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Landes RD, Jurgensen KJ, Skinner WKJ, Spencer HJ, Cary L. Feasibility of Reducing Animal Numbers in Radiation Countermeasure Experiments from Historic Levels when using Sample Size Calculations. Radiat Res 2023; 200:107-115. [PMID: 37327124 PMCID: PMC10513753 DOI: 10.1667/rade-22-00124.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 05/22/2023] [Indexed: 06/18/2023]
Abstract
Historically, animal numbers have most often been in the hundreds for experiments designed to estimate the dose reduction factor (DRF) of a radiation countermeasure treatment compared to a control treatment. Before 2010, researchers had to rely on previous experience, both from others and their own, to determine the number of animals needed for a DRF experiment. In 2010, a formal sample size formula was developed by Kodell et al. This theoretical work showed that sample sizes for realistic, yet hypothetical, DRF experiments could be less than a hundred animals and still have sufficient power to detect clinically meaningful DRF values. However, researchers have been slow to use the formula for their DRF experiments, whether from ignorance to its existence or hesitancy to depart from "tried and true" sample sizes. Here, we adapt the sample size formula to better fit usual DRF experiments, and, importantly, we provide real experimental evidence from two independent DRF experiments that sample sizes smaller than what have typically been used can still statistically detect clinically meaningful DRF values. In addition, we update a literature review of DRF experiments which can be used to inform future DRF experiments, provide answers to questions that researchers have asked when considering sample size calculations rather than solely relying on previous experience, whether their own or others', and, in the supplementary material, provide R code implementing the formula, along with several exercises to familiarize the user with the adapted formula.
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Affiliation(s)
- Reid D. Landes
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Kimberly J. Jurgensen
- Scientific Research Department, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20889
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland 20817
| | - William K. J. Skinner
- Department of Radiation Oncology, Walter Reed National Military Medical Center, Bethesda, Maryland 20814
| | - Horace J. Spencer
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Lynnette Cary
- Scientific Research Department, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20889
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Fooladi M, Cheki M, Shirazi A, Sheikhzadeh P, Amirrashedi M, Ghahramani F, Khoobi M. Histopathological Evaluation of Protective Effect of Telmisartan against Radiation-Induced Bone Marrow Injury. J Biomed Phys Eng 2022; 12:277-284. [PMID: 35698535 PMCID: PMC9175127 DOI: 10.31661/jbpe.v0i0.2012-1243] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/20/2021] [Indexed: 06/15/2023]
Abstract
BACKGROUND Radiation-induced hematopoietic suppression and myelotoxicity can occur due to the nuclear accidents, occupational irradiation and therapeutic interventions. Bone marrow dysfunction has always been one of the most important causes of morbidity and mortality after ionizing irradiation. OBJECTIVE This study aims to investigate the protective effect of telmisartan against radiation-induced bone marrow injuries in a Balb/c mouse model. MATERIAL AND METHODS In this experimental study, male Balb/c mice were divided into four groups as follow: group 1: mice received phosphate buffered saline (PBS) without irradiation, group 2: mice received a solution of telmisartan in PBS without irradiation, group 3: mice received PBS with irradiation, and group 4: mice received a solution of telmisartan in PBS with irradiation. A solution of telmisartan was prepared and administered orally at 12 mg/kg body weight for seven consecutive days prior to whole body exposing to a single sub-lethal dose of 5 Gy X-rays. Protection of bone marrow against radiation induced damage was investigated by Hematoxylin-Eosin (HE) staining assay at 3, 9, 15 and 30 days after irradiation. RESULTS Histopathological analysis indicated that administration of telmisartan reduced X-radiation-induced damage and improved bone marrow histology. The number of different cell types in bone marrow, including polymorphonuclear /mononuclear cells and megakaryocytes significantly increased in telmisartan treated group compared to the only irradiated group at all-time points. CONCLUSION The results of the present study demonstrated an efficient radioprotective effect of telmisartan in mouse bone marrow against sub-lethal X-irradiation.
