Suppression of peripheral blood natural killer cell activity by excess thyroid hormone.

Natural killer (NK) cells were assessed in patients with hyperthyroxinemia due to Graves' disease or treatment with thyroxine (T4). Cytolytic activity was measured with 51Cr-labeled K562 tumor cells and NK enumeration was by flow cytometry using NKH-1 monoclonal antibody to identify the relevant surface marker. Activity was uniformly decreased in association with hyperthyroxinemia, regardless of the underlying pathology; however, there was no reduction in the number of NKH-1+ cells. NK activity was enhanced by addition of interleukin 2 (IL-2) in both control and patients' cells although the value in the latter instance failed to reach the basal control level. Production of IL-2 by lymphocytes from hyperthyroxinemic subjects, in response to phytohemagglutinin, was also reduced. Since NK cells are thought to act as a defense against viral infections and some malignancies and may play a role in autoregulation of the immune system, this effect of T4 may have significant biological implications.     

Plasma thyrotropin-releasing hormone concentrations in the rat. Effect of thyroid excess and deficiency and cold exposure.

To investigate the physiology of thyrotropin-releasing hormone (TRH) secretion from hypothalamus and brain, a method for measurement of peripheral plasma TRH concentrations in rats was developed. Blood was collected in heparin and dimercaptopropanol containing [3H]TRH to determine recovery. The plasma was extracted with methanol and the redissolved dried methanol extracts applied to anti-TRH Sepharose columns. These columns bound greater than 80% of 125I-TRH applied and had a capacity in excess of 20 ng TRH. TRH was eluted from the anti-TRH Sepharose with acetic acid and quantitated by radioimmunoassay of the lyophilized acetic acid eluate. Mean recovery of unlabeled TRH was 44.7+/-6.1% (SD) and mean recovery of [3H]TRH was 44.0+/-4.0%. Mean plasma TRH concentrations, corrected for recovery, in plasma pools from eight groups of normal male rats (four to seven pools/experiment, five to seven rats/pool) ranged from 7 to 30 pg/ml (mean, 16). In experiments in which rats were given 5, 10, 15, 0r 50 mug thyroxine daily for 1 wk or in thyroidectomized rats, mean plasma TRH concentrations did not differ significantly from those of control animals sacrificed at the same time. In each experiment, four to seven plasma pools, each from five to seven rats, were processed from both control and experimental groups. No changes in plasma TRH concentrations were found in rats exposed to cold (4degreeC) for 30, 60, and 90-180 min. Signigicant increases in plasma thyrotropin (TSH) concentrations were found in all cold-exposed animals. These results provide no evidence that thyroid hormone excess of deficiency affects TRH secretion. If TRH secretion is responsible for cold-induced increases in plasma TSH concentrations, the increase in TRH secretion is of insufficient magnitude to alter periperal plasma TRH concentrations.     

Resistance to thyroid hormone

Resistance to thyroid hormone is a syndrome involving reduced responsiveness of target tissues to thyroid hormone. Most cases involve mutations of the thyroid hormone receptor beta gene. Since many patients demonstrate tachycardia, goiter and elevated serum thyroid hormone levels, some patients have been misdiagnosed with Graves' disease, and nearly one third of patients are being treated inappropriately. It is important to keep this diagnosis in mind when a patient with elevated thyroid hormone level accompanied by normal or slightly increased TSH levels (SITSH) is encountered. Therapy with TRIAC has been used in several patients.     

A novel 1297-1304delGCCTGCCA mutation in the exon 10 of the thyroid hormone receptor beta gene causes resistance to thyroid hormone.

