A generalised individual-based algorithm for modelling the evolution of quantitative herbicide resistance in arable weed populations.

BACKGROUND: Simulation models are useful tools for predicting and comparing the risk of herbicide resistance in weed populations under different management strategies. Most existing models assume a monogenic mechanism governing herbicide resistance evolution. However, growing evidence suggests that herbicide resistance is often inherited in a polygenic or quantitative fashion. Therefore, we constructed a generalised modelling framework to simulate the evolution of quantitative herbicide resistance in summer annual weeds. RESULTS: Real-field management parameters based on Amaranthus tuberculatus (Moq.) Sauer (syn. rudis) control with glyphosate and mesotrione in Midwestern US maize-soybean agroecosystems demonstrated that the model can represent evolved herbicide resistance in realistic timescales. Sensitivity analyses showed that genetic and management parameters were impactful on the rate of quantitative herbicide resistance evolution, whilst biological parameters such as emergence and seed bank mortality were less important. CONCLUSION: The simulation model provides a robust and widely applicable framework for predicting the evolution of quantitative herbicide resistance in summer annual weed populations. The sensitivity analyses identified weed characteristics that would favour herbicide resistance evolution, including high annual fecundity, large resistance phenotypic variance and pre-existing herbicide resistance. Implications for herbicide resistance management and potential use of the model are discussed. © 2016 Society of Chemical Industry.

Community-Driven Research Agenda to Reduce Health Disparities.

This paper describes how a new regional campus of an academic health center engaged in a community-based participatory research (CBPR) process to set a community-driven research agenda to address health disparities. The campus is situated among growing Marshallese and Hispanic populations that face significant health disparities. In 2013, with support from the Translational Research Institute, the University of Arkansas for Medical Sciences Northwest began building its research capacity in the region with the goal of developing a community-driven research agenda for the campus. While many researchers engage in some form of community-engaged research, using a CBPR process to set the research agenda for an entire campus is unique. Utilizing multiple levels of engagement, three research areas were chosen by the community: (1) chronic disease management and prevention; (2) obesity and physical activity; and (3) access to culturally appropriate healthcare. In only 18 months, the CBPR collaboration had dramatic results. Ten grants and five scholarly articles were collaboratively written and 25 community publications and presentations were disseminated. Nine research projects and health programs were initiated. In addition, many interprofessional educational and service learning objectives were aligned with the community-driven agenda resulting in practical action to address the needs identified.

Lessons from Prenatal Care Provider-Based Recruitment into the National Children's Study.

In response to recruitment difficulties experienced by the National Children's Study, alternatives to the door-to-door recruitment method were pilot tested. This report describes outcomes, successes, and challenges of recruiting women through prenatal care providers in Benton County, Arkansas, USA. Eligible women residing in 14 randomly selected geographic segments were recruited. Data were collected during pregnancy, at birth, and at 3, 6, 9, 12, 18, and 24 months postpartum. Participants were compared to non-enrolled eligible women through birth records. Of 6402 attempts to screen for address eligibility, 468 patients were potentially eligible. Of 221 eligible women approached to participate, 151 (68%) enrolled in the 21-year study. Enrolled women were similar to non-enrolled women in age, marital status, number of prenatal care visits, and gestational age and birth weight of the newborn. Women enrolled from public clinics were more likely to be Hispanic, lower educated, younger and unmarried than those enrolled from private clinics. Sampling geographic areas from historical birth records failed to produce expected equivalent number of births across segments. Enrollment of pregnant women from prenatal care providers was successful.

Family Model of Diabetes Education With a Pacific Islander Community.

