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N Shitara

Publications and source records attributed to N Shitara.

At least 19 recordsLinked to original sources
PubMed1992

Radiotherapy for pediatric brain stem glioma: radiation dose, response, and survival.

An analysis of 39 patients under 20 years of age with brain stem glioma treated with radiotherapy between 1977 and 1991 was undertaken. Twenty-eight (71.2%) of the patients responded well to initial radiotherapy, and 11 (28.8%) responded poorly. Median survival for the total patient population was 10 months. Response rates and median survivals were influenced by radiation dose: 45.5% and 9 months at doses less than 4499 cGy (n = 11), 83.3% and 13 months at doses between 4500 and 5499 cGy (n = 12), 66.7% and 11.5 months at doses between 5500 and 6499 cGy (n = 9), and 100% and 10 months at doses more than 6500 cGy (n = 7). Multivariate analysis revealed the response to initial radiotherapy was the only predictor of survival with radiation doses up to 6499 cGy. Four of the patients who responded well demonstrated radiological and/or histological calcification within or around the tumor at the time of clinical deterioration. Radiation injury was confirmed in two autopsy cases. The possibility that intratumoral radiation injury causes clinical deterioration is suggested.

Adolescent↗
PubMed1992

Leptomeningeal dissemination of cerebellar pilocytic astrocytoma. Case report.

A case of surgically treated pilocytic astrocytoma in the cerebellar vermis is reported in a patient who subsequently demonstrated multiple subarachnoid nodular masses in the cerebrum and spinal cord 6 years after the initial surgery. The nodular tumors did not indicate a growth tendency on computerized tomography or magnetic resonance imaging over a 2-year observation period. The histology of the nodular masses in the cerebrum and spinal cord was similar to that of the original tumor. The bromodeoxyuridine labeling index indicated low proliferative activity (0.5%). The peculiar pattern of dissemination of the pilocytic astrocytoma is described.

Astrocytoma↗
PubMed1992

[Inhibition of neovascularization and tumor growth by dexamethasone].

It has been proposed that angiogenesis inhibitors should be used for the treatment of diseases accompanied by an uncontrolled angiogenic response, particularly such disease occurring during progressive growth of solid tumors. In this study, the antiangiogenic effect of dexamethasone (DEX) was studied in a system using chorioallantoic membranes (CAM) of fertilized eggs and rabbit corneas. First, DEX was examined for its effect on embryonic angiogenesis using 4, 5 day old CAMs of chick embryos. After the shell and shell membrane was removed, an EV pellet with or without DEX was placed within a silicon ring. Two days later, the antiangiogenic response was evaluated by measuring the avascular zone of the CAM beneath the pellet. When the CAM showed an avascular zone of 3 mm or more in diameter, the response was scored as positive. DEX showed potent antiangiogenic activity and produced an avascular zone in 100% of CAMs at the highest dose tested. (250 ng/egg). Next, inhibitory effect of vascularization and tumor growth by local implant of DEX was observed in a rabbit cornea assay. An intra-corneal pocket extending to within 1 mm of the limbus was used to house a 1-mm3 piece of glioma. In the treatment group, DEX-containing EV pellet was inserted between the limbus and glioma. Ten days after the implantation of glioma and EV pellet, vascular response and tumor growth was evaluated. For morphologic studies, the excised corneas were fixed with formaldehyde fixative and sectioned for light microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Immunohistochemical demonstration of protein kinase C isozymes in human brain tumors.

Immunohistochemical studies of the expression of protein kinase C isozymes were done in 38 human brain tumors using monoclonal antibodies to three major isozymes: Type I, Type II, and Type III. The brain tumors, with the exception of 3 medulloblastomas and 2 of 6 pituitary adenomas, showed strong immunoreactivity for the Type III isozyme. Astrocytomas, anaplastic astrocytomas, and glioblastomas also showed weak immunostaining for Type II, whereas other tumors lacked this staining. Immunoreactivity for Type I was present, although weak, in some astrocytic gliomas. There was no correlation between the presence of immunoreactivity for protein kinase C isozymes or the intensity of staining for the Type III isozyme and the pathological grade of malignancy. In normal human brain tissue, Type I is localized mainly in neuronal cells, Type II in the neuropil of the cerebral cortex and the molecular and granular layers of the cerebellum, and Type III almost exclusively in astrocytes. The presence of immunoreactivity for the Type III isozyme in varying tumor cells, including those of non-astrocytic tumors and the presence of the Type II and/or Type I isozymes in astrocytic gliomas demonstrate that the expression of protein kinase C isozymes differs between normal and transformed cells.

Antibodies, Monoclonal↗
PubMed1990

Astrocytic localization of the immunoreactivity for protein kinase C isozyme (type III) in human brain.

The localization of 3 major types of protein kinase C (PKC) was immunohistochemically studied in human brain using monoclonal antibodies raised against each of the types. Immunoreactivity for type I was observed in neuronal cells in cerebrum and Purkinje cells in cerebellum. Immunoreactivity for type II was mainly observed in neuropil of cerebral cortex and in the molecular and granular layers of cerebellum. Occasional neurons in cerebrum were also stained. Immunoreactivity for type III was almost exclusively localized in astrocytes in gray and white matter, subpial astrocytes, and cerebellar Bergmann's glia. The present study suggests that the type III of PKC is preferentially expressed in astrocytes in human brain.

