Family, Community and Public Health

Hyperleptinemia, Adiposity and Risk of Metabolic Syndrome in Older Adults


Authors: Suruchi Mishra, Nadine Sahyoun, (PhD, RD), and Mira Mehta (PhD)
Department or Program: NFSC
Presented by: Suruchi Mishra
Abstract: Leptin is the product of the ob/ob gene that is associated with obesity and weight loss, cachexia, inflammatory processes, oxidative stress, arterial hypertension, and aging. The elevated serum leptin level in elderly individuals suggests that aging is associated with a decrease in receptors for this hormone and/or resistance to leptin. Additionally, it has been observed that there is an increase in fat mass and abdominal adiposity during aging, as well as an increase in insulin resistance that is frequently associated with leptin resistance and high leptin levels. The aim of the present study is to examine the longitudinal association between serum leptin and the risk of metabolic syndrome (MS) and to investigate the effects of measures of body adiposity (visceral fat, subcutaneous fat, total fat percent, BMI) and proinflammatory cytokines (PAI-1, IL-6, TNFα, CRP) on the potential association of serum leptin with MS. Data of participants in the Health, Aging and Body Composition (HABC) study, aged 70 to 79 years (n=3,075) were used in this study. MS was defined by NCEP ATP III guidelines as having at least 3 of the following risk factors: 1) waist circumference >102 cm for men and >88 cm for women; 2) triglyceride ≥150 mg/dl; 3) high-density lipoprotein cholesterol <40 mg/dl for men and <50 mg/dl for women; 4) blood pressure ≥ 130/85 mmHg; 5) fasting glucose ≥110 mg/dl. Multivariate logistic regression modeling was used to determine the gender specific association between baseline serum leptin and risk of developing MS at 6 year follow up, for persons in quintiles 2 through 5 of serum leptin compared with those in quintile 1 after adjusting for the potential confounders age, race, study site, smoking status, alcohol use, and physical activity. Among females, serum leptin quintile 2 (p=.008), 3 (p=.009), 4 (p=.0002), and 5 (p<.0001) were found to be significantly associated with the MS risk as compared to quintile 1 after adjusting for potential confounders. Serum leptin remained independently associated with MS risk after adjusting for fat depots and proinflammatory cytokines, in females. The results of the present study will help in establishing serum leptin as a marker for predicting the risk of MS among women.

Irrigation workers' exposures to antimicrobial-resistant bacteria and antimicrobials present in reclaimed wastewater


Authors: Rachel Rosenberg Goldstein, Shirley A. Micallef, Ashish George, Amir Sapkota, Shawn G. Gibbs, Sam W. Joseph, Amy R. Sapkota
Department or Program: MIEH
Presented by: Rachel Rosenberg
Abstract: Background: As water shortages become more common, reclaimed wastewater is increasingly being used for irrigation activities. Because of this practice, spray irrigation workers could be exposed to antibiotic-resistant bacteria and antimicrobials that may remain in treated wastewater. Objectives: One goal of our study is to evaluate the presence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), and antimicrobial residues in reclaimed wastewater used for spray irrigation. Our study will also evaluate potential inhalation and dermal exposures to these agents among spray irrigation workers. Methods: Culture methods and polymerase chain reaction (PCR) were used to evaluate the presence of MRSA and VRE in wastewater, spray irrigation water, air, and dermal and nasal swab samples at sites in Maryland and Nebraska. Water membrane filtration and centrifugation were used to isolate MRSA and VRE from water samples. Antimicrobial residues will be analyzed using an isotope dilution liquid chromatography tandem mass spectrometry method. Preliminary Results: From our first sampling session, we found an 31% rate of S. aureus nasal colonization among spray irrigation workers exposed to reclaimed wastewater. As of yet, no S. aureus or MRSA has been isolated from the wastewater or irrigation water samples, but we have isolated methicillin-resistant coagulase negative Staphylococcus (CoNS) from wastewater samples. VRE is present in influent wastewater, but not tertiary treated effluent, or reclaimed wastewater used for spray irrigation. Preliminary Conclusions: Tertiary treatment of wastewater seems to effectively reduce the presence of VRE. The presence of methicillin-resistant CoNS in incoming and treated wastewater presents a possible reservoir of methicillin-resistance genes that could be transferred to S. aureus and other organisms (Hanssen & Ericson Sollid, 2006). Although previous studies have analyzed MRSA in clinical settings and VRE in aquatic environments, no studies have quantified the prevalence of MRSA, VRE, and antimicrobials in reclaimed wastewater and biological samples collected from spray irrigation workers. Our findings will be important in assessing possible microbial and chemical risks from using reclaimed wastewater, which is likely to become a more common water source.

