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T Aoyagi

Publications and source records attributed to T Aoyagi.

At least 109 records · Page 6Linked to original sources
PubMed1997

Evaluation of skin permeability of drugs by newly prepared polymer membranes.

Four polymeric membranes were prepared consisting of various ratios of 2-hydroxyethyl-methacrylate/polydimethylsiloxane-methacrylate copolymer. These membranes had both lipophilic and hydrophilic domains in their copolymer networks like skin barrier. From permeation studies of the aqueous solutions or suspensions of various lipophilic and hydrophilic drugs using these membranes, a membrane having a similar drug permeability to hairless rat and human skins was selected. Permeation of indomethacin through the selected polymer membrane from simple ointment, gel and a marketed cream were then measured. About 10(2) times higher permeability was found in the polymer membrane than through excised hairless rat skin, but the rank order of the permeability through the polymer membrane among the formulations was the same through the skin membranes. These higher permeations of indomethacin were probably related to physical and chemical properties of pharmaceutical additives in the topical formulations. It is concluded that these synthetic polymer membranes may be utilized as an alternative tool to predict human or rat skin permeability of various (hydrophilic or lipophilic) drugs as well as to screen drug candidates for transdermal drug delivery.

Administration, Cutaneous↗
PubMed1997

Apoptosis to HL-60 by humulone.

Humulone, a bone resorption inhibitor isolated from hop extract, induced apoptosis in the premyocytic leukemia cell line HL-60 between 1 and 100 micrograms/ml. Our data suggested that there was a correlation between the apoptosis-inducing activity of humulone and its antioxidative activity.

Anti-Infective Agents↗
PubMed1996

Fas antigen expression on synovial cells was down-regulated by interleukin 1 beta.

Recent reports revealed that Fas antigen is functionally expressed on human synovial cells and apoptosis can be induced in these cells by anti-Fas antibody. We examined the effect of interleukin 1 beta (IL-1 beta) on Fas antigen-mediated apoptosis on human synovial cells in vitro. Using flowcytometric analysis, IL-1 beta inhibited Fas antigen expression on synovial cells in a dose-dependent fashion. No significant difference of Fas antigen gene expression between IL-1 beta-treated and untreated synovial cells was observed by RT-PCR analysis, suggesting that the inhibitory effect of Fas antigen expression by IL-1 beta is at posttranscriptional level. Apoptosis of synovial cells was easily induced by treatment of these cells with anti-Fas antibody. In contrast, pretreatment of synovial cells with IL-1 beta protected these cells against Fas antigen-mediated apoptosis. The expression of bcl-2 on synovial cells, known to interfere with the apoptotic process mediated by the Fas antigen, was not influenced by IL-1 beta. Our results suggest that IL-1 beta inhibits Fas antigen-mediated apoptosis of synovial cells and may perpetuate the hyperplasia of the synovium in patients with rheumatoid arthritis.

Apoptosis↗
PubMed1996

Inhibition of Fas antigen-mediated apoptosis of rheumatoid synovial cells in vitro by transforming growth factor beta 1.

OBJECTIVE: To investigate the mitogenic and anti-apoptotic effects of transforming growth factor beta 1 (TGF beta 1) on rheumatoid synovial cells in vitro. METHODS: Synovial cells were cultured with or without TGF beta 1. After incubation, the proliferative response of synovial cells and the expression of Fas antigen and bcl-2 on synovial cells were examined. Finally, Fas antigen-mediated apoptosis of synovial cells was investigated by the addition of anti-Fas antibody. RESULTS: TGF beta 1 enhanced the proliferation of synovial cells in a dose-dependent manner. In addition, Fas antigen expression on synovial cells was inhibited by the addition of TGF beta 1 with up-regulation of bcl-2 expression. The addition of anti-Fas antibody induced synovial cell apoptosis. However, stimulation of synovial cells with TGF beta 1 became markedly resistant to Fas antigen-mediated apoptosis. The results were not affected by the addition of a neutralizing antibody to platelet-derived growth factor type AA (PDGF-AA), which suggests that the effect of TGF beta 1 on synovial cells was promoted via PDGF-AA-independent mechanisms. CONCLUSION: Our results suggest that TGF beta 1 promotes synovial cell proliferation through its mitogenic effect on synovial cells and interference with the apoptotic process mediated by the Fas antigen, resulting in the perpetuation of the synovial hyperplasia in patients with rheumatoid arthritis.

