REGISTERED NUMBER NAME INSTITUION,DEPARTIMENT,TITLE OF POSITION

1991 Fiscal Year Final Research Report Summary

• Project/Area Number: 01480355
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: Cerebral neurosurgery
• Research Institution: OKAYAMA UNIVERSITY
• Principal Investigator: MATSUMOTO Kengo OKAYAMA UNIVERSITY,NEUROLOGICAL SURGERY,ASSISTANT, 医学部, 助手 (10190521)
• Co-Investigator(Kenkyū-buntansha): MATSUHISA Takashi OKAYAMA UNIVERSITY HOSPITAL,SENIOR RESIDENT, 医学部・附属病院, 医員 ; KUNISHIO Katsuzo OKAYAMA UNIVERSITY HOSPITAL,SENIOR RESIDENT, 医学部・附属病院, 医員 ; MISHIMA Nobuya OKAYAMA UNIVERSITY HOSPITAL,SENIOR RESIDENT, 医学部・附属病院, 医員 ; TSUNO Kazuyuki OKAYAMA UNIVERSITY HOSPITAL,SENIOR RESIDENT, 医学部・附属病院, 医員 ; FURUTA Tomohisa OKAYAMA UNIVERSITY HOSPITAL,ASSISTANT, 医学部・附属病院, 助手 (30181457)
• Project Period (FY): 1989 – 1991
• Keywords: Malignant brain tumor / Interstitial brachytherapy / Radiation necrosis / Blood-brain barrier

Research Abstract

Although some recent studies of interstitial brachytherapy of malignant brain tumors have shown good clinical results comparing conventional therapy alone, the biological data of normal brain response to this treatment modality are scarce. Therefore, we have developed a model system for interstitial irradiation using normal rat brain, and then studied the effects on normal brain tissue histologically.
Adult female SD rats were subjected to this study. With the head fixed in stereotaxic frame, a polyethylene catheter (O.D.=1.2 mm, 5 mm length) containing a pair of Ir-192 seeds or dummy seeds, was implanted in right hemisphere perpendicularly. Irradiation was performed with Ir-192 seeds of 3 mm length each with a mean activity of 0.5 mCi or 1.0 mCi, during 7-10 days, the radiation dose of 100 Gy or 200 Gy delivered to the reference point, at a 3 mm distance from the axis of the catheter, respectively. Sham treatment was performed with dummy seeds.
Animals were sacrificed at immediately, 4 and 12 weeks after irradiation. Immediately after irradiation, coagulative necrosis was observed in the region irradiated more than 400 Gy and extravasated edema fluid had spread along the corpus callosum with reactive astrocytes. Four weeks after irradiation, small calcified foci were observed in the necrotic tissue and demyelination was also observed marked in the irradiated hemisphere around the necrosis. Within 12 weeks after irradiation, the necrotic lesion was not enlarged and not seen in the area had irradiated less than 200 Gy.
In blood-brain barrier permiability study, HRP (100 mg/kg) was given intravenously 15 minutes before sacrifice. Increased permiability was most widespread at immediately after irradiation, extravascular accumulation of HRP was seen in the area had irradiated more than 50 Gy. Electron microscopy showed increased pinocytosis of the endothelium of cerebral capillary and impaired astrocytic processes.
In summary these findings suggest that after interstitial irradiation, blood-brain barrier is impaired in the region irradiated more than 50 Gy and coagulative necrosis is not obserbed in the area irradiated less than 200 Gy.