Biomedical subjects
Publications and source records attributed to S Asari.
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Computed angiotomography with intravenous minimum dose bolus injection of contrast medium permits identification of the circle of Willis and the basal cerebral veins. The normal and normal variations of these vessels in the various clinical cases are presented and described in relation to other neighbouring structures. A detailed knowledge of computed angiotomographic images of normal cerebral vessels can serve as a clinical basis for evaluating the cerebrovascular lesions.
The interesting case of the left oculomotor nerve paralysis with right hemiparesis following minor head trauma was reported in this paper. Computerized tomography showed clearly the intracranial lesions suggesting the oculomotor nerve avulsion.
Magnetic resonance (MR) characteristics of metastatic brain tumors (MBTs) were studied using 15 cases (13 males and 2 females whose ages ranged from 32-78 yr, with the mean age of 57.8 yr; 12 adenocarcinomas, 2 squamous-cell carcinomas, 2 large-cell carcinomas). Nine cases showed hypointensities and five showed isointensities on T1-weighted images. Six cases showed markedly hypo- or hypointensities, two showed isointensities, and six showed markedly hyper- or hyperintensities on T2-weighted images. One case was markedly hyperintense on both T1- and T2-weighted images. The decrease of the signal intensity on the T2-weighted image was the main MR characteristic. A hypointense peritumoral rim was seen in four of the six hyperintense tumors on T2-weighted images. There was no correlation between the signal intensity and the histological classification.
MR findings of five posterior fossa hemangioblastomas were reported. In the cystic type, a cyst was low intensity on T1WI and high intensity on T2WI. Mural nodule was clearly enhanced by Gd-DTPA. In the solid type, the tumor was shown as an isointense lesion on T1WI and as high intensity on T2WI, but it was markedly and homogeneously enhanced by Gd-DTPA. Multiple extremely low-intensity serpentine "flow void" signs, indicating afferent and efferent vessels, were observed within or around the tumor. These were characteristic pictures in this tumor.
Two cases of acute carbon monoxide poisoning are presented in this paper. Sequential magnetic resonance (MR) images of the brain showed abnormal lesions in the bilateral globus pallidus and/or in the subcortical white matter. The MR images disclosed that the severity of the white matter lesions correlated with the prognosis in acute carbon monoxide poisoning. However, they did not always correspond to the neurological condition in the acute and subacute stages.
We report the magnetic resonance features of meningiomas at the falcotentorial junction in six patients. Three tumors showed several characteristics on magnetic resonance images. They demonstrated hypo- or isointensity on T1-weighted images and iso- or hyperintensity on T2-weighted images. The degree of contrast between tumor and brain parenchyma, however, was less marked. The tumors often had a mottled appearance on T2-weighted images owing to their hypervascularity. All of the tumors had a peritumoral rim, and no edema was seen in adjacent brain parenchyma. With the injection of gadolinium, the tumors in all patients markedly enhanced; the adjacent dura was enhanced in four patients.
We evaluated the magnetic resonance images of the patients with intention tremor. Five patients out of seven had some atrophic structures or changes in signal intensity in the cerebello-rubral thalamic tract. Moreover, the T2-weighted images of the patients group detected the dentate and red nuclei more poorly than those of our control group. From these results, the etiological significance of the tract was confirmed and the mechanism of the intention tremor onset was discussed.
Polymer-encapsulated dopamine-secreting cell grafting is one of the most promising approaches for the treatment of Parkinson's disease. We microencapsulated dopamine secreting PC12 cells into agarose/poly(styrene sulfonic acid) complex and grafted them into the xenogeneic brain without immunosuppression. Dopamine secretion from the encapsulated cells was confirmed by high-performance liquid chromatography (HPLC) analysis before grafting. A large number of encapsulated PC12 cells survived in the brain 1 mo after transplantation and these cells were immunoreactive to tyrosine hydroxylase (TH) antibody, suggesting that these cells were secreting dopamine into the brain. There was no apparent immunological rejection or tumor formation. We concluded that microencapsulated PC12 cells survive in the xenogeneic brain without immunosuppression, and this grafting procedure is expected to be applied for the treatment of Parkinson's disease in the near future in combination with stereotaxic thalamotomy or pallidotomy.
