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Wouters BG, Delahoussaye YM, Evans JW, Birrell GW, Dorie MJ, Wang J, MacDermed D, Chiu RK, Brown JM. Mitochondrial dysfunction after aerobic exposure to the hypoxic cytotoxin tirapazamine. Cancer Res 2001; 61:145-52. [PMID: 11196153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Tirapazamine (TPZ) is a bioreductive drug that exhibits a high degree of selective toxicity toward hypoxic cells, and at doses that are used clinically, little or no cell killing is observed in aerobic cells. Nonetheless, the effects of TPZ on aerobic tissues are still responsible for the dose limitations on the clinical administration of this drug. Clinical side effects include fatigue, muscle cramping, and reversible ototoxicity. We have investigated TPZ-induced changes in the mitochondria in aerobically exposed cells as a potential mediator of these side effects. Our data show that aerobic administration of TPZ at clinically relevant doses results in a profound loss in the mitochondrial membrane potential (MMP). We show that loss in the MMP occurs in a variety of cell lines in vitro and also occurs in muscle tissues in vivo. The loss in MMP is temporary because recovery occurs within 2 h. TPZ is directly metabolized within mitochondria to a DNA-damaging form, and this metabolism leads to both the cell-killing effects of TPZ on aerobic cells at high doses and to the loss in MMP at clinically relevant doses. Using cell lines derived from genetically modified mice with a targeted deletion in manganese superoxide dismutase, we have further distinguished the phenotypic effects of TPZ in mitochondria at high toxic doses versus those at clinically relevant doses. We have investigated several potential mechanisms for this TPZ-induced loss in MMP. Our results indicate no change in the rate of cellular respiration in TPZ-treated cells. This implies that the loss in MMP results from an inability of the inner mitochondrial membrane to sustain a potential across the membrane after TPZ treatment. Incubation of cells with an inhibitor of the mitochondrial permeability transition suggests that the loss of MMP may result from the regulated opening of a large mitochondria channel.
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Stoldt CR, Caspersen KJ, Bartelt MC, Jenks CJ, Evans JW, Thiel PA. Using temperature to tune film roughness: nonintuitive behavior in a simple system. PHYSICAL REVIEW LETTERS 2000; 85:800-803. [PMID: 10991402 DOI: 10.1103/physrevlett.85.800] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2000] [Indexed: 05/23/2023]
Abstract
Ag(100) homoepitaxy constitutes one of the simplest systems in which to study thin-film growth. Yet we find that the roughness variation with temperature is extraordinarily complex. Specifically, as the deposition temperature is reduced from 300 to 50 K, the roughness of 25 monolayer films first increases, then decreases, then increases again. A transition from mound formation to self-affine (semifractal) growth occurs at approximately 135 K. The underlying mechanisms are postulated. An atomistic model incorporating these mechanisms reproduces the experimental data quantitatively.
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Liu DJ, Evans JW. Symmetry-breaking and percolation transitions in a surface reaction model with superlattice ordering. PHYSICAL REVIEW LETTERS 2000; 84:955-958. [PMID: 11017414 DOI: 10.1103/physrevlett.84.955] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/1999] [Indexed: 05/23/2023]
Abstract
A symmetry-breaking order-disorder transition of the Ising type is found in a nonequilibrium surface reaction model for CO oxidation incorporating superlattice ordering of adsorbed oxygen. We relate this transition to the percolation of superlattice domains of oxygen, and discuss the consequences for chemical diffusion of coadsorbed CO. The latter constitutes a new type of problem involving transport in disordered media.
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Evans JW, Walters AS, Hatch-Woodruff ML. Deathbed scene narratives: a construct and linguistic analysis. DEATH STUDIES 1999; 23:715-733. [PMID: 10848089 DOI: 10.1080/074811899200740] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The present study explored temporal and self/other dimensions of death attitudes among young adults. One hundred seventy-two undergraduate students were randomly assigned to 1 of 4 conditions: writing about one's death (age unspecified), one's death as a young adult, or the death of another (age unspecified), or the death of other as a young adult. Results indicated that the death of another, but not of oneself, was associated with more realistic considerations of death (e.g., pain, negative emotions). In addition, participants who wrote about death at an early age were less likely to describe their own deaths with negative emotion or to discuss physiological aspects of death and were less likely to express romanticized notions of death. Implications of these results for death anxiety research are discussed.
