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Biomedical subjects

H Yugami

Publications and source records attributed to H Yugami.

10 recordsLinked to original sources
PubMed2001

Spectral control of thermal emission by periodic microstructured surfaces in the near-infrared region.

Thermal emissive properties of microstructured surfaces are measured in the near-infrared region. Two-dimensional periodic microstructured surfaces with metal coatings are fabricated with Si anisotropic etching and laser ablation techniques. The structural periods of the samples are 2.0 and 1.5 microm. Clear selective-emission bands are observed experimentally. This selective emission is attributed to the resonance effect between the emissive field and the surface microstructures. In addition, numerical calculation computed with rigorous coupled-wave analysis (RCWA) is performed on the microstructured samples. The selective-emission peaks measured through experiments can be reproduced well by RCWA, and this result suggests strongly that the thermal radiation from periodic structures may have spatial coherence. It is confirmed that the surface microstructure can be applied to the control of spectral emission from high-temperature materials.

Journal Article↗
PubMed2001

[Dissecting aneurysm of the anterior cerebral artery with later development of collateral circulation: a case report].

Intracranial dissecting aneurysm (DA) is much less frequent than berry aneurysm. Such dissection involves mostly the vertebral and basilar arteries, followed by the internal carotid and middle cerebral arteries. DA of the anterior cerebral artery (ACA) is relatively rare and little is known about its natural Development. Only 23 cases have been reported previously. Our present patient, a 44-year-old man, suddenly developed paresis of the left leg while bathing. Diffusion magnetic resonance imaging indicated an area of high signal intensity in the territory of the ACA. Angiography on day 3 following onset showed a DA involving the left A2 segment. Antiplatelet therapy was administered. Further luminal narrowing in the lesion was demonstrated by repeat angiography on day 17. Occlusion of the distal A2 segment was demonstrated together with sufficient collateral supply on day 41. Symptoms resolved completely. DA of the ACA usually presents with ischemic attacks. Its etiology remains uncertain, and its natural course is unclear. Surgical intervention is recommended for patients with intracranial hemorrhage, while non surgical therapies have achieved good outcomes in ischemic cases.

Adult↗
PubMed1999

[A case of neurofibromatosis type 1 associated with arteriovenous fistula caused by re-bleeding of a vertebral dissecting aneurysm].

We described a dissecting aneurysm of the vertebral artery (VA), which was associated with neurofibromatosis type 1 (NF1). A 41-year-old man was referred to our hospital because of abrupt, severe headache. A CT scan revealed diffuse subarachnoid hemorrhage (SAH) predominantly in the prepontine cistern. The angiograms showed a string sign in the left VA, just distal to the posterior inferior cerebellar artery (PICA). The vertebral dissection was considered responsible for SAH, and endovascular occlusion of the left VA was attempted. During the intervention, the patient complained of severe neck pain at the time of selective vertebral angiography, which revealed an arteriovenous fistula. The VA was occluded proximal to the PICA with GDC, which covered the fistula. Open surgery confirmed the two unruptured aneurysms. Intracranial dissection is rarely reported in association with NF1. However, ateriovenous fistula is not an uncommon combination with dissecting aneurysm and the extracranial segment of the VA is a characteristic target. Anatomical feasibility is conceivably the pathogenesis.

Adult↗
PubMed1985

EEG changes 24 hours after myelography with metrizamide.

A prospective study of EEG changes following metrizamide myelography was made on 34 patients aged 17-79 years. EEGs were recorded just before and 22-26 hours after myelography. Usually 8-10 ml of metrizamide was injected by either lumbar or lateral cervical puncture. The concentration of metrizamide was relatively high. EEGs were abnormal in 15 out of the 20 patients whose baseline EEGs were normal. EEGs deteriorated in 10 of the 14 patients whose control tracings were abnormal. High voltage delta activity and/or a great deal of theta activity were common abnormalities. Three patients showed triphasic waves. No relationships were found between the EEG changes and clinical variables. But central nervous system involvements by metrizamide tended to be accompanied by a severe EEG slowing.

Adolescent↗