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Biomedical subjects

K Yuki

Publications and source records attributed to K Yuki.

At least 37 records · Page 2Linked to original sources
PubMed1999

Ultrasonic assessment of vascular complications in coronary angiography and angioplasty after transradial approach.

The transradial approach has currently been accepted as an alternative entry method for coronary angiography and angioplasty. Vascular complications of this method were evaluated by 2-dimensional echo and color Doppler ultrasonic studies in 162 patients before, early (2+/-2 [mean+/-SD] days), and late (95+/-29 days) after catheterization. Mean age was 64+/-10 years, and 103 were men. Coronary angioplasty was performed in 59 patients (79 lesions) with angiographic success in 92%. Early after the procedure, segmental stenosis was noted in 35 patients (22%) and no flow in 15 patients (9%). Late after the procedure, segmental stenosis was noted in 2, diffuse stenosis in 36 (22%), and no flow in 8 (5%) patients. The cessation of radial artery pulse was unpalpable in only 2% of cases, whereas radial flow by color Doppler was undetectable in 9% early after the procedure. Late after the procedure, recanalization was observed in 60% of these occluded cases. Thirty-three of 86 patients (38%) with no flow or diffuse stenosis had radial artery diameters smaller than the sheath diameter, and 11 of 76 patients (14%) had radial artery diameters larger than the sheath diameter (p <0.01). Multivariate analysis revealed risk factors for vascular complications: (1) Radial artery diameter before the procedure was one of the significant and independent determinants of no flow both early (p = 0.06) and late (p = 0.004) after the procedure. (2) The difference in radial artery diameter and sheath size was related to the occurrence of diffuse stenosis late after the procedure (p = 0.003). (3) Diabetes mellitus was related to no flow (p = 0.05) or diffuse stenosis (p = 0.11) late after the procedure. Thus, ultrasonic evaluation of the radial artery was useful in selecting both an access route and an appropriate size of the sheath to determine early and late vascular complications.

Angioplasty, Balloon, Coronary↗
PubMed1999

Brain metastasis of Merkel cell carcinoma. Case report and review of the literature.

Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine tumor that is locally aggressive and has potential for metastatic spread. However, brain metastases are rare, and therapy for such tumors has never reported. The authors present a 48-year-old woman with MCC of the left elbow and a right cerebellar metastasis. After the right cerebellar mass was totally resected, radiation treatment and chemotherapy were performed. Eight cases of brain metastasis have been reported in the literature, but only 5 have been presented in sufficient detail for analysis. Therapy for brain metastases has always been palliative whole-brain irradiation and chemotherapy except for our patient, who underwent total removal of the tumor and survived for 11 months without neurological deficit. Except in the case of 1 with a particularly radiosensitive MCC, the patients with brain metastases died within 9 months after detection of the brain lesions. If possible, aggressive excision of brain metastases as well as of the primary lesion should be done.

Carcinoma, Merkel Cell↗
PubMed1999

Myocardial expression of endothelin-2 is altered reciprocally to that of endothelin-1 during ischemia of cardiomyocytes in vitro and during heart failure in vivo.

We and other groups have reported that endothelin (ET)-1 expression in the heart is altered in the setting of heart diseases. We have also reported that myocardial ET-1 is involved in the progression of heart failure, and that an ET receptor antagonist improves long-term survival in heart failure (Nature 384: 353-355, 1996). However, the role of myocardial ET-2 in disease states are not known. To characterize the role of ET-2, we used a) the failing hearts of rats with heart failure caused by myocardial infarction, and b) primary cultured cardiomyocytes subjected to hypoxia. In the failing heart in vivo, ET-1 mRNA increased by 390% compared with that in the non-failing heart, while ET-2 mRNA drastically decreased by 88%. Thus, gene expression of ET-1 and ET-2 was reciprocally altered in the failing heart in vivo. In in vitro studies, reciprocal alterations in ET-1 and ET-2 gene expression were also observed in isolated primary cultured cardiomyocytes, subjected to hypoxia. Specifically, acute hypoxic stress induced a significant increase (360% of the basal level) in ET-2 mRNA expression compared with that in normoxic cells, whereas it decreased ET-1 mRNA expression by 62% in primary cultured cardiomyocytes. Although these two crucial conditions, i.e., heart failure in vivo and acute hypoxic stress in vitro, are pathophysiologically distinct from each other, reciprocal alteration of ET-1 and ET-2 gene expression was observed in both cases. To further investigate the regulatory mechanism of the altered gene expression, luciferase analysis was performed using primary cultured cardiomyocytes. ET-2 promoter, which is the 5'-flanking region of preproET-2 gene (5'ET-2), showed a marked increase in luciferase activity during acute hypoxia. In contrast, the luciferase activity of 5'ET-1 (ET-1 promoter) did not change in response to hypoxic stress. The present study suggests that there are transcriptionally distinct regulatory mechanisms for ET-1 and ET-2 expression in cardiomyocytes, and therefore this study may provide a new aspect of cardiac ET system that not only ET-1 but also ET-2 can be participated in the pathophysiological conditions.

