1,851 research outputs found
Embracing differences to improve success: American Orthopaedic Association presidential address, Boston, Massachusetts, June 23, 2017: AOA critical issues
Detecting the Stimulated Decay of Axions at Radio Frequencies
Assuming axion-like particles account for the entirety of the dark matter in
the Universe, we study the possibility of detecting their decay into photons at
radio frequencies. We discuss different astrophysical targets, such as dwarf
spheroidal galaxies, the Galactic Center and halo, and galaxy clusters. The
presence of an ambient radiation field leads to a stimulated enhancement of the
decay rate; depending on the environment and the mass of the axion, the effect
of stimulated emission may amplify the photon flux by serval orders of
magnitude. For axion-photon couplings allowed by astrophysical and laboratory
constraints(and possibly favored by stellar cooling), we find the signal to be
within the reach of next-generation radio telescopes such as the Square
Kilometer Array.Comment: Minor changes, references added, matches published versio
Treatment of intra-articular hip malignancy with extra-articular resection, preservation of the acetabular columns, and total hip arthroplasty
Control Infrastructure for a Pulsed Ion Accelerator
We report on updates to the accelerator controls for the Neutralized Drift
Compression Experiment II, a pulsed induction-type accelerator for heavy ions.
The control infrastructure is built around a LabVIEW interface combined with an
Apache Cassandra backend for data archiving. Recent upgrades added the storing
and retrieving of device settings into the database, as well as ZeroMQ as a
message broker that replaces LabVIEW's shared variables. Converting to ZeroMQ
also allows easy access via other programming languages, such as Python
Distinct metabolic programs induced by TGF-β1 and BMP2 in human articular chondrocytes with osteoarthritis
Objectives: Cellular energy metabolism is important for the function of all tissues, including cartilage. Recent studies indicate that superficial and deep subpopulations of articular chondrocytes (ACs) have distinct metabolic profiles. At the cellular and molecular level, osteoarthritis (OA) is characterised by alteration from a healthy homoeostatic state towards a catabolic state. Several molecular pathways, including transforming growth factor beta (TGF-β) and bone morphogenetic protein (BMP) signalling, have been identified as critical players in the pathogenesis and progression of OA. However, the manner in which these factors influence cellular energy metabolism in ACs is not well understood. This study investigates the effect of TGF-β or BMP signalling on energy metabolism in human articular chondrocytes (hACs).
Methods: ACs were isolated from residual macroscopically full thickness and intact cartilage from the femoral condyle of human samples obtained from patients with OA. ACs were treated with Vehicle (control), TGF-β1 or BMP2 for 48–72 hours. Metabolic assays were performed to determine glucose consumption, lactate production and adenosine triphosphate (ATP) production, whereas the mitochondrial stress test was performed to determine oxygen consumption rate. Protein was isolated to assess translational activity and was evaluated using Western blot.
Results: We showed that TGF-β1, known to maintain chondrocyte homoeostasis, stimulated glycolysis by upregulating key glycolytic factors, such as glucose transporter 1 (Glut1) and hexokinase II, while reducing oxidative phosphorylation in hACs. In contrast, BMP2 enhanced mitochondrial metabolism and oxidative phosphorylation and had a minimal effect on key glycolytic regulators.
Conclusions: Our data revealed distinct metabolic programs induced by TGF-β1 and BMP2 in hACs, suggesting that the regulation of cellular metabolism may represent a new mechanism underlying the pathogenesis of OA.
