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Izac JR, Kwee EJ, Tian L, Elsheikh E, Gaigalas AK, Elliott JT, Wang L. Development of a Cell-Based SARS-CoV-2 Pseudovirus Neutralization Assay Using Imaging and Flow Cytometry Analysis. Int J Mol Sci 2023; 24:12332. [PMID: 37569707 PMCID: PMC10418775 DOI: 10.3390/ijms241512332] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/13/2023] Open
Abstract
COVID-19 is an ongoing, global pandemic caused by the novel, highly infectious SARS-CoV-2 virus. Efforts to mitigate the effects of SARS-CoV-2, such as mass vaccination and development of monoclonal therapeutics, require precise measurements of correlative, functional neutralizing antibodies that block virus infection. The development of rapid, safe, and easy-to-use neutralization assays is essential for faster diagnosis and treatment. Here, we developed a vesicular stomatitis virus (VSV)-based neutralization assay with two readout methods, imaging and flow cytometry, that were capable of quantifying varying degrees of neutralization in patient serum samples. We tested two different spike-pseudoviruses and conducted a time-course assay at multiple multiplicities of infection (MOIs) to optimize the assay workflow. The results of this assay correlate with the results of previously developed serology and surrogate neutralization assays. The two pseudovirus readout methods produced similar values of 50% neutralization titer values. Harvest-free in situ readouts for live-cell imaging and high-throughput analysis results for flow cytometry can provide unique capabilities for fast evaluation of neutralization, which is critical for the mitigation of future pandemics.
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Affiliation(s)
- Jerilyn R. Izac
- Biosystems and Biomaterials Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA; (L.T.); (E.E.); (A.K.G.); (J.T.E.); (L.W.)
| | - Edward J. Kwee
- Biosystems and Biomaterials Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA; (L.T.); (E.E.); (A.K.G.); (J.T.E.); (L.W.)
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2
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Petersen EJ, Elliott JT, Gordon J, Kleinstreuer NC, Reinke E, Roesslein M, Toman B. Technical framework for enabling high quality measurements in new approach methodologies (NAMs). ALTEX 2022; 40:174-186. [PMID: 35867862 DOI: 10.14573/altex.2205081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 07/12/2022] [Indexed: 01/20/2023]
Abstract
New approach methodologies (NAMs) are in vitro, in chemico, and in silico or computational approaches that can potentially be used to reduce animal testing. For NAMs that require laboratory experiments, it is critical that they provide consistent and reliable results. While guidance has been provided on improving the reproducibility of NAMs that require laboratory experiments, there is not yet an overarching technical framework that details how to add measurement quality features into a protocol. In this manuscript, we discuss such a framework and provide a step-by-step process describing how to refine a protocol using basic quality tools. The steps in this framework include 1) conceptual analysis of sources of technical variability in the assay, 2) within-laboratory evaluation of assay performance, 3) statistical data analysis, and 4) determination of method transferability (if needed). While each of these steps has discrete components, they are all inter-related, and insights from any step can influence the others. Following the steps in this framework can help reveal the advantages and limitations of different choices during the design of an assay such as which in-process control measurements to include and how many replicates to use for each control measurement and for each test substance. Overall, the use of this technical framework can support optimizing NAM reproducibility, thereby supporting meeting research and regulatory needs.
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Affiliation(s)
- Elijah J Petersen
- National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
| | - John T Elliott
- National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
| | - John Gordon
- US Consumer Product Safety Commission, Rockville, MD, USA.
| | - Nicole C Kleinstreuer
- National Institute of Environmental Health Sciences, National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, Research Triangle Park, NC, USA
| | - Emily Reinke
- U.S. Army Public Health Center, Aberdeen Proving Ground, MD, USA
| | - Mattias Roesslein
- Empa, Swiss Federal Laboratories for Material Testing and Research, Particles-Biology Interactions Laboratory, St. Gallen, Switzerland
| | - Blaza Toman
- National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
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3
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Petersen EJ, Uhl R, Toman B, Elliott JT, Strickland J, Truax J, Gordon J. Development of a 96-Well Electrophilic Allergen Screening Assay for Skin Sensitization Using a Measurement Science Approach. Toxics 2022; 10:257. [PMID: 35622670 PMCID: PMC9147637 DOI: 10.3390/toxics10050257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/26/2022] [Accepted: 05/05/2022] [Indexed: 12/12/2022]
Abstract
The Electrophilic Allergen Screening Assay (EASA) has emerged as a promising in chemico method to detect the first key event in the adverse outcome pathway (AOP) for skin sensitization. This assay functions by assessing the depletion of one of two probe molecules (4-nitrobenzenethiol (NBT) and pyridoxylamine (PDA)) in the presence of a test compound (TC). The initial development of EASA utilized a cuvette format resulting in multiple measurement challenges such as low throughput and the inability to include adequate control measurements. In this study, we describe the redesign of EASA into a 96-well plate format that incorporates in-process control measurements to quantify key sources of variability each time the assay is run. The data from the analysis of 67 TCs using the 96-well format had 77% concordance with animal data from the local lymph node assay (LLNA), a result consistent with that for the direct peptide reactivity assay (DPRA), an OECD test guideline (442C) protein binding assay. Overall, the measurement science approach described here provides steps during assay development that can be taken to increase confidence of in chemico assays by attempting to fully characterize the sources of variability and potential biases and incorporate in-process control measurements into the assay.
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Affiliation(s)
- Elijah J. Petersen
- Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA;
| | - Richard Uhl
- Division of Laboratory Sciences, Chemistry, US Consumer Product Safety Commission (CPSC), 5 Research Place, Rockville, MD 20850, USA;
| | - Blaza Toman
- Statistical Engineering Division, Information Technology Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA;
| | - John T. Elliott
- Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD 20899, USA;
| | - Judy Strickland
- Inotiv-RTP., 601 Keystone Park Drive, Suite 800, Morrisville, NC 27560, USA; (J.S.); (J.T.)
| | - James Truax
- Inotiv-RTP., 601 Keystone Park Drive, Suite 800, Morrisville, NC 27560, USA; (J.S.); (J.T.)
| | - John Gordon
- Division of Toxicology and Risk Assessment, US Consumer Product Safety Commission (CPSC), 5 Research Place, Rockville, MD 20850, USA;
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4
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Lombard-Banek C, Pohl KI, Kwee EJ, Elliott JT, Schiel JE. A Sensitive and Controlled Data-Independent Acquisition Method for Proteomic Analysis of Cell Therapies. J Proteome Res 2022; 21:1229-1239. [PMID: 35404046 PMCID: PMC9087334 DOI: 10.1021/acs.jproteome.1c00887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Indexed: 11/29/2022]
Abstract
Mass spectrometry (MS)-based proteomic measurements are uniquely poised to impact the development of cell and gene therapies. With the adoption of rigorous instrumental performance qualifications (PQs), large-scale proteomics can move from a research to a manufacturing control tool. Especially suited, data-independent acquisition (DIA) approaches have distinctive qualities to extend multiattribute method (MAM) principles to characterize the proteome of cell therapies. Here, we describe the development of a DIA method for the sensitive identification and quantification of proteins on a Q-TOF instrument. Using the improved acquisition parameters, we defined a control strategy and highlighted some metrics to improve the reproducibility of SWATH acquisition-based proteomic measurements. Finally, we applied the method to analyze the proteome of Jurkat cells that here serves as a model for human T-cells. Raw and processed data were deposited in PRIDE (PXD029780).
