Group behavioral activation with and without a smartphone app in intensive outpatient treatment for substance use disorder: A three-arm randomized controlled trial.

INTRODUCTION: Reward deficits negatively impact recovery from substance use disorder (SUD). LETS ACT, a behavioral activation treatment targeting substance-free reward, has demonstrated effectiveness in reducing post treatment substance use. There remains room for modifications to extend recovery gains, and LETS ACT remains largely untested in outpatient treatment. We tested the effect of LETS ACT when delivered alongside intensive outpatient SUD treatment, with and without a smartphone app designed to extend access to treatment content outside of clinician-administered sessions. METHODS: In this three-arm randomized controlled trial (N = 206; 54 % White, 67 % male), all participants received intensive outpatient SUD treatment as usual (TAU) and either LETS ACT (n = 56), smartphone-enhanced LETS ACT (n = 65), or assessments only (n = 61). Substance use days and substance related problems were assessed through 12 months posttreatment. RESULTS: Generalized estimating equations indicated a significant condition*time interaction for substance use days; Days of substance use significantly declined from pretreatment until 1-month for TAU, 3-months for LETS ACT-SE, and 6-months for LETS ACT. Decreases in substance-related problems were maintained across all conditions through 12 months. CONCLUSIONS: Adding LETS ACT to intensive outpatient treatment resulted in significant decreases in substance use through 6 months posttreatment, yet these gains were not sustained through 12 months posttreatment. A smartphone app did not facilitate superior treatment outcomes. Future studies should consider factors impacting treatment efficacy in outpatient settings and the utility of providing more than six sessions of behavioral activation.

Changes in conformation at the cytoplasmic ends of the fifth and sixth transmembrane helices of a yeast G protein-coupled receptor in response to ligand binding.

The third intracellular loop (IL3) of G protein-coupled receptors (GPCRs) is an important contact domain between GPCRs and their G proteins. Previously, the IL3 of Ste2p, a Saccharomyces cerevisiae GPCR, was suggested to undergo a conformational change upon activation as detected by differential protease susceptibility in the presence and absence of ligand. In this study using disulfide cross-linking experiments we show that the Ste2p cytoplasmic ends of helix 5 (TM5) and helix 6 (TM6) that flank the amino and carboxyl sides of IL3 undergo conformational changes upon ligand binding, whereas the center of the IL3 loop does not. Single Cys substitution of residues in the middle of IL3 led to receptors that formed high levels of cross-linked Ste2p, whereas Cys substitution at the interface of IL3 and the contiguous cytoplasmic ends of TM5 and TM6 resulted in minimal disulfide-mediated cross-linked receptor. The alternating pattern of residues involved in cross-linking suggested the presence of a 3(10) helix in the middle of IL3. Agonist (WHWLQLKPGQPNleY) induced Ste2p activation reduced cross-linking mediated by Cys substitutions at the cytoplasmic ends of TM5 and TM6 but not by residues in the middle of IL3. Thus, the cytoplasmic ends of TM5 and TM6 undergo conformational change upon ligand binding. An α-factor antagonist (des-Trp, des-His-α-factor) did not influence disulfide-mediated Ste2p cross-linking, suggesting that the interaction of the N-terminus of α-factor with Ste2p is critical for inducing conformational changes at TM5 and TM6. We propose that the changes in conformation revealed for residues at the ends of TM5 and TM6 are affected by the presence of G protein but not G protein activation. This study provides new information about role of specific residues of a GPCR in signal transduction and how peptide ligand binding activates the receptor.