Seymour J. Gray

THE TAGGING OF RED CELLS AND PLASMA PROTEINS WITH RADIOACTIVE CHROMIUM

In preparation for the present study, arc spectrography 3 was used to demonstrate the presence of trace amounts of chromium in human tissues, including the blood. Tissue analyses were performed on samples of normal human blood by means of a colorimetric method (2) with the finding of mean values of 20 y % for packed red cells and 14 y % for plasma. The present report is concerned with a new biological tracer, radioactive chromium (Cr51), which is bound by the red cells and plasma proteins. Both anionic hexavalent (Na2Cr51O4) and cationic trivalent (Cr51Cl3) states of the element have been studied.

DETERMINATION OF THE CIRCULATING RED CELL VOLUME IN MAN BY RADIOACTIVE CHROMIUM

The circulating red cell volume of man and animals has been investigated heretofore by the injection of red cells labeled with the radioisotopes of iron (Fe55 and Fe59) and phosphorus (P32) (1-10). The preparation of red cells tagged with radioactive iron necessitates the administration of radioiron for one or more weeks to volunteer donors who incorporate it into the hemoglobin of their red cells (1, 2) which must then be transfused into the experimental subject. Radioactive phosphorus may be added in vitro to a small volume of the experimental subjects own red cells which become labeled rapidly. This technical advantage, however, is counter-balanced by the rapid phosphate exchange in vivo between the red cells and the plasma, causing the radioactivity of the tagged cells to fall significantly after one to three hours (5-8). In the present investigation a new biological tracer, radioactive chromium (Cr51), with a halflife of 26.5 days, has been employed for the determination of the circulating red cell volume. When this isotope was added to erythrocytes in vitro as Na2Cr5104, it was taken up avidly by the red cells, which retained their radioactivity without significant loss to the plasma for periods of one day or more after injection into experimental animals (11). Since the exchange of Crp5 between the red cells and plasma was negligible for 24 hours, radioactive chromate appeared to be ideal for the tagging of red blood cells and the measurement of the circulating red cell volume. The application of this method to studies in dogs

Gastric Secretion in Human Hepatic Cirrhosis

Summary 1.Gastric secretory function was measured in patients with hepatic cirrhosis by means of uropepsin excretion, blood pepsinogen level, and gastric output of acid and pepsin, both basally and after histamine. 2.In patients with decompensated cirrhosis all of the above secretory parameters were significantly reduced to below normal, and histamine achlorhydria was found in one-third of these subjects. 3.Cirrhotic patients who were not malnourished or decompensated exhibited the same marked reduction in gastric secretion; this suggests that chronic illness is not the cause of the diminution in gastric function. 4.Uropepsin and blood pepsinogen values were as low in postnecrotic and biliary cirrhosis as in alcoholic cirrhosis, indicating that alcoholism itself is not responsible for the decreased gastric activity. 5.Free 17-hydroxycorticosteroid levels were normal in both the plasma and urine of cirrhotic subjects, excluding reduced adrenal function as the cause of the reduced gastric secretion. 6.Gastric secretion and uropepsin excretion were higher in patients with both peptic ulcer and cirrhosis than in those with cirrhosis alone. 7.Gastric acid output, both basally and after histamine, was higher in cirrhotics with portacaval shunt than in cirrhotics without shunt. In 1 patient a marked increase over preoperative secretion was noted simultaneously with the development of a gastric ulcer after splenorenal shunt. Possible causes for these effects were discussed.

Intestinal Absorption of Essential Amino Acids in Man

Summary Equimolar mixtures of the eight essential l-amino acids at varying concentrations (1 to 20 mm) and in amounts usually present in a protein meal were perfused in the jejunum of man and the intestinal absorption kinetics determined. A characteristic sequence and order of amino acid absorption from the mixtures was observed which was constant for each of the amino acids. The absorption rates were most rapid for methionine and the branched amino acids, and slowest for threonine. The succus entericus of the upper jejunum in the fasting state and after perfusion with isotonic saline contains small amounts of amino acids, with leucine and lysine predominating. In an amino acid mixture amino acids may inhibit the absorption of one another if they share a common transport system. The absorption rate of threonine perfused in an equimolar mixture containing the other essential amino acids was markedly decreased compared to its absorption rate when perfused alone in identical concentrations.

The simultaneous determination of red cell mass and plasma volume in man with radioactive sodium chromate and chromic chloride.

The use of radioactive chromium in the determination of the circulating red cell mass (1, 2) and the plasma volume (3, 4) in man has been reported previously. Anionic hexavalent chromium (Na2Cr5104) is readily taken up by erythrocytes in vitro and retained by them after reinjection without appreciable loss to the plasma for approximately 24 hours. Cationic trivalent chromium in the form of chromic chloride readily tags plasma proteins in vivo and in vitro. At least 98 per cent of the radioactive chromic chloride is bound to the plasma proteins with minimal loss of the isotope to the red cells. Because of the selective affinity of erythrocytes for hexavalent anionic Cr5l and of the plasma proteins for trivalent cationic Cr5l, it seemed possible to use these two forms of the isotope for the simultaneous determination of red cell mass and plasma volume in human subjects. Simultaneous measurements of red cell mass and plasma volume were made on ten normal adult subjects with radioactive chromium. The accuracy of the combined technique was confirmed by making determinations immediately before and after the transfusion of a measured volume of blood.

Chemical and histologic demonstration of hydrochloric acid-induced release of serotonin from intestinal mucosa.

Summary Reduction of the serotonin content of the upper small intestine of the rat and degranulation of argentaflin cells were produced by perfusion with 0.1 N hydrochloric acid in physiologic amounts. A small fraction of intestinal 5-hydroxytryptamine was recovered intraluminally, which indicated a release phenomenon. It is suggested that acid-induced serotonin release may occur under physiologic circumstances.

Clinical Use of the Urinary Uropepsin Determination in Medicine and Surgery

MEASUREMENT of the excretion of pepsinogen in the urine (uropepsin) has been recommended as a quantitative test for gastric secretory function by a number of investigators.1 2 3 4 5 6 7 It has been...

ADRENAL INFLUENCES ON THE STOMACH: PEPTIC ULCER IN ADDISON'S DISEASE DURING ADRENAL STEROID THERAPY

Excerpt A relationship between the adrenal gland and the stomach has been demonstrated by an increased gastric acid and pepsin secretion during adrenal stimulation. The adrenal gland has been impli...

Effect of AGTH Upon Gastric Secretion.

Summary ACTH administered intramuscularly to normal subjects in doses of 100-160 mg daily for periods of 3-4 weeks produced a marked increase in the basal gastric secretion of hydrochloric acid and pepsin associated with an equally significant rise in the urinary uropepsin excretion. In every instance these values were increased to the levels usually observed in patients with active peptic ulcer. These studies indicate that an endocrine relationship exists between the stomach and the adrenal gland and that a hormonal phase of gastric secretion may be mediated by the adrenal corticoids. The pathway by which chronic emotional and physical stress may affect the stomach by a hypothalamus-pituitary-adrenal-gastric pathway is discussed.

Stimulation of Gastric Secretion in Man by a Serotonin Antagonist

Summary The administration of the serotonin antagonist, 1-methyl- d -lysergic acid butanolamide bimaleate (UML-491), to peptic ulcer patients produced striking elevations in gastric secretion of hydrochloric acid, both during the basal state and during stimulation with histamine. The prior infusion of the serotonin precursor, 5-hydroxytryptophan, inhibited the stimulatory effect during the basal state. The possibility that endogenous serotonin may have an inhibitory influence on gastric secretory function is considered.