Research Biologist — Office of Scientific Coordination

Angel Paredes, Ph.D.
(870) 543-7121
NCTRResearch@fda.hhs.gov  

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About  |  Publications | Standards Development Activities 

Background

Dr. Angel Paredes started his training in electron microscopy in 1983 in the Department of Microbiology at the University of Texas at Austin as a graduate student. Later, during his doctoral studies, he conducted electron cryomicroscopy (cryoEM) to determine the structure of the Sindbis virus, a prototype alphavirus. For the next 18 years, he continued his work in electron cryomicroscopy, first at Baylor College of Medicine and later at the University of Texas Health Science Center in Houston (UTHSC). During his tenure at Baylor, he was called upon to help manage the facility’s high-end electron microscopes where he was one of three managers able to maintain the microscope and train students. He was later hired by UTHSC to manage their new electron cryomicroscopy laboratory, first as manager and later as a tenured track assistant professor. For over 15 years, he has played a major role in managing electron microscopes and conducting research with these instruments. He joined NCTR in 2011 and presently oversees the electron microscopy laboratory.

Research Interests

Dr. Paredes is interested in conducting FDA-relevant research that explores the structural impact of drug treatment and drug-host interactions. In any biological or biochemical process that occurs in the body, whether natural or induced by a manmade pharmacological reaction, there is always a structural impact. This is a consequence of the structure-function relationship that drives all biology. Whether that structural effect is beneficial or deleterious is the basis for the therapeutic effect any drug is designed to elicit. Specifically, Dr. Paredes is interested in identifying the global structural changes that accompany the treatment of humans and veterinary animals to FDA-regulated products including food, drugs, makeup, and nanotechnology. He can use his expertise in electron microscopy to investigate these changes in tissues and organs at the sub-microscopic level. He would like to continue to develop one technology in particular — Serial Block Face Scanning Electron Microscopy (SBFSEM). This instrument, which he presently uses to conduct research, allows his laboratory to slice through tissues from treated animals, gathering images after each slice. The result is digital reconstructions of affected tissues that can be analyzed by very powerful image analysis software. Using this technology he plans to highlight the toxicological effects of FDA-regulated drugs. The data from his research will help FDA ensure product safety in the future.

Professional Societies/National and International Groups

American Society for Testing and Materials
Member
2016 – Present

Select Publications

Publication titles are linked to text abstracts on PubMed.

Virulence Characteristics of mecA-Positive Multidrug-Resistant Clinical Coagulase-Negative Staphylococci. 
Chon J-W., Lee U.J., Bensen R., West S., Paredes A., Lim J., Khan S., Hart M., and Sung K.
Antimicrobial Agents. 2020, In Press.

Characterization of Nanomaterials: Tools and Challenges.
Mudalige T., Qu H., Van Haute D., Ansar S.M., Paredes A., and Ingle T.
[Book Chapter]. Nanomaterials for Food Application. 2019, 313-353.

A Randomized Controlled Laboratory Study on the Long-term Effects of Methylphenidate on Cardiovascular Function and Structure in Rhesus Monkeys. 
Wilkinson J.D., Callicott R., Salminen W.F., Sandhu S.K., Greenhaw J., Paredes A., Davis K., Jones Y., Paule M.G., Slikker W. Jr., Rusconi P.G., Czachor J., Bodien A., Westphal J.A., Dauphin D.D., and Lipshultz S.E. 
Pediatr Res. 2019, 85(3):398-404. 

Electron Microscopy Techniques Employed to Explore Mitochondrial Defects in the Developing Rat Brain Following Ketamine Treatment.
Eustaquio T., Wang C., Dugard C.K., George N.I., Liu F., Slikker W. Jr., Paule M.G., Howard P.C., and Paredes A.M.  
Exp Cell Res. 2018, 373(1-2):164-70.

Investigating the Susceptibility of Mice to a Bacterial Challenge After Intravenous Exposure to Durable Nanoparticles. 
Khan S., Zhang Q., Marasa B.S., Sung K., Cerniglia C.E., Ingle T., Jones M.Y., Paredes A.M., Tobin G.A., Bancos S., Weaver J.L., Goering P.L., Howard P.C., Patri A.K., and Tyner K.M. 
Nanomedicine. 2017, 12(17):2097-111. 

