Search PubMed⌕ Search

Biomedical subjects

M Muto

Publications and source records attributed to M Muto.

At least 163 records · Page 9Linked to original sources
PubMed1985

Cellular events during radiation-induced thymic leukemogenesis in mice: abnormal T cell differentiation in the thymus and defect of thymocyte precursors in the bone marrow after split-dose irradiation.

Cellular events during the development of thymic lymphomas in young B10.BR mice given leukemogenic split-dose irradiation were studied by examining the differentiation of functional T lymphocyte precursors in the regenerating thymus. It was found that leukemogenic radiation treatment resulted in a sustained depression of the level of thymic cytotoxic T lymphocyte precursors (CTLp) and of mixed lymphocyte reactivity of thymus cells when assessed between 1 and 4 mo after irradiation, in spite of the fact that the total number of thymocytes was restored to the normal level within 2 mo and continued to increase thereafter. In vitro mixing studies of normal thymocytes with thymus cells from split-dose irradiated mice provided no evidence for active suppression as a mechanism for this depressed activity. The ability of bone marrow cells from split-dose irradiated mice to regenerate the thymus and to differentiate into functional CTLp was examined by use of supralethally irradiated Thy-1 congenic recipients. Reconstitution of supralethally irradiated B10.BR Thy-1.2 mice with normal bone marrow from B10.BR Thy-1.1 mice resulted in the complete repopulation of host-thymus with donor-derived cells when assessed at 4 wk after reconstitution. Lymphocytes from the regenerating thymus of these animals were shown to contain high levels of CTLp which were donor-derived. On the other hand, when the recipient mice were reconstituted with bone marrow cells from donor mice which had been split-dose irradiated 1 mo earlier, regeneration of the recipient thymus was severely depressed when assessed at 4 wk to 3 mo after reconstitution. Although variable but small numbers of donor-derived Thy-1+ cells were detected, CTL activity for alloantigen could not be induced in these donor-derived cells. The results suggest that T cell precursors derived from split-dose irradiated donor mice were unable to undergo active proliferation and differentiation into functional CTLp. The significance of these findings on radiation-induced thymic leukemogenesis is discussed.

Animals↗
PubMed1983

Reconfirmation of indirect induction of radiogenic lymphomas using thymectomized, irradiated B10 mice grafted with neonatal thymuses from Thy 1 congenic donors.

An experiment was conducted to reexamine earlier observations that lymphomas could develop from lymphocytes present in nonirradiated thymuses grafted into thymectomized, fractionally (170 R, 4 doses) irradiated mice by using B10. Thy 1 congenic donor-host combinations. The results indicated that: (a) 37 of 91 thymectomized, fractionally irradiated B10. Thy 1.2 mice which were grafted s.c. with 7-day-old thymuses from B10. Thy 1.1 donor mice had developed frank lymphomas between 90 and 270 days after thymus grafting; (b) 28 of 37 lymphomas developed in this group were typed individually with respect to Thy 1 alloantigens by the cytotoxicity assay using monoclonal anti-Thy 1.1 (T-11-D7) and anti-Thy 1.2 (F7D5) antibodies plus complement. It was shown that 21 thymic lymphomas (75%) had originated from lymphocytes of the nonirradiated thymus grafts and 5 tumors (17.9%) from cells of the irradiated hosts; 2 thymic lymphomas (7.1%) manifested no Thy 1 antigens; (c) lymphoma cells originated from both nonirradiated thymus grafts and irradiated hosts possessed chromosome abnormalities, which were mainly numerical changes of some chromosomes or polyploidizations.

Animals↗
PubMed1983

Mechanism of action of praziquantel on the eggs of Schistosoma japonicum.

The mode of action of praziquantel on Schistosoma japonicum eggs was examined in mice and in vitro. In a long term oogram observation of mouse intestine, lasting from 1 to 56 days after oral administration of 100 mg/kg 4 times in one day, many empty egg shells were observed from the next day. Immature eggs, however, were not killed, but developed into miracidia that later degenerated into granulated and calcified eggs. In the oograms of mouse, from 5 to 240 minutes after a single oral dose of 100 mg/kg of praziquantel, miracidium hatching occurred 5 minutes in the tissues after treatment. In the in vitro experiment, miracidia in eggs from cut pieces of intestine began to hatch starting 5 minutes after exposure to praziquantel at least at a concentration of 1 ng/ml and reached maximum hatching at 30 minutes and died in several minutes after hatching.

