has part is about declares time sampled measurement data set intervention design study design independent variable repeated measure design cross over design (source: http://www.sbu.se/Filer/Content0/publikationer/1/literaturesearching_1993/glossary.html) PMID: 17601993-Objective: HIV-infected patients with lipodystrophy (HIV-lipodystrophy) are insulin resistant and have elevated plasma free fatty acid (FFA) concentrations. We aimed to explore the mechanisms underlying FFA-induced insulin resistance in patients with HIV-lipodystrophy. Research Design and Methods: Using a randomized placebo-controlled cross-over design, we studied the effects of an overnight acipimox-induced suppression of FFA on glucose and FFA metabolism by using stable isotope labelled tracer techniques during basal conditions and a two-stage euglycemic, hyperinsulinemic clamp (20 mU insulin/m(2)/min; 50 mU insulin/m(2)/min) in nine patients with nondiabetic HIV-lipodystrophy. All patients received antiretroviral therapy. Biopsies from the vastus lateralis muscle were obtained during each stage of the clamp. Results: Acipimox treatment reduced basal FFA rate of appearance by 68.9% (52.6%-79.5%) and decreased plasma FFA concentration by 51.6 % (42.0%-58.9%), (both, P < 0.0001). Endogenous glucose production was not influenced by acipimox. During the clamp the increase in glucose-uptake was significantly greater after acipimox treatment compared to placebo (acipimox: 26.85 (18.09-39.86) vs placebo: 20.30 (13.67-30.13) mumol/kg/min; P < 0.01). Insulin increased phosphorylation of Akt (Thr(308)) and GSK-3beta (Ser(9)), decreased phosphorylation of glycogen synthase (GS) site 3a+b and increased GS-activity (I-form) in skeletal muscle (P < 0.01). Acipimox decreased phosphorylation of GS (site 3a+b) (P < 0.02) and increased GS-activity (P < 0.01) in muscle. Conclusion: The present study provides direct evidence that suppression of lipolysis in patients with HIV-lipodystrophy improves insulin-stimulated peripheral glucose-uptake. The increased glucose-uptake may in part be explained by increased dephosphorylation of GS (site 3a+b) resulting in increased GS activity. Philippe Rocca-Serra a repeated measure design which ensures that experimental units receive, in sequence, the treatment (or the control), and then, after a specified time interval (aka *wash-out periods*), switch to the control (or treatment). In this design, subjects (patients in human context) serve as their own controls, and randomization may be used to determine the ordering which a subject receives the treatment and control cross over design time series design block design blocking variable within subject comparison objective metadata complete obi.owl