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Biomedical subjects

M Komiyama

Publications and source records attributed to M Komiyama.

At least 91 records · Page 5Linked to original sources
PubMed1998

Progress towards synthetic enzymes for phosphoester hydrolysis.

Synthesis of artificial enzymes for catalyzing phosphoester hydrolysis has been attracting interest for a long time. The remarkable discovery that lanthanide ions catalyze the hydrolysis of DNA and RNA spurred the trend. Currently, progress is being made, mainly in the preparation of homogeneous catalysts, the promotion of catalytic activity by using acid/base cooperation within catalysts, the detailed understanding of the reaction mechanisms involved, and the design of artificial enzymes expressing high specificity and catalytic turn-over.

Catalysis↗
PubMed1998

Endovascular treatment of intractable oronasal bleeding associated with severe craniofacial injury.

BACKGROUND: Severe craniofacial injury may cause intractable oronasal bleeding, which is refractory to conventional treatments. This study will evaluate the efficacy of endovascular treatment for such oronasal bleeding. METHODS: Nine males between the ages of 19 and 62 years who had intractable oronasal bleeding resulting from severe craniofacial injuries received treatments of transarterial embolization using Gelfoam pledgets, polyvinyl alcohol particles, or platinum coils. We then reviewed their clinical and neuroradiologic characteristics retrospectively. RESULTS: In all but one case, angiography demonstrated bleeding points as extravasation. These bleeding points were multiple in seven cases. Except for bleeding from ethmoidal arteries, selective embolization was successful. In all cases, intractable oronasal bleeding was controlled. Patient survival was not directly related to oronasal bleeding, but rather was strongly correlated with associated brain injuries. CONCLUSION: Endovascular treatment is an acceptable treatment for intractable oronasal bleeding associated with severe craniofacial injuries when conventional treatments have failed.

Adult↗
PubMed1998

Bilateral dissecting aneurysms of the vertebral arteries resulting in subarachnoid hemorrhage: case report.

OBJECTIVE AND IMPORTANCE: We present the case of a patient with bilateral dissecting aneurysms of the vertebral arteries resulting in subarachnoid hemorrhage. CLINICAL PRESENTATION: A 44-year-old man suffered a sudden onset of severe occipital headache and nausea and then dysphasia caused by subarachnoid hemorrhage. A computed tomographic scan demonstrated right side dominant subarachnoid hemorrhage mainly in the posterior fossa. Angiography revealed bilateral, vertebral dissecting aneurysms. The right aneurysm was larger and had a bleb-like protrusion, which strongly suggested a causative lesion of the subarachnoid hemorrhage. Six months later, the patient was referred to our hospital for further evaluation and treatment. INTERVENTION: The ruptured right aneurysm was trapped surgically through a lateral suboccipital approach. The patient's postoperative course was unremarkable, and he was discharged on the 14th day after surgery. However, postoperative angiography demonstrated slight enlargement of the left nonruptured aneurysm. Four months after surgery, the patient developed brain stem ischemic symptoms. The angiography conducted at that time showed further enlargement of the left aneurysm. Five months after surgery, fatal rupture of the left aneurysm occurred. CONCLUSION: These results indicate that sacrifice of the unilateral vertebral artery may result in an enlargement of the contralateral nonruptured aneurysm and may thus be dangerous in the case of a patient with bilateral dissecting aneurysms.

