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Results for “Iodine Radioisotopes”

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[Comparative study of the titre of circulating antibodies and the results of the iodine radioisotope indication test of the thyroid gland in chronic autoimmune thyroiditis].

A total of 293 patients with chronic autoimmune thyroiditis were observed. The circulating antibody titre to thyroglobulin was determined and 131I-radioindication of the thyroid gland was made in 65 patients. The mentioned studies were diagnostically informative in the complex examination of patients with chronic autoimmune thyroiditis.

Adolescent↗
PubMed1979

Thyroid imaging with iodine-125 and technetium-99m.

Eighty-eight patients referred consecutively for thyroid imaging were studied. Each patient was scanned with a 3'' rectilinear scanner using both 125I and 99mTc. The paired scans were evaluated independently by two physicians experienced in thyroid evaluation and image analysis. The images were ranked on a scale from 1 to 5 as follows: 1) 125I scan much better than the 99mTc scan, 2) ..., 3) 125I scan and 99mTc scan the same, 4) ..., 5) 99mTc scan much better than 125I scan. The scores were statistically analyzed by the sign test and transformed normal score methods. Categories analyzed were: A. Hypothyroid, B. Euthyroid, C. Hyperthroid, (A-C based upon RAIU measurements), D. Cold Nodules, E. Graves Disease, F. Hot-Nodules, G. Multinodular Nontoxic Goiter, H. Miscellaneous and I. Normal. The significance of this study is that regardless of the classification we used, in no category was the 99mTc scan considered better than the 125I scan. This finding is at variance with the observations of some others comparing 99mTc with other iodine radioisotopes. 99mTc may have some procedural advantages and does deliver a lower radidation dose to the thyroid.

Adult↗
PubMed1979

Dual-isotope separation technique for radioassay. Precision of calculated results affected by degree of separation.

The dual-isotope separation technique for radioassay is reviewed. An expression is derived describing the effect of counting errors on the precision of the calculated bound count rate in the dual-isotope technique. This mathematic model is tested in experiments using sodium iothalamate (I-125) as a marker in the Phadebas radiosorbent assay of cobalamin (Co-57). The coefficient of variation of results calculated on the basis of the dual-isotope technique is shown to be dependent on the amount of supernatant removed. The conclusion is that relatively large amounts of the supernatant must be removed before counting if the dual-isotope technique is to give acceptable results. The experimental model is proposed as a simple test of the suitability of a projected dual-isotope system.

Analysis of Variance↗
PubMed1975

Rdiotoxicity of intracellular 67Ga, 125I and 3H. Nuclear versus cytoplasmic radiation effects in murine L1210 leukaemia.

L1210 leukaemia cells were labelled with various doses of 67Ga-citrate, 3H-thymidine, or 125I-iododeoxyuridine to evaluate the cytocidal effects of the intracellular decay of the three radionuclides. Based on radioisotope incorporation data, cellular dimensions, and intracellular radioisotope distributions (3H and 125I intranuclear, 67Ga cytoplasmic) the rates of deposition of cellular, nuclear, and cytoplasmic energy were calculated. In terms of energy absorption/cell, 67Ga (LD50: 2250 keV/hr; 69 rad/hr) was much less toxic than either 3H (LD50: 325 keV/hr; 10 rad/hr) of 125I (LD50:50 keV/hr; 1-5 rad/hr). In terms of energy absorption/nuclesu, 67Ga and 3H produced almost identical effects (LD50: 230 versus 255 keV/hr; 22-2 versus 24-6 rad/hr), but 125I remained much more toxic (LD50: 40 keV/hr; 3-9 rad/hr). These findings indicate that, although decay by electron capture in the cell nucleus (125I) is highly destructive, the same type of decay occurring in the cytoplasm (67Ga) is ineffective in killing L1210 cells. An analysis of the data suggests that the cytotoxic effects of the three radioisotopes result exclusively from nuclear damage. Cytoplasmic absorption of radiation energy appears to contribute little, if anything, to the lethal effects of ionizing radiations.

