A possible mechanism for 2,2',4,4',5,5'-hexachlorobiphenyl-mediated decrease in serum thyroxine level in mice

Serum total thyroxine (T₄) level was markedly decreased, without significant increases in the levels of hepatic T₄-UDP-glucuronosyltransferase (T₄-UGT) and serum thyroid-stimulating hormone, 3 days after treatment with 2,2′,4,4′,5,5′-hexachlorobiphenyl (CB153) (100 mg/kg, ip) in both 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-sensitive C57BL/6 and TCDD-resistant DBA/2 mice. Likewise, in either strain of mice, no CB153-mediated changes in the binding levels of [¹²⁵I]T₄ to serum proteins, such as transthyretin, albumin, and thyroxine binding globulin, were observed, while in CB153-pretreated C57BL/6 mice, but not in CB153-pretreated DBA/2 mice, the levels of biliary [¹²⁵I]T₄ and [¹²⁵I]T₄-glucuronide at 90-120 min after injection of [¹²⁵I]T₄ slightly increased, as compared with those in the corresponding control mice. Concerning tissue distribution of [¹²⁵I]T₄, liver-selective increases in the [¹²⁵I]T₄ accumulation by CB153-pretreatment were observed in both C57BL/6 and DBA/2 mice, and the hepatic levels of [¹²⁵I]T₄ in the C57BL/6 and DBA/2 mice became more than 44% and 34% of the [¹²⁵I]T₄ dosed, respectively. The present findings indicated that the CB153-mediated decreases in the level of serum total T₄ in C57BL/6 and DBA/2 mice occur mainly through an increase in the accumulation of T₄ in the liver.     

Effects of selenium depletion and selenium repletion by choice feeding on selenium status of young and old laying hens

We investigated the effect of choice feeding two diets with different selenium (Se) content to young and old moderately Se-deficient laying hens on serum Se (SSe), glutathione peroxidase (GPX), vitamin E, creatine kinase (CK), aspartate aminotransferase (ASAT), thyroxine (T4) and triiodothyronine (T3). Each of two consecutive study parts (I and II) with the same hens and treatments began with a 6-week baseline period (Medium-Se diet), followed by a 9-week depletion period (Low-Se or Medium-Se diet), followed by a 6-week choice period with two different diets offered simultaneously (Medium-Se/Low-Se, Medium-Se/High-Se, or Low-Se/High-Se). During both depletion periods, SSe and GPX gradually decreased, whereas T4 gradually increased in hens fed Low-Se confirming gradual Se-depletion. T3 decreased transiently in young hens only. As reported earlier, Se-deficient hens preferred High-Se over Low-Se diet during the first 3 weeks of choice feeding in part I, not however in part II. This preference resulted in higher SSe in these hens. GPX activity did not reflect feed preference, probably because Se-intake exceeded Se-requirement for maximal GPX activity. In Part II, hens depleted with Low-Se diet had higher SSe when previously offered High-Se diet in either combination, than when offered Low-Se/Medium-Se, presumably due to Se-stores built during choice feeding in part I, which possibly prevented development of Se-deficiency in part II. In addition, in older hens, Se depletion proceeded faster, whereas Se-repletion by choice feeding was slower than in young hens, indicating the increase in Se requirement with advancing age. Vitamin E, ASAT and CK remained largely unchanged by the treatments.     

Environmental lead exposure, maternal thyroid function, and childhood growth

Prenatal and early-life exposure to lead is hypothesized to have a range of adverse effects on childhood health. Drawing on data collected from a population-based prospective cohort study of a highly exposed town and a low exposed town in Kosovo, Yugoslavia we assessed whether elevated maternal blood lead (BPb) concentrations during pregnancy were associated with reduced childhood measures of attained height and BMI or growth rate, and whether the associations, if any, were mediated by maternal thyroid hormone concentration at mid-pregnancy. There was no association between blood lead levels and height or BMI in either town. However, increased maternal thyroid hormone was unexpectedly associated with reduced attained childhood height, and growth rate of height from 6.5 to 10 years, in the low-exposure town. We examine potential reasons for this unexpected inverse association.     

