It has been reported by others and confirmed by the present workers that following the intravenous administration of insulin in the normal animal, the glucose concentration in venous blood may exceed that of arterial blood giving rise to a negative arteriovenous difference. The simultaneous administration of glucose enhances this effect. The present investigators have extended this work to the alloxan-diabetic animal (dog) and have shown that large negative arteriovenous blood glucose differences are obtained following administration of insulin and glucose. These differences are too great and too consistent to allow the contention that negative arteriovenous differences are simply the result of analytical errors.
The metabolic activity (as gauged by glycogen synthesis, glucose uptake and oxygen consumption per gram of wet tissue) was found to be increased in diaphragms taken from rats maintained on a low-protein diet compared to normal controls. There was no significant difference in these indices of metabolic activity when they were expressed on a per cell basis (calculated on the content of desoxyribonucleic acid phosphorus). In protein deprivation, the mass of the diaphragm cell was dependent upon the protein intake rather than the total caloric intake but the metabolic activity of the cell was independent of its mass. These findings suggest that the metabolic activity of a tissue may, under certain experimental conditions, be more suitably expressed on a per cell basis than on the more usual basis of wet weight of tissue.
A study has been made of the labelling of the phospholipids, the fatty acids from the acetone-soluble lipid, and the non-esterified cholesterol in slices of rat and guinea pig liver respiring in a suitably buffered Krebs–Ringer medium containing acetate-1-C 14 . The time course of the reactions and the effects of the concentration of potassium ion and the pH of the incubating medium have been defined. For phospholipid and fatty acids of the acetone-soluble lipid, the optimum pH was in the range 6.8–7.4, whereas for cholesterol there was a much sharper optimum at pH 6.6–6.8. When the oxygen of the gas phase was replaced with nitrogen, the labelling of all three lipid fractions was abolished. The addition of glucose to the incubating medium slightly increased the labelling of the phospholipids and the fatty acids of the acetone-soluble lipid, but had no consistent effect on the labelling of the non-esterified cholesterol. Purification of the cholesterol by the method of bromination and debromination caused only a slight change in specific activity, indicating that the cholesterol was not contaminated with large amounts of companion substances with specific activities greatly different from that of the cholesterol itself. The addition of cyanide, fluoride, iodoacetate, or 2,4-dinitrophenol to the incubating medium caused a great decrease in the labelling of all fractions studied. With the exception of 2,4-dinitrophenol, the inhibitors were used in concentrations that inhibit the oxygen consumption. Malonate inhibited the incorporation of acetate-1-C 14 into cholesterol, but did not affect the labelling of the phospholipids. When the acetate-1-C 14 was replaced with other C 14 -labelled precursors, good labelling of phospholipids was observed with glycine-2-C 14 , glycerol-1-C 14 , and fructose-C 11 , but not with formate-C 14 , lactate-1-C 14 , or glucose-C 14 . The cholesterol was not significantly labelled from any of the precursors other than acetate-1-C 14 .
A method for the determination of protein-bound iodine in plasma is described. It is based essentially on the method of Barker, Humphrey, and Soley, which makes use of the catalytic effect of iodide on the reduction of ceric ion by arsenious acid. A number of improvements have been made in the direction of ease of manipulation and an over-all saving of time.
A method is described for the photometric determination of amounts of calcium ranging from 0.04 to 0.16 mgm. The calcium is precipitated as the oxalate. The latter is converted to the carbonate by heating at 475° to 500 °C. for one hour. The carbonate is dissolved in 1 ml. of 0.01 N hydrochloric acid. The excess acid is allowed to liberate iodine by reacting with potassium iodate and potassium iodide. The absorption of the iodine solution is measured by use of an Evelyn colorimeter, and the calcium originally present in the sample is determined from calibration data.
A method for the determination of protein-bound iodine in plasma is described. It is based essentially on the method of Barker, Humphrey, and Soley, which makes use of the catalytic effect of iodide on the reduction of ceric ion by arsenious acid. A number of improvements have been made in the direction of ease of manipulation and an over-all saving of time.
In confirmation of the work of others, the concentration of inorganic phosphate (P) in the plasma of hypophysectomized rats was found to be less than that in the plasma of control animals. Hypophysectomy caused no significant change in the concentration of inorganic P in the adrenal gland or liver. A single intraperitoneal injection of each of two preparations of ACTH failed to cause any significant change in the concentrations of inorganic P in plasma, adrenal, or liver.The specific activity of the inorganic P in the plasma of hypophysectomized rats after an intraperitoneal injection of inorganic P labelled with P 32 was greater than that in the control animals. Hypophysectomy caused a decrease in the specific activity of the inorganic P of the adrenal gland relative to that of the inorganic P of the plasma. Each of the two preparations of ACTH, given to the hypophysectomized animals as a single intraperitoneal injection 20 hr. before killing, restored the relative specific activity of the inorganic P of the adrenals to normal values. When the ACTH was administered six hours before killing, one of the preparations (ACTH A) caused an increase in the relative specific activity of the inorganic P of the adrenals, but a second preparation (ACTH C) was without significant effect.The increase in the specific activity of the inorganic P of the plasma comes on slowly (quite small two days after hypophysectomy), whereas the decrease in the relative specific activity of the inorganic P of the adrenal gland comes on rapidly (maximal two days after hypophysectomy). For this reason, at longer time intervals after hypophysectomy (greater than six days) the absolute activity of the acid-soluble P of the adrenal, i.e. the activity not referred to that of the inorganic P of the plasma, was greater in hypophysectomized animals, and not less, as reported by other workers. The activity of this fraction is less in hypophysectomized animals only if the observations are made at short time intervals after removal of the pituitary. Evidence is presented for the view that the increase in the specific activity of the inorganic P of the plasma is the result of changes brought about by a deficiency of growth hormone, whereas the decrease in the relative specific activity of the adrenal is due to a deficiency of ACTH.
The oral administration of vitamin E to human subjects in dail doses of 600 mgm. for seven days failed to evoke any blood change in clotting times, prothrombin times, or plasma fibrinogen levels. There was a small increase in platelet level which was statistically of borderline significance.
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