1,305 research outputs found
Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella
The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major
pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the
biologically friendly control method known as pheromone-based mating disruption. Mating
disruption likely exerts selection on the sexual communication system of codling moth, as
male and female moths will persist in their attempt to meet and mate. Surprisingly little is
known on the intraspecific variation of sexual communication in this species. We started an
investigation to determine the level of individual variation in the female sex pheromone
composition of this moth and whether variation among different populations might be
correlated with use of mating disruption against those populations. By extracting pheromone
glands of individual females from a laboratory population in Canada and from populations
from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed
a significant difference in sex pheromone composition for two of the minor components.
Overall, the intraspecific variation observed shows the potential for a shift in female sexual
signal when selection pressure is high, as is the case with continuous use of mating disruption.We would like to thank Mark Gardiner (Agriculture and Agri-Food Canada, Summerland, BC, Canada) for sending pupae to the University of Amsterdam, which was quite a challenge. We also would like to thank John Kusters (PG Kusters land en tuinbouwbenodigdheden B.V., Dreumel, The Netherlands) for providing us access to his apple orchards to collect larvae. This study was partly funded by IBED, University of Amsterdam
What is a clinical pathway? Refinement of an operational definition to identify clinical pathway studies for a Cochrane systematic review
Clinical pathways (CPWs) are a common component in the quest to improve the quality of health. CPWs are used to reduce variation, improve quality of care, and maximize the outcomes for specific groups of patients. An ongoing challenge is the operationalization of a definition of CPW in healthcare. This may be attributable to both the differences in definition and a lack of conceptualization in the field of clinical pathways. This correspondence article describes a process of refinement of an operational definition for CPW research and proposes an operational definition for the future syntheses of CPWs literature. Following the approach proposed by Kinsman et al. (BMC Medicine 8(1):31, 2010) and Wieland et al. (Alternative Therapies in Health and Medicine 17(2):50, 2011), we used a four-stage process to generate a five criteria checklist for the definition of CPWs. We refined the operational definition, through consensus, merging two of the checklist’s criteria, leading to a more inclusive criterion for accommodating CPW studies conducted in various healthcare settings. The following four criteria for CPW operational definition, derived from the refinement process described above, are (1) the intervention was a structured multidisciplinary plan of care; (2) the intervention was used to translate guidelines or evidence into local structures; (3) the intervention detailed the steps in a course of treatment or care in a plan, pathway, algorithm, guideline, protocol or other ‘inventory of actions’ (i.e. the intervention had time-frames or criteria-based progression); and (4) the intervention aimed to standardize care for a specific population. An intervention meeting all four criteria was considered to be a CPW. The development of operational definitions for complex interventions is a useful approach to appraise and synthesize evidence for policy development and quality improvement
Predicting local recurrence following breast conserving therapy for early stage breast cancer : the significance of a narrow (less than or equal to 2mm) surgical resection margin
Introduction
Controversy continues over the extent of surgical resection margin required to minimize the risk of local recurrence (LR) in breast conserving therapy (BCT) for stage I and II breast cancer. This thesis explores whether or not a narrow (less than or equal to 2 mm) but negative resection margin in BCT for stage I and II breast cancer affects LR. Methodology
To address the question, all patients registered at the Saskatoon Cancer Center between January 1, 1991 and December 31, 2000 with a diagnosis of stage I or II invasive duct carcinoma of the breast treated with BCT were examined. All charts and pathology reports were reviewed with a review of the pathology for all cases where the resection margin was unclear in the original report. Other factors know or thought to effect LR (age, radiation boost, grade, extensive duct carcinoma in situ, ER/PR receptor status, tumor size, and systemic adjuvant therapy) were considered in the statistical analysis. Results
Amongst the 200 narrow margin cases 19 LR were detected (19/200=9.5%) while 52 LR were detected in the 491 wide margin cases (52/491=10.6%). This difference was not statistically significant.
