Jill A. Bush, Ph.D.
B.S., Exercise Physiology and Physical Therapy, Rutgers University, 1993
M.S., Endocrinology and Exercise Physiology, The Pennsylvania State University, 1995
Ph.D., Muscle Physiology, Endocrinology, Kinesiology, The Pennsylvania State University, 1999
Studies conducted by Dr. Bush in the Davis laboratory focused on the regulation of protein metabolism by growth hormone. Using stable isotope tracer/mass transorgan balance, she demonstrated that growth hormone increases protein anabolism by increasing protein synthesis in the skeletal muscle and intestine and has little effect on protein degradation. In collaboration with Dr. Scot Kimball, at Penn State, Dr. Bush further demonstrated that the stimulation of muscle protein synthesis by growth hormone involves mechanisms that enhance both mRNA and initiator methionyl-tRNA binding to the ribosome. In collaboration with Dr. Guoyao Wu at Texas A&M University, she further identified the mechanism by which growth hormone treatment decreases amino acid catabolism. Dr. Bush is currently chairman of the Department of Kinesiology, Towson University.
Jeffery Escobar, Ph.D.
B.S., Agronomic Engineering, University of Costa Rica, 1996
M.S., Animal Science, University of Illinois, 1998
Ph.D., Swine Nutrition and Immunobiology, University of Illinois 2003
As a postdoctoral fellow in the Davis laboratory, Dr. Escobar focused on the role of leucine in the regulation of protein synthesis in neonates. Using neonatal pigs as a model for the human neonate, his research demonstrated that physiological levels of leucine can act as nutrient signals to stimulate muscle protein synthesis in neonate. This anabolic effect appears unique for leucine, as other branched-chain amino acids have little independent effect. Further, Dr. Escobar demonstrated that the response to leucine is not sustained unless the leucine-induced fall in other amino acids is prevented. Studies conducted by Dr. Escobar showed that the leucine-induced stimulation of muscle protein synthesis is mediated by increased formation of the translation initiation factor complex that regulates mRNA binding to the ribosome and translation initiation. Dr. Escobar is currently an assistant professor at Virginia Polytechnic Institute and State University.
Jason W. Frank, Ph.D.
B.S., Animal Sciences, Purdue University
M.S., Animal Sciences, Purdue University
Ph.D., Animal Sciences (Swine Nutrition), University of Missouri
As a postdoctoral fellow in the Davis laboratory, Dr. Frank chose to investigate the chronic effects of dietary protein and lactose on protein synthesis and the mechanisms which regulate the response. His results demonstrated that dietary protein and lactose stimulate protein synthesis by increasing the activation of translation initiation factors and signaling proteins that regulate the binding of mRNA to the ribosomal complex. This response of protein synthesis is mediated by the postprandial rise in amino acids and insulin. In collaboration with Dr. Guoyao Wu, at Texas A&M University, Dr. Frank further demonstrated that stimulation of arginine synthesis by supplementation with N-acetylglutamate can increase growth and the synthesis of muscle proteins in neonatal pigs. Dr. Frank is currently at the University of Arkansas.
Asumpthia S. Jeyapalan, D.O.
Doctor of Osteopathy, Chicago College of Osteopathic Medicine, 2001
Pediatric Residency, University of Illinois at Chicago, 2004
Critical Care Medicine Fellowship, Baylor College of Medicine 2007
Dr. Jeyapalan, a fellow in Pediatric Critical Care Medicine, elected to perform her research in the laboratory of Dr. Davis. Her work demonstrated that glucose plays an important and independent role in the regulation of protein synthesis. She showed that glucose, independently of insulin and amino acids, stimulates protein synthesis in neonates and this response occurs by AMPK and mTOR-independent pathways. Dr. Jeyapalan is currently an assistant professor of Pediatrics at the University of Miami.
Pamela M. J. O’Connor, M.D.
M.B., B.Ch., B.A.O, National Univ. Ireland, Galway, 1993
D.CH., Internship, Child Health, Univ. College Dublin, National Univ. Ireland, 1994
Residency/Sr. House Officer, Paediatrics, Neonatology, Univ. College Hospital Galway, 1994
Paediatrics, Critical Care, Emergency Paediatric Medicine, Our Lady’s Hospital for Sick Children, Crumlin, 1995
Neonatology, Rotunda Hospital, Dublin, 1996
MRCPI Medicine of Childhood, Royal College of Physicians of Ireland, 1997
Neonatology, National Maternity Hospital, Holles St., Dublin, 1997
Oncology, Haematology, Neurology, Respiratory Medicine, Paediatrics, Critical Care, Emergency Paediatric Medicine, Our Lady’s Hospital for Sick Children, Crumlin, 1999
Studies conducted by Dr. O’Connor while she was a postdoctoral fellow provided strong evidence that the postprandial rise in both insulin and amino acids play important and independent roles in the feeding-induced stimulation of muscle protein synthesis in the neonate. Using the pancreatic-substrate clamp technique, which we developed, and the neonatal pig model, Dr. O’Connor showed that the protein synthetic response to insulin is specific to skeletal muscle and decreases with development whether as the anabolic response to amino acids occurs is virtually all tissues. Further, she identified the translation initiation factors that are involved in the stimulation of protein synthesis in neonatal tissues. Dr. O’Connor is currently the director of Neonatology, Our Lady's Hospital for Sick Children, Crumlin, Dublin, Ireland.
