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Jeffery N, Granger N. New insights into the treatment of meningoencephalomyelitis of unknown origin since 2009: A review of 671 cases. Front Vet Sci 2023; 10:1114798. [PMID: 37008358 PMCID: PMC10050685 DOI: 10.3389/fvets.2023.1114798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/17/2023] [Indexed: 03/17/2023] Open
Abstract
“Meningoencephalomyelitis of unknown origin” (MUO)—a collective term for a group of clinically-indistinguishable (but pathologically distinct) autoimmune diseases of the CNS—has become increasingly commonly recognized throughout the world. In the 1960s−1980s the focus was primarily on the pathological description of these conditions and, largely anecdotally, their response to glucocorticoids. The subsequent availability of magnetic resonance imaging for companion animals led to a focus on imaging characteristics and response of MUO to various immunosuppressive medications. Previous reviews have not found clear evidence of superiority of any specific treatment regimen. Here, we review outcomes in a further 671 dogs treated with various combinations of glucocorticoids and immunosuppressive drugs and reported since 2009, aiming to determine whether recommendations can be drawn from the material published during more recent decades. We observe that: (i) there is more complete information on outcome of MUO-affected dogs solely receiving glucocorticoids and these reports provide evidence to undermine the dogma that MUO inevitably requires treatment with glucocorticoids plus an immunosuppressive drug; (ii) there is far more information on the pharmacokinetics of cytarabine delivered by a variety of routes, revealing that previous dosing and duration of administration in dogs with MUO may not have been optimal; and, (iii) there is a large number of cases that could be available for entry into multi-institutional randomized controlled trials. Finally, we suggest new research avenues that might aid future clinical trials in MUO through improved understanding of etiological triggers and individual patterns of immune response, such as the impact of the gut microbiome, the potential of CSF flow cytometry, and the establishment of robust clinical scores for evaluation of treatment success.
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Affiliation(s)
- Nick Jeffery
- Department of Small Animal Clinical Sciences, Texas A&M University, College Station, TX, United States
- *Correspondence: Nick Jeffery
| | - Nicolas Granger
- Bristol Vet Specialists, CVS Referrals & Bristol Translational Health Sciences, University of Bristol, Bristol, United Kingdom
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Levitin HA, Foss KD, Li Z, Reinhart JM, Hague DW, Fan TM. Pharmacokinetics of a cytosine arabinoside subcutaneous protocol in dogs with meningoencephalomyelitis of unknown aetiology. J Vet Pharmacol Ther 2021; 44:696-704. [PMID: 34080695 DOI: 10.1111/jvp.12980] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 10/12/2020] [Accepted: 05/03/2021] [Indexed: 11/26/2022]
Abstract
Cytosine arabinoside (CA) is a commonly used treatment for dogs with meningoencephalomyelitis of unknown aetiology (MUE) with various proposed protocols, many requiring 24 hours (h) of hospitalization or two visits within 24 h. This is a unidirectional study evaluating the pharmacokinetics of a CA subcutaneous (SC) protocol and a standard constant rate infusion (CRI) protocol in 8 dogs with MUE. Dogs received the CRI (200 mg/m2 IV over 24 h), followed by a SC protocol (50 mg/m2 every 2 h for 4 treatments) four weeks later. Plasma CA concentrations were measured by high-pressure liquid chromatography-tandem mass spectrometry (HPLC-MS). Median peak CA concentration for the SC protocol (3.40 µg/ml, range 1.60-9.70 µg/ml) was significantly higher than the CRI (1.09 µg/ml, range 0.77-1.67 µg/ml; p = .02). Median concentration at 1h and 8h following initiation of treatment was significantly higher for the SC protocol (CA1 2.28 µg/ml, range 0.97-2.67; CA8 1.83 µg/ml, range 0.77-2.84) compared to the CRI (CA1 0.01 µg/ml, range 0-0.45; CA8 0.74 µg/ml, range 0.67-1.11; p = .01). While the PK properties of CA when administered as a CRI has been previously investigated, this study demonstrated that CA when administered via repeated 50 mg/m2 injections every 2 h over an 8-h period, provided sustained plasma levels above its therapeutic target and for a significantly longer duration of time than did a standard CRI protocol.
