Biomedical subjects

T Kawase

Publications and source records attributed to T Kawase.

At least 73 records · Page 4Linked to original sources

PubMed2000

Cisplatin-induced apoptotic cell death in Mongolian gerbil cochlea.

Cisplatin is well known to cause cochleotoxicity. In order to determine the underlying mechanisms of cisplatin-induced cell death in the cochlea, we investigated the apoptotic changes and the expression of bcl-2 family proteins controlling apoptosis. Mongolian gerbils were administered 4 mg/kg/day cisplatin consecutively for 5 days. The cisplatin-treated animals showed a significant deterioration in the responses of both distortion product otoacoustic emissions and the endocochlear potential as compared with those of the age-matched controls, suggesting outer hair cell and stria vascularis dysfunction. The presence of DNA fragmentation revealed by a terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling method was recognized in the organ of Corti, the spiral ganglion, and the stria vascularis in the cisplatin-treated animals whereas almost negative results were obtained in the control animals. The nuclear morphology obtained by Hoechst 33342 staining revealed pyknotic and condensed nuclei, confirming the presence of the characteristic features of apoptosis. A significant increase and reduction in the number of bax- and bcl-2-positive cells, respectively, following cisplatin treatment was observed in the cells of the organ of Corti, the spiral ganglion, and the lateral wall. These findings suggest a critical role for bcl-2 family proteins in the regulation of apoptotic cell death induced by cisplatin. The underlying mechanisms of the cisplatin-induced cell death are discussed.

Animals↗

PubMed2000

Purification and characterization of a 49-kDa chitinase from Streptomyces griseus HUT 6037.

A 49-kDa chitinase (pI7.3) was purified to homogeneity from the culture supernatant of Streptomyces griseus HUT 6037 by ultrafiltration, DEAE-Sephadex A-50 and Sephadex G-100 column chromatographies, and chromatofocusing. The purified enzyme was stable up to 40 degrees C. The N-terminal amino acid sequence of the enzyme was highly homologous to the N-terminal region of the fibronectin type III-like domain of S. olivaceoviridis chitinase 01 belonging to family 18 glycosyl hydrolases. The 49-kDa chitinase hydrolyzed partially N-acetylated chitosan more easily than colloidal chitin. The hydrolyzate of 54% deacetylated chitosan by the enzyme was separated by CM-Sephadex C-25 column chromatography. The structures of the oligosaccharides obtained were determined by MALDI-TOF MS analysis combined with exo-glycosidase digestion. In addition to GlcNAc, (GlcNAc)2, and (GlcNAc)3, hetero-chitooligosaccharides with GlcNAc at the reducing end were detected. Thus, the specificity of the enzyme for the hydrolysis of the beta-1,4-glycosidic linkages in partially N-acetylated chitosan was similar to that of the family 18 chitinases.

Journal Article↗

PubMed2000

Sustained viral response is rarely achieved in patients with high viral load of HCV RNA by excessive interferon therapy.

Adequate dosing of interferon (IFN) and its cost-effectiveness for sustained virological response were evaluated in relation to viral load and subtype. Prospective analysis of IFN therapy on 326 patients with chronic hepatitis C free from cirrhosis was performed using 9 or 6 million unit (MU) of IFN for six months daily and/or three times a week. Sustained virological response was achieved in 50-94% of patients with < or =2 x 10(4) copies/ml (competitive RT-PCR) or <100 x 10(3) copies/ml (Amplicor monitor) of HCV RNA by 468-1206 MU of IFN, but response was only 0-25% of the patients with > or =2 x 10(5.5) copies/ml (competitive RT-PCR) or >200 x 10(3) copies/ml (Amplicor monitor), even with 468-1206 MU of IFN. A high sustained rate was demonstrated in patients with 100-200 x 10(3) copies/ml of HCV RNA by 901-1206 MU of IFN, in comparison to that with < or =900 MU of IFN. Multivariate analysis showed that IFN dose had a significant value for the efficacy of IFN therapy in patients presenting 100-200 x 10(3) copies/ml of HCV RNA. Cost efficacy analysis indicated that it cost approximately $10,000, $26,000, and $50,000-227,000 for one person-viral eradication in the patients with <100, 100-200, and >200 x 10(3) copies/ml, respectively. High-dose IFN is only cost effective in patients with intermediate viral loads, and IFN therapy could be recommended in patients with <200 x 10(3) copies/ml of HCV RNA.

