Biomedical subjects

Yuzo Hayashi

Publications and source records attributed to Yuzo Hayashi.

6 recordsLinked to original sources

PubMed2005

Metastatic leiomyosarcoma of the brain manifesting as multiple hemorrhages. Case report.

A 74-year-old man presented with a rare metastatic leiomyosarcoma of the brain manifesting as subacute development of multiple cerebral hemorrhages. Cerebral angiography demonstrated no tumor staining or vascular malformation. Whole body computed tomography revealed abnormal masses in the liver, left adrenal gland, and duodenum. Histological examination of an open biopsy specimen identified the lesion as metastatic leiomyosarcoma. Whole brain irradiation controlled the intracranial lesions, but the patient's general condition progressively deteriorated and he died of pneumonia. Metastatic leiomyosarcoma is a very uncommon tumor in the central nervous system with a poor response to existing treatment options. Consequently, new approaches to the treatment of this disease are needed.

Aged↗

PubMed2004

The pathology of ligamentum flavum in degenerative lumbar disease.

STUDY DESIGN: A pathologic study of the ligamentum flavum in degenerative lumbar disease. OBJECTIVES: To elucidate the clinical significance of each pathologic finding of the ligamentum flavum. SUMMARY OF BACKGROUND DATA: In many reports, researchers observed the ligamentum flavum removed partially during surgery and did not evaluate the whole image of the ligamentum flavum. In addition, there are only a few reports that examined the possible association between various histologic findings and clinical findings. And, thus, there are many unclear points in the clinical significance indicated by each pathologic finding. METHODS: The study participants were 50 patients with degenerative lumbar diseases who underwent surgical decompression with removal of the ligamentum flavum of the affected spinal level. Tissue specimens of the removed ligamentum flavum in cross section were prepared, and changes in the elastic fibers and collagen fibers were evaluated in three grades to evaluate the whole image. In addition, we observed the presence or absence of any focal lesions and statistically analyzed the possible association between these histologic findings and clinical symptoms or image findings. RESULTS: In regard to the association between histologic findings and clinical symptoms or image findings, calcification was observed in significantly older patients, who tended to have low scores in preoperative JOA score, and was frequently observed in patients with cauda equina symptoms. Patients with ossification had a significantly greater % slip, and chondroid cells were frequently observed in patients with spondylolisthesis. CONCLUSION: Various pathologic findings provided important foundations for discussing the pathogenesis of lesions in ligamentum flavum. Calcification was frequently observed in elderly patients and those with cauda equina symptoms, and these patients tended to have severer preoperative symptoms. Chondroid cells were frequently observed in patients with spondylolisthesis, and patients with ossification had a greater % slip, suggesting involvement of mechanical load in ossification of ligaments. The pathologic findings were significantly related to the clinical features, and these findings will be profitable for understanding the pathogenesis of degenerative lumbar disease.

Aged↗

PubMed2004

[Special proposal].

Various kinds organs and tissues obtained from operations and autopsies are preserved for a certain period of time after obtaining samples for histopathological examination and are later disposed of. Some of these organs and tissues are occasionally used for research or educational purposes. Although consent is usually obtained from the patient or from the family of the deceased patient before performing an operation or autopsy, the use and disposal of residual organs and tissues have been performed by clinicians or pathologists without obtaining consent from the patient or from the family of the deceased patient. Now, however, consent must be obtained after sufficient explanation to the patient or to the family of the deceased patient for the storage, use and disposal of residual organs and tissues. It must be kept in mind that residual organs and tissues are parts of a human body and that these parts belong to the patient from which they were obtained or to the family of the deceased patient. These points are important and provide an ethical basis for use and disposal of residual organs and tissues.

Ethics, Medical↗

PubMed2003

Application of the concepts of risk assessment to the study of amino acid supplements.

