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Biomedical subjects

T Ohmoto

Publications and source records attributed to T Ohmoto.

At least 163 records · Page 9Linked to original sources
PubMed1995

Early treatment of subarachnoid hemorrhage after preventing rerupture of an aneurysm.

Twelve patients with Hunt and Hess neurological Grades III to V underwent thrombosis of aneurysms using cellulose acetate polymer within 23 hours of aneurysm rupture. On computerized tomography (CT), nine of these patients had difuse or localized thick subarachnoid blood clots, two had diffuse thin clots and one had intraventricular clots. Immediately after thrombosis, all patients were administered tissue plasminogen activator (TPA) through spinal or ventricular catheters. The pressure of the lumbar cerebrospinal fluid was maintained at 100 to 150 mm H2O. The TPA was given as multiple injections of 2 mg on Day 0 and 1 to 2 mg on the following 1 to 2 days. In two patients the second injection of TPA was not given because of severe brain damage resulting from the initial subarachnoid hemorrhage. Ten patients showed complete clearance of the cisternal clot on CT within 72 hours after thrombosis. Seven partially thrombosed aneurysms and five multiple aneurysms were clipped during delayed surgery. Only one patient experienced mild vasospasm as shown on the follow-up angiogram. Eight patients improved clinically and had a good recovery, two had severe disability, and two died. Urgent thrombosis of a ruptured aneurysm followed by immediate postthrombotic administration of TPA may be a safe and reasonable means of preventing vasospasm and improving patient outcome.

Aged↗
PubMed1995

Direct thrombosis of experimental aneurysms with cellulose acetate polymer (CAP): technical aspects, angiographic follow up, and histological study.

Experimental aneurysms were created using a microsurgical technique to produce anastomosed venous pouches in the bilateral common carotid arteries of 12 dogs. The 24 aneurysms were then thrombosed via an endovascular approach with injection of a cellulose acetate polymer (CAP) solution that the authors have developed for use as a liquid thrombotic material. Angiography performed 1 to 4 weeks after CAP injection revealed complete thrombosis of the aneurysm with patency of the parent artery in 16 aneurysms. Histological analysis disclosed that the aneurysmal orifice in these cases was completely covered with newly formed endothelial cells 2 weeks after CAP thrombosis. Three other aneurysms exhibited parent artery occlusion caused by protrusion of the CAP mass through the aneurysmal orifice into the parent artery; this was thought to be caused by over-injection of the CAP solution. Histological analysis of the remaining five aneurysms, initially shown to have incomplete occlusion, revealed that they each possessed a residual neck that was partially covered with endothelial cells. No rupture of the aneurysms or migration of CAP into the distal arteries was observed. These results suggest that using an endovascular approach, direct thrombosis of cerebral aneurysms with CAP is safe and effective. This technique may prove to be an alternative treatment for such aneurysms. However, there is a potential risk of regrowth or rupture of aneurysms that retain a residual neck and long-term follow-up studies will be required to evaluate this issue.

Animals↗
PubMed1995

[Image guided stereotactic biopsy for brain tumors: experience of 71 cases].

Despite advances in the neuroimaging of the brain, an accurate diagnosis of intrinsic lesion of the brain requires tissue sampling and histological verification. Seventy-one patients with intraparenchymal lesion of the brain underwent CT or MRI-directed stereotactic biopsy at Okayama University Hospital between June, 1987 and March, 1995. There were 32 men and 39 women whose ages ranged between 7 and 78 years (mean 46.1 years). All patients underwent preoperative cerebral angiography, high resolution contrast enhanced CT and MRI. The lesions were located in the hemisphere in 40 cases, the thalamus or basal ganglia in 14, the midline (corpus callosum or ventricle) in 11, the pineal region in 4, the suprasellar in one and multiple sites in one. A Brown-Roberts-Wells (BRW) CT-directed stereotactic system was used for biopsy under CT guidance. For MRI-directed biopsies a prototype modification of the BRW frame was employed. Target localization was performed using either CT or MRI. Usually one or two targets within the lesion were chosen and target coordinates were calculated using the CT or MRI scan soft ware. Positive diagnosis was obtained in 67 cases and the accuracy of the histological diagnosis was 94.4%. There were 53 gliomas, 4 metastasis, 5 germinomas, 3 malignant lymphomas, one pineoblastoma, one infarction and 4 negative biopsies. Bleeding as a complication due to stereotactic intervention occurred in one patient (1.4%). To patients with potentially inoperable lesions or lesions which might be best treated by chemotherapy or irradiation, modern techniques of neurosurgery now offer the option of precise stereotactic biopsy through small twist-drill burr holes as opposed to open biopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Fistula of the posterior communicating artery and cavernous sinus.

