About FDA
National Center for Toxicological Research (NCTR)
2012 Preceptors
- Saeed A. Khan, Ph.D.
- Suzanne Morris, Ph.D.
- Baitang Ning, Ph.D.
- Angel M. Paredes, Ph.D.
- Serguei Liachenko, M.D., Ph.D.
![]() | Angel M. Paredes, Ph.D.Director of Electron Microscopy Group, NCTR/ORA Nanotechnology Core Facility, Office of Scientific Coordination, NCTR, FDA Background: |
Research Interests: Nanotechnology involves the study and manipulation of certain nano-scaled materials (~1-100 nm) for use in manufactured products. Some of these products include pharmaceuticals and medical devices, and from the FDA point of view, the potential adverse effect of these materials on human health is very important. For instance, many nanomaterials such as nano-silver, nano-gold, and nano-iron are being developed as drug delivery/organ targeting systems. My research goal is to use electron microscopy (EM) and computer aided 3D image reconstruction to investigate the structural basis of human cellular interaction with nanomaterials. As nanomaterials are introduced into a mammalian system, knowledge of the uptake, distribution, and disposition of the nanomaterial is critical for understanding potential benefit and risk. We will be using a state-of-the-art FEG Scanning Electron Microscope (SEM) with a novel new auto-ultramicrotome serial sectioning device (Gatan 3Veiw2) to look at the 3D structure of cells and organelles treated with nanomaterials. In particular, we are interested in the distribution of nanomaterial within the animal model and the effects these materials have at the cellular and organ level. Proposed Research Project for FDA Fellow: The Gatan 3View system is a new and extremely powerful technology that for the first time allows automated serial sectioning at the ultramicrotome level (10-50 nm sections) and visualization of tissues. The project for this Commissioners Fellow is to (1) use existing classical electron microscope (EM) technology to visualize nanomaterials and (2) compare the results with the new SEM serial sectioning methods. The methodology that will be employed is immuno-EM, where nanogold (5 nm) tagged antibodies are used to precisely map the location of epitopes (e.g. proteins, macromolecular structures, etc.) within the cellular structure using TEM and SEM. Because this technology is so new, techniques need to be developed to improve the power and range of the combination of SEM with serial sectioning with immuno-EM labeling. It is believed that merging immuno-EM with the resolution power of the serial sectioning system will create a new combinatorial technique for localizing the distribution of important epitopes within organisms. This technique could then be used to answer relevant questions about impact of nanomaterials (and other compounds) on cellular structure and function. The National Center for Molecular Imaging at Baylor University and the High Resolution Cryo-Electron Microscopy Facility at University of Texas Health Sciences Center are state-of-the-art electron microscope facilities. During my tenure at Baylor, I trained over two-dozen graduate students and a dozen post-doctoral fellows and faculty on cryo-EM sample preparation and microscopy. While a graduate student at University of Texas, I taught graduate level courses on EM, where students (10-15/class) were given lecture and hands-on training in EM. At the University of Texas Health Sciences Center, I was the primary person responsible for the 300 kV Polara G2 very high resolution EM, and trained approximately one dozen post-doctoral fellows and faculty on the proper use of this expensive EM. At NCTR, I have already trained seven staff on the use of the 200 kV transmission electron microscope and seven staff on the variable-vacuum SEM, both of which are capable of cryo-EM. Currently a 120 kV transmission electron microscope is being installed, and the FEG SEM described above will provide sufficient EM platforms for training of the Commissioners Fellow on state-of-the-art EM. Applicant Requirements: The applicant should have a degree related to biological sciences with some experience in electron microscopy. Selected Recent Publications: 1. Hernandez, R., Paredes, A.M., (2009) Sindbis virus as a model for studies of conformational changes in a metastable virus and the role of conformational changes in in vitro antibody neutralisation. Rev. Med. Virology. 19(5):257-72. | |
![]() | Serguei Liachenko, M.D., Ph.D.BioImaging Lab / Division of Neurotoxicology NCTR Background/Experience: MD/PhD in biochemistry/pharmacology (Russian State Medical University and National Center for Bioactive Compounds, Moscow, Russia) 7.5 years with Pfizer, Inc (Sr. Principal Scientist, Head of MRI) Mentorship Experience: 3 summer students, 1 graduate student, 3 postdoctoral fellows. |
Research Interests: - Utilization of Magnetic Resonance Imaging and Spectroscopy (MRI/MRS) in preclinical study design. Proposed Research Project for FDA Fellow: Development of MRI/MRS biomarkers of neurotoxicity in rats. Prototypic neurotoxic compounds will be used to induce brain lesions with the intent of identifying associated metabolic changes in affected tissue. Evaluation of quantitative imaging (MRI/MRS, positron emission tomography) for identifying new potentially translational biomarkers and predictors of efficacy and safety. Applicant Requirements: - basic knowledge of MRI physics Selected Recent Publications: 1. Xie Z, Liachenko S, Chiao PC, Carvajal-Gonzalez S, Bove S, Bocan T. In vivo MRI assessment of knee cartilage in the medial meniscal tear model of osteoarthritis in rats. Med Image Comput Assist Interv. 2010; 13(Pt 3): 57-64. | |












