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H Wieland

Publications and source records attributed to H Wieland.

At least 19 recordsLinked to original sources
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

Fluvastatin lowers atherogenic dense low-density lipoproteins in postmenopausal women with the atherogenic lipoprotein phenotype.

BACKGROUND: Although HMG-CoA reductase inhibitors (HMGRIs) are effective lipid-lowering agents, it remains controversial whether these agents also lower dense LDL (dLDL), a predominance of which is considered to contribute to the atherogenicity of the metabolic syndrome. METHODS AND RESULTS: In a multicenter, double-blind, randomized, placebo-controlled study, we determined the effect of the HMGRI fluvastatin on lipids, apolipoproteins, and LDL subfractions (by equilibrium density gradient ultracentrifugation). A total of 52 postmenopausal women with combined hyperlipidemia and increased dLDL were treated with either fluvastatin 40 mg/d (n=35) or placebo (n=17). After 12 weeks' treatment, significant reductions (P<0.001) in total cholesterol (-19%), IDL cholesterol (-35%), LDL cholesterol (-23%), apolipoprotein B (-21%), and apolipoprotein B in dLDL (-42%) were apparent among fluvastatin recipients. No significant changes in triglycerides or HDL cholesterol were observed. The effect of fluvastatin on dLDL was correlated with baseline values. There was no consistent relationship, however, between the effect of fluvastatin on triglycerides and the decrease in dLDL. CONCLUSIONS: Fluvastatin lowers total and LDL cholesterol and the concentration of dLDL. This profile may contribute to an antiatherogenic effect for fluvastatin that is greater than expected on the basis of changes in lipids and apolipoproteins.

Anticholesteremic Agents↗
PubMed2001

Identification of recurrent and novel mutations in the LDL receptor gene in German patients with familial hypercholesterolemia.

In order to identify mutations in the low density lipoprotein receptor (LDLR) gene in primary hypercholesterolemia, we screened 100 unrelated German individuals with elevated plasma LDL-C (LDL-C > 4,7 mmol/l) for mutations in the 18 exons and their flanking intronic sequences including the promoter region of the LDL-R gene using a combination of polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct sequencing. In addition we tested all patients for the presence of mutations in codons 3456 - 3553 of the gene encoding apolipoprotein B-100. In 56 individuals we detected 37 different mutations affecting the LDL-R gene, 16 of which, designated C122R, C127Y, C163W, F179L, R236W, E296X, R553C, V618D, T721I, V785D, G1358+2A, 257delTCTGGAGGT, 657delC, 676insACGGTATGGACTGCAdelGACG, C1205delTCT, 2420delTCCTTCT, have not yet been reported. One proband was a compound heterozygote showing two separate sequence variations (E207X and T705I). Seven patients were heterozygous for the mutation R3500Q within the apoB-100 gene. These results demonstrate that there is a broad spectrum of mutations in the LDL-R gene and that the R3500Q mutation is a frequent cause of hypercholesterolemia in the German population.

Adolescent↗
PubMed2001

An affordable, portable fluorescence imaging device for skin lesion detection using a dual wavelength approach for image contrast enhancement and aminolaevulinic acid-induced protoporphyrin IX. Part I. Design, spectral and spatial characteristics.

Steady-state fluorescence imaging can be used in conjunction with selective exogenous or endogenous fluorescent compounds for the diagnosis of skin lesions, for example cancerous lesions. Depending on the excitation and emission properties of the fluorescent compound used, various excitation and/or emission wavelengths can be chosen in order to allow fluorescence imaging. Unwanted background signals like autofluorescence and scattering can decrease the image quality and hence the diagnosis potential of this imaging method. A method involving two excitation and/or emission wavelengths was used in order to suppress the unwanted background signal and allow contrast enhanced fluorescence imaging. A fluorescence imaging device prototype was assembled using both the two wavelength excitation method and the two wavelength emission method. Additionally, a white light source was included to allow the collection of images as seen with the naked eye. The prototype was designed to be affordable and portable and was laid out towards the diagnosis of skin lesions using aminolaevulinic acid-induced protoporphyrin IX (PpIX). This paper describes the excitation and detection characteristics of a fluorescence imaging device prototype. This includes spectral and spatial characteristics of the various light sources included in the device as well as specifications of the image detector used. Furthermore, the image analysis procedure used for the dual wavelength excitation/emission is described.

