Hormone-sensitive lipase activity (HSL), which is found in the supernatant of centrifuged homogenates of lipolytically quiet isolated rat adipocytes, was greatly reduced in or absent from the supernatant of lipolytically stimulated cells. The lipase was purified 100-to 250-fold from the supernatant of lipolytically quiet cells to 10-20% purity by a single passage over phenyl-Sepharose resin with high (>70%) activity yields. Western blotting of adipocyte homogenate fractions with polyclonal antiserum raised against HSL showed that the enzyme shifted quantitatively from the supernatant of control cells to the floating "fat cake" of lipolytically stimulated cells. A similar shift to the fat cake was observed when cells were disrupted by hypotonic lysis and centrifugation rather than by homogenization. We propose that upon lipolytic activation of adipocytes and phosphorylation ofHSL by cAMPdependent protein kinase, the critical event is not an increase in catalytic activity (i.e., turnover number) but a translocation of the lipase to its substrate at the surface of the lipid storage droplet.

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The P-MIM showed promise for preventing weight gain in low-income overweight and obese women. However, a larger experimental trial is warranted to determine the effectiveness of this intervention.

BackgroundRecruitment and retention are key functions for programs promoting nutrition and other lifestyle behavioral changes in low-income populations. This paper describes strategies for recruitment and retention and presents predictors of early (two-month post intervention) and late (eight-month post intervention) dropout (non retention) and overall retention among young, low-income overweight and obese mothers participating in a community-based randomized pilot trial called Mothers In Motion.MethodsLow-income overweight and obese African American and white mothers ages 18 to 34 were recruited from the Special Supplemental Nutrition Program for Women, Infants, and Children in southern Michigan. Participants (n = 129) were randomly assigned to an intervention (n = 64) or control (n = 65) group according to a stratification procedure to equalize representation in two racial groups (African American and white) and three body mass index categories (25.0-29.9 kg/m2, 30.0-34.9 kg/m2, and 35.0-39.9 kg/m2). The 10-week theory-based culturally sensitive intervention focused on healthy eating, physical activity, and stress management messages that were delivered via an interactive DVD and reinforced by five peer-support group teleconferences. Forward stepwise multiple logistic regression was performed to examine whether dietary fat, fruit and vegetable intake behaviors, physical activity, perceived stress, positive and negative affect, depression, and race predicted dropout as data were collected two-month and eight-month after the active intervention phase.ResultsTrained personnel were successful in recruiting subjects. Increased level of depression was a predictor of early dropout (odds ratio = 1.04; 95% CI = 1.00, 1.08; p = 0.03). Greater stress predicted late dropout (odds ratio = 0.20; 95% CI = 0.00, 0.37; p = 0.01). Dietary fat, fruit, and vegetable intake behaviors, physical activity, positive and negative affect, and race were not associated with either early or late dropout. Less negative affect was a marginal predictor of participant retention (odds ratio = 0.57; 95% CI = 0.31, 1.03; p = 0.06).ConclusionDropout rates in this study were higher for participants who reported higher levels of depression and stress.Trial registrationCurrent Controlled Trials NCT00944060