Citations

Abstract Rapid formation of C14-bilirubin from glycine-2-C14 or δ-aminolevulinic acid-4-C14 has been demonstrated in isolated, perfused rat liver. The kinetics of labeled bilirubin production in vitro were similar to those of the "early labeling" pigment fraction observed in intact rats. The magnitude of bile pigment formation from C14-ALA by isolated liver was comparable to that in intact animals. Derivation of the C14-bilirubin from hepatic degradation of labeled hemoglobin was excluded by perfusion of the liver with blood poor in reticulocytes, or with plasma. The findings identify the liver as an important source of the "early-labeling" pigment fraction.

Abstract A simple test is proposed for evaluating the gastrointestinal absorption of iron. It begins with an oral dose of 50 µg. of stable iron labeled with 1 µc. of Fe59, to which about 300 mg. of ascorbic acid are added. Feces are assayed for Fe59 until any single stool contains less than 1 per cent of the dose. Absorption is determined on the assumption that all unrecovered Fe59 has been absorbed. The test was designed to minimize handling of stools by assaying whole specimens, and this process has the added virtue of increasing statistical accuracy of the measurement of radioactivity. The main advantage of the procedure using a 50 µg. dose is that with it one obtains a normal value for absorption which is about one-half of the dose. This permits measurement of either increased or decreased iron absorption. With our standard test method, 19 normal women absorbed an average of 62 per cent of the dose and 22 normal men absorbed 40 per cent. In addition to this sex difference, not explained by the difference in their blood hemoglobin levels, there seemed to be a tendency toward reduced absorption with greater age. Preliminary results of this test in patients with hypochromic anemia and steatorrhea are reported. Increased absorption of iron followed the administration of ascorbic acid whether the iron was in the ferric or the ferrous form. The concept that ferrous iron is better absorbed by man requires re-evaluation.

Abstract Thirty-six patients with active rheumatoid arthritis in whom anemia was slight were investigated, in part with radioiron and radiochromium, for abnormalities which might lead to anemia. The primary defect appeared to be a pronounced reduction of ability to absorb iron from the intestinal tract. There was an equally marked reduction in the serum concentration of iron which could not be attributed to the slight reduction in the iron-binding capacity of the serum. Despite the reduction level of iron in the serum, the apparent turnover of iron was so rapid that the total clearance per day was normal or moderately elevated. However, the fraction of the iron cleared from the blood and appearing in the circulation in newly synthesized erythrocytes was slighfly depressed. Erythrocyte survival was normal or very slightly shortened; hemolysis seems to play no important role. The fecal excretion of radioiron, not associated with erythrocytes, was greatly increased in two patients in whom there was no evidence of intestinal bleeding. A moderate increase in plasma vohime was common.

SummaryWhen 125I-labeled canine prothrombin was given to normal adult dogs intravenously, it was calculated that 240% of the plasma prothrombin crossed the capillary barrier per day, 410% of the interstitial prothrombin returned to the blood stream daily, and 79% of the plasmatic prothrombin was catabolized per day. These data are in close agreement with those observed for bovine prothrombin in calves by Takeda (1970).When derived from normal dog prothrombin, prethrombin-1 is a mixture of 2 polypeptides, one larger than the other, and both present in about equal amounts. The longer peptide, “prethrombin-1-long,” was catabolized twice as fast as prothrombin, and the shorter, “prethrombin-1-short,” 4 times faster. Prothrombin fragment-1 was catabolized by the normal dog still more rapidly.The catabolism of prothrombin was not accelerated in 3 dogs receiving continuous infusions of a thromboplastic emulsion of dog brain. Nor was the level of prothrombin in their plasma remarkably altered.

Copper-laden Bedlington terriers were found to absorb copper normally, based on the ratio of 64Cu in bile and in plasma ceruloplasmin after oral and intravenous doses of the radionuclide. The excessive accumulation of the copper in Bedlington terriers was due to impaired biliary excretion of the metal, The abnormal Bedlington pattern was simulated in normal dogs by biliary obstruction. Although the Bedlington terriers excreted more copper in their urine than normal, the amount was far less than that accumulated secondary to inadequate biliary excretion. These abnormalities are shared by patients with Wilson's disease, both conditions being inherited on an autosomal recessive basis. copper absorption; copper excretion; radiocopper; Wilson's disease Submitted on May 5, 1981 Accepted on March 30, 1982

About 100 µg of copper as cupric acetate-Cu64 was given iv to adult, male rats. Maximal concentrations of Cu64 were reached quickly in the excretory organs—liver, kidney, and gastrointestinal tract—which then slowly released their radioactivity. In most of the other organs a progressive accumulation of Cu64 began after the disappearance of most of the nonceruloplasminic Cu64 from the plasma and after ceruloplasmin-Cu64 emerged in the plasma, suggesting that ceruloplasmin may be the copper donor for the tissues. The disappearance of plasmatic Cu64 tended to parallel that from the liver after the first 48 hr.