Search PubMed⌕ Search

Biomedical subjects

T Shimamura

Publications and source records attributed to T Shimamura.

At least 199 records · Page 11Linked to original sources
PubMed1986

Selection of hypotoxigenic Vibrio cholerae population by human intestinal bacteria in gnotobiotic mice.

Strains of human intestinal bacteria when cultured with Vibrio cholerae 569B, classical Inaba, exerted either inhibitory or promotive effects on cholera toxin production. An inhibitory strain of Bacteroides fragilis was orally given to germfree mice a week before vibrio administration. In vibrio-monoassociated mice, the toxin production of most vibrios isolated from feces was as high as the inocula, while in Bacteroides-vibrio-diassociated mice toxin production decreased starting on day 3 after vibrio administration and vibrios with 1/250 to 1/1,000 of the toxin production levels of the inocula dominated 1 and 2 wk after administration. The number of vibrios remained basically unchanged in vibrio-monoassociated mice, but was kept low in Bacteroides-vibrio-diassociated mice throughout the experimental period of 4 wk. Fecal concentration of succinic acid was higher in Bacteroides-associated mice than in vibrio-monoassociated mice. An isolate from a vibrio-monoassociated mouse yielded poorer colony formation on a heart infusion agar plate containing 6.25 mM succinic acid than a vibrio from a Bacteroides-vibrio-diassociated mouse. Isolates from agar plates containing succinic acid showed low cholera toxin productivity. Thus, the presence of the Bacteroides in gnotobiotic mice may have resulted in the selection of a less toxigenic vibrio population, and succinic acid produced in abundance in Bacteroides-associated mice may be one of the selecting factors.

Animals↗
PubMed1986

Immunological effects of arsenic compounds on mouse spleen cells in vitro.

Immunological effects of arsenic compounds on mouse spleen cells in vitro were examined. Three kinds of arsenic compounds: sodium arsenite, sodium arsenate and dimethyl arsenic acid, at high doses, suppressed the plaque-forming cell response to sheep erythrocytes and the proliferative response to mitogens, whereas at low doses they enhanced both responses. And each of arsenic compounds differs in strengths at which the modulation effects on both responses were exerted. The strength was comparable to general toxicity of arsenic compounds.

Animals↗
PubMed1984

Feedback suppression of the immune response in vivo. III. Lyt-1+ B cells are suppressor-inducer cells.

We previously demonstrated that injection of a high dose (4 X 10(9] of sheep erythrocytes (SRBC) into C57BL/6 mice results in the generation of splenic B cells (plastic nonadherent, Thy-1- and Ig+) which, when transferred to normal syngeneic recipients, subsequently induce antigen-specific suppressor T cells to suppress the recipient's plaque-forming cell (PFC) responses to SRBC. In the present study we characterized the suppressor-inducer B cells phenotypically. Cytotoxic treatment of the donor's immune spleen cells with anti-Lyt-1 antibody plus complement (C'), but not with anti-Lyt-2 antibody plus C', relieved the suppression of PFC responses in recipients. The FcRr+ population separated by EA-rosette formation showed enriched suppressor-inducing activity, whereas the FcRr- population showed no activity. Our findings, taken together with the previous ones, suggest that suppressor-inducer cells are Thy-1-, Lyt-1+, Lyt-2-, FcRr+, and Ig+.

Animals↗
PubMed1984

A method to identify microinjected nephrons of rat.

This paper describes a technique for identifying individual nephrons that have been subjected to micropuncture. The general location of the nephron is marked on the surface of the kidney by implanting two micropipette tips on opposite sides of it two or three tubule diameters away. The tubule itself is marked by the injection into the lumen of a tracer material, for purposes of this account, a suspension of E. coli. After perfusion fixation the kidneys are removed and a block of tissue containing the extrapapillary portion of the nephron is excised. This block is cut into thin slices parallel to the surface of the kidney; these are embedded in plastic for subsequent sectioning. On sectioning, the marker material makes the nephron in question readily discernible under the microscope. A major advantage of this technique is that it allows the tubule of interest to be located as much as 48 hours later.

Animals↗
PubMed1984

A case report of intestinal myiasis.

