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Gopal RK, Vantaku VR, Panda A, Reimer B, Rath S, To TL, Fisch AS, Cetinbas M, Livneh M, Calcaterra MJ, Gigliotti BJ, Pierce KA, Clish CB, Dias-Santagata D, Sadow PM, Wirth LJ, Daniels GH, Sadreyev RI, Calvo SE, Parangi S, Mootha VK. Effectors Enabling Adaptation to Mitochondrial Complex I Loss in Hürthle Cell Carcinoma. Cancer Discov 2023; 13:1904-1921. [PMID: 37262067 PMCID: PMC10401073 DOI: 10.1158/2159-8290.cd-22-0976] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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] [Received: 09/01/2022] [Revised: 04/05/2023] [Accepted: 05/30/2023] [Indexed: 06/03/2023]
Abstract
Oncocytic (Hürthle cell) carcinoma of the thyroid (HCC) is genetically characterized by complex I mitochondrial DNA mutations and widespread chromosomal losses. Here, we utilize RNA sequencing and metabolomics to identify candidate molecular effectors activated by these genetic drivers. We find glutathione biosynthesis, amino acid metabolism, mitochondrial unfolded protein response, and lipid peroxide scavenging to be increased in HCC. A CRISPR-Cas9 knockout screen in a new HCC model reveals which pathways are key for fitness, and highlights loss of GPX4, a defense against lipid peroxides and ferroptosis, as a strong liability. Rescuing complex I redox activity with the yeast NADH dehydrogenase (NDI1) in HCC cells diminishes ferroptosis sensitivity, while inhibiting complex I in normal thyroid cells augments ferroptosis induction. Our work demonstrates unmitigated lipid peroxide stress to be an HCC vulnerability that is mechanistically coupled to the genetic loss of mitochondrial complex I activity. SIGNIFICANCE HCC harbors abundant mitochondria, mitochondrial DNA mutations, and chromosomal losses. Using a CRISPR-Cas9 screen inspired by transcriptomic and metabolomic profiling, we identify molecular effectors essential for cell fitness. We uncover lipid peroxide stress as a vulnerability coupled to mitochondrial complex I loss in HCC. See related article by Frank et al., p. 1884. This article is highlighted in the In This Issue feature, p. 1749.
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Affiliation(s)
- Raj K. Gopal
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Cancer Center, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Venkata R. Vantaku
- Harvard Medical School, Boston, Massachusetts
- Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts
| | - Apekshya Panda
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Bryn Reimer
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Sneha Rath
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Tsz-Leung To
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Adam S. Fisch
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Murat Cetinbas
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Maia Livneh
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | | | | | - Kerry A. Pierce
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Clary B. Clish
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Dora Dias-Santagata
- Harvard Medical School, Boston, Massachusetts
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Peter M. Sadow
- Cancer Center, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Lori J. Wirth
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Cancer Center, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Gilbert H. Daniels
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Cancer Center, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
- Thyroid Unit, Massachusetts General Hospital, Boston, Massachusetts
| | - Ruslan I. Sadreyev
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Sarah E. Calvo
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Sareh Parangi
- Cancer Center, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
- Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts
| | - Vamsi K. Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts
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Shonka DC, Ho A, Chintakuntlawar AV, Geiger JL, Park JC, Seetharamu N, Jasim S, Abdelhamid Ahmed AH, Bible KC, Brose MS, Cabanillas ME, Dabekaussen K, Davies L, Dias-Santagata D, Fagin JA, Faquin WC, Ghossein RA, Gopal RK, Miyauchi A, Nikiforov YE, Ringel MD, Robinson B, Ryder MM, Sherman EJ, Sadow PM, Shin JJ, Stack BC, Tuttle RM, Wirth LJ, Zafereo ME, Randolph GW. American Head and Neck Society Endocrine Surgery Section and International Thyroid Oncology Group consensus statement on mutational testing in thyroid cancer: Defining advanced thyroid cancer and its targeted treatment. Head Neck 2022; 44:1277-1300. [PMID: 35274388 DOI: 10.1002/hed.27025] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 02/23/2022] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The development of systemic treatment options leveraging the molecular landscape of advanced thyroid cancer is a burgeoning field. This is a multidisciplinary evidence-based statement on the definition of advanced thyroid cancer and its targeted systemic treatment. METHODS An expert panel was assembled, a literature review was conducted, and best practice statements were developed. The modified Delphi method was applied to assess the degree of consensus for the statements developed by the author panel. RESULTS A review of the current understanding of thyroid oncogenesis at a molecular level is presented and characteristics of advanced thyroid cancer are defined. Twenty statements in topics including the multidisciplinary management, molecular evaluation, and targeted systemic treatment of advanced thyroid cancer are provided. CONCLUSIONS With the growth in targeted treatment options for thyroid cancer, a consensus definition of advanced disease and statements regarding the utility of molecular testing and available targeted systemic therapy is warranted.
