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Biomedical subjects

M Ohbayashi

Publications and source records attributed to M Ohbayashi.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effectiveness of Carolina rinse solution after cold ischemic storage of rat livers: biochemical and histological analysis using perfusion model.

Using a rat liver perfusion model, the effectiveness of Carolina rinse solution was assessed for the prevention of reperfusion injury after 48 h of cold storage in UW solution. Transaminase levels (GOT, GPT and LDH) of the perfusate were significantly higher in the Ringer group (17 +/- 8, 17 +/- 9 and 191 +/- 97 IU/l, respectively) than in the Carolina group (6 +/- 4, 5 +/- 4 and 21 +/- 20 IU/l) (p < 0.05). The levels of oxygen consumption were also higher in the Carolina group (233 +/- 54 mm Hg) than in the Ringer group (164 +/- 58 mm Hg) (p < 0.05). Histological examination showed severe parenchymal cell damage in the Ringer group, whereas the damage was slight in the Carolina group. Two newly developed monoclonal antibodies, REC16-11 and REC4-1, which specifically react with rat endothelial cells, were used for immunohistochemical studies of the livers. The endothelial cells of central vein and sinusoids were more severely damaged in the Ringer group than in the Carolina group. The present study suggests that Carolina rinse solution is useful for prevention of liver damage from reperfusion injury after cold storage of the graft for organ transplantation.

Animals↗
PubMed1994

Kinetics of intestinal intraepithelial lymphocytes during acute graft-versus-host disease in mice.

We examined the kinetics of intestinal intraepithelial lymphocytes (IEL) and the incidence of apoptosis at villus or crypt sites during the development of non-irradiated acute graft-versus-host disease (GVHD). The first IEL to increase were host-origin on day 3 and the donor-derived IEL appeared first on day 12 after GVHD induction. Unique CD3+CD4+CD8 alpha/alpha+ IEL were significantly increased on day 6 and an appreciable number of IEL bearing T cell receptor V beta capable of recognizing self-superantigen were detected on day 9. The sudden appearance of apoptosis and reduction of mitotic activity occurred on day 12, accompanied by a dramatic decrease of CD3+CD4-CD8 alpha/alpha+ IEL of host origin. CD8 alpha/alpha+ IEL of host origin, which expand and then decrease by apoptosis at the early stage of acute GVHD, may be associated with pathogenesis of the enteropathy occurring during acute GVHD.

Animals↗
PubMed1994

Infectivities of four isolates of Taenia taeniaeformis to various rodents.

Taenia taeniaeformis were isolated from Norway rats captured at Sapporo (SRN isolate) and Kuala Lumpur, Malaysia (KRN) and from Bedford's gray red-backed voles at Toubetsu (TCR) and Abuta (ACR). SRN, KRN and TCR isolates showed similar degree of infectivity to various rodents in which cysticerci with hooks were obtained in laboratory rats, white tuberous lesions in mice and no cysts or lesions in Mongolian gerbils and voles. Contrary to this, inoculation with ACR isolate eggs resulted in strobilocerci formation in the liver of voles, but no cysts were observed in rats, mice or gerbils. This host specificity of ACR isolate to voles suggests that it might be a new species of Taenia.

Animals↗
PubMed1994

Interferon-beta endogenously produced by intratumoral injection of cationic liposome-encapsulated gene: cytocidal effect on glioma transplanted into nude mouse brain.

The cytocidal effect of endogenously produced human interferon-beta was tested on glioma transplanted into the brain of nude mice by intracranial injection of a cell suspension of human glioma cell line U251-SP. When plasmid pSV2IFN-beta, bearing the human interferon-beta gene, was encapsulated into cationic multilamellar liposomes composed of N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride, dilauroyl phosphatidylcholine, and dioleoyl phosphatidylethanolamine in a molar ratio of 1:2:2 and injected intratumorally, human interferon-beta was produced in the tumor. The tumor completely disappeared if the injection was done shortly after the transplantation. Even when the tumor did not disappear, survival of the tumor-bearing nude mice was markedly prolonged. In control experiments made with normal brain having no glioma, interferon-beta was not detected.

Animals↗
PubMed1993

Immunohistochemical and functional studies on rat high endothelial venules using monoclonal antibodies.

The distribution of high endothelial venules (HEVs) in various rat organs has been investigated immunohistochemically using two monoclonal antibodies (MoAbs), REC16-11 and REC4-1. The staining patterns observed with REC16-11 and REC4-1 were compared with those obtained with the MoAb anti-rat ICAM-1, which is a cell adhesion molecule in HEVs. REC16-11 reacted not only with HEVs but also with all vascular endothelial cells (ECs) in the tissues examined. Electronmicroscopy showed that REC16-11 and REC4-1 reacted with the cell surface antigens of ECs and immunoblot analysis of rat splenic stromal preparations showed that REC4-1 stained 42 kd and 60 kd bands. REC4-1 inhibited the binding of lymphocyte to HEVs in the mucosa-associated lymphoid tissues (MALT), but had no effects on lymphocyte binding to HEVs in peripheral (non-mucosal) lymph nodes. These findings suggested that the MoAb REC4-1 recognized the associated antigen of the lymphocyte-HEV recognition system in MALT.

