Faculty Research Summaries Cont.

Carlos Lifschitz, M.D.
The research being performed by Dr. Lifschitz is related to the bioavailability of different nutrients, and the effect that nutrients and growth factors have on the gut. Studies are being performed to determine the effect of growth hormone on gut adaptation in children with short bowel, the effect of the addition of fiber to the diet on mineral bioavailability, and the effect of nucleotides and glutamine on gut function.

Ronald L. McNeel, M.S.
Mr. McNeel's research interests involve studies of the influence of various fatty acids (e.g., conjugated linoleic acid) on adipocyte growth and differentiation in the human.  These studies focus on the in vitro use of isolated human stromal cells to evaluate factors regulating the differentiation process in the presence of fatty acids.  Transcript concentrations for transcription factors that regulate differentiation (C/EBP, PPAR, and ADD1) and transcript concentrations for key proteins that characterize the adipocyte (LPL, leptin, and aP2) are measured. These measurements help to characterize the mechanisms by which fatty acids influence adipocyte differentiation. A second research area involves studying the binding kinetics of fatty acids to the PPAR-RXR heterodimer. 

Harry J. Mersmann, Ph.D.
Adipocyte growth and differentiation are regulated by various hormones and growth factors. Beta-adrenergic receptors are among the major regulators of adipocyte metabolism. Dietary components may alter the pattern of adipocyte growth and differentiation. Dr. Mersmann's laboratory has studied the influence of the stage of development and of dietary factors on adipocyte beta-adrenergic receptors. Currently, the focus of his efforts is on adipocyte development. Porcine adipocyte precursor cells may be isolated from adipose tissue and when grown in culture in vitro under the proper conditions, differentiate to adipocytes. He has used this system to evaluate factors regulating the differentiation process and the influence of dietary components of differentiation. In addition to mRNA for the beta-adrenergic receptors, mRNA for various transcription factors that regulate differentiation (e.g., C/EBPa or PPAR) and mRNA for key proteins that characterize the adipocyte (e.g., lipoprotein lipase and aP2) are being measured. He is particularly interested in the role of individual fatty acids in the stimulation or inhibition of adipocyte differentiation.

Kathleen J. Motil, M.D., Ph.D.
Dr. Motil's studies focus on estimating dietary protein and amino acid needs of lactating women and adolescents and elucidating the mechanisms that underlie increased nutrient needs for milk production. Using stable isotope techniques, she has found that lean body mass of adult women is preserved during lactation because of the downregulation of rates of whole body protein turnover, synthesis and degradation, suggesting that nutrient conservation occurs because of the needs of milk production. In contrast, lean body mass of adolescents increases during lactation at the expense of a reduction in milk production. Dr. Motil's studies also focus on estimating the dietary protein and energy needs of girls with Rett syndrome and elucidating the mechanisms that underlie the universal finding of growth failure in this disorder. Using stable isotope techniques and whole-room calorimetry, she has found that involuntary motor movements associated with Rett syndrome do not increase rates of energy expenditure, and that poor growth results from reduced dietary energy intakes associated with oropharyngeal and gastroesophageal dysfunction.

Paul Nakata, Ph.D.
Calcium in plants is sequestered as a complex with other substances such as oxalates, phytates, fiber, fatty acids, proteins and other anions. Some of these substances (oxalates and phytates) are considered antinutrients, and render the calcium in plant foods unavailable for nutritional absorption by the human. The purpose of Dr. Nakata's research program is to elucidate the mechanism regulating calcium partitioning and sequestration in plants. The acquired information will be applied toward the rational design of strategies to enhance calcium abundance and bioavailability in plant food products.

Buford L. Nichols, M.D.
Mothers continue to feed cereals to infants despite pediatric advice against this practice due to the offspring's pancreatic and salivary immaturity. Because the intestinal enzymes, maltase and glucoamylase, digest starch, these enzymes may be the way in which cereal is digested by infants. An overlap exists between maltase activities of the maltaseglucoamylase with sucraseisomaltase enzymes, which has prevented direct testing of this theory. The DNA that codes the human maltaseglucoamylase protein has been cloned in Dr. Nichols' laboratory.  Dr. Nichols and his collaborators are using this DNA to make recombinant human proteins in COS1 cells in order to determine whether cereals are digested by maltase and glucoamylase in vitro. He is also working to knock out this gene in mice in order to demonstrate the enzyme's function on starch digestion in vivo. The message has been found to be decreased to 40% of normal in malnourished infants. His laboratory is now sequencing the maltaseglucoamylase gene in preparation for the study of possible genetic mutations in hypoMGAsic subjects.

