444 research outputs found
Chaperoning steroid hormone signaling via reversible acetylation
Glucocorticoid receptor (GR) and related steroid hormone receptors are ligand-dependent transcription factors whose regulation is critical for both homeostasis and diseases. The structural maturation of the GR has been shown to require the Hsp90 molecular chaperone complex. Evidence indicates that Hsp90-dependent maturation is critical for GR ligand binding capacity and activity. While the role for Hsp90 in GR function is well established, the regulation of this process is not well understood. Here we discuss a recent finding that identifies reversible protein acetylation controlled by the deacetylase HDAC6 as a novel mechanism that regulates Hsp90-dependent GR maturation. We will also speculate on the implications of this finding in steroid hormone signaling, oncogenic transformation and its potential therapeutic utility
The Deacetylase HDAC6 Regulates Aggresome Formation and Cell Viability in Response to Misfolded Protein Stress
AbstractThe efficient clearance of cytotoxic misfolded protein aggregates is critical for cell survival. Misfolded protein aggregates are transported and removed from the cytoplasm by dynein motors via the microtubule network to a novel organelle termed the aggresome where they are processed. However, the means by which dynein motors recognize misfolded protein cargo, and the cellular factors that regulate aggresome formation, remain unknown. We have discovered that HDAC6, a microtubule-associated deacetylase, is a component of the aggresome. We demonstrate that HDAC6 has the capacity to bind both polyubiquitinated misfolded proteins and dynein motors, thereby acting to recruit misfolded protein cargo to dynein motors for transport to aggresomes. Indeed, cells deficient in HDAC6 fail to clear misfolded protein aggregates from the cytoplasm, cannot form aggresomes properly, and are hypersensitive to the accumulation of misfolded proteins. These findings identify HDAC6 as a crucial player in the cellular management of misfolded protein-induced stress
Simultaneous administration of high-dose atorvastatin and clopidogrel does not interfere with platelet inhibition during percutaneous coronary intervention
BACKGROUND: Reloading with high-dose atorvastatin shortly before percutaneous coronary interventions (PCIs) has been proposed as a strategy to reduce periprocedural myonecrosis. There has been a concern that statins that are metabolized by cytochrome P450 3A4 may interfere with clopidogrel metabolism at high doses. The impact of simultaneous administration of high doses of atorvastatin and clopidogrel on the efficacy of platelet inhibition has not been established.
METHODS: Subjects (n=60) were randomized to receive atorvastatin 80 mg together with clopidogrel 600 mg loading dose (n=28) versus clopidogrel 600 mg alone (n=32) at the time of PCI. Platelet aggregation was measured at baseline, 4 hours after clopidogrel loading dose, and 16-24 hours after clopidogrel loading dose by light transmittance aggregometry using adenosine diphosphate as agonist.
RESULTS: Platelet aggregation was similar at baseline in both the atorvastatin and the control groups (adenosine diphosphate 10 µM: 57%±19% vs 61%±21%; P=0.52). There was no significant difference in platelet aggregation between the atorvastatin and the control groups at 4 hours (37%±18% vs 39%±21%; P=0.72) and 16-24 hours post-clopidogrel loading dose (35%±17% vs 37%±18%; P=0.75). No significant difference in incidence of periprocedural myonecrosis was observed between the atorvastatin and control groups (odds ratio: 1.02; 95% confidence interval 0.37-2.8).
