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Lee JH, Ma J, Hahn SE, Cao HB, Lee M, Hong T, Lee HJ, Yeom MS, Okamoto S, Zhou HD, Matsuda M, Fishman RS. Magnetic Frustration Driven by Itinerancy in Spinel CoV 2O 4. Sci Rep 2017; 7:17129. [PMID: 29215077 PMCID: PMC5719412 DOI: 10.1038/s41598-017-17160-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 11/13/2017] [Indexed: 11/12/2022] Open
Abstract
Localized spins and itinerant electrons rarely coexist in geometrically-frustrated spinel lattices. They exhibit a complex interplay between localized spins and itinerant electrons. In this paper, we study the origin of the unusual spin structure of the spinel CoV2O4, which stands at the crossover from insulating to itinerant behavior using the first principle calculation and neutron diffraction measurement. In contrast to the expected paramagnetism, localized spins supported by enhanced exchange couplings are frustrated by the effects of delocalized electrons. This frustration produces a non-collinear spin state even without orbital orderings and may be responsible for macroscopic spin-glass behavior. Competing phases can be uncovered by external perturbations such as pressure or magnetic field, which enhances the frustration.
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Affiliation(s)
- J H Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea.
| | - J Ma
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.,Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - S E Hahn
- Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA.,Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - H B Cao
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - M Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea
| | - Tao Hong
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - H-J Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea
| | - M S Yeom
- Department of Applied Research and Network R&D, Center for Computational Science and Engineering, Division of National Supercomputing R&D, Korea Institute of Science and Technology Information (KISTI), 245 Daehak-ro, Daejeon, 34141, Republic of Korea.
| | - S Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - M Matsuda
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - R S Fishman
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
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Dhaka RS, Hahn SE, Razzoli E, Jiang R, Shi M, Harmon BN, Thaler A, Bud'ko SL, Canfield PC, Kaminski A. Unusual temperature dependence of band dispersion in Ba(Fe(1-x)Ru(x))2As2 and its consequences for antiferromagnetic ordering. Phys Rev Lett 2013; 110:067002. [PMID: 23432293 DOI: 10.1103/physrevlett.110.067002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Indexed: 06/01/2023]
Abstract
We have performed detailed studies of the temperature evolution of the electronic structure in Ba(Fe(1-x)Ru(x))(2)As(2) using angle resolved photoemission spectroscopy. Surprisingly, we find that the binding energy of both hole and electron bands changes significantly with temperature in both pure and Ru substituted samples. The hole and electron pockets are well nested at low temperature in unsubstituted (BaFe(2)As(2)) samples, which likely drives the spin density wave and resulting antiferromagnetic order. Upon warming, this nesting is degraded as the hole pocket shrinks and the electron pocket expands. Our results demonstrate that the temperature dependent nesting may play an important role in driving the antiferromagnetic-paramagnetic phase transition.
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Affiliation(s)
- R S Dhaka
- Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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Guillaume T, Robillard N, Avet-Loiseau H, Delaunay J, Harousseau JL, Hahn SE, da Cruz LA, Pereira DS, Rubinstein DB, Young DS. Human chimeric anti-CD44 antibody ARH460–16–2 binds leukemic cells and malignant plasma cells. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.14010] [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: 11/20/2022] Open
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Hahn SE, da Cruz LA, Gupta A, Mak B, Popp L, Pereira DS, Rubinstein DB, Young DS. Clinical development of huARH460–16–2: A therapeutic antibody targeting the CD44 cancer stem cell antigen on high-incidence adenocarcinomas. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.14581] [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: 11/20/2022] Open
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Hahn SE, da Cruz LA, Sayegh D, Ferry A, O’Reilly K, Pereira DS, Rubinstein DB, Findlay H, Young DS. Therapeutic monoclonal antibodies target phenotypically-differing human breast cancer. J Clin Oncol 2007. [DOI: 10.1200/jco.2007.25.18_suppl.13510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
