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Biomedical subjects

T Kawase

Publications and source records attributed to T Kawase.

At least 127 records · Page 7Linked to original sources
PubMed1998

Effect of hyperosmotic solutions on human brain tumour vasculature.

Reversible opening of the blood-brain barrier (BBB) has been used to increase delivery of chemotherapeutic agents into brain tumours, but it is complicated and requires general anaesthesia. Without affecting the normal BBB, and avoiding the complications of BBB modification by hyperosmotic solution, we tried an adequate minimal BBB disruption in brain tumours. Although the effect of BBB disruption on normal brain has been described, there are no reports of the effect of an impaired BBB on microcirculation. In this study, four patients underwent surgical resection of a glioblastoma multiforme (GM; n = 1), astrocytoma (n = 2), or metastatic brain tumour (n = 1). Epicerebral microcirculation was observed in the operative field. Serial fluorescein microangiograms of the tumour and peritumoural area were obtained before and after BBB disruption was introduced intra-operatively by retrograde infusion of mannitol introducing a catheter via the temporal superficial artery back to the carotid bifurcation. On the initial microangiogram, staining by the fluorescein dye was observed in the GM and metastatic tumour but not in the astrocytoma; no extravasation of fluorescein dye was observed in the peritumoural areas. After BBB disruption, fluorescein perfusion increased and extravasation of fluorescein dye from the venules was observed in the GM and the metastatic tumour and in the peritumoural area of both lesions; BBB disruption started from venules in the peritumoural area without affecting the normal brain. However, such effects were not observed in the astrocytomas after BBB disruption nor in normal brain tissue in any patient. It appears that the integrity of the BBB is less stable in the peritumoural area of GM and metastatic brain tumours than it is in astrocytomas or normal brain. Osmotic BBB disruption may offer a method for achieving global delivery of therapeutic agents to brain tumours and peritumoural areas.

Astrocytoma↗
PubMed1998

Generation of far field potentials from the trigeminal nerve in the cat.

This study provides evidence that far field potentials (FFPs) are generated from the trigeminal nerve in the cat. By stimulating the main mental nerve, three components (component 1, 0.59 +/- 0.06 ms; component 2, 0.81 +/- 0.06 ms; and component 3, 0.98 +/- 0.07 ms) were identified from surface electrodes. These three components were thought to be positive and negative FFPs because each component had a stationary peak and was distributed on the head being divided into positive and negative fields. Results of a study of lesions and recording compound action potentials (CAPs) defined the neural origins of those potentials as follows: component 1, the mandibular nerve at the mandibular foramen; component 2, the mandibular nerve at the foramen ovale; and component 3, somewhere between the gasserian ganglion and the trigeminal root. The amplitude of component 2 decreased when the mandibular nerve at the foramen ovale was immersed in cerebrospinal fluid (CSF) after opening the foramen and recovered to the prior level after closing the foramen with beeswax. We concluded that this transformation resulted in the change in electrical resistance of the volume conductor around the nerve.

Action Potentials↗
PubMed1998

Long-latency response to transcranial magnetic stimulation in patients with hemifacial spasm.

OBJECTIVE: We studied the long-latency response of the orbicularis oris muscle elicited with transcranial magnetic stimulation in patients with hemifacial spasm (HFS) and evaluated the excitability of the facial nucleus. METHODS: We compared the thresholds on both sides in 8 normal volunteers and 7 patients with hemifacial spasm. The thresholds were determined as the lowest intensity required to produce motor evoked potentials with an amplitude of at least 50 microV in the orbicularis oris muscle. Average values were given as means +/- standard deviation. Wilcoxon's rank sum test was used for comparisons between the sides of normal subjects and of patients with HFS with respect to the threshold stimulus. RESULTS: There was no significant difference between the thresholds on the two sides of the normal subjects (mean 1.88+/-5.30%, P > 0.05). In patients with HFS, there was a significant difference between the thresholds on the spasm side and the normal side (mean 20.7+/-13.0%, P < 0.05) In one patient studied after MVD, the difference between both sides disappeared. CONCLUSION: The difference between the thresholds in patients with HFS and the normalization in threshold after MVD suggested that the mechanism of HFS was hyperexcitability of the facial nucleus.