Apoptosis↗
PubMed1996

A new type of major aminopeptidase in bovine brain.

A new type of major aminopeptidase was purified from bovine brain by ammonium sulfate fractionation and TMAE-fractogel (anion exchange), arginine-Sepharose 4B, Sephadex G-150, and Sephadex G-100 column chromatography. The purified enzyme showed a maximum activity at pH 7.2, and its molecular size was estimated to be 98,000 by gel filtration and 104,000 by SDS-PAGE with or without 2-mercaptoethanol. Further properties were activation by thiol reagents; inhibition by EDTA, puromycin, bestatin, amastatin, actinonin, leuhistin and probestin; and very low concentrations of Cu2+, Cd2+, Pb2+, Al3+, Fe3+, and Zn2+ inhibited activity. The enzyme hydrolyzed several amino acyl-7-amido-4-methylcoumalin derivatives (amino acid-MCA). The order of MCA-substrate specificity expressed as kcat/Km is Lys-MCA > Arg-MCA > Leu-MCA > Met-MCA > Phe-MCA > Tyr-MCA > Ala-MCA >> Gly-MCA, Pro-MCA, Ser-MCA, Asn-MCA. Immunoreactivity of the antibody against the purified aminopeptidase was observed in human brain and most rat tissues examined including brain, liver, kidney, lung, heart, and skeletal muscle at the same molecular size as in bovine brain aminopeptidase. Most of the Lys-, Leu-, Met-, and Phe-MCA degrading activity in crude bovine and human brain extracts was absorbed by the aminopeptidase IgG, suggesting that this aminopeptidase is a major enzyme, sharing at least Lys-, Leu-, Met-, and Phe-MCA degrading aminopeptidase activities in the brains.

Amino Acids↗
PubMed1996

Resistance to antituberculosis drugs in Japan.

SETTING: Five years after the last survey of drug-resistant tuberculosis in Japan, a serious new phenomenon has gradually begun to appear. A nationwide survey was conducted by the Tuberculosis Research Committee. OBJECTIVE: To determine resistance patterns to five anti-tuberculosis drugs and risk factors. DESIGN: Cultures were obtained from patients hospitalized at 38 hospitals in various districts of Japan throughout 6 months, from 1 June through 30 November in 1992. Drug susceptibility testing was carried out in the national reference laboratory. RESULTS AND CONCLUSIONS: Resistance to one or more drugs was found in 5.6% of new cases and 27.8% of recurrent cases (P < 0.001). About 88% of drug resistant isolates from the new cases were resistant to one drug, while 50.8% of the drug resistant isolates from the recurrent cases had resistance to two or more drugs (P < 0.001). Resistance rates to both isoniazid and rifampin in new cases was very low (only 0.14%). Primary drug resistance rates were higher in age groups less than 60 years old, compared to those of 60 years and over (P = 0.05). Compared with the rate in Japanese patients, foreign-born individuals had a higher resistance rate in the recurrent cases (P = 0.034). This survey indicated a similar trend in resistance rates to five antituberculosis drugs to those of the last survey in 1987.

Adolescent↗
PubMed1996

Inhibitory effect of clarithromycin on costimulatory molecule expression and cytokine production by synovial fibroblast-like cells.

