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Biomedical subjects

T Aoyagi

Publications and source records attributed to T Aoyagi.

At least 343 records · Page 19Linked to original sources
PubMed1984

Effects of adenosine and 2'-deoxyadenosine on epidermal keratinocyte proliferation: its relation to cyclic AMP formation.

Although it has been reported that adenosine has an inhibitory effect on keratinocyte proliferation at both G2 and S phases of the cell cycle, its relation to cyclic AMP formation through the adenylate cyclase system has been less well characterized. In order to determine the precise mechanism of the adenosine effect, another physiologic adenine nucleoside, 2'-deoxyadenosine was employed. 2'-Deoxyadenosine was shown to be remarkably different from adenosine in its ability to stimulate the epidermal adenylate cyclase; whereas adenosine markedly increased cyclic AMP levels of pig epidermis, deoxyadenosine had a much weaker effect on the cyclic AMP levels of the skin. Using several parameters of cell proliferation, comparison was made between the effects of these two compounds. Pig keratinocyte explant culture system was employed for the measurement of outgrowth and mitosis. Mitosis was determined after 72-h incubation (to monitor the overall cell proliferation inhibition) and 4-h incubation (to monitor G2 phase inhibition) with the chemicals. Pig skin keratome slice system was employed for [3H]thymidine uptake measurement. Both adenosine and deoxyadenosine were shown to have marked inhibitory effects on keratinocyte out-growth, [3H]thymidine uptake, and keratinocyte mitosis. The effects of deoxyadenosine on outgrowth and [3H]thymidine uptake were greater than that of adenosine. The inhibitory effect of adenosine and deoxyadenosine on mitosis were about the same in both 4-h and 72-h incubation systems. Thus deoxyadenosine, which is a much weaker stimulator of epidermal adenylate cyclase, was also shown to be as potent an inhibitor of keratinocyte proliferation as adenosine. These results further substantiate the view that cyclic AMP elevating agents (such as adenosine and deoxyadenosine) might not necessarily reveal their inhibitory effects on keratinocyte proliferation through their effects of cyclic AMP formation.

Adenosine↗
PubMed1984

Ornithine decarboxylase activity is inhibited by epidermal polyamine-dependent protein kinase-mediated phosphorylation.

Polyamine-dependent protein kinase in cytosol of pig epidermal cells was extracted. The fraction containing this enzyme exhibited multiple polypeptide bands on polyacrylamide gel electrophoresis, including 4 major polypeptide bands and several minor polypeptide bands. A 80 kilodalton (KD) polypeptide, one of the minor polypeptide bands, was phosphorylated by polyamine-dependent protein kinase. Authentic ornithine decarboxylase (ODC) exogenously added was separated into 2 subunits (80 KD and 40 KD) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a 80 KD polypeptide was also phosphorylated by polyamine-dependent protein kinase. A 80 KD polypeptide of ODC comigrated with the polypeptide of cytosol which was phosphorylated by polyamine-dependent protein kinase. Kinetic study revealed that the ODC activity decreased as ODC was phosphorylated. Therefore, ODC activity was inhibited by epidermal polyamine-dependent protein kinase-mediated phosphorylation. The overall results indicate that the rapid turnover of ODC might be regulated by a phosphorylation-dephosphorylation reaction without new protein synthesis.

Animals↗
PubMed1984

Difference in enzyme networks between mouse and hamster models of muscular dystrophy.

The present study was undertaken to compare the peculiarity of enzymatic changes in dystrophic hamsters and mice. Various enzymatic activities in muscle, bone, heart, spleen, liver and kidney were measured. The enzymes tested include 7 aminopeptidases, 5 endopeptidases, 3 glycosidases, creatine kinase, phosphatase and esterase. In dystrophic mice, the enzymatic changes were chiefly confined to muscle and bone. In dystrophic hamsters, on the other hand, extensive and pronounced changes in enzymatic activities were seen not only in skeletal muscle but also in bone, heart muscle, spleen, liver and kidney. Furthermore, resemblance of pattern of enzymatic changes was seen among several organs including skeletal muscle, heart muscle, bone and spleen in the hamster model. Comparing the enzymatic changes in these two models, dystrophic mouse may be regarded as more specific a model for musculoskeletal diseases. Dystrophic hamster may be related more to multiorgan diseases possibly associated with immunological or other systemic diseases. These models may represent two different disease categories, respectively.

Aminopeptidases↗
PubMed1984

Similar effects of various low-molecular-weight enzyme inhibitors on enzyme networks in dystrophic mice.

