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K Borner

Publications and source records attributed to K Borner.

At least 109 records · Page 6Linked to original sources
PubMed1981

A candidate reference method for determination of total protein in serum. II. Test for transferability.

The transferability of the candidate Reference Method for total serum protein was tested in eight laboratories in the United States and Europe. National Bureau of Standards SRM 927 (bovine serum albumin) was used in each analytical run as the calibration standard. The mean absorptivity value obtained for this material was 0.2983 L g-1 cm-1. Four serum pools prepared at the Centers for Disease Control were analyzed on each of 15 days. Within-run variation of the protein values (expressed as CV) in the eight laboratories ranged from 0.1 to 2.5% and day-to-day (total) variation in six of the laboratories ranged from 0.4 to 1%.

Biuret Reaction↗
PubMed1979

[Determination of thyroxine in serum by a heterogeneous enzyme immunoassay: results of a joint trial].

This paper describes the evaluation of a heterologous enzyme immunoassay for the determination of total thyroxine in serum by a group of seven clinical chemical laboratories. The test follows the principles of the enzyme linked immunosorbent assay (ELISA) and uses peroxidase as a marker. The evaluation of analytical reliability yielded the following results within the analytical range from 39 unto 322 nmol/l: 1. Within-batch precision ranged from 3.1 unto 10.4% (coefficient of variation) with single analyses. 2. Between-batch precision ranged from 3.7 unto 20.4% with single analyses. 3. Between-laboratories precision ranged from 5.4 unto 6.8%. 4. Pure thyroxine, added to serum or thyroxine-free serum, gave recoveries between 93 and 120%. 5. Analysis of control sera gave results essentially comparable to the assigned values based upon radioimmunoassays. 6. Analysis of 288 clinical sera gave slightly higher results by the enzyme immunoassay than by the analogous radioimmunoassay from the same manufacturer. 7. Comparison with other methods of analysis (radioimmunoassays, competitive protein ligand assays, hormonal iodine assay) yielded partly comparable, partly higher results. 8. Comparison with the homogenous enzyme immunoassay (EMIT) led to comparable results. 9. Interference due to hyperlipemia or hemolysis was not observed. 10. There might be an interference in hyperbilirubinaemic sera, due to an as yet unknown factor. With respect to practicability the ELISA-test compares favourably with the analogous solid phase radioimmunoassay. The main differences are the absence of radioactive material and a longer shelf-live of reagents. Following the manual procedure the time taken to perform the enzyme immunoassay is slightly longer than for the analogous radioimmunoassay.

Enzyme-Linked Immunosorbent Assay↗
PubMed1978

[Determination of digoxin in serum. Comparison of radioimmunoassay and a heterogeneous enzyme immunoassay (author's transl)].

This paper describes the evaluation of a heterogeneous enzymeimmunoassay (EIA, subtype ELISA) for the determination of digoxin in serum. Results are compared with those obtained from a radioimmunoassay (New England Nuclear, 125I-Digoxin). The limit of detection is 0.3 microgram/1 (0.4 nmol/1). The range of the test is from 0.3 unto 5.0 microgram/1 (0.4--6.4 nmol/1). Within-batch precision ranged from 7 to 11%, between-batch precision from 8--14%. Pure digoxin, added to solutions of albumin and pooled sera, gave recoveries between 87 and 106%. 116 sera from patients taking digoxin exclusively yielded no systematic difference compared to the results of a radioimmunoassay (RIA) (equation of the bivariate regression CELISA = 0.954 . CRIA + 0.14 (microgram/1) (0.18 nmol/1). Nevertheless marked differences between both tests were observed in individual cases. Digitoxin yielded in vitro and in vivo a cross-reactivity of 7 to 14% depending upon the concentration. In 68 sera from patients, taking digoxin plus spironolactone, we found results that were on average 0.48 microgram/1 (0.64 nmol/1) higher with the ELISA than with the RIA (p less than 0.01%). With respect to practicability the ELISA test for digoxin is very similar to the analogous RIA both using the solid phase technique.

Cross Reactions↗
PubMed1977

[Enzymatic determination of total cholesterol with the Greiner Selective Analyzer (GSA-II) (author's transl)].

A fully enzymatic method to determine total cholesterol in serum is described. The method appears especially suitable for adaptation to discrete mechanical analyzers either of the single channel or the multi-channel type. The method uses the enzymes cholesterol esterase (EC 3.1.1.13), cholesterol oxidase (EC 1.1.3.6) and peroxidase (EC 1.11.1.7) with 4-aminophenazone and phenol as substrates in the indicator reaction. The method was adapted to the Greiner Selective Analyzer GSA-II. For this purpose the critical parameters of the reaction were intensively examined. The complete reagent is stable within the GSA II dispenser at 4 degrees C for at least 1 week. By omitting cholesterol oxidase in the blank reagent a sample bland and a partial reagent blank are obtained. Within a range up to 10.4 mmol/1 (4.0 g/l) the maximum colour is developed within 6 minutes. The calibration factor was stable for 4 months. The method allows absolute measurements. At concentrations between 2 and 4 mmol/1 within-batch precision ranged from 0.5 to 1.4%. Precision from day to day for the same control sera amounted to 2.8; 2.0; 2.7 and 2.0% for a period of 3 months. Examination of accuracy yielded satisfying results. Ascorbic acid in the physiological range did not alter results to a significant extent. Catalase or novaminesulfone added in vitro did not interfere. Optical interferences by bilirubin, hemoglobin or turbidity are compensated by a sample blank. A comparison of results with the enzymatic method of Roeschlau et al. (Z. Klin. Chem. Klin. Biochem. 12, 226 (1974)) yielded satisfactory agreement. The limits of detection of the present method can be lowered by a factor of 2.2 by replacing phenol by dihalogen phenols.

Autoanalysis↗
PubMed1975

Effects of a protein-free diet on amino acids and sex hormones of rats during the early postimplantation stages of pregnancy.

In rats, the effect of a protein-free diet on the maintenance of gestation was investigated during the early postimplantation stages (days 7 to 10). The growth kinetics of the implantation site, the concentrations of free amino acids in the implantation sites as well as in the maternal liver and the levels of sex hormones in the maternal serum were determined. The results of these studies showed that in the whole implantation site, the absolute amounts of DNA, RNA and nitrogen were significantly lower in the rats fed a protein-free diet, the concentrations of essential amino acids decreased in the whole implantation site to the same extent as in the maternal liver. In the case of the non-essential amino acids, however, a significant increase in the concentrations of some of the amino acids was observed in the maternal liver. With regard to the essential amino acid pool, it appears that the liver and decidua can be regarded as being in a dynamic equilibrium. Peripheral prolactin and progesterone concentrations significantly decreased on day 8 of gestation, while the amounts of LH and total oestrogens remained unchanged.

Amino Acids↗