MutS is responsible for initiating the correction of DNA replication errors. To understand how MutS searches for and identifies rare base-pair mismatches, we characterized the dynamic movement of MutS and the replisome in real time using superresolution microscopy and single-molecule tracking in living cells. We report that MutS dynamics are heterogeneous in cells, with one MutS population exploring the nucleoid rapidly, while another MutS population moves to and transiently dwells at the replisome region, even in the absence of appreciable mismatch formation. Analysis of MutS motion shows that the speed of MutS is correlated with its separation distance from the replisome and that MutS motion slows when it enters the replisome region. We also show that mismatch detection increases MutS speed, supporting the model for MutS sliding clamp formation after mismatch recognition. Using variants of MutS and the replication processivity clamp to impair mismatch repair, we find that MutS dynamically moves to and from the replisome before mismatch binding to scan for errors. Furthermore, a block to DNA synthesis shows that MutS is only capable of binding mismatches near the replisome. It is well-established that MutS engages in an ATPase cycle, which is necessary for signaling downstream events. We show that a variant of MutS with a nucleotide binding defect is no longer capable of dynamic movement to and from the replisome, showing that proper nucleotide binding is critical for MutS to localize to the replisome in vivo. Our results provide mechanistic insight into the trafficking and movement of MutS in live cells as it searches for mismatches.super-resolution microscopy | DNA replication | bacterial cell biology | Bacillus subtilis | single-cell analysis D NA mismatch repair (MMR) is the highly conserved process responsible for correcting DNA replication errors (1). Although replication errors occur infrequently in bacteria (∼1 error per 31 million bp) (2), the consequences of MMR failure on human health are severe (3). MutS is the first protein involved in the MMR pathway, and it is responsible for detecting rare base-pairing errors. In Bacillus subtilis, MutS then recruits MutL, an endonuclease in most bacteria and eukaryotic organisms, to incise the DNA (4, 5). After MutL incision, the error-containing strand is removed, and the DNA is resynthesized to complete error correction (6).The mechanism by which MutS homologs locate a single mismatch among millions of correctly paired nucleotides has been studied extensively by bulk biochemistry, in vitro atomic force microscopy and single-molecule imaging, and visualizing MutS using in vivo cell biology approaches (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). In vitro single-molecule studies largely indicate that MutS operates as a searching clamp diffusing along DNA in a 1D search process (8,10,13). In this model, after mismatch recognition, MutS can dwell at the mismatch before exchanging ADP for ATP, converting into a stable ATP-bound sliding clamp, and subseque...

Background: Graft choice for pediatric anterior cruciate ligament reconstruction (ACLR) is determined by several factors. There is limited information on the use and outcomes of allograft ACLR in pediatric patients. The purpose of this systematic review and meta-analysis was to quantify reported failure rates of allograft versus autograft ACLR in patients ≤19 years of age with ≥2 years of follow-up. We hypothesized that there would be higher rates of failure for allograft compared with autograft ACLR in this population. Methods: PubMed/MEDLINE and Embase databases were systematically searched for literature regarding allograft and autograft ACLR in pediatric/adolescent patients. Articles were included if they described a cohort of patients with average age of ≤19 years, had a minimum of 2 years of follow-up, described graft failure as an outcome, and had a Level of Evidence grade of I to III. Qualitative review and quantitative meta-analysis were performed to compare graft failure rates. A random-effects model was created to compare failure events in patients receiving allograft versus autograft in a pairwise fashion. Data analysis was completed using RevMan 5.3 software (The Cochrane Collaboration). Results: The database search identified 1,604 studies; 203 full-text articles were assessed for eligibility. Fourteen studies met the inclusion criteria for qualitative review; 5 studies were included for quantitative meta-analysis. Bone-patellar tendon-bone (BTB) represented 58.2% (n = 1,012) of the autografts, and hamstring grafts represented 41.8% (n = 727). Hybrid allografts (autograft + supplemental allograft) represented 12.8% (n = 18) of all allograft ACLRs (n = 141). The unweighted, pooled failure rate for each graft type was 8.5% for BTB, 16.6% for hamstring, and 25.5% for allograft. Allografts were significantly more likely than autografts to result in graft failure (odds ratio, 3.87; 95% confidence interval, 2.24 to 6.69). Conclusions: Allograft ACLR in pediatric and adolescent patients should be used judiciously, as existing studies revealed a significantly higher failure rate for allograft compared with autograft ACLR in this patient population. Additional studies are needed to improve the understanding of variables associated with the high ACLR failure rate among pediatric and adolescent patients. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

