1,720,974 research outputs found
Influence of hyaluronic acid on extracellular matrix produced by mesenchymal stem cells
No full textHyaluronic acid is a natural component of the extracellular matrix found in various body fluids, organs and tissues. It is widely used in tissue engineering, as a drug delivery system and in various medical and pharmaceutical applications. It plays an important role in supporting cells during wound healing, recognizing specific surface receptors during the healing process, and favoring collagen deposition and angiogenesis. Hyaluronic acid is known to activate stem cells and is involved during the differentiation process. Nevertheless, it was demonstrated as hyaluronic acid’s biological functions and properties are strictly dependent on its molecular weight, also showing opposite effects between high-molecular- weight and low-molecular-weight. Here we tested the effects of hyaluronic acid with different molecular weights on mesenchymal stem cells, assessing the role of this natural linear polysaccharide in extracellular matrix deposition and remodeling. Gene expression of genes belonging to the “Extracellular Matrix and Adhesion Molecules” pathway was investigated in mesenchymal stem cells treated with high, medium, and low molecular weight hyaluronic acid solution 10 mg/ml for 24 h. Hyaluronic acid promotes the synthesis and stabilization of the extracellular matrix. Furthermore, treated cells respond to the treatment by opposing the inflammatory action of the molecule by down-regulating numerous metalloproteinases, thus trying to stop the degeneration processes of the extracellular matrix
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
SIMPLICITY AND RELIABILITY OF INVISALIGN® SYSTEM
No full textInvisalign® system is an orthodontic treatment method in which removable, clear, semi-elastic polyurethane aligners are used to correct malocclusions. Invisalign® therapy corrects tooth malposition by a series of removable transparent polyurethane splints (aligners) that covering all the teeth plus the marginal aspects of the gingiva, which gradually move the teeth into an ideal position. Here a case series of patients treated with Invisalign® is performed to verify the efficiency, effectiveness, and stability of treatment. Twenty patients (15 females and 5 males, median age 35.6 ± 13.5 years, min 11, max 59 years) affected by malocclusion were enrolled in this retrospective study. There were seven skeletal class 1, twelve skeletal class 2 and one skelatal class 3 malocclusion, 1 lateral cross-bite, 13 deep-bite and 4 open-bite. Lateral teleradiographic projections of the cranium were used. The cephalometric analysis was performed by using Dolphin system on pre-treatment and final control radiographies. Several variables related to teeth position were investigated. Pearson Chi Square was used to detect statistical differences among studied variables. In the present study we demonstrated that Invisalign® is an effectiveness tool to reach good clinical results since most of the studied variables (i.e. teeth position) have statistically significant differences between pre and post-treatment radiographie
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
Reconstruction of severely atrophic jaws using homografts and simultaneous implant placement: a retrospective study
No full textIn the past decade, several investigators have reported that implants inserted in autografts in the same operation (ie, simultaneously inserted implants [SIIs]) have achieved excellent results. However, no report regarding SIIs placed in fresh frozen bone (FFB) is available. Thus, the authors planned a retrospective study on a series of SIIs placed in homologue FFB (but not immediately loaded) to evaluate their clinical outcome. In addition, a comparison with implants inserted in FFB in a second stage (ie, delayed inserted implants) was performed. Seventeen patients were grafted with FFB, and 48 implants were inserted in the same operation. Implant diameter and length ranged from 3.25 to 4.0 mm and from 10.0 to 15 mm, respectively. Data were compared with 302 implants inserted in FFB in a second operation during the same period in 64 patients. Analyzing SIIs, it was noted that only 3 implants were lost (ie, survival rate [SVR] = 93.7\%), and no differences were detected among the studied variables by using lost implants as a predictor of clinical outcome. On the contrary, by using crestal bone resorption around the implant's neck and specific cutoff values, it was possible to demonstrate that prosthetic restoration (ie, removable overdentures) correlated with a statistically significant lower delta insertion abutment junction (ie, reduced crestal bone loss) and thus with a better clinical outcome. By comparing SIIs with implants inserted in a second stage in FFB, a better outcome for delayed implants was demonstrated. Implants inserted simultaneously with FFB grafts had a high survival and success rate. SIIs inserted in FFB can be considered reliable devices, although a higher marginal bone loss is to be expected when fixed prosthetic restorations are used. Implants inserted in a second surgical stage have a better SVR and success rate than SIIs
Role of Antioxidants in Dermal Aging: An In Vitro Study by q-RT-PCR
No full textBACKGROUND:
Reactive oxygen species production is the final step in skin aging. These unstable molecules can damage and destroy DNA, proteins, and membrane phospholipids. The aim of this study was to test the in vitro effect of an antioxidant precursor, N-acetylcysteine (NAC), on human dermal fibroblasts. NAC alone and a solution of NAC and amino acids together, used in aesthetic medicine as intradermal injection treatment, were tested.
METHODS:
The expression levels of some connective related genes (HAS1, HYAL1, ELN, ELANE, DSP, GDF6, and IGF1) were analyzed on cultures of dermal fibroblasts using real-time reverse-transcription polymerase chain reaction (real time RT-PCR).
RESULTS:
All genes were upregulated after 24 h of treatment.
CONCLUSIONS:
An interesting effect of gene induction by administration of NAC and amino acids in vitro was demonstrated. Upregulation of elastin-, hyaluronic acid-, and GDF6-encoding genes supports the evidence of clinical improvement induced by NAC biostimulation in the prevention and correction of skin aging.
NO LEVEL ASSIGNED:
This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/0026
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