Is it time to approach spontaneous pneumothorax more conservatively?

A recent study provides modest evidence for observational management over interventional treatment, sparing patients from invasive procedures.Gregory Jones, MD; Jeremias Georgiadis, MD; Valerie Staples, DO (South Baldwin Regional Medical Center, Foley, AL), Rebecca Mullen, MD, MPH (University of Colorado, Family Medicine Residency, Denver). Deputy Editor: Anne Mounsey, MD (Department of Family Medicine, University of North Carolina, Chapel Hill)Includes bibliographical reference

Optimization of tricyclic Nec-3 necroptosis inhibitors for in vitro liver microsomal stability

Necroptosis is a regulated caspase-independent cell death pathway with morphological features resembling passive non-regulated necrosis. Several diverse structure classes of necroptosis inhibitors have been reported to date, including a series of 3,3a,4,5-tetrahydro-2H-benz[g]indazoles (referred to as the Nec-3 series) displaying potent activity in cellular assays. However, evaluation of the tricyclic necroptosis inhibitor’s stability in mouse liver microsomes indicated that they were rapidly degraded. A structure–activity relationship (SAR) study of this compound series revealed that increased liver microsomal stability could be accomplished by modification of the pendent phenyl ring and by introduction of a hydrophilic substituent (i.e., ?-hydroxyl) to the acetamide at the 2-position of the tricyclic ring without significantly compromising necroptosis inhibitory activity. Further increases in microsomal stability could be achieved by utilizing the 5,5-dioxo-3-phenyl-2,3,3a,4-tetrahydro-[1]benzothiopyrano[4,3-c]pyrazoles. However, in this case necroptosis inhibitory activity was not maintained. Overall, these results provide a strategy for generating potent and metabolically stable tricyclic necrostatin analogs (e.g., 33, LDN-193191) potentially suitable for in vivo studies

ARTICLE Pooled Association Tests for Rare Variants in Exon-Resequencing Studies

Deep sequencing will soon generate comprehensive sequence information in large disease samples. Although the power to detect association with an individual rare variant is limited, pooling variants by gene or pathway into a composite test provides an alternative strategy for identifying susceptibility genes. We describe a statistical method for detecting association of multiple rare variants in protein-coding genes with a quantitative or dichotomous trait. The approach is based on the regression of phenotypic values on individuals' genotype scores subject to a variable allele-frequency threshold, incorporating computational predictions of the functional effects of missense variants. Statistical significance is assessed by permutation testing with variable thresholds. We used a rigorous population-genetics simulation framework to evaluate the power of the method, and we applied the method to empirical sequencing data from three disease studies

Glycomics Analysis of Mammalian Heparan Sulfates Modified by the Human Extracellular Sulfatase HSulf2

The Sulfs are a family of endosulfatases that selectively modify the 6O-sulfation state of cell-surface heparan sulfate (HS) molecules. Sulfs serve as modulators of cell-signaling events because the changes they induce alter the cell surface co-receptor functions of HS chains. A variety of studies have been aimed at understanding how Sulfs modify HS structure, and many of these studies utilize Sulf knockout cell lines as the source for the HS used in the experiments. However, genetic manipulation of Sulfs has been shown to alter the expression levels of HS biosynthetic enzymes, and in these cases an assessment of the fine structural changes induced solely by Sulf enzymatic activity is not possible. Therefore, the present work aims to extend the understanding of substrate specificities of HSulf2 using in vitro experiments to compare HSulf2 activities on HS from different organ tissues.To further the understanding of Sulf enzymatic activity, we conducted in vitro experiments where a variety of mammalian HS substrates were modified by recombinant human Sulf2 (HSulf2). Subsequent to treatment with HSulf2, the HS samples were exhaustively depolymerized and analyzed using size-exclusion liquid chromatography-mass spectrometry (SEC-LC/MS). We found that HSulf2 activity was highly dependent on the structural features of the HS substrate. Additionally, we characterized, for the first time, the activity of HSulf2 on the non-reducing end (NRE) of HS chains. The results indicate that the action pattern of HSulf2 at the NRE is different compared to internally within the HS chain.The results of the present study indicate that the activity of Sulfs is dependent on the unique structural features of the HS populations that they edit. The activity of HSulf2 at HS NREs implicates the Sulfs as key regulators of this region of the chains, and concomitantly, the protein-binding events that occur there

Molecular mechanisms of extracellular adenine nucleotides-mediated inhibition of human Cd4+ T lymphocytes activation

We have previously reported that ATPγS, a slowly hydrolyzed analog of ATP, inhibits the activation of human CD4+ T lymphocytes by anti-CD3 and anti-CD28 mAb. In this report we have partially characterized the signaling mechanisms involved in this immunosuppressive effect. ATPγS had no inhibitory effect on CD4+ T-cell activation induced by PMA and anti-CD28, indicating that it acts proximally to the TCR. It had no effect on the calcium rise induced by CD3/CD28 stimulation, but inhibited the phosphorylation of three kinases, ERK2, p38 MAPK and PKB, that play a key role in the activation of T cells. The receptor involved in these actions remains unidentified

Flexible Working and Performance: A Systematic Review of the Evidence for a Business Case

Interest in the outcomes of flexible working arrangements dates from the mid 1970s, when researchers attempted to assess the impact of flexitime on worker performance. This paper reviews the literature on the link between flexible working arrangements and performance related outcomes. Taken together, the evidence fails to demonstrate a business case for the use of flexible working arrangements. This paper attempts to explain the findings by analysing the theoretical and methodological perspectives adopted, as well as the measurements and designs used. In doing so, gaps in this vast and disparate literature are identified and a research agenda is developed