Cortisol promotes and integrates the osmotic competence of the organs in North African catfish (Clarias gariepinus Burchell): Evidence from in vivo and in situ approaches

The short-term in situ and long-term in vivo effects of cortisol were examined in North African catfish (Clarias gariepinus) to identify how this major corticosteroid integrates the osmotic competence of fish organs. In the in situ approach, the hydromineral effects of cortisol perfusion (75-300 ng ml⁻¹) for 20 min were tested and the indices of hydromineral and metabolic regulations were measured in our in vivo experimental fish after three alternate intraperitoneal cortisol injections (40 and 200 ng g⁻¹ body mass) for 5 days. Na⁺, K⁺-ATPase activity, a measure of cellular osmotic competence, responded to in situ and in vivo cortisol treatments. In situ cortisol delivery increased the Na⁺, K⁺-ATPase activity in the gill (P < 0.001) and kidney (P < 0.001) but decreased (P < 0.01) in the liver and showed no effect on intestine. In vivo cortisol treatment, on the contrary, increased Na⁺, K⁺-ATPase activity in the gills (P < 0.01), intestine (P < 0.05) and liver (P < 0.01) but decreased (P < 0.05) in the kidney. As expected, plasma cortisol increased (P < 0.001) with increasing doses of cortisol injections which produced direct effects on the metabolites and the mineral contents including the elevations of glucose (P < 0.05), lactate (P < 0.05) and Mg²⁺ (P < 0.05) and reductions of urea (P < 0.05), Na⁺ (P < 0.05) and K⁺ (P < 0.05) in the plasma. A decline of triiodothyronine (P < 0.01) occurred in the catfish after in vivo cortisol treatment and that implies a direct cortisol action on the homeostatic integration in this fish. Evidence is thus presented that in catfish cortisol regulates the whole body hydromineral and metabolite homeostasis by promoting and integrating the osmotic and metabolic functions of the multiple organ systems including liver.     

Low triiodothyronine serum levels as a predictor of poor prognosis in burn patients

OBJECTIVE: Euthyroid sick syndrome is a common finding in critically ill patients with nonthyroidal illness, characterized by low serum levels of free triiodothyronine (fT3) with a peculiar increase in reverse T3 (rT3) and normal-to-low free thyroxine (fT4) as well as thyroid-stimulating hormone (TSH) levels. This condition has been proposed as a prognostic factor of worse outcome in critically ill patients, while no conclusive data are available in burns. METHODS: Since thyroid function testing is contained in our baseline laboratory tests at admission, we retrospectively evaluated fT3, fT4 and TSH in 295 consecutive burn patients admitted to the Burn Center of Turin from January 2002 to December 2006, comparing hormone levels in survivors and non-survivors. RESULTS: fT3 and TSH levels were significantly lower (p相似文献   

Effects of Retinoic Acid,Triiodothyronine and Hydrocortisone on Mucin and Lysozyme Expression in Cultured Human Middle Ear Epithelial Cells

Mucous hypersecretion is a major complication of otitis media and can prolong the disease course and increase morbidity. Mucin, a major component of mucus, is a macromolecular complex of glycoprotein and makes mucus viscous. Lysozyme is a secretory element of the middle ear mucosa, which has a non-specific and innate antibacterial function. We attempted to identify factors that regulate these secretory products and their morphological phenotype using cultured human middle ear epithelial cells. Cellular differentiation was induced by creating an air-liquid interface on culture day 9 in serum-free conditioned media. Omission of retinoic acid (RA) caused decrease in the secretion of mucin and lysozyme, and in the cellular expression of MUC 2, MUC 5AC and MUC 5B mRNA. In contrast, removal of triiodothyronine (T3) caused an increase in the secretion of mucin and the level of MUC5AC mRNA. When hydrocortisone (HC) was removed from the media, the secretion of mucin was decreased without an apparent change of message level. The expression of MUC 1 mRNA was not changed by the respective deficiency of RA, T3 or HC. The effect of T3 or HC on lysozyme was not significant. This study shows that RA, T3 and HC influence the morphological phenotype and the secretory function of mucin and lysozyme in cultured human middle ear epithelial cells. This culture system can serve as an in vitro model for study of the regulation of various cellular secretions in human middle ear epithelium.     

