[Function of the thyroid gland of tundra voles living on sites with the increased natural radioactivity].

We studied a functional condition of the thyroid gland of tundra voles living on sites with the increased level of a natural radioactivity (in Republic Komi areas in Russia). We have revealed that the functional condition of the thyroid gland depends on the phase of the population cycle of animals. The level of thyroid hormones in the irradiated animals differed from the norm; a high concentration of hormones in the irradiated animals was observed in the phase of the maximum number of animals, while males and females showed multidirectional differences from the control in the phase of the decreased number of animals.

Occupational Radiation Exposure and Changes in Thyroid Hormones in a Cohort of Chinese Medical Radiation Workers.

OBJECTIVE: This study aimed to evaluate the association between occupational radiation exposure and changes in thyroid hormone levels among medical radiation workers. METHODS: This retrospective cohort study included 2,946 radiation workers from 20 Guangzhou hospitals. Data on general characteristics, participant radiation dosimetry, and thyroid function test results [thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroid hormone (T4)] were extracted from dosimetry and medical records. The generalized estimating equation was used to evaluate the trend of changes in thyroid hormone levels over time and was adjusted for age, gender, and occupation. RESULTS: The average annual effective dose was very low and showed a general downward trend. During the follow-up period, changes in T3 and T4 levels among radiation workers were -0.015 [95% confidence interval ( CI) -0.018 to -0.012] nmol/L per year and -2.294 (95% CI -2.426 to -2.162) nmol/L per year, respectively. Thyroid hormone levels were significantly different between males and females. T3 levels in the group of upper quartile of dose were significantly higher than in the lower quartile group ( P = 0.006). No significant decreased trend in thyroid hormone levels was observed with increasing average effective doses. CONCLUSION: Thyroid hormone secretion might be affected even in low-dose radiation exposure environments.

Effects of fission neutrons on human thyroid tissues maintained in SCID mice.

Morphology and function (secretion of thyroid hormone) of human thyroid tissues from Graves' disease patients are well maintained in C57BL/6J-scid mice. Serum level of thyroid hormone was reduced by fission neutrons from the nuclear reactor UTR-KINKI, and changes in thyroid hormone by fission neutrons were bigger than those by low LET radiations, X-rays and (137)Cs gamma-rays, suggesting high relative biological effectiveness (RBE; 6.5) of fission neutrons. Microarray analyses revealed that about 3% of genes showed more than 4-fold change in gene expression in the unexposed thyroid tissues against surgically resected thyroid tissues from the same patient, probably due to the difficult oxygen and nutrient supply shortly after transplantation. Dose-dependent changes in gene expression against unexposed concurrent controls were observed with increasing doses of fission neutrons (0.2-0.6Gy) and (137)Cs gamma-rays (1.0-3.0Gy) and showed high RBE (4.2). Furthermore, there were some specific genes which showed more than 4-fold change in gene expression in all the thyroid tissues exposed to higher doses of radiation, especially neutrons (0.4 and 0.6Gy), but none at lower doses (0.2Gy of neutrons and 1.0 and 2.0Gy of gamma-rays). These genes related to degeneration, regeneration, apoptosis, and transcription, respond specifically and very sensitively to neutron injury in human thyroid tissues. This is the first experimental report that fission neutrons can induce some morphological and functional disorders in human tissues, showing high RBE against gamma-ray exposure. These results are useful to evaluate the risks of fission neutrons and cosmic rays to humans.

Occupational Radiation Exposure and Changes in Thyroid Hormones in a Cohort of Chinese Medical Radiation Workers / 生物医学与环境科学（英文）

Objective@#This study aimed to evaluate the association between occupational radiation exposure and changes in thyroid hormone levels among medical radiation workers.@*Methods@#This retrospective cohort study included 2,946 radiation workers from 20 Guangzhou hospitals. Data on general characteristics, participant radiation dosimetry, and thyroid function test results [thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroid hormone (T4)] were extracted from dosimetry and medical records. The generalized estimating equation was used to evaluate the trend of changes in thyroid hormone levels over time and was adjusted for age, gender, and occupation.@*Results@#The average annual effective dose was very low and showed a general downward trend. During the follow-up period, changes in T3 and T4 levels among radiation workers were -0.015 [95% confidence interval ( @*Conclusion@#Thyroid hormone secretion might be affected even in low-dose radiation exposure environments.