Adult↗
PubMed1998

Endoscopic papillary balloon dilation for the management of common bile duct stones: experience of 226 cases.

BACKGROUND AND STUDY AIMS: Endoscopic sphincterotomy is a widely accepted technique for the treatment of patients with common bile duct stones. However, it is still associated with occasional complications. The recently developed technique of endoscopic papillary balloon dilation seems to be a safe and effective procedure, and to have great potential for replacing endoscopic sphincterotomy. However, few reports have been published on the use of this technique for bile duct stones. The present study was undertaken to evaluate its safety and efficacy. PATIENTS AND METHODS: Endoscopic papillary balloon dilation was used to remove common bile duct stones in 226 consecutive patients including 41 patients of ASA classification III/IV, 41 elderly patients (> 80 years) 24 with liver cirrhosis, and 86 with periampullary diverticulum. After dilation of the papilla with a balloon diameter of 8 mm, the stones were retrieved. RESULTS: In conjunction with the use of a mechanical or/and electrohydraulic lithotriptor in 79 patients (35%) with large stones (> 10 mm in diameter), clearance of the common bile duct was achieved in 225 of 226 patients (99%) without serious complications, such as hemorrhage or severe pancreatitis; mild (n = 13) or moderate (n = 2) pancreatitis occurred in 7% of cases. CONCLUSIONS: Endoscopic papillary balloon dilation is a safe and effective technique for the treatment of common bile duct stones, even in high-risk patients.

Adult↗
PubMed1998

Clinical evaluation of a portable digital hearing aid with narrow-band loudness compensation.

A new portable digital hearing aid referred to as CLAIDHA (Compensate for Loudness by Analyzing Input-signal Digital Hearing Aid), which employs frequency-dependent amplitude compression based on narrow-band loudness compensation, was clinically evaluated in 159 subjects with hearing loss. The results of speech tests revealed better intelligibility compared with the subject's own hearing aids; the advantage of using CLAIDHA in daily life was also indicated by the results of a questionnaire completed by the subjects. In about 64% of the subjects with a flat, gradually sloping type of hearing loss, CLAIDHA was satisfactorily adopted for daily use. However, in the subjects with a steeply sloping type of hearing loss and subjects with losses mainly at high and low frequencies, with near-normal mid-frequency hearing. this loudness compensation scheme seems to be slightly less effective.

Aged↗
PubMed1998

Transcranial magnetic stimulation of the oculomotor and abducens nerves: determining the site of excitation in the cat.

The authors have attempted to stimulate the feline oculomotor and abducens nerves using a magnetic coil (MC) and to determine the optimal reliable MC position for eliciting motor evoked potentials. The authors have also determined the site of excitation to analyze the validity and potential advantages of this technique as a means of neurophysiologically studying the oculomotor and abducens nerves. The potentials of both of these muscles are evoked by MC placed to be symmetrical to the line connecting the vertex and the center of the eyeball on the side being examined, as the coil center corresponds to the midpoint of this line. The latencies of the motor responses of the superior rectus and lateral rectus were 1.08 +/- 0.22 and 1.02 +/- 0.21 msec, respectively, suggesting that magnetic stimulation excites both the oculomotor and the abducens nerve at the superior orbital fissure.

Abducens Nerve↗
PubMed1998

Periodontal ligament cell culture on the hydrophobic substrate coated with proteins of periodontal ligament fibroblast-conditioned medium.