Animals↗
PubMed1998

[Multivariate analysis of intentional temporary vessel occlusion in aneurysmal surgery].

Temporary vessel occlusion (TO) for aneurysmal clipping is an effective technique to facilitate dissection between aneurysm and parent vessels, and to place a permanent clip at the aneurysmal neck precisely. However, several unsolved problems remain regarding the overall safety and risk resulting from this technique. The authors examined a series of patients in whom mannitol 500 ml, tocopherol acetate 500 mg, and phenytoin 500 mg were administered intravenously as ischemic protection during TO for the aneurysmal clipping. The study comprises a nonconcurrent retrospective analysis of 144 consecutive aneurysm clippings performed with the aid of intentional TO at the Hiroshima Prefectural Hospital from 1985 to 1995. To identify technical and patient-specific risk factors for perioperative stroke, factors studied included duration, location of the temporary clip application, number of occlusive episodes, patient sex, age, and preoperative neurological status, timing of operation, as well as postoperative, temporary or permanent, neurological deficits (ND) due to TO were used. Overall frequency of postoperative ND due to TO manifested clinically and radiologically were 9.0% and 9.7%, respectively. In both univariate and multivariate analysis there were no significant factors relevant to the ND. However, duration of the temporary occlusion time over 20 minutes was the factor most influential on the ND due to TO. Duration of the temporary occlusion time was shown to have no link with outcome. Based on our findings the authors conclude that temporary vessel occlusion within 20 minutes with anti-ischemic drugs is a relatively safe adjunct to aneurysmal surgery.

Adult↗
PubMed1997

Phosphorylation of A170 stress protein by casein kinase II-like activity in macrophages.

A170 is an oxidative stress-inducible protein having a Zinc finger domain, two PEST sequences, and many potential phosphorylation sites for serine/threonine kinases. These structural features suggest that the phosphorylation of A170 affects its function and degradation. We have found that A170 is phosphorylated in cultured murine peritoneal macrophages. In addition, using recombinant A170 proteins, we found two proteins of 40 and 44 kDa with kinase activity in cell extracts using an in-gel kinase assay. We compared the properties of the intrinsic A170 kinases with those of mitogen-activated protein kinase (ERK 2), protein kinase A (PKA), casein kinase II (CK II), and protein kinase C, since their catalytic subunits have molecular masses similar to A170 kinases. ERK 2, CK II, and PKA phosphorylated recombinant A170 as a substrate. The 40 and 44 kDa kinases present in the macrophage extract were similar to alpha and alpha' subunits of CK II in respect to substrate specificity, pharmacological properties, immuno-reactivities, and ubiquitous expression in tissues.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Low micromolar levels of hydrogen peroxide and proteasome inhibitors induce the 60-kDa A170 stress protein in murine peritoneal macrophages.

