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M Nauck

Publications and source records attributed to M Nauck.

At least 19 recordsLinked to original sources
PubMed2006

Genotype-corrected reference values for serum angiotensin-converting enzyme.

The deletion (D)/insertion (I) polymorphism in intron 16 of the angiotensin-converting enzyme (ACE) gene has the greatest impact on serum ACE level in Caucasians of any factor yet discovered. The aim of the present study was to establish new ACE genotype-corrected normal ranges for serum ACE level in a population of central European origin. After a medical examination, 159 healthy Caucasians volunteered to donate blood for the study. ACE genotypes were assessed by PCR and serum ACE levels were determined using two different kinetic tests. The distribution of the D/I polymorphism of the ACE gene was in accordance with the Hardy-Weinberg equilibrium. Serum ACE levels and ACE genotypes correlated significantly, with the highest serum ACE levels in subjects with ACE genotype D/D, and the lowest serum ACE levels in subjects with genotype I/I (mean+/-sd, assay 1: D/D 59.3+/-15.1 U x L(-1), D/I 45.5+/-15.2 U x L(-1), I/I 34.8+/-13.7 U x L(-1); assay 2: D/D 43.7+/-14.1 U x L(-1), D/I 33.7+/-12.1 U x L(-1), I/I 25.4+/-9.5 U x L(-1)). Although they gave different absolute values of serum ACE levels, the results of the two test kits correlated significantly. In conclusion, the present authors recommend the use of new, genotype-specific reference values for serum angiotensin-converting enzyme levels, especially to improve the sensitivity and specificity of tests for angiotensin-converting enzyme in the follow-up of sarcoidosis.

Adolescent↗
PubMed2004

Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14 : 1) is not superior to thyroxine alone to improve well-being and cognitive performance in hypothyroidism.

OBJECTIVES: There is evidence from recent controlled clinical studies that replacement therapy of hypothyroidism with T4 in combination with a small amount of T3 may improve the well-being of the patients. As the issue is still the subject of controversial discussion, our study was assigned to confirm the superiority of a physiological combination of thyroid hormones (absorbed molar ratio 14 : 1) over T4 alone with regard to mood states and cognitive functioning. DESIGN AND PATIENTS: After a run-in period with the T4 study medication for 4 weeks, a controlled, randomized, double-blind, two-period (each 12 weeks), cross-over study without washout between the treatment periods was performed in 23 hypothyroid patients (three males, 20 females, age 23-69 years, 21 subjects after surgery/radioiodine, two with autoimmune thyroiditis) to compare the effects of the previous individual T4 dose (100-175 micro g) with a treatment in which 5% of the respective T4 dose was substituted by T3. MEASUREMENTS: Standard hormonal characteristics and standardized psychological tests to quantify mood and cognitive performance were measured after the run-in period and at the end of each treatment period. In 12 subjects, the concentration-time profiles of fT3 and fT4 were compared after the last administration of the respective study medication. TSH, fT3 and fT4 were measured with immunological assays. CLINICAL RESULTS: Replacement therapy with T4 and T4/T3 was not different in all steady-state hormonal, metabolic and cardiovascular characteristics except for TSH, which was more suppressed after T4/T3. The efficacy of replacement therapy with the T4/T3 combination was not different from the T4 monotherapy with regard to all psychological test scores describing mood and cognitive functioning of the patients. Mood was even significantly impaired by the T4/T3 combination in eight subjects, with TSH < 0.02 mU/l, compared to patients with normal TSH (Beck Depression Inventory: 8.25 +/- 5.01 vs. 4.07 +/- 5.60, P = 0.026). PHARMACOKINETIC RESULTS: The area under the concentration-time curve (AUC(0-8h)) of fT3 was significantly higher after T4/T3 compared to the T4 monotherapy (42.8 +/- 9.03 pmol x h/l vs. 36.3 +/- 8.50 pmol x h/l, P < 0.05) and was significantly correlated to serum TSH (r(s) = -0.609, P < 0.05). After T4/T3, patients with a history of Graves' disease or autoimmune thyroiditis had significantly higher serum trough levels of fT3 whereas the fT4 concentrations were significantly lower in patients with a nonautoimmune background. CONCLUSION: Replacement therapy of hypothyroidism with T4 plus T3 does not improve mood and cognitive performance compared to the standard T4 monotherapy. There is even a higher risk of signs of subclinical hyperthyroidism associated with impaired well-being of the patients, which is clearly caused by significant fluctuations in the steady-state fT3 serum concentrations.

