Biochemical and structural insights into enzymatic depolymerization of polylactic acid and other polyesters by microbial carboxylesterases

Polylactic acid (PLA) is a biodegradable polyester derived from renewable resources, which is a leading candidate for the replacement of traditional petroleum-based polymers. Since the global production of PLA is quickly growing, there is an urgent need for the development of efficient recycling technologies, which will produce lactic acid instead of CO₂ as the final product. After screening 90 purified microbial α/β-hydrolases, we identified hydrolytic activity against emulsified PLA in two uncharacterized proteins, ABO2449 from <i>Alcanivorax borkumensis</i> and RPA1511 from <i>Rhodopseudomonas palustris</i>. Both enzymes were also active against emulsified polycaprolactone and other polyesters as well as against soluble α-naphthyl and <i>p</i>-nitrophenyl monoesters. In addition, both ABO2449 and RPA1511 catalyzed complete or extensive hydrolysis of solid PLA with the production of lactic acid monomers, dimers, and larger oligomers as products. The crystal structure of RPA1511 was determined at 2.2 Å resolution and revealed a classical α/β-hydrolase fold with a wide-open active site containing a molecule of polyethylene glycol bound near the catalytic triad Ser114-His270-Asp242. Site-directed mutagenesis of both proteins demonstrated that the catalytic triad residues are important for the hydrolysis of both monoester and polyester substrates. We also identified several residues in RPA1511 (Gln172, Leu212, Met215, Trp218, and Leu220) and ABO2449 (Phe38 and Leu152), which were not essential for activity against soluble monoesters but were found to be critical for the hydrolysis of PLA. Our results indicate that microbial carboxyl esterases can efficiently hydrolyze various polyesters making them attractive biocatalysts for plastics depolymerization and recycling

The Video intervention to Inspire Treatment Adherence for Life (VITAL Start): protocol for a multisite randomized controlled trial of a brief video-based intervention to improve antiretroviral adherence and retention among HIV-infected pregnant women in Malawi

Abstract Background Improving maternal antiretroviral therapy (ART) retention and adherence is a critical challenge facing prevention of mother-to-child transmission (PMTCT) of HIV programs. There is an urgent need for evidence-based, cost-effective, and scalable interventions to improve maternal adherence and retention that can be feasibly implemented in overburdened health systems. Brief video-based interventions are a promising but underutilized approach to this crisis. We describe a trial protocol to evaluate the effectiveness and implementation of a standardized educational video-based intervention targeting HIV-infected pregnant women that seeks to optimize their ART retention and adherence by providing a VITAL Start (Video intervention to Inspire Treatment Adherence for Life) before committing to lifelong ART. Methods This study is a multisite parallel group, randomized controlled trial assessing the effectiveness of a brief facility-based video intervention to optimize retention and adherence to ART among pregnant women living with HIV in Malawi. A total of 892 pregnant women living with HIV and not yet on ART will be randomized to standard-of-care pre-ART counseling or VITAL Start. The primary outcome is a composite of retention and adherence (viral load < 1000 copies/ml) 12 months after starting ART. Secondary outcomes include assessments of behavioral adherence (self-reported adherence, pharmacy refill, and tenofovir diphosphate concentration), psychosocial impact, and resource utilization. We will also examine the implementation of VITAL Start via surveys and qualitative interviews with patients, partners, and health care workers and conduct cost-effectiveness analyses. Discussion This is a robust evaluation of an innovative facility-based video intervention for pregnant women living with HIV, with the potential to improve maternal and infant outcomes. Trial registration ClinicalTrials.gov, NCT03654898. Registered on 31 August 2018

Screening and Characterization of Novel Polyesterases from Environmental Metagenomes with High Hydrolytic Activity against Synthetic Polyesters

