1,721,083 research outputs found
Revisione sistematica della letteratura sull’effetto dei concentrati piastrinici nel trattamento chirurgico dei difetti parodontali
No full textObiettivi
Scopo di questa revisione della letteratura è valutare in modo sistematico gli effetti dei concentrati piastrinici autogeni (CP) in aggiunta al trattamento chirurgico dei difetti parodontali.
Materiali e metodi
È stata effettuata una ricerca elettronica in MedLine, Em-Base e Cochrane Central Register of Controlled Trials utilizzando specifiche parole chiave. È stata eseguita anche una ricerca manuale nell’ambito delle principali riviste nel campo della parodontologia. Sono stati inclusi solo gli studi randomizzati. Il livello di attaccamento clinico era la principale variabile di successo per i difetti intraossei parodontali. L’aumento della copertura radicolare e l’aumento della cheratinizzazione tissutale erano le principali variabili della recessione gengivale. Per l’analisi statistica tutti i dati sono stati normalizzati rispetto ai valori basali. È stato valutato anche il rischio di bias degli studi inclusi. Per i difetti intraossei sono state analizzate anche le influenze della rigenerazione tissutale guidata (Guided Tissue Regeneration, GTR), del tipo di studio (split-mouth vs studi paralleli) e del tipo di CP (Platelet Rich Plasma, PRP, vs Platelet Rich Fibrin, PRF).
Risultati
Dei 456 articoli inizialmente esaminati, 48 erano idonei e ne è stato analizzato il testo completo. Infine, 34 studi sono stati inclusi: 24 studi sui difetti parodontali intraossei, 7 studi sulla recessione gengivale e 3 studi sui difetti di forcazione. È stato rilevato un significativo effetto positivo dell’aggiunta del CP nel trattamento dei difetti intraossei. Tale effetto era amplificato negli studi in cui non si utilizzava la GTR, mentre negli studi con GTR l’uso del CP non aveva un effetto adiuvante. Non è stato trovato alcun effetto del tipo di studio, della durata del follow-up o del tipo di CP. Tutti gli studi split-mouth (eccetto uno in cui è stata utilizzata la GTR) hanno mostrato un significativo effetto positivo del CP. Per il trattamento della recessione gengivale non è stato trovato alcun beneficio significativo del CP. Per il trattamento dei difetti di forcazione sono stati riportati vantaggi positivi del CP, ma non si è potuta eseguire alcuna metanalisi a causa dell’eterogeneità degli studi.Objectives The aim of this review was to systematically evaluate the effects of autogenous platelet concentrates (PC) as an adjunct to the surgical treatment of periodontal defects.
Materials and methods
An electronic search was performed on MedLine, EmBase, and the Cochrane Central Register of Controlled Trials using specific search terms. A manual search of the main journals in the field of periodontology was also performed. Only randomized trials were included. The clinical attachment level was the primary outcome variable for periodontal intrabony defects. Root coverage and keratinized tissue increase was the main variable for gingival recession. For the statistical analysis all data were normalized to baseline values. The risk of bias of the included studies was also assessed. For intrabony defects, the influences of Guided Tissue Regeneration (GTR), of the study type (split-mouth vs parallel studies), and of the type of PC (Platelet Rich Plasma, PRP, vs Platelet Rich Fibrin, PRF) were also evaluated.
Results
Of the 456 studies initially retrieved, 48 were eligible and their full text was examined. Finally, 34 studies were included: 24 studies on periodontal intrabony defects, 7 studies on gingival recession, and 3 studies on furcation defects. A significant positive effect of the adjunct of PC was found for intrabony defects. Such an effect was magnified in studies in which GTR was not used, whereas in studies that used GTR, the use of PC had no adjunctive effect. No effect of the study type, of the follow-up duration or of the type of PC was observed. All split-mouth studies (except one in which GTR was used) displayed a significant positive effect of PC. No significant effect of PC was found for gingival recession treatment. Significant benefits of PC were reported for furcation treatment but, due to heterogeneity of the studies, no meta-analysis could be done.
