The Contribution of Subunits of Thyroid Stimulating Hormone to the Binding and Biological Activity of Thyrotropin

The binding of bovine TSH (thyroid stimulating hormone), LH (luteinizing hormone), and their subunits to the TSH receptor of beef thyroid membranes was compared to stimulation by these agents of adenylate cyclase [ATP pyrophosphate-lyase(cyelizing), EC 4.6.1.1] in the same membranes, glucose oxidation in dog thyroid slices, and the secretory process in mouse thyroids in vitro (colloid droplet formation) and in vivo (hormone release). The beta-subunits of TSH and LH can bind to the TSH receptor and can activate thyroid function in vitro. In contrast, the alpha-subunit of TSH binds negligibly to the TSH receptor and has very low potency for stimulation of thyroid function (except for colloid droplet formation). Neither binding nor the biological activity of the beta-subunits can be accounted for by TSH contamination, whereas this cannot be ruled out for alpha-TSH. LH binds to the TSH receptor even better than the beta-subunit of TSH but the increased binding does not result in a corresponding activation of thyroid function. Neither alpha- nor beta-TSH alone can induce more than 4-8% of the response to intact TSH in any of the investigated parameters. It is proposed that the beta-subunit has within its structure the primary determinants which are necessary to stimulate biological activity, whereas the alpha-subunit imposes conformational changes on the beta-subunit which in intact TSH promote binding and biological activity commensurately but in LH promote only binding.     

Die Bestimmung des schwach gebundenen Aldosterons im Plasma Gesunder und Kranker

Ohne ZusammenfassungDurchgeführt mit Mitteln der Deutschen Forschungsgemeinschaft und der Hotchkiss-Heyn Foundation.     

10. Lebertransplantation

Ohne Zusammenfassung

---

Transplantation of the liver

     

Amino acid and protein requirements in a preterm infant with classic phenylketonuria.

A preterm infant with classic phenylketonuria required rather less than 90 mg/kg of phenylalanine and between 270 and 290 mg/kg tyrosine daily to achieve a rate of weight gain of around 20 g/kg per day. Using Lofenalac as the low phenylalanine food, the intake of tyrosine, an essential amino acid for patients with phenylketonuria seemed to be limiting in respect of growth.