Animals↗
PubMed1978

Simultaneous canine tracheal transport of different particles.

We describe a method to study simultaneously the transport of 2 different markers in the canine trachea. In our studies, we found that choice of radioisotopic label and variation in marker size from 3 to 180 micrometer did not affect the transport rate of basic anion exchange resin particles. Furthermore, anion exchange and acidic cation exchange particles of the same size had similar tracheal transport rates. This method may help to determine the influence of the physicochemical properties of markers on mucous transport.

Animals↗
PubMed1978

Accumulation of radionuclides by plants as a monitor system.

The accumulation of radionuclides by plants acting as a monitoring system in the environment may occur by two modes; foliar absorption by the leaves and shoot of the plant, or by root uptake from the soil. Data on plant accumulation of radionuclides may be obtained from studies of fission product radionuclides deposited as worldwide fallout, and from tracer studies of plant physiology. The epidermal features of plant foliage may exert an effect upon particle retention by leaves, and subsequent uptake of radionuclides from the surface. The transport of radionuclides across the cuticle and epidermis of plant leaves is determined in part by the anatomy of the leaf, and by physiological factors. The foliar uptake of fallout radionuclides, 99Sr, 131I, and 137Cs, is described with examples from the scientific literature. The environmental half-life of 131I, for example, is considerably shorter than its physical half-life because of physical and biological factors which may produce a half-life as short as 0.23/day. 99Sr and 137Cs are readily taken up by the leaf, but 137Cs undergoes more translocation into fruit and seeds than 99Sr which tends to remain in the plant part in which it was initially absorbed. Soil-root uptake is conditioned primarily by soil chemical and physical factors which may selectively retain a radionuclide, such as 137Cs. The presence of organic matter, inorganic colloids (clay), and competing elements will strongly affect the uptake of 99Sr and 137Cs by plants from the soil. The role of plants as monitors of radionuclides is twofold: as monitors of recent atmospheric releases of radionuclides; and as indicators of the long-term behavior of aged deposits of radionuclides in the soil.

Absorption↗
PubMed1977

Medullary carcinoma of the thyroid gland.

Out of the discovery of concurrent multiple endocrine neoplasms has evolved the concept of multiple endocrine adenomatosis (MEA1 and MEA2). Medullary carcinoma of the thyroid gland is the most constant facet of MEA2 and is derived from C-cells of the neural crest. These cells, resembling parafollicular cells of lower animals, elaborate calcitonin which acts as a sensitive signal of the presence of the tumor. Ninety per cent of MCT occurs sporadically; in 10% the tumor presents as an atuosomal dominant trait. Other endocrinopathies, especially pheochromocytomas, are present in 70% of cases. The lesions are "cold" on iodine radioisotope scan. On microscopic examination, the appearance of amyloid is characteristic. Regional lymph node metastasis occurs early. The tumor deserves appropriate aggressive management. Surgical therapy should begin early and vigorously with the minimum procedure being total thyroidectomy. Frequent lymph node metastasis speaks for the need for regional neck dissection extended into the superior mediastinum. The search for, and the treatment of, the frequently associated endocrinopathies is essential. Pheochromocytoma must be suspected and eradicated before treatment of the thyroid tumor. A genetic workup should be included.

Adolescent↗
PubMed1979

Microdosimetric measurements of ionization by some radioisotopes.

Microdosimetry has been a fast growing field in dosimetry during the last years. We have measured and calculated microdosimetric quantities which are important in correlation between the energy deposited in microscopic volumes and the biological effect. We have measured the energy distribution spectra in volumes with diameters of 1 and 2 mum and calculated the dose mean of specific energy and the mean event number per unit absorbed dose for the radioisotopes: 60Co, 137Cs, 99Tcm, 125J and the beta emitter 90Sr.

Cesium Radioisotopes↗