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T Ohmoto

Publications and source records attributed to T Ohmoto.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effects of lecithinized superoxide dismutase on traumatic brain injury in rats.

Only small amounts of superoxide dismutase (SOD) are present in the extracellular space to scavenge excess amounts of superoxide anions (02-) released after traumatic brain injury (TBI). Experiments were performed in rats with cerebral contusion produced by weight-drop technique. We investigated the effects of exogenous lecithinized SOD (PC-SOD) on accumulation of 02- produced in our model, by measuring the level of SOD activity (using the NBT-reducing method) and the expression of copper, zinc-SOD (Cu, Zn-SOD) mRNA (by Northern blot analysis). As determined by tissue-specific gravity, administration of PC-SOD reduced brain edema in the periphery of the lesion 6 h after contusion. SOD activity increased in the peripheral region at 30 min after contusion, but returned to normal levels at 6 h after TBI. Administration of PC-SOD increased SOD activity up to 6 h after TBI. The expression of Cu, Zn-SOD mRNA increased in the core region, peripheral portion, and contralateral hemisphere up to 6 h after TBI, then was suppressed in all three regions by PC-SOD. Our results confirm the important role of 02- in the development of brain edema after TBI and indicate that PC-SOD diminishes brain edema through a protective effect against 02-.

Animals↗
PubMed1997

The protective effect of dexamethasone against radiation damage induced by interstitial irradiation in normal monkey brain.

OBJECTIVE: The protective effect of dexamethasone against radiation damage is unclear. We examined the effect of early treatment of high-dose dexamethasone on iridium-192-induced damage to normal brain tissue. METHODS: Brain damage induced by interstitial irradiation with iridium-192 was evaluated with sequential magnetic resonance imaging and proton magnetic resonance spectroscopy in 11 adult monkeys, with or without short-term high-dose dexamethasone treatment. Dexamethasone (1 mg/kg of body weight/d) was administered intramuscularly to five irradiated animals every 24 hours, beginning 2 days before and ending 7 days after irradiation. Magnetic resonance imaging and proton magnetic resonance spectroscopy were performed 1 week, 1 month, and 3 months after irradiation. RESULTS: Magnetic resonance imaging performed 1 week after irradiation revealed marked edema in five nontreated animals. In dexamethasone-treated animals, the volume of edema was reduced significantly, compared to that of nontreated animals, 1 week and 1 month after irradiation. The volume of ring enhancement in dexamethasone-treated animals was also reduced significantly, compared to that of nontreated animals, 3 months after the irradiation. Proton magnetic resonance spectroscopy spectra revealed that N-acetylaspartate and choline peaks were reduced 1 week after irradiation in both groups. However, there were no statistically significant differences between the two groups at any time points. CONCLUSION: These results suggest that dexamethasone treatment may have an antiedema effect at an early stage and may modify subsequent development of vascular and inflammatory changes but may have no effect of preventing radiation-induced necrosis and the reduction of N-acetylaspartate after brachytherapy.

Animals↗
PubMed1997

Direct clip obliteration of a ruptured giant aneurysm of the posterior communicating artery: case report.

OBJECTIVE AND IMPORTANCE: A review of the literature documents that giant posterior communicating artery (PCoA) aneurysms are rare. To our knowledge, this report is the first to describe a ruptured giant aneurysm arising from a PCoA that was successfully clipped. CLINICAL PRESENTATION: A 27-year-old man had a left oculomotor palsy and then suffered a subarachnoid hemorrhage. Cerebral angiography and three-dimensional computed tomographic angiography revealed a giant fusiform aneurysm of the left PCoA. These imaging techniques documented the rapid growth of the aneurysm from a moderate to a giant size in fewer than 3 days. INTERVENTION: The patient underwent a left subtemporal craniotomy. The neck was constructed and was successfully clipped, and the PCoA was reconstructed with five sequentially placed fenestrated clips in a tandem fashion. The patient experienced a good recovery. CONCLUSION: This report describes the usefulness of three-dimensional computed tomographic angiography in planning the surgical approach to giant aneurysms originating from the PCoA and the use of fenestrated clips to obliterate giant fusiform aneurysms.

Adult↗
PubMed1997

Three-dimensional analysis of vasospastic major cerebral arteries in rats with the corrosion cast technique.

