Biomedical subjects

Y Kadota

Publications and source records attributed to Y Kadota.

At least 19 recordsLinked to original sources

PubMed1999

T-cell development in human thymoma.

Human thymoma is derived from thymic epithelial cells and often associated with a large number of cortical thymocytes. Since thymic epithelial cells play key roles in T-cell development in the normal thymus, we hypothesized that the neoplastic epithelial cells of thymoma may support T-cell differentiation. We attempted to reconstitute the T-cell development in vitro by using neoplastic epithelial cells isolated from thymoma. CD34, a stem cell marker, was expressed on a proportion of CD4-CD8- cells in thymoma. These CD34+CD4-CD8- cells also expressed both IL-7R alpha-chain and common gamma-chain. Purified CD4-CD8- cells from thymomas were cultured with the neoplastic epithelial cells, and their differentiation into CD4+CD8+ cells via CD4 single positive intermediates was observed within 9 days' co-culture in the presence of recombinant IL-7. The CD34+CD4-CD8- cells purified from a normal thymus also differentiated to CD4+CD8+ cells in an allogeneic co-culture with the neoplastic epithelial cells of thymoma. In addition, a pleural dissemination from thymoma contained a large amount of cortical thymocytes. These results suggest that the neoplastic epithelial cells retain the function of thymic epithelium and can support T-cell development in thymomas.

Adult↗

PubMed1999

Impaired expression of MHC class II molecules in response to interferon-gamma (IFN-gamma) on human thymoma neoplastic epithelial cells.

A human thymoma is a neoplasm derived from the thymic epithelial cell, and is well known for its association with autoimmune diseases, especially myasthenia gravis. The neoplastic epithelial cells of thymoma clearly retain thymic epithelial functions, but the development of T cells in thymoma is somewhat impaired. In this study, we quantified by flow cytometry the in vitro expression of MHC molecules on neoplastic epithelial cells precultured with IFN-gamma. While MHC class I expression was comparable with that on normal thymic epithelial cells, the level of MHC class II molecules on neoplastic epithelial cells was lower than in controls, and also varied greatly from case to case. Additionally, there was a significant positive correlation between the expression level of MHC class II and the proportion of mature CD3+ cells in the CD4+CD8- subset. Thus, accumulation of CD3-CD4+CD8- cells in thymoma may result from impaired expression of the MHC class II molecules, suggesting that the function of the neoplastic epithelial cells might determine the maturation and the positively selected repertoire of T cells in thymomas.

Adult↗

PubMed1999

[Management under anesthesia of a patient with renal cell carcinoma extending into the retrohepatic inferior vena cava with the aid of partial cardiopulmonary bypass].

A 70-year-old male with renal cell carcinoma extending into the retrohepatic inferior vena cava was scheduled for radical nephrectomy with vena caval resection under general anesthesia. He had received partial gastrectomy for gastric cancer twelve years before. Computed tomography and inferior vena cavography confirmed that the vena cava was almost completely occluded and that a collateral venous network was well established. It was considered that the surgical approach to the retrohepatic cavals area was technically very difficult, and that there was a high possibility of a pulmonary embolus during the surgical manipulation. To prevent a pulmonary embolus and get good control of the vena cava above the tumor and below the hepatic vein, we decided to use a partial cardiopulmonary bypass (CPB) until the vena cava was clamping above the tumor. Anesthesia was induced with propofol and fentanyl, and maintained with fentanyl and isoflurane-N2O-O2. In the partial CPB blood from the hepatic vein was drained from the inferior vena cava cannula through right atrium, oxygenated by microporus membrane oxygenator, and returned to the left femoral artery. Cannulation to drain the venous circulation entering the vena cava below the tumor was abandoned because the extensive collateral venous network ultimately drains into the superior vena cava. The partial CPB time was 90 min, and the bladder temperature during the CPB was 35-36 degrees C. During the 7.3 hr procedure, the pulmonary embolus did not occur and the total blood loss was 5515 ml. The patient made an uncomplicated recovery and was discharged 30 days after the operation. This newly reported partial-CPB method may be safe and effective for the management under anesthesia of other patients.

Aged↗

PubMed1998

Pliability of the vocal fold mucosa in relation to the mucosal upheaval during phonation.

OBJECTIVES: To quantitatively evaluate the effect of vocal fold lengthening on pliability of the mucosa measured along the superior-inferior axis and to examine the relation of the location of mucosal upheaval (MU) during phonation to the changes in pliability pattern of the mucosa when the vocal fold was lengthened. DESIGN: Investigation of mechanical characteristics of the vocal fold in relation to the MU during phonation. MATERIALS: Five excised canine larynges. INTERVENTIONS: Vibrations with and without vocal fold lengthening were recorded from the tracheal side via high-speed photography or video recording combined with stroboscopic illumination. Tattooed marks on the lower surface of the vocal fold were used to locate the MU. Pliability was defined as the maximal distance elevated in response to a constant focal negative pressure. RESULTS: Pliability decreased significantly (P=.05) when the vocal fold was lengthened. The point of minimal pliability and MU without vocal fold lengthening were located slightly above the area where the muscular layer approached the epithelial layer. They were located closer to the free edge of the vocal fold when it was lengthened than when it was not. Discrepancy of their locations when the vocal fold was lengthened was suggested. CONCLUSIONS: The MU occurs around the point of minimal pliability when the vocal fold is not lengthened, whereas the MU occurs slightly more laterally than the point of minimal pliability when the vocal fold is lengthened. Although further study is necessary to explain this discrepancy, the presence of the sparse deep layer of the lamina propria seems to be essential in the generation of the mucosal wave.

