A Helping Hand during -Testing Times.
Ontology highlight
ABSTRACT:
SUBMITTER: Wiles S
PROVIDER: S-EPMC3928026 | biostudies-other | 2014 Feb
REPOSITORIES: biostudies-other
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Project description:Although native chemical ligation (NCL) and related chemoselective ligation approaches provide an elegant method to stitch together unprotected peptides, the handling and purification of insoluble and aggregation-prone peptides and assembly intermediates create a bottleneck to routinely preparing large proteins by completely synthetic means. In this work, we introduce a new general tool, Fmoc-Ddae-OH, N-Fmoc-1-(4,4-dimethyl-2,6-dioxocyclo-hexylidene)-3-[2-(2-aminoethoxy)ethoxy]-propan-1-ol, a heterobifunctional traceless linker for temporarily attaching highly solubilizing peptide sequences ("helping hands") onto insoluble peptides. This tool is implemented in three simple and nearly quantitative steps: (i) on-resin incorporation of the linker at a Lys residue ε-amine, (ii) Fmoc-SPPS elongation of a desired solubilizing sequence, and (iii) in-solution removal of the solubilizing sequence using mild aqueous hydrazine to cleave the Ddae linker after NCL-based assembly. Successful introduction and removal of a Lys6 helping hand is first demonstrated in two model systems (Ebola virus C20 peptide and the 70-residue ribosomal protein L31). It is then applied to the challenging chemical synthesis of the 97-residue co-chaperonin GroES, which contains a highly insoluble C-terminal segment that is rescued by a helping hand. Importantly, the Ddae linker can be cleaved in one pot following NCL or desulfurization. The purity, structure, and chaperone activity of synthetic l-GroES were validated with respect to a recombinant control. Additionally, the helping hand enabled synthesis of d-GroES, which was inactive in a heterochiral mixture with recombinant GroEL, providing additional insight into chaperone specificity. Ultimately, this simple, robust, and easy-to-use tool is expected to be broadly applicable for the synthesis of challenging peptides and proteins.
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Project description:ImportanceSmoking cessation interventions for hospitalized patients must continue after discharge to improve long-term tobacco abstinence. How health systems can best deliver postdischarge tobacco treatment is uncertain.ObjectiveTo determine if health system-based tobacco cessation treatment after hospital discharge produces more long-term tobacco abstinence than referral to a community-based quitline.Design, setting, and participantsThis randomized clinical trial was conducted September 2018 to November 2020 in 3 hospitals in Massachusetts, Pennsylvania, and Tennessee. Cigarette smokers admitted to a study hospital who received brief in-hospital tobacco treatment and wanted to quit smoking were recruited for participation and randomized for postdischarge treatment to health system-based Transitional Tobacco Care Management (TTCM) or electronic referral to a community-based quitline (QL). Both multicomponent interventions offered smoking cessation counseling and nicotine replacement therapy (NRT) for up to 3 months. Data were analyzed from February 1, 2021, to April 25, 2022.InterventionsTTCM provided 8 weeks of NRT at discharge and 7 automated calls with a hospital-based counselor call-back option. The QL intervention sent referrals from the hospital electronic health record to the state quitline, which offered 5 counseling calls and an NRT sample.Main outcomes and measuresThe main outcome was biochemically verified past 7-day tobacco abstinence at 6 months. Self-reported point-prevalence and continuous tobacco abstinence and tobacco treatment utilization were assessed 1, 3, and 6 months after discharge.ResultsA total of 1409 participants (mean [SD] age, 51.7 [12.6] years; 784 [55.6%] women; mean [SD] 16.4 [10.6] cigarettes/day) were recruited, including 706 randomized to TTCM and 703 randomized to QL. Participants were comparable at baseline, including 216 Black participants (15.3%), 82 Hispanic participants (5.8%), and 1089 White participants (77.3%). At 1 and 3 months after discharge, more TTCM participants than QL participants used cessation counseling (1 month: 245 participants [34.7%] vs 154 participants [21.9%]; 3 months: 248 participants [35.1%] vs 123 participants [17.5%]; P < .001) and pharmacotherapy (1 month: 455 participants [64.4%] vs 324 participants [46.1%]; 3 months: 367 participants [52.0%] vs 264 participants [37.6%]; P < .001). More TTCM than QL participants reported continuous abstinence for 3 months (RR, 1.30; 95% CI, 1.06-1.58) and point-prevalence abstinence at 1 month (RR, 1.22; 95% CI, 1.08-1.35) and 3 months (RR, 1.23; 95% CI, 1.09-1.37) but not at 6 months (RR, 1.14; 95% CI, 0.99-1.29). The primary outcome, biochemically verified point-prevalence abstinence at 6 months, was not statistically significantly different between groups (19.9% vs 16.9%; RR, 1.18; 95% CI, 0.92-1.50).Conclusions and relevanceIn this randomized clinical trial, biochemically verified tobacco abstinence rates were not significantly different between groups at the 6-month follow-up. However, the health system-based model was superior to the community-based quitline model throughout the 3 months of active treatment. A longer duration of postdischarge treatment may sustain the superiority of the health system-based model.Trial registrationClinicalTrials.gov Identifier: NCT03603496.
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