Thyroid hormone synthesis during hypothermia in rats

Zusammenfassung Tiefe und oberflächliche Hypothermie an Ratten reduziert die Radiojodfixation der Schilddrüse. Markierte Jodtyrosine werden dedektiert, während Jodtyronine fehlen.     

Diuretic and antifeedant actions byManduca sexta diuretic hormone in lepidopteran larvae

Neuroendocrine disruption of water balance in insect larvae was evaluated as the basis for a new approach to pest insect control. Effects on water balance and food consumption were measured for larvae ofHeliothis virescens (cotton budworm) treated with syntheticManduca sexta diuretic neurohormone (MasDH). Synthetic MasDH (50–250 nM) caused dose-dependent increases in fluid secretion by larval Malpighian tubules in vitro; higher concentrations resulted in lower fluid secretion. Last instar larvae injected with 20–100 pmol MasDH exhibited increasing weight loss. Larvae injected with 500 pmol MasDH dramatically reduced both water excretion and food consumption by 70%. These latter results indicate that high titers of diuretic hormone can suppress feeding damage by larval insects by depressing water excretion and food consumption.     

Thyroid hormone in serum of fetal calf and pregnant cow during the last trimester of pregnancy

Summary Considerably higher thyroxine and triiodothyronine concentrations in sera of bovine fetuses than in maternal samples were found during the last trimester of pregnancy.Acknowledgment. We wish to thank Miss.R. Fajkoová for skilled technical assistance.     

Thyroid hormones and cathepsin D activity in the rat liver,kidney and brain

Summary The effect of thyroidectomy and subsequent treatment with tri-iodothyronine (T₃), as well as that of thyrotoxicosis, was examined on cathepsin D activity in the rat liver, kidney and brain. Thyrotoxicosis resulted in a generalized increase in the enzyme activity in the 3 tissues; the effect of other thyroidal states was diverse and tissue-specific.     

Melatonin and cell death: differential actions on apoptosis in normal and cancer cells

Melatonin is a natural compound synthesized by a variety of organs. It has been shown to function as a cell-protective agent. Since 1994, when the first paper was published documenting the role of melatonin in apoptosis, the number of reports in this area has increased rapidly. Much of the research conducted falls into three major categories: first, the role of melatonin in inhibiting apoptosis in immune cells; second, the role of melatonin in preventing neuronal apoptosis and finally, the role of melatonin in increasing apoptotic cell death in cancer cells. The mechanisms whereby melatonin influences apoptosis have not clarified, although a number of mechanistic options have been suggested. Apoptotic cell death is a physiological phenomenon related to homeostasis and proper functioning of tissues and organs; however, a failure in the apoptotic program is related to a number of diseases. The participation of melatonin in apoptosis in numerous cell types and its potential importance in a variety of diseases such as immunodeficiency, neurodegeneration and cancer is summarized in this review.Received 14 November 2002; received after revision 16 January 2003; accepted 10 February 2003     

Thyroid hormone receptor-mediated regulation of the methionine adenosyltransferase 1 gene is associated with cell invasion in hepatoma cell lines

The thyroid hormone T₃ regulates differentiation, growth, and development. We demonstrated that methionine adenosyltransferase 1A (MAT1A) was positively regulated by T₃ identified by cDNA microarray previously. The expression of the MAT1A was upregulated by T₃ in hepatoma cell lines overexpressing thyroid hormone receptors (TRs). Additionally, these findings indicate that MAT1A may be regulated by CCAAT/enhancer binding protein (C/EBP). The critical role of the C/EBP binding sites was confirmed by the reporter or chromatin immuno-precipitation (ChIP) assay. In addition, C/EBP was upregulated in hepatoma cells after T₃ treatment and ectopic expression of MAT1A inhibited cell migration and invasion in J7 hepatoma cells. Conversely, knockdown of MAT1A expression increased cell migration. Together, these findings suggest that the expression of the MAT1A gene is mediated by C/EBP and is indirectly upregulated by T₃. Finally, TR was downregulated in a small subset of hepatocellular carcinoma cells concomitantly reduced the expression of C/EBPα and MAT1A.     