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Affiliation(s)
- David C Shonka
- Department of Otolaryngology - Head and Neck Surgery, University of Virginia, Charlottesville, Virginia, USA
| | - Alan Ho
- Department of Hematology and Medical Oncology, Solid Tumor Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | | | - Jessica L Geiger
- Department of Hematology and Medical Oncology, Cleveland Clinic Taussig Cancer Institute, Cleveland, Ohio, USA
| | - Jong C Park
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Nagashree Seetharamu
- Division of Hematology-Oncology, Donald and Barbara Zucker School of Medicine at Hofstra University, New Hyde Park, New York, USA
| | - Sina Jasim
- Division of Endocrinology, Metabolism and Lipid Research, Department of Internal Medicine, School of Medicine, Washington University in St. Louis, Saint Louis, Missouri, USA
| | - Amr H Abdelhamid Ahmed
- Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA
| | - Keith C Bible
- Division of Medical Oncology, Mayo Clinic, Rochester, Minnesota, USA
| | - Marcia S Brose
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Maria E Cabanillas
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA
| | - Kirsten Dabekaussen
- Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Louise Davies
- Department of Surgery, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Dora Dias-Santagata
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - James A Fagin
- Endocrinology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - William C Faquin
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ronald A Ghossein
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Raj K Gopal
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | - Yuri E Nikiforov
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Matthew D Ringel
- Division of Endocrinology, Diabetes, and Metabolism, The Ohio State University Medical Center, Columbus, Ohio, USA
| | - Bruce Robinson
- Northern Clinical School, Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Mabel M Ryder
- Division of Endocrinology, Diabetes, Metabolism, & Nutrition, Mayo Clinic, Rochester, Minnesota, USA
| | - Eric J Sherman
- Head and Neck Oncology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Peter M Sadow
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Jennifer J Shin
- Department of Otolaryngology - Head and Neck Surgery, Center for Surgery and Public Health, Harvard Medical School, Boston, Massachusetts, USA
| | - Brendan C Stack
- Department of Otolaryngology - Head and Neck Surgery, Southern Illinois University School of Medicine, Springfield, Illinois, USA
| | - R Michael Tuttle
- Endocrinology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Lori J Wirth
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Mark E Zafereo
- Department of Head and Neck Surgery, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA
| | - Gregory W Randolph
- Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA
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Wadehra N, Tomar R, Varma RM, Gopal RK, Singh Y, Dattagupta S, Chakraverty S. Planar Hall effect and anisotropic magnetoresistance in polar-polar interface of LaVO 3-KTaO 3 with strong spin-orbit coupling. Nat Commun 2020; 11:874. [PMID: 32054860 PMCID: PMC7018836 DOI: 10.1038/s41467-020-14689-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [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: 06/11/2019] [Accepted: 01/23/2020] [Indexed: 11/26/2022] Open
Abstract
Among the perovskite oxide family, KTaO3 (KTO) has recently attracted considerable interest as a possible system for the realization of the Rashba effect. In this work, we report a novel conducting interface by placing KTO with another insulator, LaVO3 (LVO) and report planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) measurements. This interface exhibits a signature of strong spin-orbit coupling. Our experimental observations of two fold AMR and PHE at low magnetic fields (B) is similar to those obtained for topological systems and can be intuitively understood using a phenomenological theory for a Rashba spin-split system. Our experimental data show a B2 dependence of AMR and PHE at low magnetic fields that could also be explained based on our model. At high fields (~8 T), we see a two fold to four fold transition in the AMR that could not be explained using only Rashba spin-split energy spectra. Two dimensional electron gas (2DEG) at oxide interfaces is promising in modern electronic devices. Here, Wadehra et al. realize 2DEG at a novel interface composed of LaVO3 and KTaO3, where strong spin-orbit coupling and relativistic nature of the electrons in the 2DEG, leading to anisotropic magnetoresistance and planar Hall effect.
