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Biomedical subjects

E Adams

Publications and source records attributed to E Adams.

At least 127 records · Page 7Linked to original sources
PubMed1978

3-Hydroxyproline content of normal urine.

Values for total 3-hydroxyproline and 4-hydroxyproline were obtained from 24-h urine specimens of 18 healthy human subjects of both sexes, whose ages ranged from the first to the sixth decade in age. Urinary 3-hydroxyproline levels, not earlier described to our knowledge, were determined by an isotope-dilution method requiring considerable purification and utilizing the amino acid analyzer for final measurement. 3-Hydroxyproline averaged 3% of the corresponding 4-hydroxyproline in individual urine samples. Like 4-hydroxyproline, 3-hydroxyproline excretion is increased in the second decade, and there is generally good correlation between the two values in individual urines. A hydroxyprolinemic subject excreting greatly elevated 4-hydroxyproline levels did not excrete excessive 3-hydroxyproline, consistent with independent catabolic pathways for the two compounds. 3-Hydroxyproline appears to be selectively excreted relative to 4-hydroxyproline when compared with the probable total body content of each amino acid. Possible explanations are: a more rapid turnover of basement membrane collagen than interstitial collagen or, alternatively, relatively greater resistance to the proteolytic cleavage of peptides containing 3-hydroxyproline.

Adolescent↗
PubMed1977

Glutarate semialdehyde dehydrogenase of Pseudomonas. Purification, properties, and relation to L-lysine catabolism.

The lysine-induced glutarate semialdehyde dehydrogenase of Pseudomonas was purified to electrophoretic homogeneity from a mutant strain lacking delta-aminovalerate transaminase. The properties of the enzyme, including molecular weight, amino acid composition, electrophoretic behavior, and kinetic features, distinguish it from similar dehydrogenases induced in the same cell strain by hydroxyproline or by glucarate. Enzyme induction patterns and the growth behavior of a mutant deficient in glutarate semialdehyde dehydrogenase clearly relate this enzyme to the so-called delta-aminovalerate pathway of L-lysine catabolism. Induction studies also indicate that delta-aminovalerate is a better inducer of the dehydrogenase than L-lysine. Cells of a mutant strain lacking delta-aminovalerate transaminase contained higher levels of the dehydrogenase, presumably as a result of the accumulation of delta-aminovalerate, making this mutant a useful preparative source of the enzyme. The marked reduction of lysine-inducible glutarate semialdehyde dehydrogenase in a mutant strain permitted assessment of the basal levels of hydroxyproline/glucarate-inducible ketoglutarate semialdehyde dehydrogenases not possible in wild type cells.

Aldehyde Oxidoreductases↗
PubMed1977

Prolyl hydroxylase of earthworms. Substrate specificity of an enzyme from the subcuticular epithelium.

A relatively crude enzyme preparation derived from the subcuticular epithelium of earthworms catalyzed the formation of 4-hydroxyproline from prolyl residues in unhydroxylated natural collagens and in several synthetic collagen-like polypeptides. The specificity of hydroxylation differed from that of all vertebrate polyl hydroxylases in that (Gly-Pro-Ala)n was a much better substrate than (Gly-Ala-Pro)n. In contrast, however, only the so-called Y position proline (Gly-X-Y) was hydroxylated in Gly-Pro-Pro sequences derived either from natural collagen or from synthetic polypeptides; specificity of hydroxylation for the latter sequence is identical with that of the vertebrate enzymes. Little or no formation of 3-hydroxyproline could be demonstrated in preparations of the enzyme active as a 4-hydroxylase. In contrast with an earlier report from another laboratory, using a crude extract of earthworm body wall, we were unable to demonstrate either significant 3-hydroxyproline formation or efficient 4-hydroxylation of X position prolyl residues in synthetic polypeptides with the internal sequence Gly-Pro-Pro.

Animals↗
PubMed1977

S-carboxymethylcysteine sulfone: instability to acid hydrolysis and unreactivity with N-terminal reagents.

An examination of the properties and reactivity of S-carboxymethylcysteine sulfone indicated that, unlike S-carboxymethylcysteine, the sulfone is not stable under acid hydrolysis conditions and decomposes to yield alanine. Unlike S-carboxymethylcysteine, the sulfone is resistant to N-derivatization by the dansyl reagent or by phenylisothiocyanate. Efforts were made to determine if spontaneous cyclization of the sulfone to the corresponding thiazane (lactam) accounts for lack of reactivity. These included i.r. spectroscopy, natural abundance 13C-n.m.r. spectroscopy and differential scanning calorimetry, but yielded equivocal results concerning the existence of the cyclic form in solution. Solubility behavior of the sulfone after lyophilization from strongly acid solutions was consistent with conversion of the open chain form to the cyclic form on addition of water.

Acids↗
PubMed1976

Antigens on melanoma cells detected by leukocyte dependent antibody assays of human melanoma antisera.