Adult↗
PubMed1998

Moyamoya disease and pregnancy: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Many female patients with moyamoya disease are of childbearing years, including those who were diagnosed before entering their childbearing years. However, there have been no extensive reviews of the management of pregnancy and delivery in association with moyamoya disease. The purpose of this report is to describe the case of a patient with moyamoya disease complicated by pregnancy and to review the literature on other such cases. CLINICAL PRESENTATION AND INTERVENTION: We report a 23-year-old primipara with moyamoya disease who delivered uneventfully by cesarean section under spinal anesthesia at 38 weeks of gestation. In the literature, 30 cases were reported of patients who had been diagnosed with moyamoya disease before pregnancy and delivery, and 23 patients who were symptomatic and were diagnosed for the first time with moyamoya disease in association with pregnancy. CONCLUSION: There is no evidence that pregnancy increases the risk of cerebrovascular accident or that bypass surgery decreases its risk. Poor prognosis of the patient or the newborn is mostly caused by cerebral hemorrhage and not by cerebral ischemia. It is important to control blood pressure and especially to avoid toxemia during pregnancy. Either cesarean section or vaginal delivery can be accomplished safely. Any anesthetic method can be used, provided special attention is given to avoiding hypocapnia, hypotension, and hypertension. Oral contraceptives should be avoided.

Adult↗
PubMed1998

Magnetic resonance imaging features of unusually dilated Virchow-Robin spaces--two case reports.

Two patients presented with unusually dilated Virchow-Robin spaces appearing as cystic lesions of varying size with signal intensity identical to the cerebrospinal fluid on all magnetic resonance pulse sequences. However, fluid-attenuated inversion-recovery (FLAIR) images disclosed small, high intensity foci adjacent to these cystic lesions in one patient. These high intensity foci on FLAIR images may represent chronic ischemic change, which produces the gradual dilation of the Virchow-Robin spaces.

Adult↗
PubMed1998

Embolic stroke in the territory of a cerebellar arteriovenous malformation--case report.

A 63-year-old male presented with an embolic stroke in the right medial inferior cerebellum. Angiography at 2 and 8 months after the stroke revealed arteriovenous shunts from the vermian branch of the right posterior inferior cerebellar artery of the right inferior vermian vein. The shunts mimicked the arteriovenous shunts of post-recanalization in acute ischemic stroke, but were finally diagnosed as a pre-existing congenital arteriovenous malformation based on their persistence. Arteriovenous shunts that persists more than 2 weeks after ictus should be differentiated from the post-recanalization arteriovenous shunts of ischemic stroke, as the different etiology may affect the ultimate prognosis and course of treatment.

Cerebellum↗
PubMed1998

Prospective analysis of complications of catheter cerebral angiography in the digital subtraction angiography and magnetic resonance era.

Permanent and temporary neurological complications of catheter cerebral angiography were prospectively evaluated in 500 consecutive diagnostic cerebral angiographic procedures, 268 performed on 213 males and 232 on 175 females. Complications were divided into permanent (> 1 week), reversible (< or = 1 week, > 24 hours), and temporary (< or = 24 hours). There were four permanent (0.8%), one reversible (0.2%), and nine temporary neurological complications (1.8%). There was no death. With the correct selection of patients, catheter cerebral angiography is considered to be safe with acceptable rates of complications.

Aged↗
PubMed1998

Cerebellar mutism after basilar artery occlusion--case report.

A 30-year-old female became comatose due to embolic occlusion of the basilar artery, caused by surgical injury to the origin of the vertebral artery during removal of a neurinoma in the upper thoracic paravertebral region. The basilar artery occlusion was treated by local fibrinolysis through a microcatheter. Two weeks later she recovered her consciousness but suffered mutism. Her speech disturbance was characterized by severe ataxic dysarthria known as "cerebellar mutism" but without cranial nerve paresis. The mutism gradually improved during the following 3 months. This is case of cerebellar mutism was apparently due to ischemic stroke. Disturbance by hypoperfusion of the cerebellum and brain stem may have been involved in the pathogenesis of cerebellar mutism.

Adult↗
PubMed1998

Rupture mechanism of a thrombosed slow-growing giant aneurysm of the vertebral artery--case report.

