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Biomedical subjects

K Mizoi

Publications and source records attributed to K Mizoi.

At least 91 records · Page 5Linked to original sources
PubMed1988

Cerebral protective effect of flunarizine in a canine model of cerebral ischaemia.

To test the effect of flunarizine on cerebral ischaemia, 15 dogs were subjected to ischaemia, using the 'canine model of the completely ischaemic brain regulated with a perfusion method' in which the cerebral blood flow (CBF) can be fully regulated. Five animals served as untreated controls, 10 received flunarizine, a calcium antagonist (1 mg/kg in 5 dogs and 3 mg/kg in 5 dogs), before the ischaemic period. After 1 h CBF was restored and recovery of the electrical activity of the brain and the degree of brain swelling were observed for 3 h. At the end of the experiments, the degree of extravasation of Evans blue was examined. Remarkable recovery of EEG was found in the groups given flunarizine when compared with untreated controls. However, no significant difference was found between untreated controls and flunarizine treated groups for the degree of brain swelling and the degree of extravasation of Evans blue. These results suggest that the treatment of flunarizine is of benefit for functional recovery against cerebral ischaemia, but does not suppress ischaemic brain oedema.

Animals↗
PubMed1988

[Protective effect of various agents against ischemic neuronal damage in guinea pig hippocampal neurons studied in vitro].

A study was made of protective effect of several drugs (mannitol, phenytoin, vitamin E and dexamethasone) against the deprivation of both glucose and oxygen from the bathing medium on electrical activities of guinea-pig hippocampal neurons in vitro. Using guinea-pig hippocampal slice, we recorded antidromic field potentials in the granular cell layer of the dentate gyrus with stimulating mossy fibers. "Ischemia" of a slice was achieved by substracting both glucose and oxygen from the perfusing medium. In standard medium, after 10 minutes of ischemia, field potentials had minimum recovery with an amplitude of 5% of control after 60 minutes in the standard medium. Mannitol treatment had no protective effect, but phenytoin, vitamin E and dexamethasone had clear dose-dependent effect. The protective effect was evaluated by recovery of field potential amplitude of the 60 minutes postischemic response and histological examination of the brain slice tissue. The degree of the histological damage was correlated with recovery of field potential. In this experiment we have demonstrated that phenytoin and vitamin E obviously have the protective action against ischemic neuronal damage in the guinea-pig hippocampal slice and the combined application of these drugs were more effective.

Animals↗
PubMed1988

[Multiple meningiomas with Werner's syndrome--a case report].

A case of multiple meningiomas with Werner's syndrome is reported. He was 45-year-old man, who complained change of character and slight right motor weakness for 4 months. His symptoms were characteristic small stature, premature senility, scleroderma-like changes and other manifestations. Glucose tolerance test showed a diabetic pattern. CT scan and cerebral angiography revealed multiple meningiomas. After chemical embolization of the feeding artery, we removed these meningiomas successfully. We also reviewed the literature on Werner's syndrome with meningioma.

Humans↗
PubMed1988

[Results of the surgical treatment of multiple aneurysms--review of 372 cases].

The authors review the surgical results in 372 cases of multiple intracranial aneurysms during this 25-year period in which one of the authors (JS) performed 2,000 direct operations for aneurysms. All patients were classified into four groups according to the location of aneurysms as follows: Group 1: multiple aneurysms including anterior communicating artery aneurysm (157 cases); Group 2: multiple aneurysms of unilateral anterior circulation (72 cases); Group 3: multiple aneurysms of bilateral anterior circulation (110 cases); Group 4: multiple aneurysms including vertebrobasilar artery aneurysms (33 cases). In multiple aneurysm cases, their policy has been to treat all aneurysms, ruptured and unruptured, in a one-stage operation whenever possible. About 90% of patients in both Group 1 and Group 2 were treated by one-stage operations, while 60% of patients in Group 3 and 42% of in Group 4 were operated on in the same manner. Excellent and good results in from 73% to 81% of cases was obtained in patients of Group 1, Group 2 and Group 3. Morbidity was 14-19% and mortality was 6-8%. These results were almost equal to the results with a single aneurysm of the anterior circulation. On the other hand, the surgical results in Group 4 were poor with a mortality of 27%. Poor results were attributable to the postoperative rebleeding from the untreated vertebro-basilar aneurysms, which were thought to be unruptured aneurysms preoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1988

[A successful removal of huge confluence meningioma].