BACKGROUND AND PURPOSE: Although mice, rats, and other small animals are commonly used for molecular biology research, their use in the evaluation of cerebral vasospasm after subarachnoid hemorrhage is somewhat problematic because of the correspondingly small size of their cerebral vessels. We have already reported that the corrosion cast technique was useful for evaluating newly formed cerebral vessels in neural grafts in these small animals. In the present study we applied the corrosion cast technique to the evaluation of hemolysate-induced cerebral vasospasm in rats and performed three-dimensional analysis for comparison. The casting was done 10 minutes after the hemolysate injection, so that only acute "vasospasm" was assessed. METHODS: After withdrawal of 0.1 mL cerebrospinal fluid, 0.2 mL hemolysate (n = 9) or saline (n = 10) was injected into the cisterna magna of male Sprague-Dawley rats weighing between 300 and 350 g. Ten minutes later, perfusion of a semipolymerized casting medium was performed at an injection pressure of 100 to 120 mm Hg. The brains were immersed and corroded in 10% NaOH solution. After these procedures, the basilar artery as well as peripheral vessels was analyzed morphologically with scanning electron microscopy. Conventional histological analysis with the use of paraffin-embedded section with hematoxylin-eosin staining was also performed, and the results were compared with those for the corrosion cast methods. RESULTS: In the saline-injected group, SEM showed that the inner surface of the basilar artery was smooth and the form of the endothelial cell was printed on the surface of the cast. In the hemolysate-injected group, the basilar artery showed an apparent vasospasm over its entire length, and corrugation was observed on the inner surface of the basilar artery in a three-dimensional fashion. Higher magnification revealed that the nuclei of the endothelial cells were distorted. Local narrowing of the basilar artery and vasospasm in the arteries of the anterior circulation and in peripheral arteries were also observed. Measurement of the inner diameter of the basilar artery showed 37.8% contraction in the hemolysate-injected group compared with the saline-injected group by the corrosion cast method. This degree of vasospasm was similar to that observed by the conventional histological method. CONCLUSIONS: In this report we show that detailed three-dimensional observation in the rat can be performed qualitatively and quantitatively with the corrosion cast technique. We conclude that this method derives an accurate measurement of the diameter of rat major cerebral arteries and is more reliable for analyzing vasospasm in rats than angiography and other conventional procedures.

Animals↗
PubMed1997

New method for the evaluation of the response of cultured cell lines to continuous low-dose-rate irradiation from encapsulated iridium-192 seeds with hyperthermia.

A new method was designed to investigate and evaluate the biological effectiveness of hyperthermia combined with continuous low-dose-rate irradiation (CLDRI) from encapsulated iridium-192 seed sources on glioma cells in vitro using the MTT assay. The system consists of 10 iridium seeds contained in a catheter bent into a circle, which is placed on a culture plate containing the cells. The effects of CLDRI and CLDRI combined with hyperthermia on a cultured rat glioma cell line (C-6) were studied. The number of surviving cells decreased as the total radiation dose increased. There was no significant difference in survival rates at dose rates of 0.1 Gy/hr and of 0.2 Gy/hr (p = 0.2811). An additive effect was observed in the cells treated with hyperthermia at 41 degrees C and 42 degrees C, combined with CLDRI, and synergistic effect between the two treatment modalities was observed at 43 degrees C. This new device is less expensive, easily reproducible, and can also be performed easily enough to examine a large number of samples in a short time period for sensitivity testing.

Animals↗
PubMed1997

Intraparenchymal metastatic tumor with periventricular dissemination--case report.

A 50-year-old male presented with a rare intraparenchymal metastatic tumor spreading through the periventricular tissue. Magnetic resonance (MR) imaging demonstrated the tumor as a heterogeneous low-intensity area on T1-weighted images with enhancement by gadolinium-diethylenetriaminepenta-acetic acid, and as a heterogeneous high- or isointensity area on T2-weighted images. Histological examination of a biopsy sample showed adenocarcinoma. This MR imaging appearance is typical of malignant glioma. The differential diagnosis of tumor in the cerebral parenchyma with ventricular dissemination should include both primary and secondary intracranial malignant tumors. MR imaging is useful in the diagnosis of such tumors, but the final diagnosis should be based on either tissue biopsy or cytological examination of the cerebrospinal fluid.

