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Biomedical subjects

N Komai

Publications and source records attributed to N Komai.

At least 109 records · Page 6Linked to original sources
PubMed1989

Vascular "sphincter" and microangioarchitecture in the central nervous system: constriction of intraparenchymal blood vessels following a treatment of vasoconstrictive neurotransmitter.

The site of action of neuropeptide Y (NPY), a potent vasoconstrictive neurotransmitter, on the intraparenchymal blood vessels in the rat parietal cortex was demonstrated using a corrosion cast technique with scanning electron microscopy. Our observations were confined to the cortical area where the regional cerebral blood flow (rCBF) had been reduced significantly by in situ application of NPY. A striking finding in that area was the diffuse narrowing of the perforating arteries in the upper cortical layers. Ring-like compressions on the corrosion casts, presumably formed by active vascular sphincters along the arteries, capillaries and venules within the brain parenchyma, seemed to be more prominent in the perforating arteries of the NPY-treated cortex as compared with those of control cortex. We conclude that NPY-containing nerve fibers along the parenchymal blood vessels may take part in regulating the rCBF primarily by reducing the caliber of the proximal perforating arteries.

Animals↗
PubMed1989

[Three-dimensional display of structures and lesions in the brainstem using a personal computer].

The method of three-dimensional reconstruction of structures and lesions in the brainstem was developed by using a personal computer to visualize the affected sites in some cranial nuclei and long tracts. Outlines of brainstem structures and lesions were digitalized manually by tracing the atlas of the human brainstem and CT or MR images. Four outlines of the brainstem, the medulla, lower pons, upper pons and midbrain, and the outlines of any parenchymal structures were taken at every point 2 mm in thickness. These were used as the standard visualization of the atlas. The CT and MRI, which show outlines of the lesions, were taken on the vertical planes to the floor of the fourth ventricle, one of which included the fastigium, at every point 3 to 5 mm in thickness. These two kinds of outlines, taken from the atlas and the CT/MRI, were reconstructed three-dimensionally with commercial 3-D software. It took only 20 to 25 minutes for the digitalization and the 3-D reconstruction. Three-dimensional display of small structures, which were difficult to identify on CT or MRI, and lesions would enable the visualization of their anatomical relations and make possible the detection of the affected sites, not only in the axial but in the longitudinal direction. Correspondence between the affected sites on 3-D and the neurophysiological examinations (ABR, SSEP) confirms that our 3-D method is adequate for use in the anatomical diagnosis of affected sites in any small structure in the brainstem.

Brain Diseases↗
PubMed1989

[A study on the vascular permeability of brain tumors using dynamic CT].

The vascular permeability of 50 brain tumors of various kinds was examined by means of dynamic CT. The degree of the vascular permeability within the tumor was evaluated according to the theoretical basis that the regression of the time-density curve after the peak to the base line became less in accord with the increase in vascular permeability. The time-density curves obtained from dynamic CT were classified into the following four types. Type 1; This type shows a similar pattern to normal brain tissue and is thought to reveal the normal vascular permeability. Type 2; this type shows intermediate pattern between type 1 and type 3. And the vascular permeability is thought to have been moderately increased. Type 3; This type shows the flattening or gradual increase in the time-density curve after forming the peak. The vascular permeability is thought to have increased markedly. Type 4; The peak of the time-density curve is lower than that of the white matter. This type of tumor is regarded to be least vascularized. All tumors except for gliomas and AVMs showed type 2 or 3 and their vascular permeability was thought to be increased. Most of the gliomas showed type 2 or 3, although some gliomas showed type 1 even in the lesion with positive contrast enhancement. In the lesions of such cases, it was thought that the vascular permeability was not affected significantly, so that blood brain barrier modification therapy by intraarterial mannitol infusion may be quite effective. All AVMs showed type 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Effects and indications of spinal cord stimulation on the vegetative syndrome].