Adolescent↗

PubMed2000

Cytostatic action of enamel matrix derivative (EMDOGAIN) on human oral squamous cell carcinoma-derived SCC25 epithelial cells.

During surgical treatment of periodontal disease, enamel matrix derivative (EMD) is topically applied as a substitute for extracellular matrix in order to facilitate regeneration of damaged periodontal tissue. However, the mechanism for EMD action is poorly understood. We have now examined the effects of EMD on the proliferation of oral epithelial (SCC25) cells in vitro. After 3 days of treatments, EMD (25 100 microg/ml) dose-dependently inhibited cell division and concomitantly arrested cell cycle at the G1 phase. Prior to this inhibition, EMD significantly up-regulated p21WAF1/cip1, a cyclin-dependent kinase inhibitor, induced G1-arrest, and inhibited DNA synthesis. In addition, EMD down-regulated expression of cytokeratin-18 (CK18) protein, which was most due to decreased production, but less to increased degradation. However, EMD did not discernibly increase the number of apoptotic cells over 8 days of treatment. These findings indicate (1) that EMD acts as a cytostatic agent, rather than a cytotoxic agent, on epithelial cells, and (2) that this anti-proliferative action is probably due to p21WAF1/cip1-mediated G1-arrest. Furthermore, our in vitro cellular data clearly verify and provide an explanation for the clinical observation that EMD application suppresses the down-growth of junctional epithelium onto dental root surfaces, a process that frequently interferes with the formation of new connective tissue attachments.

Adolescent↗

PubMed2000

Antitumoral effects of defective herpes simplex virus-mediated transfer of tissue inhibitor of metalloproteinases-2 gene in malignant glioma U87 in vitro: consequences for anti-cancer gene therapy.

We set up experiments to evaluate the effects of defective herpes simplex virus (HSV)-mediated in vitro gene transfer of tissue inhibitor of metalloproteinases-2 (TIMP-2) in malignant glioma cells. Intrinsic TIMPs are known to be inhibitors of the strong invasive activities of matrix metalloproteinases in malignant gliomas. The defective HSV vectors dvSRaTIMP2 was engineered to express human TIMP-2 (hTIMP-2) with a combination of replication-competent HSV mutant, temperature-sensitive HSV-tsK, and amplicon plasmid-containing hTIMP-2. The hTIMP-2 gene was driven by the simian virus 40 promoter. The helper virus (HSV-tsK) was thermosensitive; consequently, this vector could proliferate only at 31.5 degrees C. After infection of U87 human glioblastoma cells with the vector in vitro, expression of TIMP-2 was confirmed by reverse zymography. The U87 cells infected in vitro either with dvSRaTIMP2 or HSV-tsK were efficiently destroyed under replication-permissive conditions (at 31.5 degrees C) and significantly lowered under replication-nonpermissive conditions (at 37 degrees C). The invasive activity of U87 was clearly inhibited by dvSRaTIMP2 infection at both 31.5 degrees C and 37 degrees C. Our studies suggest that TIMP-2 expressing the defective HSV vector is possibly useful for the treatment of malignant brain tumors.

Animals↗

PubMed2000

Lateral ventricular meningioma encapsulated by the dura-like membrane.