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Affiliation(s)
- Masoomeh Fooladi
- PhD Candidate, Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Cheki
- PhD, Department of Medical Imaging and Radiation Sciences, Faculty of Paramedicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Alireza Shirazi
- PhD Candidate, Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Peyman Sheikhzadeh
- PhD, Department of Nuclear Medicine, Imam khomeini Hospital complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahsa Amirrashedi
- PhD Candidate, Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- PhD Candidate, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Ghahramani
- MSc, Radiotherapy-Oncology Center, Yas Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi Khoobi
- PhD, Biomaterials Group, Pharmaceutical Sciences Research Center, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran
- PhD, Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
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3
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Wei S, Peng W, Zhang C, Su L, Zhang Z, Wang J, Huang C, Chu Z. Cordyceps sinensis aqueous extract regulates the adaptive immunity of mice subjected to 60 Co γ irradiation. Phytother Res 2021; 35:5163-5177. [PMID: 34236103 DOI: 10.1002/ptr.7186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 11/10/2022]
Abstract
Cordyceps sinensis (CS) is a traditional Chinese medicine that is known for treating various diseases, and particularly for exerting therapeutic effects in immune disorders. The adaptive immunoregulatory effects of CS aqueous extract (CSAE) on γ-irradiated mice have not been reported previously. The study aimed to evaluate the therapeutic effects of CSAE in mice immunosuppressed by irradiation. We observed that CSAE administration significantly increased body weight and spleen index, as well as the number of white blood cells, lymphocytes, and platelets in peripheral blood, T and B lymphocytes in spleen tissue, and total serum immunoglobulins in irradiated mice, whereas total serum pro-inflammatory cytokine levels were decreased. Collectively, CSAE maintained the structural integrity of spleen tissue and repaired its damage in irradiated mice as shown by hematoxylin and eosin staining, and decreased the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive splenocytes. Mechanistically, CSAE upregulated Bcl-2, and downregulated Bax and cleaved caspase-3 in spleen of irradiated mice. However, there were no significant differences in red blood cells and neutrophils in different groups. The results revealed that CSAE had protective effects against irradiation-induced immunosuppression, which was likely associated with an antiapoptotic effect and the regulation of adaptive immunity.
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Affiliation(s)
- Shanshan Wei
- School of Pharmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang, China.,Naval Medical Research Institute, Naval Medical University, Shanghai, China
| | - Weibiao Peng
- School of Pharmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang, China.,Naval Medical Research Institute, Naval Medical University, Shanghai, China
| | - Chenxi Zhang
- Institute of Translational Medicine, Shanghai University, Shanghai, China
| | - Li Su
- Institute of Translational Medicine, Shanghai University, Shanghai, China
| | - Zhenzhen Zhang
- Naval Medical Research Institute, Naval Medical University, Shanghai, China
| | - Jiachun Wang
- Naval Medical Research Institute, Naval Medical University, Shanghai, China
| | - Caiguo Huang
- Department of Biochemistry and Molecular Biology, the Faculty of Basic Medical Science, Naval Medical University, Shanghai, China
| | - Zhiyong Chu
- School of Pharmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang, China.,Naval Medical Research Institute, Naval Medical University, Shanghai, China
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4
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Singh VK, Seed TM. Repurposing Pharmaceuticals Previously Approved by Regulatory Agencies to Medically Counter Injuries Arising Either Early or Late Following Radiation Exposure. Front Pharmacol 2021; 12:624844. [PMID: 34040517 PMCID: PMC8141805 DOI: 10.3389/fphar.2021.624844] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 04/26/2021] [Indexed: 12/12/2022] Open
Abstract
The increasing risks of radiological or nuclear attacks or associated accidents have served to renew interest in developing radiation medical countermeasures. The development of prospective countermeasures and the subsequent gain of Food and Drug Administration (FDA) approval are invariably time consuming and expensive processes, especially in terms of generating essential human data. Due to the limited resources for drug development and the need for expedited drug approval, drug developers have turned, in part, to the strategy of repurposing agents for which safety and clinical data are already available. Approval of drugs that are already in clinical use for one indication and are being repurposed for another indication is inherently faster and more cost effective than for new agents that lack regulatory approval of any sort. There are four known growth factors which have been repurposed in the recent past as radiomitigators following the FDA Animal Rule: Neupogen, Neulasta, Leukine, and Nplate. These four drugs were in clinic for several decades for other indications and were repurposed. A large number of additional agents approved by various regulatory authorities for given indications are currently under investigation for dual use for acute radiation syndrome or for delayed pathological effects of acute radiation exposure. The process of drug repurposing, however, is not without its own set of challenges and limitations.
