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Frydman JL, Gelfman LP, Farquhar D, Ramaswamy R, Dow LA. Goals, Values, and Priorities of Hospitalized Patients: Using a Structured Communication Tool to Engage Medical Students in Serious Illness Communication. J Palliat Med 2024; 27:99-103. [PMID: 37878370 DOI: 10.1089/jpm.2023.0281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023] Open
Abstract
Background: To build third-year medical students' serious illness communication skills, we implemented a structured communication tool-the VALUES tool-focused on patients' goals, values, and priorities and described students' experiences using this tool. Methods: Medical students participated in a social worker-led VALUES didactic and discussion with a patient on the palliative care consult service and, subsequently, completed an anonymous survey about their comfort with the VALUES tool and its usefulness for learning (5-point Likert scales). Results: Of the 142 medical students who participated in the VALUES didactic, 37 completed the survey (26%). The VALUES tool was rated highly in terms of usefulness (mean 4.5; standard deviation [SD] 0.7) and rated lower in terms of overall comfort (mean 3.7; SD 0.7). Conclusion: Our project explored the integration of a VALUES tool into medical student education, and we show that the tool is well rated by learners in terms of comfort and usefulness.
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Affiliation(s)
- Julia L Frydman
- Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Laura P Gelfman
- Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Geriatric Research, Education and Clinical Center, James J. Peters VA Medical Center, Bronx, New York, USA
| | - Diane Farquhar
- Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ravishankar Ramaswamy
- Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Lindsay A Dow
- Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Tanner A, Mazul A, Farquhar D, Taylor J, Brennan P, Anantharaman D, Abedi-Ardekani B, Hayes N, Weissler M, Patel S, Chera B, Olshan A, Zevallos J. Comparative Analysis of New Staging Systems for HPV-associated Oropharyngeal Squamous Cell Carcinoma in a Population-Based Cohort. Int J Radiat Oncol Biol Phys 2018. [DOI: 10.1016/j.ijrobp.2017.12.114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Farquhar D, Sheth S, Mazul A, Little P, Hayes D, Zevallos J. Genetic Mutations in KEAP/NFE2L2 Associated With Radiation Resistance in Early-Stage Laryngeal Squamous Cell Carcinoma: A Case Series. Int J Radiat Oncol Biol Phys 2018. [DOI: 10.1016/j.ijrobp.2017.12.176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Pompon A, Lefebvre I, Imbach JL, Kahn S, Farquhar D. Decomposition Pathways of the Mono- and Bis(Pivaloyloxymethyl) Esters of Azidothymidine 5′-Monophosphate in Cell Extract and in Tissue Culture Medium: An Application of the ‘on-line ISRP-Cleaning’ HPLC Technique. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/095632029400500205] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bis(pivaloyloxymethyl) azidothymidine 5′-monophosphate (piv2-AZTMP) was designed as a cell membrane-permeable precursor of AZTMP. We have reported previously that when incubated with CEM cells deficient in thymidine kinase, piv2-AZTMP gives rise to intracellular AZTMP and the corresponding diphosphate (AZTDP) and triphosphate (AZTTP). Under similar conditions, no intracellular nucleotides were formed with AZT. However, the mechanism by which piv2-AZTMP is converted to AZTMP has not been established. To address this question, we have used the recently developed ‘on-line ISRP-cleaning’ HPLC technique to investigate the stability and metabolic fate of piv2-AZTMP (1) in RPMI 1640 medium, (2) in RPMI containing 10% heat-inactivated fetal calf serum, and (3) in CEM cell extracts. Similar studies were conducted starting with mono(pivaloyloxymethyl) azidothymidine 5′-monophosphate (piv2 AZTMP). From the kinetics of these reactions, it appears that piv2-AZTMP is slowly hydrolyzed to piv1-AZTMP in RPMI and that the metabolic sequence in cell extract and in tissue culture medium is clearly: piv2-AZTMP→ piv1AZTMP→ AZTMP→ AZT. The rate constants are quite different in these three media. Although it is evident that the first step in the metabolism of piv2-AZTMP is catalysed by carboxylate esterase, the enzyme(s) responsible for the second step, piv1-AZTMP→ AZTMP, is less apparent, as carboxylate esterases and/or phosphodiesterases can be taken in account. However, analysis of the kinetic data strongly suggests that carboxylate esterase does not play a significant role and that this second step is mediated by phosphodiesterases. Collectively, these studies demonstrate that piv2-AZTMP is an effective prodrug of AZTMP. They also establish that prv1-AZTMP is an intermediate in this process, and define the sequence of the overall metabolic reaction. With this increased understanding of the metabolism of piv2-AZTMP, it should be possible rationally to design analogues with optimal structural and pharmacological properties for use in vivo.
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Affiliation(s)
- A. Pompon
- Laboratoire de Chimie Bio-Organique, U.R.A. CNRS no. 488, case 008, Université Montpellier II, Place E. Bataillon, 34095 Montpellier cédex 5, France
| | - I. Lefebvre
- Laboratoire de Chimie Bio-Organique, U.R.A. CNRS no. 488, case 008, Université Montpellier II, Place E. Bataillon, 34095 Montpellier cédex 5, France
| | - J.-L. Imbach
- Laboratoire de Chimie Bio-Organique, U.R.A. CNRS no. 488, case 008, Université Montpellier II, Place E. Bataillon, 34095 Montpellier cédex 5, France
| | - S. Kahn
- Department of Medical Oncology, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
| | - D. Farquhar
- Department of Medical Oncology, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
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Spath NB, Amft N, Farquhar D. Reply: On the radar: Lyme neuroborreliosis, an infectious cause of cerebral vasculitis. QJM 2015; 108:756. [PMID: 25660611 DOI: 10.1093/qjmed/hcv040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- N B Spath
- Intensive Care Unit, Waikato Hospital, Hamilton 3206, New ZealandDepartment of Rheumatology, Western General Hospital, Edinburgh, Scotland EH4 2XU, UKDepartment of General Medicine, St John's Hospital, Livingston, Scotland EH54 6PP, UK
| | - N Amft
- Intensive Care Unit, Waikato Hospital, Hamilton 3206, New ZealandDepartment of Rheumatology, Western General Hospital, Edinburgh, Scotland EH4 2XU, UKDepartment of General Medicine, St John's Hospital, Livingston, Scotland EH54 6PP, UK
| | - D Farquhar
- Intensive Care Unit, Waikato Hospital, Hamilton 3206, New ZealandDepartment of Rheumatology, Western General Hospital, Edinburgh, Scotland EH4 2XU, UKDepartment of General Medicine, St John's Hospital, Livingston, Scotland EH54 6PP, UK
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Affiliation(s)
- N B Spath
- From the Department of Haematology and the Department of Rheumatology, Western General Hospital, Crewe Road South, Edinburgh, EH4 2XU and Consultant Physician, St. John's Hospital, Howden Road West, Livingston, West Lothian EH54 6PP, UK
| | - N Amft
- From the Department of Haematology and the Department of Rheumatology, Western General Hospital, Crewe Road South, Edinburgh, EH4 2XU and Consultant Physician, St. John's Hospital, Howden Road West, Livingston, West Lothian EH54 6PP, UK
| | - D Farquhar
- From the Department of Haematology and the Department of Rheumatology, Western General Hospital, Crewe Road South, Edinburgh, EH4 2XU and Consultant Physician, St. John's Hospital, Howden Road West, Livingston, West Lothian EH54 6PP, UK
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Khodadadian M, Leroux ME, Auzenne E, Ghosh SC, Farquhar D, Evans R, Spohn W, Zou Y, Klostergaard J. MRP- and BCL-2-mediated drug resistance in human SCLC: effects of apoptotic sphingolipids in vitro. Lung Cancer 2009; 66:48-57. [PMID: 19195736 DOI: 10.1016/j.lungcan.2009.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 12/31/2008] [Accepted: 01/03/2009] [Indexed: 12/25/2022]
Abstract
Multidrug-resistance-associated protein (MRP) and BCL-2 contribute to drug resistance expressed in SCLC. To establish whether MRP-mediated drug resistance affects sphingolipid (SL)-induced apoptosis in SCLC, we first examined the human SCLC cell line, UMCC-1, and its MRP over-expressing, drug-resistant subline, UMCC-1/VP. Despite significantly decreased sensitivity to doxorubicin (Dox) and to the etoposide, VP-16, the drug-selected line was essentially equally as sensitive to treatment with exogenous ceramide (Cer), sphingosine (Sp) or dimethyl-sphingosine (DMSP) as the parental line. Next, we observed that high BCL-2-expressing human H69 SCLC cells, that were approximately 160-fold more sensitive to Dox than their combined BCL-2 and MRP-over-expressing (H69AR) counterparts, were only approximately 5-fold more resistant to DMSP. Time-lapse fluorescence microscopy of either UMCC cell line treated with DMSP-Coumarin revealed comparable extents and kinetics of SL uptake, further ruling out MRP-mediated effects on drug uptake. DMSP potentiated the cytotoxic activity of VP-16 and Taxol, but not Dox, in drug-resistant UMCC-1/VP cells. However, this sensitization did not appear to involve DMSP-mediated effects on the function of MRP in drug export; nor did DMSP strongly shift the balance of pro-apoptotic Sps and anti-apoptotic Sp-1-Ps in these cells. We conclude that SL-induced apoptosis markedly overcomes or bypasses MRP-mediated drug resistance relevant to SCLC and may suggest a novel therapeutic approach to chemotherapy for these tumors.