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Affiliation(s)
- Camille Lombard-Banek
- National
Institute of Standards and Technology, Material and Measurements Laboratory, Gaithersburg, Maryland 20899, United States
- Institute
for Bioscience and Bioengineering Research, Rockville, Maryland 20850, United States
| | | | - Edward J. Kwee
- National
Institute of Standards and Technology, Material and Measurements Laboratory, Gaithersburg, Maryland 20899, United States
| | - John T. Elliott
- National
Institute of Standards and Technology, Material and Measurements Laboratory, Gaithersburg, Maryland 20899, United States
| | - John E. Schiel
- National
Institute of Standards and Technology, Material and Measurements Laboratory, Gaithersburg, Maryland 20899, United States
- Institute
for Bioscience and Bioengineering Research, Rockville, Maryland 20850, United States
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5
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Petersen EJ, Elliott JT, Bancos S, Caldwell B, Khajotia SS, Kleinstreuer NC, Margerrison E, Pfeifer C. Predictive alternative methods for assessing biocompatibility of dental materials: A NIST-NIDCR workshop report. ALTEX 2022; 39:522-524. [PMID: 35871505 DOI: 10.14573/altex.2206241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 06/30/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Elijah J Petersen
- Biosystems and Biomaterials Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD, United States
| | - John T Elliott
- Biosystems and Biomaterials Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD, United States
| | - Simona Bancos
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Brittany Caldwell
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Sharukh S Khajotia
- Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Nicole C Kleinstreuer
- National Institute of Environmental Health Sciences, National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, Research Triangle Park, NC, United States
| | - Edward Margerrison
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Carmem Pfeifer
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland, OR, USA
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Petersen EJ, Nguyen A, Brown J, Elliott JT, Clippinger A, Gordon J, Kleinstreuer N, Roesslein M. Characteristics to consider when selecting a positive control material for an in vitro assay. ALTEX 2021; 38:365-376. [PMID: 33637998 DOI: 10.14573/altex.2102111] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 02/18/2021] [Indexed: 11/23/2022]
Abstract
The use of in vitro assays to inform decision-making requires robust and reproducible results across studies, laboratories, and time. Experiments using positive control materials are an integral component of an assay procedure to demonstrate the extent to which the measurement system is performing as expected. This paper reviews ten characteristics that should be considered when selecting a positive control material for an in vitro assay: 1) the biological mechanism of action, 2) ease of preparation, 3) chemical purity, 4) verifiable physical properties, 5) stability, 6) ability to generate responses spanning the dynamic range of the assay, 7) technical or biological interference, 8) commercial availability, 9) user toxicity, and 10) disposability. Examples and a case study of the monocyte activation test are provided to demonstrate the application of these characteristics for identification and selection of potential positive control materials. Because specific positive control materials are often written into testing standards for in vitro assays, selection of the positive control material based on these characteristics can aid in ensuring the long-term relevance and usability of these standards.
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Affiliation(s)
- Elijah J Petersen
- Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
| | - Andrew Nguyen
- PETA Science Consortium International e.V., Stuttgart, Germany
| | - Jeffrey Brown
- PETA Science Consortium International e.V., Stuttgart, Germany
| | - John T Elliott
- Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
| | - Amy Clippinger
- PETA Science Consortium International e.V., Stuttgart, Germany
| | - John Gordon
- US Consumer Products Safety Commission (CPSC), Rockville, MD, USA
| | - Nicole Kleinstreuer
- National Institute of Environmental Health Sciences (NIEHS), National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, Research Triangle Park, NC, USA
| | - Matthias Roesslein
- Empa, Swiss Federal Laboratories for Material Testing and Research, Particles-Biology Interactions Laboratory, St. Gallen, Switzerland
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7
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Petersen EJ, Hirsch C, Elliott JT, Krug HF, Aengenheister L, Arif AT, Bogni A, Kinsner-Ovaskainen A, May S, Walser T, Wick P, Roesslein M. Cause-and-Effect Analysis as a Tool To Improve the Reproducibility of Nanobioassays: Four Case Studies. Chem Res Toxicol 2019; 33:1039-1054. [DOI: 10.1021/acs.chemrestox.9b00165] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Elijah J. Petersen
- Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Cordula Hirsch
- Particles-Biology Interactions Laboratory, Empa, Swiss Federal Laboratories for Material Science and Technology, CH-9014 St. Gallen, Switzerland
| | - John T. Elliott
- Biosystems and Biomaterials Division, Material Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States
| | - Harald F. Krug
- NanoCASE GmbH, St. Gallerstr. 58, 9032 Engelburg, Switzerland
| | - Leonie Aengenheister
- Particles-Biology Interactions Laboratory, Empa, Swiss Federal Laboratories for Material Science and Technology, CH-9014 St. Gallen, Switzerland
| | - Ali Talib Arif
- Institute for Infection Prevention and Hospital Epidemiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, D-79106 Freiburg, Germany
- Kurdistan Institution for Strategic Studies and Scientific Research (KISSR), Qirga, Sulaimani, Iraq
| | - Alessia Bogni
- European Commission, Joint Research Centre (JRC), 21027 Ispra, Italy
| | | | - Sarah May
- Particles-Biology Interactions Laboratory, Empa, Swiss Federal Laboratories for Material Science and Technology, CH-9014 St. Gallen, Switzerland
| | | | - Peter Wick
- Particles-Biology Interactions Laboratory, Empa, Swiss Federal Laboratories for Material Science and Technology, CH-9014 St. Gallen, Switzerland
| | - Matthias Roesslein
- Particles-Biology Interactions Laboratory, Empa, Swiss Federal Laboratories for Material Science and Technology, CH-9014 St. Gallen, Switzerland
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8
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Hanna SK, Bustos AM, Peterson AW, Reipa V, Scanlan LD, Coskun SH, Cho TJ, Johnson ME, Hackley VA, Nelson BC, Winchester MR, Elliott JT, Petersen EJ. Agglomeration of Escherichia coli with Positively Charged Nanoparticles Can Lead to Artifacts in a Standard Caenorhabditis elegans Toxicity Assay. Environ Sci Technol 2018; 52:5968-5978. [PMID: 29672024 PMCID: PMC6081640 DOI: 10.1021/acs.est.7b06099] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The increased use and incorporation of engineered nanoparticles (ENPs) in consumer products requires a robust assessment of their potential environmental implications. However, a lack of standardized methods for nanotoxicity testing has yielded results that are sometimes contradictory. Standard ecotoxicity assays may work appropriately for some ENPs with minimal modification but produce artifactual results for others. Therefore, understanding the robustness of assays for a range of ENPs is critical. In this study, we evaluated the performance of a standard Caenorhabditis elegans ( C. elegans) toxicity assay containing an Escherichia coli ( E. coli) food supply with silicon, polystyrene, and gold ENPs with different charged coatings and sizes. Of all the ENPs tested, only those with a positively charged coating caused growth inhibition. However, the positively charged ENPs were observed to heteroagglomerate with E. coli cells, suggesting that the ENPs impacted the ability of nematodes to feed, leading to a false positive toxic effect on C. elegans growth and reproduction. When the ENPs were tested in two alternate C. elegans assays that did not contain E. coli, we found greatly reduced toxicity of ENPs. This study illustrates a key unexpected artifact that may occur during nanotoxicity assays.
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Affiliation(s)
| | - Antonio Montoro Bustos
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Alexander W. Peterson
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Vytas Reipa
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | | | - Sanem Hosbas Coskun
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Tae Joon Cho
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Monique E. Johnson
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Vincent A. Hackley
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Bryant C. Nelson
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Michael R. Winchester
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - John T. Elliott
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
| | - Elijah J. Petersen
- Materials Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8313
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9
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Lin-Gibson S, Sarkar S, Elliott JT. Summary of the National Institute of Standards and Technology and US Food And Drug Administration cell counting workshop: Sharing practices in cell counting measurements. Cytotherapy 2018; 20:785-795. [PMID: 29699860 DOI: 10.1016/j.jcyt.2018.03.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/13/2018] [Indexed: 11/19/2022]
Abstract
The emergence of cell-based therapeutics has increased the need for high-quality, robust and validated measurements for cell characterization. Cell count, being one of the most fundamental measures for cell-based therapeutics, now requires increased levels of measurement confidence. The National Institute of Standards and Technology (NIST) and the US Food and Drug Administration (FDA) jointly hosted a workshop focused on cell counting in April 2017 entitled "NIST-FDA Cell Counting Workshop: Sharing Practices in Cell Counting Measurements." The focus of the workshop was on approaches for selecting, designing and validating cell counting methods and overcoming gaps in obtaining sufficient measurement assurance for cell counting. Key workshop discussion points, representing approximately 50 subject matter experts from industry, academia and government agencies, are summarized here. A key conclusion is the need to design the most appropriate cell counting method, including control/measurement assurance strategies, for a specific counting purposes. There remains a need for documentary standards for streamlining the process to develop, qualify and validate cell counting measurements as well as community-driven efforts to develop new or improved biological and non-biological reference materials.
