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Biomedical subjects

K Tabuchi

Publications and source records attributed to K Tabuchi.

At least 19 recordsLinked to original sources
PubMed2001

Protection of outer hair cells from reperfusion injury by an iron chelator and a nitric oxide synthase inhibitor in the guinea pig cochlea.

To examine whether an active process of the cochlea was injured by ischemia-reperfusion, time courses of distortion-product otoacoustic emissions (DPOAEs) were examined before, during and after 30 min cochlear ischemia using albino guinea pigs. DPOAEs decreased to the minimum level when the animals were subjected to ischemia. When the cochlea was recirculated, DPOAEs initially recovered with time until 20 min after the onset of reperfusion. However, thereafter the amplitude of DPOAEs gradually decreased toward the noise level. Administration of deferoxamine (an iron chelator) or N-nitro-L-arginine (a nitric oxide synthase inhibitor) ameliorated this decrease of DPOAEs during reperfusion and significantly increased the DPOAE amplitudes 60 min after the onset of reperfusion as compared with those in non-treated animals. These results suggest that cochlear reperfusion as well as ischemia injured the active process of the cochlea and that free radicals and nitric oxide play important roles in this injury.

Animals↗
PubMed2001

Fas ligand expression and depletion of T-cell infiltration in astrocytic tumors.

Fas (APO-1/CD95) ligand (FasL) and its receptor, Fas, play a key role in the regulation of apoptosis in the immune system. FasL acts as a cytotoxic effector molecule to Fas-expressing malignant tumor cells; however, it has recently been suggested that FasL also acts as a possible mediator of tumor immune privilege. We studied FasL expression in glioblastoma cell lines and a series of human glioma specimens by Western blotting and immunohistochemistry. In addition, quantitative analysis of T-cell infiltration in these tumors was performed. FasL expression was seen in all cell lines and in 9 of 14 specimens by Western blotting and immunohistochemistry. The distribution of FasL was recognized in the cytoplasm of tumor cells (5 of 9) and in the vascular endothelium (4 of 9). Both types of FasL expression were associated with a significant reduction (p < 0.05) in T-cell infiltration when compared with FasL-negative areas within the same tumor or FasL-negative specimens. Since T-cell apoptosis could be induced by FasL-expressing tumor cells, the present findings suggest that apoptosis induction by FasL expressed on tumor cells and/or vascular endothelium might be one mechanism for T-cell depletion in astrocytic tumor tissues.

Adult↗
PubMed2001

123I-IMP SPET in the diagnosis of primary central nervous system lymphoma.

We reviewed N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) single-photon emission tomography (SPET) images of brain tumours and assessed the usefulness of 123I-IMP SPET for the diagnosis of primary central nervous system (CNS) lymphoma. We analysed 52 tumours that showed enhancement on magnetic resonance imaging: 11 malignant lymphomas, 3 anaplastic astrocytomas, 17 glioblastomas, 12 meningiomas, 4 metastatic brain tumours and 5 other brain tumours. 123I-IMP uptake in the tumours on early (15-min) and delayed (4-h) scans was visually classified as high, moderate or low as compared with the contralateral brain cortex. Early and delayed 123I-IMP uptake ratios comparing tumours with contralateral brain cortex (T/N ratio) were also calculated. In malignant lymphomas, the visual uptake of 123I-IMP was moderate to high on the delayed scans. The delayed T/N ratios were significantly higher than the early ratios (P<0.05) and all lymphomas, with the exception of one small one, had delayed ratios greater than 0.9. In non-lymphomatous tumours, the visual uptake of 123I-IMP was low on the delayed scans. The delayed T/N ratios were significantly lower than the early ratios (P<0.01) and all non-lymphomatous tumours had delayed ratios of less than 0.8. The T/N ratios of lymphomas were significantly higher than those of non-lymphomatous tumours on both early and delayed scans (P<0.0001). These results suggest that 123I-IMP SPET may be a useful tool in the differential diagnosis of primary CNS lymphoma.

Adolescent↗
PubMed2001

Expression of prostaglandin H synthase-2 in human brain tumors.

