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Biomedical subjects

I Nakamura

Publications and source records attributed to I Nakamura.

At least 343 records · Page 19Linked to original sources
PubMed1981

Generation of F1 hybrid cytotoxic T lymphocytes specific for self H-2.

Cytotoxic T lymphocytes specific for self H-2 antigens are generated by murine F1 hybrid (H-2 heterozygous) spleen cells cultured with irradiated parental (H-2 homozygous) splenocytes. The effectors bind to heterozygous and homozygous cells bearing the appropriate H-2 alleles but only lyse homozygous targets. Autoreactivity for membrane-bound molecules of normal cells may be a mechanism for regulating cellular interactions.

Animals↗
PubMed1981

Absorption of protein molecules by the small intestine of the bullfrog tadpole, Rana catesbeiana.

In the tadpole of the bullfrog, Rana catesbeiana, the absorptive cells of the small intestine are characterized by the presence of invaginations of the surface plasma membrane or pinocytic vesicles in the apical cytoplasm and numerous lysosomes in the supranuclear region. These cytological features suggest that the absorptive cells may be able to ingest some macromolecules or particles. The possibility of macromolecular absorption in this animal was examined by using horseradish peroxidase (HRP) and the electron microscopic cytochemical technique. Exogenous HRP was ingested in the absorptive cells by pinocytosis and then accumulated in multivesicular bodies (MVBs) by the contribution of pinocytic vesicles to MVBs. The pinocytic vesicle changed its shape to have an inner vesicle. Some of the inner vesicles of MVBs seem to have originated from the inner vesicles of pinocytic vesicles. Almost all the MVBs in the subapical region showed HRP activity, but some of them showed no acid phosphatase (AcPase) activity; those in the supranuclear region always showed an intense AcPase activity. Therefore some of the subapical MVBs are heterophagosomes and may be joined with lysosome during the movement toward the supranuclear region. The MVBs with lysosomal enzymes in the subapical or supranuclear region are presumably important sites of intracellular digestion. The results indicate that intracellular digestion may occur in the small intestine of the bullfrog tadpole under natural conditions.

Animals↗
PubMed1981

Laterality differences in recognition of Japanese and Hangul words by monolinguals and bilinguals.

Two-character nonsense Kana words, individual Kanji words and individual Hangul words are presented tachistoscopically in the left or right visual field to 20 normal, right-handed Japanese students and 13 normal, right-handed Korean subjects. The former did not know Hangul letters. The latter were born and raised in Japan, in exclusively Japanese-speaking families, but they could read Hangul letters and write them a little because they have learned the Hangul language for 6 months. In each of three conditions (Kana, Kanji and Hangul work recognition), each subject was required to move the index finger of his right or left hand leftwards as fast as possible after the presentation of two of four stimuli and rightwards after the presentation of the other two. The reaction time was measured. A significant right field superiority for the recognition of Kana words and no lateral asymmetry for Kanji words were shown in both Japanese and Korean groups. However, for the Hangul recognition, a significant left field superiority for Japanese subjects and a significant right field superiority for Korean subjects were obtained. These findings are interpreted as follows. Kana and Kanji are processed somewhat differently in the cerebral hemispheres. Japanese subjects do not recognize Hangul stimuli as orthographic characters but as shapes or figures. Korean subjects can identify Hangul stimuli as letters. Both the first language (Kana) and second language (Hangul) are processed in the dominant left hemisphere by right-handed Korean subjects.

Adult↗
PubMed1981

Fine structure of experimental epileptogenic focus produced by intracerebral implantation of cobalt-gelatin stick in rabbits.

The experimental epileptogenic focus produced by cobalt-gelatin stick implantation in the cerebral cortex of rabbits has been studied by electron microscopy. Since our cobalt focus was latent, the bemegride maneuver was intravenously performed to identify the cobalt lesion of the cortex as an epileptogenic focus. The cobalt lesion comprised three different zones. Of the three zones, the reactive zone showed a glio-mesenchymal scar and prominent ultrastructural changes. The major change of this zone was found in the neurons, neuropils and astrocytes. Electron-lucent neurons deprived of the usual neuropils surrounding them, widening of extracellular spaces and swollen dendrites in neuropils, and proliferating astrocytes were observed constantly throughout the experimental period. These findings may be significant for the genesis of this type of epilepsy.

