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S Namioka

Publications and source records attributed to S Namioka.

At least 37 records · Page 2Linked to original sources
PubMed1993

Hypersensitivity of LEC strain rats in radiation-induced acute bone-marrow death.

LEC strain rats, which have been known to develop hereditarily spontaneous fulminant hepatitis 4 to 5 months after birth, were highly sensitive to whole-body X ray-irradiation as compared to WKAH strain rats. Radiation-induced acute bone-marrow death occurred at doses higher than 2.0 Gy in LEC rats, and at doses higher than 7.4 Gy in WKAH rats, respectively. By probit analysis of survival data, it was shown that the LD50/30 value for LEC rats was 3.0 Gy which was significantly lower than that (7.8 Gy) of WKAH rats. Histopathological examinations of the bone marrows from both strains after irradiation at a dose of 4.0 Gy revealed that a number of hemopoietic cells were recovered in WKAH rats on day 8 after irradiation, but not in LEC rats. These results suggested the hypersensitivity of LEC rats to ionizing radiation in connection with acute bone-marrow death.

Animals↗
PubMed1993

Transgenic mice with antisense RNA against the nucleocapsid protein mRNA of mouse hepatitis virus.

In this study transgenic mice which expressed antisense RNA against the nucleocapsid protein gene of mouse hepatitis virus (MHV) under the control of RSV LTR were produced. These transgenic mice were able to transmit the foreign gene to their progeny in a Mendelian fashion. Antisense RNA was detected in various tissues from the transgenic mice including liver and brain, the target organs of MHV infection. One strain of transgenic mice derived from founder mouse No. 19 was more resistant to the lethal challenge of MHV than non-transgenic mice. The results of the present study show the ability of antisense RNA against the viral gene to protect against viral infection in vivo.

Animals↗
PubMed1992

Higher sensitivity of LEC strain rat in radiation-induced acute intestinal death.

LEC strain rats (LEC rats), which have been known to develop hereditarily spontaneous fulminant hepatitis 4-5 months after birth, were highly sensitive to whole-body X-irradiation as compared to WKAH strain rats (WKAH rats). Radiation-induced acute intestinal death occurred at doses higher than 6.5 Gy in LEC rats, and at doses higher than 12.8 Gy in WKAH rats, respectively. By the probit analysis of survival data, it was shown that the LD50/7 value of LEC rats was estimated to be 7.03 Gy which was significantly lower than that (12.99 Gy) of WKAH rats. Histopathological examinations of small intestines from LEC rats 2 days after irradiation at the dose of 8.5 Gy showed severe epithelial death together with edema, whereas little or no significant changes were noted in intestinal epithelium of 8.5 Gy-irradiated WKAH rats. These results suggest that the radiosensitivity of LEC rats to ionizing radiation appears to be higher than that of other strains of rats.

Animals↗
PubMed1992

Inhibition of mouse hepatitis virus multiplication by an oligonucleotide complementary to the leader RNA.

An oligonucleotide complementary to a leader RNA of positive-stranded mouse hepatitis virus (MHV) was tested for the effect on the viral multiplication in mouse DBT cells. A 14-mer antisense oligonucleotide contained a sequence complementary to the conserved pentanucleotide sequence, UCUAA, of the leader RNA. A treatment of MHV-infected cells with the antisense oligonucleotide at concentrations from 5 to 25 microM had an inhibitory effect on the viral multiplication and reduced the synthesis of viral specific mRNA and proteins. No inhibitory effect was observed when the cells were treated with sense oligonucleotide and oligonucleotide which contained unrelated sequences at concentrations from 1 to 10 microM. These results showed that antisense oligonucleotide against the leader RNA reduced the multiplication of positive-stranded RNA virus, MHV.

Animals↗
PubMed1992

Unidirectional distribution of mosaicism in chimeric rats.

Experimental rat chimeras were produced by aggregation of eight-cell embryos from two inbred strains, ACI/Hkm and WKAH/Hkm, which differ from each other in their major histocompatibility complexes and coat colors, and their mosaicism was analyzed. The existence of the isozyme Es-1, a serum cholinesterase specifically produced by WKAH-derived cells, and the agouti coat color due to ACI cells, indicated that all of the rats analyzed were unequivocal chimeras. The proportion of ACI cells in the red blood cell populations of the chimeras varied from 45% to 98%, as determined with a fluorescence-activated cell sorter and a monoclonal antibody against class I (RT1) antigen. Digital analysis of the coat color revealed that the proportion of the ACI type of coat color ranged from 72% to 98% in these chimeric rats. Each phenotype expressed in the coat color was complex and varied in size. The ratios of red blood cells and the coat color inclined toward the ACI type of cell population. Conversely, the rate of the WKAH-cell-type population was less than 50%. A breeding test disclosed chimerism of germ cells in two chimeric rats, and there were more pups with agouti coats than with albino coats. Taken together, it was shown in most of the phenotypes analyzed that the ACI type of cells was predominant in all of the chimeric rats. We discuss the possible causes for this unbalanced distribution in the rats.

Animals↗
PubMed1991

The inhibitory effects of oligonucleotides, complementary to Marek's disease virus mRNA transcribed from the BamHI-H region, on the proliferation of transformed lymphoblastoid cells, MDCC-MSB1.

An oligonucleotide complementary to the splice donor sequence of the 1.8 kb gene family produced from the BamHI-H region of Marek's disease virus (MDV) DNA inhibited the proliferation of the MDV-derived lymphoblastoid cell line, MDCC-MSB1 (MSB-1), but not that of the avian lymphoid leukosis-derived lymphoblastoid cell line, LSCC-BK3. Colony formation in soft agar was also inhibited by treatment of MSB-1 cells with the antisense oligonucleotide. It is hypothesized that expression of the 1.8 kb gene family produced from the BamHI-H region is directly associated with the maintenance of the tumorigenic state of transformed Marek's disease-derived lymphoblastoid cells.

