Mary L. Parker

STUDIES ON HUMAN GROWTH HORMONE. II. THE PHYSIOLOGICAL DISPOSITION AND METABOLIC FATE OF HUMAN GROWTH HORMONE IN MAN

The metabolic effects of human growth hormone have received much attention, but little is known regarding the metabolism of the hormone itself in man. Studies of growth hormone metabolism carried out in experimental animals suggest that both bovine growth hormone and human growth hormone have rapid turnovers. Van Dyke, Simpson, Li and Evans (1) and Gemzell, Heijkenskjdld and Str6m (2) injected rats with large doses of bovine growth hormone and determined plasma levels of growth hormone by the tibial cartilage width assay. The half-lives of disappearance were 26 and 40 minutes, respectively, in the two studies, and the volume of distribution of the hormone was roughly equivalent to the extracellular fluid space. Isotopic methods have also been applied to the study of growth hormone metabolism. Sonenberg and co-workers (3) injected rats with radioiodinated bovine growth hormone and, although their work was principally concerned with tissue localization, they published a graph depicting the disappearance of radioactivity from plasma after a single intravenous injection. The half-life of disappearance was approximately 25 minutes. In the experiments of Salmon, Utiger, Parker and Reichlin (4), radioiodinated human growth hormone had a half-life of disappearance from plasma of 17 minutes when injected into rabbits. Only preliminary reports of the disappearance

Infants of Diabetic Mothers

Of six infants of gestational diabetic mothers (IGDM), the levels of insulinwere high in four during the first week of life; levels of free fatty acid and glucose tended to be low. Growth hormone values were within normal limits. In six infants of overt diabetic mothers, five had significant hypoglycemia; three were symptomatic. Growth hormone levels were within normal limits. There was a positive correlation between the mothers blood glucose and the infants insulin level at delivery in five of the IGDM. After birth, a negative correlation was found between the infants blood glucose and the plasma insulin. There was apositive correlation between weight and insulin levels at birth in twenty normal infants and five growth hormone levels and birth weight 1967.

Cryoablation of the Pituitary in the Treatment of Progressive Diabetic Retinopathy

Sixteen diabetic patients with sight-threatening progressive diabetic retinopathy who were carefully screened ophthalmologically, endocrinologically and medically, underwent stereotaxic transphenoidal pituitary cryoablation and were followed for an average of 26.2 months postoperatively. Hypophysectomy was complete or borderline in fifteen of the sixteen patients with no serious complications except chronic diabetes insipidus in one patient. Two patients died of nonsurgically-related conditions four and one-half and twentyfive months respectively after operation. Endocrine management was uncomplicated except for reversible cholestatic jaundice due to oral methyltestosterone in one patient. Insulin requirements were reduced in most instances following pituitary cryoablation. Ocular improvement occurred in ten of the sixteen patients with two patients stable, indicating a 75 per cent success rate. It is concluded that cryoablation offers a safe, reproducible, simple and effective method of pituitary ablation in well-selected patients with progressive diabetic retinopathy and threatening blindness.

Effects of Human Growth Hormone (HGH) on 79 Hypopituitary Children

We have treated 58 idiopathic (IH) and 16 organic hypopituitary (OH) children for 12 months, using 5 treatment regiments, in order to determine optimum therapy with HGH and glucocorticoids. All patients had: growth hormone levels < 5 mμg/ml plasma during insulin induced hypoglycemia; bone ages of 12 years or less; sexual infantilism. In IH, height wa −4 SD or further below the mean. In OH, pretreatment growth rate was below 2.5 cm/year. Listed are 5 treatment regimens and growth rates during therapy.Conclusions: HGH stimulated linear growth of hypopituitary children to varying degrees; more effectively in younger smaller dwarfs, less effectively in the older larger or cortisone treated dwarfs. HGH from embalmed bodies is clinically useful. HGH, 10 U., was not more beneficial than 2 U. The craniopharyngiomas in the OH did not grow during short-term treatment with HGH.

Growth hormone levels in premature and full-term infants

to alter its antigenic and biologic properties, a new labeling method was devised. Purified human growth hormone was acetylated with acetic-l-C 14 anhydride, resulting in addition of 1.2 to 4.0 acetyl groups per molecule. Acetylated human growth hormone was demonstrated to be biologically (rat growth response) and antigenically (agar gel diffusion) identical to unlabeled hormone. This new labeling procedure permits studies of the chemical and biologic properties of growth hormone which is unaltered by the labeling procedure. The demonstration of the transport mechanism in human plasma represents the initial application of this new labeled hormone preparation.