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Biomedical subjects

K Umehara

Publications and source records attributed to K Umehara.

At least 73 records · Page 4Linked to original sources
PubMed1986

Cytopathic effects of antigens in patients with IgA nephropathy.

The cytopathic effects of extracts of pharyngeal cells from patients with IgA nephropathy on fibroblasts were determined. Autoradiographical analysis of antigens in the fibroblasts was also described. Freeze and thawed extracts of pharyngeal cells obtained from patients with IgA nephropathy, other glomerular diseases and healthy adults were cultured with fibroblasts such as Vero or Hel cells at 37 degrees C for 1 or 2 weeks. The cytopathic effects of fibroblasts were examined with a light microscope. In addition, the eluate obtained from renal tissues of IgA nephropathy was labeled with iodine-125 by the chloramine-T method. These cultured fibroblasts were incubated with iodine-125-labeled eluate from the same or other patients with IgA nephropathy. The degree of cytopathic effects of extracts of pharyngeal cells from patients with IgA nephropathy on Vero or Hel cells was significantly increased compared with that from patients with other glomerular diseases or healthy adults without glomerular diseases. The cytopathic effects of such fibroblasts were not inhibited by filtration of extracts of pharyngeal cells obtained from patients with IgA nephropathy. It was shown that the antibodies eluted from renal tissues of patients with IgA nephropathy specifically bound with the nuclear regions of such fibroblasts. It was suggested that some antigenic substances might exist in the epithelial cells of the upper respiratory tracts of some patients with IgA nephropathy, and that such antigens were able to be transferred to cultured fibroblasts.

Adult↗
PubMed1986

Trial of isolation of a virus from sera of patients with Kawasaki disease.

We tried to isolate pathogenic viruses from specimens of patients with Kawasaki disease. Blood clots and sera, spinal fluid, throat swabs, stool and urine from 24 patients with Kawasaki disease were studied. The specimens were inoculated into HEL cells and Vero cells. The cells were observed for one month, but no cytopathic effect (CPE) occurred. Blind passage was performed, but no degeneration of the second series of cells was observed. Fluorescent antibody indirect methods to determine viral antigens in cells inoculated with patients' specimens was also negative.

Child, Preschool↗
PubMed1985

Specific binding of circulating IgA antibodies in patients with IgA nephropathy.

Detection of circulating IgA antibodies which are specific in patients with IgA nephropathy is described. Freeze and thawed extracts of pharyngeal cells obtained from patients with IgA nephropathy, other glomerular diseases, and healthy adults were cultured with fibroblasts such as Vero or Hel cells at 37 degrees C for 2 weeks. Serum samples were obtained from these patients and healthy adults. The cultured fibroblasts were fixed on slide glasses, and then incubated with the serum samples from the same or other patients with IgA nephropathy. The cells were stained with FITC-labeled heavy-chain specific anti-human IgA antiserum and then examined with a fluorescent microscope. It was demonstrated that the IgA antibodies in sera obtained from patients with IgA nephropathy or HSP nephritis were bound with the nuclear regions of such fibroblasts. It was suggested that IgA antibodies in sera could be bound with some antigenic substances which were transferred from pharyngeal cells of patients with IgA nephropathy to fibroblasts in vitro.

Antibodies, Anti-Idiotypic↗
PubMed1984

Restoration of aerial mycelium and antibiotic production in a Streptomyces griseoflavus arginine auxotroph.

An arginine auxotrophic mutant was obtained from Streptomyces griseoflavus (bicozamycin-producing strain). The mutant grew on synthetic agar supplemented with either arginine, ornithine, citrulline or argininosuccinate, but produced massive aerial mycelium and bicozamycin only with citrulline. In liquid culture, citrulline also completely restored the ability of the mutant to produce bicozamycin. Culture with arginine or ornithine markedly changed intracellular pools of these ornithine-cycle amino acids, but did not affect the other amino acid pools. The ability to produce antibiotic (but not that to form aerial mycelium) was partially restored by certain mutations to ethionine resistance (Eth-1 and Eth-2). These mutations caused decreased or increased S-adenosylmethionine synthetase activity, but both resulted in a 4.5-8-fold increase in the intracellular S-adenosylmethionine pool. Exogenous addition of S-adenosylmethionine (0.5-3 mM) also partially restored the antibiotic-producing ability of the arginine auxotroph. No difference in the S-adenosylmethionine pool was observed in organisms grown with arginine and citrulline. It was suggested that citrulline and S-adenosylmethionine are somehow involved in the initiation of differentiation and secondary metabolism of S. griseoflavus.

Amino Acids↗
PubMed1984

Fluctuation of antiviral resistance in the intestinal tracts of nude mice infected with a mouse adenovirus.

Oral administration of adenovirus strain K87 to BALB/c nude mice resulted in viral proliferation in the intestinal tract up to around week 6 at which point replication was suppressed. In other words, the host acquired resistance. However, this resistance was temporary and the viral infection persisted over a long period with repeated periods of proliferation and resistance. That the appearance of this resistance is the result of infecting mice with the virus and is not due to age difference per se was made clear through experimentation with nude mice of different age groups. However, it was indicated that increase in age is involved in the decreased rate of reproliferation following initial suppression. No evidence of the virus was obtained from any other organ throughout the infection. Furthermore, throughout the persistent infection, even during the aforementioned periods of resistance, no neutralizing antibody was detected from sera, intestinal wall or intestinal content. When spleen cells from BALB/c heterozygous littermate mice was transferred to the nude mice, an earlier onset of antiviral resistance was seen than in nude mice without the transfer, and this was accompanied by a rise in neutralizing antibody titer. From these results, it is believed that the resistance characteristic of nude mice infected by mouse adenovirus is dependent on some factor other than the neutralizing antibody invoked resistance exhibited by euthymic mice.

