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Biomedical subjects

C Ohye

Publications and source records attributed to C Ohye.

At least 55 records · Page 3Linked to original sources
PubMed1994

Visualization of dopamine nerve terminals in monkey by positron emission tomography using 4-[18F]fluoro-L-m-tyrosine.

4-[18F]Fluoro-L-m-tyrosine (FMT) is an L-Dopa analog that essentially follows the L-Dopa metabolic pathway, but without 3-O-methylation or extensive peripheral metabolism. As such, FMT may serve as a useful probe of striatal dopaminergic function with positron emission tomography (PET). FMT was synthesized, as previously described by Perlmutter et al. [Appl Radiat Isot 1990;41:801-807]. Scanning was undertaken with the SHR2000 positron tomograph (image spatial resolution, 3.5 x 4.5 x 6.5 mm). Two Macaca monkeys were anesthetized with ketamine (10 mg/kg) and pentobarbital (20 mg/kg). FMT was administered intravenously (5-6 mCi; specific activity 1-2 Ci/mmol) following carbidopa pretreatment (5 mg/kg i.v., 60 min before FMT administration). Dynamic image acquisition was done for 2 h immediately after tracer injection. This emission acquisition involved twelve 2-min frames followed by nine 4-min frames, and six 10-min images. Arterial blood samples were collected according to a schedule for assay of plasma [18F] radioactivity. Specific uptake of FMT in aromatic L-amino-acid-decarboxylase-rich areas of the monkey striatum was observed with PET imaging. The striatum-to-cerebellum ratio of the accumulation increased over time to 3.0 at 2 h. These results show the promise of FMT as a PET tracer in evaluating the CNS dopaminergic system.

Animals↗
PubMed1994

CT-oriented microrecording guided selective thalamotomy.

A further trial of CT-oriented microrecording guided stereotactic selective thalamotomy was conducted at the Centro Internacional de Restauración Neurológica, Havana City as treatment of resting tremor in 11 patients with idiopathic Parkinson's disease (PD), and in 3 other patients with intentional tremor associated with multisystemic atrophy and cerebral palsy. Three of the parkinsonian patients had undergone fetal mesencephalic tissue transplantation with significant improvement of the most debilitating symptoms of PD and stabilization of the motor state, but predominantly unilateral tremor had impaired them progressively despite increased levodopa doses. A Leksell frame was used with a novel surgical planning system and electrophysiological recordings to identify the optimal target point inside the ventralis intermedius. In all but 1 case, the tremor was totally arrested. No persistent complications were observed.

Case-Control Studies↗
PubMed1994

Neurotransplantation in Parkinson's disease: from open microsurgery to bilateral stereotactic approach: first clinical trial using microelectrode recording technique.

This paper summarizes the results of three controlled clinical trials related to the transplantation of embryonic ventral mesencephalic tissue into the striatum of 46 idiopathic parkinsonian patients exhibiting motor complications on standard levodopa therapy. From January 1988 to April 1990, 30 subjects with fluctuating Parkinson's disease received fetal dopaminergic tissue implants by the open microsurgical technique. In March 1992 the stereotactic approach was adopted for successive fetal mesencephalic cell suspension transplants (7 unilateral and 9 bilateral) into the caudate and putamen of parkinsonian patients with levodopa-induced complex fluctuations and dyskinesias. The neurological assessment performed 12 months before and 3-18 months after transplantation demonstrated a reduction of both the daily time spent in the 'off' condition and the number of daily 'off' periods, and a significant improvement of the motor scale. The stereotactic selective thalamotomy with microelectrode recording was introduced in January 1993, in order to provide a further potential treatment strategy; i.e., the combination of the two surgical trends in Parkinson's disease, the restorative neurotransplantation technique, and the selective lesional approach. In addition to that, microelectrode recording is also used for implantation site selection and functional characterization.

Adrenal Medulla↗
PubMed1994

Pathophysiology of central (thalamic) pain: combined change of sensory thalamus with cerebral cortex around central sulcus.

In 13 patients with central (thalamic) pain after stroke, CT, MRI, PET scan and intraoperative thalamic microrecordings were performed. Electrophysiological studies showed that irregular burst discharges were often encountered in the posterolateral thalamus. The more often the irregular burst discharges were encountered, the greater the decrease of sensory response in the posterolateral thalamus. Metabolic studies showed that regional cerebral glucose metabolism decreased in both the posterolateral thalamus and in the cortical postcentral area on the lesioned side in all cases. In the thalamic lesion cases in which many irregular burst discharges were found in the posterolateral thalamus, regional cerebral glucose metabolism and the relative value of glucose to oxygen metabolism increased in the cortical precentral area on the lesioned side. It was suggested that decreased activity with abnormal burst discharge in the posterolateral (sensory) thalamus associated with changes in cortical activity adjacent to the central sulcus might be related to the genesis of central (thalamic) pain. It is emphasized that cortical activity decreased in the postcentral area, but often increased in the precentral area.