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Affiliation(s)
- M Khodadadian
- Department of Molecular and Cellular Oncology, The University of Texas, M.D. Anderson Cancer Center, Houston, TX 77030, United States
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Leroux ME, Auzenne E, Evans R, Hail N, Spohn W, Ghosh SC, Farquhar D, McDonnell T, Klostergaard J. Sphingolipids and the sphingosine kinase inhibitor, SKI II, induce BCL-2-independent apoptosis in human prostatic adenocarcinoma cells. Prostate 2007; 67:1699-717. [PMID: 17879964 DOI: 10.1002/pros.20645] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
BACKGROUND Elevated BCL-2 is one mechanism of therapeutic resistance in prostate cancer (PC), and new approaches are needed to overcome such resistance. METHODS We evaluated the effects of BCL-2 over-expression in human prostatic adenocarcinoma cells on their susceptibility to sphingolipids (SLs) and to the sphingosine kinase (SpK) inhibitor, SKI II. RESULTS In survival assays, no significant differences were observed in the responses to sphingosine or ceramide among parental PC-3 cells lacking detectable BCL-2 and BCL-2 over-expressing PC-3 transfectants; similarly, the responses to dimethyl-sphingosine (DMSP) of parental LNCaP cells and a BCL-2 over-expressing LNCaP transfectant were equivalent. SKI II induced protracted, BCL-2-independent survival loss in both PC-3 and LNCaP parental/transfectant pairs; in contrast, DMSP induced rapid cell shrinkage, caspase activation and caspase-dependent DNA fragmentation. DMSP-induced DNA fragmentation and loss of mitochondrial membrane potential were equivalent in BCL-2 transfectants and parental PC-3 cells and were not associated with BCL-2 downregulation. DMSP-mediated cytotoxicity was not associated with the enhanced production of reactive oxygen intermediates. SL analyses of parental and transfectant PC-3 cells did not reveal increased levels of sphingosine-1-phosphate in the BCL-2 transfectants; further, there only a modest early shift, corresponding to apoptotic onset, in pro- versus anti-apoptotic SLs in response to DMSP treatment. CONCLUSIONS Thus, in contrast to the inhibitory effects of BCL-2 on apoptosis induced by various agents in tumor cells, SKI II and selected pro-apoptotic SLs appear atypical in their independence from such inhibition, and may have merits as new candidates for treatment of AI PC.
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Affiliation(s)
- M E Leroux
- Department of Molecular and Cellular Oncology, The University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
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Klostergaard J, Auzenne E, Ghosh S, Farquhar D, Rivera B, Price RE. Magnetic resonance imaging-based prospective detection of intraperitoneal human ovarian carcinoma xenografts treatment response. Int J Gynecol Cancer 2006; 16 Suppl 1:111-7. [PMID: 16515577 DOI: 10.1111/j.1525-1438.2006.00502.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The feasibility of applying magnetic resonance imaging (MRI) for conducting prospective studies of intraperitoneal (i.p.) tumor treatment response to chemotherapy and resultant effects on survival in human ovarian carcinoma/nude mouse orthotopic xenograft models was evaluated. Female nude mice were implanted i.p. with either NMP-1 or SKOV-3ip. human ovarian carcinoma cells on day 0. Initial T2-weighted magnetic resonance (MR) images of the abdomens of NMP-1-implanted mice were obtained on day 7 to confirm the presence of nascent tumors; similar confirmations were made on day 14 with mice bearing SKOV-3ip. xenografts. On the initial imaging days, a multiple-dose regimen of cisplatin (CDDP; qd7 x3) was commenced, using 4 or 6 mg/kg treatments with the NMP-1 model and using 6 mg/kg treatments with the SKOV-3ip. model. Mice were reimaged multiple times, 2 days following each CDDP injection and at later times as well, depending on host survival. The images for each mouse from the last imaging day (day 30 for NMP-1, day 44 for SKOV-3ip.) were used in a blinded fashion to attempt to visually distinguish control from treated mice and to determine whether MRI could predict a survival benefit. For SKOV-3ip. mice, ten out of ten mice were correctly segregated into the control or the CDDP treatment group based solely on these blinded, nonquantified MR results. In this model, the 6 mg/kg multiple-dose regimen achieved a modest response, improving life span by approximately 24%. However, for the NMP-1 mice, only six out of nine evaluable mice were correctly segregated into the control or one of the treatment groups by similar MRI criteria, a virtually random distribution; further, neither CDDP treatment regimen achieved a significant improvement in survival in this model. In another study, NMP-1-implanted mice were treated on day 7 after tumor implantation with a single injection of a hyaluronic acid-paclitaxel copolymer. Control and treated mice were MR imaged on day 28, which revealed marked reductions in tumor burden in treated mice, correlating well with a subsequently observed improved survival of approximately 40%. Our results suggest that MRI can be used to serially and noninvasively monitor treatment response and predict ongoing treatment effects on survival.
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Affiliation(s)
- J Klostergaard
- Department of Molecular and Cellular Oncology, The University of Texas, MD Anderson Cancer Center, Houston, Texas 77030, USA.