M. Carole Thivierge, Ph.D.
B. Sc., Agronomy, Faculte des Sciences de Agriculture et de Alimentation, Universite Laval, 1994
M.S., Animal Science, Faculte des Sciences de Agriculture et de Alimentation, Universite Laval, 1996
Ph.D. Candidate, Animal Science, Faculte des Sciences de Agriculture et de Alimentation, Universite Laval, 2001
In the Davis laboratory, Dr. Thivierge chose to investigate the role of proteolysis in the regulation of protein accretion during the neonatal period. In her research, she performed studies on the effect of feeding on protein synthesis and protein degradation in the hindlimb, as well as in the whole body, using amino acid tracer kinetics methodology in neonatal pigs. She also used a direct stable isotopic tracer incorporation technique to determine protein synthesis rates in individual muscles. Dr. Thiviege’s work demonstrated that the high rate of protein accretion and efficient utilization of nutrient for growth during the early neonatal period is sustained by a high rate of protein turnover in skeletal muscle during the fasting period and the accelerated utilization of amino acids for protein synthesis in response to feeding. Dr. Thivierge is currently at the Rowett Research Institute at the University of Aberdeen, Scotland.
Roberto Murgas Torrazza, M.D.
Postdoctoral Fellow in Pediatric Nutrition, USDA/ARS Children’s Nutrition Research Center, Baylor College of Medicine
M.D., Medicine and Surgery, Universidad de Cuenca, Ecuador,.2001
Internship, General Physician, Hospital Metropolitano, Universidad de Panama, 2003
Internship, General Physician, Hospital de Sona, Seguro Social, 2004
Pediatric Residency, Hospital de Especialidades Pediatricas, Universidad de Panama, 2007
Clinical Scientist Training Program (CSTP), Baylor College of Medicine, current
Dr. Torrazza is a pediatrician with a special interest in neonatal nutrition. His main career goal is to become both a clinical and research expert in the treatment of neonatal nutrition related problems. In the laboratory of Dr. Davis, his research project is to examine the potential for using leucine supplementation to improve the nutritional management of low birth weight infants. Using a neonatal piglet model, Dr. Torrazza is testing milk formulas with different levels of protein and comparing them with formulas supplemented with leucine to determine the effects of enteral leucine supplementation on muscle protein synthesis in neonates and the signalling mechanisms involved. Muscle protein synthesis, nutrient signalling proteins, and translation initiation factors are being examined.
Fiona A. Wilson, Ph.D.
B.S., Biomedical Science (Molecular Biology), University of Aberdeen, Scotland
Ph.D., Biomedical Science (Physiology), University of Aberdeen, Scotland
The overall objective of Dr. Wilson's research in the Davis laboratory was to understand the molecular mechanisms by which hormones and substrates regulate protein synthesis during early life. Her initial research in the Davis laboratory examined the role of insulin and amino acids in the regulation of muscle protein synthesis by growth hormone. Subsequent studies examined the insulin and amino acid signaling proteins that stimulate protein synthesis after eating. Lastly, she investigated whether prolonged parenteral infusion of leucine can stimulate protein synthesis, the role of other amino acids in this process, and the signaling mechanism involved. Dr. Wilson is now pursuing research on insulin signaling at the University of Dundee.
Diane Wray-Cahen, Ph.D.
Ph.D., Animal Science, Cornell University
Early studies by Dr. Wray-Cahen in the Davis laboratory focused on the development of a hyperinsulinemic-euglycemic-amino acid clamp technique to identify the role of insulin in the regulation of protein synthesis during early life, using the neonatal pig as the animal model. Her studies showed that the insulin sensitivity of protein metabolism in the whole body is enhanced in the neonate. Her studies further demonstrated that insulin stimulates protein synthesis in skeletal muscle of the neonate and this response declines with development. Dr. Wray-Cahen is currently a biologist with the U.S. Department of Health and Human Services, Food and Drug Administration.
Rhonda Vann, Ph.D.
B.S., Animal Science, Texas A&M University
M.S., Animal Science, Texas A&M University
Ph.D., Animal Physiology and Nutrition, Mississippi State University
Dr. Vann’s research in the Davis laboratory focused on identifying the mechanisms by which growth hormone increases the efficiency with which dietary amino acids are used for growth. Using stable isotopic tracers to measure rates of whole body protein turnover and amino acid oxidation, she demonstrated that growth hormone improves protein balance by minimizing the loss of protein during fasting and maximizing the protein gained during meal absorption. Dr. Vann is currently an associate research professor at Mississippi State University.