We compared the therapeutic effects of various low-molecular-weight enzyme inhibitors on dystrophic mice. Leupeptin, bestatin, forphenicinol and forphenicine significantly affected the enzymatic activities in the dystrophic muscles. The pattern of enzymatic changes in the muscles of forelimb and hindlimb caused by these inhibitors were similar in spite of the variety of their inhibitory spectra in vitro. However, comparing the pattern of enzymatic changes in spleen, forphenicinol differed from the other inhibitors tested. This may be related to the peculiar effects of this inhibitor on immunologically responsive cells.

Alkaline Phosphatase↗
PubMed1984

Biosynthetic studies of arphamenines A and B.

The biosynthetic pathways of arphamenines A and B were studied. Arphamenine A was derived from acetic acid, L-arginine and L-phenylalanine, and arphamenine B from acetic acid, L-arginine and L-tyrosine.

Acetates↗
PubMed1984

The structure of histargin.

The structure of histargin, an inhibitor of carboxypeptidase B, produced by Streptomyces roseoviridis MF118-A5 strain, has been defined as N-[(S)-1-carboxy-4-guanidinobutyl]-N'-[(S)-1-carboxy-2-(imidazol-4 -yl) ethyl]ethylenediamine, by spectral analysis and chemical synthesis.

Amino Acids↗
PubMed1984

Decreased serum levels of various hydrolytic enzymes in patients with rheumatoid arthritis.

It is known that the serum level of glycylproline aminopeptidase (Gly-Pro-AP) is decreased in the patients with rheumatoid arthritis. In the present study, the serum levels of various hydrolytic enzymes were tested in such patients. In comparison to the controls, many enzymes, including Ala-AP, Ser-AP, Phe-AP, Gly-Pro-AP, Gly-Pro-Leu-AP, dipeptidyl carboxypeptidase (angiotensin converting enzyme), and esterase, showed significantly decreased activities in the patients' sera. Only the activity of Trp-AP was significantly increased. Of these enzymatic activities in serum, several ones including those of Gly-Pro-AP, Ala-AP, Phe-AP, trypsin-like enzyme, and esterase, were significantly correlated with the severity of the disease. Although a part of these findings are compatible with previous observations, they suggest rather more extensive disorders of peptide metabolism in this immunological disease.

Acetylcholinesterase↗
PubMed1984

Different tendencies of changes in hydrolytic enzyme activities in sera from prostatic cancer patients with or without bone metastasis.

Serum levels of various hydrolytic enzymes in prostatic cancer patients with or without bone metastasis were compared with those in patients with prostatic hypertrophy and in the control subjects. The enzymes tested included 11 aminopeptidases, 2 endopeptidases, dipeptidyl carboxypeptidase, esterase, acetyl cholinesterase, and RNase. Although most of the enzymatic levels tended to be decreased in the cancer patients without bone metastasis, they tended to be increased in those with metastasis as well as in the patients with prostatic hypertrophy. Thus, bone metastasis is an important factor affecting the serum levels of hydrolytic enzymes in cancer patients. Of the enzymes tested, RNase was unique in that its serum levels were significantly increased regardless of the existence of bone metastasis. This enzyme may become a marker of malignancy.

Aged↗
PubMed1984

Oscillation of enzyme networks in spleen triggered by an immunopotentiator, bestatin.

In order to understand the effects of an immunomodulator in vivo, we performed time series analysis on mice given an aminopeptidase inhibitor, bestatin. This agent, which is known to be an immunopotentiator, caused peculiar oscillation of the activities of various hydrolytic enzymes in spleen. Autocorrelation curves obtained from serial data of each enzymatic activity revealed that sine curve-type oscillations are brought about in enzyme networks by this inhibitor. Judging from the pattern of the variations of enzymatic activities, it seems that metabolic homeostasis is strongly affected by this agent. The inhibitor probably initiated the homeostatic movements directly and secondarily caused extensive changes in the enzyme networks in vivo. This effect of bestatin may be useful in altering the pathological homeostasis (such as the one in autoimmune diseases) by affecting the dynamic equilibrium among the various components in the immunological system.

Adjuvants, Immunologic↗
PubMed1984

Abnormalities of splenic enzyme networks in nude mice.

The activities of various hydrolytic enzymes in splenic tissues of nude mice were compared with those of their controls of the same age. Since all of the enzymatic activities varied with age in both nude mice and in the controls, the difference between the two groups were difficult to define clearly. Principal component analysis enabled us to clearly categorize the enzymatic variations of both groups into two main components. One was related to the maturation process of the animals and the other to the pathological processes in the nude mice. The enzymes related especially to the latter component were formyl-methionine aminopeptidase (fMet-AP), mannosidase, and beta-N-acetyl-D-glucosaminidase (GlcNAc-ase). These enzymes may represent the abnormality of the surface of lymphocytes in the nude mice.

Aging↗