The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Paul W. Ladenson - One of the best experts on this subject based on the ideXlab platform.
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augmented hepatic and skeletal thyromimetic effects of Tiratricol in comparison with levothyroxine
The Journal of Clinical Endocrinology and Metabolism, 1997Co-Authors: Steven I Sherman, Matthew D Ringel, Michele J Smith, Helen A Kopelen, William A Zoghbi, Paul W. LadensonAbstract:A thyroid hormone analog with organ-selective effects could have therapeutic application for disorders such as hyperlipidemia and osteoporosis. We performed a randomized clinical trial to determine the specific thyromimetic effects of Tiratricol. Twenty-four athyreotic patients underwent detailed metabolic and physiological evaluation after a 2-month baseline period, taking TSH-suppressive doses of L-T4. They were then randomized to blinded treatment with either Tiratricol (24 micrograms/kg twice daily) or L-T4 (1.9 micrograms/kg daily). The dose of hormone was increased until the TSH level was less than 0.1 mU/L, and the metabolic and physiological testing was repeated. Comparing the change from baseline to the study drug periods, when serum TSH levels were equivalently suppressed, there were no significant differences between the two groups in resting metabolic rate, weight, urea nitrogen excretion, or symptom score. Plasma total and low density lipoprotein cholesterol levels declined 13 +/- 4% and 23 +/- 6% in the Tiratricol group compared with 2 +/- 2% and 5 +/- 3% in the L-T4 group (P = 0.015 and P = 0.0066, respectively). Serum sex hormone-binding globulin levels increased 55 +/- 13% with Tiratricol compared with a 1.7 +/- 4% decline with L-T4 (P = 0.0006), indicating an augmented hepatic response to Tiratricol. Skeletal metabolic activity was enhanced, with increased levels of serum osteocalcin and urinary excretion of calcium and pyridinium cross-links. Tiratricol and L-T4 had comparable effects on cardiovascular function. Tiratricol has distinct augmented hepatic and skeletal thyromimetic actions of potential therapeutic value.
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Organ-specific effects of Tiratricol: A thyroid hormone analog with hepatic, not pituitary, superagonist effects
Journal of Clinical Endocrinology and Metabolism, 1992Co-Authors: Steven I Sherman, Paul W. LadensonAbstract:Tiratricol has been used to suppress pituitary TSH secretion, with reported attenuation of extrapituitary thyromimetic effects. A randomized, double-blind trial was performed to define precisely the tissue-specific thyromimetic actions of Tiratricol. Ten athyreotic patients, treated for thyroid carcinoma, were randomly assigned to receive L-T4 sodium 0.7 micrograms/kg daily and either Tiratricol 10 micrograms/kg or placebo twice daily. The daily dose of L-T4 was increased by 25-50 micrograms increments until the TRH-stimulated TSH level was less than 0.1 mU/L. After measurement of biochemical and physiological parameters of thyroid hormone actions, patients crossed treatment groups. Patients required 46% less L-T4 to achieve equivalent TSH suppression when taking Tiratricol. Hepatic effects were enhanced by Tiratricol administration, with significant increases in sex hormone binding globulin and ferritin concentrations, 14% and 37%, respectively. Levels of serum cholesterol, LDL cholesterol, and apolipoprotein B were reduced by 7%, 10%, and 13%, respectively, during Tiratricol therapy. Triglyceride levels also declined, but there were no changes of high density lipoprotein cholesterol or apolipoproteins AI and AII. Resting metabolic rate, body weight, urea nitrogen excretion, and symptoms did not differ between the two treatment regimens. Cardiovascular function, as reflected by mean arterial pressure and pulse wave arrival time, was not different during Tiratricol therapy. Skeletal metabolic activity was affected by Tiratricol, with marked elevation of osteocalcin without significant change in serum calcium, PTH, and urinary calcium and hydroxyproline excretion. Tiratricol has increased hepatic and skeletal actions of potential therapeutic value, but does not have enhanced thyromimetic activity specific to the pituitary gland.