Risk assessment is defined as the use of available scientific information to characterize potentially adverse effects associated with exposure of humans to an agent under known or expected conditions. Practically, risk assessment is intended to provide the scientifically sound basis for regulatory or nonregulatory action to manage the risks in humans from the agent. Therefore, the final goal of risk assessment for supplementary use of amino acids is to provide scientific evidence and scientific logic for the establishment of tolerable upper intake levels (UL) for amino acids. At present, however, execution of risk assessment for amino acids is hampered by deficiencies in necessary scientific information, particularly, experimental or clinical/epidemiological data related to the estimation of no-observed-adverse-effect-levels (NOAEL), and scientific principles for the allocation of uncertainty factors (UF) in extrapolation from experimental/clinical data to the general human population. This paper attempts to identify the scientific data and scientific thoughts/methodologies required for deriving UL or assessing the margin of safety for the supplementary use of amino acids.

Aging↗

PubMed2003

Inhibition of COX-2 prevents hypertension and proteinuria associated with a decrease of 8-iso-PGF2alpha formation in L-NAME-treated rats.

BACKGROUND: The inhibition of nitric oxide (NO) exerts injurious effects on the cardiovascular system by several mechanisms, such as the activation of the renin-angiotensin system, oxidative stress, and inflammatory cytokines. We examined whether COX-2, an inducible isoform of cyclooxygenase, is associated with the pathogenesis observed in N(omega)-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. METHODS: Three groups of 8-week-old male Sprague-Dawley rats were studied (n = 6 in each group): group 1, untreated controls; group 2, treated with L-NAME (1 g/l for 3 weeks, p.o.); and group 3, L-NAME co-treated with COX-2 inhibitor NS-398 (5 mg/kg per day, i.p.). The L-NAME-induced expression of COX-2 mRNA and protein was semi-quantified in the kidneys and the thoracic aorta. Urinary excretion of the prostaglandin 6-keto PGF(1alpha), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2) was measured in the three groups. Moreover, urinary excretion of 8-iso-PGF(2alpha), a potent vasoconstricting arachidonic acid metabolite acting through thromboxane A (TXA) receptor activation, proposed recently as a marker of oxidative stress, was also measured. RESULTS: L-NAME induced significant increases in systolic blood pressure (P< 0.01), urinary protein (P< 0.05), and renal excretion of 8-iso-PGF(2alpha)(P< 0.01), compared with the control. In L-NAME-treated rats, the levels of COX-2 mRNA and protein were more than 50% higher in the kidneys (P< 0.05), and six-fold higher in the thoracic aorta (P< 0.01) than in control rats. NS-398 significantly ameliorated an increase in systolic blood pressure (P< 0.01) and urinary protein (P< 0.05) induced by L-NAME. CONCLUSIONS: These data indicate that an increase in COX-2 expression might have a hypertensive effect, partly associated with 8-iso-PGF(2alpha) formation in l-NAME-treated rats.

Animals↗

PubMed2002

Dissecting basilar artery aneurysm growing during long-term follow up--case report.

A 58-year-old male presented with a dissecting aneurysm of the basilar artery manifesting as dysarthria, left hemiparesis, and numbness of the left side. Angiography revealed a double lumen at the midportion of the basilar artery which was consistent with a diagnosis of dissecting basilar artery aneurysm. The patient was treated conservatively, and remained neurologically stable for a 5-year period following initial presentation, but serial magnetic resonance imaging revealed growth of the aneurysm compressing the brain stem. His condition then worsened. Computed tomography revealed obstructive hydrocephalus. Ventriculoperitoneal shunting was performed and the patient's symptoms improved. However, he died of subarachnoid hemorrhage. Autopsy showed the patient had had a type 3 "dolichoectatic dissecting aneurysm." Surgical treatment should be seriously considered for treating the patients with dissecting basilar artery aneurysm causing brain stem ischemia, especially if the aneurysm is growing. High-flow bypass and proximal occlusion may be the choice in patients with poor collateral circulations.

Aortic Dissection↗