Animals↗
PubMed1981

Mechanism of thiamine-induced respiratory deficiency in Saccharomyces carlsbergensis.

Cells of Saccharomyces carlsbergensis 4228 grown aerobically with added thiamine (1 microgram . ml-1) in a vitamin B6-free medium contained no detectable heme precursors, such as delta-aminolevulinate, coproporphyrin III, or protoporphyrin IX. The deficiency in heme precursors in the thiamine-grown cells was accompanied by previously reported phenomena, i.e., growth depression, vitamin B6 deficiency, and respiratory deficiency due to a marked decrease in the activities of heme-containing enzymes and cytochrome level (I. Nakamura et al., FEBS Lett. 62: 354-358, 1976). It has been reported that all of the effects of thiamine are abolished by adding pyridoxine to the medium. delta-Aminolevulinate was found to have quite similar effects to those of pyridoxine, except that growth was partially improved by delta-aminolevulinate, whereas it was fully restored by pyridoxine. Incubation of the thiamine-grown cells with delta-aminolevulinate resulted in the appearance of the heme precursors and the heme-containing enzymes. Consistent with the lowered amount of vitamin B6, the thiamine-grown cells had a lowered activity of delta-aminolevulinate synthase, a pyridoxal phosphate-dependent enzyme. Not only the holoenzyme activity but also the apoenzyme activity was very low in these cells. These results indicate that the thiamine-induced vitamin B6 deficiency brings about the decrease in delta-aminolevulinate synthase activity, which leads to heme deficiency and therefore to respiratory deficiency.

5-Aminolevulinate Synthetase↗
PubMed1981

F1 hybrid-anti-parental H-2b cell-mediated lympholysis: genetic control of target antigens by the H-2D region.

The immunogenetic specificity of (C57BL/6 X DBA/2)F1 anti-parental C57BL/6 cytotoxic T lymphocytes (CTL) induced in primary mixed spleen cell cultures was determined in direct lytic and competitive inhibition assays. A large panel of peritoneal exudate cells (PEC) bearing nonrecombinant and recombinant H-2-Tla haplotypes was the source of target and inhibitor cells. All PEC of H-2b, H-2bc, H-2j, and H-2ja types, irrespective of background genetic constitution, were as susceptible to direct lysis as C57BL/6 PEC, but PEC of H-2a, H-2d, H-2k, H-2q, H-2s, and H-2u types were not. The possible involvement of the Tla region in controlling target antigens was excluded by testing PEC obtained from 4 H-2/Tla or intra-Tla recombinant mouse strains. The genes controlling target antigens were mapped to the D region with the aid of 9 intra-H-2 recombinants; for target PEC to be lysed it was necessary and sufficient that Db antigens be part of the H-2 phenotype. These results were confirmed by competitive inhibition assays. Resident peritoneal cells not exposed to fetal bovine serum were also lysed by F1 anti-parental H-2b CTL, a demonstration that target antigens are expressed on normal cells.

Animals↗
PubMed1980

The two survival cases of alpha-pattern coma caused by large amounts of hypnotica and neuroleptica.

The EEGs of two men (42 and 63 years old) in coma who took large amounts of hypnotica and neuroleptica for intended suicides were occupied by an alpha pattern, and the patients were diagnosed as alpha-pattern coma. The prominent pattern in their EEGs changed from an alpha pattern to a theta pattern, and subsequently into an alpha pattern of low amplitude. The patients recovered without any residual neurological symptoms. It has been confirmed by our two cases, as well as by other reported cases, that the outcome of the alpha-pattern coma caused by drug poisoning is favorable. It is concluded that a longitudinal EEG recording should be performed as early as possible when the patient is in a comatose state.

Adult↗