Steven I Sherman - One of the best experts on this subject based on the ideXlab platform.
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augmented hepatic and skeletal thyromimetic effects of Tiratricol in comparison with levothyroxine
The Journal of Clinical Endocrinology and Metabolism, 1997Co-Authors: Steven I Sherman, Matthew D Ringel, Michele J Smith, Helen A Kopelen, William A Zoghbi, Paul W. LadensonAbstract:A thyroid hormone analog with organ-selective effects could have therapeutic application for disorders such as hyperlipidemia and osteoporosis. We performed a randomized clinical trial to determine the specific thyromimetic effects of Tiratricol. Twenty-four athyreotic patients underwent detailed metabolic and physiological evaluation after a 2-month baseline period, taking TSH-suppressive doses of L-T4. They were then randomized to blinded treatment with either Tiratricol (24 micrograms/kg twice daily) or L-T4 (1.9 micrograms/kg daily). The dose of hormone was increased until the TSH level was less than 0.1 mU/L, and the metabolic and physiological testing was repeated. Comparing the change from baseline to the study drug periods, when serum TSH levels were equivalently suppressed, there were no significant differences between the two groups in resting metabolic rate, weight, urea nitrogen excretion, or symptom score. Plasma total and low density lipoprotein cholesterol levels declined 13 +/- 4% and 23 +/- 6% in the Tiratricol group compared with 2 +/- 2% and 5 +/- 3% in the L-T4 group (P = 0.015 and P = 0.0066, respectively). Serum sex hormone-binding globulin levels increased 55 +/- 13% with Tiratricol compared with a 1.7 +/- 4% decline with L-T4 (P = 0.0006), indicating an augmented hepatic response to Tiratricol. Skeletal metabolic activity was enhanced, with increased levels of serum osteocalcin and urinary excretion of calcium and pyridinium cross-links. Tiratricol and L-T4 had comparable effects on cardiovascular function. Tiratricol has distinct augmented hepatic and skeletal thyromimetic actions of potential therapeutic value.
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Organ-specific effects of Tiratricol: A thyroid hormone analog with hepatic, not pituitary, superagonist effects
Journal of Clinical Endocrinology and Metabolism, 1992Co-Authors: Steven I Sherman, Paul W. LadensonAbstract:Tiratricol has been used to suppress pituitary TSH secretion, with reported attenuation of extrapituitary thyromimetic effects. A randomized, double-blind trial was performed to define precisely the tissue-specific thyromimetic actions of Tiratricol. Ten athyreotic patients, treated for thyroid carcinoma, were randomly assigned to receive L-T4 sodium 0.7 micrograms/kg daily and either Tiratricol 10 micrograms/kg or placebo twice daily. The daily dose of L-T4 was increased by 25-50 micrograms increments until the TRH-stimulated TSH level was less than 0.1 mU/L. After measurement of biochemical and physiological parameters of thyroid hormone actions, patients crossed treatment groups. Patients required 46% less L-T4 to achieve equivalent TSH suppression when taking Tiratricol. Hepatic effects were enhanced by Tiratricol administration, with significant increases in sex hormone binding globulin and ferritin concentrations, 14% and 37%, respectively. Levels of serum cholesterol, LDL cholesterol, and apolipoprotein B were reduced by 7%, 10%, and 13%, respectively, during Tiratricol therapy. Triglyceride levels also declined, but there were no changes of high density lipoprotein cholesterol or apolipoproteins AI and AII. Resting metabolic rate, body weight, urea nitrogen excretion, and symptoms did not differ between the two treatment regimens. Cardiovascular function, as reflected by mean arterial pressure and pulse wave arrival time, was not different during Tiratricol therapy. Skeletal metabolic activity was affected by Tiratricol, with marked elevation of osteocalcin without significant change in serum calcium, PTH, and urinary calcium and hydroxyproline excretion. Tiratricol has increased hepatic and skeletal actions of potential therapeutic value, but does not have enhanced thyromimetic activity specific to the pituitary gland.
