Increased Radioiodine Uptake Research Articles

Radioisotope determination of apical seal integrity of silver point-filled endodontic teeth after ultrasonic vibration

Twenty-six human mandibular incisors with single root canals were instrumented and obturated with silver points and sealer. The efficacy of the initial seal was tested by immersion in radioiodine and counted for gamma radiation. Subsequently, the teeth were subjected to the vibration of an ultrasonic scaling device and reimmersed in the isotope so that the integrity of the apical seal could be re-evaluated as a function of increased radioiodine uptake and, thus, increased gamma radiation. No significant difference was found after use of the Cavitron device.

Effets de la photopériode et du taux d'androgène circulant sur la fonction thyroïdienne du Canard

Thyroid function has been studied in male ducks under various experimental conditions, including: (1) controls reared in a natural light environment (december); (2) natural light + 14 days i.m. testosterone (10 mg/day); (3) 14 days exposure to an 18L-6D light regimen; (4) 14 days at 18L-6D + testosterone (10 mg/day); (5) castration; (6) castration + testosterone (10 mg/day); (7) castration + 14 days at 18L-6D. Castration was followed: (a) at the thyroid level by an increased radioiodine uptake, and, among the labeled iodoamino acids, an increased radiothyroxine ratio; (b) at the peripheral level, by an increased ratio of unbound radiothyroxine (Sephadex); and by an increased biological half-life ( t 1 2 ) of labeled thyroxine. Testosterone injections led to opposite effects, and reversed the situation in castrates. Testosterone seems therefore to inhibit thyroid function, while it increases the peripheral metabolism of thyroid hormones. Testosterone-thyroid interrelationships must be kept in mind when considering the effects of “long days” photoperiods on thyroid function. However, “long days” per se may act on thyroid function, as evidenced in the castrates, by decreasing (1) the radioiodine uptake and (2) the PB 125I (Sephadex). On the other hand, exposure to increased lighting regimens inhibits the stimulating effect of testosterone on the peripheral metabolism of thyroxine. In the present experiments, “long days” photoperiods seem thus to exert an inhibitory effect on thyroid function, although this environmental factor has been claimed to stimulate the pituitary thyrotropic activity in birds.

Goiters with high radioiodine uptake and other characteristics of iodine deficiency in rats chronically treated with aminoglutethimide.

In experiments with rats, small doses of the antithyroid drug aminoglutethimide (AG), given as a single injection (2 mg) or as an admixture to an iodine-enriched diet for a few days, had a propylthiouracil-like action on thyroidal radioiodine metabolism characterized by a decrease of uptake, organic binding, release of labeled PBI and synthesis of iodothyronines. However, chronic administration of AG for more than 3 weeks produced small goiters characterized by an increase of radioiodine uptake and organic binding and an accelerated release of labeled PBI, while iodothyronine synthesis returned to control levels. With labeling times of 4 hr or less, the iodoaminoacid distribution within these goiters still revealed the antithyroid action of AG, whereas 48 hr after labeling the distribution of the tracer on chromatograms was hardly any different from that usually reported for goiters produced by moderate iodine deficiency. Double labeling experiments using 125I, administered with the drinking water for 50 ...

Interaction of thyrotropin or the long-acting thyroid stimulator with theophylline.

Theophylline in multiple doses of 1.0 mg increased radioiodine uptake in thyroid hormone-treated mice and had an effect equivalent to that of 1 mU thyrotropin on the 131I distribution in thyroid gland hydrolysates. Multiple doses of 0.5 mg theophylline alone had no effect on thyroid 131I uptake but potentiated the increase in uptake produced by LATS at 2 dose levels. In doses of 1.0 mg, theophylline potentiated the effects of both thyrotropin and LATS in altering the proportions of 131I-labeled components in thyroid gland hydrolysates, suggesting potentiation of the influence of these agents on thyroid hormone synthesis. (Endocrinology 83: 309,1968)

Endemic goiter in Greece: an iodine balance study in the field.