The first case of a ventricular meningioma that was encapsulated by the dura-like membrane is reported. Magnetic resonance imaging (MRI) showed a heterogeneous mass with a low intensity rim in the trigone of the right lateral ventricle of a 63-year-old male. Histological examination revealed that the tumor was a transitional meningioma encapsulated by a thick dura-like membrane. Moreover, abundant clusters of the dura-like connective tissue existed in the tumor, indicating that both the dura-like capsule and the dura-like clusters in the tumor were created by the tumor cells.

Dura Mater↗

PubMed2000

CT scans essential after posttraumatic loss of consciousness.

The frequency of "talk and deteriorate" in the emergency department (ED), subsequent deterioration of patients with seemingly "mild" head injury at the time of presentation, is summarized. Among the 1,073 patients with minor head injury treated in the last 5 years, five patients (0.5%) deteriorated in the ED. All of the five patients had experienced transient loss of consciousness (LOC) before presentation. Deterioration had occurred during treatment of trivial associated injuries in four-fifths of the cases. Computed tomography (CT) scans revealed four acute epidural hematomas and one cerebellar contusion. Retrospectively, immediate brain CT shortly after their arrival may have revealed the presence of traumatic intracranial hematomas before deterioration. Although routine use of CT scans in patients with mild head injury has been controversial, the authors conclude that CT scans should be taken if patients have experienced transient LOC to prevent or reduce the occurrence of deterioration in ED.

Adult↗

PubMed2000

Enlarged entry space for the transpetrosal approach.

This report describes the removal of the roof of the external auditory meatus in approaching the tentorial edge, the cerebropontine angle, hippocampal brainstem lesions, and upper clival lesions. This procedure not only provides more space in approaching the tentorial edge or upper brainstem, it also provides a wider entry space for approaching posterior fossa lesions. This approach is also for lesions located lower than the tentorium or in the upper clivus. There is still some confusion about the method for removing the roof of the external auditory canal. We describe the clinical experience and comprehensive surgical procedures used on cadavers. Our extended temporal craniotomy technique using the removal of the roof of the external auditory meatus is a simple, safe, and useful method for obtaining a wider entry space to approach deep perimesencephalic lesions and the posterior fossa.

Journal Article↗

PubMed2000

Glomus jugulare tumor presenting with intracerebellar hemorrhage.

What is believed to be the first case of a glomus jugulare tumor presenting with intracerebellar hemorrhage is described. A 25-year-old normotensive man suddenly suffered from severe headache, nausea, vomiting, vertigo, and ataxia due to an intracerebellar hemorrhage. Magnetic resonance imaging and angiography revealed a highly vascular jugulare foramen tumor extending into the intracranial space adjacent to the hematoma. Total removal of the tumor was performed successfully via the combined pre- and retrosigmoid approach, and the histologic diagnosis was a glomus jugulare tumor. We concluded that one of the numerous draining veins on the surface of intracranial tumor, which were observed during the operation, was the origin of the intracerebellar hemorrhage.

Case Reports↗

PubMed2000

Neurosurgery at Fujita Health University, Japan.

Neurosurgery at the Fujita Health University began in 1972 with Dr. Tetsuo Kanno. In 1973, he was joined by Dr. Kazuhiro Katada and in the year 1976, an independent neurosurgery department was established with Dr. Kanno as the Chief of Neurosurgery. Under his guidance the department continued to grow and by 1978, a neurosurgical residency program recognised by the Japanese Board of Neurosurgery was established. Integration of laboratory research and clinical experience is the hallmark of this program. The current philosophy is directed towards subspecialization and academic training. This article provides a brief overview of the rapid development of a Neurosurgical Centre to reach international acclaim under the guidance of Prof. Tetsuo Kanno.

Hospitals, University↗

PubMed2000

Medial (intra-cisternal) acoustic neuromas.

