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Biomedical subjects

O Nakai

Publications and source records attributed to O Nakai.

50 records · Page 3Linked to original sources
PubMed1988

[A case of multiple cerebral hemorrhage related to cerebral amyloid angiopathy].

A case of multiple cerebral hemorrhage in the bilateral parietal lobes related to cerebral amyloid angiopathy (CAA) is reported. A 66-year-old man was admitted to our hospital because of headache and vomiting on Feb. 21, 1983. He had no history of hypertension, diabetes mellitus, recent head injury, or dementia. Four days prior to admission, he had behaved as if he were blind, but, had denied any blindness. On examination, he was confused and disoriented. Blood pressure was 130/80 mmHg. Abnormal findings on neurological examination included memory disturbance, apraxia for dressing, right-left disorientation, finger agnosia and Balint's syndrome. A CT scan showed multiple subcortical hematomas in the bilateral parietal lobes. Intracerebral hemorrhage related to CAA was suspected. Confirmation of the presence of amyloid in the cerebral vessels was established by examination of brain biopsy specimens. The characteristics of cerebral hemorrhage related to CAA are as follow--occurrence in elderly, sometimes demented people; localization to the cortex and subcortical white matter, with direct extension into the subarachnoid space; frequent multiple occurrence in time and/or at several sites within the cerebral hemispheres; sometimes occurrence after operative procedures or head injuries. A specific diagnosis of CAA can only be made by histological examination, but the indication of brain biopsy should be carefully decided because of hemostatic difficulty and tendency to rebleed. In conclusion, CAA should be considered as a cause of hemorrhage in elderly patients who are often normotensive and demented.

Aged↗
PubMed1986

[Responsiveness of brain tumors to chemotherapeutic agents in the subrenal capsule assay].

The 6-day subrenal capsule assay was used to determine chemotherapeutic sensitivities of brain tumors. Twenty-nine brain tumors were obtained at the time of surgical resection. A minced tumor fragment (1-mm cube) was implanted under the renal capsule of 5- to 8- week-old normal female ddY mice. Each fragment was measured at two diameters using ocular micrometer unit (10 omu = 1.0 mm). The animals were randomized, usually 5 to 7 per group, and treated with anticancer drugs on day 1 through 5. On day 6, the mice were killed. The kidney was exteriorized and the tumor was again measured. The change in tumor size was obtained for each animal by ratio of the final tumor size/the initial tumor size. Sensitivities of tumors to anticancer agents were determined by comparing differences in mean values of the change in tumor size between control and treated group. Twenty-seven out of 29 specimens (93%) were submitted to evaluable assay. The response rate of 11 malignant gliomas (grade 3 and 4) was 44% and that to anticancer drugs tested were as follow: 5-FU 78%, ACNU and CPA 50%, VCR 40%, CDDP 36%. The response rate of 3 medulloblastomas was 36%: MTX 67%, CPA 50%, ACNU and CDDP 33%. That of two low-grade gliomas (grade 2) was 29%, while that of 4 malignant brain tumors (2 metastasis, chordoma, malignant fibrous histiocytoma) was 60%. Four neurinomas and 3 meningiomas were not sensitive to Tamoxifen and none were determined for estrogen receptor. In histological analysis, the transplanted tumor retained similar characteristics to the original tumor in the cases of neurinomas, meningiomas and some gliomas. Lymphocytic infiltration was observed in many cases. In the cases of metastasis (adenocarcinomas), considerable mesenchymation and lymphocytic infiltration was observed, tumor cells were reduced in number with poor preservation. Clinical response in 9 cases treated with sensitive drugs were 1 complete response, 2 partial response, 5 stable and 1 progressive disease in CT examination. The subrenal capsule assay is therefore considered to be very useful for determining suitable chemotherapeutic agents for brain tumors.

Animals↗
PubMed1982

Dynamics of contrast enhancement in delayed computed tomography of brain tumors: tissue-blood ratio and differential diagnosis.

Thirty-one patients with brain tumors were studied by delayed computed tomographic (CT) scanning performed one and two hours after intravenous administration of contrast medium. Dynamics of contrast enhancement in the lesion were analyzed quantitatively and qualitatively by calculating the tissue-blood ratio (TBR) at each scan, and are expressed as relative TBR (R-TBR). The R-TBRs obtained two hours after the first contrast-enhanced scan were found to be most useful in diagnosis, and were classified into three groups: less than 1.5 (Class I), 1.5 to 3.0 (Class II), and more than 3.0 (Class III). In the glioma group, seven of eight anaplastic gliomas were Class III and all of three anaplastic astrocytomas were Class II. All of seven meningiomas were Class I. Four of five pituitary adenomas were Class II. Three of four neurinomas were Class III. This method is potentially useful in differential diagnosis of some brain tumors.

Adenoma↗
PubMed1982

[Monitoring of the spinal cord function using evoked spinal cord potentials].

Monitoring of the spinal cord function by evoked spinal cord potentials (ESP) has come to be used widely with the establishment of a safe technique using an epidural electrode and the great improvement in medical electronic devices. According to other investigations ESP has been recorded through an electrode placed in the posterior epidural space, it is well known that residual ESP can be actually recorded after transection of the posterior half of the spinal cord and that ESP shows no change after a small transection of the anterior column. If ESP originating from the anterior half of the spinal cord is recorded, it is very useful for monitoring during anterior decompression surgery for myelopathy such as ossification of the posterior longitudinal ligament and cervical spondylosis. The purpose of this report is to analyse ESP originating from the anterior half of the spinal cord experimentally and further investigate the ESP monitoring clinically. Sixty cats were used in this study. ESP recording principally consisted of stimulation to the spinal cord at the level of thoracic or lumbar region and recording of ESP with a monopolar electrode placed in the cervical epidural space. Changes in the ESP after transection and compression of the spinal cord were analysed. Anterior vertebrectomy and laminectomy at C2 and C6 were performed for the purpose of placing an electrode correctly and facilitating transection or compression of the spinal cord. Recording electrodes were placed on both the anterior and posterior surfaces of the dura mater at C2. As the result of this study, it is apparent that there exists the ESP originating from the anterior half of the spinal cord. Such ESPs are more accurately recorded through an anterior placed electrode rather than through that placed posteriorly.

Animals↗