This study was undertaken to investigate the immunomodulatory effect of clarithromycin against synovial fibroblast-like cells (synoviocytes). Synovial tissue obtained from rheumatoid arthritis (RA) or osteoarthritis (OA) patients was enzymatically digested to separate synoviocytes. The synoviocytes were cultured with or without cytokines in the presence of various concentrations of clarithromycin. The expression of costimulatory molecules was examined on the surface of the synoviocytes, using specific MoAbs and flow cytometry. The production of cytokines by synoviocytes was also measured using an immunoenzymatic assay. Finally, autologous T cells were stimulated by interferon-gamma (IFN-gamma)-treated synoviocytes in response to purified protein derivative (PPD). In some experiments, MoAbs specific for costimulatory molecules or clarithromycin were added and 3H-thymidine incorporation was counted. Intercellular adhesion molecule-1 (ICAM-1), LFA-3 and vascular cell adhesion molecule-1 (VCAM-1) were detected on the surface of both RA and OA synoviocytes. However, ICAM-2, B7-1 and B7-2 were not detected, and cytokines failed to induce these molecules. Both spontaneous and up-regulated expression of ICAM-1, LFA-3 and VCAM-1 by IFN-gamma, IL-1beta or 12-o-tetradecanoyl phorbol 13-acetate (TPA) were markedly suppressed by clarithromycin in a dose-dependent manner at concentrations between 0.1 and 10 microg/ml. The production of IL-1beta, IL-6, IL-8, granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) but not IL-1alpha and tumour necrosis factor-alpha (TNF-alpha) by synoviocytes was detected. Clarithromycin significantly suppressed the production of these cytokines, but did not enhance IL-10 production. Finally, autologous T cells were stimulated by IFN-gamma-treated synoviocytes in response to PPD. As clarithromycin suppressed HLA-DR and costimulatory molecule expression was enhanced by IFN-gamma, autologous T cell proliferation was markedly inhibited by clarithromycin. Clarithromycin has a considerable immunosuppressive effect on synoviocytes by inhibiting costimulatory molecule expression, cytokine production and antigen-specific T cell proliferation induced by synoviocytes.

Anti-Bacterial Agents↗
PubMed1996

TNF-alpha-mediated expression of membrane-type matrix metalloproteinase in rheumatoid synovial fibroblasts.

Degradation of the extracellular matrix plays an important role in rheumatoid articular destruction. Rheumatoid synovial fibroblasts secrete a large amount of matrix-degrading metalloproteinases (MMPs), which initiate tissue damage by proteolytic degradation of collagens and proteoglycans. Cytokines, such as interleukin-1 alpha, -1 beta or tumour necrosis factor (TNF)-alpha, are potent inducers of MMPs in rheumatoid synovial fibroblasts, MMPs are synthesized and secreted as latent pro-enzymes and their activation is achieved by proteolytic cleavage or the propeptide domain at the N-terminus of the molecule. Thus, the interaction of the pro-enzymes with specific activators determines the enzymatic activity in the extracellular space. In the present study, we identified a novel mechanism for the activation of pro-MMP-2, which can be achieved through the interaction of the inflammatory cytokine, TNF-alpha, with synovial fibroblasts. Although MMP-2 is constitutively secreted by synovial fibroblasts as a pro-enzyme, stimulation of fibroblasts by TNF-alpha-induced secretion of MMP-2 in an active form. In support of this result, TNF-alpha stimulation-induced membrane-type matrix metalloproteinase (MT-MMP), a newly identified MMP-2-specific activator on synovial fibroblasts. Cycloheximide analysis demonstrated that protein synthesis may be required for TNF-alpha-mediated MT-MMP expression on synovial fibroblasts. Our results suggest that TNF-alpha induces MMP-2 activation in part by up-regulating MT-MMP expression, thus representing a new mechanism for cytokine-mediated articular destruction in rheumatoid arthritis (RA).

Arthritis, Rheumatoid↗
PubMed1996

Gene expression of TGF-alpha, EGF and IL-6 in cultured renal tubular cells and renal cell carcinoma.

BACKGROUND: Renal cell carcinoma (RCC) is thought to arise from the renal tubular cells (RTC). Assuming that proliferating RTC imply a premalignant change of RTC into RCC, messenger RNA expressions of growth factors in cultured RTC were compared to both cultured and frozen noncultured RCC. METHODS: The expression of transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), EGF receptor (EGFR) and interleukin-6 (IL-6) were studied in surgically obtained RCC (n = 17), cultured RCC (n = 10), and autologous cultured RTC (n = 15). Quantitation of the PCR product was performed using a computer image analyzer which evaluated the intensity of each cytokine relative to beta-actin. RESULTS: TGF-alpha, EGFR and IL-6 were detected in most of the cultured RTC, and both cultured and noncultured RCC were also expressed at high levels. In contrast to a high positivity of TGF-alpha, EGF was not strongly positive in all specimens. CONCLUSIONS: Our results show that there is a predominant autocrine production of TGF-alpha in RCC and RTC, suggesting that TGF-alpha plays a distinct role in the proliferation of these cells. These studies also indicate that the mechanisms of proliferation and cytokine production of RCC and RTC are similar.

