2005 Annual Report 1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? This research unit focuses on the nutritional regulation of cell and organ growth, differentiation, and development and is composed of five individual research projects:. 1)Intestinal amino acid requirements in neonates;. 2)Nutritional regulation of tissue anabolism in neonates;. 3)Nutrient regulation of blood and blood vessel formation;. 4)Consequences of perinatal undernutrition for satellite cell function and skeletal muscle growth; and. 5)Nutritional influences on gastrointestinal function in health and disease. This research unit falls within Components 1 (Nutrient Requirements) and 7 (Bioavailability of Nutrients and Food Components) of National Program 107 – Human Nutrition. Additionally, this research adheres to ARS Strategic Plan Goal 4 Improve the Nation's Nutrition and Health, specifically Objective 4.1: Promote Healthier Individual Food Choices and Lifestyles and Prevent Obesity; Improve Human Health by Better Understanding the Nutrient Requirements of Individuals and the Nutritional Value of Foods; Determine Food Consumption Patterns of Americans. Project 1: Intestinal amino acid requirements in neonates Optimum nutrition from fetal life through to puberty is critical for sustaining the appropriate growth and functional development of the organism. "Optimum" requires that we know how an organism uses specific nutrients at different stages of development. This research project addresses the underlying metabolic and physiological processes that determine the amino acid requirements in infants. Specifically, it examines the metabolic fate and quantitative significance of the amino acids methionine and cysteine used by the gastrointestinal tract in neonates fed enterally and parenterally. This is important because the high metabolic activity of the intestine consumes a significant proportion of the dietary amino acid intake and, thereby, can limit their availability for somatic growth. Thus, the metabolic fate and functional requirements of indispensable amino acids within the intestines is critical to understanding the metabolic basis of infant amino acid requirements. The project has four objectives: (1) Quantify the intestinal metabolic fate of methionine derived from the diet and systemic circulation in enterally fed neonatal animal models; (2) quantify the intestinal metabolic fate of cysteine derived from the diet and systemic circulation in enterally fed neonatal piglets; (3) quantify the intestinal metabolic fate of parenterally administered methionine and cysteine in TPN-fed neonatal piglets; and (4) establish the cellular localization and metabolic significance of sulfur amino acid (SAA) metabolism in the maintenance of intestinal epithelial cell redox status and cell survival. Project 2: Nutritional regulation of tissue anabolism in neonates Researchers will examine how protein synthesis in neonates is regulated by branched chain amino acids and the intracellular mechanisms that regulate the response. Moreover, because amino acids are usually consumed as part of a meal, the response to glucose and insulin will also be examined to determine how these may modulate the response to amino acids. The studies will quantify the changes in translation initiation and protein synthesis that occur in vivo in response to variations in circulating levels of leucine, other amino acids, glucose, and insulin. How stage of development and feeding status influence these processes will be examined subsequently. This work will provide valuable information to improve strategies for the nutritional management of low birth weight infants. Project 3: Consequences of perinatal undernutrition for satellite cell function and muscle growth Our research will examine how the intrauterine nutritional environment of the fetus and nutrition in early postnatal life influence skeletal muscle development. Specifically, it aims to identify how the development of skeletal muscles is compromised in a rat model when perinatal nutrition is suboptimal. This is important because there are data that indicate that inadequate muscle growth in early life can never be entirely reversed. This may have significant implications for the precocious development of a number of detrimental, chronic conditions in adulthood, such as glucose intolerance, sarcopenia, obesity, and osteoporosis. The objectives of the project are: (1) to determine the effects of undernutrition either during fetal development or postnatally on satellite cell replicative capacity; (2) to clarify the roles of insulin-like growth factor-I (IGF-I) and hepatocyte growth factor (HGF) in the nutritional regulation of satellite cell replication; (3) to identify the mechanism