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Biomedical subjects

E Adams

Publications and source records attributed to E Adams.

At least 145 records · Page 8Linked to original sources
PubMed1975

Specificity of cell-mediated cytotoxicity against human melanoma lines: evidence for "non-specific" killing by activated T-cells.

The specificity of cell-mediated cytotoxicity against melanoma cells in vitro has been analyzed in a large number of studies with cells both from normal and melanoma subjects. As in a number of other, recent, similar human studies, no evidence for tumour specificity was found. Effector cells in peripheral blood responsible for the cytotoxic raction were examined by cell separation methods based on red cell rosette formation and separation through Hypaque-Ficoll mixtures. The evidence suggests that non-specificity results from killing by cells separating largely in the non-sheep red blood cell rosetting fraction and which have cytotoxic specificity directed broadly to cells with abnormal membranes. Further analysis revealed that the cells were non-phagocytic and did not bear receptors for complement. They appear to be activated into cell division and to bear surface receptors for the Fc portion of IgG. Additional evidence is presented suggesting that the cells mainly responsible are activated thymus-dependent cells present in the circulation of both tumour-bearing and normal subjects.

Antigen-Antibody Reactions↗
PubMed1975

Sequence position of 3-hydroxyproline in basement membrane collagen. Isolation of glycyl-3-hydroxyprolyl-4-hydroxyproline from swine kidney.

The position of 3-hydroxyproline was investigated in the triplet sequences of peptides released by collagenase digestion of a collagen preparation from kidney cortex. Composition of the collagen preparation indicated that it was largely or wholly of basement membrane origin. 3-Hydroxyproline was detected in only one sequence, the tripeptide, glycyl-3-hydroxyprolyl-4-hydroxyproline, which accounted for a major fraction of the total 3-hydroxyproline obtained in the peptides released by collagenase. Preliminary data, based on sequencing the peptide mixture released by collagenase treatment, suggested that, in contrast, 4-hydroxyproline occurs predominantly if not exclusively in the Y position of Gly-X-Y triplet sequences in the collagen preparation studied.

Amino Acid Sequence↗
PubMed1975

Formation and excretion of pyrrole-2-carboxylic acid. Whole animal and enzyme studies in the rat.

A corrected method for the measurement of pyrrole-2-carboxylate in rat urine was used in studies of its excretion under various experimental conditions. The findings implicated administered hydroxy-L-proline as a relatively efficient source of urinary pyrrole-2-carboxylate and tended to exclude administered L-proline as a significant direct source. Removal of aerobic gut flora had no influence on the excretion of pyrrole-2-carboxylate either endogenously or following hydroxy-L-proline administration. Related studied showed that rat kidney L-amino acid oxidase catalyzes oxidation of hydroxy-L-proline to delta1-pyrroline-4-hydroxy-2-carboxylate, which is converted to pyrrole-2-carboxylate on acidification of reaction mixtures. All findings were consistent with hydroxy-L-proline as the source of endogenous pyrrole-2-carboxylate excretion. Excretion patterns and labeling patterns were compared after administration of pyrrole-2-carboxylate or of hydroxy-proline epimers. From these data, the true excretion product of hydroxy-L-proline oxidation by L-amino acid oxidase appeared to be the unstable oxidation product, delta1-pyrroline-4-hydroxy-2-carboxylate, which is converted to pyrrole-2-carboxylate in urine. The capacity of homogenates of guinea pig kidney and human kidney to carry out oxidation of hydroxy-L-proline to pyrrole-2-carboxylate was much less than that of rat kidney, consistent with the lower levels of urinary pyrrole-2-carboxylate in these species. Experiments designed to examine the modest increase of pyrrole-2-carboxylate excretion after proline loads led to new observations on tissue levels of hydroxy-L-proline following proline administration and on the inhibition by L-proline of hydroxy-L-proline oxidase.

Alcohol Oxidoreductases↗
PubMed1975

Leukocyte-dependent antibody in sheep immunized with murine mastocytoma cells.

Sheep serum removed after hyperimmunization with murine P-815 mastocytoma cells was fractionated and two types of cytotoxic antibody were isolated. Complement-dependent antibody (CDA) was detected in the IgM and IgG1 fractions whereas "leukocyte" -dependent antibody (LDA) was found in the IgG1 and IgG2 fractions. Effector cells that mediated LDA cytotoxicity were isolated from sheep blood but not from sheep lymph, showing that recirculating lymphocytes do not have LDA effector function. Removal of adherent cells from blood leukocyte suspensions reduced antibody-mediated cytotoxicity, suggesting that LDA effector leukocytes may be a heterogenous population containing both adherent and nonadherent cells.