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Affiliation(s)
- Vijay K. Singh
- Division of Radioprotectants, Department of Pharmacology and Molecular Therapeutics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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5
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General principles of developing novel radioprotective agents for nuclear emergency. RADIATION MEDICINE AND PROTECTION 2020. [DOI: 10.1016/j.radmp.2020.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Han W, Liu R, Zhang X, Lv P, Li M, Wang X. The potential agents from food for preventing leukopenia induced by benzene: garlic preparations. Toxicol Mech Methods 2019; 29:702-709. [PMID: 31364917 DOI: 10.1080/15376516.2019.1650148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Leukopenia is the early clinical manifestation of benzene poisoning. The aim of our research was to evaluate the preventive effects of three kinds of garlic preparations on benzene induced leukopenia. The mouse model of Leukopenia was established with benzene orally. At the same time, mice were administrated with garlic homogenate (GH), garlic oil (GO) or diallyl trisulfide (DATS) as preventional measures. The counts of white blood cells (WBC), the organ indexes, pathological examinations, blood biochemical parameters, weight gains, and food intakes were evaluated to observe the protective effect and potential adverse events. The results demonstrated that the counts of WBC increased by 144.04%, 140.07%, and 148.34%, respectively, after intervention by GH (400 mg/kg), GO (60 mg/kg) and DATS (30 mg/kg), compared with that in the model group. The spleen and thymus indexes in the benzene model group were 44.99% and 54.04% lower than those in the blank control group, the number of spleen nodules reduced and the thymus atrophy, which were restored by three garlic preparations at different degree. The results suggested that the three preparations all could prevent the leukopenia and protect the organ injuries induced by benzene. However, the spleen index and weight gains revealed that GH and GO brought more adverse events than DATS.
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Affiliation(s)
- Wenting Han
- School of Public Health and Management, Binzhou Medical University , Yantai , China
| | - Ruogu Liu
- School of Teacher Education, Ludong University , Yantai , China
| | - Xiaoshuai Zhang
- School of Public Health and Management, Binzhou Medical University , Yantai , China
| | - Peng Lv
- School of Public Health and Management, Binzhou Medical University , Yantai , China
| | - Ming Li
- Institute of Toxicology, School of Public Health, Shandong University , Jinan , China
| | - Xujing Wang
- Institute of Toxicology, School of Public Health, Shandong University , Jinan , China
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7
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Potdar RR, Gupta S, Giebel S, Savani BN, Varadi G, Nagler A, Blamek S. Current Status and Perspectives of Irradiation-Based Conditioning Regimens for Patients with Acute Leukemia Undergoing Hematopoietic Stem Cell Transplantation. Clin Hematol Int 2019; 1:19-27. [PMID: 34595407 PMCID: PMC8432382 DOI: 10.2991/chi.d.190218.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 02/18/2019] [Indexed: 11/01/2022] Open
Abstract
Acute myeloid leukemia and acute lymphoblastic leukemia are the most common indications for allogeneic hematopoietic stem cell transplantation. Total body irradiation (TBI) is an important part of conditioning regimens. TBI-based regimens offer advantages in sanctuary sites but are associated with significant risks of early and late side effects, including pulmonary toxicity, growth retardation, and second malignancy. TBI is also associated with technical problems, such as dose heterogeneity. With evolving techniques in radiation oncology, it is possible to focus the dose to the entire skeleton while sparing the rest of the body. This technique is called total marrow irradiation (TMI). TMI is able to deliver the same or higher doses to bone marrow while reducing toxicity. With the success of TMI, we are moving toward ultra-personalized conditioning. We review the clinical role of the irradiation-based regimens currently in clinical use, emphasizing on their strengths and limitations. Novel technologies with targeted irradiation accompanied by the modern imaging techniques and increased knowledge of the disease process can help us achieve our goal of maximum response with minimum toxicity.
