Smith Freeman

Lipogenesis by adipose tissue, dietary effects.

Summary 1. The incorporation of C14-acetate into lipid and carbon dioxide by rat adipose tissue (in vitro) was investigated. This investigation concerned the effect of the nutritional status upon the lipogenic activity of adipose tissue. 2. Fasting was found to produce an increase in nitrogen concentration and a decrease in lipid concentration and lipogenic activity. 3. In normal rats lipogenic activity of the tissue was found to increase during recovery feeding following fasting. The increased activity was paralleled by increased nitrogen and glucose content of the tissue and by decreased lipid content. 4. Lipogenic activity of adipose tissue of rats could be made relatively constant by depletion of fat stores followed by recovery feeding.

The use of high centrifugal force in separating plasma calcium into its protein-bound and protein-free fractions

Abstract The method of obtaining protein-free calcium in plasma using the Spinco/ Beckman Model L Preparative Ultracentrifuge was investigated. It proved to be a simple procedure of high precision requiring the minimum of manipulation. The pH and temperature were easily and effectively controlled throughout the procedure. Equilibration with CO 2 was eliminated. The protein-free calcium in 14 normal subjects was 53.5% of the total plasma calcium as compared with 60% in 3 cases of hyperparathyroidism.

Effect of Aspergillus fumigatus endotoxin on the respiration and phosphorylation of kidney tissue.

Abstract The nephrotoxin in mycelial extracts of Aspergillus fumigatus produces morphological changes resembling those observed in mercuric chloride poisoning in vivo . The toxic factor has been purified by ammonium sulfate precipitation and chromatographic fractionation. This paper presents the effects of purified toxic extracts on mouse kidney homogenate and mitochondria in vitro . Homogenate respiration rate was a function of substrate concentration. In the presence of succinate or ascorbate, respiration increased to a high plateau with increasing substrate concentration, whereas with citrate, malate, or other pyridine nucleotide-linked substrates, the rate increased to a low maximum and then decreased. At optimal concentration of substrates, respiration was stimulated by low concentrations of toxin but depressed by high concentrations. A much lower concentrations of toxin produced these effects with citrate than with ascorbate or succinate. Similar patterns of stimulation and depression were obtained with 2,4-dinitrophenol. Complete uncoupling of oxidative phosphorylation, as judged from the P:O ratio, was evident with both succinate and citrate at higher toxin concentrations. This uncoupling effect disappeared when nephrotoxicity was inactivated by heat, although some respiratory inhibition effect persisted. The previously reported hypercitricemia after intravenous administration of a lethal dose of toxin to mammals is probably due to suppression of citrate oxidation.

Effect of Protein Depletion on Response to Water, Sodium Chloride and Pituitrin

Summary 1. The time required to excrete 50% of an ingested water load was increased in 3 protein-depleted dogs. 2. The glomerular filtration rate was reduced in all protein-depleted dogs. 3. The urinary suppression produced by pituitrin was increased in the protein-depleted dogs.

Inhibition of steroid-mediated transhydrogenation and dehydrogenation by Δ4-3-oxosteroids

Abstract Transhydrogenation from TPNH to DPN by an enzyme preparation from rat liver was mediated by 4.10 −6 M androsterone. The Δ 4 -3-oxosteroids inhibited this transhydrogenation at concentrations of 10 −7 to 10 −6 M . The majority of the transhydrogenase inhibitors also inhibited DPN- and TPN-dependent dehydrogenation of androsterone. The inhibitory influence on hydrogen transfer was potentiated by the introduction of an additional double bond in ring A but depressed by substitution on position 17. Certain steroids, such as 19-nor-4-androstene-3α, 17β-diol, were active substrates for the dehydrogenases and did not inhibit dehydrogenation of androsterone but significantly inhibited transhydrogenation, which suggests that the dehydrogenases and transhydrogenase may be separate systems.

Urinary Excretion of Corticosteroids and Neutral 17-Ketosteroids in Adult Female Dogs

Summary Normal values for neutral 17-ketosteroids and reducing corticoids have been presented for adult female mongrel dogs. Stimulation of the adrenal glands of the dog by continuous intravenous infusion of ACTH increased both the reducing corticoid and neutral 17-ketosteroid excretion. Additional observations are reported regarding factors that influence the excretion of reducing corticoids by the adult female dog.

