The article reviewed dietary iodine reference intakes for different populations constituted by major countries and international organizations. Lowor high iodine intake can renderrisks to human health and there are different cut-points of iodineexcess for susceptible population. Universal salt iodization demonstratedthe influence on the spectrum of thyroid diseases and its benefitsoutweighrisks since its significant benefits on human potential and quality of life. This article has suggested practical evaluation indicators for certification of sufficient iodine intaketo keep adequate iodine intake for population.

The choline acetyltransferase (CHAT) and the molecular forms of acetyl-cholinesterase (ACHE) activites in various brain regions of 20-day-old hypothyroid and hyper-thyroid rats were measured. The results provided the following information: 1) CHAT and ACHE activities were directly interrelated with thyroid hormones. 2) In both hypothyroid and hyperthyroid rats the nonextractable ACHE activity was distinctly decreased in every brain region, suggesting that both conditions were affected in the critical period of cholinergic synaptic development. 3) The ratio of membrane-bound ACHE to soluble ACHE decreased;it showed that thyroid hormone deficiency might distrub development and maturation of cholinergic neurons. 4) In most regions of the central nervous system,the CHAT seemed to be more affected than ACHE by thyroid hormones.

The effects of different iodide intakes on the thyroid sodium iodide symporter (NIS) mRNA expression, thyroid hormones, urinary iodine and tissue iodine in thyroid were observed. NIS mRNA expression was elevated; and urinary iodine, thyroid tissue iodine and thyroid hormones were significantly lowered in low iodine group. In high iodine group, NIS mRNA expression was inhibited and thyroid hormones decreased. The results show that NIS is the important component of this autoregulatory mechanism. Both low and high iodine intakes can lead to hypothyroidism.

Objective:To study the master iodine nutrition status of population living in areas with different iodine in drinking water and the cut-off point of stopping iodized salt supply and the range of adequate iodine intake for the strategy of prevention from iodine deficiency or excess. Method:Thirteen townships points along the Yellow River downstream in Shandong were investigated and divided into six groups(A-F) based on water iodine concentrations of 0-50,50-100,100-150,150-300,300-800 and over 800 ?g/L. The indicators of water iodine,edible salt iodine,urinary iodine(UI) and thyroid goiter were observed. Results:From A,B,C,D,E and F group,the medians of water iodine concentration were 20.3,91.4,143.2,203.6,341.9 and 812.3 ?g/L,of edible salt iodine were 0,25.7,25.8,30.4,36.4 and 33.0 mg/kg,and of UI were 116.8,354.2,400.4,607.9,881.3 and 1 213.8 ?g/L respectively. The goiter rates were 10.8,8.6,15.0,14.2,14.9 and 25.0 % respectively . The sample proportion of UI below 100 ?g/L was 8.2%,of 100-300 ?g/L was 18.2% and of over 300 ?g/L was 73.6%. Frequency excursion of UI had a high trend towards water iodine concentration over 90?g/L in 5 groups. The proportion of UI over 300 ?g/L increased,consistent with higher water iodine level. Median UI of all groups with iodized salt decreased significantly,especially group F. There were significant correlations between UI and water iodine. Iodine nutrition status was markedly excessive in group B,C,D,E and F. Conclusions:Iodine nutrition status of most residents consuming drinking water with iodine concentration about 20 ?g/L should be adequately supplied with eligible iodized salt. Iodine intakes in groups B-F were excessive,and iodized salt supply should be stopped there. The cut-point of water iodine level where iodized salt stopped could possibly be 90 ?g/L,and the range of adequate iodine intake,in terms of drinking water,could be defined at range of over 20 to 90 ?g/L in iodine concentration.

FRTL cells were incubated in the culture medium containing 10 -6 -10-3 mol/L KI for 24, 48 and 72 h, and the levels of sodium iodide symporter (NIS) mRNA and protein were measured using RT-PCR and Western blot. The levels of NIS mRNA in FRTL cells incubated with different concentrations of iodide for 24 and 48 h showed no significant difference as compared with the control group, however, NIS protein was reduced gradually in FRTL cells incubated with different concentrations of iodide for 48 and 72 h as compared with that in control group. The higher the iodide concentration, the lower the levels of NIS protein. The results show that acute iodine excess does not affect the expression of NIS mRNA, but down-regulates NIS protein expression. Iodine excess may regulate the expression of NIS through post-transcription.

