Effects of Iron on Bone Micro-architecture and Strength in Female Rats During Rapid Growth and Following Ovariectomy

This study investigated the effects of varying levels of dietary iron on bone micro-architecture and strength of female rats. Weanling rats were fed with one of three levels of dietary iron: 6 ppm, 35 ppm or 150 ppm. At 18 weeks of age growing rats were killed and bones were collected. Ovariectomy was performed to mimic menopause or sham-operated as controls at 18 weeks in the other two groups. After 30 weeks of age both sham-operated and ovariectomized rats were killed and bones were collected. Right femur and fifth lumbar (L5) vertebrae were used for analyzing the bone micro-architecture and strength using micro-computed tomography (CT-40, SCANCO MEDICAL AG, Zurich, SW). Iron deficiency significantly decreased L5 architecture (Tb.N, Tb.Sp) and strength (Phy_fce, Strain, Stiffness, SIS) and increased Von Mises in growing rats. Femur architecture indicated by degree of anisotropy (DA) but not strength was affected by diet. Sham L5 architecture (BV.TV, Tb.N) was significantly greater and DA was lower indicating better quality bone than in OVX. A diet x treatment interaction was found for connectivity density with greater density in the 150 ppm sham rats. Shams had significantly greater L5 strength (Phy_fce, Strain, Stiffness, SIS) with a diet x treatment interaction for Von Mises (35 ppm OVX greater than all others and 150 ppm OVX less than 6 and 35 ppm sham and OVX). No diet, treatment or interactions were found in any group in femur mid-shaft cortical architecture. Our findings suggest that dietary iron affects bone micro-architecture and strength in low iron fed growing animals but not in sham and OVX. The diet by treatment interactions suggests that high iron may be detrimental to some. However, it was not clear what levels of iron when combined with estrogen deficiency would be detrimental with aging. Our findings also suggest that the effect of iron changes with skeletal site since we found significant effects in lumbar bone but not on distal femur or midshaft.Department of Nutritional Science

The Effects of Zinc on Homeostasis, Growth and Oxidative Stress Responses in Cultured Cells

Zinc is involved in many physiological processes and is required as a catalytic cofactor for more than 300 metalloenzymes. Zinc levels are tightly regulated for maintaining cellular homeostasis. Previous studies from our laboratory with radioactive 65Zn demonstrated that cancer cell lines decrease zinc efflux when zinc availability is deprived with the extracellular metal chelator DTPA (diethylenetriaminepentaacetic acid). Primary cell lines, however, give out more zinc under the same conditions. The focus of this dissertation is to further examine these differential homeostatic responses and to investigate the underlying mechanisms. ^ This dissertation is comprised of three majorstudies investigating (1) the differential zinc homeostasis in rat lymphoma and hepatoma cell lines, (2) the effects of immortalizing rat hepatocytes and knock down of the plasma membrane localized zinc efflux transporter ZnT-1 on cellular responses to DTPA, and (3) the effects of altered zinc availability on viability and oxidative stress in a hepatoma cancer cell line. Findings suggest that (1) depletion of extracellular zinc induces a decrease in retention of zinc, a depletion of glutathione levels and an increase in oxidative stress in lymphoma cells, (2) transformation of hepatocytes result in greater retention of zinc in the face of limited availability, (3) ZnT-1 is crucial for zinc retention during zinc deficiency in cancer cells, and (4) both zinc and zinc deficiency induce oxidative stress, activating p53 and leading to two different mechanisms of apoptotic cell death. Taken together, these data suggest that transformed cells increase zinc retention to meet their growth demands under conditions of zinc deprivation, perhaps by altering the activity of ZnT-1. Although, cancer cells alter homeostatic response to survive with limited zinc availability, exposure to diminished or increased zinc concentrations leads to apoptosis and/or necrosis. Overall, these studies provide greater insights for understanding cellular zinc homeostasis and the complex roles that zinc plays in physiological processes.

The Relationship between Macronutrient Distribution and Type 2 Diabetes in Asian Indians

Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.Asian Indians (AIs) are at increased risk for type 2 diabetes mellitus than other ethnic groups. AIs also have lower body mass index (BMI) values than other populations, so can benefit from strategies other than weight reduction. Macronutrient distributions are associated with improved glycemic control; however, no specific distribution is generally recommended. This study looks at whether a macronutrient distribution of 50:30:20 (percent of total calories from carbohydrates, fats, and protein) is related to diabetes status in AIs. Diet and Hemoglobin A1c (HbA1c) were assessed from convenience sample of AI adults in Maryland. A ratio of actual to needed calories using the 50:30:20 macronutrient distribution was then tested against diabetes status to identify associations. All groups except non-diabetic females, were in negative energy balance. The non-diabetic group consumed larger actual to needed ratios of protein than pre-diabetics and diabetics. However, all groups consumed protein at the lower end of the Acceptable Macronutrient Distribution Range (AMDR), and the quality of all macronutrients consumed was low. Therefore, weight loss may not be the recommendation for diabetes management for AIs. Increasing protein and insoluble fiber consumption, could play a critical role

Diet Quality and Nutrition Behavior of Federal Nutrition Education Program Participants before and during the COVID-19 Pandemic

Despite challenges due to the COVID-19 pandemic, reports from regional and national meetings of the Expanded Food and Nutrition Education program (EFNEP) have provided anecdotal evidence that the program has persevered, pivoted, and continued to positively impact the lives of some of the nation’s most vulnerable populations. However, there have been necessary changes to program delivery, inevitable changes in the lives of participants, and changes in the food environment that may have impacted program outcomes. This study compares national EFNEP data (demographics, behavior change data, and 24 h dietary recall data) of participants from two federal fiscal years, before the COVID-19 pandemic and during the pandemic. Linear mixed model analysis of variance and covariance were used to assess the effects of year on program outcomes. Results of this study provide quantitative evidence of the resiliency of EFNEP to facilitate positive behavior changes related to diet quality, physical activity, food safety, food resource management, and food security. Amidst changes in the food environment during the COVID-19 pandemic, these results emphasize the importance and value of federal nutrition education programs in any food environment

Conducting 24-Hour Dietary Recalls in Group Settings with Adults Having Low-Income: Perspectives of EFNEP Peer Educators

The Expanded Food and Nutrition Education Program (EFNEP) is a federally funded program that teaches nutrition education to adults and youth with low-income. EFNEP is funded throughout the United States including federal territories. The purpose of EFNEP is to provide nutrition education. Evaluation for adult programs includes pre/post surveys and pre/post 24-h diet recalls (24HDR). A validated standard of dietary measures, 24HDR are useful when collected as designed: one-on-one by a trained professional. In EFNEP, 24HDR are collected in group settings by EFNEP peer educators who often have not received a college degree or any formal education in nutrition. The purpose of this study was to explore attitudes and behaviors of EFNEP peer educators regarding how they collect diet recalls in a group setting, their perceptions of how adult participants feel about the recalls, and the benefits and challenges of using recalls. Online interviews were conducted with EFNEP peer educators across the U.S. Peer educators recognized the importance of collecting the recall data but identified several challenges such as time, resources, and participant reluctance to complete the recall. Program evaluation through methods like the 24HDR is important to measure outcomes and inform program improvements but also needs to include how evaluation can benefit participants and minimize data collection burden. Future research needs to examine the validity of collecting recalls in a group setting compared to other measures of diet quality