103 research outputs found
Evidence for operative treatment of talar osteochondral lesions: a systematic review.
Purpose
Operative treatment of talar osteochondral lesions is challenging with various treatment options. The aims were (i) to compare patient populations between the different treatment options in terms of demographic data and lesion size and (ii) to correlate the outcome with demographic parameters and preoperative scores.
Methods
A systemic review was conducted according to the PRISMA guidelines. The electronic databases Pubmed (MEDLINE) and Embase were screened for reports with the following inclusion criteria: minimum 2-year follow-up after operative treatment of a talar osteochondral lesion in at least ten adult patients and published between 2000 and 2020.
Results
Forty-five papers were included. Small lesions were treated using BMS, while large lesions with ACI. There was no difference in age between the treatment groups. There was a correlation between preoperative American Orthopaedic Foot and Ankle Society (AOFAS) score and change in AOFAS score (R = -0.849, P < 0.001) as well as AOFAS score at follow-up (R = 0.421, P = 0.008). Preoperative size of the cartilage lesion correlates with preoperative AOFAS scores (R= -0.634, P = 0.001) and with change in AOFAS score (R = 0.656, P < 0.001) but not with AOFAS score at follow-up. Due to the heterogeneity of the studies, a comparison of the outcome between the different operative techniques was not possible.
Conclusion
Patient groups with bigger lesions and inferior preoperative scores did improve the most after surgery.
Level of evidence
IV
Effect of Lateral Sliding Calcaneus Osteotomy on Tarsal Tunnel Pressure
Background:
Lateral sliding calcaneus osteotomies are common procedures to correct hindfoot varus deformities. Shifting the calcaneal tuberosity laterally (lateralization) can lead to tarsal tunnel pressure increase and tibial nerve palsy. The purpose of this cadaveric biomechanical study was to investigate the correlation of lateralization and pressure increase underneath the flexor retinaculum.
Methods:
The pressure in the tarsal tunnel of 12 Thiel-fixated human cadaveric lower legs was measured in different foot positions and varying degrees of calcaneal lateralization.
Results:
The mean pressure increased from plantarflexion (PF) to neutral position (NP) and from NP to hindfoot dorsiflexion (DF), and with increasing amounts of lateralization of the calcaneal tuberosity. The mean baseline pressure in PF was 1.5, in NP 2.2, and in DF 6.5 mmHg and increased to 8.1 in PF, 18.4 in NP, and 33.1 mmHg with 12 mm of lateralization. The release of the flexor retinaculum significantly lowered the pressure.
Conclusion:
Increasing pressures were found in the tarsal tunnel with increasing lateralization of the tuberosity and with both dorsiflexion and plantarflexion of the ankle.
Clinical Relevance:
A pre-emptive release of the flexor retinaculum for a lateralization of the calcaneal tuberosity of more than 8 mm should be considered, especially if specific patient risk factors are present. No tibial nerve palsy should be expected with 4 mm of lateralization
Patterns of subnet usage reveal distinct scales of regulation in the transcriptional regulatory network of Escherichia coli
The set of regulatory interactions between genes, mediated by transcription
factors, forms a species' transcriptional regulatory network (TRN). By
comparing this network with measured gene expression data one can identify
functional properties of the TRN and gain general insight into transcriptional
control. We define the subnet of a node as the subgraph consisting of all nodes
topologically downstream of the node, including itself. Using a large set of
microarray expression data of the bacterium Escherichia coli, we find that the
gene expression in different subnets exhibits a structured pattern in response
to environmental changes and genotypic mutation. Subnets with less changes in
their expression pattern have a higher fraction of feed-forward loop motifs and
a lower fraction of small RNA targets within them. Our study implies that the
TRN consists of several scales of regulatory organization: 1) subnets with more
varying gene expression controlled by both transcription factors and
post-transcriptional RNA regulation, and 2) subnets with less varying gene
expression having more feed-forward loops and less post-transcriptional RNA
regulation.Comment: 14 pages, 8 figures, to be published in PLoS Computational Biolog
X-ray Fluorescent Fe Kalpha Lines from Stellar Photospheres
X-ray spectra from stellar coronae are reprocessed by the underlying
photosphere through scattering and photoionization events. While reprocessed
X-ray spectra reaching a distant observer are at a flux level of only a few
percent of that of the corona itself, characteristic lines formed by inner
shell photoionization of some abundant elements can be significantly stronger.