Thyroid function ultimately depends on appropriate iodine supply to the gland. Thyroid hormone deiodination is an intrinsic component of the thyroid hormone homeostasis. Type Ⅰ iodothyronine deiodinase (D1) plays an important role in thyroid hormone metabolism and has close relationship with thyroid function. Based on successfully establishing animal models of iodine deficiency and iodine excess in Babl/c mice (Babl/c mice were randomly divided into five groups: low iodine (LI), normal iodine (NI), five-fold iodine (5HI) , ten-fold iodine (10HI) and fifty-fold iodine (50HI) group. Three months and six months after admistration, they were sacrificed and thyroids were excised), the expression level of D1 mRNA were examined by using real time quantitative PCR method. D1 activity was analyzed by 125I-rT3 as substrate combined with ion-exchange chromatography. The thyroid hormone was measured with radioimmunoassay method. The data revealed that in the case of iodine deficiency, both D1 mRNA expression and D1 activity was greatly increased(compared with NI groups, P

Objective:To investigate the effects of exogenous hydrogen peroxide(H_2O_2)on mitochondrial superoxide production and mitochondrial membrane potential changes(△ψ)in fisher rat thyroid cell line(FRTL).Methods:Following 1 mmol/L H_2O_2 exposure in FRTL cells for 10 min,30 min and 24 h,mitochondrial superoxide production was measured by living cell imaging and flow cytometry using MitoSOX.The mitochondrial membrane potential was assayed by spectrofluorimeter and fluorescent microscopy using rhodamine 123(rh123).The cell viability was detected by MTT colorimetric method.Morphological changes were observed by invert microscope.Apoptosis assay was performed by acridine orange staining.Results:Quantitative measurements of the mean intensities of MitoSOX demonstrated significant increase with 1 mmol/L H_2O_2 following 10 min,30 min and 24 h treatment in FRTL cells compared with that of control.Fluorescence intensity of rh123 and optical density of MTr were significantly decreased in FRTL ceils with 1 mmol/L H_2O_2 following 30 min and 24 h treatment(P ＜ 0.01).Under light microscope and fluorescence microscope the characteristic morphological features of programmed cell death,pickuosis,karyorrhexis,and cell shrinkage were observed after acridine orange staining.Conclusion:Acute and chronic exogenous H_2O_2 exposure cause oxide stress in FRTL cells,which result in the increase of mitochondrial superoxide production,△ψdecline,cell necrosis and apoptosis.

BACKGROUND: Triiodothyronine (T3) is an important regulation factor at the critical period of brain development. It maybe control the successive differentiation during the development of central nervous system (CNS).OBJECTIVE: To monitor the differentiation of neural stem cells (NSCs) induced by T3 and the thyroid hormone receptor (TR) mRNA expression changes.DESIGN: Open experiment.SETTING: Department of Pathology, Tianjin Medical College of Chinese People's Armed Police Force; Institute of Endocrinology of Tianjin Medical University.MATERIALS: This study was carried out in the Tianjin Medical University between January 2003 and March 2005.Ten-to-twelve-week-old aborted fetuses were obtained from the General Hospital of Tianjin Medical University with the approval of the local ethical committee. Informed consents were obtained from the mothers and their relatives.METHODS: ①Under the aseptic condition, the bilateral cortex of human fetal brain was removed and dissociated by brief mechanical trituration in D-Hanks. Then, 20 μg/L bFGF and 30 nmol/L T3 were used to induce the proliferation of NSCs and inoculated to poly-L-lysine-coated 24-well plate and 25 mL culture flask for routine culture at 1 ×109 L-1. The culture medium was DMEM/F12 serum-free complemented with N2. Half of the culture medium was changed every 48 hours.Seven days later, bFGF was discarded, only T3 was used for induction and differentiation. ② At 1, 2 and 3 weeks of culture, cells were collected, and RT-PCR was semiquantitatively used to detect TR mRNA expression changes at different stages of differentiation of NSCs. Isoforms were identified by immuocytochemistry.MAIN OUTCOME MEASURES: ①Cellular morphology observation and isoforms identification before and after differentiation of NSCs induced by T3. ② TR mRNA expression changes during the differentiation of NSCs.RESULTS: ①The hNSCs were round and had a smooth surface and gradually gathered to neurospheres. The proliferative hNSCs were nestin-positive and incorporated BrdU. When NSCs were induced by T3 for one week, most of the cells took on monopole or double poles, and had long and thin processes. The differentiated cells were neurofilament protein (NFP)-positive, galactocerebroside (GC)-positive or glial fibrillary acidic protein (GFAP)-positive. When NSCs were induced by T3 for three weeks, most of the cells were big, with unclear cell membrane, round nucleus, many thick processes which had many branches. The spider-like cells were scattered, and 80% of the cells were myelin basic protein-positive. ② TRα1 mRNA expression level was the highest before inducing NSCs. With the induction of T3, the expression level was decreased gradually, and was the lowest at 2 weeks, and then was rebounded gradually, but the final level was still lower than that of NSC (F =32.49, P =0.008). The tendency of TRα2 mRNA expression alteration was identical with that of TRα1 mRNA. TRβ1 mRNA expression level was the lowest in NSC, was increased gradually with the induction of T3 and attained the highest level at 2 weeks of induction of T3. Furthermore, the expression level of TRβ1 mRNA was also higher than that of TRα1 at the same time (t =15.64,P =0.001), and it reached the lowest level at 3 weeks of the induction. TRα3 expression level was firstly decreased after the differentiation induced by T3, and was close to the expression level of NSC at 2 weeks of induction (F =51.94, P =0.378), then was decreased to lower lever.CONCLUSION: T3 can induce NSC to differentiate into neurons, oligodendrocyte and astrocytes. TR mRNAs are expressed in different time intervals during the differentiation of NSCs.