A 24-year-old man was admitted with conjunctival hyperemia of the left eye and progressive chemosis and proptosis 1 month after a head injury. An angiogram showed an arterial-cavernous sinus fistula of the posterior communicating artery, which was treated with minicoils. The atypical configuration, transvenous embolization, and unusual nature of the communication suggested that communication developed through a newly generated vessel in granulation tissue.

Adult↗
PubMed1995

[The use of twist drill craniostomy in stereotactic surgery for brain tumors].

A twist drill craniostomy is a rapid and relatively simple technique for perforating the skull in order to gain access to the epidural and subdural spaces and the brain. Fifty-eight patients underwent 173 twist drill craniostomies in the stereotactic procedures for the diagnosis and the treatment of brain tumors (brain tumor biopsy, implanting radioactive sources and placement of the catheters for navigation surgery) from September, 1992, through to May, 1995, at our institute. The technique was compared with standard burr hole craniostomy used in 42 patients with brain tumor. In the twist drill craniostomy, the scalp was penetrated directly by hand twist drill (2.7 mm in diameter) and scalp bleeding was able to be be controlled by injecting local anesthetic with epinephrine subcutaneously. The safety stop on the drill was set in advance based on the expected thickness of the skull at its penetration point to provide control of penetration depth as it passed through the skull hole and dura. A hole in the skull was made as the drill was advanced until a change in resistance indicated that the inner table of the skull had been penetrated and the dura lacerated. The cannula with stylet was then inserted through the guide tube to assure the penetration of the skull and dura. As the cannula penetrated the dura, a loss of resistance was noted as it proceeded through the dura toward the pial surface, The time needed in this procedure was less than 3 minutes. Associated with this procedure, there were no complications such as bleeding, or infection in 173 twist drill craniostomies in the 58 patients. Our experience with this procedure proved it to be simple, efficient, safe and superior to conventional burr hole craniostomy.

Adolescent↗
PubMed1994

Induction of Cu,Zn-superoxide dismutase after cortical contusion injury during hypothermia.

To determine the effect of hypothermia on superoxide injury after cerebral contusion, the induction of Cu,Zn-superoxide dismutase was examined 6 h after contusion in rats using Northern blotting. Cu,Zn-superoxide dismutase gene expression increased at the periphery of the contusion, which may indicate the severity of the superoxide stimulus. This increase was preserved after contusion under hypothermia, which may show that superoxide injury is still severe although brain edema is decreased.

Animals↗
PubMed1994

The significance of nucleolar organizer region (AgNOR) score in predicting meningioma recurrence.

BACKGROUND: Argyrophilic nucleolar organizer region (AgNOR) has been demonstrated in recent studies of human brain tumors, including meningiomas. The authors used this technique in meningiomas to analyze whether the mean numbers of AgNOR per nucleus (AgNOR score) are related to the recurrence rate or the proliferative potential of meningiomas. METHODS: AgNOR staining technique was applied to paraffin-embedded sections of 60 meningiomas. Twenty of these specimens also were investigated immunohistochemically with monoclonal antibody (MoAb) against DNA polymerase alpha (Pol.alpha) and with MoAb Ki-67 to compare the AgNOR score with the proliferative potential. RESULTS: There was a statistically significant difference between the AgNOR score in nonrecurrent meningiomas (2.48 +/- 0.73) and recurrent histologically benign meningiomas after gross total resection (3.20 +/- 0.96) (P < 0.02). The recurrence rate of tumors after gross total resection with an AgNOR score of 3.0 or more was significantly higher than that with an AgNOR score of less than 3.0. The AgNOR score did not always correlate with Pol.alpha or Ki-67 score; the AgNOR score of malignant meningioma that had high proliferative score was not always high. CONCLUSIONS: This study indicates that AgNOR staining appears to be a simple and useful method for estimating the probability of histologically benign meningioma recurrence even after gross total resection.

Adult↗
PubMed1994

Effect of host age upon the degree of nigrostriatal dopaminergic system recovery following cografts of adrenal medulla and pretransected peripheral nerve.

Accumulation of nerve growth factor (NGF) has been reported to occur at the distal stump of pretransected peripheral nerve. We performed adrenal medullary grafts or cografts of adrenal medulla and distal stump of pretransected peripheral nerve into the striatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated young or aging mice. We subsequently compared the survivability of chromaffin cells and the degree of host dopaminergic (DA) fiber recovery in relation to host age. In both young and aging hosts, adrenal medullary chromaffin cells cografted with pretransected peripheral nerve survived better than those in adrenal grafts alone. Host DA fiber recovery, however, showed less recovery and more restriction around the grafted site in aging compared with young hosts. We conclude that pretransected peripheral nerve can enhance the survivability of cografted chromaffin cells both in young and in aging hosts, but that DA fiber recovery is more limited in aging hosts compared to young hosts.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1994

Increased nerve growth factor level in the distal stump of transected sciatic nerve in relation to aging and its application for neural grafting.