Animals↗
PubMed1993

White pulp reconstitution after human bone marrow transplantation.

To reveal the reconstitution process of the white pulp after bone marrow transplantation (BMT), spleens of 24 marrow recipients whose survival times ranged from 34 to 303 days after BMT, were analyzed at the histopathological and immunohistochemical level. Up to 3 months after BMT, the white pulp was atrophic and consisted mainly of T cells forming periarteriolar lymphatic sheaths (PALS). Approximately 100 days after BMT, B cells aggregated in some of the white pulp, forming primary follicles, whereas marginal zones could not be detected. Beyond 4 months after BMT, the PALS, the lymphoid follicle, and the marginal zone of the white pulp could be seen in most of the recipients' spleens. However, the recovery of the marginal zone was poor up to 10 months after BMT. Thus, the white pulp was reconstituted sequentially, beginning in the PALS, followed by reconstitution in lymphoid follicles, and finally in the marginal zone. The development of the PALS corresponded well with the appearance of interdigitating dendritic cell, as did the development of lymphoid follicles with the appearance of follicular dendritic cell. The sequential reconstitution of the white pulp demonstrated in this study provides the morphological basis for the functional immune recovery of marrow recipients. In particular, the delay of the marginal zone reconstitution seems to be responsible for the functional asplenia of long-term survivors.

Adolescent↗
PubMed1992

The ret oncogene can induce melanogenesis and melanocyte development in Wv/Wv mice.

We recently reported the establishment of transgenic mouse lines carrying the mouse metallothionein/ret fusion gene in which severe melanosis and melanocytic tumors developed. In the present study, we demonstrate that a significant number of pigmented hairs developed in Wv/Wv mice crossed to one of the transgenic mouse lines. The pigmented hair of Wv/Wv mice carrying the ret oncogene did not lose color during aging and reappeared after shaving, indicating that the melanocytes in the hair follicle function. The melanocytic tumors also developed in these mice, although the incidence was lower than that in the wild transgenic mice. Furthermore, the neutral tube culture of mouse embryos indicated that neural crest cells of the transgenic mice gave rise to a cell population that autonomously produced melanin even in the absence of melanocyte stimulating hormone. These results strongly suggested that the introduced ret oncogene could compensate for the defect of c-kit in Wv mice during both embryogenesis and postnatal life and induce a high level of melanin synthesis in the process of melanocyte development.

Aging↗
PubMed1992

Use of enzyme-linked immunosorbent assays with chimeric fusion proteins to titrate antibodies against Epstein-Barr virus nuclear antigen 1.

Two new enzyme-linked immunosorbent assays (ELISAs) with chimeric fusion polypeptides for the detection of human antibodies specific to Epstein-Barr virus nuclear antigen 1 (EBNA-1) are described. One is an indirect ELISA with affinity-purified beta-galactosidase-EBNA-1 fusion protein as the antigen. The other is a "sandwich" assay based on the use of anti-beta-galactosidase antibody to capture beta-galactosidase-EBNA-1 fusion proteins in bacterial extracts. A good correlation was shown between antibody titers determined by the ELISA with the EBNA-1 fusion proteins and those determined by a conventional anticomplement immunofluorescence test which is being widely performed with Raji cells for the purpose of research and clinical diagnosis. The advantage of the ELISAs for seroepidemiologic studies on Epstein-Barr virus was demonstrated by sensitive detection of marginal immunoglobulin G antibody to the EBNA-1 domain in serum samples from patients with infectious mononucleosis.

Antibodies, Viral↗
PubMed1992

Establishment and characterization of a malignant melanocytic tumor cell line expressing the ret oncogene.

We established a cell line (designated Mel-ret) from a melanocytic tumor developed in a metallothionein/ret transgenic mouse. Unlike primary melanocytic tumors, which did not show malignant features, when the Mel-ret cells were transplanted into nude mice they invaded into surrounding tissues and had metastatic ability. Although the Ret proteins were expressed at similar levels in the cell line and the primary tumors, the level of tyrosine phosphorylation in the Mel-ret cells was much higher than that in the primary tumors. In particular, an 85-kDa tyrosine-phosphorylated band was specifically detected in the Mel-ret cells. These results suggest that the increase in tyrosine phosphorylation may be responsible for malignant transformation of the Mel-ret cells. Immunofluorescence and cell fractionation studies showed that the Ret proteins and most of tyrosine-phosphorylated proteins in the Mel-ret cells localized in the membrane fraction. No activation of phosphatidyl-inositol-3 kinase (PI-3 kinase), a target protein for several tyrosine kinases, was detected in the Mel-ret cells.

Animals↗
PubMed1991

Aberrant melanogenesis and melanocytic tumour development in transgenic mice that carry a metallothionein/ret fusion gene.

