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Biomedical subjects

P C Scriba

Publications and source records attributed to P C Scriba.

At least 145 records · Page 8Linked to original sources
PubMed1976

Cooperative study on the radioimmunological thyrotropin determination (hTSH) in serum (author's transl).

This paper deals with a cooperative survey on the radioimmunoassay of thyrotropin in human serum, which was organized by the Thyroid Group of the German Society for Endocrinology. Eighteen serum specimens were to be measured in triplicates. Among the latter were 10 specimens of a hTSH standard curve, prepared in low hTSH serum, which contained approximately 1 mU/l. One of these pool sera was divided in half, and one half was enriched with 10 kU/l human chorionic gonadotropin to test for cross reactivity. One specimen las for the measurement of the non-specific binding. The count rates and the dose levels of the standard curve of each participating laboratory (N = 32), normally performed in albumin-buffer, and the count rates of the 18 unknowns were requested as results. THE CALCULATION OF THE STANDARD CURVES AND THE RECOVERy curves, the evaluation of the unknowns and the statistics were performed by spline functions, using a 48 kb FORTRAN-program on a Siemens 404/3 computer. The results demonstrated that the interlaboratory precision of 128% and the recovery rates between 50 and 926% are very unsatisfactory. However, the coefficient of variation was lowered to 31%, when the controls were read from the recovery curves, as included in the samples. In addition to this improvement of the interlaboratory precision and of the accuracy, this study showed, that the sensitivity was markedly improved by using delayed addition of tracer.

Buffers↗
PubMed1975

[Thyroidal autoregulation in nontoxic goiter patients: normalization of the T3/T4 ratio in serum by treatment with potassium iodide (author's transl)].

In iodine deficiency areas, an increased T3/T4 ratio in serum was reported earlier. In this study the influence of potassium iodide on the T3/T4 ratio was investigated. Treatment with 200 mug KI per day for only 4 weeks normalized the initially elevated T3/T4 ratio in 16 nontoxic goiter patients (24.6 plus or minus 9.9 times 10-3, mean plus or minus S.D., before, respectively 18.9 plus or minus 5.5 times 10-3 after KI treatment, p smaller than 0.0025). The mean basal TSH levels (1.42 plus or minus 0.68 before, respectively 1.29 plus or minus 0.52 mugU/ml after KI), and the TSH increase 30 min after 200 mug TRH i.v. (5.54 plus or minus 4.22 and 6.50 plus or minus 5.09 mugU/ml, respectively) did not change significantly. Since the normalization of the T3/T4 ratio in nontoxic goiter patients was independent from changes in the TSH levels, this effect of KI obviously represents an example of thyroidal autoregulation.

Goiter, Endemic↗
PubMed1975

A modular analyzer system for double antibody radioimmunoassays.

The increasing number of determinations performed by radioimmunoassays necessitates rationalization of the procedures. An analyzer system has been developed in order to fully mechanize double antibody radioimmunoassays, which is essentially composed out of four independently working modules. The samples, in microliter vials, are carried in sample chains of up to 650 links. The first pipetting step is performed by syringes with displacement pistons. Additional reagents are rapidly added by an electronically controlled Hamilton repeating dispenser, which makes shaking procedures for mixing unnecessary. The bound/free separation is achieved discontinuously by use of Nuclepore-filters, which are carried in 3 inches distance (76 mm) by a 35 mm dark leader film. After covering the radioactive filter positions with an adhesive plastic foil from both sides, the film spool is directly inserted into a specially constructed gamma-counter. The results of the evaluation of the efficiency and of the precision of each module are presented in this paper.

Autoanalysis↗
PubMed1975

[Simultaneous column chromatography for the automatic determination of hormones (author's transl)].

The automatic determination of hormone levels in serum by column chromatograhoic methods using a 25 channel peristaltic pump, allows the simultaneous chromatography of 25 samples. The different volumes which are necessary for the successive elution steps are set by the tubing size of the pump and by a preset switch clock. The eluates from the 25 columns are collected simultaneously in fractionated volumes which are also determined in the same electronic clock device. The assays so far adapted to this principle are reviewed: Serum thyroxine (competitive protein binding assay), T3-uptake test (dextran gel filtration), triiodothyronine (radioimmunoassay) and cortisol (competitive protein binding assay or radioimmunoassay). The main advantages of this procedure are increased frequency, improved specificity and standardization at lower costs for these methods. The principle of simultaneous column chromatography appears to be most suited for assays, which require various extraction steps prior to the determination of the hormone, since it allows extraction, specific protein binding and bound/free separation on only one column.

Autoanalysis↗