Adult↗
PubMed2003

Haplotypes of the cholesteryl ester transfer protein gene predict lipid-modifying response to statin therapy.

Cholesteryl ester transfer protein (CETP) plays a central role in high-density lipoprotein (HDL) metabolism. Single nucleotide polymorphisms (SNPs) and haplotypes in the CETP gene were determined in 98 patients with untreated dyslipidemias and analyzed for associations with plasma CETP and plasma lipids before and during statin treatment. Individual CETP SNPs and haplotypes were both significantly associated with CETP enzyme mass and activity. However, only certain CETP haplotypes, but not individual SNPs, significantly predicted the magnitude of change in HDL cholesterol (HDL-C) and triglycerides. After adjusting for covariates and multiple testing, the TTCAAA haplotype showed a gene-dose effect in predicting the HDL-C increase (P=0.03), while the TTCAAAGGG and AAAGGG haplotypes predicted a decrease in triglycerides (P=0.04 both). This is the first study to demonstrate that SNP haplotypes derived from allelic SNP combinations in the CETP gene were more informative than single SNPs in predicting the response to lipid-modifying therapy with statins.

Aged↗
PubMed2003

Effects of one week juice fasting on lipid metabolism: a cohort study in healthy subjects.

OBJECTIVE: We investigated the effects of a popular modified juice fasting program on lipid metabolism. VOLUNTEERS AND METHODS: 5 healthy, nonobese, male volunteers fasted for 8 days. Daily energy intake was limited to 150-300 kcal/d solely as carbohydrates (vegetable and fruit drinks). Physical activity was maintained as before. At baseline, on days 2, 3, and 8 during fasting, and on days 2 and 8 after fasting, serum lipids, lipoproteins, and insulin were investigated. RESULTS: Juice fasting resulted in bi-phasic changes: Until day 2 and 3 triacylglycerols (TG), very low-density lipoprotein apolipoprotein B (VLDL apo B), and insulin decreased by 52, 51, and 65% respectively, while nonesterified fatty acids (NEFA), low-density lipoprotein (LDL) apo B, and LDL cholesterol increased by 363, 38, and 35%. Between day 3 and 8 NEFA increased; TG and insulin increased as well, but remained below baseline values, and LDL cholesterol normalized. After 8 days juice fasting significant changes (p < 0.05) compared to the baseline were found only for free cholesterol (-10%), phospholipids (-14%), apo AI (-9%), apo AII (-11%), insulin (-42%), C-peptide (-57%), and NEFA (+535%, p = 0.0001). Total cholesterol decreased by 9% (n.s.) after 8 days. One week after the ending of fasting all parameters returned to normal. CONCLUSION: Contrary to total fasting and fasting with limited physical activity, 8 days juice fasting without limitation of physical activity results in a decrease of free cholesterol and an only initial increase of LDL cholesterol. After 8 days insulin, TG, and VLDL are still lower than at baseline, however, they have increased compared to the initial phase, probably counterregulatory to a further increase of NEFA.

Adult↗
PubMed2001

Effect of atorvastatin, simvastatin, and lovastatin on the metabolism of cholesterol and triacylglycerides in HepG2 cells.