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Affiliation(s)
- Rashmika R Potdar
- Division of Hematology and Oncology, Department of Internal Medicine, Einstein Medical Center, Philadelphia, PA, USA
| | - Sorab Gupta
- Division of Hematology and Oncology, Department of Internal Medicine, Einstein Medical Center, Philadelphia, PA, USA
| | - Sebastian Giebel
- Department of Bone Marrow Transplantation and Onco-Hematology, Maria Sklodowska-Curie Institute-Oncology Center, Gliwice Branch, Gliwice, Poland
| | - Bipin N Savani
- Division of Hematology/Oncology, Department of Medicine, Vanderbilt University Medical Center & Veterans Affairs Medical Center, Nashville, TN, USA
| | - Gabor Varadi
- Division of Hematology and Oncology, Department of Internal Medicine, Einstein Medical Center, Philadelphia, PA, USA
| | - Arnon Nagler
- Hematology and Bone Marrow Transplantation, Chaim Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel
| | - Slawomir Blamek
- Department of Radiotherapy, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, Gliwice, Poland
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8
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CpG-oligodeoxynucleotides may be effective for preventing ionizing radiation induced pulmonary fibrosis. Toxicol Lett 2018; 292:181-189. [PMID: 29679710 DOI: 10.1016/j.toxlet.2018.04.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 03/21/2018] [Accepted: 04/10/2018] [Indexed: 11/21/2022]
Abstract
Pulmonary fibrosis is a serious adverse effect of radiotherapy for thoracic tumor, which is believed to be a process that is tightly regulated by the phenotype of the developing Th response after radiation. Here, we will investigate whether CpG-oligodeoxynucleotides (ODN) prevent radiation-induced pulmonary fibrosis by shifting the imbalance of Th1 and Th2 response and summarizes the possible mechanism. In this study, female C57BL/6 mice were chosen to preform pulmonary fibrosis model, the whole-thorax of mice was exposed to a single radiation dose of 15 Gy. When irradiated mice were administrated with CpG-ODN, forming of pulmonary fibrosis was significantly prevented. Th2-related cytokines (IL-4 and IL-13) expression decreased, Th1 related-cytokine (IFN-γ and IL-12) expression increased. Alveolar macrophage accumulation was reduced in irradiated tissue. Profibrotic cytokine TGF-β1 expression stayed at lower level. In TGF-β1-Smad-dependent pathways, TGF-β1, TβR and phosphor-Smad 2/3 were down regulated, and Smad 7 was up regulated. These suggested that CpG-ODN prevented pulmonary fibrosis after radiation. The mechanism might be associated with reduction of alveolar macrophages accumulation and profibrogenic cytokines secretion TGF-β1 through stimulating the combination of Th1-promoting and Th2-limiting responses after radiation, and finally inhibited the fibrosis-related downstream TGF-β1-Smad-dependent pathway.
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9
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Dong L, Yang Y, Lu Y, Lu C, Lv J, Jiang N, Xu Q, Gao Y, Chang Q, Liu X. Radioprotective effects of dammarane sapogenins against 60 Co-induced myelosuppression in mice. Phytother Res 2018; 32:741-749. [PMID: 29356175 DOI: 10.1002/ptr.6027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/14/2017] [Accepted: 12/14/2017] [Indexed: 12/15/2022]
Abstract
Radiotherapy frequently induces failure of hematopoietic system and leads to myelosuppression. The objective of this study was to investigate the protective effect of dammarane sapogenins (DS), the hydrolysed product of the constituent ginsenosides of Panax ginseng, which are produced by gut metabolism, on radiation-induced hematopoietic injury. Mice were exposed to 3.5 Gy 60 Co γ-rays of total body radiation at a dose rate of 1.60 Gy per minute and treated with DS or granulocyte colony-stimulating factor immediately after radiation. The general condition of the mice, the peripheral blood cell counts, multiple colony forming unit (CFU) assays of hematopoietic progenitor cells, hematopoietic stem cell counts, bone marrow histology, and spleen colony forming unit counts were then investigated. Our results indicated that administration with DS could ameliorate 60 Co-irradiation induced damage and significantly increase the number of peripheral blood cells (white blood cells and platelets), 5 types of hematopoietic progenitor cells CFU (CFU-GM, CFU-E, BFU-E, CFU-Meg, and CFU-GEMM), hematopoietic stem cell (Lin- c-kit+ Scal-1+ ) numbers, and CFUs in the spleen, as well as improved bone marrow histopathology. All together, these results confirmed the enhancement of DS on hematopoiesis.