A rare case of huge confluence meningioma with many kinds of venous collaterals is presented. A 58-year-old female was admitted because of severe headache and gait disturbance. An enhanced CT (computerized tomography) scan demonstrated a homogeneous spherical high density mass in the region of the posterior falco-tentorial junction adjacent to the internal occipital crest. Cerebral angiograms showed (1) the occluded confluence sinuum and compensatory venous collaterals, (2) venous drainage through the persistent falcial sinus, which was rare in an adult, from the straight sinus into the superior sagittal sinus (SSS), (3) venous drainage through diploic veins and emissary veins into scalp veins. The tumor including the confluence sinuum was totally removed via a combined bioccipital and suboccipital craniectomy. The confluence sinuum was invaded and occluded by the tumor. The tumor was histologically diagnosed as a fibroblastic meningioma. Post-operative angiogram showed a formation of the new venous channel which is located between the posterior part of the SSS and the lateral part of right transverse sinus. The origin of this new venous pathway was thought to be congenital presence of a "latent" dural venous channel. After ventriculoperitoneal shunting, the patient was discharged without any neurological deficits. A follow-up angiogram one year and two months after discharge showed that the channel become dilated and the venous collaterals seen before surgery disappeared probably due to the change of balance of venous pressure. The venous drainage pattern seemed to become resembling the normal variant type in which the SSS drains into the right transverse sinus, and left sinus was hypoplastic.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Angiography↗
PubMed1987

Protective effect of phenytoin and its enhanced action by combined administration with mannitol and vitamin E in cerebral ischaemia.

To study the therapeutic effect of phenytoin on cerebral ischaemia and confirm whether or not the effectiveness of phenytoin could be enhanced by combined administration with free radical scavengers, twenty-five dogs were subjected to ischaemia, using the "canine model of the completely ischaemic brain regulated with a perfusion method". Five animals served as untreated controls, fifteen received treatment with several doses of phenytoin and five were treated with 10 mg/kg phenytoin, 2 g/kg mannitol and 30 mg/kg vitamin E. These drugs were administered prior to the production of ischaemia. After one hour ischaemia, cerebral blood flow was restored and the recovery of electrical activity of the brain and the degree of brain swelling were observed for three hours. With regard to the recovery of the EEG, the higher the administered dosage, the better was the degree of recovery of the EEG. And the group which was treated with a combination of phenytoin, mannitol and vitamin E exhibited remarkable recovery of the EEG. With regard to the degree of brain swelling, a similar dose-related suppressive effect was seen in the phenytoin-treated groups. Furthermore, in the combination therapy group, brain swelling was attenuated significantly. Based on these results, it is concluded that phenytoin has a protective effect in cerebral ischaemia and it shows its most remarkable effect when given together with radical scavengers, such as mannitol and vitamin E.

Animals↗
PubMed1987

Experimental study on the reversibility of cerebral ischemia. Residual blood flow and duration of ischemia.

The flow threshold and time threshold for reversibility of cerebral ischemia were studied using a canine model of cerebral ischemia regulated by controlled perfusion of cerebral blood flow (CBF). CBF was continuously monitored with a laser Doppler flow meter, the brain was brought to a constant level of ischemia for a defined period of time, after which recirculation was instituted. The electroencephalogram (EEG) and somatosensory evoked potentials (SEP) were monitored and used as an index of brain function. No recovery of brain function was found following recirculation if the CBF was reduced to a level below 20% of the normal state for more than one hour. When residual blood flow was 30% of the normal level, however, recirculation after one hour of ischemia resulted in nearly complete recovery of brain function. Significant functional recovery was not seen after two or more hours of such ischemia. Nearly complete recovery was also seen following reperfusion within three hours with 40% of normal CBF. It was demonstrated that the reversibility in the ischemic brain was critically correlated to the level of blood flow and its duration. If these results can be applied to the human brain, emergency cerebral revascularization for ischemic stroke should be attempted when critical flow and time thresholds have not been crossed, namely, in less than 1 hour and 3 hours of insult when the residual blood flow is reduced to 30 and 40% of the normal state, respectively. In clinical situations, this "critical time" may be too short for acute revascularization unless cerebral protective measures are applied pre-operatively to prolong the viability period of ischemic cerebral tissue.

Animals↗
PubMed1987

[A case of von Hippel-Lindau disease showing only spinal cord symptoms].