We evaluated the effects of the hydroxymethylglutaryl coenzyme A reductase inhibitors (HMGRI) atorvastatin, lovastatin, and simvastatin on lipid homeostasis in HepG2 cells. The drugs were almost equally effective in inhibiting cholesterol synthesis and in decreasing cellular cholesterol. Atorvastatin and lovastatin increased low-density lipoprotein receptor mRNA (2.5-fold at 3 x 10(-7) M) and the transcription rate at the promoter of the low-density lipoprotein receptor gene (>5-fold at 10(-6) M). The three compounds enhanced the activity of the low-density lipoprotein receptor at a similar magnitude (1.6-2.1- fold at 10(-6) M). Atorvastatin and lovastatin increased the nuclear form of sterol regulatory element binding protein (SREBP)-2, but not of SREBP-1. Each of the drugs increased triacylglyceride synthesis (50% at 10(-7)-10(-6) M), cellular triacylglyceride content (16% at 10(-6) M), and expression of fatty acid synthase by reporter gene and Northern blot analysis (2-fold and 2.7-fold at 10(-6) M and 3 x 10(-7) M, respectively). All compounds reduced the secretion of apo B (30% at 3 x 10(-7) M). HMGRI decreased the ratio of cholesterol to apo B in newly synthesised apo B containing particles by approximately 50% and increased the ratio of triacylglycerides to apo B by approximately 35%. We conclude that regulatory responses to HMGRI are mediated by SREBP-2 rather than by SREBP-1, that HMGRI oppositely affect the cellular cholesterol and triacylglyceride production, that HMGRI moderately decrease the release of apo B containing particles, but profoundly alter their composition, and that atorvastatin does not significantly differ from other HMGRI in these regards.

Anticholesteremic Agents↗
PubMed2001

The effect of anastrozole on the single-dose pharmacokinetics and anticoagulant activity of warfarin in healthy volunteers.

AIMS: The aims of this study were to determine the effects of the nonsteroidal, selective aromatase inhibitor, anastrozole, at steady-state concentrations, on the pharmacokinetics and pharmacodynamics of warfarin, and to assess whether or not anastrozole alone has any anticoagulant activity. METHODS: This was a randomized, double-blind, placebo-controlled, two-way crossover trial conducted at a single centre. The study comprised two treatment periods of 11 days, separated by a 3 week washout. Healthy male volunteers (n = 16, median age 28.5 years) were randomized to receive either anastrozole (7 mg loading dose on day 1, followed by 1 mg daily on days 2-11) in the first treatment period and placebo in the second treatment period, or vice versa. In addition to their randomized treatment, all volunteers received a single dose of 25 mg warfarin on day 3 of each treatment period. Blood samples for pharmacokinetic and pharmacodynamic assessment were taken at frequent intervals during each treatment period. The safety of volunteers was monitored throughout the study. RESULTS: Administration of anastrozole resulted in no clinically significant changes in the pharmacokinetics of either R- or S-warfarin compared with placebo for AUC (ng ml-1 h) (glsmean, R-warfarin; anastrozole 93619.9, placebo 91127.91, 95%CI 0.988-1.068; S-warfarin; anastrozole 57129.21, placebo 55676.34, 95%CI 0.979-1.076), CL/F (ml min-1) (glsmean, R-warfarin; anastrozole 2.23, placebo 2.29, 95%CI 0.937-1.012; S-warfarin; anastrozole 3.65, placebo 3.74, 95%CI 0.929-1.021) and t1/2 (h) (lsmean, R-warfarin; anastrozole 55.40, placebo 55.15, 95%CI-2.083-2.592; S-warfarin; anastrozole 39.38, placebo 40.98, 95%CI-6.189-2.996). In addition, anastrozole had no clinically significant effect on the pharmacodynamic effects of warfarin, as assessed 240 h after warfarin dosing by measurement of prothrombin time (s) (glsmean, anastrozole 11.56, placebo 11.31, 95%CI 0.987-1.059), thrombin time (s) (glsmean, anastrozole 19.06, placebo 18.75, 95%CI 0.980-1.054) activated partial thromboplastin time (s) (glsmean, anastrozole 29.94, placebo 29.74, 95%CI 0.968-1.047) and factor VII (%) (glsmean, anastrozole 97.81, placebo 107.26, 95%CI 0.821-1.012). Anastrozole alone had no effect on these indicators of the clotting process. CONCLUSIONS: Overall, there was no evidence to suggest that anastrozole has any clinically relevant effects on the pharmacokinetics of warfarin. Anastrozole had no effect on clotting mechanisms or on the pharmacodynamic activity of warfarin, as assessed by prothrombin time, thrombin time, activated partial thromboplastin time, and factor VII.

