1,721,078 research outputs found
Patient perspectives on use of stem cells to treat osteoporosis
Full text linkOsteoporosis is a systemic skeletal disease leading to increased risk of fragility fractures. These fractures lead to significant patient morbidity, increased mortality and substantial health and social care costs. The use of stem cells for cell-based therapies is currently an exciting, promising and growing area for disease treatment and regenerative medicine. However, the attitudes of participants towards the use of stem cells for regenerative medicine applications, particularly for therapeutic interventions amongst the older population, have not been well explored.This study explored patient perceptions of a proposed new treatment utilising a novel orthobiologic stem cell therapy. An online questionnaire for participants affected by osteoporosis was designed using the ‘Bristol Online Survey’ tool. In addition, three focus groups were held to explore a number of the issues raised by the findings in more depth.Findings showed that acceptability for the new treatment was high, as current treatments were variable in their effectiveness and new treatments were keenly welcomed. Participants indicated a willingness to have the proposed treatment in order to reduce their chance of experiencing a fracture, regardless of whether the treatment would reduce existing pain, or improve existing quality of life. The use of both autologous and allogeneic stem cells was acceptable, with slight differences in opinion indicating reservations regarding the potentially painful nature of stem cell extraction and allogeneic stem cell rejection. The findings demonstrated a clear mandate to the research team (and community) to continue their efforts in developing stem cell-based treatments for bone repair applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Bioaktive Phosphatgläser
Full text linkDue to their tunable solubility, phosphate-based glasses (PBG) also in the form of phosphate glass fibres (PGF), are gaining increasing attention as materials for medical applications representing an interesting alternative to antibiotics. A controlled release of ions from the glass can result in improved biological properties or bring antibacterial capability. In the presented studies, a modified melt quenching method delivered phosphate-based glasses based on the quaternary system P2O5–CaO–Na2O–MgO. In order to impact antibacterial properties, cerium oxide (CeO2) and gallium oxide (Ga2O3) were incorporated into the glass matrix. Later, two glass compositions were used to manufacture cerium-doped and gallium-doped phosphate glass fibres (Ce-PGF and Ga-PGF).
The physicochemical and biological properties of novel PBG and PGF were characterised using several techniques. The structure of the glasses was analysed using Raman, Fourier Transorm Infrared Spectroscopy (FTIR), Differential scanning calorimetry (DSC), X-ray powder fluorescence (XRF) and X-ray powder diffraction (XRD) techniques. Correlations between the glass composition and its structure were found, showing an impact of gallium and cerium inclusion into the glass matrix. Addition of Ga and Ce has shown to increase glass transition temperature and processing windows. The XRD confirmed the amorphous character of the novel phosphate-based glasses. Moreover, the dissolution behaviour, surface charge (measured by zeta potential), ion release and pH were shown to depend on elemental composition. In particular the relative amounts of Ca and Mg showed a vast influence on the glass dissolution behaviour. The dissolution rate increase with an increase of magnesium content and decrease with an increase of calcium amount. A bioactivity test in simulated body fluid (SBF) did not confirm the bioactive properties of PBG and PGF. The mechanical properties performed using a single fibre tensile test method showed tensile strengths of 428 (±94) and 379 (±74) MPa and elastic moduli of 45 (±4) and 54 (±9) GPa for the novel Ce-PGF (26 µm) and Ga-PGF (18 µm), respectively. Moreover, viscosity measurements were carried out for gallium-doped phosphate glass which revealed the complex melting behaviour of this particular composition material.
Biological evaluation of PBG and PGF showed a positive cell response in different cell culutres related to both hard and soft tissues. Cell viability of a bone marrow-derived stromal cell line (ST-2) was measured showing promising results for glasses doped with cerium. An in vitro scratch test using both soft tissue cells: mice embryonic fibroblast (MEF), and hard tissue cells: osteoblast precursor cell line derived from mouse calvaria (MC3T3-E1), resulted in cell migration towards wound closure. Moreover, the proliferation behaviour was tested showing that cerium-doped samples improved proliferation of MC3CT-E1 cells.