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Affiliation(s)
- Liming Dong
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
| | - Yanyan Yang
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
- China Astronaut Research and Training Center, Beijing, 100094, China
| | - Yan Lu
- Outpatient Department of PLA 306th Hospital, Aerospace Town Branch, Beijing, 100193, China
| | - Cong Lu
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
| | - Jingwei Lv
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
| | - Ning Jiang
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
| | - Qiuxia Xu
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
| | - Yue Gao
- Beijing Institute of Radiation Medicine, Beijing, 100850, China
| | - Qi Chang
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
| | - Xinmin Liu
- Research Center for Pharmacology & Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China
- China Astronaut Research and Training Center, Beijing, 100094, China
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10
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Kurkjian CJ, Guo H, Montgomery ND, Cheng N, Yuan H, Merrill JR, Sempowski GD, Brickey WJ, Ting JPY. The Toll-Like Receptor 2/6 Agonist, FSL-1 Lipopeptide, Therapeutically Mitigates Acute Radiation Syndrome. Sci Rep 2017; 7:17355. [PMID: 29230065 PMCID: PMC5725477 DOI: 10.1038/s41598-017-17729-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/16/2017] [Indexed: 02/03/2023] Open
Abstract
Risks of radiation exposure from nuclear incidents and cancer radiotherapy are undeniable realities. These dangers urgently compel the development of agents for ameliorating radiation–induced injuries. Biologic pathways mediated by myeloid differentiation primary response gene 88 (MyD88), the common adaptor for toll–like receptor (TLR) and Interleukin–1 receptor signaling, are critical for radioprotection. Treating with agonists prior to radiation enhances survival by activating TLR signaling, whereas radiomitigating TLR–activating therapeutics given after exposure are less defined. We examine the radiomitigation capability of TLR agonists and identify one that is superior for its efficacy and reduced toxic consequences compared to other tested agonists. We demonstrate that the synthetic TLR2/6 ligand Fibroblast–stimulating lipopeptide (FSL–1) substantially prolongs survival in both male and female mice when administered 24 hours after radiation and shows MyD88–dependent function. FSL–1 treatment results in accelerated hematopoiesis in bone marrow, spleen and periphery, and augments systemic levels of hematopoiesis–stimulating factors. The ability of FSL–1 to stimulate hematopoiesis is critical, as hematopoietic dysfunction results from a range of ionizing radiation doses. The efficacy of a single FSL–1 dose for alleviating radiation injury while protecting against adverse effects reveals a viable radiation countermeasures agent.
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Affiliation(s)
- Cathryn J Kurkjian
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Hao Guo
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Nathan D Montgomery
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Ning Cheng
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA.,Oral Biology Curriculum, School of Dentistry, University of North Carolina, Chapel Hill, NC, USA
| | - Hong Yuan
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Biomedical Imaging Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joseph R Merrill
- Biomedical Imaging Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - W June Brickey
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Jenny P-Y Ting
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA. .,Department of Genetics, University of North Carolina, Chapel Hill, NC, USA.
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11
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TLR5 signaling in murine bone marrow induces hematopoietic progenitor cell proliferation and aids survival from radiation. Blood Adv 2017; 1:1796-1806. [PMID: 29296826 DOI: 10.1182/bloodadvances.2017006981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 08/19/2017] [Indexed: 12/21/2022] Open
Abstract
Administration of the bacterial protein flagellin to mice activates innate immune signaling that protects against an array of challenges, including ionizing radiation. Herein, we define the underlying mechanism for this protection. We report that flagellin treatment induces proliferation and mobilization of bone marrow cells that aid survival following irradiation. Specifically, treatment of mice or bone marrow cells ex vivo with flagellin induced Toll-like receptor 5 (TLR5)-dependent and NOD-like receptor C4-independent proliferation of Lin-Sca-1+Kit+ (LSK) cells, which includes both hematopoietic stem cells that provide long-term repopulation (LTR) and multipotent progenitor cells (MPPs) that transiently proliferate and differentiate into a range of blood cell types. TLR5 expression on bone marrow cells was necessary and sufficient for flagellin-induced LSK proliferation. Flagellin treatment stimulated LSK proliferation by inducing a 10-fold increase in type 3 MPP (MPP3) without a concomitant increase in LTR cells. Cotransfer of 5 × 103 fluorescence-activated cell sorted flagellin-induced MPP3 cells along with 1 × 105 whole bone marrow cells to lethally irradiated mice revealed that such cells predominantly repopulated the neutrophil compartment for up to 4 week, and dramatically increased the survival rate of the bone marrow transplantation procedure. Hence, we propose the administration of MPP3 cells, elicited by flagellin, as a novel approach to prevent life-threatening neutropenia that can accompany bone marrow transplant and other myeloablative therapeutic procedures.