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Affiliation(s)
- Sheng Lin-Gibson
- National Institute of Standards and Technology, Biosystems and Biomaterials Division, Gaithersburg, Maryland, USA.
| | - Sumona Sarkar
- National Institute of Standards and Technology, Biosystems and Biomaterials Division, Gaithersburg, Maryland, USA
| | - John T Elliott
- National Institute of Standards and Technology, Biosystems and Biomaterials Division, Gaithersburg, Maryland, USA
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10
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Abstract
The current push for rigor and reproducibility is driven by a desire for confidence in research results. Here, we suggest a framework for a systematic process, based on consensus principles of measurement science, to guide researchers and reviewers in assessing, documenting, and mitigating the sources of uncertainty in a study. All study results have associated ambiguities that are not always clarified by simply establishing reproducibility. By explicitly considering sources of uncertainty, noting aspects of the experimental system that are difficult to characterize quantitatively, and proposing alternative interpretations, the researcher provides information that enhances comparability and reproducibility.
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Affiliation(s)
- Anne L. Plant
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
- * E-mail:
| | - Chandler A. Becker
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Robert J. Hanisch
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Ronald F. Boisvert
- Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Antonio M. Possolo
- Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - John T. Elliott
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
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11
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Peterson AW, Halter M, Tona A, Plant AL, Elliott JT. Mass Measurements of Focal Adhesions in Single Cells Using High Resolution Surface Plasmon Resonance Microscopy. Proc SPIE Int Soc Opt Eng 2018; 10509:1050905. [PMID: 29755164 PMCID: PMC5947864 DOI: 10.1117/12.2290776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Surface plasmon resonance microscopy (SPRM) is a powerful label-free imaging technique with spatial resolution approaching the optical diffraction limit. The high sensitivity of SPRM to small changes in index of refraction at an interface allows imaging of dynamic protein structures within a cell. Visualization of subcellular features, such as focal adhesions (FAs), can be performed on live cells using a high numerical aperture objective lens with a digital light projector to precisely position the incident angle of the excitation light. Within the cell-substrate region of the SPRM image, punctate regions of high contrast are putatively identified as the cellular FAs. Optical parameter analysis is achieved by application of the Fresnel model to the SPRM data and resulting refractive index measurements are used to calculate protein density and mass. FAs are known to be regions of high protein density that reside at the cell-substratum interface. Comparing SPRM with fluorescence images of antibody stained for vinculin, a component in FAs, reveals similar measurements of FA size. In addition, a positive correlation between FA size and protein density is revealed by SPRM. Comparing SPRM images for two cell types reveals a distinct difference in the protein density and mass of their respective FAs. Application of SPRM to quantify mass can greatly aid monitoring basic processes that control FA mass and growth and contribute to accurate models that describe cell-extracellular interactions.
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12
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Sarkar S, Lund SP, Vyzasatya R, Vanguri P, Elliott JT, Plant AL, Lin-Gibson S. Evaluating the quality of a cell counting measurement process via a dilution series experimental design. Cytotherapy 2017; 19:1509-1521. [DOI: 10.1016/j.jcyt.2017.08.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/10/2017] [Accepted: 08/16/2017] [Indexed: 12/17/2022]
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13
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Wu JC, Halter M, Kacker RN, Elliott JT, Plant AL. A novel measure and significance testing in data analysis of cell image segmentation. BMC Bioinformatics 2017; 18:168. [PMID: 28292256 PMCID: PMC5351215 DOI: 10.1186/s12859-017-1527-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 02/06/2017] [Indexed: 02/02/2023] Open
Abstract
Background Cell image segmentation (CIS) is an essential part of quantitative imaging of biological cells. Designing a performance measure and conducting significance testing are critical for evaluating and comparing the CIS algorithms for image-based cell assays in cytometry. Many measures and methods have been proposed and implemented to evaluate segmentation methods. However, computing the standard errors (SE) of the measures and their correlation coefficient is not described, and thus the statistical significance of performance differences between CIS algorithms cannot be assessed. Results We propose the total error rate (TER), a novel performance measure for segmenting all cells in the supervised evaluation. The TER statistically aggregates all misclassification error rates (MER) by taking cell sizes as weights. The MERs are for segmenting each single cell in the population. The TER is fully supported by the pairwise comparisons of MERs using 106 manually segmented ground-truth cells with different sizes and seven CIS algorithms taken from ImageJ. Further, the SE and 95% confidence interval (CI) of TER are computed based on the SE of MER that is calculated using the bootstrap method. An algorithm for computing the correlation coefficient of TERs between two CIS algorithms is also provided. Hence, the 95% CI error bars can be used to classify CIS algorithms. The SEs of TERs and their correlation coefficient can be employed to conduct the hypothesis testing, while the CIs overlap, to determine the statistical significance of the performance differences between CIS algorithms. Conclusions A novel measure TER of CIS is proposed. The TER’s SEs and correlation coefficient are computed. Thereafter, CIS algorithms can be evaluated and compared statistically by conducting the significance testing.
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Affiliation(s)
- Jin Chu Wu
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
| | - Michael Halter
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Raghu N Kacker
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - John T Elliott
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Anne L Plant
- National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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14
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Johnson ME, Hanna SK, Montoro Bustos AR, Sims CM, Elliott LCC, Lingayat A, Johnston AC, Nikoobakht B, Elliott JT, Holbrook RD, Scott KCK, Murphy KE, Petersen EJ, Yu LL, Nelson BC. Separation, Sizing, and Quantitation of Engineered Nanoparticles in an Organism Model Using Inductively Coupled Plasma Mass Spectrometry and Image Analysis. ACS Nano 2017; 11:526-540. [PMID: 27983787 PMCID: PMC5459480 DOI: 10.1021/acsnano.6b06582] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
For environmental studies assessing uptake of orally ingested engineered nanoparticles (ENPs), a key step in ensuring accurate quantification of ingested ENPs is efficient separation of the organism from ENPs that are either nonspecifically adsorbed to the organism and/or suspended in the dispersion following exposure. Here, we measure the uptake of 30 and 60 nm gold nanoparticles (AuNPs) by the nematode, Caenorhabditis elegans, using a sucrose density gradient centrifugation protocol to remove noningested AuNPs. Both conventional inductively coupled plasma mass spectrometry (ICP-MS) and single particle (sp)ICP-MS are utilized to measure the total mass and size distribution, respectively, of ingested AuNPs. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) imaging confirmed that traditional nematode washing procedures were ineffective at removing excess suspended and/or adsorbed AuNPs after exposure. Water rinsing procedures had AuNP removal efficiencies ranging from 57 to 97% and 22 to 83%, while the sucrose density gradient procedure had removal efficiencies of 100 and 93 to 98%, respectively, for the 30 and 60 nm AuNP exposure conditions. Quantification of total Au uptake was performed following acidic digestion of nonexposed and Au-exposed nematodes, whereas an alkaline digestion procedure was optimized for the liberation of ingested AuNPs for spICP-MS characterization. Size distributions and particle number concentrations were determined for AuNPs ingested by nematodes with corresponding confirmation of nematode uptake via high-pressure freezing/freeze substitution resin preparation and large-area SEM imaging. Methods for the separation and in vivo quantification of ENPs in multicellular organisms will facilitate robust studies of ENP uptake, biotransformation, and hazard assessment in the environment.