Sensitized photooxidation of thyroidal hormones. Evidence for heavy atom effect on singlet molecular oxygen [O2(1Deltag)]-mediated photoreactions.

Thyronine derivatives are essential indicators of thyroid gland diseases in clinical diagnosis and are currently used as standards for developing ordinary biochemical assays. Photooxidation of gland hormones of the thyronine (TN) family and structurally related compounds (TN, 3,5-diiodothyronine,3,3',5-triiodothyronine and 3,3',5,5'-tetraiodothyronine or thyroxine) was studied using rose bengal, eosin and perinaphthenone (PN) as dye sensitizers. Tyrosine (Tyr) and two iodinated derivatives (3-iodotyrosine and 3,5-diiodotyrosine) were also included in the study for comparative purposes. Irradiation of aqueous solutions of substrates containing xanthene dyes with visible light triggers a complex series of competitive interactions, which include the triplet excited state of the dye (3Xdye*) and singlet molecular oxygen [O2(1Deltag)]-mediated and superoxide ion-mediated reactions. Rate constants for interaction with the 3Xdye*, attributed to an electron transfer process, are in the order of 10(8)-10(9) M-1 s-1 depending on the dye and the particular substrate. The photosensitization using PN follows a pure Type-II (O2(1Deltag) mediated) mechanism. The presence of the phenolic group in Tyr, TN and iodinated derivatives dominates the kinetics of photooxidation of these compounds. The reactive rate constants, k(r), and the quotient between reactive and overall rate constants (k(r)/k(t) values, in the range of 0.7-0.06) behave in an opposite fashion compared with the overall rate constants and oxidation potentials. This apparent inconsistency was interpreted on the basis of an internal heavy atom effect, favoring the intersystem-crossing deactivation route within the encounter complex with the concomitant reduction of effective photooxidation.

Light-Regulated Thyroid Hormone Signaling Is Required for Rod Photoreceptor Development in the Mouse Retina.

PURPOSE: Ambient light is both a stimulus for visual function and a regulator of photoreceptor physiology. However, it is not known if light can regulate any aspect of photoreceptor development. The purpose of this study was to investigate whether ambient light is required for the development of mouse rod photoreceptors. METHODS: Newborn mouse pups (C57BL/6) were reared in either cyclic light (LD) or constant dark (DD). Pups were collected at postnatal day (P)5, P10, P17, or P24. We performed retinal morphometric and cell death analysis at P5, P10, and P17. Rhodopsin expression was assessed using immunofluorescence, Western blot, and quantitative RT-PCR analysis. Electroretinograms were performed at P17 and P24. Radioimmunoassay and ELISA were used to follow changes in thyroid hormone levels in the serum and vitreous. RESULTS: In the DD pups, the outer nuclear layer was significantly thinner at P10 and there were higher numbers of apoptotic cells at P5 compared to the LD pups. Rhodopsin expression was lower at P10 and P17 in DD pups. Electroretinogram a-waves were reduced in amplitude at P17 in the DD pups. The DD animals had lower levels of circulating thyroid hormones at P10. Light-mediated changes in thyroid hormones occur as early as P5, as we detected lower levels of total triiodothyronine in the vitreous from the DD animals. Drug-induced developmental hypothyroidism resulted in lower rhodopsin expression at P10. CONCLUSIONS: Our data demonstrate that light exposure during postnatal development is required for rod photoreceptor development and that this effect could be mediated by thyroid hormone signaling.

Pattern of recovery of the hypothalamic-pituitary-thyroid axis following radioactive iodine therapy in patients with Graves' disease.

