The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
Keizo Sugimachi - One of the best experts on this subject based on the ideXlab platform.
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Use of the succinate dehydrogenase inhibition test in assessing the Heat Sensitivity of tumor cells.
Oncology, 1993Co-Authors: Shunji Kohnoe, Yoshihiko Maehara, Ikuo Takahashi, Motofumi Yoshida, Yasunori Emi, Tetsuya Kusumoto, Keizo SugimachiAbstract:The in vitro succinate dehydrogenase (SD) inhibition (SDI) test was used to determine the Heat Sensitivity of tumor cell lines and human tumor cells. The tumor cells were exposed to Heat in vitro and the decrease in SD activity was assayed using a colorimetric assay, the SDI test. With respect to survival curves of HeLa cells, the SDI test correlated well with the clonogenic assay and the dye exclusion assay. Decrease in the SD activity of HeLa cells after the Heat treatment (41–44 °C, 10 min to 5 h) depended on both the temperature and the duration of Heat exposure. S- and G2/M-phase-rich HeLa cells were more sensitive to Heat than were the G1-phase-rich cells. The SDI test exhibited a wide variation in the Heat Sensitivity among four cell lines (HeLa, B-16, V-79, and a human GT-1 squamous cell carcinoma). Variation in Heat Sensitivity was also detected among individual tumor tissues obtained from clinical specimens of gastric, esophageal, and colorectal cancers. Gastric cancer tissues were more sensitive to Heat than were esophageal and colorectal tissues. We recommended that if the SDI test is used to assess the Heat Sensitivity of clinical tumor tissues in vitro, appropriate therapy for individual patients can be designed.
Edo Vellenga - One of the best experts on this subject based on the ideXlab platform.
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Differences in Heat Sensitivity between normal and acute myeloid leukemic stem cells: Feasibility of hyperthermic purging of leukemic cells from autologous stem cell grafts
Experimental hematology, 2003Co-Authors: Pieter K. Wierenga, Rita Setroikromo, Gera Kamps, Harm H. Kampinga, Edo VellengaAbstract:Abstract Objectives. In autologous stem cell transplantation contamination of the graft with malignant cells is frequently noticed and necessitates the use of in vivo or in vitro purging modalities. The hematopoietic recovery after transplantation depends on the number of stem and progenitor cells in the transplant. Therefore, in the present study the effects of hyperthermic treatment on the human normal and acute myeloid leukemic (AML) stem cell compartment were investigated. Methods. Normal bone marrow and AML blasts were Heat treated up to 120 minutes at 43°C. The surviving fractions of the different stem cell subsets were determined using in vitro methylcellulose and cobblestone area-forming cell (CAFC) clonogenic assays, as well as the in vivo NOD/SCID repopulating assay. The leukemic nature of the colonies from AML cells was confirmed by RT-PCR analysis. In order to increase the therapeutic index of the hyperthermic purging modality, the Heat treatment was preceded by a 3-hour incubation at 37°C with the ether lipid ET-18-OCH 3 (25 μg/mL). Results. It could be demonstrated that normal progenitor cells are far more resistant to hyperthermia than leukemic progenitor cells (56%±7% vs 9.9%±2.6% survival after 60 minutes at 43°C, respectively). Furthermore, normal hematopoietic stem cells appear to be extremely resistant to the Heat treatment (94%±9% survival after 60 minutes at 43°C). In contrast, in the leukemic stem cell compartment no significant differences in Heat Sensitivity between the stem cells and progenitor subsets could be observed (12.3%±2.9% vs 9.9%±2.6% survival after 60 minutes at 43°C, respectively). The combined treatment resulted in a survival for normal progenitor and stem cells of 32%±6% and 85%±15% after 60 minutes at 43°C, respectively. Under these conditions the number of leukemic stem cells was reduced to 1%±0.3%. After 120 minutes at 43°C, no AML-colonies could be detected anymore. Conclusions. Our data demonstrate that leukemic stem cells have an increased hyperthermic Sensitivity compared to their normal counterparts and that this difference can be further increased in combination with ET-18-OCH 3 . These striking differences in Heat Sensitivity warrant the use of hyperthermia as a clinically applicable purging modality in autologous stem cell transplantation.
Jatinder Ahluwalia - One of the best experts on this subject based on the ideXlab platform.