Antibodies, Monoclonal↗
PubMed1989

Chondromyxoid fibroma of the mastoid invading the occipital bone.

We describe a case of chondromyxoid fibroma of the mastoid bone extending along the occipital bone in a 48-year-old man. The presence of this tumor was heralded solely by aural fullness caused by otitis media with effusion. The tumor arose from the mastoid cavity, eroding the entire petrous portion, and invading the foramen magnum and jugular foramen. The occurrence of this tumor is exceedingly rare, and, to our knowledge, this is only the second article in the literature that describes a chondromyxoid fibroma of the mastoid region. The clinical appearance of this tumor and its light- and electron-microscopic findings are presented with reference to other articles.

Chondroma↗
PubMed1989

Clinical course and surgical prognosis of 33 cases of intracranial epidermoid tumors.

Thirty-three cases of intracranial epidermoid tumors treated during the past 25 years were analyzed with regard to clinical manifestations, recurrence rates related to the extent of surgery, and long-term survival rates. Epidermoid tumors caused various symptoms, especially in the cerebellopontine angle (15 cases), of which a transient remission of symptoms was observed in 4 cases (23.5%). The average time from initial symptoms to surgery was much shorter in suprasellar region and third ventricular locations (average of 11 months) than in other locations (average of 7 years). In 28 patients (84.9%), the tumor was removed totally or subtotally. Most of the patients could lead an independent and useful life after operation (93.1%). Among the 29 patients in a long-term follow-up survey, seven tumors recurred after an average interval of 8 years and 10 months (from the first to second operation) and 12 years and 6 months (from the second to third operation). Patients with recurrent tumors were successfully treated, and excellent functional prognosis was observed even after the second or third operation. The 20-year survival rate was 92.8% (Kaplan-Meier method).

Adolescent↗
PubMed1989

Postradiation astrocytoma. Report of two cases.

The authors describe two cases of malignant astrocytomas associated with previous radiation therapy in childhood for intracranial germinoma and craniopharyngioma. In both patients, there was no recurrence at the primary tumor site. Because of a geometric coincidence between the tumor location and the radiation field, radiotherapy was strongly implicated as a cause of these two astrocytomas.

Adolescent↗
PubMed1989

[Multimodality treatment of malignant brain tumors].

The outcome of treatment for malignant brain tumors has remarkably improved in recent years by applying multimodal therapeutic procedures. This conclusion was made by analysis of accurate data consisting 22,600 cases of completely followed brain tumor patients accumulated under the All Japan Brain Tumor Registry. The 5-years survival rates of malignant brain tumors have much improved in these 15 years, in which the most significant improvements were noticed in cases of medulloblastoma and intracranial germ cell tumors. The 5-year survival rate of medulloblastoma was improved from about 30% to more than 80%, and the number of cured patients are increasing. These favorable results are due to many factors, such as advanced imaging diagnosis of CT scan and MRI, radical surgical removal of tumors under operating microscope, and combined radiotherapy with chemotherapy. The synchronized chemoradiotherapy using vincristine and ACNU or ACNU and interferon has significantly improved the outcome of treatment for malignant gliomas. The administration of calcium entry blocker before the injection of vincristine has improved the effectiveness rates of chemoradiotherapy. Germinoma can completely be cured by chemoradiotherapy. The 5-year survival rates of germinoma have reached to 100% in female and more than 93% in male cases. The effectiveness of surgical removal, sensitivity for radiotherapy and chemotherapy were analyzed in various histological types of brain tumors and the significant effect of multimodal treatment for these tumors were discussed.

Brain Neoplasms↗
PubMed1989

[The composition of glycosphingolipids and the effect of neuraminidase on cultured glioma cell lines].

The composition of glycosphingolipid on human cultured glioma cell line U 251 and rat glioma cell line C6 was analysed by high performance thin layer chromatography. As a result, the major gangliosides were simple gangliosides such as GM3 (U 251: 7.7%, C6: 84.3%), GM2 (U 251: 32.6%) and SPG (U 251: 30.0%) on glioma cells whereas the major neutral glycosphingolipids were CDH, CTH and globoside. After treatment with neuraminidase 2.92 nmol/mg dry weight and 3.73 nmol/mg dry weight of sialic acid were freed from U 251 cells and C6 cell, but only 8.11% (U 251 cell) and 11.24% (C 6 cell) of these sialic acids originated from glycolipid, and thus the major part of sialic acid might be released from glycoprotein of the cells. The gangliosides that react to neuraminidase are SPG, GD1a and GD1b in U 251 cells and are GM1a and little GM3 in C 6 cells. The biolabelling study using N-acetyl-14C-mannosamine as a precursor of sialic acid demonstrated that the precursor was mainly incorporated into both or either of GM3 and SPG in the acidic glycolipid fraction. In addition, no significant change on proliferation and morphology of glioma cells after neuraminidase treatment was observed in this study.