The effects of spinal cord stimulation (SCS) on the vegetative syndrome were studied in six patients. Factors affecting the results were mentioned with a view to establishing indications as to whether or not the SCS should be performed. "Persistent vegetative states" were thought to be identical with Ohta's "vegetative syndrome" which consists of eleven signs. Six of these signs--polyphasic cycle of waking and sleeping, urinary incontinence, being bedridden and being tube fed etc--were important criteria of the vegetative syndrome. SCS was thought to be effective if one or more of the 6 signs disappeared after SCS. SCS was performed at level from C2 to C4 with a frequency of 25 to 120 Hz, an intensity of 2.5 to 6 volts, a pulse duration of 0.3 to 0.5 msec. and a duration of 3 to 11 hours per day. Neurological signs, ABR, CT/MRI, EEG and the grade of the vegetative syndrome were estimated before and after SCS. In the course of SCS, 2 of the 6 patients recovered from the vegetative syndrome. Both had a localized lesion in the brain stem without a cerebral lesion on CT/MRI, with bilateral appearance of the fifth peak with prolonged latency and decreased amplitude of main peaks on ABR. The other 4 patients showed little or no improvement. They all had diffuse cerebral atrophy or low density areas on CT and almost normal ABR. One of these patients, who suffered a cerebral contusion leading to transtentorial herniation with unilateral cerebral contusion on CT and unilateral disappearance of the fifth peak on ABR, showed no recovery from the vegetative syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Immunohistochemical demonstration of vasopressin nerve fibers in the cerebral artery.

Vasopressin-immunoreactive nerve fibers were demonstrated in the cerebral pial arteries by peroxidase immunohistochemistry. In the large pial artery (proximal part of the middle cerebral artery), they ran longitudinally to the long axis of the vessel. They ran in a spiral pattern in the distal part of the middle cerebral artery. Even in small arteries, vasopressin nerve fibers were found arranged in a longitudinal fashion. The present morphological data suggest that vasopressin nerve fibers in the cerebral artery may play a role in cerebral circulation.

Animals↗
PubMed1988

Congenital vertical pendular nystagmus in sisters.

Sisters with congenital vertical nystagmus are described in this report. In these 2 cases, the nystagmus on the electronystagmogram (ENG) showed a pure pendular pattern on forward gaze. Neurological examinations revealed no abnormality except for the nystagmus and visual disturbance. In the elder sister, the ENG showed that the intensity of the nystagmus decreased during eye closure and that there was no response to vertical optokinetic stimulation. We believe that the elder sister is the first case of congenital vertical pendular nystagmus confirmed by neuro-otological and neuro-ophthalmological examinations.

Child↗
PubMed1988

Autotransplantation of the superior cervical ganglion into the brain. A possible therapy for Parkinson's disease.

The superior cervical ganglion (SCG) of rats was transplanted into their own parietal cortex. Four weeks after implantation, catecholamine histofluorescence revealed many transplanted catecholamine cells in the cortex. However, no fibers extended from the transplanted tissue to the cerebral cortex. In a second group of rats which had been pretreated with 6-hydroxydopamine (a specific neurotoxin to the catecholamine neuron), some showed extension of catecholamine fibers to the cerebral cortex. To simulate an animal model of Parkinson's disease, MPTP (1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine) was administered to five monkeys. Two weeks after MPTP administration, dopamine terminals in the caudate nucleus disappeared. After autotransplantation of the SCG into the caudate nucleus of these monkeys, many of the transplanted SCG cells extended axons beyond the graft into the caudate nucleus. These results show that transplanted SCG cells survived well in the brain. Under special circumstances, such as a shortage of catecholamine in the brain, implanted SCG cells extended their axons into the brain. It is suggested that autotransplantation of SCG grafts may be a new therapy for Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

Pineoblastoma with an unusually long survival. Case report.