Carcinoma, Renal Cell↗
PubMed1996

Inhibition of tumor cell invasion and matrix degradation by aminopeptidase inhibitors.

We investigated the effects of several types of aminopeptidase inhibitors on tumor cell-associated aminopeptidase activity and invasion. The aminopeptidase expressed by the human metastatic HT1080 fibrosarcoma cells was effectively suppressed by actinonin A, bestatin, leuhistin and matlystatin A, which are capable of inhibiting the purified aminopeptidase N, but not by arphamenine B specific for aminopeptidase B. The aminopeptidase N inhibitors inhibited HT1080 cells from degrading the subendothelial matrix and from invading into Matrigel in parallel with their aminopeptidase inhibitory activities. Matlystatin A, with multiple inhibitory activity against both aminopeptidase N and matrix metalloproteinases (MMP), was the most effective inhibitor of invasion. However, leuhistin and bestatin, without MMP inhibitory activity, also exhibited significant inhibition of invasion. The results suggest that aminopeptidase N plays a crucial role in the degradation and invasion of extracellular matrices by fibrosarcoma cells and that aminopeptidase inhibitors may be useful for preventing the spread of malignant tumors.

Aminopeptidases↗
PubMed1996

[Screening, characterization and pharmaceutical and medical application of enzyme inhibitors from microbial origin with low-molecular-weight].

In living organisms a large number of enzymes are working in complicated networks to express various biological functions. In order to analyze such functions from various aspects, specific enzyme inhibitors are likely to become useful tools. They are also useful for the studies of reaction mechanisms and analysis of three-dimensional structures of enzymes. Moreover, they are of great value in elucidating disease processes and seem to have usefulness in treatment of various diseases. Searching for inhibitors in culture filtrate of microbes, we discovered many substances which specifically inhibit various enzymes such as endopeptidases, exopeptidases, glycosidases, lipases, an so forth. These inhibitors have low-molecular-weights and unique structures. We found significant activities of exopeptidases, alkaline phosphatases, esterases, and so forth, on surface membranes of various mammalian cells. Searching for specific inhibitors against these cell surface enzymes, we have discovered many interesting inhibitors. These inhibitors proved to bind to the cellular surface and to modify the functions of cells involved in immune responses. Thus the studies on these enzyme inhibitors may well afford important keys to understand various aspect of biological phenomena and diseases: inflammation, immune response, hypertension, hyperlipemia, diabetes, Alzheimer's disease, carcinogenesis, metastasis, viral infection, autoimmune diseases, and so forth. Because of their interesting pharmacological activities, some of the inhibitors are now under clinical evaluation for their uses as medical drugs. Enzyme inhibitors seems to propose a new promising field of science.

Animals↗
PubMed1996

Infectivity of Salmonella typhimurium isolated from the bengalee to chickens.

Due to its importance in public health, the infectivity of Salmonella Typhimurium (S. Typhimurium) originating from the bengalee, a variety of Lonchura striata, was examined in 3-day-old chickens. When chickens were inoculated orally with 10(4) CFU or 10(8) CFU of S. Typhimurium isolated from the bengalee and observed for 7 days, Salmonella was found in cloacal swabs from both groups. S. Typhimurium was also recovered from the liver, spleen and cecal of all the birds, and the counts in the cecal content were approximately 10(8) CFU per gram in each bird. Focal necrosis in the liver was observed in both groups. When chickens were inoculated with 10(4) CFU of S. Typhimurium originating from the bengalee or the chicken and observed for 21 days, more birds were positive for Salmonella in the former group than the latter group during the first week. S. Typhimurium was isolated from the liver, spleen and cecal content of both groups, and the counts of the cecal content were approximately 10(8) CFU per gram. Focal necrosis in the liver was noted in both groups. The results indicate that S. Typhimurium originating from the bengalee is infective and pathogenic to chickens, and the pathogenicity is almost similar to that of Salmonella derived from the chicken.