Theresa A. Nicklas, Dr.P.H., M.P.H., L.N.
Dr. Nicklas' research interests and expertise are in the areas of nutritional epidemiology, cardiovascular health, child health, health promotion and disease prevention.  For 12 years, Dr. Nicklas was director of all the dietary studies for the Bogalusa Heart Study, an epidemiologic investigation of cardiovascular disease risk in children that has been ongoing for 26 years.  She also has been an investigator on several NIH grants designed to decrease chronic disease risk in children and adolescents through comprehensive health education. Dr. Nicklas is particularly interested in conducting both epidemiologic and intervention studies addressing childhood obesity. Similarly, she is interested in examining environmental factors that influence children's eating patterns and nutrient intakes.

Emiel W. Owens, Ed.D.
Dr. Owens' research projects focus on development of mathematical models to access dietary and behavior patterns among children. Modeling dietary habits in children will open the door to understanding and ultimately precluding the potential causes of fatal disease in their adult years. His other work involves the evaluation of school-based nutrition programs.

Peter J. Reeds, Ph.D.
Dr. Reeds' primary work concerns the nutritional and humoral regulation of growth. He places specific  emphasis on comparative nutrition and studies of growth regulation in both animal models and humans.  He has concentrated much of his recent efforts on the study of in vivo intermediary metabolism, especially in the gastrointestinal tract, and its impact on amino acid bioavailability and requirements. He makes extensive use of stable isotopic techniques, which he applies to studies of nonessential amino acid metabolism and its relationship to the energetics of growth.

Richard J. Schanler, M.D.
Dr. Schanler's research focuses on clinical aspects of feeding premature infants.  He has conducted studies on the fortification of human milk, feeding methods in the nursery, and the use of trophic feedings. Currently, he is measuring the body composition changes in a large population of premature infants during their first years after hospital discharge. He measures body composition using dual energy x-ray absorptiometry and total body potassium, as well as standard anthropometric techniques. Dr. Schanler estimates mineral and fat balance by classical techniques and, in some cases, by stable isotope methods.

Robert J. Shulman, M.D.
Dr. Shulman is investigating the factors regulating the development of gastrointestinal function in the premature infant. He is particularly interested in carbohydrate digestion and absorption and the interaction of carbohydrates with other nutrients, both as facilitators and potential inhibitors of digestion and absorption of other nutrients. He also is studying the factors that contribute to feeding intolerance and is seeking ways to ameliorate premature infants' difficulty with enteral feedings.

Roman J. Shypailo, B.S.
The unprecedented growth of technology during the past decade has created challenges for researchers. Powerful computers and data acquisition equipment enable rapid accumulation of information that requires processing. The CNRC Body Composition Laboratory houses sophisticated instruments designed to measure the elemental composition of the human body using nuclear-based techniques. Each instrument is in a dynamic state of evolution. New measurement systems are being developed, including a multiparameter whole-body counter capable of isolating and measuring a signal coming from a specific site in the body, and a portable  ⁴⁰  K counter for use in a hospital setting.  Coordinating these efforts and incorporating new technology are the primary focus of Mr. Shypailo's work.

Janice E. Stuff, Ph.D.
Dr. Stuff's broad area of interest is that of nutritional epidemiology and the role of nutrition in chronic diseases and public health problems. A focus area is research on methodologies to assess dietary intakes in populations. Currently, Dr. Stuff collaborates with the USDA/ARS Delta Nutrition Intervention Research Initiative. The initial purpose of this initiative is to measure the nutrition and health status of individuals and communities in the Lower Mississippi Delta region.  Specifically, Dr. Stuff has helped in efforts to develop and validate dietary methodology in the Lower Delta, which now will be applied to assess dietary intakes in cross-sectional and longitudinal designs. Other interests include the impact of food insecurity on the health, nutritional requirements and health status of children; nutritional interventions for children in high-risk, low-income areas; and the application of research findings on mineral and caloric requirements of children to interpreting nationwide nutrition surveys and databases.

Agneta L. Sunehag, M.D., Ph.D.
Dr. Sunehag's primary research interest is glucose metabolism, particularly gluconeogenesis, in premature infants. Her current research project is focusing on substrate and hormone regulation of gluconeogenesis from various precursors provided these infants via total parenteral nutrition (TPN) solutions. The ultimate goal of these studies is to define a composition of TPN solutions that will maintain normoglycemia and provide sufficient calorie intake for growth. She is also interested in glucose metabolism in children and adolescents in relation to dietary macronutrient intake and obesity.

William W. Wong, Ph.D.
Dr. Wong is conducting research focused on the efficacy of school-based implementation of the U.S. Department of Health and Human Services' "Healthy People 2000" physical activity guidelines to prevent excessive weight gain in U.S. children.  A second research project focuses on the efficacy of soy protein and its phytoestrogens in reducing the risks of cardiovascular heart disease and osteoporosis in postmenopausal women.