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Affiliation(s)
- Hilary A Levitin
- The Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA
| | - Kari D Foss
- The Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA
| | - Zhong Li
- The Metabolomics Center, Roy J. Carver Biotechnology Center, University of Illinois, Urbana, Illinois, USA
| | - Jennifer M Reinhart
- The Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA
| | - Devon W Hague
- The Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA
| | - Timothy M Fan
- The Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA.,Cancer Center at Illinois, University of Illinois, Urbana, Illinois, USA
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Abstract
The pyrimidine antimetabolite drugs consist of base and nucleoside analogues of the naturally occurring pyrimidines uracil, thymine and cytosine. As is typical of antimetabolites, these drugs have a strong structural similarity to endogenous nucleic acid precursors. The structural differences are usually substitutions at one of the carbons in the pyrimidine ring itself or substitutions at on of the hydrogens attached to the ring of the pyrimidine or sugar (ribose or deoxyribose). Despite the differences noted above, these analogues, can still be taken up into cells and then metabolized via anabolic or catabolic pathways used by endogenous pyrimidines. Cytotoxicity results when the antimetabolite either is incorporated in place of the naturally occurring pyrimidine metabolite into a key molecule (such as RNA or DNA) or competes with the naturally occurring pyrimidine metabolite for a critical enzyme. There are four pyrimidine antimetabolites that are currently used extensively in clinical oncology. These include the fluoropyrimidines fluorouracil and fluorodeoxyuridine, and the cytosine analogues, cytosine arabinoside and azacytidine.
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Affiliation(s)
- G C Daher
- Department of Pharmacology, University of Alabama, Birmingham 35294
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White JC, Rathmell JP, Capizzi RL. Membrane transport influences the rate of accumulation of cytosine arabinoside in human leukemia cells. J Clin Invest 1987; 79:380-7. [PMID: 3805274 PMCID: PMC424079 DOI: 10.1172/jci112823] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The role of membrane transport in the cellular accumulation of 1-beta-D-arabinofuranosylcytosine (ara-C) was studied in freshly isolated human acute leukemia cells. Patient cells had low rates for ara-C transport as compared with human and murine experimental cells and correspondingly low binding capacities for the nucleoside transport inhibitor, nitrobenzylmercaptopurine riboside (NBMPR). At 1 microM ara-C, the rate of net cellular accumulation was close to the membrane transport rate, and NBMPR inhibited transport and accumulation to the same extent. The rate of ara-C accumulation was half maximal at only 3-5 microM, a level much lower than that required for murine cells (67-85 microM). At concentrations below 1 microM the rate of ara-C accumulation was determined primarily by the transport rate, but at higher concentrations above 10 microM, phosphorylation capacity was the principal determinant of the net uptake rate. This difference in the role of transport at high and low ara-C concentrations may explain, in part, the efficacy of high-dose ara-C in patients refractory to standard dose protocols.
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Farghali H, Novotný L, Ryba M, Beránk J, Janků I. Kinetics of transport and metabolism of 1-beta-D-arabinofuranosylcytosine and structural analogs by everted perfused rat jejunum. Biochem Pharmacol 1984; 33:655-62. [PMID: 6704182 DOI: 10.1016/0006-2952(84)90322-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Few reports have dealt with the kinetics and metabolism of AraC and analogs by rat intestine. Using everted rat jejunum with continuous perfusion, it was possible to demonstrate that AraC and Cyd cross the intestinal barrier(s) by a carrier mediated process which was saturable and exhibited fairly good fitting of the flux rate by Michaelis-Menten equation. The transport rate of different analogs was not consistent with the pH-partition theory of membrane transport of drugs being rather dependent on the chemical structure of the nucleoside. A free amino group of cytosine increased the rate of transport within the present series of AraC analogs. There was a detectable deaminase as well as esterase activity towards AraC and its analogs in rat jejunum.
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Wiley JS, Jones SP, Sawyer WH. Cytosine arabinoside transport by human leukaemic cells. EUROPEAN JOURNAL OF CANCER & CLINICAL ONCOLOGY 1983; 19:1067-1074. [PMID: 6684553 DOI: 10.1016/0277-5379(83)90029-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The membrane transport of cytosine arabinoside (araC) has been studied in blasts freshly isolated from a variety of acute leukaemias. The major fraction of araC influx was facilitated and this fraction was 80-87% at l microM araC and 68-80% at 200 microM araC. Competitive kinetics were observed between araC and deoxycytidine for entry into leukaemic blasts and, moreover, araC influx was blocked by phloretin, a broad-spectrum inhibitor of facilitated transport systems. Kinetic analysis of facilitated araC influx gave KmS which varied over a 10-fold range between patients and which were positively correlated to the Vmax. Nucleoside influx Vmax also varied over an 80-fold range between individuals, although the mean araC transport was 4-fold greater in myeloblasts than in lymphoblasts. Larger transport of araC may explain the greater sensitivity of acute myeloid leukaemia to this drug.
