a new reverse phase HPLC method (acetonitril/phosphate gradient; Aquapore RP-300, 7 microm, 220 x 4.6 mm) to isolate a number of different apoproteins, including apoC-III and apoE from VLDL. This method was then used in a study which aimed at determining VLDL-apoE-3 and VLDL-apoC-III metabolism. In addition VLDL-apoB and LDL-apoB metabolism was determined. Endogenous labeling with d(3)-leucine, mass spectrometry and multicompartmental modeling was used in 6 normolipidemic healthy male subjects. Tracer/tracee ratios of free plasma leucine, VLDL-apoE, -apoC-III, -apoB, and LDL-apoB leucine were determined over 60 h following a bolus of d(3)-leucine (5 mg kg(-1)). In all subjects sufficient apoC-III could be isolated by reverse phase HPLC to derive metabolic parameters, while apoE metabolic parameters could only be determined if apoE plasma concentration was 0.75 mg dl(-1) or higher. Compared to VLDL-apoB (FCR 10.4 +/- 3.3 d(-1), production 17.8 +/- 4.5 mg kg(-1) d(-1)), VLDL-apoE-3 (FCR 1.03 +/- 0.11 d(-1), production 0.50 +/- 0.29 mg kg(-1) d(-1)) and VLDL-apoC-III (FCR 1.67 +/- 1.22 d(-1), production 0.44 +/- 0.24 mg kg(-1) d(-1)) parameters were much lower. This indicates that apoE-3 and apoC-III recirculate in plasma and that only a small fraction of apoE and apoC-III on VLDL is newly synthesized.

CONCLUSIONS

We conclude that HPLC methodology can be used to isolate VLDL-apoC-III and apoE for metabolic studies and that the metabolic fate of apoC-III and apoE is different from that of apoB because both apoproteins recycle through the VLDL fraction.

Increase in adiponectin levels during pioglitazone therapy in relation to glucose control, insulin resistance as well as ghrelin and resistin levels

Glitazones increase the secretion of the adipocyte-derived hormone adiponectin. Furthermore, the gastric signal peptide ghrelin is known to suppress adiponectin expression in adipocyte cell culture models. It is not known whether the increase in adiponectin during glitazone therapy is due to a suppression of ghrelin levels, a decrease of resistin concentrations or an amelioration of glucose control. In 10 patients (age 71+/-9 yr, body mass index 29.9+/-3.6 kg/m(2), HbA1c 6.9+/-0.5%) with Type 2 diabetes, who had already been treated with sulfonylureas, we additionally initiated a pioglitazone therapy (30 mg/day) for 12 weeks. To investigate the pioglitazone effect independently of blood glucose, glycosylated hemoglobin (HbA1c) was kept unchanged by reducing the daily dose of sulfonylurea if necessary. Ghrelin concentration [radioimmunoassay (RIA), Phoenix Pharmaceuticals, Mountain View, CA, USA], adiponectin levels [enzyme-linked immunosorbent assay (ELISA), Biovendor, Heidelberg, Germany] as well as resistin concentrations (ELISA, Linco Research, St. Charles, MO, USA) were measured before and after pioglitazone. Glucose control remained unchanged within the 12-week pioglitazone therapy (HbA1c 6.9+/-0.5% before vs 6.8+/-0.6% after pioglitazone) while body weight increased from 86.6+/-9.2 to 88.0+/-9.4 kg (p<0.05), and insulin concentration decreased from 19.6+/-5.7 to 10.1+/-1.6 microU/ml (p<0.05). Adiponectin concentration increased in all patients from 7.70+/-2.47 to 23.33+/-8.28 microg/ml (p<0.01), while resistin concentrations tended to decrease (by 15%; p=0.059). However, ghrelin remained unchanged during therapy. No correlations were observed either between ghrelin, resistin, insulin and adiponectin, or between body weight and hormone plasma levels. The increase in adiponectin levels during pioglitazone therapy seems to be at least partly independent of blood glucose and insulin concentration as well as of ghrelin levels, and it was not associated with a decrease in resistin concentrations.