Aminolevulinic Acid↗
PubMed2001

Apolipoprotein E1 Baden (Arg(180)-->Cys). A new apolipoprotein E variant associated with hypertriglyceridemia.

Apolipoprotein (apo) E mediates the removal of chylomicron and very low density lipoprotein remnants from plasma. It is polymorphic in sequence and the products of the three common alleles (epsilon 2, epsilon 3, epsilon 4) differ from one another in their binding to lipoprotein receptors. ApoE2 is defective in binding and homozygosity for apoE2 is associated with type III hyperlipoproteinemia (HLP). Other rare isoforms of apoE have been found to be associated either with dominant type III HLP or with the development of hypertriglyceridemia. We identified a 42 year-old hypertriglyceridemic woman with an apoE phenotype 3/1. Restriction isotyping using AflIII/HaeII resulted in an apparent apoE genotype 3/2, suggesting that the mutation occurred in an epsilon 2 allele. DNA sequence analysis revealed a C-->T point mutation at the first position of the codon for amino acid residue 180 of the mature apoE. This predicted a change Arg(180)-->Cys. The mutation altered a recognition site for the endonuclease HaeII, which allowed us rapidly to screen for this mutation. In relatives of the proband, apoE1 Baden was consistently associated with hypertriglyceridemia. Similar to other apoE variants linked to hypertriglyceridemia, the Arg(180)-->Cys mutation is located within the lipid binding domain of apoE. We therefore suggest that apoE1 Baden may cause hypertrigylceridemia, possibly by inhibiting the hydrolysis of triglycerides associated with very low density lipoproteins.

Adult↗
PubMed2001

Cord blood levels of interleukin-6 and interleukin-8 for the immediate diagnosis of early-onset infection in premature infants.

BACKGROUND: Cytokine plasma levels are suggested to be sensitive indicators of neonatal sepsis, but conventional assays are time consuming. This study aimed at evaluating the significance of cord blood levels of interleukin (IL)-6 and IL-8 determined by a fully automated random access assay within 90 min of admission to predict systemic bacterial infection. PATIENTS AND METHODS: Cord blood levels of IL-6 and IL-8 were determined in 71 mature and 100 premature infants by a chemiluminescence assay (Immulite). Patients were divided into four groups according to a clinical and laboratory scoring system. Group A: documented early-onset infection; group B: infection possible; group C: infection unlikely, and group D: healthy newborns. RESULTS: Median IL-6 levels in the subgroup of premature newborns were as follows: group A, 1,920 pg/ml (5-95% confidence interval 308-4,660 pg/ml); group B, 50 (15-102) pg/ml; group C, 21 (12-71) pg/ml, and group D, 8 (6-11) pg/ml. For IL-8, median levels for groups A-D were 289 (226-514) pg/ml, 87 (40-107) pg/ml, 44 (33-98) pg/ml and 21 (16-25) pg/ml, respectively. The difference between group A and the other groups was highly significant (IL-6 p < 0.0001, IL-8 p < 0.001). At a cut-off of 80 pg/ml, the sensitivity of IL-6 for the diagnosis of sepsis was 96% (specificity 95%). For IL-8 (cut-off 90 pg/ml), the sensitivity was 87% (specificity 94%). CONCLUSION: In premature infants, the diagnosis of an early-onset infection can be established or ruled out with a high level of confidence by measuring IL-6 or IL-8 levels from cord blood using a random access chemiluminescence assay.

Apgar Score↗
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

The significance of genetic polymorphisms in modulating the response to lipid-lowering drugs.