We previously reported cDNA cloning of a novel oxidative stress protein termed A170 from murine macrophages. Further experiments have demonstrated that exposure of the cells to low levels of H2O2 produced by glucose/glucose oxidase markedly induced the 60-kDa A170 protein. This result suggests that the level of A170 protein can also be controlled at posttranscriptional levels, because we showed previously that H2O2 hardly increased the level of A170 mRNA. We have found that proteasome inhibitors markedly induced the A170 protein after 2 to 8 h similarly to glucose/glucose oxidase, suggesting rapid degradation of the A170 protein by proteasome under normal conditions. Activation of cellular signaling pathways either by epidermal growth factor, lipopolysaccharide or tumor necrosis factor-alpha did not enhance the level of the A170 protein. The levels of glucose oxidase-induced A170 protein did not decrease after the addition of cycloheximide. These results suggest that low levels of H2O2 may stabilize the A170 protein, allowing it to accumulate within cells.

Adaptor Proteins, Signal Transducing↗
PubMed1997

[A case of hearing loss caused by overdrainage of cerebrospinal fluid after ventriculo-peritoneal shunting procedure].

We describe a case of intracranial hypotension syndrome due to overdrainage of cerebrospinal fluid presented with hearing loss after ventriculoperitoneal shunting procedure. A 69-year-old man suffering from subarachnoid hemorrhage presented with an angiogram showing two aneurysms, one of the right internal carotid and one of the middle cerebral artery. Neck clipping was performed. One month later, he developed normal pressure hydrocephalus (NPH), which was treated by ventriculoperitoneal (NPH), which was treated by ventriculoperitoneal shunting procedure using low pressure Pudenz system. Trias of NPH were improved by insertion of shunt system. However, he complained of hearing loss which was worsened by upright position and improved by lying down. Such kinds of phenomenon were demonstrated by audiogram showing that the transitory decrease of hearing and electrocochleography showing the elongation of N1 latency at upright position. These data suggested that his hearing loss was caused by inner ear or auditory nerve lesion. After the shunt system was replaced into the antisiphon device, his hearing disturbance improved. Axial computed tomography of bone window at the level of orbitomeatal line demonstrated widely perilymphatic duct on both sides. This finding suggested that the fluctuation of intracranial pressure was easily transmitted into the cochlear through the widened perilymphatic duct, resulting in hearing disturbance.

Aged↗
PubMed1997

[Magnetic resonance imaging of Kernohan's notch in chronic subdural hematoma].

Compression of the crus cerebri against the free edge of the tentorium contralateral to a supratentorial mass, the so-called Kernohan's notch, can be a cause of false localizing sign. Kernohan's notch has been thoroughly studied clinically and pathologically, but not radiographically. The authors describe a case of left chronic subdural hematoma, which resulted in left hemiparesis caused by Kernohan's notch. Injury to the contralateral cerebral peduncle was clearly shown by magnetic resonance imaging (MRI) performed in the postoperative period. A 43-year-old man was transferred to our hospital in deep coma with dilated pupils, unreactive to light. Computed tomography (CT) scans obtained on admission revealed a left chronic subdural hematoma and a midline shift to the right. After drainage and irrigation of the left chronic subdural hematoma through a single burr hole, his clinical condition improved gradually. But 1 month after the operation, mild left hemiparesis still persisted. MRI T2-weighted images demonstrated an abnormally increased signal area in the right cerebral peduncle. T1-weighted coronal images showed the anatomical relationship between the hypointense lesion in the right cerebral peduncle and tentorial edge. Three-dimensional-MRI (3D-MRI) clearly demonstrated the surface image of Kernohan's notch. We emphasize the utility of 3D-MRI for detecting evidence of brain stem injury, such as Kerno han's notch.

Adult↗
PubMed1997

[A surgery for an acute case of a ruptured aneurysm associated with idiopathic thrombocytopenic purpura: a case report].

A surgery for an case acute of a ruptured aneurysm with idiopathic thrombocytopenic purpura (ITP) is very rare. We encountered a case of a ruptured basilar artery (BA) superior cerebellar artery (SCA) aneurysm associated with ITP. A successful operation was carried out while the patient was in the acute stage. The patient was a 63-year-old female. She has been suffering from ITP for two years, when she experienced a sudden severe headache and vomitting on May 5, 1995. She was referred to our hospital as a case of subarachnoid hemorrhage estimated to be in group 2 according to the Fisher grade. Her neurological condition caused by the subarachnoid hemorrhage was grade 2 according to Hunt & Kosnik classification, and she was classified according to WFNS as grade 1. The number of platelets was, however, 2.3 x 10(4)/mm3 on admission. Cerebral angiography showed the aneurysm at the bifurcation of BA and SCA. The administration of platelet transfusion, betamethasone and gamma-globulin induced an increase of the number of platelets to 8.7 x 10(4) mm3 just before the operation. Neck clipping for the aneurysm was performed using platelet transfusion via the right pterional approach 25 hours after the onset. No tendency to bleed was recognized during the operation. The number of platelets was kept constantly at the level between 16.9 x 10(4)/mm3 and 22.0 x 10(4)/mm3 during the postoperative course with the administration of betamethasone. The postoperative course was good with no manifestations of delayed ischemic neurological deficits.