We generated four independent transgenic mouse lines that showed severe melanosis of the whole body by introducing the ret oncogene fused to the mouse metallothionein (MT)-I promoter-enhancer (MT/ret). Whereas melanogenesis was accelerated without distinct proliferative disorders in one line, melanocytic tumours frequently developed in the other three lines. Northern hybridization and in situ hybridization analyses showed that tumour cells and non-tumorous melanin-producing cells expressed the transgene at high levels. The aberrant melanogenesis and tumour development were influenced by genetic and environmental factors. Furthermore, crossbreeding experiments between the transgenic mice and Wv mice suggested that the ret gene product can partially compensate for the defect of melanocyte development in Wv mice. This is a novel mammalian model in which melanosis and melanocytic tumours develop stepwise, triggered by a single transgene.

Animals↗
PubMed1991

Maduropeptin, a complex of new macromolecular antitumor antibiotics.

Maduropeptin, a complex of new macromolecular antitumor antibiotics, is a metabolite of Actinomadura madurae H710-49. The active components maduropeptins A1, A2 and B are acidic chromopeptides with MW of around 22,500 and composed of 14 types of amino acids and an unstable chromophore. The antibiotics are active in vitro against Gram-positive bacteria and highly cytotoxic to tumor cells. They produced significant prolongation of survival time of mice implanted with P388 leukemia and B16 melanoma.

Actinomyces↗
PubMed1991

Phenotypic changes in hepatic mast cells accumulating around the metacestodes of Taenia taeniaeformis in rats.

Staining properties, kinetics and degranulation of the hepatic mast cells (HMC) accumulating around the metacestodes of Taenia taeniaeformis in the liver of rats were studied. Two different types of HMC, designated as Type I and Type II, could be classified according to histochemical properties and response to compound 48/80. Type I cells resembled mucosal mast cells (MMC), whereas Type II did not. HMC, mostly Type I, were observed from day 14 postinfection (PI), while Type II were seen only from day 28 PI. On day 28 PI, Type II represented a transitional staining pattern between MMC and connective tissue mast cells (CTMC). The ratio of Type II to Type I increased gradually with the course of infection and was about 1 to 1 on day 70 PI. At this time, most of the HMC that constituted Type II as well as CTMC could be stained with berberine sulfate. While the phenotypic change of HMC to CTMC was found in the middle and inner capsular layers, most of the HMC in the outer capsular layer maintained the phenotype of MMC. The present results suggest that hepatic mast cells increased as the MMC phenotype, then showed the heterogeneity in which the transitional form of mast cells emerged followed by the appearance of the CTMC type.

Animals↗
PubMed1990

Growth of a Japanese isolate of Taenia crassiceps in intermediate and definitive hosts.

Higher infection rates were observed in gerbils and voles than in ICR mice after oral inoculation with eggs of a Japanese isolate of Taenia crassiceps. Asexual reproduction of T. crassiceps cysticerci was observed in all gerbils and voles infected i.p. with the cysticerci. However, ICR mice and Wistar rats were not suitable for the asexual proliferation of T. crassiceps. The hooks of cysticerci from mice were smaller than those from gerbils. In experimentally infected puppies, parasite development was noted as follows: strobilation and initial differentiation of the genital primordia on day 7 postinoculation (p.i.), appearance of the testes on day 9, observation of the ovaries on day 10, and development of the lateral branches of the uterus on day 15. The prepatent period was 27-31 days. After day 15 p.i., most of the worms were recovered from the middle third of the small intestine. The number of proglottids shed per day by each strobila was about 1. The number of eggs contained in a gravid segment was about 13,000.

Animals↗
PubMed1990

A new screening method for melanin biosynthesis inhibitors using Streptomyces bikiniensis.

A novel screening method for melanin biosynthesis inhibitors using Streptomyces bikiniensis NRRL B-1049 as the indicator organism has been developed. Several known compounds, including tyrosinase inhibitors, were found to inhibit melanin production of S. bikiniensis on agar plates. This screening method was applied to fermentation broths of actinomycetes and several cultures with melanin biosynthesis inhibitory activity were found.

Histidine↗
PubMed1990

Quinaldopeptin, a novel antibiotic of the quinomycin family.

Quinaldopeptin, a new type of quinomycin antibiotic, was isolated from the culture of Streptoverticillium album strain Q132-6. The antibiotic exhibited strong in vitro antimicrobial and cytotoxic activity and significantly prolonged the survival time of mice inoculated with a murine tumor. Quinaldopeptin is a symmetric cyclic peptide linked only by peptide bonds and differs from known antibiotics of the quinomycin family by the lack of ester linkage.

Amino Acid Sequence↗
PubMed1990

Parasites from the Asiatic black bear (Ursus thibetanus) on Kyushu Island, Japan.

Two Dirofilaria ursi, six Trichodectes pinguis and numerous Haemaphysalis megaspinosa were obtained from an Asiatic black bear (Ursus thibetanus) shot in Kyushu, Japan. The presence of two parasites specific to black bears may indicate the existence of a wild population, although the bears are regarded to be extinct on Kyushu Island.

Animals↗