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Richardson VJ, Curt GA, Ryman BE. Liposomally trapped AraCTP to overcome AraC resistance in a murine lymphoma in vitro. Br J Cancer 1982; 45:559-64. [PMID: 7073946 PMCID: PMC2010996 DOI: 10.1038/bjc.1982.92] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Two cell lines, one sensitive and one resistant to the cytotoxic effects of cytosine arabinoside (AraC) were studied in vitro as a drug-resistance model. The sensitivity of these cell lines, to the effects of free and liposomally trapped AraC and AraCTP as well as empty liposomes alone and mixed with free drug, was studied. This was done by following the inhibition of [3H]-dT incorporation into cellular DNA during exposure to the various drugs and liposomes. Some of the liposomal-lipid compositions inhibited [3H]-dT incorporation at very low concentrations, which made them unsuitable for further study. Liposomes composed of a 7:2:1 molar ratio of phosphatidylcholine:cholesterol:phosphatidic acid were selected as a suitable non-inhibitory carrier. Sensitivity of the two cell lines to free AraC differed by 3 logs, when compared in the [3H]-dT-incorporation assay. The resistant cell line was studied further, and was found to be up to 2 logs more sensitive to AraCTP when given in liposomes than to either the free drug alone or mixed with empty liposomes. It appears from these studies that liposomes are able to help overcome drug resistance in this cell line in vitro.
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Harris AL, Grahame-Smith DG. Cytosine arabinoside triphosphate production in human leukaemic myeloblasts: interactions with deoxycytidine. Cancer Chemother Pharmacol 1981; 5:185-92. [PMID: 6945922 DOI: 10.1007/bf00258478] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effect of 1 mu M deoxycytidine (dC) on Ara-C conversion to Ara-CTP and on inhibition of DNA synthesis by Ara-C was measured in intact leukaemic myeloblasts. dC decreased Ara-CTP production in blasts with high Ara-C phosphorylation, but not those with low activity. The Ki for dC was similar to values found with partially purified deoxycytidine kinase. The change in Ara-CTP concentration was associated with a proportional reduction in inhibition of DNA synthesis. dC decreased the effects of Ara-C by inhibition of Ara-CTP production, rather than by production of dCTP and competition with Ara-CTP. Since low Ara-CTP production in patients' blasts is a predictor of poor therapeutic response to Ara-C, the use of dC with Ara-C may improve the therapeutic index in this group of patients.
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Mejer J. Enzymatic studies on possible improvement of cytosine arabinoside treatment. Scand J Clin Lab Invest 1981; 41:29-34. [PMID: 6942484 DOI: 10.3109/00365518109092011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Initial phosphorylation and deamination of cytosine arabinoside (Ara-C) and the natural metabolite deoxycytidine (CdR) were estimated in cell free extracts of leucocytes from patients with CML and controls, Phosphorylation of CdR had been increased while deamination of Cdr in extracts of CML cells from peripheral blood had been decreased compared with normal leucocytes. Comparing the ratios between Ara-C and CdR phosphorylation it was revealed that these were twice as high in CML cells as in normal leucocytes, whereas no difference was found when comparing ratios between Ara-C and CdR deamination. From these discoveries it is proposed that Ara-C can be combined with CdR with advantage, because apparently CdR protects the normal cells more than the malignant ones.
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Permeation of Nucleosides, Nucleic Acid Bases, and Nucleotides in Animal Cells. CARRIERS AND MEMBRANE TRANSPORT PROTEINS 1980. [DOI: 10.1016/s0070-2161(08)60118-5] [Citation(s) in RCA: 237] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Koren R, Shohami E, Yeroushalmi S. A kinetic analysis of the uptake of cytosine-beta-D-arabinoside by rat-B77 cells. Differentiation between transport and phosphorylation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1979; 95:333-9. [PMID: 222581 DOI: 10.1111/j.1432-1033.1979.tb12970.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We present here a differentiation by kinetic methods of the tandem processes of transport and metabolic during uptake of cytosine-beta-D-arabinoside by intact rat fibroblasts. Transport across the cell membrane occurs by a carrier-mediated mechanism displaying a Km of approximately 500 microM and a V of approximately pmol x min-1 x (10(6) cells)-1. The subsequent metabolic trapping (phosphorylation) has a Km of approximately 15 microM and V of approximately 0.25 pmol x min-1 x (10(6) cells)-1. In this system, transport is rate-limiting for the first phase of the uptake process whereas phosphorylation becomes rate-limiting when internal concentration of radioactive labeled substrate exceeds that in the extracellular medium. The duration of the first phase depends on the substrate concentration.