Size- and Coating-Dependent Cytotoxicity and Genotoxicity of Silver Nanoparticles Evaluated Using In Vitro Standard Assays.
Guo X., Li Y., Yan J., Ingle T., Jones M.Y., Mei N., Boudreau M.D., Cunningham C.K., Abbas M., Paredes A., Zhou T., Moore M.M., Howard P.C., and Chen T.  
Nanotoxicology. 2016, 10(9):1373-84.

Differential Effects of Silver Nanoparticles and Silver Ions on Tissue Distribution and Toxicity in the Sprague Dawley Rat Following Daily Oral Gavage Administration for 13-Weeks.
Boudreau M., Imam M., Paredes A., Bryant M., Cunningham C., Felton R., Jones M., Davis K., and Olson G.
Toxicol. Sci. 2016, 1:131-60.

Microscopy: Transmission Electron Microscopy.
Paredes A.  
Encyclopedia of Food Microbiology. 2013, Second Edition. Netherlands: Elsevier.

Fatty Aldehydes in Cyanobacteria are a Metabolically Flexible Precursor for Adversity of Biofuel Products.
Kaiser B., Carleton M., Hickman J., Miller C., Lawson D., Budde M., Warrener P., Paredes A., Mullapudi S., Navarro P., Cross F., and Roberts J.
PLoS One. 2013, Vol. 8(3):e58307.

Espiritio Santo Virus: A New Birnavirus that Replicates in Insect Cells.
Vancini R., Paredes A., Ribeiro M., Ferreira D., Hernandez R., and Brown D.
J Virol. 2012, 86(5):2390-9.

DNA Ejection by Cryo-Electron Tomography of Spore-Binding Phage. 
Fu X., Walter M., Paredes A., Morais M., and Lui J.
Virology. 2011, Vol. 421(2): pp141-148.

Reconstitution of the Platelet Glycoprotein Ib-IX Complex in Phospholipid Bilayer Nanodiscs.
Yan R., Mo X., Paredes A., Dai K., Lanza F., Cruz M., and Li R.
Biochemistry. 2011, Vol. 50(49):10598-606.

Plasma Restoration of Endothelial Glycocalyx in a Rodent Model of Hemorrhagic Shock. 
Kozar R., Peng Z., Holcomb J., Pati S., Park P., Ko T., and Paredes A.
Anesth. Analg. 2011, Vol. 112(6):1289-1295.

Sindbis Virus as a Model for Studies of Conformational Changes in a Metastable Virus and the Role of Conformational Changes in In Vitro Antibody Neutralization.
Hernandez R. and Paredes A.
Rev. Med. Virology. 2009, 19(5):257-72.

Intra- and Intermembrane Pairwise Molecular Recognition between Synthetic Hydrogen-Bonding Phospolipids.
Ma M., Paredes A., and Bong D.
J. American Chem. Soc. 2008, 44: 14456-8.

Sindbis Virus Conformational Changes Induced by a Neutralizing Anti-E1 Monoclonal Antibody.
Hernandez R., Paredes A., West M., and Brown D.
J. Virology. 2008, Vol. 82:5750-5760.

Structure of Halothiobacillus Neapolitanus Carboxysomes by Cryo-Electron Tomography.
Schmid M., Paredes A., Khant H., Soyer F., Aldrich H., Chiu W., and Shively J.
J. Molecular Biology. 2006, Vol. 364, No. 3, pp526-35.

Structural Biology of Old World and New World Alphaviruses.
Paredes A., Weaver S., Watowich S., and Chiu W.
Arch Virol Suppl. 2005, 19: 179-185.

Conformational Changes in Sindbis Virions Resulting from Exposure to Low pH and Interactions with Cells Suggest that Cell Penetration may Occur at the Cell Surface in the Absence of Membrane Fusion.
Paredes A., Ferreira D., Horton M., Saad A., Tsuruta H., Johnston R., Klimstra W., Ryman K., Hernandez R., Chiu W., and Brown D.
Virology. 2004, 324(2), 373-86.
 

Standards Development Activities

Co-led the development of ASTM Standard E3143-18b, "Standard Practice for Performing Cryo-Transmission Electron Microscopy of Liposomes," ASTM International, West Conshohocken, PA, 2018, DOI: 10.1520/E3143-18B, www.astm.org.