Non-invasive measurement of thyroid hormone in feces of a diverse array of avian and mammalian species

We developed and validated a non-invasive thyroid hormone measure in feces of a diverse array of birds and mammals. An I¹³¹ radiolabel ingestion study in domestic dogs coupled with High Pressure Liquid Chromatography (HPLC) analysis, showed that peak excretion in feces occurred at 24-48 h post-ingestion, with I¹³¹-labelled thyroid hormone metabolites excreted primarily as triiodothyronine (T3) and relatively little thyroxine (T4), at all excretion times examined. The immunoreactive T3 profile across these same HPLC fractions closely corresponded with the I¹³¹ radioactive profile. By contrast, the T4 immunoreactive profile was disproportionately high, suggesting that T4 excretion included a high percentage of T4 stores. We optimized and validated T3 and T4 extraction and assay methods in feces of wild northern spotted owls, African elephants, howler monkeys, caribou, moose, wolf, maned wolf, killer whales and Steller sea lions. We explained 99% of the variance in high and low T3 concentrations derived from species-specific sample pools, after controlling for species and the various extraction methods tested. Fecal T3 reflected nutritional deficits in two male and three female howler monkeys held in captivity for translocation from a highly degraded habitat. Results suggest that thyroid hormone can be accurately and reliably measured in feces, providing important indices for environmental physiology across a diverse array of birds and mammals.     

兔甲状腺组织移植血清T3,T4变化的动态观察

本实验建立兔甲状腺颈阔肌下移植模型，并动态观查移植甲状腺的功能。实验结果发现普通馈料喂养的兔血清Ｔ３、Ｔ４值较稳定。而甲状腺全切后，兔血Ｔ３、Ｔ４明显降低，Ｔ３下降较快，Ｔ４则缓慢些。同品系移植组动物（Ⅰ、Ⅱ）在第１、２周时，血Ｔ３、Ｔ４较低，第３、４周后，则接近正常值。异品系移植组动物（Ⅳ）在第１周时，血Ｔ３、Ｔ４接近组Ⅲ，组Ⅳ第２周以后，血Ｔ３、Ｔ４明显低于组Ⅲ，而逐渐接近同一时间组Ⅱ的水平。     

In vitro binding of triiodothyronine to rat liver mitochondria

Saturable high affinity T₃ binding sites were detected in a mitochondrial fraction enriched in internal membranes and partly solubilized by Triton X-100. Specific T₃ binding to the solubilized sites, only detected at low T₃ concentrations, was optimal at pH 8.0 and not dependent upon the presence of divalent cations or reducing agents; it was destroyed by heat and proteolytic enzymes. The solubilized T₃ binding sites were distributed, after Sephadex G-200 gel filtration, between two peaks of similar affinity for T₃ (Ka5×10¹⁰ l/mol) and similar binding characteristics. T₃ was bound with a high stereospecificity, while some analogues of biological importance (l-T₄; 3,5,3-triiodothyroacetic acid: 3,3-diiodo-l-thyronine) competed withl-T₃ in the same range of low concentrations. This suggests that the high affinity mitochondrial T₃ binding sites could be of biological relevance in the mitochondrial metabolism.     

