PEOPLE

Al Powers

From Memphis, TN
Al Powers, M.D.

Joe C. Davis Chair in Biologic Science and Professor of Medicine, Molecular Physiology and Biophysics at Vanderbilt University

Director, Vanderbilt Diabetes Center

Chief of the Vanderbilt Division of Diabetes, Endocrinology, and Metabolism

Director, Vanderbilt Diabetes Research and Training Center

Dr. Powers is a physician-scientist whose research on type 1 and type 2 diabetes focuses on pancreatic islet biology, development, and function is funded by the NIH, JDRF, VA Research Service, and The Leona M. and Harry B. Helmsley Charitable Trust. He is part of the Human Islet Research Network, serving as Chair of the Transnetwork Steering Committee. He directs the NIH-funded Vanderbilt Diabetes Research and Training Center, an interdisciplinary program involving more than 120 faculty. 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.

Marcela Brissova

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

Dr. Brissova's research focuses on the biology of pancreatic islets and pancreas and islet development, especially the development of pancreatic islet vasculature and innervation and their role in regulation of pancreatic islet function. Her research also seeks to understand the regulation of islet cell gene expression to provide insight into processes controlling normal pancreatic beta cell function. She is especially expert in studies on the human pancreas and islet and integrating these with findings in rodent models of islet biology. Her research is funded by the NIH, JDRF, and The Leona M. and Harry B. Helmsley Charitable Trust; she is part of the Human Islet Research Network. As Director of the NIDDK-funded Human Islet Phenotyping Program, she oversees the phenotyping of all human islet preparations distributed by the IIDP. Dr. Brissova received her Ph.D. from Slovak University of Technology and did postdoctoral training in the Department of Chemical and Biomolecular Engineering at Vanderbilt University.




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.

Amber Bradley, B.S., M.S

From Memphis, TN
Amber Bradley, B.S., M.S
Lab Manager
Education

M.S. in Biomolecular Sciences, Lipscomb University and B.S. in Molecular Biology, Lipscomb University

Amber joined the Powers group in January 2019 where she supports pancreatic islet research using her molecular biology skill set and experience with mouse models. Prior to joining the Powers lab, Amber worked at Lipscomb University’s Pharmaceutical Sciences Research Center as a lab manager and supported the Bioanalytical Core with development of tissue culture, flow cytometry and plate based assays. Previously, Amber worked at Vanderbilt studying the importance of MTG transcriptional corepressors in colonic crypt proliferation in the Williams lab (Division of Gastroenterology, Hepatology and Nutrition). She is applying her skill set to study islet biology and dysfunction in diabetes.



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 & Brissova 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.



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.

Meg Heaberlin, B.A.

From Houston, TX
Meg Heaberlin, B.A.
Lead Administrative Assistant
Education

B.A. in Health Communication, University of Houston

Originally from Houston, TX, Meg worked full-time as an office assistant while she completed her Bachelor's degree from the University of Houston. Upon graduation, she worked for two years at the University of Texas Health Science Center in the Texas Medical Center. After the birth of their son, Meg and her husband moved to Nashville to be closer to family. Currently, Meg works to support Dr. Powers and the members of his lab.



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.

Shristi  Shrestha, Ph.D.

From Kathmandu, Nepal
Shristi Shrestha, Ph.D.
Postdoctoral Fellow
Education

Ph.D. in Biotechnology Science and Engineering, University of Alabama - Huntsville

Shristi completed her dissertation research under Dr. Shawn Levy at HudsonAlpha Institute for Biotechnology, where she studied transcriptomics of human pancreatic islets from individuals with Type 1 diabetes in collaboration with the Powers lab. Shristi is interested in molecular characterization of human pancreatic islets through single cell RNA-sequencing analysis and investigating their transcript level changes at various ages and diabetic states.



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.