Brain Neoplasms↗
PubMed1997

Induction of resistance to etoposide and adriamycin in a human glioma cell line treated with antisense oligodeoxynucleotide complementary to the messenger ribonucleic acid of deoxyribonucleic acid topoisomerase II alpha.

Acquisition of resistance to anticancer agents is a serious problem for cancer chemotherapy. The present study analyzed the relationship between expression of the alpha isoform of deoxyribonucleic acid (DNA) topoisomerase II (topo II alpha) and chemosensitivity to topo II inhibitors by modulating the level of topo II alpha expression. A phosphorothioate analogue of an 18-nucleotide oligomer which is complementary to the translation initiation site of the human topo II alpha messenger ribonucleic acid sequence was used to suppress the expression of topo II alpha in a human glioma cell line (U373MG). The topo II alpha activity of the treated cells was reduced to 1/3 of untreated cells in a decatenation assay using kinetoplast DNA. Antisense oligoDNA-treated cells showed mild resistance to the topo II inhibitors, etoposide and adriamycin, of about 2.0 fold and 1.5 fold, respectively, compared to control cells. Only partial reduction in the activity of topo II alpha in the glioma cell line can cause a measurable resistance to topo II inhibitors, implying that the degree of topo II expression is correlated with chemosensitivity to topo II inhibitors.

Antibiotics, Antineoplastic↗
PubMed1997

Effect of adjuvant iridium-192 brachytherapy on the survival of patients with malignant gliomas.

The effect of iridium-192 brachytherapy (BRTX) on the survival of patients with malignant gliomas was evaluated in 83 patients with malignant gliomas (42 astrocytoma grade III, 41 glioblastoma multiforme) over a period of 8.5 years. Fifty patients (Group 1) received only standard external beam radiotherapy (EBRT) (mean dose 51.5 +/- 12.4 Gy in 2.0 Gy fractions), and 33 patients (Group 2) received EBRT (mean dose 51.0 +/- 10.8 Gy) combined with BRTX (mean dose 50.2 +/- 13.2 Gy, dose rate of 0.3-0.4 Gy/hr). The median survival periods for patients in Groups 1 and 2 were 12.2 and 23.7 months, respectively (p = 0.0145). The median survival for 17 patients in Group 2 with glioblastoma multiforme was 21.9 months. Using BRTX as an adjuvant to EBRT appeared to confer survival benefits compared to only EBRT (p = 0.0284). Univariate and multivariate analysis identified the variables of histological diagnosis, location, Karnofsky performance status, and BRTX as relevant risk factors for survival time (p < 0.05 for each factor). Among these factors, BRTX was the most important for prolonging survival (p = 0.0015). Adjuvant iridium-192 BRTX and conventional EBRT appears to greatly improve the survival time of patients with malignant gliomas compared to only EBRT and may be the treatment of choice in selected patients with tumors located in deep-seated or eloquent areas.

Adult↗
PubMed1997

Pineocytoma with massive intratumoral hemorrhage after ventriculoperitoneal shunt--case report.

A 58-year-old male suffered a massive intratumoral hemorrhage after placement of a ventriculoperitoneal shunt before treatment for pineocytoma. At admission, he complained of headache, urinary incontinence, gait disturbance, and recent memory disturbance. His neurological examination revealed impaired memory and papilledema from hydrocephalus. Two days after the placement of the ventriculoperitoneal shunt, he suddenly became stuporous and Parinaud's sign appeared. Computed tomography showed a massive intratumoral hemorrhage occupying the third ventricle which had extended into the lateral ventricle. The infratentorial supracerebellar approach was used to remove the hematoma and the tumor. The histological diagnosis was pineocytoma. Intratumoral hemorrhage in pineocytoma after the placement of a ventriculoperitoneal shunt is rare, but should be kept in mind when a ventriculoperitoneal shunt is placed before a craniotomy.

Cerebral Hemorrhage↗
PubMed1997

Penetration of the optic chiasm by a ruptured anterior communicating artery aneurysm. Case report.