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Farquhar D, Benvenuto JA, Loo TL. An efficient and convenient synthesis of 5-(3,3-dimethyl-14C-1-triazeno)-imidazole-4-carboxamide. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580160414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Klostergaard J, Auzenne E, Ghosh S, Farquhar D, Rivera B, Price RE. Magnetic resonance imaging–based prospective detection of intraperitoneal human ovarian carcinoma xenografts treatment response. Int J Gynecol Cancer 2006. [DOI: 10.1136/ijgc-00009577-200602001-00018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The feasibility of applying magnetic resonance imaging (MRI) for conducting prospective studies of intraperitoneal (i.p.) tumor treatment response to chemotherapy and resultant effects on survival in human ovarian carcinoma/nude mouse orthotopic xenograft models was evaluated. Female nude mice were implanted i.p. with either NMP-1 or SKOV-3ip. human ovarian carcinoma cells on day 0. Initial T2-weighted magnetic resonance (MR) images of the abdomens of NMP-1–implanted mice were obtained on day 7 to confirm the presence of nascent tumors; similar confirmations were made on day 14 with mice bearing SKOV-3ip. xenografts. On the initial imaging days, a multiple-dose regimen of cisplatin (CDDP; qd7 ×3) was commenced, using 4 or 6 mg/kg treatments with the NMP-1 model and using 6 mg/kg treatments with the SKOV-3ip. model. Mice were reimaged multiple times, 2 days following each CDDP injection and at later times as well, depending on host survival. The images for each mouse from the last imaging day (day 30 for NMP-1, day 44 for SKOV-3ip.) were used in a blinded fashion to attempt to visually distinguish control from treated mice and to determine whether MRI could predict a survival benefit. For SKOV-3ip. mice, ten out of ten mice were correctly segregated into the control or the CDDP treatment group based solely on these blinded, nonquantified MR results. In this model, the 6 mg/kg multiple-dose regimen achieved a modest response, improving life span by ∼24%. However, for the NMP-1 mice, only six out of nine evaluable mice were correctly segregated into the control or one of the treatment groups by similar MRI criteria, a virtually random distribution; further, neither CDDP treatment regimen achieved a significant improvement in survival in this model. In another study, NMP-1–implanted mice were treated on day 7 after tumor implantation with a single injection of a hyaluronic acid–paclitaxel copolymer. Control and treated mice were MR imaged on day 28, which revealed marked reductions in tumor burden in treated mice, correlating well with a subsequently observed improved survival of ∼40%. Our results suggest that MRI can be used to serially and noninvasively monitor treatment response and predict ongoing treatment effects on survival.
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Abstract
N-(5,5-Diacetoxypent-1-yl)doxorubicin (DAPDOX) (3), a new, water-soluble analogue of doxorubicin, has been synthesized by coupling doxorubicin with 5-oxopentane-1,1-diacetate in the presence of NaBH3CN. This analogue was designed to be converted to the corresponding aldehyde, N-(5-oxopent-1-yl)doxorubicin, in the presence of carboxylate hydrolases, enzymes that are ubiquitous in tissue. DAPDOX had a half-life of several days in 0.05 M phosphate or 0.05 M acetate buffer solution at pH 4.0. However, in 0.05 M phosphate buffer at pH 7.4 in the presence of 20 unit equiv of porcine liver carboxylate esterase, the half-life of DAPDOX was less than 1 min. N-(5-acetoxypent-1-yl)doxorubicin (4), which should give rise to N-(5-hydroxypent-1-yl)doxorubicin on esterase-mediated hydrolysis, and N-(pent-1-yl)doxorubicin (5), were also prepared for comparative biological studies. DAPDOX was 150 times more potent than doxorubicin at inhibiting the growth of Chinese hamster ovary (CHO) cells in culture. The compound retained the same degree of potency against a CHO subline 100-fold resistant to doxorubicin (CHO/DOX) that expressed elevated levels of P-glycoprotein. Compounds 4 and 5, on the other hand, were no more effective than doxorubicin at inhibiting the growth of CHO cells and were 4-7-fold less potent against the CHO/DOX subline. DAPDOX is representative of a new structural class of doxorubicin analogues with unique chemical and biological properties.
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Affiliation(s)
- A Cherif
- Department of Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston 77030
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Farquhar D. Angiotensin-Il-receptor blockers and nephropathy in patients with type 2 diabetes. CMAJ 2001; 165:1379. [PMID: 11760990 PMCID: PMC81648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
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Farquhar D. Bypass surgery or stenting for multivessel coronary artery disease? CMAJ 2001; 164:1742. [PMID: 11450219 PMCID: PMC81178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Affiliation(s)
- D Farquhar
- Division of Internal Medicine, Queen's University, Kingston, Ont
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Farquhar D. Varicella vaccine in clinical practice. CMAJ 2001; 164:1485. [PMID: 11387927 PMCID: PMC81095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Affiliation(s)
- D Farquhar
- Division of Internal Medicine, Queen's University, Kingston, Ont
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Affiliation(s)
- D Farquhar
- Division of General Internal Medicine, Queen's University, Kingston, Canada.
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Farquhar D. ASA or low-molecular-weight heparin in the initial management of acute ischemic stroke complicating atrial fibrillation? CMAJ 2001; 164:396. [PMID: 11232150 PMCID: PMC80756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Affiliation(s)
- D Farquhar
- Division of Internal Medicine, Queen's University, Kingston, Ont
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Cameron S, McKenzie F, Warnock L, Farquhar D. Impact of a nurse led multidisciplinary team on an acute medical admissions unit. Health Bull (Edinb) 2000; 58:512-4. [PMID: 12813785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
OBJECTIVE To determine the impact of a nurse-led multi-disciplinary team on management of elderly patients with functional problems admitted to an acute medical admission unit. DESIGN Data collection from the first 16 months of the team's operation. SETTING A district general hospital, Scotland. SUBJECTS All elderly patients with functional problems who were considered fit for immediate multi-disciplinary assessment. RESULTS Over 1000 patients were assessed during the first 16 months. Twenty four per cent of these frail individuals were discharged directly home, of whom, almost half had some form of ongoing support. The remaining 76% were transferred for ongoing care to other wards in the Medical Directorate. Of this group, 49% moved to general medicine, 43% to geriatric assessment and 8% to the Stroke Unit. The team were perceived to improve the appropriateness of these transfers by enabling staff to review both the medical and functional needs of elderly patients when deciding on the best setting for ongoing care. CONCLUSIONS Immediate multi-disciplinary assessment of elderly patients admitted to a medical admissions unit enables the early supported discharge of a proportion of elderly and enhances the ability of the hospital to place appropriately those patients requiring a longer stay.