In regenerating periodontal ligament (PDL) around the root of an artificial tooth, an important role is played by some physiologically active substance that promotes adhesion of the cells to the surface of the tooth root and induces cell proliferation and differentiation. In this study, the supernatant of the conditioned medium (CM) of dog periodontal ligament fibroblast (DPLF) was fractionated using an ion exchange chromatography-diethylaminoethyl (IEC-DEAE) column. DPLFs were cultured on hydrophobic dishes coated with each fraction. Cell proliferative activity and alkaline phosphatase (ALPase) activity, including electron microscopic features of the contact surface between the cells and the dish, were investigated. The DPLF-CM was separated by IEC-DEAE column into six fractions. Each fraction promoted an increase in DNA content and ALPase activity of the cultured DPLF, and especially remarkable were fractions 2 and 3. Fraction 2 at a molecular weight (Mw) of 210, 160, 85, 50 and 22 kD, and fraction 3 at Mw = 21 and 23 kD contained the type of proteins not found in other fractions. Electron microscopic analysis revealed that the cells in the coating group were in close contact with the surface of the dishes and that fine fibers protruding from the cell membrane clinged to the dishes. In the control group, a wide gap between the cells and the dishes was observed. These findings suggest that the DPLF-CM fractions contain specific physiological activating factors that induce proliferation and differentiation as well as cell adhesion of the DPLF cells.

Alkaline Phosphatase↗
PubMed1998

In situ phosphorylation of bone and dentin proteins by the casein kinase II-like enzyme.

Our previous studies suggested the possibility of extracellular phosphorylation of matrix phosphoproteins into more phosphorylated forms by mature odontoblasts and osteocytes (Mikuni-Takagi et al., 1995; Satoyoshi et al., 1995). To elucidate such phosphorylation of bone and dentin proteins, we developed a histochemical method using frozen sections to determine the sites of enzymatic processing by the casein kinase II-like enzyme. It was observed that proteins in bone, dentin, and predentin are phosphorylated by the endogenous enzyme when the tissue slices were incubated with [gamma-32P] GTP, suggesting that there are both substrates and the enzyme in these matrices. In vivo, phosphate donors, ATP and GTP, may be supplied through dentinal canals and osteocyte canaliculi. Immunohistochemical analysis of frozen sections showed that the extremely intense staining of phosphoserine residues by anti-phosphoserine antibodies appeared in dentin only after demineralization of the tissue samples. It implies that these phosphoserine residues become bound to mineral as soon as the phosphorylation is completed, thereby being inaccessible to the antibodies without demineralization. The data support our notion that the extracellular phosphorylation of dentin/bone proteins, regulated by the developmental stages of bone and dentin cells, occurs prior to matrix mineralization.

Alkaline Phosphatase↗
PubMed1998

Calcitonin gene-related peptide stimulates potassium efflux through adenosine triphosphate-sensitive potassium channels and produces membrane hyperpolarization in osteoblastic UMR106 cells.

In previous studies, we have shown that calcitonin gene-related peptide (CGRP) acutely inhibits 45Ca2+ uptake in osteoblastic UMR106 cells, and we have proposed that ATP-sensitive potassium (K(ATP)) channels are involved in mediating this action of CGRP. To directly test this proposed mechanism, we have now examined the effects of CGRP on both membrane potential (Em) and K+ mobilization in UMR106 cells, using specific fluorometric dye assays. CGRP (0.01-100 nM) induced membrane hyperpolarization in a dose-dependent manner, with a half maximal effect (ED50) at approximately 0.2 nM and a maximal effect at 100 nM. Both pinacidil (Pina; a K(ATP) channel opener) and forskolin (FSK) induced similar membrane hyperpolarization, but the actions of these three agents could be easily distinguished: both CGRP and Pina actions were well antagonized by glibenclamide (Glib; a selective K(ATP) channel blocker), whereas FSK action was strongly attenuated only by tetraethylammonium (a K(Ca) channel blocker) or compound H-89 (an inhibitor of cAMP-dependent protein kinases). Cells pretreated with Pina no longer responded to CGRP, but they could still respond to FSK; furthermore, pretreatment with FSK failed to block successive treatment with either CGRP or Pina. In parallel with observed changes in Em, CGRP (0.01-100 nM) decreased intracellular K+ concentrations ([K+]i) in a dose-dependent manner, with an ED50 identical to that obtained for alterations in Em. This action of CGRP was sensitive to Glib and had only slight sensitivity to tetraethylammonium; this CGRP effect was mimicked by Pina but not by FSK. Interestingly, CGRP significantly elicited changes in cell shape by a Glib-sensitive mechanism that included notable decreases in cross-sectional cytoplasmic area. These observations strongly support our proposal that CGRP primarily stimulates K+ efflux via activation of K(ATP) channels and thereby induces membrane hyperpolarization in UMR106 cells. Furthermore, our data also suggest that this cascade of initial cellular events may result in rapid changes in cell morphology and decreases in cellular area of the type that are thought to act as triggers for proliferation and/or differentiation in many cellular phenotypes.

