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Biomedical subjects

C Ohye

Publications and source records attributed to C Ohye.

At least 19 recordsLinked to original sources
PubMed1997

Basal interhemispheric supra- and/or infrachiasmal approaches via superomedial orbitotomy for hypothalamic lesions: preservation of hypothalamo-pituitary functions in combination treatment with radiosurgery.

Although several approaches to the hypothalamus have been used, none is able to give full views of the hypothalamus. The risk of permanent morbidity for hypothalamo-pituitary functions is still high, especially in patients with craniopharyngioma. Basal interhemispheric supra-chiasmal or infra-chiasmal approaches via superomedial orbitotomy were developed for better visualization of the hypothalamus. Operative techniques and results, including combination treatment with radiosurgery, are reported. Twelve patients with tumors compressing the hypothalamus upward or extending into the III ventricle, or both, were operated on: 3 tumors were removed totally, 6 tumors subtotally and 3 tumors partially. Six patients received radiosurgery for residual tumor. Four patients with hypopituitarism preoperatively required oral corticosteroids and thyroid hormones postoperatively. The basal interhemispheric approach via superomedial orbitotomy is useful for better visualization of the hypothalamus and preservation of hypothalamo-pituitary functions.

Adenoma↗
PubMed1997

Single-unit activity in the primate nucleus tegmenti pedunculopontinus related to voluntary arm movement.

In the pedunculopontine tegmental nucleus (PPN), single-unit activity was recorded in two monkeys trained to manipulate an on-off lever with a hand. Among 280 neurons recorded, a change in the firing rate related to the lever-off movement was observed in 125 neurons for the contralateral limb movement (53%) and in 96 neurons for the ipsilateral limb movement (48%). The changes were an increase in the firing rate in 122 neurons and a decrease in 99 neurons. These changes in the firing rate related to the task often occurred for both the contralateral and ipsilateral limb movements. The change of activity preceded the movement onset for both contralateral and ipsilateral arm movements. These findings suggest that in primates the PPN contributes to coordination of upper limb movements on both sides.

Animals↗
PubMed1996

Gamma knife for glioma: selection factors and survival.

PURPOSE: To determine factors associated with survival differences in patients treated with radiosurgery for glioma. METHODS AND MATERIALS: We analyzed 189 patients treated with Gamma Knife radiosurgery for primary or recurrent glioma World Health Organization (WHO) Grades 1-4. RESULTS CONCLUSION: The median minimum tumor dose was 16 Gy (8-30 Gy) and the median tumor volume was 5.9 cc (1.3-52 cc). Brachytherapy selection criteria were satisfied in 65% of patients. Median follow-up of all surviving patients was 65 weeks after radiosurgery. For primary glioblastoma patients, median survival from the date of pathologic diagnosis was 86 weeks if brachytherapy criteria were satisfied and 40 weeks if they were not (p = 0.01), indicating that selection factors strongly influence survival. Multivariate analysis showed that increased survival was associated with five variables: lower pathologic grade, younger age, increased Karnofsky performance status (KPS), smaller tumor volume, and unifocal tumor. Survival was not found to be significantly related to radiosurgical technical parameters (dose, number of isocenters, prescription isodose percent, inhomogeneity) or extent of preradiosurgery surgery. We developed a hazard ratio model that is independent of the technical details of radiosurgery and applied it to reported radiosurgery and brachytherapy series, demonstrating a significant correlation between survival and hazard ratio. CONCLUSIONS: Survival after radiosurgery for glioma is strongly related to five selection variables. Much of the variation in survival reported in previous series can be attributed to differences in distributions of these variables. These variables should be considered in selecting patients for radiosurgery and in the design of future studies.

Adolescent↗
PubMed1996

Radiobiological effects of gamma knife radiosurgery on brain tumors studied in autopsy and surgical specimens.

To elucidate the radiobiological effect of Gamma Knife radiosurgery on brain tumors, we performed a histological study on nine cases. In two, the material was obtained at autopsy and in seven following surgery. In the central region of the radiation field, destructive changes occurred both in tumor cells and in vessels. In the peripheral area, destructive and proliferative vascular changes were intermingled with residual tumor tissue. Immunohistochemical staining of surgical specimens showed that the vascular proliferative changes consisted of pericytic proliferation with or without endothelial proliferation. These characteristic changes might suppress tumor growth, at least in the short-term.

