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Biomedical subjects

A Kaneko

Publications and source records attributed to A Kaneko.

At least 127 records · Page 7Linked to original sources
PubMed1997

Fractionated stereotactic radiotherapy for choroidal melanoma.

Stereotactic radiotherapy used for the treatment of choroidal melanoma made use of a 6-MeV linac with built-in multileaf collimators and a simple plastic head mold. The latter provided excellent head and ocular immobilization. The system resulted in highly localized dose distributions with a maximum 2-mm targeting error during fractionated treatments. Based on these techniques, sixteen patients with choroidal melanoma have so far been treated. Majority of patients received a total dose of 48 Gy in 8 fractions. Fourteen patients who presented with small- to moderate-sized tumors have remained free of relapse or major complications during the follow-up period of 3-42 months. Two patients who presented with an extensive tumor eventually required enucleation after irradiation. Technical precision required for stereotactic radiotherapy and reproducibility for fractionation appear adequate. Encouraging preliminary results justify further studies to evaluate its efficacy as an alternative to other conventional therapeutic approaches.

Adult↗
PubMed1997

Appearance of a fast inactivating voltage-dependent K+ currents in developing cerebellar granule cells in vitro.

To elucidate the molecular mechanisms that regulate the maturation of action potential, we began by examining voltage-dependent K+ currents, known to contribute to the maturation of action potential, of developing granule cells in mouse cerebellar microexplant cultures. The migration of developing granule cells in this culture is reported to mimic the in vivo process, but their specific identification is still incomplete. In this study, we identified and characterized granule cells in this culture. Immunocytochemical analysis found that granule cells migrated radially out from explants and subsequently formed small clusters and also that their morphology changed from a bipolar to a T shape during migration. Moreover, in the electrophysiological study, the GABA response of granule cells in this culture clarified that the electrophysiological properties of granule cells were normally maintained. We therefore have concluded, that this culture system is a powerful tool for investigating the differentiation of cerebellar granule cells. Based on these findings, we recorded voltage-dependent K+ currents of developing granule cells in this culture, while concurrently observing their morphology. Our results show that voltage-dependent K+ currents of developing granule cells change from delayed rectifier to A current in parallel with their morphological changes from bipolar to T-shaped cells.

Animals↗
PubMed1997

Nonselective suppression of voltage-gated currents by odorants in the newt olfactory receptor cells.

Effects of odorants on voltage-gated ionic channels were investigated in isolated newt olfactory receptor cells by using the whole cell version of the patch-clamp technique. Under voltage clamp, membrane depolarization to voltages between -90 mV and +40 mV from a holding potential (Vh) of -100 mV generated time- and voltage-dependent current responses; a rapidly (< 15 ms) decaying initial inward current and a late outward current. When odorants (1 mM amyl acetate, 1 mM acetophenone, and 1 mM limonene) were applied to the recorded cell, the voltage-gated currents were significantly reduced. The dose-suppression relations of amyl acetate for individual current components (Na+ current: I(Na), T-type Ca2+ current: I(Ca), T, L-type Ca2+ current: I(Ca), L, delayed rectifier K+ current: I(KV) and Ca2(+)-activated K+ current: IK(Ca)) could be fitted by the Hill equation. Half-blocking concentrations for each current were 0.11 mM (INa), 0.15 mM (ICa,T), 0.14 mM (ICa,L), 1.7 mM (IKV), and 0.17 mM (IK(Ca)), and Hill coefficient was 1.4 (INa), 1.0 (ICa,T), 1.1 (ICa,L), 1.0 (IKV), and 1.1 (IK(Ca)), suggesting that the inward current is affected more strongly than the outward current. The activation curve of INa was not changed significantly by amyl acetate, while the inactivation curve was shifted to negative voltages; half-activation voltages were -53 mV at control, -66 mV at 0.01 mM, and -84 mV at 0.1 mM. These phenomena are similar to the suppressive effects of local anesthetics (lidocaine and benzocaine) on INa in various preparations, suggesting that both types of suppression are caused by the same mechanism. The nonselective blockage of ionic channels observed here is consistent with the previous notion that the suppression of the transduction current by odorants is due to the direst blockage of transduction channels.

