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Biomedical subjects

S Kohsaka

Publications and source records attributed to S Kohsaka.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Current advances in neural transplantation].

In the present study, we obtained genetically manipulated non-neuronal cells which synthesize a catecholamine precursor for future use in the intracerebral grafting. Human type 1 tyrosine hydroxylase (TH, EC 1. 14. 16. 2) cDNA was inserted into eukaryotic expression vector pKCRH2 and was co-transfected into C6 cells with plasmid pSV2neo. Expression of the TH minigene was screened by immunocytochemical staining with TH antibody and immunoblotting analysis. Several clones of the C6 transfectants that produce TH molecules were obtained. These cells showed TH activity and the product, L-DOPA, was detected intracellularly due to the absence of L-amino acid decarboxylase (AADC, EC 4. 1. 1. 28) activity. It was found that a large amount of L-DOPA was released from the cells into the culture medium. These transfectants were transplanted into rat brain and the expression of TH was examined immunohistochemically. At the 10th day following transplantation, a mass of C6 cells which was heavily stained with TH antibody was observed in the brain. These findings may provide us an opportunity to investigate the effects of intracerebral transplantation of non-neuronal cells that produce catecholamine or its precursor.

Animals↗
PubMed1989

[Morphological and immunohistochemical studies on degenerative changes of the retina and the optic nerve in neonatal rats injected with monosodium-L-glutamate].

Degenerative changes in the retina and the optic nerve were investigated morphologically and immunohistochemically following administration of monosodium-L-glutamate (MSG) in rats. MSG (5mg/g b.w.) was injected subcutaneously every other day for 5 times after birth. The retina and the optic disc was observed ophthalmoscopically at 1, 3 and 6 months after birth. At the same stage, morphological and immunohistochemical changes were also investigated under light microscopy. The neuron of the retinal ganglion cell was identified immunohistochemically with antiserum to neurofilament 200 kD (NF). Glial cells were stained with antisera to glial fibrillary acidic protein (GFAP) and S-100 beta protein, and myelin of oligodendrocytes was also stained with antiserum to myelin basic protein (MBP). Histologically the inner layer of the retina was selectively destroyed, and the optic nerve also showed degeneration, changing into a thin strand. The retinal vessels were narrow and coarse, however, they extended to the peripheral region. Although immunohistochemical staining with NF antiserum was scarcely detected both in the retina and in the optic nerve, glial stainings with GFAP and S-100 beta protein antisera were widely observed in the perivascular space of the retina and in the glial column of the optic nerve. These findings indicated that the ganglion cells and their neurons are significantly affected by MSG, but the retinal vessels and glial cells are rarely affected. Ophthalmoscopically, the optic discs of rats treated with MSG were small and deeply excavated. The vitreous vessels persisted in most cases even at 6th months after birth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Experimental studies on microphthalmos formation in neonatal rats treated with monosodium-L-glutamate].

Changes in the eyeball size were investigated in rats treated with monosodium glutamate (MSG) during the neonatal period. Correlations among ocular size and degenerative changes of the retina and optic nerve were also studied ophthalmoscopically and histologically. Rats received MSG 5 times, 2 times or once. In rats which received MSG 5 times, the administration was made at 1, 3, 5, 7 and 9 days of birth. In rats, which received MSG 2 times, the administration was made on 2 subsequent days (1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10, 12 and 13 or 15 and 16 postnatal days). In the group of rats, which received MSG once, the administration was made on each from the 1st to the 15th postnatal day. Microphthalmos formation was clearly observed only in rats with 5 times and 2 times (9 and 10 days) injection of MSG. In these rats, narrowing of retinal vessels, paleness and excavation of optic disks were observed ophthalmoscopically. Total liquefaction of the vitreous body were seen in the same groups. Histological examinations also revealed degeneration of the inner layers of the retina. These findings indicated that the administration of MSG at critical stages during postnatal development induces disturbances of eyeball growth. It was also suggested that the growth of the eyeball is closely associated with the postnatal development of the retina.

Animals↗
PubMed1989

[Morphological studies on cataract and small lens formation in neonatal rats treated with monosodium-L-glutamate].

Changes in the transparency and size of lenses in rats were investigated following administration of monosodium-L-glutamate (MSG), MSG (5 mg/g b.w.) was injected subcutaneously on the 9th and 10th days after birth. Morphological changes of the lenses were examined ophthalmoscopically and histologically. Ophthalmoscopically, localized opacity was apparent at the posterior pole of the lens corresponding to the attached portion of hyaloid artery at 1 months of age. The incidence of cataract increased with age, reaching more than 75% at 4 months of age. Morgagni's globules were histologically detected in the opacity of the posterior lens cortex. Degenerative changes of the lens epithelium were observed in the mature cataract. However, the capsules of the lens were well preserved. The size and weight of the lens were smaller than those of controls. Although the pathogenesis of the cataract and small lenses are not clear at the moment, these findings indicate that administration of MSG could be an etiologic factor in cataract formation in the developing rat.