Brain Diseases↗
PubMed1994

Use of a frameless isocentric stereotactic system (NEURO-SAT) combined with the intraoperative microrecording.

Combining the frameless isocentric stereotactic system (NEURO-SAT) and intraoperative microrecording, we performed stereotactic biopsies of deep-seated brain tumors in two cases. Case 1 was a 58-year-old male suffering from a right thalamus to basal ganglia tumor and case 2 was a 29-year-old male suffering from brain stem tumor. In both cases, the border between the tumor and the normal tissue was ambiguous on neuroimagings. NEURO-SAT provides three-dimensional real-time surgical navigation by displaying the positional information on the MRI images, and intraoperative microrecording shows a clear delineation between the tumor and the normal tissue in both cases. Therefore, since this combined method provides real-time surgical navigation and clear delineation of the tumor and normal tissue, it is a promising method of accurate and reliable image-directed stereotactic biopsy of deep-seated brain tumor.

Adult↗
PubMed1994

Neurobiologic effects of radiosurgery: histologic, immunohistochemical and electron-microscopic studies of a rat model.

Spinal cords of rats were irradiated with a single fraction of 14-36 Gy (group A) or 55 Gy (group B) and examined by light and electron microscopy. Degeneration and reduced numbers of motor neurons were found even at an early stage in group B animals. Necrosis in the spinal cord was found at a later stage. The ultrastructure of vessels around areas of necrosis showed degeneration of pericytes and vacuolar changes of vascular walls. This study indicates that single, high-dose irradiation causes direct effects on neurons at early stages and degeneration of vascular walls followed by necrosis at a later stage.

Animals↗
PubMed1993

The possible role of the cerebral cortex adjacent to the central sulcus for the genesis of central (thalamic) pain--a metabolic study.

In nine patients with central (thalamic) pain after stroke, X-CT, MRI, PET scan and intraoperative thalamic microrecordings were performed. The PET studies made use of Sokoloff's method with 18FDG and a steady-state method with C15O2-15O2. CT scan and MRI revealed definite thalamic damage (Th) in 3 cases, putaminal damage (Put) in 3 cases, combined damage (Th + Put) in one case, and cortical (parietal) damage in 2 cases. In patients with a subcortical lesion, the greater the severity of superficial pain, the higher was the relative value of regional cerebral glucose metabolism (rCMRGlu) as compared to oxygen metabolism (rCMRO2) in the cerebral cortex around the central sulcus on the damaged side. Also, in a case with combined (Th + Put) lesion, regional oxygen extraction ratio (rOEF) was increased in this area. Moreover, in another case, central pain disappeared after a small subcortical haemorrhage in the same structure. In all patients including those with a cortical lesion, rCMRGlu was decreased in the postero-lateral (sensory) thalamus on the invalued side. The possible role of the cerebral cortex around the central sulcus for the genesis of central pain is discussed.

Adult↗
PubMed1993

Delayed brain hemorrhage associated with prophylactic whole brain irradiation for pediatric malignant brain tumor: a case report.

Intraparenchymal hemorrhage in the left frontal lobe suddenly occurred in a 7-year-old girl who had undergone partial removal of an undifferentiated brain stem glioma and received craniospinal (30 Gy) and posterior fossa booster (20 Gy) irradiation at the age of 20 months. The brain hemorrhage was thought to be delayed irradiation effect. Follow-up neuro-imaging at age 9 years showed two more small occult chronic and subacute hemorrhages in the brain. The possibility of repeated hemorrhage as a delayed reaction to brain irradiation is emphasized.

Brain Neoplasms↗
PubMed1993

General activation of cerebral metabolism with speech: a PET study.

We report the pattern of metabolic activation of the brain associated with speech, using 15O positron emission tomography (PET) in normal volunteers, as well as patients with or without language deficit. 15 trials were performed on 13 subjects. Regional oxygen metabolism with the subjects at rest was compared to that during a speech-from-memory task. As expected, there was strong activation of Broca's area and the medial left temporal lobe, corresponding to the motor speech and memory aspects of the task. In addition, both cerebellar hemispheres and pre-motor areas, as well as the right frontal operculum, supplementary motor area and right parietal lobe were active. This technique provided insight into the mechanism of aphasia in two subjects, even in one whose traditional language areas were structurally and metabolically intact at rest. We conclude that this practical activation technique may be useful not only in studying the physiology of normal brain, but also in understanding functional responses to disease.