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Affiliation(s)
- Monique E Johnson
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Shannon K Hanna
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Antonio R Montoro Bustos
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Christopher M Sims
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Lindsay C C Elliott
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Akshay Lingayat
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Adrian C Johnston
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Babak Nikoobakht
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - John T Elliott
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - R David Holbrook
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Keana C K Scott
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Karen E Murphy
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Elijah J Petersen
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Lee L Yu
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Bryant C Nelson
- Chemical Science Division, ‡Biosystems and Biomaterials Division, and §Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
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Elliott JT. Liaison psychiatry: a brief history. BJPsych Bull 2016; 40:348-349. [PMID: 28377820 PMCID: PMC5353520 DOI: 10.1192/pb.40.6.348] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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16
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Abstract
Surface plasmon resonance (SPR) imaging allows real-time label-free imaging based on index of refraction and changes in index of refraction at an interface. Optical parameter analysis is achieved by application of the Fresnel model to SPR data typically taken by an instrument in a prism based figuration. We carry out SPR imaging on a microscope by launching light into a sample and collecting reflected light through a high numerical aperture microscope objective. The SPR microscope enables spatial resolution that approaches the diffraction limit and has a dynamic range that allows detection of subnanometer to submicrometer changes in thickness of biological material at a surface. However, unambiguous quantitative interpretation of SPR changes using the microscope system could not be achieved using the Fresnel model because of polarization dependent attenuation and optical aberration that occurs in the high numerical aperture objective. To overcome this problem, we demonstrate a model to correct for polarization diattenuation and optical aberrations in the SPR data and develop a procedure to calibrate reflectivity to index of refraction values. The calibration and correction strategy for quantitative analysis was validated by comparing the known indices of refraction of bulk materials with corrected SPR data interpreted with the Fresnel model. Subsequently, we applied our SPR microscopy method to evaluate the index of refraction for a series of polymer microspheres in aqueous media and validated the quality of the measurement with quantitative phase microscopy.
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Simon CG, Lin-Gibson S, Elliott JT, Sarkar S, Plant AL. Strategies for Achieving Measurement Assurance for Cell Therapy Products. Stem Cells Transl Med 2016; 5:705-8. [PMID: 27386605 DOI: 10.5966/sctm.2015-0269] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
UNLABELLED The cell therapy industry has identified the inability to reliably characterize cells as possibly its greatest challenge and has called for standards and reference materials to provide assurance for measurements of cell properties. The challenges in characterization of cell therapy products can be largely addressed with systematic approaches for assessing sources of uncertainty and improving confidence in key measurements. This article presents the many strategies that can be used to ensure measurement confidence and discusses them in terms of how they can be applied to characterization of cell therapy products. SIGNIFICANCE Application of these strategies to cell measurements will help to establish qualified assays for cell characterization, which may help streamline regulatory approval and enable more efficient development of cell therapy products.
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Bhadriraju K, Halter M, Amelot J, Bajcsy P, Chalfoun J, Vandecreme A, Mallon BS, Park KY, Sista S, Elliott JT, Plant AL. Large-scale time-lapse microscopy of Oct4 expression in human embryonic stem cell colonies. Stem Cell Res 2016; 17:122-9. [PMID: 27286574 PMCID: PMC5012928 DOI: 10.1016/j.scr.2016.05.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 04/15/2016] [Accepted: 05/20/2016] [Indexed: 01/06/2023] Open
Abstract
Identification and quantification of the characteristics of stem cell preparations is critical for understanding stem cell biology and for the development and manufacturing of stem cell based therapies. We have developed image analysis and visualization software that allows effective use of time-lapse microscopy to provide spatial and dynamic information from large numbers of human embryonic stem cell colonies. To achieve statistically relevant sampling, we examined >680 colonies from 3 different preparations of cells over 5 days each, generating a total experimental dataset of 0.9 terabyte (TB). The 0.5 Giga-pixel images at each time point were represented by multi-resolution pyramids and visualized using the Deep Zoom Javascript library extended to support viewing Giga-pixel images over time and extracting data on individual colonies. We present a methodology that enables quantification of variations in nominally-identical preparations and between colonies, correlation of colony characteristics with Oct4 expression, and identification of rare events.
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Affiliation(s)
- Kiran Bhadriraju
- Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Michael Halter
- Biosystems and Biomaterials Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Julien Amelot
- Software Systems Division, Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Peter Bajcsy
- Software Systems Division, Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Joe Chalfoun
- Software Systems Division, Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Antoine Vandecreme
- Software Systems Division, Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Barbara S Mallon
- The NIH Stem Cell Unit, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, NIH, U.S. Department of Health and Human Services, Bethesda, MD, USA
| | - Kye-Yoon Park
- The NIH Stem Cell Unit, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, NIH, U.S. Department of Health and Human Services, Bethesda, MD, USA
| | - Subhash Sista
- Biosystems and Biomaterials Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - John T Elliott
- Biosystems and Biomaterials Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Anne L Plant
- Biosystems and Biomaterials Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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Rösslein M, Elliott JT, Salit M, Petersen EJ, Hirsch C, Krug HF, Wick P. Use of Cause-and-Effect Analysis to Design a High-Quality Nanocytotoxicology Assay. Chem Res Toxicol 2015; 28:21-30. [DOI: 10.1021/tx500327y] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Matthias Rösslein
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
| | - John T. Elliott
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
| | - Marc Salit
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
| | - Elijah J. Petersen
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
| | - Cordula Hirsch
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
| | - Harald F. Krug
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
| | - Peter Wick
- Materials-Biology Interactions Laboratory, and ‡International
Research Cooperations Manager, Swiss Federal Laboratories for Material Testing and Research (Empa), CH-9014 St. Gallen, Switzerland
- Cell Systems Science
Group, and ∥Genome Scale Measurements Group, National Institute of Standard and Technology, Gaithersburg, Maryland 20899, United States
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Halter M, Bier E, DeRose PC, Cooksey GA, Choquette SJ, Plant AL, Elliott JT. An Automated Protocol for Performance Benchmarking a Widefield Fluorescence Microscope. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1743] [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: 11/30/2022] Open
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21
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Peterson AW, Halter M, Tona A, Lin NJ, Elliott JT. Applications of High Resolution Surface Plasmon Resonance Imaging to Adherent Cells: Single Mammalian Cells to Bacterial Biofilms. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1770] [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: 11/25/2022] Open
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22
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Halter M, Bier E, DeRose PC, Cooksey GA, Choquette SJ, Plant AL, Elliott JT. An automated protocol for performance benchmarking a widefield fluorescence microscope. Cytometry A 2014; 85:978-85. [DOI: 10.1002/cyto.a.22519] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 07/11/2014] [Accepted: 07/22/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Michael Halter
- Biosystems and Biomaterials Division, Materials Measurement Laboratory; National Institute of Standards and Technology; Gaithersburg Maryland 20899
| | - Elianna Bier
- Department of Physics; Augsburg College; Minneapolis Minnesota 55454
| | - Paul C. DeRose
- Biosystems and Biomaterials Division, Materials Measurement Laboratory; National Institute of Standards and Technology; Gaithersburg Maryland 20899
| | - Gregory A. Cooksey
- Biosystems and Biomaterials Division, Materials Measurement Laboratory; National Institute of Standards and Technology; Gaithersburg Maryland 20899
| | - Steven J. Choquette
- Biosystems and Biomaterials Division, Materials Measurement Laboratory; National Institute of Standards and Technology; Gaithersburg Maryland 20899
| | - Anne L. Plant
- Biosystems and Biomaterials Division, Materials Measurement Laboratory; National Institute of Standards and Technology; Gaithersburg Maryland 20899
| | - John T. Elliott
- Biosystems and Biomaterials Division, Materials Measurement Laboratory; National Institute of Standards and Technology; Gaithersburg Maryland 20899
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Tichauer KM, Diop M, Elliott JT, Samkoe KS, Hasan T, St Lawrence K, Pogue BW. Accounting for pharmacokinetic differences in dual-tracer receptor density imaging. Phys Med Biol 2014; 59:2341-51. [PMID: 24743262 DOI: 10.1088/0031-9155/59/10/2341] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dual-tracer molecular imaging is a powerful approach to quantify receptor expression in a wide range of tissues by using an untargeted tracer to account for any nonspecific uptake of a molecular-targeted tracer. This approach has previously required the pharmacokinetics of the receptor-targeted and untargeted tracers to be identical, requiring careful selection of an ideal untargeted tracer for any given targeted tracer. In this study, methodology capable of correcting for tracer differences in arterial input functions, as well as binding-independent delivery and retention, is derived and evaluated in a mouse U251 glioma xenograft model using an Affibody tracer targeted to epidermal growth factor receptor (EGFR), a cell membrane receptor overexpressed in many cancers. Simulations demonstrated that blood, and to a lesser extent vascular-permeability, pharmacokinetic differences between targeted and untargeted tracers could be quantified by deconvolving the uptakes of the two tracers in a region of interest devoid of targeted tracer binding, and therefore corrected for, by convolving the uptake of the untargeted tracer in all regions of interest by the product of the deconvolution. Using fluorescently labeled, EGFR-targeted and untargeted Affibodies (known to have different blood clearance rates), the average tumor concentration of EGFR in four mice was estimated using dual-tracer kinetic modeling to be 3.9 ± 2.4 nM compared to an expected concentration of 2.0 ± 0.4 nM. However, with deconvolution correction a more equivalent EGFR concentration of 2.0 ± 0.4 nM was measured.