Acute Disease↗
PubMed1996

Murine peritoneal macrophages induce a novel 60-kDa protein with structural similarity to a tyrosine kinase p56lck-associated protein in response to oxidative stress.

Using differential screening we have cloned a cDNA encoding a novel oxidative stress protein designated A170 from murine peritoneal macrophages. It has a Zn-finger domain, a PEST domain and several potential phosphorylation sites for kinases. Treatments with oxidative stress agents such as diethyl maleate and paraquat increased a 2.0-kilobase A170 mRNA about twofold in the macrophages after 12 hours in culture. However, H2O2 or glucose/glucose oxidase did not increase the level of the A170 mRNA. Using an A170-specific antibody we have detected in the macrophages a 60-kDa protein that was induced 5 to 10 hours after the addition of the oxidative stress agents. A search of sequence databases revealed that the A170 protein is roughly 90% identical to a human protein that binds to the Src homology 2 domain of the T-cell-specific tyrosine kinase p56lck. These features suggest that the A170 protein plays a significant role in oxidative stress-responsive signal transduction in macrophages.

Adaptor Proteins, Signal Transducing↗
PubMed1996

[A case of Rathke's cleft cyst in association with anterior communicating artery aneurysm presenting a rare visual field defect].

We report a case of Rathke's cleft cyst associated with anterior communicating artery aneurysm. The patient was 60-year-old woman who developed visual disturbance two months before admission to our hospital. Visual acuity on the right was 0.06 and on the left was 0.08. The visual fields showed a complete temporal hemianopsia on the left eye and an incomplete temporal hemianopsia of the right eye with a central defect of the temporal visual field. CT and MR imagings showed an intra- and suprasellar mass lesion with no enhancement. Angiography showed bilateral A1 elevations and anterior communicating artery aneurysm. The operation was performed through interhemispheric approach. Suprasellar cystic mass compressed upward the optic nerves and chiasm, and aneurysmal dome stuck in the central region of chiasm. This anatomical disorders affected to the optic chiasm resulted in a rare visual field defect. Neck clipping of aneurysm and opening of the cyst were performed. A diagnosis of Rathke's cleft cyst was made. Following surgery, her visual fields resolved but she suffered from diabetes insipidus.

Craniopharyngioma↗
PubMed1996

[Indication of early surgery in elderly patients with ruptured intracranial aneurysms--the comparison between surgical and conservative therapy].

The purpose of this study was to investigate the indication of direct early surgery for elderly cases aged over 70 years with ruptured intracranial aneurysms. The result of early surgical treatment in 39 elderly cases was analyzed and was compared with that of conservative treatment in 39 elderly patients. According to the multiple logistic analysis, surgery was only significant factor influenced the outcome, however, Hunt & Kosnik grade (HKG), activity of daily life (ADL) before subarachnoid hemorrhage (SAH) and past history were related to the outcome. The outcome in the direct early surgical group statistically correlated (p < 0.05) with preoperative HKG, although the outcome in the conservative group did not correlate with HKG. The outcome in conservative group was miserable because of rerupture or poor preoperative neurological grade. The indication of direct early surgery for elderly cases with ruptured intracranial aneurysms should be considered as follows, HKG 1 to 3, ADL before SAH 1, no or minor past history and age under 84 since most elderly patient was 84 in our series. Direct early surgery in elderly patients seems to improve the outcome under these indications.

Activities of Daily Living↗
PubMed1995

Choroid plexus carcinoma in the lateral ventricle--case report.

