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Biomedical subjects

M Miwa

Publications and source records attributed to M Miwa.

At least 217 records · Page 12Linked to original sources
PubMed1987

Comparison of spectral and structural properties of three homologous dimeric proteins.

Spectroscopic and structural properties of three homologous dimeric inhibitors of microbial origin, Streptomyces subtilisin inhibitor, alkaline proteinase inhibitor and plasminostreptin, were discussed by comparing the hydropathy maps, the secondary structure contents obtained from the CD analysis, and the Chou and Fasman prediction. The major process of thermal denaturation of these proteins was the two-step transition. The denaturation temperature dropped in the order Streptomyces subtilisin inhibitor greater than alkaline proteinase inhibitor greater than plasminostreptin. Differences in the denaturation temperature were interpreted in terms of differences in the hydropathy scale of side-chains of the alpha 1-helix of these proteins. The lower CD change upon the complex formation of plasminostreptin with subtilisin BPN' than those with of Streptomyces subtilisin inhibitor and alkaline proteinase inhibitor was explained in terms of the large increase in hydrophilicity of the contact region of plasminostreptin with the enzyme.

Amino Acid Sequence↗
PubMed1987

Platelet-activating factor stimulation of rabbit platelets is blocked by serine protease inhibitor (chymotryptic protease inhibitor).

The serine protease inhibitors diethyl p-nitrophenyl phosphate and phenylmethylsulfonyl fluoride (chemical modifiers of serine residue) and N-acetyl-l-tryptophan ethyl ester (competitive inhibitor of chymotryptic protease) inhibited 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC; platelet-activating factor)-induced platelet aggregation and secretion. The inhibition was dependent on the preincubation time with the serine protease inhibitor and on the concentration of AGEPC and inhibitor. The IC50 value of diethyl-p-nitrophenyl phosphate, phenylmethylsulfonyl fluoride, and N-acetyl-l-tryptophan ethyl ester towards 5 X 10(-10) M AGEPC in serotonin release was 2.2 X 10(-4), 8.0 X 10(-4), and 5.0 X 10(-4) M, respectively. In experiments where platelets were incubated with these inhibitors and then washed with buffer, the inhibition of AGEPC stimulation was not observed. Prostaglandin H2 analog U46619 (10(-6) to 10(-5) M)- and thrombin (0.1 unit/ml)-induced platelet activation were also blocked by 1 mM diethyl p-nitrophenyl phosphate and 1 mM N-acetyl-l-tryptophan ethyl ester. The binding of AGEPC (1.5 X 10(-11) to 9.4 X 10(-10) M) to platelets and the platelet cyclic AMP level were not affected by diethyl p-nitrophenyl phosphate, phenylmethylsulfonyl fluoride, and N-acetyl-l-tryptophan ethyl ester. However, 1 mM diethyl p-nitrophenyl phosphate and 1 mM N-acetyl-l-tryptophan ethyl ester suppressed 10(-9) M AGEPC-induced breakdown of phosphatidylinositol 4,5-bisphosphate and formation of phosphatidic acid to 10-12 and 39-42%, 40-kDa protein phosphorylation to 4 and 30%, and arachidonic acid release to 17 and 28% of controls, respectively. On the other hand, 5 mM diethyl p-nitrophenyl phosphate did not inhibit diacylglycerol production and arachidonic acid release initiated by 2.5 mM deoxycholate treatment, suggesting that receptor-mediated phospholipase C and phospholipase A2 activation were inhibited by the serine protease inhibitor, but the deoxycholate (physicochemical stimulant)-initiated activation was not. AGEPC-induced 20-kDa protein phosphorylation and the inhibitory action of AGEPC on cyclic AMP accumulation were abolished in the presence of diethyl p-nitrophenyl phosphate and phenylmethylsulfonyl fluoride. However, a tryptic protease inhibitor, 1 mM p-aminobenzamidine and 1 mM benzoyl-l-arginine methyl ester, did not prevent the AGEPC-induced platelet secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Occurrence of an endogenous inhibitor of platelet-activating factor in rat liver.