Conclusions
A narrow (less than or equal to 2 mm) surgical resection margin does not result in an increase in local recurrence compared to a surgical resection margin greater than 2 mm in breast conserving therapy for early stage duct carcinoma and does not warrant re-excision
What is a clinical pathway? Refinement of an operational definition to identify clinical pathway studies for a Cochrane systematic review
Clinical pathways (CPWs) are a common component in the quest to improve the quality of health. CPWs are used to reduce variation, improve quality of care, and maximize the outcomes for specific groups of patients. An ongoing challenge is the operationalization of a definition of CPW in healthcare. This may be attributable to both the differences in definition and a lack of conceptualization in the field of clinical pathways. This correspondence article describes a process of refinement of an operational definition for CPW research and proposes an operational definition for the future syntheses of CPWs literature. Following the approach proposed by Kinsman et al. (BMC Medicine 8(1):31, 2010) and Wieland et al. (Alternative Therapies in Health and Medicine 17(2):50, 2011), we used a four-stage process to generate a five criteria checklist for the definition of CPWs. We refined the operational definition, through consensus, merging two of the checklist's criteria, leading to a more inclusive criterion for accommodating CPW studies conducted in various healthcare settings. The following four criteria for CPW operational definition, derived from the refinement process described above, are (1) the intervention was a structured multidisciplinary plan of care; (2) the intervention was used to translate guidelines or evidence into local structures; (3) the intervention detailed the steps in a course of treatment or care in a plan, pathway, algorithm, guideline, protocol or other 'inventory of actions' (i.e. the intervention had time-frames or criteria-based progression); and (4) the intervention aimed to standardize care for a specific population. An intervention meeting all four criteria was considered to be a CPW. The development of operational definitions for complex interventions is a useful approach to appraise and synthesize evidence for policy development and quality improvement
Steady shear flow thermodynamics based on a canonical distribution approach
A non-equilibrium steady state thermodynamics to describe shear flows is
developed using a canonical distribution approach. We construct a canonical
distribution for shear flow based on the energy in the moving frame using the
Lagrangian formalism of the classical mechanics. From this distribution we
derive the Evans-Hanley shear flow thermodynamics, which is characterized by
the first law of thermodynamics relating infinitesimal
changes in energy , entropy and shear rate with kinetic
temperature . Our central result is that the coefficient is given by
Helfand's moment for viscosity. This approach leads to thermodynamic stability
conditions for shear flow, one of which is equivalent to the positivity of the
correlation function of . We emphasize the role of the external work
required to sustain the steady shear flow in this approach, and show
theoretically that the ensemble average of its power must be
non-negative. A non-equilibrium entropy, increasing in time, is introduced, so
that the amount of heat based on this entropy is equal to the average of
. Numerical results from non-equilibrium molecular dynamics simulation
of two-dimensional many-particle systems with soft-core interactions are
presented which support our interpretation.Comment: 23 pages, 7 figure
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A novel PEG–haloperidol conjugate with a non-degradable linker shows the feasibility of using polymer–drug conjugates in a non-prodrug fashion
A PEG–haloperidol conjugate containing a non-biodegradable linker was synthesised. Incubation with rat plasma demonstrated excellent linker stability, and competition radioligand binding assays demonstrated retained binding to the D2-receptor. In silico studies predicted that the conjugate will not cross the blood–brain barrier (BBB), thus potentially restricting haloperidol action to one side of the BBB
Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions
The weak nucleon axial-vector form factor for quasi-elastic interactions is
determined using neutrino interaction data from the K2K Scintillating Fiber
detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of
which half are charged-current quasi-elastic interactions nu-mu n to mu- p
occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for
oxygen and assume the form factor is approximately a dipole with one parameter,
the axial vector mass M_A, and fit to the shape of the distribution of the
square of the momentum transfer from the nucleon to the nucleus. Our best fit
result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated
vector form factors from recent electron scattering experiments and a
discussion of the effects of the nucleon momentum on the shape of the fitted
distributions.Comment: 14 pages, 10 figures, 6 table
Measurement of Branching Fraction and Dalitz Distribution for B0->D(*)+/- K0 pi-/+ Decays
We present measurements of the branching fractions for the three-body decays
B0 -> D(*)-/+ K0 pi^+/-B0 -> D(*)-/+ K*+/- using
a sample of approximately 88 million BBbar pairs collected by the BABAR
detector at the PEP-II asymmetric energy storage ring.