The nerve growth factor (NGF) level in the distal stump of mouse sciatic nerve transected 24 h before increased significantly compared with that in the nontransected contralateral side. This level was higher in aged (24-month-old) mice than in aging (12-month-old) or in young (1-month-old) mice. Adrenal medullary tissue mixed with the pretransected (24 h before) distal stump of the sciatic nerve of aged mice was cografted into the ipsilateral striatum of aged mice with a unilateral 6-hydroxydopamine lesion of dopaminergic system. Two and 4 weeks after transplantation, cografted mice showed partial functional compensation in amphetamine-induced motor asymmetry while mice with adrenal grafts alone did not show the functional recovery. The immunocytochemical staining of tyrosine hydroxylase revealed large numbers of chromaffin cells surviving in cografted animals. It is concluded that NGF level in the distal stump of pretransected peripheral nerve is increased even in aged animals and cografting of this nerve stump with adrenal medulla can be effectively utilized in aged animals with nigrostriatal insufficiency.

Adrenal Medulla↗
PubMed1994

Detection of endogenous albumin as an index of blood parenchymal border alteration.

We used a microdialysis technique to establish a method to detect sequential changes in disruption of the blood parenchymal border. Twelve cats were divided into two groups; one group underwent occlusion of the middle cerebral artery for 60 minutes, the other a cold injury model. Microdialysis probes were implanted bilaterally into the white matter, and dialysates were collected successively at 30 minute intervals for 6 hours in the occlusion model and 4 hours in the cold injury model. Regional cerebral blood flow was measured simultaneously using the hydrogen clearance method. The water content of the white matter was measured using specific gravity. The proteins in the dialysate were analyzed using electrophoresis with silver stain, and, with densitometric analysis, the density of the 66.2 kDa band was quantified as albumin. The ratio of this density to the preoperative density was defined as the "albumin index." On the side of the lesion in the cold injury model, this index significantly increased 3 hours after the cold injury compared with the contralateral side, and a correlation between the water content and this index was observed. The albumin index was believed to indicate the severity of disruption of the blood parenchymal border.

Animals↗
PubMed1994

Endogenous superoxide dismutase activity in reperfusion injuries.

To elucidate the relationship between reperfusion injuries and free radicals, we monitored the endogenous superoxide dismutase (SOD) activity by intracerebral microdialysis. Six cats underwent a transient occlusion of the middle cerebral artery for 60 minutes after microdialysis probes were implanted bilaterally into the white matter under the ectosylvian gyrus. Dialysates were collected at 30 minute intervals over the course of 5 hours after reperfusion. The SOD activity of the dialysates was measured with electron spin resonance spectrometry. Regional cerebral blood flow was measured simultaneously and the water content of the white matter was assayed at the end of the experiment. After reperfusion, SOD activity increased significantly in the first 30 minutes compared with the preoperative value, and decreased over 4-4.5 hours and 4.5-5 hours in the occluded side. The water content in the occluded side was significantly higher than that in the contralateral side. The highest SOD activity during reperfusion and the water content in the occluded side seemed to correlate, although not significantly. A leakage of intracellular SOD or a reactive increase of SOD activity in response to the reperfusion injury are possible mechanisms of increase in extracellular SOD.

Animals↗
PubMed1994

Histochemical demonstration of free radicals (H2O2) in ischemic brain edema and protective effects of human recombinant superoxide dismutase on ischemic neuronal damage.

A new histofluorescence method by HPAA (p-hydroxyphenyl acetic acid) for free radicals in the brain tissue was devised to study neuronal damage induced by ischemia. Cerebral ischemia was produced in rats by injection of plastic microspheres and arachidonic acid (AA) into the right carotid artery. The concentration of malondialdehyde (MDA; free radical) in cerebral cortex of aminotriazol (an H2O2-dependent inhibitor of catalase) treated rats 2 h after stroke was 6.33 times the level before infarction, while the concentration of MDA in h-r SOD (free radical-scavenging enzyme) treated rats 2 h after stroke was significantly lower than in untreated rats. The histochemical findings demonstrated marked H2O2 production around blood vessels occluded by microspheres in the cerebral cortex of the aminotriazole treated rats 2 h after stroke together with disruption of the BBB. Light microscopical findings demonstrated extensive edematous changes in the aminotriazole treated rats 2 h after stroke, while pathological damage in SOD treated rat brains was absent or minimal. We conclude that free radicals are formed during ischemia, and that AA appears to be a major source of activated oxygen radicals. The findings indicate that SOD is protective against ischemia-induced neuronal damage.