A 68-year-old male presented with choroid plexus carcinoma in the left lateral ventricle manifesting as dysarthria and gait disturbance. Magnetic resonance imaging showed a homogeneously enhanced mass in the trigone of the left lateral ventricle. Selective left posterior cerebral arteriography showed the tumor was fed by the left medial posterior choroidal artery. Detailed examinations found no evidence of an extraneural primary focus. He underwent partial removal of the tumor followed by local Lineac irradiation (50 Gy). After irradiation, the serum level of carcinoembryonic antigen decreased and the size of the residual tumor was reduced.

Adenocarcinoma↗
PubMed1995

[A case of dural arteriovenous malformation in the anterior fossa associated with an occlusion of the unilateral middle cerebral artery with moyamoya phenomenon].

The authors report a case of dural arteriovenous malformation (dAVM) in the anterior fossa that was associated with an occlusion of the unilateral middle cerebral artery with Moyamoya phenomenon. The patient was a 79-year-old man referred to our department with an episode of consciousness disturbance and headache. Computed tomography scan showed intracerebral hematoma in the left frontal lobe, combined with left frontal subdural hematoma and subarachnoid hemorrhage. Angiography revealed dAVM in the left anterior fossa, fed by the bilateral ethmoidal and the bilateral middle meningeal arteries, and draining into the superior and inferior sinuses through the pial veins with vascular sacs. While angiography revealed an occlusion of the right middle cerebral artery (M1 portion) good collaterals via leptomeningeal anastomosis had developed. T1-weighted magnetic resonance (MR) images showed an intracerebral hematoma as a low intensity area, and flow-void areas were indicative of vascular sacs. Time-of-flight MR angiography also clearly showed dAVM in the left anterior fossa. Co-existence of an occlusion of an intracranial major artery and dAVM in this location has not been reported previously and it was speculated that this association had occurred by chance.

Aged↗
PubMed1994

In vitro chemosensitivity test of human brain tumors using a three-dimensional organ culture with a collagen gel matrix.

We evaluated the usefulness of an in vitro tumor organ culture system using a specialized collagen gel matrix derived from pig skin as a chemosensitivity test for human brain tumors. Two xenograft tumors derived from human glioblastoma and medulloblastoma were examined with this system and the results were compared with data obtained from a nude mouse assay. Xenograft tumors exhibited in vivo-like three-dimensional growth on the collagen gel matrix and had increasing incorporation of tritiated (3H)thymidine for 2 weeks. Drug sensitivity, as measured by this assay at therapeutic peak plasma concentrations of anticancer drugs, corresponded with that measured with the nude mouse assay. Chemosensitivity of 16 surgical specimens of malignant brain tumors were also examined successfully by this collagen gel matrix (CGM) assay. When the highest inhibition rate in dose-inhibition curve was equal to or greater than 50%, the tumor was regarded to be sensitive to the agent. The efficacy rates in CGM assay for 16 lesions were 25.0% (4/16) for ACNU, 67.8% (11/16) for adriamycin, 31.3% (5/16) for cisplatin, and 67.8% (11/16) for etoposide. The CGM assay has advantages as a chemosensitivity test because of its simple procedure, rapidity, high rate of evaluable tumor growth, and in vivo-like three dimensional tumor growth. Our results indicate that the CGM assay is feasible to test the chemosensitivity of malignant brain tumors.

Animals↗
PubMed1994

[A case of hemangioblastoma in the thalamus].

Supratentorial hemangioblastoma is encountered very rarely. About 80 cases in all have been reported. The authors present a case of supratentorial hemangioblastoma in the thalamus with gradually enlarging cysts. The patient was a 45-year-old man with complaints of left hemiparesis and headache. Computed tomographic scans of the brain showed a cystic mass with mural nodule in the right thalamus. Left vertebral angiography demonstrated a vascular tumor fed by a thalamogeniculate artery. A right temporo-parietal craniotomy was performed and the tumor was totally resected through the transcortical approach. The histological diagnosis was hemangioblastoma. Post-operative course was good except for a minor complication of the left lower quadrant homonymous hemianopsia and left hemiparesis which had disappeared at the time of discharge.

Hemangioblastoma↗