Action Potentials↗
PubMed1997

Modulation of GABAC response by Ca2+ and other divalent cations in horizontal cells of the catfish retina.

GABAC responses were recorded in cultured cone-driven horizontal cells from the catfish retina using the patch clamp technique. At a holding potential of -49 mV, a bicuculline-resistant inward current (IGABA) was observed when 10 microM GABA was applied. The amplitude of IGABA increased as the extracellular Ca2+ ([Ca2+]o) was increased. Concentration-response curves of IGABA at 2.5 and 10 mM -Ca2+-o had similar EC50 (3.0 and 3.1 microM) and Hill coefficients (1.54 and 1. 24). However, the maximal response estimated at 10 mM [Ca2+]o was larger than the maximal response at 2.5 mM [Ca2+]o. Increasing Ca influx through voltage-gated Ca channels and the resulting rise in the intracellular Ca2+ concentration had no effects on IGABA. However, IGABA was inhibited by extracellular divalent cations, with the following order of the inhibitory potency: Zn2+ > Ni2+ > Cd2+ > Co2+. The inhibitory action of Zn2+ on the [Ca2+]o-dependent IGABA increase was noncompetitive. The action of [Ca2+]o on IGABA was mimicked by Ba2+ or Sr2+. These results demonstrate that the extracellular domain of GABAC receptors has two functionally distinct binding sites represented by Ca2+ (facilitation) and Zn2+ (inhibition). Since [Ca2+]o and [Zn2+]o change into the opposite direction by light, it seems likely that they modify cooperatively the efficacy of the positive feedback consisting of the GABAC receptor.

Animals↗
PubMed1997

[Effects of globulin preparations on phagocytic killing of oral streptococci].

The phagocytic bacterial activity on Streptococcus intermedius and Streptococcus oralis, clinical isolates from patients suffering from severe oral surgical infections, was evaluated by using sera and neutrophils of patients who had been treated with polyethylene glycal treated human normal immunoglobulin (Venoglobulin-IH). The phagocytic function of the neutrophils against the two strains, approximately 10 cells/neutrophil, was unrelated to the administration of Venoglobulin-IH. The bactericidal function of the serum and neutrophils on the third day following Venoglobulin-IH administration, on the other hand, rose to 10 times that of the sera and neutrophils of patients with mild infections. The agglutinin titer of Venoglobulin-IH against S. intermedius and S. oralis were 32 and 16 times, respectively, indicating an evident rise in these titers against the clinical isolates in comparison with the reference strains of the same organisms. These findings indicated that the oral streptococci that are isolated from patients with grave infections are associated with an antigenicity that is different from the normal bacterial flora; and these organisms are more labile to phagocytosis by neutrophils that were obtained from patients who have been treated with Venoglobulin-IH.

Administration, Oral↗
PubMed1997

Electrophysiological characterization of cultured hepatic stellate cells in rats.

This study aimed to examine electrophysiological properties of cultured rat hepatic stellate cells (HSCs) using the whole cell configuration of patch-clamp technique. At least three different current components were identified. First, when the membrane was depolarized to voltages more positive than -40 mV, a transient outward K+ current was evoked. Second, membrane hyperpolarization below -60 mV evoked a sustained and inward-rectifying K+ current. The third component was a current flowing outward, which was activated when the cell was depolarized more positively than 0 mV. The channel for this current allowed Na+, K+, and Cl- to pass nonspecifically, suggesting the presence of hemi gap-junctional channel. Furthermore, a laser photobleaching technique revealed the presence of gap junctions between adjacent HSCs. A voltage-gated Ca2+ current, which is known to occur in smooth muscle cells, was searched for but was not detectable. These results suggest that membrane potential of HSCs is determined specifically by the two distinct K+ channels and by an intercellular mechanism involving gap-junctional communication.

Animals↗
PubMed1997

Multiple hemorrhagic gastric ulcers due to polyarteritis nodosa.

A 73-year-old man developed refractory multiple hemorrhagic gastric ulcers. Emergent gastrectomy was performed, and the diagnosis of polyarteritis nodosa was made by histologic evaluation of the resected stomach. Although gastric ulceration is a relatively rare complication of polyarteritis nodosa, it should be considered in the differential diagnosis of refractory hemorrhagic gastric ulcers. Emergent surgery may be indicated in such cases.