Hepatocytes obtained from livers derived from fed rats perfused with a collagenase-containing mixture were found to contain significant levels of platelet-activating factor activity as isolated by Silica Gel G thin layer chromatography. However, when soybean trypsin inhibitor was included in the collagenase-containing perfusion medium for hepatocyte preparation, platelet-activating factor activity could not be detected on Silica Gel G chromatograms. Examination of the lipids extracted from freeze clamped perfused rat livers revealed low, but detectable, levels of platelet-activating factor. Further investigation of these observations indicated that a lipid-like inhibitor was present in freeze-clamped perfused livers as well as in hepatocytes isolated in the presence of soybean trypsin inhibitor. In each instance platelet-activating factor and this newly discovered inhibitor, which comigrated at the same RF value on Silica Gel G thin layer chromatography plates, could be separated by further chromatography on high performance thin layer plates. The present study shows that platelet-activating factor is present in unstimulated liver and that its detection is masked by an endogenous lipid-like inhibitor.

Animals↗
PubMed1987

Topographical study of stereo-related potentials.

In order to estimate objectively binocular vision and especially stereopsis, random dot stereograms generated by a personal computer were used. Brain activity during stereopsis was topographically studied by visually evoked potentials (VEPs). The potentials evoked by binocular viewing of patterns without disparity, e.g. correlogram, were very similar to the potentials evoked from patterns with disparity, i.e. stereogram, as many authors have already indicated. To derive the stereo-related potentials from the VEP elicited by stereograms, the potentials evoked by correlograms were subtracted from the potentials evoked by stereograms, and the differences of topographical distribution between normal and stereoblind subjects were investigated.

Adult↗
PubMed1987

Potentiation of the chemotherapeutic action of 5'-deoxy-5-fluorouridine in combination with guanosine and related compounds.

The effect of inosine, guanosine, and guanosine 5'-monophosphate (GMP) on the antitumor activity of 5'-deoxy-5-fluorouridine (5'-DFUR) was investigated using P388 leukemia and P815 mastocytoma. The antitumor activity of 5'-DFUR was markedly enhanced by coadministration of inosine or guanosine. The increase in lifespan (ILS) of mice treated with 5'-DFUR was augmented by the combination with guanosine or inosine in a dose-dependent fashion, and the maximum ILS was about 160% with the combination, while that in the case of 5'-DFUR alone was only 48% in the P388 leukemia system. The therapeutic ratio (dose at ILSmax/dose at ILS30) of the combination with guanosine or inosine was 333 and 136, respectively, whereas that of 5'-DFUR alone was 3.6. GMP also markedly potentiated the antitumor activity of 5'-DFUR in both P388 leukemia and P815 mastocytoma systems, just as it potentiated the activity of 5-fluorouracil in the latter system. The uric acid level in the serum was elevated after IP injection of guanosine or inosine but the value was much lower in the case of guanosine than in inosine.

Animals↗
PubMed1987

A case of CD4+/CD8- adult T-cell leukemia with good response to interferon-beta terminating as a CD4+/CD8+ adult T-cell lymphoma.

The leukemic cells of adult T-cell leukemia (ATL) usually express the helper/inducer associated antigen reactive with anti-CD4 antibodies but not with anti-CD8. We present a 63-yr-old woman with ATL characterized by circulating leukemic cells with CD4+/CD8- phenotype, hepatosplenomegaly with no lymphadenopathy, and the presence of proviral DNA of human T-cell leukemia virus I in the leukemic cells. She was successfully treated with interferon beta and the remission lasted for 12 months. She then relapsed in the lymph nodes with minimal peripheral blood involvement. The neoplastic cells of the lymph node now co-expressed CD4 and CD8 antigens indicating that the change in clinical manifestation was accompanied by a phenotypic change of the leukemic cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Nitrosation of amines by stimulated macrophages.

Rats and mice treated in vivo with Escherichia coli lipopolysaccharide (LPS) synthesize and excrete large quantities of nitrate. Murine peritoneal macrophages, elicited in vivo with thioglycolate and stimulated in vitro with LPS and/or gamma-interferon (IFN), produce copious amounts of nitrate and nitrite. We report here experiments showing N-nitrosamine formation by macrophages immunostimulated in vitro. Macrophage cell lines J774.1, PU5-1.8, WEHI-3 and RAW 264 and freshly isolated macrophages from C3H/He mice were used. Macrophages were cultured in Dulbecco's modified Eagle's medium (pH 7.5) supplemented with calf serum (10%). Supernatant NO2- and NO3- were measured. N-Nitrosamines were extracted with dichloromethane and the extracts analyzed by a gas chromatography--thermal energy analyzer. Cells (1.5 X 10(6)/ml) were incubated with LPS (10 micrograms/ml) and morpholine (15 mM) for 72 h at 37 degrees C. Under these conditions, all of the cell types listed above produced nitrite (40-70 microM) and N-nitrosomorpholine (NMOR; 114-940 nM). LPS was required for both processes, and this effect was enhanced by IFN. Nitrite (150 microM) incubated with morpholine in cell-free medium did not form NMOR nor did cells plus morpholine and NO2-. The rate of NMOR formation in the J774.1 cell line was highest in the middle incubation period (24-36 h) although [NO2-] was highest in the final incubation period (48-72 h). Thus, the cells do not catalyze nitrosamine formation per se, rather the amine traps out a reactive nitrosating species prior to the formation of NO2- and NO3-. These results suggest that immunostimulated macrophages may be capable of nitrosamine formation under physiological conditions.