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the putative role of vanilloid receptor like protein 1 in mediating high threshold noxious Heat Sensitivity in rat cultured primary sensory neurons
European Journal of Neuroscience, 2002Co-Authors: Humphrey P Rang, Jatinder Ahluwalia, Istvan NagyAbstract:High threshold noxious Heat-activated currents and vanilloid receptor-like protein-1 expression were studied in rat cultured primary sensory neurons to find out the molecule(s) responsible for high threshold noxious Heat-Sensitivity. The average temperature threshold and amplitude of high threshold noxious Heat-activated currents were 51.6 +/- 0.13 degrees C and -2.0 +/- 0.1nA (at a holding potential of -60 mV), respectively. The current-voltage relationship of high threshold noxious Heat-activated currents was linear at positive membrane potentials, while it showed a weak inward rectification at negative membrane potentials. The average reversal potential measured in control intracellular and extracellular solutions was 4.5 +/- 0.9 mV (n = 6). Ionic substitutions revealed that the high threshold noxious Heat-activated current is a nonselective cationic current with calculated ionic permeabilities of Cs+ : Na+ : Ca2+ (1 : 1.3 : 4.5). Consecutive stimuli reduced the Heat threshold from 52.2 +/- 1 to 48.4 +/- 1.4 degrees C and then to 44 +/- 0.7 degrees C (n = 3). High threshold noxious Heat-activated currents could dose-dependently and reversibly be reduced by ruthenium red (100 nm-10 micro m) but not by capsazepine (10 micro m). The average longest diameter of high threshold noxious Heat-sensitive neurons was 31.48 +/- 0.5 micro m (A = approximately 778 micro m2; n = 77). Twenty-three percent of the total neuronal population expressed vanilloid receptor-like protein-1. The average area of the vanilloid receptor-like protein-1-immunopositive cells was 1,696 +/- 65.3 micro m2 (d = approximately 46 micro m). Vanilloid receptor-like protein-1-expressing neurons did not express the vanilloid receptor 1. Comparison of our data with results obtained in vanilloid receptor-like protein-1-expressing non-neuronal cells and previous immunohistochemical findings suggests that high threshold noxious Heat-activated currents are produced by vanilloid receptor-like protein-1 and that high threshold Heat-sensitive dorsal root ganglion neurons are the perikarya of type I noxious Heat-sensitive fibers.
Shunji Kohnoe - One of the best experts on this subject based on the ideXlab platform.
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Use of the succinate dehydrogenase inhibition test in assessing the Heat Sensitivity of tumor cells.
Oncology, 1993Co-Authors: Shunji Kohnoe, Yoshihiko Maehara, Ikuo Takahashi, Motofumi Yoshida, Yasunori Emi, Tetsuya Kusumoto, Keizo SugimachiAbstract:The in vitro succinate dehydrogenase (SD) inhibition (SDI) test was used to determine the Heat Sensitivity of tumor cell lines and human tumor cells. The tumor cells were exposed to Heat in vitro and the decrease in SD activity was assayed using a colorimetric assay, the SDI test. With respect to survival curves of HeLa cells, the SDI test correlated well with the clonogenic assay and the dye exclusion assay. Decrease in the SD activity of HeLa cells after the Heat treatment (41–44 °C, 10 min to 5 h) depended on both the temperature and the duration of Heat exposure. S- and G2/M-phase-rich HeLa cells were more sensitive to Heat than were the G1-phase-rich cells. The SDI test exhibited a wide variation in the Heat Sensitivity among four cell lines (HeLa, B-16, V-79, and a human GT-1 squamous cell carcinoma). Variation in Heat Sensitivity was also detected among individual tumor tissues obtained from clinical specimens of gastric, esophageal, and colorectal cancers. Gastric cancer tissues were more sensitive to Heat than were esophageal and colorectal tissues. We recommended that if the SDI test is used to assess the Heat Sensitivity of clinical tumor tissues in vitro, appropriate therapy for individual patients can be designed.
Pieter K. Wierenga - One of the best experts on this subject based on the ideXlab platform.
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Differences in Heat Sensitivity between normal and acute myeloid leukemic stem cells: Feasibility of hyperthermic purging of leukemic cells from autologous stem cell grafts
Experimental hematology, 2003Co-Authors: Pieter K. Wierenga, Rita Setroikromo, Gera Kamps, Harm H. Kampinga, Edo VellengaAbstract:Abstract Objectives. In autologous stem cell transplantation contamination of the graft with malignant cells is frequently noticed and necessitates the use of in vivo or in vitro purging modalities. The hematopoietic recovery after transplantation depends on the number of stem and progenitor cells in the transplant. Therefore, in the present study the effects of hyperthermic treatment on the human normal and acute myeloid leukemic (AML) stem cell compartment were investigated. Methods. Normal bone marrow and AML blasts were Heat treated up to 120 minutes at 43°C. The surviving fractions of the different stem cell subsets were determined using in vitro methylcellulose and cobblestone area-forming cell (CAFC) clonogenic assays, as well as the in vivo NOD/SCID repopulating assay. The leukemic nature of the colonies from AML cells was confirmed by RT-PCR analysis. In order to increase the therapeutic index of the hyperthermic purging modality, the Heat treatment was preceded by a 3-hour incubation at 37°C with the ether lipid ET-18-OCH 3 (25 μg/mL). Results. It could be demonstrated that normal progenitor cells are far more resistant to hyperthermia than leukemic progenitor cells (56%±7% vs 9.9%±2.6% survival after 60 minutes at 43°C, respectively). Furthermore, normal hematopoietic stem cells appear to be extremely resistant to the Heat treatment (94%±9% survival after 60 minutes at 43°C). In contrast, in the leukemic stem cell compartment no significant differences in Heat Sensitivity between the stem cells and progenitor subsets could be observed (12.3%±2.9% vs 9.9%±2.6% survival after 60 minutes at 43°C, respectively). The combined treatment resulted in a survival for normal progenitor and stem cells of 32%±6% and 85%±15% after 60 minutes at 43°C, respectively. Under these conditions the number of leukemic stem cells was reduced to 1%±0.3%. After 120 minutes at 43°C, no AML-colonies could be detected anymore. Conclusions. Our data demonstrate that leukemic stem cells have an increased hyperthermic Sensitivity compared to their normal counterparts and that this difference can be further increased in combination with ET-18-OCH 3 . These striking differences in Heat Sensitivity warrant the use of hyperthermia as a clinically applicable purging modality in autologous stem cell transplantation.