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Biomedical subjects

H J Thiele

Publications and source records attributed to H J Thiele.

At least 19 recordsLinked to original sources

Regeneration of adsorbed and covalently immobilized antibodies on solid phases for immunoassay.

A technique for the reproducible re-use of antibody-coated solid phases for immunoassays is described. The method based on the dissociation of the antigen-antibody complexes. Two different procedures, using glycine buffer (pH 2.3) or ethanolamine, were developed. More than ten immunoassay cycles can be realized with the same antibody-coated microtitre plates. These procedures were tested with competitive and sandwich immunoassays, monoclonal and polyclonal antibodies, and a commercial immunoassay kit.

Adsorption↗

An improved solid-phase enzyme and luminescent immunoassay system for steroid hormones and digoxin.

A uniform solid-phase system has been developed for enzyme (ELISA) or luminescent (LIA) immunoassays for steroids. These assays were improved by (a) irradiating microtiter plates or polystyrene tubes before coating with antibody or Protein A, (b) coating the plastic trays with nonspecific anti-gamma-globulin or Protein A instead of the steroid-specific first antibody, and (c) partial denaturation of the second antibody before coating the plates or tubes with it. Specific antibodies were raised against cortisol, aldosterone, 17-hydroxyprogesterone, and digoxin. Horseradish peroxidase was used as label for the ELISA and aminoethylisoluminol for the LIA. In comparison with the first (specific) antibody coating method we observed some advantages: From 10- to 33-fold lower concentrations of first antibodies were necessary to bind the same amount of steroids; precision was better (CV, 3.8-7.5% vs 6.9-15.5%). The high sensitivity of these assays (0.5-2.0 pg per tube for the steroids) also allows determination of the steroids and digoxin in plasma and saliva.

17-alpha-Hydroxyprogesterone↗

Enzymeimmunoassay of unconjugated estriol in serum and saliva during pregnancy.

An enzymeimmunoassay (EIA) for unconjugated estriol was developed. Estriol-6-CMO-BSA was used as antigen for the antiserum production with low cross reactivities to estrone (0.3%) and estradiol (0.17%). The enzyme conjugate (estriol-peroxidase) was prepared using the mixed anhydride reaction. The antibody bound estriol fraction was separated from the free fraction with the double antibody technique. The test requires a simple photometer for the measurement of enzyme label. The developed estriol-EIA needs a short incubation time (2 hrs). The normal values of estriol in serum were determined. The results are in good agreement with the results of RIA. Furthermore, we found an inverse diurnal rhythm of serum and salivary estriol in comparison to the cortisol level. Low estriol levels in the morning and high estriol concentration in the evening are indices of fetal health. Decreased estriol levels in the morning of several days were found in pathological pregnancies (intrauterine fetal death, fetal distress, hepatose).

Circadian Rhythm↗

A simple solid phase enzyme immunoassay for aldosterone in plasma and saliva.

A sensitive, solid phase enzyme immunoassay for the determination of aldosterone in plasma and saliva has been developed. For this purpose anti-aldosterone coated tubes were used. The enzyme marker was a covalently linked aldosterone/horseradish peroxidase conjugate. The assay had a limit of detection of 5 pg/assay tube. The test requires neither centrifuge nor gamma or beta counter, but only a simple photometer. The free/bound separation is based on the solid phase technique with a simple washing step. The normal values for aldosterone in plasma and saliva before and after ACTH application were determined. Saliva, being easily collected by a non-invasive, stress-free technique, is an alternative to plasma. The aldosterone levels in patients with Conn's syndrome were significantly increased in plasma and also in saliva.

Addison Disease↗

[Organization of laboratories in the German Democratic Republic].

The effectivity of the clinical medicine becomes increasingly dependent on the efficiency of medico-experimental subjects, to which belong pathological chemistry and clinical biochemistry as well as haematology. The scientifically proved increasing demands made on the laboratories concern the quality of the results of investigations, constantly increasing numbers of investigations as well as a considerable enlargement of the investigation programmes. Adequate developments of workman are not to be expected. The requirements are to be met by the increase of the working productivity, for which a good organisation of work the use of mechanisation and automatisation means for the elaboration of large series of investigations are the prerequisite. A high degree of centralisation ascertains the effectivity of the adequate investments. Exceeding the ascertained foundations for a project of organisation of the laboratory work in the GDR in the next time still various problems must be solved which especially influence the organisation. Among others they concern the necessary investigation programme for the general practitioner in an out-patient practice, moreover the establishment of investigation programmes for several levels of care, the necessary quality (precision and exactness) of the results of investigations, the suitableness of stripe tests and the influence of preanalytic factors and especially of the biorhythmics on the findings of investigations. The tendencies described are accompanied by the danger that the reciprocities between clinic and laboratory becoming increasingly more necessary for the interpretation and classification of laboratory findings into the symptom complex become rather loose. Therefore, it will be one of the most important tasks of future to develop together reorganisation and collaboration.

Chemistry, Clinical↗

[Methods and specificity of internal medicine specialties in multiphasic screening].

Issuing from the classical definitions for the diagnostic sensitivity and specifity of examination methods in multiphasic screenings is deduced that out of the whole methodical spectre of internal specialities only limited parts are to be applied in multiphasic screenings. At the instance of a multiple multiphasic screenings (model study Sternberg '70) ways to the establishment of reduced optimal parameter combinations are demonstrated. With multivariate statistical methods (facotor analysis, discriminative methods) we succeeded in finding parameter combinations for special groups of diagnosis (liver diseases, hypertension and obesity), by means which these groups in multiphasic screenings are clearly to be differentiated from the healthy symptom-free residual population.

Cardiovascular Diseases↗