Biomedical subjects

M Urano

Publications and source records attributed to M Urano.

176 records · Page 10Linked to original sources

PubMedDate not supplied

The effect of cis-diamminedichloroplatinum(II) treatment at elevated temperatures on murine fibrosarcoma, FSa-II.

The effect of cis-diamminedichloroplatinum(II) (cis-DDP) on the murine fibrosarcoma cells was investigated in vitro and in vivo. For in vitro experiments tumour cell suspensions containing a given amount of cis-DDP were treated in water bath maintained at a desired temperature, and cell survival was determined by the lung colony assay. The D0 or the time to reduce survival from 1.0 to 0.37 on the exponential portion of the survival curve was determined and 1/D0 was plotted as a function of 1/T, where T stands for the absolute temperature. The slope of this Arrhenius plot indicated that the activation energy for chemical reaction of cis-DDP was 44 kcal/M between the temperature range from 37 to 41 degrees C. For in vivo experiments tumours were transplanted into the foot and treated by immersing the animal foot into a water bath when each tumour reached an average diameter of 4 mm (35 mm3). The drug was injected i.p. immediately before hyperthermia. The tumour growth (TG) time or the time required for a tumour to reach 1000 mm3 from the treatment day was determined, and the median TG time was obtained by logit analysis. Dose-response curves between the TG time and drug dose indicated that the cytotoxic effect of cis-DDP was enhanced at elevated temperatures. This enhancement increased with increasing temperature from room temperature to 43.5 degrees C. Because of short plasma half-time of cis-DDP, continuous infusion and pulse injections were attempted.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

The cytotoxic effect of cis-diamminedichloroplatinum(II) on cultured Chinese hamster ovary cells at elevated temperatures: Arrhenius plot analysis.

The effect of cis-diamminedichroloplatinum (II) (cis-DDP) and hyperthermia on cultured Chinese hamster ovary (CHO) cells were investigated. Cells were treated with 6 microM cis-DDP for various durations of time at temperatures ranging from 37 to 43 degrees C, and cell survival curves were determined as a function of treatment time. The cytotoxic effect of cis-DDP increased with increasing temperatures, indicating that hyperthermia enhanced cytotoxicity of cis-DDP. Arrhenius analysis of surviving fraction data (6 microM cis-DDP) yielded activation energies of 61 kcal/M between 37 and 41 degrees C and 213 kcal/M between 41 and 43 degrees C. Further experiments using two different drug concentrations (3 and 12 microM) confirmed these activation energies in these two different temperature ranges. However, the activation energy for 12 microM cis-DDP given in the temperature range 33-37 degrees C was 22 kcal/M, which is smaller than those found above 37 degrees C. This activation energy appeared to be identical to that reported for the degradation or depurination of DNA. The activation energy between 37 and 41 degrees C, i.e. approximately 61 kcal/M, was twice as great as that found for alkylation of thio-TEPA, an alkylating agent. This may indicate that the mechanism of action of cis-DDP differs from that of thio-TEPA. A greater activation energy observed in the range of 41-43 degrees C is most likely attributable to the additive effect of hyperthermia and thermal enhancement for cis-DDP. Although only one data point is available at the temperature above 43 degrees C, it suggests that the activation energy is identical to that for hyperthermia alone.

Animals↗

PubMedDate not supplied

Enhancement of the thermal response of murine tumour and normal tissues by a streptococcal preparation, OK-432 (Picibanil).