A rare case of von Hippel-Lindau disease showing only spinal cord symptoms is reported. This 18-year-old boy was admitted to our clinic because of urinary disturbance, slowly progressive muscle weakness and sensory disturbance of his body and four extremities. Myelography demonstrated an expanding spinal cord and a figure of complete block of contrast medium at the lower cervical level. Dilated syrinx below the level of Th-3 was shown by delayed scan (19 hr.) of metrizamide CT myelography. These findings suggest that metrizamide could pass through the cord substance from the subarachnoid space into a syrinx cavity. Contrast enhancement CT scan revealed a slightly high density mass lesion at the level of Th-1 and a more marked tumor stain at the level of C-5 and 6. Syringo-subarachnoid shunt was done but the spinal intramedullary tumors were so deeply situated in the spinal cord that total removal of them was abandoned. The pathological diagnosis was hemangioblastoma. There were also a hemangioma at the right retina and multiple small tumor stains in the cerebellum, but they presented no clinical symptoms.

Adolescent↗
PubMed1987

[Cerebral protective effect of flunarizine in a canine model of cerebral ischemia].

Recently there is the hypothesis proposing that ischemic brain damage is associated with intracellular accumulation of calcium (Ca++). Therefore a variety of experiments have been carried out to investigate whether a Ca++-entry blocker was able to protect against brain damage caused by ischemia. The purpose of the present experiment is to study the protective effects of a Ca++ antagonist, flunarizine, on cerebral ischemia. In this experiment fifteen dogs were subjected to ischemia, using the "canine model of the completely ischemic brain regulated with a perfusion method" in which the cerebral blood flow (CBF) can be fully regulated. Five animals served as untreated controls, ten received treatment with flunarizine (1 mg/kg in five dogs and 3 mg/kg in five dogs, respectively). This agent was administered intravenously 20 minutes prior to the production of ischemia, when cerebral blood flow was reduced to one-tenth its normal value while monitoring CBF by means of a laser-Doppler flow meter. After one hour CBF was restored and the recovery of electrical activity of the brain and the degree of brain swelling were observed for three hours. At the end of the experiments, the degree of extravasation of Evans blue in the excised brain was examined. With regard to the recovery of EEG, no recovery of EEG was seen subsequent to recirculation except one dog in the control group. Whereas in the groups treated with flunarizine, remarkable recovery of EEG was found following recirculation in a dose dependent fasion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Development of new cerebral protective agents: the free radical scavengers.

The generation of the free radical reaction in the ischaemic and hypoxic brain has been demonstrated using the chemiluminescence and the ESR techniques. The effects of various drugs, thought to be free radical scavengers were then tested in the ischaemic brain of dogs. It was found that not only mannitol, but also vitamin E, dexamethasone and other drugs have significant cerebral protective effects--particularly when administered together. Moreover, remarkable improvements were found when these 3 drugs were administered with the artificial blood substitute, PFC, which is known to have a high oxygen-carrying capacity. Finally, using the chemiluminescence and the ESR method, we have demonstrated that mannitol, vitamin E and glucocorticoids act as free radical scavengers and particularly mannitol acts as a scavenger of the hydroxy radical.

Animals↗
PubMed1986

Bifrontal interhemispheric approach to aneurysms of the anterior communicating artery.

The authors review their experience with the bifrontal interhemispheric approach in 603 cases of single anterior communicating artery (ACoA) aneurysms and describe the operative technique. With this approach, the olfactory tracts are dissected, and both A1 segments of the anterior cerebral arteries are identified subfrontally. The interhemispheric fissure is then dissected and A2 segments are followed from the distal portion toward the ACoA complex. Following the administration of a combination of mannitol, vitamin E, and dexamethasone, a temporary clip is placed on at least the dominant A1 segment prior to dissection of the aneurysm itself. Once the aneurysm has been completely freed from the surrounding structures, the neck is ligated and clipped. If the aneurysm ruptures during surgery, temporary clips are placed on both A1 and A2 segments bilaterally and the operation proceeds in a completely dry field. With this method, it is possible to occlude any of the intracranial vessels for up to 40 minutes within 100 minutes of drug administration. To prevent the possibility of rerupture and the development of vasospasm in the period before aneurysm surgery, the authors have adopted a policy of performing ultra-early operations within 48 hours of the onset of symptoms. Among the 257 cases operated on during the 9 years since 1975, one-fifth have been operated on within 48 hours of rupture, and the in-hospital mortality rate has been only 4.3% (11 cases). Follow-up studies have shown that 87% of the 246 surviving patients have returned to useful lives.

Humans↗
PubMed1986

Early cerebral angiography after aneurysm rupture. Analysis of 197 cases.

Although many patients with aneurysm rupture have undergone re-rupture during angiography, this event seldom occurs in the early period after the original hemorrhage. The authors review 197 cases of ruptured cerebral aneurysms that had received cerebral angiography within 1 week of rupture. With the exception of one case of re-rupture during angiography, no complications were noted in any of the patients. The criteria used for early cerebral angiography after aneurysm rupture are described.

Cerebral Angiography↗
PubMed1986

[A successfully treated case of giant basilar artery aneurysm utilizing balloon catheter occlusion and brain protective substances].

A case of giant basilar artery aneurysm successfully treated utilizing balloon catheter under the administration of 20% mannitol, dexamethasone, vitamin E (Sendai Cocktail) is reported. The patient, 59 years old female, was admitted to our clinic with complaints of headache. CT scan revealed partially enhanced, round-shaped high density mass with a diameter of 35 mm in the left posterior part of the basal cistern. Vertebral angiography revealed aneurysm at the junction of left posterior cerebral artery and superior cerebellar artery. These findings indicate the partially thrombosed giant basilar artery aneurysm. Direct operation was performed just after the inflation of balloon within the aneurysm which made temporary occlusion of the aneurysm to make the operation safely. After removal of some amount of thrombosed aneurysm, temporary clips were applied on the basilar and bilateral posterior cerebral arteries, and then the neck of aneurysm was clipped. The combined use of the balloon, Sendai cocktail and temporary clips were recommended in such a case.

Aneurysm↗
PubMed1986

[Protective effect of phenytoin and its enhanced action by combined administration of mannitol and vitamin E in cerebral ischemia].

Phenytoin is well known as the anticonvulsant agent and also said to protect the brain against ischemic damage. The purpose of the present experiment is to study the therapeutic effect of phenytoin on cerebral ischemia and confirm whether the effectiveness of phenytoin could be enhanced by combination of free radical scavengers such as mannitol and vitamin E. In this experiment, twenty-five dogs were subjected to ischemia, using the "canine model of complete ischemic brain regulated with a perfusion method" in which it is possible to control the degree of blood flow to a cerebral hemisphere via a perfusion pump at will. Five animals served as untreated control, fifteen received treatment with phenytoin (7 mg/kg in five dogs, 10 mg/kg in five dogs and 30 mg/kg in five dogs) and five treated with 10 mg/kg phenytoin, 2 g/kg of mannitol and 30 mg/kg of vitamin E. These drugs were administered intravenously 20 minutes prior to the production of ischemia, when cerebral blood flow was reduced to one-tenth its normal volume. After one hour, cerebral blood flow was restored and the recovery of electrical activity of the brain and the degree of brain swelling were observed for three hours. With regard to the recovery of EEG, no recovery of EEG was seen subsequent to recirculation except one dog in the control group. Whereas in the group treated with phenytoin, gradual emergence of slow wave ws observed soon after recirculation. The higher the administered dosage is, the better the degree of recovery of EEG was seen. Thus, the dose-related recovery of EEG was observed within the dose ranges tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[Experimental study on reversibility of cerebral ischemia--residual blood flow and duration of ischemia].

This experimental study was designed to estimate the flow thresholds and the time thresholds for reversibility of cerebral ischemia. We used a "canine model of completely ischemic brain regulated with a perfusion method", in which the cerebral blood flow (CBF) could be controlled. The residual blood flow was reduced to 10%, 20%, 30% or 40% of normal CBF, and the recirculation was started after 1, 2, 3 or 4 hours of ischemia. CBF was measured by a laser doppler flow meter. EEG and somatosensory evoked potential (SEP) was monitored and used as a parameter expressing the brain function. In the 10% and 20% ischemia group, functional recovery could not be obtained even if reperfusion was started at 1 hour after the onset of ischemia. On the other hand, in the 30% ischemia group, nearly complete recovery of EEG and SEP could be seen when reperfusion was done at 1 hour from the onset of ischemia. But recirculation after 2 hours of ischemia did not lead to significant functional recovery. In the 40% ischemia group, reperfusion within 3 hours of ischemia allowed full recovery of ischemic brain. On the contrary, reperfusion after 4 hours of ischemia showed a gradual deterioration of EEG and SEP. Accordingly, it was clearly demonstrated that the reversibility of ischemic brain was critically correlated to severity and duration of cerebral ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