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Farquhar D. Use of a critical pathway for the management of community-acquired pneumonia: the CAPITAL Study. CMAJ 2000; 163:755. [PMID: 11022594 PMCID: PMC80189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
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Farquhar D. E. coli, antibiotics and hemolytic-uremic syndrome in children. CMAJ 2000; 163:438. [PMID: 10976267 PMCID: PMC80394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
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Farquhar D. Inhaled corticosteroids and COPD. CMAJ 2000; 163:326-7. [PMID: 10951737 PMCID: PMC80333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
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Bakina E, Farquhar D. Intensely cytotoxic anthracycline prodrugs: galactosides. Anticancer Drug Des 1999; 14:507-15. [PMID: 10834272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
We have reported the synthesis of a series of anthracycline analog prodrugs that give rise to intensely cytotoxic metabolites in the presence of carboxylate esterases and beta-glucuronidases. We now report structurally related prodrugs that are converted to similar potent metabolites in the presence of beta-galactosidases. The prototypical compound, N-[(4"RS)-4"-ethoxy-4"(1'"-O-beta-D-galactopyranosyl)butyl]daunorubicin, 8a, was prepared by reductive condensation of daunomycin with 1-O-[(1'RS)-1'-ethoxy-4'-oxobutyl]-2, 3, 4, 6-tetra-O-acetyl-beta-D-galactopyranoside in the presence of sodium cyanoborohydride, followed by deacetylation of the galactoside moiety with sodium methoxide. A related prodrug (8b) with enhanced lipophilicity (the 4'-hexoxy analog of 8a) and 8c (the propyldaunomycin analog of 8a) were prepared for comparative studies. 8a and 8b were isolated after chromatography on silica as a mixture of 4'R and 4'S diastereomers; 8c, on the other hand, was resolved into its component 3' diastereomers, 8c(R) and 8c(S). 8a, 8c(R) and 8c(S) showed no evidence of decomposition when incubated at 37 degrees C in 0.05 M phosphate buffer, pH 7.4, for 2 weeks; 8b, under the same conditions, was degraded with a half-life of 49 h. In the presence of two units of Escherichia coli beta-galactosidase per pmol of substrate, the half-lives of 8a, 8b, 8c(R) and 8c(S) were 1.98, 1.06, 3.5 and 2.4 h, respectively. HPLC analysis of the incubation mixtures showed that 8a and 8b gave rise to a single, chromatographically identical metabolite. 8c(R) and 8c(S) also gave rise to a single, identical metabolite. 8a and 8b were nearly one million-fold more toxic to human A375 melanoma cells in culture in the presence of E. coli beta-galactosidase than in the absence of the enzyme. The activation products of 8c(R) and 8c(S) were approximately 1000-fold less potent. These beta-galactoside prodrugs have chemotherapeutic potential for use in conjunction with tissue-targeting strategies such as antibody-directed enzyme prodrug therapy (ADEPT) and gene-directed enzyme prodrug therapy (GDEPT).
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Affiliation(s)
- E Bakina
- Department of Clinical Investigation, The University of Texas MD Anderson Cancer Center, Houston 77030, USA
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Affiliation(s)
- D Farquhar
- Division of General Internal Medicine, Queen's University, Kingston, ON, Canada.
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Pattison R, Corr J, Ogilvie M, Farquhar D, Sutherland D, Davidson HIM, Richardson RA. Reliability of a qualitative screening tool versus physical measurements in identifying undernutrition in an elderly population. J Hum Nutr Diet 1999. [DOI: 10.1046/j.1365-277x.1999.00150.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
N-(5,5-Diacetoxypent-1-yl)doxorubicin (1b) is an intensely cytotoxic doxorubicin analogue that retains full potency against tumor cells that express elevated levels of P-glycoprotein and are resistant to doxorubicin. 1b was designed to be hydrolyzed in the presence of carboxylate esterases to N-(5-oxypent-1-yl)doxorubicin, an aldehyde capable of existing in equilibrium with a cyclic carbinolamine. To investigate the structural determinants of potency for 1b, we have prepared a series of chemically related compounds in which various omega-[bis(acetoxy)]alkyl or omega-[bis(acetoxy)]alkoxyalkyl groups are substituted at the 3'-amino position of the daunosamine sugar. These groups were selected to assess the effect of chain length, oxygen substitution, and carbinolamine ring size on analogue potency. The compounds were evaluated for their ability to inhibit the in vitro growth of the following cell lines: (a) Chinese hamster ovary (CHO) cells, (b) a CHO cell mutant 100-fold resistant to doxorubicin that expresses elevated levels of P-glycoprotein, (c) a murine ductal cell pancreatic adenocarcinoma (Panc 02), and (d) a murine mammary carcinoma (CA 755). The most potent members of the series were those that could form a straight chain aldehyde intermediate after esterase-mediated hydrolysis of the omega-bis(acetoxy) groups and give rise to 5- or 6-membered ring carbinolamines. Analogues capable of forming 7-, 8-, or 9-membered carbinolamines were markedly less active. The N-methyl derivative of 1b, which cannot give rise to a cyclic carbinolamine, was 2 orders of magnitude less potent than 1b. A branched chain analogue, 1f, which contained a tertiary carbon atom adjacent to the omega-bis(acetoxy) groups, was also substantially less active than its nonbranched counterpart, 1a. These findings suggest that the chain length of the 3'-amino substituents and the ability of the derived aldehydes to form 5- or 6-membered carbinolamines are critical determinants of biologic potency.
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Affiliation(s)
- D Farquhar
- Department of Clinical Investigation, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA
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Abstract
We previously reported the synthesis of a series of doxorubicin analogue prodrugs that give rise to intensely cytotoxic metabolites in the presence of carboxylate esterases. We now report studies on structurally related beta-glucuronide prodrugs that are converted to similar potent metabolites in the presence of beta-glucuronidases. These prodrugs were prepared by reductive condensation of daunomycin or doxorubicin with methyl 1-O-[(1'RS)-1'-ethoxy-4'-oxobutyl]-2,3,4-tri-O-acetyl-beta-D- glucopyranosyluronate in the presence of sodium cyanoborohydride followed by base-mediated cleavage of the glucuronate protective groups. The doxorubicin derivatives were isolated in very low yield, most likely because of the inherent base lability of the parent aglycone. By contrast, fairly good yields of the more base-stable daunomycin analogues were obtained. The target daunomycin glucuronide, N-[(4"RS)-4"-ethoxy-4"-(sodium 1"'-O-beta-D-glucopyranuronate)butyl]daunorubicin (6a), had a half-life of 30 h when incubated at a concentration of 12 microM in aqueous 0.05 M phosphate buffer, pH 7.4, at 37 degrees C. Under identical conditions in the presence of 197 units/mumol of Escherichia coli beta-glucuronidase, 6a was hydrolyzed with a half-life of 1.7 h. The single metabolite observed was chromatographically identical with that formed from the hydrolysis of N-(4,4-diacetoxybut-1-yl)daunomycin by carboxylate esterases. 6a was approximately 10,000-fold more toxic to human A375 melanoma cells in the presence of E. coli beta-glucuronidase than in the absence of the enzyme. These findings indicate the therapeutic potential of anthracycline glucuronide prodrugs as independent entities or four use in conjunction with enzyme tissue-targeting strategies such as antibody-directed enzyme prodrug therapy (ADEPT) or gene-directed enzyme prodrug therapy (GDEPT).
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Affiliation(s)
- E Bakina
- Department of Clinical Investigation, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA
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Uribe-Luna S, Quintana-Hau JD, Maldonado-Rodriguez R, Espinosa-Lara M, Beattie KL, Farquhar D, Nelson JA. Mutagenic consequences of the incorporation of 6-thioguanine into DNA. Biochem Pharmacol 1997; 54:419-24. [PMID: 9278101 DOI: 10.1016/s0006-2952(97)00200-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
6-Thioguanine (S6G) has been used in the treatment of acute leukemias because of its cytotoxic effect on proliferating leukemic cells. The cytotoxicity of S6G is thought to derive from its incorporation into DNA in place of guanine. The deoxyribonucleoside triphosphate of S6G, SdGTP, is a good substrate for bacterial and human DNA polymerases (Ling et al., Mol Pharmacol 40: 508-514, 1991). Since SdGTP was observed to misincorporate in place of adenine at a greater frequency than did dGTP, it appeared plausible that this analog could produce more subtle effects (mutations) due to mispairing with thymine. To assess whether such mutations occur, SdGTP was incorporated into the lacI gene of phage M13lacISaXb in reactions that omitted dGTP (-G) or dATP (-A). LacI mutation frequency was determined by beta-galactosidase colorimetric staining (inactivation of the lac repressor results in blue plaques in the absence of inducer). When a high concentration of SdGTP (24 microM) was used in the DNA polymerase reaction, phage infectivity was inhibited. When a relatively low concentration (2.4 nM) was added to the -G and -A reactions, mutagenic effects were observed. DNA sequencing of mutant progeny arising from the -G + S6G reaction revealed C-to-T base transitions and some C-to-A transversions. Similarly, the presence of SdGTP in the -A reactions led to mutants with T-to-C transitions. No insertions or deletions were observed. These data indicate that mispairing of S6G with thymine leads to mutagenic effects in this assay.