The authors report a case of pineoblastoma with a 9-year follow-up period after stereotaxic biopsy, a shunting procedure, and radiotherapy. Light and electron microscopic studies of biopsy and autopsy specimens revealed no cell differentiation of the pineoblastoma. The possible factors predisposing to long survival are discussed in comparison with the course in patients with medulloblastoma.

Adult↗
PubMed1988

[A case of carotid superior cerebellar artery anastomosis associated with bilateral hypoplasia of the internal carotid artery represented as the rupture of posterior cerebral artery-posterior communicating artery aneurysm].

A rare case of a variant type of the persistent primitive trigeminal artery associated with bilateral hypoplasia of the internal carotid artery was reported. Left common carotid arteriography revealed a thin left internal carotid artery terminated at the ophthalmic artery. Right common carotid arteriography showed that a narrow internal carotid artery gave off several fine vessels to the cavernous portion, and terminated at the right superior cerebellar artery via the prominent persistent primitive trigeminal artery (PTA). Supraclinoid portions of the bilateral internal carotid arteries were not able to be found. Eventually the entire cerebral hemisphere was supplied by the vertebrobasilar system via the posterior communicating artery. The narrowed supraclinoid portion of the left internal carotid artery was confirmed by surgery of the left posterior cerebellar artery-posterior communicating artery aneurysm. This case may provide an important suggestion about the mechanism of the persistence of the primitive trigeminal artery. In an embryo, at the stage of 5-6mm embryo in size, the posterior communicating artery begins to develop and then PTAs begin to dwindle. If the C1- or C2- portion of the internal carotid artery is gradually occluded, the forebrain, which has to be supplied by the internal carotid system, must be supplied retrogradely by the basilar system via the posterior communicating artery. At this stage, however, the vertebral artery has not developed enough to supply the entire central nervous system. Therefore, the PTA can not regress and this results in the postnatal persistence of the primitive trigeminal artery.

Adult↗
PubMed1988

[Transplantation of the superior cervical ganglion into the brain--a new experimental therapy of Parkinson disease].

To supplement catecholamine deficit in the brain with Parkinson disease, we have aimed to transplant the superior cervical ganglion (SCG), which contains norepinephrine and dopamine, into the brain. 1. Transplantation of SCG into rat cerebral cortex SCG was transplanted into the same rat's parietal cortex. Three weeks after the transplantation, catecholamine histofluorescence revealed many transplanted catecholamine cells in the cortex. However, no fibers extended from the transplanted tissue to the cerebral cortex. Some catecholamine fibers extended to the cerebral cortex where 6-OHDA (a specific neurotoxin to the catecholamine neuron) had been pretreated. 2. Transplantation of SCG into the caudate nucleus of MPTP-induced Parkinson monkey For animal model of Parkinson disease, MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) was administered to 5 monkeys. Tow weeks after MPTP administration, dopamine terminals disappeared in the caudate nucleus. After transplantation of SCG in the same animal, many transplanted SCG cells extended their axons to the caudate nucleus. The present results showed that transplanted SCG cells were well survived in the brain. Under a special circumstance such as shortage of catecholamine in the brain, transplanted SCG cells extended their axons into the brain. It is suggested that the transplantation of SCG can be a new therapy for Parkinson disease.

Animals↗
PubMed1988

[Three-dimensional correlation between auditory brainstem response and auditory tract in hypertensive pontine hematoma].

A three-dimensional reconstructed display using a microcomputer represents the spatial correlation between the nuclei of auditory tract and pontine hematoma. Stereotaxic evacuation of hematoma was performed on seven cases of pontine hemorrhage. By making a comparison between preoperative and postoperative findings of ABR and this display, we examined the effect of the surgical intervention on ABR findings. ABR was recorded according to the standard way (100 dBSL, 2000 click stimuli). Hematoma was drawn on the Atlas of the Human Brainstem and Cerebellar Nuclei by Farhad Afshar. The data plotted on digitizer was inputted and processed under our computer program that enables the brainstem and hematoma visualized and rotated three-dimensionally at our option. The results were as follows: a) ipsilateral dominance in human auditory tract in terms of the origin of ABR waves, b) delayed latency time of wave II which was supposed to be based on an influence upon the ipsilateral superior olivary nucleus, c) that of wave III upon the ipsilateral lateral lemniscus, d) four cases of them showed an improvement of I-III interpeak latency time, which suggested the decompressive effect on caudal aspect of pons.