Animals↗
PubMed1988

An interactive multivariate analysis of FCM data.

The procedure and results of the interactive multivariate analysis of FCM data are described. Using principal-components analysis, cluster analysis, and interactive maneuvers, this procedure facilitates an effective data compression from a four-dimensional space into two-dimensional space, then allows cluster separation. The procedure is especially effective for separating clusters, which are degenerated in the usual scattergrams. Programs were mostly written in C language on MS-DOS and were tested on four-dimensional analysis of the blood cells, which resulted in a successful separation of the degenerated clusters.

Cell Separation↗
PubMed1988

Effect of interferon-beta on the cell cycle of human glioma cell line U-251 MG: flow cytometric two-dimensional (BrdU/DNA) analysis.

This paper describes the determination of the effect of IFN-beta on U-251 MG cells using the bromodeoxyuridine (BrdU/DNA) analysis technique. The cell cycle perturbation of exponentially growing cells was estimated by a newly developed two-dimensional analysis of sequential BrdU/DNA distributions measured at 4-hr intervals after IFN-beta administration. The U-251 MG cell line was sensitive to IFN-beta, and cell proliferation was inhibited by 50.0% at 48 hr. Analysis of DNA histograms indicated that IFN-beta accumulated the cells in the S-phase, from 16 to 48 hr after treatment. In the two-dimensional analysis, labeled cells treated with IFN-beta moved from the S-phase through the G2M-phase and then entered the G1-phase within 12 hr after the initial treatment, in a pattern similar to labeled cells untreated with IFN-beta. After 16 hr, labeled cells treated with IFN-beta began to accumulate in the S-phase and remained there even after 48 hr. These results imply that IFN-beta may have an effect on the G1-phase, thereby inducing S-phase accumulation of human glioma cell line U-251 MG.

Bromodeoxyuridine↗
PubMed1988

Insulin binds to specific receptors and stimulates macromolecular synthesis in C6 glioma cells.

The existence of insulin receptors and biological responses to insulin on macromolecular synthesis have been studied in C6 glioma cells. Binding of 125I-insulin to C6 glioma cells was specific, time- and PH-dependent. Porcine insulin competed for 125I-insulin binding in a dose-dependent manner. Unlabeled polypeptides, including glucagon, bovine growth hormone, bovine prolactin did not compete for 125I-insulin binding. Scatchard analysis of the binding data gave a curvilinear plot which may indicate negative co-operativity or the existence of both high and low affinity (Ka = 7.55 x 10(10) - 4.25 x 10(9] sites. Incubation of cultures with insulin caused a time and dose-dependent stimulation of DNA, RNA and protein synthesis in C6 glioma cells (measured by 3H-thymidine, 3H-uridine or 3H-leucine incorporation into DNA, RNA, or protein respectively). The increase of macromolecular synthesis was admitted at more than 2 nM concentration of insulin. Maximal stimulation of DNA synthesis (142% of control) occurred 6 hours after incubation with 167 nM insulin. The same concentration of insulin caused a 45% increase in 1 hour on RNA synthesis, a 37% increase in 2 hour on protein synthesis. These results indicate that C6 glioma cells have specific insulin receptors capable of mediating effects of insulin on macromolecular synthesis. Insulin in the brain and even blood may be an important growth factor in the glioma cells of the patients with disrupted blood-brain-barrier.

Cells, Cultured↗
PubMed1988

Factors possibly influencing the prognosis of oligodendroglioma.

Fifty-seven cases of oligodendroglioma (including eight cases of malignant oligodendroglioma) treated at the University of Tokyo Hospital between 1961 and 1985 were analyzed for factors influencing the survival rate. Factors related to a poor outcome were findings of malignancy and symptoms of dementia. Survival rate and postoperative survival period were not influenced significantly by radiation therapy, extent of resection, tumor characteristics, or ABO blood groups.

Adolescent↗
PubMed1988

[Treatment of recurrent craniopharyngioma].

Treatment results on 48 patients with "recurrent" craniopharyngioma treated by surgery or/and radiation are analyzed. Median relapse-free survival time was 43.6 months in patients treated initially with radiation and 22.2 months without. Operative death occurred in 17% of all patients and in 3 out of six patients after total removal. The five- and ten-year survival rates were 91.7% and 66.8%, respectively, for 14 patients treated with combined surgery and radiation therapy. For 26 patients treated with surgery, the survival rates were 20.3% and 10.1%. All of 6 patients, who had received both initial and later radiotherapy, were well 1/2 to 18 years later without clinical evidence of radiation injury. These results lead us to the following conclusions: 1) A radical surgery in recurrent cases has the higher risks of mortality and morbidity than that of the first radical surgery. 2) Radiation therapy improved the survival rate of patients with "recurrent" craniopharyngioma. 3) After initial radiation therapy, additional irradiation was allowed based on the scale of nominal standard dosage and the estimation of "decay factor".

Adolescent↗