130,404 research outputs found
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Design of graded biomimetic osteochondral composite scaffolds
No full textWith the ultimate goal to generate suitable materials for the repair of osteochondral defects, in this work we aimed at developing composite osteochondral scaffolds organized in different integrated layers, with features which are biomimetic for articular cartilage and subchondral bone and can differentially support formation of such tissues. A biologically inspired mineralization process was first developed to nucleate Mg-doped hydroxyapatite crystals on type I collagen fibers during their self-assembling. The resulting mineral phase was non-stoichiometric and amorphous, resembling chemico-physical features of newly deposited, natural bone matrix. A graded material was then generated, consisting of (i) a lower layer of the developed biomineralized collagen, corresponding to the subchondral bone, (ii) an upper layer of hyaluronic acid-charged collagen, mimicking the cartilaginous region, and (iii) an intermediate layer of the same nature as the biomineralized collagen, but with a lower extent of mineral, resembling the tidemark. The layers were stacked and freeze-dried to obtain an integrated monolithic composite. Culture of the material for 2 weeks after loading with articular chondrocytes yielded cartilaginous tissue formation selectively in the upper layer. Conversely, ectopic implantation in nude mice of the material after loading with bone marrow stromal cells resulted in bone formation which remained confined within the lower layer. in conclusion, we developed a composite material with cues which are biomimetic of an osteochondral tissue and with the capacity to differentially support cartilage and bone tissue generation. The results warrant testing of the material as a substitute for the repair of osteochondral lesions in orthotopic animal models
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Valutazione istologica di apatite biomimetica SINTlife in alveoli postestrattivi umani.
No full textTra le varie tecniche atte alla preservazione/ricostruzione delle dimensioni dell’osso alveolare edentulo
ai fini di ottimizzare l’inserzione dell’impianto, l’utilizzo di innesti sintetici come sostituti degli
autoinnesti ossei è sempre più frequente. Tra questi, l'idrossiapatite è stata largamente utilizzata
come sostituto d'osso grazie alla sua eccellente biocompatibilità e osteoconduttività. Recenti
studi hanno dimostrato che l’inserimento del magnesio nella struttura chimica dell’idrossiapatite
rende questo materiale molto simile per composizione alla dentina naturale. Lo scopo del presente
studio è stato valutare istologicamente e radiograficamente a distanza variabile tra 1 e 7 mesi
dall’impianto, le capacità osteoconduttive del biomateriale SINT-lifeTM (sostituto osseo biomimetico
a base di idrossiapatite non stechiometrica) in siti alveolari postestrattivi nell’uomo. I risultati
di questo studio consentono di affermare che SINT-lifeTM è caratterizzato da ottima biocompatibilità
e ottime proprietà di osteointegrazione. L’intimo rapporto tra particelle di biomateriale
e l’osso neoformato, nelle sue diverse fasi di formazione e mineralizzazione, consente di asserire
la capacità osteoconduttiva del materiale. Caratteristico di SINT-lifeTM è la presenza di un processo
di calcificazione/mineralizzazione che avviene all’interno delle particelle di materiale. La
radioopacità del materiale è risultata essere sovrapponibile a quella del tessuto osseo nativo
A novel nano-composite multi-layered biomaterial for treatment of osteochondral lesions: Technique note and an early stability pilot clinical trial
No full textINTRODUCTION:
Osteochondral articular defects are a key concern in orthopaedic surgery. Current surgical techniques to repair osteochondral defects lead to poor subchondral bone regeneration and fibrocartilage formation, which is often associated with joint pain and stiffness. The objective of this pilot clinical study is to evaluate the performance and the intrinsic stability of a newly developed biomimetic osteochondral scaffold and to test the safety and the feasibility of the surgical procedure.
METHODS:
A gradient composite osteochondral scaffold based on type I collagen-hydroxyapatite was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles. Thirteen patients (15 defect sites) were treated with scaffold implantation from January 2007 to July 2007: four at the medial femoral condyle, two at the lateral femoral condyles, five at the patellas and four at the trochleas. The mean size of the defects was 2.8 cm(2) (range: 1.5-5.9 cm(2)). All patients were followed up prospectively. High-resolution magnetic resonance imaging (MRI) was used to determine "the early postoperative adherence rate" at 4-5 weeks and 25-26 weeks after scaffold implantation. Moreover, the magnetic resonance observation of cartilage repair tissue (MOCART) score was performed on every MRI. Two second-looks were performed at 6 months; cartilage repair was assessed using the International Cartilage Repair Society (ICRS) visual scoring system and histological and immunohistochemical analysis of the two biopsies was carried out.
RESULTS:
A completely attached graft and repair tissue were found in 13 of 15 lesions (86.7%). A partial detachment was observed in two patients (13.3%). No detached grafts were found. Complete filling of the cartilage defect and congruency of the articular surface were seen in 10 lesions (66.7%) with MRI evaluation at 6 months. The complete integration of the grafted cartilage was detected in eight lesions (53.3%). Subchondral bone changes (oedema or sclerosis) were found in eight defects (53.3%). Statistical analysis showed a significant improvement in the International Knee Documentation Committee (IKDC) subjective and objective scores from preoperative to 6 months' follow-up (p<0.0005). Visual scoring of the repaired tissue at second-look revealed a normal repair score in one case and a near-normal repair score in the other case. Histological analysis showed the formation of subchondral bone without the presence of biomaterial. The cartilage repair tissue appeared to be engaged in an ongoing maturation process.
CONCLUSIONS:
The technique is safe and MRI evaluation at short-term follow-up has demonstrated good stability of the scaffold without any other fixation device. The preliminary clinical results at short-term follow-up are encouraging. A clinical and MRI study with longer follow-up and randomised studies will be done to confirm the high potential of this novel osteochondral scaffold
Nuovo scaffold biomimetico nanostrutturato per il trattamento dei difetti osteocondrali: studio pilota”
No full textPerno per l’ancoraggio di protesi articolari e protesi articolare comprendente tale perno
No full text
NEW GENERATION OF ORTHOPEDIC MIMETIC BIOCERAMICS ASSAYED WITH HUMAN MESENCHYMAL STEM CELLS
No full textDeveloping of functionally active human tissues in vitro, or inducing their regeneration in vivo, are prerequisite for regenerative medicine applications. The effectiveness of orthopedic surgical procedures often fall into clinical problems related to the availability of bone allograft or substitutes, thus engineering of bone tissue plays a prominent role in applied research to this field. Recently research focused its attention to the development of biomaterials which exhibit two main features: the capability (i) of making available a favorable cellular environment and (ii) of inducing precursor bone cell proliferation and differentiation, to develop bone tissue. In such context, calcium and phosphate-based substitutes have led to the constitution of a new class of biomaterials termed “bioceramics”. Assaying of bioceramics bone substitutes features employing mesenchymal stem cellular models represent an important tool for understanding the interaction between engineered matrices and osteoblast precursors, as well as their involvement in modulation of developmental processes
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