that relates ribosomal formation to satellite cell replication; (4) to delineate the significance of glucocorticoids in mediating the effects of intrauterine malnutrition on skeletal muscle growth in the fetus. Achieving these objectives will enable us to develop preventive and therapeutic strategies for those individuals who, because they were inappropriately nourished during the perinatal period, are at greater risk for the development of chronic adult diseases, such as glucose intolerance, sarcopenia, obesity, and osteoporosis. These disorders constitute the most common chronic medical problems in our adult population today, and their treatment is a substantial economic burden on society. Project 4: Nutrient regulation of blood and blood vessel formation Most embryos that die prior to birth do so for one of three reasons:. 1)failure to implant or establish fetal-maternal connection;. 2)inability to produce blood cells to sustain embryonic life; or. 3)inadequate circulatory system. Our current knowledge of the molecular regulation of these processes and our understanding of how specific nutrients regulate these processes is very limited. Gaining such insights will greatly aid in understanding how maternal diet influences pregnancy outcome, and how it could be altered to prevent embryonic death. In our studies, we will examine the molecular events that lead to the formation of blood vessels and, more specifically, how nutrients such as retinoic acid regulate this process. Blood vessel formation will be studied in the mouse embryo model in mice that are genetically deficient in retinoic acid; thus, the impact of retinoic acid deficiency on vascular development can be studied directly. Understanding how blood vessels form and how retinoic acid controls this process will provide important insights that can be applied to controlling the aberrant vessel formation that underlies much prevalent pathology including tumorigenesis, diabetes, and arteriosclerosis. This project will contribute to the national program mission to understand how nutrients regulate cell and organ growth during development by revealing how retinoids regulate the formation of blood and blood vessels in the embryo. The long-term goal of these studies is to understand, on a cellular and molecular level, the events leading to vascular development and hematopoiesis. We further aim to determine how nutrients, such as Vitamin A, contribute to the regulation of these processes. Project 5: Nutritional influences on gastrointestinal function in health and disease Recurrent abdominal pain (RAP) in children and irritable bowel syndrome (IBS) in adults are debilitating conditions present in a significant number of individuals. These conditions often lead to significant disability (e.g., school absence) with adverse economic impact (expensive medical evaluations, loss of job productivity because of parent time away from work). From 30 to 66% of children with RAP will go on to develop the irritable bowel syndrome (IBS) in adulthood. IBS is more prevalent than heart disease and hypertension combined, and its economic impact has been calculated to be almost $8 billion per year. Our research will develop nutritional strategies to minimize the occurrence of RAP in children, with specific emphasis on the effects of probiotics, fiber (Objective. 1)and sugars (Objective 2). The resulting measurements will identify the mechanisms whereby these dietary components impact those gastrointestinal functions that are responsible for the symptoms of RAP (Objective 3). The development of effective treatments in childhood RAP is important because it is likely to reduce the chances of developing IBS in adulthood. 2.List the milestones (indicators of progress) from your Project Plan. Project 1: Intestinal amino acid requirements in neonates Year 1 (FY2005): Completion of animal infusion studies and preliminary plasma analysis of isotopic tracers, and quantifying the intestinal metabolic fate of methionine derived from the diet and systemic circulation in enterally fed neonatal piglets. Year 2 (FY2006): Completion of animal infusion studies and preliminary plasma analysis of isotopic tracers described, and quantifying the intestinal metabolic fate of cysteine derived from the diet and systemic circulation in enterally fed neonatal piglets. Development of cell culture studies to assess the localization and extent of intestinal methionine metabolism. Year 3 (FY2007): Completion of animal infusion studies and preliminary plasma analysis of isotopic tracers described, and quantifying the intestinal metabolic fate of parenterally administered methionine and cysteine in parenterally fed neonatal piglets Continued development of cell culture studies to assess