Adenosine Triphosphate↗
PubMed1998

The acoustic reflex for filtered broadband stimuli: a lesser contribution of the lower frequency neurons.

The effects of the cut-off frequency of the filtered broadband stimuli on the human acoustic reflex (AR) were examined to observe the relation between the area of excitation in the cochlea and the AR response. The results obtained have indicated that all the input from the cochlear region does not equally contribute to trigger the AR equally; i.e., there is a lesser contribution from the frequency region below 700 Hz.

Adult↗
PubMed1998

Acute effects of combined administration of kanamycin and furosemide on the stria vascularis studied by distortion product otoacoustic emission and transmission electron microscopy.

Acute effects of kanamycin and/or furosemide administration on the stria vascularis of the guinea pig cochlea were assessed by distortion product otoacoustic emission (DPOAE) and transmission electron microscopy. Kanamycin alone failed to affect the DPOAE levels and ultrastructural changes. Furosemide alone caused a rapid but reversible fall of the DPOAE levels. No remarkable pathological changes in the strial vascularis were observed after a complete recovery of the DPOAEs. On the other hand, furosemide injection following kanamycin with a 2 hour interval resulted in two patterns of significant changes in the DPOAEs, namely, a sudden drop in the DPOAE levels 2 to 3 hours after furosemide injection and a gradual fall in the DPOAE levels immediately after the incomplete recovery from the furosemide-induced decrease of the DPOAE levels. Ultrastructural changes in the stria vascularis included numerous vacuoles in the strial marginal cells and increased electron density of the intermediate and basal cells. These physiological and morphological changes in the stria vascularis may imply new ototoxic features induced by kanamycin potentiated by furosemide.

Animals↗
PubMed1998

Plasma cell granuloma extending from the extracranial to the intracranial space associated with Epstein-Barr virus infection.

A 70-year-old male presented with a plasma cell granuloma extending from the extracranial to the intracranial space. Findings of preoperative magnetic resonance imaging and intraoperative observation indicated that the lesion extended from the temporal muscle to the subarachnoid space, penetrating the frontal bone. The subarachnoid lesion was composed of neutrophils indicating the presence of acute or subacute inflammation. The final diagnosis of the resected tumor was plasma cell granuloma. High levels of antibodies against Epstein-Barr (EB) virus in the cerebrospinal fluid and the immunohistochemical demonstration of EB nuclear antigens in the plasma cell granuloma suggested that EB virus infection was associated with the development of plasma cell granuloma in this patient.

Aged↗
PubMed1998

Clinical importance of c-Met protein expression in high grade astrocytic tumors.