The emergent photospheric spectra are sensitive to the distance and location of
the fluorescing radiation and can provide diagnostics of coronal geometry and
abundance. Here we present Monte Carlo simulations of the photospheric Kalpha
doublet arising from quasi-neutral Fe irradiated by a coronal X-ray source.
Fluorescent line strengths have been computed as a function of the height of
the radiation source, the temperature of the ionising X-ray spectrum, and the
viewing angle. We also illustrate how the fluorescence efficiencies scale with
the photospheric metallicity and the Fe abundance. Based on the results we make
three comments: (1) fluorescent Fe lines seen from pre-main sequence stars
mostly suggest flared disk geometries and/or super-solar disk Fe abundances;
(2) the extreme ~1400 mA line observed from a flare on V1486 Ori can be
explained entirely by X-ray fluorescence if the flare itself were partially
eclipsed by the limb of the star; and (3) the fluorescent Fe line detected by
Swift during a large flare on II Peg is consistent with X-ray excitation and
does not require a collisional ionisation contribution. There is no convincing
evidence supporting the energetically challenging explanation of electron
impact excitation for observed stellar Fe Kalpha lines.Comment: 30 pages; accepted for publication in the Astrophysical Journa
Long-Lived Individuals Show a Lower Burden of Variants Predisposing to Age-Related Diseases and a Higher Polygenic Longevity Score
Longevity is a complex phenotype influenced by both environmental and genetic factors. The genetic contribution is estimated at about 25%. Despite extensive research efforts, only a few longevity genes have been validated across populations. Long-lived individuals (LLI) reach extreme ages with a relative low prevalence of chronic disability and major age-related diseases (ARDs). We tested whether the protection from ARDs in LLI can partly be attributed to genetic factors by calculating polygenic risk scores (PRSs) for seven common late-life diseases (Alzheimer's disease (AD), atrial fibrillation (AF), coronary artery disease (CAD), colorectal cancer (CRC), ischemic stroke (ISS), Parkinson's disease (PD) and type 2 diabetes (T2D)). The examined sample comprised 1351 German LLI (≥94 years, including 643 centenarians) and 4680 German younger controls. For all ARD-PRSs tested, the LLI had significantly lower scores than the younger control individuals (areas under the curve (AUCs): ISS = 0.59, p = 2.84 × 10-35; AD = 0.59, p = 3.16 × 10-25; AF = 0.57, p = 1.07 × 10-16; CAD = 0.56, p = 1.88 × 10-12; CRC = 0.52, p = 5.85 × 10-3; PD = 0.52, p = 1.91 × 10-3; T2D = 0.51, p = 2.61 × 10-3). We combined the individual ARD-PRSs into a meta-PRS (AUC = 0.64, p = 6.45 × 10-15). Furthermore, the inclusion of nine markers from the excluded region (not in LD with each other) plus the APOE haplotype into the model raised the AUC from 0.55 to 0.61. Thus, our results highlight the importance of TOMM40/APOE/APOC1 as a longevity hub
Spitzer Observations of the Brightest Galaxies in X-ray-Luminous Clusters
We have studied the infrared properties of the brightest cluster galaxies
(BCGs) located in the cores of X-ray-luminous clusters at 0.15 < z < 0.35. The
majority of the BCGs are not particularly infrared-luminous compared with other
massive early-type galaxies, suggesting that the cluster environment has little
influence on the infrared luminosities of the BCGs. The exceptions, however,
are the BCGs in the three X-ray-brightest clusters in the sample, A1835, Z3146,
and A2390. These BCGs have a prominent far-infrared peak in their spectral
energy distributions (SEDs), and two of them (those in A1835 and Z3146) can be
classified as luminous infrared galaxies (LIRGs: L_{IR} > 10^{11} L_{sun}).