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Xu Y, Chen Y, Liu H, Lei X, Guo J, Cao K, Liu C, Li B, Cai J, Ju J, Gao F, Yang Y. Heat-killed salmonella typhimurium (HKST) protects mice against radiation in TLR4-dependent manner. Oncotarget 2017; 8:67082-67093. [PMID: 28978017 PMCID: PMC5620157 DOI: 10.18632/oncotarget.17859] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/04/2017] [Indexed: 12/21/2022] Open
Abstract
It is urgently required to develop novel safe and effective radioprotectors to alleviate radiation damages. Recently, several toll like receptors (TLRs), including TLR2, TLR4, TLR5, TLR9, have been proved to exert protective effects against ionizing radiation. Due to different tissue-distribution and distinct functions of TLRs, we hypothesized that co-activation of multiple TLRs simultaneously may produce extensive and stronger radioprotective effects. In this study, we found the co-agonist of TLR2, TLR4 and TLR5, heat-killed salmonella typhimurium (HKST) significantly inhibited radiation-induced cell apoptosis, increased cell survival and alleviated DNA damage. HKST also prolonged animal survival and protected radiosensitive tissues against radiation damages, such as bone marrow, spleen and testis. Decrease of CD4+ and CD8+ cells were also reversed by HKST treatment. By using TLR2 and TLR4 knockout mice, we found that most of radioprotective effects of HKST were abrogated in TLR4 knock out mice. And HKST failed to inhibited cell apoptosis in TLR5 knock down cells. In conclusion, we demonstrated that HKST effectively protected cells and radiosensitive tissues against radiation injury in a TLR4 biased mechanism, suggesting HKST as a potential radioprotector with low toxicity.
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Affiliation(s)
- Yang Xu
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Yuanyuan Chen
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Hu Liu
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Xiao Lei
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Jiaming Guo
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Kun Cao
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Cong Liu
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Bailong Li
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Jianming Cai
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Jintao Ju
- Faculty of Naval Medicine, Second Military Medical University, 200433, Shanghai, P.R. China
| | - Fu Gao
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
| | - Yanyong Yang
- Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, P.R. China
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13
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Morais EA, Chame DF, Melo EM, de Carvalho Oliveira JA, de Paula ACC, Peixoto AC, da Silva Santos L, Gomes DA, Russo RC, de Goes AM. TLR 9 involvement in early protection induced by immunization with rPb27 against Paracoccidioidomycosis. Microbes Infect 2015; 18:137-47. [PMID: 26597327 DOI: 10.1016/j.micinf.2015.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/16/2015] [Accepted: 10/19/2015] [Indexed: 02/07/2023]
Abstract
Paracoccidioidomycosis is caused by fungi of the Paracoccidioides genus and constitutes the most prevalent deep mycosis in Latin America. Toll-like receptors promote immune response against infectious agents. Recently, it was reported that TLR9 is crucial for mice survival during the first 48 h of P. brasiliensis infection. In this study, we used CPG oligodeoxynucleotide motif as an adjuvant with and without rPb27 to immunize mice against Paracoccidioidomycosis. CPG adjuvant induced differential recruitment of lymphocytes in the inflammatory process and a lower recruitment of neutrophils. In addition, CPG induced the production of pro-inflammatory cytokines such as IL-1β, TNF-α, IL-6 and IL-12; increased phagocytic ability and microbicidal activity by macrophages; and induced differential production of lgG2a and lgG2b, subtypes of Ig. Knockout mice for TLR9 and IL-12 showed higher fungal loads and rates of mortality compared to control mice after 30 days of infection. The association between CPG and rPb27 induced a high level of protection against Paracoccidioidomycosis after the first 30 days of infection but not at 60 days. Our findings demonstrate that TLR 9 plays a role in the protection induced by immunization with rPb27 and confirms the importance of TLR9 in the initial protection against Paracoccidioidomycosis.
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Affiliation(s)
- Elis Araujo Morais
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Daniela Ferreira Chame
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Eliza Mathias Melo
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | - Ana Cláudia Chagas de Paula
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Andiara Cardoso Peixoto
- Laboratory of Pulmonary Immunology and Mechanics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | | | - Remo Castro Russo
- Laboratory of Pulmonary Immunology and Mechanics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Alfredo Miranda de Goes
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil.
