Toxic Effects of Tetrabromobisphenol A on Thyroid Hormones in SD Rats and the Derived-reference Dose

The present study determined the thyroid hormone interference of tetrabromobisphenol A （TBBPA） in Sprague-Dawley （SD） rats, and the derived-reference dose （RfD） of different endpoint effects on mammals based on experimental results and data collection. Based on repeated exposure toxicity tests on mammals and extensive research, the present study used BMDS240 Software to derive a benchmark dose, and analyzed the accuracy and uncertainty, and similarity with other studies. Test results on triiodothyronine （T3）, thyroxine （T4）, and thyroid stimulating hormone （TSH） demonstrated that all the indicators presented a non-monotonous dose-effect relationship clearly, except TSH in male rats exposed to 0-1000 mg/kg BW per day. Therefore, RfDs were derived from different critical effects. In summary, RfD for mammals in the present study was found to be 0.6 mg/kg per day.

Effects of topiramate and carbamazepine on thyroid hormone level in adults with epilepsy

BACKGROUND: It has been demonstrated that traditional antiepileptics, such as phenytoin, carbamazepine (CBZ), phenobarbital, etc., can result in the decrease of thyroid hormone of epileptic patients. However, there is still no sufficient evidence for the studies about the effect of new-type antiepileptics, such as topiramate (TPM), on thyroid hormones. OBJECTIVE: To observe the effects of TPM and CBZ on the level of thyroid hormones in serum of adults with epilepsy. DESIGN: A comparative observation. SETTING: Department of Neurology, Sichuan Provincial People's Hospital. PARTICIPANTS: Totally 100 outpatients or inpatients newly diagnosed to have epilepsy were selected from the Department of Neurology, Sichuan Provincial People's Hospital from July 2003 to August 2005, including 60 males and 40 females, aged 18-70 years. All the patients were accorded with the standard for the classification of epilepsy set by International League Against Epilepsy (ILAE) in 1981; Had been Informed and agreed with the detection; Had no history of thyroid gland disease; Had not taken any drugs could affect the thyroid function. Meanwhile, 40 adult healthy examinees were selected from our hospital as the control group, including 24 males and 16 females, aged 18-65 years. METHODS: ① The 100 epileptic patients were randomly divided into TPM group (n =50) and CBZ group (n =50), and they were treated with TPM (Xian-Janssen Pharmaceutical, Ltd.; Batch number: 03AS032, Norm: 25 mg/tablet) and CBZ (Shanghai Sunve Pharmaceutical Co., Ltd.; Batch number: 030201, Norm: 100 mg/tablet) respectively. The initial dosage of TPM was 25 mg per day, increased by 25 mg every week, the objective dosage of 100-200 mg per day was maintained when the symptoms were satisfactorily controlled. The dosage of CBZ was 6-8 mg/kg per day. All the patients were administrated for 1 year. ② The serum levels of total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3) and thyroid stimulating hormone (TSH) in the epileptic patients were detected by means of chemiluminescence before treatment and at 3, 6 and 12 months after treatment respectively. ③Standards for judging curative effects: Controlled by without seizure, the frequency of seizure reduced by ≥ 75% was taken as significant effect, reduced by 50%-74% as effect, and reduced by < 49% as invalid, whereas increased by more than 20% was taken as aggravation. ④ The intergroup and intragroup differences of the measurement data were compared by the analysis of variance and paired t test respectively. MAIN OUTCOME MEASURES: Serum levels of thyroid hormones before treatment and at different time points after treatment of TPM and CBZ. RESULTS: All the 100 epileptic patients and 40 healthy subjects were involved in the analysis of results. ① Changes of serum levels of thyroid hormones: The serum levels of TT3, TT4, FT3, FT4 and TSH were close between the epileptic patients and normal subjects before treatment (P > 0.05). In the CBZ group, the serum levels of FT4 at 3, 6 and 12 months after treatment [(16.87±3.77), (16.34±3.98) , (16.97±3.95) pmol/L] were significantly decreased as compared with those before treatment [(18.00±3.54) pmol/L, t =2.74, 3.50, 2.26, P < 0.05]; The levels of TT3 at 3, 6 and 12 months [(2.09±0.54), (1.99±0.49), (1.84±0.47) nmol/L] were significantly decreased as compared with those before treatment [(2.22±0.63) nmol/L, t =2.73, 2.78, 5.18, P < 0.05]. The levels of TT3 at 6 and 12 months [(109.65±23.98), (107.72±23.90) nmol/L] were significantly decreased as compared with those before treatment [(118.98±28.48) nmol/L, t =3.11, 3.30, P < 0.05]. TT4 level in serum at 3 months and the levels of FT3 and TSH at each time point after CBZ treatment had no obvious changes as compared with those before treatment (P > 0.05). In the TPM group, the levels of thyroid hormones at each time point had no obvious changes as compared with those before treatment (P > 0.05). ② Curative effects: Of the 100 epileptic patients, it was controlled in 12 cases, significantly effective in 30 cases, effective in 39 cases and invalid in 19 cases, the total effective rate was 81% (81/100). CONCLUSION: CBZ treatment can lead to the decreases of thyroid hormones in adult epileptic patients. Epilepsy itself and TPM treatment cannot change the thyroid hormones in adult epileptic patients, which suggests that TPM treatment is safer for the thyroid function of adult epileptic patients.