Animals↗
PubMed1987

[Change in the electrical impedance caused by cornification of the epithelial cell layer of the vaginal mucosa in the rat].

The electrical impedance in the vagina (EIV) is significantly high in the proestrus stage compared with other stages of the estrous cycle in rats. Therefore, the EIV can be used to detect the optimum day for mating. The relation between the EIV and the conditions of the epithelial cell layer of vaginal mucosa were investigated. The EIV was at a high level (over 3,000 omega) in vaginas in the proestrus stage in either intact or excised vaginal mucus. But it decreased (under 3,000 omega) after the epithelium of the vaginal mucosa was removed. The EIV of ovariectomized rats was low, but increased after Estradiol administration. The cornification of the epithelial cell layer of the vaginal mucosa occurred concurrently with the high EIV in the proestrus stage and after Estradiol administration. This indicates that the cornification of the epithelial cell layer of the vaginal mucosa may cause the elevation of EIV in the proestrus stage, the optimum day for mating in the rats.

Animals↗
PubMed1987

Inherited hydrocephalus in Csk: Wistar-Imamichi rats; Hyd strain: a new disease model for hydrocephalus.

Hydrocephalic rats were found in a breeding colony of Csk: Wistar-Imamichi strain rats. In males, the hydrocephalus were serious and could be detected from 7 days after birth. Survival was 3-4 weeks. In females, the hydrocephalus was moderate, there was no abnormal external appearance, and the rats were able to mature. Ventricular dilatation was excessive in males but moderate in females. The total frequency of hydrocephalus was 34.3% in both males and females. Breeding data indicated that this disease is heritable and is single dominant and X-linked (symbol, Hyd). The female moderate hydrocephalics could be detected by progeny tests without examining brain sections. No evidence of developmental anomaly was observed in the ventricles. This hydrocephalus was classified as being of the communicating type, and this strain was named the Hyd strain as an animal model for human hydrocephalus.

Animals↗
PubMed1987

[A method for detecting the optimum day for mating during the 4-day estrous cycle in the rat; measuring the value of electrical impedance of the vagina].

A method for detecting the optimum day for mating in the rat was investigated. Cyclic changes of electrical impedance of vagina (EIV) were studied in the rats. EIV indicated high value (over 3,000 omega) only at proestrus, and it was lower (under 3,000 omega) at other stage of estrous cycle. These results apparently indicate that measuring the EIV made to distinguish proestrus from other phases of estrous cycle. The female caged with male showed high copulation rate (88 approximately 96%) when her EIV had been over 3,000 omega.

Animals↗
PubMed1987

[A recessive mutant causing testicular/ovarian teratoma in rats (Tera strain)].

A hereditary testicular/ovarian teratoma strain (Tera) of rats was developed from the Csk: Wistar-Imamichi strain. As the teratoma consisted of tridermic tissues such as bone, epithelium and neural tissue, it was diagnosed as triphyllomatous teratoma. The frequency of the teratoma was about 25% in either sex, with no sexual difference. Accordingly, the heredity of the teratoma appeared to be an autosomal single recessive trait (symbol, tera).

Animals↗
PubMed1987

A unique T-cell line derived from an HTLV-1-negative adult T-cell leukemia patient.

A unique T-cell line, designated ATL-5T, was established from lymphoma cells in pericardial effusion of an adult T-cell leukemia (ATL) patient not carrying HTLV-1 provirus. The cell line is OKT4 and/or Leu3a+ and OKT8 and/or Leu2a+, but interleukin 2 receptor (IL2R)- and HTLV-1 provirus genome negative, and has cytogenetically abnormal karyotypes. The cell line contains rearranged T-cell receptor beta-chain gene, which was identical in rearrangement pattern to the T-cell receptor beta-chain gene in primary cells. These results suggest that factors other than HTLV-1 may sometimes be associated with HTLV-1-negative ATL. The ATL-5T cell line we describe here is unique, and should contribute to further elucidation of the mechanisms involved in the pathogenesis of HTLV-1-negative ATL and HTLV-1-positive ATL.