Adult↗
PubMed2001

Has blood glucose level measured on admission to hospital in a patient with acute pancreatitis any prognostic value?

BACKGROUND: Early detection of pancreatic necrosis allows better management of the disease. Contrast-enhanced computed tomography (CT) as the gold standard for detecting pancreatic necrosis is expensive. AIM OF THE STUDY: This study was to evaluate for the first time whether blood glucose estimation on hospital admission--a simple, cheap, readily available laboratory parameter--may detect pancreatic necrosis and have prognostic value in acute pancreatitis. METHODS: Single blood glucose estimation upon hospital admission was evaluated prospectively for detecting pancreatic necrosis and as a prognostic indicator. The study included 241 nondiabetic patients with a first attack of acute pancreatitis. All underwent CT within 72 h of admission. RESULTS: High blood glucose (> 125 mg/dl) correlated significantly with complex high clinical and biochemical prognostic scores (Ranson, Imrie), a high Balthazar score, pancreatic pseudocysts, and a long hospital stay, but not with organ failure, indication for artificial ventilation, dialysis, surgery, length of intensive care, and mortality. Pancreatic necrosis detection sensitivity of high blood glucose was 83%, specificity 49%, positive predictive value 28%, and negative predictive value 92%. CONCLUSION: A patient with normal blood glucose on admission is unlikely to have pancreatic necrosis. Contrast-enhanced CT would not be needed unless the patient fails to improve.

Acute Disease↗
PubMed2001

The Friedewald formula underestimates LDL cholesterol at low concentrations.

Due to recent advances in the treatment of hypercholesterolemia, low density lipoprotein (LDL) cholesterol concentrations below 2.6 mmol/l have become attainable. In general, LDL cholesterol is determined indirectly according to Friedewald. We examined the performance of the Friedewald formula at low concentrations of LDL cholesterol in comparison with a beta-quantification method. We analyzed 176 samples from individuals treated by LDL apheresis with a mean LDL cholesterol concentration of 3.07 mmol/l and found that the Friedewald formula underestimated LDL cholesterol with a bias of -18.5%, -14.5%, -7.3%, and -3.8% at mean LDL cholesterol levels of 1.58, 2.4, 3.49, and 4.67 mmol/l, respectively. Thus, the lower the LDL cholesterol concentration was, the greater the negative bias. We conclude that the Friedewald formula may not be reliable at low LDL cholesterol concentrations produced by LDL apheresis. This finding may also be of relevance to the monitoring of patients being treated with lipid lowering drugs.

Cholesterol, HDL↗
PubMed2001

Pre-analytical conditions affecting the determination of the plasma homocysteine concentration.