INTRODUCTION: Resistance to the thyroid hormone (RTH) is an inherited syndrome of reduced tissue responsiveness to hormonal action caused by mutations located in the ligand-binding domain and adjacent hinge region of the thyroid hormone receptor beta (TRbeta) gene. PATIENT: The patient in this study, a 42-year-old Caucasian male, came to medical attention because he experienced atrial fibrillation. Clinical evaluation showed a small and diffuse goiter and biochemical tests revealed markedly elevated concentrations of total T4, total T3, and free T4, normal thyroid-stimulating hormone (TSH) values and slightly increased I131 thyroid uptake at 24 hours. The thyroperoxidase, thyroglobulin, and TSH receptor antibodies were positive. He was treated with cabergoline plus methimazole. This treatment was stopped because of the inconsistent response, monotherapy with tri-iodothyroacetic acid (TRIAC) was then prescribed after molecular diagnosis confirmed RTH syndrome. METHODS: The exons 9 and 10 of the TRbeta gene, including splicing signals and the flanking intronic regions of each intron, were amplified with PCR. DNA sequences from each amplified fragment were performed with the Taq polymerase-based chain terminator method and using the specific TRbeta forward and reverse primers. RESULTS: Direct sequence analysis of the exons 9 and 10 of the TRbeta gene revealed an eight basepair deletion, 1297-1304delGCCTGCCA in exon 10. The mutation produces a frameshift at amino acid 433 and introduces a stop codon TGA at position 461, 85 nucleotides downstream from deletion. This alteration was not detected in either the father or mother of the patient, suggesting a de novo mutation that was confirmed by DNA fingerprint analysis. CONCLUSIONS: In the present study we have identified a novel sporadic mutation corresponding to 1297-1304delGCCTGCCA deletion in the activating function 2 (AF-2) region of TRbeta. To our knowledge, this is the first time that the presence of a partial deletion of eight nucleotides in the TRbeta has been reported.     

Transient exposure of carcinoma cells to RAS/MEK inhibitors and UCN-01 causes cell death in vitro and in vivo

The present studies were initiated to determine in greater molecular detail how MEK1/2 inhibitors [PD184352 and AZD6244 (ARRY-142886)] interact with UCN-01 (7-hydroxystaurosporine) to kill mammary carcinoma cells in vitro and radiosensitize mammary tumors in vitro and in vivo and whether farnesyl transferase inhibitors interact with UCN-01 to kill mammary carcinoma cells in vitro and in vivo. Expression of constitutively activated MEK1 EE or molecular suppression of JNK and p38 pathway signaling blocked MEK1/2 inhibitor and UCN-01 lethality, effects dependent on the expression of BAX, BAK, and, to a lesser extent, BIM and BID. In vitro colony formation studies showed that UCN-01 interacted synergistically with the MEK1/2 inhibitors PD184352 or AZD6244 and the farnesyl transferase inhibitors FTI277 and R115,777 to kill human mammary carcinoma cells. Athymic mice carrying approximately 100 mm(3) MDA-MB-231 cell tumors were subjected to a 2-day exposure of either vehicle, R115,777 (100 mg/kg), the MEK1/2 inhibitor PD184352 (25 mg/kg), UCN-01 (0.2 mg/kg), or either of the drugs in combination with UCN-01. Transient exposure of tumors to R115,777, PD184352, or UCN-01 did not significantly alter tumor growth rate or the mean tumor volume in vivo approximately 15 to 30 days after drug administration. In contrast, combined treatment with R115,777 and UCN-01 or with PD184352 and UCN-01 significantly reduced tumor growth. Tumor cells isolated after combined drug exposure exhibited a significantly greater reduction in plating efficiency using ex vivo colony formation assays than tumor cells that were exposed to either drug individually. Irradiation of mammary tumors after drug treatment, but not before or during treatment, significantly enhanced the lethal effects of UCN-01 and MEK1/2 inhibitor treatment. These findings argue that UCN-01 and multiple inhibitors of the RAS-MEK pathway have the potential to suppress mammary tumor growth, and to interact with radiation, in vitro and in vivo.     