PURPOSE: To characterize the time course of recovery of the hypothalamic-pituitary-thyroid (HPT) axis by determining the frequency, onset, duration, and clinical attributes of the central hypothyroid phase following 131I therapy for Graves' disease and to examine whether the central hypothyroid phase is due to direct pituitary thyrotroph suppression or to hypothalamic thyrotropin-releasing hormone (TRH) deficiency. PATIENTS AND METHODS: Twenty-one hyperthyroid patients with Graves' disease evaluated at a university endocrine clinic and treated with radioactive iodine were prospectively studied. Serial thyroid function levels (serum thyroxine [T4], free thyroxine [free T4], triiodothyronine [T3], and thyroid-stimulating hormone [TSH]) were measured and TRH stimulation tests were performed at 2 to 4 week intervals for all subjects following 131I treatment. None of the patients was treated with thionamides after receiving 131I therapy. RESULTS: Nineteen (90%) of the patients with Graves' disease experienced a transient central hypothyroid phase defined as the presence of a suppressed or inappropriately normal TSH level despite a low free T4 level following 131I treatment. This phase occurred a mean of 62.8 +/- 5.1 days following 131I treatment, persisted for an average of 24.7 +/- 2.4 days, and was not predictive of eventual treatment outcome. All patients had concordantly low T4 and T3 levels during this period and exhibited a blunted TSH response to TRH compared to 29 euthyroid control subjects, suggesting primary feedback suppression at the level of the pituitary thyrotrophs. The suppressed thyrotrophs required a minimum of 2 weeks to recover once patients became hypothyroid. The length of preexisting hyperthyroidism, basal free T4 elevation, and administered dose of 131I failed to predict the duration of the central hypothyroid phase, although a higher dose of 131I was associated with an earlier onset of central hypothyroidism (r = -.51, P < 0.05). CONCLUSIONS: Clinicians should be aware of the delay in the recovery of the HPT axis that occurs in the majority of patients with Graves' disease treated with 131I and is manifested by a transient central hypothyroid phase. The blunted TSH response to TRH stimulation during this period suggests that suppression occurs primarily at the level of the pituitary thyrotrophs. The use of sensitive TSH measurements alone to monitor these patients during this period is not helpful and may be misleading.

Changes in lipid peroxide levels and the activity of reactive oxygen scavenging systems in thyroid tissue after exposure to radioactive iodine in rats.

Exposure to ionizing radiation causes radiolysis of water in tissues leading to generation of reactive oxygen species (ROS), which are known to affect the antioxidant defense systems and induce lipid peroxidation (LP). Use of radioactive iodine (131I) for diagnosis and therapy of thyroid disorders may also generate ROS in the thyroid. Early (24 and 48 hours) and late (18 days) effects of subablation doses of 131I (370/555/1110 kBq) on the antioxidant defense and LP in the thyroid tissues have been studied. LP was elevated in all 131I treated groups by 10% to 41%. Although there was no change in catalase (CAT), the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities showed evidence of change from 48 hours onwards--SOD decreased by 32% to 56% and GPx increased by 15% to 43%. Nonprotein thiols (reduced glutathione, GSH) showed an elevation of 16% at 24 hours, but later declined by 15% by day 18 after 370 KBq of 131I. Thus, the increase in LP observed may be due to beta irradiation induced ROS by 131I. The parallel decrease in SOD could be due to inactivation by ROS. The increase in GPx may be a consequence of induction due to elevated LP and/or ROS, which may be inadequate to lower the LP. In spite of elevated LP, the thyroid function appears to be normal.

[Atmospheric radiations. Effects of potassium-inhibitory and potassium-retentive hormones on two types of infective agent]. / Radiazioni atmosferiche. Effetti degli ormoni potassio inhibitori e potassio ritentivi su due tipi di agenti infettivi.

The glucocorticoids and the estrogens facilitate the loss of potassium from the cells (iK+ hormones). The thyroid hormones, the androgens, the growth hormone and the insulin facilitate the penetration of potassium into the cells (rK+ hormones). The incretion of iK+ hormones follows the course of the intensity of the atmospheric radiations (atmospheric electric field, terrestrial magnetic field), that is it grows or diminishes according to the increase or decrease of the intensity of said radiations, while the incretion of rK+ hormones has an opposite course in comparison with the variations of said intensity. The iK+ hormones cause loss of iodine, decrease of eosinophils, of RNA and antibodies, while the rK+ hormones cause opposite effects. High temperatures produce an increase of iK+ hormones and low temperatures an increase of rK+ hormones. The study of the effects of atmospheric radiations on infectious diseases has shown the existence of two kind of infectious agents: the iK+ agents and the rK+ agents on which the hormones iK+ and rK+ have an effect. The hormones iK+ work jointly with iK+ agents (virus RNA, bacteria Gram-negative) and counteract the rK+ agents (virus DNA, bacteria Gram-positive, protozoa). The rK+ hormones have opposite effects in comparison to those of iK+ hormones, that is they counteract the iK+ agents and work jointly with the rK+ agents.

[The effect of artificial ultraviolet light on biochemical indicators in calves]. / Vplyv umelého ultrafialového svetla na biochemické ukazovatele teliat.