Conclusions
The use of PC may exert a positive adjunctive effect for the treatment of intrabony defects when used in combination with graft materials, but not with GTR. No significant adjunctive benefit of PC could be demonstrated for the treatment of gingival recession and furcation defects. A standardization of study design and clinical protocols is needed in future studies in order to gain more insight into the true effect of PC in periodontal regeneration
PLATELET CONCENTRATE AND TISSUE REGENERATION: DOES IT WORK? A PRE-CLINICAL STUDY
Full text linkDuring the last decades, the combination of cellular and molecular biology and mechanical engineering, has stimulated the development of new multidisciplinary fields in biomedical sciences, such as tissue engineering and regenerative medicine. The primary goal of these approaches is to provide an alternative to organ and tissue transplantation, by creating viable substitutes for damaged or diseased organs and tissues.
Tissue healing is a complex process that involves a cascade of cellular and molecular events, that are mostly shared by the different tissues of the body. Interestingly, the tissue repair process initiates immediately after a traumatic injury and is mediated and controlled by a wide range of cytokines, proteins and growth factors released from platelets upon activation. Consequently, many growth factors have being considered as therapeutic molecules for the repair or regeneration of a wide range of tissues. Although their role has been only partially elucidated, the potential benefit of most growth factors has been demonstrated. In the last few years, the development of platelet-rich preparations has revolutionized the field of regenerative medicine, due to the repair capacities of the platelet-released growth factors, that stimulate and accelerate both soft and hard tissue healing and regeneration. Today, platelet concentrates are used in a wide range of disciplines such as dentistry, oral surgery, orthopedics, sport medicine, dermatology, and plastic and reconstructive surgery. Currently, different techniques to obtain these hemocomponents are available, each leading to preparations that may differ in platelet concentration, leukocyte and fibrin content. Among them, there is Plasma Rich in Growth Factors (PRGF), a preparation rich in platelets, easily obtained from a small volume of patient’s blood, which, being autologous, does not promote any immune reaction and infectious disease transmission. Additionally, leukocytes are excluded from PRGF, so as to avoid any pro-inflammatory effects. Despite the growing craze for platelet concentrates technology, the scientific literature reported controversial results regarding the beneficial effect of these preparations on tissue healing, especially for bone regeneration.
Considering all this information, the aim of our research was to developed a study model in order to gain more information about the biological effect of a platelet concentrate on both soft and hard tissue regeneration.
For this purpose, human adipose-derived stem cells (hASCs), human osteoblasts (hObs) and human dermal fibroblasts (hDFs) cultured in the presence of PRGF, were studied. Usually, cells used for human therapy are expanded in fetal bovine serum (FBS), but this way carries the risk of potential immunogenic residual bovine proteins exposure and possible contamination with infectious agents, likely generating immune responses in patients. Therefore, in this study, FBS was completely substituted by the platelet concentrate for the cells culture. Interestingly, PRGF never affected cell viability and, after a short adaptation period, both hASCs and hDFs grown in the presence of PRGF, increased their proliferation rate compared to standard culture condition, while hObs growth was evident only without any cell’s detachment. Furthermore, neither donor nor cell population effect on both cell viability and proliferation was observed. Regarding osteo-differentiation, alkaline phoshatase (ALP) activity was induced in both hASCs and hObs, with a peak at day 7 and 14, respectively.
In parallel, in order to elucidate the clinical benefit of platelet concentrates in hard tissue repair, the combination of a bone graft substitute with PRGF in enhancing a bone defect regeneration performed in a preclinical animal model, was also investigated. In particular, bilateral circular critical lesions were created in the proximal tibia of six New Zealand rabbits, for a total of 12 defects, filled with the bone substitute alone or in association with PRGF. Untreated defects were also included as control. No side-effects have been observed during the 8 weeks follow-up. Both histological and histomorphometric analysis showed a non-significant difference between treatment groups in terms of bone density, even if the addition of PRGF to the bone substitute seemed to induce a higher percentage of newly formed bone.
In conclusion, this in vitro and in vivo study provided the evidence of the beneficial effect of platelet concentrates in both soft and hard tissue regeneration, thus supporting the application of this technology in clinical regenerative therapies
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
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
Pikaia: a new way to inform on evolution in Italy
No full textThe case study of the scientific web site "Pikaia": communicating science and evolution online
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
- …
