ABSTRACT
The experimental conditions in the potentiometric method for the determination of the iodine-binding capacity (Ib) of starch and amylose [R. L. Bates, D. French, and R. E. Rundle (1943) J. Amer. Chem. Soc. 65, 142-148] were not suitable for glycogen because of the much lower affinity for iodine of the latter. This difficulty was overcome by titration of small volume with both the iodine and glycogen at high concentration. Using the concentration cell circuit Pt electrode-blank-bridge-glycogen-Pt electrode, small increments of standard iodine solution were added to the blank solution and each was titrated to null by adding iodine to the glucogen solution [G. A. Gilbert and J. V. R. Marriott (1948) Trans. Faraday Soc. 44, 84-93]. Glycogen was determined by an anthrone-sulfuric acid method [F. W. Fales (1951) J. Biol. Chem. 193, 113-124]. Glycogens with Ib's ranging from 1.8 to 5.3% were observed.
Subject(s)
Glycogen/analysis , Iodine , Animals , Anthracenes , Chemical Phenomena , Chemistry , Glucose Oxidase , Glycogen/isolation & purification , Liver/metabolism , Methods , Muscles/metabolism , Potentiometry , RabbitsABSTRACT
Clearance of 0-100 mg/L concentrations of galactose from the blood depends on nutrient hepatic blood flow. We can measure such concentrations, which was not previously possible, by a continuous-flow method involving the use of galactose oxidase and peroxidase, the latter being coupled to a fluorogenic substrate, p-hydroxyphenylacetic acid. Interfering substances in the peroxidase reaction are removed by zinc/alkali precipitation. Sensitivity is maximized by using saturating concentrations of the enzymes and substrate. In prepared plasma test samples with galactose concentrations of 10, 40, 70, and 100 mg/L, the within-run CV's ranged from 2.1 to 8.6%, and day-to-day CV's from 2.2 to 17.2%, the largest CV's being for the 10 mg/L concentration. Normal subjects are shown to clear galactose more efficiently than subjects with moderate cirrhosis.
Subject(s)
Fluorometry/methods , Galactosemias , Anticoagulants , Galactose , Humans , Liver/blood supply , Liver Cirrhosis/blood , Regional Blood Flow , Specimen HandlingABSTRACT
Plasma urea and protein determinations proved suitable for measuring changes in total diffusible water and plasma volume in whole blood. Deoxygenation by saturation with carbon dioxide at 25 degrees C caused no change in plasma urea, but a significant increase in plasma protein concentration was induced with both normal and sickle-cell (HbSS) blood. Thus in HbSS blood there was no binding or trapping of water as a result of sickling and there was a normal influx of water into the cells (Bohr effect) despite the polymerization of the hemoglobin molecules with sickling. Consistent with this observation was the finding that the deoxygenation induced a similar increase in concentration of the plasma cations, sodium plus potassium. HbSS erythrocytes neither lost nor gained water under the more physiologic conditions of deoxygenation with a 95% nitrogen, 5% carbon dioxide gas mixture.
