1a.Objectives (from AD-416)
Objective 1: Determine acceptability of types of carbohydrate-containing foods recommended in the Dietary Guidelines and measure their effects on appetite, satiety, and energy balance. Objective 2: Determine how Dietary Guideline recommendations for types of dietary fat affect partitioning of lipids, formation of pro-inflammatory oxy-lipins, and in turn, alter risk of unhealthy weight gain, body fat gain, and cardiovascular risk factors. Objective 3: Determine how potential modulators of metabolism, such as physical activity and stress, impact the response to food and affect weight and body fat distribution. Objective 4: Identify molecular factors that influence critical metabolic pathways in body weight regulation and determine if gene expression is responsive to dietary and physical activity interventions related to the Dietary Guidelines. Objective 5: Identify, among low- and middle-income groups, specific barriers to and facilitators for adopting the dietary and physical activity recommendations of the Dietary Guidelines. The research comprises studies that address the Dietary Guidelines for carbohydrates, fats, or physical activity. We will test how recommendations for whole grains, added sugar, types of polyunsaturated fatty acids, or physical activity affect metabolic health.

1b.Approach (from AD-416)
We will use a multidisciplinary approach to test molecular, physiological, and metabolic responses to dietary patterns composed of whole foods, determine how physical activity, stress, and genetic factors modify these responses, and identify important behavioral and psychosocial factors related to adopting the Dietary Guidelines. Our work will use classical investigations of metabolic and energetic response along with metabolomic analysis to investigate these questions and will link these phenotypic descriptions with gene expression profiles. Randomized controlled trials, a longitudinal observation study, and community focus groups and interviews will be conducted to test metabolic health and obtain information about behavior related to the Dietary Guidelines. Important studies in animal models will complement this work to gain understanding of underlying mechanisms associated with specific dietary interventions or to obtain proof of concept before designing and conducting human trials. Replacing 5306-51000-002-00D (3/06).

3.Progress Report
Research Program in Behavioral Nutrition (Obj 5). A new SY joined this project in FY2007 and is studying factors related to healthy eating. He obtained a UC Davis Imaging Research Center Pilot Program Grant in 2007 and will examine whether and how psychosocial stress alters neural responses to different categories of food cues in humans. Key factors will be identified that potentially trigger and perpetuate unhealthy eating behaviors, subsequent obesity and the metabolic syndrome. These data will form the basis of future studies that will address the effects of exercise and/or diet on the neurobehavioral changes promoted by psychological stress. A California National Primate Research Center Pilot Research Program grant will be used to identify interrelationships between the peripheral metabolome and brain stress systems that mediate changes in appetite and eating behaviors related to the dietary relapse that commonly occurs in stress-vulnerable individuals restricting their caloric intake. Experimental models and paradigms developed by this SY are being used to assess specific dietary and physical activity interventions that mitigate unhealthy eating decisions that result from neurobehavioral factors related to psychological stress.

Biomarkers for Muscle Fat Combustion (Obj 1): Limited capacity for fat combustion in muscle has been associated with poor metabolic health, reduced insulin sensitivity, and diabetes. Identification of biomarkers of muscle-specific fat combustion would be of value for health assessment and intervention evaluation. Metabolomics technologies are being applied to unique biological systems in which muscle fat metabolism is up- or down-regulated. Through collaboration with scientists at University of Alabama, the plasma metabolome of African-Americans who harbor a genetic shift that causes disruption in the muscle enzyme UCP3 and mitochondrial fat catabolism was characterized, acyl-carnitine analyses were completed, and data are being evaluated. New methods were instituted to determine broad metabolite shifts in isolated mitochondria burning palmitate. These novel studies promise to be some of the first ever to uncover unanticipated metabolites associated with muscle lipid catabolism and that can be used as biomarkers to evaluate nutritional and physical activity interventions that improve insulin sensitivity.

Biomarkers of Whole Grain Intake (Obj 1): Biomarkers of whole grain intake are needed to better understand the relationship between whole grains and disease prevention. Using samples generated from a study comparing whole grain with refined grain consumption, we have characterized the plasma metabolome and determined that unique patterns of metabolites exist after acute exposure to a whole grain cereal and after 3-days of controlled intake of diet pattern based on whole grains. Identifying key metabolites specific to whole grain consumption and determining sensitivities to dose hold promise as a valid approach to quantifying whole grain intake in dietary survey studies and intervention studies.