the localization and extent of intestinal methionine metabolism. Year 4 (FY2008): Perform cell culture studies and biochemical assessments of epithelial methionine metabolism to establish the cellular localization and metabolic significance of sulfur amino acid (SAA) metabolism in the maintenance of intestinal epithelial cell redox status and cell survival. Year 5 (FY2009): Complete cell culture studies and biochemical assessments of epithelial methionine metabolism to establish the cellular localization and metabolic significance of sulfur amino acid (SAA) metabolism in the maintenance of intestinal epithelial cell redox status and cell survival. Project 2: Nutritional regulation of tissue anabolism in neonates Year 1 (FY2005): Determine the effect of leucine on protein synthesis and translation initiation factors activation; determine the effect of individual amino acids on tissue protein synthesis, time course of action, and effect of other amino acids and insulin; and determine the effect of glucose on protein synthesis. Year 2 (FY2006): Determine the effect of other amino acids on protein synthesis and translation initiation; determine the effect of signaling inhibitors on glucose-stimulated protein synthesis; determine the effect of development on abundance and feeding-induced activation and protein-protein interaction of PTEN, PDK1, PKB, TSC1-2, Rheb, and mTOR. Year 3 (FY2007): Determine the effect of glucose on the intracellular signaling pathways leading to protein synthesis and determine the effect of development on abundance and feeding-induced activation and protein-protein interaction of PTEN, PDK1, PKB, TSC1-2, Rheb, and mTOR. Year 4 (FY2008): Identify the effect of development on nutrient and insulin signaling proteins that regulate protein synthesis and determine rapamycin's effect on protein synthesis and translation initiation. Year 5 (FY2009): Determine the role of insulin and amino acids in the developmental change in the feeding-induced activation of insulin and nutrient signaling proteins leading to protein synthesis. Project 3: Consequences of perinatal undernutrition for satellite cell function and muscle growth Year 1 (FY2005): Establish technique for isolating satellite cells from muscles, and culture procedures to measure in vitro proliferation rates. Compare the consequences of intrauterine versus postnatal undernutrition on the growth in skeletal muscle mass, satellite cell number, and replicative capacity upon nutritional rehabilitation. Quantify myonuclear accretion and satellite cell number in skeletal muscles from undernutrition study using immunohistochemical (IHC) procedures; quantify skeletal muscle growth responses as measured by total protein, RNA, and DNA. Year 2 (FY2006): Complete muscle measurements. Assess plasma and muscle IGF-I, HGF, and myostatin levels, as well as the abundance and degree of activation of the respective muscle receptors in response to the nutritional treatments. Develop, produce, and test in vitro myogenic cDNA expression plasmids for HGF and IGF-I. Verify efficacy of in vivo gene transfer and expression of peptides from HGF and IGF expression plasmids. Compare growth of skeletal muscle mass in pups subjected to postnatal malnutrition followed by post-weaning nutritional rehabilitation with or without augmented expression of local IGF-I and/or HGF induced by in vivo gene transfer. Year 3 (FY 2007): Complete analysis of muscle growth responses and analysis of intracellular signaling responses associated with the enhanced IGF and/or HGF production. Perform animal protocols as described for Objective 1, but in which rates of muscle protein synthesis will be assessed in vivo in the undernourished state and with nutritional rehabilitation. The concurrent response in the abundance and activity of signaling intermediates that regulate rRNA transcription will be determined. Year 4 (FY 2008): Complete analytical measurements. Evaluate data. Perform animal component of protocol as previously described for Objective 1, but include two additional treatments to distinguish the roles of glucocorticoids and protein deficiency on the impairment of intrauterine muscle growth. Perform IHC of muscles to assess satellite cell responses to alterations in fetal exposure to glucocorticoids. Year 5 (FY 2009): Complete analysis and assessment of skeletal muscle mass from fetus exposed to variable levels of glucocorticoids. Evaluate data from Objective 4. Project 4: Nutrient regulation of blood and blood vessel formation Year 1 (FY2005): Measure levels of cellular apoptosis and proliferation in Raldh2-/- and WT embryos and yolk sacs. Assess the level of visceral endoderm differentiation and measure its expression of soluble effectors in WT and