Antibacterial properties were investigated using disc diffusion method and a turbidity measurements against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus carnosus. The antibacterial effect increased with increasing Ga/Ce content in the glass.
The last step in the investigation of novel phosphate-based glasses and phosphate glass fibres involved composite manufacturing. Two different types of PBG-polymer composites were produced: random mesh and 3D discs (PGF/Alg). Random mesh was obtained from Ce-PGF and methylcellulose and was used to create a prototype soluble wound dressing. A 3D disc was manufactured by immersing a random mesh in sodium alginate solution and further crosslinking with CaCl2. The compressive strength of hydrogel (PGF/Alg) was assessed. The mesh-like structure exhibited a high dissolution rate and showed outstanding water uptake which are both promising properties for wound healing applications.
Addition of gallium and cerium into the parent glass matrix influenced several properties, namely decreased dissolution rate, decreased pH (to slightly acidic), increased negative value of the zeta potential as well as influenced glass transition temperature. The influence of the Ga/Ce on the structural properties on the glasses was confirmed by the changes in the characteristic peaks in FTIR or Raman spectra, without compromising the amorphous character of the glass. Release of Ce/Ga ions influenced the biological properties, both cell response and antibacterial capability of the glass. Increase of gallium content increased antibacterial performance, however when Ga content was too high, the glass became toxic for cells. Cerium-doped glasses showed cell viability and improved proliferation with moderate antibacterial properties.
In summary, this research was successful in designing and manufacturing a series of biocompatible novel phosphate-based glasses and phosphate glass fibres with antibacterial properties for potential application in the medical field, both in hard and soft tissue repair.Das HyMedPoly-Projekt konzentriert sich auf medikamentenfreies antibakterielles Material für medizinische Anwendungen als Antwort auf das wachsende Problem der Bakterienresistenz. Aufgrund ihrer abstimmbaren Löslichkeit gewinnen Phosphat-basierte Gläser (PBG) und Phosphatglasfasern (PGF) als Materialien für medizinische Anwendungen zunehmend an Bedeutung und sind eine interessante Alternative für Antibiotika. Eine kontrollierte Freisetzung von Ionen aus dem Glas kann zu verbesserten biologischen Eigenschaften führen oder antibakterielle Fähigkeiten bringen. In den vorgestellten Studien lieferte ein modifiziertes Schmelzabschreckverfahren phosphatbasierte Gläser auf Basis des quaternären Systems P2O5–CaO–Na2O–MgO. Um antibakterielle Eigenschaften zu erzielen, wurden Ceroxid (CeO2) und Galliumoxid (Ga2O3) in die Glasmatrix eingebaut. Später wurden zwei Glaszusammensetzungen verwendet, um Ce-dotierte und Gallium-dotierte Phosphatglasfasern (Ce-PGF und Ga-PGF) herzustellen.
Die physikochemischen und biologischen Eigenschaften von neuartigen PBG und PGF wurden unter Verwendung verschiedener Techniken charakterisiert. Die Struktur der Gläser wurde unter Verwendung der Raman-, FTIR-, DSC-, XRF- und XRD-Technik analysiert. Es wurde eine Korrelation zwischen der Glaszusammensetzung und der Struktur des Glases gefunden, die einen Einfluss von Gallium und Cer in die Glasmatrix zeigt. Die Zugabe von Ga und Ce erhöht die Glasübergangstemperatur und das Verarbeitungsfenster. Das XRD bestätigte den amorphen Charakter neuer Gläser auf Phosphatbasis. Darüber hinaus waren das Auflösungsverhalten und die Oberflächenladung, gemessen durch Zetapotential, Ionenfreisetzung und pH, von der Elementzusammensetzung abhängig. Insbesondere