ABSTRACT Iodine balance studies were carried out in the homes of 15 goitrous and 15 nongoitrous females in a Greek village with endemic goiter, and radioiodine techniques were used to evaluate iodine metabolism in the same subjects. The mean ±se dietary iodine intake of the goitrous (21.2 ±2.2 μg/day) was not significantly different from the nongoitrous (30.6 ±8.5), whereas the urinary iodine excretion was significantly reduced in the former group. The fecal iodine excretion was 5.1 ±0.16 and 6.4 ±0.39 μg/day in the goitrous and the nongoitrous, respectively. This latter group was apparently in a negative iodine balance. Quantitative studies of iodine metabolism revealed that, although the plasma inorganic iodine level was low in both groups studied, the greatly increased radioiodine uptake resulted in a significantly higher absolute iodine uptake in the goitrous. However, in spite of greater iodide trapping, the trend for slightly lower PBI and BEI values could be taken as indirect evidence against an in...

Thyroid Function Tests

Introduction Thyroid function during the first weeks of life is characterized by hyperactivity as measured by increased radioiodine uptake, increased serum hormonal iodine values, and increased erythrocyte triiodothyronine I 131 uptake. This neonatal thyroid hyperactivity subsides within one to two weeks and the elevated test results have returned to normal childhood levels by 8 to 12 weeks of age. 1 There are relatively few reports characterizing and correlating thyroid function tests during childhood subsequent to this period. Radioiodine uptake tests on normal children summarized by Andersen 2 and Diwany et al 3 have been, for the most part, late uptake studies (24-48 hours) and have shown considerable variation with geographic area. Adequate comparisons with adult values by similar methodology and characterization of I 127 excretion have generally not been available. Investigations of serum hormonal iodine values in normal children have been few. 4-6 Values have been reported to be significantly

The in vitro stimulation of thyroidal activity by propylthiouracil.

In vitro studies indicated that a small amount of propylthiouracil (10-8M) added to the medium significantly increased the total uptake of radioiodine by rat thyroid slices under both aerobic and anaerobic conditions, and significantly increased radioiodine uptake by sheep thyroid slices under aerobic conditions. Chromatography of the propylthiouracil treated slices indicated a significant increase in total radioactivity, a decrease in the ratio of radioiodide to organic radioiodine compounds (I-/Io), and a decrease in the ratio of radiomonoiodotyrosine to radiodiiodotyrosine (MIT/DIT). There was, in addition, a significant increase in oxygen consumption by rat thyroid slices when treated with small amounts of propylthiouracil. The in vitro results indicate a direct stimulatory effect by small amounts of propylthiouracil on both rat and sheep thyroid slices resulting in an increase in oxygen consumption, radioiodine uptake, and radiodiiodotyrosine formation.

Radioiodine uptake by the infarcted heart

An increased uptake of radioiodine by the infarcted heart has been reported by us previously. Forty-nine patients have now been investigated: twenty-three patients with recent myocardial infarction, twenty-one control patients and five patients in whom exact diagnostic classification as to the presence or absence of infarction was impossible. In all patients with infarction, an increased radioiodine uptake over the area of the heart in comparison with the corresponding area on the right side of the chest could be observed. The increased left-to-right ratio appeared after twenty-four to forty-eight hours and was also noticeable at least on the sixth, the seventh or the eighth day after iodine administration. The 100 μc. dose of I 131 seems to be a suitable one with the instruments employed. The phenomenon of increased radioiodine uptake by the infarcted heart, although its nature is still poorly understood, appears to have some clinical diagnostic value.

INFLUENCE OF OESTROGENS ON TSH-THYROID RELATIONSHIP

SUMMARY 1. Oestradiol benzoate in a dosage range of 10-1000 μg. administered daily for a week to castrated male rats enhances the thyroid weight and increases the uptake of radioactive iodine by the thyroid. There is, however, no clear-cut quantitative relation between dosage of oestrogens and effect on the thyroid. 2. In hypophysectomized rats oestrogens enhance the action of T. S. H. on thyroid weight and radioactive iodine uptake, though, in the absence of T. S. H., they have by themselves no »thyrotrophic« action. The enhancement increases with increasing doses of oestrogens. 3. It is concluded that oestrogens influence the thyroid in two ways, viz. by diminishing the release of T. S. H. by the hypophysis and by sensitizing the thyroid to the effect of T. S. H. 4. The abovementioned conclusion is supported by control experiments, performed in order to eliminate possible objections: a. The transformation of inorganic iodides into organically bound iodine is not inhibited by oestrogens. b. Although oestrogens cause a slight diminution of the urinary iodine excretion, we were able to show that this could not be the only factor responsible for the observed increase in radioiodine uptake in the thyroid. c. Even in vitro isolated thyroids from oestrogen treated rats show a larger uptake of radioiodine from the medium.