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Affiliation(s)
- S Uribe-Luna
- Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, U.S.A
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Abstract
Penclomedine (PEN) is a synthetic pyridine derivative that has been selected for clinical development based on its activity against human and mouse breast tumors implanted in mice. Its mechanism of action was unclear, and we were interested in determining its mechanism of cytotoxicity in vitro and in vivo. We found chromosome breaks, gaps, and exchanges in P388 ascites cells from BD2F1 mice treated with 200 mg/kg PEN. Maximal observed damage occurred 24 hr after drug administration. Alkaline elution indicated only limited DNA strand breaks and interstrand cross-linking. In vitro, PEN (75 micrograms/mL) inhibited RNA and DNA syntheses almost completely. In addition, incubation of [14C]PEN with rat liver S-9 fraction in the presence of calf thymus DNA resulted in the stable transfer of radioactivity to DNA. Addition of butylated hydroxytoluene, a free radical scavenger, to the incubation mixture inhibited the binding of drug to DNA, implicating free radicals as the ultimate reactive species. These data suggest that PEN can be metabolized to free radical, DNA-reactive products, and that its cytotoxicity is due to chromosomal damage produced by monofunctional alkylation. As an alternate mechanism, the ability of PEN to inhibit cellular dihydroorotate dehydrogenase was explored. Although PEN is an inhibitor of this enzyme in cells in vivo, in vitro, and in isolated cell sonicates, HPLC analyses of ribonucleotide triphosphate pools in P388 cells showed that all triphosphates had increased, especially UTP. Addition of uridine to the cell culture failed to prevent PEN-mediated cytotoxicity, suggesting that inhibition of de novo pyrimidine biosynthesis was not likely to be an important mechanism of action of this drug. These data suggest that PEN is activated in cells to a free radical that binds DNA.
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Affiliation(s)
- J A Benvenuto
- Department of Clinical Investigation, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA
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Pattison R, Ogilvie M, Corr J, Farquhar D, Davidson H, Richardson R. P.77 Validation of a subjective nutritional scoring system used in the elderly. Clin Nutr 1995. [DOI: 10.1016/s0261-5614(95)80226-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Farquhar D. Misconceived ideas. Can Fam Physician 1995; 41:563, 565. [PMID: 7787484 PMCID: PMC2146543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Farquhar D, Chen R, Khan S. 5'-[4-(Pivaloyloxy)-1,3,2-dioxaphosphorinan-2-yl]-2'-deoxy-5-fluorouridine: a membrane-permeating prodrug of 5-fluoro-2'-deoxyuridylic acid (FdUMP). J Med Chem 1995; 38:488-95. [PMID: 7853342 DOI: 10.1021/jm00003a012] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
5'-[4-(Pivaloyloxy)-1,3,2-dioxaphosphorinan-2-yl]-2'-deoxy-5 -fluorouridine (1c) was designed as a potential membrane-permeable prodrug of 2'-deoxy-5-fluorouridine 5'-monophosphate (FdUMP), a putative active metabolite of the antitumor drug 5-fluorouracil (FU). It was anticipated that 1c would be hydrolyzed in vivo by carboxylate esterase (E.C. 3.1.1.1) to the labile 4-hydroxy analogue 2a, which should penetrate cells by passive diffusion and ring open to the aldehyde 3a. Spontaneous elimination of acrolein from 3a would then generate the free nucleotide, FdUMP. 1c might also penetrate cells directly and undergo the same degradation sequence after hydrolysis by cellular esterases. 1c was prepared by condensing 2-hydroxy-2-oxo-4-(pivaloyloxy)-1,3,2-dioxaphosphorinane with 2'-deoxy-5-fluorouridine (FUdR) in the presence of triphenylphosphine and diethyl azodicarboxylate. 1c was moderately stable in aqueous buffers over the pH range 1-7.4 (T1/2 > 30 h). In the presence of carboxylate esterase, however, it was degraded, in a concentration-dependent manner, to FdUMP. No intermediates were detected in the incubation mixture. In mouse plasma, 1c was degraded first to FdUMP and then to FUdR. The latter is presumably formed by dephosphorylation of FdUMP by plasma 5'-nucleotidases or phosphatases. 1c and FU inhibited the growth of Chinese hamster ovary (CHO) cells in culture at a concentration of 5 x 10(-6) M. 1c was equally potent against a CHO variant that was 20-fold resistant to FU. Administered intraperitoneally for 5 consecutive days, 1c was as effective as FU at prolonging the life span of mice bearing P-388 leukemia. In the presence of 2-mercaptoehtanesulfonic acid, an acrolein scavenger, 1c was equally effective against a P-388 mutant cell line that was resistant to FU. Collectively, these data suggest that 1c acts as a membrane-permeable prodrug of FdUMP. This prodrug strategy may be generally useful for introducing dianionic phosphates and phosphonates into cells.
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Affiliation(s)
- D Farquhar
- Department of Clinical Investigation, University of Texas M.D. Anderson Cancer Center, Houston 77030
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Abstract
The 4-hydroperoxycyclophosphamide (4HC)-resistant B5-180(3) subline of the cloned KBM-7/B5 cell line was developed as a model of induced cyclophosphamide resistance in human myeloid leukemia. Based on IC90 values, this subline was approximately 20-fold resistant to 4HC. Furthermore, it was significantly cross-resistant to phosphorodiamidic mustard (PM), whose cytotoxicity is independent of aldehyde dehydrogenase (ADH). Using alkaline elution we found that the resistant line had decreased initial levels of DNA interstrand cross-links (ISCs) following 4HC but not PM treatment. The resistant cells also appeared to remove ISCs from their DNA more rapidly than the parental cells. Our data therefore suggest that 4HC resistance in the B5-180(3) subline is multifactorial; ADH is an important mediator of its resistance to ISC induction by 4HC, while a second process, which may involve an increased ability to tolerate drug-induced DNA damage, appears to be important for its resistance to both 4HC and PM. The B5-180(3) cells were also cross-resistant to gamma-radiation (approximately 1.7-fold at a surviving fraction of 0.1); if generally applicable, such effects could have important clinical implications, since pretransplant total body irradiation is a major component of the eradication of leukemic cells.
