Janis V. Klavins

Pathology of amino acid excess: V. Effects of methionine on free amino acids in serum

Abstract When excessive amounts of methionine were administered in the diet for 4 weeks there were significant alterations in serum amino acid composition. There was increase of methionine, α-aminobutyric acid, lysine, and glutathione. Serine and glycine were decreased when compared with the values of control animals. In addition, there was decrease of threonine, valine and leucine when serum amino acid levels of rats fed excess methionine were compared with the control animals according to their percent distribution. The profiles of serum amino acids in rats fed methionine excess, except for alanine and leucine, correlated with values calculated from Michaelis-Menten kinetics with respect to presumed concentrations of these amino acids in the gastrointestinal tract. In normal rats those amino acids which are known to have lower affinity for intestinal transport system were in higher concentrations in the serum. The effect of methionine in lowering the serum amino acid concentration was more evident in those amino acids, with the exception of lysine, which are normally in serum at higher concentrations than methionine. The elevated serum glutathione levels were attributed to possible release of this compound from the red blood cells due to methionine-excess induced hemolysis.

Xanthine Oxidase Activity and Iron Storage in the Liver.

Summary Sodium tungstate was added to the diet to decrease liver xanthine oxidase activity. There were no concomitant changes in liver iron or iron absorption associated with the decrease in xanthine oxidase activity.

Influence of transferrin saturation on the effect of intraluminal fructose or histidine on iron absorption.

Summary The influence of transferrin saturation on the enhancement of iron absorption by intraluminal histidine or intraluminal fructose was studied in rats. A loop of lumen immediately distal to the pylorus was perfused in vivo with a solution containing Fe59. The greatest amount of Fe59 absorption was noted when the perfusate was supplemented with histidine or with fructose. When the perfusate in the intestinal lumen was not supplemented, or when it was supplemented with histidine, increase in transferrin saturation did not influence the iron absorption in each instance. However, when the perfusate contained fructose, the transferrin saturation had a lessening effect on the amount of iron absorbed. Histidine supplement to the perfusate caused a rapid transit of iron across the intestinal mucosa, since there was significantly less iron retained in the mucosa in the face of a high level of iron absorption.

Depression of Liver Affinity for Iron with Iron Overload.

Summary When liver slices were incubated in Ringers solution containing Fe59 the uptake of the radioactive iron was significantly decreased if the rats were previously overloaded with iron parenterally. Oral administration of iron did not produce the same degree of overload, and subsequently there was no significant decrease in the affinity of the liver for Fe59 in vitro. The deposition of histochemically demonstrable iron in the liver was associated with the presence of a DPAS positive material and acid phosphatase.

Unusual liver pathology associated with xanthomatosis and jaundice. Report of a case.

SummaryA 56-year-old man developed insidious progressive jaundice with xanthomatosis. The laboratory findings indicated biliary obstruction but the biliary outflow tract was patent. Serial biopsies and postmortem examination of the liver revealed the centrilobular deposition of collagen-like material. The resemblance of the clinical picture to primary biliary cirrhosis and the possibile relationship of hepatic changes to cardiac failure are discussed, but the etiology of the findings in this case is unknown.