13510 Background: CD44 (an adhesion molecule and stem cell antigen), CD59 (a complement-inhibitory molecule), MCSP (an adhesion and cell-cell interactions), and Trop-2 (EpCam a related signaling molecule) represent a group of biologically-significant cancer proteins acting through distinct mechanisms. We have described Abs with in vitro and in vivo cancer suppressive activity to this group of targets. However, their effectiveness depends on the phenotype of malignant cells; cell response should correlate with expression of its Ag, and tumor cells represent a heterogeneous group of non-synchronous cells. The present study describes the efficacy of those antibodies in breast cancer models and the prevalence of their antigen targets in a survey of human breast cancer tissues. Methods: In vivo activity of antibodies ARH460–16–2 (anti-CD44), AR36A36.11.1 (anti-CD59), AR11BD-2E11–2 (anti-MCSP), and AR47A6.4.2 (anti-Trop-2) in estrogen-dependent and hormone sensitive xenograft models of human breast cancer was examined. In addition, distribution of the antigens in breast cancer was determined by immunohistochemistry using tumor tissue arrays of breast cancer sections from distinct patients. Results: Treatment of an established breast cancer model with ARH460–16–2 resulted in 51% median tumor xenograft suppression (p<0.05), as well as increased survival in an MDA-MB-231 (breast cancer) grafted model. 63% of human breast cancer sections expressed the CD44 antigen. Treatment with anti-CD59 antibody AR36A36.11.1 resulted in 68% xenograft tumor suppression (p<0.005). AR47A6.4.2 anti-Trop-2 antibody bound to 100% of human breast cancer sections tested, and showed efficacy in the estrogen- dependent MCF-7 breast cancer model. Anti-MCSP antibody AR11BD-2E11–2 demonstrated 80% tumor growth inhibition (p<0.001), increased survival in an estrogen-dependent model of breast cancer, and was found to stain 62% of breast cancer tissues examined. Conclusions: The heterogeneity of breast cancer cell phenotypes in in vitro and in vivo studies and variable composite cellular antigen targets is the basis for the therapeutic use of multiple antibodies, each with independent mechanisms of action, and offers a rationale for combined antibody therapy in selected patients. [Table: see text]
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Affiliation(s)
| | | | - D. Sayegh
- Arius Research Inc, Toronto, ON, Canada
| | - A. Ferry
- Arius Research Inc, Toronto, ON, Canada
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Young DS, Sayegh D, Desousa-Hitzler J, Hahn SE. ARH460–16-2: a therapeutic monoclonal antibody targeting CD44 in Her2/neu negative breast cancer. J Clin Oncol 2004. [DOI: 10.1200/jco.2004.22.90140.2622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
| | - D. Sayegh
- ARIUS Research Inc., Toronto, ON, Canada
| | | | - S. E. Hahn
- ARIUS Research Inc., Toronto, ON, Canada
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Hahn SE, Yu M, Tong S, Geisterfer-Lowrance AA, Sindrey D, Lee DK. Development of an In Vitro Screening Assay for Compounds that Increase Bone Formation. J Biomol Screen 2000; 4:363-372. [PMID: 10838433 DOI: 10.1177/108705719900400611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although parathyroid hormone (PTH) has the ability to stimulate bone growth in both rats and humans, its mechanism of action is not fully understood at the molecular level. An in vitro marker that reflects the in vivo anabolic actions of PTH would facilitate the discovery of small-molecule compounds that stimulate bone growth. We therefore compared the patterns of gene expression in three cell lines treated with PTH. The levels of c-fos, collagenase, interleukin-6 (IL-6), and collagen mRNA were determined by reverse transcription-polymerase chain reaction (RT-PCR) in three osteoblast-like cell lines. The most responsive marker was c-fos, which was induced 5-10-fold after 1 h of PTH treatment in the UMR106-01 cell line. Because it is a critical early response gene in bone growth, we investigated the possibility of using c-fos stimulation as a method to screen for compounds that can stimulate bone formation. A highly sensitive, medium-throughput RT-PCR assay for c-fos mRNA expression was established using the Taqmantrade mark Detection System (Perkin Elmer, Mississauga, Ontario). Cells were treated with a series of compounds to determine the specificity of c-fos stimulation. Of the compounds tested, only PTH, prostaglandin E(2), 8-bromo-cAMP, and forskolin induced c-fos mRNA levels, indicating that this assay was specific for compounds that are known to induce cAMP and stimulate bone growth. These results indicate that a simple in vitro assay for c-fos may be a reliable method for the screening of compounds that stimulate bone growth in vivo.
