• Toxicological Research
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• v.16 no.1
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• pp.27-31
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• 2000

Recently, there is a worldwide concern that a great number of man-made chemicals have a hormone-like action both in humans and in animals. EPA and OECD are developing screening programs using validated test systems to determine whether certain substances may have an effect on humans. In the present study, the establishment of in vivo short-term test system for pubertal female assay with thyroid to detect endocrine disrupting chemicals was tried using a model substance, methoxychlor (MC), a chlorinated hydrocarbon insencticide. Forty female rats were assigned to four groups. MC was administered at dose levels of 0, 8, 40 and 200mg/kg by gavage to female rats from day 21 post partum to the completion of vaginal opening. We evaluated body weight change, age at vaginal opening, onset of estrous cyclicity, age at first esturs, ovary weight, and serum concentrations of thyroxine and thyroid stimulating hormone in female rats. The age at vaginal opening of females receiving 40 200mg/kg was significantly younger than control. The onset of estrus cyclicity and age at first estrus of females receiving 200mg/kg was also younger than controls. There was no effect of treatment on body weight, ovary weight, and hormone concentration. Based on these results, it can be concluded that application of MC at dose level of 40mg/kg affects the vaginal opening and application of MC at dose level of 200mg/kg accelerates the vaginal opening and the onset of estrus cylicity.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.2
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• pp.132-140
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• 2006

Well-differentiated thyroid cancer is the most common endocrine malignancy with an increasing incidence. Most patients with well-differentiated thyroid caner have a favorable prognosis with high survival rate. While surgery and radioiodine therapy is sufficient treatment for the majority of patients with differentiated thyroid cancer, a minority of these patients experiences progressive, life-threatening growth and metastatic spread of the disease. Because there is no prospective controlled study to evaluate the differences of management of thyroid cancer, it is hard to choose the best treatment option. And there are still lots of controversies about the management of this disease, such as surgical extent, proper use of radioiodine for remnant ablation and therapy, use of rhTSH instead of withdrawal of thyroid hormone, long-term follow-up strategy, thyroglobulin as a tumor marker, etc. In this review, recent data related to these conflicting issues and recent advances in diagnosis, radioiodine therapy and long-term monitoring of well-differentiated thyroid cancer are summarized.

• Journal of Aquaculture
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• v.8 no.2
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• pp.133-140
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• 1995

Olive flounder (Paralichthys olivaceus) larvae of pre-metamorphic and early metamorphic stage were treated with different concentrations of triiodothyroxine $(T_3)\;and\; thyroxine\;(T_4)$ by immersion (0.02, 0.04, 0.08 and 0.16 ppm) for 11 days. Although $T_3$ was more potent than $T_4,\;both\;T_3\;and\;T_4$ accelerated the settlement time of fish larvae. Duration upto complete settlement in hormone-treated groups was significantly shorter than that in controls. Survival of hormone-treated groups at the pre-metamorphic stage decreased as hormone concentrations increased, however groups treated at the early metamorphic stage were not differ from control. Growth rates of groups treated with high concentration of hormone were slightly lower than that of control except 0.02ppm $T_4$ treated group.

• The Korean Journal of Physiology
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• v.26 no.2
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• pp.99-111
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• 1992

Permissive action of thyroid hormone at the level of Ca channel and responsible mechanisms underlying thyroid hormone-induced change in myocardial contractile state and $T_3-induced$ arrhythmias were investigated in rabbit ventricular or atrial myocytes using whole cell patch clamp technique. Single cells were isolated by Langendorff perfusion with collagenase. Cardiac myocytes were incubated in $low-Cl^-,$, $high-K^+$ medium containing $1_{\mu}M\;L-triiodothyronine\;(T_3)$ at $4^{\circ}C$ for 2.10 hours. The calcium currrent $(I_{Ca})$ was increased in $T_3$ loaded cells, however, the shape of current voltage curve and reverse potential did not altered. Cyclic AMP, cyclic GMP, isoprenaline and 3-isobutyl-1-methyl-xanthine increased $I_{Ca}$ in euthyroid and hyperthyroid conditions, and acetylcholine blocked the increase of $I_{Ca}\;in\;T_3$ loaded cells. The amplitude of $I_{Ca}$ was much larger after perfusing cGMP than cGMP in both conditions, whereas the degree of increase of $I_{Ca}$ was greater after perfusing cAMP than cGMP in $T_3$ loaded cells. The degree of increase of $I_{Ca}$ after perfusing isoprenaline or IBMX also was greater in $T_3$ loaded cells than in control cells. Background current induced by isoprenaline also increased in $T_3$ loaded cells. The Ca release dependent inward current was increased in amplitude but its activation and inactivation time course was not changed in $T_3$ loaded cells. Activation of Na pump current was not changed in $T_3$ loaded cells. From the above results it is suggested that thyroid hormone induced increase in the contractile state of cardiac myocytes are accompanied by augmented $I_{Ca}$ and the increase of Ca release from sarcoplasmic reticulum and the permissive action of thyroid hormone to catecholamines could induce arrhythmias through the increase of $I_{Ca}$ and background current.

• Clinical and Experimental Pediatrics
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• v.57 no.10
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• pp.425-433
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• 2014

Adrenal and thyroid hormones are essential for the regulation of intrauterine homeostasis, and for the timely differentiation and maturation of fetal organs. These hormones play complex roles during fetal life, and are believed to underlie the cellular communication that coordinates maternal-fetal interactions. They serve to modulate the functional adaptation for extrauterine life during the perinatal period. The pathophysiology of systemic vasopressor-resistant hypotension is associated with low levels of circulating cortisol, a result of immaturity of hypothalamic-pituitary-adrenal axis in preterm infants under stress. Over the past few decades, studies in preterm infants have shown abnormal clinical findings that suggest adrenal or thyroid dysfunction, yet the criteria used to diagnose adrenal insufficiency in preterm infants continue to be arbitrary. In addition, although hypothyroidism is frequently observed in extremely low gestational age infants, the benefits of thyroid hormone replacement therapy remain controversial. Screening methods for congenital hypothyroidism or congenital adrenal hyperplasia in the preterm neonate are inconclusive. Thus, further understanding of fetal and perinatal adrenal and thyroid function will provide an insight into the management of adrenal and thyroid function in the preterm infant.

