PEOPLE

Al Powers
Al Powers, M.D.

Alvin C. Powers, the Joe C. Davis Chair in Biologic Science and Professor of Medicine, Molecular Physiology and Biophysics at Vanderbilt University, is the Director of the Vanderbilt Diabetes Center, the Chief of the Vanderbilt Division of Diabetes, Endocrinology, and Metabolism, and the Director of the Vanderbilt Diabetes Research and Training Center, a NIH-funded center that facilitates the diabetes-related research of more than 120 Vanderbilt scientists. He is a physician-scientist whose research on type 1 and type 2 diabetes focuses on pancreatic islet biology, development, and function. His research is or has been supported by the NIH, the VA Research Service, the JDRF, and the American Diabetes Association (ADA). Dr. Powers is also the Director of the Vanderbilt Medical Student Research Training Program in Diabetes, Endocrinology, and Metabolism and the Coordinator for the NIDDK Medical Student Research Program in Diabetes. These two programs enable more than 100 medical students to conduct diabetes-related research each summer at a NIDDK-supported Diabetes Research Center. Dr. Powers, a physician at Vanderbilt University Medical Center and the VA Tennessee Valley Healthcare System, is listed by Castle Connolly Medical Ltd as one of “America’s Top Doctors.” Dr. Powers has served on advisory panels or study sections for the NIH, the JDRF, the Endocrine Society, and the ADA. In 2017, he served as President, Medicine & Science of the American Diabetes Association. Dr. Powers received his undergraduate degree from the University of Virginia and his medical degree from the University of Tennessee Center for the Health Sciences. After training in internal medicine at Duke University Medical Center, Dr. Powers trained in Endocrinology and Diabetes at the Joslin Diabetes Center, the Massachusetts General Hospital, and Harvard Medical School.




Radhika Aramandla, M.S.

From Guntur, India
Radhika Aramandla, M.S.
Senior Research Specialist
Education

M.S., Vanderbilt University
B.S., Nagarjuna University, Majored in Math, Physics, & Chemistry

Radhika's research interests are the molecular aspects of type 1 and type 2 diabetes. She is involved in projects dealing with human islet transplantation, in vitro analysis and imaging in order to study human islet survival, function, regeneration and proliferation. She has generated various animal models including mice that express the firefly luciferase transgene in the pancreatic islets to study β cell survival and mass regulation by in vivo imaging. In addition to her research responsibilities, Radhika also manages the organizational needs of the lab and trains graduate students/fellows in a variety of lab technologies.

Marcela Brissova, Ph.D.

From Martin, Slovakia
Marcela Brissova, Ph.D.
Research Associate Professor, Division of Diabetes, Endocrinology & Metabolism
Director, Islet Procurement and Analysis Core, Vanderbilt Diabetes Research & Training Center
Education

Ph.D., Slovak University of Technology, Bratislava, Slovakia

A faculty member since 2001, Dr. Brissova first joined Vanderbilt for postdoctoral training in the Department of Chemical and Biomolecular Engineering. Dr. Brissova’s research interests include the biology of pancreatic islets with a focus on the regulation of beta cell gene expression to provide insight into processes controlling normal pancreatic beta cell function in rodent models and translating this research to human islet biology. Her research also includes the study of molecular events involved in the development of pancreatic islet vasculature and innervation and their role in regulation of pancreatic islet function. She also directs the Islet Procurement and Analysis Core of the Vanderbilt Diabetes Research & Training Center.



Jean-Philippe Cartailler, Ph.D.

From Paris, France
Jean-Philippe Cartailler, Ph.D.
Director, Creative Data Solutions
Education

Ph.D. in Biological Sciences, University of California Irvine
B.Sc. in Biology, Rutgers University

JP is involved in multiple informatics and data-management projects, from laboratory information management to databases to visualization solutions. His expertise in systems development in the area of diabetes-related basic research, alongside of his leadership roles in the Beta Cell Biology Consortium and dkCOIN, is well suited to the activities and mission of the research group.

Chunhua Dai, M.D.

From Hunan, China
Chunhua Dai, M.D.
Research Associate Professor
Education

M.D., Hunan Medical University
M.S., Hunan Medical University
Residency, Hunan Medical University, Internal Medicine
Fellowship, Hunan Medical University, Hematology

Dr. Dai began her career at Vanderbilt University Medical Center in the Division of Hematology/Oncology before joining the Powers Research Group in the Division of Diabetes, Endocrinology, & Metabolism. Her research focuses on the molecular, cellular, and vascular changes in human islets when they are challenged with hyperglycemia and/or insulin resistance in vivo. She is investigating in vivo age-dependent human beta cell proliferation and how current therapeutic agents for type 2 diabetes preserve and/or enhance human beta cell function or survival in vivo.