There are few reports of anterior communicating artery aneurysms causing visual symptoms, and penetration of the optic chiasm by such aneurysms has not been reported. A 40-year-old man presented with the abrupt onset of left homonymous hemianopsia, right visual acuity disturbance (finger counting), and slight headache. Angiography disclosed a 7-mm anterior communicating artery aneurysm projecting inferiorly. After the neck of the aneurysm was clipped, the dome of the aneurysm was resected. The operation confirmed that the aneurysm had penetrated the right half of the optic chiasm and the thrombosed dome had also compressed the right optic tract. Although the aneurysm was successfully clipped, the visual disturbance persisted after surgery, suggesting that the damage to the visual pathways by aneurysm penetration was irreversible in this case.

Adult↗
PubMed1997

[Transient mutism after resection of left frontal lobe astrocytoma in adult: case report].

We reported a case of a 32-year-old female who had a transient mutism after resection of a malignant astrocytoma in the left frontal lobe. Preoperatively magnetic resonance (MR) imaging revealed a cystic tumor in the left frontal lobe. The patient underwent surgery. She was alert but did not speak immediately after surgery. She could follow verbal commands, comprehend written language, and write letters. She had no cranial nerve or extremity paresis. Seven days postoperatively, she began to say simple words, and one month postoperatively she could talk normally. Postoperative MR imaging revealed a hypointensity area on T1 weighted image in the frontal lobe including a part of the anterior cingulate cortex and the anterior part of the corpus callosum. It appears that a dominant hemisphere lesion of both the anterior cingulate cortex and the corpus callosum may be responsible for the development of postoperative mutism.

Adult↗
PubMed1997

[Clinical study of primary central nervous system lymphoma: the role of chemotherapy].

We conducted a retrospective study of 32 patients with histologically confirmed primary central nervous system lymphoma treated in our institute between 1971 and 1995 with an emphasis on the role of chemotherapy. Thirty of the 32 patients underwent tumor resection, whereas 2 patients had biopsies only. Twenty-eight patients received adjuvant therapy, 9 of whom received radiation therapy alone, 2 received chemotherapy alone, and 17 received both radiation therapy and chemotherapy. Chemotherapies performed were CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone). VEMP or VENP (vincristine, cyclophosphamide, mercaptopurine [or Natulan], and prednisolone), intravenous ACNU (nimustine), and intravenous or intra-arterial MCNU (ranimustine) and CBDCA (carboplatin). Survival data were available for 30 of the 32 patients. The median survival time of this study was 12.5 months. Twenty-seven patients died from one month through 79 months after the initiation of therapy, and 3 patients were alive for 13 to 69 months. Two patients who received the combination of radiation therapy and chemotherapy survived longer than 5 years. Although radiation therapy and chemotherapy were individually both effective and prolonged the survival time, their combination was more effective. The median survival time was significantly shorter (7.0 vs 16.5 months, p < 0.05) for the patients who received radiation therapy alone than for the patients who received the combination of radiation therapy and chemotherapy. We conclude from our results and review of previous studies that it is important for the chemotherapy of primary central nervous system lymphoma 1) to apply a combination of a variety of effective drugs, similar to that for systemic malignant lymphoma, and 2) to make a sufficient amount of anti-cancer drugs penetrate the whole central nervous system, thereby satisfying the adequate dose intensity for each drug.

Adolescent↗
PubMed1997

[Preservation of olfaction in frontal transbasal approach].

Lesions in the frontal base and clival area have conventionally been approached using the transbasal approach described by Derome and Guiot. However, this approach necessitates removal of the crista galli and sectioning of the olfactory rootlets with the associated risk of anosmia and cerebrospinal fluid leak and, in addition, complex reconstruction of the frontal base is required. We describe a new approach to deeply situated tumors in the frontal base, parasellar and clival area which is a modification of Spetzler's craniofacial approach with preservation of olfaction. In this approach, circumferential osteotomy cuts are made around the cribriform plate to permit en block removal with its attachment to both the dura and underlying mucosa. Opening of the dura is avoided and the cribriform bone is used to reconstruct the frontal base. Three patients underwent surgery using this approach for treatment of recurrent pituitary adenoma in two cases and for clivus chordoma in one. In one patient, olfactory function was not preserved because resection of nasal mucosa was small. In the other two patients, however, olfaction was preserved by creating a cribriform plate complex with a sufficient area of resection of nasal mucosa and tumors were completely removed. Olfaction can be preserved, CSF leakage can be prevented, and facial skin incision and complex frontal base reconstruction can be avoided when this technique for maintaining normal olfactory-cribriform anatomy is used in frontal transbasal approaches.