The clinical characteristics of "medial" or "intra-cisternal" acoustic neuroma (AN) treated in our institute were reviewed. Among 466 patients with ANs in our series during the last 20 years, 6 patients (1.3%) were considered to fill the criteria of medial AN definition. Compared with those with non-medial ANs, the patients with medial ANs show a tendency to have cerebellar and/or cranial nerve dysfunction (especially trigeminal and/or facial nerves) in addition to hearing loss at the time of initial presentation. On magnetic resonance imaging, medial AN is visualized as a multi-cystic mass lesion in the cerebello-pontine cistern without extension into the internal auditory canal in most cases. Although total removal of tumor was achieved in all cases, the results of preservation of facial nerve function were not satisfactory. Medial AN can be considered as a clinical, but not pathological, subtype in terms of the functional outcomes of the facial nerve and hearing.

Facial Nerve↗

PubMed2000

Apparent change of masking functions with compression-type digital hearing aid.

Signal perception ability under conditions of a narrow band masker in subjects with hearing aids was examined using a theoretical model of the auditory nerve fibre (ANF) with a deteriorated tuning curve in addition to measurements of actual masking function in subjects wearing hearing aids. The results obtained indicate that the apparent masking function could be affected by the frequency-gain character as well as by the degree of compression. Usually, the compression-type of amplification with flat and/or high-frequency weighted characteristics improves not only the apparent thresholds but also the apparent masked thresholds under conditions of lower frequency masking. On the other hand, a low-frequency masker amplified by a higher gain with low-frequency weighted amplification could cause larger upward-masking effects on the signal perception of the higher frequency signal in some conditions. The present study may contribute to our understanding of the underlying mechanisms of the effects of different amplification by the aid.

Acoustic Stimulation↗

PubMed2000

F-waves and facilitated late responses of the mentalis muscle in patients with a cerebrovascular accident.

F-waves in the extremities result from the backfiring of antidromically activated anterior horn cells and F-waves of the mentalis muscle can be also elicited after stimulation of the marginal mandibular branch of the facial nerve. In order to investigate the influence of the descending pathway of the excitability of the facial motonucleus, the F-wave of the mentalis muscle and the facilitated late response, which follows F-waves and which seems to be the snout reflex due to their similar latency and habituation, were studied in 11 conscious patients with a hemispheric cerebrovascular accident (CVA) presenting with hemiparesis, and in 10 unconscious patients with CVA or head injury. The duration and the persistence of the F-waves increased significantly statistically on the normal side in the CVA patients compared with those of the palsy side and the normal subjects. In comatose patients the F-waves and the facilitated late response were not elicited. The latency (46.1 +/- 13.3 msec) of the facilitated late responses in the unconscious patients tended to increase compared with the latency (36.6 +/- 4.3 msec) in the conscious patients. These findings suggest that the hyperexcitability of the facial motoneuron is ipsilateral to any hemispheric lesion; the hemispheric lesion exerts a bilateral excitatory influence on the interneuron of the facilitated late response: and that the reticular formation may influence the facial motoneuron and any interneurons concerned in the facilitated late response. F-waves and facilitated late responses should be further examined as neurophysiologically useful diagnostic methods.

Consciousness Disorders↗

PubMed2000

Developmentally and regionally regulated expression of growth hormone secretagogue receptor mRNA in rat brain and pituitary gland.