We have studied the effect of a streptococcal preparation, OK-432, given alone or in combination with hyperthermia on murine tumour and normal tissues. The experimental tumour was a spontaneous non-immunogenic fibrosarcoma FSa-II transplanted in the foot of C3Hf/Sed mice. Local hyperthermia was achieved by immersing the mouse foot into a constant temperature water bath (42-45 degrees C) for various lengths of time. Tumour response was studied by analysing the tumour growth (TG) time. Various doses of OK-432 (1-5 KE/mouse) were injected locally into the tumour. Local administration of OK-432 alone (without hyperthermia) had no effect on the TG time. Thermal enhancement ratio (TER) for combined treatment was independent of drug dose greater than or equal to 2 KE, and the mean TER was 1.48 +/- 0.27 (95% CL). The TER was greater for 6 mm tumours than for 4 mm tumours, and it was greatest if the time interval between hyperthermia and drug administration was 3 h or less. There was no effect if the drug was administrated 4 days before hyperthermia, but its application 9 days prior to hyperthermia caused a slight prolongation of the TG time of non-heated tumours, and a reduction in the TG time of heated tumours. Normal-tissue response was studied by scoring the peak foot reaction and RD50 (the treatment time to induce a specified response in one-half of the treated animals). The effect of OK-432 on the thermal response of the foot was also studied at various temperatures. The mean TER was 1.11 +/- 0.07. Local administration of OK-432 failed to modify significantly the kinetics of thermotolerance. Present experiments demonstrated that OK-432 after local administration enhanced the thermal response of murine tumour and normal tissues. This enhancement was greater for the tumour than for the normal tissue, resulting in a favourable differential effect between normal and malignant tissues (the average therapeutic gain was 1.33 +/- 0.19).

Animals↗

PubMedDate not supplied

Cytotoxic effect of 1,3 bis (2-chloroethyl)-N-nitrosourea at elevated temperatures: Arrhenius plot analysis and tumour response.

The effect of hyperthermia on the cytotoxicity of 1,3-bis-(2-chloroethyl)-N-nitrosourea (BCNU) was investigated in vitro and in vivo. Tumour cells were early-generation isotransplants of a spontaneous C3Hf/Sed mouse fibrosarcoma, FSa-II. For in vitro studies, single cell suspensions containing 1.0 x 10(6) cells/ml were treated in a water bath where a desired temperature was maintained by a constant-temperature circulator. Cell survival was determined by lung colony assay immediately thereafter. For in vivo studies the tumour cell suspensions were transplanted into the dorsal site of the C3Hf/Sed mouse foot. Tumours were treated by immersing animal feet into a constant-temperature water bath when tumours reached an average diameter of 4 mm (35 mm3). The tumour growth (TG) time or the time for one-half of the treated tumours to reach 1000 mm3 from initial treatment day was used as an endpoint. BCNU dose-cell survival curve at 37 degrees C was exponential with a D0 of 1.1 microgram/ml. Dose-cell survival curves at 37-43 degrees C were determined as a function of treatment time at pH 6.7 and 7.4. BCNU of 1 microgram/ml was added immediately before treatment. The slope of the survival curve became steeper with increasing temperature, indicating that the cytotoxic effect of BCNU was enhanced by hyperthermia. The Arrhenius plot analysis showed that activation energies at pH 6.7 and 7.4 were 53 and 51 kcal/M, respectively (no significant difference). Of interest in this analysis was that the Arrhenius plot did not show a breaking point which has been observed for other agents. Further investigation demonstrated that the decomposition of BCNU, which has been reported to be essential for production of reactive intermediates, occurred in aqueous medium at elevated temperatures. The magnitude of this decomposition depended on treatment temperature. As a result, preheated BCNU became less cytotoxic with an increase in preheating temperatures. The activation energy for this decomposition was about one-half of the activation energy for BCNU cytotoxicity. Studies in vivo indicated that the effect of BCNU was enhanced with increasing temperatures, and the enhancement was greatest when BCNU was administered i.p. immediately before hyperthermia. A glucose dose of 5 g/kg administered i.p. 60 min before hyperthermia further enhanced the antitumour effect of BCNU.

Animals↗

PubMedDate not supplied

Augmentation of mouse natural killer cell activity by combined hyperthermia and streptococcal preparation, OK-432 (Picibanil) treatment.

