Influence of dietary methionine on rat growth and thyroid activity

Résumé Une diète contenant 2.8% de méthionine a réduit la croissance et l'activité thyroïdienne du rat. La restriction de nourriture appliquée à des rats normaux a donné des résultats comparable. L'augmentation de la cystine dans cette diète pour obtenir le même taux de soufre n'a pas altéré la croissance ou l'activité thyroïdienne comparée à celle des rats normaux. En conclusion, la réduction de l'activité thyroïdienne des rats recevant un excès de méthionine est due à une insuffisance de nutrition.

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Journal paper No. 3769 of the Purdue University Agricultural Experiment Station.     

Influence of adrenal cortex on thyrocalcitonin content of the rat thyroid

Riassunto Il trattamento con ATCH o cortisone causa un aumento del contenuto in tirocalcitonina delle tiroidi di ratto. Vengono discusse le possibili implicazioni dei risultati ottenuti.     

Ethionine and methionine biosynthesis in rat liver

Zusammenfassung Injektionen von Ethionin oder Homocystein steigern die Transmethylierung in der Leber.     

Partial sparing of dietary methionine by lanthionine inArgyrotaenia velutinana larvae

Summary Lanthionine was able to partially spare the dietary methionine requirement ofArgyrotaenia velutinana (Walker) larvae but the sparing of methionine by lanthionine was not as efficient as cysteine. Partial sparing of dietary methionine by lanthionine, a non-member of the cystathionine pathway, indicated the possibility of sulphur amino acid metabolism by routes other than the cystathionine pathway.     

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat

Summary Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that bothV _max andK _m were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH₄ cofactor. TP replacement to castrate rats increased theK _m for added DMPH₄ cofactor, whileV _max decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzymereduced pteridine cofactor complex.     

Metal accumulation inAgaricus bisporus: Influence of Cd and Cu on growth and tyrosinase activity

Summary To investigate heavy metal uptake in the common mushroomAgaricus bisporus, commercial cultures of the fungus were exposed to different amounts of copper ad cadmium. In contrast to copper, cadmium already exerted pronounced toxic effects at low concentrations (>10 M) in the compost and concomitantly enhanced the uptake of copper. Tyrosinase activity measured in the fruit bodies increased sharply, when small amounts of Cd (10 M) were added to copper-rich compost. Gel filtration experiments with crude extracts from fruit bodies demonstrated the absence of a low molecular weight metal binding protein.Acknowledgments. This work was supported by the Schweizerischer Nationalfonds grant 3.420–0.78 (to K.L.) and by Hauser Champignonkulturen AG. We are indepted to Dr D. Rast for helpful discussions.     

Effect of adrenalectomy and dexamethasone treatment on the monoamine oxidase activity in the thyroid gland of the rat

Summary Adrenalectomy increased MAO activity in the thyroid gland of rats. The administration (200 g/100 g daily for 7 days) to adrenalectomized rats decreased MAO activity below levels of intact controls.     

Influence of age on epidermal growth factor receptor level in the rat brain

Summary The influence of age on¹²⁵I-epidermal growth factor (EGF) binding to rat brain plasma membranes was investigated. The specific binding of EGF to membranes decreased gradually with age in both male and female rats. There was no significant difference in the specific binding between males and females. Scatchard analysis of the binding data showed that the decrease in EGF binding with age was due to a decrease in the number of EGF receptors.     

Influence of age on epidermal growth factor receptor level in the rat brain

The influence of age on 125I-epidermal growth factor (EGF) binding to rat brain plasma membranes was investigated. The specific binding of EGF to membranes decreased gradually with age in both male and female rats. There was no significant difference in the specific binding between males and females. Scatchard analysis of the binding data showed that the decrease in EGF binding with age was due to a decrease in the number of EGF receptors.     

Influence of testicular fluid, spermatozoa and androgens on physiological activity of rat epididymis]

By ligation of the efferent duct and the corpus epididymis, the GPC concentration in this delimited anterior region decreased. However, HCG infection increased the GPC concentration. When spermatozoa are present in the epididymal tubule there is always a decrease in GPC concentration in these experimental conditions. Activity of the epididymis is disturbed by ligation.     

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat.

Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that both Vmax and Km were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH4 cofactor. TP replacement to castrate rats increased the Km for added DMPH4 cofactor, while Vmax decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzyme-reduced pteridine cofactor complex.     

Influence of dietary lactose on the development of lactase activity in the digestive tract of the pig]

Lactase activity has been measured in the pancreas, the small and large intestine of 79 pigs varying in age from 6-7 months. The endogenous enzyme level fluctuated along the small intestine but the activity did not vary according to the level of lactose fed in the diet either just after weaning or from 25 to 100 kg of live weight. Measurements performed in the content of the intestine showed that lactose could be digested by the enzymes of the microflora mostly active in the ileum, the caecum and the large intestine.