Search PubMed⌕ Search

Biomedical subjects

E Kano

Publications and source records attributed to E Kano.

At least 19 recordsLinked to original sources
PubMed2001

Metabolism of phenylpropionic acid in enteropathogenic Escherichia coli belonging to serogroup O111 and its application for diagnosis.

We evaluated a biochemical assay based on the ability to metabolise beta-phenylpropionic acid (PPA) as a diagnostic aid in the identification of typical enteropathogenic Escherichia coli (EPEC) strains. A total of 1061 E. coli strains of serogroups O55, O111, and O119 were initially characterised regarding their H types (serotypes) and the presence of EPEC DNA sequences, eae, EAF, and bfpA. In case of the serogroup O111 strains, 84.6% carried the typical EPEC markers, and the great majority of those (98.1%) were PPA-positive. In contrast, only 0.9% of the serogroups O55 and O119 strains carrying the typical EPEC markers (53.6% and 75.4%, respectively) were PPA-positive. We conclude that the PPA test is a useful method to detect typical EPEC strains only among strains of the O111 serogroup.

Bacterial Proteins↗
PubMed2001

Acidic environment modifies heat- or radiation-induced apoptosis in human maxillary cancer cells.

PURPOSE: The effects of hyperthermia or irradiation on cell killing and induction of apoptosis were evaluated using human maxillary carcinoma IMC-3 cells and low pH (pH 6.8) adapted cells (IMC-3-pH). METHODS AND MATERIALS: Cellular heat-sensitivity or radiosensitivity was determined using the clonogenic assay. Apoptosis was assessed on the basis of a flow cytometric determination of the DNA content, DNA fragmentation, and poly(ADP-ribose)polymerase cleavage. RESULTS: When IMC-3 cells or IMC-3-pH cells were exposed to heat at 44 degrees C in pH 6.8 medium, an increase in thermosensitivity was observed compared with when the IMC-3 cells were exposed to heat at 44 degrees C in pH 7.4 medium. However, the selective reduction in survival was not observed after irradiation. In IMC-3 cells, apoptosis after heating at 44 degrees C for 60 min in pH 7.4 medium occurred earlier than that after 8 Gy irradiation, although both thermal and irradiated doses decreased the cell count to 10%. The degree of apoptosis after heating at pH 6.8 in IMC-3 cells or IMC-3-pH cells was greater than that at pH 7.4 in IMC-3 cells. However, the degree of apoptosis after 8 Gy irradiation at pH 6.8 in IMC-3 cells or IMC-3-pH cells was smaller than that at pH 7.4 in IMC-3 cells. CONCLUSION: Hyperthermia treatment is more effective at inducing apoptosis than radiation is in tumors that contain a population of low pH adapted cells.

Apoptosis↗
PubMed2001

Induction of radioresistance by a nitric oxide-mediated bystander effect.

To elucidate whether nitric oxide secreted from irradiated cells affects cellular radiosensitivity, we examined the accumulation of inducible nitric oxide synthase, TP53 and HSP72, the concentration of nitrite in the medium of cells after X irradiation, and cellular radiosensitivity using two human glioblastoma cell lines, A-172, which has a wild-type TP53 gene, and a transfectant of A-172 cells, A-172/mp53, bearing a mutated TP53 gene. Accumulation of inducible nitric oxide synthase was caused by X irradiation of the mutant TP53 cells but not of the wild-type TP53 cells. Accumulation of TP53 and HSP72 in the wild-type TP53 cells was observed by cocultivation with irradiated mutant TP53 cells, and the accumulation was abolished by the addition of an inhibitor for inducible nitric oxide synthase, aminoguanidine, to the medium. Likewise, accumulation of these proteins was observed in the wild-type TP53 cells after exposure to conditioned medium from irradiated mutant TP53 cells, and the accumulation was abolished by the addition of a specific nitric oxide scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, to the medium. The radiosensitivity of wild-type TP53 cells was reduced when the cells were cultured in conditioned medium from irradiated mutant TP53 cells compared to conventional fresh growth medium. Collectively, these findings indicate the potential importance of an intercellular signal transduction pathway initiated by nitric oxide in the cellular response to ionizing radiation.

Cell Line↗
PubMed2001

Enhancement of cell killing by induction of apoptosis after treatment with mild hyperthermia at 42 degrees C and cisplatin.

