Biomedical subjects

H Yokote

Publications and source records attributed to H Yokote.

At least 37 records · Page 2Linked to original sources

PubMed1996

Clinical use of mechanical detachable coils for dural arteriovenous fistula.

Seven dural arteriovenous fistulas were successfully embolized with mechanical detachable coils. Two lesions were located in the transverse-sigmoid sinus, four in the cavernous sinus, and one in the marginal sinus. All lesions were completely occluded on postembolization angiography. No recurrent symptoms appeared during a mean follow-up period of 11 months. Owing to the length and retrievability of the mechanical detachable coils, embolization was quicker and safer, and coils were packed more densely, than is possible with conventional coils. Coil migration was avoided because coils of the appropriate size were chosen before they were placed.

Aged↗

PubMed1995

[The effect on higher cortical dysfunction of percutaneous transluminal angioplasty for internal carotid artery stenosis].

Seven patients with internal carotid artery (ICA) stenosis with higher cortical dysfunction due to hemodynamic ischemia were treated by percutaneous transluminal angioplasty (PTA). The patients ranged from 49 to 71 years of age, and included five males and two females. Neuropsychological tests were evaluated before and after PTA. Higher cortical dysfunction improved in all cases after PTA. It is concluded that PTA is effective to improve higher cortical dysfunction in patients who have ICA stenosis associated with hemodynamic compromise, if the ICA is satisfactorily dilated.

Aged↗

PubMed1994

Stenotic kinking of the cavernous internal carotid artery with a giant intra-cavernous aneurysm: case report.

We report a giant aneurysm of the cavernous internal carotid artery with proximal internal carotid stenosis. The stenosis showed two typical features: a kink at the stenosis and location at the exit from the carotid canal. We believe that the cavernous portion of the internal carotid artery is compressed medially by the giant aneurysm and a kink occurs at the point where the artery leaves the bony carotid canal.

Aneurysm↗

PubMed1994

Tissue plasminogen activator thrombolysis and transluminal angioplasty in the treatment of basilar artery thrombosis: case report.

A 61-year-old man with basilar artery thrombotic occlusion was successfully treated by a combination of local infusion of tissue plasminogen activator (t-PA) followed by percutaneous transluminal angioplasty (PTA). t-PA superselective infusion combined with the mechanical destruction of the clot by the guide wire was effective for recanalization. A Stealth dilation catheter, with a 2.5-mm balloon diameter and 10-mm length, was used for PTA. A balloon inflation time of 60 seconds with 4 atmospheres of pressure was delivered for successful dilation of the basilar artery. It was confirmed to be widely patent on follow-up angiography 40 days after the combined procedure with no further ischemic attacks apparent on clinical examination at 6 months.

Angioplasty, Balloon↗

PubMed1993

Complex occipital arteriovenous fistula associated with neurofibromatosis treated by embolization and surgery. Case report.

It is well known that neurofibromatosis is associated with various types of arteriovenous fistulas (AVF), but association with an occipital AVF has not been reported. We are reporting this case which was successfully treated with a combination of embolization and surgery. Superselective angiography defines the anatomic details of the fistula and intraoperative digital subtraction angiography (DSA) facilitates the surgery to cure the fistula. It is important to identify the best therapeutic options using angiographic information to treat a complex arteriovenous fistula.

Adult↗

PubMed1993

[Newly developed blocking balloon catheter for PTA of internal carotid artery].

We have developed a new blocking balloon system for percutaneous transluminal angioplasty (PTA) of the internal carotid artery (ICA). A latex balloon (BALT) is attached on the top of a Superselector infusion-type catheter (TORAY) which is used as a blocking balloon catheter. It can be navigated into the distal part of the ICA under torque control as well as flow control by withdrawing the core wire. Our PTA procedure is as follows, 1) insert the sheath catheter 8-9 F in size, 2) insert the PTA balloon catheter (Accent balloon, Cook) with a blocking balloon catheter through the sheath catheter, 3) navigate the blocking balloon into the distal part of the ICA, 4) introduce the PTA balloon to the stenotic portion after occlusion of the distal ICA by the blocking balloon, 5) PTA, 6) wash the lumen of the ICA with saline, 7) deflate the blocking balloon and withdraw the system. We performed PTA for 5 ICA lesions in 4 cases and got successful dilatations for all of them without complications. Our blocking balloon system is useful for performing the PTA of the ICA safely.