Beyond LDL-cholesterol: HDL-cholesterol as a target for atherosclerosis prevention

Dyslipoproteinemias such as elevated LDL-cholesterol, reduced HDL-cholesterol, elevated triglycerides and elevated lipoprotein(a) play a central role in atherosclerosis. An elevated LDL concentration is pro-atherogenic because LDL are intimately linked to oxidative and inflammatory processes in the arterial wall. HDL on the other hand are anti-atherogenic because they mediate cholesterol efflux from the arterial wall, modulate the metabolism of atherogenic lipoproteins, and directly affect endothelial function. The current therapeutic focus is on LDL reduction and much less on HDL elevation, although fibrates and particularly nicotinic-acid/niacin are potent drugs to increase HDL-cholesterol and although both groups of drugs have been proven beneficial in large end-point studies. Furthermore, new HDL raising drugs are being developed. In patients with established atherosclerosis or at high risk for atherosclerosis statin-based LDL reduction will remain the cornerstone of lipid therapy, but many patients may benefit from combination therapy aiming at optimizing all lipid parameters.

Novel Mutation (Gly280Ala) in the ATP-Binding Domain of Glycerol Kinase Causes Severe Hyperglycerolemia

Glycerol kinase deficiency is a rarely diagnosed X-linked recessive disorder which occurs as a complex form together with the adrenal hypoplasia congenita (AHC) or with Duchenne muscular dystrophy (DMD) or as an isolated form either symptomatic or asymptomatic. We report the case of a male adult who had pseudo-hypertriglyceridemia (falsely elevated triglycerides of 552 mg/dl) refractory to lipid-lowering therapy for more than 15 years. Further investigations revealed an isolated, asymptomatic glycerol kinase deficiency. Using polymerase chain reaction and direct DNA sequencing, a novel missense mutation Gly280Ala in the Xp21.3 glycerol kinase gene was found. Comparison between human and E.coli glycerol kinase showed that the mutation affects a highly conserved amino acid in an ATP-binding domain in the active centre. This mutation is assumed to destabilize a hydrogen bond between ligand and enzyme resulting in a reduced activity of glycerol kinase and therefore in hyperglycerolemia.

Limited preanalytical requirements for insulin measurement

OBJECTIVES

To evaluate the stability of insulin in serum and plasma under conditions relevant for the transport of samples from outpatient clinics to a centralized laboratory.

DESIGN AND METHODS

Venous blood samples were taken from 15 volunteers and processed either immediately or after storage at room temperature for 24 h. The effect of EDTA or sodium fluoride on insulin results was investigated.

RESULTS

Insulin was found to be stable in EDTA-containing tubes at room temperature for at least 24 h, whereas significantly lower concentrations were found if samples without additives or potassium fluoride as an additive were used.

CONCLUSIONS

If shipment of patients' samples for insulin measurement from an outpatient clinic to a centralized laboratory can be performed within 24 h, centrifugation and freezing of plasma is not required. These findings facilitate a widespread application of insulin measurements to characterize and follow-up individual insulin sensitivity.

Atorvastatin improves diabetic dyslipidemia and increases lipoprotein lipase activity in vivo