Ohtsubo, T., Igawa, H., Saito, T., Matsumoto, H., Park, H. J., Song, C. W., Kano, E. and Saito, H. Enhancement of Cell Killing by Induction of Apoptosis after Treatment with Mild Hyperthermia at 42 degrees C and Cisplatin. Radiat. Res. 156, 103-109 (2001). We examined the interactive effects of cisplatin (1.0 microg/ml) combined with hyperthermia on cell killing and on the induction of apoptosis in IMC-3 human maxillary carcinoma cells. The cytotoxic effects of hyperthermia on IMC-3 cells at 44 degrees C were greater than at 42 degrees C, as has been reported for many other cells. The induction of apoptosis, DNA fragmentation and poly(ADP-ribose) polymerase cleavage were greater after hyperthermia at 44 degrees C for 30 min compared with treatment at 42 degrees C for 105 min, even though both of these heat doses were isoeffective in reducing cell survival to 50%. Treatment with cisplatin at 37 degrees C for up to 120 min did not result in cytotoxicity or the induction of apoptosis. The enhancement ratio for treatment with cisplatin at 42 degrees C was greater than that at 44 degrees C. More apoptosis was induced after the treatment with cisplatin at 42 degrees C compared to treatment with cisplatin at 44 degrees C. Taking these findings together, the combination of cisplatin and hyperthermia at 42 degrees C appeared to be more effective than cisplatin with hyperthermia at 44 degrees C for the induction of apoptosis in IMC-3 cells.

Antineoplastic Agents↗
PubMed2001

Modification of thermosensitivity and chemosensitivity induced by combined treatments with hyperthermia and adriamycin.

Both adriamycin (ADM) and hyperthermia show thermal chemo-enhancement. Tolerance induction against ADM in heated cells has been reported resulting in clinical difficulty of cancer therapy. We investigated thermo-enhancement induced with ADM (0.2 microg/ml) treatment alone or combined with ADM and 42 degrees C hyperthermia in Chinese hamster V79 cells in vitro. Intracellular accumulation of hsc70 and hsp72 proteins after hyperthermia or ADM was observed to examine the possible relationship between cell killing effect and their accumulations. Thermosensitivity of V79 cells at 42 degrees C after the simultaneous treatments with ADM showed marked thermo-enhancement within the short-term treatments for less than 1 h, while the combined treatments for longer than 1 h, the cells showed reduced thermosensitivity. Survival from the simultaneous treatments for less than 1 h was reduced markedly less than the single treatment both with ADM or 42 degrees C hyperthermia alone. Thermotolerance was markedly induced in a step-up hyperthermia (42 degrees C 2 h-44 degrees C). The combined treatments with ADM and 44 degrees C hyperthermia following the 42 degrees C preheating alone does not inhibit thermotolerance development. The combined treatments with ADM and 42 degrees C preheating showed markedly interactive cell killing, but no thermo-enhancement to the following 44 degrees C hyperthermia was shown. The leveling slope of the 44 degrees C heating period-survival curve was drawn. In the Western blot analyses, hsc70 existed constitutively in the V79 cells. Following the 42 or 44 degrees C hyperthermia alone, intracellular accumulation of hsp72 was determined. ADM treatment alone did not induce any accumulation of hsp72. In the simultaneous treatments with ADM and hyperthermia, the accumulation of hsp72 was markedly reduced. The accumulation of hsp72 after the combined treatment with ADM and hyperthermia was not observed as markedly as that after hyperthermia alone.

Adaptation, Physiological↗
PubMed2000

Induction of radioresistance to accelerated carbon-ion beams in recipient cells by nitric oxide excreted from irradiated donor cells of human glioblastoma.

PURPOSE: To investigate whether nitric oxide excreted from cells irradiated with accelerated carbon-ion beams modulates cellular radiosensitivity against irradiation in human glioblastoma A-172 and T98G cells. MATERIALS AND METHODS: Western-blot analysis of inducible nitric oxide synthase, hsp72 and p53, the concentration assay of nitrite in medium and cell survival assay after irradiation with accelerated carbon-ion beams were performed. RESULTS: The accumulation of inducible nitric oxide synthase was caused by accelerated carbon-ion beam irradiation of T98G cells but not of A-172 cells. The accumulation of hsp72 and p53 was observed in A-172 cells after exposure to the conditioned medium of the T98G cells irradiated with accelerated carbon-ion beams, and the accumulation was abolished by the addition of an inhibitor for inducible nitric oxide synthase to the medium. The radiosensitivity of A-172 cells was reduced in the conditioned medium of the T98G cells irradiated with accelerated carbon-ion beams compared with conventional fresh growth medium, and the reduction of radiosensitivity was abolished by the addition of an inducible nitric oxide synthase inhibitor to the conditioned medium. CONCLUSIONS: Nitric oxide excreted from the irradiated donor cells with accelerated carbon-ion beams could modulate the radiosensitivity of recipient cells. These findings indicate the importance of an intercellular signal transduction pathway initiated by nitric oxide in the cellular response to accelerated heavy ions.