Changes in the biochemical parameters of the blood serum of calves were studied after exposure to optimum doses of ultraviolet radiation. The calves were exposed to UV-light twice daily in three periods: 8, 9 and 10 days. Daily doses of 90, 130 and 180 mEr.h.m-2 were used in the first experiment, 120, 180 and 240 mEr.h.m-2 in the second experiment. As found, exposure to radiation in the individual periods increased total proteinaemia, the differences between the experimental and control groups being significant. Exposure to ultraviolet light induced an increase in the activity of the thyroid gland; at the end of the periods of UV-radiation the concentration of thyroxine in the experimental groups was significantly or highly significantly higher. The largest differences were recorded in the first trial (15 nmol per litre to 21.4 nmol per litre). No changes were detected by the evaluation of the activities of alkaline phosphatase, triiodothyronine, sodium, potassium and calcium and in the sodium: potassium ratio.

[The immunomodulating action of microwaves in the induction of an immune response to Vi antigen]. / Immunomoduliruiushchee deistvie mikrovoln pri induktsii immunnogo otveta na Vi-antigen.

In this work the possibility of using microwaves for immunomodulation in the immunization of animals with thymus-independent antigen was studied. The projection zones of the thymus and adrenal glands of the test animals were subjected to the action of decimeter, or ultrahigh frequency (UHF), waves, while the corresponding zones of the control animals were subjected to imitation UHF irradiation. Vi-antigen was shown to be a thymus-independent antigen for rabbits (according to the results of the evaluation of the functional state of thymocytes, as manifested by the adsorption of acridine orange by the chromatin of thymocyte nuclei and by the content of RNA and DNA in the thymus). The action of UHF waves on the projection zone of the thymus was accompanied by a decrease in the glucocorticoid activity of the adrenal cortex, observed simultaneously with a pronounced immunostimulating effect. The UHF irradiation of the zone of the adrenal glands was accompanied by immunosuppression in combination with enhanced glucocorticoid activity of the adrenal cortex.

[The effect of radon baths at Khmel'nik health resort on the central hemodynamic indices, on thyroid function and on adrenal glucocorticoid function in hypertension patients]. / Vliianie radonovykh vann kurorta Khmel'nik na pokazateli tsentral'noi gemodinamiki, funktsiiu shchitovidnoi zhelezy i gliukokortikoidnuiu funktsiiu nadpochechnikov u bol'nykh gipertonicheskoi bolezn'iu.

As many as 63 patients with stage I, II hypertensive disease were examined. Characteristics of central hemodynamics were studied by means of tetrapolar thoracic rheography, the content of thyroid-stimulating hormone, thyroxin, triiodothyranine, hydrocortisone were determined by radioimmunologic method. All investigations were done before and after the patients having radon baths. Hypotensive effect of radon baths in hyperkinetic type hemodynamics was manifested by a significant drop in cardiac index and increase in specific peripheral resistance. In hypokinetic type hemodynamics there was a significant fall in average hemodynamic pressure, and improvement of the arteriole patency. The levels of thyroxin and hydrocortisone have raised significantly. The Khmel'nik health resort radon baths have hypotensive effect in HD patients, enhance the function of the thyroid gland and glucocorticoid function of the adrenals.

[Hypophyseal-thyroid system function in patients with nonspecific lung diseases who participated in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station]. / Sostoianie gipofizarno-tireoidnoi sistemy u bol'nykh nespsetsificheskimi zabolevaniiami legkikh, uchastvovavshikh v likvidatsii posledstvii avarii na ChAES.

A comparative evaluation was done of the condition of the hypophyseal-thyroid axis in those patients with unspecific pulmonary diseases having taken part in the elimination of the aftermath of the ChNPP accident in 1986-1988, as well as patients with no particular prior history and essentially healthy subjects. With the thyroxin content tending downwards, the main differences manifested themselves at the level of hypophyseal control. Provision of the organism with more active forms of hormones was found to be maintained in all the cases at the physiological level.

[The effect of environmental factors on the concentration of tumor markers in the blood serum and on the indices characterizing thyroid function]. / Vliianie nekotorykh faktorov okruzhaiushchwei sredy na kontsentratsiiu v syvorotke krovi opukholevykh markerov i pokazateli, kharakterizuiushchie sostoianie shchitovidnoi zhelezy.