造血干细胞移植后死因分析

目的：探讨造血干细胞移植（HSCT）治疗血液系统恶性疾病珀患者常见的死亡原因，方法：对采用HSCT技术治疗的24例患者的临床资料进行了回顾性分析，结果：移植后 死亡10例，治愈或长期无病生存14例，天文馆原因为感染4例，死亡时间＋16－－＋268天，其中巨细胞病毒（CMV）性间质性肺炎（IP）2例，败血症和肺部细菌，真菌，病毒混合性感染各1例，病死率16．7％（4／24）；肿瘤复发6例，死亡时间＋102－－＋741天，病死率25％（6／24）。结论：感染和肿瘤复发是HSCT后常见死亡原因，应积极防治感染和避免使用过量免疫抑制剂，预防移植物抗宿主病（GVHD），以降低移植后病死率。     

甲状腺激素抵抗1例临床报道

病例:女,17岁。因心悸、怕热、多汗6年,拟“Graves病”于2004年8月入院。患者6年前无明显诱因出现心悸、怕热、多汗、消瘦、手颤,当地诊所诊断为“甲状腺肿”,予以甲状腺素片口服,治疗半年后症状无好转而停药。2001年家长发现患者颈部较前增粗,又至外院就诊,诊断为“Graves病”     

富碘中药海藻对甲状腺细胞凋亡及凋亡调控基因的影响

目的:通过观察富碘中药海藻对碘缺乏机体甲状腺滤泡上皮细胞凋亡,Fas,FasL,Bcl-2蛋白表达的影响,分析富碘中药过量对甲状腺损伤的机制。方法:实验于2006-03/09在辽宁中医药大学实验中心完成。①实验干预:选用健康鼠龄4周的Wistar大鼠150只。取120只喂低碘饲料建立缺碘大鼠模型,随机分为4组,每组30只:单纯高碘组喂含碘2000μg/L的双蒸水;模型组喂等体积双蒸水;常规剂量海藻组和3倍剂量海藻组分别灌胃海藻生药量13.5g/(kg·d)和40.5g/(kg·d)。以其余30只大鼠为正常对照组:正常饮食,每日灌服等体积双蒸水。②实验评估:分别在给药0,7,28d后取材。采用脱氧核糖核苷酸末端转移酶介导原位缺口末端标记确定甲状腺滤泡上皮细胞凋亡细胞数。采用免疫组化方法观察甲状腺滤泡上皮细胞Fas,FasL,bcl-2表达。结果:大鼠150只均进入结果分析。①凋亡细胞数:给药后7d,常规剂量海藻组和3倍剂量海藻组低于模型组,差异有非常显著性意义(P<0.01)。常规剂量海藻组和3倍剂量海藻组低于单纯高碘组,差异有显著性意义(P<0.05)。给药后28d,正常对照组甲状腺滤泡上皮细胞凋亡细胞数低于其他4组,差异有显著性或非常显著性意义(P<0.05～0.01)。常规剂量海藻组高于单纯高碘组,差异有显著性意义(P<0.05)。②Fas,FasL,Bcl-2蛋白表达:给药7d后,常规剂量海藻组和3倍剂量海藻组Fas蛋白的表达低于模型组,差异有显著性意义(P<0.05)。单纯高碘组和3倍剂量海藻组FasL表达低于模型组,差异有显著性意义(P<0.05)。常规剂量海藻组Bcl-2蛋白表达高于模型组,差异有显著性意义(P<0.05)。给药28d后,单纯高碘组和3倍剂量海藻组Fas蛋白的表达低于模型组,差异有显著性意义(P<0.05)。单纯高碘组、常规剂量海藻组和3倍剂量海藻组Bcl-2蛋白表达高于模型组,差异有显著性意义(P<0.05)。结论:富碘中药海藻给药28d可造成碘缺乏大鼠甲状腺细胞损伤,Fas,FasL,bcl-2可能参与诱导细胞凋亡。     