Raldh2-/- yolk sac tissues. Year 2 (FY2006): Determine the extent to which yolk sac progenitors from Raldh2-/- mutants and WT embryos form hematopoietic colonies in vitro. Measure the levels of differentiated blood cells formed in Raldh2-/- and WT embryos/yolk sacs in vivo and in colony-forming assays in vitro. Year 3 (FY2007): Complete gene and protein expression analyses. Attempt to rescue the vascular defects in Raldh2-/- mutants with soluble effectors down-regulated in response to retinoic acid deficiency. Measure the restoration of morphological defects, cellular proliferation, and gene expression in rescued mutants. Year 4 (FY2008): Determine the hierarchy of signaling molecules involved in endodermal induction of vascular development in the mesoderm. Measure levels of transcription factors and signaling molecules, which induce or are associated with embryonic hematopoiesis in Raldh2-/- and WT embryos. Determine whether retinoid-regulated factors induce hematopoietic cell fates in WT mesodermal progenitors that we have recently isolated and characterized. Year 5 (FY2009): Complete data collection, analyses, and manuscript preparation for all objectives. Project 5: Nutritional influences on gastrointestinal function in health and disease Year 1 (2005): This is a random double-blind protocol that entails the recruitment of 180 human subjects (45 subjects in 2005) with the necessary characteristics to qualify for the study. The efficacy of treatment for 4 weeks with a probiotic, fiber, or a placebo on symptoms of RAP will be assessed (Objective 1). Tests will be performed that will measure GI transit time, carbohydrate malabsorption, GI integrity, and GI inflammation. Subjects who do not respond positively to treatments in Objective 1 will be tested in Objective 2 in which the effect of a sugar elimination diet on symptoms will be assessed. Year 2 (2006): This is a random double-blind protocol that entails the recruitment of 180 human subjects (45 subjects in 2006) with the necessary characteristics to qualify for the study. The efficacy of treatment for 4 weeks with a probiotic, fiber, or a placebo on symptoms of RAP will be assessed (Objective 1). Tests will be performed that will measure GI transit time, carbohydrate malabsorption, GI integrity, and GI inflammation. Subjects who do not respond positively to treatments in Objective 1 will be tested in Objective 2 in which the effect of a sugar elimination diet on symptoms will be assessed. Year 3 (2007): This is a random double-blind protocol that entails the recruitment of 180 human subjects (45 subjects in 2007) with the necessary characteristics to qualify for the study. The efficacy of treatment for 4 weeks with a probiotic, fiber, or a placebo on symptoms of RAP will be assessed (Objective 1). Tests will be performed that will measure GI transit time, carbohydrate malabsorption, GI integrity, and GI inflammation. Subjects who do not respond positively to treatments in Objective 1 will be tested in Objective 2 in which the effect of a sugar elimination diet on symptoms will be assessed. Year 4 (2008): Recruitment of a total of 180 human subjects with the necessary characteristics to qualify for the study will be complete. The efficacy of treatment for 4 weeks with a probiotic, fiber, or a placebo on symptoms of RAP will be assessed (Objective 1). Tests will be performed that will measure GI transit time, carbohydrate malabsorption, GI integrity, and GI inflammation. The subjects' pain episodes and stooling patterns will also be tracked. Subjects who do not respond positively to treatments in Objective 1 will be tested in Objective 2 in which the effect of a sugar elimination diet on symptoms will be assessed. Year 5 (FY2009): The effects of the various treatments on the perceived indices of pain will be related to the corollary measures of gastrointestinal function, to determine the mechanism responsible for the observed responses (Objective 3). The results will be disseminated through publications and presentation to healthcare workers who deal with this population of children. 4a.What was the single most significant accomplishment this past year? Project 4: Nutrient regulation of blood and blood vessel formation NORMAL VESSEL FORMATION AND CELL GROWTH Knowledge of the molecular regulation of why embryos die prior to birth and our understanding of how specific nutrients regulate these processes is very limited. Researchers at the Children's Nutrition Research Center in Houston, TX, have determined the effects of embryonic retinopic retinoic acid deficiency on cellular apoptosis and proliferation using Raldh2-/- and WT mouse embryos and yolk sacs. CNRC researchers discovered that in the absence of retinoic acid (a biologically active form of Vitamin A), there is excessive endothelial cell growth, which leads to abnormalities in blood vessel formation and function. Thus, we determined that Vitamin A, in its retinoic acid form, is required for normal blood vessel formation and may aid in controlling neovascularization, the abnormal new blood vessel formation associated with prevalent adult vascular pathologies that accompany health concerns including diabetes, atherosclerosis, and the formation of cancerous tumors. 