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D Neumeier

Publications and source records attributed to D Neumeier.

At least 37 records · Page 2Linked to original sources
PubMed1997

Quantification of the neuromuscular blocking agent rocuronium and its putative metabolite 17-desacetylrocuronium in heparinized plasma by capillary gas chromatography using a nitrogen sensitive detector.

We have developed a sensitive and specific capillary GC (cGC) assay for the quantification of the quarternary aminosteroidal compound rocuronium (roc), a neuromuscular blocking agent, and its putative metabolite 17-desacetylrocuronium (17OH-roc), using 3-desacetylvecuronium (3OH-vec) as an internal standard (I.S.). This novel method has been applied to a pharmacokinetic study with roc, monitoring sixty patients who were classified according to four different body mass index (BMI) groups. The isolation of these drugs from plasma was carried out using a dichloromethane liquid-liquid extraction after ion-pairing of the positively charged ammonium compounds with iodide. To achieve thermal stability, tert.-butyldimethylsilyl-ethers were formed at the 3OH- and 17OH-steroidal positions by reaction with N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide at 70 degrees C overnight. An automated cGC system fitted with a nitrogen sensitive detector with a specially prepared glass phase bead and a computer controlled data handling system was used to analyze and quantify the compounds, which were separated on a DB1 capillary column with helium as the carrier gas and a temperature program ranging from 120 to 300 degrees C. The method is linear for 50-6400 ng/ml for roc and 80-6400 ng/ml for 17OH-roc. The detection limits were 10 ng/ml for roc and 50 ng/ml for 17OH-roc. The lower limit of quantification was 50 ng/ml for roc and 80 ng/ml for 17OH-roc. Intra-assay coefficients of variation (C.V.s) were 10% and 15% and the inter-assay C.V.s 8-18% and 16-21% for roc and 17OH-roc, respectively.

Androstanols↗
PubMed1997

Role of nuclear factor-kappa B in atherogenesis.

Transcription factors of the nuclear factor-kappa B (NF-kappa B)/Rel family have an important function in the regulation of a variety of genes involved in the inflammatory and proliferative responses of cells. Recent studies strongly indicate that the inducible transcription factor NF-kappa B is involved in the pathogenesis of atherosclerosis. Activated NF-kappa B is present in the fibrotic thickened intima-media and atheromatous areas of the atherosclerotic lesion, within smooth muscle cells, macrophages and endothelial cells, whereas little or no activated NF-kappa B can be detected in vessels lacking atherosclerosis. A variety of molecules have been identified in the atherosclerotic environment that are able to activate NF-kappa B in vitro. Furthermore, an increased expression of numerous genes known to be regulated by NF-kappa B has been found in the atherosclerotic lesion. Possible functional implications for activated NF-kappa B in atherogenesis are discussed here. The activation and role of NF-kappa B in atherosclerosis may provide a model for the involvement of the transcription factor in human chronic inflammatory disease.

Animals↗
PubMed1997

Dysregulation of monocytic nuclear factor-kappa B by oxidized low-density lipoprotein.

Nuclear factor-kappa B (NF-kappa B)/Rel transcription factors may be involved in atherosclerosis, as is suggested by the presence of activated NF-kappa B in human atherosclerotic lesions. The aim of the present study was to investigate the effects of oxidized LDL (oxLDL) on the NF-kappa B system in human THP-1 monocytic cells as well as adherent monocytes. Our results demonstrate that short-term incubation of these cells with oxLDL activated p50/p65 containing NF-kappa B dimers and induced the expression of the target gene IL-8. This activation of NF-kappa B was inhibited by the antioxidant and H2O2 scavenger pyrrolidine dithiocarbamate and the proteasome inhibitor PSI. The oxLDL-induced NF-kappa B activation was accompanied by an initial depletion of I kappa B-alpha followed by a slight transient increase in the level of this inhibitor protein. In contrast, long-term treatment with oxLDL prevented the lipopolysaccharide-induced depletion of I kappa B-alpha, accompanied by an inhibition of both NF-kappa B activation and the expression of tumor necrosis factor-alpha and interleukin-1 beta genes. These observations provide additional evidence that oxLDL is a potent modulator of gene expression and suggest that (dys)regulation of NF-kappa B/Rel is likely to play an important role in atherogenesis.

Antioxidants↗
PubMed1997

Evaluation of a rapid, quantitative cardiac troponin I immunoassay.

We evaluated a rapid, quantitative immunoassay for the detection of cardiac troponin I. Coefficient of variation is between 1.29 and 13.63% for intra-assay and between 3.88 and 10.15% for inter-assay imprecision. Linearity is given up to 35 micrograms/l. Possible interfering substances (haemoglobin, bilirubin, triacylglycerol and rheuma factors) do not disturb the assay. The analyte is stable under normal storage conditions (+20 degrees C/48 h and +4 degrees C/l week) with decrease up to 30% after 3 months at -20 degrees C. Reference value for apparently healthy individuals is < 0.1 microgram/l. In plasma cardiac troponin I is measured up to 30% depressed compared to serum. Comparison with another cardiac troponin I assay (y = 0.92x + 2.42, r = 0.940) and cardiac troponin T is good with y = 6.61x - 1.94, r = 0.91 for the first generation cardiac troponin T assay and y = 5.59x - 0.68, r = 0.87 for the second generation cardiac troponin T assay. In summary, the evaluated assay is fast, easy to perform, and can be used not only in a specialized laboratory, but is also suitable for emergency laboratory or smaller laboratory units.