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Affiliation(s)
- SE Hahn
- Department of Pharmacology, Allelix Biopharmaceuticals Inc., Mississauga, Ontario, Canada
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Pace-Asciak CR, Rounova O, Hahn SE, Diamandis EP, Goldberg DM. Wines and grape juices as modulators of platelet aggregation in healthy human subjects. Clin Chim Acta 1996; 246:163-82. [PMID: 8814965 DOI: 10.1016/0009-8981(96)06236-5] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.1] [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: 02/02/2023]
Abstract
To test the hypothesis that red wine, by virtue of its relatively high concentration of polyphenols, is more protective against atherosclerosis and coronary heart disease (CHD) than white wine, and that grape juice enriched in one of these, trans-resveratrol, may share some of these properties, studies were performed on 24 healthy males aged 26-45 years. Each consumed the following beverages for periods of 4 weeks: red wine, white wine, commercial grape juice and the same grape juice enriched with trans-resveratrol. Apart from the last beverage, 2 weeks abstinence was maintained before commencing the schedule. Blood was taken at the beginning and end of each schedule to determine plasma thromboxane B2 (TxB2) concentration and the IC50 (concentration required for 50% aggregation) for ADP and thrombin-induced platelet aggregation. White wine (P < 0.05) but not red wine increased the IC50 for ADP. Both wines increased the IC50 for thrombin (P < 0.02 and P < 0.001, respectively) and also lowered plasma TxB2 concentrations (P < 0.01 and P < 0.025, respectively). Neither grape juice altered ADP-induced aggregation or TxB2 concentrations, but the commercial juice lowered the IC50 for thrombin (P < 0.001) whereas the resveratrol-enriched juice caused a dramatic increase (P < 0.001). In vitro experiments demonstrated that the aggregation of fresh washed human platelets by ADP and thrombin was moderately reduced by both grape juices, strongly by red wine and not at all by white wine. The synthesis of TxB2 by platelets from labelled arachidonate was stimulated by commercial grape juice, slightly enhanced by resveratrol-enriched juice and strongly inhibited by red wine with white wine having little effect. Platelets from subjects consuming the commercial juice had a higher ratio of cyclo-oxygenase to lipoxygenase product formation and those consuming the resveratrol-enriched juice a lower ratio than during the control period. We conclude that trans-resveratrol can be absorbed from grape juice in biologically active quantities and in amounts that are likely to cause reduction in the risk of atherosclerosis. The failure of red wines (which have a 20-fold excess of polyphenols over white wines) to show any advantage suggests that, in vivo, ethanol is the dominant anti-aggregatory component in these beverages which are more potent than grape juices in preventing platelet aggregation in humans.
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Affiliation(s)
- C R Pace-Asciak
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
This paper reviews epidemiological investigations which have identified an inverse relationship between alcohol consumption and death from coronary heart disease: evidence from studies of mixed populations as well as of single-sex populations have, on the whole, demonstrated that this relationship is independent of sex or age. This 'cardioprotective effect' of alcohol can be explained, at least in part, by ethanol-related increases in high density lipoprotein cholesterol and reduced platelet coagulability. With certain beverages, especially red wine, phenolic compounds may provide additional protection by altering eicosanoid metabolism in favour of increased prostacyclin and decreased thromboxane synthesis, as well as antioxidant functions which prevent the peroxidation of low-density lipoprotein. Trans-resveratrol, a tri-hydroxy stilbene present in the skins of specific grape cultivars, is a constituent of certain red wines which may play a crucial role in modulating lipoprotein metabolism, eicosanoid synthesis, oxidation and coagulation. Preliminary studies using the human hepatoma cell line HepG2 are described, demonstrating that this compound has no effect upon cell viability or overall protein synthesis in these cells, and at high concentrations DNA synthesis as measured by radioactive thymidine incorporation is enhanced. Reduced intracellular concentration and secretion of apolipoprotein B have been shown to occur in response to resveratrol although a clear dose-dependency has not yet been demonstrated. The mechanisms underlying these changes as well as the effects upon the synthesis and secretion of other apolipoproteins are under active investigation in our laboratory.
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Affiliation(s)
- D M Goldberg
- Department of Clinical Biochemistry, University of Toronto, Ontario, Canada
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Abstract
The concentration of apo B is an important risk factor for atherosclerosis, and thus its reduction is associated with a reduction in CHD mortality. In order to reduce apo B concentrations effectively, we must understand how plasma apo B concentration is regulated. Apo B is synthesized, assembled, and secreted by the liver, controlling this process will reduce the number of particles that eventually enter the plasma compartment. The assembly of apo B into a VLDL particle is a complex process which occurs through several stages: peptide synthesis, translocation, accumulation of lipid, and transport through the secretory pathway. Multiple control points regulate the synthesis and secretion of apolipoproteins. Modulation of transcription, translation and intracellular degradation represent independent regulatory mechanisms. The ability of the lipoprotein to bind cotranslationally to lipid appears to be crucial to the formation of a secreted particle. This process may be regulated solely by MTP, or may be modified by the activity of the lipid-synthesizing enzymes. A great deal of evidence supports the role of TG and CE synthesis, although the relative importance of these two lipids is a source of major controversy. In summary, all the lipoprotein components can be limiting for apo B and VLDL synthesis when their availability is substantially decreased. The rate-limiting component in vivo has still not been identified. By understanding how lipoprotein synthesis and assembly are regulated, it should become possible to design new ways of altering these processes in a beneficial manner.