Animals↗
PubMed1982

[Water intake and urinary output in rhesus (Macaca mulatta) and cynomolgus monkeys (Macaca fascicularis)].

Water intake (drinking water and water from food) and urinary output in rhesus (Macaca mulatta) and cynomolgus monkey (M. fascicularis) watered ad libitum in individual cage were examined with 52 animals. The animal room was maintained at 25 +/- 2 degrees C and 55 +/- 10% with relative humidity, being lit at 12 hours interval. Water intake was found in wide variation between individuals, and about 20% of the monkeys were recognized as polydipsia without another abnormal behavior. No significant variation was found between daily water intake, but periodical (or seasonal) variation was observed in polydipsic monkey. Urinary output changed accordingly with water intake. Rate of the urinary output to the water intake was 76% in male rhesus, 59% in male cynomolgus and 49% in female cynomolgus. The rate was higher in the polydipsia than in the normal monkey. Diurnal patterns of water drinking and urinary output indicated that the monkeys were mostly active during the hours of lighting. Some effects of experimental procedure were observed on drinking and voiding in cynomolgus monkeys while no effect on rhesus monkeys. Prandial drinking was observed in monkeys as was reported on other laboratory animals such as rats.

Animals↗
PubMed1980

Neurogenic tumor of small intestine, report of a case with review of literature.

A case of neurofibroma of small intestine presented with massive intra-abdominal bleeding was reported. There was a total of 51 cases of neurogenic tumor of small intestine including the present case to be collected from Japanese literature. 33 cases were not associated with Von Recklinghausen's disease. Discussion was given according to their sex and age distribution, symptom and sign, type of development, tendency of malignant degeneration, and treatment.

Gastrointestinal Hemorrhage↗
PubMed1979

Three dimensional organization of mammalian adrenal cortex. A scanning electron microscopic study.

The adrenal cortex of different mammals was studied by SEM in order to demonstrate its actual three-dimensional organization. In the rat, as well as in the cat and pig, the adrenal cortex appeared as a "tunnelled continuum" of polyhedral cells arranged in plate-like structures (laminae). This laminar arrangement was more evident in the inner fasciculate and reticular zones where the cortex revealed a striking similarity to liver tissue. The polyhedral cells of all cortical zones possessed regular facets populated by small pits, larger invaginations and numerous microvilli with the exception of very short and smooth areas probably corresponding to attachment zones and/or gap junctions. This cellular architecture produced a labyrinthic system of intercellular channels or lacunae in which the capillaries were suspended. The pericapillary areas of this labyrinth contained microvilli, amorphous material, a delicate net of fibrils and occasional cells. The intercellular compartment of this lacunar system was mainly bordered by numerous microvilli arising from endocrine cells. The luminal surface of the capillary wall showed not only irregularly protruding margins (interpretable as endothelial junctions) but also clearly overlapping and flattened endothelial extensions. In all the animals and areas of the adrenal cortex examined, the endothelial wall was provided with abundant clusters of small fenestrations (about 50 nm in diameter) generally arranged in sieve plates. Larger fenestrations were noted mainly in the fasciculate and reticular zones of the cat and pig and occasionally in the rat. A final point related to the nature and significance of sinusoidal fenestrations was the occurrence of irregularly shaped and intracapillary located cells mainly noted in the deeper zones of the fasciculate and reticular zones of the gland. These elements--possessing the surface characteristics of macrophages--were observed, with their irregular and slender evaginations, in close proximity to the large fenestrations in a manner reminiscent of Kupffer cells within the lumen of liver sinusoids.

Adrenal Cortex↗
PubMed1978

Results of esophagocardioplasty with gastric patch in the treatment of esophageal achalasia.

Since 1968 esophagocardioplasty with gastric patch was employed in 57 patients as a primary operation for achalasia of the esophagus and eight patients with previous operations for achalasia. Satisfactory results were obtained in follow-up studies up to eight years. The results indicate that this procedure is successful in dilating the lower part of the esophagus and esophagocardiac junction without interfering with their proper functions. This provides better passage through the junction with preservation of the mechanism which prevents reflux.

Adult↗