PURPOSE: The purpose of the study was to use a community-based participatory research approach to pilot-test a family model of diabetes education conducted in participants' homes with extended family members. METHODS: The pilot test included 6 families (27 participants) who took part in a family model of diabetes self-management education (DSME) using an intervention-driven pre- and posttest design with the aim of improving glycemic control as measured by A1C. Questionnaires and additional biometric data were also collected. Researchers systematically documented elements of feasibility using participant observations and research field reports. RESULTS: More than three-fourths (78%) of participants were retained in the study. Posttest results indicated a 5% reduction in A1C across all participants and a 7% reduction among those with type 2 diabetes. Feasibility of an in-home model with extended family members was documented, along with observations and recommendations for further DSME adaptations related to blood glucose monitoring, physical activity, nutrition, and medication adherence. CONCLUSIONS: The information gained from this pilot helps to bridge the gap between knowledge of an evidence-based intervention and its actual implementation within a unique minority population with especially high rates of type 2 diabetes and significant health disparities. Building on the emerging literature of family models of DSME, this study shows that the family model delivered in the home had high acceptance and that the intervention was more accessible for this hard-to-reach population.

Deconstruction of medulloblastoma cellular heterogeneity reveals differences between the most highly invasive and self-renewing phenotypes.

Medulloblastoma (MB) is the most common malignant primary pediatric brain tumor. Major research efforts have focused on characterizing and targeting putative brain tumor stem or propagating cell populations from the tumor mass. However, less is known about the relationship between these cells and highly invasive MB cells that evade current therapies. Here, we dissected MB cellular heterogeneity and directly compared invasion and self-renewal. Analysis of higher versus lower self-renewing tumor spheres and stationary versus migrating adherent MB cells revealed differential expression of the cell surface markers CD271 [p75 neurotrophin receptor (p75NTR)] and CD133. Cell sorting demonstrated that CD271 selects for subpopulations with a higher capacity for self-renewal, whereas CD133 selects for cells exhibiting increased invasion in vitro. CD271 expression is higher in human fetal cerebellum and primary samples of the Shh MB molecular variant and lower in the more aggressive, invasive group 3 and 4 subgroups. Global gene expression analysis of higher versus lower self-renewing MB tumor spheres revealed down-regulation of a cell movement transcription program in the higher self-renewing state and a novel potential role for axon guidance signaling in MB-propagating cells. We have identified a cell surface signature based on CD133/CD271 expression that selects for MB cells with a higher self-renewal potential or invasive capacity in vitro. Our study underscores a previously unappreciated role for CD271 in selecting for MB cell phenotypes and suggests that successful treatment of pediatric brain tumors requires concomitant targeting of a spectrum of transitioning self-renewing and highly infiltrative cell subpopulations.

Spatial variability of atrazine and metolachlor dissipation on dryland no-tillage crop fields in Colorado.

An area of interest in precision farming is variable-rate application of herbicides to optimize herbicide use efficiency and minimize negative off-site and non-target effects. Site-specific weed management based on field scale management zones derived from soil characteristics known to affect soil-applied herbicide efficacy could alleviate challenges posed by post-emergence precision weed management. Two commonly used soil-applied herbicides in dryland corn (Zea mays L.) production are atrazine and metolachlor. Accelerated dissipation of atrazine has been discovered recently in irrigated corn fields in eastern Colorado. The objectives of this study were (i) to compare the rates of dissipation of atrazine and metolachlor across different soil zones from three dryland no-tillage fields under laboratory incubation conditions and (ii) to determine if rapid dissipation of atrazine and/or metolachlor occurred in dryland soils. Herbicide dissipation was evaluated at time points between 0 and 35 d after soil treatment using a toluene extraction procedure with GC/MS analysis. Differential rates of atrazine and metolachlor dissipation occurred between two soil zones on two of three fields evaluated. Accelerated atrazine dissipation occurred in soil from all fields of this study, with half-lives ranging from 1.8 to 3.2 d in the laboratory. The rapid atrazine dissipation rates were likely attributed to the history of atrazine use on all fields investigated in this study. Metolachlor dissipation was not considered accelerated and exhibited half-lives ranging from 9.0 to 10.7 d in the laboratory.