4b.List other significant accomplishments, if any. Project 1: Intestinal amino acid requirements in neonates IMPORTANCE OF GUT METHIONINE METABOLISM Methionine is a dietary indispensable amino acid and serves as a precursor for body protein synthesis, but also for homocysteine and cysteine, two key amino acids that affect the antioxidant status in the body. Scientists at the Children's Nutrition Research Center in Houston, TX, have completed a study designed to quantify the extent of dietary methionine metabolism by the gut using an animal model as a model for the human infant. Scientists traced the metabolism in the gut and whole body using highly sensitive methionine isotopes as a marker and discovered that 20% of the dietary methionine is metabolized or used by the gut for normal growth, development, and function. More importantly, researchers showed for the first time that the gut is an important tissue that converts methionine to homocysteine and cysteine. These findings have implications for determining the metabolic availability of dietary methionine in infant formulas. Project 2: Nutritional regulation of tissue anabolism in neonates INCREASED LEUCINE CONTENT PROMOTES PROTEIN SYNTHESIS IN MUSCLE Feeding increases the synthesis of protein in young animals but the precise mechanism by which this occurs is not known. Scientists at the Children's Nutrition Research Center (CNRC) in Houston, TX, infused different doses of leucine within the physiological range into fasted neonatal animal models, while other substrates and hormones remained at the fasting level. Results showed that an increase in the amino acid leucine after a meal stimulates the synthesis of protein in the muscle in these young models. CNRC Researchers also identified the intracellular signaling proteins that regulate the effect of leucine. We successfully demonstrated that the response is independent of insulin and is specific for muscle tissue. This work provides valuable information to improve strategies for the nutritional management of low birth weight infants. HIGH PROTEIN DIETS DO NOT ENHANCE PROTEIN DEPOSITION Although feeding increases protein synthesis, it is not known whether the feeding of a high dietary protein diet will further stimulate protein synthesis. Animal models were fed artificial milk diets that contained marginal, adequate, or high levels of protein. Scientists at the Children's Nutrition Research Center in Houston, TX, showed that feeding stimulates protein synthesis in skeletal muscle and the liver by modulating translation initiation factors that regulate mRNA binding to the ribosomal complex. However, provision of a high protein diet that exceeds the protein requirement does not appear to further enhance protein synthesis or translation initiation factor activation. These results suggest that feeding a high protein diet above the protein requirement will not enhance protein deposition in the young animal. Project 3: Consequences of perinatal undernutrition for satellite cell function and muscle growth STIMULATING PROTEIN TRANSLATION AND NUCLEAR PROLIFERATION Additional knowledge is needed regarding the promotion of muscle growth, especially in the area of the anabolic pathways responsible for the stimulation of newborn muscle growth by local insulin-like growth factor-I (IGF-I). Researchers at the Children's Nutrition Research Center in Houston, TX, established that local IGF-I primarily upregulates a signaling pathway that has the potential of initiating protein translation and nuclear proliferation. The latter also requires concurrent activation of the MAPKinase signaling pathway. However, a key intermediary in the MAPKinase pathway, is down-regulated when the muscle is exposed to high levels of IGF-I, and nuclear proliferation is no longer stimulated. This has a significant impact for the development of IGF-I-based interventions that are currently being considered for promoting muscle growth in agriculture, and for treatment of individuals with muscle diseases. Project 5: Nutritional influences on gastrointestinal function in health and disease RESEARCHERS DISCOVER MORE PALTABLE CAPSULES TO CONDUCT RESEARCH Recurrent abdominal pain (RAP) in children and irritable bowel syndrome (IBS) in adults