Numerous studies have demonstrated that prostaglandin H synthase-2 (PHS-2) is involved in gastrointestinal carcinogenesis, and that nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit PHS, can reduce the risk of colon cancer. In brain tumors, elevated prostaglandin production and its correlation to anaplastic grade of gliomas have been demonstrated. To determine whether the increased prostaglandin production is due to enhanced expression of PHS-2 and whether the up-regulation of PHS-2 has any correlation to histopathological findings in brain tumors, we evaluated the profile of PHS expression in several human glioma cell lines and surgical specimens from patients with various types of brain tumors. In glioma cell lines, five out of six cell lines showed constitutive expression of PHS-2, whereas PHS-1 was weakly expressed in all of them. All surgical specimens, except an ependymoma, which expressed both isozymes equally, expressed PHS-2 mRNA predominantly. Immunohistochemistry of various types of brain tumors, including six glioblastomas, nine astrocytomas, six meningiomas, five medulloblastomas, four craniopharyngiomas, three ependymomas, three neurinomas, two oligodendrogliomas, two malignant lymphomas, two dysembryoplastic neuroepitherial tumors and one metastatic brain tumor showed PHS-2 staining in most cases. In gliomas, astrocytomas (grade 2 and 3) were strongly stained, but the staining intensity of glioblastomas was relatively weak. Meningiomas and a metastatic brain tumor were also strongly stained. Our data thus suggest that most brain tumors express PHS-2, which may also play a role in tumorigenesis in the brain.

Adolescent↗
PubMed2001

Embryonic neuronal death due to neurotrophin and neurotransmitter deprivation occurs independent of Apaf-1.

Apoptotic protease-activating factor-1 (Apaf-1), dATP, and procaspase-9 form a multimeric complex that triggers programmed cell death through the activation of caspases upon release of cytochrome c from the mitochondria into the cytosol. Although cell death pathways exist that can bypass the requirement for cytochrome c release and caspase activation, several gene knockout studies have shown that the cytochrome c-mediated apoptotic pathway is critical for neural development. Specifically, the number of neuronal progenitor cells is abnormally increased in Apaf-1-, caspase-9-, caspase-3-deficient mice. However, the role of the cytochrome c cell death pathway for apoptosis of postmitotic, differentiated neurons in the developing brain has not been investigated in vivo. In this study we investigated embryonic neuronal cell death caused by trophic factor deprivation or lack of neurotransmitter release by analyzing Apaf-1/tyrosine kinase receptor A (TrkA) and Apaf-1/Munc-18 double mutant mice. Histological analysis of the double mutants' brains (including cell counting and terminal (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) staining) reveals that neuronal cell death caused by these stimuli can proceed independent of Apaf-1. We propose that a switch between apoptotic programs (and their respective proteins) characterizes the transition of a neuronal precursor cell from the progenitor pool to the postmitotic population of differentiated neurons.

Animals↗
PubMed2001

Does xanthine oxidase contribute to the hydroxyl radical generation in ischemia and reperfusion of the cochlea?

We investigated the effect of a hydroxyl radical scavenger, 1,3-dimethyl-2-thiourea (dimethylthiourea), and two xanthine oxidase inhibitors, oxypurinol and allopurinol, on the threshold shift of the compound action potential (CAP) after transient ischemia of the cochlea. Transient ischemia of 30 min duration was induced in albino guinea pigs via a skull base approach. The animals were treated with perilymphatic perfusion of dimethylthiourea, oxypurinol or allopurinol from 10 min before the onset of ischemia to 4 h after the termination of ischemia. Dimethylthiourea ameliorated the CAP threshold shifts at 4 h after the onset of reperfusion in a dose-dependent manner. However, oxypurinol and allopurinol did not affect the post-ischemic cochlear dysfunction. These results imply that the hydroxyl radical plays an important role in generation of cochlear dysfunction induced by ischemia-reperfusion and that xanthine oxidase may not be the primary source of this radical.

Action Potentials↗
PubMed2001

Ischemia-reperfusion injury of the cochlea: effects of an iron chelator and nitric oxide synthase inhibitors.

