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Biomedical subjects

E C Theil

Publications and source records attributed to E C Theil.

84 records · Page 5Linked to original sources
PubMed1978

The effect of copper excess on iron metabolism in sheep.

Sheep were treated with large amounts of copper (20 mg of CuSO4,5H2O/kg body wt. per day) for 9 weeks to examine the effect of copper excess on iron metabolism. In addition to confirming that massive haemolysis and accumulation of copper occurs in the liver, kidney and plasma after 7 weeks of exposure to excess copper, it was observed that excess copper produced an increased plasma iron concentration and transferrin saturation within 1 week. Further, iron preferentially accumulated in the spleen between 4 and 6 weeks of copper treatment, producing 3-fold increases in the iron content of both the ferritin and non-ferritin fractions. A 3-4 fold increase was also observed in the amount of ferritin that could be isolated from the spleen. The copper treatment had little or no effect on the concentration of iron in the liver and bone marrow. The following properties of erythrocytes were also unaffected by copper treatment: size, haemoglobin content and pyruvate kinase activity, although the erythrocyte concentration of copper increased after 6 weeks. Copper accumulated in the spleen between 6 and 9 weeks, probably owing to the phagocytosis of erythrocytes containing high concentrations of copper. The data suggest that copper excess influences iron metabolism, initially by causing a compensated haemolytic anaemia, and later by interfering with re-utilization of iron from ferritin in the reticuloendothelial cells of the spleen.

Animals↗
PubMed1976

The abundance of ferritin in yolk-sac derived red blood cells of the embryonic mouse.

Circulating red blood cells formed early in development have several distinctive properties which include retention of the nucleus (mammals), large size and characteristic haemoglobin type (mammals, birds, amphibia). The primitive or embryonic red cells of early development are replaced by the definitive red cells which contain fetal or adult haemoglobin; a second developmental change occurs in the haemoglobin of some mammals (man, cattle, sheep) but does not involve a cell replacement. Circulating yolk-sac derived red cells from embryonic mice are siderocytes; elevated ferritin levels are associated with the circulating red cells of bullfrog tadpoles, but not with those of the adult frog, again indicating that red cell iron metabolism can change during development. In order to extend the observations made on an amphibian to a mammal, the ferritin content of circulating red cells from embryonic mice was determined and found to be 0.65 mg/100 mg of soluble protein; no ferritin (less than or equal to 0.007 mg/100 mg of soluble protein) was detected in adult mouse red cells. Elevated ferritin levels appeared to be specifically associated with the yolk-sac derived population of red cells since a decline in red-cell ferritin content coincided with the replacement of yolk-sac derived red cells by definitive red cells derived from the liver. Fractionation of mixtures of yolk-sac derived and liver derived red cells showed that fractions rich in the definitive red cells contained less ferritin than the mixture. The results suggest that elevated ferritin levels may be a general characteristic of the circulating, haemoglobinized red cells formed early in development.

Aging↗
PubMed1975

Cathodal proteins from primitive (embryonic) red cells of amphibia. Isolation and characterization.

A group of abundant (15% of the soluble protein) nonhemoglobin proteins was isolated from the primitive (embryonic) red cells found in tadpoles, using the cationic properties of the proteins at pH 8.6 to separate them from hemoglobin and other red cell proteins. The cathodal proteins (CP) were resolved into five components, and the two most predominant proteins were separated and characterized. Purified CP-1b and CP-2 had an amino acid composition similar to that of unfractionated cathodal proteins and to each other, except for small variations in the lysine and half-cystine content. The molecular weight of the purified CP-1b and CP-2 was 13 to 14,000, determined by gel filtration chromatography and electrophoresis in the presence of sodium dodecyl sulfate. Cathodal proteins were immunologically related although there were quantitative differences in reactivity. The concentration of cathodal proteins in primitive (embryonic) red cells was 100 times that in definitive (adult) red cells coincided with the replacement of primitive red cells. The synthesis of the cathodal proteins appeared to continue throughout the life of the primitive red cells; when hemoglobin synthesis declined in primitive red cells, approximately half of the protein synthesized by the cells was cathodal protein. Although the function of the cathodal proteins is as yet unknown, the data suggest that the cathodal proteins are a unique characteristic of erythroid differentiation in early development.

Amino Acids↗
PubMed1969

Expression of the arginine regulon of Escherichia coli W: evidence for a second regulatory gene.

Effect of the M (modifier) gene of Escherichia coli W on the expression of wild-type structural genes of four arginine biosynthetic enzymes was studied by examining enzyme activity in cell-free extracts of cultures grown in minimal medium and medium containing arginine. The mutant M gene was originally identified as causing arginine-induced synthesis of acetylornithine delta-transaminase in a strain deficient for the enzyme. The strains used in this study received the mutant M gene by recombination. Noncoordinate repression has been demonstrated for two more enzymes of the arginine regulon of E. coli W and the M(-) gene increases the degree of noncoordinate repression for the regulon. Mutation of the M gene results in altered regulation of acetylornithine delta-transaminase, ornithine transcarbamylase, and acetylornithinase. In addition, a decreased growth rate is observed. It is proposed that the M gene is a regulatory gene. A model is presented to explain the data which involves changes in operator-repressor affinity for the structural genes and possibly for the gene controlling arginyl transfer ribonucleic acid synthetase.

Amidohydrolases↗