A 76-year-old male developed left hemiparesis in July 1991. The diagnosis was thrombosed giant vertebral artery aneurysm. He showed progressive symptoms and signs of brainstem compression, but refused surgery and was followed up without treatment. He died of rupture of the aneurysm and underwent autopsy in March 1995. Histological examination of the aneurysm revealed fresh clot in the aneurysmal lumen, old thrombus surrounding the aneurysmal lumen, and more recent hemorrhage between the old thrombus and the inner aneurysmal wall. The most important histological feature was the many clefts containing fresh blood clots in the old thrombus near the wall of the distal neck. These clefts were not lined with endothelial cells, and seemed to connect the lumen of the parent artery with the most peripheral fresh hemorrhage. However, the diameter of each of these clefts is apparently not large enough to transmit the blood pressure of the parent artery. Simple dissection of the aneurysmal wall by blood flow in the lumen through many clefts in the old thrombus of the distal neck may be involved in the growth and rupture of thrombosed giant aneurysms of the vertebral artery.

Aged↗
PubMed1998

Middle cerebral artery variations: duplicated and accessory arteries.

PURPOSE: Our goal was to analyze the anatomic similarity between the duplicated middle cerebral artery (MCA) and the accessory MCA and their relationship to the early branches of the MCA. METHODS: We reviewed stereoscopic angiograms of duplicated MCAs in four patients and accessory MCAs in four patients with reference to the origin, size, and cortical supply of these anomalous vessels, along with the presence of perforating arteries and the recurrent artery of Heubner (RAH). RESULTS: The duplicated MCAs supplied the cortical territory of the temporopolar and the anterior temporal and/or middle temporal arteries. The accessory MCAs supplied the cortical territory of the orbitofrontal and/or prefrontal arteries. The duplicated MCAs had perforating arteries in three of four cases and coexisted with the RAH in three of four cases, whereas the main MCA had perforating arteries in all four cases. The accessory MCA had perforating arteries in all four cases and coexisted with the RAH in three of four cases, whereas the main MCA had perforating arteries in one of four cases. CONCLUSION: A consistent cortical supply by the duplicated MCA and the accessory MCA to the anterior temporal lobe and the anterior frontal lobe, respectively, and its similarity to the cortical supply by the early branches of the MCA suggest that development of duplicated and/or accessory MCAs is an anomalously early ramification of the early branches of the MCA.

Adult↗
PubMed1998

[Indications for external ventricular drainage after clipping of ruptured aneurysms in the acute stage].

The indication for external ventricular drainage after clipping of ruptured aneurysms in the acute stage is evaluated. Since 1990, 234 patients who presented with subarachnoid hemorrhage (SAH) and underwent aneurysmal clipping in the acute stage were evaluated retrospectively. Patients with ventricular dilatation had intraoperative placement of a ventriculostomy to obtain intraoperative brain relaxation, but the ventricular catheter was removed at the end of the surgery. All these patients were managed postoperatively in a similar fashion with no ventricular drainage, avoidance of dehydration complemented by a course of sodium ozagrel and nicardipine or fasudil hydrochloride. Acute hydrocephalus was defined as clinically and radiographically demonstrated ventricular dilatation that developed within 2 weeks of the onset of SAH and that required ventricular drainage. Three surgical approaches were employed; pterional approach (PA) for the aneurysms of the anterior circulation and upper basilar artery in 207 patients, interhemispheric approach (IHA) for the aneurysms of the pericallosal artery in 11 patients and lateral suboccipital approach (LSA) for the aneurysms of the vertebral arteries in 16 patients. No significant differences were found among these three approach groups in Fisher CT classification and the Hunt & Kosnik gradings. Four patients developed acute hydrocephalus within two weeks of surgery: three patients were operated on via LSA and one through IHA. Compared to the IHA or LSA, PA was superior for reestablishing cerebrospinal fluid circulation, because it is possible to remove more subarachnoid clot in the basal cisterns than to do so in the other two approaches. Opening of the lamina terminalis and the Liliequist membrane are also possible using PA. In conclusion, PA can prevent development of acute hydrocephalus, whereas postoperative ventricular drainage may be necessary in patients operated upon via IHA or LSA.

Acute Disease↗
PubMed1998

[Management of elderly patients with incidentally discovered unruptured aneurysms].