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Affiliation(s)
- B S Andersson
- Department of Hematology, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA
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Caughey P, Seaman CEA, Parry DA, Farquhar D, McLennan WJ, Prescott RJ. Weight and skeletal size: comparisons between elderly people living in the community and in sheltered housing. J Hum Nutr Diet 1994. [DOI: 10.1111/j.1365-277x.1994.tb00285.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Farquhar D, Khan S, Srivastva DN, Saunders PP. Synthesis and antitumor evaluation of bis[(pivaloyloxy)methyl] 2'-deoxy-5-fluorouridine 5'-monophosphate (FdUMP): a strategy to introduce nucleotides into cells. J Med Chem 1994; 37:3902-9. [PMID: 7966151 DOI: 10.1021/jm00049a009] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The bis[(pivaloyloxy)methyl] [PIV2] derivative of 2'-deoxy-5- fluorouridine 5'-monophosphate (FdUMP) was synthesized as a potential membrane-permeable prodrug of FdUMP. The compound was designed to enter cells by passive diffusion and to revert to FdUMP after removal of the PIV groups by hydrolytic enzymes. The most convenient preparation of PIV2FdUMP was by condensation of 2'-deoxy-5-fluorouridine (FUdR) with PIV2 phosphate in the presence of triphenylphosphine and diethyl azodicarboxylate (the Mitsunobo reagent). PIV2FdUMP was stable in the pH range 1.0-4.0 (t1/2 > 100 h). It was also fairly stable at pH 7.4 (t1/2 = 40.2 h). In 0.05 M NaOH solution, however, it was rapidly degraded (t1/2 < 2 min). In the presence of hog liver carboxylate esterases, PIV2FdUMP was converted quantitatively to the mono-[(pivaloyloxy)methyl] [PIV1] analogue PIV1FdUMP. After a 24 h incubation, only trace amounts of FdUMP (1-3%) were observed, indicating that PIV1FdUMP is a poor substrate for carboxylate esterases. In mouse plasma, PIV2FdUMP was rapidly metabolized, first to PIV1FdUMP and then to FdUMP. With continued incubation, FUdR was formed, presumably due to further catabolism of FdUMP by plasma phosphatases or 5'-nucleotidases. Since PIV1FdUMP is a poor substrate for carboxylate esterase, the cleavage of the second PIV group is most likely mediated by plasma phosphodiesterases. The rate of degradation of PIV2FdUMP in the presence of acid and alkaline phosphatase, 5'-nucleotidase, or spleen phosphodiesterase was the same as that in buffer controls, indicating that the compound is not a substrate for these nucleotide catabolizing enzymes. The concentration of PIV2FdUMP and its 3'-O-acetyl ester (PIV2 3'-O-Ac-FdUMP) required to inhibit the growth of Chinese hamster ovary (CHO) cells in vitro to less than 50 cells per colony was 5 x 10(-6) M, the same as that required for 5-fluorouracil (FU). Both nucleotide prodrugs showed the same growth-inhibitory potency against a mutant CHO cell line that was 20-fold resistant to FU (CHO/FU). Administered intraperitoneally at optimal dosage for 5 consecutive days, PIV2FdUMP and PIV2 3'-O-Ac-FdUMP were as effective as FU at prolonging the life spans of mice bearing intraperitoneally implanted P388 leukemia. Both prodrugs retained full therapeutic activity against a P388 subline resistant to FU. Collectively, these data indicate that PIV2FdUMP and PIV2 3'-O-Ac-FdUMP are effective membrane-permeable prodrugs of FdUMP.
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Affiliation(s)
- D Farquhar
- Department of Clinical Investigation, University of Texas M. D. Anderson Cancer Center, Houston 77030
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Abstract
In recent years much attention has been drawn to the use of buprenorphine (Temgesic) by heroin injectors in Glasgow and elsewhere. Glasgow has also witnessed a parallel increase in use of the benzodiazapine temazepam, often used as a 'cocktail' with buprenorphine. This paper presents new evidence that, although buprenorphine use among Glasgow drug injectors may now be declining, the use of temazepam-opioid cocktails has continued.
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Affiliation(s)
- A J Forsyth
- Addiction Research Group, (ARGUS), University of Strathclyde, Glasgow, UK
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Sastry JK, Nehete PN, Khan S, Nowak BJ, Plunkett W, Arlinghaus RB, Farquhar D. Membrane-permeable dideoxyuridine 5'-monophosphate analogue inhibits human immunodeficiency virus infection. Mol Pharmacol 1992; 41:441-5. [PMID: 1372082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023] Open
Abstract
2',3'-Dideoxyuridine (ddU) is ineffective at controlling human immunodeficiency virus type 1 (HIV-1) infection in human T cells, because it is not biotransformed to the active 5'-triphosphate. The metabolic block resides in the poor substrate affinity of ddU for cellular nucleoside kinases. This problem cannot be overcome by supplying the preformed nucleotides, because such compounds are unable to penetrate cells. To circumvent the requirement of ddU for enzymic phosphorylation, we have prepared bis(pivaloyloxymethyl) 2',3'-dideoxyuridine 5'-monophosphate (piv2 ddUMP), as a potential membrane-permeable prodrug of ddUMP, and investigated its metabolism and anti-HIV activity in two human T cell lines, one with wild-type thymidine kinase activity (MT-4) and the other deficient in thymidine kinase activity (CEM-tk-). The 5'-mono-, di-, and triphosphates of ddU were formed in both cell lines after exposure to piv2-ddUMP. In contrast, phosphorylated metabolites were not observed in cells treated with ddU or ddUMP alone. piv2-ddUMP also reduced the cytopathic effects of HIV-1 in MT-4 cells (ED50, 4.75 microM) and inhibited virus production in culture fluid (ED50, 20 microM). In addition, piv2-ddUMP protected CEM-tk- cells from HIV-1 infection, as demonstrated by inhibition of intracellular p24 antigen levels (ED50, 3 microM) and reverse transcriptase activity in culture medium (Ed50, 2.5 microM). Based on these findings, we propose that the "masked nucleotide" strategy may make available for development nucleoside analogues hitherto considered inactive because of failure to undergo biotransformation to the corresponding 5'-monophosphates. Moreover, by circumventing metabolic dependency on nucleoside kinases, the strategy may overcome acquired resistance to nucleoside analogues caused by the loss or depletion of nucleoside kinases.
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Affiliation(s)
- J K Sastry
- Department of Molecular Pathology, University of Texas M. D. Anderson Cancer Center, Houston 77030
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Huang P, Farquhar D, Plunkett W. Selective action of 2',3'-didehydro-2',3'-dideoxythymidine triphosphate on human immunodeficiency virus reverse transcriptase and human DNA polymerases. J Biol Chem 1992; 267:2817-22. [PMID: 1370834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023] Open
Abstract
This study used DNA primer extension and sequencing gel analyses to evaluate the molecular action of 2',3'-didehydro-2',3'-dideoxythymidine triphosphate (D4TTP), in comparison with 3'-azido-2',3'-dideoxythymidine triphosphate (AZTTP), on DNA strand elongation by human immunodeficiency virus reverse transcriptases (HIV-RT) and human DNA polymerases alpha (pol alpha) and epsilon (pol epsilon) purified from T-lymphoblastoid CEM cells. D4TTP was preferentially incorporated into the T sites of the elongating DNA strand by HIV-RT and terminated DNA synthesis at the incorporation sites. The DNA chain termination activity of D4TTP was equipotent to that of AZTTP. In contrast, D4TTP was a poor substrate for pol alpha and pol epsilon. The analogue was incorporated into DNA by the human enzymes about 10,000- to 20,000-fold less efficiently than by HIV-RT, whereas the incorporation of AZTTP by pol alpha and pol epsilon was not detectable by the DNA primer extension assay. Pol epsilon, an enzyme with 3'----5'-exonuclease activity, was unable to remove the incorporated 2',3'-didehydro-2',3'-dideoxythymidine monophosphate (D4TMP) from the 3'-end of the DNA strand, whereas 3'-azido-2',3'-dideoxythymidine monophosphate was excised from DNA by pol epsilon at about 20% of the rate for normal deoxynucleotide excision. The preferential incorporation of D4TTP by HIV-RT appears to be a molecular basis for the selective anti-HIV activity of D4T, whereas the inability of pol epsilon to remove D4TMP from DNA may be related to the cytotoxicity of this compound.