Adenoma↗
PubMed1997

[Motor functional MRI by spiral scan--compared with GRE].

Recently, functional MRI (fMRI) has been performed in two methods using 1.5 tesla machine. One was performed using gradient recalled echo (GRE), the other was performed using echo planner imaging (EPI). There is a third method for fMRI called spiral scan. This method is applicable without strong gradient magnetic field such as required by EPI. In this study, motor fMRI was performed in ten normal volunteers by both spiral scan and GRE. Less than 1% risk (t-test), spiral scan showed the reactive area more clearly than GRE. And GRE showed higher signal intensity changing ratio than spiral scan, but there was no significant difference between spiral scan and GRE. The acquisition time of spiral scan was 2 seconds per image, and that of GRE was 10.5 seconds. Spiral scan has good temporal resolution and contrast-noise ratio. These are very advantageous for fMRI.

Adult↗
PubMed1997

[Stereotactic brachytherapy for clival chordoma].

There has recently been interest in the use of high-dose radiation with methods such as radiosurgery and brachytherapy for skull base tumors. Brachytherapy is believed to be effective for clival chordomas, but technical difficulties exist in stereotactic insertion of catheters into the clivus. We assessed the usefulness following improvement of implantation techniques in three patients with clival chordomas. All tumors were larger than 50 mm in diameter. Removable iridium-192 sources were held in catheters which were implanted through a transnasal approach under general anesthesia using a CT-guided stereotactic system in one patient and a CRW stereotactic system adapted to a magnetic resonance imaging (MRI) scanner in 2 patients. The implantation array was designed based on results of stereotactic 3-D MRI scanning, and coordinates were calculated for stereotactic implantation through twist drill holes. These catheters were introduced through the nares and directed into the clival chordoma under endoscopic visualization and X-ray fluoroscopy. No complications such as CSF liquorrhea, hemorrhage or infection were observed. Brachytherapy with a total dose of 43.2-58.0 Gy at the tumor periphery was administered for 7 to 10 days, and serial follow-up imaging studies demonstrated reduction in tumor size in two patients and no tumor growth in the other. Our results suggested that stereotactic brachytherapy is potentially useful for the control of clival chordomas and that computer-guided transnasal stereotactic insertion enables implantation of catheters less invasively and more accurately than does X-ray fluoroscopic guidance alone.

Adolescent↗
PubMed1997

Proton MR spectroscopy of delayed cerebral radiation in monkeys and humans after brachytherapy.

PURPOSE: To determine whether radiation necrosis can be differentiated from residual/recurrent tumor by proton MR spectroscopy. METHODS: We studied the effects of interstitial brachytherapy on the brains of healthy monkeys and in humans with glioblastoma multiforme. The effects of radiation therapy on normal brain tissue in monkeys were assessed with sequential proton MR spectroscopic studies 1 week to 6 months after brachytherapy. Proton MR spectroscopy was also performed in five patients with residual/recurrent glioblastoma multiforme (three of whom had radiation necrosis after brachytherapy), seven patients with newly diagnosed untreated glioblastoma multiforme, and 16 healthy volunteers, who served as a control group. RESULTS: In monkeys, the ratio of N-acetylaspartate (NAA) to creatine-phosphocreatine (Cr) and the ratio of choline-containing compounds (Cho) to Cr of the reference point were significantly lower 1 week after brachytherapy than before treatment. The ratio of NAA to Cho of the irradiated area tended to be higher 1 week after brachytherapy than before irradiation. These peak metabolic ratios showed characteristic changes 6 months after treatment. In two of three monkeys, lipid signal was elevated 6 months after irradiation. In the clinical study, the ratio of NAA to Cho in the area of radiation necrosis was significantly different from that in glioblastoma multiforme when compared with the contralateral hemisphere after irradiation. In addition, lipid signal was detected in all patients with radiation necrosis. CONCLUSION: It might be possible to use proton MR spectroscopy to differentiate radiation necrosis from residual/recurrent glioblastoma multiforme on the basis of comparisons with the contralateral hemisphere after radiation therapy.

Adult↗