Long-term natural history of unruptured cerebral aneurysms is not found frequently. Hence, the indications for surgery on unruptured asymptomatic cerebral aneurysms are still unclear. The benefit of treatment ultimately depends on the relative risk of subsequent aneurysm rupture in untreated patients versus the risk involved in surgery. Clinical features of fourteen elderly patients aged over 70 years with incidentally discovered unruptured aneurysms were analyzed. Two were male and 12 were female, with ages ranging from 70 to 82 years (mean: 74.5 years). Aneurysms were located in the anterior circulation in 13 patients and in the posterior circulation in 1 patient. One patient had multiple aneurysms, that is, bilateral middle cerebral aneurysms. The size of all these aneurysms was less than 10 mm. The indication for surgery was determined case by case. General information about the natural history of incidentally discovered aneurysms was given to the patients and their relatives. Informed consent was based on the fact that subarachnoid hemorrhage was associated with a poor prognosis, while excellent operative results were common in patients with unruptured aneurysms. Five patients agreed to surgical treatment. Four of them, their ages being 70, 70, 72 and 72 years old, with aneurysms located on the middle cerebral arteries, underwent neck clipping of their aneurysms with no operative morbidity or mortality. However, the remaining one patient was not recommended for surgery in spite of her consent to having it, because of her high age (82 years) and the location of her aneurysm (intracavernous internal carotid artery). Consequently, 10 patients who didn't receive surgery were followed-up at periods ranging from 3 months to 7 years. Two patients developed rupture of the aneurysms, either proven (one patient) or presumed (one patient). The former patient made an uneventful recovery after surgery, but the latter died. None of the remaining eight patients have experienced rupture of the aneurysms. It is our clinical impression, however, that they harbor an unruptured aneurysm with at least mild trepidation. With the rapid aging of the population, withholding aneurysm surgery merely because a patient is elderly may not necessarily be the most appropriate decision. Our conclusions are as follows: (1) Elderly patients in their early seventies are apt to agree to having surgical treatment for their unruptured aneurysms. (2) The cases reported herein show that asymptomatic middle cerebral artery aneurysms were able to be clipped very safely. (3) Most patients have experienced a decrease in quality of life from knowing they are living with an unruptured aneurysm.

Age Factors↗
PubMed1998

Traumatic carotid cavernous sinus fistula: serial angiographic studies from the day of trauma.

BACKGROUND AND PURPOSE: The purpose of this study was to ascertain the early angiographic features characteristic of traumatic carotid cavernous sinus fistulas (CCFs). METHODS: Eight patients with severe craniofacial injuries underwent emergency diagnostic and therapeutic angiography for intractable oronasal bleeding, starting on an average of 6.7 hours after trauma. Carotid angiograms and the clinical manifestation of traumatic CCFs were then reviewed retrospectively to determine characteristic angiographic features. RESULTS: In four of the eight patients, no arteriovenous fistulas were found in the cavernous sinuses and symptomatic CCF did not occur during the follow-up period. In the remaining four patients, dural CCFs (Barrow type B) were observed, unilaterally in three patients and bilaterally in one. One of these four patients subsequently became symptomatic and required transarterial coil embolization. CONCLUSION: Traumatic dural CCFs are frequently observed in the early stage of severe craniofacial trauma, if investigated. Although their spontaneous disappearance is known, some of these do become symptomatic and need treatment.

Adult↗
PubMed1998

[Application of ultrafast 3D-CT in cervical spine injury].

The authors investigated the usefulness of the ultrafast three-dimensional computed tomography (UF-3D-CT) in cervical spine injury. At Osaka City General Hospital, between April 1995 and March 1998, the authors examined 38 patients with cervical spine injury using UF-3D-CT. The ultrafast CT reduces scanning time. There were no complications associated with the examination. We examined 12 patients with vertebral body fracture, 11 patients with lamina fracture, 8 cases with subluxation including locking facet, 2 patients with atlanto-axial dislocation and 8 patients without bony abnormality. Results suggested that UF-3D-CT was very useful for helping us to understand the bony deformity and the relationship between the bone and the important vessels. UF-3D-CT is very useful for preoperative evaluation and pathophysiological evaluation in cervical spin injury.