Release of free iron from cellular stores and activation of nitric oxide synthase (NOS) has been implicated in a wide variety of cochlear injuries. In order to evaluate the effects of deferoxamine (a iron chelator), 3-bromo-7-nitroindazole (a relatively selective neuronal NOS (nNOS) inhibitor) or aminoguanidine (a relatively selective inducible NOS (iNOS) inhibitor) on the post-ischemic cochlear dysfunction, albino guinea pigs were subjected to 30 min ischemia, and the threshold shifts of the compound action potential (CAP) from pre-ischemic values were compared with those of control animals 4 h after the onset of reperfusion. A statistically significant reduction in the post-ischemic CAP threshold shift was observed in the animals treated with deferoxamine or 3-bromo-7-nitroindazole. However, aminoguanidine did not affect the post-ischemic CAP threshold shift. These results suggest that free iron and nNOS play deleterious roles in the cochlear injury induced by transient ischemia.

Action Potentials↗
PubMed2001

Transnasal bamboo foreign body lodged in the sphenoid sinus.

Transnasal sphenoid sinus foreign body is a rare condition. We report a very rare case of transnasal bamboo foreign body lodged in the sphenoid sinus without damages to the orbital wall or skull base. A 69-year-old man fell down onto a bamboo stick, which snapped after penetrating his face through the right nostril. CT demonstrated that the bamboo stick stuck into the middle meatus, penetrated the ethmoid sinus just medial to the lamina papyracea and reached to the sphenoid sinus. No abnormal findings were detected in the orbit or skull base. The foreign body was removed from the nasal cavity without any complication. The endoscope was useful for evaluating possible injuries in the orbit and skull base and confirming the absence of residual foreign bodies.

Aged↗
PubMed2001

Relief of post-tonsillectomy pain by release of lidocaine from fibrin glue.

OBJECTIVES: Pain inevitably develops after resection of the palatine tonsil (tonsillectomy). Therefore, we applied a mixture of lidocaine and fibrin glue to the tonsillar fossae immediately after tonsillectomy and evaluated its analgesic effects. STUDY DESIGN: A prospective randomized trial. METHODS: Seventy-four consecutive patients who had undergone tonsillectomy by the same surgeon (S.K.) were allocated by the sealed envelope method into three groups. After routine tonsillectomy, the operation was terminated in group A (control group), but the bilateral tonsillar fossae were covered with 1 mL fibrin glue using CaCl2 as solution to dissolve thrombin in group B and using 4% lidocaine chloride instead of CaCl2 in group C. No significant difference was observed in age or sex among the three groups. Analgesic effects were evaluated in terms of the postoperative days required until the patient began to eat normally and the postoperative days on which the patient desired analgesic administration. RESULTS: The mean postoperative days until the patient began to eat normally were 4.22 in group A and 3.78 in group B, showing no significant difference, but 2.83 in group C, being significantly shorter (P <.05). The mean postoperative days on which analgesic administration was necessary were 4.56 in group A and 4.91 in group B, showing no significant difference, but 2.88 in group C, being significantly shorter (P <.05). CONCLUSION: This method can be readily performed, requires no special treatment, and appears to have adequate pain-relieving effects.

Adult↗
PubMed2001

Expression of ICAD-l and ICAD-S in human brain tumor and its cleavage upon activation of apoptosis by anti-Fas antibody.

ICAD / DFF is a downstream molecule of caspases, participating in nuclear DNA fragmentation during apoptosis. ICAD / DFF binds CAD / DFF40 and inhibits its DNase activity. ICAD / DFF has two alternative isoforms, long isoform (ICAD-L / DFF45) and short isoform (ICAD-S / DFF35). We have studied the presence and functional status of ICAD / DFF in human glioma cell lines. All cell lines tested expressed both ICAD-L and ICAD-S. When the cultured glioma cells were exposed to anti-Fas antibody, these isoforms were degraded prior to the fragmentation of the nuclear DNA, indicating that the ICAD / DFF expressed in cultured glioma cells was potentially functional. In primary brain tumors and normal brain tissues, there was a difference in the expression level between ICAD-L and ICAD-S. In glioblastomas, ICAD-S was more abundant than ICAD-L. In contrast, ICAD-L was more abundant than ICAD-S in medulloblastomas. The present findings suggest that primary brain tumors and normal brain constitutively express ICAD / DFF, and that there is a difference between the expression levels of ICAD-L and ICAD-S.

