Plasma thyroxine levels in Duchenne muscular dystrophy

Some young Duchenne muscular dystrophy (DMD) patients (3-7 years) had total thyroxine (T4) levels and T4 to thyroxine binding globulin (TBG) ratios above the normal range and significantly increased free thyroxine indices (fT4I) which, however, remained within the normal range. Older DMD patients (7-11 years) had T4 and TBG levels and fT4I similar to normal. In both DMD groups the thyroxine binding index (TBI) values were in the normal range.     

Free thyroxine in myocardial infarction

High values for the free thyroxine fraction were found in the serum of 24 patients during the early phase of myocardial infarction. A strong correlation between the free thyroxine fraction and free fatty acids suggests that they compete for protein binding sites. The increase in free thyroxine may have undesirable effects on myocardial oxygen demand during acute myocardial infarction.     

Annual cycle of plasma testosterone and thyroxine in the European badger (Meles meles L.)]

In the male European Badger there are important variations in the plasma testosterone and thyroxine levels during the annual cycle. During the summer, plasma testosterone concentrations are low while plasma thyroxine rises to a very high level. In winter, when the thyroid activity is minimal, testicular activity increases. From February to May, the plasma testosterone remains at a high level, and then, after a sudden fall, a second peak occurs in June at which time the concentration of thyroxine is low.     

Plasma thyroxine levels in Duchenne muscular dystrophy

Summary Some young Duchenne muscular dystrophy (DMD) patients (3–7 years) had total thyroxine (T₄) levels and T₄ to thyroxine binding globulin (TBG) ratios above the normal range and significantly increased free thyroxine indices (fT₄I) which, however, remained within the normal range. Older DMD patients (7–11 years) had T₄ and TBG levels and fT₄I similar to normal. In both DMD groups the thyroxine binding index (TBI) values were in the normal range.     

Estimation of plasma thyroxine concentration in ducks in relation to different environmental and experimental conditions.

Plasma thyroxine concentration was measured in ducks by the thyroxine-binding globulin technique. The assay allowed us to detect annual variations in thyroid activity as well as significant changes after starvation or cold exposure. No detectable thyroxine was formed in surgically thyroidectomized ducks.     

Opposite effects of one and three injections of cortisone or thyroxine on intestinal lactase activity in suckling mice.

A single injection of cortisone or thyroxine to 8-day-old suckling mice initiates a temporary decrease of lactase activity. On the contrary, 3 injections of cortisone or thyroxine provoke a significant increase of lactase activity. It appears that the mechanism which controls the postnatal development of lactase in suckling animals is more complex than expected.     

Estimation of plasma thyroxine concentration in ducks in relation to different environmental and experimental conditions

Summary Plasma thyroxine concentration was measured in ducks by the thyroxine-binding globulin technique. The assay allowed us to detect annual variations in thyroid activity as well as significant changes after starvation or cold exposure. No detectable thyroxine was formed in surgically thyroidectomized ducks.Supproted by CNRS and the Department of Biology of the CEA.     

Effects of hypo- and hyperthyroidism on the activity of cystathionase in mammalian parenchymatous organs during early development

Summary In rats after neonatal thyroid destruction, cystathionase in liver and pancreas increased, but the enzyme activity in kidneys decreased. Substitution with thyroxine corrected these changes. Excess of thyroxine, too, had an effect on tissue cystathionase.     

Use of radioimmunoassay of "thyroxine binding globulin" to determine the concentration of free plasma thyroxine]

A relationship is proposed for calculating the concentration of free serum thyroxine using the measured values of thyroxine and thyroxine-binding globulin total concentrations. This calculation has been performed on a population of 335 patients. A good discrimination of the different thyroid diseases has been obtained.     

Effects of various hormones and adrenalectomy on the levels of amylase in rat pancreas and parotid gland.

Dexamethasone, adrenocorticotropic hormone and thyroxine increased the amylase activities in both the pancreas and the parotid gland of infant rats. After adrenalectomy, the amylase activities of the pancreas and parotid gland were about half the control levels, suggesting that both glucocorticoid and thyroxine are involved in maintaining the amylase activities in these organs.     