Danielle Dean, Ph.D.

From Murfreesboro, TN
Danielle Dean, Ph.D.
Research Instructor
Education

Ph.D. in Molecular and Systems Pharmacology, Emory University
M.S. in Biochemistry, Cellular and Molecular Biology, University of Tennessee – Knoxville
B.S. in Biochemistry, Cellular and Molecular Biology, University of Tennessee – Knoxville

While at Emory University, Danielle was awarded Toxicology Scholar for her work on neurodegeneration. She now studies signals that regulate the growth of alpha cells in the pancreatic islet. Recently, she discovered that amino acids stimulate both human and mouse alpha cell proliferation.

In her free time, Danielle loves to volunteer, cook, garden, homebrew, and can/pickle just about any food.

Rachana Haliyur, Ph.D.

From Chantilly, VA
Rachana Haliyur, Ph.D.
MSTP Student
Education

Ph.D. in Molecular Physiology & Biophysics, Vanderbilt University
B.S. in Biochemistry, University of Maryland Baltimore County

Recent observations have challenged long-held concepts in the pathophysiology of type 1 diabetes. By implementing an integrative approach to study both the native pancreas and isolated islets from the same human donor, Rachana works to characterize the function and morphology of T1D pancreatic islets using in vitro and in vivo functional studies and immunohistochemistry. Her primary project focuses on the glucagon-producing alpha cells in the T1D islet and identifying the mechanisms behind disordered glucagon secretion in T1D.



Regina Jenkins, HT (ASCP)

From Nashville, TN
Regina Jenkins, HT (ASCP)
Histotechnologist Research
Education

HT (ASCP), American Society for Clinical Pathology, Board of Certification
A.A.S in Office Administration, Nashville State Community College

Regina has worked as a histotechnician (HT) for 25 years in both the clinical and research realms. Regina also assisted pathologists on a part-time basis as a college student which led her to decide on this career path. Regina received her HT certification from the American Society for Clinical Pathology (ASCP) in May of 2004. That same year she began working at Vanderbilt and in December 2016 she joined the Powers lab.

Jill Lindner, B.S., M.Ed.

From New York City, NY
Jill Lindner, B.S., M.Ed.
Projects Manager
Education

M. Ed. in Secondary Education, Vanderbilt University
B.S. in Biology, University of Tennessee – Knoxville

Jill joined the Division of Diabetes, Endocrinology and Metabolism in 2016, where she serves as a Projects Manager for various scientific projects within the Al Powers group.

She is a long standing Vanderbilt employee whose career spans clinical research (David Rabin Lab - Division of Endocrinology), basic research (Mark Magnuson Lab - Vanderbilt Center for Stem Cell Biology), secondary education (Science Educator - John Overton High School, Nashville, TN) and website application support (Vanderbilt Center for Stem Cell Biology).



Jimmy Messmer, B.S., B.A.

From Charlotte, NC
Jimmy Messmer, B.S., B.A.
Associate Application Developer
Education

B.S. Computer Science & B.A. History, University of North Carolina at Chapel Hill

Jimmy recently graduated from UNC in 2018 with degrees in computer science and history. In the Powers lab, he is applying his talents with web development to create an online atlas for the human pancreas, which would allow users to engage with images of the pancreas through an online interface.

Heather Nelson, Ph.D.

From Canyon Country, CA
Heather Nelson, Ph.D.
Postdoctoral Fellow
Education

Ph.D. Anatomy and Cell Biology, SUNY Upstate Medical University
B.S. Biology and Chemistry, Elmira College

Heather completed her dissertation research in Michael Roe's lab at SUNY Upstate Medical University, where she studied a protein involved in regulation of calcium signal transduction. She joined the Powers lab as a postdoctoral fellow in July 2018. Heather is interested in conducting translational diabetes-related research.



Greg Poffenberger, M.S.

From Hagerstown, Maryland
Greg Poffenberger, M.S.
Senior Research Specialist
Education

M.S. in Laboratory Investigation, Vanderbilt University
B.S. in Biochemistry, Lipscomb University

Greg has worked in the Powers Group since 2003. His areas of expertise are small animal surgeries, functional islet analysis/assays in vitro and in vivo.

Greg took a very different path in his pursuit of a career in research. He comes from a family of entrepreneurs that include businesses in office solutions and restaurants. He started working as an electrician in his hometown of Hagerstown, MD. He then moved to Nashville to manage national restaurant chains. Greg then changed career paths with Avco Corporation, a Nashville based aircraft company. He later worked at the Smyrna, TN Airport and served as a structural airframe manager.

Greg studied Biochemistry at Lipscomb University and later earned his master’s degree at Vanderbilt University. He started in research at Vanderbilt in the Infectious Disease Department and then later joined the Vanderbilt Hormone Assay & Analytical Services Core while being mentored by Wendell Nicholson in hormonal assay development.