The response to lipid-lowering drugs is modified by a number of factors like age, gender, concomitant disease and genetic determinants. Even within homogenous groups of patients, individual responses vary greatly. Until now, no clinical or biochemical parameter exists which predicts whether a subject will respond well to a particular lipid-lowering drug or, in the extreme case, will develop adverse, life-threatening effects (e.g., myositis or rhabdomyolysis). The recent advances in the human genome project promises to have a great impact on our understanding of lipid and lipoprotein metabolism and of the individual response to lipid-lowering drugs. Monogenetic disorders of the lipid metabolism produce severe clinical phenotypes, such as Tangier disease, but have a minor role in the evaluation of cardiovascular risk in the general population. On the other hand, several polymorphisms in genes involved in lipoprotein metabolism (e.g., apolipoprotein E) are associated with the plasma levels of lipoproteins, explaining a substantial fraction of the variance of LDL or HDL concentrations. In combination, the knowledge of these polymorphisms, further variants yet to be discovered and variants within the genes involved in the metabolism of lipid-lowering drugs will in the future allow these drugs to be selected according to the patients needs and thus increase both efficacy and cost-effectiveness of lipid-lowering regimes.

Animals↗
PubMed2000

Characterization of a new electrophoretically silent hemoglobin variant. Hb saale OR alpha 2beta 2 84(EF8)Thr --> Ala.

A new abnormal hemoglobin was detected in a young German anemic patient by cation-exchange high performance liquid chromatography (HPLC). Using a combination of electrospray mass spectrometry, HPLC, direct sequencing, and family screening with polymerase chain reaction/restriction digestion approach, we have characterized this hemoglobin variant as resulting from a Thr --> Ala replacement at beta84(EF8). It could be separated neither by electrophoresis nor by isoelectric focusing. Hb Saale is slightly unstable, exhibiting a moderate tendency to auto-oxidize. Functional properties and the heterotropic interactions are similar to those of Hb A.

Adult↗
PubMed2000

HMG-CoA reductase inhibition: anti-inflammatory effects beyond lipid lowering?

Atherosclerosis has many features of a chronic inflammatory disease. Atherosclerotic lesions contain inflammatory cells like activated T-lymphocytes and macrophages. Systemic markers of inflammation such as white blood cells, C-reactive protein, serum amyloid A, interleukin 6 and soluble adhesion molecules are predictive of future cardiovascular events, even after adjustment for the contribution of established cardiovascular risk factors. Atherogenic lipoprotein particles, in particular modified low-density lipoproteins (LDL), elicit pro-inflammatory responses of cellular elements of the vessel wall, including endothelial dysfunction and activation of monocyte-derived macrophages. Treatment, with HMG-CoA reductase inhibitors has proven the most successful strategy to reduce the concentration of LDL in the circulatory system. These compounds lower LDL cholesterol by inhibiting the mevalonate pathway in the liver, which in turn depletes the regulatory pool of cholesterol and enhances the activity of LDL receptors. Five prospective clinical trials have convincingly demonstrated that HMG-CoA reductase inhibitors can effectively lower the incidence of cardiovascular events in primary and secondary prevention. Post hoc analyses of these trials suggest that the clinical benefit brought about by HMG-CoA reductase inhibitors may not entirely be due to their effect on the levels of circulating lipoproteins. In-vitro observations of anti-inflammatory actions of HMG-CoA reductase inhibitors on vascular cells have been suggested to explain effects beyond lipid-lowering. It is, however, not clear whether these findings are relevant to the in-vivo situation. Further investigation is now necessary in order to determine the relative significance of cholesterol lowering and of ancillary effects to the overall clinical benefit of statin treatment.

Anti-Inflammatory Agents↗
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

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

HDL steady state levels are not affected, but HDL apoA-I turnover is enhanced by Lifibrol in patients with hypercholesterolemia and mixed hyperlipidemia.

Lifibrol (4-(4'-tert-butylphenyl)-1-(4'carboxyphenoxy)-2-butanol) is a new hypocholesterolemic drug effectively reducing total cholesterol, LDL cholesterol, and apolipoprotein (apo) B in experimental animals and in humans. In contrast to fibrates and HMG-CoA reductase inhibitors the cholesterol and triglyceride lowering effect of Lifibrol is not accompanied by increases in HDL cholesterol and apoA-I levels. We examined the impact of Lifibrol on the metabolism of HDL apoA-I in patients with hyperlipoproteinemia, using endogenous labeling with stable isotopes. Kinetic studies were performed in five male hypercholesterolemic individuals (type IIa), before and on treatment with 450 mg of Lifibrol daily for 4 weeks and in five male individuals suffering from mixed hyperlipidemia (type IIb), before and on therapy, for 12 weeks. Lifibrol reduced total cholesterol by 14% (P=0.02) and LDL cholesterol by 16% (P=0. 014) in all patients, and decreased triglycerides by 34% in type IIb patients. During Lifibrol therapy, HDL cholesterol and ApoA-I concentrations did not change. Tracer kinetics revealed that the fractional catabolic rate (FCR) of HDL apoA-I increased by 22% (P=0. 013). This increase in the apoA-I FCR was accompanied by a 23% increase in HDL apoA-I production rate (P=0.006). We conclude that Lifibrol, although not changing HDL steady state concentrations, enhances the turnover of apoA-I containing HDL particles.