A case of mixed infection of Salmonella (type C2) and Parasarcophaga crassipalpis (an intestinal myiasis) in a two-year-old girl is reported. A girl after dining in a restaurant developed typical Salmonella food-poisoning symptoms. Stool culture showed both Salmonella and fly larvae. This paper is to report a first case of this fly larvae infection and to review the recent trends of food-poisoning in Japan.

Child, Preschool↗
PubMed1983

Focal glomerulosclerosis in obese zucker rats and prevention of its development.

Genetically obese Zucker rats develop a spontaneous glomerular disease. The mechanism of development of this lesion is poorly understood. We therefore examined structural alterations of the kidneys by light microscopy and by use of nephron dissection technique. The glomerular lesion was a focal segmental sclerosis that developed in association with glomerular enlargement and with prominent dilation of collecting and connecting tubular lumina. Reduction of dietary intake in these obese rats prevented the emergence of glomerulomegaly, glomerulosclerosis, and tubular dilation. The development of the glomerulosclerosis might be related to glomerulomegaly. In addition, the prominent dilation of collecting and connecting tubules without evidence of obstruction of lower urinary tract indicated that there was intrarenal tubular obstruction.

Animals↗
PubMed1982

[Toxicological study of amikacin following intravenous drip infusion. 2. Subacute toxicity in dogs after intravenous injection].

Subacute toxicity of amikacin sulfate (AMK) was investigated with 50 Beagle dogs (male 25, female 25). As a substitute for drip intravenous infusion (d.i.v.), AMK was administered by intravenous injection (i.v.) twice a day, 1 hour apart, for 38 days at daily doses of 400, 200, 100 mg/kg and 25 mg/kg. 1. At the doses of 25 mg/kg and 100 mg/kg, there were no significant changes or signs recognized as toxicological effects of AMK. 2. At the dose of 200 mg/kg, slight renal damages were observed in 3 of 5 males and 2 of 5 females. These were slight elevation of urea N and creatinine, and slight degeneration or regeneration of the renal proximal tubules. 3. At the dose of 400 mg/kg, renal damages were noted in all the dogs. Two males and 1 female died after 14-17 days' treatment and the remainders were sacrificed for inspection after 18-20 days' treatment. In any dogs, the adverse findings were mainly observed in the renal proximal tubules but not in the glomeruli. In the other organs, there were no significant impairments. 4. From these results, it is considered that the maximum no effect dose of AMK is 100 mg/kg.

Amikacin↗
PubMed1982

[Effects of intravenous infusion of amikacin. Intraperitoneal administration to rats before and in the early stage of pregnancy. Segment 1].

Fertility study on amikacin sulfate (AMK) was carried out in Wistar rats. AMK was administered intraperitoneally at the doses of 0, 25, 100 mg/kg/day and 200 mg/kg/day in males for 60 days prior to mating and mating period and in females for 14 days prior to mating, mating period and day 0-7 of gestation. The drug induced no significant changes or signs in parent animals, except that soft feces was occasionally found at the 100 mg/kg/day and 200 mg/kg/day and the impairment in kidneys was recognized only at the 200 mg/kg/day. There were no adverse effects on mating, fertility or reproduction indices in males and females. And there were no evidences of teratogenic or embryotoxic effects in at any doses of AMK.

Amikacin↗
PubMed1981

Experimental cholera in germfree suckling mice.

Vibrio cholerae V86 El Tor Inaba caused experimental cholera in germfree ICR suckling mice. Sucklings born of gnotobiotic mothers monoassociated with the same strain were completely protected against live oral homologous challenge.

Animals↗
PubMed1981

Molecular properties of cholera enteroxin.

The molecular properties of Vibrio cholerae enterotoxin obtained from two different insitutions were studied. The preparations, which were purified by different methods, showed the same physicochemical properties. Ultracentrifugal analysis showed that the toxin had a molecular weight of 79,000, a sedimentation coefficient of 5.25 S and a diffusion coefficient of 6.02 D. When the toxin was subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the A subunit with an apparent molecular weight of 31,000-32,000 was observed. Based of these findings and the molecular weight of the B subunit of 11,604 which was calculated from its primary structure, it is proposed that holotoxin is composed of one A subunit and four B subunits.

Amino Acids↗