DNA, Viral↗
PubMed1987

Aberrant expression of ganglioside and asialoglycosphingolipid antigens in adult T-cell leukemia cells.

Gangliosides (GM3, GD3, GM2, gangliotetraose-series gangliosides) and their asialo derivatives of several adult T-cell leukemia (ATL) cell lines (ATL-1K, ATL-3I, ATL-5S, and MT-2 cells) and the lymphocytes from a patient with ATL were quantified by highly sensitive enzyme-immunostaining on silica gel thin layer chromatograms using specific antiglycolipid antibodies. GM2 and GD3 gangliosides and asialo GM1 (GA1) newly appeared in all cultured ATL cells and the lymphocytes from patients with ATL but not in normal human T-lymphocyte-rich fraction. Gangliotetraose-series gangliosides, GM1a, GD1a and GD1b, were also found in cultured ATL cells, but were not detected in normal human lymphocytes or the lymphocytes of a patient with ATL. Quantitative immunostaining analysis of GM2, GD3 gangliosides and GA1 in T-cell lines from non ATL leukemia (Molt-3, CEM and Jurkat) revealed GM2 gangliosides in all the T-cells from non ATL tested and GA1 in Jurkat cells, but no GD3 ganglioside was found in the non ATL leukemia cells tested. The above results indicate that ganglioside GD3 may be a T-cell glycosphingolipid antigen associated with ATL, and ganglioside GM2 and GA1 may be useful as surface markers related with ATL, as well as T-cell lymphoma. The contents of GA1, GM3, GD3, GM2 and gangliotetraose-series gangliosides in ATL cells were all different, even though all the cells used have a common antigen reactive with monoclonal OKT-4 antibody, indicating that there are several subsets of human inducer/helper T-cells, which possess different metabolism and expression of gangliosides.

Antigens, Neoplasm↗
PubMed1987

[Conversion of 5'-deoxy-5-fluorouridine to 5-FU by pyrimidine nucleoside phosphorylases in normal and tumor tissues from rodents bearing tumors and cancer patients].

Enzyme levels of pyrimidine nucleoside phosphorylase, which is an essential enzyme for the phosphorolysis of 5'-deoxy-5-fluorouridine (5'-DFUR) to 5-fluorouracil (5-FU), in normal and tumor tissues were investigated. In all mouse strains tested, the enzyme level was found to be higher in the small intestine and stomach than other tissues, while in rats a higher level of the enzyme in the lung was also observed additionally. The enzyme levels of tumor tissues varied in tumor cell lines transplanted. P388 leukemia, Ehrlich ascites carcinoma, sarcoma 180, colon 26 carcinoma, and Lewis lung carcinoma cells contained high levels of the enzyme and the mice bearing these tumors responded well to the therapy with 5'-DFUR than its active metabolite 5-FU, while 5'-DFUR did not show clear advantage over 5-FU against L1210 or LSTRA leukemia, in which the enzyme levels were low. These results indicate that there is some correlation between the enzyme level and antitumor efficacy of 5'-DFUR. In human specimens, the enzyme levels were 2-6 times higher in tumors than those of the corresponding normal tissues and those adjacent to the tumors. These results predict that 5'-DFUR seemed to be converted efficiently to 5-FU also in human tumors.

Animals↗
PubMed1987

[Antitumor effects of 5'-deoxy-5-fluorouridine (5'-DFUR) against various murine tumors in combination with recombinant interferon alpha or cytostatics].

Antitumor effects of oral fluorinated pyrimidines including 5'-DFUR and their combination with recombinant interferon (rIFN) alpha A/D (Bgl) or cytostatics were investigated using various tumor models in mice. 5'-DFUR was more effective against Colon 26 than tegafur and 5-FU as a single agent, and their therapeutic indices were 14.7, 2.3 and 1.2, respectively. In combination with various cytostatics, 5'-DFUR as well as 5-FU and tegafur showed better efficacy against mouse Colon 26, Meth A fibrosarcoma and A755 adenocarcinoma than any other single agents. Combination therapy with 5'-DFUR and rIFN-alpha A/D also showed better efficacy against all seven murine tumors tested than their single therapy. In these combination therapies, increased toxicities measured by a body weight change and the incidence of toxic death were also observed to some extent. Among combinations with fluorinated pyrimidines, those with 5'-DFUR showed the toxicities at a lesser degree than those with 5-FU or tegafur. These results indicate that 5'-DFUR would be useful for the multiple combination chemotherapy like 5-FU and tegafur.

Animals↗