Andrew L Hodge - One of the best experts on this subject based on the ideXlab platform.
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a report of hypothyroidism induced by an over the counter fat loss supplement Tiratricol
International Journal of Sport Nutrition and Exercise Metabolism, 2003Co-Authors: Michael C Scally, Andrew L HodgeAbstract:Prior to presentation, two physically fit adults, a 39-year-old male and 40-year-old female, began supplementation with an over-the-counter thyroid preparation marketed as a metabolic accelerator and fat loss aid, Tiratricol. Both participants took the supplement for 5 weeks (3000–4000 mcg/d) and 3 weeks (6000 mcg/d), respectively. At presentation, both complained of lethargy, loss of appetite, and muscle weakness. Upon initial laboratory evaluation, results revealed low thyroid stimulating hormone with profoundly elevated T3 values in both patients. After an extensive review of the literature, the cause of the problem was found to be the nutritional supplement they consumed contained Tiratricol. After discontinuation of the supplement, thyroid levels slowly returned to baseline 40 days and 5 months later, respectively.
Michael D Brennan - One of the best experts on this subject based on the ideXlab platform.
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symptomatic hyperthyroidism in a patient taking the dietary supplement Tiratricol
Mayo Clinic proceedings, 2002Co-Authors: Brent A Bauer, Peter L Elkin, Dana Erickson, George G Klee, Michael D BrennanAbstract:An 87-year-old woman was referred for evaluation of nervousness, tremor, insomnia, and fatigue of 2 months' duration. Initial laboratory evaluation revealed a suppressed thyrotropin level and an elevated triiodothyronine level. A review of her medications revealed that she had started taking several dietary supplements at the recommendation of her chiropractor before the onset of symptoms. One of these was Tiratricol (3,5,3'-triiodothyroacetic acid or Triac), a substance sold as a dietary supplement despite classification as a drug by the Food and Drug Administration. Tiratricol has weak thyromimetic effects, can inhibit pituitary thyrotropin secretion, and in higher doses can significantly stimulate metabolism. Such was the case with this patient who presented with signs, symptoms, and biochemical evidence of hyperthyroidism that promptly resolved after discontinuation of Tiratricol therapy. To our knowledge, this is the first reported case of documented thyrotoxicosis secondary to Tiratricol use. Because Tiratricol is still available for sale on several Internet sites, this case emphasizes the importance of inquiring about the use of dietary supplements in all patients. The availability of such products on the Internet increases the already complex task of monitoring patients' use of dietary supplements.
Yooheon Park - One of the best experts on this subject based on the ideXlab platform.
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Development and characterization of a human cell line-based transactivation assay to assess thyroid EDCs.
Environmental research, 2020Co-Authors: Seok-hee Lee, Hyeyeong Seo, Hee-seok Lee, Yooheon ParkAbstract:Abstract Thyroid hormones (THs) are one of the most important hormones, playing key roles in the regulation of various physiological functions. Although THs have important function in human, in vitro test methods based on human cells are currently insufficient to effectively screen and test TH-related endocrine disrupting chemicals (EDCs). We established a TH agonist TA assay using the adenocarcinomic human alveolar basal epithelial cell line A549 to test and screen potential TH agonists. To establish the TH agonist TA assay, a TRE-secNluc-IRES-EGFP reporter cassette was constructed and transfected into the A549 cell line using a retrovirus. We evaluated the TH agonistic properties of several chemicals which were tested by existing thyroid agonists testing method (OECD GD 207). Comparing the results of the TH agonist TA assay with the OECD GD 207, T3, T4, Tiratricol, and tetrac (natural TH and 3,3′,5,5′-tetraiodothyroacetic acid derivatives), which are TH agonists according to the OECD GD 207, also tested positive in the TH agonist TA assay using the A549 cell line. These results suggested that the TH agonist TA assay developed in this study using a human cell line can provide the information, such as accuracy and specificity to TH agonistic properties of chemicals.