Adenoviridae↗
PubMed1984

[Nitrogen retention in germ-free and conventional mice reared on an antigen-free diet and the significance of the appearance of protein nitrogen in their feces].

The nutritional state of animals removed from as much antigenic stimuli as possible--germ-free mice on an antigen-free liquid diet--was compared with that of conventional mice through assessment of their protein metabolism. Both the germ-free and conventional mice reared on the antigen-free liquid diet for 7 weeks exhibited relatively stable body weight throughout the experimental period. Although the nitrogen retention rate was generally higher for the conventional mice, even in the germ-free mice with the exception of one observation in a male, positive nitrogen retention rates were observed, and this suggests nutritional adequacy of the diet. The amount of protein-nitrogen excreted in the feces due to the physiological processes, such as the digestive tract cell turnover, digestive juice secretions, etc, (4.2-5.3 mg/mouse/week), and the amount that was influenced by the presence of intestinal bacteria and due to bacterial protein per se (2.3-4. 4 mg /mouse/week) could be estimated through the comparison of the fecal protein values obtained from germ-free and conventional mice reared on the antigen-free liquid diet.

Animals↗
PubMed1984

Studies on new antiplatelet agents, WS-30581 A and B.

WS-30581 A and B are antiplatelet agents produced by a strain of Streptoverticillium waksmanii. The compounds were purified by solvent extraction and column chromatography, and identified as new pimprinine analogs on the basis of their physico-chemical properties. The producing organism produced pimprinine along with these compounds. Pimprinine and the two new analogs have potent inhibitory effects on platelet aggregation.

Animals↗
PubMed1984

Studies on WF-5239, a new potent platelet aggregation inhibitor.

WF-5239 was produced by a fungal strain identified as Aspergillus fumigatus Fresenius. The substance was purified by solvent extraction followed by chromatography on silica gel and then crystallized (C9H9NO2, mp 142 approximately 145 degrees C). The chemical structure was determined from its physico-chemical properties as N-[2-cis(4-hydroxyphenyl)ethenyl]formamide. WF-5239 has inhibitory activity against rabbit platelet aggregation induced by arachidonic acid and collagen, with IC50 values of 1.25 and 5.0 micrograms/ml, respectively. Arachidonic acid induced mortality in mice was reduced by a single intraperitoneal dose of WF-5239 (30 mg/kg). These biological properties have been compared with those of aspirin.

Animals↗
PubMed1983

Studies on WF-3161, a new antitumor antibiotic.

WF-3161 is an antitumor antibiotic produced by a strain of fungus, Petriella guttulata. The antibiotic was purified by solvent extraction and a combination of silica gel and reverse phase column chromatography. The chemical structure of the antibiotic (C31H44N4O6, mp 181-183 degrees C) was found to be a cyclic tetrapeptide consisting of phenylalanine, leucine, pipecolinic acid and 2-amino-8-oxo-9,10-epoxydecanoic acid. WF-3161 inhibited the growth of Trichophyton asteroides. It prolonged survival period of mice bearing leukemia P-388 with a high therapeutic index.

Animals↗
PubMed1982

Studies on new vasodilators, WS-1228 A and B. I. Discovery, taxonomy, isolation and characterization.

New vasodilators, designated WS-1228 A and B have been discovered in the culture filtrate of a strain of Streptomyces aureofaciens. The active compounds were purified by column chromatography with Diaion HP-20 and silica gel, and finally separated from each other by high performance liquid chromatography. They were obtained as pale yellow crystals and their molecular formulae were both C11H17N3O.

Animals↗
PubMed1979

Susceptibility to adjuvant-induced arthritis among germfree, specific-pathogen-free, and conventional rats.

Germfree F344 rats developed severe arthritis with 100% incidence after a single intradermal inection of either squalane containing 0.5 mg of heat-killed Mycobacterium bovis BCG or a water-in-oil emulsion containing 0.2 mg of peptidoglycan derived from Staphylococcus epidermidis. Conventional F344 rats developed less-severe arthritis with 20% incidence for heat-killed BCG and 0% incidence for peptidoglycan. Specific-pathogen-free rats showed an intermediate susceptibility between germfree and conventional rats. Interestingly, both unimmunized specific-pathogen-free and conventional rats. but not unimmunized germfree rats, showed weak delayed-type hypersensitivity reactions to peptidoglycans derived from either S. epidermidis or Lactobacillus plantarum, suggesting that a bacterial flora may furnish a stimulus for induction of cell-mediated immunity to ubiquitous bacterial peptidoglycans. It is thus possible that although a bacterial flora is not necessary for development of adjuvant arthritis, it may have some suppressive effect on the development of the disease in specific-pathogen-free and conventional F344 rats, possibly through modulation of the immune response.

Animals↗