Combined versus separate exposure of male organism to cesium-137 and chemical agents results in a more pronounced hyperferritinemia in the former case. In female chemists the ferritin level is dependent to a considerable extent on the menstrual cycle showing a tendency for the iron-containing protein level to decrease because of the action of a number of chemical agents. The rise of the level of cancer embryonic antigen is more readily seen in persons with high levels of cesium-137. Concentrations of carbohydrate antigen (CA-125) and mucin-like antigen are appreciably higher in female chemists incorporating cesium-137, and in those within the 30-km radius of the ChNPP. The level of thyroglobulin was raised in the chemists having a background incorporation of cesium, the liquidators of the aftermaths, and particularly in those happened to be in the 30-km zone. Each of the unfavourable factors taken separately (chemical agent or cesium-137) had lesser effect on the degree of elevation of TG content and hormone-forming function of the thyroid gland. An additional information has been obtained concerning the risk groups, which, however, serves as an indirect measure of carcinogenic effect various environmental factors exert on the organism.

[The sanatorium-health resort treatment of children with thyroid hyperplasia]. / Sanatorno-kurortnoe lechenie detei s giperplaziei shchitovidnoi zhelezy.

A favourable effect of sanatorium treatment on the key body functions was found in children with thyroid hyperplasia consequent to environmental pollution due to Chernobyl accident. It is emphasized that balneofactors in the above children should be used in sparing regimens.

Assessment of the systemic effects of low-level laser therapy (LLLT) on thyroid hormone function in a rabbit model.

The aim of this study was to assess the effects of low-level laser therapy (LLLT) applied to a dental extraction socket on thyroid gland function in a rabbit model, based on serum triiodothyronine and thyroxine levels. Sixteen male New Zealand rabbits were randomly distributed into two groups: a control group (non-irradiated animals) and an experimental group (irradiated animals: one irradiation point in the extraction socket of the lower incisor). Animals in the experimental group were irradiated with an aluminium gallium arsenide diode laser (AlGaAs; wavelength 830 nm, 40 mW, CW laser), for 13 days, every 48 h, at a dose of 6 J/cm(2) per session, resulting in a total dose of 42 J/cm(2). Serum triiodothyronine and thyroxine levels were measured in both groups before extraction and on the last day of observation (day 15). There were no statistically significant differences between the groups in pre- and post-irradiation triiodothyronine and thyroxine values. With the irradiation protocol used in this study, LLLT did not affect thyroid function in rabbits as assessed by circulating serum triiodothyronine and thyroxine levels.

Thyroid remnant dose: 124I-PET/CT dosimetric comparison of rhTSH versus thyroid hormone withholding before radioiodine remnant ablation in differentiated thyroid cancer.

AIM: Recombinant human thyroid-stimulating hormone (rhTSH) recently was approved as an alternative to thyroid hormone withholding (THW) to elevate TSH for thyroid remnant ablation in differentiated thyroid carcinoma patients. High ablation success rates are reported with diverse rhTSH-aided (131)I activities. Improved renal function causes approximately 50% faster radioiodine clearance under euthyroidism versus hypothyroidism. Knowledge of comparative remnant radioiodine kinetics, particularly the remnant radiation dose in Gy/GBq of administered (131)I activity (RDpA), could assist in choosing rhTSH-aided ablative activities. MATERIAL AND METHODS: To compare the RDpA, determined through (124)I-positron emission tomography/computed tomography (PET/CT), under the two stimulation methods, we retrospectively divided into two groups 55 consecutive totally-thyroidectomized, radioiodine-naïve patients. The rhTSH group (n=16) received (124)I on thyroid hormone, 24 h after two consecutive daily intramuscular injections of rhTSH, 0.9 mg. The THW group (n=39) received (124)I after weeks-long THW, when serum TSH first measured > or = 25 mIU/L. We performed PET investigations 4 h, 24 h, 48 h, 72 h and 96 h and PET/CT 25 h after (124)I administration. RESULTS: Median stimulated serum thyroglobulin was 15 times higher (p=0.023) and M1 disease almost twice as prevalent (p=0.05) in rhTSH versus THW patients. Mean+/-standard deviation RDpA was statistically equivalent between the groups: rhTSH, 461+/-600 Gy/GBq, THW, 302+/-329 Gy/GBq, two-sided p=0.258. CONCLUSIONS: rhTSH or THW deliver statistically equivalent radiation doses to thyroid remnant and may be chosen based on safety, quality-of-life, convenience and pharmacoeconomic factors. Institutional fixed radioiodine activities formulated for use with THW need not be adjusted for rhTSH-aided ablation.