CONCLUSION: High-dose atorvastatin given simultaneously with clopidogrel loading dose at the time of PCI does not significantly alter platelet inhibition by clopidogrel. Statin reloading with high doses of atorvastatin at the time of PCI appears to be safe without adverse effects on platelet inhibition by clopidogrel (ClinicalTrials.gov: NCT00979940)
Effectiveness of compression stockings to prevent the post-thrombotic syndrome (The SOX Trial and Bio-SOX biomarker substudy): a randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Post thrombotic syndrome (PTS) is a burdensome and costly complication of deep venous thrombosis (DVT) that develops in 20–40% of patients within 1–2 years after symptomatic DVT. Affected patients have chronic leg pain and swelling and may develop ulcers. Venous valve disruption from the thrombus itself or thrombus-associated mediators of inflammation is considered to be a key initiating event for the development of venous hypertension that often underlies PTS. As existing treatments for PTS are extremely limited, strategies that focus on preventing the development of PTS in patients with DVT are more likely to be effective and cost-effective in reducing its burden. Elastic compression stockings (ECS) could be helpful in preventing PTS; however, data on their effectiveness are scarce and conflicting.</p> <p>Methods/Design</p> <p>The SOX Trial is a randomized, allocation concealed, double-blind multicenter clinical trial. The objective of the study is to evaluate ECS to prevent PTS. A total of 800 patients with proximal DVT will be randomized to one of 2 treatment groups: ECS or placebo (inactive) stockings worn on the DVT-affected leg daily for 2 years. The primary outcome is the incidence of PTS during follow-up. Secondary outcomes are severity of PTS, venous thromboembolism (VTE) recurrence, death from VTE, quality of life and cost-effectiveness. Outcomes will be evaluated during 6 clinic visits and 2 telephone follow ups. At baseline, 1 and 6 months, blood samples will be obtained to evaluate the role of inflammatory mediators and genetic markers of thrombophilia in the development of PTS (Bio-SOX substudy).</p> <p>Discussion</p> <p>The SOX Trial will be the largest study and the first with a placebo control to evaluate the effectiveness of ECS to prevent PTS. It is designed to provide definitive data on the effects of ECS on the occurrence and severity of PTS, as well as DVT recurrence, cost-effectiveness and quality of life. This study will also prospectively evaluate the predictive role of biomarkers that are reflective of putative underlying pathophysiological mechanisms in the development of clinical PTS. As such, our results will impact directly on the care of patients with DVT.</p> <p>Trial Registration</p> <p>NCT00143598 and ISRCTN71334751</p
Economic Impacts of Non-Native Forest Insects in the Continental United States
Reliable estimates of the impacts and costs of biological invasions are critical to developing credible management, trade and regulatory policies. Worldwide, forests and urban trees provide important ecosystem services as well as economic and social benefits, but are threatened by non-native insects. More than 450 non-native forest insects are established in the United States but estimates of broad-scale economic impacts associated with these species are largely unavailable. We developed a novel modeling approach that maximizes the use of available data, accounts for multiple sources of uncertainty, and provides cost estimates for three major feeding guilds of non-native forest insects. For each guild, we calculated the economic damages for five cost categories and we estimated the probability of future introductions of damaging pests. We found that costs are largely borne by homeowners and municipal governments. Wood- and phloem-boring insects are anticipated to cause the largest economic impacts by annually inducing nearly 830 million in lost residential property values. Given observations of new species, there is a 32% chance that another highly destructive borer species will invade the U.S. in the next 10 years. Our damage estimates provide a crucial but previously missing component of cost-benefit analyses to evaluate policies and management options intended to reduce species introductions. The modeling approach we developed is highly flexible and could be similarly employed to estimate damages in other countries or natural resource sectors
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PPM1D Mutations Drive Clonal Hematopoiesis in Response to Cytotoxic Chemotherapy.
