3,697 research outputs found

    Dynamic Pattern Formation in a Vesicle-Generating Microfluidic Device

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    Spatiotemporal pattern formation occurs in a variety of nonequilibrium physical and chemical systems. Here we show that a microfluidic device designed to produce reverse micelles can generate complex, ordered patterns as it is continuously operated far from thermodynamic equilibrium. Flow in a microfluidic system is usually simple—viscous effects dominate and the low Reynolds number leads to laminar flow. Self-assembly of the vesicles into patterns depends on channel geometry and relative fluid pressures, enabling the production of motifs ranging from monodisperse droplets to helices and ribbons

    A Peptide Core Motif for Binding to Heterotrimeric G Protein α Subunits

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    Recently, in vitro selection using mRNA display was used to identify a novel peptide sequence that binds with high affinity to G{alpha}i1. The peptide was minimized to a 9-residue sequence (R6A-1) that retains high affinity and specificity for the GDP-bound state of G{alpha}i1 and acts as a guanine nucleotide dissociation inhibitor (GDI). Here we demonstrate that the R6A-1 peptide interacts with G{alpha} subunits representing all four G protein classes, acting as a core motif for G{alpha} interaction. This contrasts with the consensus G protein regulatory(GPR) sequence, a 28-mer peptide GDI derived from the GoLoco (G{alpha}i/0-Loco interaction)/GPR motif that shares no homology with R6A-1 and binds only to G{alpha}i1-3 in this assay. Binding of R6A-1 is generally specific to the GDP-bound state of the G{alpha} subunits and excludes association with G{beta}{gamma}. R6A-G{alpha}i1 complexes are resistant to trypsin digestion and exhibit distinct stability in the presence of Mg2+, suggesting that the R6A and GPR peptides exert their activities using different mechanisms. Studies using G{alpha}i1/G{alpha}s chimeras identify two regions of G{alpha}i1 (residues 1–35 and 57–88) as determinants for strong R6A-Gi{alpha}1 interaction. Residues flanking the R6A-1 peptide confer unique binding properties, indicating that the core motif could be used as a starting point for the development of peptides exhibiting novel activities and/or specificity for particular G protein subclasses or nucleotide-bound states

    Molecular basis for resistance of acanthamoeba tubulins to all major classes of antitubulin compounds

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    Tubulin is essential to eukaryotic cells and is targeted by several antineoplastics, herbicides, and antimicrobials. We demonstrate that Acanthamoeba spp. are resistant to five antimicrotubule compounds, unlike any other eukaryote studied so far. Resistance correlates with critical amino acid differences within the inhibitor binding sites of the tubulin heterodimers

    Recent Developments in Montana Natural Resources Law

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    Recent Developments In Montana Natural Resources La

    Validation of a 5-Item Tool to Measure Patient Assessment of Clinician Compassion in Hospitals

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    BACKGROUND: We previously validated a 5-item compassion measure to assess patient experience of clinician compassion in the outpatient setting. However, currently, there is no validated and feasible method for health care systems to measure patient experience of clinician compassion in the inpatient setting across multiple hospitals. OBJECTIVE: To test if the 5-item compassion measure can validly and distinctly measure patient assessment of physician and nurse compassion in the inpatient setting. DESIGN: Cross-sectional study between July 1 and July 31, 2020, in a US health care network of 91 community hospitals across 16 states consisting of approximately 15,000 beds. PATIENTS: Adult patients who had an inpatient hospital stay and completed the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey. MEASUREMENTS: We adapted the original 5-item compassion measure to be specific for physicians, as well as for nurses. We disseminated both measures with the HCAHPS survey and used confirmatory factor analysis for validity testing. We tested reliability using Cronbach\u27s alpha, as well as convergent validity with patient assessment of physician and nursing communication and overall hospital rating questions from HCAHPS. RESULTS: We analyzed 4756 patient responses. Confirmatory factor analysis found good fit for two distinct constructs (i.e., physician and nurse compassion). Both measures demonstrated good internal consistency (alpha \u3e 0.90) and good convergent validity but reflected a construct (compassionate care) distinct from what is currently captured in HCAHPS. CONCLUSION: We validated two 5-item tools that can distinctly measure patient experience of physician and nurse compassion for use in the inpatient hospital setting in conjunction with HCAHPS

    Evaluating multiple causes of persistent low microwave backscatter from Amazon forests after the 2005 drought

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    Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon’s vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999–2009, and low morning backscatter persisted for 2006–2009, after which the instrument failed. The persistent low backscatter has been suggested to be indicative of increased forest vulnerability to future drought. To better ascribe the cause of the low post-drought backscatter, we analyzed multiyear, gridded remote sensing data sets of precipitation, land surface temperature, forest cover and forest cover loss, and microwave backscatter over the 2005 drought region in the southwestern Amazon Basin (4°-12°S, 66°-76°W) and in adjacent 8°x10° regions to the north and east. We found moderate to weak correlations with the spatial distribution of persistent low backscatter for variables related to three groups of forest impacts: the 2005 drought itself, loss of forest cover, and warmer and drier dry seasons in the post-drought vs. the pre-drought years. However, these variables explained only about one quarter of the variability in depressed backscatter across the southwestern drought region. Our findings indicate that drought impact is a complex phenomenon and that better understanding can only come from more extensive ground data and/or analysis of frequent, spatially-comprehensive, high-resolution data or imagery before and after droughts

    Effects of Flight Activity and Age on Oxidative Damage in the Honey Bee, Apis Mellifera

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    Frequent and Highly Aerobic Behaviors Likely Contribute to Naturally Occurring Stress, Accelerate Senescence and Limit Lifespan. to Understand How the Physiological and Cellular Mechanisms that Determine the Onset and Duration of Senescence Are Shaped by Behavioral Development and Behavioral Duration, We Exploited the Tractability of the Honeybee (Apis Mellifera) Model System. First, We Determined Whether a Cause-Effect Relationship Exists between Honeybee Flight and Oxidative Stress by Comparing Oxidative Damage Accrued from Intense Flight Bouts to Damage Accrued from D-Galactose Ingestion, Which Induces Oxidative Stress and Limits Lifespan in Other Insects. Second, We Experimentally Manipulated the Duration of Honeybee Flight Across a Range of Ages to Determine the Effects on Reactive Oxygen Species (ROS) Accumulation and Associated Enzymatic Antioxidant Protective Mechanisms. in Bees Fed D-Galactose, Lipid Peroxidation (Assessed by Measuring Malondialdehyde Levels) Was Higher Than in Bees Fed Sucrose and Age-Matched Bees with a High and Low Number of Flight Experiences Collected from a Colony. Bees with High Amounts of Flight Experience Exhibited Elevated 8-Hydroxy-2′-Deoxyguanosine, a Marker of Oxidative DNA Damage, Relative to Bees with Less Flight Experience. Bees with High Amounts of Flight Experience Also Showed Increased Levels of Pro-Oxidants (Superoxide and Hydrogen Peroxide) and Decreased or Unchanged Levels of Antioxidants (Superoxide Dismutase and Catalase). These Data Implicate an Imbalance of Pro- to Antioxidants in Flight-Associated Oxidative Stress and Reveal How Behavior Can Damage a Cell and Consequently Limit Lifespan
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