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Affiliation(s)
- Neha Wadehra
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India
| | - Ruchi Tomar
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India
| | - Rahul Mahavir Varma
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangaluru, Karnataka, 560012, India
| | - R K Gopal
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Manauli, 140306, India
| | - Yogesh Singh
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Manauli, 140306, India
| | - Sushanta Dattagupta
- Bose Institute, P-1/12, CIT Rd, Scheme VIIM, Kankurgachi, Kolkata, West Bengal, 700054, India
| | - S Chakraverty
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India.
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Gopal RK, Kübler K, Calvo SE, Polak P, Livitz D, Rosebrock D, Sadow PM, Campbell B, Donovan SE, Amin S, Gigliotti BJ, Grabarek Z, Hess JM, Stewart C, Braunstein LZ, Arndt PF, Mordecai S, Shih AR, Chaves F, Zhan T, Lubitz CC, Kim J, Iafrate AJ, Wirth L, Parangi S, Leshchiner I, Daniels GH, Mootha VK, Dias-Santagata D, Getz G, McFadden DG. Widespread Chromosomal Losses and Mitochondrial DNA Alterations as Genetic Drivers in Hürthle Cell Carcinoma. Cancer Cell 2018; 34:242-255.e5. [PMID: 30107175 PMCID: PMC6121811 DOI: 10.1016/j.ccell.2018.06.013] [Citation(s) in RCA: 155] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 03/30/2018] [Accepted: 06/27/2018] [Indexed: 12/24/2022]
Abstract
Hürthle cell carcinoma of the thyroid (HCC) is a form of thyroid cancer recalcitrant to radioiodine therapy that exhibits an accumulation of mitochondria. We performed whole-exome sequencing on a cohort of primary, recurrent, and metastatic tumors, and identified recurrent mutations in DAXX, TP53, NRAS, NF1, CDKN1A, ARHGAP35, and the TERT promoter. Parallel analysis of mtDNA revealed recurrent homoplasmic mutations in subunits of complex I of the electron transport chain. Analysis of DNA copy-number alterations uncovered widespread loss of chromosomes culminating in near-haploid chromosomal content in a large fraction of HCC, which was maintained during metastatic spread. This work uncovers a distinct molecular origin of HCC compared with other thyroid malignancies.
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Affiliation(s)
- Raj K Gopal
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Kirsten Kübler
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Sarah E Calvo
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Paz Polak
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Dimitri Livitz
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Peter M Sadow
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Braidie Campbell
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Samuel E Donovan
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Salma Amin
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Zenon Grabarek
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Julian M Hess
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Chip Stewart
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Peter F Arndt
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Scott Mordecai
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Angela R Shih
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Frances Chaves
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Tiannan Zhan
- Institute for Technology Assessment, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Carrie C Lubitz
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA; Institute for Technology Assessment, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Jiwoong Kim
- Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - A John Iafrate
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Lori Wirth
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Sareh Parangi
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Surgery, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | | | - Gilbert H Daniels
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Thyroid Unit, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Vamsi K Mootha
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Dora Dias-Santagata
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Gad Getz
- Cancer Center, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard Medical School, Boston, MA 02115, USA.