Adolescent↗
PubMed1996

Lesion size following Gamma Knife treatment for functional disorders.

In this study we investigated the reproducibility and consistency of the size of radiosurgical lesions produced for functional disorders. The T1 gadolinium-enhanced magnetic resonance (MR) images of 56 patients treated for parkinsonism, pain, or other functional diseases were used to measure 140 lesion sizes at various times after radiosurgical treatment (1-26 months, mean: 11.3 months). Only the 4-mm collimator was used to create the lesions. The maximum dose ranged from 110 to 180 Gy (mean: 145 Gy). In 42 cases (78%), one isocenter was used to create the lesion. Thirteen lesions (20%) were created with two isocenters and in 1 case, three isocenters were used. Lesions were detectable on MR images as early as 30 days after treatment. The maximum lesion volume was reached after 6-12 months and ranged from nondetectable to more than 4,000 mm3. Larger lesion volumes were strongly associated with the use of more than one isocenter. In addition, maximum doses of 160 Gy or more increased the likelihood of producing lesions larger than expected. It is therefore concluded that the use of the Gamma Knife for the treatment of functional disorders is safest when single-isocenter shots with the 4-mm collimator and a maximum dose of less than 160 Gy are used.

Adult↗
PubMed1996

Gamma thalamotomy for parkinsonian and other kinds of tremor.

On the basis of our experiences with selective ventralis intermedius thalamotomy with microrecording, certain cases of tremor with Parkinson's disease (PD, six cases), intentional tremor (one case) and essential tremor (one case) were treated by Gamma Knife. In all cases, 140-150 Gy were irradiated using 4-mm collimators. Three different strategies were used. (1) Gamma thalamotomy as the primary surgical treatment. (2) As a secondary treatment, irradiation of the symmetric point of the contralateral selective thalamotomy. (3) Extension of the previous thalamotomy. For the first three cases (all PD), a special plug pattern (100 plugs) was used, but was not employed for the later cases. No acute untoward effects were noted, and overall there appeared to be a reduction in tremor. The time course of tremor reduction varied from case to case, from about 5-6 months to 1 year.

Adult↗
PubMed1996

Gamma Knife radiosurgery for acoustic schwannoma: effects of low radiation dose and functional prognosis.

The effects of relatively low dose Gamma Knife irradiation on acoustic schwannoma were evaluated in 29 patients followed over 2 years after treatment. The mean dose delivered to the tumor periphery was 12.1 Gy. Lowering of the magnetic resonance signal intensity in the tumor center appeared in 69% and signs of tumor shrinkage appeared in 59% of cases. The cyst in the tumor enlarged in 3 cases, and 2 cases developed hydrocephalus. The percentage of pure-tone hearing preservation was 82% at 3 months, 73% at 6 months, 68% at 12 months. 64% at 18 months and 59% at 24 months in 22 out of 29 cases. Relatively low dose Gamma Knife radiosurgery was effective in suppressing tumor growth, with preservation of hearing.

Adult↗
PubMed1996

Pathobiology of cerebral gliomas in children and the role of radiosurgery.

Twenty-five gliomas of the cerebral hemisphere in children were examined. Most hemispheric gliomas in children have relatively clear margins and less infiltrative potential. Radiosurgery has a role in the treatment of these tumors in addition to reducing the risk of radiation injuries developing later. Fifteen patients were alive 1-27 years (mean 8.4) following treatment and 10 patients died. Histologic examination demonstrated 10 differentiated gliomas, 10 poorly differentiated gliomas and 5 other gliomas. Most tumors had relatively clear margins on computed tomography and/or magnetic resonance images, and peritumoral edema was slight. In 9 autopsy cases, tumor dissemination and/or metastasis were seen in 7. However, tumor infiltration was not extensive, and clear tumor margins were found in some cases. Thus, cerebral gliomas in children have relatively clear margins and low infiltrative potential. Radiosurgery has a role in the treatment of these tumors.

Adolescent↗
PubMed1996

Peripheral nerve regeneration in a silicone tube: effect of collagen sponge prosthesis, laminin, and pyrimidine compound administration.