Aged↗
PubMed1997

Quantitative analysis of Na+ and Ca2+ current contributions on spike initiation in the newt olfactory receptor cell.

The contribution of Na+ (INa) and T-type Ca2+ (ICa,T) currents on the action potential initiation in newt olfactory receptor cells (ORC) was investigated quantitatively. Since both the Na+ channel and T-type Ca2+ channel show rapid inactivation, it was questioned how much INa and ICa,T are activated during the gradually depolarizing initial phase of the receptor potential. Because the conventional voltage clamp technique does not allow direct current measurement during voltage changes, we estimated the amplitude of INa and ICa,T in an ionic current model. The model was constructed based on voltage clamp experiments. The estimated ratio of ICa,T/INa during the action potential induced by ramp current injection was 0.59 +/- 0.03 (mean +/- SD) under control Ringer's solution. This ratio was more than twice as large as that (0.25) obtained from the previous voltage clamp experiment using step commands. This result suggests that the T-type Ca2+ channel carries a more significant amount of current to generate the action potentials than expected previously.

Action Potentials↗
PubMed1997

Evaluation of combined therapy with chemoembolization and ethanol injection for advanced hepatocellular carcinoma.

To evaluate the therapeutic efficacy of transcatheter arterial chemoembolization (TACE) combined with percutaneous ethanol injection therapy (PEIT) for advanced hepatocellular carcinoma, we studied the effectiveness of TACE therapy combined with PEIT (50 cases) and TACE alone (50 cases). In both groups, patients had multiple lesions, or a single lesion with a diameter exceeding 2 cm or with vascular invasion (stages II, III, and IV in the tumor staging classification of the Liver Cancer Study Group of Japan). The clinical features in the two groups were comparable. The cumulative survival rates with TACE-PEIT were 95.0% for 1 year, 72.5% for 2 years, and 50.0% for 3 years, whereas the rates with TACE alone were 92.5% for 1 year, 57.5% for 2 years, and 20.0% for 3 years. The survival rate in the TACE-PEIT group was significantly higher than that in the TACE alone group. Moreover, the survival rate of patients with stage II or III disease in the TACE-PEIT group was significantly better than that in the TACE alone group, and the survival rate of patients with Child's classification B or C in the TACE-PEIT group was significantly higher than that in the TACE alone group. Multivariate analysis using Cox's proportional hazard regression model showed that the most significant prognostic factors in the TACE-PEIT group were tumor embolus in the portal vein and the number of tumors. These results suggest the effectiveness of combining TACE and PEIT for the treatment of advanced hepatocellular carcinoma.

Antibiotics, Antineoplastic↗
PubMed1997

Comparison of in vitro activity of azithromycin and ampicillin against 31 isolates of Streptococcus milleri.

Antibacterial action of azithromycin against 31 strains of dental infection-derived Streptococcus milleri and tissue transfer of the agent were compared with ampicillin, the drug of first choice for dental infections. Concentrations required to inhibit 50% of isolates(MIC50) and Concentrations required to kill 50% of isolates(MBC50) were 0.10 and 0.2 microgram/ml, respectively, for azithromycin. The antibacterial action of azithromycin was 4 times more potent in than ampicillin. The MBC90 for azithromycin was 0.39 microgram/ml, for amplicill 3.13 micrograms/ml. Bactericidally, azithromycin was 8 times more active than ampicillin. The peak value of concentrations (Cmax) of azithromycin was 0.45 microgram/ml, about 1/10 that of ampicillin. The half-life of azithromycin was 10 hours, about 5 times longer than that of ampicillin. The contact time of MIC90 concentrations for azithromycin was 12 hours, distinctly longer than the 8 hours calculated for ampicillin. Azithromycin showed excellent tissue transfer concentrations: the gingival transfer concentration following oral administration of 500 mg/day ranged from 0.7-23.5 micrograms/ml.

Administration, Oral↗
PubMed1996

Loss of heterozygosity on chromosome 17 and mutation of the p53 gene in retinoblastoma.