Effect of thyroid hormone on somatomedin-C release from perfused rat liver

The effect of thyroid hormone on plasma somatomedin-C (SmC) level and on SmC release from perfused rat liver was investigated. Plasma SmC levels and liver tissue SmC were significantly increased in thyroxine-treated rats. Physiological doses of triiodothyronine increased SmC release and SmC concentration in the perfused rat liver. These results indicate that thyroid hormone directly enhances the synthesis and release of SmC in the rat.     

Intravenous thyrotropin releasing hormone (TRH) enhances the excitatory actions of acetylcholine (ACh) on rat cortical neurons

Summary I. v. administered TRH (1.25-10 mg/kg) enhanced the excitatory actions of iontophoretically applied ACh on spontaneously active cerebral cortical neurons of pentobarbital-anaesthetized rats. These observations are consistent with the hypothesis of a cholinergic-link in the anti-anaesthetic actions of exogenously administered TRH.     

Plasma growth hormone in the rabbit fetus. Relation to maturation of the liver and lung]

Day 25 after insemination is a date of peculiar importance in the maturation of several organs in the Rabbit fetus. From day 25 onward the fetal liver stores increasing amounts of glycogen and the lung stores increasing amounts of lecithins, concomitant with sudden rise in the activity of lung phosphatidic-acid phosphohydrolase. Earlier studies on decapitated fetuses established that glycogen storage in the liver is dependent on a dual hormonal control, comprising a pituitary hormone like growth hormone or prolactin (some placental hormones share the same activity) and corticosteroids (Jost, 1961). Since the variations in endogenous corticosteroids do not seem to herald these liver or lung changes (Mulay et al., 1973), a study was made of growth hormone. Plasma immunoreactive growth hormone--determined with a heterologous Rat system (Kervran et al., 1976)--increases eightfold between days 23 and 25. During the same time plasma prolactin does not change according to McNeily and Friesen, 1978, and to unpublished data obtained with Dr McNeilly. In preliminary assays, Rat growth hormone was seen to increase phosphorylase "a" activity in the lung of 18.5 day-old Rat fetuses, thus anticipating normal development. We suggest that growth hormone plays a role in initiating liver and lung maturation.     

Pharmacological actions of caerulein

Riassunto La caeruleina, nonapeptide attivo della pelle diHyla caerulea, possiede un insieme di potenti azioni farmacologiche sulla muscolatura liscia vasale ed extravasale e sulle secrezioni del tubo digerente. La caeruleina provoca una relativamente prolungata caduta della pressione del sangue nel cane e nel coniglio, contrae potentemente la muscolatura in situ dello stomaco, dell'intestino e soprattutto della cistifellea, stimola poderosamente la secrezione gastrica, la secrezione pancreatica e, in misura minore, la secrezione biliare. In queste sue multiformi azioni farmacologiche la caeruleina risulta più potente rispettivamente della bradichinina, della gastrina e della colecistochinina-pancreozimina.

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Supported by grants from the Consiglio Nazionale delle Ricerche, Roma.     

Influence of previous feeding with a high-fat diet on liver steatosis produced by acute starvation or growth hormone in mice

Zusammenfassung Bei 12–22 Tage mit einer ausreichend ergänzten Fettdiät gefütterten Mäusen, tritt die durch akuten Hunger oder einmalige Verabfolgung von STH ausgelöste Lebersteatose, wenn überhaupt, nur in abgeschwächter Form auf. Dieser Effekt kann als Folgeerscheinung einer Stoffwechseladaptation an die hohe Fettzufuhr gedeutet werden, die durch eine gesteigerte Verwertungskapazität von exogenem und endogenem Fett in Erscheinung tritt.     

CT诊断甲状腺肿块18例临床分析

目的探讨甲状腺肿块的CT诊断价值。方法回顾分析18例甲状腺肿块的CT特征,并与手术病理对照。结果CT诊断18例甲状腺肿块与手术病理符合率的情况：（1）结节性甲状腺肿7例,诊断符合率71％（5／7）;（2）甲状腺腺瘤8例,诊断符合率63％（5／8）;（3）甲状腺癌3例,诊断符合率67％（2／3）。结论CT对甲状腺肿块的诊断虽然有很大价值,但是部分甲状腺肿块CT表现无特征性,定位诊断准确,定性诊断困难。