A major factor contributing to cardiovascular mortality in type 2 diabetes is dyslipidemia, characterized by low HDL cholesterol and high triglycerides, rather than elevated LDL cholesterol. Lipoprotein lipase (LPL) is the rate-limiting enzyme of triglyceride removal from plasma and has been implicated in atherosclerosis. Since treatment with statins significantly reduces cardiovascular morbidity in diabetes, we analyzed the lipid profile and LPL activities in 61 patients with type 2 diabetes before and 8 weeks after initiation of atorvastatin (40 mg) or placebo treatment. Lipid parameters and LPL activity were unchanged under treatment with placebo. Atorvastatin treatment resulted in a 30% reduction of total and a 45% reduction of LDL cholesterol (6.06 +/- 1.39 mmol/L versus 4.14 +/- 1.27 mmol/L and 4.11 +/- 1.13 mmol/L versus 2.27 +/- 0.89 mmol/L, both P < 0.0001). Triglycerides and VLDL cholesterol were also significantly reduced by statin therapy (2.24 +/- 2.11 mmol/L versus 1.82 +/- 1.46 mmol/L and 1.08 +/- 1.56 mmol/L versus 0.67 +/- 0.66 mmol/L, both P < 0.05). HDL cholesterol was not different between the atorvastatin and the placebo group. Compared to baseline, LPL activity was increased by 25% after atorvastatin treatment (213.0 +/- 28.1 nmol/mL/min versus 171.9 +/- 17.7 nmol/mL/min, P < 0.01). Our data demonstrate that atorvastatin induces a significant improvement of diabetic dyslipidemia and a significant increase of LPL activity. Since low LPL activity indicates an increased cardiovascular risk, the statin-mediated increase in LPL activity may help to explain the reduction of CAD in diabetic patients treated with statins.

Effects of ursodeoxycholic acid on synthesis of cholesterol and bile acids in healthy subjects

BACKGROUND/AIMS

Ursodeoxycholic acid (UDCA) decreases biliary secretion of cholesterol and is therefore used for the dissolution of cholesterol gallstones. It remains unclear whether these changes in biliary cholesterol excretion are associated with changes in cholesterol synthesis and bile acid synthesis. We therefore studied the activities of rate-limiting enzymes of cholesterol synthesis and bile acid synthesis, 3-hydroxy-3-methylglutaryl-coenzyme A reductase and cholesterol 7alpha-hydroxylase, respectively, in normal subjects during UDCA feeding.

METHODS

UDCA was given to 8 healthy volunteers (5 men, 3 women; age 24-44 years) in a single dose of 10-15 mg/kg body weight for 40 days. Before and during (days 3, 5, 10, 20, 30 and 40) UDCA treatment, urinary excretion of mevalonic acid and serum concentrations of 7alpha-hydroxy-4-cholesten-3-one (7alpha-HCO) were determined as markers of cholesterol and bile acid synthesis, respectively. The Wilcoxon signed rank test and Spearman's rank correlation coefficient were used for statistical analysis.

RESULTS

Cholesterol synthesis and serum lipid concentrations remained unchanged during UDCA treatment for 40 days. However, synthesis of bile acids increased during long-term treatment with UDCA as reflected by an increase in 7alpha-HCO serum concentrations from 39.7 +/- 21.3 ng/ml (median 32.8 ng/ml) before treatment to 64.0 +/- 30.4 ng/ml (median 77.5 ng/ml) at days 30-40 of UDCA treatment (p < 0.05).

CONCLUSIONS

UDCA treatment does not affect cholesterol synthesis in the liver, but does increase bile acid synthesis after prolonged treatment. This may represent a compensatory change following decreased absorption of endogenous bile acids as observed with UDCA therapy.

Effect of Pioglitazone on Lipids in Well Controlled Patients with Diabetes Mellitus Type 2 - Results of a Pilot Study

INTRODUCTION

Patients with diabetes mellitus type 2 are characterized by a typical dyslipoproteinemia. Improvement in glucose control usually also ameliorates this dyslipoproteinemia. It is unclear whether different antidiabetic strategies differ in their effects on the lipid profile. Particularly, it is unknown whether glitazones improve lipid values independently of their effects on glucose metabolism.