Blotting, Western↗
PubMed1999

Nitric oxide is an initiator of intercellular signal transduction for stress response after hyperthermia in mutant p53 cells of human glioblastoma.

Nitric oxide is known to be a multifunctional physiological substance. Recently, it was suggested that nitric oxide is involved in p53-dependent response to many kinds of stress, such as heat shock and changes in cellular metabolism. To verify this hypothesis, we examined the effect of nitric oxide produced endogenously by heat-shocked cells on nonstressed cells using a human glioblastoma cell line, A-172, and its mutant p53 (mp53) transfectant (A-172/mp53). The accumulation of inducible nitric oxide synthase was caused by heat treatment of the mtp53 cells but not of the wild-type p53 (wtp53) cells. The accumulation of heat shock protein 72 (hsp72) and p53 was observed in nontreated mtp53 cells cocultivated with heated mp53 cells, and the accumulation of these proteins was suppressed by the addition of a specific inducible nitric oxide synthase inhibitor, aminoguanidine, to the medium. Furthermore, the accumulation of these proteins was observed in the wtp53 cells after exposure to the conditioned medium by preculture of the heated mp53 cells, and the accumulation was completely blocked by the addition of a specific nitric oxide scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, to the medium. In addition, the accumulation of hsp72 and p53 in the wtp53 cells was induced by the administration of an nitric oxide-generating agent, S-nitroso-N-acetylpenicillamine, to the medium. Finally, the thermosensitivity of the wtp53 cells was reduced in the conditioned medium by preculture of the heated mp53 cells as compared with conventional fresh growth medium. Our finding of the accumulation of hsp72 and p53 in nitric oxide-recipient cells cocultivated with heated nitric oxide-donor cells provides the first evidence for an intercellular signal transduction pathway via nitric oxide as intermediate without cell-to-cell interactions such as gap junctions.

Benzoates↗
PubMed1999

Intercellular signaling initiated by nitric oxide produced in heat-shocked human glioblastoma cells.

The accumulation of inducible nitric oxide synthase was caused by heat shock of human glioblastoma T98G cells but not of A-172 cells. The accumulation of hsp72 and p53 was observed in A-172 cells cocultivated with heat-shocked T98G cells, which was suppressed by the addition of aminoguanidine to the medium. The accumulation of these proteins was observed in A-172 cells after exposure to the conditioned medium of heat-shocked T98G cells, which was completely blocked by the addition of 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide to the medium. In addition, the accumulation of these proteins in A-172 cells was induced by the administration of S-nitroso-N-acetylpenicillamine to the medium. Finally, the thermosensitivity of A-172 cells was reduced in the conditioned medium of heat-shocked T98G cells compared with conventional fresh growth medium. Our findings demonstrate that the accumulation of stress-induced proteins and thermoresistance in NO recipient cells cocultivated with heat-shocked NO donor cells is induced through an intercellular signal transduction pathway initiated by NO without cell-to-cell interactions such as gap junctions.

Brain Neoplasms↗
PubMed1999

Thermosensitivity, incidence of apoptosis and accumulations of hsp72 and p53 proteins of murine L cells in wild type status of p53 gene.

Murine L cells showed markedly high lethal thermosensitivity. Survivals from fractionated heating at 44 degrees C with variety of interval time at 37 degrees C (44 degrees C for 10 min--variety of interval time at 37 degrees C-44 degrees C for 10 min) increased markedly in accordance with elongation of the internal time; i.e. survival fraction of 0.9% from 44 degrees C for 20 min alone without the interval time to those of 25% from the fractionated heating with interval time at 37 degrees C for 3-10 hrs. Incidence of apoptosis of the L cells from heating at 44 degrees C for 6.5 min (LD50) increased from 7% immediately after the heating to 30% 6-12 hrs after the post-incubation time at 37 degrees C. Accumulation of both hsp72 and p53 proteins markedly increased after a heating at 44 degrees C for 10 min alone in accordance with elongation of post-incubation time at 37 degrees C, representing a peak 6 hrs after the post incubation. Status of p53 gene in L cells were determined with Reverse Transcription-Polymerase Chain Reaction-Single Strand Conformational Polymorphism (RT-PCR-SSCP), i.e. wild type.

Animals↗
PubMed1998

Suppression of heat-induced HSF activation by CDDP in human glioblastoma cells.