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Heichal O, Bibi O, Katz J, Cabantchik ZI. Nucleoside transport in mammalian cell membranes. III. Kinetic and chemical modification studies of cytosine-arabinoside and uridine transport in hamster cells in culture. J Membr Biol 1978; 39:133-7. [PMID: 641975 DOI: 10.1007/bf01870329] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Transport of the nucleoside analog cytosine-arabinoside (CAR) in transformed hamster cells in culture has been studied in conditions of minimal metabolic conversion. Uptake (zero-trans in) properties at 20 degrees C over a limited range of CAR concentrations were characterized by a Km of 350 micrometer and a maximal velocity (V) of 780 micrometer.min-1 (V/Km = 2.28 min-1). Equilibrium exhcange at 20 degrees C over a wider range of concentrations was best described by a saturable component with a Km of 500 micrometer and a v of 1230 micrometer.min-1 (V/Km = 2.26 min-1) and either a saturable component of high Km or a nonsaturable component of k = 0.3 min-1. For the saturable component, the v/Km values were similar in both procedures. CAR transport was inhibited by various metabolizable nucleosides. Uptake of some of these nucleosides was inhibited by CAR. CAR transport and uridine uptake were inhibited in a reversible but partially competitive fashion by high affinity probes like S-(p-nitrobenzyl-6-mercaptoinosine (NBMI) (Ki less than 0.5 nM) and in an irreversible fashion by SH reagents such as N-ethylmaleiimide (NEM). The organomercurial p-hydroxymercuribenzene sulfonate (pMBS) markedly stimulated transport of these nucleosides, but also markedly potentiated the inhibitory effects of either NBMI or NEM. The effects are interpreted either in terms of models which invoke allosteric properties or in terms of two transport systems which display distinct chemical susceptibilities to externally added probes.
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Wohlhueter RM, Marz R, Graff JC, Plagemann PG. A rapid-mixing technique to measure transport in suspended animal cells: applications to nucleoside transport in Novikoff rat hepatoma cells. Methods Cell Biol 1978; 20:211-36. [PMID: 692430 DOI: 10.1016/s0091-679x(08)62020-8] [Citation(s) in RCA: 115] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Mulder JH, Smink T, Van Putten LM. Schedule dependent effectiveness of CCNU and 5-fluorouracil in experimental chemotherapy. Eur J Cancer 1977; 13:1123-31. [PMID: 270404 DOI: 10.1016/0014-2964(77)90011-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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The role of the cell surface in the mechanism of the action of antineoplastic drugs (literature survey). Pharm Chem J 1977. [DOI: 10.1007/bf00777727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Plagemann PG, Marz R, Erbe J. Transport and countertransport of thymidine in ATP depleted and thymidine kinase-deficient Novikoff rat hepatoma and mouse L cells: evidence of a high Km facilitated diffusion system with wide nucleoside specificity. J Cell Physiol 1976; 89:1-18. [PMID: 956273 DOI: 10.1002/jcp.1040890102] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Incubation of cultured Novikoff rat hepatoma and mouse L cells in a glucose-free basal medium containing 5 mM KCN and 5 mM iodoacetate for about 10 minutes resulted in a complete depletion of the cells of ATP. ATP-depleted wild type cells or thymidine kinase-deficient sublines of Novikoff or L cells took up thymidine rapidly from the medium without concentrating it intracellularly, and exhibited countertransport of thymidine. Thus uptake was by facilitated diffusion. This transport system differs from the substrate-specific, low-Km (0.5 muM] thymidine transport system previously described for various types of cultured cells in that it exhibits an at least 100-fold higher Km and transports equally well various ribo- and deoxyribonucleosides. The results suggest that the rate-limiting step in thymidine incorporation into the nucleotide pool by wild type cells is phosphorylation rather than transport, or that the cells possess two transport systems, a facilitated diffusion system with low substrate specificity and a second system which involves substrate phosphorylation by thymidine kinase.
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Smyth JF, Robins AB, Leese CL. The metabolism of cytosine arabinoside as a predictive test for clinical response to the drug in acute myeloid leukaemia. Eur J Cancer 1976; 12:567-73. [PMID: 1066282 DOI: 10.1016/0014-2964(76)90164-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Persohn LK, Drewinko B, Loo TL. Uptake of 1-beta-D-arabinofuranosylcytosine and prednisolone by synchronized human lymphoma cells. MEDICAL AND PEDIATRIC ONCOLOGY 1976; 2:291-7. [PMID: 989884 DOI: 10.1002/mpo.2950020310] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The cytotoxicity of many antitumor agents exhibits cell-cycle phase specificity. Using a human lymphoma cell line synchronized by thymidine block, we have investigated the differential uptake of radioactive 1-beta-D-arabinofuranosylcytosine (ara-C) and prednisolone in various phases of the cycle. Uptake of ara-C is highest during early S and declines steadily throughout the rest of the cycle. In comparison, prednisolone demonstrates no significant age-dependent difference in uptake although its cytotoxicity is cell cycle sensitive.
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