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Kovacs MS, Hocking DJ, Evans JW, Siim BG, Wouters BG, Brown JM. Cisplatin anti-tumour potentiation by tirapazamine results from a hypoxia-dependent cellular sensitization to cisplatin. Br J Cancer 1999; 80:1245-51. [PMID: 10376978 PMCID: PMC2362366 DOI: 10.1038/sj.bjc.6690492] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Tirapazamine (TPZ) is a new anticancer drug that is activated specifically at the low oxygen level typically found in solid tumours. It exhibits preferential cytotoxicity towards hypoxic cells and has been shown in preclinical studies with transplanted tumours and in phase II and III clinical trials to potentiate the anti-tumour efficacy of cisplatin without increasing its systemic toxicity. At present, the mechanism for this potentiation is unknown. Here we show that there is a schedule-dependent enhancement of cisplatin cytotoxicity by TPZ for cells in vitro that is similar to that seen with transplanted murine tumours. This cisplatin potentiation depends on the TPZ exposure being at oxygen concentrations below 1%, which are typical of many cells in tumours but not in normal tissues. Also, the interaction between TPZ and cisplatin does not occur in cells mutant in ERCC4, a protein essential for repair of DNA interstrand cross-links. Incubation of the cells with TPZ under hypoxia prior to cisplatin treatment increases cisplatin-induced DNA interstrand cross-links with kinetics suggesting that TPZ inhibits or delays repair of the DNA cross-links. In conclusion, we show that the tumour-specific potentiation of cisplatin cytotoxicity is likely the result of an interaction between TPZ and cisplatin at the cellular level that requires the low oxygen levels typical of those in solid tumours. The mechanism of the interaction appears to be through a potentiation of cisplatin-induced DNA interstrand cross-links, possibly as a result of a diminished or delayed repair of these lesions
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Evans JW, Yudoh K, Delahoussaye YM, Brown JM. Tirapazamine is metabolized to its DNA-damaging radical by intranuclear enzymes. Cancer Res 1998; 58:2098-101. [PMID: 9605751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tirapazamine (TPZ), a new anticancer drug that is currently in Phase II and III clinical trials, has a unique mechanism of action. Its cytotoxicity is selective for hypoxic cells in solid tumors and results from DNA damage produced by a free radical, which is generated by enzymatic reduction of the parent molecule. However, there is no agreement as to which enzyme(s) are involved. Here, we have measured both DNA damage and TPZ metabolism in A549 human lung cancer cells and in isolated nuclei derived from the cells. We show that, although the nuclei metabolize TPZ at a rate that is only 20% of that of whole cells, they have levels of DNA damage that are similar to those of the cells. We also show that TPZ radicals that are formed outside nuclei do not contribute to intranuclear DNA damage. Thus, essentially all of the DNA damage from TPZ results from radicals generated within the nucleus, and the 80% of the drug metabolism that occurs in the cytoplasm is probably irrelevant for the activity of this drug in killing hypoxic cells.
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Elwell JH, Siim BG, Evans JW, Brown JM. Adaptation of human tumor cells to tirapazamine under aerobic conditions: implications of increased antioxidant enzyme activity to mechanism of aerobic cytotoxicity. Biochem Pharmacol 1997; 54:249-57. [PMID: 9271329 DOI: 10.1016/s0006-2952(97)00171-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Tirapazamine (TPZ, 3-amino-1,2,4-benzotriazine 1,4-di-N-oxide, SR 4233, WIN 59075) is a bioreductive antitumor agent with a high selective toxicity for hypoxic cells. The selective hypoxic toxicity of TPZ results from the rapid reoxidation of the one-electron reduction product, the TPZ radical, in the presence of molecular oxygen with the concomitant production of superoxide radical. Under hypoxia the TPZ radical kills cells by causing DNA double-strand breaks and chromosome aberrations. However, the mechanism of aerobic cytotoxicity is still a matter of debate. In this study, we investigated the mechanism of aerobic cytotoxicity by adapting human lung adenocarcinoma A549 cells to aerobic TPZ exposure and characterizing the changes associated with drug resistance. The adapted cells were resistant to aerobic TPZ exposures (with dose-modifying factors of up to 9.2), although hypoxic sensitivity was largely unchanged. Relative to the parental A549 cell line, adaptation to continuous aerobic TPZ exposure resulted in increased levels of manganese superoxide dismutase (up to 9.4-fold), moderate increases in glutathione reductase (up to 2.1-fold), and loss of both quinone oxidoreductase (DT-diaphorase) activity and NADPH cytochrome P450 reductase activity. There was essentially no change in the activity of the cytoplasmic form of superoxide dismutase (CuZnSOD), catalase, or glutathione peroxidase. The increased activity of antioxidant enzymes in the resistant cell lines (in particular MnSOD) strongly suggests that reactive oxygen species are, in large part, responsible for the toxicity of TPZ under aerobic conditions, and is consistent with aerobic and hypoxic drug cytotoxicity resulting from different mechanisms.