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14
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Lin W, Yuan N, Wang Z, Cao Y, Fang Y, Li X, Xu F, Song L, Wang J, Zhang H, Yan L, Xu L, Zhang X, Zhang S, Wang J. Autophagy confers DNA damage repair pathways to protect the hematopoietic system from nuclear radiation injury. Sci Rep 2015; 5:12362. [PMID: 26197097 PMCID: PMC4508834 DOI: 10.1038/srep12362] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/26/2015] [Indexed: 12/23/2022] Open
Abstract
Autophagy is essentially a metabolic process, but its in vivo role in nuclear radioprotection remains unexplored. We observed that ex vivo autophagy activation reversed the proliferation inhibition, apoptosis, and DNA damage in irradiated hematopoietic cells. In vivo autophagy activation improved bone marrow cellularity following nuclear radiation exposure. In contrast, defective autophagy in the hematopoietic conditional mouse model worsened the hematopoietic injury, reactive oxygen species (ROS) accumulation and DNA damage caused by nuclear radiation exposure. Strikingly, in vivo defective autophagy caused an absence or reduction in regulatory proteins critical to both homologous recombination (HR) and non-homologous end joining (NHEJ) DNA damage repair pathways, as well as a failure to induce these proteins in response to nuclear radiation. In contrast, in vivo autophagy activation increased most of these proteins in hematopoietic cells. DNA damage assays confirmed the role of in vivo autophagy in the resolution of double-stranded DNA breaks in total bone marrow cells as well as bone marrow stem and progenitor cells upon whole body irradiation. Hence, autophagy protects the hematopoietic system against nuclear radiation injury by conferring and intensifying the HR and NHEJ DNA damage repair pathways and by removing ROS and inhibiting apoptosis.
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Affiliation(s)
- Weiwei Lin
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Na Yuan
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Zhen Wang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Yan Cao
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Yixuan Fang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Xin Li
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Fei Xu
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Lin Song
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Jian Wang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Han Zhang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Lili Yan
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Li Xu
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Xiaoying Zhang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Suping Zhang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
| | - Jianrong Wang
- Hematology Center of Cyrus Tang Medical Institute, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Jiangsu Key Laboratory for Stem Cell Research, Soochow University School of Medicine, Suzhou 215123, China
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15
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Ratikan JA, Micewicz ED, Xie MW, Schaue D. Radiation takes its Toll. Cancer Lett 2015; 368:238-45. [PMID: 25819030 DOI: 10.1016/j.canlet.2015.03.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 12/13/2022]
Abstract
The ability to recognize and respond to universal molecular patterns on invading microorganisms allows our immune system to stay on high alert, sensing danger to our self-integrity. Our own damaged cells and tissues in pathological situations activate similar warning systems as microbes. In this way, the body is able to mount a response that is appropriate to the danger. Toll-like receptors are at the heart of this pattern recognition system that initiates innate pro-oxidant, pro-inflammatory signaling cascades and ultimately bridges recognition of danger to adaptive immunity. The acute inflammatory lesions that are formed segue into resolution of inflammation, repair and healing or, more dysfunctionally, into chronic inflammation, autoimmunity, excessive tissue damage and carcinogenesis. Redox is at the nexus of this decision making process and is the point at which ionizing radiation initially intercepts to trigger similar responses to self-damage. In this review we discuss our current understanding of how radiation-damaged cells interact with Toll-like receptors and how the immune systems interprets these radiation-induced danger signals in the context of whole-body exposures and during local tumor irradiation.
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Affiliation(s)
- Josephine A Ratikan
- Department of Radiation Oncology, David Geffen School of Medicine, University of California at Los Angeles, CA, USA
| | - Ewa D Micewicz
- Department of Radiation Oncology, David Geffen School of Medicine, University of California at Los Angeles, CA, USA
| | - Michael W Xie
- Department of Radiation Oncology, David Geffen School of Medicine, University of California at Los Angeles, CA, USA
| | - Dörthe Schaue
- Department of Radiation Oncology, David Geffen School of Medicine, University of California at Los Angeles, CA, USA.
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16
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Xu W, Yang F, Shen X, Fan S, Liu Q, Wang D. Polysaccharide isolated from Parmelia tinctorum ameliorates ionizing irradiation-induced damage in mice. JOURNAL OF RADIATION RESEARCH 2014; 55:641-647. [PMID: 24722682 PMCID: PMC4099985 DOI: 10.1093/jrr/rrt224] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 12/19/2013] [Accepted: 12/20/2013] [Indexed: 06/03/2023]
Abstract
In this study, WPT-A, a type of water-soluble homogeneous lichen polysaccharide, was isolated and purified from Parmelia tinctorum. We investigated whether WPT-A has radioprotective effects when administered before total-body irradiation (TBI). Mice were treated with WPT-A via intraperitoneal injection (i.p.) once per day for three consecutive days prior to 7, 7.5, 8.5, 10 or 10.5-Gy TBI. Our results indicated that the survival rate was enhanced at a range of levels of TBI. The calculated dose reduction factor (DRF) was 1.2. White blood cell (WBC) counts, spleen colony forming units (CFU-S) and bone marrow nucleated cell (BMNC) counts were used to investigate the radioprotective effects of WPT-A on the hematopoietic system. The treatment groups received WPT-A at 20, 50 and 80 mg/kg b.w. doses before 6.5-Gy TBI and showed significantly higher BMNC and WBC counts compared with the radiation-only group. The groups administered 50 and 80 mg/kg b.w. WPT-A showed a significant increase in CFU-S compared with the radiation-only group. We also carried out a single cell gel electrophoresis assay to explore the radioprotective effects of WPT-A on DNA damage. The results from single-cell gel electrophoresis of peripheral blood leukocytes showed that WPT-A attenuated radiation-induced DNA damage. These results indicate a potential use for WPT-A as a radioprotector.