METHODS

Ten patients well controlled on sulfonylureas (HbA1c 6.9 +/- 0.5 %) with diabetic dyslipoproteinemia were treated with additional pioglitazone (30 mg/d) for 3 months. Every 4 weeks the sulfonylurea dose was adjusted to keep HbA1c and fasting glucose constant. Before and after 3 months of pioglitazone therapy lipid metabolism was determined in detail (cholesterol, triglyceride, LDL-cholesterol, HDL-cholesterol, VLDL-cholesterol, VLDL-triglycerides, lipoprotein(a), LDL-subtype distribution by isopycnic density gradient ultracentrifugation).

RESULTS

Although glucose control remained unchanged (HbA1c 6.9 +/- 0.5 % vs. 6.8 +/- 0.6 %; fasting glucose concentration 7.7 +/- 1.1 vs. 7.3 +/- 1.3 mmol/l) we observed a significant reduction in triglyceride concentration (1.9 +/- 0.6 vs. 1.4 +/- 0.5 mmol/l, - 26 %, p < 0.01), a significant increase in HDL-cholesterol concentration (1.2 +/- 0.2 vs. 1.4 +/- 0.2 mmol/l, + 14 %, p < 0.05), a significant decrease in LDL/HDL-ratio (3.03 +/- 0.77 vs. 2.51 +/- 0.61, - 24 %, p < 0.05) and non-significant improvements in total cholesterol, LDL-cholesterol, VLDL-triglycerides, and VLDL-cholesterol concentrations. The LDL-subtype profile improved (significant reduction [- 20 %] in small dense LDL).

CONCLUSIONS

This pilot study indicates that at comparable fasting glucose concentration and at comparable HbA1c value pioglitazone is superior to sulfonylureas concerning the improvement of diabetic dyslipoproteinemia. Whether this relates to indirect effects (improvement in insulin sensitivity) or direct effects (stimulation of PPARalpha) remains to be determined.

Effects of ezetimibe on plasma lipoproteins in severely hypercholesterolemic patients treated with regular LDL-apheresis and statins

Ezetimibe, a cholesterol absorption inhibitor, can be combined with statins to lower LDL-cholesterol. We evaluated additional ezetimibe (10 mg/day) in a placebo-controlled, double blind, randomized cross-over study in 20 patients (age 56+/-9 years, m:f 10:10, BMI 27.5+/-4.0 kg/m(2)) suffering from severe hypercholesterolemia and CHD who were treated by statins and regular LDL-apheresis. Lipoproteins (cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, VLDL-cholesterol, VLDL-triglycerides, lipoprotein(a)) were determined twice (before and during ezetimibe/placebo, each given for 5 weeks), dietary behaviour was analyzed once (3-days-protocol) during each treatment period. During ezetimibe the mean (+/-S.D.) preapheresis LDL-cholesterol concentration decreased from 159+/-26 mg/dl (4.11+/-0.67 mmol/l) to 133+/-28 mg/dl (3.44+/-0.72 mmol/l) (-16+/-11%, P<0.0001, Wilcoxon test) and the postapheresis LDL-cholesterol from 51+/-9 mg/dl (1.32+/-0.23 mmol/l) to 43+/-8 mg/dl (1.11+/-0.21 mmol/l) (-14+/-25%, P<0.05), while there was no significant change during placebo. Mean VLDL-cholesterol fell by 18+/-71% (P<0.05) during ezetimibe and was not significantly changed by placebo (+19+/-70%). Furthermore, during ezetimibe less plasma volume was treated (3725+/-1560 versus 3870+/-1549 ml, P<0.05). Ezetimibe had no effect on pre- and postapheresis triglyceride, HDL-cholesterol and lipoprotein(a) levels. The effect of ezetimibe was independent of the statin dose. Dietary behaviour did not change and no side effects were observed. Thus, in patients with severe LDL-hypercholesterolemia and CHD the addition of ezetimibe to intensive lipid lowering therapy (statins and LDL-apheresis) resulted in a further, clinically significant decrease of LDL-cholesterol.