Ca und Mg haben einen großen Einfluss auf das Auflösungsverhalten von Glas. Die Auflösung steigt mit steigendem Magnesiumgehalt und nimmt mit steigender Calciummenge ab. Der Bioaktivitätstest in simulierter Körperflüssigkeit (SBF) bestätigte nicht die bioaktiven Eigenschaften von PBG und PGF. Die mechanischen Eigenschaften, die unter Verwendung des Einzelfaser-Zugtestverfahrens durchgeführt wurden, zeigten jeweils eine Zugfestigkeit von 428 (± 94) und 379 (± 74) MPa sowie einen Elastizitätsmodul von 45 (± 4) und 54 (± 9) GPa des neuen Ce-PGF (26 µm) bzw. Ga-PGF (18 µm). Darüber hinaus wurde die Viskositätsmessung für mit Gallium dotiertes Phosphatglas hinsichtlich der Komplexität des Schmelzverhaltens durchgeführt. Die biologische Bewertung von PBG und PGF zeigte eine gute Zellantwort sowohl auf hartes als auch auf weiches Gewebe. Die Lebensfähigkeit der Zellen einer aus Knochenmark stammenden Stromazelllinie (ST-2) wurde gemessen, was vielversprechende Ergebnisse für mit Cer dotierte Gläser zeigt. Der In-vitro-Kratztest unter Verwendung sowohl von Weichgewebszellen, embryonale Fibroblasten der Maus (MEF), als auch von Hartgewebszellen, Osteoblasten-Vorläuferzelllinie, die aus der Calvaria der Maus (MC3T3-E1) stammten, führte zur Migration der Zellen in Richtung Wundverschluss. Darüber hinaus wurden das Proliferationsverhalten und die Verdopplungszeit gemessen, was zu der Schlussfolgerung führte, dass Cer-dotierte Proben die Proliferation von MC3CT-E1-Zellen verbesserten. Antibakterielle Eigenschaften wurden unter Verwendung der Scheibendiffusionsmethode und einer Trübungsmessung gegen Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis und Staphylococcus carnosus untersucht. Die antibakterielle Wirkung nahm mit zunehmendem Ga / Ce-Gehalt im Glas zu.
Der letzte Schritt bei der Untersuchung neuartiger phosphatbasierter Gläser und Phosphatglasfasern war die Herstellung von Verbundwerkstoffen. Drei verschiedene Arten von PBG-Polymer-Verbundwerkstoffen wurden hergestellt: zufällig orientierte Fasergeflechte und 3D-Scheiben (PGF/Alg). Das zufällig orientierte Fasergeflecht wurde aus Ce-PGF und Methylcellulose als löslicher Wundverband erhalten. Eine 3D-Scheibe wurde durch Eintauchen eines zufälligen Gitters in eine Natriumalginatlösung und Vernetzen mit CaCl2 hergestellt. Die mechanischen Eigenschaften des Verbundwerkstoffs wie Druckfestigkeit (PGF/Alg) wurden gemessen. Die maschenartige Struktur weist eine hohe Auflösungsrate auf, zeigt jedoch eine hervorragende Wasseraufnahme, was vielversprechende Eigenschaften für Wundheilungsanwendungen ist.
Die Zugabe von Gallium und Cer in die Glasmatrix beeinflusst mehrere Eigenschaften – sie verringert die Auflösungsrate, senkt den pH-Wert (leicht sauer), verschiebt das Zeta-Potential zu einer stärker negativ geladenen Oberfläche und beeinflusst auch die Glasübergangstemperatur. Das Vorhandensein von Ga/Ce kann im Glas als Veränderung der charakteristischen Peaks im FTIR- oder Raman-Spektrum gesehen werden, ohne den amorphen Charakter des Glases zu beeinträchtigen. Die Freisetzung von Ce/Ga beeinflusst die biologischen Eigenschaften, sowohl die Antwort der Zellen als auch die antibakterielle Fähigkeit des Glases. Eine Erhöhung des Galliumgehalts erhöht die antibakterielle Leistung, wird jedoch bei zu hohen Werten für die Zellen toxisch. Cer-dotierte Gläser zeigten Zellviabilität und verbesserte Proliferation mit moderaten antibakteriellen Eigenschaften.
Zusammenfassend ist es gelungen, neuartige phosphatbasierte Gläser und Phosphatglasfasern mit antibakteriellen Eigenschaften und potentieller Anwendung im medizinischen Bereich zu entwickeln und herzustellen
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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