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Biomedical subjects

R Kattermann

Publications and source records attributed to R Kattermann.

At least 19 recordsLinked to original sources
PubMed1992

Fatty acid modulation of HepG2 cell cholesterol biosynthesis and esterification.

We investigated the effects of medium supplementation with increasing amounts of different fatty acids on HepG2 cell cholesterol biosynthesis and esterification. Up to 200 microM 16:0 led to an increase in cholesterol secretion/synthesis of 60%/40%; 18:1, 18:2, or 18:3 decreased secretion/synthesis by 35%/25%, 65%/65%, and 60%/60%; 80 microM 20:5 caused a reduction of 75%/50%. Compared to 200 microM 16:0, 18:2 led to a 50% reduced cellular cholesterol ester biosynthesis; the effect of 30 microM 20:5 was comparable to that of 18:2 while the addition of 200 microM 18:1 raised esterification. Supplementation of 18:2 reduced the cellular cholesterol ester content by 50%; 16:0 led to an increase of 80%. The effects of saturated and unsaturated fatty acids seem to be related to their number of double bonds and could be due to changes in membrane phospholipid fatty acid composition.

Carcinoma, Hepatocellular↗
PubMed1992

Liquid chromatographic analysis of phenobarbital, phenytoin, and theophylline.

Sera from the routine of therapeutic drug monitoring were assayed for phenobarbital, phenytoin, and theophylline with three different methods: fluorescence polarization immunoassay as the standard procedure, the new CEDIA assays within a multicenter evaluation and HPLC which is known to yield results with a high specificity. CVs for between-day imprecision ranged from 2.6-8.6%, depending on the concentration of the drugs. There was a tendency to lower CVs for the HPLC procedure. Accuracy was verified with commercial control materials and spiked sera and proved to be satisfactory for all three methods and parameters. The linear range was approx. twice as wide for the HPLC compared with the other methods. The method comparisons were quite favorable. Deviations occurred mainly in the subtherapeutic concentration range.

Chromatography, High Pressure Liquid↗
PubMed1992

Results of the multicenter evaluation of the CEDIA Theophylline assay.

We report on the results of the multicenter evaluation of the CEDIA Theophylline assay on Boehringer Mannheim/Hitachi analyzers in 15 clinical laboratories in Europe and U.S.A. Main items of investigation were imprecision, recovery of control sera, interlaboratory survey and method comparisons using patient samples. Imprecision was found to be comparable to other routine methods. An advantage of the CEDIA assay can be seen in the good interlaboratory transferability of results. The new test has been shown to measure very accurately particularly by comparison with HPLC procedures revealing highly correspondent results. The reagent can be used up to one month using multiple recalibration. Due to its high practicability and reliability the CEDIA Theophylline assay can be recommended as a very suitable routine method for therapeutic drug monitoring on random access analyzers like Boehringer Mannheim/Hitachi analysis systems.

Dose-Response Relationship, Drug↗
PubMed1992

Results of the multicenter evaluation of the CEDIA Phenytoin assay.

Thirteen clinical evaluation sites in Europe and U.S.A. investigated the CEDIA Phenytoin assay on Boehringer Mannheim/Hitachi analyzers with respect to imprecision, recovery of control sera, interlaboratory survey, linearity and method comparisons using patient samples. The linear dose-response relationship up to 40 micrograms/mL was confirmed by all participants. Imprecision at therapeutic analyte concentrations equalled that of other routine methods. Recovery of controls was found in a +/- 6% range for target values assigned by the CEDIA assay. The good interlaboratory transferability of the CEDIA assay was confirmed with control material and human samples. The reconstituted reagent can be used up to one month using weekly recalibration. In method comparison studies good correlations to other routine methods were obtained. Results in analyte-free human sera did not deviate systematically from the zero-point. Thus, the accuracy in patient sera has been shown for the CEDIA Phenytoin assay.

Dose-Response Relationship, Drug↗
PubMed1992

Results of the multicenter evaluation of the CEDIA Phenobarbital assay.

