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Biomedical subjects

P C Scriba

Publications and source records attributed to P C Scriba.

At least 91 records · Page 5Linked to original sources
PubMed1983

[Critique of goiter epidemiology. I. Goiter size].

Comparison of three methods for demonstration of thyroid enlargement in 92 patients showed that the sensitivity of sonographic volumetrics (93%) and palpation (91%) is superior to radiography (45%). Sonography has the disadvantage of lack of quantitative demonstration of retrosternal goitre. Palpation and chest radiograph had the disadvantage of a frequency of false positive findings in 8.7 and 10.9%.

Adult↗
PubMed1983

[Critique of goiter epidemiology. II. Age dependence].

Chest radiographs (n = 2000) of the public health office of Eutin were evaluated for the frequency of goitre in northern West-Germany. Up to the 40th year of age the frequency was 5%. Thereafter the prevalence of goitre-suspect radiographs gradually rose to 25% and to 50% after the 65th year of life. The radiographic method indicates that endemic goitre exists in Schleswig-Holstein as was to be expected due to formerly demonstrated alimentary iodine deficiency.

Adolescent↗
PubMed1983

[Comparison of three quality control investigations on radioimmunological determination of thyrotropin using the "Munich model"].

The results of a thyrotropin external quality assessment survey (EQAS) carried out in 1980 using the "Munich Model" and including a "matched reagent" experiment are presented and are compared with the results from similar surveys carried out in 1974 and 1977. Despite the fact that in 1974 only 4 different kits were used, compared with 12 in 1977 and 17 in 1980, the inter-laboratory precision has continually improved. This was reflected by the inter-laboratory coefficient of variation (CV) for all laboratories, which, for a sample with ca. 15 microU/l thyrotropin were: 65% (1974), 22% (1977) and 12% (1980), and for a sample containing ca. 5 microU/l thyrotropin: 75% (1974), 45% (1977) and 20% (1980). During the same period, the fraction of participants using commercial kits increased from 0.65 to 0.95. There was a definite trend towards shorter assays, even though with such assays there is a danger that the measured values for low thyrotropin concentrations will be too high. In spite of the fact that the "high-blank" effects have to a large extent disappeared, many kits showed an unacceptably high cross-reactivity with human chorionic gonadotropin. A fraction of 0.30 of all participants in 1974 used computer-assisted data-processing, compared with 0.78 in 1980. In 1980, the most commonly used algorithm was a spline function (0.46 of participants using a computer for data-processing). Although the number of kits has increased, the precision has improved, showing that more robust methods are now employed. This has partly come about because of the introduction of human thyrotropin-free serum as matrix for the standards (1974 - 0.16, 1980 - 0.83 of all participants). Further external quality assessment programmes are discussed for the continual monitoring of hormone assay performance.

Humans↗
PubMed1982

Solid phase antigen luminescent immunoassays (SPALT) for the determination of insulin, insulin antibodies and gentamicin levels in human serum.

We describe an interesting and novel alternative to conventional immunoassay techniques for the measurement of antigens and antibodies in body fluids. The label used for all assays is a pyruvate kinase-IgG conjugate of the relevant second (species-specific) antibody. All assays follow the same principle in which a solid phase antigen is used to adsorb unreacted first (substance-specific) antibody following a conventional antibody-antigen reaction in a liquid phase. After washing, the solid phase antigen-first antibody is allowed to react with the labelled second antibody. The solid phase is then washed and the pyruvate kinase bound to the solid phase is used to generate ATP which is measured kinetically in a luminometer. Assays are described for insulin, insulin antibodies and gentamicin to demonstrate both the versatility and sensitivity of this type of assay. The insulin assay had a lower detection limit of under 0.25 microU per tube and was comparable with the radioimmunoassay used for routine purposes both in sensitivity and reproducibility. The insulin antibody assay correlated well with the radiometric determination used routinely in the laboratory. The gentamicin assay correlated well with the routine commercial radioimmunoassay and also had comparable coefficients of variation. In all cases, the inter- and intra-assay variation was under 10% in the range of interest.

Animals↗
PubMed1981

[Volumetric analysis of thyroid lobes by real-time ultrasound (author's transl)].

Thyroid volume as measured by real-time ultrasound in cadavers was compared with direct measurements obtained by submersion. Length X width X thickness of the thyroid lobe multiplied by factor pi/6, correspond to a rotation ellipsoid, while the best calculated volume of the lobe is obtained by multiplying with the optimised correction factor f = 0.479. The correctness of this calculation is, by definition, 100%; average error of the method is 16%. The measurements are easy to do and require no additional equipment for planimetry or calculations. Volumetric analysis of the thyroid gland is especially necessary in assessing results of treatment and for measuring dosage in connection with radioiodine therapy.