Aged↗

PubMed1992

Autotransplantation of peripheral cholinergic neurons into the brains of Alzheimer model rats.

Current hypotheses regarding Alzheimer's disease implicate cholinergic function. In this study, peripheral cholinergic neurons in the vagal nodosal ganglion were transplanted into the brains of Alzheimer model rats. Eighteen Sprague-Dawley strain rats were divided into three groups: 1) unoperated control rats, 2) rats that had undergone bilateral destruction of the nucleus basalis of Meynert (NBM) (Alzheimer model), and 3) the transplantation group in which the vagal nodosal ganglion was transplanted into the cerebral neocortex one week after the bilateral destruction of the Meynert nucleus. Seven weeks after the transplantation rat behaviour was assessed using psychological tests (spontaneous activity, passive avoidance response and the Hebb-Williams maze test). The Alzheimer model rats had a statistically significant increase in spontaneous activity in comparison with controls (P less than 0.01). The transplant rats showed some amelioration of this abnormal increase in spontaneous activity observed in the Alzheimer model rats. All of the control rats showed conditioned passive avoidance responses, while only one Alzheimer model rat retained is shocked-conditions behaviour before 24 hours (P less than 0.01). Three of the six transplanted rats showed complete improvement in the passive avoidance response test. In the Hebb-Williams maze test, the rats with NMB lesions made more errors than the control rats. The transplanted rats had a lower number of errors than NBM-lesioned rats but still more than the controls. Histological examination revealed many cholinergic cells in the transplanted tissue, especially in the area adjacent to the cerebral cortical surface. The present results indicate that autotransplantation of peripheral cholinergic cells ameliorates abnormal behaviour in Alzheimer model rats.

Alzheimer Disease↗

PubMed1992

A possible involvement of central atrial natriuretic peptide in cerebral cortical microcirculation.

The possible involvement of atrial natriuretic peptide (ANP) in cerebral cortical microcirculation was investigated in rats by means of laser-Doppler flowmetry and immunohistochemistry. In the laser-Doppler study, local cerebral blood flow (LCBF) changes after the administration of 10(-6) to 10(-8) mol/LANP solution or vehicle (saline solution) as an intracortical injection for 5 minutes were continuously monitored throughout the 30 minutes of the study and were expressed as percentages of preinjection values represented as 0%. The administration of 10(-6) to 10(-8) mol/LANP caused a significant decrease in LCBF; the onset of LCBF responses occurred within a few minutes after the start of the injection and the decrease in LCBF reached the maximum level within 7 to 10 minutes after the completion of the administration, after which LCBF gradually recovered. In the immunohistochemical study, no specific ANP immunoreactivity was found associated with the intraparenchymal blood vessels; however, ANP-immunoreactive neurons were observed primarily in the hypothalamus and septum, in which high concentrations of ANP-containing neurons have been identified. The data from the laser-Doppler study suggest that central ANP may produce a vasoconstriction of the intraparenchymal blood vessels, regardless of whether through direct action on these vessels or through the mediation by some system in the central nervous system. Because there is no evidence for ANP-containing nerves around these vessels, the role of central ANP in the cerebral circulation must await identification of the source of perivascular ANP.

Animals↗

PubMed1992

Meningeal melanocytoma: magnetic resonance imaging characteristics and pathological features. Case report.

A case of meningeal melanocytoma at the foramen magnum is reported in a 62-year-old man. Magnetic resonance (MR) imaging revealed characteristic signal patterns: homogeneous high intensity on the T1-weighted image and low intensity on the T2-weighted image. Light microscopy showed a histological appearance similar to that of melanotic meningioma. The ultrastructural features of the neoplastic cells were compatible with those of melanocytes, but they contained no features of arachnoidal cells. Immunohistochemical bromodeoxyuridine study revealed low proliferative activity among the neoplastic cells. The MR appearance and pathological features in this rare case of meningeal melanocytoma are demonstrated and discussed.

Humans↗

PubMed1991

[Selective vulnerability of peptide-containing neurons in cerebral ischemia; immunohistochemical study].

