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Biomedical subjects

K Yada

Publications and source records attributed to K Yada.

At least 73 records · Page 4Linked to original sources
PubMed1992

[The neurological outcome in patients with acute cervical spinal cord injury].

UNLABELLED: Twenty-three patients (twenty males and three females) with acute cervical spinal cord injury were cared for within a defined protocol and followed for 14 to 589 days (mean. 133 days). We evaluated the relationship between neurological recovery and neurological examination, myelography (MLG), CT-myelography (CTM) on admission. All of them were admitted to Kitasato University Hospital within 24 hours after injury. Thirteen of the 23 patients had complete injury, and the others had incomplete injury. RESULT: Four factors were found to be related to neurological recovery. They included: 1) complete injury; 2) areflexia; 3) cord swelling on CTM; and 4) complete block on MLG. Fourteen of 15 patients who had at most two of the four factors improved. But, no patients with three or four factors improved. CONCLUSION: These four factors have been recognized as indicators of bad neurological outcome. However, our result indicates that by our result, improvement of neurological function can be expected in patients affected by only one or two of these four factors. In other words these four factors have prognostic value for predicting the neurological outcome after acute cervical spinal cord injury.

Acute Disease↗
PubMed1992

[Preoperative embolization for meningiomas using PVA particles].

Preoperative embolization for highly vascularized and large meningiomas is an indispensable technique for facilitating their surgical removal by decreasing blood loss during the operation. This is a report of 4 large and highly vascularized meningiomas in the skull base, on which embolization of feeders was performed preoperatively by PVA (Polyvinyl alcohol foam) particles (150-250 micron produced by INGENOR CO, Paris) and small strips of gelfoam (0.5 x 0.5 x 3-5mm). Under EEG monitoring, Isosorbide dinitrate was used for prevention and relief of vascular spasm. Lidocaine injection tests (Xylocaine 2%: 50mg mixed in equal volumes with Iopamiron 300) were performed for checking before embolization. In the intracranial portion, standard taper steerable guide wire was changed to seeker flexible soft-tip guide wire. In two cases, the meningioma was located in the medial part of the sphenoidal ridge. In the other two cases, one meningioma was in the lateral part of the sphenoidal ridge and the other was in the olfactory groove. In all 4 cases, we successfully performed embolization without complication. In one case, we had to perform embolization twice, because of revascularization detected by angiography 3 weeks after the first embolization. In this latter case, we had performed central embolization only, by using PVA particles, having left feeder without occlusion (peripheral embolization) using gelfoam. The result suggested that it was also necessary to perform peripheral embolization especially if the tumor is fed by large tortuous and irregular abnormal vessels. Peripheral embolization may prevent PVA particles from washing out and causing progressive thrombosis by PVA particles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Intramedullary neurofibroma in the cervical spinal cord; a case report].

A 62-year-old woman was admitted complaining of clumsiness in both hands. On neurological examination, bilateral hand muscles were weak, both legs were spastic and hyperreflexic, all the extremities were hypoesthetic. Urological examination revealed detruser sphincter dyssynergia. Spinal CT scan demonstrated an iso density mass lesion in the cervical spinal cord, and it was markedly enhanced. On MRI, it was also markedly enhanced by Gd-DTPA. The operative finding was that an oval shaped tumor was buried in the spinal cord and was totally removed. Its histological diagnosis was neurofibroma. Intramedullary neurofibroma is rare and only 18 cases have been reported. In this case the tumor seemed to have arisen at the root entry zone and to have grown sub-pially.

Female↗
PubMed1991

Meningiomas differentiating to arachnoid trabecular cells: a proposal for histological subtype "arachnoid trabecular cell meningioma".

Three cases of meningiomas which had abundant small vacuoles in the tumor tissue are reported. By electron microscopy, the tumor cells exhibited long and thin processes, the tips of which were united by desmosomes. The tumor tissue was revealed to have wide extracellular spaces which corresponded to the vacuoles observed by light microscopy. In previous literature, various terms have been used when referring to this meningioma, such as microcystic meningioma or vacuolated meningioma. Since the ultrastructure of the tumor showed similarity to that of normal arachnoid trabecular cells, we propose to call the tumor "arachnoid trabecular cell meningioma" denoting its morphological nature clearly.