Animals↗
PubMed1996

Infectivity and persistence of Salmonella Typhimurium for zebra finches (Poephila guttata) isolated from the same species.

Salmonella Typhimurium (S. Typhimurium) originating from a naturally infected zebra finch (Poephila guttata), a common cage bird, was examined for the infectivity to the same species of the birds because of its importance to public health. Eight birds per group for each experiment were used. When zebra finches were inoculated orally with 10(2), 10(4) or 10(5) colony forming units (CFU) of S. Typhimurium and observed for 7 days, all the birds receiving 10(5) CFU of S. Typhimurium were positive for the Salmonella in the liver or the intestines and necrotic foci in the liver were observed in 7 birds. When zebra finches were inoculated with 10(5) CFU of S. Typhimurium and observed for 22 days, the S. Typhimurium was found in fecal samples throughout the experimental period and the maximum S. Typhimurium counts in feces were 4.0 x 10(3) CFU per gram. S. Typhimurium was recovered from the liver, spleen and intestines in 2 birds and necrotic foci in the liver were also observed in 6 birds. The results indicate that S. Typhimurium originating from the zebra finch is pathogenic to these birds and the persistence of the pathogen lasts at least for 22 days.

Animals↗
PubMed1996

Effects of ebelactone B, a lipase inhibitor, on intestinal fat absorption in the rat.

Ebelactones A and B, natural products from Streptomyces aburaviensis are potent inhibitors of pancreatic lipase. Lipase is the key enzyme required for the absorption of dietary triglycerides (TG). Ebelactone B inhibited, in a dose-dependent manner, the intestinal absorption of fat after fat-feeding in the rat. The most effective inhibition was observed when the inhibitor was administered at 60 min prior to fat-feeding. When ebelactone B (10 mg/kg) was administered, the serum levels of TG (58%) and cholesterol (36%) were decreased. Since ebelactone B effectively inhibitors absorption of dietary fat, if may provide a promising means for prophylaxis or therapeutics of hyperlipidemia and obesity.

Animals↗
PubMed1996

Piperastatin A, a new selective serine carboxypeptidase inhibitor produced by actinomycete. I. Taxonomy, production, isolation and biological activities.

Piperastatin A (structure, N-formyl-allo Ile-Thr-Leu-Val-Pip-Leu-Pip, Pip = hexahydropyridadine-3-carboxylic acid; molecular weight, 809), a new inhibitor of serine carboxypeptidase was discovered in the fermentation broth of Streptomyces lavendofoliae MJ908-WF13. It was purified by activated charcoal chromatography, YMC gel ODS-A chromatography and centrifugal partition chromatography (CPC) by monitoring its inhibitory activity against carboxypeptidase Y (CP-Y), and finally obtained as colourless needles. Piperastatin A is a competitive inhibitor of the enzyme with Ki = 52 +/- 6.2 nM. Piperastatin A is a highly specific inhibitor of the serine carboxypeptidases, CP-Y and platelet deamidase with little effect on related enzymes, has no antimicrobial activity and has low toxicity.

Carboxypeptidases↗
PubMed1996

Piperastatin A, a new selective serine carboxypeptidase inhibitor produced by actinomycete. II. Physico-chemical properties and structure determination.

Piperastatin A, a new inhibitor of serine carboxypeptidase, was discovered in the culture broth of Streptomyces lavendofoliae MJ908-WF13. The molecular formula of piperastatin A was established as C38H67N9C10 by HRFAB-MS and elemental analysis. The structure was determined to be N-formyl-allo Ile-Thr-Leu-Val-Pip-Leu-Pip (Pip = hexahydropyridadine-3-carboxylic acid) by various spectral analyses of piperastatin A and piperastatin A methylester.

Amino Acids↗