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Kovacs MS, Yudoh K, Evans JW, Menke D, Brown JM. Stable translocations detected by fluorescence in situ hybridization: a rapid surrogate end point to evaluate the efficacy of a potentiator of tumor response to radiotherapy. Cancer Res 1997; 57:672-7. [PMID: 9044844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Testing potential modifiers of the response of tumors to radiation therapy requires large, expensive, and time-consuming clinical trials. It would, therefore, be of value to have a rapid surrogate end point of tumor response that could be used to evaluate such modifiers. We here propose that radiation-induced stable chromosome translocations measured by fluorescence in situ hybridization (FISH) could fulfill this purpose. The assay requires that the ratio of nonlethal stable translocations to lethal dicentric aberrations be unity and not change with radiation dose and that radiation-induced stable translocations remain in the tumor cell population essentially indefinitely after irradiation. We have tested these assumptions with four human tumor cell lines in vitro at doses of 1-5 Gy and found them to be valid. We also modified the response to fractionated irradiation of a human tumor xenograft in three different ways and quantitated the tumor response using clonogenic cell survival and using the FISH stable translocation assay. Both assays gave similar values for the extent of radiation modification. These data suggest that this assay could allow clinical evaluation of potential radiation sensitizers with fewer patients and in shorter times than is the case with conventional clinical trials.
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Bartelt MC, Evans JW. Exact island-size distributions for submonolayer deposition: Influence of correlations between island size and separation. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R17359-R17362. [PMID: 9985957 DOI: 10.1103/physrevb.54.r17359] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Bartelt MC, Günther S, Kopatzki E, Behm RJ, Evans JW. Island-size distributions in submonolayer epitaxial growth: Influence of the mobility of small clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:4099-4104. [PMID: 9983966 DOI: 10.1103/physrevb.53.4099] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Wen J, Evans JW, Bartelt MC, Burnett JW, Thiel PA. Coarsening mechanisms in a metal film: From cluster diffusion to vacancy ripening. PHYSICAL REVIEW LETTERS 1996; 76:652-655. [PMID: 10061513 DOI: 10.1103/physrevlett.76.652] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Evans JW, Liu XF, Kirchgessner CU, Brown JM. Induction and repair of chromosome aberrations in scid cells measured by premature chromosome condensation. Radiat Res 1996; 145:39-46. [PMID: 8532835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Severe combined immunodeficient (scid) murine cells, which are defective in both repair of DNA double-strand breaks and V(D)J recombination, are deficient in DNA-dependent protein kinase (DNA-PK), a protein which forms an activated complex with the DNA end-binding Ku proteins (p80 and p70) upon association with damaged DNA. Xrs 5 cells are deficient in the Ku p80 protein and also fail to form an active DNA-PK repair complex. Since both scid and xrs cells are defective in the same protein complex, we compared the kinetics of chromosome repair in scid cells to results published previously for xrs 5 cells. C.B-17 cells, scid cells and scid cells complemented with a single human chromosome 8 were irradiated with 6 Gy and allowed to repair from 0-24 h before fusion to HeLa cells for chromosome condensation. Breaks and dicentrics were visualized by fluorescence in situ hybridization. All cells had the same initial amount of chromosome damage, but scid cells had a slower rate of rejoining, more unrejoined breaks and more dicentrics than C.B-17 and scid cells with human chromosome 8. The scid cells appear to respond differently than xrs 5 cells, despite both cells lacking an essential component of the same DNA repair complex.
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Bartelt MC, Evans JW. Transition to Multilayer Kinetic Roughening for Metal (100) Homoepitaxy. PHYSICAL REVIEW LETTERS 1995; 75:4250-4253. [PMID: 10059857 DOI: 10.1103/physrevlett.75.4250] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Tammaro M, Evans JW. Monomer-dimer surface-reaction model: Influence of the dimer adsorption mechanism. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1995; 52:2310-2317. [PMID: 9963672 DOI: 10.1103/physreve.52.2310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Kirchgessner CU, Patil CK, Evans JW, Cuomo CA, Fried LM, Carter T, Oettinger MA, Brown JM. DNA-dependent kinase (p350) as a candidate gene for the murine SCID defect. Science 1995; 267:1178-83. [PMID: 7855601 DOI: 10.1126/science.7855601] [Citation(s) in RCA: 491] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Severe combined immunodeficient (SCID) mice are deficient in a recombination process utilized in both DNA double-strand break repair and in V(D)J recombination. The phenotype of these mice involves both cellular hypersensitivity to ionizing radiation and a lack of B and T cell immunity. The catalytic subunit of DNA-dependent protein kinase, p350, was identified as a strong candidate for the murine gene SCID. Both p350 and a gene complementing the SCID defect colocalize to human chromosome 8q11. Chromosomal fragments expressing p350 complement the SCID phenotype, and p350 protein levels are greatly reduced in cells derived from SCID mice compared to cells from wild-type mice.