The clinical importance of the expression of c-Met protein, the receptor of hepatocyte growth factor/scatter factor, was evaluated in neuroepithelial tissue tumors. c-Met immunohistochemistry was performed using the streptavidin-biotin-peroxidase complex method with anti-c-Met polyclonal antibody. Specimens were classified as c-Met negative (< 30%) or c-Met positive (> or = 30%) according to the proportion of immunopositive cells under microscopic examination. All c-Met-positive cases occurred in high grade astrocytic tumors, not in other neuroepithelial tissue tumors. Most c-Met-positive astrocytic tumors were classified histologically as high grade tumors. Epidermal growth factor-receptor (EGFR) and MIB-1 immunohistochemistry were also performed for high grade astrocytic tumors. Survival analysis was performed for patients with these tumors with variables including c-Met positivity, EGFR positivity, and MIB-1 labeling index. Positivity of c-Met was independent from EGFR positivity and MIB-1 labeling index, and the c-Met-positive group showed a significant shorter survival (p < 0.05). c-Met immunopositivity may be a parameter of biological aggressiveness in high grade astrocytic tumors. Examination of c-Met expression in astrocytic tumors provides significant clinical information, especially as a prognostic factor.

Astrocytoma↗
PubMed1998

[Is medical linac suitable for high-precision stereotactic irradiation?: investigations in geometrical accuracies of gantry and couch].

Linac-based radiosurgery has many advantages over the gamma knife, including low initial cost and no need of source replacement. On the other hand, most of the medical linacs currently in use were not originally designed to be applied for radiosurgery, and, therefore, careful quality assurance programs are required. In the gantry-head of a linac, a small CCD video camera is mounted in a position optically identical to that of the x-ray source. The video signal from the camera was digitalized to be evaluated for geometrical errors. A metal ball fixed to the stereotactic base frame via XYZ-sliding rods was used as a simulated target. Displacements of the target from the isocenter were measured during rotation of the gantry. Displacements in the gantry-rotation plane were satisfactorily small, while those perpendicular to it were maximal at gantry position angles of 0 degree and 180 degrees. This error night be caused by gravitational vending of the heavy gantry head. Although other major errors of the linac were within one millimeter, the center of coach rotation around the isocenter did not coincide with the center of gantry rotation, probably owing to gravitational vending. Special care should be taken when very small collimators are employed.

Quality Control↗
PubMed1998

[Analysis of abnormal findings observed on brain MRI T 2 weighted image in a system for the detection of asymptomatic brain disease in 1,200 cases].

In this study we described the significance of asymptomatic cerebral infarction (ACI) and periventricular hyperintensity (PVH) observed on brain MRI in a system for detection of asymptomatic brain disease with 1,200 cases. The risk factors (RF), population in each age bracket of ACI and PVH, among groups with hypertension (HTG) and without RF (no-RFG), were investigated. The RF of ACI were hypertension (HT), diabetes mellitus (DM), and aging. Without DM, those are common RF of PVH. The population of PVH and ACI with PVH increased with aging in no -RFG. On the other hand, only the population of ACI with PVH increased with aging in HTG. The rate of these abnormal findings in HTG was significantly higher than that in no-RFG. In addition, HT accelerated the occurrence of these findings by 10-20 years. When patients were over 60 years old, ACI increased rapidly. Accordingly, we concluded that (1) PVH and ACI had a common background. (2) Long term follow up concerning the incidence of ACI in the group with only PVH was necessary. (3) It was desirable that treatment for RF should be effected before the age of sixty.

Adolescent↗
PubMed1998

[FLAIR images of mild head trauma with transient amnesia].

A newly advanced MRI pulse sequence, the FLAIR (fluid-attenuated inversion recovery) imaging, in which a long TE spin echo sequence is used with suppression of the CSF with an inversion pulse, displays the CSF space as a no signal intensity area. We examined 45 cases of mild head trauma with posttraumatic amnesia by FLAIR images and could detect some findings which could not be detected by CT scan and conventional MR images. These findings could be detected in many patients with long post-traumatic amnesia (over 2 hours), but they could not be detected in patients with short posttraumatic amnesia (within 30 mins). These findings existed surrounding lateral ventricles and we classified them into 3 types: type 1 is anterior horn of lateral ventricle, type 2 is the base of frontal lobe, type 3 is cerebral deep white matter. Some of them were examined again by FLAIR images a month later, and these findings had disappeared. We suspect that these lesions were brain edema or mild contusion without hemorrhage.

Adolescent↗