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
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.,
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
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
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
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
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