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Biomedical subjects

T Akai

Publications and source records attributed to T Akai.

At least 37 records · Page 2Linked to original sources
PubMed1996

Extradural optic nerve decompression for fibrous dysplasia with a favorable visual outcome.

A 10-year-old boy with progressive left visual disturbance associated with craniobasal fibrous dysplasia underwent left frontotemporal craniotomy. Dysplastic lesions of the sphenoid ridge, orbital roof, anterior clinoid, and ethmoid sinus were removed through an extradural pterional approach and the optic nerve was completely decompressed. His vision was markedly improved postoperatively. Consecutive follow-up studies for 3 years have shown no deterioration of his visual acuity. Early optic nerve decompression is highly recommended to preserve visual function in patients with craniofacial fibrous dysplasia causing visual disturbance.

Child↗
PubMed1995

Behavioral involvement of central dopamine D1 and D2 receptors in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian cynomolgus monkeys.

To clarify the roles of dopamine D1 and D2 receptors in behavioral symptoms of Parkinson's disease, antiparkinsonian effects of various dopamine agonists in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian monkeys were investigated with regard to induction of hyperactivity such as excitability, irritability and aggressiveness. The non-selective dopamine agonist apomorphine ameliorated the parkinsonism, but induced marked hyperactivity dose-dependently. Pretreatment with either the dopamine D1 antagonist SCH 23390 or the dopamine D2 antagonist sulpiride markedly suppressed the apomorphine-induced hyperactivity with slight attenuation of the antiparkinsonian effects. Both the dopamine D2-receptor agonist quinpirole and the dopamine D1-receptor agonist SKF 82958 ameliorated the parkinsonism in a dose-dependent manner with a slight induction of hyperactivity. Combination treatment of a threshold dose of quinpirole with that of SKF 82958 augmented the antiparkinsonian effects without a marked induction of hyperactivity. However, the combination treatment at higher doses induced marked hyperactivity accompanied by augmented antiparkinsonian effects. These results suggest that stimulation of either central dopamine D1 or D2 receptors is requisite for the antiparkinsonian effects and concurrent strong stimulation of both central dopamine D1 and D2 receptors causes marked hyperactivity which may be predictive of dopaminergic psychiatric side effects.

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

Early endovascular treatment for ruptured basilar bifurcation aneurysm--case report.

A 69-year-old male presented with sudden onset of headache. Computed tomography of the head demonstrated diffuse subarachnoid hemorrhage. Angiography showed a saccular basilar bifurcation aneurysm. Endovascular coil occlusion of the aneurysm on the same day enabled complete obliteration of the aneurysm. He did not develop vasospasm and returned home 4 months later. Early endovascular occlusion of the aneurysmal sac is an alternative method for the management of ruptured basilar bifurcation aneurysms.

Aged↗
PubMed1995

Multiple neuroepithelial tumors of different cell types--case report.

A 31-year-old male developed intramedullary tumors in the medulla oblongata and the upper cervical spinal cord. He was first admitted with tetraparesis. Magnetic resonance (MR) imaging revealed a low intensity mass lesion in the medulla oblongata. The tumor was removed and diagnosed as a pilocytic astrocytoma. Nine years later, he was readmitted with motor weakness and dysesthesia in the right arm. MR imaging revealed a mass lesion in the cervical cord. This tumor was removed and diagnosed histologically as ependymoma. We suggest that the displacement of primitive spongioblasts with subsequent differentiation resulted in an astrocytoma and an ependymoma in adjacent areas.

Adult↗
PubMed1995

[Ruptured mycotic aneurysm of the middle cerebral artery: a case report].

A sixty-two-year-old woman was diagnosed as having the mitral valve insufficiency seven months prior to admission. The patient was admitted to the hospital with complaints of right hemiparesis and aphasia. CT scan revealed an intracerebral hematoma in the left front-parietal region. Cerebral angiography disclosed an aneurysm at the distal portion of left middle cerebral artery. An increase in the amount of C reactive protein and leukocytosis indicated the presence of inflammatory lesions. Antibiotics were administered because a mycotic aneurysm was suspected. White blood cell count and C reactive protein returned to normal after treatment with antibiotics for one months. The aneurysm had disappeared on the second angiography performed after treatment. Strategy for mycotic aneurysm is still controversial. 49 reported cases in the literature since 1975 were reviewed and the efficiency of antibiotic therapy was discussed.

Aneurysm, Infected↗
PubMed1995

Combination treatment of the partial D2 agonist terguride with the D1 agonist SKF 82958 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned parkinsonian cynomolgus monkeys.

The optimal combination of a dopamine D2 agonist and a D1 agonist was evaluated for symptomatic treatment of Parkinson's disease. Behavioral effects of combination treatment of the full D2 agonist quinpirole or the partial D2 agonist terguride with the full D1 agonist SKF 82958 [(I) 6-Chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2, 3, 4, 5-tetra-hydro-1H-3-benzazepine] were investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian cynomolgus monkeys with attention to the induction of hyperactivity such as irritability, excitability and aggressiveness and of dyskinesias such as licking of paws, chewing and biting. Both quinpirole and SKF 82958 alone improved the parkinsonism with a slight induction of the hyperactivity and dyskinesias. Terguride also improved the parkinsonism but did not induce the hyperactivity and dyskinesias. Combination treatment of quinpirole with SKF 82958 not only showed a tendency to augment the antiparkinsonian effects but also induced the marked hyperactivity and dyskinesias. On the other hand, combination treatment of terguride with SKF 82958 also augmented the antiparkinsonian effects but did not induce any hyperactivity and dyskinesias. These findings suggest that combination therapy with a partial D2 agonist and a full D1 agonist or monotherapy with a dopamine agonist that has both partial D2 and full D1 agonist properties might be beneficial for treating motor dysfunction in Parkinson's disease without inducing dopaminergic side effects.

Animals↗
PubMed1994

Dural arteriovenous fistulae involving the transverse-sigmoid sinus and foramen magnum.

The authors present a rare case of dural arteriovenous fistulae (AVFs) involving both the transverse-sigmoid sinus and the foramen magnum, which was treated successfully with multi-staged endovascular procedures. The transverse-sigmoid sinus, which was thrombosed proximally and distally, was occluded by transarterial embolization followed by intraoperative embolization of the sinus using platinum coils. The dural AVF involving the foramen magnum was occluded via a transvenous approach.

Arteriovenous Fistula↗
PubMed1994

Treatment of traumatic facial arteriovenous fistula with embolization and surgical excision--a case report.

A 57-year-old male presented with a traumatic arteriovenous fistula on his face. The fistula was first treated with transarterial embolization and subsequently resection. His course was complicated by several recurrences of his fistula prior to definitive surgical treatment. The treatment of facial arteriovenous fistula and its complications are discussed in this article.

Arteries↗
PubMed1994

Pharmacological characterization of the novel anxiolytic beta-carboline abecarnil in rodents and primates.

beta-Carboline abecarnil was behaviorally and biochemically characterized as a new anxiolytic agent in rodents and primates in comparison with the benzodiazepine (BZ) anxiolytics. Oral treatment with abecarnil (0.5-10 mg/kg) showed a potent anticonflict activity in the water-lick test in rats. The minimal effective dose was lower than those of BZ anxiolytics, such as etizolam, diazepam, clotiazepam and tofisopam. Abecarnil also showed taming effects to suppress fighting and aggressive behaviors in mice and monkeys with little sedative and ataxic effects, in contrast to the BZ anxiolytics producing marked sedative and ataxic effects. Furthermore, abecarnil suppressed both the sedative and ataxic effects induced by diazepam. Abecarnil bound to rat cerebellar BZ1 receptors (Ki = 0.24 nM) with higher affinity than to rat spinal cord BZ2 receptors (Ki = 1.3 nM), whereas BZ derivatives bound to both the receptors with a low and equal affinity. GABA-ratios of abecarnil were 1.9 for the BZ1 receptors and 2.8 for the BZ2 receptors, and they were smaller than those of diazepam and flunitrazepam. Thus, in contrast to the BZ derivatives, abecarnil may act as a selective partial agonist at central BZ1 receptors, resulting in its potent anticonflict and taming effects with little sedative and ataxic effects.

Aggression↗
PubMed1994

Multiple cerebral vascular malformations and spontaneous regression--case report.

A female infant manifested a rare case of spontaneous regression of a vascular malformation in the occipital lobe after removal of another arteriovenous malformation in the frontal lobe. She was born with multiple nevi on the face, body, and upper and lower extremities. She demonstrated developmental retardation at 8 months of age. Computed tomography at 11 months of age demonstrated ventricular enlargement and a mass in the subdural portion of the left anterior fossa. Magnetic resonance images demonstrated signal void signs in the left frontal lobe, which suggested vascular malformation. Cerebral angiograms disclosed two vascular malformations. The malformation in the frontal lobe was totally removed. Cerebral angiograms 25 days after the operation failed to demonstrate either vascular malformation previously observed. Hemodynamic change following the removal of the arteriovenous malformation may have contributed to the occlusion of the remaining malformation.

Cerebral Angiography↗
PubMed1994

[Effects of display and memory load on event-related potentials during a visual search task].

We recorded event-related potentials (ERPs) in nine normal adult subjects to investigate the effects of display load (number of positions to be processed) and memory load (memory set size) on ERPs in visual search tasks. The stimulus consisted of a horizontal array of five different alphabets. In search task, subjects were required to respond only to stimuli containing a target letter. In a simple reaction task, they were required to respond to all the stimuli. The results showed that display load affected N200 and NA deflections recorded at occipital and posterior temporal electrodes, although memory load did not affect them. We also found the different effects of display load and memory load on search-related negativities. That is, in latency, search-related negativities with increasing display load appeared before those with memory load. The difference in topography between display and memory load effects on search-related negativities was not confirmed statistically. The validity of ERPs as indices for the visual and memory search processes was discussed.

Adult↗
PubMed1994

Chronic pharmacological activities of the novel anxiolytic beta-carboline abecarnil in rats.

Abecarnil, a novel beta-carboline anxiolytic, has been shown to possess potent anxiolytic and anticonvulsant activities with weak or no sedative and ataxic effects in relevant animal models. In the present study, anxiolytic, anticonvulsant and amnesic effects of abecarnil after single and repeated treatments in rats were compared with those of diazepam. Both abecarnil (0.52-10 mg/kg, p.o.) and diazepam (20 and 50 mg/kg, p.o.) exhibited significant anticonflict effects in the water-lick test. Neither abecarnil (5 mg/kg, p.o.) nor diazepam (50 mg/kg, p.o.) produced any tolerance to anticonflict effects after 14 days of repeated treatment. Both abecarnil (5-50 mg/kg, p.o.) and diazepam (20 and 50 mg/kg, p.o.) exhibited significant anticonvulsant effects against pentylenetetrazol-induced seizure. The anticonvulsant effects of abecarnil (5 mg/kg, p.o.) were not attenuated during 14 days of repeated treatment, but diazepam (20 and 50 mg/kg, p.o.) produced tolerance to anticonvulsant effects after 5 days of repeated treatment. In the three-panel runway task, abecarnil at 5 mg/kg, p.o. impaired only working memory, but diazepam at 20 mg/kg, p.o. impaired working memory and at 50 mg/kg, p.o. markedly impaired reference and working memories. The amnesic effects of abecarnil disappeared rapidly within 2 to 3 days of repeated treatment, whereas that of diazepam decreased rapidly but persisted during 14 days of repeated treatment. Thus, chronic abecarnil was found to exhibit persistent anxiolytic and anticonvulsant effects without any amnesic effects, in contrast to chronic diazepam.

Animals↗
PubMed1993

Effects of terguride, a partial D2 agonist, on MPTP-lesioned parkinsonian cynomolgus monkeys.

Behavioral effects of terguride, a partial dopamine D2 agonist, on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian cynomolgus monkeys were compared with those of the dopamine agonist apomorphine and the dopamine antagonist haloperidol. Terguride alone ameliorated the parkinsonism without inducing any sign of excitability, irritability, or aggressiveness (hyperactivity). Apomorphine alone also ameliorated the parkinsonism but induced marked hyperactivity. Haloperidol alone caused worsening of the parkinsonism, inducing transient eyelid closure. In combination with apomorphine, terguride suppressed the hyperactivity induced by apomorphine without reducing its antiparkinsonian effects. Pretreatment with haloperidol suppressed both the antiparkinsonian effects and the hyperactivity induced by apomorphine. Terguride thus exhibits both antiparkinsonian and antihyperactivity effects in a monkey model of Parkinson's disease, suggesting that terguride might be beneficial for treating motor dysfunction and dopaminergic psychosis in advanced Parkinson's disease.

Aggression↗
PubMed1993

[Effects of terguride, an ergot alkaloid derivative, on the central nervous system: biochemical and behavioral studies].