Loss of heterozygosity (LOH) on chromosome 17 and mutations of the p53 gene were examined in 25 retinoblastomas (RB), consisting of three familial tumors, nine hereditary tumors without family history, 11 non-hereditary tumors, one recurrent tumor and one lung-metastatic tumor. LOH on chromosome 17 was detected in only one of the 23 primary RB. No mutations of the p53 gene were detected in the primary tumors. A recurrent tumor showed LOH on the short arm region of chromosome 17. LOH on chromosome 17 and a point mutation of the p53 gene were also detected in a metastatic tumor. These results suggest that LOH on chromosome 17 and mutation of the p53 gene may not be associated with the development of primary RB, but may play a role in the progression of RB.

Blotting, Southern↗
PubMed1996

L-Glutamate-induced responses in OFF-type bipolar cells of the cat retina.

L-Glutamate (Glu)-induced current responses were studied in 119 isolated OFF-type bipolar cells of the cat retina. Cells were recorded by the patch clamp technique in the whole-cell configuration. Glu induced a current carried by alkali metal ions and divalent cations with a permeability ratio of PNa:PK:PCs:PCa = 1:0.94:1.32:0.57. Sensitivity to Glu was highest in the dendritic region. Kainate and AMPA worked as potent agonists, but neither APB, L-aspartate, ACPD, nor NMDA (all at 100 microM) was effective. The Glu-induced response was antagonized by > 1 microM CNQX. We inferred that OFF-type bipolar cells have a non-NMDA receptor channel that is permeable to alkali metal ions with low selectivity, but not NMDA receptor or metabotropic Glu receptor.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1996

A retrospective analysis of different modalities for treatment of primary orbital non-Hodgkin's lymphomas.

We have reviewed 37 patients with primary orbital lymphoma, using the Ann Arbor criteria and the Working Formulation and its modification. Thirty-one patients had stage I disease, four stage II, one stage III and one stage IV. The male to female ratio was 2.7:1. There were 34 low-grade tumours (including 24 mantle zone) and three intermediate-grade. Patients were divided into three groups according to their primary treatment. Group 1: radiotherapy (17 cases); Group 2: surgery alone (13 cases); Group 3: chemotherapy (seven cases). Patients were followed up from 5 months to 24.3 years, with a mean and median of 7.6 and 6.2 years, respectively. The BMDP software package was used for survival estimation (Kaplan-Meier) and determination of prognostic variable (univariate Cox regression). Local relapse-free survival at 10 years was 100% in Group 1, 0% in Group 2 and 42% in Group 3 with a statistically significant difference (p < 0.01) in favour of radiotherapy. Statistically significant good prognostic features were: complete remission (CR) in response to initial treatment, primary radiotherapy and older age. For stage I cases, there was no difference in distant relapse-free survival in the three groups. The overall cause-specific survival for stage I patients at 10 years was 100% for each group and at 20 years was 100, 67 and 0% for Groups 1, 2 and 3. The difference between the primary radiotherapy and chemotherapy-treated groups was significant at the p = 0.08 level. Statistically significant prognostic factors were early stage, low-grade histology and primary radiotherapy. In one patient, ptosis and diplopia appeared after surgery. One case of glaucoma required enucleation, one patient suffered severe dry eye syndrome. All patients (11/11) in whom the lens received direct radiation developed cataracts of different degrees if follow-up was long enough. Cataract formation was prevented by adequate lens shielding. One patient in CR from a stage I low-grade tumour died from chemotherapy-induced marrow aplasia. Primary orbital lymphoma is an indolent, usually stage I disease, showing low to intermediate-grade histology. After biopsy the best treatment is 30 (low-grade) to 40 Gy (intermediate-grade) carefully planned, lens-sparing megavoltage radiation without adjuvant chemotherapy.

Adult↗
PubMed1996

Monoclonal antibodies specific to the integral membrane protein P0 of bovine peripheral nerve myelin.