It has previously been demonstrated that the local administration of OK-432 (Picibanil) enhances the response of a murine tumour and normal tissue to elevated temperatures. The experimental animals were C3Hf/Sed mice and the tumours were the fourth generation isotransplants of a spontaneous non-immunogenic fibrosarcoma, FSa-II. The thermal enhancement ratio was greater for the tumour than for normal tissue, resulting in a favourable differential effect between normal and malignant tissues. Further studies were conducted to disclose the mechanism of OK-432 induced thermal enhancement. Although OK-432 showed a slight direct cytotoxic activity against tumour cells in vitro, the in vivo antitumour effect of combined OK-432 and hyperthermia treatments was greater than the effect expected from in vitro cytotoxicity, indicating the involvement of the host-mediated mechanisms. Whole body irradiation (WBI), which suppressed the host's immune reaction, did not affect the thermal enhancement mediated by OK-432, suggesting that radiosensitive cells (sensitive to WBI) were not involved in this process. As expected, the i.v. injections of the anti-mouse T-cell serum did not have any effect on the thermal enhancement of OK-432. The administration of blockers of the reticuloendothelium system, i.e. silica or trypan blue, did not inhibit the OK-432 induced thermal enhancement. Moreover, local intratumoural injections of normal or OK-432 induced macrophages showed no effect on tumour growth. The thermal enhancement by OK-432 was eliminated following treatments with anti-(asialo GM1) globulin. Despite the fact that the cytotoxic effect of anti-(asialo GM1) globulin was not selective to natural killer (NK) cells, all the experimental results indicated that NK cells were probably attributable to thermal enhancement by OK-432 in vivo. The NK cell activity was stimulated when the OK-432 was locally administered with hyperthermia.

Animals↗

PubMedDate not supplied

Effect of thermoimmunotherapy with OK-432 on the development of spontaneous lung metastases in mice.

The effect of combined hyperthermia and intratumoral administration of OK-432 (Picibanil) on the development of spontaneous lung metastases was studied. The spontaneous non-immunogenic fibrosarcoma, FSa-II, transplanted into the right foot of C3Hf/Sed mice, was used throughout. Hyperthermia was given locally by immersing the animal foot in a water bath set at 44.0 degrees C for 30 min. OK-432 in the dose of 2.5 KE was injected into the tumour 3 h before hyperthermia. This treatment has been shown to strongly inhibit local tumour growth. Sham hyperthermia, i.e. restraining the mice in holders, as well as local injection of saline solution, increased metastases incidence. The high incidence of metastases following combined sham hyperthermia and saline injection was substantially reduced by intratumoral administration of OK-432 given alone or combined with hyperthermia.

Animals↗

PubMedDate not supplied

Interaction between the kinetics of thermotolerance and effect of cis-diamminedichloroplatinum(II) or bleomycin given at 37 or 43 degrees C.

The interaction between the cytotoxic effect of bleomycin (BLM) or cis-diamminedichloroplatinum(II) (cis-DDP) and the kinetics of thermotolerance was studied in cultured Chinese hamster ovary (CHO) cells. Pre-heated cells were treated with cis-DDP or BLM at 37 or 43 degrees C for various times after heating. Pre-heating enhanced cis-DDP cytotoxicity given immediately after heating, but this enhancement decreased within 24 h to an additive level. Cell survival following the initial heating and the second treatment of 'cis-DDP at 43 degrees C was minimal when cis-DDP at 43 degrees C was given immediately after the initial heating, but became higher with increasing treatment interval and reached 'less than additive' level when the treatment interval was extended to more than 24 h. This alteration in cell survival appeared to follow the kinetics of thermotolerance. The interaction between BLM treatment and the kinetics of thermotolerance was similar to that of cis-DDP. However, pre-heating enhanced BLM cytotoxicity much less extensively than cis-DDP cytotoxicity. These results indicate that: (a) pre-heating of cells enhanced drug-toxicity when the drug was given shortly after heating, but the magnitude of this enhancement depended on the drug; (b) pre-heating did not influence the cytotoxicity of drugs given at 37 degrees C; and (c) pre-heating decreased the magnitude of thermal sensitization of drug cytotoxicity. The magnitude of the decrease in thermal sensitization appeared to be parallel to the kinetics of thermotolerance. In this study it was also demonstrated that pre-treatment of CHO cells by cis-DDP or BLM did not alter sensitivity to subsequent drug treatment, hyperthermia or thermochemotherapy.