Adult↗
PubMed2000

FH-Freiburg: a novel missense mutation (C317Y) in growth factor repeat A of the low density lipoprotein receptor gene in a German patient with homozygous familial hypercholesterolemia.

We describe the characterization of a novel mutation in the low density lipoprotein receptor (LDL-R) gene in a patient with true homozygous familial hypercholesterolemia (FH). The combined use of denaturing gradient gel electrophoresis (DGGE) and sequencing of genomic DNA revealed a guanine to adenine base substitution at nucleotide position 1013 of the LDL-R cDNA. This point mutation results in a change from cysteine to tyrosine at amino acid residue 317 of repeat A of the epidermal growth factor (EGF) precursor homology domain. Binding, uptake and degradation of iodinated LDL in skin fibroblasts from the homozygous patient were less than 10% of normal. In contrast, binding, uptake and degradation of iodinated VLDL was reduced by only 60, 30, and 38%, respectively. Incubation of the patient's fibroblasts in the presence of cholesterol diminished the residual binding of VLDL by 50%, suggesting that the loss of the highly conserved cysteine at position 317 results in a LDL-R that fails to bind LDL, but retains some ability to bind VLDL by interacting with the apolipoprotein E. Both parents were heterozygous for the C317Y mutation. Interestingly, however, the father presented with markedly elevated levels of triglycerides and VLDL cholesterol, whereas his LDL cholesterol was unexpectedly low. The mother of the index patient had only slightly elevated LDL cholesterol. These observations testify to the biological complexity of genotype-environment interactions in individuals carrying mutations at the LDL-R locus and indicate that genetic analysis importantly complements the clinical and biochemical diagnosis of patients with hyperlipidemia.

Adolescent↗
PubMed2000

Cholesterol efflux from normal and Tangier disease fibroblasts into normal, high-density lipoprotein-deficient, and apolipoprotein E-deficient plasmas.

Tangier disease (TD) fibroblasts have defective cholesterol release in the presence of lipid-free apolipoproteins. We compared normolipidemic probands and patients with apolipoprotein A-I (apoA-I) deficiency, apoE deficiency, or TD in terms of the plasma capacity to induce the efflux of [3H]-cholesterol from normal and TD fibroblasts and to esterify this cell-derived cholesterol. Compared with normal fibroblasts, TD fibroblasts released a significantly smaller fraction of [3H]-cholesterol into normal, high-density lipoprotein (HDL)-deficient, and apoE-deficient plasmas. Supplementation of apoE-deficient plasma with exogenous apoE normalized the cholesterol efflux from normal cells but did not fully restore the reduced cholesterol efflux from TD fibroblasts. Compared with control plasma, HDL- and apoE-deficient plasmas had a significantly reduced activity to esterify cell-derived cholesterol. Cholesterol derived from TD fibroblasts was less available for esterification in either patient or normal plasmas than cholesterol derived from normal cells. The esterification defect of TD cell-derived cholesterol was more pronounced in patient plasmas than in control plasma. We conclude that (1) apoA-I and, to a lesser degree, apoE are important determinants of the cholesterol efflux and esterification capacity of plasma, (2) TD fibroblasts have a reduced capacity to release cholesterol into the plasma, and (3) TD cell-derived cholesterol is less available for esterification in plasma than cholesterol from normal fibroblasts. The absence of distinct apoA-I- or apoE-containing subclasses aggravates the defective efflux and esterification of cholesterol derived from TD cells.

Adult↗