• The Korean Journal of Nuclear Medicine
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• v.19 no.1
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• pp.29-36
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• 1985

The results of radioiodine treatment of 88 patients are reported. As in the case presented above, careful follow-up with continuous administration of adequate amount of thyroid hormone is very important. To check whether recurrent lesions have appeared or not, scintigrams with test dose of $I^{131}$, usually 1 to 10 mCi, are taken in general. However, it is important that there is a fact that administration of much larger dose (30 to 100 mCi) of $I^{131}$ may result in presenting additional lesions on the scintigrams. Recently, clinical usefulness of serum thyroglobulin determination has been mentioned in literatures from the standpoint of follow-up study of patients after radioiodine treatment. Although this technique seems to be valuable, we have to be aware of the possibility of fluctuation of data which may occur in connection with administration of thyroid hormone. Finally, I would like to say that radioiodine treatment is an effective method for thyroid cancer if patients are adequately selected. However, radioiodine treatment itself is sometimes not enough from the standpoint of radiation dose to the lesions. In such cases, we should not hesitate to consider combination therapy with other modalities. Therefore, in order to overcome this undesirable disease, cooperation between nuclear medicine specialists and other oncologists, such as radiotherapists, is necessary.

• Journal of Medicine and Life Science
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• v.19 no.3
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• pp.95-102
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• 2022

This retrospective study aimed to investigate whether there was a difference in the success rate of removal of residual thyroid tissue in patients with the same cutoff serum thyroglobulin (Tg) value-measured 2 weeks after thyroid hormone withdrawal (THW)-for different radioactive iodine (RAI) activities. We identified 132 patients with papillary thyroid cancer who were treated with total thyroidectomy and RAI therapy to evaluate the efficacy of three radioactivities of I-131: 1,110, 3,700, and 5,550 MBq. Serum Tg testing was performed 1 week before RAI treatment and 2 weeks after THW (pre-Tg); the cutoff pre-Tg level was below 10 ng/mL. Stimulated Tg levels were measured on the day of I-131 administration (off-Tg). After 6 months of treatment, we compared the groups for complete ablation, defined as no uptake on a diagnostic I-131 scan, stimulated Tg level of <1.0 ng/mL, and Tg antibody level of <100 ng/mL. Ninety-five patients (72.0%) achieved complete ablation, with 57.1% (8/14), 78.2% (68/87), and 61.3% (19/31) in the 1,110 MBq, 3,700 MBq, and 5,550 MBq groups, respectively. There was no significant difference in the complete ablation rates between the three groups. In the multivariate analysis, the off-Tg level was a significant predictor of complete ablation. RAI therapy with low radioactivity (1,110 MBq) seemed sufficient for ablation in patients with papillary thyroid cancer with a pre-Tg level below 10 ng/mL. The off-Tg level is a promising and useful predictor of complete ablation after initial RAI therapy.

• Clinical and Experimental Pediatrics
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• v.48 no.8
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• pp.799-805
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• 2005

Hypothyroidism is a deficiency in thyroid hormone secretion by the thyroid gland and a defect in thyroid hormonal receptor activity. It is categorized by the two major forms in children, the one is congenital hypothyroidism and the other is acquired hypothyroidism. Congenital hypothyroidism is one of the commonest treatable causes of mental retardation and occurs in 1 in 3,000-4,000 infants worldwide. Acquired hypothyroidism is a diseases that have an onset usually after 6 months of age and it may be relate to deceleration in linear growth. The objectives of this article are obtain general and practical concepts of congenital and acquired hypothyroidism during infancy, childhood, and adolescence.

• Neonatal Medicine
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• v.16 no.2
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• pp.244-247
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• 2009

Thyroid hemiagenesis is a rare congenital anomaly in which one thyroid lobe fails to develop. Thyroid hemiagenesis usually does not cause clinical symptoms by itself, therefore, this anomaly is detected incidentally during the evaluation of other thyroid disorders. We describe a rare case of thyroid hemiagenesis in a 1-month-old female infant who presented with prolonged jaundice and abnormal laboratory findings of congenital hypothyroidism. The patient showed the characteristic features of thyroid hemiagenesis of the left lobe in Tc-99m pertechnetate scintigraphy and ultrasonography of the thyroid gland. The patient has improved with supportive care, including thyroid hormone replacement. Further long-term follow-up is required for the investigation of recurrence of thyroid abnormalities.

• Korean Journal of Head & Neck Oncology
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• v.17 no.1
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• pp.56-58
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• 2001

Anaplastic thyroid carcinoma, which is one of the most aggressive tumors of the thyroid, has been seldomly reposted to have altered thyroid function. There have been few reports of patients with anaplastic thyroid cancer presenting in a hyperthyroid state. In the literatures, the mechanism of hyperthyroidism in anaplastic thyroid cancer is supposed that the rapid invasive growth of cancer seems to cause destruction of thyroid tissue and develops a hyperthyroid state, which is thought to be anlalogous to that of subacute thyroiditis and several types of metastatic cancer of the thyroid: rapid tissue necrosis with resultant release of thyroid hormone. Recently, we experienced a case of anaplastic thyroid cancer presenting with rapid growing mass and hyperthyroidism in a 67-year-old woman and report it with the review of the literatures.