Control of cell growth. II. Requirement of thyroid hormones for the in vivo estrogen-dependent growth of rat pituitary tumor cells

A subclone of rat pituitary tumor cells, designated GH3/C14, was isolated from the parent population of GH3 pituitary cells and was estrogen-dependent for growth in vivo. GH3/C14 cells inoculated into host animals formed tumors in intact females, estrogen-treated ovariectomized females, and estrogen-treated males, but not in untreated intact or castrated males, or untreated ovariectomized females. Exogenous treatment with estrogens supported tumor formation in male animals. Radioimmunoassay of the average serum estradiol concentrations that support tumor growth in intact females, estradiol-treated intact females, and estradiol-treated intact males gave values of 41 +/- 4, 1,130 +/- 150, and 730 +/- 140 pg/ml, respectively. Tumor formation by GH3/C14 cells inoculated into male animals was not supported by either exogenous progesterone or hydrocortisone acetate. Further, these two steroid hormones had no significant effect on the estrogen-promoted growth in males or females. Exogenous testosterone treatment promoted tumor formation in males and ovariectomized females, but dihydrotestosterone was completely ineffective. Radioimmunoassay of the serum from tumor-bearing animals and the medium from the cells in culture showed that the cells produced growth hormone in vivo and in vitro but did not produce measurable amounts of luteinizing hormone or follicle-stimulating hormone. The groth of GH3/C14 cells in culture was examined in medium without added estrogen, and with estradiol added to the level of either the normal intact female rat or the estradiol-treated animals. No direct growth stimulation by estrogens could be detected in culture; the data suggested an indirect growth control mechanism.     

Relative importance of growth hormone and sex steroids for the growth at puberty of trunk length, limb length, and muscle width in growth hormone-deficient children

We have followed the growth of stature, sitting height, skinfolds, muscle widths measured radiologically, and skeletal maturity in growth hormone-deficient patients in whom hGH was given and withheld in alternating three-month periods throughout puberty (referred to as "off-hGH" and "on-hGH" periods). Six boys and four girls had true isolated GH deficiency and developed puberty spontaneously. Two boys had gonadotrophin deficiency plus GH deficiency, and five boys had multiple deficiencies; in these boys the signs of puberty were induced by hormone treatment. Boys with true isolated deficiency grew about two-thirds as much in height in the off-hGH periods as in the on-hGH periods; their total gain in height during the adolescent spurt would have been about 20 cm, instead of 30 cm, if hGH had been discontinued at the beginning of puberty. The effect of hGH was entirely on growth in leg-length, however, which virtually ceased during the off-hGH periods. Growth in sitting height altered little when hGH was withdrawn. Growth in limb muscles, however, was GH dependent throughout puberty; during the majority of periods when hGH was withheld, muscle was actually lost; this occurred in the boys who were receiving large doses of testosterone as well as in those producing their own normal amounts. Subcutaneous fat diminished when hGH was given and increased when it was withdrawn; this occurred independently of administration of testosterone. There was little evidence that growth of pubic and axillary hair progressed faster during on-hGH periods, except perhaps in patients with multiple deficiencies. There was some evidence, however, that bone age progressed less rapidly during on-hGH periods than during off-hGH periods in the patients with isolated deficiency. The results in the girls agreed with those in boys so far as stature was concerned, but the relationship with sitting height and leg length appeared to be different; the reasons for this are discussed. We conclude that all children with GH deficiency should continue on treatment with hGH throughout puberty, ideally until growth ceases.     

Althesin infusion for cardiac catheterisation

A trial of a continuous intravenous infusion of Althesin is described for sedation during cardiac catheterisation, both for children and adults. The conditions produced for the procedure were very satisfactory. The advantages and problems of its use are discussed. The technique justifies further trials.     

Synthesis and loss of activity of glucose-6-phosphate dehydrogenase in dividing plant cells

1. Using the technique of density-labelling with deuterium oxide, evidence has been obtained for the de novo synthesis of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADPH+ 1-oxidoreductase, EC 1.1.1.49), during the culture of synchronously growing plant cells. 2. The entire increase in enzyme activity during the early cell cycles in this material can be accounted for by the appearance of an enzyme species with increased buoyand density. 3. A method is described for resolving overlapping distribution profiles after density centrifugation, which allows estimation of the amount of each species present at different times, and calculation of the loss of activity of the light species present from the start of culture. 4. Loss of activity of glucose-6-phosphate dehydrogenase in normal growing conditions in the presence of 2,4-dichlorophenoxyacetic acid is very much faster than in conditions which do not lead to cell division: in the absence of 2,4-dichlorophenoxyacetic acid, or in the presence of the inhibitor of RNA synthesis, 6-methylpurine.     

Dissociation of beta-hydroxy-beta-methylglutaryl-CoA reductase activity from the overall rate of cholesterol synthesis in the liver following the intravenous administration of lipid

After the intravenous administration to the intact rat of triglyceride carried in either intestinal lipoproteins or in an artificial fat emulsion, the enzymatic activities of microsomal beta-hydroxy-beta-methylglutaryl-CoA reductase activity in the liver assayed in vitro became markedly elevated. This elevation of enzyme activity was not associated with a corresponding change in the overall rate of cholesterol synthesis in the rat liver slice as measured by the incorporation of either [3H]water or [1-14C]octanoate into nonsaponifiable lipids or into digitonin-precipitable sterols. The degree of dissociation of hydroxymethylglutaryl-CoA reductase activity from the overall rate of cholesterol synthesis correlated closely with the amount of lipid administered to the animal, the level of circulating lipids, and the level of ketone synthesis manifest in the liver cell suggesting that this phenomenon might be the consequence of a detergent effect of elevated cellular levels of fatty acids. In any event, under these experimental circumstances hydroxymethylglutaryl-CoA redutase activity no longer reflects the rate at which the liver cell is synthesizing cholesterol.     

Cathepsin D from horse spleen. I. Purification and study of certain physicochemical properties

Horse spleen cathepsin D (3.4.23.5.) was purified from crude extract by sodium chloride and ethanol precipitation, column chromatography fractionation on DEAE cellulose and CM Sephadex, re-chromatography on DEAE cellulose and gel filtration. The enzyme has been purified about 3.000 folds with a yield of 30 per cent. The purified enzyme seems to be homogeneous on Sephadex G100, one protein band is apparent on disc electrophoresis. Determined by dansylation the N-terminal amino acid is glycine. A molecular weight of 42,500 +/- 3,000 was obtained with Sephadex G100 gel filtration and light scattering measurements. Amino acid analysis and chemical determinations were performed: cathepsin D is a glycoprotein (2 or 3 osamine residues) including 344 amino acids and 4 disulfide bonds. Spectrophotometric data show that E1cm/1 mg/ml = 1.01 at lambda = 280 nm. ORD measurements indicate about 20 per cent of helicoidal content in the molecule.