Cell Differentiation↗
PubMed1991

Capsular and thalamic infarction caused by tentorial herniation subsequent to head trauma.

Five patients (4 male and 1 female) were observed to have capsular and thalamic infarction ascribed to descending transtentorial herniation (DTH) caused by head injury. A lucid interval immediately after the trauma and the presence of an epidural hematoma (EDH) characterized all five cases. At the time of hospitalization consciousness was seriously impaired and signs of cerebral herniation were apparent. Two to four days after the trauma, low attenuation in the computed tomography (CT) images pinpointed intracerebral damage in the anterolateral part of the thalamus and in the internal capsule on the same side as that of the EDH in three patients, and in the other two patients bilateral thalamic and capsular damage was noted. The low attenuation implicated the perforating arteries, that is the anterior thalamoperforating and anterior choroidal arteries, suggesting infarcted regions caused by occlusion of these arteries. Findings in the present study suggest that arterial occlusion in closed head injury may result from DTH. Moreover, infarction may be attributed to the delayed effects of injury.

Adult↗
PubMed1991

Hemorrhagic venous infarction after excision of an arteriovenous malformation: case report.

A case of arteriovenous malformation (AVM) in which postoperative hemorrhagic infarction developed, probably because of occlusion of the former draining veins, is reported. The hemorrhage developed in the temporal lobe 3 days after the initial operation and was located in the immediate vicinity of the site of the AVM. The following findings suggest that the postsurgical hemorrhage probably resulted from a venous thrombosis: 1) no evidence of residual AVM; 2) delayed onset of the hemorrhage, inconsistent with the time course of a hemorrhage developing according to the breakthrough theory or with insufficient hemostasis with a high-pressure afterload; 3) good correlation between the location of the hemorrhage and the occlusion of the draining veins; and 4) multifocal hemorrhage affecting both the gray matter and the subcortical white matter. Postoperative hemorrhagic infarction caused by thrombosis in the draining veins is rare, but it should be considered as a distinct postoperative complication after removal of an AVM.

Cerebral Hemorrhage↗
PubMed1991

Fenestration of the intracranial internal carotid artery--case report.

A rare case of fenestration of the intracranial internal carotid artery (ICA) was identified by angiography in a 51-year-old female with suspected subarachnoid hemorrhage. Only two similar cases have been reported previously. Fenestration tends to develop on the right side and near the bifurcation of the ophthalmic artery. Congenital factors at the 4 mm embryonic stage may be involved in the fenestration of the intracranial ICA.

Carotid Artery, Internal↗
PubMed1990

Neurinoma of the oculomotor nerve--case report.

Only 10 cases of oculomotor nerve neurinoma have been reported previously. The authors report the rarity of a neurinoma originating from Schwann cells of the oculomotor nerve. The diagnosis was based on the initial sign of oculomotor nerve paresis without involvement of other cranial nerves, neuroradiological and surgical findings, and histological features of the specimen obtained at surgery.

Aged↗
PubMed1990

Retrograde thrombosis of feeding arteries after removal of arteriovenous malformations.

Five cases of retrograde thrombosis of former feeding arteries after removal of an arteriovenous malformation (AVM) are reported. The clinical features of these patients were studied and compared to those of 71 patients without this complication. The following characteristics were found to correlate with retrograde thrombosis: 1) advancing age of the patient; 2) large AVM size; and 3) markedly dilated and elongated feeders. It is suggested that the slow flow in the former feeding arteries that was observed immediately after AVM removal and pathological changes in these vessels due to long-standing hemodynamic stresses contributed to the development of retrograde thrombosis. Neurological manifestations related to retrograde thrombosis were noted in three of the five cases. Although infrequent, this complication should be considered as a serious possibility following removal of an AVM.

Adolescent↗
PubMed1990

[Clinical feature and pathophysiology of compression myelopathy].

In treating compressive lesions to the spinal cord, it is essential to understand underlying pathophysiology which causes compression myelopathy. When the spinal cord is compressed by static lesions, such as very slowly expanding extramedullary benign tumors, function of the white matter remains unaffected till later stage. Even in advanced cases, in which the function has been markedly affected, the function recovers remarkably following to surgical removal of the lesion. These phenomena have been proved by neurophysiological and clinical evidence. In cases with spondylotic myelopathy, dynamic factors, such as hyperextension of the neck, play more important role than the size of bony spurs, herniated discs or ossified posterior longitudinal ligament. In these cases, function of the white matter is more easily affected than in cases with static compression. The gray matter is more vulnerable than the white matter. In cases which exhibit slow finger opening, it was proved that the interneuronal connection was affected. In cases with myelopathy caused by overstretch mechanism, main lesion is limited to the gray matter. Based on several experimental works, it was suggested that venous engorgement probably is the main cause which affects the gray matter.