Goiter↗
PubMed1981

Thyroxine-binding globulin: investigation of microheterogeneity.

Preparations of T4-binding globulin (TBG) from human serum was performed using only two affinity chromatography steps. Purity of the protein was demonstrated by a single band in overloaded disc and sodium dodecyl sulfate electrophoresis, equimolar binding to T4, and linearity in sedimentation velocity run. The molecular weight was calculated to be 60,000 +/- 3,000 daltons (n = 3), the sedimentation coefficient was 3.95S, and the Stokes' radius was 37 A. The amino acid composition was found to be in good agreement with the calculations of other authors. By isoelectric focussing (IEF), pure TBG showed four main bands at pH 4.25, 4.35, 4.45, and 4.55 together with several fainter bands. The N-acetylneuraminic acid (NANA) content of the four TBG bands isolated by preparative IEF was found to decrease from 10.2 mol NANA/mol TBG in the band at pH 4.25 to 4.8 mol NANA/mol TBG in the band at pH 4.55. No significant difference in the affinity constants of the TBG bands to T4 was found. The affinity constants for TBG ranged from 3.1 x 10(9) to 7.2 x 10(9) M-1. Sequential kinetic desialylation of pure TBG resulted in a progressive tendency toward one major band at pH 6.0. In native sera, microheterogeneity of TBG was detected after IEF on polyacrylamide gel plates by immunofixation. The typical TBG patterns shown by pure TBG were also found in normal subjects. Characteristic deviations from this pattern were found in the sera of females during estrogen therapy or pregnancy, where there was a gradual increase in density of the band at pH 4.25 and the appearance of an additional band at pH 4.15. In sera from patients with liver disease and elevated TBG levels, there was a fading of the acidic bands, whereas the more alkaline band at pH 4.55 was intensified. It is therefore proposed that microheterogeneity of TBG is caused by differences in NANA content and that variations of TBG patterns in native sera may reflect altered TBG synthesis or degradation. A genetically related microheterogeneity of TBG could not be demonstrated after examination of 800 sera, including 2 families with quantitative TBG deficiency.

Amino Acids↗
PubMed1981

The development of a direct homologous radioimmunoassay for serum cortisol.

This article describes the synthesis of a pure cortisol-3-(O-carboxymethyl) oxime with its subsequent use in producing highly specific antibodies and a 125I-tracer with a shelf life in excess of several weeks. An assay was developed using a pH of 4, thus allowing a direct measurement of cortisol in serum without extraction or heat denaturation. The quality-control parameters were checked - the intra-assay C.V. in the working range (area of clinical interest) was under 5%, and the interassay C.V. under 11%. Correlation studies with results using other antisera and with 3H-tracer are highly significant with the slope of the regression curve deviating less than 2% from the ideal volume. Finally the assay is fully automatable and is suitable for most automatic pipetting and analysis systems.

Animals↗
PubMed1981

Experiences using chloramine-T and 1, 3, 4, 6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril (Iodogen) for radioiodination of materials for radioimmunoassay.

A comparison of labelling compounds with chloramine-T and with 1, 3, 4, 6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril (Iodogen) has been carried out. For human transferrin, human calcitonin, 1-84 bovine parathyrin, fibrinopeptide-A, human thyrotropin and F-CB3, a cyanogen bromide cleavage peptide of human fibrinogen, the quality of tracer produced by the Iodogen method was better. For rat lutropin, human growth hormone and human prolactin, labelling with Iodogen produced a tracer of unsatisfactory quality. For a further 13 peptides, the results from both methods were comparable. Optimal reaction times using Iodogen were of the magnitude of two to three times longer than when using chloramine-T. Reduction of the volume of radioactive waste by up to 90% could be achieved when the Iodogen method was coupled with a short cation-exchange column to separate unreacted iodide from the labelled compound. Data is presented on the quality of tracer, expressed in terms of elution profiles and radioimmunoassay standard curves. A novel "combi-method" of labelling proteins without tyrosine or histidine moieties is presented where N-succinimidyl-3-(4-hydroxyphenyl)-propionate is labelled at pH 7.5 using Iodogen to give "Bolton-Hunter" reagent, which is then transferred to a vessel containing the peptide to be labelled at ph 8.6.

Animals↗