In vivo metabolism of LDL subfractions in patients with heterozygous FH on statin therapy

LDL can be subfractionated into buoyant (1.020-1.029 g/ml(-1)), intermediate (1.030-1.040 g/ml(-1)), and dense (1.041-1.066 g/ml(-1)) LDLs. We studied the rebound of these LDL-subfractions after LDL apheresis in seven patients with heterozygous familial hypercholesterolemia (FH) regularly treated by apheresis (58 +/- 9 years, LDL-cholesterol = 342 +/- 87 mg/dl(-1), triglycerides = 109 +/- 39 mg/dl(-1)) and high-dose statins. Apolipoprotein B (apoB) concentrations were measured in LDL subfractions immediately after and on days 1, 2, 3, 5, and 7 after apheresis. Compartmental models were developed to test three hypotheses: 1) that dense LDLs are derived from the delipidation of buoyant and intermediate LDLs (model A); 2) that dense LDLs are generated directly from LDL-precursors (model B); or 3) that a model combining both pathways (model C) is necessary to describe the metabolism of dense LDLs. In all models, it was assumed that apoB production and fractional catabolic rate (FCR) did not change with apheresis. Apheresis decreased buoyant, intermediate, and dense LDL-apoB by 60 +/- 12%, 67 +/- 5%, and 69 +/- 11%, respectively. Models B and C, but not model A, described the rebound data. The model with the greatest biological plausibility (model C) was used to estimate metabolic parameters. FCR was 1.05 +/- 0.86 d(-1), 0.48 +/- 0.11 d(-1), and 0.69 +/- 0.24 d(-1) for buoyant, intermediate, and dense LDLs, respectively. Dense LDL production was 17.3 +/- 0.2 mg/kg(-1)/d(-1), 58% of which was derived directly from LDL precursors (VLDL, IDL, or direct secretion), while 42% was derived from buoyant and intermediate LDLs. Thus, our data indicate that in statin-treated patients with heterozygous FH dense LDLs originate from two sources. Whether this is also valid in other metabolic situations (with predominant small, dense LDLs) remains to be determined.

[A 32-year old male patient with pathological humeral fracture, splenomegaly and thrombocytopenia]

We describe the case of a 32-year old male patient who presented with a pathological fracture of his right humerus, splenomegaly and thrombocytopenia, the typical symptoms of Gaucher's disease, a lysosomal storage disease. Diagnosis was confirmed by bone marrow biopsy (detection of lipid engorged macrophages - Gaucher cells), by a markedly diminished activity of acid, beta-Glucosidase and by showing two different mutations (764T/A, 1187G/A) in the gene encoding acid beta-Glucosidase. The first mutation causes an amino-acid substitution (phenylalanine to tyrosine). The second mutation causes a premature termination at amino-acid position 396. Enzyme replacement therapy was started with 60 Units/kg body weight, because of severe bone symptoms. Following the decrease in spleen size and increase in platelet count the dose was gradually tapered to 20 U/kg. After two years of enzyme replacement therapy platelet count and spleen volume have normalized and the bone lesions have almost disappeared.

Long-term reduction of C-reactive protein concentration by regular LDL apheresis

BACKGROUND

Increased C-reactive protein (CRP) concentration is an independent risk predictor for coronary heart disease (CHD). A therapeutic reduction of CRP might, therefore, reduce the risk of cardiovascular events. A single LDL apheresis lowers LDL cholesterol by 45-70%, and CRP by 20-65%, however, less is known about the long-term effects of LDL apheresis on CRP levels.

METHODS

We investigated 34 CHD patients (20 males, 14 females, 52 +/- 10 years) on statin therapy who were regularly treated by LDL apheresis because of drug-resistant hypercholesterolemia. Measurements of CRP (ultrasensitive nephelometric assay) were performed before the first apheresis, before a current apheresis (1 or 2 weeks after the last apheresis), and after a current apheresis (treatment period: 5.3 +/- 4.2 years, range: 0.25-12.5 years). LDL apheresis was performed by immunoadsorption (n = 6), dextran sulfate adsorption (n = 13), heparin-induced extracorporal LDL precipitation (HELP, n = 9), or direct adsorption of lipoproteins (DALI, n = 6).