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PubMed1988

Immunohistochemical studies on the proliferation of reactive astrocytes and the expression of cytoskeletal proteins following brain injury in rats.

The appearance of reactive astrocytes following brain injury was investigated in 4-week-old rats with special reference to their proliferation and chronological changes in the cytoskeletal proteins. Two days after the injury, glial fibrillary acidic protein (GFAP)-positive cells had increased in number around the lesion and spread to the entire ipsilateral cortex by 3 days after the injury. To investigate the distribution of mitotic cells and its chronological change, immunohistochemical staining with monoclonal antibody to bromodeoxyuridine (BrdU) was performed. BrdU-positive cells began to appear around the lesion and spread to the entire ipsilateral cortex by 3 days and their distribution was the same as that of GFAP-positive cells. To investigate the association of GFAP-positive cells with cell division, double labeling experiments using [3H]thymidine autoradiography and immunohistochemical staining with antiserum to GFAP were performed. Cells doubly labeled with GFAP and [3H]thymidine were localized in the area adjacent to the lesion, in the molecular layer of the cortex and in the white matter. By contrast, none of the cells were doubly labeled in the IInd to VIth layers of the cortex. Furthermore, only astrocytes in the former areas expressed vimentin transiently from 2 to 10 days after the injury. In the rats administered vincristine, cells arrested during mitosis were found in the regions which express vimentin. From these results, it was suggested that astrocytes in the molecular layer of the cortex and the white matter adjacent to the lesion proliferated in response to the injury and expressed vimentin transiently, then acquired GFAP, and that astrocytes in the IInd to VIth layers of the cortex became reactive astrocytes without mitosis.

Animals↗
PubMed1988

Possible synapse formation by embryonic cerebellar tissue grafted into the cerebellum of the weaver mutant mouse.

The weaver mutant mouse is characterized by degeneration of cerebellar granule cells in early post-natal stage. In the present study, the possibility of synapse formation in the weaver mouse cerebellum by implanted granule cells was analyzed immunohistochemically with antiserum against synaptic vesicle protein, Synapsin I. Normal cerebellar tissue, obtained from 15-day-old CBA/JNCij mouse embryos, was transplanted into the cerebellum of 4-week-old weaver mice. 6 weeks after the transplantation, the grafted tissue was clearly detected in the host cerebellum, developing a trilaminar organization. A number of granule-like cells were observed in the folia of the host cerebellum, suggesting that the implanted granule cells may have migrated from the grafted tissue into the host cerebellum. Some areas in the host cerebellum as well as in the grafted tissue were intensely stained by anti-Synapsin I serum, indicating that the implanted granule cells make synaptic contacts with the neuronal cells.

Animals↗
PubMed1988

Reorganization of cerebellar cell suspension transplanted into the weaver mutant cerebellum and immunohistochemical detection of synaptic formation.

Dissociated cells prepared from the cerebellar primordia of normal 15-day mouse embryos were grafted into the cerebellum of 1-month-old weaver mutant mice which are characterized by degeneration of cerebellar granule cells during the early postnatal period. The growth of the grafted cells was investigated at 1 month after the operation. Implanted cells were highly developed to form a large mass of tissue in the host cerebellar folia. Histological examination revealed that a trilaminar cortical structure was partially developed in certain areas of the grafted tissue. The implanted granule-like cells were labeled with [3H]thymidine which was injected into the host, suggesting that the granule-like cells actively proliferate in the host cerebellum after the transplantation. In this area, strong immunoreactivity with synapsin I was detected indicating that the dissociated granule cells of the cerebellar primordia are able to develop a synaptic organization in the weaver mouse cerebellum.

Animals↗
PubMed1987

Immunohistochemical studies on synapse formation by embryonic cerebellar tissue transplanted into the cerebellum of the weaver mutant mouse.

Normal cerebellar tissue, obtained from 15-day-old CBA/JNCij mouse embryos, was transplanted into the cerebellum of 4-week-old weaver mice. At the 6th week after the transplantation, the grafted tissue was distinguishable from the host cerebellum, developing a trilaminar organization. The formation of synapses by the implanted granule cells was analyzed immunohistochemically with antiserum against synaptic vesicle protein, Synapsin I. Some areas in the host cerebellum as well as in the grafted tissue were intensely stained by anti-Synapsin I serum, suggesting that the implanted granule cells make synaptic contacts with the neuronal cells.

Animals↗
PubMed1986

Subcultured astrocytes suppress the proliferation of neuroblasts in vitro.