Regeneration of transected peripheral nerve with a 10-mm gap encased in a silicone tube was evaluated in the presence of collagen sponge with or without laminin, or with systemic administration of a pyrimidine compound, MS-818. The sciatic nerve of 20 adult rats was transected and the proximal and distal nerve stumps were fixed in a silicone tube. The lumen of the silicone tube was empty, or filled with a collagen sponge alone or with a laminin-soaked collagen sponge. Also, a pyrimidine compound was injected intraperitoneally after implantation of the empty silicone tube. Three weeks later, the contents of the silicone tubes were processed for histological examination of regenerated nerve fibers. Other animals were observed 6, 12, and 18 months after surgery to examine the long-term effects of the collagen sponge on nerve regeneration. All animals had regenerated tissue within the tube 3 weeks after nerve transection. The diameter of the tissue decreased toward the distal stump in the empty tube, but was the same throughout the full length in the collagen sponge-containing tube. Immunohistochemical studies revealed that the nerve fibers extended beyond the midline of the regenerated tissue in animals treated with a laminin-containing collagen sponge or receiving a pyrimidine compound. Long-term observation showed the regenerated nerve was thick as the proximal stump and many neurofilament- and peripheral myelin-positive fibers were observed around the collagen sponge. Collagen sponge assists the progress of regenerated tissues in silicone tubes, and laminin-containing prostheses and administration of a pyrimidine compound enhance peripheral nerve regeneration.

Animals↗
PubMed1996

[Automatic anatomic-physiologic correspondence of deep structures of the central nervous system in stereotaxic functional neurosurgery].

This work describes in detail the graphic facilities of a neurosurgical deep recording system for the anatomic-physiologic analysis of central nervous system deep structures in stereotaxic function neurosurgery guided by deep semi-microrecordings of the brain, as developed by the International Center of Neurologic Restoration in Cuba. This system for digitization of electrical activity in the brain uses an IBM-compatible 80386/80486 microprocessor in place of analog equipment for the visualization and recording of signals, thereby providing easier manipulation of recorded data and greater flexibility of analysis. The system automatically integrates each pulse recorded and quantifies its average amplitude. For each brain region explored, the behavior of the integrated activity recorded can be displayed on the corresponding sagittal view from the cerebral atlas of Schaltenbrand-Wahren, and then automatically scaled to the anatomic dimensions of each patient. The picture, with its different options, Facilitates analysis of anatomic correspondence of deep electrophysiologic signals so the various structures, nuclei and specific neuronal groups can be precisely located in the patient's brain. To date the system has been used successfully in over 110 neurosurgical procedures ventral intermedios (vim)-thalamotomy, pallidotomy, subthalotomy and neurotransplantation, providing more certain location of lesions or grafting sites for managing symptoms in Parkinson's disease and other movement disorders.

Brain↗
PubMed1995

Grafts of genetically modified fibroblasts expressing neural cell adhesion molecule L1 into transected spinal cord of adult rats.

L1, a neural cell adhesion molecule, is known to promote neurite elongation via a homophilic interaction in vitro. In the present study, fibroblast L cells that were genetically modified to express the L1 molecule were grafted to a lesion of rat spinal cord immediately after hemisection. Grafts drastically promoted regeneration of the axons in the injured spinal cord 2 weeks after grafting. A number of regenerating axons penetrated the glial scar along the host-graft interface, and elongated into the graft. These results suggest that grafts of genetically modified cells expressing L1 can provide an environment suitable for regeneration of the axons in the injured spinal cord.

Animals↗
PubMed1995

Parkinsonian rigidity, dopa-induced dyskinesia and chorea--dynamic studies on the basal ganglia-thalamocortical motor circuit using PET scan and depth microrecording.

Regional cerebral glucose metabolism (rCMRGlu-18FDG) was measured in 6 cases with rigid type Parkinson's disease (PD) (2 cases with dopa-induced dyskinesia = DID), 6 cases with chorea (Ch), 5 cases with essential tremor (EssT) and 2 cases with normal subjects (N). The effects of L-Dopa on rCMRGlu was studied in 3 cases with PD. With the aid of depth microrecording study, stereotactic pallidotomy was performed in all cases with PD. Thalamotomy was performed in 3 cases with Ch. In the EssT and N group, the metabolic pattern was high in the frontal cortex (FCx) but low in the lenticular nucleus (LN). In contrast, all cases with a rigid type PD showed lower rCMRGlu in FCx (premotor, prefrontal area). However, 4 out of 6 cases were higher in LN than the control group. Administration of L-Dopa shifted rCMRGlu toward the normal pattern in this group. Five out of 6 cases with Ch represented higher rCMRGlu in FCx (3 focal, 2 diffuse) but lower in LN. Moreover, when DID occurred, it showed almost the same pattern as in Ch. Electrophysiological studies showed high background neuronal activity (BNA) in the medial segment of the globus pallidus (GP) but low BNA in the lateral segment of the GP in the rigid type of PD. In cases with Ch, irregular burst discharges were often encountered in ventro-oral thalamus. From these results, the on-going changes of basal ganglia-thalamocortical motor circuit in cases with a rigid type PD, DID and Ch are discussed. The underlying mechanisms of Parkinsonian rigidity was considered to contrast with those of DID and Ch within the same motor circuit.

