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Biomedical subjects

Y Kadota

Publications and source records attributed to Y Kadota.

At least 19 recordsLinked to original sources
PubMed1995

Thyroarytenoid muscle activity and infraglottic aspect of canine vocal fold vibration.

OBJECTIVES: To investigate the effect of contraction of the thyroarytenoid (TA) muscle on the location of the mucosal upheaval (MU) and to estimate the location of the MU in relation to the histologic structure of the vocal fold. BACKGROUND: The MU is a small mucosal ridge arising on the lower surface of the vocal fold during phonation and is thought to be the lower border of the vibrating structure. METHODS: Vibrations were elicited under three conditions: during bilateral TA muscle contraction, without TA muscle stimulation, and during vocal fold lengthening. The vibrations were recorded from the tracheal side by high-speed cinematography or videotape recording combined with stroboscopic illumination. The larynx was prepared for histologic observation in the frontal plane. Tattooed marks on the lower surface of the vocal fold were used to locate macroscopically observed landmarks with reference to microscopic structures. RESULTS: The MU shifted laterally toward the tracheal side during TA muscle contraction. When the vocal fold was lengthened, the MU shifted medially toward the free edge. Histologic examination showed that the MU in the absence of TA muscle contraction arose slightly above the area where the muscular layer approached the epithelial layer. CONCLUSION: When the TA muscle contracts, the vibrating area expands toward the tracheal side, and a more dynamic mucosal wave occurs in the vertical direction. We believe that a part of the body and the cover are probably involved in the vibratory movement of the vocal fold.

Animals↗
PubMed1995

Neural differentiation and maturation in metastatic medulloblastoma--case report.

A 6-year-old boy presented with a cerebellar medulloblastoma. Radical removal of the tumor and postoperative irradiation achieved complete remission. However, a metastatic tumor in the frontal lobe developed 2 years later. Radical removal and postoperative chemotherapy achieved partial remission, but he died of multiple intracranial and intraspinal dissemination of the tumor 2 years later. Comparison of the light microscopy, immunohistochemical staining, and electron microscopy findings from specimens of the tumors showed that the mainly undifferentiated primary tumor demonstrated both glial and neural differentiation, while the more mature metastatic tumor showed only neural differentiation. This suggests that differentiation and maturation of immature tumors such as medulloblastoma may proceed independently of metastatic potential.

Cell Differentiation↗
PubMed1992

Skull base reconstruction in cases of intracranial teratoma extending into the extracranial structures.

Recently experienced were two cases of postnatally diagnosed intracranial teratoma, one a mature teratoma and the other an immature teratoma, both extending into the extracranial structures. In each case, tumor resection was performed in which a barrier was created between the intracranial and extracranial spaces with a temporalis muscle flap. The technical aspect of skull base reconstruction is described, and previously reported cases of intracranial teratoma involving the skull base are reviewed.

Brain Neoplasms↗
PubMed1991

[Clinical studies of isosorbide dinitrate spray in postoperative patients].

We investigated the effect of isosorbide dinitrate (ISDN) single spray, containing 1.25 mg of ISDN, on cardiovascular and respiratory functions in eight postoperative patients. Concentrations of plasma ISDN and its metabolites were also investigated. Hemodynamic as well as blood gas studies were performed at 4 points (before, plus 10, 30 and 60 minutes after administration of ISDN) and the blood levels of ISDN and its metabolites were measured at 5 points (before, plus 5, 10, 30 and 60 minutes after administration of ISDN). Mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), cardiac index (CI), pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP) decreased significantly and heart rate (HR) increased significantly at 10 and 30 minutes after the spray. The maximum changes observed of each parameters were MAP 7%, MPAP 22%, CI 9%, PCWP 33%, CVP 36% and HR 6%. Systemic and pulmonary vascular resistance indices did not change significantly throughout the study. PaO2 decreased significantly only at 10 minutes after the spray. Plasma ISDN concentration showed the maximum value of 56.3 ng.ml-1 at 5 minutes after the spray. After this value, the concentrations decreased rapidly. From this study, we conclude that single spray of ISDN is effective in decreasing preload promptly, but it is not effective in decreasing afterload. When using the spray, we should pay attention to pulmonary oxygenation.

Adult↗
PubMed1990

Regrowth of damaged neurosecretory axons to fenestrated vessels of implanted peripheral tissues.

A major target of neurosecretory axons (NSA) is the basal lamina around fenestrated blood vessels (FBV) in the neural lobe of the pituitary gland. We have posed the question of whether there is neurovascular specificity. Do mature, regenerating NSA terminate selectively on the FBV of the neural lobe compared with the FBV of other tissues that normally are not innervated by NSA? Three types of tissue were transplanted between inbred Fisher rats. Fragments, about 1 mm3, of pineal, adrenal medulla, and neural lobe were grafted bilaterally to the hypothalamic, retro-chiasmatic area, which includes bundles of NSA from supraoptic and paraventricular neurosecretory nuclei exclusively, but no FBV. Two and 4 weeks later, the grafts were prepared for the immunohistochemical localization of NSA and for electron microscopy. NSA-FBV proximity was measured, and the number of NSA, FBV, and of NSA-FBV associations was counted per surface area of each graft. Regenerating NSA can associate as closely with FBV of other tissues as they can with the FBV of the neural lobe. There does not appear to be specificity with respect to the closeness of association between neurosecretory terminals and fenestrated capillaries. However, the number of these associations is greater in neural lobe grafts than in adrenal or pineal grafts at 4 weeks. The number of FBV is also greatest in neural lobe grafts at this time, an increase that would provide a greater opportunity for NSA-FBV associations.

Adrenal Medulla↗
PubMed1988

[A case of clivus chordoma showing hemorrhage in the posterior fossa].

We are reporting a rare case of clivus chordoma with fatal hemorrhage in the posterior fossa. A 38-year-old woman afflicted with sudden onset of severe headache and vomiting. On neurological examination, she was mildly lethargic. She had slight dysarthria and nystagmus, but no cranial nerve abnormalities. Craniogram revealed erosive changes in the right petrous bone. CT scan showed a massive intracerebellar hemorrhage and isodense mass in the sphenoid sinus, which were not enhanced by contrast medium. She became comatose and died 3 days later. No operation was performed. Autopsy revealed massive hemorrhage in the posterior fossa and yellowish, gelatinous tumor extending from the right clivus to the sphenoid sinus. Histological examination showed a chordoma. This case demonstrates that the hemorrhage associated with brain tumor, especially in posterior fossa, produces a significant sudden elevation of intracranial pressure and leads clinically to a rapid loss of consciousness and death soon after the onset.

Adult↗