4.Accomplishments
Characterization of Tusc5, an Adipocyte Gene Uniquely Co-Expressed in Peripheral Afferent Neurons. In ongoing studies, Scientists at the WHNRC, Davis, CA are characterizing the biology of this unique adipocyte gene in terms of its role in regulating adiposity, fat tissue function, and to better understand how nutrition and obesity influence its expression and activity in fat and neurons. The functional and anatomical connections between afferent neurons and adipose tissue are important in regulating how external and peripheral tissue cues influence energy balance-related pathways, and ultimately how healthy body weight is maintained. In FY2007, we generated a series of important findings, including: (a) Tusc5 expression is specific to adipocytes and afferent peripheral neurons, (b) initial studies with newly-built gene knockdown vectors indicate that loss of Tusc5 during adipogenesis seriously attenuates normal fat cell development, lipid storage, and glucose utilization (c) modest, but statistically-significant reductions in adipose Tusc5 expression is observed in some obese human cohorts, (d) Tusc5 is induced by activites related to the nuclear receptor peroxisome proliferator activated receptor-gamma (PPARg), and preliminary evidence from a collaboration with Jae Bum Kim, Seoul National University, indicates that the Tusc5 gene interacts physically with PPARg. We believe our findings, in conjunction with what has been seen with Synuclein-gamma (SNCG) indicate that Tusc5 and SNCG are critical for governing adipose tissue “plasticity” in terms of cellular transitions toward a fully-mature phenotype versus less mature state supportive of adipose proliferation or major functional shifts--this provides a link between the adiposity, adipose functional characteristics, and ultimately, health. The molecular regulators of adipocyte or neuron plasticity have not previously been fully-elucidated. This accomplishment relates to NP107, Component 6: Prevention of obesity and disease: relationship between diet, genetics, and lifestyle.

Investigations of Tusc5 Led to Discovery of a Second Adipocyte-Neuron Gene, Synuclein-gamma (SNCG). Scientists at the WHNRC, Davis, CA identified SNCG as a second gene expressed in both adipocytes and peripheral afferent neurons (see discussion above regarding the importance of neuronal circuits and adipose in regulating energy balance). Unlike Tusc5, which appears to be involved with promoting entry into and persistence of the growth-arrested mature fat cell phenotype, evidence from the literature indicating SNCG triggers exit from growth arrest suggests a role in adipocyte proliferation. We have determined that SNCG is (a) downregulated by PPARg agonism, (b) induced during adipogenesis, (c) significantly increased in obese human WAT determined in three independent cohorts. Our preliminary findings in a collaboration with Dr. James Pan, Campbell Family Institute for Breast Cancer Research, indicate that knockdown of SNCG reduces cancer cell survival, suggestive of a growth promoting role of the protein. This accomplishment relates to NP107, Component 6: Prevention of obesity and disease: relationship between diet, genetics, and lifestyle.

Application of a Fructose Assay to Human Fructose Challenge Trials to Identify Persons At-Risk for Fructose-Related Hypertriglyceridemia. With increasing use of high-fructose corn syrup (HFCS) and sweetened foods, some believe the population’s risk for developing metabolic conditions such as obesity, hypertriglyceridemia, and insulin resistance is heightened. More physiological research regarding differences between fructose and glucose are required to more fully evaluate this concern, and to understand if a subset of the population are at-risk for fructose-related metabolic dysregulation. Scientists at the WHNRC, Davis, CA in collaboration with University of California-Davis scientists, we have assessed plasma fructose excursions post-meal challenge and discovered remarkable person-to-person variability. This variability appears to correlate very tightly with indices of triglyceridemia, supporting a working hypothesis that individuals at-risk for hypertriglyceridemia generally, and in response to fructose specifically, display reduced fructose excursions presumably due to avid liver uptake and conversion to triglycerides. This accomplishment relates to NP107, Component 6: Prevention of obesity and disease: relationship between diet, genetics, and lifestyle.