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Affiliation(s)
- K M Tichauer
- Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA
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Cho TJ, MacCuspie RI, Gigault J, Gorham JM, Elliott JT, Hackley VA. Highly stable positively charged dendron-encapsulated gold nanoparticles. Langmuir 2014; 30:3883-3893. [PMID: 24625049 DOI: 10.1021/la5002013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report the development of a novel cationic dendron (TAG1-PCD) and a positively charged gold nanoparticle-dendron conjugate (PCD-AuNP). TAG1-PCD was designed by considering the reactivity, hydrophilicity, and cationic nature that is required to yield a stable gold conjugate in aqueous media. The PCD-AuNPs, nominally 10 nm in size, were synthesized by reduction of chloroauric acid in the presence of TAG1-PCD. The physicochemical properties of PCD-AuNPs were characterized by dynamic light scattering, transmission electron microscopy, UV-vis absorbance, and X-ray photoelectron spectroscopy for investigation of size distribution, shape uniformity, surface plasmon resonance bands, and Au-dendron bonding. Asymmetric-flow field flow fractionation was employed to confirm the in situ size, purity, and surface properties of the PCD-AuNPs. Additionally, the stability of PCD-AuNPs was systematically evaluated with respect to shelf life determination, stability in biological media and a wide range of pH values, chemical resistance against cyanide, redispersibility from lyophilized state, and stability at temperatures relevant to biological systems. Dose dependent cell viability was evaluated in vitro using the human lung epithelial cell line A549 and a monkey kidney Vero cell line. Observations from in vitro studies are discussed. Overall, the investigation confirmed the successful development of stable PCD-AuNPs with excellent stability in biologically relevant test media containing proteins and electrolytes, and with a shelf life exceeding 6 months. The excellent aqueous stability and apparent lack of toxicity for this conjugate enhances its potential use as a test material for investigating interactions between positively charged NPs and biocellular and biomolecular systems, or as a vehicle for drug delivery.
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Affiliation(s)
- Tae Joon Cho
- Materials Measurement Science Division and ‡Biosystems and Biomaterials Division, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
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Peterson AW, Halter M, Tona A, Bhadriraju K, Elliott JT, Plant AL. High Resolution Surface Plasmon Resonance Imaging of Focal Adhesions in Single Cells. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.190] [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: 10/23/2022] Open
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26
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Elliott JT. Transparency and the foundations of the health service. BMJ 2013; 346:f2507. [PMID: 23618843 DOI: 10.1136/bmj.f2507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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27
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Mancia A, Elliott JT, Halter M, Bhadriraju K, Tona A, Spurlin TA, Middlebrooks BL, Baatz JE, Warr GW, Plant AL. Quantitative methods to characterize morphological properties of cell lines. Biotechnol Prog 2012; 28:1069-78. [DOI: 10.1002/btpr.1564] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 03/23/2012] [Indexed: 12/22/2022]
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28
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Arora R, Ridha M, Lee DS, Elliott JT, Rosenberg H, St Lawrence K. Changes in Cerebral Hemodynamics in Response to Medical Therapy for Patent Ductus Arteriosus: Prediction of Treatment Outcome in Preterm Infants. Paediatr Child Health 2012. [DOI: 10.1093/pch/17.suppl_a.38a] [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: 11/14/2022] Open
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29
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Halter M, Sisan DR, Chalfoun J, Stottrup BL, Cardone A, Dima AA, Tona A, Plant AL, Elliott JT. Cell cycle dependent TN-C promoter activity determined by live cell imaging. Cytometry A 2012; 79:192-202. [PMID: 22045641 DOI: 10.1002/cyto.a.21028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The extracellular matrix protein tenascin-C plays a critical role in development, wound healing, and cancer progression, but how it is controlled and how it exerts its physiological responses remain unclear. By quantifying the behavior of live cells with phase contrast and fluorescence microscopy, the dynamic regulation of TN-C promoter activity is examined. We employ an NIH 3T3 cell line stably transfected with the TN-C promoter ligated to the gene sequence for destabilized green fluorescent protein (GFP). Fully automated image analysis routines, validated by comparison with data derived from manual segmentation and tracking of single cells, are used to quantify changes in the cellular GFP in hundreds of individual cells throughout their cell cycle during live cell imaging experiments lasting 62 h. We find that individual cells vary substantially in their expression patterns over the cell cycle, but that on average TN-C promoter activity increases during the last 40% of the cell cycle. We also find that the increase in promoter activity is proportional to the activity earlier in the cell cycle. This work illustrates the application of live cell microscopy and automated image analysis of a promoter-driven GFP reporter cell line to identify subtle gene regulatory mechanisms that are difficult to uncover using population averaged measurements.
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Affiliation(s)
- Michael Halter
- Cell Systems Science Group/Biochemical Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Abstract
Background There are significant challenges associated with the building of ontologies for cell biology experiments including the large numbers of terms and their synonyms. These challenges make it difficult to simultaneously query data from multiple experiments or ontologies. If vocabulary terms were consistently used and reused across and within ontologies, queries would be possible through shared terms. One approach to achieving this is to strictly control the terms used in ontologies in the form of a pre-defined schema, but this approach limits the individual researcher's ability to create new terms when needed to describe new experiments. Results Here, we propose the use of a limited number of highly reusable common root terms, and rules for an experimentalist to locally expand terms by adding more specific terms under more general root terms to form specific new vocabulary hierarchies that can be used to build ontologies. We illustrate the application of the method to build vocabularies and a prototype database for cell images that uses a visual data-tree of terms to facilitate sophisticated queries based on a experimental parameters. We demonstrate how the terminology might be extended by adding new vocabulary terms into the hierarchy of terms in an evolving process. In this approach, image data and metadata are handled separately, so we also describe a robust file-naming scheme to unambiguously identify image and other files associated with each metadata value. The prototype database http://sbd.nist.gov/ consists of more than 2000 images of cells and benchmark materials, and 163 metadata terms that describe experimental details, including many details about cell culture and handling. Image files of interest can be retrieved, and their data can be compared, by choosing one or more relevant metadata values as search terms. Metadata values for any dataset can be compared with corresponding values of another dataset through logical operations. Conclusions Organizing metadata for cell imaging experiments under a framework of rules that include highly reused root terms will facilitate the addition of new terms into a vocabulary hierarchy and encourage the reuse of terms. These vocabulary hierarchies can be converted into XML schema or RDF graphs for displaying and querying, but this is not necessary for using it to annotate cell images. Vocabulary data trees from multiple experiments or laboratories can be aligned at the root terms to facilitate query development. This approach of developing vocabularies is compatible with the major advances in database technology and could be used for building the Semantic Web.
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Affiliation(s)
- Anne L Plant
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Nelson BC, Petersen EJ, Marquis BJ, Atha DH, Elliott JT, Cleveland D, Watson SS, Tseng IH, Dillon A, Theodore M, Jackman J. NIST gold nanoparticle reference materials do not induce oxidative DNA damage. Nanotoxicology 2011; 7:21-9. [DOI: 10.3109/17435390.2011.626537] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Reyes DR, Hong JS, Elliott JT, Gaitan M. Hybrid cell adhesive material for instant dielectrophoretic cell trapping and long-term cell function assessment. Langmuir 2011; 27:10027-10034. [PMID: 21702467 DOI: 10.1021/la200762j] [Citation(s) in RCA: 4] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Dielectrophoresis (DEP) for cell manipulation has focused, for the most part, on approaches for separation/enrichment of cells of interest. Advancements in cell positioning and immobilization onto substrates for cell culture, either as single cells or as cell aggregates, has benefited from the intensified research efforts in DEP (electrokinetic) manipulation. However, there has yet to be a DEP approach that provides the conditions for cell manipulation while promoting cell function processes such as cell differentiation. Here we present the first demonstration of a system that combines DEP with a hybrid cell adhesive material (hCAM) to allow for cell entrapment and cell function, as demonstrated by cell differentiation into neuronlike cells (NLCs). The hCAM, comprised of polyelectrolytes and fibronectin, was engineered to function as an instantaneous cell adhesive surface after DEP manipulation and to support long-term cell function (cell proliferation, induction, and differentiation). Pluripotent P19 mouse embryonal carcinoma cells flowing within a microchannel were attracted to the DEP electrode surface and remained adhered onto the hCAM coating under a fluid flow field after the DEP forces were removed. Cells remained viable after DEP manipulation for up to 8 d, during which time the P19 cells were induced to differentiate into NLCs. This approach could have further applications in areas such as cell-cell communication, three-dimensional cell aggregates to create cell microenvironments, and cell cocultures.
