194 research outputs found
An Early Transcriptional Analysis of Fracture Hematoma in Rat
Among other stressors, age and mechanical constraints significantly influence
regeneration cascades in bone healing. Here, our aim was to identify genes
and, through their functional annotation, related biological processes that
are influenced by an interaction between the effects of mechanical fixation
stability and age. Therefore, at day three post-osteotomy, chip-based whole-
genome gene expression analyses of fracture hematoma tissue were performed for
four groups of Sprague-Dawley rats with a 1.5-mm osteotomy gap in the femora
with varying age (12 vs. 52 weeks - biologically challenging) and external
fixator stiffness (mechanically challenging). From 31099 analysed genes, 1103
genes were differentially expressed between the six possible combinations of
the four groups and from those 144 genes were identified as statistically
significantly influenced by the interaction between age and fixation
stability. Functional annotation of these differentially expressed genes
revealed an association with extracellular space, cell migration or
vasculature development. The chip-based whole-genome gene expression data was
validated by q-RT-PCR at days three and seven post-osteotomy for MMP-9 and
MMP-13, members of the mechanosensitive matrix metalloproteinase family and
key players in cell migration and angiogenesis. Furthermore, we observed an
interaction of age and mechanical stimuli in vitro on cell migration of
mesenchymal stromal cells. These cells are a subpopulation of the fracture
hematoma and are known to be key players in bone regeneration. In summary,
these data correspond to and might explain our previously described
biomechanical healing outcome after six weeks in response to fixation
stiffness variation. In conclusion, our data highlight the importance of
analysing the influence of risk factors of fracture healing (e.g. advanced
age, suboptimal fixator stability) in combination rather than alone
Pose Measurement Performance of the Argon Relative Navigation Sensor Suite in Simulated Flight Conditions
Argon is a flight-ready sensor suite with two visual cameras, a flash LIDAR, an on- board flight computer, and associated electronics. Argon was designed to provide sensing capabilities for relative navigation during proximity, rendezvous, and docking operations between spacecraft. A rigorous ground test campaign assessed the performance capability of the Argon navigation suite to measure the relative pose of high-fidelity satellite mock-ups during a variety of simulated rendezvous and proximity maneuvers facilitated by robot manipulators in a variety of lighting conditions representative of the orbital environment. A brief description of the Argon suite and test setup are given as well as an analysis of the performance of the system in simulated proximity and rendezvous operations
A Study of 323 Asymptomatic Volunteers
Background The understanding of the individual shape and mobility of the
lumbar spine are key factors for the prevention and treatment of low back
pain. The influence of age and sex on the total lumbar lordosis and the range
of motion as well as on different lumbar sub-regions (lower, middle and upper
lordosis) in asymptomatic subjects still merits discussion, since it is
essential for patient-specific treatment and evidence-based distinction
between painful degenerative pathologies and asymptomatic aging. Methods and
Findings A novel non-invasive measuring system was used to assess the total
and local lumbar shape and its mobility of 323 asymptomatic volunteers (age:
20–75 yrs; BMI <26.0 kg/m2; males/females: 139/184). The lumbar lordosis for
standing and the range of motion for maximal upper body flexion (RoF) and
extension (RoE) were determined. The total lordosis was significantly reduced
by approximately 20%, the RoF by 12% and the RoE by 31% in the oldest (>50
yrs) compared to the youngest age cohort (20–29 yrs). Locally, these decreases
mostly occurred in the middle part of the lordosis and less towards the lumbo-
sacral and thoraco-lumbar transitions. The sex only affected the RoE.
Conclusions During aging, the lower lumbar spine retains its lordosis and
mobility, whereas the middle part flattens and becomes less mobile. These
findings lay the ground for a better understanding of the incidence of level-
and age-dependent spinal disorders, and may have important implications for
the clinical long-term success of different surgical interventions
The processing of it and this in written narrative discourse
Two experiments explored the hypothesis that anaphors and demonstratives signal different procedural instructions: while the anaphor it brings a concrete entity into a reader’s focus, the demonstrative this directs the focus to a predicate proposition in a discourse representation. The findings from an online eye-tracking reading experiment confirm that preferences for it and this differ as predicted.Moreover, a sentence-completion experiment revealed converging evidence for this difference, with clear differences in antecedent preferences for it and this. Overall, findings show that the processing and use of anaphoric expressions is affected by the interaction between the lexical characteristics of referential forms and different types of referent
Defining the canal for ischial and pubic screws in cup revision surgery
Abstract Purpose When revising acetabular cups, it is often necessary to provide additional stabilisation with screws. In extensive defect situations, the placement of screws caudally in the ischium and/or pubis is biomechanically advantageous. Especially after multiple revision operations, the surgeon is confronted with a reduced bone stock and unclear or altered anatomy. In addition, screw placement caudally is associated with greater risk. Therefore, the present study aims to identify and define safe zones for the placement of caudal acetabular screws. Methods Forty-three complete CT datasets were used for the evaluation. Sixty-three distinctive 3D points representing bone landmark of interests were defined. The coordinates of these points were then used to calculate all the parameters. For simplified visualisation and intra-operative reproducibility, an analogue clock was used, with 12 o’clock indicating cranial and 6 o’clock caudal. Results A consistent accumulation was found at around 4.5 ± 0.3 hours for the ischium and 7.9 ± 0.3 hours for the pubic bone. Conclusions The anatomy of the ischium and pubis is sufficiently constant to allow the positioning of screws in a standardised way. The interindividual variation is low — regardless of gender — so that the values determined can be used to position screws safely in the ischium and pubis. The values determined can provide the surgeon with additional orientation intra-operatively when placing caudal acetabular screws
Strategies for Digital Music Markets: Pricing and the Effectiveness of Measures Against Pirate Copies - Results of an Empirical Study
The recording industry is still facing a global decline in revenues and record sales. Paid music services have failed to deliver on their promise of a full-catalog shopping experience so far, and filesharing platforms are still widely used for obtaining online music. In this context we conducted an empirical study via the Internet with 2.260 participants. The main results are: Neither the installation of copy protection measures nor legal actions against users of file-sharing platforms seem to be appropriate means to increase sales of CDs and online music. Potential consumers’ willingness to pay is distinctly lower than the prices currently set by the available paid music services. Our study\u27s results suggest that a price cut for music downloads would lead to increased sales, thus creating benefits for both suppliers and consumers
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
Local Infiltrations in Patients with Radiculopathy or Chronic Low Back Pain Due to Segment Degeneration—Only A Diagnostic Value?