A rare case of the pituitary apoplexy was presented in this paper. Computerized tomography clearly showed a blood-fluid level in the pituitary adenoma.
Three to four overlapping cerebral CT scans were obtained after the injection of a single bolus of contrast medium. The rapid sequential dynamic scanning was carried out with table increments, while there was peak iodine density in the carotid artery. The demonstration of cerebral vessel lesions (aneurysms, moyamoya disease, arteriovenous malformations, arterial narrowing, etc.) is easier and safer with this method as compared with the conventional multiple injection technique.
Twenty-seven unruptured cerebral aneurysms in 25 patients were detected by computed angiotomography. A comparison of the computed angiotomographic features in common aneurysm sites with plain CT and conventional arteriography was carried out. An isodense, round cisternal defect and a calcification or high-density mass in the basal cisterns on plain CT are important findings suggestive of unruptured aneurysms larger than 7 mm in diameter. The identification of the aneurysm, as well as of the afferent and efferent arteries on computed angiotomography is essential for the direct diagnosis of smaller unruptured aneurysms related to the circle of Willis. This is possible in a number of cases when the aneurysms are relatively large. It appears that the aneurysm size must be larger than 3 mm in diameter to permit its recognition on the basis of angiotomography and the avoidance of false-positive findings.
The magnetic resonance signal intensity and cyst content were analyzed in 2 new and 17 previously reported cases of Rathke cleft cyst. Lesions displaying hypointensity on T1-weighted images (T1WI) and hyperintensity on T2-weighted images (T2WI) contained CSF-like fluid. Cases showing hyperintensity on T1WI and isointensity on T2WI frequently contained mucoid material. Hyperintensity on both T1WI and T2WI suggests the presence of blood. A small area of hypo- or isointensity indicates thickening of the cyst wall or collection of cellular debris.
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The PC12 phenochromocytoma tumor cell line is derived from a rat adrenal medullary tumor and secretes dopamine. We have previously reported that grafted microencapsulated PC12 cells using agarose and poly (styrene sulfonic acid) survived in the xenogeneic brain without immunosuppression. To investigate whether unencapsulated PC12 cells form a tumor and how they provoke immunological reaction, PC12 cell suspension was implanted into the striatum of Sprague-Dawley rat (allogeneic graft) or guinea pig (xenogeneic graft) and histological analysis using Nissl stain and immunocytochemical analysis using antityrosine hydroxylase (TH) antibody were performed 1, 2, and 4 wk after transplantation. Host animals were not immunosuppressed. PC12 cells formed a mass 1 and 2 wk after transplantation both in allogeneic and xenogeneic brain. These grafted PC12 cells were immunoreactive to anti-TH antibody. Four weeks after transplantation, however, grafted PC12 cells in the allogeneic brain were only found within the restricted area near the site of implantation. In the xenogeneic brain, only the trace of grafted PC12 cells were found around the site of implantation 4 wk after transplantation. In both allogeneic and xenogeneic animals, a number of lymphocytes were found in and around the grafts at all period investigated. These findings indicate that PC12 cells could survive in the allogeneic or xenogeneic brain for 2 wk and were ultimately rejected by immunological reaction by 4 wk after transplantation. Implantation of encapsulated PC12 cells in the allogeneic or xenogeneic brain is considered a safe and effective method for delivering dopamine into the brain because PC12 cells will not form a tumor in the long-term even if capsules are damaged in some reason.
A radionuclide counting method, performed with the patient prone and the neck flexed, was used successfully to diagnose CSF rhinorrhea in two patients. A normal radionuclide ratio (radionuclide counts in pledget/radionuclide counts in 1-ml blood sample) was obtained in 11 normal control subjects. Significance was determined to be a ratio greater than 0.37. Use of radionuclide counting method of determining CSF rhinorrhea is recommended when other methods have failed to locate a site of leakage or when posttraumatic meningitis suggests subclinical CSF rhinorrhea.