Demonstration, extraction and intracellular distribution of kidney phosphoprotein kinase activity.

Summary 1. A phosphoprotein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) was demonstrated in kidney. Phosphoprotein kinase activity was measured by determining the amount of 32 P transferred from [ γ - 32 P]ATP to 30–40% dephosphorylated Phosvitin. 2. Methods of extracting phosphoprotein kinase from kidney were investigated. 0.05 M Na 4 P 2 O 7 was found to be the best extractant. 3. Intracellular distribution of phosphoprotein kinase activity was studied in hog, rat and rabbit kidneys. The major portion of the phosphoprotein-kinase activity was found in the kidney-supernatant fraction. 4. Optimal conditions for the assay of kidney-phosphoprotein kinase activity were investigated. A bivalent metal ion was required and Mg 2+ produced optimal activation. Co 2+ , Mn 2+ and Ni 2+ also activated kidney phosphoprotein kinase. With an optimal concentration of Mg 2+ further activation was produced by potassium phosphate buffer, NaCl, KCl and Tris-HCl buffer. Phosvitin, 20–40% dephosphorylated by wheat-germ acid phosphatase (EC 3.1.3.2.), was the best substrate. 5. The effect of inhibitors on kidney phosphoprotein kinase was studied. Iodoacetamide, N -ethylmaleimide and KF had no effect on enzyme activity. 2,4-Dinitrophenol inhibited kidney-phosphoprotein kinase. With an optimal concentration of Mg 2+ the addition of other metal ions produced inhibition. 6. A convenient method for the preparation and isolation of [ γ - 32 P]ATP of high specific activity is described. The portion of the glycolytic pathway from fructose 1,6-diphosphate to 3-phosphoglyceric acid was used. The substrates and enzymes are avallable commercially.

Effects of Age on Citrate Metabolism in Bone and on the Distribution of Skeletal Fluoride

Summary In calvaria and long bones of the rat the concentration of citrate changed in a pattern characteristic for the bone site during active growth; it remained relatively constant after growth was essentially complete (epiphyses 60 days, calvaria 75 days, diaphyses 90-113 days). In metaphyses (the growing zone of long bones) there was still reduced activity after this time since growth in long bone continues even in old rats. This procedure may be useful in determining maturity in other bone areas where rate of growth is difficult to assess by other methods, and in selection of the proper age and bone site for evaluation of the effects of various treatments. Differences in the citrate response to vitamin D and in the deposition of fluoride at various bone sites in growing rats could be correlated with the age at which growth in a given site was complete. Fluoride deposition also appears to be related to deposition of calcium in the site during fluoride ingestion. Most of the differences in distribution of skeletal fluoride can be explained on this basis. Fluoride acts much as the radioactive tracers and it may be that fluoride deposition could be used to measure calcium accretion during the bone remodelling process.

Comparison of the absorption and destruction of the lactone and salt form of glucuronic acid by dogs.

Comparative studies were made on the fate of d-glucuronolactone and d-glucuronate in dogs. The studies included: a ) measurement of the rate of conversion of the lactone into the salt form at various ph values ranging from 2.0 to 7.4; b ) measure of the rate of absorption from isolated loops of small intestine; c ) determination of the blood plasma concentration in relation to intestinal absorption of the two forms of glucuronic acid in normal, Eck fistula and nephrectomized animals; d ) the stability and magnitude of the plasma values were determined following the intravenous injection of the lactone or salt form of glucuronic acid into nephrectomized dogs. From the foregoing studies, it was determined that: a ) glucuronolactone is rapidly converted into glucuronate at the ph of plasma; b ) glucuronolactone is absorbed from the small intestine much more rapidly than is glucuronate; c ) absorbed glucuronolactone is metabolized rapidly while glucuronate appears to be relatively inert in the body and to occupy a space similar to that of inulin. The limiting factor in the metabolism of glucuronolactone is the rate of its conversion into the salt form.

Effect of alkalis on conjugation of sulfonamides with glucuronic and acetic acid.

Summary These studies indicate that alkalis, particularly sodium citrate and sodium lactate, may increase the conjugation of sulfamerazine and sulfadiazine with glucuronic acid and decrease conjugation with acetic acid in human subjects.