Animals↗
PubMed1991

Nucleosomal structure of Marek's disease virus genome in transformed lymphoblastoid cell lines, MDCC-MSB1 and MDCC-RP1.

The latent MDV (Marek's disease virus) genomes are folded into nucleosomal structures in both virus-productive and -nonproductive lymphoblastoid cell lines, MDCC-MSB1 (MSB-1) and -RP1 (RP-1), respectively. There was no difference between transcriptionally active and inactive regions of MDV genome with regard to nucleosomal patterns. In order to investigate whether nucleosomal structure is correlated with the repression of the transcription of MDV genome in lymphoblastoid cells, we examined the DNaseI sensitivity of nucleosomal MDV DNA in lymphoblastoid cell lines, MSB-1 and RP-1. No difference in the DNaseI sensitivity between transcriptionally active and inactive MDV DNA regions in lymphoblastoid cells was observed.

Blotting, Northern↗
PubMed1990

Restriction fragment length polymorphism for the Yc subunit gene of rat liver glutathione S-transferase.

An altered expression of the Yc subunit gene of rat glutathione S-transferase (GST) in the liver of the LEC rat, which is a mutant strain with spontaneous hereditary hepatitis associated with severe jaundice, has been reported. To provide further information concerning the structure of the Yc subunit gene, we carried out the Southern blot hybridization analysis of DNA samples from rats of eight different inbred strains including LEC with cDNA complementary to mRNA specific for the Yc subunit of rat liver GST as a probe. The hybridization patterns of the DNA samples from rats belonging to the different inbred strains showed interstrain variation in the length of restriction fragments with four restriction endonucleases. Since the DNA samples prepared from several rats of one inbred strain gave an identical hybridization pattern, the restriction fragment patterns for the Yc gene could be used as markers for genetic monitoring of inbred rat strains. Although the altered expression of Yc-Yc activity of GST has been observed in the liver of the LEC rat, the characteristic changes in the gene structure of the Yc subunit of LEC rat were not detected in the present hybridization analysis.

Animals↗
PubMed1989

Biological effects of lipopolysaccharide from Achromobacter stenohalis on lymphocytes and macrophages.

The immunopotentiating activities of lipopolysaccharide from Achromobacter stenohalis (A-LPS) were examined. A-LPS was structurally atypical and gave no endotoxin shock in A-LPS-inoculated mice. Analysis in vitro showed that A-LPS was a potent activator of both macrophages and B-lymphocytes. After macrophage stimulation with A-LPS, interleukin-1 (IL-1) secretion, interferon (IFN) production and chemiluminescence (CL) response were induced. A-LPS was a potent mitogen for spleen lymphocytes. However, induction of interleukin-2 (IL-2) secretion in T lymphocytes was not observed. These activities of A-LPS were similar to or higher than that of enterobacterial LPS.

Alcaligenes↗
PubMed1989

Oral flora of mongrel and beagle dogs with periodontal disease.

The plaque flora was studied in adult mongrel and beagle dogs with periodontal disease. Gingival plaque from maxillary premolars was removed and cultured on various growth media. The flora in all dogs was composed of mostly anaerobic gram negative rods. Bacteroides asaccharolyticus was found in the highest proportion of plaque samples from mongrel dogs, and decomposed hydrogen peroxide suggesting catalase activity. Fusobacterium nucleatum was found in higher proportion in the plaque of beagle dogs as compared to B. asaccharolyticus. With the increasing numbers of obligative anaerobic gram negative organisms such as B. asaccharolyticus, the proportions of Streptococcus, Enterococcus and Staphylococcus decreased in the dogs with periodontal disease. The salivary flora was different from the plaque flora of the dogs with periodontal disease. It was constant regardless with the disease. The salivary flora of beagle dogs with the healthy gingiva was different from that of mongrel dogs. Enterococcus, Lactobacillus, Eubacterium and black-pigmented Bacteroides (BPB, mainly B. asaccharolyticus) were higher proportion in the flora of beagle dogs as compared to mongrel dogs, while Fusobacterium, Enterobacteriaceae, yeast and molds were lower in the flora. The results reveal that B. asaccharolyticus and F. nucleatum are common pathogens and uniquely contribute to the development of gingival inflammation in dog.

Animals↗
PubMed1989

Escherichia coli associated endotoxemia in dogs with parvovirus infection.

Escherichia coli bacteremia and endotoxemia were observed in 3 adult mongrel dogs which had been prediagnosed as canine parvoviral disease. The endotoxin level was 46.5 pg/ml in the plasma of clinical cases, while 2.3 pg/ml in healthy controls. The microflora of the feces was confused in the clinical cases. The percentage of E. coli was major in the feces. Serologically similar strains were isolated from the blood. These strains did not produce enterotoxins such as heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT). Histopathologically, the lesions in the small intestine consisted of epithelial degeneration and necrosis. Viral inclusion bodies were frequently observed in the epithelial cells. Disseminated intravascular coagulation was observed in various tissues including the liver and small intestinal submucosa. After experimental infection with CPV, all dogs showed various clinical signs. CPV was positive in the feces. Endotoxin level in the plasma gradually increased and high level continued for long period from 10 to 30 days. Mean maximum level of endotoxin in the experimental dogs was 73.6 pg/ml. These results indicate that intestinal flora plays a important role in the pathogenesis of CPV infection and that endotoxin is one of the factors which predispose to severe disease after the infection.

Animals↗