PURPOSE: The kinetics of the accumulation of inducible 72-kD heat shock protein (hsp72) and the activation of heat shock transcriptional factor (HSF) after hyperthermia and/or CDDP treatment in two human glioblastoma cell lines, A-172 having the wild-type p53 gene and T98G having the mutated p53 gene were evaluated. METHODS AND MATERIALS: Western blot analysis of hsp72, gel-mobility shift assay of HSF, cell survival, and development of thermotolerance were examined. RESULTS: The prominent suppression of heat-induced hsp72 accumulation by CDDP was seen in A-172 cells, but not in T98G cells. This was due to the p53-dependent inhibition of heat-induced HSF activation by CDDP. The interactive hyperthermic enhancement of CDDP cytotoxicity was observed in A-172 cells, but not in T98G cells. In addition, the heat-induced thermotolerance was suppressed by the presence of CDDP in the pretreatment. CONCLUSION: Suppression of heat-induced hsp72 accumulation by CDDP contributes to an interactive hyperthermic enhancement of CDDP cytotoxicity in the cells bearing the wild-type p53 gene.

Antineoplastic Agents↗
PubMed1998

Sensitization to hyperthermia by intracellular acidification of C6 glioma cells.

Hyperthermia has been introduced as a new modality of treatment for glioma. In these experiments, the cytotoxicity of hyperthermia in C6 glioma cells was enhanced by increasing the intracellular acidity with amiloride and/or 4,4'-diisothiocyanatostilbene-2,2' disulfonic acid (DIDS). Intracellular pH (pHi) is regulated mainly by Na+/H+ and HCO3-/Cl- antiports through the cell membrane, and amiloride acts on the former, DIDS on the latter to lower pHi. The cellular thermosensitivity to clinically achievable brain hyperthermia at 42 degrees C was enhanced by 0.5 mM amiloride (Na+/H+ antiport inhibitor). T0 values (T0 = the heating period required to reduce experimental survival rate by 1/e) at 42 degrees C without and with amiloride was 192 and 81 min, respectively. The addition of DIDS (HCO3-/Cl- antiport inhibitor) further enhanced. T0 value was 25 min. Fluorophotometric measurement of pHi was employed using the pH sensitive dye, bis(carboxyethyl)carboxyfluorescein, which is trapped in viable cells. The average pHi in control C6 glioma cells in pH 7.2 media was 7.21. In the untreated cells heated at 42 degrees C for 1 hour, the pHi was 7.12. The pHi of the cells heated in the presence of amiloride was decreased to 6.83. The pHi was further lowered to 6.67 by the treatment with amiloride in combination with DIDS for 2 hours. Hyperthermia with amiloride and DIDS may be a more effective treatment for malignant gliomas.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Suppression of heat-induced p53 accumulation and activation by CDDP or x-rays in human glioblastoma cells.

We showed that the prominent suppressions of heat-induced accumulation and activation of p53 by CDDP or X-rays were observed in A-172 cells, but not in T98G cells. In addition, the interactive hyperthermic enhancement of CDDP or X-ray cytotoxicity was observed in A-172 cells, but not in T98G cells. Our findings indicate that suppressions of heat-induced accumulation and activation of p53 by CDDP or X-rays contribute positively to an interactive hyperthermic enhancement of CDDP- or X-ray cytotoxicity.

Antineoplastic Agents↗
PubMed1997

The effects of combined treatments with low hyperthermia and bleomycin on survivals of murine L cells.

Modification effects of low hyperthermia (40 degrees C) on cellular chemosensitivity to bleomycin (BLM), and of BLM on thermosensitivity (40 degrees C) were investigated in cultured murine L cells with simultaneous or sequential treatments of these two agents. The heating of L cells at 40 degrees C up to 6 hours resulted in no remarkable lethal damage. Treatment with low hyperthermia followed by BLM for 4 hours showed no more than additive effect. However, a significant chemical (BLM) enhancement effect on the cellular thermosensitivity was observed by the treatment with BLM for 4 hours prior to the low hyperthermia at 40 degrees C. No appreciable thermal enhancement effect on the cellular chemosensitivity to BLM was shown by preheating at 40 degrees C for 3 hours, while post-heating at 40 degrees C showed a significant thermal enhancement effect as well as in the simultaneous treatments. The cell phase response to BLM was levelled in the clinical range of the doses. It is possible that the repair of sublethal damage (SLDR) from treatment with BLM was inhibited by 40 degrees C post-heating and this SLDR was completed at 3 hours of the interval at 37 degrees C between BLM and 40 degrees C heating.

Animals↗
PubMed1996

Suppression of heat-induced hsp72 accumulation by cisplatin in human glioblastoma cells.