Histochemical changes in peptidergic and catecholaminergic neurons during ischemia were investigated in the cerebral neocortex of the gerbil. Catecholaminergic fibers were observed by catecholamine histofluorescence with glyoxylic acid solution, and peptidergic neuron systems such as vasoactive intestinal polypeptide (VIP), somatostatin (SOM), and neuropeptide Y (NPY) were observed by immunohistochemistry. Two hours after unilateral occlusion of the internal carotid artery, catecholaminergic fibers disappeared in the neocortex on the occlusion side, while peptidergic nerve fibers except for NPY fibers were intact after 2 hours of ischemia. NPY fibers had decreased in number on the occlusion side 2 hours after ischemia. VIP-, SOM-, and NPY-immunoreactive neurons showed a decrease of 60% six hours after ischemia, and these neurons completely disappeared in the cerebral neocortex 24 hours after ischemia. These results suggest that catecholaminergic neuron system is more vulnerable than the peptidergic one in ischemic event.

Animals↗

PubMed1991

[Dynamics of extracellular acetylcholine of the gerbil striatum during cerebral ischemia monitored by intracerebral microdialysis].

Neurons in the hippocampus and striatum are vulnerable to the ischemic insult. In the present study we focused on the vulnerability of acetylcholine (ACh)-containing neurons in the striatum. To determine the change of ACh content in the striatum, we employed a simple sensitive brain microdialysis method with high performance liquid chromatography electrochemical detection. Morphological change of cholinergic neurons was studied by ACh-esterase staining during ischemic insult. After bilateral carotid artery occlusion, local cerebral flow decreased less than 5 ml/min/100 g in the striatum. Ach content in dialysate for 20 min after the occlusion was elevated to 135% of the control. ACh content decreased to 15% of the control 2hs after the ischemia. Density of Cholinergic fibers and cell bodies was reduced 10 min after the ischemia and further decreased 20 min after the occlusion. Our study suggests that the transient elevation of ACh content was probably due to diffusion of ACh from destruction cholinergic terminals after the ischemic insult. The increase of ACh immediately after arterial occlusion may affect severity of ischemic damage in the brain by its excitatory effect.

Acetylcholine↗

PubMed1990

Effect of atrial natriuretic peptide on ischaemic brain oedema.

We investigated the effect of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium and potassium contents in ischaemic brain oedema. Global ischaemia (15 min) followed by recirculation (30 min) produced by a three vessel occlusion in the rat served as a model for induction of ischaemic cerebral oedema. Water content was measured by a drying-weighing method. Sodium and potassium contents were measured by means of flame photometry. The effect of ANP was evaluated by comparing these parameters of the ANP-treated group (5 micrograms/kg and 10 micrograms/kg atriopeptin) with those of the control group (administration of 0.9% NaCL). ANP did not significantly change the content of water, sodium and potassium in the preischaemic or ischaemic brain. Intraventricularly administered ANP (5 micrograms/kg and 10 micrograms/kg) caused significant decrease in the brain water (p less than 0.02) and sodium (p less than 0.01) contents after 15 min of ischaemia and 30 min of recirculation, while the brain potassium content remained unaltered. Serum osmolality, and sodium and potassium concentrations were not influenced by administration of ANP. Accordingly, ANP acts directly on the central nervous system to inhibit brain water and sodium accumulation in ischaemic brain oedema.

Animals↗

PubMed1990

Effect of atrial natriuretic peptide on ischemic brain edema: changes in brain water and electrolytes.

The effects of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium, and potassium contents in ischemic brain edema were investigated. By use of a three-vessel occlusion model, ischemic brain edema was produced in the rat brain by 15 minutes of global ischemia followed by recirculation. Water content was measured by means of a drying/weighing method; sodium and potassium contents were measured by means of flame photometry. The effects of intraventricular administration of ANP were evaluated by a comparison between the groups given 2 and 5 micrograms of atriopeptin II (treated) and those given 0.9% NaCl (sham-treated). The treated groups showed significant decreases in brain water (P less than 0.02) and sodium (P less than 0.01) contents at 15 and 30 minutes after recirculation, whereas the brain potassium contents remained unaltered. Before ischemia and immediately after 15 minutes of ischemia, intraventricularly administered ANP did not significantly change the brain water, sodium, or potassium contents. There was no significant difference in the effect on the amount of brain water and sodium between the two doses (2 and 5 micrograms). These effects of ANP were thought not to be mediated by primary changes in serum osmolality and sodium and potassium concentrations, because intraventricular administration of ANP did not change them significantly. The present results reveal that, in ischemic brain edema, ANP may act directly on the central nervous system to inhibit brain water and sodium accumulation.

Animals↗

PubMed1990

Transplantation of peripheral cholinergic neurons into Alzheimer model rat brain.