The translational potential of this article: The findings define the regulation of energy metabolism as a potential novel therapeutic approach for the treatment of OA
Deletion of EP4 in S100a4-lineage cells reduces scar tissue formation during early but not later stages of tendon healing
AbstractTendon injuries heal via scar tissue rather than regeneration. This healing response forms adhesions between the flexor tendons in the hand and surrounding tissues, resulting in impaired range of motion and hand function. Mechanistically, inflammation has been strongly linked to adhesion formation, and Prostaglandin E2 (PGE2) is associated with both adhesion formation and tendinopathy. In the present study we tested the hypothesis that deletion of the PGE2 receptor EP4 in S100a4-lineage cells would decrease adhesion formation. S100a4-Cre; EP4flox/flox (EP4cKOS100a4) repairs healed with improved gliding function at day 14, followed by impaired gliding at day 28, relative to wild type. Interestingly, EP4cKOS100a4 resulted in only transient deletion of EP4, suggesting up-regulation of EP4 in an alternative cell population in these mice. Loss of EP4 in Scleraxis-lineage cells did not alter gliding function, suggesting that Scx-lineage cells are not the predominant EP4 expressing population. In contrast, a dramatic increase in α-SMA+, EP4+ double-positive cells were observed in EP4cKOS100a4 suggesting that EP4cKOS100a4 repairs heal with increased infiltration of EP4 expressing α-SMA myofibroblasts, identifying a potential mechanism of late up-regulation of EP4 and impaired gliding function in EP4cKOS100a4 tendon repairs.</jats:p
A conceptual design study of a biological specimen holding facility. Volume 2: Technical report
Local Group dSph radio survey with ATCA (III): Constraints on Particle Dark Matter
We performed a deep search for radio synchrotron emissions induced by weakly
interacting massive particles (WIMPs) annihilation or decay in six dwarf
spheroidal (dSph) galaxies of the Local Group. Observations were conducted with
the Australia Telescope Compact Array (ATCA) at 16 cm wavelength, with an rms
sensitivity better than 0.05 mJy/beam in each field. In this work, we first
discuss the uncertainties associated with the modeling of the expected signal,
such as the shape of the dark matter (DM) profile and the dSph magnetic
properties. We then investigate the possibility that point-sources detected in
the proximity of the dSph optical center might be due to the emission from a DM
cuspy profile. No evidence for an extended emission over a size of few arcmin
(which is the DM halo size) has been detected. We present the associated bounds
on the WIMP parameter space for different annihilation/decay final states and
for different astrophysical assumptions. If the confinement of electrons and
positrons in the dSph is such that the majority of their power is radiated
within the dSph region, we obtain constraints on the WIMP annihilation rate
which are well below the thermal value for masses up to few TeV. On the other
hand, for conservative assumptions on the dSph magnetic properties, the bounds
can be dramatically relaxed. We show however that, within the next 10 years and
regardless of the astrophysical assumptions, it will be possible to
progressively close in on the full parameter space of WIMPs by searching for
radio signals in dSphs with SKA and its precursors.Comment: 17 pages, 6 figure panels. Companion papers: arXiv:1407.5479 and
arXiv:1407.5482. v3: minor revision, matches published versio
Patient-Reported Outcomes Measurement Information System physical function correlates with Toronto Extremity Salvage Score in an orthopaedic oncology population
Background: The National Institute of Health\u27s Patient-Reported Outcomes Measurement Information System (PROMIS) uses computerised-adaptive testing to reduce survey burden and improve sensitivity. PROMIS is being used across medical and surgical disciplines but has not been studied in orthopaedic oncology.
Questions/purposes: The aim of the study was to compare PROMIS measures with upper extremity (UE) and lower extremity (LE) Toronto Extremity Salvage Score (TESS) by assessing the following: (1) responder burden, (2) correlation between scores and (3) floor/ceiling effects.
Patients and methods: This cross-sectional trial analysed all 97 adult patients treated surgically for a bone or soft tissue tumour at a tertiary institution between November 2015 and March 2016. TESS (UE or LE) and PROMIS (Physical Function, Pain Interference and Depression) surveys were administered preoperatively. Pearson correlations between each PROMIS domain and TESS were calculated, as were floor/ceiling effects of each outcome measure.
Results: (1) Completion of three PROMIS questionnaires required a mean total of 16.8 (+/- 5.8 standard deviation) questions, compared with 31 and 32 questions for the LE and UE TESS questionnaires, respectively. (2) The PROMIS Physical Function scores demonstrated a strong positive correlation with the LE TESS (r = 0.84; 95% confidence interval [CI], 0.72-0.91; p \u3c 0.001) and moderate positive correlation with the UE TESS (r = 0.64; 95% CI, 0.34-0.83; p = 0.055). The PROMIS Depression scores demonstrated a weak negative correlation with both the LE TESS (r = -0.38; 95% CI, -0.61 to -0.10; p = 0.010) and with UE TESS (r = -0.38; 95% CI, -0.67 to -0.01; p = 0.055). The PROMIS Pain Interference scores demonstrated a strong negative correlation with the LE TESS (r = -0.71; 95% CI, -0.83 to -0.52; p \u3c 0.001) and a moderate negative correlation with the UE TESS (r = -0.62; 95% CI, -0.81 to -0.30; p = 0.001). (3) The UE TESS had a range of scores from 16 to 100 with a 27% ceiling effect and no floor effect, and the LE TESS had a range from 10 to 98 with no floor or ceiling effect. There was no floor or ceiling effect for any PROMIS measures.
Conclusions: In an orthopaedic oncology population, the PROMIS Physical Function and Pain Interference scores correlate with the TESS and have the benefit of reduced survey burden and ceiling effect. The PROMIS Depression scores may provide additional information regarding patient outcomes not captured by the TESS.
Level of Evidence: Level III.
The translational potential of this article: Patient reported outcome measures asses patients\u27 symptoms, function and health-related quality of life and are designed to capture more clinical information than can be gathered by objective medial testing alone. As reimbursements and the understanding of patient outcomes are becoming tied to performance on PROMIS measures, it is an important step to establish how PROMIS measures correlate and compare to traditional legacy measures
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