In the past decade, moderately elevated homocysteine concentration has achieved wide-spread recognition as an independent risk factor for vascular diseases, such as stroke and peripheral vascular disease, as well as for an impaired nutritional status. In general, EDTA plasma is used for the determination of homocysteine. However, from the pre-analytical point of view it is important, that, when plasma is not separated from blood cells within 30 minutes, homocysteine levels increase in samples significantly by about 10% per hour. This 10% increase is very important, because the normal range is between 5 and 15 micromol/l and moderately elevated homocysteine concentrations above 15 micromol/l may signify an increased risk of vascular disease. These preliminary cut-off points show that there is only a small difference between normal and moderately elevated homocysteine concentrations. Most blood samples are obtained outside the hospital, and in these cases homocysteine concentrations will be falsely elevated, if no precautions are taken, such as immediate centrifugation and separation of plasma and cells. This aspect is critical both for clinical studies and in patient care outside the hospital. But even in the hospital it is difficult to separate plasma and cells within 30 minutes. In the past, different approaches were adopted to solve this problem. Potential stabilisers were sodium fluoride (4 g/l) and 3-deazaadenosine (100 micromol/l). Sodium fluoride initially increased the homocysteine concentration, which dropped below the initial values after 72 h. On the other hand, 3-deazaadenosine stabilised homocysteine concentrations for 24 h, but increased it within 72 h by roughly 10%. However, this stabiliser is restricted to HPLC technology but does not work reliably with immunoassays. Lysis of blood stabilised homocysteine, but homocysteine concentrations were systematically lower requiring totally new reference ranges. In addition, acidic citrate (0.5 mol/l) was evaluated, which seems to stabilise plasma homocysteine concentrations at ambient temperatures for several hours. However, small but systematic deviations at baseline are observed. This stabilisation procedure does not interfere with immunoassays. Because immunoassays will be the future method of choice for robust and easy to perform homocysteine measurements, because they easily allow the analyses of high sample numbers, homocysteine stabilisation in whole blood is still an important matter. It must be solved before homocysteine determinations are introduced as a general screening for vascular risk factors in non-specialist laboratories.

Chemistry, Clinical↗
PubMed2001

Evolution of methods for measurement of HDL-cholesterol: from ultracentrifugation to homogeneous assays.

BACKGROUND: Adoption of automated homogeneous assays for HDL-cholesterol (HDL-C) is increasing, driven by the need of clinical laboratories to cope with increasing workloads while containing costs. However, performance characteristics of homogeneous assays often differ in important aspects from those of the earlier precipitation methods. This review provides an overview of the new generation of homogeneous assays for HDL-C within the historical context of the evolution of methods and the efforts to standardize measurements of the lipoproteins. APPROACH: This is a narrative review based on method evaluations conducted in the laboratories of the authors as well as on relevant publications, especially comparative evaluation studies, from the literature. Publications considered here have been collected by the authors over the past 30 years of involvement as methods for HDL-C made the transition from their early use in lipid research laboratories to clinical laboratories and the recent emergence of homogeneous assays. CONTENT: The presentation includes descriptions of methodologies, including homogeneous, precipitation, electrophoresis, and ultracentrifugation assays. Reference methods and recommended approaches for assessing accuracy are described. Accuracy and imprecision are summarized in the context of the National Cholesterol Education Program (NCEP) standards for analytical performance. The effects of interfering substances and preanalytical sources of variation are presented. SUMMARY: Homogeneous assays have been shown to be reasonably well suited for use in routine clinical laboratories, generally meeting the NCEP criteria for precision, accuracy, and total error. However, discrepant results compared with the reference methods have been observed with some of the assays, and the sources of discrepancies are not well characterized. Some homogeneous reagents have not been thoroughly evaluated. At least three of the reagents have experienced successive adjustments in formulation; hence, the reagents may not yet be fully optimized. For these reasons, the homogeneous assays cannot be confidently recommended for use in long-term clinical trials and other research applications without thorough validation.

Chemical Precipitation↗
PubMed2001

Cigarette smoking is independently associated with markers of endothelial dysfunction and hyperinsulinaemia in nondiabetic individuals with coronary artery disease.