The CEDIA Phenobarbital assay has been evaluated in twelve clinical laboratories in Europe and U.S.A. on Boehringer Mannheim/Hitachi analysis systems. The evaluation focused on the analysis of imprecision and accuracy. Within-run and between-day coefficients of variations of the new assay were comparable to those of established routine methods. As demonstrated in an interlaboratory survey study with controls and human sera, results obtained in different laboratories showed a good agreement. The CEDIA Phenobarbital assay measured very accurately, as particularly confirmed by comparison with HPLC. It can be recommended as a reliable and practicable test for monitoring of phenobarbital on Boehringer Mannheim/Hitachi analyzers used in routine clinical chemistry.

Calibration↗
PubMed1992

Results of the multicenter evaluation of the CEDIA cortisol assay.

The present paper describes the multicenter evaluation of the CEDIA Cortisol test for total cortisol. The observed linearity of the test was between 1.2 and 50 micrograms/dL cortisol. The limit of detection was calculated as 1.2/dL. Imprecision studies covering the diagnostically relevant range (5-20 micrograms/dL cortisol) yielded coefficients of variation between 1.7-8.9% (within-run) and 2.7-10.5% (between-day). An interlaboratory survey using 41 human samples and three control sera demonstrated that the new CEDIA Cortisol assay has a good interlaboratory transferability. Method comparison studies between the CEDIA Cortisol test and EIA, FIA, FPIA, and various RIAs yielded an acceptable level of agreement and concordant results in most cases. Low cross-reactivity of the antibody used in the new cortisol assay was observed with precursors or metabolites of cortisol. Especially, dexamethasone did not cross-react. However, prednisolone, 6-methylprednisone, and corticosterone showed cross-reactivities. No limitation by endogenous interferences was observed. The CEDIA Cortisol assay permits the precise, fast and sufficiently specific determination of cortisol. Furthermore, it offers the advantages of a non-radioactive assay and can be performed conveniently on Boehringer Mannheim/Hitachi analyzers in combination with routine clinical chemistry.

Humans↗
PubMed1989

Improved method for enzymic determination of cholesterol in lipoproteins separated by electrophoresis on thin layer agarose gels.

The cholesterol of lipoproteins, separated electrophoretically on thin layer agarose films, is visualised and quantitated by incubating the gels in an enzymic reagent containing cholesterol esterase and cholesterol dehydrogenase. The individual fractions are quantitated by scanning densitometry. No sample pretreatment is necessary. All major fractions are detected readily. The accuracy of the determination is similar to that of ultracentrifugation. On average, imprecision is 3.1% for beta-, 7.0% for pre beta-, and 4.8% for alpha-lipoprotein cholesterol. Concentration and colour development are linear up to 8 mmol/l cholesterol in a given lipoprotein fraction. The results from the direct enzymic procedure for beta-, pre beta- and alpha-lipoprotein cholesterol are compared with those from quantitative lipoprotein electrophoresis after precipitation with phosphotungstic acid and bivalent cations and with those from different precipitation methods using dextran sulphate and polyethylene glycol. The new method has several advantages: high specificity; lack of dependence on the actual composition of the lipoproteins; lack of interference from coprecipitated proteins in the gel, e.g. fibrinogen or paraproteins; and insensitivity to lipolysis and high free fatty acid concentrations caused by heparin application or ageing of the specimen (at least for alpha-lipoprotein cholesterol quantitation). In its convenience and simplicity of operation, and the simple calculation of results, the method is similar to standard protein electrophoresis. The proposed method is therefore suggested as a standard method for elucidating lipoprotein disorders.

Cholesterol↗
PubMed1989

Enzymatic determination of lipids in human bile without bilirubin interference: reliable assessment of the cholesterol saturation index (CSI).

