Biomedical subjects
Publications and source records attributed to N Kuwayama.
A case of cerebral arterial ectasia is reported. A sixty-one year old male revealed sudden disturbance of consciousness. CT examinations disclosed massive intraventricular hemorrhage and the cerebral angiograms showed remarkable elongation and dilatation of cerebral arteries. The authors discuss cerebral arterial ectasia from a clinico-pathological point of view.
The Peltier stack, which allows quantitative measurement of cerebral blood flow (CBF) by means of thermal diffusion, has a probe too large for use in small animals. However, it is difficult to measure CBF by a thermal diffusion method involving the use of a constantan heating wire, because of heat conduction between the two gold plates. The authors developed a new thermal diffusion flow probe, using a constantan wire as a heat source rather than the Peltier stack. With the new probe, separation of the gold plates and attachment of a pair of long thermocouples minimize heat conduction between the two plates. Moreover, the probe itself is considerably smaller than that of the Peltier stack. The new probe was inserted to the subdural space of rabbits and the voltage (V; mV) was measured with an amplifier by the circuit of constant current method. CBF (F; ml/100 g/min) was measured simultaneously by the hydrogen clearance method in the adjacent cortex. A regression equation of F = 29, 111 (1/V-1/226) was obtained between 35 pairs of F and V (r = 0.92, p less than 0.001), which verified that CBF can be accurately measured with the new probe.
Two cases of multiple dural arteriovenous malformations (AVM's) in different locations are reported. One patient was diagnosed as having a dural AVM involving the right cavernous sinus that disappeared spontaneously 4 months after onset of symptoms. After an interval of 4 months, another dural AVM appeared involving the right lateral sinuses (transverse and sigmoid sinuses) with occlusion of the right sigmoid sinus. In the other patient, multiple dural AVM's were demonstrated on angiography, one involving the cavernous sinus and the other the left lateral sinus. The frequency of multiple occurrence and possible mechanisms of sinus occlusion are discussed.
A case of thoracic myelopathy due to ossification of the ligamentum flavum is presented. A fifty-five year old female complained of sensory and motor disturbance of lower limbs. Neuroradiologically, in addition to ossification of the posterior longitudinal ligament throughout the spines, ossified ligamenta flava were found at the Th10-11 level and magnetic resonance imaging (MRI) clearly showed the spinal cord compressed at the same level by a low-intensity-signal lesion. Laminectomy and removal of the ossfied ligamenta flava improved her neurological dysfunction. The usefulness of the MRI in the neuroradiological diagnosis was confirmed.
The authors have analysed dead cases of ruptured intracranial aneurysms. This analysis included 270 patients with ruptured intracranial aneurysms, admitted to Mito National Hospital over an 8 yr period. Of the 98 patients who had surgery within 48 h after SAH, 17 cases died (mortality rate 17.3%); 7 deaths were due to massive haemorrhage, 5 due to vasospasm and 5 to other causes. Analysis of the causes of death in the non-surgical group (62 cases) disclosed that massive haemorrhage was the most common (29 cases), followed by rerupture after admission (14 cases), vasospasm (7 cases) and miscellaneous cases (5 cases). The possibility of improving the mortality rate in the early surgical group and the non-surgical group is discussed.
A rare case of bilateral arachnoid cysts of the middle cranial fossa in a child successfully treated by partial excision of their walls is reported. Patients with bilateral arachnoid cysts are usually severely disabled, presumably due to primary dysgenesis of the operculum; however, in our case no primary dysgenesis was noted and the operative result was excellent.
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We report a rare case of subdural hematoma associated with dural carcinomatosis of gastric cancer and DIC. Such subdural hemasma is supposed to be caused by tumor cell embolism in the dural vessels and DIC. Most cases show acute clinical symptoms such as consciousness disturbances, and their prognosis is extremely poor.
Spontaneous extradural hematomas are rare and may be caused by pericranial infections, bleeding tendencies, or vascular abnormalities of the dura mater. The authors describe a case of spontaneous bilateral extradural hematomas assumed to be caused by a bleeding tendency with hypofibrinogenemia. A brief review of the literature is reported.
Vascular lesions of the central nervous system in neurofibromatosis (NF) are uncommon. Cerebral arterial occlusive diseases in NF have been documented in only 29 patients. This paper reports a case of a 16-year-old male having occlusion of the right internal carotid artery with NF. He was admitted with an episode of clonic convulsion and left hemiparesis at the age of five years. On admission, he had multiple café-au-lait spots, depigmentation and fibroma molle throughout his body. Neurological examination revealed left hemiparesis with hypereflexia and pathological reflex on the left side. CT scan showed brain atrophy of the right hemisphere and low density area in the white matter of the right frontal lobe. Cerebral angiography showed occlusion at the extracranial portion of the right internal carotid artery. He underwent STA-MCA bypass on the right side. On histological examination of a section of STA, the intimal layer was thickened by elastofibrosis. The mechanisms of arterial occlusion in patients with NF are discussed with review of the literature.