Opposite effects of one and three injections of cortisone or thyroxine on intestinal lactase activity in suckling mice

Summary A single injection of cortisone or thyroxine to 8-day-old suckling mice initiates a temporary decrease of lactase activity. On the contrary, 3 injections of cortisone or thyroxine provoke a significant increase of lactase activity. It appears that the mechanism which controls the postnatal development of lactase in suckling animals is more complex than expected.Supported by grant MA-5969 from the Medical Research Council of Canada to D. M. C. M. is a recipient of a studentship from MRC of Canada.     

Potency of thyroid hormone analogues in suppressing prolactin-mediated mammary growth in thyroidectomized rats.

An antagonism between prolactin and thyroxine, similar to that found in amphibian tissues at metamorphosis, has been recently shown to occur at the level of the rat mammary epithelium. This phenomenon may be implicated in the pathogenesis of human breast cancer. This experiment demonstrates that two analogues of thyroid hormone, triiodothyropropionic acid and triiodothyroacetic acid, which are relatively very weak in their calorigenic action, are as potent as thyroxine and triiodothyronine in inhibiting the prolactin-mediated mammary growth in thyroidectomized rats. The possible implication of this finding in the treatment of mammary cancer is discussed.     

Sexual differences in the development of plasma thyroxine levels in the embryo and young chick]

Plasma thyroxine (T4) levels were separately ascertained in male and female embryo and young chicken from the 12th day of incubation till the 4th day after hatching by the thyroxine binding globulin technique. In both sexes, plasma T4 reach a peak the 20th day of incubation, but values are significantly higher in females. A sharp decrease occurred thereafter, plasma T4 tending toward adult values the 4th day after hatching.     

Effects of thyroxine on the reproductive organs and growth of young chickens

Summary Male chicks of an egg-laying strain were injected with 0, 1, 2 or 4 g/100g b. wt thyroxine s. c. daily from 7 to 12 weeks of age. Increasing dose suppressed testicular development and puberty was completely blocked by the highest level. Live weight gain was enhanced by thyroxine treatment. Similar treatment of females prevented normal development of the ovaries at puberty.     

Effects of various hormones and adrenalectomy on the levels of amylase in rat pancreas and parotid gland

Summary Dexamethasone, adrenocorticotropic hormone and thyroxine increased the amylase activities in both the pancreas and the parotid gland of infant rats. After adrenalectomy, the amylase activities of the pancreas and parotid gland were about half the control levels, suggesting that both glucocorticoid and thyroxine are involved in maintaining the amylase activities in these organs.Acknowledgments. This work was supported by Grants-in-Aid for Cancer Research from the Ministry of Education, Science and culture, Japan, and the Ministry of Health and Welfare, Japan.     

Seasonal variations in the blood testosterone and thyroxine levels in the hedgehob (Erinaceus europaceus L)]

In adult male European Hedgehogs, which were studied outdoors, the plasma levels of both testosterone and thyroxine exhibited a marked annual cycle with a minimum in autumn and a maximum during spring and summer. The winter resumption of the testicular activity started already during the phase of hibernation and was concomitant with an increase of the plasma thyroxine level. The plasma titers of the two hormones dropped down together in August. The correlation between both hormones was less close from May through July.     

Freies Thyroxin im Serum durch Ultrafiltration

Summary A rapid determination of free thyroxine in human serum using¹²⁵J-thyroxine and pressure ultrafiltration is presented. Assaying per cent free thyroxine (PFT₄) more than 30 specimen/day can easily be established. The mean value of healthy controls is 0.030±0.010 (1 SD). Interference of results with height of pressure applied and duration of ultrafiltration resp. could not be detected. Both precision and sensitivity of this method allow further research and routine clinical employment.     

NMR-studies of triiodothyropropionic acid in ethanol-HCl.

The barrier to rotation in the N-acetyl methyl ester of the thyroxine was found to be 8.6 kcal mol-1. Previous experiments determining the barrier to rotation in triiodothyropropionic acid in HCl-ethanol were shown to be in error.     

Oxygen consumption in the rat following neonatal thyrotoxicosis.

Adult rats made thyrotoxic with large doses of thyroxine during the neonatal period had a lower oxygen uptake as compared with neonatal controls and those of neonatal calorically-deprivated ones.     

Oxygen consumption in the rat following neonatal thyrotoxicosis

Summary Adult rats made thyrotoxic with large doses of thyroxine during the neonatal period had a lower oxygen uptake as compared with neonatal controls and those of neonatal calorically-deprivated ones.