Two monoclonal antibodies (mAbs), 58A and 46E, were generated against the major protein P0 of bovine peripheral nervous system myelin (PNSM). The reactivities of the mAbs were assessed by enzyme-linked immunosorbent assay (ELISA), Western blot, and immunohistochemistry. Both mAbs, 58A and 46E, reacted to PNSM of bovine, human, rat and rabbit, but not to chicken PNSM or the brains of rat and rabbit. In the Western blot, these mAbs showed specific binding to bovine P0 as well as deglycosylated P0, but not to myelin-associated glycoprotein (MAG) of bovine spinal cord. The analyses of the lysylendopeptidase-digested peptides of bovine P0 revealed that the epitopes for the mAbs 58A and 46E were located on the amino acid residues 68-79 and 210-216, respectively. Since the mAbs 58A and 46E recognize the extracellular domain and the cytoplasmic domain of P0, respectively, they could be useful for studies on P0's role in myelin formation, its adhesive properties, and functions of the N-terminal extracellular and C-terminal cytoplasmic domains of the protein.

Amino Acid Sequence↗
PubMed1996

A quinine-activated cationic conductance in vertebrate taste receptor cells.

The chincona alkaloid quinine is known to be a bitter tasting substance for various vertebrates. We examined the effects of quinine on isolated taste receptor cells from the bullfrog (Rana catesbeiana). Membrane currents were recorded by whole-cell recording, while quinine hydrochloride was applied extracellularly from a puffer pipette. At the resting potential (-77 +/- 9 mV, mean +/- SD, n = 49 cells), taste cells generated inward currents in response to quinine stimulation (> 1 mM), indicating a depolarizing response in the taste cells. Two types of current responses were observed; a newly found quinine-activated cationic conductance and a previously reported blocking effect of quinine on K+ conductances. The cationic current was isolated from the K+ current by using a Cs(+)-containing patch pipette. The relative permeabilities (Pion) of the quinine-activated cationic conductance were: PNa/PK/PCs = 1:0.5:0.42. The quinine dose-response relation was described by the Hill equation with the K1/2 of 3.6 mM and Hill coefficient of 5.3. When extracellular [Ca2+] (1.8 mM) was reduced to nominally free, the conductance was enhanced by about sixfold. This property is consistent with observations on quinine responses recorded from the gustatory nerve, in vivo. The quinine-induced cationic current was decreased with an application of 8-bromo-cAMP. We conclude that the bitter substance quinine activates a cation channel in taste receptor cells and this channel plays an important role in bitter taste transduction.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

T-type Ca2+ channel lowers the threshold of spike generation in the newt olfactory receptor cell.

Mechanisms underlying action potential generation in the newt olfactory receptor cell were investigated by using the whole-cell version of the patch-clamp technique. Isolated olfactory cells had a resting membrane potential of -70 +/- 9 mV. Injection of a depolarizing current step triggered action potentials under current clamp condition. The amplitude of the action potential was reduced by lowering external Na+ concentration. After a complete removal of Na+, however, cells still showed action potentials which was abolished either by Ca2+ removal or by an application of Ca2+ channel blocker (Co2+ or Ni2+), indicating an involvement of Ca2+ current in spike generation of newt olfactory receptor cells. Under the voltage clamp condition, depolarization of the cell to -40 mV from the holding voltage of -100 mV induced a fast transient inward current, which consisted of Na+ (INa) and T-type Ca2+ (ICa.T) currents. The amplitude of ICa,T was about one fourth of that of INa. Depolarization to more positive voltages also induced L-type Ca2+ current (ICa,L). ICa,L was as small as a few pA in normal Ringer solution. The activating voltage of ICa,T was approximately 10 mV more negative than that of INa. Under current clamp, action potentials generated by a least effective depolarization was almost completely blocked by 0.1 mM Ni2+ (a specific T-type Ca2+ channel blocker) even in the presence of Na+. These results suggest that ICa,T contributes to action potential in the newt olfactory receptor cell and lowers the threshold of spike generation.

Action Potentials↗
PubMed1996

Direct measurement of eustachian tube compliance.

We developed a method by which tubal compliance can be directly measured, and using this method we examined tubal compliance in 18 adults with a disease-free ear and 8 adults with chronic otitis media. This method is advantageous in that one can directly measure tubal compliance in the cartilaginous part of the eustachian tube. It is our view that each eustachian tube has its own compliance which is not influenced by mucosal swelling or muscle tension around the tube.

Adult↗