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Biomedical subjects

S Toya

Publications and source records attributed to S Toya.

At least 109 records · Page 6Linked to original sources
PubMed1989

Synthesis of L-3,4-dihydroxyphenylalanine by tyrosine hydroxylase cDNA-transfected C6 cells: application for intracerebral grafting.

In the present study, we obtained genetically manipulated nonneuronal cells which synthesize a catecholamine precursor for future use in 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 immunohistochemical 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-3,4-dihydroxyphenylalanine (L-DOPA), was detected intracellularly due to the absence of L-amino acid decarboxylase (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. On 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 with an opportunity to investigate the effects of intracerebral transplantation of nonneuronal cells that produce catecholamine or its precursor.

Animals↗
PubMed1989

[Cystic pineocytoma successfully treated with synchronized chemoradiotherapy. Case report].

A case of pineocytoma associated with intraventricular and meningeal metastasis is reported. The patient, a 25-year-old female, was admitted complaining of headache. Computed tomography revealed an irregular-shaped pineal lesion enhanced by contrast medium and accompanied by a cyst. An intraventricular cystic metastatic lesion and meningeal metastasis were also suggested. Biopsy of the pineal region proved the lesion to be a pineocytoma without neuronal or glial differentiation. Ventriculoperitoneal shunting was performed, and radiation therapy combined with chemotherapy (ACNU and vincristine) was administered. This treatment apparently destroyed both the primary and metastatic lesions, and the patient returned to her normal life. In 4 years of follow-up there has been no recurrence of the tumor. Pineocytoma with meningeal metastasis usually has a poor prognosis, but in this case combined radiation therapy and chemotherapy was curative. Although pineocytoma is rarely accompanied by a cyst, in cases of a pineal lesion coexistent with a cyst, a diagnosis of pineocytoma should be considered.

Adult↗
PubMed1989

Nonfamilial turcot syndrome presenting with astrocytoma--case report.

A nonfamilial case of Turcot syndrome (glioma-polyposis syndrome) is described. A 16-year-old male with no siblings first developed a frontal astrocytoma, and was later found to have colonic polyposis with adenocarcinoma. The family history was negative for the syndrome, but his parents were first cousins.

Adenocarcinoma↗
PubMed1989

[Xenon-enhanced CT CBF measurements in intracranial vascular malformations].

In the management of intracranial vascular malformations, it is important to know the regional cerebral blood flow in its surrounding structure. However, CT scan with contrast medium and angiography have only a limited ability to estimate the rCBF. In this study, stable xenon-computerized tomography scanning by means of the end-tidal gas-sampling method was performed in eleven patients with intracranial vascular malformations. Seven of the patients had arteriovenous malformations, three had venous angiomas and one had aneurysm of the vein of Galen. In two patients with large arteriovenous malformations, in two with "larger" venous angioma and in one with aneurysm of the vein of Galen, rCBF values were significantly reduced, particularly adjacent to the malformations. In contrast, there were no areas showing reduced rCBF in cases where the malformations were small. This indicates development of ischemia correlates with the size of malformations. From the xenon-enhanced CT scan and angiographic findings, the presence of steal phenomenon with venous congestion might be a cause of rCBF reduction in those cases where ischemia exists.

Adolescent↗
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↗
PubMed1988

A modified extended middle cranial fossa approach for acoustic nerve tumors. Results of 125 operations.

During the past 10 years, 125 operations for acoustic nerve tumors were performed on 114 patients at the authors' institution using a modified extended middle cranial fossa approach. This approach is based on a combination of King and Morrison's translabyrinthine-transtentorial approach and on the extended approach through the middle cranial fossa described by Bochenek and Kukwa. There were two hospital deaths (operative mortality 1.6%). In 102 operations on the initial tumor, total removal was performed in 89 cases (87%), and in 71 (80%) of these the facial nerve was anatomically preserved. Intracranial end-to-end anastomosis was performed on five of the 18 sacrificed facial nerves; a facial-hypoglossal anastomosis was carried out in the remaining 13 patients and in five (7%) of the 71 patients whose anatomically preserved facial nerve functioned poorly. In seven (39%) of the 18 patients in whom an attempt to preserve hearing was made, postoperative hearing was saved. In 23 operations on 17 patients for recurrent tumors, most of which had previously been removed subtotally via the suboccipital approach, total removal was accomplished in 13 (57% of the 23 reoperations and 76% of the 17 patients). At reoperation, the facial nerve was preserved in six (55%) of the 11 patients in whom the facial nerve had not been sacrificed. Postoperative leakage of cerebrospinal fluid occurred in 11 cases (8.8%), with rhinorrhea in 10 cases and otorrhea in one. Five of the fistulas were corrected by surgery and the rest healed spontaneously. Other complications were not significant.

Adolescent↗
PubMed1988

A simple technique to measure regional cerebral blood flow during intravascular balloon clamping.

A case of giant internal carotid ophthalmic aneurysm was presented. In order to clarify whether the patient could tolerate carotid occlusion, a balloon clamping test was performed. before surgery. The cerebral blood flow was measured using early imaging by single photon emission computed tomography (SPECT) with N-isopropyl-(iodine-123)-p-iodoamphetamine (123I-IMP). When the balloon clamping test was performed the tracer was injected, and scanning was performed 35 minutes after removing the catheter. This tracer enabled a "memory of blood flow" during temporary ischemia to determine the character of quick diffusion and slow wash out, that could not be performed by other methods of cerebral blood flow measurement. SPECT with 123I-IMP can simplify the measurement of cerebral blood flow during the balloon clamping test.

Adult↗
PubMed1988

[A case of alpha coma in acute brainstem dysfunction--consecutive electroencephalograms and evoked potentials].

A 31-year-old woman was admitted because of severe headache and dysarthria in December 1985. Neurological examination on admission revealed severe impairment of consciousness, anisocoria, absent light reflex on the right side, and evidence of left hemiparesis, but other brainstem reflexes were intact. A CT scan taken shortly after arrival demonstrated a large hematoma in the right temporal lobe and the right cerebellum. Breathing became irregular and intubation was needed. An emergency operation was performed. After the operation the patient remained comatose without any spontaneous respiration or brainstem reflexes. The next day she was still comatose without any spontaneous movement and other neurological finding remained unchanged. An initial EEG obtained at this time showed an 8- to 9-Hz alpha rhythm of about 15-40 microV with preponderance over the posterior and central regions. Some spontaneous variability was noted. The same day, investigations of brainstem auditory evoked potential (BAEP), visual evoked potential (VEP), and somatosensory evoked potential (SEP) were performed. BAEP showed only the first, second and third waves (I-III) bilaterally. VEP was able to elicit the primary response (II-III) without the secondary response. SEP could not be obtained from the early cortical response to left median nerve stimulation, but showed N14 bilaterally and small N20 upon right median nerve stimulation. On the second day of hospitalization, a repeated EEG showed generalized slowing with loss of alpha frequency rhythms and it proved impossible for SEP to elicit N20 bilaterally. At this time, BAEP showed bilateral I-IIIth waves and VEP still showed primary response.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Intraoperative electrophysiological monitoring for hearing preservation in acoustic neurinoma surgery].

Five acoustic neurinomas have been operated with hearing preservation as a goal. We monitored intraoperative brainstem auditory evoked potentials (BAEP) in all five cases, electrocochleogram (ECoG) using needle electrode in external auditory meatus in four, and compound action potentials directly recorded from the cochlear nerve (CAP VIII) in three. In all five cases the tumor was totally resected and cochlear nerve was anatomically preserved. However, in only one case useful hearing was preserved with preservation of all wave forms of the BAEP. Another patient with preservation of all wave forms of BAEP and the ECoG showed postoperative severe hearing loss. Other three patients showed postoperative severe hearing loss: only Wave I of BAEP and ECoG were preserved without preservation of the CAP VIII in one whose cochlear nerve was thought to be damaged in cerebellopontine angle cistern; Wave I of BAEP, ECoG and CAP VIII were preserved in one in whom it was suggested cochlear nerve near brainstem or cochlear nucleus was damaged; none of the BAEP, ECoG and CAP VIII was preserved in one in whom it was suggested distal cochlear nerve, or internal auditory artery was damaged. These different patterns of changes suggested that different causes for the hearing loss and difficulties in hearing preservation during acoustic neurinoma surgery. Having identified the putative mechanism of the hearing loss by monitoring those potentials, suggestions are made about how such hearing loss might be avoided. For preservation of the hearing in acoustic neurinoma surgery, all of those potentials including all wave forms of BAEP, ECoG and CAP VIII should be preserved during surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1988

[Clinicophysiological study of multimodality evoked potentials and computed tomographic findings in persistent vegetative state].

The auditory brainstem response (ABR), short latency somatosensory evoked potential (SSEP) and visual evoked potential (VEP) of patients in the persistent vegetative state (PVS) are reported, and the correlations between the electrophysiological findings and the CT scan findings with the three clinical grades of the PVS (transitional, incomplete and complete vegetative syndromes) are discussed. Twenty two patients in a vegetative state caused by subarachnoid hemorrhage (3), hypertensive intracerebral hemorrhage (5), cerebral infarction (6), head injury (3), cerebral anoxia (4) and brain tumor (1). Each evoked response was evaluated for the presence or absence of abnormalities and assigned a grade ranked I to III. Briefly an evoked response was assigned a grade I, II, III if it satisfied the respective criteria of normal, moderately abnormal and severely abnormal or absent electrical activity. On the other hand CT scan findings in the PVS were evaluated for abnormal low density areas, ventricular dilatation and enlargement of the sulci and cisterns indicative of atrophy of the brain parenchyma. SSEP and VEP were better correlated with the clinical grade than ABR, and upper brainstem atrophy and abnormal low density area in CT scan findings were more valuable as an index to expresses the clinical features than ventricular dilatation. On the basis of these results, it is concluded that studies of ABR, SSEP and VEP associated with CT scan findings in the PVS could be a useful diagnostic aid to evaluate the lesions of these patients.

Adult↗
PubMed1988

[Folliculo-stellate cells in normal human adenohypophyses and in pituitary adenomas].

Nine normal human adenohypophyses and 155 cases of pituitary adenoma of various endocrinological types were studied for existence of folliculo-stellate cells (FSCs) by an immunohistochemical method using the antibody for S-100 (S-100 protein). In all normal materials, S-100 positive FSCs were distributed throughout the glands, constituting 0.9-4.0% of the adenohypophysial cells. FSCs were morphologically characteristic showing a few slender cytoplasmic processes which extended among the other endocrine cells. On the other hand, FSCs were recognized in 13 cases (8%) of the adenomas, which we called FSC-containing pituitary adenomas. In them, S-100 positive FSCs existed diffusely in the tissue and increased in number, but did not differ in appearance from those in the normal gland. We also examined immunoreactivity of FSCs for the anti-GFAP (glial fibrillary acidic protein) antibody. GFAP positive cells showed a greater number than S-100 positive cells in the normal glands, but a smaller number in the adenomas. Ultrastructural features of FSCs were observed in the tumor by an electron microscope. We studied clinical aspects of these FSC-containing adenomas, expecting some common features. However, we found no rules in age, sex, endocrinological type, tumor size, previous therapy, intraoperative finding of the tumor, and recurrence. So far, the function of FSC has not been clearly elucidated, and the present study did not contribute in this respect. The property of FSCs which proliferate in some adenomas is enigmatic. They may be entrapped normal cells, or reactive hyperplastic cells, or neoplastic cells. We considered them reactive hyperplastic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