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14. Supply and Demand for Radiation Oncologists in Canada: Workforce Planning Projections from 2020 to 2040

Author

Loewen, Shaun K., primary, Ruan, Yibing, additional, David Wu, Che Hsuan, additional, Arifin, Andrew, additional, Kim, Michael, additional, Bashir, Bashir, additional, Halperin, Ross, additional, McKenzie, Michael, additional, Archambault, Jean, additional, Thompson, Robert, additional, Ringash, Jolie, additional, Brundage, Michael, additional, Brenner, Darren, additional, and Stuckless, Teri, additional

Published
2023
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18. The Impact of Parent and Family Caregiver Roles Among Canadian Radiation Oncologists

Author

Barry, Aisling, primary, Elliott, Mary, additional, Loewen, Shaun, additional, Alfieri, Joanna, additional, Bowes, David, additional, Croke, Jennifer, additional, Debenham, Brock, additional, Keyes, Mira, additional, Papadakos, Janet, additional, Quartey, Naa Kwarley, additional, Stuckless, Teri, additional, Lajkosv, Katherine, additional, Weiss, Jessica, additional, and Giuliani, Meredith, additional

Published
2022
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23. 167: A Randomized Controlled Trial of Pre-Operative Versus Post-Operative Stereotactic Radiosurgery for Patients with Surgically Resectable Brain Metastases

Author

Das, Subhadip, primary, Faruqi, Muhammad, additional, Bowden, Gregory, additional, Starreveld, Yves, additional, Kelly, John, additional, Amanie, John, additional, Fairchild, Alysa, additional, Lim, Gerald, additional, Loewen, Shaun, additional, Nordal, Robert, additional, Rowe, Lindsay, additional, Wallace, Carla, additional, and Patel, Samir, additional

Published
2022
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35. MSOR07 Presentation Time: 10:30 AM

Author

Keyes, Mira, primary, Leiter, Michael, additional, Ingledew, Paris-Ann, additional, Loewen, Shaun, additional, Dosani, Maryam, additional, and Brundage, Michale, additional

Published
2021
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37. An ancient prevertebrate [Na.sup.+]-nucleoside cotransporter (hfCNT) from the Pacific hagfish (Eptatretus stouti)

Author

Yao, Sylvia Y., Ng, Amy M., Loewen, Shaun K., Cass, Carol E., Baldwin, Stephen A., and Young, James D.

Subjects
Hagfishes -- Physiological aspects, Nucleosides -- Physiological aspects, Carrier proteins -- Research, Biological sciences
Abstract

An ancient prevertebrate [Na.sup.+]-nucleoside cotransporter (hfCNT) from the Pacific hagfish (Eptatretus stouti). Am J Physiol Cell Physiol 283: C155-C168, 2002. First published February 20, 2002; 10.1152/ajpcell.00587.2001.The human concentrative ([Na.sup.+]-linked) plasma membrane transport proteins hCNT1, hCNT2, and hCNT3 are pyrimidine nucleoside-selective (system cit), purine nucleoside-selective (system cif), or broadly selective for both pyrimidine and purine nucleosides (system cib), respectively. All have orthologs in other mammalian species and belong to a gene family (CNT) that has members in insects, nematodes, pathogenic yeast, and bacteria. Here, we report the cDNA cloning and functional characterization of a CNT family member from an ancient marine prevertebrate, the Pacific hagfish (Eptatretus stouti). This [Na.sup.+]-nucleoside symporter, designated hfCNT, is the first transport protein to be characterized in detail in hagfish and is a 683-amino acid residue protein with 13 predicted transmembrahe helical segments (TMs). hfCNT was 52, 50, and 57% identical in sequence to hCNT1, hCNT2, and hCNT3, respectively. Similarity to hCNT3 was particularly marked in the TM 4-13 region. When produced in Xenopus oocytes, hfCNT exhibited the transport properties of system cib, with uridine, thymidine, and inosine apparent [K.sub.m] values of 10-45 [micro]M. The antiviral nucleoside drugs 3'-azido-3'-deoxythymidine, 2',3'-dideoxycytidine, and 2',3'-dideoxyinosine were also transported. Simultaneous measurement of uridine evoked currents and radiolabeled uridine uptake under voltage-clamp conditions gave a [Na.sup.+]-to-uridine coupling ratio of 2:1 (cf. 2:1 for hCNT3 and 1:1 for hCNT1/2). The apparent [K.sub.50] value for [Na.sup.+] activation was > 100 mM. A 50:50 chimera between hfCNT and hCNT1 (TMs 7-13 of hfCNT replaced by those of hCNT1) exhibited hCNT1-like cation interactions, establishing that the structural determinants of cation stoichiometry and binding affinity were located within the carboxy-terminal half of the protein. The high degree of sequence similarity between hfCNT and hCNT3 may indicate functional constraints on the primary structure of the transporter and suggests that cib-type CNTs fulfill important physiological functions. Craniata; Xenopus oocyte; 3'-azido-3'-deoxythymidine; 2',3'-dideoxycytidine; 2',3'-dideoxyinosine.

Published
2002

49. Radiation Oncology Workforce Recruitment Survey of 2000–2010 Graduates: Is There a Need for Better Physician Resource Planning?

Author

Loewen, Shaun, Brundage, Michael, Tankel, Keith, Fairchild, Alysa, Trotter, Theresa, Wiebe, Ericka, Ann Ingledew, Paris, Stuckless, Teri, and Yee, Don

Subjects
education, Major Contribution / Research Article
Abstract

Purpose of the Study To survey employment and training characteristics of Canadian radiation oncology training program graduates and foreign medical graduates with Canadian radiation oncology post-graduate education or specialist certification. Methods A 38-question, web-based survey was distributed to radiation oncologists who completed specialty training between 2000–2010. Results Out of 256 radiation oncologists contacted, 148 completed the survey (58% response rate). Thirty-two respondents (22%) were foreign MD graduates. One-hundred and fifteen respondents (78%) undertook fellowship training after residency. Many Canadian MD graduates (77%) and foreign MD graduates (34%) had staff positions in Canada, while 11% of all respondents had staff positions outside Canada, and 21% did not have a commitment for staff employment. Of the 31 respondents without a staff position, 22 graduated from Canadian residency training in 2009 or 2010, and 21 had completed medical school training in Canada. Conclusions The majority of respondents were successful in securing staff positions in Canada. A sizeable proportion extended training with fellowships. New graduates may have more difficulty in finding Canadian staff positions in radiation oncology in the near future. Implications for specialty training programs and for an improved national strategy for physician resource planning are discussed.

Published
2012

50. Specific mutations in transmembrane helix 8 of human concentrative [Na.sub.+]/ nucleoside contransporter hCNT1 affect permeant selectivity and cation coupling

Author

Slugoski, Melissa D., Loewen, Shaun K., Ng, Amy M. L., Smith, Kyla M., Yao, Sylvia Y. M., Karpinski, Edward, Cass, Carol E., Baldwin, Stephen A., and Young, James D.

Subjects
Gene mutations -- Analysis, Nucleosides -- Structure, Nucleosides -- Research, Oocytes -- Research, Xenopus -- Genetic aspects, Xenopus -- Research, Cell membranes -- Research, Biological sciences, Chemistry
Abstract

Various studies are conducted to study the specific mutations observed in the transmembrane helix 8 of the human concentrative [Na.sub.+]/nucleoside contransporter hCNT1. The analysis reveals that the residues of hCNT1 exhibits uridine-protectable inhibition by p-chloromercuribenzene sulfonate, as they occupy the positions close to the nucleoside translocation pore.

Published
2007

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