RESULTS

CRP was significantly lower before a current apheresis (median: 0.75 mg/l, range: 0.16-4.33 mg/l) compared to before the first apheresis (median: 0.85 mg/l, range: 0.16-7.02 mg/l; P < 0.05). As expected, total and LDL cholesterol were lower before a current apheresis compared to before the initial apheresis while fibrinogen concentration did not differ significantly.

CONCLUSION

Over the period of more than 5 years LDL apheresis slightly, but significantly reduced CRP concentrations in patients with CHD on statin therapy, which may contribute to the stabilization of atherosclerosis in hypercholesterolemic patients treated with LDL apheresis. These results are even more impressive when the known age-related increase in CRP over the treatment period is taken into account.

[Therapy of hyperlipoproteinemia in the elderly]

Atherosclerosis associated diseases are the major cause of mortality in men and women over 65 years. Although the epidemiological relationship between hypercholesterolemia and cardiovascular disease is less prominent in elderly than in younger patients, the results of numerous intervention trials show that risk reduction can also be achieved in elderly and old patients. The numbers needed to treat to prevent one cardiovascular event is usually lower in this age group because of the high absolute rate of events. Therefore, in secondary prevention settings these patients should be treated similar to younger patients, i.e. a LDL-cholesterol below 100 mg/dl should be achieved. In hyper- or dyslipoproteinemic patients without evidence of clinical or subclinical atherosclerosis cholesterol lowering drugs should be used restrictively.

Differential effects of fenofibrate versus atorvastatin on the concentrations of E-selectin and vascular cellular adhesion molecule-1 in patients with type 2 diabetes mellitus and mixed hyperlipoproteinemia: a randomized cross-over trial

Background

Diabetic dyslipoproteinemia is characterized by hypertriglyceridemia, low HDL-cholesterol and often elevated LDL-cholesterol and is a strong risk factor for atherosclerosis. Adhesion molecule levels are elevated both in hyperlipoproteinemia and diabetes mellitus. It is unclear whether fibrate or statin therapy has more beneficial effects on adhesion molecule concentrations.

Methods

Atorvastatin (10 mg/d) was compared to fenofibrate (200 mg/d) each for 6 weeks separated by a 6 week washout period in 11 patients (6 male, 5 female; 61.8 ± 8.2 years; body mass index 29.8 ± 3.1 kg/m²) with type 2 diabetes mellitus (HbA_1c 7.3 ± 1.1 %) and mixed hyperlipoproteinemia using a randomized, cross-over design. Fasting blood glucose, HbA₁c, lipid parameters, E-selectin, ICAM-1, VCAM-1, and fibrinogen concentrations were determined before and after each drug.

Results

Glucose and HbA₁c concentrations remained unchanged during the whole study period. LDL cholesterol was reduced during atorvastatin therapy, triglycerides were lowered more effectively with fenofibrate. Comparison of pre- and postreatment concentrations of E-selectin showed a reduction during atorvastatin (-7 %, p = 0.11) and fenofibrate (-10 %, p < 0.05) therapy. Atorvastatin treatment reduced VCAM-1 levels by 4% (p < 0.05), while VCAM-1 concentrations remained unchanged (+1%, ns) during fenofibate therapy. However, direct comparisons of post-treatment levels during both forms of therapy were not of statistical significance. ICAM-1 levels were not influenced by either form of therapy.

Conclusions

In addition to the different beneficial effects on lipid metabolism, both drugs appear to lower adhesion molecule plasma concentrations in a different manner in patients with type 2 diabetes and mixed hyperlipoproteinemia. Our observations should be confirmed in a larger cohort of such patients.