are debilitating conditions present in a significant number of individuals, and a method to reduce these occurrences of conditions is needed. To alleviate these conditions, research involving a fiber product administered to the subjects had been planned; however, it was determined that because of the number of capsules required, a more optimal product is needed to reduce the amount of capsules ingested. Researchers at the Children's Nutrition Research Center in Houston, TX, have devised a method that will allow administration of a similar fiber product that will be more palatable and will require less intake. Development of this new method will ensure completion of this research objective and will be conducive to the subjects and their ability to meet the research protocol. 4c.List any significant activities that support special target populations. None. 5.Describe the major accomplishments over the life of the project, including their predicted or actual impact. Project 1: Intestinal amino acid requirements in neonates Researchers at the Children's Nutrition Research Center in Houston, TX, have completed a study designed to quantify the extent of dietary methionine metabolism by the gut using an animal model as a model for the human infant. Scientists traced the metabolism in the gut and whole body using highly sensitive 13C- and 2H-labeled methionine isotopes as a marker and discovered that 20% of the dietary methionine is metabolized or used by the gut for normal growth and function. More importantly, researchers showed for the first time that the gut is an important tissue that converts methionine to homocysteine and cysteine. These findings have implications for determining the metabolic availability of dietary methionine in infant formulas. The consumers of the scientific information from the lab's scientific publications and presentations include pediatricians, neonatologists, gastroenterologists, pediatric gastroenterologists, dieticians, and academic nutritionist with an interest in dietary nutrient requirements and methionine metabolism. The findings address the need to understand the biological basis for dietary amino acid requirements in infants. Dietary Recommended Intakes for amino acids in infants are based on factorial estimates and represent at best indirect measures of nutrient requirements. Project 2: Nutritional regulation of tissue anabolism in neonates CNRC Researchers have demonstrated that the increase in the amino acid leucine that occurs after a meal acts as a nutrient signal to rapidly stimulate protein synthesis in muscle of very young animals. This work will provide important new information on the potential for using leucine supplementation to optimize the nutritional management of low birth weight infants. Project 3: Consequences of perinatal undernutrition for satellite cell function and muscle growth The studies performed aimed to delineate the anabolic pathways responsible for the stimulation of neonatal muscle growth by local IGF-I in vivo. We established that local IGF-I primarily upregulates the PI3 kinase/Akt signaling pathway which has the potential of stimulating both protein translation and nuclear proliferation. However, the latter response also requires concurrent activation of the MAPKinase signaling pathway. However, ERK1/2 (a key intermediary in the MAPKinase pathway) is down-regulated when the muscle is exposed chronically to high levels of IGF-I, and nuclear proliferation is no longer stimulated. This has a significant impact for the development of IGF-I-based interventions that are currently being considered for promoting muscle growth in agriculture, and for treatment of individuals with muscle diseases. Project 4: Nutrient regulation of blood and blood vessel formation Scientists at the Children's Nutrition Research Center in Houston, TX, have gained knowledge of the molecular role(s) of specific nutrients during blood and blood vessel development that will provide insights into the impact of maternal diet on the developing embryo. We are also in the process of discovering novel, retinoic acid-regulated genes that modulate blood and vascular development, and will determine whether these genes will be useful for the treatment of vascular and hematopoietic defects in adults. We anticipate pregnant women and physicians who care for them will benefit from this work. Other scientists will also gain a better understanding of the molecular regulation of blood and blood vessel development, and the impact of specific nutrients on these processes. Project 5: Nutritional influences on gastrointestinal function in health and disease Because of the concern that the initial fiber product that we had planned to use might be difficult for the