Blood Pressure-Lowering Mechanisms of the DASH Dietary Pattern

Potential blood pressure- (BP-) lowering mechanisms of the DASH dietary pattern were measured in 20 unmedicated hypertensive adults in a controlled feeding study. At screening, participants averaged 44.3 ± 7.8 years, BMI 33.9 ± 6.6 Kg/m2, and BP 144.2 ± 9.38/88.5 ± 6.03 mmHg. All consumed a control diet for one week, then were randomized to control or DASH for another two weeks (week one and two). With DASH, but not controls, SBP fell by 10.65 ± 12.89 (P = 0.023) and 9.60 ± 11.23 (P = 0.039) mmHg and DBP by 5.95 ± 8.01 (P = 0.069) and 8.60 ± 9.13 mmHg (P = 0.011) at the end of week one and two, respectively. Univariate regressions showed that changes in urinary sodium/potassium ratio (β = 1.99) and plasma renin activity (β = −15.78) and percent change in plasma nitrite after hyperemia were associated with SBP changes at week one (all P < 0.05). Plasma nitrite following hyperemia showed a treatment effect (P = 0.014) and increased at week two (P = 0.001). Pulse wave velocity decreased over time with DASH (trend P = 0.019), and reached significance at week two (P = 0.026). This response may be mediated by an improvement in upregulation of nitric oxide bioavailability. Early natriuresis and reductions in oxidative stress cannot be ruled out. Future studies are needed to verify these findings, assess the possibility of earlier effects, and examine other potential mediators

Gene by Sex Interaction for Measures of Obesity in the Framingham Heart Study

Obesity is an increasingly prevalent and severe health concern with a substantial heritable component and marked sex differences. We sought to determine if the effect of genetic variants also differed by sex by performing a genome-wide association study modeling the effect of genotype-by-sex interaction on obesity phenotypes. Genotype data from individuals in the Framingham Heart Study Offspring cohort were analyzed across five exams. Although no variants showed genome-wide significant gene-by-sex interaction in any individual exam, four polymorphisms displayed a consistent BMI association (P-values .00186 to .00010) across all five exams. These variants were clustered downstream of LYPLAL1, which encodes a lipase/esterase expressed in adipose tissue, a locus previously identified as having sex-specific effects on central obesity. Primary effects in males were in the opposite direction from females and were replicated in Framingham Generation 3. Our data support a sex-influenced association between genetic variation at the LYPLAL1 locus and obesity-related traits

Measurement of Weight in Clinical Trials: Is One Day Enough?

Background. Weight is typically measured on a single day in research studies. This practice assumes negligible day-to-day weight variability, although little evidence exists to support this assumption. We compared the precision of measuring weight on one versus two days among control participants in the Weight Loss Maintenance trial. Methods. Trained staff measured weight on two separate days at baseline, 12 months, and 30 months (2004–2007). We calculated the standard deviation (SD) of mean weight change from baseline to the 12- and 30-month visits using (a) the first and (b) both daily weights from each visit and conducted a variance components analysis (2009). Results. Of the 316 participants with follow-up measurements, mean (SD) age was 55.8 (8.5) years, BMI was 30.8 (4.5) kg/m2, 64% were women, 36% were black, and 50% were obese. At 12 months, the SD of mean weight change was 5.1 versus 5.0 kg using one versus two days of weight measurements (P = .76), while at 30 months the corresponding SDs were 6.3 and 6.3 kg (P = .98). We observed similar findings within subgroups of BMI, sex, and race. Day-to-day variability within individuals accounted for <1% of variability in weight. Conclusions. Measurement of weight on two separate days has no advantage over measurement on a single day in studies with well-standardized weight measurement protocols

Blood Pressure-Lowering Mechanisms of the DASH Dietary Pattern

Potential blood pressure-(BP-) lowering mechanisms of the DASH dietary pattern were measured in 20 unmedicated hypertensive adults in a controlled feeding study. At screening, participants averaged 44.3 ± 7.8 years, BMI 33.9 ± 6.6 Kg/m 2 , and BP 144.2 ± 9.38/88.5 ± 6.03 mmHg. All consumed a control diet for one week, then were randomized to control or DASH for another two weeks (week one and two). With DASH, but not controls, SBP fell by 10.65±12.89 (P = 0.023) and 9.60±11.23 (P = 0.039) mmHg and DBP by 5.95 ± 8.01 (P = 0.069) and 8.60 ± 9.13 mmHg (P = 0.011) at the end of week one and two, respectively. Univariate regressions showed that changes in urinary sodium/potassium ratio (β = 1.99) and plasma renin activity (β = −15.78) and percent change in plasma nitrite after hyperemia were associated with SBP changes at week one (all P &lt; 0.05). Plasma nitrite following hyperemia showed a treatment effect (P = 0.014) and increased at week two (P = 0.001). Pulse wave velocity decreased over time with DASH (trend P = 0.019), and reached significance at week two (P = 0.026). This response may be mediated by an improvement in upregulation of nitric oxide bioavailability. Early natriuresis and reductions in oxidative stress cannot be ruled out. Future studies are needed to verify these findings, assess the possibility of earlier effects, and examine other potential mediators

Psychosocial predictors of weight regain in the weight loss maintenance trial

This study's purpose was to identify psychosocial predictors of weight loss maintenance in a multi-site clinical trial, following a group-based weight loss program. Participants (N = 1025) were predominately women (63 %) and 38 % were Black (mean age = 55.6 years; SD = 8.7). At 12 months, higher SF-36 mental health composite scores were associated with less weight regain (p < .01). For Black participants, an interaction existed between race and friends' encouragement for exercise, where higher exercise encouragement was related to more weight regain (p < .05). At 30 months, friends' encouragement for healthy eating was associated with more weight regain (p < .05), whereas higher SF-36 mental health composite scores were related to less weight regain (p < .0001). Perceived stress and select health-related quality of life indices were associated with weight regain; this relationship varied across gender, race, and treatment conditions. Temporal changes in these variables should be investigated for their impact on weight maintenance

PS2-34: Implementation Cost Analysis of Telephone and Internet-based Interventions for the Maintenance of Weight Loss

Objectives: The Weight Loss Maintenance Trial (WLM) was a multi-center, randomized trial comparing two weight loss maintenance interventions, a telephone-based personal contact program (PC) with monthly contacts primarily by phone and an Internet-based program (IT), to a self-directed control group, among overweight or obese individuals at high cardiovascular risk. This presentation describes the implementation costs of both interventions as well as the development costs of the IT program