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Biomedical subjects

M Lee

Publications and source records attributed to M Lee.

At least 1,135 records · Page 63Linked to original sources
PubMed1976

Oxygen-hemoglobin equilibrium of normal and glutathione-deficient sheep.

The affinity of hemoglobin for oxygen did not differ significantly between normal and glutathione-deficient sheep. Although phlebotomy in sheep of both types did not significantly alter the partial pressure values at which hemoglobin is 50% saturated with oxygen, it did increase significantly the erythrocyte glutathione and 2,3-diphosphoglycerate (GSH) and (DPG) concentrations. Because DPG does not bind to sheep hemoglobin, its increase in hypoxic sheep must mean DPG is metabolically controlled in the absence of physiologic effect.

Animals↗
PubMed1975

Transport properties of merodiploids covering the dagA locus in Escherichia coli K-12.

A membrane componenet of the dag transport system which serves for glycine, D-alanine, and D-serine is coded for by the dagA gene at minute 83 of the Escherichia coli chromosome. Merodiploid strains (dagA+/dagA+) show two to three times the transport activity for only those amino acids that are substrates of the dag transport system. The increased transport activity is a result of a two-to threefold increase in Vmax for amino acid uptake with little or no change in the Km value. The two- to threefold gene dose effect of the merodiploid strains is maintained even during carbon starvation, eliminating the possibility that a greater energy supply for transport activity may account for the effect. Since merodiploids which carry more than one copy of the dagA allele show a gene dose response for transport activity, we conclude that the membrane componenet of the dag transport system which is coded for by the dagA allele is present in limiting amounts.

Alanine↗
PubMed1975

Effect of oral administration of large quantities of ascorbic acid on blood levels and urinary excretion of ascorbic acid in healthy men.

The influence of the daily ingestion of 1, 2, 3, and 5 grams of ascorbic acid on whole blood and plasma ascorbic acid levels and on the urinary excretion of ascorbic acid has been investigated. The ingestion of one gram of ascorbic acid per day for one week significantly increases plasma and whole blood levels over presupplementation levels, but larger amounts of ascorbic acid do not further increase plasma and whole blood ascorbic acid levels. Urinary excretion increases with intake, up to intakes of 3 grams per day but does not increase further when 5 grams of ascorbic acid is ingested per day. Upon discontinuing ascorbic acid supplementation the plasma and whole blood levels decline rapidly and the urinary excretion of ascorbic acid falls to presupplementation values within a few days. The results suggest that there is need for a detailed study of the routes of excretion of ascorbic acid at high levels of intake and that the safety of ingesting large quantities of ascorbic acid may be questioned.

Adult↗
PubMed1974

T7 exonuclease (gene 6) is necessary for molecular recombination of bacteriophage T7.

The role of T7-induced exonuclease (gene 6) in molecular recombination was studied by examining the fate of parental DNA during parental-to-progeny recombination. The method used was to compare infections with T7(+), T7am-6-233 (am gene 6), or T7ts6-136 (ts gene 6) under permissive and nonpermissive conditions. CsCl density gradient analysis of replicative DNA indicated that T7 exonuclease is necessary for recombination to occur, i.e., in the absence of the exonuclease the parental DNA replicated continuously as a hybrid molecule and did not recombine. Further studies under conditions where replicative DNA was denatured and analyzed by CsCl density gradient centrifugation indicated that the exonuclease is also needed for a limited amount of covalent repair of recombinants. A repair function for the T7-induced exonuclease is also suggested by results obtained from alkaline sucrose gradient analysis of replicative DNA. Under conditions nonpermissive for the exonuclease, discontinuities in the DNA accumulated during infection by T7am6-233 or by T7ts6-136.

Bromodeoxyuridine↗