International audienc

Sorghum Genome Sequencing by Methylation Filtration

Sorghum bicolor is a close relative of maize and is a staple crop in Africa and much of the developing world because of its superior tolerance of arid growth conditions. We have generated sequence from the hypomethylated portion of the sorghum genome by applying methylation filtration (MF) technology. The evidence suggests that 96% of the genes have been sequence tagged, with an average coverage of 65% across their length. Remarkably, this level of gene discovery was accomplished after generating a raw coverage of less than 300 megabases of the 735-megabase genome. MF preferentially captures exons and introns, promoters, microRNAs, and simple sequence repeats, and minimizes interspersed repeats, thus providing a robust view of the functional parts of the genome. The sorghum MF sequence set is beneficial to research on sorghum and is also a powerful resource for comparative genomics among the grasses and across the entire plant kingdom. Thousands of hypothetical gene predictions in rice and Arabidopsis are supported by the sorghum dataset, and genomic similarities highlight evolutionarily conserved regions that will lead to a better understanding of rice and Arabidopsis

The Video intervention to Inspire Treatment Adherence for Life (VITAL Start): protocol for a multisite randomized controlled trial of a brief video-based intervention to improve antiretroviral adherence and retention among HIV-infected pregnant women in Malawi

Background Improving maternal antiretroviral therapy (ART) retention and adherence is a critical challenge facing prevention of mother-to-child transmission (PMTCT) of HIV programs. There is an urgent need for evidence-based, cost-effective, and scalable interventions to improve maternal adherence and retention that can be feasibly implemented in overburdened health systems. Brief video-based interventions are a promising but underutilized approach to this crisis. We describe a trial protocol to evaluate the effectiveness and implementation of a standardized educational video-based intervention targeting HIV-infected pregnant women that seeks to optimize their ART retention and adherence by providing a VITAL Start (Video intervention to Inspire Treatment Adherence for Life) before committing to lifelong ART. Methods This study is a multisite parallel group, randomized controlled trial assessing the effectiveness of a brief facility-based video intervention to optimize retention and adherence to ART among pregnant women living with HIV in Malawi. A total of 892 pregnant women living with HIV and not yet on ART will be randomized to standard-of-care pre-ART counseling or VITAL Start. The primary outcome is a composite of retention and adherence (viral load < 1000 copies/ml) 12 months after starting ART. Secondary outcomes include assessments of behavioral adherence (self-reported adherence, pharmacy refill, and tenofovir diphosphate concentration), psychosocial impact, and resource utilization. We will also examine the implementation of VITAL Start via surveys and qualitative interviews with patients, partners, and health care workers and conduct cost-effectiveness analyses. Discussion This is a robust evaluation of an innovative facility-based video intervention for pregnant women living with HIV, with the potential to improve maternal and infant outcomes. Trial registration ClinicalTrials.gov, NCT03654898. Registered on 31 August 2018

Lack of effective communication between communities and hospitals in Uganda: a qualitative exploration of missing links

<p>Abstract</p> <p>Background</p> <p>Community members are stakeholders in hospitals and have a right to participate in the improvement of quality of services rendered to them. Their views are important because they reflect the perspectives of the general public. This study explored how communities that live around hospitals pass on their views to and receive feedback from the hospitals' management and administration.</p> <p>Methods</p> <p>The study was conducted in eight hospitals and the communities around them. Four of the hospitals were from three districts from eastern Uganda and another four from two districts from western Uganda. Eight key informant interviews (KIIs) were conducted with medical superintendents of the hospitals. A member from each of three hospital management boards was also interviewed. Eight focus group discussions (FGDs) were conducted with health workers from the hospitals. Another eight FGDs (four with men and four with women) were conducted with communities within a five km radius around the hospitals. Four of the FGDs (two with men and two with women) were done in western Uganda and the other four in eastern Uganda. The focus of the KIIs and FGDs was exploring how hospitals communicated with the communities around them. Analysis was by manifest content analysis.</p> <p>Results</p> <p>Whereas health unit management committees were supposed to have community representatives, the representatives never received views from the community nor gave them any feed back from the hospitals. Messages through the mass media like radio were seen to be non specific for action. Views sent through suggestion boxes were seen as individual needs rather than community concerns. Some community members perceived they would be harassed if they complained and had reached a state of resignation preferring instead to endure the problems quietly.</p> <p>Conclusion</p> <p>There is still lack of effective communication between the communities and the hospitals that serve them in Uganda. This deprives the communities of the right to participate in the improvement of the services they receive, to assume their position as stakeholders. Various avenues could be instituted including using associations in communities, rapid appraisal methods and community meetings.</p

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements