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Biomedical subjects

Y Kadota

Publications and source records attributed to Y Kadota.

At least 37 records · Page 2Linked to original sources
PubMed1997

The effects of sevoflurane anesthesia on insulin secretion and glucose metabolism in pigs.

We investigated the effects of two different concentrations of sevoflurane, 0.4 minimum alveolar anesthetic concentration (MAC) and 1.0 MAC, on insulin secretion before, during, and after sevoflurane anesthesia using three successive intravenous glucose tolerance tests (IVGTT) in pigs with indwelling catheters. We also investigated changes in the levels of plasma glucose, catecholamines (epinephrine [E], norepinephrine [NE]), and cortisol (Cor). The pigs were grouped as awake, 0.4 MAC, or 1.0 MAC. Sevoflurane decreased the ratio of insulin/glucose (INS/GLU) in the basal condition (P < 0.05 awake versus 1.0 MAC) and during IVGTT (P < 0.01 awake versus 1.0 MAC and 0.4 MAC). These decreases were quickly reversible (control levels were regained within 2 h of the end of anesthesia), were probably dose-related, appeared not to be mediated by E, NE, or Cor. In addition, the INS/GLU ratio 2.5-4 h after the end of anesthesia was significantly higher in the anesthetized groups than in the awake group. We conclude that sevoflurane anesthesia has a rapidly reversible inhibitory effect on basal and glucose-stimulated insulin secretion, as do other inhaled anesthetics, and might induce insulin resistance.

Anesthesia, General↗
PubMed1997

Quantitative evaluation of the effects of thyroarytenoid muscle activity upon pliability of vocal fold mucosa in an in vivo canine model.

Stiffness of the vocal fold is a significant factor in determining mucosal wave propagation and in the control of the fundamental frequency of phonation. We measured pliability of the vocal fold mucosa in an in vivo canine model as an index of stiffness while the histological layer-by-layer structure of the vocal fold was not disrupted. The point 1 mm below the free edge showed a maximal pliability that gradually diminished toward the tracheal side and reached a minimum. When the thyroarytenoid (TA) muscle contracted, pliability of the mucosa was significantly increased (P < 0.001). Mucosal pliability of the excised larynx was significantly increased compared with that in vivo (P < 0.001). The point of minimal pliability in the absence of TA muscle contraction did not shift after excision of the larynx, while TA muscle contraction caused a downward shift of the point of minimal pliability. Mucosal pliability can thus be used to quantitatively assess the effects of TA muscle contraction on stiffness of the vocal fold mucosa.

Animals↗
PubMed1997

Subglottic stenosis in Wegener's granulomatosis limited to the head and neck region.

Subglottic stenosis as a complication of Wegener's granulomatosis (WG) is a relatively rare lesion and is difficult to treat surgically once stenosis becomes sufficiently severe to cause inspiratory dyspnea. Thus, it is important to diagnose WG in its early stages to prevent troublesome subglottic stenosis from developing by initiating immunosuppressive therapy. The authors report on a 30-year-old woman suffering from subglottic stenosis of sudden onset due to protracted WG limited to the head and neck region. She had had exudative otitis media for 13 years and saddle nose and nasal crusting for five years. Repeated biopsies of the nasal mucosa and enzyme-linked immunosorbent assays for cytoplasmic patterns of antineutrophil cytoplasmic autoantibody (cANCA) had failed to establish the diagnosis. However, further histologic examination of the nasal mucosa showed vasculitis, and indirect immunofluorescence detected the presence of cANCA. Thus, the diagnosis of WG was confirmed 13 years after the appearance of the initial symptoms in the ear. The patient was given prednisolone (60 mg/day for five days), which greatly relieved the subglottic stenosis. The prednisolone dosage was then tapered to 5 mg/day.

Adolescent↗
PubMed1996

Induction of peripheral-type benzodiazepine receptors in mouse brain following thioacetamide-induced acute liver failure.

To investigate the possible role of peripheral-type benzodiazepine receptors (PBR) in hepatic encephalopathy, we examined expression of PBR in mouse brain following thioacetamide (TAA)-induced acute liver failure. Treatment of mice with TAA resulted in an increase in the number of binding sites of the PBR ligand [3H] Ro5-4864 to brain homogenates, with no significant change in affinity of the ligand. The order of potency of different ligands to compete against [3H] Ro5-4864 binding in the brain of TAA-treated mice was Ro5-4864 > PK11195 > diazepam > protoporphyrin IX, findings similar to those in the control. Northern blot analysis revealed an increase in PBR/isoquinoline binding protein (PBR/IBP) mRNA in mouse brain following TAA treatment, in a time- and dose-dependent manner. These results indicate that the increased number of PBR in the brains of TAA-treated mice relates to the induction of PBR/IBP expression and suggest that the induction of PBR in brain may contribute to pathogenesis of hepatic encephalopathy.

Animals↗
PubMed1996

Vocal fold vibration viewed from the tracheal side in living human beings.