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Affiliation(s)
- P Huang
- Department of Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston 77030
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Zwelling LA, Altschuler E, Cherif A, Farquhar D. N-(5,5-diacetoxypentyl)doxorubicin: a novel anthracycline producing DNA interstrand cross-linking and rapid endonucleolytic cleavage in human leukemia cells. Cancer Res 1991; 51:6704-7. [PMID: 1660346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The cytotoxic and DNA-damaging effects of a novel alkylating anthracycline, N-(5,5-diacetoxypentyl)doxorubicin, were quantified in HL-60 human leukemia cells and in an intercalator-resistant daughter line, HL-60/AMSA. The new drug was cytotoxic to both lines at doses as low as 50 nM for 1 h. N-(5,5-Diacetoxypentyl)doxorubicin produced DNA interstrand cross-linking in both lines. The cross-linking appeared to increase in both lines following drug treatment, but the increase was greater in the resistant line. This appeared to be due to an underestimation of cross-linking, particularly in sensitive HL-60, secondary to time-dependent DNA fragmentation that followed drug removal. This time-dependent DNA fragmentation was probably endonucleolytic cleavage (a feature of apoptosis) as characteristic nucleosomal ladders were produced by N-(5,5-diacetoxypentyl)doxorubicin treatment in a cotemporal time-dependent fashion. This novel anthracycline is the first of a family of alkylating anthracyclines designed to be water soluble, easy to formulate, and capable of producing DNA interstrand cross-linking. Because this last characteristic has previously been associated with doxorubicin analogues of great potency and low toxicity, these newer, more readily formulated drugs may have great clinical utility.
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Affiliation(s)
- L A Zwelling
- Department of Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston 77030
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41
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Farquhar D, Nowak B, Khan S, Plunkett W. Masked nucleotides: A strategy to introduce therapeutic nucleoside 5′-phosphates into cells. Antiviral Res 1991. [DOI: 10.1016/0166-3542(91)90274-u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Doxorubicin (1) analogues 2-5, incorporating the following alkylating or latent alkylating substituents, R, on the 3'-position of the daunosamine sugar have been synthesized as potential antitumor agents: 2, R = NHCOC6H4(p)SO2F; 3, R = NHCOCH2Br; 4, R = NHCOCH2Cl; 5, R = NHCON(NO)CH2CH2Cl. These compounds were designed on the premise that alkylating anthracyclines might bind covalently to critical intracellular target macromolecules and overcome resistance to the parent agent attributable to reduced cellular drug accumulation. Growth inhibitory studies of the analogues were conducted in vitro against mouse leukemia cells (L1210 and P388) and human uterine sarcoma cells that are sensitive (MES-SA) and resistant (MES-SA/DOX) to doxorubicin. The analogues were 5-100-fold less potent than doxorubicin against the sensitive cell lines. However, they were only marginally cross-resistant with doxorubicin against MES-SA/DOX. Compounds 3 and 5 were also evaluated against a human myelocytic cell line (KBM-3) and a subline (KBM-3/DOX) resistant to doxorubicin. They were equally potent against both cell lines, indicating a complete lack of cross-resistance with doxorubicin. Alkylating anthracyclines may have potential for the treatment of tumors resistant to the parent agents.
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Affiliation(s)
- D Farquhar
- Division of Medicine, University of Texas M. D. Anderson Cancer Center, Houston 77030
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Abstract
The synthesis of aldophosphamide acetal diacetate and a number of structural analogues is described. These compounds are designed to undergo biotransformation to the corresponding aldehydes in the presence of carboxylate esterases, enzymes that are ubiquitous in mammalian tissue. Several of these aldehydes can theoretically exist in pseudoequilibrium with the 4-hydroxyoxazaphosphorine tautomers; others lack this capability. The half-lives of the acetals in 0.05 M phosphate buffer, pH 7.4, at 37 degrees C ranged from 1 to 2 days. In the presence of 2 unit equiv of porcine liver carboxylate esterase, all of the compounds were hydrolyzed with half-lives of less than 1 min. Although closely structurally related, the compounds exhibited a wide range of cytotoxicities to L1210 murine leukemia cells in vitro.
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Affiliation(s)
- Y Q Wang
- Department of Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston 77030
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44
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Fugère P, Percival-Smith RK, Lussier-Cacan S, Davignon J, Farquhar D. Cyproterone acetate/ethinyl estradiol in the treatment of acne. A comparative dose-response study of the estrogen component. Contraception 1990; 42:225-34. [PMID: 2150795 DOI: 10.1016/0010-7824(90)90106-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The investigators compared 2 mg cyproterone acetate (CPA) in combination with either 0.035 mg or 0.050 mg ethinyl estradiol (EE2) (Diane -35 versus Diane -50) in the treatment of acne. Both formulations of Diane were highly effective in improving acne, even in women who had been refractory to other types of medication. Cycle control with both formulations was excellent and adverse effects were generally mild and confined to the first two cycles of treatment. Mean plasma lipid levels increased with both treatments, yet most individual values remained within normal limits after one year of therapy while the LDL-cholesterol/HDL-cholesterol ratio was stable throughout the study period. Plasma testosterone and DHEA-S levels paralleled the decline in the clinical severity of the acne. There was no loss of clinical effectiveness with Diane -35 and it provided the advantage of a 30% decrease in the amount of estrogen.
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Affiliation(s)
- P Fugère
- Hôpital Saint-Luc, Université de Montréal, Québec, Canada
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45
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Huang P, Farquhar D, Plunkett W. Selective action of 3'-azido-3'-deoxythymidine 5'-triphosphate on viral reverse transcriptases and human DNA polymerases. J Biol Chem 1990; 265:11914-8. [PMID: 1694849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The action of 3'-azido-3'-deoxythymidine 5'-triphosphate (N3dTTP) on DNA strand elongation catalyzed by human immunodeficiency virus type 1 reverse transcriptase was evaluated in comparison with human DNA polymerase alpha and proliferating cell nuclear antigen-independent DNA polymerase delta. Sequencing gel analysis demonstrated that the human immunodeficiency virus 1 reverse transcriptase preferentially incorporated N3dTTP into the T sites of the growing DNA strands and caused chain termination in a dose-dependent manner. This effect was observed even when the N3dTTP concentration was 0.3 microM, 100-fold less than dTTP. Studies with reverse transcriptases from avian myeloblastosis virus and Moloney murine leukemia virus showed that N3dTTP was also efficiently incorporated into DNA by these enzymes and terminated DNA strand elongation. In contrast, human DNA polymerases alpha and delta did not incorporate detectable amounts of N3dTTP into the DNA and were not inhibited by 300 microM N3dTTP. The selective incorporation of the chain-terminating nucleotide by the viral reverse transcriptases appears to be a molecular basis for the positive therapeutic index of 3'-azido-3'-deoxythymidine.