Adolescent↗
PubMed1993

Tremor-mediating thalamic zone studied in humans and in monkeys.

The thalamic zone mediating the rhythmic burst activity related to the contralateral tremor was studied by microelectrodes in clinical cases with tremor and in monkeys with experimental tremor. The rhythmic burst time-locked with the tremor was found in a restricted area of the ventrointermedius nucleus (Vim) in humans and also in VPLo nucleus in monkeys. In both cases, only the lateral and ventrocaudal part of each nucleus, which was defined as the kinesthetic zone, was involved. A possible tremor-mediating neural circuit is postulated.

Animals↗
PubMed1993

Long-term clinical effects of radiation therapy for primitive gliomas and medulloblastomas: a role for radiosurgery.

The effect of conventional irradiation on primitive gliomas and medulloblastomas was examined for 21 patients and a role for radiosurgery was evaluated. Five patients survived more than 8 years after treatment. However, side effects were recognized not only on neuronal and hormonal functions but also on neurovascular structures in the developing brain. The remaining patients died due to tumor recurrence, dissemination and/or metastases. Although these tumors were radioresponsive, conventional irradiation was inadequate in more than half the cases. A role for Gamma Knife radiosurgery should be considered, especially for young children and recurrences. Radiosurgery could also conceivably contribute to the prevention of tumor dissemination. In all events a multidisciplinary treatment should be considered.

Adolescent↗
PubMed1993

Pathological anatomy of autopsy brain with malignant glioma.

The morphology of supratentorial malignant glioma was examined in autopsy brains from three anaplastic astrocytoma and 11 glioblastoma multiforme patients. Large histological preparations and routine preparations were used to investigate the primary lesion site, infiltration to adjacent brain, and cerebrospinal fluid (CSF) dissemination. The primary lesion sites showed active tumor growth with mass effect in three cases, necrotic tumor and brain with no or mild mass effect in nine, and no residual tumor in two. Tumor infiltration included extensive bilateral cerebral hemisphere infiltration in seven cases, moderate infiltration of one or two lobes in three, minimal infiltration just beyond the tumor bed in two, and no infiltration in two. Infiltration occurred along the fiber tract and subependymal tissue. CSF tumor cell dissemination occurred in the ventricular system in two cases, cerebral subarachnoid space in five, and spinal subarachnoid space in one. Small fibrillated cells and small anaplastic cells predominated in infiltrated lesions and CSF dissemination.

Adult↗
PubMed1993

Clinical evaluation of thallium-201 SPECT in supratentorial gliomas: relationship to histologic grade, prognosis and proliferative activities.

We performed 201Tl SPECT and cell kinetic studies on 28 presurgical patients with supratentorial gliomas by administering bromodeoxyuridine (BUdR). All patients had surgery and had follow-up for more than 25 mo. In patients with grade IV glioma (198.1% +/- 32.8%, n = 10), the 201Tl index, expressed as the count rate of the tumor site to the count rate over the contralateral normal region, was significantly higher than that in patients with grade III glioma (140.5% +/- 15.1%, n = 4, p < 0.01) or low-grade glioma (104.1% +/- 22.6%, n = 14, p < 0.001). A significant correlation was observed between the 201Tl index and BUdR-positive cells in excised tumor specimens (r = 0.67, p < 0.001). The 201Tl index of the 12 patients who died was higher than those who survived (173.2% versus 122.4%, p < 0.01). These results show the clinical utility of 201Tl brain SPECT in imaging supratentorial glioma and that the 201Tl index is representative of proliferative activity of the tumor.

Adult↗
PubMed1992

Application of magnetic resonance imaging in functional stereotactic thalamotomy for the evaluation of individual variations of the thalamus.

An application of MRI in functional stereotactic thalamotomy is presented. To estimate the individual anatomic variations of the thalamus prior to stereotactic thalamotomy, a special study using a proton density image that shows myeloarchitectonic features of the thalamus was performed. The proton density MRI was demonstrated to be very useful to determine the safest trajectory and tentative target point. However, as a detailed functional localization of the thalamic subnuclei cannot be yet obtained by MRI, the final target should be decided on the basis of electrophysiological findings.

Adult↗