Alcohol consumption during gestation reduces the histamine and triiodothyronine content of rat immune cells

Objective: Different factors acting during pregnancy can cause non-morphological alterations of cells which are manifested later, in adulthood. We studied the effect of maternal alcohol consumption for one day in early pregnancy on the hormone content of immune cells in the adult rat. Methods: Lactating dams were given 15% ethanol in the drinking water for 24 h on the 3rd day post partum, exposing their pups to ethanol in the breast milk. Some of the same dams had been successfully mated on the day of delivery, so that they were also 3 days pregnant on the treatment day, exposing embryos to alcohol on the third day of pregnancy. In 4 month old pups histamine and triiodothyronine (T₃) content of citrate elicited peritoneal immune cells (lymphocytes, monocyte-macrophage-granulocyte group, mast cells) as well as thymic cells were determined by flow cytometry and confocal microscopy using specific antibodies. Results: Alcohol treatment during pregnancy decreased highly significantly the content of both hormones in peritoneal cells of the 4 month old adult animals while it was ineffective by breast feeding after birth. Thymic cells did not show any changes. Conclusion: Since the immune system had not developed at the time of treatment (3rd day of pregnancy), stem cells were presumably imprinted. Our results indicate the deleterious effects of early maternal alcohol consumption on the hormone content of the immune system. Received 13 April 2005; returned for revision 23 May 2005; accepted by I. Ahnfelt-R?nne 2 June 2005     

Sites of thyroid hormone action on Na−K-ATPase along the rabbit nephron

Although Ismail-Beigi and Edelman demonstrated in 1971 that thyroid hormones control the activity of Na–K-ATPase in the mammalian kidney, the actual site of this regulation inside the organ was not located. We therefore decided to study the relationship between thyroid hormones and Na–K-ATPase activity in individual nephron segments obtained by microdissection of collagenase-treated rabbit kidneys. For this purpose, the changes in the activity and number of catalytic sites of Na–K-ATPase in response to thyroidectomy or triiodothyronine administration were examined. Eight to 12 days after thyroidectomy, Na–K-ATPase activity had dropped by 40 to 80% in the convoluted and straight portions of the proximal tubules, and in the cortical and outer medullary collecting tubules, but not in the thick ascending limbs of Henle's loops or distal convoluted tubules. The apparent number of catalytic sites for Na–K-ATPase, as measured by specific binding of³H-ouabain, decreased in parallel with Na–K-ATPase activity, and therefore this enzyme's specific activity was not altered. Fourty eight hours after injection of thyroidectomized animals with a single dose of either 100 or 500 g/kg triiodothyronine, Na–K-ATPase activity in target segments was restored to the level measured in control animals. These effects of thyroid hormone were specific for Na–K-ATPase, since the activity of adenylate cyclase, another marker of the basolateral membrane, was not altered by thyroidectomy. The results obtained indicate that triiodothyronine controls Na–K-ATPase activity in specific nephron segments, by altering the number of this enzyme's catalytic sites.Abbreviations PCT proximal convoluted tubule - PR pars recta - MAL medullary thick ascending limb of Henle's loop - CAL cortical thick ascending limb - DCT_b initial bright portion of the distal convoluted tubule - DCT_g granular portion of the distal convoluted tubule - CCT cortical collecting tubule - MCT outer medullary collecting tubule - TX thyroidectomized - T₃ triiodothyronine - AVP arginine vasopressin - PTH parathyroid hormone - ISO isoproterenol     

脑性瘫痪患儿血清T_3、T_4、TSH水平测定

目的：通过对脑性瘫痪患儿血清Ｔ３、Ｔ４、ＴＳＨ水平测定,旨在研究其与脑性瘫痪的发生有无关系。方法：放射免疫测定法,使用ＳＮ－６９５Ｂ智能放免测量仪。结果：测定值经统计学处理其平均值：Ｔ３ｘ±ｓ：１４．２±０．４０ｎｇ／ｍｌ,Ｔ４ｘ±ｓ：９．５３±３．９９ｇ／ｄｌ,ＴＳＨｘ±ｓ：３．３２±２．８７μＩＵ／ｍｌ,与参考值对比处于正常范围内。结论：脑性瘫痪患儿血清Ｔ３、Ｔ４、ＴＳＨ水平处于正常,其与脑性瘫痪的发生无关。