Drug Stability↗
PubMed1996

Activated transcription factor nuclear factor-kappa B is present in the atherosclerotic lesion.

Nuclear factor-kappa B (NF-kappaB)/Rel transcription factors play an important role in the inducible regulation of a variety of genes involved in the inflammatory and proliferative responses of cells. The present study was designed to elucidate the implication of NF-kappaB/Rel in the pathogenesis of atherosclerosis. Activation of the dimeric NF-kappaB complex is regulated at a posttranslational level and requires the release of the inhibitor protein IkappaB. The newly developed mAb alpha-p65mAb recognizes the IkappaB binding region on the p65 (RelA) DNA binding subunit and therefore selectively reacts with p65 in activated NF-kappaB. Using immunofluorescence and immunohistochemical techniques, activated NF-kappaB was detected in the fibrotic-thickened intima/media and atheromatous areas of the atherosclerotic lesion. Activation of NF-kappaB was identified in smooth muscle cells, macrophages, and endothelial cells. Little or no activated NF-kappaB was detected in vessels lacking atherosclerosis. Electrophoretic mobility shift assays and colocalization of activated NF-kappaB with NF-kappaB target gene expression suggest functional implications for this transcription factor in the atherosclerotic lesion. This study demonstrates the presence of activated NF-kappaB in human atherosclerotic tissue for the first time. Atherosclerosis, characterized by features of chronic inflammation and proliferative processes, may be a paradigm for the involvement of NF-kappaB/Rel in chronic inflammatory disease.

Animals↗
PubMed1994

A rapid assay for the quantification of myoglobin: evaluation and diagnostic relevance in the diagnosis of acute myocardial infarction.

We evaluated a new, fast, quantitative, turbidimetric assay (TurbiTimeSystem, Behringwerke AG, Marburg, Germany) for the determination of myoglobin concentration in serum. Within-run imprecision (n = 10) was < 3.7% in controls ranging from 81.1 to 621.4 micrograms/l and between-day imprecision (n = 50) was < 6% in controls ranging from 69.5 to 623.4 micrograms/l. The assay is linear over the measuring range and interfering substances such as bilirubin, haemoglobin or haptoglobin do not interfere but triacylglycerol-rich samples are only measurable after brief ultracentrifugation. EDTA- or citrate-treated samples display depressed myoglobin concentration when compared with serum samples. The upper reference limit for apparently healthy individuals (n = 100, 50 female and 50 male) is 61.5 micrograms/l. Comparison with nephelometry revealed a good correlation (r = 0.982) between the two methods with the regression equation: turbidimetric assay = 5.53 + 1.02x nephelometric assay. Serial determination of myoglobin concentration and creatine kinase in 18 patients with proven acute myocardial infarction showed in general an equal diagnostic significance for both analytes. In the first 4 hours after onset of chest pain, the determination of myoglobin can have an advantage, since it is released into the blood stream at an earlier stage, but thereafter myoglobin can lead to false negative diagnosis. Therefore, determination of creatine kinase and its isoenzyme MB is still the diagnostic strategy of choice in the diagnosis of acute myocardial infarction.

Citrates↗
PubMed1993

Multicenter evaluation of Iso-ALP test kit for measurement of bone alkaline phosphatase activity in serum and plasma.

A test kit (Iso-ALP, Boehringer Mannheim) for measuring human bone alkaline phosphatase activity in serum or plasma was evaluated in five laboratories in three countries. The assay is based on the principle described by Rosalki and Foo (Clin Chem 1984;30:1182-6) and uses wheat germ lectin to precipitate bone alkaline phosphatase. Residual ALP in the supernate in comparison with total ALP is used to quantify the bone fraction. The imprecision of residual ALP measurement was low (median between-run CV 4.9%) and comparable with that of total ALP. Linearity of precipitation was demonstrable up to a bone ALP activity (diethanolamine buffer 37 degrees C) of 2000 U/L, though a matrix effect was observed for dilutions of high-activity sera in saline or bovine serum albumin. For assaying patients' samples, different batches of lectin demonstrated excellent comparability. Taking electrophoresis as a basis for standardization, we determined that the lectin precipitated approximately 90% of bone ALP, but < 5% of nonbone ALP. From this we derived serum/plasma upper reference limits for bone ALP activity in adults and children.

Adult↗
PubMed1992

Cross-reactivity of a commercial chemiluminescence immunoassay for human chorionic gonadotropin with the free beta-subunit.