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Affiliation(s)
- P Huang
- Department of Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston 77030
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46
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Huang P, Farquhar D, Plunkett W. Selective action of 3'-azido-3'-deoxythymidine 5'-triphosphate on viral reverse transcriptases and human DNA polymerases. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38487-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Andersson BS, Wang YQ, McCredie KB, Farquhar D. Suitability of a new stable acetal analogue of aldoifosphamide for purging leukemic cells from human bone marrow. Leukemia 1990; 4:435-40. [PMID: 2359343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The in vitro cytotoxic properties of acetaldoifosphamide, a new chemically stable bis-acetate analogue of aldoifosphamide that requires enzymatic activation by cellular carboxylate esterases, has been compared with that of 4-hydroperoxycyclophosphamide (4-HC). On a molar basis, acetaldoifosphamide was 8-10 times more potent than 4-HC against two different human leukemic myeloid cell lines, but only twice as potent as 4-HC against normal bone marrow granulocyte-macrophage colony-forming cells (GM-CFC). Acetaldoifosphamide retained its activity against leukemic cell lines that were highly resistant to the antileukemic drugs doxorubicin and m-AMSA. GM-CFC doubling times after exposure of bone marrow to high concentrations of acetaldoifosphamide in suspension cultures were 6-12 hours. Similar doubling times were obtained after incubation of marrow with 4-HC. Acetaldoifosphamide has a sparing effect on hematopoietic stem cells that is similar to that found for 4-HC; however, it is considerably more potent than 4-HC. Acetaldoifosphamide is different from 4-HC in its chemical stability and its unique requirement for carboxylate esterase activation. We conclude that acetaldoifosphamide may have advantages over 4-HC for in vitro purging of leukemic cells from human bone marrow.
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Affiliation(s)
- B S Andersson
- Department of Hematology, University of Texas M. D. Anderson Cancer Center, Houston 77030
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48
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Hao Z, Cooney DA, Farquhar D, Perno CF, Zhang K, Masood R, Wilson Y, Hartman NR, Balzarini J, Johns DG. Potent DNA chain termination activity and selective inhibition of human immunodeficiency virus reverse transcriptase by 2',3'-dideoxyuridine-5'-triphosphate. Mol Pharmacol 1990; 37:157-63. [PMID: 1689452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
2',3'-Dideoxyuridine (ddUrd) exhibits poor if any anti-human immunodeficiency virus (HIV) activity in ATH8 and MT-4 cells. This is in agreement with the failure of ddUrd to be efficiently anabolized intracellularly to its 5'-triphosphate metabolite. However, 2',3'-dideoxyuridine-5'-triphosphate (ddUTP) proved to be a potent and selective inhibitor of the reverse transcriptase of HIV (Ki, 0.05 microM) and avian myeloblastosis virus (Ki, 1.0 microM). Bacterial DNA polymerase I, mammalian DNA polymerase alpha, terminal deoxyribonucleotidyl transferase, and Moloney murine leukemia virus reverse transcriptase were resistant to ddUTP. ddUTP is incorporated into the growing DNA chain principally at dTTP sites and inhibits further elongation. The potential of ddUTP as an anti-HIV therapeutic agent merits further investigation. However, to achieve this goal, it will be necessary to resort to techniques capable of delivering preformed phosphorylated ddUrd to the susceptible cells.
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Affiliation(s)
- Z Hao
- Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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49
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Freed JJ, Farquhar D, Hampton A. Evidence for acyloxymethyl esters of pyrimidine 5'-deoxyribonucleotides as extracellular sources of active 5'-deoxyribonucleotides in cultured cells. Biochem Pharmacol 1989; 38:3193-8. [PMID: 2818620 DOI: 10.1016/0006-2952(89)90613-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cells commonly resist growth inhibition by purine and pyrimidine bases and nucleosides by restricting intracellular formation of the corresponding 5'-mononucleotides. Nucleotide derivatives that can act as effective membrane-transport precursors of the poorly membrane-permeable nucleotides have not been identified so far. We studied the bis(pivaloyloxymethyl)ester (I) of FdUMP (5-fluoro-dUMP) and a cyclic phosphodiester (II) of FdUMP derived from 1,3-dihydroxyl-1-C-(pivaloyloxy-methyl)propane which are active in vivo against a 5-fluoro-2'-deoxyuridine (FUdR)-resistant mouse leukemia and are attacked by carboxylic esterases under physiological conditions to produce FdUMP by elimination of formaldehyde and acrolein respectively. The assay for intracellular FdUMP was the inhibition of DNA synthesis due to inhibition of TMP synthetase in cultured mouse LM(TK-) fibroblasts genetically devoid of thymidine kinase (TK) and thus unable to convert FUdR directly to FdUMP. At 10(-6)M, I, II, or FUdR inhibited DNA synthesis in 2 hr by 99, 80, and 35% respectively; at 10(-5)M. maximal inhibition was attained after less than 15, 30 and 90 min respectively. Inhibition of DNA synthesis in TK+ cells by 10(-5) M I, II, or FUdR was reversed completely by 10(-5)M thymidine (TdR) but unaffected by 10(-5)M UdR, confirming TMP synthetase as the locus of inhibition. At 10(-5)M, bis(pivaloyloxymethyl) esters of phenyl phosphate or a p-substituted benzylphosphonic acid did not inhibit significantly DNA synthesis in TK+ cells. From this finding, and from effects produced by V (see below), we conclude that pivalic acid and CH2O arising from I contribute little to its above inhibitory effects. In TK- cells in which DNA synthesis is prevented by blockade of TMP synthetase with aminopterin, the bis(pivaloyloxymethyl) ester (V) of TMP, at 0.9 x 10(-4) M, induced a 4-fold faster rate of DNA synthesis than did 10(-3)M TMP, whereas 10(-3) M TdR did not affect the rate. After 3 hr the rate with V was 80% that in the absence of aminopterin. In the above systems the nucleotide diesters I, II and V appear to be acting as effective extracellular sources of active intracellular FdUMP and TMP, in processes that involve loss of the two esterifying groups.
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Affiliation(s)
- J J Freed
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111
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50
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Beran M, Andersson BS, Wang Y, McCredie KB, Farquhar D. The effects of acetaldophosphamide, a novel stable aldophosphamide analogue, on normal human and leukemic progenitor cells in vitro: implications for use in bone marrow purging. Cancer Res 1988; 48:339-45. [PMID: 3275495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Acetaldophosphamide (A-ALD), a novel in vitro active and stable derivative of aldophosphamide, kills human bone marrow-derived granulocyte-macrophage colony-forming cells (GM-CFC) independent of the cell cycle. The surviving fraction of GM-CFC is an exponential function of the drug concentration and time of exposure. Variation of marrow light-density cell concentration between 2 x 10(6) and 10 x 10(6)/ml does not significantly influence its GM-CFC toxicity. Marrow depleted of GM-CFC by A-ALD subsequently generates GM-CFC when grown in suspension cultures. During the early period after treatment with A-ALD the number of surviving GM-CFC (size of surviving GM-CFC compartment) does influence the speed of the GM-CFC repopulation in suspension cultures. The importance of the number of surviving GM-CFCs for the growth and maintenance of GM-CFC population in such suspension cultures diminishes with time. No significant differences are observed after 2 wk, indicating that the ancestor stem cell population and its regenerative potential responsible for in vitro hematopoiesis have not been significantly affected by the drug treatment. A-ALD-treated progenitor cells retain their ability to integrate with the previously established marrow stromal cell layer and generate GM-CFC within this layer to an extent comparable to that of untreated marrow cells. The effect of A-ALD on human hematopoiesis is comparable to that of 4-hydroperoxycyclophosphamide. Its advantage over 4-hydroperoxycyclophosphamide is a greater stability in vitro. It has sparing effect on GM-CFC ancestor cells. Its toxicity to myeloid leukemia cell line (KBM-3)-derived clonogeneic cells is higher than to the GM-CFC. It is similar in doxorubicin-sensitive (KBM-3) and -resistant (KBM-3/DOX) leukemic cells. Thus, A-ALD appears to be a promising drug for in vitro purging of bone marrow cells.
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Affiliation(s)
- M Beran
- Department of Hematology, University of Texas M.D. Anderson Hospital and Tumor Institute at Houston 77030
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