2001 Faculty Research Interests

Steven Abrams, M.D.
Dr. Abrams' research projects are designed to use stable isotopes to evaluate mineral metabolism in infants and children. True dietary calcium absorption and bone formation and turnover are determined using orally and intravenously administered stable isotopes of calcium. Studies in children with mineral deficiencies are designed to determine the etiology of the mineral deficiency and the possible response to therapy. Studies are under way to evaluate the absorption of calcium and iron from milk, formula and dietary supplements in children age 4-12 months. Studies are being conducted to determine the iron needs of children with rheumatoid arthritis.

Cheryl B. Anderson, Ph.D.
Dr. Anderson’s research is aimed at the promotion of regular physical activity by understanding its determinants, including self-identity as a motivational factor in health behavior, and the development of psychometrically valid and reliable measurement instruments of attitudes and behaviors. Her work focuses on the description and measurement of athletic identity and its relation to physical activity in adolescents, children, and parents, as well as the factors that contribute to identity formation, stability, and change.

Janice C. Baranowski, M.P.H.
Tom Baranowski, Ph.D.
Eating larger amounts of fruit, 100% juice and vegetables has been shown to provide protection from several chronic diseases, and may enhance weight control. Eating practices are learned in childhood. The focus of the research conducted by Janice and Tom Baranowski is on theory-based programs aimed at determining how to help children eat more fruit, 100% juice and vegetables. Their many community-based, nutrition education research projects have included “GIMME 5,” a school-based class curriculum intervention; “5 A Day Boy Scout Achievement Badge;” “Squire’s Quest!,” a school-based, interactive, multimedia, nutrition education game; and “Bringing It Home,” a school-based program designed toward influencing the parents of 4th-grade children. All the individuals targeted by these programs showed some change in dietary behavior. The researchers also demonstrated that an interactive, multimedia program for dietary assessment among 4th-grade children worked almost as well as a dietitian-conducted, 24-hour dietary recall. Janice and Tom Baranowski currently are actively involved in the Houston-area “Fun, Food and Fitness Program,” which is part of the national Girls’ Health Enrichment Multi-site Study, aimed at the prevention of obesity in 8-year-old African-American girls.

Dennis M. Bier, M.D.
Dr. Bier's primary research interest is the regulation of interorgan transport of metabolic fuels; specifically, substrate and hormonal regulation of glucose, lipid, and protein/amino acid fuels. This work has taken two principal directions. The first entails the regulation of endogenous fuel availability for metabolic functions when a subject is ill and incapable of ingesting sufficient food. The second involves the assessment of the metabolic fates of ingested, exogenous fuels under various classical nutritional circumstances. In each instance, he has developed and employed a wide variety of stable isotope tracer kinetic methods to quantify substrate flux, metabolism, precursor-product relationships, and irreversible oxidation to excreted end products. The physiological information obtained also has been used to further assess aberrations in interorgan fuel transport consequent to a variety of pathological conditions.

Douglas G. Burrin, Ph.D.
Dr. Burrin’s major research objective is to elucidate the cellular and hormonal signals that mediate the stimulatory effects of enteral nutrition on the growth and function of the neonatal intestine. Recent studies have established the quantity and quality of enteral nutrients necessary for maintaining normal intestinal growth and function. He has found that the neonatal intestine utilizes a substantial proportion of the dietary nutrients to maintain normal growth. He also has found that the secretion of the gut-derived peptide, glucagon-like peptide 2 (GLP-2), is closely correlated with enteral nutrient intake, and that infusion of GLP-2 produces intestinal trophic effects when given to neonatal pigs. In contrast, treatment with dexamethasone has a potent catabolic effect on the neonatal intestine. Future studies will investigate the physiological significance of GLP-2, and how it affects intestinal protein and amino acid metabolism in neonatal pigs. He will examine whether the catabolic effects of dexamethasone compromise intestinal absorptive function, and how the provision of either minimal enteral nutrition or GLP-2 ameliorates the actions of dexamethasone. To understand how these nutritional and hormonal factors modulate intestinal growth, he will quantify the rates of cellular protein turnover, proliferation and programmed cell death. How these factors affect the expression and activity of key intermediates in these cellular pathways will be identified.

Nancy F. Butte, Ph.D.
The energy requirements of reproductive women and their infants are the focus of Dr. Butte's research. Her major interests are the functional consequences of variations in energy balance on pregnancy outcome, lactation performance, and infant growth and development. To further these evaluations, methodologies have been developed to measure energy expenditure and body composition in the populations of interest, including room respiration calorimeters and the doubly labeled water method for the measurement of free-living energy expenditure. Factors that predispose women to postpartum weight retention and later development of obesity are under investigation. Also, genetic and environmental factors that predispose infants and children to the development of obesity are being explored.

David M. Cohen, Ph.D.
Dr. Cohen’s research concerns the regulated coordination of metabolic fluxes that is fundamental to health and sustained by adequate nutrition. Study of the quantitative relationships among metabolic flux rates depends on accurate measurement of those rates, preferably in vivo. To this end, he has investigated mathematical aspects of modeling rates of metabolic pathways, subsequent to the administration of isotope-labeled precursors. An important focus of Dr. Cohen’s work is the measurement of cerebral metabolism in vivo, using nuclear magnetic resonance spectroscopy. Currently, he is developing a new method for estimation of the rate of cerebral glucose metabolism, with a substantial improvement in time resolution. In the long term, he hopes to learn more about the role of diet in support of brain metabolism and function.