Efficacy and Safety of a New Whole-blood Low-density Lipoprotein Apheresis System (Liposorber D) in Severe Hypercholesterolemia

Low-density lipoprotein (LDL) apheresis is an extracorporeal modality to lower LDL cholesterol. While most of the devices eliminate LDL particles from plasma, a recently introduced whole-blood perfusion column (DALI) adsorbs lipoproteins directly from whole blood. We investigated the efficacy and safety of a new whole-blood LDL apheresis system (Liposorber D) in 10 patients with severe hypercholesterolemia in a multicenter trial. In 93 LDL aphereses, the mean reduction in LDL cholesterol and lipoprotein(a) was 62.2 +/- 11.5% and 55.6 +/- 16.9%, respectively (P < 0.01). If hemodilution during apheresis was considered, the reductions were 58.0 +/- 10.9 and 55.3 +/- 10.9%, respectively (P < 0.01), while high-density lipoprotein (HDL) cholesterol did not change significantly. Three mild episodes of hypocalcemia and two mild episodes of arterial hypotension were observed; however, LDL apheresis could be continued in each case. In conclusion, the new whole-blood LDL apheresis with Liposorber D is a safe, simple, and useful modality to reduce LDL cholesterol and lipoprotein(a) in cardiovascular high-risk patients.

Influence of Etofibrate on LDL-Subtype Distribution in Patients with Diabetic Dyslipoproteinemia

Low density lipoprotein (LDL-) particles can be subfractionated in large-buoyant (lb), intermediate-dense (id) and small-dense (sd) LDL-subtypes. Fibrates improve the LDL-subtype profile by reducing proatherogenic sd-LDL which are prominent in diabetic dyslipoproteinemia. We evaluated the effect of etofibrate on the LDL-subtype distribution in patients with type 2 diabetes mellitus (n = 13, 55 +/- 18 years, BMI 27.9 +/- 5.5 kg/m2, HbA1c 10.1 +/- 3.9 %) and diabetic dyslipoproteinemia (triglycerides 343 +/- 253 mg/dl, HDL-cholesterol 36 +/- 7 mg/dl, LDL-cholesterol 110 +/- 37 mg/dl). Plasma lipids (enzymatic methods) and LDL-subtypes (7 LDL-subfractions, density gradient ultracentrifugation) were measured before and during etofibrate therapy (500 mg/d, 7 - 16 weeks). Etofibrate significantly (p < 0.05, Wilcoxon-test) reduced triglycerides (- 31 +/- 60 %) and increased HDL-cholesterol (+ 24 +/- 22 %), whereas total cholesterol and LDL-cholesterol did not change. Cholesterol concentration decreased in sd-LDL by 12 % (p < 0.05), while it increased in id- and lb-LDL (+ 26 %,+ 39 %, respectively). Thus, the LDL-subtype profile showed a relative increase of the fraction of lb- (+ 13 +/- 32 %, n.s.) and id-LDL (+ 23 +/- 33 %, p < 0.05) and a relative decrease of the fraction of sd-LDL (- 19 +/- 18 %, p < 0.05). We conclude that etofibrate not only decreases triglycerides and increases HDL-cholesterol but also improves the LDL-subtype profile and thus may reduce the cardiovascular risk in patients with an abundance of sd-LDL such as diabetic patients.