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Affiliation(s)
- Darwin R Reyes
- Semiconductor Electronics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, MS 8120, Gaithersburg, Maryland 20899-8120, United States.
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Dima AA, Elliott JT, Filliben JJ, Halter M, Peskin A, Bernal J, Kociolek M, Brady MC, Tang HC, Plant AL. Comparison of segmentation algorithms for fluorescence microscopy images of cells. Cytometry A 2011; 79:545-59. [PMID: 21674772 DOI: 10.1002/cyto.a.21079] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 02/24/2011] [Accepted: 04/12/2011] [Indexed: 11/07/2022]
Abstract
The analysis of fluorescence microscopy of cells often requires the determination of cell edges. This is typically done using segmentation techniques that separate the cell objects in an image from the surrounding background. This study compares segmentation results from nine different segmentation techniques applied to two different cell lines and five different sets of imaging conditions. Significant variability in the results of segmentation was observed that was due solely to differences in imaging conditions or applications of different algorithms. We quantified and compared the results with a novel bivariate similarity index metric that evaluates the degree of underestimating or overestimating a cell object. The results show that commonly used threshold-based segmentation techniques are less accurate than k-means clustering with multiple clusters. Segmentation accuracy varies with imaging conditions that determine the sharpness of cell edges and with geometric features of a cell. Based on this observation, we propose a method that quantifies cell edge character to provide an estimate of how accurately an algorithm will perform. The results of this study will assist the development of criteria for evaluating interlaboratory comparability.
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Affiliation(s)
- Alden A Dima
- Software and Systems Division, Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Abstract
Numerous opportunities exist to apply microfluidic technology to high-throughput and high-content cell-based assays. However, maximizing the value of microfluidic assays for applications such as drug discovery, screening, or toxicity evaluation will require assurance of within-device repeatability, day-to-day reproducibility, and robustness to variations in conditions that might occur from laboratory to laboratory. This report describes a study of the performance and variability of a cell-based toxicity assay in microfluidic devices made of poly(dimethylsiloxane) (PDMS). The assay involves expression of destabilized green fluorescent protein (GFP) as a reporter of intracellular protein synthesis and degradation. Reduction in cellular GFP due to inhibition of ribosome activity by cycloheximide (CHX) was quantified with real-time quantitative fluorescence imaging. Assay repeatability was measured within a 64-chamber microfluidic device. Assay performance across a range of cell loading densities within a single device was assessed, as was replication of measurements in microfluidic devices prepared on different days. Assay robustness was tested using different fluorescence illumination sources and reservoir-to-device tubing choices. Both microfluidic and larger scale assay conditions showed comparable GFP decay rates upon CHX exposure, but the microfluidic data provided the higher level of confidence.
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Zook JM, MacCuspie RI, Locascio LE, Halter MD, Elliott JT. Stable nanoparticle aggregates/agglomerates of different sizes and the effect of their size on hemolytic cytotoxicity. Nanotoxicology 2010; 5:517-30. [DOI: 10.3109/17435390.2010.536615] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Chalfoun J, Dima AA, Peskin AP, Elliott JT, Filliben JJ. A Human Inspired Local Ratio-Based Algorithm for Edge Detection in Fluorescent Cell Images. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/978-3-642-17289-2_3] [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: 03/09/2023]
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Halter M, Almeida JL, Tona A, Cole KD, Plant AL, Elliott JT. A mechanistically relevant cytotoxicity assay based on the detection of cellular GFP. Assay Drug Dev Technol 2009; 7:356-65. [PMID: 19530892 DOI: 10.1089/adt.2009.0192] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cell-based assays for measuring ribosome inhibition by proteins such as the plant toxin ricin are important for characterizing decontamination strategies and developing detection technologies for field use. We report here an assay for ricin that provides a response that is relevant to the mechanism of ricin activity and permits a much faster readout than the commonly used assays for cytotoxicity. The assay relies on the response of an engineered reporter cell line that was produced by stably transfecting Vero cells to express green fluorescent protein (GFP) under the control ofa cytomegalovirus (CMV) promoter. The results of the GFP-based assay were compared with the assay results from three commercially available cytotoxicity assays. The GFP assay reports a sensitive response to ricin after 6 h of treatment while the other assays require a 24-h incubation. Unlike the other assays, monitoring cellular GFP on a per-cell basis allows detection of reduced ribosome activity before significant cell death occurs, and the results are not convoluted by the numbers of cells being assayed.
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Affiliation(s)
- Michael Halter
- Cell Systems Science Group/Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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Bhadriraju K, Chung KH, Spurlin TA, Haynes RJ, Elliott JT, Plant AL. The relative roles of collagen adhesive receptor DDR2 activation and matrix stiffness on the downregulation of focal adhesion kinase in vascular smooth muscle cells. Biomaterials 2009; 30:6687-94. [PMID: 19762078 DOI: 10.1016/j.biomaterials.2009.08.036] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 08/26/2009] [Indexed: 12/25/2022]
Abstract
Cells within tissues derive mechanical anchorage and specific molecular signals from the insoluble extracellular matrix (ECM) that surrounds them. Understanding the role of different cues that extracellular matrices provide cells is critical for controlling and predicting cell response to scaffolding materials. Using an engineered extracellular matrix of Type I collagen we examined how the stiffness, supramolecular structure, and glycosylation of collagen matrices influence the protein levels of cellular FAK and the activation of myosin II. Our results show that (1) cellular FAK is downregulated on collagen fibrils, but not on a non-fibrillar monolayer of collagen, (2) the downregulation of FAK is independent of the stiffness of the collagen fibrils, and (3) FAK levels are correlated with levels of tyrosine phosphorylation of the collagen adhesion receptor DDR2. Further, siRNA depletion of DDR2 blocks FAK downregulation. Our results suggest that the collagen receptor DDR2 is involved in the regulation of FAK levels in vSMC adhered to Type I collagen matrices, and that regulation of FAK levels in these cells appears to be independent of matrix stiffness.
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Affiliation(s)
- Kiran Bhadriraju
- SAIC, Mail stop 8313, 100 Bureau Drive, Gaithersburg, MD-20899, USA.
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Halter M, Almeida JL, Tona A, Cole KD, Plant AL, Elliott JT. A Mechanistically Relevant Cytotoxicity Assay Based on the Detection of Cellular Green Fluorescent Protein. Assay Drug Dev Technol 2009. [DOI: 10.1089/adt.2009.192] [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: 10/20/2022] Open
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Pease LF, Elliott JT, Tsai DH, Zachariah MR, Tarlov MJ. Determination of protein aggregation with differential mobility analysis: application to IgG antibody. Biotechnol Bioeng 2008; 101:1214-22. [PMID: 18980182 DOI: 10.1002/bit.22017] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Here we describe the use of electrospray differential mobility analysis (ES-DMA), also known as gas-phase electrophoretic mobility molecular analysis (GEMMA), as a method for measuring low-order soluble aggregates of proteins in solution. We demonstrate proof of concept with IgG antibodies. In ES-DMA, aqueous solutions of the antibody protein are electrosprayed and the various aerosolized species are separated according to their electrophoretic mobility using a differential mobility analyzer. In this way, complete size distributions of protein species present from 3 to 250 nm can be obtained with the current set up, including distinct peaks for IgG monomers to pentamers. The sizes of the IgG and IgG aggregates measured by DMA were found to be in good agreement with those calculated from simple models, which take the structural dimensions of IgG from protein crystallographic data. The dependence of IgG aggregation on the solution concentration and ionic strength was also examined, and the portion of aggregates containing chemically crosslinked antibodies was quantified. These results indicate that ES-DMA holds potential as a measurement tool to study protein aggregation phenomena such as those associated with antibody reagent manufacturing and protein therapeutics.