Animals↗

PubMed1998

Immaturity of lymphocytes in the metastatic lesions of thymoma.

Thymoma is a thymic epithelial tumor which often contains a large number of immature T cells. Although the metastatic lesions are also associated with abundant lymphocytes, their characteristics have not been assessed in detail. In this study, the phenotype was analyzed and compared with those in their primary lesions. Nine metastatic thymomas were obtained from seven patients. In the metastatic lesions, CD1a+ cells and CD4(+)CD8(+) cells accounted for 77.7 +/- 10.6 and 52.3 +/- 15.8% of all the lymphocytes, respectively. In five primary lesions and their metastatic lesions, CD3(-)CD4(+)CD8(-) cells accounted for 23.9 +/- 16.9 and 45.2 +/- 15. 5% of the CD4(+)CD8(-) cells, respectively. CD69 was expressed on 70. 9 +/- 9.5 and 53.1 +/- 11.8% of the CD4(+)CD8(-) cells, respectively. These results indicate that the metastatic lesions of thymoma are associated with abundant immature T cells which are phenotypically less mature than those in their primary lesions.

Adult↗

PubMed1998

Quantitative measurement of mucosal wave by high-speed photography in excised larynges.

The movement characteristics of mucosal waves of the vocal fold are important components in normal phonation. Quantitative studies of the mucosal wave have used stroboscopic techniques from a supraglottic view. The current study measured displacement of mucosal epithelium during experimental phonation by using high-speed photography from an infraglottic view. Effects of thyroarytenoid contraction, increased mean airflow rate, and variation of vocal fold length were examined in canine larynges. Top and bottom vocal fold "lip" amplitude, fundamental frequency, and phase difference were the dependent variables examined. Thyroarytenoid contraction increased the amplitude of the top and bottom lips, decreased the fundamental frequency, and increased the phase difference. Increase in airflow through the glottis decreased the top lip amplitude and phase difference and appeared to increase the fundamental frequency and to decrease the bottom lip amplitude. Vocal fold lengthening decreased the bottom lip amplitude and increased the fundamental frequency and appeared to decrease the top lip amplitude and phase difference.

Animals↗

PubMed1998

[Laterofixation of the vocal cord by Ejnell's operation for bilateral vocal cord paralysis].

In patients with bilateral vocal cord paralysis, several therapeutic techniques have been proposed to improve laryngeal obstruction. Since 1990, we have performed Ejnell's operation on six patients, one male and five females, suffering from bilateral vocal cord paralysis. Tracheostomy had been performed in four patients prior to their consultation. Five patients underwent a breathing capacity examination before and after the operation. Four of the patients showed improvement in breathing capacity and the tracheostoma was closed in those four patients. There was little aspiration problem during the postoperative follow-up period. Our experience suggests that Ejnell's operation is technically simple and should be useful in the treatment of bilateral vocal cord paralysis.

Adult↗

PubMed1998

[Pulmonary edema due to acute airway obstruction immediately after tracheal extubation].

A 33-year-old male was scheduled for tonsillectomy and pharyngoplasty due to sleep apnea syndrome. The intubation was uneventful following induction with thiamylal and vecuronium. Anesthesia was maintained with O2-N2O-sevoflurane. No complications were observed during the 90 min operation. After the termination of the anesthesia, a hyperadrenergic state was observed: arterial pressure and heart rate rose to 230/135 mmHg and 135 bpm, respectively. Immediately after extubation, he developed dyspnea with tracheal tag and stridor, and became cyanotic despite the use of a simple oxygen mask and assisted ventilation. Laryngospasm was suspected. The patient was reintubated and suctioned; pink, frothy sputum was not obtained. Arterial blood gases 5 minutes after reintubation revealed a pH of 7.24, Pao2 86 mmHg (FIo2 1.0), and Paco2 54 mmHg. Chest X-ray 30 minutes after reintubation revealed bilateral diffuse alveolar infiltration. The diagnosis was interstitial pulmonary edema. The patient was ventilated mechanically by applying a positive end-expiratory pressure of 5cm H2O, and furosemide and dopamine were administered intravenously. The patient was extubated the next day, and discharged from hospital ten days later. We considered that the lung edema was induced by the severe negative pressure generated by inspirating against a closed upper airway, as well as by the hyperadrenergic state and severe hypoxemia observed during and after extubation.

Acute Disease↗

PubMed1997

A newly identified membrane protein localized exclusively in intracellular organelles of neurons.

We report here cloning of the cDNA of a novel membrane protein, termed p24, which, of the eight mouse tissues tested, was found only in brain where it is localized exclusively in neurons. The cDNA encodes 196 amino acids with a molecular weight of approximately 24000. P24 contains two putative membrane spanning domains and a sequence in the hydrophilic tail homologous to the microtubule-binding domain of microtubule-associated proteins, such as TAU and MAP-2. We prepared antibodies to p24 and demonstrated that the protein is rich in nerve fibers of the cerebral cortex, anterior cerebral nuclei and hypothalamus. When neuroblastoma Neuro 2a cells were treated with retinoic acid to induce differentiation, p24 mRNA increased but the p24 protein was not detected. The protein expressed from the p24 cDNA in non-neuronal Cos-7 cells was 24 kDa in size and were localized only in lysosomes. These findings indicate that p24 is a neuron-specific membrane protein localized in intracellular organelles of highly differentiated neural cells and suggest that it may play a role in the neural organelle transport system.

Amino Acid Sequence↗

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↗