Antiparkinson Agents↗
PubMed1995

Calcified astrocytoma of the amygdalo-hippocampal region in children.

Three pediatric cases of temporal lobe seizure due to calcified glioma of amygdalo-hippocampal region are described. Computed tomography and magnetic resonance imaging showed dense calcification with no postcontrast enhancement in the amygdalo-hippocampal region. Positron emission tomography showed low oxygen metabolism, low glucose metabolism, hypermetabolism of amino acids, and low regional cerebral blood flow in the tumors. Single photon emission computed tomography showed a high accumulation of 201Tl chloride and 123I-isopropyl iodoamphetamine in one tumor, but otherwise low radioisotope uptake. These studies indicated low-grade malignancies. The patients were treated by partial tumor removal and radiotherapy. Histological examination of the tumor specimens showed astrocytoma with interstitial calcification. One patient died due to tumor recurrence, while the others are doing well with minimal seizure. We recommended temporal lobectomy in similar cases to achieve complete remission.

Adolescent↗
PubMed1995

Positron emission tomography with 4-[18F]fluoro-L-m-tyrosine in MPTP-induced hemiparkinsonian monkeys.

PET imaging studies with 4-[18F]fluoro-L-m-tyrosine (FMT) in normal macaca monkeys showed selective accumulations of radioactivity in the striatum with time. In monkeys rendered hemiparkinsonian by intracarotid infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), FMT uptake was eliminated in the lesioned striatum. FMT-PET studies were able to detect dopaminergic terminals in both normal and hemiparkinsonian monkeys, and clearly showed a reduction in aromatic L-amino acid decarboxylase (AAAD) activities in the MPTP-lesioned striatum. These results show that FMT is promising as a PET tracer for the evaluation of central dopaminergic systems in parkinsonism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1995

Gamma Knife radiosurgery for the treatment of brainstem tumors.

Ten patients with brainstem tumors (BST) underwent Gamma Knife radiosurgery. In 5 cases, there were definitive histological diagnoses; ependymoma (n = 3) and CNS lymphoma (n = 2). The others were diagnosed as ependymoma (n = 1), CNS lymphoma (n = 2) and glioma (n = 2) on clinical grounds. Of 4 cases with ependymoma, the tumor showed a marked response in 3 cases. Of 4 cases with CNS lymphoma, all responded rapidly and the clinical symptoms improved markedly. However, in the 2 cases with glioma, the tumor remained unchanged or continued to grow. Gamma Knife radiosurgery was effective in local growth control of BST without adverse effects. An alternative treatment design will be required in glioma cases.

Adult↗
PubMed1995

Classification of arteriovenous malformations for radiosurgery. Neuroimaging, histopathology and radiobiologic effects.

Arteriovenous malformations (AVMs) were classified based on morphologic and hemodynamic factors. They were categorized as Moya type, shunt type or mixed type on the basis of hemodynamic factors, and as homogeneous or heterogeneous types on the basis of morphology. Histopathologic and radiobiologic characteristics were evaluated with respect to these AVM types. Classification depending on the type as well as the size of an AVM is important for modern treatment modalities, especially radiosurgery.

Cerebral Angiography↗
PubMed1995

Gamma Knife thalamotomy for the treatment of functional disorders.

Gamma Knife thalamotomy was performed with a 4-mm collimator in 2 cases with thalamic pain following a stroke and in 1 case of Parkinson's disease with tremor. In both cases with pain the maximum dose of 130 Gy was focused at the mediocaudal region of the previous thalamic lesion. In the case with tremor in Parkinson's disease, the maximum dose was 150 Gy. Longer follow-up is now proceeding, but the short-term results are encouraging. Based on data obtained from selective thalamotomy with depth microrecording, Gamma Knife thalamotomy could be a safe and effective technique for the treatment of these functional disorders.

Aged↗