| | - David G McFadden
- Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Thyroid Unit, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Internal Medicine, Division of Endocrinology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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5
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Singh S, Gopal RK, Sarkar J, Pandey A, Patel BG, Mitra C. Linear magnetoresistance and surface to bulk coupling in topological insulator thin films. J Phys Condens Matter 2017; 29:505601. [PMID: 29095149 DOI: 10.1088/1361-648x/aa97ba] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We explore the temperature dependent magnetoresistance of bulk insulating topological insulator thin films. Thin films of Bi2Se2Te and BiSbTeSe1.6 were grown using the pulsed laser deposition technique and subjected to transport measurements. Magnetotransport measurements indicate a non-saturating linear magnetoresistance (LMR) behavior at high magnetic field values. We present a careful analysis to explain the origin of LMR taking into consideration all the existing models of LMR. Here we consider that the bulk insulating states and the metallic surface states constitute two parallel conduction channels. Invoking this, we were able to explain linear magnetoresistance behavior as a competition between these parallel channels. We observe that the cross-over field, where LMR sets in, decreases with increasing temperature. We propose that this cross-over field can be used phenomenologically to estimate the strength of surface to bulk coupling.
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Affiliation(s)
- Sourabh Singh
- Indian Institute of Science Education and Research Kolkata, Mohanpur-741246, India
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6
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Abstract
BACKGROUND Increasing complexity of medical care, coupled with limits on resident work hours, has prompted consideration of extending Internal Medicine training. It is unclear whether further hour reductions and extension of training beyond the current duration of 3 years would be accepted by trainees. OBJECTIVE We aimed to determine if further work-hour reductions and extension of training would be accepted by trainees and whether resident burnout affects their opinions. DESIGN A postal survey was sent to all 143 Internal Medicine residents at the University of Colorado School of Medicine in May 2004. MEASUREMENTS The survey contained questions related to opinions on work-hour limits using a 5-point Likert scale ranging from strongly agree to strongly disagree. Burnout was measured using the Maslach Burnout Inventory, organized into three subscales: emotional exhaustion (EE), depersonalization (DP), and personal accomplishment, with burnout defined as high EE or DP. RESULTS Seventy-four percent (106/143) of residents returned the survey. The vast majority (84%) of residents disagreed or strongly disagreed with extending training to 4 or 5 years. Burnout residents were less averse to extending training (strongly agree or agree, 18.9% vs 4.3%, P = .04). The majority of residents (68.9%) disagreed or strongly disagreed with establishing a 60-hour/week limit. Residents who met the criteria for burnout were more likely to agree that a 60-hour limit would be better than an 80-hour limit (strongly agree or agree, 22% vs 8%, P = .02). CONCLUSIONS In this program, most Internal Medicine residents are strongly opposed to extending their training to 4 or 5 years and would prefer the current 80 hours/week cap. A longer, less intense pace of Internal Medicine training seems to be less attractive in the eyes of current trainees.
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Affiliation(s)
- R K Gopal
- Division of Ambulatory Care, Department of Internal Medicine, Denver Veterans Affairs Medical Center, Denver, CO 80220, USA.
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7
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Abstract
The aim of this study was to determine the prevalence of sickness absenteeism among the three types of agencies, government, semi-government (boards) and private (public) companies. The methodology involved eliciting retrospective data on medical leave over the year 1990 by requesting the agencies to fill up a questionnaire (Appendix I), and calculating the indices of absenteeism from this data. The results show that the private agencies scored higher for all the indices but only the "lost time" percentage was significantly increased. Females also had significantly higher severity of sickness absenteeism rates in all the agencies. Overtime work was associated with higher absenteeism indices, markedly noted in the private agencies. In conclusion, agencies showed work out their own indices of absenteeism so that it could be compared with national rates.
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Affiliation(s)
- S K Indran
- Department of Psychiatry, Faculty of Medicine, University Kebangsaan Malaysia, Kuala Lumpur, Malaysia
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Gopal RK, Garg BR, Srivastava TN, Behl PN. Clinical trial of a new topical steroid in inflammatory dermatoses. Indian J Dermatol 1966; 11:58-60. [PMID: 5930326] [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: 01/17/2023] Open
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