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Affiliation(s)
- Leonard F Pease
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Halter M, Elliott JT, Hubbard JB, Tona A, Plant AL. Cell volume distributions reveal cell growth rates and division times. J Theor Biol 2008; 257:124-30. [PMID: 19068221 DOI: 10.1016/j.jtbi.2008.10.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 10/21/2008] [Accepted: 10/30/2008] [Indexed: 11/30/2022]
Abstract
A population of cells in culture displays a range of phenotypic responses even when those cells are derived from a single cell and are exposed to a homogeneous environment. Phenotypic variability can have a number of sources including the variable rates at which individual cells within the population grow and divide. We have examined how such variations contribute to population responses by measuring cell volumes within genetically identical populations of cells where individual members of the population are continuously growing and dividing, and we have derived a function describing the stationary distribution of cell volumes that arises from these dynamics. The model includes stochastic parameters for the variability in cell cycle times and growth rates for individual cells in a proliferating cell line. We used the model to analyze the volume distributions obtained for two different cell lines and one cell line in the absence and presence of aphidicolin, a DNA polymerase inhibitor. The derivation and application of the model allows one to relate the stationary population distribution of cell volumes to extrinsic biological noise present in growing and dividing cell cultures.
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Affiliation(s)
- Michael Halter
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Plant AL, Bhadriraju K, Spurlin TA, Elliott JT. Cell response to matrix mechanics: focus on collagen. Biochim Biophys Acta 2008; 1793:893-902. [PMID: 19027042 DOI: 10.1016/j.bbamcr.2008.10.012] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 10/27/2008] [Indexed: 01/16/2023]
Abstract
Many model systems and measurement tools have been engineered for observing and quantifying the effect of mechanics on cellular response. These have contributed greatly to our current knowledge of the molecular events by which mechanical cues affect cell biology. Cell responses to the mechanical properties of type 1 collagen gels are discussed, followed by a description of a model system of very thin, mechanically tunable collagen films that evoke similar responses from cells as do gel systems, but have additional advantages. Cell responses to thin films of collagen suggest that at least some of the mechanical cues that cells can respond to in their environment occur at the sub-micron scale. Mechanical properties of thin films of collagen can be tuned without altering integrin engagement, and in some cases without altering topology, making them useful in addressing questions regarding the roles of specific integrins in transducing or mitigating responses to mechanical cues. The temporal response of cells to differences in ECM may provide insight into mechanisms of signal transduction.
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Affiliation(s)
- Anne L Plant
- National Institute of Standards and Technology, Biochemical Science Division, Gaithersburg, MD 20899, USA.
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Halter M, Tona A, Bhadriraju K, Plant AL, Elliott JT. Automated live cell imaging of green fluorescent protein degradation in individual fibroblasts. Cytometry A 2007; 71:827-34. [PMID: 17828790 DOI: 10.1002/cyto.a.20461] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [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: 11/06/2022]
Abstract
To accurately interpret the data from fluorescent proteins as reporters of gene activation within living cells, it is important to understand the kinetics of the degradation of the reporter proteins. We examined the degradation kinetics over a large number (>1,000) of single, living cells from a clonal population of NIH3T3 fibroblasts that were stably transfected with a destabilized, enhanced green fluorescent protein (eGFP) reporter driven by the tenascin-C promoter. Data collection and quantification of the fluorescence protein within a statistically significant number of individual cells over long times (14 h) by automated microscopy was facilitated by culturing cells on micropatterned arrays that confined their migration and allowed them to be segmented using phase contrast images. To measure GFP degradation rates unambiguously, protein synthesis was inhibited with cycloheximide. Results from automated live cell microscopy and image analysis indicated a wide range of cell-to-cell variability in the GFP fluorescence within individual cells. Degradation for this reporter was analyzed as a first order rate process with a degradation half-life of 2.8 h. We found that GFP degradation rates were independent of the initial intensity of GFP fluorescence within cells. This result indicates that higher GFP abundance in some cells is likely due to higher rates of gene expression, because it is not due to systematically lower rates of protein degradation. The approach described in this study will assist the quantification and understanding of gene activity within live cells using fluorescent protein reporters.
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Affiliation(s)
- Michael Halter
- Cell and Tissue Measurements Group, Biochemical Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Bhadriraju K, Elliott JT, Nguyen M, Plant AL. Quantifying myosin light chain phosphorylation in single adherent cells with automated fluorescence microscopy. BMC Cell Biol 2007; 8:43. [PMID: 17941977 PMCID: PMC2213650 DOI: 10.1186/1471-2121-8-43] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [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: 03/23/2007] [Accepted: 10/17/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In anchorage dependent cells, myosin generated contractile forces affect events closely associated with adhesion such as the formation of stress fibers and focal adhesions, and temporally distal events such as entry of the cell into S-phase. As occurs in many signaling pathways, a phosphorylation reaction (in this case, phosphorylation of myosin light chain) is directly responsible for cell response. Western blotting has been useful in measuring intracellular phosphorylation events, but cells are lysed in the process of sample preparation for western blotting, and spatial information such as morphology, localization of the phosphorylated species, and the distribution of individual cell responses across the population is lost. We report here a reliable automated microscopy method for quantitative measurement of myosin light chain phosphorylation in adherent cells. This method allows us to concurrently examine cell morphology, cell-cell contact, and myosin light chain diphosphorylation in vascular smooth muscle cells. RESULTS Paraformaldehyde fixation and Triton X-100 permeabilization preserved cell morphology and myosin light chain phosphorylation better than the alternative fixation/permeabilization methods tested. We utilized automated microscopy methods to acquire three color images, determine cell spread area, and quantify the intensity of staining within each cell with anti-phospho-MLC antibody. Our results indicate that A10 rat aortic smooth muscle cells exhibit a re producible non-Gaussian distribution of MLC phosphorylation across a population of unsynchronized genetically identical cells. Adding an inhibitor of Rho kinase, Y27632, or plating cells on a low density of fibronectin, reduced phospho-myosin light chain signal as expected. On the other hand, adding calyculin A, an activator of contractility, increased myosin light chain phosphorylation. The IC50 for myosin light chain phosphorylation using Y27632 was determined to be 2.1 +/- 0.6 micrometers. We observed a positive linear relationship between cell area and myosin light chain diphosphorylation, which is consistent with what has been reported in the literature using other methods. CONCLUSION Our results show that using proper specimen fixation techniques and background subtraction methods, imaging cytometry can be used to reliably measure relative myosin light chain phosphorylation in individual adherent cells. Importantly, the ability to make this measurement in adherent cells allows for simultaneous measurement of and correlation with other parameters of cellular topography such as morphology and cell-cell proximity. This assay has potential application in screening for drug development.
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Abstract
In this chapter, we describe the preparation of thin films of collagen that can serve as reference materials for assuring reproducible and predictable cell responses. Subtle differences in the molecular-scale characteristics of extracellular matrix proteins, including the supramolecular structure of type 1 collagen, can have tremendous influences on cell state and cell-signaling pathways; therefore the careful control and analysis of the culture surface is critical to assure a relevant and consistent response in cell-based assays. We also describe how cell-phenotypic parameters such as morphology, proliferation, and green fluorescent protein expression can be unambiguously quantified in adherent cells by automated fluorescence microscopy or high content screening. Careful consideration of protocols, and the use of fluorescent reference materials, are essential to assure day-to-day and instrument-to-instrument interoperability. The ability to collect quantitative data on large numbers of cells in homogeneous matrix environments allows assessment of the range of phenotypes that are reproducibly expressed in clonal cell populations. The inherent distribution of responses in a cell population will determine how many cells must be measured to reach an accurate determination of cellular response.