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Sasai K, Evans JW, Kovacs MS, Brown JM. Prediction of human cell radiosensitivity: comparison of clonogenic assay with chromosome aberrations scored using premature chromosome condensation with fluorescence in situ hybridization. Int J Radiat Oncol Biol Phys 1994; 30:1127-32. [PMID: 7961021 DOI: 10.1016/0360-3016(94)90319-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
PURPOSE The purpose of the present investigation was to determine whether chromosome aberrations scored by premature chromosome condensation (PCC) and fluorescence in situ hybridization (FISH) can predict the radiosensitivity of human cell lines, thereby providing a possible means of assessing the in situ radiosensitivity of normal tissues and the radiocurability of individual human cancers. METHODS AND MATERIALS We used four cells lines of different radiosensitivity: normal human fibroblasts (AG1522), ataxia-telangiectasia fibroblasts (AT2052), a human fibrosarcoma cell line (HT1080), and a human melanoma cell line (melanoma 903). These were irradiated in plateau phase with a range of doses and assessed both for clonogenic cell survival and for aberrations in a single chromosome (number 4) immediately after, and 24 h after irradiation. RESULTS The initial number of breaks in chromosome 4 was proportional to irradiation dose and was identical for all the different human cell lines, irrespective of radiosensitivity. On the other hand, the number of chromosome 4 breaks remaining 24 h after irradiation reflected the radiosensitivity of the cells such that the relationship between residual chromosome aberrations and cell survival was the same for the different cell lines. CONCLUSIONS These results suggest that the scoring of chromosome aberrations in interphase using FISH with PCC holds considerable promise for predicting the radiosensitivity of normal and tumor tissues in situ.
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Evans JW, Singer M, Coppinger SW, Macartney N, Walker JM, Milroy EJ. Cardiovascular performance and core temperature during transurethral prostatectomy. J Urol 1994; 152:2025-9. [PMID: 7966668 DOI: 10.1016/s0022-5347(17)32297-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hemodynamic performance and core temperature were recorded during transurethral prostatectomy in 52 patients who were stratified according to cardiac symptom score and then randomized to undergo standard (31) or isothermic (21) transurethral prostatectomy. During the standard procedure ambient temperature (21C) irrigant was used, while during isothermic prostatectomy warmed irrigant at 38C was used to prevent heat loss from the bladder, and a warming blanket and humidifying filter were used to decrease cutaneous and respiratory heat loss. Core temperature decreased by a mean of 0.8C (95% confidence interval -0.9 to -0.7) during standard transurethral prostatectomy and by 0.27C (-0.4 to -0.15) during the isothermic procedure. The standard prostatectomy group showed a significant hemodynamic response consisting of increased mean arterial pressure (p < 0.0002), increased index of systemic vascular resistance (p < 0.0001), bradycardia (p < 0.02), and decreased Doppler indexes of stroke volume (p < 0.005) and cardiac output (p < 0.001). The isothermic transurethral prostatectomy group was hemodynamically stable. These differences between the groups suggest that rapid central cooling exerted a significant effect on perioperative hemodynamic performance during transurethral prostatectomy.
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Evans JW, Ray TR. Interface propagation and nucleation phenomena for discontinuous poisoning transitions in surface-reaction models. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1994; 50:4302-4314. [PMID: 9962511 DOI: 10.1103/physreve.50.4302] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Wen J, Chang S, Burnett JW, Evans JW, Thiel PA. Diffusion of large two-dimensional Ag clusters on Ag(100). PHYSICAL REVIEW LETTERS 1994; 73:2591-2594. [PMID: 10057099 DOI: 10.1103/physrevlett.73.2591] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Elliott JP, Gordon JO, Evans JW, Platt LO, Milam WH, Rigby JR. Are PSA 8-10 particularly worrisome numbers? JOURNAL OF THE MISSISSIPPI STATE MEDICAL ASSOCIATION 1994; 35:323-325. [PMID: 7528806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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