We measure:
B(B0->D-/+ K0 pi+/-)=(4.9 +/- 0.7(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K0 pi+/-)=(3.0 +/- 0.7(stat) +/- 0.3 (syst)) 10^{-4}
B(B0->D-/+ K*+/-)=(4.6 +/- 0.6(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K*+/-)=(3.2 +/- 0.6(stat) +/- 0.3 (syst)) 10^{-4}
From these measurements we determine the fractions of resonant events to be :
f(B0-> D-/+ K*+/-) = 0.63 +/- 0.08(stat) +/- 0.04(syst) f(B0-> D*-/+ K*+/-) =
0.72 +/- 0.14(stat) +/- 0.05(syst)Comment: 7 pages, 3 figures submitted to Phys. Rev. Let
Mammalian end binding proteins control persistent microtubule growth
© 2009 Komarova et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License 3.0. The definitive version was published in Journal of Cell Biology 184 (2009): 691-706, doi:10.1083/jcb.200807179.End binding proteins (EBs) are highly conserved core components of microtubule plus-end tracking protein networks. Here we investigated the roles of the three mammalian EBs in controlling microtubule dynamics and analyzed the domains involved. Protein depletion and rescue experiments showed that EB1 and EB3, but not EB2, promote persistent microtubule growth by suppressing catastrophes. Furthermore, we demonstrated in vitro and in cells that the EB plus-end tracking behavior depends on the calponin homology domain but does not require dimer formation. In contrast, dimerization is necessary for the EB anti-catastrophe activity in cells; this explains why the EB1 dimerization domain, which disrupts native EB dimers, exhibits a dominant-negative effect. When microtubule dynamics is reconstituted with purified tubulin, EBs promote rather than inhibit catastrophes, suggesting that in cells EBs prevent catastrophes by counteracting other microtubule regulators. This probably occurs through their action on microtubule ends, because catastrophe suppression does not require the EB domains needed for binding to known EB partners.This work was supported by the Netherlands Organization for Scientifi
c Research grants to A.A., by Funda ç ã o para a Ci ê ncia e a Tecnologia
fellowship to S.M. Gouveia, by a FEBS fellowship to R.M. Buey, by the National
Institutes of Health grant GM25062 to G.G. Borisy and by the Swiss
National Science Foundation through grant 3100A0-109423 and by the
National Center of Competence in Research Structural Biology program to
M.O. Steinmetz
Current State of Open Source Force Fields in Protein-Ligand Binding Affinity Predictions.
In drug discovery, the in silico prediction of binding affinity is one of the major means to prioritize compounds for synthesis. Alchemical relative binding free energy (RBFE) calculations based on molecular dynamics (MD) simulations are nowadays a popular approach for the accurate affinity ranking of compounds. MD simulations rely on empirical force field parameters, which strongly influence the accuracy of the predicted affinities. Here, we evaluate the ability of six different small-molecule force fields to predict experimental protein-ligand binding affinities in RBFE calculations on a set of 598 ligands and 22 protein targets. The public force fields OpenFF Parsley and Sage, GAFF, and CGenFF show comparable accuracy, while OPLS3e is significantly more accurate. However, a consensus approach using Sage, GAFF, and CGenFF leads to accuracy comparable to OPLS3e. While Parsley and Sage are performing comparably based on aggregated statistics across the whole dataset, there are differences in terms of outliers. Analysis of the force field reveals that improved parameters lead to significant improvement in the accuracy of affinity predictions on subsets of the dataset involving those parameters. Lower accuracy can not only be attributed to the force field parameters but is also dependent on input preparation and sampling convergence of the calculations. Especially large perturbations and nonconverged simulations lead to less accurate predictions. The input structures, Gromacs force field files, as well as the analysis Python notebooks are available on GitHub
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