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Affiliation(s)
- S E Hahn
- Department of Clinical Biochemistry, University of Toronto, Banting Institute, Ontario, Canada
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Hahn SE, Parkes JG, Goldberg DM. Apolipoprotein synthesis and secretion in Hep G2 cells: effects of monensin and cycloheximide. Biochem Cell Biol 1992; 70:1339-46. [PMID: 1338570 DOI: 10.1139/o92-182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [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: 12/26/2022] Open
Abstract
Hep G2 cells were used to study the relationship between apolipoprotein synthesis and secretion, as revealed by their interaction with agents modulating these processes. Cycloheximide inhibited the secretion of both apolipoproteins (apo) AI and B, but the reduction in apo AI secretion was evident at earlier times. Monensin also inhibited secretion of apo AI and apo B, but only apo AI accumulated intracellularly. Pulse-chase studies showed that, at concentrations of monensin that had no effect on total protein synthesis, apo B synthesis was specifically inhibited. Triacylglycerol synthesis was inhibited to the same extent as apo B synthesis, but this preceded the latter inhibition and unlike apo B there was an accumulation of intracellular triglyceride. These results suggest that distinctive mechanisms modulate the synthesis and secretion of apo AI and apo B, and that apo B synthesis can be specifically inhibited by mechanisms that initially block triglyceride production.
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Affiliation(s)
- S E Hahn
- Department of Clinical Biochemistry, University of Toronto, Banting Institute, Ont., Canada
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Abstract
Fenofibrate and other fibrate derivatives are commonly used to treat hyperlipidemia. It is not yet clear how they exert their modulatory effects on plasma lipoproteins. To investigate whether these drugs act on the liver to primarily inhibit very low density lipoprotein production, we utilized the highly differentiated human hepatoma cell line, Hep G2. At concentrations greater than 15 micrograms/mL, fenofibrate caused a 30% decrease in secreted apolipoprotein B (apo B) after 4 days of treatment. Pulse-chase studies demonstrated that this was not due to inhibition of apo B synthesis. Triglyceride synthesis by fenofibrate-treated Hep G2 cells was decreased by 30%, and the amount secreted into the medium was reduced by 50%. At a low concentration of drug (5 micrograms/mL), triglyceride secretion was reduced markedly while apo B secretion remained unchanged. Thus, apo B secretion is less sensitive to fenofibrate than the synthesis and secretion of triglyceride, and may be secondary to changes in the latter. Fenofibrate has also been shown to raise plasma high density lipoprotein concentrations. We found that low concentrations of fenofibrate caused a 20-101% increase in secreted apolipoprotein AI (apo AI), and pulse-chase immunoprecipitation studies showed that this was due to an increase in apo AI synthesis. Fenofibrate was compared to clofibrate to investigate whether their relative effects on lipoprotein production in Hep G2 cells were comparable to their relative effects on plasma lipoproteins. Both fibrates decreased the secretion of apo B to the same extent, but only fenofibrate increased apo AI secretion. Fenofibrate was more effective than clofibrate in inhibiting the secretion of lipids by these cells. Thus, the known effects of fenofibrate on plasma lipoproteins can be attributed to its direct modulation of lipoprotein synthesis in the liver cell. Hep G2 cells may thus be useful in testing the relative efficacy of fibric acid derivatives in vitro.
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Affiliation(s)
- S E Hahn
- Department of Biochemistry, Hospital for Sick Children, Toronto, Ontario, Canada
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Hahn SE, Parkes JG, Goldberg DM. Enzyme-linked immunosorbent assay to measure apolipoproteins AI and B secreted by a human hepatic carcinoma cell line (Hep G2). J Clin Lab Anal 1992; 6:182-9. [PMID: 1403337 DOI: 10.1002/jcla.1860060404] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 12/26/2022] Open
Abstract
We describe an enzyme-linked immunosorbent assay (ELISA) to measure apolipoproteins AI and B secreted by Hep G2 cells and in cell homogenates. These assays utilize commercially available polyclonal antibodies, affinity-purified to improve their specificity, thereby achieving a dramatic increase in the sensitivity of the assay. These affinity-purified antibodies were also more sensitive than a series of monoclonal antibodies tested. We achieved a sensitivity of 0.4 ng in the apo AI assay, and a sensitivity of 5 ng in the apo B assay. By these methods, we measured secretion rates by Hep G2 cells of 358 +/- 41 ng/mg cell protein/hr for apo B and 137 +/- 8 ng/mg cell protein/hr for apo AI. These assays also allowed the measurement of intracellular apolipoproteins and thus can be used to facilitate investigations of human lipoprotein metabolism in cell culture systems.
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Affiliation(s)
- S E Hahn
- Department of Clinical Biochemistry, University of Toronto, Ontario, Canada
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