Clonal hematopoiesis (CH), in which stem cell clones dominate blood production, becomes increasingly common with age and can presage malignancy development. The conditions that promote ascendancy of particular clones are unclear. We found that mutations in PPM1D (protein phosphatase Mn2+/Mg2+-dependent 1D), a DNA damage response regulator that is frequently mutated in CH, were present in one-fifth of patients with therapy-related acute myeloid leukemia or myelodysplastic syndrome and strongly correlated with cisplatin exposure. Cell lines with hyperactive PPM1D mutations expand to outcompete normal cells after exposure to cytotoxic DNA damaging agents including cisplatin, and this effect was predominantly mediated by increased resistance to apoptosis. Moreover, heterozygous mutant Ppm1d hematopoietic cells outcompeted their wild-type counterparts in vivo after exposure to cisplatin and doxorubicin, but not during recovery from bone marrow transplantation. These findings establish the clinical relevance of PPM1D mutations in CH and the importance of studying mutation-treatment interactions. VIDEO ABSTRACT.This work was supported by the Center Prevention and Research Institute of Texas (CPRIT) (RP160451 and R120501) and the NIH (DK092883, DK116428, S10RR024574, AI036211, P30 CA125123, and P30 CA016672). The Welch Foundation (G-0040), MD Anderson’s MoonShot Program, the Baylor Research Advocates for Student Scientists, and the BCM MSTP program also provided support. K.T. is supported by a Khalifa Physician Scientist Award, the Physician Scientist Program at MD Anderson, and a Leukemia SPORE Career Enhancement Award. G.V. is funded by a Cancer Research UK Senior Cancer Research Fellowship (C22324/A23015), the Kay Kendall Leukaemia Fund, Bloodwise, and core funding from the Sanger Institute (WT098051). We also thank the Samuel Waxman Cancer Research Foundation
A Naturally Occurring Bovine Tauopathy Is Geographically Widespread in the UK
Many human neurodegenerative diseases are associated with hyperphosphorylation and widespread intra-neuronal and glial associated aggregation of the microtubule associated protein tau. In contrast, animal tauopathies are not reported with only senescent animals showing inconspicuous tau labelling of fine processes albeit significant tau aggregation may occur in some experimental animal disease. Since 1986, an idiopathic neurological condition of adult cattle has been recognised in the UK as a sub-set of cattle slaughtered as suspect bovine spongiform encephalopathy cases. This disorder is characterised by brainstem neuronal chromatolysis and degeneration with variable hippocampal sclerosis and spongiform change. Selected cases of idiopathic brainstem neuronal chromatolysis (IBNC) were identified from archive material and characterised using antibodies specific to several tau hyperphosphorylation sites or different isoforms of the tau microtubule binding region. Labelling was also carried out for alpha synuclein, ubiquitin, TDP43, Aβ 1-42, Aβ 1-40. Widespread tau labelling was identified in all IBNC brains examined and with each of seven tau antibodies recognising different hyperphosphorylated sites. Labelling with each antibody was associated with dendrites, neuronal perikarya and glia. Thus IBNC is a sporadic, progressive neurological disease predominantly affecting aged cattle that occurs throughout the UK and is associated with hyperphosphorylation of tau, a rare example of a naturally-occurring tauopathy in a non-primate species. Secondary accumulation of alpha synuclein and ubiquitin was also present. The neuropathology does not precisely correspond with any human tauopathy. The cause of IBNC remains undetermined but environmental factors and exposure to agrochemicals needs to be considered in future aetiological investigations
CosmoDC2: A Synthetic Sky Catalog for Dark Energy Science with LSST
This paper introduces cosmoDC2, a large synthetic galaxy catalog designed to
support precision dark energy science with the Large Synoptic Survey Telescope
(LSST). CosmoDC2 is the starting point for the second data challenge (DC2)
carried out by the LSST Dark Energy Science Collaboration (LSST DESC). The
catalog is based on a trillion-particle, 4.225 Gpc^3 box cosmological N-body
simulation, the `Outer Rim' run. It covers 440 deg^2 of sky area to a redshift
of z=3 and is complete to a magnitude depth of 28 in the r-band. Each galaxy is
characterized by a multitude of properties including stellar mass, morphology,
spectral energy distributions, broadband filter magnitudes, host halo
information and weak lensing shear. The size and complexity of cosmoDC2
requires an efficient catalog generation methodology; our approach is based on
a new hybrid technique that combines data-driven empirical approaches with
semi-analytic galaxy modeling. A wide range of observation-based validation
tests has been implemented to ensure that cosmoDC2 enables the science goals of
the planned LSST DESC DC2 analyses. This paper also represents the official
release of the cosmoDC2 data set, including an efficient reader that
facilitates interaction with the data
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