Effect of atorvastatin on postprandial lipoprotein metabolism in hypertriglyceridemic patients

Postprandial lipoprotein metabolism is impaired in hypertriglyceridemia. It is unknown how and to what extent atorvastatin affects postprandial lipoprotein metabolism in hypertriglyceridemic patients. We evaluated the effect of 4 weeks of atorvastatin therapy (10 mg/day) on postprandial lipoprotein metabolism in 10 hypertriglyceridemic patients (age, 40 +/- 3 years; body mass index, 27 +/- 1 kg/m2; cholesterol, 5.74 +/- 0.34 mmol/l; triglycerides, 3.90 +/- 0.66 mmol/l; HDL-cholesterol, 0.85 +/- 0.05 mmol/l; and LDL-cholesterol, 3.18 +/- 0.23 mmol/l). Patients were randomized to be studied with or without atorvastatin therapy. Postprandial lipoprotein metabolism was evaluated with a standardized oral fat load. Plasma was obtained every 2 h for 14 h. Large triglyceride-rich lipoproteins (TRLs) (containing chylomicrons) and small TRLs (containing chylomicron remnants) were isolated by ultracentrifugation, and cholesterol, triglyceride, apolipoprotein B-100 (apoB-100), apoB-48, apoC-III, and retinyl-palmitate concentrations were determined. Atorvastatin significantly (P < 0.01) decreased fasting cholesterol (-27%), triglycerides (-43%), LDL-cholesterol (-28%), and apoB-100 (-31%), and increased HDL-cholesterol (+19%). Incremental area under the curve (AUC) significantly (P < 0.05) decreased for large TRL-cholesterol, -triglycerides, and -retinyl-palmitate, while none of the small TRL parameters changed. These findings contrast with the results in normolipidemic subjects, in which atorvastatin decreased the AUC for chylomicron remnants (small TRLs) but not for chylomicrons (large TRLs). We conclude that atorvastatin improves postprandial lipoprotein metabolism in addition to decreasing fasting lipid levels in hypertriglyceridemia. Such changes would be expected to improve the atherogenic profile.

Extracorporal low-density lipoprotein elimination by immunoadsorption

Low-density lipoprotein (LDL) apheresis has proven its therapeutic usefulness in patients who suffer from coronary heart disease but cannot achieve LDL cholesterol concentrations defined by the National Cholesterol Education Program guidelines. Immunoadsorption was the first commercially available apheresis technique. It is based on affinity chromatography. As with other apheresis techniques, immunoadsorption has specific advantages and disadvantages. These have to be taken into account when selecting an apheresis technique for the individual patient.

Effect of atorvastatin on lipid parameters, LDL subtype distribution, hemorrheological parameters and adhesion molecule concentrations in patients with hypertriglyceridemia

BACKGROUND AND AIM

Hypertriglyceridemia is a risk factor for atherosclerosis that is typically associated with high concentrations of adhesion molecules, impaired hemorrheology and an unfavourable low-density lipoprotein (LDL) subtype distribution. We hypothesised that some of these risk markers might be beneficially influenced by lipid-lowering therapy with atorvastatin in hypertriglyceridemic patients.

METHODS AND RESULTS

Nineteen patents with primary hypertriglyceridemia were given 10 mg of atorvastatin per day for four weeks. Their cholesterol, triglyceride, LDL and high-density lipoprotein cholesterol (HDL-C) levels, LDL subtype profile, hemorrheological parameters and E-selectin, vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 concentrations were measured before and at the end of atorvastatin therapy. The levels of total and LDL cholesterol respectively decreased by 25% and 24% (both p < 0.001). Furthermore, cholesterol was reduced by 8-29% in all seven LDL subfractions (density range: 1.020-1.066 g/mL) (p < 0.05). The reduction in triglyceride concentrations was of marginal significance (9%, p = 0.1), but its degree positively correlated with the reduction of small-dense LDL (r = 0.5, p < 0.025). Plasma viscosity and blood viscosity at low shear rates were respectively reduced by 2% and 16% (both p < 0.05). The effect of the treatment on the concentrations of HDL-C, fibrinogen and adhesion molecules was not significant.

CONCLUSIONS

Atorvastatin (10 mg/day) not only reduced the plasma concentrations of atherogenic lipoproteins but also improved the LDL-subtype profile and reduced plasma and blood viscosity in patients with hypertriglyceridemia; however, it failed to significantly lower triglyceride concentrations.