Animals↗

PubMedDate not supplied

Comparative study of thermoradiosensitization by misonidazole and metronidazole in vivo: antitumour effect and pharmacokinetics.

Tumour control by local hyperthermia (43.5 degrees C, 30 min) and radiation (20 Gy) given in combination with misonidazole (MISO) or metronidazole (METRO) was studied using FSa-II murine fibrosarcoma. When MISO or METRO (5 mmol/kg) was given 30 min before heat and subsequently treated with radiation, tumour regression was observed for both agents. Radiation dose-response curves for MISO and METRO with heating at 43.5 degrees C for 30 min were identical. Mouse foot reaction was used to evaluate local toxicity following combined heat, a nitroimidazole and radiation treatment. MISO enhanced the magnitude of foot reaction and prolonged the recovery time compared with heat plus radiation controls. There were no observable differences of foot reaction between animals treated with heat plus radiation and those animals treated with heat, radiation and METRO. Pharmacokinetics of the nitroimidazoles heated at 43.5 degrees C for 30 min in FSa-II tumours were investigated as a possible mechanism of thermal sensitization. Local hyperthermia did not alter the pharmacokinetics of METRO. Tumour concentration and tumour/plasma ratio of MISO were slightly decreased during heating. Since the hypoxic metabolism of the nitroimidazoles did not increase significantly during the heat treatment, the thermal enhancement of MISO or METRO radiosensitization cannot be explained by the increase in hypoxic cytotoxicity of the nitroimidazoles at elevated temperature alone. The two nitroimidazoles also were not accumulated in the tumour after heating. Therefore, alternation of pharmacokinetics is not the major mechanism for the thermal enhancement of nitroimidazole radiosensitization. The METRO radiosensitization effect became identical to that of MISO at elevated temperatures is of particular importance in clinical radiosensitization. The very low local and systemic toxicity together with the high efficacy of METRO at elevated temperatures will make it an attractive candidate as a future clinical radiosensitizer.

Animals↗

PubMedDate not supplied

Synergism between alkylating agent and cis-platin with moderate local hyperthermia: the effect of multidrug chemotherapy in an animal system.

The combined effect of multidrug chemotherapy given in combination with hyperthermia was investigated using early-generation isotransplants of a spontaneous fibrosarcoma, FSa-II in C3Hf/Sed mice. Combinations of various types of chemotherapeutic agents, including alkylating agents, cyclophosphamide (CY) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU); antibiotics, bleomycin (BLM) and mitomycin C (MMC); an antimetabolite, 5-fluorouracil (5FU); and a platinum complex, cis-diamminedichloroplatinum(II) (cDDP), were examined using the tumour growth (TG) time assay. Simultaneously, the effect of glucose on the response to thermochemotherapy was investigated. Graded doses of the multidrugs were given i.p. immediately before hyperthermia with or without a glucose dose of 5 g/kg given i.p. 60 min before hyperthermia. Hyperthermia was given by immersing the tumour-bearing murine feet into a water bath set at 41.5 +/- 0.05 degrees C for 60 min. Dose-response curves were obtained between the TG time and drug dose. The thermal enhancement ratio (TER) was expressed as a ratio of the slope of the dose-response curve obtained at 41.5 degrees C to that obtained at room temperature. To evaluate normal tissue damage, the number of white blood cells (WBC) was counted from a day before treatment to the 21st day after treatment. A substantial thermal enhancement of the anti-tumour effect was observed in all five multidrug regimens tested. Glucose administered prior to thermochemotherapy further enhanced the antitumour effect. The TER was largest for the combination of CY+cDDP (TER was 5 without glucose). The second largest TER was obtained for a combination of CY+cDDP+MMC (TER was 4.1 without glucose and 6.5 with glucose). The antitumour effects of these two combinations were synergistic at a test elevated temperature only. No synergistic effect was found at room temperature for any of the drug combinations tested. The smaller TERs were observed in the treatment regimens that included 5FU. In general, a decrease in the number of WBC following multidrug chemotherapy was slightly less than that following the individual drugs.

