1,721,015 research outputs found
Beyond inflammation: the molecular basis of bone remodeling in axial spondyloarthritis and psoriatic arthritis
Get PDFSpondyloarthritis (SpA) encompasses a group of chronic inflammatory diseases with overlapping genetic, clinical, and radiographic features. Axial spondyloarthritis (axSpA), a subset of SpA, predominantly involves the sacroiliac joints and spine, often progressing to ankylosis, severe disability, and functional impairment. Psoriatic arthritis (PsA), another SpA subtype, is characterized by a heterogeneous phenotype that includes peripheral arthritis, enthesitis, and axial involvement, frequently associated with psoriasis. Bone remodeling in axSpA and PsA is driven by a dynamic interplay between inflammatory cytokines and the uncoupling of anabolic and catabolic processes, resulting in bone erosion, systemic and local bone loss, and pathological new bone formation. In axSpA, tumor necrosis factor-alpha (TNFα) and interleukin-17A (IL-17A) drive osteoclastogenesis via the RANKL pathway while suppressing osteoblast-mediated bone formation through WNT/β-catenin signaling. Mechanical stress, combined with inflammatory mediators, promotes mesenchymal stem cell differentiation and new bone formation, which manifests as syndesmophytes and contributes to progressive ankylosis. Conversely, PsA is distinguished by concurrent bone erosion and neoformation, driven by IL-17A, IL-22, and IL- 23, with axial disease exhibiting asymmetrical, bulky para-syndesmophytes rather than the fine, hair-like syndesmophytes typical of axSpA. Advanced imaging modalities, particularly MRI, have elucidated key mechanisms of disease progression, revealing processes such as fat metaplasia and reparative changes. This review explores the intricate molecular and cellular mechanisms underlying bone remodeling in SpA, emphasizing both shared pathways and disease-specific features. It aims to enhance the understanding of these processes to support the development of more precise and effective therapeutic approaches tailored to axSpA and PsA
Advanced Imaging of Gout and Other Inflammatory Diseases Around the Knee
No full textThe knee is one of the most commonly affected joints in the course of inflammatory arthropathies, such as crystal-induced and autoimmune inflammatory arthritis. The latter group includes systemic connective tissue diseases and spondyloarthropathies. The different pathogenesis of these entities results in their varied radiologic images. Some lead quickly to joint destruction, others only after many years, and in the remaining, destruction will not be a distinguishing radiologic feature. Radiography, ultrasonography, and magnetic resonance imaging have traditionally been the primary modalities in the diagnosis of noninflammatory and inflammatory arthropathies. In the case of crystallopathies, dual-energy computed tomography has been introduced. Hybrid techniques also offer new diagnostic opportunities. In this article, we discuss the pathologic findings and imaging correlations for crystallopathies and inflammatory diseases of the knee, with an emphasis on recent advances in their imaging diagnosis
Gouty arthritis: Can we avoid unnecessary dual-energy CT examinations using prior radiographs?
Get PDFOBJECTIVE:The dual-energy CT (DECT) algorithm for urate detection is feasible only if hyperdense deposits are present. Based on our experience, around half of the performed DECT examinations show no such deposits and thus were useless for this indication. Our diagnostic accuracy study investigates whether conventional radiographs can serve as gatekeeper test prior to DECT for reliable exclusion of such radiopaque deposits. MATERIALS AND METHODS:In this retrospective study, 77 clinically indicated DECT examinations of the hand (n = 29), foot (n = 36) and ankle (n = 12) of 55 patients (13 female, mean age 62±15 years) with suspected gouty arthritis were included. Two blinded readers independently evaluated DECT, gray-scale CT images (reference standard) and corresponding standardized radiographs for the presence/location of dense soft tissue deposits. RESULTS:Interreader agreement for detection of soft tissue deposits with DECT and radiographs was excellent (DECT: both readers, κ = 1; radiographs: both readers, κ = 0.94). DECT showed soft tissue deposits in 54/77 DECT (70%) scans. 30/54 scans (56%) showed deposits on the corresponding radiographs, while in 24 scans (44%) no deposits were seen on radiographs. Test performance of radiographs for soft tissue deposit detection: sensitivity 56%, specificity 100%, PPV 100%, NPV 48.9%, and accuracy 69%. Low density of the deposits was the main reasons for false-negative radiographs (19 cases, 79%), followed by superimposition of deposits by osseous structures (5 cases, 21%). CONCLUSION:Conventional radiographs of the hand, foot and ankle cannot serve as a gatekeeper test for reliable exclusion of radiopaque soft tissue deposits prior to DECT
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dual-Energy Computed Tomography for Muskuloskeletal Diagnostic