Antibody-dependent cell-mediated cytotoxic assays have been used to examine antigens on human melanoma cells obtained either directly from patients or from long-term melanoma cell lines. A panel of melanoma antisera was selected from human subjects which could be shown not to have significant reactivity to histocompatibility antigens. With these antisera extensive cross-reactions between melanoma cells were found. However, the cross-reactivity was incomplete and the pattern of reactivity was different for each antiserum tested. These results were not consistent with a common melanoma antigen on human melanoma cells but rather indicated heterogeneity of melanoma antigens and multiple antibody specificities in the sera tested. This appeared to be confirmed by extensive cross-absorption studies which indicated limited cross-reactivity of antigens on melanoma cells from either long-term or short-term cultures. Several changes in the antigenic profile of melanoma cells in vitro from both long-term and short-term cultures were documented which resulted from contamination of the melanoma cell lines with non-melanoma cells and fibroblasts. Melanoma antisera may therefore be useful to mintor changes in long-term cultures which would otherwise give spurious results in in vitro tests. These results appear to have considerable significance for understanding tumour/host relationships and for the establishment of rational immunotherapeutic procedures and diagnostic tests in melanoma.

Antibodies↗
PubMed1976

Antibody-dependent cell-mediated cytotoxicity against melanoma cells induced by plasmapheresis.

Patients with disseminated melanoma were treated by repeated plasmapheresis using a continuous-flow blood-cell separator, as part of a study to investigate methods of removing factors from tissue fluids which block cell-mediated immunity. Using 51Cr release cytotoxic assays, it was found that plasmapheresis resulted in removal of serum blocking activity. Post-plasmapheresis sera taken from several patients also increased cell-mediated cytotoxicity by induction of antibody-dependent cell-mediated killing. This effect may have resulted from removal or alteration of circulating immune complexes in the serum. It is not known whether cytotoxic activity induced in this way improves the patient's immune response against their tumours. However, the procedure is well tolerated and these preliminary in-vitro results indicate that this form of therapy could act as an adjunct to other forms of treatment of advanced melanoma.

Antigen-Antibody Complex↗
PubMed1976

Synthesis of peptides and derivatives of 3- and 4- hydroxyproline.

Synthesis and properties are reported for a number of peptides and related derivatives of 3-hydroxy-L-proline and 4-hydroxyl-L-proline. These were made for several different purposes, namely, sythesis of N-acetyl-O-tosyl-4-hydroxy-L-proline amide as a model for chemical reduction of peptide-bound hydroxyproline, synthesis of tripeptides with the sequence glycyl-4-hydroxy-L-hydroxy-L-prolyl-X, synthesis of the naturally occurring sequence, glycyl-3-hydroxy-L-prolyl-4-hydroxy-L-proline, and monomers for polymerization to yield the sequence -glycyl-prolyl-4-hydroxy-L-prolyl-.

Amino Acids↗
PubMed1975

Hydroxyproline-2-epimerase of Pseudomonas: active-site peptides.

Hydroxyproline-2-epimerase was treated with 14C-iodoacetate under conditions that produced almost complete inactivation of the enzyme and concomitant incorporation of almost one molar equivalent of iodoacetate. Both processes were prevented by saturating concentrations of substrate. From reaction mixtures in which both incorporation and inactivation were 85 to 90% complete, two radioactive tryptic peptides were isolated by paper chromatography-electrophoresis. The incorporated radioactivity was divided between the peptides in an approximately 2:1 ratio. Analysis of the isolated peptides suggested that they both contained 9 amino acids and had similar composition; one appeared to be a lysine, the second an arginine peptide. Attempts to sequence each peptide failed, apparently because of the conversion of the S-carboxymethylcysteine to S-carboxymethylcysteine sulfone, indicating that the cysteine residue was N-terminal in each peptide.

Amino Acid Isomerases↗
PubMed1975

Comparison of 51Cr release and microcytotoxicity assays against human melanoma cells.

Comparisons of the cytotoxic activity of mononuclear cells from venous blood of human subjects against human melanoma cell lines have been made by means of the 51Cr release assay (CRA) and the microcytotoxicity assay (MCA) of Takasugi and Klein. The relative effectiveness of the two assays in the detection of killing by various sub-populations of effector cells was studied after depletion of monocytes and separation of the blood monocluear cells by SRBC receptor and Fc receptor resetting techniques. Overall, the results showed good correlation. Most differences were the result of low values recorded with the CRA when effector cells were obtained from Hypaque-Ficoll--separated populations which had not been further fractionated. These differences were largely removed when monocytes were depleted by glass absorption and may reflect interference with the CRA by monocytes. No consistent differences were found between the assays in the detection of killing by subfractions enriched for T cells or B cells in this tumour system. The MCA appears to offer the advantage of greater sensitivity and possibly detection of a wider range of cytotoxic mechanisms but the CRA has a number of advantages of a technical nature which make it more applicable to routine assays in clinical studies.

Antigen-Antibody Reactions↗