Antibodies, Monoclonal↗
PubMed2001

Poly(adenosine diphosphate-ribose) synthetase inhibitor 3-aminobenzamide alleviates cochlear dysfunction induced by transient ischemia.

The present study was undertaken to determine the possible deleterious role played by poly(adenosine diphosphate-ribose) synthetase (PARS) in cochlear ischemia-reperfusion injury. Transient ischemia of the cochlea was induced in albino guinea pigs for 15, 30, or 60 minutes by pressing the labyrinthine artery at the porus acusticus internus. The animals were given intravenous 3-aminobenzamide (a PARS inhibitor) or physiological saline solution I minute before the onset of reperfusion. The compound action potential thresholds were measured before the onset of ischemia and 4 hours after the onset of reperfusion. A statistically significant reduction in the postischemic compound action potential threshold shift was observed in the animals treated with 3-aminobenzamide after 15 or 30 minutes of ischemia, whereas no statistical difference was found after 60 minutes of ischemia. These results suggest that excessive activation of PARS exerts deleterious effects on the cochlear injury induced by transient ischemia.

Action Potentials↗
PubMed2001

Adoptive immunotherapy for malignant brain tumors using human peripheral blood mononuclear cells activated by the Streptococcal preparation OK-432.

Adoptive immunotherapy using OK-432-activated mononuclear cells (OK-MCs) offers cell-mediated and cytokine-mediated pathways for antitumor activity. The effectiveness of direct intratumoral administration of OK-MCs via a catheter/reservoir system was studied in patients with malignant brain tumors. Seventeen patients, 12 with malignant glioma, four with metastatic adenocarcinoma, and one with primary sarcoma of the brain, were treated by OK-MC therapy (1.0 to 11.2 x 10(7) cells/person) between June 1989 and April 1999. The OK-MC therapy was given to patients with tumors progressing despite previous cytoreductive surgery, radiation, or chemotherapy. Adverse effects seen after the therapy were fever in 10 patients, seizure in two patients, and hypotension in one patient. Evaluation by computed tomography or magnetic resonance imaging revealed that seven patients showed no change including three with minor response, and 10 showed progressive disease. Adoptive immunotherapy using OK-MC was safe and well tolerated, but the therapeutic potential is limited.

Adenocarcinoma↗
PubMed2001

Brain specific human genes, NELL1 and NELL2, are predominantly expressed in neuroblastoma and other embryonal neuroepithelial tumors.

NELL1 and NELL2 encode cysteine-rich amino acid sequences including six epidermal growth factor-like motifs, which contain signal peptides at the N-terminals. The deduced amino acid sequences of both genes are 55% identical and their cysteine stretch structures are conserved. NELL1 is expressed in the brain and kidney, whereas NELL2 is expressed specifically in the brain. The cell lineage expressing NELLs in the nervous system was investigated in established cell lines and central nervous system tumor tissues obtained from patients by Northern blot and reverse transcriptase-polymerase chain reaction analyses. NELL1 and NELL2 were predominantly expressed in neuroblastoma cell lines and little expressed in glioblastoma cell lines. NELL1 and NELL2 were also expressed in central neurocytoma, medulloblastoma, and some astrocytic tumors. Immunohistochemical analysis revealed that NELL2 protein was localized in the cytoplasm of neurons. These results suggest that NELL2 is predominantly expressed in the neuronal cell lineage in the human nervous system. NELL1 is expressed mainly in tumors in the neuronal cell lineage.

Aged↗
PubMed2001

Detection of simian virus 40 DNA sequence in human primary glioblastomas multiforme.

OBJECT: Deoxyribonucleic acid oncoviruses can induce neoplastic transformation of cells because their viral proteins interfere with antiproliferative cellular proteins. Simian virus 40 (SV40) is a DNA virus that induces the emergence of ependymomas, choroid plexus tumors, mesotheliomas, osteosarcomas, sarcomas, and various tumors when injected into newborn hamsters. Recently, approximately 60% of human ependymomas, choroid plexus tumors, and mesotheliomas were reported to contain and express SV40 DNA sequences. In this study the presence of SV40 DNA sequences was investigated in human brain tumors. METHODS: Three of 32 glioblastomas mutiforme (GBMs), but none of two ependymomas and five medulloblastomas, were found to possess SV40 DNA sequences when examined using polymerase chain reaction (PCR). The DNA sequence analysis of PCR-amplified fragments disclosed that the samples were identical to the regulatory region of SV40. All three GBMs, which arose in elderly patients with wild-type p53, were considered to be primary (de novo) tumors. Although each of the three tumors was immunohistochemically negative for SV40 T antigen, in situ hybridization successfully demonstrated the messenger RNA for SV40 T antigen. CONCLUSIONS: The results of this study indicate that latent infection of SV40 in elderly people may be implicated in the tumorigenesis of certain primary GBMs.