BackgroundAmong HIV+ patients, alcohol use is a highly prevalent risk factor for both HIV transmission and poor adherence to HIV treatment. The large-scale implementation of effective interventions for treating alcohol problems remains a challenge in low-income countries with generalized HIV epidemics. It is essential to consider an intervention’s cost-effectiveness in dollars-per-health-outcome, and the long-term economic impact —or “return on investment” in monetary terms.MethodsWe conducted a cost-benefit analysis, measuring economic return on investment, of a task-shifted cognitive-behavioral therapy (CBT) intervention delivered by paraprofessionals to reduce alcohol use in a modeled cohort of 13,440 outpatients in Kenya. In our base-case, we estimated the costs and economic benefits from a societal perspective across a six-year time horizon, with a 3% annual discount rate. Costs included all costs associated with training and administering task-shifted CBT therapy. Benefits included the economic impact of lowered HIV incidence as well as the improvements in household and labor-force productivity. We conducted univariate and multivariate probabilistic sensitivity analyses to test the robustness of our results.ResultsUnder the base case, total costs for CBT rollout was $554,000, the value of benefits were $628,000, and the benefit-to-cost ratio was 1.13. Sensitivity analyses showed that under most assumptions, the benefit-to-cost ratio remained above unity indicating that the intervention was cost-saving (i.e., had positive return on investment). The duration of the treatment effect most effected the results in sensitivity analyses.ConclusionsCBT can be effectively and economically task-shifted to paraprofessionals in Kenya. The intervention can generate not only reductions in morbidity and mortality, but also economic savings for the health system in the medium and long term. The findings have implications for other countries with generalized HIV epidemics, high prevalence of alcohol consumption, and shortages of mental health professionals.Trial registrationThis paper uses data derived from “Cognitive Behavioral Treatment to Reduce Alcohol Use Among HIV-Infected Kenyans (KHBS)” with ClinicalTrials.gov registration NCT00792519 on 11/17/2008; and preliminary data from “A Stage 2 Cognitive-behavioral Trial: Reduce Alcohol First in Kenya Intervention” (NCT01503255, registered on 12/16/2011).

Background: Although sleep has been identified as an important modifiable risk factor for injury, the effect of decreased sleep on sports injuries in adolescents is poorly studied. The objective of this study was to quantitatively and qualitatively review published literature to examine if a lack of sleep is associated with sports injuries in adolescents and to delineate the effects of chronic versus acute lack of sleep. Methods: PubMed (includes MEDLINE) and EMBASE databases were systematically searched using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were included if they reported statistics regarding the relationship between sleep and sports injury in adolescents aged 19 years or younger published between January 1, 1997 and December 21, 2017. From these included studies, the following information was extracted: bibliographic and demographic information, reported outcomes related to injury and sleep, and definitions of injury and decreased sleep. A random effects model was then created to quantify the odds of injury with decreased sleep in adolescents. Results: Of 907 identified articles, 7 met inclusion criteria. Five studies reported that adolescents who chronically slept poorly were at a significantly increased likelihood of experiencing a sports or musculoskeletal injury. Two studies reported on acute sleep behaviors. One reported a significant positive association between acutely poor sleep and injury, whereas the other study reported no significant association. In our random effects model, adolescents who chronically slept poorly were more likely to be injured than those who slept well (OR, 1.58; 95% CI, 1.05-2.37; P=0.03). Conclusions: Chronic lack of sleep in adolescents is associated with greater risk of sports and musculoskeletal injuries. Current evidence cannot yet definitively determine the effect of acute lack of sleep on injury rates. Level of Evidence: Level IV—systematic review of level II studies and one level IV study.