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Biomedical subjects

S Toya

Publications and source records attributed to S Toya.

At least 55 records · Page 3Linked to original sources
PubMed1995

Accumulation of nerve growth factor in cerebrospinal fluid and biological activity following neurosurgery.

Perioperative nerve growth factor (NGF) levels in cerebrospinal fluid (CSF) of patients with acoustic neurinoma (14 cases), tentorial meningioma (1 case), or subarachnoid hemorrhage (1 case) were examined. Preoperative NGF levels in CSF were below the level of detection in all patients. However, NGF was found to accumulate transiently in CSF following neurosurgery. Pre- and postoperative CSF obtained from a patient with acoustic neurinoma enhanced the proliferation of astrocytes in neuronal cell cultures derived from embryonic rat cortex grown in serum-free defined medium, and increased choline acetyltransferase activity of cholinergic neurons derived from embryonic rat septal area and brainstem. The effect of postoperative CSF on septal and brainstem neurons was more potent than that of preoperative CSF. These results indicate that NGF and non-NGF-type neurotrophic activities accumulate in the CSF following neurosurgery. These neurotrophic activities are probably important in the regeneration of damaged neural networks in the central nervous system.

Adult↗
PubMed1995

Unusual location of intracranial vagus neurinoma--case report.

A 55-year-old male presented with hearing disturbance and tinnitus in the left ear. Computed tomography (CT) and magnetic resonance imaging demonstrated a well-defined, homogeneously enhanced mass in the left cerebellomedullary cistern without extension close to the jugular foramen. A three-dimensional image reconstructed from thin-slice CT scans demonstrated that the mass was clearly separated from the jugular foramen. The mass lesion was totally removed surgically. At surgery the tumor was found to originate from one rootlet of the vagal nerve just after its exit from the medulla oblongata. The histological diagnosis was neurinoma. Intracranial neurinomas of the glossopharyngeal, vagal, or accessory nerve usually originate within or close to the jugular foramen. This unusual location made it difficult to achieve a correct preoperative diagnosis.

Cranial Nerve Neoplasms↗
PubMed1995

[Usefulness of 3-dimensional image analysis of skull base lesions].

We have evaluated three-dimensional (3D) images of the skull base lesions for planning cranial base surgery. Fifty 3D images were reconstructed from computed tomographies (CT), and/or magnetic resonance (MR) images or MR angiographic images of 30 patients with skull base lesions. These images have provided useful information for pre-operative evaluation. The 3D image reconstructed from CT provides clear information concerning the bone. Conversely, the 3D image from MR images demonstrates soft tissue very clearly, and that from MR angiography provides a detailed description of the vasculature. For skull base lesions, it is essential to evaluate 3D images from the different modalities, especially CT scan and MR image.

Adolescent↗
PubMed1995

[Transcranial magnetic stimulation of the accesory nerve--investigation of the site and mechanism of excitation in the cat].

The site where transcranial magnetic stimulation excites the accessory nerve was studied in 5 cats. Transcranial magnetic stimulation of the accessory nerve was recorded from the right trapezius. The accessory nerve was stimulated electrically at the C1 level, jugular tubercle and jugular foramen. The latencies of the compound muscle action potentials (CMAPs) for each portion were measured and compared with the magnetic response, which was coincidental with that of the jugular tubercle. The accessory nerve was then transected in steps distally from the C1 level, and CMAPs following magnetic stimulation were recorded at each step. The CMAPs disappeared following the nerve transection at the jugular tubercle. The results of both approaches in this study conclude that transcranial magnetic stimulation excites the accessory nerve at jugular tubercle. This stimulation site was anatomically coincidental with that of the facial nerve and trigeminal nerve in being right before the point where the nerve bends. Following the accessory nerve transection at the C1 level, the amputation stump was moved cranially, and CMAPs disappeared. CMAPs recorded after the accessory nerve was returned to its original position. These examinations suggested that sudden alteration of the traveling lie of the nerve participates in the mechanism of transcranial magnetic stimulation.

Accessory Nerve↗
PubMed1995

[Cooperative multicentric study on posttraumatic epilepsy].

A multicenter cooperative study was conducted to investigate factors influencing posttraumatic epilepsy (PTE) and to evaluate the prophylactic effect of anticonvulsants. A retrospective study of 102 PTE patients revealed the following typical clinical features: occurrence in young males, traffic accidents, contusion and/or cerebral hematoma. The latent period after the injury was longer in children. The percentage of EEG paroxysmal activity gradually increased as the generalized abnormality diminished. A retrospective-prospective study of 1998 patients who suffered a head injury between 1984 and 1988 was conducted till 1994. During the follow-up period, 62 patients (3.1%) developed PTE. The drop-out cases were excluded, and the 154 cases followed at least two years were analyzed. Statistical analysis of differences between patients with and without PTE suggested following factors: young, immediate early epilepsy (within 24 hours after injury; IMEE) and early epilepsy (within one week after injury). The risk with the highest relative risk rate was early epilepsy. Multiple regression analysis revealed that three factors, IMEE, early epilepsy and young age, contributed to the prediction of PTE. There was no significant difference in the percentage of patients having PTE in the group treated with anticonvulsants and the untreated group. Anticonvulsant treatment after head injury was unlikely to have a prophylactic effect on the development of PTE.

Adolescent↗
PubMed1994

GFAP transfected cells produce laminin, leading to neurite outgrowth promotion.

Accumulating evidence indicates the importance of astrocytes in neuronal development and regeneration. While glial fibrillary acidic protein (GFAP) is believed to mediate the morphology of developing astrocytes, its precise function remains unknown. To analyse the function of GFAP in astrocytes, we established GFAP-expressing cell lines by transfection of mouse GFAP cDNA into mouse fibroblast L cells. Stable transfectants expressed GFAP uniformly in the cytoplasm with no phenotypic changes and exhibited extended processes rich in GFAP. GFAP-expressing cells significantly promoted the neurite outgrowth of rat cerebral cortex neurones in the co-culture system. Analysis of the products of GFAP-expressing cells revealed an increase in production of laminin, but not fibronectin. These results suggest that L cells expressing GFAP increase laminin production, leading to promotion of neurite outgrowth.

Animals↗
PubMed1994

Peripheral myelin P0 protein mediates neurite outgrowth of cortical neurons in vitro and axonal regeneration in vivo.

Peripheral myelin P0 protein is a homophilic adhesion molecule of immunoglobulin superfamily to compact myelin structure. In addition to its roles in formation and maintenance of myelin, P0 shows neurite-outgrowth promotion activity of dorsal root ganglions. In this paper, we examined biological activity of P0 in central nervous system (CNS). Neurite outgrowth of cortical neurons of rat embryo was markedly promoted in the co-culture on C6 transformants expressing P0 protein. The neurite outgrowth was not inhibited by the P0-glycopeptide but specifically inhibited by the anti-P0 monoclonal antibody recognizing the extracellular peptide of P0. In in vivo studies, we observed significant axonal regeneration into grafts only in animals implanted with P0-expressing transformants after spinal one-third transection. These results suggest that P0 protein has promoting activity on the neurite elongation in CNS as well as in peripheral nervous system.

Animals↗
PubMed1994

Glial conditioned medium alters the expression of amyloid precursor protein in SH-SY5Y neuroblastoma cells.

The effect of conditioned medium from astroglia or microglia cultures on the mRNA expression of amyloid precursor protein (APP) in SH-SY5Y human neuroblastoma cells was examined. When incubated with conditioned medium of glial cells, SH-SY5Y cells expressed a larger amount of APP mRNA than the control cells. Reverse transcription followed by the polymerase chain reaction showed marked induction of expression of APP isoforms containing a Kunitz-type protease inhibitor domain. Our results suggest that glial cells may contribute to the regulation of expression of APP in neurons.

Amyloid beta-Protein Precursor↗
PubMed1994

Colocalization of growth hormone (GH) and glycoprotein subunit alpha in GH-producing pituitary adenomas in acromegalic patients.

Thirty-one consecutive cases of pituitary adenoma in acromegalic patients were studied by immunohistochemistry. All adenomas contained cells immunoreactive with the anti-alpha-subunit of gonadotropic hormones (alpha; 0.6-53% of tumor cells) as well as with anti-growth hormone (GH; 4-74% of tumor cells). In serial section study, most cells immunoreactive with anti-alpha were identical to cells immunoreactive with anti-GH. There was a positive correlation between the percentages of cells immunoreactive for alpha in GH cells [alpha (%)/GH(%)] and those for prolactin (PRL) in immunoreactive tumor cells (PRL(%)/[PRL(%) + GH(%)]) in mixed GH cell-PRL cell adenomas, suggesting that the alpha-subunit may play a role in emergence of PRL cells.

Acromegaly↗
PubMed1994

Middle fossa transpetrosal-transtentorial approaches for petroclival meningiomas. Selective pyramid resection and radicality.

Forty-two patients with petroclival meningioma were operated upon by the middle fossa transpetrosal-transtentorial approaches since 1977. Half of those showed tumour extension into the middle fossa and one-third in the cavernous sinus. Seventeen (40%) had a large tumour of 40 mm in diameter or larger, and 8 of those had a broad attachment from the clivus to petrous pyramid of the temporal bone. The site of pyramid resection was selected from three types, depending on the tumour location and the patients' pre-operative hearing. There was no surgical mortality. Significant risk of lower cranial nerves palsy was minimal and useful hearing was preserved in 18 out of 21 patients. The follow-up, an average of 4 and a half years, showed tumours were completely eradicated in 32 patients (76%) and there was regrowth in 3 (7%). Thirty-four patients (81%) were independent, 3 disabled and only one died of rapid tumour regrowth. The most influential factor on surgical results was the extent to which the tumour had invaded the brain stem. The presence or absence of arterial encasement and of peritumoural oedema on MRI were important in the selection for radical surgery.

Adolescent↗
PubMed1994

Mixed germ cell tumor of the basal ganglia: a case report.

A case of mixed germ cell tumor (germinoma and immature teratoma) of right cranial basal ganglia is presented. We followed the natural course for 8 months, and the change in his clinical, radiologic, and endocrinologic features was remarkable.

Adolescent↗
PubMed1994

Cell growth suppression of astrocytoma C6 cells by glial fibrillary acidic protein cDNA transfection.

The cellular functions of the intermediate filament family including glial fibrillary acidic protein (GFAP) are not well known yet beyond their roles as structural elements of cells. Expression of GFAP, which is specific in astrocytes and regulated developmentally, suggests its involvement in cell growth and differentiation of astrocytes. We transfected murine GFAP cDNA into a rat astrocytoma C6 cell line to assess the specific effect of GFAP on cells. Two stable GFAP-transfected cell lines, GFC6-5 and GFC6-6, exhibited a series of morphological and growth characteristics that distinguish them from their counterparts, i.e., NeoC6 cells transfected only with the neomycin-resistant gene, and native C6 cells. Both GFC6-5 and GFC6-6 cells showed elongated cell shapes with extended processes rich in GFAP, markedly suppressed cell growth, and decreased bromodeoxyuridine uptake. Western blot analysis revealed a remarkable increase of GFAP expression in GFC6-5 and GFC6-6 compared with that in NeoC6 and C6, in contrast to similar vimentin expression in all cell lines. The results indicate that the expression of GFAP has dramatic effects on cell morphology and cell growth suppression in C6 cells, suggesting that GFAP may function as a tumor suppressor in astrocytoma.

Animals↗
PubMed1994

Hearing preservation by the extended and nonextended middle cranial fossa approach for acoustic neuroma.

The results of 248 cases of acoustic neuroma surgery carried out mainly by the extended middle cranial fossa approach during a 16-year period from 1976 to 1991 are analyzed. Hearing preservation was attempted in 69 cases and successfully achieved in 35 (51%) cases. Hearing was preserved in 24 (57%) of 42 cases in which a tumor was 20 mm or smaller in diameter, pure-tone hearing level was 50 dB or lower, and speech discrimination score was 50% or higher. The hearing preservation rate (76%) in the cases with a tumor extending 3 mm or less from the internal auditory canal was much higher than in cases with a larger tumor. Hearing was preserved in three of seven cases with a tumor of 21 mm or larger and in two of four cases of neurofibromatosis type 2. The evaluation of postoperative hearing is also discussed.

Journal Article↗
PubMed1994

A new model for in vivo observation of the feline spinal microcirculation: the closed spinal window.

A new experimental model is described that uniquely allows the in vivo observation and quantification of vascular caliber changes on the dorsal surface of the feline spinal cord. The model consists of a rectangular Plexiglas window that is sutured to the lumbar dura and is supported by a special holder. Inlet and outlet tubes attached to the window serve for topical applications of mock cerebrospinal fluid or vasoactive agents to the surface of the cord and for continuous monitoring of intrathecal pressure. Pial vessels below the window were observed at 200-fold magnification with the aid of a microvideo camera. Spinal arterioles reacted to hypercarbia and superfusion with acetylcholine solution in a manner similar to cerebral arterioles. Tests with increased intrathecal pressure showed that the window remained watertight between 25 and 130 mm Hg, with an average leakage pressure of 57.8 +/- 33.5 mm Hg. To promote the use of this model in other laboratories, the authors give a detailed description of the closed spinal window preparation and report their experiences gained from 50 experiments. It is concluded that the closed spinal window is a highly reproducible model, suitable for the study of the feline spinal microcirculation for several hours in vivo.

Animals↗
PubMed1994

A wrapping clip combined with silastic sheet for emergent hemostasis: technical note.

The attachment of a thin silastic sheet combined with the use of Sugita's fenestrated aneurysm clip was developed for the emergency repair of vascular perforation during surgery. The sheet is flexible and tailored in the operating room, corresponds to the vascular curve, and is semitransparent, allowing observation of the area of perforation. The device can be applied under severe bleeding conditions without temporary clipping. It may be useful as an emergency tool for vascular repair in the operating room.

Adult↗
PubMed1994

[Neurophysiological study of hemifacial spasm--F wave of the facial muscles].

We studied the F wave of the facial muscles on both the normal side and the spastic side in 14 patients with hemifacial spasm. The purpose of this study was to determine if the mechanism of hemifacials spasm originates in ephaptic transmission in the facial nerve at the site of vascular compression or in a hyperexcited facial motor nucleus. Larger amplitude, longer duration and shorter latency F waves in the peripheral nerves than in normals indicate anterior horn cell hyperexcitability. We found abnormal potentials exhibiting synkinesis (lateral spread), a typical electrophysiological finding in hemifacial spasm, in the facial nerve evoked electromyograms of the 14 patients, none of whom had experienced facial palsy or facial nerve block. Electrical stimulation was delivered transcutaneously to the most distal portion of the marginal mandibular branch of the facial nerve. Using surface electrodes the F waves were obtained over the mentalis muscle as the second response after the M wave. While the F waves were normal on the patients' normal side, on the spastic side, their duration was longer (mean duration about 1.9 times that of the normal side), their onset latency was slightly shorter, and their F/M amplitude latency was greater than on the normal side. After microvascular decompression, the facial spasm and abnormal F-wave findings resolved. Onset latency was not increased, and on the spastic side some patients displayed facial spasm clinically and electrophysiologically for one year after MVD. In other words, there was hardly any focal demyelination of the facial nerve, so it is possible that ephaptic transmission and ectopic excitation are the mechanism of HFS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Molecular cloning of cDNA encoding human drebrin E and chromosomal mapping of its gene.

Drebrins are novel actin-binding proteins in the brain which are developmentally regulated. Three isoforms: two embryonic types (E1 and E2) and an adult type (A) are generated by alternative RNA splicing from a single debrin gene in the chicken brain. A full length cDNA clone of human drebrin E has been isolated from a cDNA library of human fetus brain. The clone is 2596 base pairs in length and contains an open reading frame of 1947 nucleotides encoding a protein of 649 amino acids. The deduced amino acid sequence, except for the internal 138-nucleotide sequence (ins2), exhibits 88% homology with rat drebrin A. Spot blot hybridization using flow-sorted human chromosomes provides evidence that the gene encoding human drebrin protein locates on human chromosome 5.

Amino Acid Sequence↗