Feeding Supplemental lodine to Adult Mink;Effect on Thyroid Hormones in Adult and offspring

We fed adult mink diets containing supplemental iodine, from 0 to 320 ppm, for one or seven months prior to breeding. Blood samples collected from the adults and their offspring (kits) at 4 wk post-partum were assayed for total thyroxine (T4), triiodothyronine (T3), reverse T3 (rT3), and T4-binding indices. As expected T4 concentrations of the adult and kit mink varied inversely with the level of supplemental iodine. In addition, T3 and rT3 concentrations decreased gradually in kits from the long-term experiment in response to the increased dietary iodine of the dams. T3 concentrations of kits from dams fed iodine short-term decreased markedly while rTy concentrations were elevated greatly in response to increased dietary iodine of the dam. These decreases in hormone levels are due to serum iodine blocking the thyroid uptake of iodine and subsequent decrease of hormone synthesis. Excess iodine may also block the effect of thyroid stimulating hormone. The T4-binding indices of the adults, in general, were depressed, while the T4-binding indices of the kits were more variable. These effects are probably due to fluctuations in thyroglobulin.

Effect of thyroid hormone on serum NO concentration and iNOS activity of intestinal mucosa in septic rats

Objective To investigate the effect of exogenous thyroid hormone on serum NO and iNOS activity of intestinal mucosa in septic rats. Methods Septic model was established by cecal ligation puncture (CLP) in male SD rats. Triiodothyronine ( T3 ) was administered intraperitoneally to correct the low T3 syndrome of septic rats. Blood was collected to examine serum NO and thyroid hormone concentration. Intestinal mucosa iNOS activity was assayed using immunochemical stain. Results Mortality rate in the prevention group was significantly lower than the septic group (Log rank = 3. 85, P 【 0.05). Serum NO concentration was significantly lower in the prevention group (F=19.6,F【0.01). The degree of inflammatory injury of intestinal mucosa was much milder in the prevention group than in the septic group (x2 = 5.303,P【0. 05). Mucosa iNOS activity was also significantly lower in the prevention group (x2 = 4. 876, P【0. 01). Conclusion Thyroid hormone protects the intestinal mucosa barrier inhibiting the expression of

Human biological monitoring of suspected .ndocrine-disrupting compounds

Endocrine-disrupting compounds are exogenous agents that interfere with the natural hormones of the body. Human biological monitoring is a powerful method for monitoring exposure to endocrine disrupting compounds. In this review, we describe human biological monitoring systems for different groups of endocrine disrupting compounds, polychiorinated biphenyls, brominated flame retardants, phthalates, alkylphenols, pesticides, metals, perfluronated compounds, parabens, ultraviolet filters, and organic solvents. The aspects discussed are origin to exposure, metabolism, matrices to analyse, analytical determination methods, determinants, and time trends.

EFFECTS OF PARATHYROID HORMONE AND ESTRADIOL ON PROLIFERATION AND FUNCTION OF HUMAN OSTEOBLASTS FROM FETAL LONG BONE AN IN VITRO STUDY

The effect of parathyroid hormone (PTH) (0.01 nM-10 nM) and 17 -estradiol (E2, 1 nmol-10 nM) alone or in combination on 3H thymidine incorporation, alkaline phosphatase and adenylate cyclase activities were investigated in human fetal osteoblasts using serum-free monolayer primary cultures. The results showed that PTH inhibited cell proliferation while E, promoted it. On alkaline phosphatase activity, PTH showed a complex results while E, were slightly inhibitory. PHT-E2 combination suggested that E2 could alter the effect of PTH alone, also potentiated the anabolic and antagonize the catabolic effects of PTH on bone formation.

The effects of thyroid-stimulating hormone,estradiol and prolactin on sodium/iodide symporter mRNA expression in mouse lactating mammary gland cells under different iodine levels

Objective The present study investigated the sodium/iodide symporter mRNA expression in mouse lactating mammary gland cells under different iodine levels and the effects of thyroid-stimulating hormone(TSH),estradiol(E2)and prolactin(PRL)on NIS mRNA expression in mouse lactating mammary gland cells.

SYMPTOMATIC HEMODYNAMIC AND HORMONAL EFFECTS OF INTRAVENOUS CAPTOPRIL IN PATIENTS WITH HEART FAILURE

Since only oral preparations of captopril are clinically available, intravenous captopril was studied in 10 patients with mild heart failure and in 20 severe. The results showed that intravenous captopril may rapidly reduce cardiac preload and afterload, increase cardiac output, inhibit renin-angiotensin-aldosterone system, and depress plasma levels of catecholamine. After captopril infusion, a rapid symptomatic improvement occurred and the infusion could be well tolerated in patients with acute or severe heart failure. In addition, reversing hyponatremia and hypokalemia or improving azotemia may benefit the patients with acute or severe heart failure.