3,779 research outputs found
Recommended from our members
Substrate-Specific Inhibition Constants for Phospholipase A2 Acting on Unique Phospholipid Substrates in Mixed Micelles and Membranes Using Lipidomics.
Assaying lipolytic enzymes is extremely challenging because they act on water-insoluble lipid substrates, which are normally components of micelles, vesicles, and cellular membranes. We extended a new lipidomics-based liquid chromatographic-mass spectrometric assay for phospholipases A2 to perform inhibition analysis using a variety of commercially available synthetic and natural phospholipids as substrates. Potent and selective inhibitors of three recombinant human enzymes, including cytosolic, calcium-independent, and secreted phospholipases A2 were used to establish and validate this assay. This is a novel use of dose-response curves with a mixture of phospholipid substrates, not previously feasible using traditional radioactive assays. The new application of lipidomics to developing assays for lipolytic enzymes revolutionizes in vitro testing for the discovery of potent and selective inhibitors using mixtures of membranelike substrates
Pediatric Rehabilitation Medicine in the USA
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147145/1/pmr253.pd
Striking a Balance: Managing Blogs in Loosely Coupled Systems
As the oldest implementation of Web 2.0 technologies, blogs present an opportunity to understand how community college administrators are addressing two conundrums: conundrum of control and the conundrum of adaptability. These problems arise from the need of leaders to put organizational controls in place even as these controls limit the tool\u27s usefulness and the adaptability of the technology. The purpose of this study using a multiple case study method is (1) to further the understanding of how community college administrators and blog authors strike a balance between organizational control and adaptability when implementing and using blog technologies and (2) to create a model that will help administrators better strike this balance within a loosely coupled system of college units and individuals. The findings have implications for how organizations use other Web 2.0 tools such as Facebook and Twitter
Plasma PGE-2 levels and altered cytokine profiles in adherent peripheral blood mononuclear cells in non-small cell lung cancer (NSCLC)
INTRODUCTION: PGE-2 is constitutively produced by many non-small cell lung cancers (NSCLC) and its immunosuppressive effects have been linked to altered immune responses in lung cancer. We asked whether elevated levels of plasma PGE-2 correlated with monocyte IL10 production in the NSCLC environment. Looking for correlation in NSCLC patient blood we assayed plasma from NSCLC patients for PGE2 and IL10; we further evaluated production of IL10 by adherent mononuclear cells from a subset of these patients looking for an altered cytokine profile. RESULTS: Our initial in vitro experiments show that monocyte IL10 induction correlates with tumor cell PGE-2 production, confirming similar reports in the literature. Data show plasma PGE-2 levels in 38 NSCLC patients are elevated compared to normal controls. Plasma IL10 levels were not significantly elevated; however, adherent monocytes derived from NSCLC patient blood did produce significantly more IL10 in 24 hr primary culture than those from normal controls (p < 0.01). The association of elevated plasma PGE-2 and monocyte derived IL-10 was not significant. CONCLUSIONS: Elevated plasma PGE-2 and monocyte IL10 production are associated with NSCLC. The biological significance to elevated PGE-2 levels in NSCLC are unclear. Further investigation of each as a nonspecific marker for NSCLC tumor is warranted
Fluoroketone inhibition of Ca(2+)-independent phospholipase A2 through binding pocket association defined by hydrogen/deuterium exchange and molecular dynamics.
The mechanism of inhibition of group VIA Ca(2+)-independent phospholipase A(2) (iPLA(2)) by fluoroketone (FK) ligands is examined by a combination of deuterium exchange mass spectrometry (DXMS) and molecular dynamics (MD). Models for iPLA(2) were built by homology with the known structure of patatin and equilibrated by extensive MD simulations. Empty pockets were identified during the simulations and studied for their ability to accommodate FK inhibitors. Ligand docking techniques showed that the potent inhibitor 1,1,1,3-tetrafluoro-7-phenylheptan-2-one (PHFK) forms favorable interactions inside an active-site pocket, where it blocks the entrance of phospholipid substrates. The polar fluoroketone headgroup is stabilized by hydrogen bonds with residues Gly486, Gly487, and Ser519. The nonpolar aliphatic chain and aromatic group are stabilized by hydrophobic contacts with Met544, Val548, Phe549, Leu560, and Ala640. The binding mode is supported by DXMS experiments showing an important decrease of deuteration in the contact regions in the presence of the inhibitor. The discovery of the precise binding mode of FK ligands to the iPLA(2) should greatly improve our ability to design new inhibitors with higher potency and selectivity
On Silicon Group Elements Ejected by Supernovae Type Ia
There is compelling evidence that the peak brightness of a Type Ia supernova
is affected by the electron fraction Ye at the time of the explosion. The
electron fraction is set by the aboriginal composition of the white dwarf and
the reactions that occur during the pre explosive convective burning. To date,
determining the makeup of the white dwarf progenitor has relied on indirect
proxies, such as the average metallicity of the host stellar population. In
this paper, we present analytical calculations supporting the idea that the
electron fraction of the progenitor systematically influences the
nucleosynthesis of silicon group ejecta in Type Ia supernovae. In particular,
we suggest the abundances generated in quasi nuclear statistical equilibrium
are preserved during the subsequent freezeout. This allows one to potential
recovery of Ye at explosion from the abundances recovered from an observed
spectra. We show that measurement of 28Si, 32S, 40Ca, and 54Fe abundances can
be used to construct Ye in the silicon rich regions of the supernovae. If these
four abundances are determined exactly, they are sufficient to recover Ye to 6
percent. This is because these isotopes dominate the composition of
silicon-rich material and iron rich material in quasi nuclear statistical
equilibrium. Analytical analysis shows that the 28Si abundance is insensitive
to Ye, the 32S abundance has a nearly linear trend with Ye, and the 40Ca
abundance has a nearly quadratic trend with Ye. We verify these trends with
post-processing of 1D models and show that these trends are reflected in model
synthetic spectra.Comment: Submitted to the Ap
- …