The accumulation of the inducible hsp72 (72-kDa heat shock protein) after hyperthermia and/or cisplatin treatment in human glioblastoma cell line (A-172) was studied by Western blot analysis. The level of hsp72 increased to eight-fold 10 h after hyperthermia alone (44 degrees C for 20 min, D50) and to three-fold 10 h after cisplatin treatment (5 microg/ml) at 37 degrees C for 15 min (D50). In contrast, when the cells were simultaneously heated with cisplatin, the accumulation of hsp72 was suppressed. The level of hsp72 increased to about six-fold and two-fold 10 h after hyperthermia (44 degrees C, 15 min) in the presence of 1 and 10 microg/ml (D50 or D10) of cisplatin, respectively. In addition, we found both the enhancement of thermosensitivity and the suppression of thermotolerance by the simultaneously combined treatment of hyperthermia and cisplatin. It has been reported that the enhancement of cisplatin cytotoxicity by hyperthermia is due to increase of both cisplatin uptake and DNA damage by hyperthermia. Our results suggest that the interactive cytotoxic enhancement by the combination of hyperthermia and cisplatin may be also due to the suppression of heat-induced hsp72 accumulation by cisplatin.

Antineoplastic Agents↗
PubMed1996

Application of the ATP-bioluminescence assay to thermosensitivity testing for head and neck cancer.

We investigated the usefulness of the ATP assay as a thermosensitivity test in comparison with a colony-forming assay (CFA). The intracellular ATP levels in KB cells were markedly decreased after exposure to hyperthermia (43 degrees C for 1 h), reaching less than half that in the control cells in 12-18 h, and recovering gradually thereafter. The effect of hyperthermia assessed by the ATP assay closely correlated to that assessed by CFA, not only when KB cells were heated at 42, 43, and 44 degrees C but also in the conditions where L, KB and IMC-3 cell lines were heated at 43 degrees C. Findings showed that the ATP assay can be performed easily and more quickly than CFA for evaluating cell viability after heating. We also investigated heterogeneous responses to hyperthermia in cells from fresh surgical specimens of tumors. Thus, this rapid and reliable test was found to be useful for predicting the outcome of hyperthermia as a clinical treatment.

Adenosine Triphosphate↗
PubMed1996

Effects of sequence and temperature of hyperthermia and peplomycin on human pharyngeal carcinoma KB cells in vitro.

To maximize the interactive effect, we examined the time sequence of high (above 43 degrees C) or low (below 43 degrees C)-hyperthermia and peplomycin (PEP)(0.5 microgram/ml). Simultaneous or post-hyperthermic PEP treatment at 44 degrees C resulted in a slight synergistic effect with thermoenhancement ratios (TER) of 1.30 or 1.34, respectively. However, at 42 degrees C, maximal interaction was obtained (TER = 10.19) when KB cells were simultaneously heated with PEP. Furthermore, pre-treatment at 44 degrees C for 25 min or 42 degrees C for 4 h enhanced PEP cytotoxicity more than that of post-treatment at 44 degrees C for 25 min or 42 degrees C for 4 h, respectively. However, chemoenhancement ratios (CER) of pre-treatment at 44 degrees C for 25 min and at 42 degrees C for 4 h were 19.1 and 3.5, respectively, although the isothermic dose decreased the cell count to 60% in both cases. These results indicated that simultaneous or post-hyperthermic PEP treatment with high-hyperthermia, and simultaneous PEP treatment with low-hyperthermia, are the most effective means of PEP thermochemotherapy with hyperthermia.

Cell Survival↗
PubMed1995

Thermosensitization of murine FM3A cells by transient incubation at low culture temperatures.

We show that when murine FM3A cells maintained at 37 degrees C were incubated at low culture temperatures between 24 degrees and 33 degrees C for 12-24 h, they became thermosensitive as compared to those incubated at 37 degrees C. The synthesis and accumulation of inducible HSP70 and constitutive HSC70 by heat shock decreased in cells incubated at 33 degrees C, whereas no such decreases were found in cells incubated at 37 degrees C. The accumulation of HSP105 because of heat shock also decreased in cells incubated at 33 degrees C. The decreased inducibility of HSP70, HSC70, and HSP105 by heat shock may in part be responsible for the increase seen in the thermosensitivity of the cells. Furthermore, the cellular concentration of HSP105 decreased in cells incubated at 33 degrees C but not in those incubated at 37 degrees C, whereas the concentration of HSC70 did not change at all in cells incubated at either temperature. The cellular content of HSP105, but not of HSC70, therefore may be a good indicator of the thermoresistant state of cells.

Animals↗