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We present a case of multiple aneurysms of the posterior inferior cerebellar artery (PICA) at the distal portion, which is very rare. A 62-year-old woman was admitted to our hospital with complaint of a severe headache. Four-vessel study was carried out and we found one aneurysm in the retromedullary segment of the right PICA. The aneurysm was clipped through the median suboccipital approach. But postoperative angiography showed that aneurysm was not being clipped and the clip was seen about 1 cm proximal to the aneurysm. We concluded that she had two aneurysms and the second operation was performed. The second aneurysm was found about 1cm distal of the one first clipped. The histological finding of the first clipped aneurysm was a degenerative change of slight cellular swelling of the muscle layer. The patient died 10 days after the second operation from fluminant hepatitis and autopsy was not performed. We made a review of the literature about the incidence of multiple aneurysms at the distal portion of PICA.
A rare case of spontaneous bilateral extradural hematomas probably due to hypofibrinogenemia is reported. On April 17, 1983, a 21-year-old woman was referred to our hospital because of her comatose state. She has complained of her longer duration of menstrual bleeding lasting 10 days to 2 weeks, but has had no history of hemorrhagic diseases. At the last night, she complained of headache and vomited several times, after drinking some beer but she went to bed without therapy. We cannot see a history of her head injury several days before admission. On admission, she was comatose with bilateral dilated pupils and flexed her upper extremities against painful stimuli. There was a tendency for subcutaneous hematomas to form immediately in places where the stimuli were applied. Skull fracture was not found on craniogram and CT scan showed bilateral extradural hematomas (60 ml on the right side and 130 ml on the left side). Laboratory data showed leukocytosis (14800), longer prothrombin time (15.2 seconds with a control of 11.9 seconds), markedly elongated activated partial thromboplastin time (90 seconds with a control of 15-45 seconds) and decreased fibrinogen concentration (114 mg/dl with a control of 200-400 mg/dl). At the bilateral decompressive craniectomies with infusion of 5 gram of fibrinogen and 300 ml of fresh blood, we found neither scalp hemorrhage nor skull fracture and after removal of coagulated hematomas no dural anomaly was found. After operation she improved gradually and laboratory re-examination was normal including bone marrow puncture. Now, 5 months after operation she is clear with slight tetraparesis on her rehabilitating course.(ABSTRACT TRUNCATED AT 250 WORDS)
The effect of quartz addition was investigated on the sintering processes of powder compacts made from frit and glass powder with quartz powder. The results obtained are summarized as follows. 1) The quartz powder gave some effects on the shrinkage curves and the firing temperature range of frit and glass powder. Pyrex glass powder was more effective on the firing temperature range of the powder compacts with quartz addition comparing with other frits and glass powders. 2) The produced crystal during heat treatment of the powder compacts made from pyrex glass powder with quartz powder were cristobalite. 3) The sintered composite showed larger thermal expansion value by expansion due to the transition of cristobalite followed with the crystallization of cristobalite than that without crystallizing property.
Dental porcelains were made from frit and glass powder with electro fused alumina powder addition in the range from 20 to 60 wt% using sintering method at the temperature from 500 degree C to 1 000 degree C, and the effects of alumina content and firing temperature on firing processes of sintered composite were investigated. Shrinkage curves of the powder compacts varied with kind of frit and content of alumina. Particulary, powder compact with alumina addition in the range from 50 to 55% was found to have a remarkable influence for extention of firing temperature range. The densification of the powder compacts was considered to be accelerated by the dissolution of a small a mount of alumina particle into the frit and glass above 900 degree C. Expansion coefficient value of sintered composite of alumina and Pyrex glass powder gradually increased with increase of alumina content. Inversely, expansion coefficient of soda-lime-silica glass showed the minimum value at 40 wt% alumina content and then had a tendency of slight increases with increase of alumina content.
Tensile behaviour of Ag-Pd-Au-Cu alloys depending on age-hardening was studied by the tensile test with extensometer. The fractured surface of the alloys was observed by the scanning electron microscope. Plastic deformation of alloys was changed from discontinuous yielding to parabolic strain hardening, as the size of precipitate hard particles was grown by aging. There appears to be good correlation between the tensile strength of alloys with aging and the hardness. Strain hardening parameters of the Ludwik, Swift, Voce and Hollomon empirical equations in describing the stress-strain curves were calculated by the least square method. Theoretical tensile strength which was computed from these empirical equations, was good agreement with the tensile test of alloys with aging. But, theoretical uniform elongation tended to elongate. The ratio of tensile strength to proof stress of over-aged alloys was extremely low, as compared with the other alloys. So, over-aging should be avoided to use the alloys in dentistry. If structure of the precipitate particles is controlled by aging temperature and time, the loss of ductility on age-hardening will be considerably eliminated.