Adult↗
PubMed1988

[Usefulness of CT angiography for demonstrating cerebral aneurysms].

We report the usefulness of computed cerebral angiotomography (CT angiography) for demonstrating cerebral aneurysm and the clinical significance of CT angiography for ruptured cerebral aneurysm. Our modified method of CT angiography was easy and less time-consuming. Fifteen seconds after starting a single bolus injection, 1 ml/kg/25 seconds via cubital vein, of contrast medium (60% urograffin), 5 serial 5 mm thick-CT slices were scanned in every 6.5 seconds including 2 seconds of interval, beginning from an axial level 20 mm above the orbitomeatal line and ending at a level 40 mm. A total of 103 patients were examined in this report, consisting of 70 unruptured asymptomatic, 8 unruptured symptomatic (oculomotor nerve palsy) and 25 subarachnoid hemorrhage (SAH). Seven unruptured aneurysms in 4 asymptomatic cases, 2 unruptured aneurysms in 2 symptomatic cases 27 aneurysms in 24 SAH cases were suspected by CT angiography. Of these 36 aneurysms suspected by CT angiography 32 aneurysms were confirmed by cerebral angiography. The detection rate of CT angiography in this report was 89%, higher than those of previous reports. Thirteen aneurysms were located at internal carotid-posterior communicating artery (ICPC) junction. 11 at anterior communicating artery (Acom), 7 at middle cerebral artery (MCA). CT angiography showed a false positive findings in 4 cases, which were all located at Acom. Four aneurysms were not detected in CT angiography, which were all located at MCA and were very small (2-3 mm) in diameter. There were no deteriorated cases during and after CT angiography. We suggest that CT angiography is a useful and safe method for predicting the location of not only unruptured but ruptured aneurysms.

Aged↗
PubMed1987

Stereotactic operation for brain abscess.

Stereotactic management of brain abscess (stereotactic aspiration with external drainage) was performed in 14 patients. Fifteen abscesses in 14 patients were successfully aspirated by this method. After aspiration of the abscess, all patients underwent external drainage for an average of 14.5 days. No complications during aspiration or during external drainage (such as bleeding or infection, respectively) were encountered in our series. Ten out of 14 patients (71.4%) showed excellent prognosis, and 3 of 14 (21.4%) showed good outcome. Only one patient died after the operation, but this was due to lung cancer. Our operative results are quite satisfactory in comparison with operative results reported by other authors.

Adult↗
PubMed1987

Microangioarchitecture of the feline spinal cord. Three-dimensional observation of blood vessel corrosion casts by scanning electron microscopy.

The microangioarchitecture of corrosion casts of the cat spinal cord was studied by scanning electron microscopy. On the ventral surface of the spinal cord, the anterior spinal artery and the anterior spinal vein ran parallel along the anterior median fissure. Many central arteries branching from the anterior spinal artery coursed in a wavelike manner in the anterior median fissure. The number of central arteries was lowest in the thoracic spinal cord. Central arteries at some spinal cord levels revealed well-developed anastomoses with other central arteries in the anterior median fissure. These well-developed anastomotic central arteries were frequently observed in the thoracic spinal cord, in which the number of central arteries was lowest. On the dorsal surface of the spinal cord, the posterior spinal vein ran longitudinally at the midline and was drained by circumferential veins and posterior central veins. This vein formed a characteristic anastomotic plexus. Small arterioles (20 microns in diameter) in the spinal parenchyma revealed a ring-like compression at the branching site.

Animals↗