Objective:To observe the effect of different iodine intake on the thyroid function in euthyroid adult persons.Methods:One hundred and sixty-one euthyroid healthy volunteers aged 18-24 years were randomly divided into 7 groups.Each group was assigned to receive 500 μg,750 μg,1 000 μg,1 250 μg,1 500 μg,and 2 000 μg iodide/day for four weeks.Serum concentrations of free triiodothyronine(FT3),free thyroxin(FT4)and sensitive thyroid-stimulating hormone(sTSH)were measured by chemolumineseenee assays.Results:Serum FT3 concentration was found a small decline within the normal range in all the iodide supplemented groups(P ＜ 0.05).The level of FT4 was significantly lower,when the dose was up to 1 500 μg (P ＜ 0.05).The level of serum sTSH was increased after 2 weeks iodide supplement in all groups,and after 4 weeks in 500 μg and 750 μg groups(P ＜ 0.05).No significant changes were observed in FT3,FT4 and sTSH between groups(P＞ 0.05).Conclusion:The thyroid function of normal people showed a rise in serum sTSH at a short time and a high-dose of iodine intake.

Objective To observe and compare the different orthotopic models of papillary thyroid cancer ( PTC) cell lines of RET/PTC1 rearrangement and BRAFV600E mutation in nude mice. Methods Human PTC cell lines TPC-1, BHP5-16 and BHP2-7 were used. The genotypes of RET/PTC1 rearrangement and BRAFV600E mutation were determined by realtime-PCR and DNA sequencing analysis. The cells(2×105) were injected into the thyroid gland of nude mice. The nude mice were executed at 4th, 12th week, and then their thyroid tumors were removed and weighed. The levels of thyroid hormone were detected using chemiluminescent immunoassay. Results Both TPC-1 and BHP2-7 cells were identified as RET/PTC1 rearrangement by real time-PCR, and the expression of RET/PTC1 rearrangement in BHP2-7 cell was higher than that of TPC-1 cell. BRAFV600E mutation was found in BHP5-16 cell by DNA sequencing analysis, but was not found in TPC-1 and BHP2-7 cells. There were different characteristics in three orthotopic nude model groups. Tumorigenic rates of TPC-1 and BHP5-16 groups were 100%, but the growth of tumor was more rapid in BHP5-16 group than that in TPC-1 group, with more weight tumor. The changes of thyroid hormone levels in BHP5-16 group and TPC-1 group were the same, which were normal at 4th week and sharply decreased at 12 th week(P<0. 05). However, the tumorigenic rate of BHP2-7 group was only 6. 25%. Compared with normal control group, there was no statistical difference in the levels of thyroid hormone in BHP2-7group(P>0. 05). Conclusions It showed difference in the orthotopic models of PTC cell lines of RET/PTC1 rearrangement and BRAFV600E mutation in nude mice. BRAFV600E mutation has obvious impacts on increasing tumorigenic rate and promotion of tumor growth in the orthotopic model. It should not be ignored that advanced thyroid tumor will lead to the destruction of thyroid function.