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[en] When determining ''D.P.D.'' free oxidizers, the monochloramine interfers in particular for iodide levels analogous to those likely to be found in sea water. This is not so for iodate. The zero time extrapolation of the change in colour curve is one method that enables the method to be made more selective
[fr]Lors du dosage des oxydants, libres a la D.P.D., la monochloramine interfere notablement pour les teneurs en iodure analogues a celles susceptibles d'etre rencontrees en eau de mer. Ce n'est pas le cas de l'iodate. L'extrapolation au temps zero de la courbe d'evolution de la coloration est une methode qui permet de rendre la methode plus selective
[en] 125I-Labelling of human thyrotropin (h-TSH) Was performed using a small amount of chloramine T (CT) as an oxidant at room temperature. When compared with the conventional method that uses a large amount of CT, this method facilitated uniform labelling and reduced the damage of h-TSH by CT, a strong oxidizing reagent. h-TSH prepared by the new method was comparable to the commercial product of Daiichi Company, in terms of affinity to antibody and effective period.
[en] Radioiodine labelled human follicle stimulating hormone has been prepared using chloramine-T, with the approximate labelling yield of 65%. The labelled product is purified by means of a starch gel electrophoresis, and a Sephadex gel filtration, and the separation efficiencies are assessed for the effective use in radioimmunoassay. The results indicate that the gel filtration is efficient in view of the separation time, simplicity and bindability of the labelled hormone to the antibody. In determining the ratio of the free to the antibody bound labelled hormone, a double antibody technique is applied in comparison with a chromatoelectrophoresis. The ratio could be obtained only in the case of applying the double antibody technique.
[en] Preparation and quality control of HBsAg and anti-HBs RIA/IRMA kits, which are applied for detection of hepatitis B virus and its antibody have been done. I-125-HBsAg and I-125-anti HBs used for tracer, prepared by iodination method using chloramine-T as an oxidizing agent. HBsAg and anti-HBs polystyrene coated bead were used as a separating agent. It was found the HBsAg and Anti HBs RIA/IRMA reagents prepared, have reasonably good quality. I-125-HBsAg as well as I-125-anti HBs gave a high yield, (59,55% and 80,75% respectively, with more than 90% radiochemical purity, and P/N > 136 and 150. HBsAg and anti HBs coated bead also gave a good performance. The density and dissociation index were 0,58 - 0,69 and 0,21 - 0,42% for anti-HBs coated bead and 0,15 - 0,66 and 1,8 - 5,1 % for HBsAg coated bead. The positive and negative ratio given by HBsAg and anti-HBs reagents prepared in this work is satisfactory, (P/N = 89 and 136) which is higher than the requirement (>20). From comparison study performed against CIAE RIA kits, the sensitivity and specificity of the reagents prepared, are very high, 100%
[en] An experiment has been done to assess the optimum condition necessary for obtaining a maximum yield in the production of L-thyroxine 131I. The following factors : pH, carrier iodide and mole ratio of L-thyroxine to Chloramine-T are considered important. Physical and chemical tests of the final product were performed according to the established quality control procedures. (author)
[en] Cetrizine dihydrochloride (CTZH) is widely used as an anti-allergic drug. Sodium N-bromo-p-toluenesulfonamide or bromamine-T (BAT) is the bromine analogue of chloramine-T (CAT) and is found to be a better oxidizing agent than CAT. In the present research, the kinetics of oxidation of CTZH with BAT in acid and alkaline media was studied at 313 K. The experimental rate laws obtained are: -d[BAT]/dt = k[BAT] [CTZH]0.80[H+]-0.48 in acid medium and -d[BAT]/dt = k[BAT][CTZH]0.48[OH-]0.52[PTS]-0.40 in alkaline medium where PTS is p-toluenesulfonamide. Activation parameters and reaction constants were evaluated. The solvent isotope effect was studied using D2O. The dielectric effect is positive. The stoichiometry of the reaction was found to be 1:1 and the oxidation products were identified as 4-chlorobenzophenone and (2-piperazin-1-yl-ethoxy)-acetic acid in both media. The rate of oxidation of CTZH is faster in acid medium. Suitable mechanisms and related rate laws have been worked out
[en] Labeling of Nimesulide with iodine-125 and its biological evaluation is described. "1"2"5I-Nim was prepared by electrophilic substitution of nimesulide with "1"2"5I using chloramine-T as an oxidizing agent . The labeling yield percentage obtained was 95.1 % using 200μg Nimesulide, 300 μg chloramine-T and Na "1"2"5I carrier-free at ph 7 within 1 min as a reaction time. The labeled drug was stable up to 48 h post labeling. Biodistribution study of "1"2"5I - Nim in tumor bearing mice showed that it is localized in tissues with a high proliferation rate with preferential accumulation in cancerous tissues. "1"2"5I-Nim was incorporated rapidly in the tumor site and declined slowly wh ile declined rapidly from other tissues. I n-vitro cell growth inhibition assay stated that the therapeutic activity of "1"2"5I-Nim was significantly increased with the increase of radioactivity by decreasing cell surviving fraction when examined on EAC cells. The percentage survival in tumor bearing mice was the best when starting treatment with 125 I - Nim at the third day after inoculation. It also revealed that locoregional administration of "1"2"5I-Nim resulted in higher percentage survival than the intravenous route. This study may introduce a new radiotherapeutic agent which could be used in tumor imaging and therapy
[en] When labeled to monoclonal antibodies (MAbs) or their fragments, 123I can be used for imaging or for predicting the treatment potential and radiation dosimetry of 131I labeled to the same molecular species. Because 123I (p,5n) from the Crocker Nuclear Laboratory is in dilute solution, when compared with commercial 125I of labeling grade, we have evaluated labeling parameters using Chloramine-T as the oxidant and derived an optimum set of labeling conditions that provide a 60-80% radiochemical yield of highly immunoreactive antibody. When Lym-1, an IgG-2a murine antibody against human lymphoma, was used, yields of labeled immunoglobulin were decreased by protein or Chloramine-T concentrations less than 0.4 microgram/microliter and 0.8 microgram/microliter, respectively; denaturation of the immunoglobulin occurred when the Chloramine-T concentration was greater than 1.0 microgram/microliter. Optimum labeling occurred at pH 7-8 with deleterious effects when the pH was below 5 or above 10. An optimum method for labeling antibodies with multimillicurie amounts of 123I (less than one iodine atom per 100 antibody molecules) is described. Some of the observations derived from this study are also applicable to the preparation of treatment doses of 131I-labeled antibodies, wherein the amount of antibody can be a restrictive factor