BACKGROUND: Oxidative stress and endothelial dysfunction have been introduced as a unifying pathological mechanism for early atherosclerotic disease. They are caused by a variety of stimuli including cigarette smoking (environmental) and type 2 diabetes (disease factor). However, the role of hyperinsulinemia, a marker of insulin resistance, as a risk factor for atherosclerosis remains to be clarified. STUDY OBJECTIVES: To study the relationship of smoking, hyperinsulinaemia and biochemical markers of oxidative stress and endothelial dysfunction, in patients with coronary artery disease. DESIGN: Case-control study of 5-year survivor status in smokers, former smokers and nonsmokers with angiographically documented stable coronary artery disease classified by self-reporting of smoking status together with plasma cotinine measurements. SETTING: Cardiology and cardiac surgery unit of a tertiary care referral centre. PATIENTS AND METHODS: Plasma levels of vitamins C, E and selenium, and the adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were assessed in 214 patients at baseline together with the glucose and insulin response to an oral glucose challenge. Sixty known or newly diagnosed type 2 diabetic patients (28%) were identified and excluded from further analysis. RESULTS: E-selectin and ICAM-1, serving as markers of endothelial dysfunction, significantly correlated with hyperinsulinaemia (p < 0.05). Circulating immunoreactive insulin was elevated in active smokers and former smokers as compared to non-smokers after an oral glucose load (p < 0.05 for the area under the insulin time curve), despite a similar glucose response. Smoking was associated with a decrease in antioxidant vitamins C (p = 0.02) and E (p = 0.03), and an increase of E-selectin (p < 0.05) and ICAM-1 (p < 0.001). Low baseline ICAM-1 and high vitamin C levels emerged as the most significant multivariate predictors of 5-year survival (p < 0.001). CONCLUSIONS: Hyperinsulinaemia in smokers is linked with markers of endothelial dysfunction. Impaired vascular reactivity can thus be a new possible mechanism linking insulin resistance and smoking.

Biomarkers↗
PubMed2000

The molecular mechanisms of inherited thrombophilia.

Venous Thromboembolism develops as the result of multiple interactions between non-genetic and genetic risk factors. The most important non-genetic risk factors are age, tissue damage, oral contraception, pregnancy, obesity and lack of physical activity. Inborn factors predisposing to thrombosis are present in the majority of patients. These comprise defects affecting the anticoagulant pathways of blood coagulation like antithrombin III, protein C and protein S. Together these defects are found in 15-20% of thrombophilia families. The relatively rare defects of antithrombin III, protein C and protein S stand in contrast to two common genetic polymorphisms of procoagulant molecules, factor V-Leiden, the most frequent cause for resistance to activated protein C, and the prothrombin 20210 A allele. Together, these anomalies are found in almost two third of the thrombophilia families. The identification of factor FV-Leiden and prothrombin 20210 A has allowed to examine in detail interactions between genetic and non-genetic risk factors of thromboembolism. The results of these studies indicate that many symptomatic individuals are endowed with more than one (genetic and/or environmental) risk factor. Thrombophilia thus represents an oligogenetic rather than monogenetic clinical phenotype, the expression of which is amplified by circumstantial risk factors. As a consequence of the "multiple hit" concept, the laboratory screening of thrombosis patients needs to include all of the known genetic risk factors even if the "clinical" situation seemingly provides sufficient "explanation" for a thrombotic event.

Activated Protein C Resistance↗
PubMed2000

Analytical performance and clinical efficacy of three routine procedures for LDL cholesterol measurement compared with the ultracentrifugation-dextran sulfate-Mg(2+) method.

The diagnosis and management of adults with hypercholesterolemia in the US are largely based on low-density lipoprotein cholesterol (LDL-C) concentration. In order to classify someone correctly into the National Cholesterol Education Program cut-points, LDL-C must be measured with a total error of </=12%. We examined simultaneously the analytical and clinical performance of two homogeneous LDL-C assays (LDL-C(RD), Roche Diagnostics and LDL-C(GZ), Genzyme) and the Friedewald calculation (LDL-C(Fried)). These assays correlated highly with the ultracentrifugation-dextran sulfate-Mg(2+) method (LDL-C(RD): r=0.962, y=1.029x-0.48 mmol/l, n=134; LDL-C(GZ): r=0.961, y=0.986x-0.12 mmol/l, n=134; LDL-C(Fried): r=0.960, y=1.017x-0.18 mmol/l, n=115). The total error requirement was met by the LDL-C(GZ) assay at all clinical decision cut-points, whereas the LDL-C(RD) assay met this requirement only at LDL-C concentrations of 4.92 mmol/l. The LDL-C(Fried) failed to meet the total error requirement, because the compounded imprecision of the three independent tests required for this calculation was high. Both, the LDL-C(GZ) and the LDL-C(RD) assays appeared to be only slightly affected by increasing triglycerides. At the medical decision cut-point range, the LDL-C(RD), LDL-C(GZ) and LDL-C(Fried) assays showed positive predictive values of 89-100, 85-100 and 83-99%, respectively, and negative predictive values of 52-98, 77-98 and 68-98%, respectively. The homogeneous assays provide clinical laboratories with the means to measure LDL-C in hypertriglyceridemic samples and could have a role in the diagnosis and management of hyperlipidemic patients.