No full textDie Dual-Energy-Computertomographie ist eine moderne Methode der CT-Bildgebung und erlaubt die bessere Charakterisierung von Geweben. In dieser kumulativen Habilitationsschrift werden die Methoden der Zwei- und Dreimaterialdifferenzierung für die muskuloskelettale Diagnostik mittels Dual-Energy-Computertomographie (DECT) in mehreren Originalarbeiten analysiert und für den Nachweis von Gichttophi und entzündliche und traumatische Veränderungen des Knochenmarkes angewendet. Mittels Phantommessungen konnte die Fähigkeit von DECT zur Unterscheidung von Kristallarthropathien ex-vivo und im Modell bestätigt und die Sensitivität für unterschiedliche Konzentrationen von Harnsäure in-vivo abgeschätzt und Protokolle hinsichtlich Sensitivität und Strahlenexposition optimiert werden. Nachdem in einer Fallserie die Machbarkeit der DECT im sequentiellen Einzelröhrensystem demonstriert worden ist, wurde die klinische Bedeutung der DECT erarbeitet, in dem sie mit der konventionellen Röntgen- und CT-Bildgebung, der Sonographie und der Arthrozentese verglichen wurde. So kann der Mehrwert der DECT in Hinblick auf die bisher übliche Diagnostik beschrieben und kritisch diskutiert werden. Im Bereich der Knochenmarksdiagnostik konnte erstmals die Sensitivität der DECT für entzündliche Knochenveränderungen im Rahmen rheumatischer Erkrankungen nachgewiesen werden und die DECT in sequentieller Volumentechnik über die räumlichen Beschränkungen des Detektors auf das Achsenskelett ausgeweitet werden. Darüber hinaus gibt die Arbeiten einen aktuellen Überblick über Anwendungsgebiete und Limitationen der Technik für die Diagnostik am muskuloskelettalen System
Microstructural analysis of grey and white Matter with diffusion tensor imaging in patients with hydrocephalus before and after chirurgical therapy
No full textDTI ist ein MRT-Bildgebungsverfahren, das eine mikrostrukturelle Analyse des
Gehirns durch Quantifizierung der Diffusionseigenschaften erlaubt. Bei
insgesamt sechzehn Patienten mit Hydrozephalus, die mit einem VP-Shunt oder
einer Ventrikulostomie behandelt wurden, konnten vor und nach operativer
Therapie und im Vergleich mit einer Kontrollgruppe mittels DTI signifikante
Veränderungen in der Pyramidenbahn, im Balken und in ventrikelnah gelegenen
Bestandteilen der Basalganglien (Nucleus caudatus) nachgewiesen werden. Diese
stimmen mit in der Vergangenheit publizierten Beobachtungen überein und
ergänzen diese. Es konnten Hinweise auf reversible, in erster Linie
kompressionsbedingte mikrostrukturelle Veränderungen im hinteren Schenkel der
Capsula interna und in den periventrikulär verlaufenden Anteilen der
Pyramidenbahn gefunden werden. Es fanden sich anhand charakteristischer
Veränderungen des Diffusionsverhaltens außerdem Belege für eine irreversible
axonale Schädigung der Balkenfasern und es gelang der indirekte Nachweis eines
erhöhten extrazellulären Wasseranteils in weiten Teilen der zerebralen weißen
Substanz, der in erster Linie auf einen vermehrten Übertritt von Wasser aus
den inneren Liquorräumen zurückgeführt wird. Die erhobenen Befunde betrafen
auch Anteile der im Rahmen konventioneller MRT-Bildgebung normal erscheinenden
weißen Substanz. Der DTI wird deshalb ein wesentlicher Platz in der
nichtinvasiven, bildgebenden Erforschung der Pathophysiologie des
Hydrozephalus und bei der Gewinnung von Zusatzinformationen neben der
konventionellen klinischen Bildgebung zuerkannt. Weitere Untersuchungen sind
erforderlich, um die praktische Relevanz dieser Informationen für
Verlaufskontrollen und Therapieentscheidungen zu evaluieren.DTI is a MRI imaging technique that enables a microstructural Analysis of the
brain through quantification of the diffusion parameters. We measured
significant changes in the corticospinal tract (CST), the corpus callosum and
the paraventricular basal ganglia (caudate nucleus) in sixteen patients with
hydrocephalus, that were treated with ventriculoperitoneal shunt or
ventriculostomia. That changes are similar to the already published
oberservations but also supplement new details. We found indications of
reversible microstructural changes in the posterior limb of the internal
capsule and periventrikular parts of the CST primarily due to compression. We
also found poofs of irreversible neuronal damage on the basis of
characteristic changes of the diffusion parameters as well as an indirect
detection of elevated extracellular water content in large parts of the white
matter – most likely due to increased movement of water from the ventricle
system. These changes also included parts of in conventional MRI normal
appearing white matter. Therefore, we think that DTI is an important part of
non-invasive imaging science in pathophysiology of the hydrocephalus and
provides complementary information in conventional clinical Imaging. Further
studies are needed to evaluate the practical relevance of these information in
medical follow-up and therapeutic decisions
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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