Animals↗
PubMed1975

Studies in gram staining.

Gram-negative bacteria stained with crystal violet are decolorized by 95% alcohol within 2 min, whereas Gram-positive bacteria require at least 3 min treatment. Aqueous solutions of safranin, neutral red, and fuschsin replace crystal violet from stained Gram-positive bacteria more quickly than alcohol alone, and alcoholic solutions of these counterstains are in most cases still more effective. Treatment of crystal violet-stained organisms with alcoholic safranin (0.25%) for 15 sec will distinguish Gram-positive bacteria (violet) from Gram-negative bacteria (pink). Alcohol containing very low concentrations of iodine generally decolorizes crystal violet-stained Gram-positive bacteria more quickly than alcohol alone. Increasing concentrations of iodine in alcohol reduce the rate of decolorization of stained bacteria, but stained Gram-negative bacteria are still readily decolorized. The addition of 0.1% iodine to alcohol increases the rate of extraction of crystal violet by alcohol from Gram-negative organisms, but delays extraction of dye from Gram-positive organisms, and this applies when counterstain is also present. A two-solution modification of Gram staining is described in which crystal violet-stained bacteria are treated with an alcoholic solution of safranin, fuchsin, and iodine.

Bacteria↗
PubMed1974

D-lysine catabolic pathway in Pseudomonas putida: interrelations with L-lysine catabolism.

The isolation of several mutant strains blocked in l-lysine degradation has permitted an assessment of the physiological significance of enzymatic reactions related to lysine metabolism in Pseudomonas putida. Additional studies with intact cells involved labeling of metabolic intermediates from radioactive l- or d-lysine, and patterns of enzyme induction in both wild-type and mutant strains. These studies lead to the conclusions that from l-lysine, the obligatory pathway is via delta-aminovaleramide, delta-aminovalerate, glutaric semialdehyde, and glutarate, and that no alternative pathways from l-lysine exist in our strain. A distinct pathway from d-lysine proceeds via Delta(1)-piperideine-2-carboxylate, l-pipecolate, and Delta(1)-piperideine-6-carboxylate (alpha-aminoadipic semialdehyde). The two pathways are independent in the sense that certain mutants, unable to grow on l-lysine, grow at wild-type rates of d-lysine, utilizing the same intermediates as the wild type, as inferred from labeling studies. This finding implies that lysine racemase in our strain, while detectable in cell extracts, is not physiologically functional in intact cells at a rate that would permit growth of mutants blocked in the l-lysine pathway. Pipecolate oxidase, a d-lysine-related enzyme, is induced by d-lysine and less efficiently by l-lysine. Aminooxyacetate virtually abolishes the inducing activity of l-lysine for this enzyme, suggesting that lysine racemase, although functionally inactive for growth purposes, may still have regulatory significance in permitting cross-induction of d-lysine-related enzymes by l-lysine, and vice versa. This finding suggests a mechanism in bacteria for maintaining regulatory patterns in pathways that may have lost their capacity to support growth. In addition, enzymatic studies are reported which implicate Delta(1)-piperideine-2-carboxylate reductase as an early step in the d-lysine pathway.

Acetates↗
PubMed1974

Formation and excretion of pyrrole-2-carboxylate in man.

A detailed investigation of the purification of pyrrole-2-carboxylate (PCA) from human and rat urine indicates that previously reported mean values overestimate the correct quantity of free PCA by a factor of approximately three for rat urine and approximately five for human urine. Although several criteria of purity were satisfied by a previous method, pyrrole-reactive impurities were still present in the final fractions. These impurities are separated from PCA by chromatography through an amino acid analyzer ion-exchange resin. With the corrected method, normal human values for endogenous urinary PCA in 16 individuals averaged 0.51 mumol/day, with a range of 0.20-1.3 mumol and a SD of 0.31 mumol. The probable source of human PCA is free hydroxy-L-proline, as inferred from the high value for PCA in the urine of a subject with hereditary hydroxyprolinemia, and from the threeto eightfold elevation in PCA excretion by two normal subjects after a large oral load of hydroxyl-L-proline. Subcutaneous administration of [2-(14)C]PCA to a single human subject indicated almost complete conversion of the exogenous compound to derivatives, which are largely excreted in the urine. Data are discussed suggesting that much or all of the PCA in human urine may be formed in urine from a labile precursor, presumably Delta(1)-pyrroline-4-hydroxy-2-carboxylate.

Adolescent↗