The mucosal upheaval where the mucosal wave starts and propagates upward appears on the lower surface of the canine vocal fold during vibration. We investigated the vibratory behavior of the in vivo human vocal fold viewed from the tracheal side. Subjects consisted of 14 men and 6 women who had undergone tracheostomy for various head and neck diseases; their ages ranged from 22 to 70 years, with a mean of 53.9 years. The inferior aspect of the vocal fold during phonation was observed with the aid of a rigid oblique-view endoscope inserted through a tracheostoma (inferior glottoscopy). Each subject was asked to sustain the vowel /a/ at a comfortable pitch and loudness (easy phonation) and then at a higher pitch. Inferior glottoscopy could be performed during easy phonation in 19 subjects and during high-pitched phonation in 10 subjects. During easy phonation, the mucosal upheaval appeared on the lower surface of the vocal fold between the anterior commissure and the vocal process in all 19 subjects. During high-pitched phonation, the vocal fold became longer, and the subglottic vault surrounded by the bilateral mucosal upheavals became narrower compared with those during easy phonation. Use of a dilated blood vessel as a landmark in one subject showed the location of the mucosal upheaval on the vocal fold mucosa to actually shift medially toward the oral side during high-pitched phonation. Despite structural differences between the human and canine vocal folds, the infraglottic aspect of the vocal fold vibration observed in the living human larynx was quite similar to that observed in the excised canine larynx.

Adult↗
PubMed1996

Akinetic mutism and involuntary movements following radical resection of hypothalamic glioma--case report.

A 3-year-old boy presented with an unusual consciousness disturbance accompanied by involuntary movement disorder after radical surgical removal of a huge hypothalamic glioma. Postoperative computed tomography and magnetic resonance imaging revealed a lesion in the bilateral basal ganglia. Marked neurological improvement was obtained by treatment with dopamine agonists, suggesting that the disruption of the dopaminergic pathway via the hypothalamus was the cause of these neurological symptoms.

Brain Neoplasms↗
PubMed1996

[Enzyme saturation of sevoflurane in piglets at clinically-used concentrations].

To investigate if sevoflurane saturates the metabolic capacity of the enzymes responsible for sevoflurane at clinically-used concentration ranges, we compared plasma fluoride levels and urinary excretion of inorganic fluoride in piglets after (1) low concentration sevoflurane anesthesia versus (2) high concentration sevoflurane anesthesia. Eleven male piglets, weighing 18-23.5 kg, were randomly divided into two groups: 1) L group: five animals were anesthetized for two hours with sevoflurane at 0.8% end-tidal concentration (0.4 MAC); 2) H group: six animals were anesthetized for two hours with sevoflurane at 3.0% end-tidal concentration (1.4 MAC). Plasma inorganic fluoride levels, blood sevoflurane concentration, urinary inorganic fluoride concentration and urine volume were measured. The blood sevoflurance concentration in both groups reached their plateau levels 30 min after the start of anesthesia. The plateau levels in the H and L groups were 275-306 microM and 105-115 microM, respectively. The plasma fluoride concentrations reached plateau levels 60 min after the start of anesthesia in both groups. The H group showed significantly higher plasma fluoride levels than the L group during sevoflurane anesthesia. The H group also showed significantly higher urinary excretion of inorganic fluoride than the L group. Therefore, metabolite production levels in the H group were significantly higher than the L group. These results suggest that low concentration sevoflurane anesthesia did not saturate the metabolic capacity of the enzymes responsible for defluorination of sevoflurane in piglets.

Anesthetics, Inhalation↗
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↗
PubMed1995

Melanotic neuroectodermal tumor of infancy: a molecular approach to diagnosis. Case report.

A case of melanotic neuroectodermal tumor of infancy arising from the transverse sinus is presented. The tumor was located on the outer surface of the dura and extended extracranially through the occipitomastoid suture. Two cell populations were observed: pigmented melanocyte-like cells and small neuroblast-like cells. Ultrastructural analysis revealed epithelial tumor cells and melanosomes at various stages. Expression of melanotransferrin messenger RNA transcripts within the tumor tissue was observed using a reverse transcriptase-polymerase chain reaction method in addition to immunohistological studies. The positive expression of melanotransferrin confirmed that this melanotic neuroectodermal tumor was derived from neural crest cells.

Base Sequence↗
PubMed1995

[Anesthetic management of a patient with congenital cystic adenomatoid malformation].

Congenital cystic adenomatoid malformation (CCAM) is a rare disease that is diagnosed by severe respiratory dysfunction from birth. A 5-day-old-boy with CCAM underwent removal of a large cyst which was present at lower lobe of right lung. Anesthesia was induced slowly and maintained with oxygen and sevoflurane. Severe airway obstruction occurred transiently by the secretion from the lung cyst. Thereafter, the surgery was completed safely and his postoperative course was uneventful. Perioperative anesthetic management of the patient with CCAM is also discussed.

Airway Obstruction↗
PubMed1994

[Pliability of vocal fold mucosa in relation to the location of subglottic mucosal upheaval during phonation].

Mucosal pliability was measured in 23 excised larynges, 19 canine and four human, at the three portions of the vocal fold, namely the midline, the anterior 1/4 and the posterior 1/4. The pliability at the midline showed a greater value than those at the other two portions. The free edge of the vocal fold showed a maximum pliability which gradually diminished toward the tracheal side and reached a minimum 3mm from the free edge of the fold. An increase in vocal fold tension resulted in lowering of mucosal pliability at all measured points and the point of minimal pliability shifted toward the oral side. The point of minimal pliability moved toward the tracheal side with direct electrical stimulation of the thyroarytenoid muscle (TA). Both pliability measurement and observation of mucosal vibration from the tracheal side using high speed cinematography or stroboscopy were performed on eleven of the excised canine larynges. The mucosal upheaval occurred at the point around which pliability was minimal. An increase in vocal fold tension resulted in an upward shift of the mucosal upheaval which occurred slightly below the point of minimal pliability. Electric stimulation of the TA resulted in a downward shift of the mucosal upheaval which occurred in accordance with the point of minimal pliability. Histological examination of the canine larynges revealed that the lamina propria became increasingly thin toward the point around which pliability was minimal and at which the mucosal upheaval occurred. At this point, the muscle layer approximated the epithelial layer with disappearance of the deep layer of the lamina propria. The point shifted to the oral side following an increment in vocal fold tension, while the point moved toward the tracheal side following contraction of the TA. Pliability of the vocal fold is minimal at the point around which the deep layer of the lamina propria disappears and the mucosal upheaval occurs.

Animals↗
PubMed1994

Immunohistochemical expression of proliferating cell nuclear antigen (PCNA) in intracranial glioma and meningioma.

BACKGROUND: Immunohistochemical study of proliferating cells in normal or neoplastic tissues has its advantages over other methods in understanding cell kinetic information. Proliferating cell nuclear antigen (PCNA) immunolocalization in paraffin section was reported as an index for cellular proliferation and well-correlated with the histopathological grading of certain systemic malignancies. METHODS: By using immunohistochemical staining of PCNA on formalin-fixed, paraffin-embedded sections, the anti-PCNA monoclonal antibody (PC10) staining scores were counted in 32 intracranial gliomas and 32 intracranial meningiomas. RESULTS: The PC10 scores ranged from 7.8% to 24.1% (m = 15.7 +/- 4.5%) in 12 anaplastic astrocytomas, and from 15.1% to 51.3% (m = 38.4 +/- 11.7%) in 9 glioblastomas. The difference in between was significant. The mean PC10 scores of benign meningiomas, malignant meningiomas, and hemangiopericytomas were 13.8%, 50.2%, and 50.8% respectively. The difference of PC10 scores was also significant between benign and malignant meningioma, as well as between benign meningioma and hemangiopericytoma. CONCLUSIONS: The PC10 scores have a good correlation with the histopathological grading of both intracranial glioma and meningioma.

Antigens, Neoplasm↗
PubMed1993

Tracheal view of vocal fold vibration in excised canine larynxes.

The mucosal upheaval where the mucosal wave starts and propagates upward appears on the lower surface of the vocal fold during vibration. We investigated the location of the mucosal upheaval in response to variations in vocal fold tension and mean air flow rate. Twelve excised canine larynxes were used in the experiment. The lower surfaces of the vocal folds were marked with india ink. After cinematography was performed, a small cut wound was made at the mark. This wound served to relate cinematographic findings with the histologically observed position of the mark. The larynx was then fixed, sectioned in the frontal plane, and stained for histologic examination. Horizontal movements of the free edge, mucosal wave, mucosal upheaval, and marks were analyzed. Under a fixed vocal fold tension, the mucosal upheaval appeared more laterally to a limited extent as mean air flow rate increased, but its location on the vocal fold mucosa did not change from its position before the increase of mean air flow rate. The mucosal upheaval appeared more medially when vocal fold tension increased. The position of the mucosal upheaval actually changed medially compared with its original position before the tension increase. Histologic examination indicated that the mucosal upheaval arose on the lower surface of the vocal fold between the free edge and the area where the muscular layer comes in close proximity to the epithelial layer.

Air Movements↗
PubMed1993

Molecular defect in human erythropoietic protoporphyria with fatal liver failure.

We investigated the molecular basis of ferrochelatase in a Japanese patient with erythropoietic protoporphyria (EPP), complicated by fatal liver failure, and defined a novel point mutation in the ferrochelatase gene. cDNAs were synthesized using Epstein-Barr-virus-transformed lymphoblastoid cells from the proband. cDNA clones encoding ferrochelatase in the proband were isolated by amplification using the polymerase chain reaction. There were two sizes of ferrochelatase cDNAs; one was normal in size, the other being smaller. Sequence analysis of the abnormally sized cDNA clones revealed that they lacked exon 9 of the ferrochelatase gene. Genomic DNA analysis demonstrated that the proband had the abnormal allele and that it contained a G to A point mutation at the first position of the donor site of intron 9. An identical mutation was detected in the affected family members of the proband by allele-specific oligonucleotide hybridization analysis. EPP is inherited in an autosomal dominant manner in this family.

Adult↗