subjects to take because of the number of capsules required, researchers at the Children's Nutrition Research Center in Houston, TX, have devised a method that will allow us to administer a similar fiber product that will be more palatable and will require less intake. This research unit falls within Components 1 (Nutrient Requirements) and 7 (Bioavailability of Nutrients and Food Components) of National Program 107 – Human Nutrition. Additionally, this research adheres to ARS Strategic Plan Goal 4 Improve the Nation's Nutrition and Health, specifically Objective 4.1: Promote Healthier Individual Food Choices and Lifestyles and Prevent Obesity; Improve Human Health by Better Understanding the Nutrient Requirements of Individuals and the Nutritional Value of Foods; Determine Food Consumption Patterns of Americans. 6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Project 2: Nutritional regulation of tissue anabolism in neonates The scientific results of this project are being disseminated to other scientists in publications and in abstracts/presentations at scientific meetings. The information from the work is published as it becomes available for consideration of implementation for the years of this project. Practical results, applied to humans and animals, will be forthcoming as they are indicated by the research results. The long delay results from the extensive testing for safety and efficiency necessary before acceptance of technologies applied to humans and animals. 7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Project 3: Consequences of perinatal undernutrition for satellite cell function and muscle growth Fiorotto M. 2005. Local IGF-I promotes skeletal muscle growth directly through activation of the type 1 IGF receptor and indirectly by enhancing the activation of the insulin-signaling pathway. FASEB Summer Research Conference. Review Publications Bos, C., Stoll, B., Fouillet, H., Gaudichon, C., Guan, X., Grusak, M.A., Reeds, P.J., Burrin, D.G., Tome, D. 2005. Postprandial intestinal and whole body nitrogen kinetics and distribution in piglets fed a single meal. American Journal of Physiology: Endocrinology and Metabolism. 288(2):E436-E446. Riedijk, M.A., Stoll, B., Chako, S., Cottrell, J., Stephens, J., Sunehag, A., Van Goudoever, J.B., Burrin, D.G. 2005. First-pass intestinal methionine metabolism is limited in enterally-fed piglets. Journal of Federation of American Societies for Experimental Biology. 19:A422. Burrin, D.G., Riedijk, M.A., Stoll, B., Chacko, S., Sunehag, A.L., Van Goudoever, J.B. 2005. Transmethylation and transsulfuration of methionine in the piglet gastrointestinal tract. Gastroenterology. 128:A-552. German, J.B., Bauman, D.E., Burrin, D.G., King, J.C., Klein, S., Milner, J.A., Pelto, G.H., Rasmussen, K.M., Zeisel, S.H. 2004. Metabolomics in the opening decade of the 21st century: building the roads to individualized health. Journal of Nutrition. 134:2729-2732. Kleinman, R.E., Baldassano, R.N., Caplan, A., Griffiths, A.M., Heyman, M.B., Issenman, R.M., Lake, A.M., Motil, K.J., Seidman, E., Udall, J.N. 2004. Nutritional support for pediatric patients with inflammatory bowel disease: a clinical report of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. Journal of Pediatric Gastroenterology and Nutrition. 39:15-27. Erratum: 39:430. Draghia-Akli, R., Fiorotto, M.L. 2004. A new plasmid-mediated approach to supplement somatotropin production in pigs. Journal of Animal Science. 82(8)[E. Suppl.]:E264-E269. Ramsay, T.G., Bush, J.A., McMurtry, J.P., Thivierge, M.C., Davis, T.A. 2004. Peripheral leptin administration alters hormone and metabolite levels in the young pig. Comparative Biochemistry and Physiology. 138(Part A):17-25. Escobar, J., Frank, J.W., Suryawan, A., Nguyen, H.V., Davis, T.A. 2005. A physiological rise in leucine, but not isoleucine or valine, increases protein synthesis and translation initiation factor activation in skeletal muscle of neonatal pigs [abstract]. The 2005 Federation of American Societies for Experimental Biology Conference. Part II(abstract 571.3):A976. Frank, J.W., Escobar, J., Suryawan, A., Nguyen, H.V., Liu, C.W., Kimball, S.R., Jefferson, L.S., Davis, T.A. 2005. Dietary protein and lactose increase protein synthesis via modulation of insulin signaling proteins and translation initiation factors in neonatal pigs [abstract]. The Federation of American Societies for Experimental Biology Conference. Part II (abstract 571.4):A977. Suryawan, A., Frank, J.W., Nguyen, H.V., Liu, W. Davis, T.A. 2005. Expression of TGF-Beta family of ligands is developmentally regulated in skeletal muscle of neonatal rats [abstract]. The Federation of American Societies for Experimental Biology Conference. Part II(abstract 