The effects of subcultured astrocytes on the proliferation of neuronal precursor cells (neuroblasts) from rat embryonic cerebral hemispheres were examined. The survivability of neurons and the neurite outgrowth were significantly enhanced by the subcultured astrocytes compared to those of neurons plated on poly-L-lysine-coated coverslips. The incorporation of [3H]thymidine into neuroblasts was remarkably suppressed by the subcultured astrocytes indicating that the astrocytes inhibit the proliferation of neuroblasts. These results suggest that astrocytes enhance the maturation of neuroblasts possibly via either cell-cell contact or trophic substances.

Animals↗
PubMed1986

Possible association of platelet-derived growth factor (PDGF) with the appearance of reactive astrocytes following brain injury in situ.

The association of platelet-derived growth factor (PDGF) with the appearance of reactive astrocytes following injury was investigated by using a specific antagonist of PDGF, Trapidil. The cerebral cortex of 4-week-old male rats was unilaterally injured with a 22-gauge needle. Immunohistochemical staining with antiserum to glial fibrillary acidic protein revealed that reactive astrocytes had increased in number around the wound by 2 days following the injury and had spread to the ipsilateral areas distant from the wound by 3 days. The appearance of reactive astrocytes in areas distant from the wound was dramatically suppressed by the administration of Trapidil. This finding indicates that PDGF might play a role in gliosis following injury.

Animals↗
PubMed1986

Septal deafferentation enhances the neurotrophic effects of rat hippocampus on cultured neural cells from the central nervous system.

Neurotrophic effects (NTEs) of various brain regions of 4-week-old rats were examined in primary culture of rat embryonic cerebral hemispheres. Extracts of the hippocampus, brainstem and septal nucleus highly enhanced the survivability of neuronal cells and the division of non-neuronal cells by 9 days. The septohippocampal tract (fimbria fornix) was cut and the effect on the neurotrophic activity in the hippocampus was examined. The NTEs of hippocampal extracts remained unchanged 3 days after septal deafferentation, was significantly increased by 7 days, peaked at 14 days and returned to the basal level by 21 days.

Animals↗
PubMed1986

Transplantation of bulk-separated oligodendrocytes into the brains of shiverer mutant mice: immunohistochemical and electron microscopic studies on the myelination.

Normal oligodendrocytes were separated from 7-day-old mouse (BALB/c) brains by the Percoll gradient method. Immunohistochemical staining with an anti-galactocerebroside serum revealed that about 85% of the separated cells were oligodendrocytes. The oligodendrocytes were transplanted into the corpus striatum of 4-week-old shiverer mutant mice which are characterized by the lack of myelin basic protein (MBP). Myelination by the implanted oligodendrocytes was investigated immunohistochemically and electron microscopically 6 weeks after the operation. Certain areas in the corpus striatum were intensely stained with antiserum to MBP. Electron microscopic examination showed that some axons were surrounded by normal type myelin sheaths with major dense lines. These results clearly indicate that matured oligodendrocytes are able to survive and myelinate the host axons even in the adult brain.

Animals↗
PubMed1986

The effect of arcuate nucleus transplantation on the development of the anterior pituitary in monosodium glutamate-treated rats.

Treatment with monosodium glutamate (MSG) during the neonatal period is known to produce a selective lesion of the arcuate nucleus in rat brain, which is the major site of production of growth hormone releasing-hormone (GRH), followed by a secondary reduction in growth hormone (GH) synthesis in the anterior pituitary. Normal arcuate nuclei from hypothalamic areas of newborn rats were transplanted into the third ventricles of 27-day-old rats which were treated with MSG on alternate days for the first 10 days of life. Ninety days after birth, the anterior pituitaries were examined for GH synthesis by immunohistochemical staining with GH antiserum. The results indicated that the impaired GH synthesis in the anterior pituitary treated with MSG was partially restored in some recipients by grafts of arcuate nuclei in which the GRH-containing neurons were clearly detected by immunohistochemical staining with GRH antiserum.

Animals↗
PubMed1986

Production of monoclonal antibody to 2',3'-cyclic nucleotide 3'-phosphodiesterase from bovine cerebral white matter.

Lewis rats were immunized with partially purified 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) from bovine cerebral white matter and the spleen cells were fused with cell of a mouse myeloma cell line (SP-2). The production of monoclonal antibody was detected by enzyme-linked immunoadsorbent assay, immunohistochemical staining of bovine cerebrum, Western blotting analysis, and CNPase binding assay. Monoclonal antibody that specifically binds CNPase molecules was obtained. However, the antibody did not suppress the enzyme activity. Western blotting analysis demonstrated that the monoclonal antibody binds both CNa (Wla) and CNb (Wlb). The monoclonal antibody was identified as being of the IgG2c subclass. Immunohistochemical examination revealed that the myelin sheath in the CNS was heavily stained with the monoclonal antibody in several species (bovine, mouse, rat, and human). In contrast, peripheral nervous system myelin was not stained even in bovine tissue. These results suggest that the monoclonal antibody obtained in the present study specifically recognizes the CNPase molecules in the CNS.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