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Affiliation(s)
- Wenqing Xu
- Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300192, China
| | - Fujun Yang
- Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300192, China
| | - Xiu Shen
- Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300192, China
| | - Saijun Fan
- Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300192, China
| | - Qiang Liu
- Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300192, China
| | - Dezhi Wang
- Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300192, China
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17
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Zeng T, Li Y, Zhang CL, Yu LH, Zhu ZP, Zhao XL, Xie KQ. Garlic oil suppressed the hematological disorders induced by chemotherapy and radiotherapy in tumor-bearing mice. J Food Sci 2014; 78:H936-42. [PMID: 23772706 DOI: 10.1111/1750-3841.12137] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 03/24/2013] [Indexed: 12/31/2022]
Abstract
Although the anticancer effects of garlic and its products have been demonstrated by a variety of studies; however, few studies were conducted to investigate the effects of garlic on the adverse effects of chemo/radiotherapy. In order to clarify the above question and make a more comprehensive understanding of the anticancer effects of garlic, tumor xenograft mice model was established by subcutaneous injection of H22 tumor cells, and was used for the investigation of effects of garlic oil (GO) on the chemo/radiotherapy. In the chemotherapy test, tumor-bearing mice were treated with cyclophosphamide (CTX) or CTX plus GO (25 or 50 mg/kg bw) for 14 d, while the mice received a single 5 Gy total body radiation or radiation plus GO (25 or 50 mg/kg bw) in radiotherapy test. The results showed that GO did not increase the tumor inhibitory rate of CTX/radiation, which indicated that GO could not enhance the chemo/radiosensitivity of cancer cells. However, the decrease of the peripheral total white blood cells (WBCs) count induced by CTX/radiation was significantly suppressed by GO cotreatment. Furthermore, GO cotreatment significantly inhibited the decrease of the DNA contents and the micronuclei ratio of the bone marrow. Lastly, the reduction of the endogenous spleen colonies induced by CTX/radiation was significantly suppressed by GO cotreatment. These findings support the idea that GO consumption may benefit for the cancer patients receiving chemotherapy or radiotherapy.
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Affiliation(s)
- Tao Zeng
- School of Public Health, Shandong Univ., 44 Wenhua West Road, Shandong Province, Jinan City, 250012, People's Republic of China
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18
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Landes RD, Lensing SY, Kodell RL, Hauer-Jensen M. Practical advice on calculating confidence intervals for radioprotection effects and reducing animal numbers in radiation countermeasure experiments. Radiat Res 2013; 180:567-74. [PMID: 24164553 DOI: 10.1667/rr13429.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The dose of a substance that causes death in P% of a population is called an LDP, where LD stands for lethal dose. In radiation research, a common LDP of interest is the radiation dose that kills 50% of the population by a specified time, i.e., lethal dose 50 or LD50. When comparing LD50 between two populations, relative potency is the parameter of interest. In radiation research, this is commonly known as the dose reduction factor (DRF). Unfortunately, statistical inference on dose reduction factor is seldom reported. We illustrate how to calculate confidence intervals for dose reduction factor, which may then be used for statistical inference. Further, most dose reduction factor experiments use hundreds, rather than tens of animals. Through better dosing strategies and the use of a recently available sample size formula, we also show how animal numbers may be reduced while maintaining high statistical power. The illustrations center on realistic examples comparing LD50 values between a radiation countermeasure group and a radiation-only control. We also provide easy-to-use spreadsheets for sample size calculations and confidence interval calculations, as well as SAS® and R code for the latter.
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Affiliation(s)
- Reid D Landes
- a Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205; and
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