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Biomedical subjects

T Aoyagi

Publications and source records attributed to T Aoyagi.

At least 433 records · Page 24Linked to original sources
PubMed1978

Aminopeptidase activities on the surface of mammalian cells and their alterations associated with transformation.

Activities of various hydrolytic enzymes were determined in rat organ homogenates and on the surface of cells from various sources, i.e., tumor cell strains, primary cultured cells, normal cells, and their transformants. Alanine, leucine, methionine, phenylalanine, and glycyl-proline aminopeptidases and esterase showed relatively high activities in all these organs and cells. In the kidney homogenate the aminopeptidase A activity was higher in other organs; i.e., the aminopeptidase A activity was lower than that of aminopeptidase B. Normal cells derived from kidneys showed the kidney-type pattern of amino-peptidases A and B on the surface of cells, whereas tumor cells from various origins were of another organ type. When cultured mouse fibroblast strain C3H2K and rat fibroblast strain 3Y1 cells were transformed by SV40 or by a ts A mutant and maintained at permissive temperature, aminopeptidase A activity was drastically decreased, and the ratio of aminopeptidase A to aminopeptidase B was reduced to the levels of tumor cells. If the ts A mutant-transformed cells were grown at the restrictive temperature, the ratio approached that of normal cells. In normal cells, however, cultivation at high or low temperature did not cause any change of the activities.

Aminopeptidases↗
PubMed1977

Synthesis and structure-activity relationships of bestatin analogues, inhibitors of aminopeptidase B.

Stereoisomers and analogues of bestatin, [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl]-L-leucine, were synthesized and tested for aminopeptidase B and leucine aminopeptidase inhibiting activity. Among the eight stereoisomers, the 2S stereoisomers exhibited strong activity. In a series of compounds in which the L-leucine residue of bestatin was substituted with other amino acids, only the one containing isoleucine showed more activity than bestatin. Norleucine, norvaline, methionine, valine, serine, glutamine, phenylalanine, glutamic acid, proline, and lysine analogues gave, in that order, decreasing activity. Alkyl and phenyl sub stitution for the benzyl group of bestatin decreased the activity markedly. p-Methyl-, p-chloro-, and p-nitrobestatins showed greater activity than bestatin.

Aminopeptidases↗
PubMed1977

[Erythema elevatum diutinum, a variant of cutaneous vasculitis].

A 59 year-old man with erythema elevatum diutinum which we consider a variant of cutaneous vasculitis, is reported. An excellent therapeutic effect with Dapsone (DDS) was obtained in this case. Clinical and histopathological similarities among erythema elevatum diutinum, extracellular cholesterosis and granuloma annulare are discussed.

Dapsone↗
PubMed1977

Enzyme inhibitors in relation to cancer therapy.

In the last 11 years the authors have succeeded in isolating nearly 40 enzyme inhibitors of small molecular size from microbial origins. These inhibitors proved to be not only useful tools in analyses of homeostasis of living organisms but also promising agents for cancer chemotherapy. Leupeptin was originally isolated as an inhibitor against serine or thiol proteases such as trypsin, plasmin, papain and cathepsin B. And soon it was demonstrated that leupeptin suppressed chemical carcinogenesis in rats. Pepstatin has an extremely strong activity to inhibit pepsin and cathepsin D. It also inhibits ascites accumulation caused by neoplastic diseases. Bestatin is a specific inhibitor against aminopeptidase B and leucine aminopeptidase. The enzymes are located on the surface membrane in various kinds of cells including lymphocytes. Bestatin was shown to enhance not only blastogenesis of lymphocytes in vitro but also establishment of delayed-type hypersensitivity in vivo. Combined use of bestatin and other antitumor agents gave promising results in animal experiments. Studies on enzyme inhibitors have provided us a new approach to cancer chemotherapy.

Aminopeptidases↗
PubMed1976

Aminopeptidase activities on the surface of mammalian cells.

Activities of hydrolytic enzymes on the surface of monkey kidney, canine kidney, L. FM3A and various tumor cells were determined and compared with those in the cell homogenate. Although aminopeptidase (EC 3.4.11.-) activities were always detected on the surface membrane in mammalian cells, trypsin, chymotrypsin and elastase activities were not detected while slight glycosidase activity was detected in a suspension of cultured cells. The activities of alanine-, leucine-, methionine- and phenylalanine-aminopeptidases were rather high but aminopeptidase A, proline-, valine-, glycyl propline dipeptidyl-and glycyl propyl leucine-tripeptidyl-aminopeptidases showed relatively low activities. Aminopeptidase activity was also demonstrated in the isolated membrane fractions. The specific activities of enzymes in these membrane fractions were not significantly greater than in cell homogenate so it was concluded that these enzyme activities were rather loosely bound to the cell membrane. Further evidence for the localization of the aminopeptidase activities on the cell surface was obtained by using glass-bead-bound substrate and detecting the release of the terminal residues. When bestatin, a specific inhibitor against aminopeptidase B and leucine aminopeptidase, was included in the assay system for the enzyme activities on the cell surface, the enzymes were commonly inhibited in all types of cells.

Aminopeptidases↗