Adolescent↗
PubMed2001

[Fatal pulmonary embolism developing after tympanoplasty: a case report and incidence of pulmonary embolism at Toyooka Hospital].

We report a case of fatal pulmonary embolism (PE) developing after tympanoplasty. A 69-year-old woman underwent type III tympanoplasty for a middle ear cholesteatoma under general anesthesia. Operating time was 3 hours 27 minutes and anesthesia lasted 5 hours 9 minutes. The next morning, 14 hours 5 minutes after returning to the recovery room, the patient lost consciousness while getting out of bed. Although consciousness recovered transiently, she went into shock with cardiopulmonary arrest. Heart beat was regained after resuscitation with artificial respiration and cardiac massage, but her blood pressure was unstable. Echocardiography revealed right ventricular overload and pulmonary hypertension. Because PE was suspected, thrombolytic therapy was conducted to stabilize hemodynamics. Enhanced computed tomography (CT) of the chest showed bilateral pulmonary thromboembolism. The patient died of hypoxic encephalopathy 23 days after PE onset. We have seen 40 cases of PE at our hospital in the last 70 months. Five patients developed PE after surgery with a postoperative occurrence rate of 0.03% (5/16, 277), and 3 of them died. Enhanced CT in 19 of 21 cases (90.5%) before or just after the start of therapy for PE was useful in establishing the diagnosis. Although PE is rare in the field of otolaryngology and head and neck surgery, it may develop rapidly after any type of surgery resulting in a fatal outcome. It is thus important to establish diagnosis early and prevent such serious complications.

Aged↗
PubMed2001

[Transsphenoidal surgery assisted by navigation system].

Microneurosurgical technique combined with precise localization of lesions, can minimize the invasiveness of neurosurgical procedures. This report describes the usefulness of the neuronavigation system in transsphenoidal surgery. Nineteen transsphenoidal operations for sellar lesions including pituitary adenoma, clival chordoma, Rathke's cleft cyst and suprasellar germinoma were assisted by the optical tracking system (OTS). Operations were performed either through the sublabial or the endonasal approach using an operative microscope and, to a certain extent, the endoscope. All five microadenomas were totally removed. The tumors could be precisely localized by the navigation system. Four out of seven macroadenomas were totally removed. The operations were assisted effectively by the excellent guidance to the lateral margin of the tumors and the internal carotid arteries provided by the navigation system. The endonasal approach, in which the surgeon looks through a nostril at the sellar floor obliquely, was especially facilitated by the three-dimensional view provided by the system. The navigation system, however, was not useful in estimating the amount of the suprasellar residual tumor because of the dislocation that occurred during the tumor removal.

Adenoma↗
PubMed2001

Coronary artery bypass in dialysis patients.

This study evaluated the operative outcome of dialysis patients undergoing coronary artery bypass (CAB). In the past 6 years, 38 dialysis patients with a mean age of 57.5 years underwent CAB. Thirty-one operations were elective, and 7 were nonelective operations. Thirty-two operations were performed under cardiac arrest, 3 operations were performed under fibrillatory arrest, and 3 operations were performed without cardiopulmonary bypass. The average number of bypass grafts was 2.8. In all patients, the internal thoracic artery was used. Hospital mortality was 5.3%. Actuarial survival rates at 1, 3, and 5 years including all causes of death were 88%, 80%, and 72%, respectively. With improvements in perioperative management, coronary artery bypass can be performed with acceptable mortality and morbidity in dialysis patients. Complete revascularization without cardiopulmonary bypass is the ideal method and will increase in usage. However, the conventional CAB also provides acceptable results.

Adult↗