Although radio AGNs are found to be prevalent among the BCGs, the infrared
luminosities of these three BCGs, judged from the infrared SED signatures, are
likely to be powered by star formation. Considering the overall trend that
clusters with shorter radiative gas cooling times harbor more infrared-luminous
BCGs, the enhanced star formation may be caused by the cooling cluster gas
accreting onto the BCGs.Comment: 35 pages, 8 figures, 4 tables; Accepted for publication in Ap
Heating groups and clusters of galaxies: the role of AGN jets
X-Ray observations of groups and clusters of galaxies show that the
Intra-Cluster Medium (ICM) in their cores is hotter than expected from
cosmological numerical simulations of cluster formation which include star
formation, radiative cooling and SN feedback. We investigate the effect of the
injection of supersonic AGN jets into the ICM using axisymmetric hydrodynamical
numerical simulations. A simple model for the ICM, describing the radial
properties of gas and the gravitational potential in cosmological N-Body+SPH
simulations of one cluster and three groups of galaxies at redshift z=0, is
obtained and used to set the environment in which the jets are injected. We
varied the kinetic power of the jet and the emission-weighted X-Ray temperature
of the ICM. The jets transfer their energy to the ICM mainly by the effects of
their terminal shocks. A high fraction of the injected energy can be deposited
through irreversible processes in the cluster gas, up to 75% in our
simulations. We show how one single, powerful jet can reconcile the predicted
X-Ray properties of small groups, e.g. the Lx-Tx relation, with observations.
We argue that the interaction between AGN jets and galaxy groups and cluster
atmospheres is a viable feedback mechanism.Comment: 18 pages, 14 figures, to appear on Astronomy and Astrophysic
Definition and validation of a radiomics signature for loco-regional tumour control in patients with locally advanced head and neck squamous cell carcinoma
Purpose: To develop and validate a CT-based radiomics signature for the prognosis of loco-regional tumour control (LRC) in patients with locally advanced head and neck squamous cell carcinoma (HNSCC) treated by primary radiochemotherapy (RCTx) based on retrospective data from 6 partner sites of the German Cancer Consortium - Radiation Oncology Group (DKTK-ROG).
Material and methods: Pre-treatment CT images of 318 patients with locally advanced HNSCC were col-lected. Four-hundred forty-six features were extracted from each primary tumour volume and then fil-tered through stability analysis and clustering. First, a baseline signature was developed from demographic and tumour-associated clinical parameters. This signature was then supplemented by CT imaging features. A final signature was derived using repeated 3-fold cross-validation on the discovery cohort. Performance in external validation was assessed by the concordance index (C-Index). Furthermore, calibration and patient stratification in groups with low and high risk for loco-regional recurrence were analysed.
Results: For the clinical baseline signature, only the primary tumour volume was selected. The final sig-nature combined the tumour volume with two independent radiomics features. It achieved moderatel
Clusters of galaxies : observational properties of the diffuse radio emission
Clusters of galaxies, as the largest virialized systems in the Universe, are
ideal laboratories to study the formation and evolution of cosmic
structures...(abridged)... Most of the detailed knowledge of galaxy clusters
has been obtained in recent years from the study of ICM through X-ray
Astronomy. At the same time, radio observations have proved that the ICM is
mixed with non-thermal components, i.e. highly relativistic particles and
large-scale magnetic fields, detected through their synchrotron emission. The
knowledge of the properties of these non-thermal ICM components has increased
significantly, owing to sensitive radio images and to the development of
theoretical models. Diffuse synchrotron radio emission in the central and
peripheral cluster regions has been found in many clusters. Moreover
large-scale magnetic fields appear to be present in all galaxy clusters, as
derived from Rotation Measure (RM) studies. Non-thermal components are linked
to the cluster X-ray properties, and to the cluster evolutionary stage, and are
crucial for a comprehensive physical description of the intracluster medium.
They play an important role in the cluster formation and evolution. We review
here the observational properties of diffuse non-thermal sources detected in
galaxy clusters: halos, relics and mini-halos. We discuss their classification
and properties. We report published results up to date and obtain and discuss
statistical properties. We present the properties of large-scale magnetic
fields in clusters and in even larger structures: filaments connecting galaxy
clusters. We summarize the current models of the origin of these cluster
components, and outline the improvements that are expected in this area from
future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics
Review. 58 pages, 26 figure
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