Orla M. Conneely, Ph.D.
The objective of Dr. Conneely’s research is to establish the role of nuclear receptors in vertebrate development. Nuclear receptors comprise a large family of structurally related transcription factors regulating the expression of genes that control a variety of developmental and physiological responses to diverse stimuli.

Austin J. Cooney, Ph.D.
Dr. Cooney’s research goal is to understand the mechanism of action of the transcription factor GCNF in regulating embryonic gene expression, and the influence of the maternal diet on its activity. To achieve this objective, his research focuses on identifying GCNF- responsive target genes expressed during embryogenesis and studying the GCNF mode of regulation of these genes. To date, he has been able to identify Oct4 as a GCNF- responsive gene that is silenced in somatic cells after gastrulation by GCNF. Using a yeast two-hybrid screen, he has identified DNA methyl transferases as interacting partners of GCNF. Methylation of DNA around genes has been implicated in the silencing of genes, so this would be the first example of regulated and targeted DNA methylation by specific recruitment of a DNA methyltransferase. His laboratory is using knockout mouse models and the multipotent embryonic carcinoma cell P19 to study GCNF’s regulation of Oct4 expression via DNA methylation

Karen Weber Cullen, Dr. P.H.
Dr. Cullen’s research focuses on the prevention of diet-related, chronic diseases through the development, implementation, and evaluation of nutrition behavior-change programs for children and adolescents. Of particular interest are programs aimed at increasing children’s fruit and vegetable consumption, using unique delivery channels. Current projects include implementing and evaluating an environmental behavior-change program involving middle-school cafeteria a la carte/snack bars; developing and implementing a school-based program aimed at the prevention of type 2 diabetes among youth; and conducting a feasibility study of an Internet-based, dietary behavior-change program aimed at families.

Teresa Davis, Ph.D.
Dr. Davis' research goal is to identify the mechanisms by which hormones and nutrients interact to regulate the high rate of skeletal muscle protein deposition in the neonate. To achieve this objective, her research focuses on four main areas: the role of insulin and amino acids in the regulation of protein synthesis in the neonate; the role of insulin and amino acids in the regulation of the insulin signaling pathway which leads to translation initiation; the role of hormones, cytokines, and nutrients in the regulation of muscle protein synthesis during sepsis; and the role of insulin and nutrient intake in the anabolic response to growth hormone.

Debby Demory-Luce, Ph.D.
Two focal points of interest of Dr. Debby Demory-Luce are the eating habits of preschool children, and pediatric nutrition education for primary care providers. A current research area involves the examination of how preschool children’s eating habits are affected by environmental factors and their parents’ personal characteristics, such as weight and health-related beliefs.

Kenneth J. Ellis, Ph.D.
The goal of Dr. Ellis' research is to establish reference standards for body elemental composition in infancy, childhood and adolescence. This research focuses on the development and application of nuclear?based techniques for in vivo studies of human body composition. This approach provides knowledge of changes in growth and body composition that reflect the body's cumulative response to basic physiologic and metabolic processes. Detection of these changes often requires unique instrumentation like the CNRC's whole body counters, which monitor 40K, a naturally occurring isotope in the human. Dr. Ellis has developed in vivo neutron activation techniques for clinical research and postmortem examinations, and he has extended the use of dual-energy X-ray absorptiometry to the examination of infants and children.

Marta Fiorotto, Ph.D.
The effects of chronic alterations in nutrient intake on the growth and development of skeletal muscle are the focus of Dr. Fiorotto's research. Currently, she is attempting to show that the nature of skeletal muscle response is dependent on the developmental stage at which the organism is subjected to a nutritional insult. She is also attempting to identify the underlying factors responsible for the age?related change in the sensitivity of skeletal muscle to nutritional perturbations. Dr. Fiorotto also will evaluate the consequences of changes in sensitivity on the numerous functional roles of skeletal muscle in the body.

Jennifer Orlet Fisher, Ph.D.
Dr. Fisher’s goal is to understand behavioral and environmental factors that modify food intake regulation and growth patterns during early childhood. To this end, her research focuses on children’s early eating experiences and learning about eating within the family. In particular, Dr. Fisher’s work evaluates children’s eating patterns as a function of parents’ choices regarding the types of foods that constitute the family diet, parents’ models of eating behavior, and parents’ child-feeding practices. Her current projects investigate the extent to which eating in the absence of hunger constitutes a behavioral phenotype of overweight Hispanic children, the extent to which it is related to characteristics of the family eating environment, and the extent to which this type of eating behavior reflects a shared eating style among family members.

Ian J. Griffin, M. B., Ch. B.
Dr. Griffin’s work is to understand the mechanisms by which humans regulate zinc metabolism, particularly the metabolic adaptations to low zinc intakes, and the importance of marginal zinc status in human disease (e.g., Crohn’s disease.) His research uses stable (i.e., nonradioactive) isotopes and mathematical modeling techniques to describe zinc metabolism in health and disease.

Michael A. Grusak, Ph.D.
Dr. Grusak’s laboratory is involved in both plant physiology and human nutrition research. His plant physiology research is focused on the mechanisms and regulation of nutrient transport in plants. His long-term goals are to characterize the dynamics of nutrient flow within plants in order to determine the biophysical/molecular signals that regulate source-to-sink nutrient partitioning, and ultimately to use this information to enhance the nutritional quality of plant foods for human consumption. With regard to his human nutrition research, his laboratory group has developed hydroponic growth facilities and various protocols to intrinsically label plant foods with stable isotopes of important nutrients; these are then used to assess nutrient bioavailability and metabolism in humans.