An enhanced chemiluminescence immunoassay for the determination of serum human chorionic gonadotropin (HCG) in specimens from oncology patients has been assessed with respect to its cross-reactivity with the free HCG beta-subunit (HCG-beta). The assay, standardized against the First International Reference Preparation 75/537, had a cross-reactivity with the free beta-subunit of 625% (molar basis). Therefore this assay achieves high sensitivity for the detection of either intact HCG or free HCG-beta in serum of patients with seminomatous or nonseminomatous testicular cancers. Results of both assays, the in-house immunoradiometric assay (+HCG-beta) and the Amerlite HCG-60 assay, showed a close correlation (R = 0.854-0.960) when serum samples from tumour patients were analyzed. Moreover, the content of free beta-subunit determined in a specific HCG-beta assay, could be quantitatively measured in the enhanced chemiluminescence immunoassay. Thus, this assay is suitable for oncology use, but also highlights the limitations of measuring HCG in serum samples.

Antibodies, Monoclonal↗
PubMed1991

Application of ion-pair high-performance liquid chromatography to detection of the atypical coproporphyrin isomers II and IV in human faeces.

A highly selective and sensitive method has been developed for the detection of small amounts of the atypical isomers II and IV of coproporphyrin in human faeces. This method combines liquid-liquid extraction and solid-phase sampling techniques using talc and C18-modified silica gel as the sorbents. Simultaneous separation of the four coproporphyrin isomers I-IV was achieved by isocratic ion-pair high-performance liquid chromatography. Stool samples of healthy subjects (n = 12) contained 1.1 +/- 0.4% (mean +/- S.D.) isomer II and 2.2 +/- 0.9% isomer IV of total coproporphyrins. A somewhat higher content of isomer II (2.7%) and isomer IV (5.4%) was found in faeces of a patient suffering from porphyria variegata.

Chromatography, High Pressure Liquid↗
PubMed1991

Simultaneous occurrence of the MB isoenzyme of creatine kinase and macro creatine kinase type 1 in a patient with acute myocardial infarction.

When the immunoinhibition method is used for differentiation of isoenzymes of creatine kinase, the simultaneous occurrence of the MB isoenzyme and variants of macro creatine kinase may lead to misinterpretation in the diagnosis of acute myocardial infarction. We describe the case of an elderly woman in whom the MB isoenzyme and the type 1 variant of macro creatine kinase were found simultaneously in her serum after acute myocardial infarction. It proved possible to identify the MB isoenzyme rapidly using a fast enzymeimmunoassay.

Aged↗
PubMed1991

The isomer ratios of urinary coproporphyrins I--IV are pH-dependent.

The percentage of porphyrinogens as related to total porphyrin excretion was determined in the urine of healthy subjects. Acidic urines (pH 5.0 to 5.9) contained 62.9 +/- 10.7% (means +/- s, N = 11) porphyrinogens, whereas in neutral urines (pH 6.0 to 7.2) a somewhat lower percentage (51.2 +/- 15.3%, N = 11) was detected. However, there was no significant difference between the mean porphyrinogen contents of acidic and neutral urines. Evidence was found for a previously unreported pH-dependent influence on the isomer ratios of urinary coproporphyrins I and III. Acidic urines (N = 18) from healthy subjects showed significantly higher percentages of isomer I (27.1 +/- 6.4%), isomer II (2.7 +/- 1.1%), and isomer IV (5.0 +/- 1.3%) as compared to respective values from neutral urines (22.2 +/- 5.1% isomer I, 0.6 +/- 0.6% isomer II, and 1.5 +/- 1.3% isomer IV; N = 16, p less than 0.001). Conversely, the percentage of isomer III was markedly lower in acidic urines than in neutral urines (65.1 +/- 7.9% vs. 75.9 +/- 5.4%; p less than 0.001). The same relationship was confirmed in an individual subject by analysis of a series of urines (N = 13) with pH values ranging from 5.4 to 7.3. These results point to the possibility that the atypical coproporphyrin isomers II and IV are predominantly formed by an increased isomerization rate of coproporphyrinogens under acidic intravesical conditions.

Chromatography, High Pressure Liquid↗
PubMed1989

Isocratic ion-pair high-performance liquid chromatographic methods for the determination of uroporphyrin and coproporphyrin type II and IV isomers in human urine.

Urinary porphyrins of porphyric patients were isolated as their methyl esters by using a simple, modified thin-layer chromatographic system. Existing methods for the isocratic ion-pair high-performance liquid chromatographic separation of uroporphyrin and coproporphyrin isomers were decisively improved by elevating the column temperatures, changing the types of columns used and modifying the eluent compositions. These techniques were applied to the determination of the isomeric distribution of uroporphyrins and coproporphyrins isolated from urines of patients in the acute or latent phase of acute intermittent porphyria. In these urines relatively high contents of the atypical uroporphyrins II (2-5%) and IV (13-19%) were found. The coproporphyrin fractions contained significantly smaller amounts of the atypical isomers II (1-2%) and IV (2-5%), the presence of which was demonstrated for the first time in such urines. Several mechanisms for the formation of the atypical coproporphyrin isomers are discussed. The isocratic ion-pair separation method served also to control the isomeric purity of uroporphyrin specimens of both natural and synthetic origin.

Chromatography, High Pressure Liquid↗