Animals↗
PubMed1994

Assessment of the pathological grade of astrocytic gliomas using an MRI score.

To evaluate the usefulness of an MRI score for identifying tumour tissue characteristics, 41 histologically verified supratentorial astrocytic gliomas, including 13 low-grade astrocytomas (LGA) 14 anaplastic astrocytomas (AA) and 14 glioblastoma multiformes (GBM), were examined with a 0.5T superconductive MR imager. Nine MRI criteria were used: heterogeneity (HET), cyst formation or necrosis (CN), haemorrhage (HEM), crossing the midline (CM), oedema or mass effect (EM), border definition (BD), flow void (FV), degree (CE-D) and heterogeneity (CE-HET) of contrast enhancement; Gd-enhanced T1-weighted images were obtained in 32 cases (10 LGA, 10 AA, and 12 GBM). Each of the criteria was scored and analysed statistically. The mean values of LGA, AA and GBM were 0.45 +/- 0.31, 1.18 +/- 0.20, and 1.47 +/- 0.22, respectively. The MRI score increased with the pathological grades (P < 0.01-0.001). LGA had significantly lower values than AA in five (HET, CN, EM, BD, CE-D) of the nine criteria (55.6%) and lower values than GBM in all except HEM (88.9%). Three criteria (33.3%): HET, CN, and FV were significantly higher in GBM than AA. CE-D, HET, EM, CN, and CE-HET proved to be related to the pathological grade by a multiple regression analysis (P < 0.001).

Adolescent↗
PubMed1994

Ribbon enchephalo-duro-arterio-myo-synangiosis for moyamoya disease.

In patients with advanced moyamoya disease, reconstructive surgery alone may not prevent the deterioration of blood flow in the territory of the anterior cerebral artery. These types of surgery include superficial temporal artery-to-middle cerebral artery anastomosis and encephalo-duro-arterio-myo-synangiosis (EDAMS). Bilateral encephalo-duro-arterio-synangiosis (EDAS) gradually reduced the transient ischemic attacks in one of our patients who experienced motor weakness in the left extremities. After surgery, however, persistent bilateral attacks still occurred in the patient's legs. In a subsequent maneuver, we inserted the pedicle of the galea on both sides into the interhemispheric fissure, which induced marked vascularization in the territory of the anterior cerebral artery, and the attacks disappeared. Since then, we have combined this "ribbon" technique with EDAMS to treat eight patients with moyamoya disease. Postoperative angiograms showed widespread collateral circulation on the ischemic brain surface in six patients undergoing ribbon EDAS or EDAMS. Postoperative measurements of cerebral blood flow revealed improved circulation in the frontal region in four patients. The clinical results were excellent in six patients, and good in one, and we lost follow-up in one. The ribbon EDAMS procedure is effective on moyamoya disease with symptomatic cerebral ischemia of the anterior circulation.

Adolescent↗
PubMed1994

Primary cerebellar yolk sac tumor: case report.

A rare case of cerebellar yolk sac tumor is described. A 4-year-old boy was admitted for the treatment of a cerebellar tumor and, following total removal of the tumor, he was treated with combination chemotherapy consisting of cisplatin, vinblastine, and bleomycin. He died 18 months after the primary diagnosis due to tumor recurrence. Serum alpha-fetoprotein level was well correlated with the clinical course and the amount of the tumor mass in neuroimaging.

Cerebellar Neoplasms↗
PubMed1994

Superoxide scavenging activity in vitro and in the cerebral extracellular space measured by microdialysis.

Using the electron spin resonance (ESR) spin-trapping method and a high molecular cut-off membrane, we measured the superoxide scavenging activity in dialysates obtained from microdialysis. The activity in the dialysates of the Cu,Zn-superoxide dismutase (SOD) solution and feline serum were measured in vitro, and the recovery rate was calculated to be 12.88 +/- 0.9% in Cu,Zn-SOD solution and 21.52 +/- 4.38 in feline serum, which was significantly different. This difference was believed to originate from the higher osmotic pressure due to proteins in the serum and substances other than Cu,Zn-SOD that acted as antioxidants in the serum. In an in vivo study, microdialysis probes were implanted into the cerebral hemispheres in 6 cats. The sequential changes of superoxide scavenging activity were measured for 16 h and during induced cardiac arrest. No significant difference was observed and the microdialysis technique itself did not seem to cause the significant alteration of the activity in the extracellular space, although at cardiac arrest, the activity varied widely. This method can be used to study the reaction against superoxide injury in further experiments involving brain insult.

Animals↗