正常范围甲状腺激素水平与冠状动脉Gensini评分的相关性分析

Abstrat：Objective To study the correlation between normal level of thyroid hormone and gensini coronary scoring system．Methods 233 patients who were treated with CAG and diagnosed of patients with coronary heart disease were divided into 4 groups based on gensini coronary scoring system ,all the patients were determined kinds of index which include triiodothyronine(T3),thyronine(T4),free thyronine(FT4), free triiodothyronine (FT3), thyroid stimulating hormone (TSH) and correlation between thyroid hormone level and gensini coronary scoring system was studied by Spearman correlation analysis and Multiple regression analysis.Results No significant difference was found in the levels of triiodothyronine(T3),thyronine(T4),freethyronine(FT4),Cholesterol(CHO)andTriglyceride(TG) between the 4 groups(P>0．05).FT3 and HDL-C decreased with the increase of the degree of coronary artery lesions（P<0.01）, AGE and LDL-C increased with the increase of the degreeof coronary artery lesions(P<0.05),there was statistical significance.Negative linear correlation was found between the gensini coronary scoring system and FT3、HDL-c,was positively correlated with age and LDL-C .both the index Was independently correlated to Gensini integral.Conclusion the lower level of FT3 is an indepent risk factor for lesion severity of CHD．      

左甲状腺素钠对妊娠早期甲状腺过氧化物酶抗体阴性的亚临床甲状腺功能减退患者围产结局的影响

目的 探讨左甲状腺素钠(L-T4)对妊娠早期伴甲状腺过氧化物酶抗体(TPoAb)阴性的亚临床甲状腺功能减退(甲减)患者围产结局的影响。方法 选择就诊的妊娠早期亚临床甲减伴TPoAb阴性患者1 140例,随机分为L-T4组(n=570)和对照组(n=570),L-T4组给予L-T4治疗并达到目标值[促甲状腺素(TSH)<2.5 mU/L],对照组不进行相应治疗。观察两组患者妊娠高血压、贫血、流产、早产及新生儿体质量等相关指标。结果 对照组妊娠高血压、贫血、流产率及早产率等指标显著高于L-T4组(P＜0.05),顺产率显著低于L-T4组,并且L-T4组患者治疗达目标值所需L-T4剂量与患者的TSH水平呈明显正相关(r=0.763,P＜0.05)。结论 L-T4可以明显改善妊娠早期伴TPoAb抗体阴性的亚临床甲状腺功能减退患者的围产结局。     

妊娠期甲状腺减退患者妊娠期间左旋甲状腺素钠替代剂量探讨

目的 探讨妊娠甲状腺功能减退症(甲减)妊娠期间左旋甲状腺素钠替代剂量。方法 2014年3月至 2015年3月入选在我院分娩的274例妊娠合并甲减孕妇,其中亚临床型甲减组(SHT)207例,临床型甲减组(HT)67 例,以妊娠早期促甲状腺激素(TSH)<2.5mU/L,妊娠中晚期TSH<3.0mU/L为治疗目标,根据TSH 及孕周变化 予调整左旋甲状腺素钠治疗剂量。并根据TSH 水平分为TSH1 组,TSH3~5mU/L,TSH2 组,TSH5~8mU/L, TSH3 组,TSH8~10mU/L,TSH4 组,TSH10~15mU/L,TSH5 组,TSH15~20 mU/L 和TSH6 组,TSH>20 mU/L。结果 各组达治疗目标后,SHT 组T1、T2 和T3 期,左旋甲状腺素钠剂量分别为:(52.26±19.43)μg、 (56.69±20.58)μg和(56.76±19.99)μg;HT组在T1、T2 和T3 期,左旋甲状腺素钠剂量分别为:(64.58±50.26) μg、(66.67±47.64)μg和(65.91±34.06)μg;TSH1 组-TSH6 组左旋甲状腺素钠剂量分别为(45.65±16.08)μg、 (72.32±14.85)μg、(75.00±13.06)μg、(112.5±53.03)μg、(137.5±23.18)μg和(150.00±23.13)μg;T1、T2 和 T3 妊娠期TSH2、TSH3、TSH4 和TSH5 组左旋甲状腺素钠剂量高于TSH1 组(P <0.05);TSH4、TSH5 和TSH6 组 左旋甲状腺素钠片剂量高于TSH2 组(P <0.05);TSH4、TSH5 和TSH6 组高于TSH3 组(P <0.05);TSH5 和 TSH6 组高于TSH4 组(P <0.05);TSH6 组高于TSH5 组(P <0.05)。结论 妊娠期临床型甲减左旋甲状腺素钠 剂量在T1、T2 和T3 妊娠期均高于亚临床型甲减(P <0.05)。随着TSH 水平增高,所需左旋甲状腺素钠明显增加 (P <0.05)。     