579.2):A985. Oliver, W.T., Lopez, R., Cummings, K.K., Rosenberger, J., Fiorotto, M.L. 2005. Functional significance of developmental changes in muscle IGFBPs for IGF-I signaling [abstract]. The Federation of American Societies for Experimental Biology Conference. Part II(abstract 579.3):A985. Oliver, W.T., Cummings, K.K., Rosenberger, J., Lopez, R., Fiorotto, M.L. 2005. Local IGF-I enhances activation of the muscle IGF-I receptor (IGF-1R) but not of ERK 1/2 "in vivo" [abstract]. The Federation of American Societies for Experimental Biology Conference. Part I (abstract 348.7):A571. Oliver, W.T., Cummings, K.K., Rosenberger, J., Lopez, R., Gomez, A., Fiorotto, M.L. 2005. In vivo, skeletal muscle IGF-I activates Akt directly via the IGF-1R and indirectly by enhancing insulin receptor phosphorylation [abstract]. The Endocrine Society's 87th Annual Meeting "Shaping the Future of Endocrinology: Today's Research...Tomorrow's Care". Abstract P3-715, p. 721. Sweatt, A.J., Wood, M., Suryawan, A., Wallin, R., Willingham, M.C., Hutson, S.M. 2004. Branched-chain amino acid catabolism: Unique segregation of pathway enzymes in organ systems and peripheral nerves. American Journal of Physiology, Endocrinology, & Metabolism. 286(1):E64-E76. Fiorotto, M.L., Lopez, R., Oliver, W.T., Rosenberger, J., Draghia-Akli, R. 2004. Nonplacental growth hormone-releasing hormone (GHRH) is transported from the mother to the fetus in the rat [abstract]. The Endocrine Society's 86th Annual Meeting, June 16-19, 2004, New Orleans, Louisiana. Abstract P3-96, p. 488. Davis, T.A., Fiorotto, M.L. 2005. Regulation of skeletal muscle protein metabolism in growing animals. In: Burrin, D.G., Mersmann, H.J., Salek, E., editors. Biology of Metabolism in Growing Animals. Biology of Growing Animals Series, Volume 3. London, United Kingdom:Elsevier Limited. Part II: Protein Metabolism, Chapter 2, p. 37-68. Riedijk, M.A., Stoll, B., Chako, S., Sunehag, A.L., Van Goudoever, J.B., Burrin, D.G. 2005. Intestinal sulfur amino acid metabolism in neonatal piglets [abstract]. Pediatric Research. 57:1608. Lackeyram, D., Burrin, D.G., Mine, Y., Fan, M.Z. 2005. Changes in the plasma citrulline concentration are a predictor of alterations in gut mucosal morphology and functions in the piglet. Journal of Animal Science. 83 (Suppl. 1):207. Stoll, B., Burrin, D.G. 2005. Measuring splanchnic amino acid metabolism by using stable isotope tracers [abstract]. Journal of Animal Science. 83(Suppl. 1):242. Horst, D.A., Sedenquist, M., Stoll, B., Burrin, D.G. 2005. Glucagon-like peptide 2 decreases a marker of bone resorption in tpn-fed neonatal piglets [abstract]. Pediatric Academic Society Meeting. Pediatric Research. 57:Abstract 1609. 2005 CDROM. Shulman, R., Wong, W.W., Smith, O.E. 2005. Influence of changes in lactase activity and small-intestinal mucosal growth on lactose digestion and absorption in preterm infants. American Journal of Clinical Nutrition. 81:472-479. Thivierge, M.C., Bush, J.A., Suryawan, A., Nguyen, H.V., Orellana, R.A., Burrin, D.G., Jahoor, F., Davis, T.A. 2005. Whole-body and hindlimb protein breakdown are differentially altered by feeding in neonatal piglets. Journal of Nutrition. 135(6):1430-1437. Frank, J.W., Escobar, J., Suryawan, A., Nguyen, H.V., Liu, C.W., Kimball, S.R., Jefferson, L.S., Davis, T.A. 2004. Influence of dietary protein and lactose levels on protein synthesis and translation initiation factor activation in neonatal pigs [abstract]. Journal of Animal Science, Proceedings of the 2004 Joint Annual Meeting of the American Society of Animal Sciences. 82(Suppl. 1):Abstract 766, p. 419. Escobar, J., Frank, J.W., Kimball, S.R., Suryawan, A., Nguyen, H.V., Liu, C.W., Jefferson, L.S., Davis, T.A. 2004. Infusion of a physiological dose of leucine stimulates muscle protein synthesis in neonatal pigs by enhancing the activity of translation initiation factors [abstract]. Journal of Animal Science, Proceedings of the 2004 Joint Annual Meeting of the American Society of Animal Science. 82(Suppl. 1):abstract 767, p. 419. Escobar, J., Frank, J.W., Suryawan, A., Nguyen, H.V., Kimball, S.R., Jefferson, L.S., Davis, T.A. 2005. Physiological rise in plasma leucine stimulates muscle protein synthesis in neonatal pigs by enhancing translation initiation factor activation. American Journal of Physiology, Endocrinology, and Metabolism. 288(5):E914-E921. Frank, J.W., Escobar, J., Suryawan, A., Kimball, S.R., Nguyen, H.V., Jefferson, L.S., Davis, T.A. 2005. Protein synthesis and translation initiation factor activation in neonatal pigs fed increasing levels of dietary protein. Journal of Nutrition. 135(6):1374-1381. Frank, J., Escobar, J., Suryawan, A., Liu, C., Nguyen, H., Davis, T., Wu, G. 2005. 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