Alkylating Agents↗

PubMedDate not supplied

Interaction between adriamycin cytotoxicity and hyperthermia: growth-phase-dependent thermal sensitization.

Thermal sensitization of adriamycin cytotoxicity was studied in vitro and in vivo using tumour cells originated from a spontaneous mouse fibrosarcoma, FSa-II. The adriamycin dose-cell survival curve for exponentially growing cells was biphasic with the initial sensitive portion followed by a resistant tail. The survival curves determined in vitro as a function of treatment time at various temperatures were also biphasic. With increasing temperatures the initial portion became steeper and the resistant fraction decreased. At a temperature of 43 degrees C, which gives lethal damage to cells by itself, the cell survival decreased rapidly during the initial 30 min of treatment and became relatively constant for subsequent treatment times up to 180 min. The tumour response determined by the median tumour growth time for one-half of treated tumours to reach 1000 mm3 from the treatment day (35 mm3) indicated that the tumour response to adriamycin was independent of temperature. Hyperthermia at 43.5 degrees C for 60 min prolonged the tumour growth time without showing chemosensitization. The maximum drug dose used was 12 mg/kg that is < LD10 or the drug dose that kills animals with < 10% probability. The dose-response curves (tumour growth versus drug dose) showed identical slopes at room temperature, 41.5 and 43.5 degrees C. Further studies were conducted in vitro. Plateau phase cells were treated with graded adriamycin doses for 60 min at 37 degrees C, or with a constant adriamycin dose of 0.25 microgram/ml for various times at 37 or 43 degrees C. The dose-cell survival curves for both exponential and plateau phase cells were biphasic, but the plateau phase cells were more resistant to adriamycin at 37 degrees C than the exponential phase cells. The survival curve for plateau phase cells, determined as a function of treatment time, showed an initial shoulder followed by an exponential portion. Compared with the heat survival curve at 43 degrees C, the survival curve for the drug treatment at 43 degrees C was identical to that for the heat alone treatment for the first 60 min and then became steeper than the heat alone survival curve. These results suggest that adriamycin cytotoxicity may be enhanced at elevated temperatures only when tumours are treated for a prolonged time or possibly with a large drug dose.

Animals↗

PubMedDate not supplied

The advantageous use of hypoxic tumour cells in cancer therapy: identical chemosensitization by metronidazole and misonidazole at moderately elevated temperatures.

Chemosensitization by two nitroimidazoles (NIs), metronidazole (METRO) and misonidazole (MISO), of the anti-tumour effect of alkylating agents was studied at three different temperatures: room temperature (RT), 37 and 41.5 degrees C. Three alkylating agents, cyclophosphamide (CY), 1,3 bis(2-chloroethyl)-N-nitrosourea (BCNU) and melphalan (L-PAM) were tested when the tumours reached an average diameter of 4 mm. Tumours were 4th generation isotransplants of a spontaneous fibrosarcoma, FSa-II. Treatment at 37 or 41.5 degrees C was given by immersing the tumour-bearing foot for 60 min in a water bath set at these temperatures. The test agents were injected ip immediately before immersing the foot in the water bath, whereas METRO or MISO (2.5 mmol/kg) was given ip 30 min before the injection of a test agent. Following treatment the tumour growth (TG) time, i.e. the time required for one-half of treated tumours to reach 1000 mm3 after the treatment day, was studied. For CY, MISO was a better sensitizer than METRO at RT and 37 degrees C, but the magnitude of the chemosensitization by MISO and METRO became identical at 41.5 degrees C. Notably, the chemosensitization was substantially enhanced at 41.5 degrees C, whereas neither 41.5 degrees C-heat, NIs or combined NI and heat prolonged the TG time. Although no chemosensitization was observed for BCNU at RT, both METRO and MISO equally enhanced the effect of BCNU at 41.5 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Thermal enhancement of the effect of ifosfamide against a spontaneous murine fibrosarcoma, FSa-II.