碘过量的危害及相关机制

碘是合成甲状腺激素和维持机体正常生理功能的重要元素。碘过量可引起甲状腺功能减退、 甲状腺功能 亢进、 自身免疫性甲状腺疾病等, 不同个体对碘过量的易感性不同, 过度的氧化应激及继发的免疫反应可能是碘过 量引起甲状腺细胞毒性的潜在机制。本文对碘过量的流行病学现状、 推荐摄入量和摄入来源、 机体对碘过量的调节 机制及其相关致病机制做一综述。     

妊娠期甲状腺功能减退症的诊治进展

甲状腺功能减退症（甲减）是妊娠期最常见的甲状腺功能异常。妊娠期甲减包括临床甲减和亚临床甲减 （SCH）。SCH （患病率 3%~5%） 比临床甲减 （<1%） 常见。目前, 临床倾向采用妊娠特异性促甲状腺激素 （TSH） 和血清 游离甲状腺素 （FT4） 参考值诊断妊娠期甲减。妊娠前已确诊的临床甲减在妊娠期间需增加血清左甲状腺素 （L-T4） 的剂量; 而妊娠期新诊断的临床甲减, 应立即给予 L-T4 治疗并尽快使 TSH 水平达到目标值。对于 SCH, 虽然对母 胎获益的相关临床研究结果不一致, 国内外指南的治疗建议也不尽相同, 但是, 最近几年的研究提示对 SCH 无论是 否伴有甲状腺自身抗体阳性均可考虑治疗。本文就妊娠期临床甲减及 SCH 诊治相关的研究现状进行综述。     

PNPLA3 polymorphism influences the association between high-normal TSH level and NASH in euthyroid adults with biopsy-proven NAFLD

AimWe aimed to evaluate the association between serum thyroid stimulating hormone (TSH) levels, within the reference range, and the histological severity of nonalcoholic fatty liver disease (NAFLD), and whether this association was modulated by the patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism.Materials and methodsWe enrolled 327 euthyroid individuals with biopsy-proven NAFLD, who were subdivided into two groups, i.e., a ‘strict-normal’ TSH group (TSH level 0.4 to 2.5 mIU/L; n = 283) and a ‘high-normal’ TSH group (TSH level 2.5 to 5.3 mIU/L with normal thyroid hormones; n = 44). Logistic regression analyses were performed to assess the association between TSH status and presence of nonalcoholic steatohepatitis (NASH) after stratifying subjects by PNPLA3 genotypes.ResultsCompared to strict-normal TSH group, patients with high-normal TSH levels were younger and had a greater prevalence of NASH and higher histologic NAFLD activity score. After stratifying by PNPLA3 genotypes, the significant association between high-normal TSH levels and presence of NASH was restricted only to carriers of the PNPLA3 G risk allele and remained significant even after adjustment for potential confounding factors (adjusted-odds ratio: 3.279; 95% CI: 1.298–8.284; P = 0.012).ConclusionIn euthyroid individuals with biopsy-proven NAFLD, we found a significant association between high-normal TSH levels and NASH. After stratifying by PNPLA3 rs738409 genotypes, this association was observed only among carriers of the PNPLA3 G risk allele.     

甲状腺素对大鼠胰岛β细胞作用和机制的研究

目的研究甲状腺素对大鼠胰岛β细胞功能的影响及其机制。方法采用放射免疫测定法和电镜技术,观察甲状腺素对大鼠血清葡萄糖、胰岛素、肿瘤坏死因子(TNF)、白介素-1β(IL-1β)水平的影响和胰岛β细胞超微结构的改变。结果甲状腺素600μg.kg-1.d-1,灌胃(ig),连续14 d,大鼠血清胰岛素水平明显降低,而血糖含量、IL-1β水平则显著升高,同时电镜发现大鼠胰岛β细胞的超微结构呈现退行性改变。结论甲状腺素大剂量长期应用对大鼠胰岛β细胞内分泌功能有抑制作用,其机制与细胞因子IL-1β分泌增多,诱导胰岛β细胞凋亡有关。