Adolescent↗
PubMed1997

Cortical laminar necrosis in brain infarcts: chronological changes on MRI.

We studied the MRI characteristics of cortical laminar necrosis in ischaemic stroke. We reviewed 13 patients with cortical laminar high signal on T1-weighted images to analyse the chronological changes in signal intensity and contrast enhancement. High-density cortical lesions began to appear on T1-weighted images about 2 weeks after the ictus. At 1-2 months they were prominent. They began to fade from 3 months but could be seen up to 11 months. These cortical lesions showed isointensity or high intensity on T2-weighted images and did not show low intensity at any stage. Contrast enhancement of the laminar lesions was prominent at 1-2 months and became less apparent from 3 months, but could be seen up to 8 months.

Aged↗
PubMed1997

Vertebral artery occlusion after subarachnoid hemorrhage from a dissecting aneurysm of the vertebral artery: case report.

BACKGROUND: Generally speaking, occlusion of the vertebral artery is a finding of a dissecting aneurysm associated with completed stroke. We present a case of a vertebral dissecting aneurysm that produced subarachnoid hemorrhage (SAH). Angiography on the day of hemorrhage, however, demonstrated complete occlusion of the vertebral artery. CASE PRESENTATION: A 44-year-old hypertensive woman suffered a sudden onset of headache and vomiting followed by loss of consciousness due to SAH. Angiography on the day of hemorrhage revealed a complete occlusion of the right vertebral artery just distal to the dissecting aneurysm. This is the first report of such a case. The patient was still considered to be at significant risk of rerupture. Craniotomy and clip occlusion of the right vertebral artery and the origin of the right posterior inferior cerebellar artery were carried out to trap the thin-walled sac. At discharge, the patient had recovered completely except for some left limb ataxia, which subsequently disappeared. CONCLUSIONS: Two options are available for the treatment of such a case: surgical or medical treatment. We employed surgery. Which is the preferred approach, however, is a difficult judgment to make at this juncture.

Adult↗
PubMed1997

Enormously fast RNA hydrolysis by lanthanide(III) ions under physiological conditions: eminent candidates for novel tools of biotechnology.

Lanthanide(III) ions have shown enormous catalyses for the hydrolysis of the phosphodiester linkages in RNA, indicating their high potential for versatile applications to biotechnology and molecular biology. The activity monotonically increases with increasing atomic number in the lanthanide series, the last three ions (Tm3+, Yb3+, and Lu3+) being the most active. Non-lanthanide metal ions are virtually inactive. The pseudo first-order rate constant for the hydrolysis of adenylyl(3'-5')adenosine (ApA) by LuCl3 (5 mmol x dm(-3)) at pH 7.2 and 30 degrees C is 1.9 x 10(-1) min(-1) (the half-life is only 3.6 min), corresponding to 10(8)-fold acceleration. The product is an equimolar mixture of adenosine and its 2'- or 3'-monophosphate without any byproducts. The 2',3'-cyclic monophosphate of adenosine is not accumulated much in the reaction mixture. Lanthanide ions also efficiently hydrolyze oligoribonucleotides without a specific base-preference. In ApA hydrolysis by NdCl3 and GdCl3, the dependence of the hydrolysis rate on either the pH or concentration of the metal salt coincides fairly well with the corresponding profile of the equilibrium concentration of the bimetallic hydroxo-cluster [M2(OH)2]4+ (M=metal ion). Both the formation of the pentacoordinated intermediate and its decomposition are greatly promoted by lanthanide ions. A catalytic mechanism in which two metal ions (or their coordination water) in these tetracationic hydroxo-clusters show acid/base cooperation is proposed.

Adenosine Monophosphate↗