Tissue responses to thyroid hormone in a kindred with resistance to thyroid hormone harboring a commonly occurring mutation in the thyroid hormone receptor beta gene (P453T)

Resistance to thyroid hormone (RTH) is a dominantly inherited syndrome of reduced tissue responsiveness to thyroid hormone (TH) usually due to mutations in the TH receptor beta gene (TRbeta). We studied pituitary and peripheral tissue responses to graded doses of liothyronine (L-T3) in 5 affected members (2 children and 3 adults) of a family with RTH due to the common TRbeta mutation P453T. Overall, the 5 subjects studied exhibited suppressed thyrotropin response to thyrotropin-releasing hormone of 51% +/- 8%, 12.1% +/- 1.5%, and 6.3% +/- 3% of the 100% baseline on 50, 100, and 200 microg/dL L-T3, respectively. This degree of suppression was greater than that observed in subjects with RTH due to other TRbeta mutations, indicating less resistance. Compared with normal subjects, however, the family described here demonstrated less suppression by L-T3, compatible with their RTH, although of a mild magnitude. The 2 children with RTH demonstrated less L-T3-mediated suppression of prolactin and cholesterol than the adults. Patients often receive thyroid ablative therapy before the diagnosis of RTH and are left with variable degrees of hypothyroidism. Our results demonstrate that graded doses of L-T3 can be used to evaluate RTH patients, even under the condition of limited thyroid reserve, when results are compared with their baseline. We demonstrate that RTH patients can be evaluated either on or off thyroid hormone and still be distinguished from hypothyroid subjects without RTH.     

The effects of endocrine-disrupting chemicals on thyroid hormone binding to Xenopus laevis transthyretin and thyroid hormone receptor.

We investigated the effects of medical, industrial and agricultural chemicals on 3,3',5-L-[125I]triiodothyronine ([125I]T3) binding to purified recombinant Xenopus laevis (X. laevis) transthyretin (xTTR), a plasma thyroid hormone-binding protein, and to the ligand-binding domain of thyroid hormone receptor-beta (xTR LBD). xTTR derived from X. laevis serum had about 80 times higher affinity for T3 than for L-thyroxine. The xTTR's relative affinities for diethylstilbestrol, pentachlorophenol and ioxynil were 10(-1)- to 10(-2)-fold less than that for T3. However, all chemicals investigated had either a weak or no influence on [125I]T3 binding to xTR LBD. The concentration of diethylstilbestrol, the most potent chemical, required for 50% inhibition of [125I]T3 binding to xTR LBD was 10(4) times greater than that of unlabeled T3. These results indicate the existence of several chemicals that interact with xTTR but not with xTR LBD.     

DNA-based diagnosis of thyroid hormone resistance syndrome: a novel THRB mutation associated with mild resistance to thyroid hormone

BACKGROUND: Thyroid hormones govern a wide range of metabolic processes in the body via thyroid hormone receptors (TR). We report a patient with mild resistance to thyroid hormone who was initially misdiagnosed and treated as having thyrotoxicosis. METHODS: We used direct DNA sequencing of the THRB gene. RESULTS: We identified a novel missense mutation, I276L, located in exon 8 of the gene. The mutation is located in cluster 3 of the ligand-binding domain, a protein domain associated with resistance to thyroid hormone. CONCLUSION: DNA-based diagnosis of thyroid hormone resistance syndrome is simple, reliable, and economical compared to traditional biochemical tests. Once the mutation is identified, targeted screening for the whole family can be performed and the unnecessary use of anti-thyroid drugs or thyroidectomy can be avoided.     

Resistance to the effects of thyroid hormone in children

We have described three children with serum levels of TSH that are too high for the concomitant serum T4 level. Two of them meet the criteria for combined central and peripheral resistance to thyroid hormone. The third has long-standing central resistance to TSH suppression previously reported in congenital hypothyroidism. The recognition of this syndrome by physicians is important to avoid unnecessary and potentially dangerous treatment.