We describe a simple and rapid, but nevertheless precise and accurate method for the enzymatic determination of the main lipid constituents in human bile. Interfering bile pigments, especially bilirubin are eliminated by the use of aminopropyl bonded phase columns ("Bond-Elut") prior to the enzymatic measurement of cholesterol and lecithin. Intra-assay imprecision was between 3.1 and 4.9% CV, while the inter-assay figures were rather higher at 4.6 to 7.5% CV. Recoveries of bile salts, lecithin and cholesterol were between 94 and 103%. In contrast, the direct enzymatic determination in native bile produces falsely low results: lecithin from 5 to 20%, cholesterol from 25 to 40% of the true value. The results of both enzymatic methods correlated well with commonly accepted procedures for phospholipid and cholesterol determination. When compared with methods of bile lipid analysis involving solvent extraction, the column separation followed by enzymatic determination has the advantage of being simpler and less time consuming, without need of high-cost equipment, e.g. gas chromatography.

Alcohol Oxidoreductases↗
PubMed1989

[Risk indicators of urinary calculus formation: value of oxalate and citrate excretion in comparison with the oxalate tolerance value].

Several methods for the measurement of crystallization conditions in urine, the so-called whole urine systems, have recently been of considerable interest in urolithiasis research. The diagnostic accuracy of the oxalate tolerance value (OTV) was therefore compared with the daily excretion of oxalate and citrate in normal persons and patients with urinary calculi. With the aid of the oxalate/citrate ratio, 77% of the patients could be classified correctly. After standardization of the experimental conditions (24-h urine sample, constant pH value, consideration of endogenous oxalate) we succeeded in correctly classifying 82% of patients using the OTV. These results favour the introduction of the OTV as a clinical chemical tool for the follow-up of patients with urinary calculi and for the screening of normal persons at risk.

Adult↗
PubMed1988

A specific method for the direct determination of lipoprotein cholesterol in electrophoretic patterns.

Lipoproteins are separated electrophoretically and cholesterol is visualised with an enzymic reagent specific for cholesterol in which the gels are incubated. Quantitation of the individual fractions is accomplished by scanning densitometry. No sample pretreatment is necessary. All major fractions are detected readily. Accuracy agrees favorably with results from the ultracentrifugation. On the average, imprecision is 3.1% for beta-, 6.9% for prebeta-, and 5.2% for alpha-lipoprotein cholesterol. Concentration and color development are linear up to 8 mmol/l cholesterol in a given lipoprotein fraction. The results of the direct enzymic procedure for beta-, prebeta- and alpha-lipoprotein cholesterol are compared to the quantitative lipoprotein electrophoresis after precipitation with phosphotungstic acid and bivalent cations.

Cholesterol↗
PubMed1988

Investigation of the performance of the ES 600 Enzymun-Test system. A multicentre study.

The ES 600 sample-selective multibatch analyser was subjected to a multicentre evaluation in six laboratories in accordance with ECCLS guide-lines. During the 3-month trial, five Enzymun-Test diagnostics (T4, TBG, Digoxin, CEA and TSH)1) were measured at 25 degrees C. The study yielded the following results: 1. The within-series and between-series precision were very good, with mean CV's of approx. 3% and 7% respectively. 2. Recovery of the target values for three control sera was in the range +/- 5%. 3. A trend in measurements did not occur in any of the methods investigated (for series of over 240 determinations). 4. Comparison of the results with those obtained on the ES 22 Enzymun-Test system showed good agreement. 5. Within the measuring range defined by the standards, no deviations could be ascertained upon dilution of the samples. 6. Total carry-over in the instrument was below 0.05%. From studies with instruments from the first production series, it became evident that modifications were necessary to improve the reliability. A follow-up measuring programme confirmed a clear improvement in reliability and a reduction in the imprecision, particularly for results from series to series.

Carcinoembryonic Antigen↗
PubMed1985

Acetate formation after short-term ethanol administration in man.

The effect of an acute oral load of 0.5 g ethanol/kg body weight was studied in a group of 10 healthy male and one of 10 healthy female individuals. The following parameters were measured in the blood between 0 and 7 h after the start of the experiment: ethanol, acetate, glucose, free fatty acids, free glycerol, lactate, pyruvate, 3-hydroxybutyrate, acetoacetate. While the elimination of ethanol followed zero-order kinetics between 2 and 5 h, a steady-state concentration of 0.4 to 0.6 mM acetate in the serum was observed during the same time interval. Concomitantly, a significant decrease of free fatty acid and free glycerol concentrations was observed.

Acetaldehyde↗