Consuming Beverages Sweetened with High Fructose Corn Syrup or Sucrose Induces Postprandial Triglyceridemia Similar to That Observed with Fructose Ingestion. High fructose corn syrup (HFCS) has replaced sucrose to become the predominant sweetener used in beverages, but little data exist to demonstrate the metabolic effects associated with controlled consumption of these sweeteners. In collaboration with University of California-Davis scientists, we found that consumption of sucrose- or HFCS-sweetened beverages produced similar patterns of postprandial glucose, insulin, leptin, ghrelin or triglyceride concentrations in blood. Increases in circulating triglycerides following consumption of beverages with HFCS or sucrose were comparable to those observed with fructose-sweetened beverages. The findings suggest that acute consumption of any of these three sweeteners—HFCS, sucrose, or fructose—elevates postprandial triglyceride concentrations, a known risk factor for atherogenesis and cardiovascular disease. This accomplishment relates to NP107, Component 6: Prevention of obesity and disease: relationship between diet, genetics, and lifestyle.

Whole Grain Consumption Improves Cardiovascular Risk Profiles. Several epidemiological studies have linked consumption of unrefined, whole grains to reduced risk for acquiring type 2 diabetes and coronary heart disease, but few controlled feeding trials have been conducted to evaluate this association. We evaluated the short-term effects of consumption of a diet pattern based on whole grains and cereals on cardiovascular disease risk profile, energy and lipid metabolism, hunger and satiety in adult women. Compared to consumption of a diet based on refined cereals and grains, consumption of the whole grain diet reduced circulating levels of insulin and triglycerides, increased fat combustion for energy, and increased satiety in the short-term. The postprandial lipoprotein pattern in circulation following meals based on whole grains or refined grains had a reduced number of LDL particles and a decrease in the relative amount of apoprotein C-III associated with triglyceride-rich lipoproteins. If the observed metabolic outcomes are sustained with long-term consumption of this type of diet, unhealthy weight gain could be prevented as whole body metabolism shifts to favor oxidation, not deposition of ingested fat. The reduced atherogenic properties of the circulating lipoprotein profile associated with the whole grain meal suggests that with long-term consumption of this type of diet, development of cardiovascular disease might be reduced or delayed. This accomplishment relates to NP107, Component 5: Health-promoting properties of plant and animal foods.

Proteinuria Alters Lipoprotein Oxylipid Concentrations. Microalbuminuria, the excretion of small amounts of protein in the urine, is common in patients with hypertension and diabetes is associated with cardiovascular disease (CVD), altered plasma lipids and lipoprotein structure. The alteration in lipoprotein structure may be a causal link to CVD, since lipoproteins can influence inflammation, vascular tension, vascular permeability and oxidative stress. A non-obese rodent model with renal insufficiency and a very low density lipoprotein clearance deficit was used to evaluate the impact of this physiological dysfunction on oxidized lipid composition and distribution in lipoproteins. We found that a very low density lipoprotein clearance defect resulted in elevated concentrations of oxidized polyunsaturated lipids in the very low and high density lipoprotein density classes, while low density lipoproteins were depleted in these lipids; the pattern of lipids retained in each particle fraction was distinct, suggesting that a dynamic enzymatic process is responsible for remodeling the oxylipid content of the lipoproteins. Since many oxidized lipids in free fatty acids are potent regulators of vascular physiology and inflammation, these findings provide novel perspective on the interrelationship between proteinuria, hypertriglyceridemia, and cardiovascular disease. This accomplishment relates to NP107, Component VI: Prevention of obesity and disease: relationship between diet, genetics, and lifestyle.

5.Significant Activities that Support Special Target Populations
None.

6.Technology Transfer

Number of new CRADAs and MTAs	1
Number of non-peer reviewed presentations and proceedings	9

Review Publications
Keim, N.L., Motton, D.D., Tenorio, F.A., Horn, W.F., Rutledge, J.C. Postprandial monocyte activation in response to meals with high and low glycemic loads in overweight women. American Journal of Clinical Nutrition. 2007; 85:60-65.