The effect of transplantation of peripheral cholinergic neurons was examined in rats with a lesion of the nucleus basalis Meynert (NBM). The rats with an NBM lesion showed abnormal increase of spontaneous activity, disturbance of memory retention, and disturbance of learning acquisition. In contrast, the rats which had received transplantation of cholinergic neurons into the cerebral cortex displayed amelioration of abnormal behavior produced by the destruction of the NBM. Morphological study (acetylcholinesterase) clearly showed survival of many transplanted cholinergic cells. The present study suggests that autotransplantation of peripheral cholinergic cells may be a possible therapy for Alzheimer's disease.

Acetylcholinesterase↗

PubMed1990

Stereotactic hyperthermia for brain tumors.

We have developed a localized hyperthermia system using computed tomography-stereotactic surgery as malignant brain tumor therapy. In an experimental study, the temperature in the area of the cat brain within 20 mm from a radiofrequency electrode reached more than 43.7 degrees C. Intravenous administration of MCNU during hyperthermia caused a significant increase of MCNU content in the heated brain as compared with a control brain. In the clinical study, localized radiofrequent hyperthermia using stereotactic surgery was performed on 7 malignant deep-seated gliomas and 21 metastatic brain tumors. Especially, combination therapy of stereotactic hyperthermia and chemotherapy was effective treatment for gliomas less than 30 mm deep in the brain.

Adolescent↗

PubMed1989

Non-Hodgkin's lymphoma involving the brain. Diagnostic usefulness of stereotactic needle biopsy in combination with paraffin-section immunohistochemistry.

A stereotactic needle biopsy was examined for applicability in diagnosing brain non-Hodgkin's lymphoma (NHL), because the procedure is far less aggressive than biopsy by open surgery. Formalin-fixed materials including four stereotactic specimens were available from nine patients with brain NHL. In addition to routine histopathology and histochemistry, paraffin-section immunohistochemistry was performed using a panel of monoclonal antibodies suited to such sections. Although several histopathological features characteristic of brain NHL could not be evaluated in three of the four stereotactic specimens owing to the small size of the specimens and partial invasion by lymphoma cells, the lesions in all cases could be characterised by immunohistochemistry. Examination for cytoplasmic immunoglobulin (cIg) was also performed, but specific identification of cIg was difficult in five cases because of diffuse background staining and passive diffusion of plasma protein into the cells during tissue processing. A review of the literature indicates the technical difficulty in cIg staining, since the incidence of cIg-positive cases in an individual study varied considerably, and lymphoma cells in 15 of 128 cIg-positive brain NHL cases have been reported to possess both light chains. From these findings, together with the relative difficulty in obtaining fresh tissues for study, it is concluded that, when the specimens are to be examined by paraffin-section immunohistochemistry using the above monoclonal antibodies, stereotactic needle biopsy is a useful, less aggressive method for diagnosing brain NHL.

Adult↗

PubMed1989

Stereotactic evacuation of hypertensive cerebellar hemorrhage using plasminogen activator.

Treatment for hypertensive cerebellar hemorrhage still remains controversial as to whether direct surgical procedure is indicated or not. This is so even after the introduction of CT scan which easily demonstrates the location and size of the hematoma and the presence of hydrocephalus. In this paper, we present our experience of 20 patients with cerebellar hemorrhage treated by stereotactic evacuation using Komai's CT-stereotactic apparatus. All the patients had vertigo, cerebellar symptoms, dysfunction of brain stem or consciousness disturbance. The hematomas on CT scan were more than 28 mm in diameter. Acute obstructive hydrocephalus occurred in 90% of the patients with hematoma 40 mm or larger in size. The patients with consciousness disturbance were immediately operated on after the attack, and a drainage tube was placed in the hematoma cavity to drain cerebrospinal fluid and liquefied hematoma for one to eight days. On the other hand, when patients with hematoma around 30 mm in diameter complained vertigo for about two weeks, they also were operated on stereotactically. After the operation, their symptoms improved rapidly. The stereotactic operation could aspirate about 85% of the estimated hematoma volume and improved the hydrocephalus, except in one case in which the patient rapidly deteriorated to coma level with a large cerebellar hemorrhage and brain stem damage. This stereotactic evacuation of cerebellar hematoma using a plasminogen activator is effective for not only the removal of hematoma, but also for the treatment of secondary hydrocephalus following obstruction of the fourth ventricle by cerebellar hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

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↗