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Affiliation(s)
- Anne L Plant
- National Institute of Standards and Technology, Gaithersburg, MD, USA
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McDaniel DP, Shaw GA, Elliott JT, Bhadriraju K, Meuse C, Chung KH, Plant AL. The stiffness of collagen fibrils influences vascular smooth muscle cell phenotype. Biophys J 2006; 92:1759-69. [PMID: 17158565 PMCID: PMC1796816 DOI: 10.1529/biophysj.106.089003] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [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: 11/18/2022] Open
Abstract
Cells receive signals from the extracellular matrix through receptor-dependent interactions, but they are also influenced by the mechanical properties of the matrix. Although bulk properties of substrates have been shown to affect cell behavior, we show here that nanoscale properties of collagen fibrils also play a significant role in determining cell phenotype. Type I collagen fibrils assembled into thin films provide excellent viewing of cells interacting with individual fibrils. Cells can be observed to extensively manipulate the fibrils, and this behavior seems to result in an incompletely spread stellate morphology and a nonproliferative phenotype that is typical of these cells in collagen gels. We show here that thin films of collagen fibrils can be dehydrated, and when seeded on these dehydrated fibrils, smooth muscle cells spread and proliferate extensively. The dehydrated collagen fibrils appear to be similar to the fully hydrated collagen fibrils in topology and in presentation of beta(1) integrin ligation sites, but they are mechanically stiffer. This decrease in compliance of dehydrated fibrils is seen by a failure of cell movement of dehydrated fibrils compared to their ability to rearrange fully hydrated fibrils and from direct measurements by nanoindentation and quantitative atomic force measurements. We suggest that increase in the nanoscale rigidity of collagen fibrils can cause these cells to assume a proliferative phenotype.
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Affiliation(s)
- Dennis P McDaniel
- Biochemical Science Division and Manufacturing Metrology Division/National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Elliott JT, Woodward JT, Umarji A, Mei Y, Tona A. The effect of surface chemistry on the formation of thin films of native fibrillar collagen. Biomaterials 2006; 28:576-85. [PMID: 17049596 DOI: 10.1016/j.biomaterials.2006.09.023] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Accepted: 09/20/2006] [Indexed: 11/23/2022]
Abstract
In this study, we used well-defined, homogeneous, gradient and patterned substrates to explore the effects of surface chemistry on the supramolecular structure of adsorbed type I collagen. Type I collagen (320microg/mL) was allowed to adsorb onto self-assembled CH(3)-, COOH-, NH(2)- and OH-terminated alkylthiolate monolayers at 37 degrees C. Atomic force microscopy, ellipsometry and phase microscopy indicated that large supramolecular collagen fibril structures (approximately 200nm in diameter, several microns long) assembled only at the hydrophobic CH(3)-terminated surfaces. By varying the surface energy using a mixture of OH- and CH(3)-terminated thiols during monolayer formation, we found that large fibril assembly occurred at surfaces with a water contact angle above 83 degrees , but not on surfaces with a water contact angle below 63 degrees . Examining a surface with a linear hydrophobicity gradient revealed that the assembly of large collagen fibrils requires a hydrophobic surface with a water contact angle of at least 78 degrees . Collagen fibril density increased over a narrow range of surface energy and reached near-maximum density on surfaces with a water contact angle of 87 degrees . These studies confirm that the supramolecular structure of adsorbed collagen is highly dependent on the underlying substrate surface chemistry. We can take advantage of this dependency to pattern areas of fibrillar and non-fibrillar collagen on a single surface. Morphology studies with vascular smooth muscle cells indicated that only collagen films formed on hydrophobic substrates mimicked the biological properties of fibrillar collagen gels.
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Affiliation(s)
- John T Elliott
- Biochemical Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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Mei Y, Elliott JT, Smith JR, Langenbach KJ, Wu T, Xu C, Beers KL, Amis EJ, Henderson L. Gradient substrate assembly for quantifying cellular response to biomaterials. J Biomed Mater Res A 2006; 79:974-88. [PMID: 16948143 DOI: 10.1002/jbm.a.30883] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [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: 11/10/2022]
Abstract
Using quantitative fluorescence microscopy in conjunction with a method of gradient substrate assembly established in their group, the authors were able to introduce and measure reproducible changes in cellular morphology and cell density by manipulating polymer grafting density. The mechanism behind this change in cellular behavior was explained by a semiempirical, geometric model that describes the effect of the spatial distribution of the polymer on protein attachment. A 10-fold increase in graft density of poly(2-hydroxyethyl methacrylate) [PHEMA] along the surface of a gradient sample, preexposed to bovine fibronectin, caused a change in the size of fibroblasts on the surface (i.e., cell spreading) from (1238 +/- 704) to (377 +/- 216) microm(2). The results were in quantitative agreement with those obtained on three separate gradient samples. Both cellular response and fibronectin adsorption (as measured via ellipsometry) were found to vary sigmoidally with graft density of PHEMA, demonstrating the high degree of correlation between the two phenomena. A simple, rigid-disk model accounting for the surface coverage of PHEMA was able to predict the amount of adsorbed fibronectin with a correlation coefficient of 0.97. Maximal cell adhesion and cell spreading were found to occur at fibronectin surface densities of 50 and 100 ng/cm(2), respectively. The results demonstrate the role of gradient substrate assembly as a method for quantifying the relationship between protein and cellular response to technologically relevant polymeric materials.
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Affiliation(s)
- Ying Mei
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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49
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Langenbach KJ, Elliott JT, Tona A, McDaniel D, Plant AL. Thin films of Type 1 collagen for cell by cell analysis of morphology and tenascin-C promoter activity. BMC Biotechnol 2006; 6:14. [PMID: 16519810 PMCID: PMC1523190 DOI: 10.1186/1472-6750-6-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Accepted: 03/06/2006] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The use of highly reproducible and spatiallyhomogeneous thin film matrices permits automated microscopy and quantitative determination of the response of hundreds of cells in a population. Using thin films of extracellular matrix proteins, we have quantified, on a cell-by-cell basis, phenotypic parameters of cells on different extracellular matrices. We have quantitatively examined the relationship between fibroblast morphology and activation of the promoter for the extracellular matrix protein tenascin-C using a tenascin-C promoter-based GFP reporter construct. RESULTS We find that when considering the average response from the population of cells, cell area correlates with tenascin-C promoter activity as has been previously suggested; however cell-by-cell analysis suggests that cell area and promoter activity are not tightly correlated within individual cells. CONCLUSION This study demonstrates how quantitative cell-by-cell analysis, facilitated by the use of thin films of extracellular matrix proteins, can provide insight into the relationship between phenotypic parameters.
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Affiliation(s)
- Kurt J Langenbach
- Biotechnology Division/National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - John T Elliott
- Biotechnology Division/National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Alex Tona
- Geo-centers, Inc. Newton, MA 02459, USA
| | - Dennis McDaniel
- Biotechnology Division/National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Anne L Plant
- Biotechnology Division/National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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Mei Y, Wu T, Xu C, Langenbach KJ, Elliott JT, Vogt BD, Beers KL, Amis EJ, Washburn NR. Tuning cell adhesion on gradient poly(2-hydroxyethyl methacrylate)-grafted surfaces. Langmuir 2005; 21:12309-14. [PMID: 16343007 DOI: 10.1021/la050668x] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A simple yet versatile method was developed to prepare a low-density polymerization initiator gradient, which was combined with surface-initiated atom transfer radical polymerization (ATRP) to produce a well-defined poly(2-hydroxyethyl methacrylate) (HEMA) gradient substrate. A smooth variation in film thickness was measured across the gradient, ranging from 20 A to over 80 A, but we observed a nonmonotonic variation in water contact angle. Fits of X-ray reflectivity profiles suggested that at the low graft density end, the polymer chain structure was in a "mushroom" regime, while the polymer chains at high graft density were in a "brush" regime. It was found that the "mushroom" region of the gradient could be made adhesive to cells by adsorbing adhesion proteins, and cell adhesion could be tuned by controlling the density of the polymer grafts. Fibroblasts were seeded on gradients precoated with fibronectin to test cellular responses to this novel substrate, but it was found that cell adhesion did not follow the expected trend; instead, saturated cell adhesion and spreading was found at the low grafting density region.
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Affiliation(s)
- Ying Mei
- Polymers Division and Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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