Greg is an integral part in all human islet studies. He collaborates with other laboratories within and outside of Vanderbilt University.

Tiffany Richardson, A.B.

From Spotsylvania, Virginia
Tiffany Richardson, A.B.
MPB Graduate Student
Education

A.B. in Molecular Biology and minor in Engineering Biology from Princeton University

Tiffany joined the Powers Lab in the Spring of 2018. Her past research investigated the biophysical dynamics and interactions within the nucleolus using a novel optogenetic system. She is now interested in elucidating the molecular aspects of islet proliferation, tissue regeneration, and cellular interactions within the pancreas.



Diane Saunders, Ph.D.

From Durham, NC
Diane Saunders, Ph.D.
Postdoctoral Fellow
Education

Ph.D. in Molecular Physiology & Biophysics, Vanderbilt University
B.A. in Studio Art & B.S. in Biology, Bates College

Diane completed her dissertation research in the Powers Lab, where she investigated the role of pancreatic endothelial cells in the islet microenvironment by determining their role in macrophage recruitment and beta cell regeneration. As a fellow, she is continuing work to characterize gene expression changes in isolated subpopulations of human islet cells during developmental stages and disease progression, and is also helping to organize histology-based data detailing juvenile pancreatic development.

Alena Shostak, M.S.

From Minsk, Belarus
Alena Shostak, M.S.
Laboratory Manager
Education

Postgraduate training in Immunocytochemistry, Department of Neurochemistry, Max-Planck Institute for Psychiatry
M.S. in Chemistry, Belarussian State University

Alena began her career at Vanderbilt as a research assistant in the Department of Cell and Developmental Biology. In 2002, she joined the Powers Lab and currently works with Dr. Dai on research projects involving human islet response to insulin resistance, hyperglycemia, and drugs used to treat type 2 diabetes.



Walter Siv

From Chattanooga, TN
Walter Siv
Undergraduate Student
Education

Anticipated B.A. in Neuroscience, Vanderbilt University

Walt began his undergraduate education at Vanderbilt University in 2016, and after joining the Powers lab in Spring of 2018, he is working with both mouse models and human tissues to study the mechanisms of alpha cell proliferation. His primary research focus is in glutamine metabolism in pancreatic islets, specifically investigating the role of glutaminase in alpha cell proliferation.

Erick Spears, Ph.D.

From Denver, CO
Erick Spears, Ph.D.
Staff Scientist
Education

Ph.D. in Molecular, Cellular and Developmental Biology, University of Kansas
M.A. in Biology, University of Colorado - Denver
B.A. in Environmental, Populational and Organismic Biology, University of Colorado - Boulder

Erick's general interests include in vitro modeling of human development and disease. He studied the molecular mechanisms involved in translational regulation of APC expression in human colorecatal cancer cell lines at the University of Kansas. During a postdoc in Cell and Developmental Biology at Vanderbilt he used directed differentiation of human iPS cells to produce intestinal organoid and used them to study the role of Myc in colorectal cancer. In the Powers Lab, Erick is employing similar techniques to model human endocrine pancreas development and diabetes. Specifically, he is using molecular genetic manipulation to understand the role of alpha and beta cell dedifferentiation in diabetes.



Jack Walker, B.S.

From Kansas City, KS
Jack Walker, B.S.
M.D./Ph.D. Student
Education

B.S. in Chemical Engineering, Washington University in St. Louis

Jack became interested in the pancreas and pancreatic islet because of its unique role in helping control and coordinate both metabolism and digestion. He joined the Powers Lab in September 2016. Using the unique infrastructure in the Powers lab, Jack is characterizing the functional, morphologic, and transcriptional profiles of islets, sorted α and β cells, and pancreatic tissue from individuals with type 2 diabetes. Jack is also using viral manipulation of human islets to understand mechanisms of islet dysfunction in type 2 diabetes. Jack plans to become a pediatrician upon his return to medical school.

Jordan Wright, M.D., Ph.D.

From Spanish Fork, UT
Jordan Wright, M.D., Ph.D.
Postdoctoral Fellow
Education

B.A. in Biology, University of Utah, M.D. and Ph.D. in Molecular and Integrative Physiology, University of Michigan

Jordan's research career began as an undergraduate, studying cardiovascular complications of diabetes in the lab of Dale Abel at the University of Utah. He completed his PhD with Peter Arvan at the University of Michigan, studying the role of ER stress and protein misfolding in monogenic forms of diabetes caused by misfolded proinsulin. He joined the Powers lab, after completing residency and a clinical year of endocrinology fellowship, to study human islet physiology and its interaction with the exocrine pancreas in type 1 diabetes.