Adult↗
PubMed1990

[Surgical treatment and long-term results of aneurysms of Valsalva sinus in 24 cases].

Twenty-four patients with aneurysm of Valsalva sinus were surgically repaired over a 23 year period (1965-1988). These patients were ranged 2 to 54 years of age and eleven of them were male. Rupture of aneurysm of Valsalva sinus was combined with aneurysm in 20 cases, ventricular septal defect in 12 cases and aortic regurgitation in 6 cases. At present, our routine operative procedure for ruptured aneurysm is direct closure of the defect with patch closure of aneurysm after resection of the aneurysm, but when the diameter of aneurysm is smaller than 7 mm, direct closure of the defect of the aneurysm was used. Only one patient after patch closure of ruptured sinus of Valsalva (Konno type I) required reoperation for penetration into left ventricle. This case might be avoided if patch was sutured to annulus of aortic valve. There were two operative death and one late death. The former died of cerebral infarction and low output syndrome, the latter died of sepsis. The mean follow-up period (+/- standard deviation) was 8.2 +/- 6.0 years. All patients that were followed were thirteen and found to be in New York Heart Association class I.

Adolescent↗
PubMed1990

[Asynchronus rejection of intrathoracic heart-lung transplantation rats].

We have reported intrathoracic heart-lung transplantation in rats could be made easily by using Internal Shunt Method as described elsewhere. In this study, we examined the rejection of intrathoracic heart-lung allografts in this model to determine whether acute pulmonary rejection precedes cardiac rejection following heart-lung transplantation or not. Ten heart-lung allografts (no immunosuppressive agent was given) and four isografts were examined pathologically. There was no pathologic change except perivascular or peribronchiolar edema in isografts, which was attributed to operative damage. Acute pulmonary rejection apparent pathologically 3 days after transplantation and lung allografts lost its function 6 days after transplantation. Otherwise, acute cardiac rejection first became apparent pathologically 5 days after transplantation. And their pulsation appeared well 6 days after it. It is concluded that pulmonary rejection precedes cardiac rejection following heart-lung transplantation.

Animals↗
PubMed1989

Studies of refractory carbides, nitrides, and borides as the thermionic emitters for electron microscopy.

Thermionic emission properties of several kinds of refractory carbides, nitrides, and borides of the transition metals in the form of powder were investigated with a newly developed measuring device and evaluated by the figure of merit defined as the ratio of the effective work function to the working temperature at which the vapor pressure becomes 1 x 10(-5) Torr. There are several materials whose thermionic emission properties are better than those of tungsten or compatible to those of tungsten among the carbides and borides, such as TaC, HfC, ZrC, LaB6, and CeB6, as judged by the figure of merit. New preparation methods for carburization, nitriding, and boriding of the wires of matrix metals and alloys were successfully developed for using these materials as the cathode of the electron microscope. Other necessary techniques such as spot welding and electrolytic etching were also developed. From the brightness characteristics, it was found that some of carbides, carbide solid solutions, and borides such as HfC, ZrC (Ta0.8-0.7Hf0.2-0.3)C, TaB2, and HfB2 are very good emitters comparable to LaB6. It is emphasized that the work functions of the carbide-solid solutions (Ta0.8Hf0.2)C and (Ta0.7Hf0.3)C, which have low rates of evaporation at high temperature, show no remarkable rise as compared with that of HfC, so that their figures of merit are better than that of HfC. Feasibility of providing good cathodes with HfC and (Ta0.8Hf0.2)C tips was demonstrated by taking high-resolution electron micrographs.

Boranes↗
PubMed1989

Clear cell ependymoma. A histological variant with diagnostic implications.