Adult↗
PubMed2000

The effects of lifibrol (K12.148) on the cholesterol metabolism of cultured cells: evidence for sterol independent stimulation of the LDL receptor pathway.

Lifibrol (4-(4'-tert. butylphenyl)-1-(4'-carboxyphenoxy)-2-butanol) is a new hypocholesterolemic compound; it effectively lowers low density lipoprotein (LDL) cholesterol. We studied the effects of lifibrol on the cholesterol metabolism of cultured cells. In the hepatoma cell line HepG2, Lifibrol decreased the formation of sterols from [14C]-acetic acid by approximately 25%. Similar to lovastatin, lifibrol had no effect on the synthesis of sterols from [14C]-mevalonic acid. Lifibrol did not inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. Instead, cholesterol synthesis inhibition by lifibrol was entirely accounted for by competitive inhibition of HMG-CoA synthase. Lifibrol enhanced the cellular binding, uptake, and degradation of LDL in cultured cells in a dose dependent fashion. The stimulation of LDL receptors was significantly stronger than expected from the effect of lifibrol on sterol synthesis. In parallel, lifibrol increased the amount of immunologically detectable receptor protein. Stimulation of LDL receptor mediated endocytosis was observed both in the presence and in the absence of cholesterol-containing lipoproteins. In the absence of an extracellular source of cholesterol, both lifibrol and lovastatin induced microsomal HMG-CoA reductase. Co-incubation with LDL was sufficient to suppress the lifibrol mediated increase in reductase activity, indicating that lifibrol does not affect the production of the non-sterol derivative(s) which are thought to regulate HMG-CoA reductase activity at the post-transcriptional level. Considered together, the data suggest that the hypolipidemic action of lifibrol may, at least in part, be mediated by sterol-independent stimulation of the LDL receptor pathway. A potential advantage of lifibrol is that therapeutic concentrations do not interfere with the production of mevalonate which is required not only to synthesize sterols but also as a precursor of electron transport moieties, glycoproteins and farnesylated proteins.

Anticholesteremic Agents↗
PubMed2000

Lack of germline mutations in the preproglucagon gene region coding for glucagon-like peptide 1 in Type 2 diabetic (NIDDM) patients.

Glucagon-like peptide 1 (GLP-1) has antidiabetic effects and many facets of Type 2 diabetes could theoretically be the consequence of a reduction in or lack of GLP-1 function. Exogenous GLP-1 is exquisitely effective in Type 2 diabetic patients, making receptor defects unlikely. GLP-1 responses after meals as detected by radioimmunoassay are not overtly reduced in Type 2 diabetic patients. Therefore, a sequence analysis of exon 2 of the preproglucagon gene coding for the GLP-1 protein was initiated in order to exclude potential germline mutations. 24 Type 2 diabetic patients and in 14 control subjects with normal oral glucose tolerance (WHO criteria) were studied. In all specimens of peripheral blood leukocyte DNA examined, no germline mutations of the GLP-1 sequence were identified, thus excluding mutations in the GLP-1 sequence as a major contributor to the pathophysiological appearance of the Type 2 diabetic phenotype. Rare mutations, however, cannot be excluded due to the small number of Type 2 diabetic patients examined.

Aged↗