The purpose of this study was to investigate the differences in the therapeutic effectiveness of CT-assisted infiltration of a local anesthetic + corticosteroid between nerve root and facet joint capsule in patients with chronic complaints. In this prospective trial with a 12-month follow-up, a total of 250 patients with chronic low back pain and radiculopathy were assigned to two groups. In the first group, patients with specific lumbar pain due to spondyloarthritis received periarticular facet joint capsule infiltration (FJI). In the second group, patients with monoradicular pain received periradicular infiltration (PRI) via an extraforaminal selective nerve block. Clinical improvement after FJI and PRI regarding pain (NRS), function (ODI), satisfaction (McNab), and health related quality of life (SF-36) were compared. Minimally clinically important difference (MCID) served as the threshold for therapeutic effectiveness evaluation. A total of 196 patients were available for final analysis. With respect to the pain reduction and functional improvement (ODI, NRSoverall, and NRSback), the PRI group performed significantly better (ptreatment < 0.001) and longer over time (ptreatment × time 0.001) than the FJI group. Regarding pain and function, only PRI demonstrated a durable improvement larger than MCID. A significant and durable therapeutic value was found only after receiving PRI but not after FJI in patients with chronic pain
Patient-controlled sublingual sufentanil tablet system versus intravenous opioid analgesia for postoperative pain management after lumbar spinal fusion surgery
Abstract Purpose This retrospective cohort study investigated the efficacy of a sublingual sufentanil tablet system (SSTS) in comparison to intravenous patient-controlled analgesia (IV-PCA) with piritramide for the management of postoperative pain following lumbar spinal fusion surgery. Methods This was a retrospective analysis of patients undergoing single- or two-level lumbar spinal fusion surgery and receiving the SSTS or IV-PCA for postoperative pain relief as part of multimodal pain management that included IV paracetamol and oral metamizole. The following variables were collected: postoperative pain intensity and frequency scores using the numerical rating scale (NRS), hospital anxiety and depression scale (HADS), occurrence of nausea, postoperative mobilization, and patient satisfaction (MacNab criteria). Results Sixty-four patients were included. Those receiving the SSTS ( n = 30) had significantly lower pain intensities on the operative day (NRS: 4.0, CI: 3.6–4.3 vs. 4.5, CI: 4.2–4.9; p < 0.05) and one day postoperatively (NRS: 3.4, CI: 3.1–3.8 vs. 3.9 CI: 3.6–4.3; p < 0.05) compared to patients receiving IV-PCA ( n = 34). No differences were observed on postoperative days 2 to 5. SSTS patients experienced more nausea than IV-PCA patients ( p = 0.027). Moreover, SSTS patients had a higher percentage of early mobilization following surgery than IV-PCA patients ( p = 0.040). Regarding patient satisfaction, no significant differences were seen between the groups. Conclusion The SSTS is a potentially advantageous alternative to opioid IV-PCA for use within a multimodal approach to managing postoperative pain after lumbar fusion surgery. Furthermore, the potentially higher emetic effect of SSTS should be considered, and the patient should be able to perform the application
Destructive per continuitatem spondylodiscitis after endovascular abdominal or thoracic aneurysm repair (EVAR/TEVAR): rare and untreatable?
Introduction Very few publications have previously described spondylodiscitis as a potential complication of endovascular aortic procedures (EVAR/TEVAR). We present to our knowledge the first case series of spondylodiscitis following EVAR/TEVAR based on our data base. Particular focus was laid on the complexity of disease treatment and grave outcome perspectives from a spine surgeon’s point of view in this seriously affected patient group. Materials and methods A retrospective analysis and chart review was performed for 11 out of 284 consecutive spondylodiscitis patients who underwent EVAR/TEVAR procedure and developed destructive per continuitatem spondylodiscitis. Results All 11 patients had single or more level destructive spondylodiscitis adjacent to the thoracic/lumbar stent graft. In mean, four surgeries were performed per patient to treat this rare complication. Six out of eleven patients (55%) died within 6 months of first identification of per continuitatem spondylodiscitis. In four patients due to persisting infection of the graft and recurrence of the abscess formation, a persisting fistula from anterior approach to the skin was applied. Conclusions Destructive per continuitatem spondylodiscitis is a rare and severe complication post-EVAR/TEVAR. Clinical and imaging features of anterior paravertebral disease and anterior vertebral body involvement suggest direct continuous spread of the graft infection to the adjacent vertebral column. The mortality rate of these severe infections is extremely high and treatment with a permanent fistula may be one salvage procedure
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