Four cystic brain tumours, one from the frontal lobe, one in the third ventricle and two in the cerebellum, were studied histologically including immunostaining and electron microscopy. Anatomically, all the tumours were located within or adjacent to the ventricular system. By light microscopy, the tumours had a largely honeycomb pattern and were made up of clear cells. Some of the clear cells showed positive for GFAP. Leu 7, Factor VIII and NSE were negative. Electron microscopy of the areas with clear cells revealed densely packed polyhedral cells with clear cytoplasm. They had well developed intercellular junctions, microvilli and some cilia which confirmed their ependymal derivation. Perivascular pseudorosettes or papillary features were only seen in limited areas, where GFAP was strongly positive in the tumour cell processes. As these tumours mimic oligodendroglioma and cerebellar haemangioblastoma, they are called as "clear cell ependymoma" to obviate such errors in diagnosis.

Adult↗
PubMed1989

Cranial burr hole for revascularization in moyamoya disease.

Currently, superficial temporal artery-middle cerebral artery (MCA) anastomosis, encephalomyosynangiosis (EMS), and encephalo-duro-arterio-synangiosis are used to treat moyamoya disease and are reported to effectively improve ischemic symptoms. All are methods of reversing the flow of blood from the external carotid artery system into the cortical branches of the MCA. As moyamoya disease advances, these operations alone will predictably not correct the deterioration in blood flow in the territory of the anterior cerebral artery. It was noted in a case of moyamoya disease with intraventricular hemorrhage that a burr hole, made in the frontal region for drainage purposes, induced marked neovascularization. Since then, similar frontal burr holes have been made in five juvenile cases of moyamoya disease; this procedure involved making a burr hole in both frontal bones and incising both the dura and the arachnoid membrane. In two cases a frontal burr hole in both frontal bones and incising both the dura and the arachnoid membrane. In two cases a frontal burr hole was placed simultaneously with EMS, and in the others the frontal burr hole was made following EMS. The clinical symptoms improved after the frontal burr hole was made, and dynamic computerized tomography revealed improved circulation in the frontal regions. Together with conventional surgical therapy for juvenile cases of moyamoya disease, this operation is considered beneficial both to the circulation in the frontal region and for the protection of frontal brain function.

Arterial Occlusive Diseases↗
PubMed1989

Target materials suitable for projection X-ray microscope observation of biological samples.

Trials for improving the contrast of projection X-ray images by finding better target materials than Ti (lambda K alpha: 2.75 A), which has been found to be suitable for many kinds of specimens, were carried out, considering the factors of melting point, thermal conductivity, mechanical strength, chemical stability, absorption of the X-ray, etc. Au, Ta, and Ge were found to be suitable, giving 5-10 A X-rays when low electron beam energies around 10 kV were used. In order to take advantage of the long wavelength X-rays of these targets, we tried to minimize the attenuation of the imaging X-rays in the air or to use a vacuum camera. Even in non-stained biological samples such as HeLa cells and lingual muscle section, their microstructures were visible with sufficient contrast.

Animals↗
PubMed1989

[Blunt injury of the vertebral artery: report of three cases].

The authors reported three cases, whose vertebral arteries had been injured by blunt trauma to the neck which was followed by cerebello-brainstem infarctions. Case 1: a 32-year-old man, who developed severe vertigo and nausea 7 days after a traffic accident. He showed neck pain and horizontal nystagmus on admission. Three days later, he became drowsy. CT scan of the head demonstrated right-side cerebellar infarction, and the angiography revealed an occlusion of the right vertebral artery at C4-5 level. After the removal of the right cerebellar hemisphere, he recovered neurologically and was discharged from the hospital, able to walk. Case 2: a 47-year-old man, who suddenly became comatose 6 hours after an accident. Plain CT demonstrated a highly dense basilar artery. Angiography revealed the occlusion of the left vertebral artery, and severe stenosis of the right vertebral artery. The basilar artery was not visualized. Anticoagulant therapy was started immediately. He survived, but he developed locked-in syndrome. Case 3: a 53-year-old man, who developed transient apnea after an injury. On admission, neurological examination showed horizontal nystagmus, weakness of his right upper limb, and sensory disturbance in the left side of the body. Neck traction was done for spinal C1 and C2 fractures. Twenty-one hours after the injury, he became comatose suddenly. The four-vessels angiography revealed the occlusion of both vertebral arteries. The basilar artery was visualized through the posterior communicating arteries. He died on the 6th day after the trauma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