Distribution and development of growth hormone secretagogue receptor (GHS-R) mRNA expression in rat brain and pituitary gland were examined using ribonuclease protection assay. In adult male rats, GHS-R mRNA levels were highest in the pituitary gland, whereas those in the hypothalamus and hippocampus were 57 and 30% of those in the pituitary gland, respectively. Less abundant but detectable levels of GHS-R mRNA were found in the midbrain, pons, and medulla oblongata, but expression was barely detectable in the cerebellum and cerebral cortex. The expression of GHS-R mRNA was detected at late gestation (embryonic day 19) in the pituitary gland, hypothalamus, and brainstem. The mRNA levels increased with age in the pituitary gland, and decreased postnatally in the brainstem, while they remained constant in the hypothalamus during development. In contrast, GHS-R mRNA was not detectable in the hippocampus during the fetal period, but was first detected on postnatal day 7. Expression of GHS-R mRNA was also examined in the spontaneous dwarf rat (SDR), a model for isolated GH deficiency, to examine alterations in GHS-R mRNA expression in a GH-deficient state. GHS-R mRNA levels in the pituitary gland of SDRs were higher than those of control rats, suggesting negative regulation of GHS-R mRNA by GH in this region. GHS-R mRNA levels increased in the hypothalamus of female, but not in male SDRs. In contrast, GHS-R mRNA levels were not affected by GH in the brainstem and hippocampus. These results indicate that region-specific, developmentally regulated expression of GHS-R mRNA may reflect divergent physiological roles of GHS/GHS-R in distinct regions of the central nervous system and the pituitary gland.

Age Factors↗

PubMed2000

The time-course of the effects of contralateral sound on the level of distortion product otoacoustic emissions.

The effects of the addition of contralateral noise on the level of distortion product otoacoustic emissions (DPOAEs) were examined. In the present study, the DPOAEs were recorded for a relatively long period (2 minutes), and the time-course of the effects of contralateral sound on the level of DPOAEs were considered. In general, the addition of the contralateral noise resulted in suppression of the level of DPOAEs. The time-course of this suppression appeared to depend on the level of the contralateral noise. When the level of the contralateral noise was low, the suppression of the level of DPOAEs seemed to be largely unchanged for at least 2 minutes. In contrast, when a relatively high level of contralateral noise was used, the suppression of the level of DPOAEs decreased with time.

Acoustic Stimulation↗

PubMed2000

Primary osteosarcoma of the sphenoid bone with extensive periosteal extension--case report.

A 28-year-old male presented with a primary osteosarcoma of the sphenoid bone with extensive periosteal extension manifesting as severe headache and right exophthalmos. Computed tomography (CT) and magnetic resonance imaging revealed an anterior middle cranial fossa tumor extending into both the orbit and the extracranial space. However, roentgenography and CT with bone windows showed no marked osteolytic changes of the sphenoid bone. Total removal of the tumor was performed via the orbitozygomatic approach. Surgery revealed that the tumor had extended periosteally without macroscopic bone destruction, but no obvious abnormalities of the skull. The histological diagnosis was osteosarcoma. The patient was treated with chemotherapy and radiation therapy, but died of tumor recurrence 10 months after the surgery.

Adult↗

PubMed2000

Hypoglossal neurinoma--two case reports.

Two patients presented with hypoglossal neurinoma extending both intra- and extracranially. A 63-year-old male presented with right trigeminal neuralgia and hypoglossal nerve paresis. The intracranial part of the tumor was removed totally via a suboccipital craniectomy. Over-coagulation of the venous collaterals, particularly the emissary veins, resulted in dural venous sinus thrombosis and cerebellar infarction. Unfortunately this patient died. A 48-year-old male presented with pareses of the VII, IX, X, XI, and XII cranial nerves and cerebellar sign. The tumor extended both extra- and intracranially, and was completely removed by opening the hypoglossal canal and the jugular foramen without over-coagulation of the venous collaterals. Preservation of the venous collaterals is very important for the prevention of postoperative venous complications.

Cerebral Angiography↗

PubMed2000

Reduced size of the cochlear branch of the vestibulocochlear nerve in a child with sensorineural hearing loss.

A 12-year-old female patient presented with unilateral sensorineural hearing loss. Distortion-product otoacoustic emission testing failed to reveal any measurable emissions in the affected side. MR imaging did not reveal labyrinthine malformation. Three-dimensional Fourier transformation-constructive interference in steady-state MR images showed a thin cochlear branch. We speculated that mumps infection or developmental malformation caused the unilateral sensorineural hearing loss.

Child↗