[en] Triiodothyronine concentration was determined in human serum and in thyroid extracts by two radioimmunoassay technics. Both antibodies, radioactive T₃, stable T₃, protein-binding-hormone inhibitors, methods used to separate the free from the bound fractions were different. Each factor from a method was substituted to the homologue of the other method. The results occasionnally showed a variation of 32% in the first method and 50% in the second one. However the results gave a correct interpretation of the triiodothyronine values measured in human serum and in thyroid extracts

[en] A novel double antibody-coated test tube is described for use in radioimmunoassays. The solid phase separation technique of this invention is based on a test tube which has been coated on its internal surface with two antibody layers: a first layer of nonspecific antibodies which is bound to the internal surface of the test tube and a second layer of more specific antibodies which are bound to the nonspecific antibodies. The invention is illustrated in the preparation of double antibody-coated test tubes for use in the radioimmunoassays of plasma digoxin levels and serum triiodothyronine levels. (U.K.)

[en] A method based on the principle of gel separation followed by antibody extraction (GSAE) has been developed for isolation of radioactive thyroxine (T₄), 3,5,3'-triiodothyronine (T₃), 3,3',5'-triiodothyronine (rT₃), 3,3'-diiodothyronine (3,3'-T₂), 3',5'-diiodothyronine (3',5'-T₂) and 3'-monoiodothyronine (3'-T₁) in serum. This method was used for the estimation of the metabolic clearance rate (MCR) of the iodothyronines using the single injection, non-compartmental approach, and was compared to the conventional trichloroacetic acid precipitation/ethanol extraction (TCA-E) technique. The GSAE method excluded the co-determination of radioactive iodine and iodoproetins, whereas the co-determination of radiolabelled daughter iodothyronines was found negligible. The relative difference of duplicate estimations of MCR was approximately 10%. Using the TCA-E method for isolation of tracer, the MCR of T₄, T₃ and rT₃ was underestimated to a minor degree (20%), whereas the MCRs of 3,3'-T₂, 3',5'-T₂ and 3'-T₁ were 20-40% of those estimated by the GSAE method In conclusion the GSAE method was found suitable for kinetic studies of iodothyronines, whereas the TCA-E method cannot be used for turnover studies of 3,3'-T₂, 3',5'-T₂ or 3'-T₁. (author)

[en] Measurement of triiodothyronine(T³) concentration is usful for the diagnosic and treatment of thyroid gland diseases. Fundamental studies of measurement of T³ concentration by radioimmunoassay were performed and values determined by commercially available kit, Coat-A-Count, Diagnostic Products Corporation. The optimal utilization of the radioimmunoassay in measuring T³ condentration is dependent not only on high quality performance of the assay, but also on their appropriate application to the clinical situation. These are several aspects that must be considered in every individual case. These include factors such as accurate pippeting in reagent preparation in the assay and through decanting to remove all visible moisture after incubation steps and so forth. In attempt to assesses quality control of the radioimmunoassay of serum T³, serum pools with high, medium, low T³ concentrations were assayed for each of 5 samples. The results obtained with this study were as follows: 1. The coefficient of variation (C.V.) for the standard curve ranged between 0.2-3.5%. 2. It was necessary that both incubation time and temperature should correctly be maintained all the in the assay performance. 3.The precision with the T³ RIA procedure was good. 4. The measured values of serially diluted serum T³ concentration with 0ng/dl standard solution was proportional to the predicted values. However dilution curve of distilled water was not strait. 5. Calculated T³ values of patient serum in normal group was 107.8+-25.90 ng/dl in male patient and 127.29+-24.08 ng/dl in female patient. (Author)

[en] The development of new, economic computer hardware enables the common laboratory to apply sophisticated mathematical methods in evaluation of radioimmunoassays. We describe a versatile program system for minicomputers using the spline approximation method in combination with a statistical quality control. (orig.)

No abstract available

[en] In all radioimmunoassays the bound antigen is separated from the unbound fraction (B/F-separation). A technique in which the antibody is coupled to magnetizable particles is described. The antigen-antibody complex is separated by a magnetic field. The technique is compared with an adsorbent separation process. In both cases triiodothyronine (T₃) kits are used. The magnetic method is easier to perform with the same separation capacities. (Auth.)

[en] The need for defining the assay conditions assumes greater significance for the manufacturer of RIA kits. A number of parameters were studied mainly to define the stability of the assay system to changes in the protein concentration, the influence of polyethylene glycol in various ionic media, incubation parameters for systematic error analysis in three separation systems based on dextran coated charcoal, plain polyethylene glycol and polyethylene glycol assisted second antibody. Among the three methods the second antibody employed as a complex with primary antibody assisted by polyethylene glycol had superior separation without any specific criticality. (author) 5 refs.; 5 figs.; 3 tabs

[en] Published in summary form only

[en] Thyroxine T₄ radioimmunoassay (RIA) kit has already been developed in this laboratory. For an efficient diagnosis of thyroid disease, however, it is well known that the T₃ RIA should also be carried out in addition to the T₄ RIA. Accordingly, the development of T₃ RIA kit was urgently desired to match the T₄ kit and to hold a sound domestic supply systems. The high specific activity T₃¹²⁵I about 3,000 μCi/μg T₃) could be obtained by radioiodinating T₂ with chloramine-T, and the labelled product could be stahilized. In the preparation of T₃ free serum, charcoal was eliminated easily from serum by high speed centrifugation, and the resulting T₃ free serum was used for the preparation of T₃ standard serum solutions. RIA buffer system could be improved with the use of 0.025M barbital buffer, pH 8.2, containing 0.1% BSA, 0.5% bovine aamma globulin and 0.02% merthiolate. Antibody titer was increased threefold by using the 0.025M barbital buffer; the titer was 8,000: 1 in the 0.078M borbital buffer, pH 8.6, containing 0.1% BSA and 0.1% NaN₃ while it was 26,000 : 1 in the above described 0.025M barbital buffer. The modified buffer system was also efficient for the use in T₄ RIA since it increased the T₄ antibody titer twofold. When the same buffer system was used in T₃ RIA, no significant difference was observed between the use of HSA and of BSA in so far as 0.5% bovine gamma globulin was added to the buffer, contradicting those in the reference. The resalts indicated that the cost for the preparation of both kits can be saved. Quality guaranteed kits could be prepared by careful control of the assay values in comparing with those of the reference control sera. In consequence, there is not any technical difficulty in routine production. (Author)