The Journal of clinical endocrinology and metabolism
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J. Clin. Endocrinol. Metab. · Jul 2001
RET/PTC rearrangements in thyroid nodules: studies in irradiated and not irradiated, malignant and benign thyroid lesions in children and adults.
Rearrangements of the RET proto-oncogene may occur in both naturally occurring and radiation-induced papillary thyroid carcinomas. Conflicting results on the frequency and type of RET/PTC rearrangements have been reported in relation to age, radiation exposure, and histological tumor variant. We designed the present study to evaluate in a single laboratory, using the same methodologies, the pattern of RET/PTC activation in thyroid tumors from different groups of patients (exposed or not exposed to radiation, children or adults, with benign or malignant tumors) in relationship to the above mentioned variables. ⋯ The relative frequency of RET/PTC1 and RET/PTC3 in rearranged benign tumors showed no major difference. In conclusion, our results indicate that the presence of RET/PTC rearrangements in thyroid tumors is not restricted to the malignant phenotype, is not higher in radiation-induced tumors compared with those naturally occurring, is not different after exposure to radioiodine or external radiation, and is not dependent from young age. Other factors, probably influenced by ethnic or genetic background, may act independently from or in cooperation with radiation, to trigger the DNA damage leading to RET proto-oncogene activation.
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J. Clin. Endocrinol. Metab. · Jul 2001
Lactate and glycerol release from adipose tissue in lean, obese, and diabetic women from South Africa.
Abnormalities observed in intermediary metabolism may be related to the pathogenesis of obesity-related diseases such as type 2 diabetes. Glycerol and lactate production was estimated in the sc adipose tissue of two anatomical regions of 10 lean (LW), 10 obese (OW), and 10 matched diabetic (DW) black urban women. This was done with the sc microdialysis technique and combined with adipose tissue blood flow (ATBF) rates calculated from (133)Xe clearance. ⋯ Obesity in the black population is therefore characterized by a marked degree of adipose tissue lipolysis. This degree of resistance together with increasing body fat mass may predispose the obese women to developing type 2 diabetes. Once this disease is established, the onset of adipose tissue vascular insulin resistance will sustain ongoing insulin resistance, even in the presence of relative insulinopenia.
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J. Clin. Endocrinol. Metab. · Jul 2001
Low concentrations of the histone deacetylase inhibitor, depsipeptide (FR901228), increase expression of the Na(+)/I(-) symporter and iodine accumulation in poorly differentiated thyroid carcinoma cells.
Thyroid carcinoma accounts for the majority of deaths from endocrine cancers. A major cause of treatment failure is the inability to trap iodine. Chemotherapeutic agents with differentiating properties have been tried in an attempt to increase iodine uptake. ⋯ Depsipeptide induced increases in (125)I accumulation indicated that a functional Na(+)/I(-) symporter protein was induced. Transient transfections indicate that the effects are mediated at least in part by a trans-activating factor. These in vitro results suggest that depsipeptide or other histone deacetylase inhibitors might be used clinically in thyroid carcinomas that are unable to trap iodine as an adjunct to radioiodine therapy.
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J. Clin. Endocrinol. Metab. · Jul 2001
Evaluation of the hypothalamic-pituitary-adrenal axis in children with leukemia before and after 6 weeks of high-dose glucocorticoid therapy.
Among the adverse effects arising from chronic high-dose glucocorticoid treatment, adrenal insufficiency secondary to suppression of the hypothalamic-pituitary-adrenal (HPA) axis is a cause for concern. Glucocorticoid-induced adrenal suppression is related to the duration of therapy, type of steroid used and dosage, and schedule of glucocorticoid administration. To evaluate the suppression and recovery time of the HPA axis in children with acute leukemia, we performed the ovine CRH (oCRH) stimulation test in 15 patients, who were given high doses of dexamethasone as part of their induction chemotherapy for 42 days. ⋯ One of these patients had manifestations of mild adrenal insufficiency, 6-8 days after discontinuation of therapy, but required no glucocorticoid coverage. We conclude that up to 2 weeks after discontinuation of 6 weeks of high-dose dexamethasone administration, the HPA axis of patients with acute leukemia is mildly suppressed but infrequently associated with clinical manifestations of adrenal insufficiency. This may indicate that major stress, when concurrent with glucocorticoid treatment, may prevent clinically significant adrenal suppression.