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Biomedical subjects

A Nishimoto

Publications and source records attributed to A Nishimoto.

At least 145 records · Page 8Linked to original sources
PubMed1979

Electron microscopic features of a brain tumor induced in hamster by BK virus, a human papova virus.

In order to locate the target cells for malignant transformation by BK virus (a human papova virus) in hamster brain, electron microscopic observation of tumor originally induced in hamster brain by BK virus was performed. With light microscopy, the BK virus-induced tumor (Vn 17) bore a close resemblance to human malignant ependymoma. Under the electron microscope, numerous microvilli and few cilia were visible on the surface of the tumor cells. These tumor cells were joined to each other by desmosomes. Gap junctions were not observed. Multilayered cuboidal cells were observed around the lumen and blood vessels in the tumor. With regard to fine structure, three types of Vn 17 cells were recognized; ependymal like cells, tanycytes with prominent cell processes, and undifferentiated cells with few cytoplasmic organelles. There was no basal lamina between the ependymal cells and the connective tissue stroma. The Vn 17 cells showed some similarity to the ultrastructural features of the epemdymal cells of newborn rabbits, suggesting that the target cells for Vn 17 may be cells related to ependyma. Malignant transformation of the cells would be initiated in the early stages after BK virus inoculation into the brain of newborn hamsters.

Animals↗
PubMed1979

[Histopathological study on experimental cerebral infarction in rat (author's transl)].

An experimental model of cerebral infarction in rat brain was successfully established by means of the unilateral internal carotid injection of carbon microspheres. A histopathological investigation of the infarcted brain was performed. The results were as follow: 1. No cerebral infarction was made by the unilateral internal carotid ligation alone. 2. Focal cerebral edema was most marked at the white matter of the embolized hemisphere. 3. The edema was also conspicuous in the deep cerebral gray matter, especially in hippocampus. Degeneration and pyknosis of the neurons were observed at the same area. 4. Transudative hemorrhage in the focal cerebral edema was usually observed in the thalamus. 5. Edematous change in the cortical gray matter was not so marked as compared with the hippocampus and thalamus. 6. Carbon microsphere was not found in the capillaries of ipsilateral choroid plexus. The present experimental model of cerebral infarction will be useful in elucidating the pathological mechanisms of the cerebral infarction.

Animals↗
PubMed1978

Immunoelectron microscopic localization of s-100 protein in cultured rat glioma cells.

Immunoelectron microscopic localization of the nervous system specific protein S-100 in the cultured rat glioma cells was successfully conducted by an unique immunocytochemical technique using peroxidase-labeled antigen binding Fab' fragments. The intensely electron dense reaction product for S-100 protein was localized mainly at ribosome granules associated with endoplasmic reticulum membranes and at free ribosome granules. S-100 protein was also associated to some extent with the cytoplasmic and nuclear membranes. A positive reaction was localized at the nuclear pores as if it were being prevented from entering into the nucleus. No activity was found in the nucleoplasm except for a slightly positive reaction product associated with nucleolus. The possible role for S-100 protein in neural cells was discussed in relation to the nuclear acidic proteins involved in genomic regulation.

Animals↗
PubMed1978

Thalamic control of spontaneous alpha-rhythm and evoked responses.

EEG, depth recordings from the thalamus, visual-evoked potentials, and readiness motor potentials were analyzed with a computer in 40 patients with involuntary movements and intractable pain who underwent stereotactic thalamotomy. It was demonstrated that there were significant correlations in alpha-rhythms between the ventrolateral (VL) nucleus and the frontocentral cortex, and also between the centromedian nucleus and the centroparietal cortex, with the phase difference of the cortex lagging behind the thalamus. Relationships between the thalamic VL nucleus and the frontocentral cortex were significant not only in alpha-rhythms, but also in evoked responses following photic stimulations, voluntary movements, and electrical thalamic stimulation. Thalamotomy produced a bilaterally decreased synchronization of the cortical alpha-rhythms, which recovered within 6 months.

Alpha Rhythm↗
PubMed1978

[Diabetes insipidus in children--long-term follow-up study].

A follow-up study was carried out on 12 children with vasopressin sensitive diabetes insipidus. 1) Nine cases (75%) of 12 were finally diagnosed as having brain tumor in later course. There were 3 cases (25%) who could not be decided as having brain tumor during the follow-up period of more than 6 years. 2) There was one case who developed the overt signs of brain tumor 9 years after the onset of diabetes insipidus. Therefore, it seems necessary to follow-up cases with diabetes insipidus for at least 10 years before determining it as idiopathic type. 3) In cases with diabetes insipidus due to brain tumor, associated growth retardation, autonomic symptoms, behavior disorder, endocrine dysfunction and metabolic dysfunction were frequently observed. In the case where these symptoms become aggravated with lapse of time, these findings should be taken seriously as indicating brain tumor. 4) In the case showing either anterior or posterior focal slow waves in the EEG, if such focal slow waves aggravate with age, the findings should be considered as indicative of brain tumor. 5) We would like to emphasize the significance of brain tumor as the underlying pathology of childhood diabetes insipidus.

Astrocytoma↗
PubMed1977

Primary intracranial malignant lymphomas with particular reference to their pathogenesis.

During the past 6 years we have experienced a total of 6 cases of malignant lymphomas, which originated primarily in the central nervous system. The most reliable diagnostic criteria will be a "perivascular cuffing" by silver impregnation with further spreading of tumor cells to the periphery, a "starry-sky" appearance consisting of numerous histiocytes with foamy cytoplasm intermingled with tumor cells, and cytological features of the imprint preparation. Since there is a close histologic similarity to extracerebral malignant lymphomas, we would like to propose that these tumors should be regarded as primary malignant lymphomas of the central nervous system instead of mere reticulum cell sarcoma-microglioma, and also would like to regard the brain to be not an exceptional site other than visceral lymphomas for occurrences of malignant lymphomas. For the pathogenesis of primary intracranial malignant lymphomas, the hypothesis, proposed by FEIGIN, of the possible existence of multipotential stem cells in the brain was discussed.

Adult↗