The effect of hyperthermia on the cytotoxicity of 3-(2-chloroethyl)-2-[(2-chloroethyl)amino]-tetrahydro-2H-,1,3, 2-oxazaphosphorine-2-oxide, ifosfamide (IFO) was investigated in vivo. Tumours were early generation isotransplants of a spontaneous C3Hf/Sed mouse fibrosarcoma, FSa-II. The tumour cell suspensions containing approximately 2 x 10(5) cells were transplanted into the dorsal site of the C3Hf/Sed mouse foot. Hyperthermia was given by immersing the tumour-bearing foot into a constant temperature water bath set at 41.5 degrees C for 0-90 min when tumours reached 34 mm3. IFO was administered i.p. immediately before hyperthermia. Tumour response was studied by the tumour growth (TG) time assay; namely, the TG time or the time for one-half of the treated tumours to reach 700 mm3 from the initial treatment day was determined and the dose-response curves was fitted between the TG time and IFO dose. The anti-tumour effect of IFO was enhanced at this elevated temperature. The thermal enhancement ratio (TER) or the ratio of the slope of dose-response curve at 41.5 degrees C to that of dose-response curve without hyperthermia was relatively small for a short treatment time of 30 min. This TER was smaller for IFO than the TERs for cyclophosphamide (CY) and BCNU which had been studied in our laboratory. However, the TER for IFO increased greatly with a prolongation of treatment time from 30 to 90 min, and exceeded the TER for CY. The TERs were 1.5, 2.6 and 3.6 for heating time of 30, 60, and 90 min, respectively, indicating that a long treatment time such as 90 min at moderately elevated temperatures could result in a substantial enhancement of the antitumour effect of IFO.

Animals↗

PubMedDate not supplied

Overexpression of manganese superoxide dismutase gene suppresses spontaneous apoptosis without a resultant alteration in in vivo growth of the mouse fibrosarcoma, FSa-II.

The relationship between spontaneous apoptosis and overexpression of manganese superoxide dismutase (MnSOD) gene was examined in vivo. The mouse fibrosarcoma cells expressing high MnSOD activities due to transfection with the human MnSOD cDNA (SOD-H), or the fibrosarcoma cells transfected with the selectable marker alone (NEO), were transplanted into immune-deficient Fox Chase SCID C.B-17/Icr-scid Jcl mice. Apoptosis in tumors was visually quantified by the in situ end-labeling method. The number of apoptotic cells in the SOD-H tumors was significantly less than that in the NEO tumors. The tumor growth time of the SOD-H tumors to grow from 34 to 500 mm3 in one-half of the mice was slightly longer than that of the NEO tumors, but the difference was not statistically significant. These results suggest that overexpression of MnSOD gene is involved in the suppression of spontaneous apoptosis, without a resultant alteration in the tumor growth.

Animals↗

PubMedDate not supplied

Adherence of plaque components to different restorative materials.

This study compared the amount of artificial plaque synthesized in vitro by Streptococcus sobrinus on various dental materials using radioisotopes. In particular, plaque-retaining capacities of new types of ceramics were the focus of this study. Specimens were fabricated from the following materials (one amalgam alloy [Spherical-D], one casting gold alloy [Casting Gold TYPE I], one resin composite [Herculite XR] and three ceramics [Vita Celay Blanks, IPS Empress and Dicor MGC]). The amount of bacteria and glucans adhered on the specimens was measured after incubation for 24 hours at 37 degrees C with radio-labeled cariogenic bacteria and sucrose. This adhesion test was performed using two different surfaces with 600-grit roughness and clinical smoothness. Irrespective of the surface roughness, the least amount of plaque adhered to the ceramics. However, in the case of the resin composite and amalgam, the amount of bacteria and glucan adhesion decreased dramatically by polishing, though there were no statistically different changes in the amount of bacteria and glucans that adhered to the ceramics even after polishing. In general, the amount of adhered bacteria showed almost the same tendency as that of glucans. Although no statistical differences in the amount of bacteria and glucan adhesion were detected among the three ceramics investigated in this study, a lesser amount of bacteria and glucans adhered to them compared to the other materials.

Aluminum Silicates↗