Effects of terguride, a 9,10-dihydrogenated derivative of lisuride, on the central nervous system were investigated in rodents in comparison with those of lisuride. In vitro binding studies in rat brains showed that terguride, similar to lisuride, had a high affinity for D2-, 5-HT1A-, 5-HT2-, alpha 1- and alpha 2-receptors. Terguride, as does lisuride, induced hypomotility and yawning at low doses in rats, suggesting its presynaptic D2-agonist action. Terguride, unlike the postsynaptic D2-agonist lisuride, induced neither hypermotility nor stereotypy in rats and guinea pigs, but suppressed the hypermotility and stereotypy induced by apomorphine. Terguride suppressed haloperidol-induced catalepsy in rats and induced contralateral rotations in unilaterally 6-OHDA-lesioned rats, as does lisuride. These effects may be due to the postsynaptic D2 partial agonist action. Terguride, unlike lisuride, neither induced the serotonin syndrome nor generalized to the discriminative stimuli of the 5-HT1A- agonist 8-OH-DPAT in rats. Terguride did not induce head twitch in mice. Terguride blocked noradrenaline-induced lethality and clonidine-induced hypothermia at high doses in mice. Repeated administration of terguride did not affect the behavioral actions in rats. Thus, the effects of terguride on the central nervous system seems to be produced by mediation of the agonist and partial agonist actions at presynaptic and postsynaptic D2- receptors, respectively.

Animals↗
PubMed1993

Terguride as a new anti-hyperprolactinemic agent: characterization in rats and dogs in comparison with bromocriptine.

Terguride, a derivative of the ergot alkaloid, was characterized as a new anti-hyperprolactinemic agent in rats and dogs in comparison with bromocriptine. Terguride was found to bind selectively to the pituitary dopamine D2-receptors with a high affinity (Kd = 0.39 nM). In reserpinized rats, terguride at 0.03 mg/kg, p.o. significantly reduced the serum prolactin (PRL) level. The PRL lowering effect and the effective dose were longer lasting and about 30 times lower than those of bromocriptine, respectively. In rats bearing estrogen-induced pituitary prolactinoma, chronic terguride induced shrinkage of the prolactinoma as well as reduction of the high serum PRL level. In lactating rats, terguride (1.0 mg/kg, s.c.) reduced milk production in the mammary gland, whereas bromocriptine showed no significant effect up to 10 mg/kg, s.c. Terguride (10 mg/kg, p.o.) did not induce any stereotypy and hypermotility in reserpinized rats, while bromocriptine induced both stereotypy and hypermotility significantly at 10 mg/kg, p.o. In dogs, terguride, like bromocriptine, reduced the serum PRL level, but did not affect the serum levels of growth hormone and luteinizing hormone. In dogs, bromocriptine induced both emesis and PRL-lowering at almost the same dose, whereas emesis-inducing doses of terguride were about 100 times higher than the PRL-lowering dose. These results suggest that terguride as a dopamine D2-agonist is a potent inhibitor of PRL secretion with less neurotropic side effects compared to bromocriptine, and thus a useful drug for the treatment of galactorrhea and hyperprolactinemia including prolactinoma.

Animals↗
PubMed1991

Antithrombin III modulates the effect of thrombin on the metabolism of glycosaminoglycans in cultured endothelial cells.

We previously reported that a treatment of cultures of endothelial cells from bovine aorta with thrombin resulted in a less accumulation of glycosaminoglycans (GAG) in the cell layer. In the present study, we found that thrombin-induced decrease in the accumulation of [35S]sulfate-labeled GAG (35S-GAG) such as heparan sulfate was prevented by antithrombin III (AT III) but not by heparin cofactor II (HC II). However, AT III did not show a significant effect on the 35S-GAG accumulation individually. Pretreatment of the cell layer with neither AT III nor HC II showed any preventive effect. When GAG in the cell layer was labeled with both [35S]sulfate and [3H]glucosamine, neither thrombin nor a combination of thrombin with AT III changed the ratio of the radioactivity of 35S to that of 3H. Although thrombin stimulated the release of 35S-GAG from the cell layer, AT III completely prevented the stimulatory effect. In conclusion, it was suggested that AT III may inhibit the thrombin action on GAG metabolism of endothelial cells to prevent thrombosis in vivo.

Animals↗
PubMed1991

Effect of thrombin on the production of glycosaminoglycans by cultured endothelial cells.

We investigated the effect of thrombin on the production process of glycosaminoglycans (GAG) in cultured bovine aortic endothelial cells. It was revealed that the trichloroacetic acid-insoluble [35S]sulfate-labeled GAG (35S-GAG) was decreased by thrombin. The thrombin-induced decrease in the accumulation of 35S-GAG in the cell layer occurred even in the presence of actinomycin D or cycloheximide. The incorporation of both [35S]sulfate and [3H]glucosamine into the GAG was decreased by thrombin, while the ratio of 35S to 3H was not changed. Also, the incorporation of both [3H]glucosamine and [14C]UDP-xylose into the GAG was inhibited by thrombin. From these results, it was suggested that thrombin decreased GAG in the endothelial cell layer through an suppression of formation of polysaccharide chains rather than that of core protein.

Animals↗