The relationship between perceived racial discrimination and health outcomes in an urban African American community cohort


Authors: Deliya R. Banda, MPH and Kerry M. Green, PhD
Department or Program: HLTH
Presented by: Deliya Banda
Abstract: A growing body of literature documents the relationship between social stressors and health outcomes. Experiences of racial discrimination, an important social stressor among minority groups, has been proposed as a key determinant of health, and may account in part for increased risk of disease seen among African Americans relative to other groups (Macinko, Shi, Starfield, & Wulu, 2003; Shi, Macinko, Starfield, Politzer, & Xu, 2005). Hence there is a need for research which investigates both the upstream determinants of perceived discrimination and the downstream mechanisms by which discrimination affects health outcomes (Borrell, Cataerina et. al, 2006). This study explores the experience of racial discrimination as it relates to health outcomes in a community cohort of urban African Americans followed longitudinally. This analysis characterizes the sources and rates of perceived racial discrimination within our sample and examines their association with both physical and mental health outcomes. Consistent with the current literature, we also examine the extent to which perceptions of racial discrimination are associated with other life adversities, such as poverty, disadvantaged neighborhood circumstance, and lack of employment.

Low-Volume/Moderate-Intensity Aerobic Training Improves Insulin Action in Obese Minority Adolescent Females


Authors: Gina Many, Maria-Eugenia Hurtado, Joseph A. Houmard, Charles J. Tanner, Jung-Jung Park, Christopher F. Spurney, Eric P. Hoffman
Department or Program: KNES
Presented by: Gina Many
Abstract: The most pronounced declines in physical activity occur in early adolescence and are thought to significantly contribute to adolescent-onset obesity and type 2 diabetes. Washington DC youth are among the heaviest in the nation and are at increased risk of obesity-related complications due the large proportion of minorities (Black, Latino) and the obesogenic environment. The magnitude of aerobic training-induced improvements on type 2 diabetes risk factors have never been studied in this high-risk minority population, warranting a need for interventional assessments. PURPOSE: To examine the effects of two-months of low-volume/moderate-intensity aerobic training on insulin action in previously sedentary and obese (BMI 40 ± 1.93 kg/m2) minority adolescent females residing in Washington DC. METHODS: Black (B) and Latino (L) adolescents at high risk for insulin resistance were recruited through the local community. Inclusion criteria consisted of non-diabetic insulin resistance (OGTT); sedentary behavior; BMI-for-age >95th percentile; non-smoker; no history of chronic illness known to affect glucose metabolism; not pregnant or lactating. Subjects completed two-months of supervised aerobic training (~180 min/wk at 40-55% VO2peakR to expend ~1200 kcal/wk) after a one-month training ramp-up. Aerobic fitness (VO2peak), body composition (DEXA) and insulin sensitivity (SI from a FSIVGTT) were assessed before and after exercise training. RESULTS: S I improved ~37% (1.00 ± 0.15 to 1.37 ± 0.26 µUl-1min-1, p<0.05) in response to training (n=7; 5B/2L). There were no significant changes (p>0.05) in fasting insulin (21.67 ± 4.20 vs. 21.59 ± 3.82 µU/ml), fasting glucose (81.8 ± 2.33 vs. 79.53 ± 2.49 mg/dl) and AIRg (2.18 ± 0.63 vs. 1.54 ± 0.29 mU/mM). Improvements in insulin action were observed despite non-significant changes in BMI (40.16 ± 1.93 to 39.51 ± 2.03 kg/m2, p>0.05) and minimal reductions in total body fat percentage (45.42 ± 1.17 to 44.12 ± 0.91, p<0.05). CONCLUSION: Initiation of a low-volume/moderate-intensity aerobic training program improved insulin action in this group of obese and insulin-resistant Washington DC adolescent minority females. Our findings are of public health relevance as they demonstrate the ability of aerobic training to enhance insulin action in this very high-risk population.