1,721,081 research outputs found
Discussion: Protective Effect of Hydrogen Gas Inhalation on Muscular Damage Using a Mouse Hindlimb Ischemia-Reperfusion Injury Model
No full textTissue-mimicking gelatin scaffolds by alginate sacrificial templates for adipose tissue engineering
Get PDFWhen adipose tissue (AT) is impaired by trauma or disease, AT engineering could provide a shelf-ready structural and functional restoration as alternative to current clinical treatments, which mainly aim at aesthetic replacement. Yet, the lack of an efficient vascular network within the scaffolds represents a major limitation to their translation application in patients. Here, we propose the use of microstructured crosslinked gelatin hydrogels with an embedded prevascular channel as scaffolding materials for AT engineering. The scaffolds are fabricated using – simultaneously – alginate-based microbeads and 3D printed filaments as sacrificial material encapsulated in gelatin at the point of material fabrication and removed post-crosslinking. This method yields the formation of microstructures that resemble the micro-architecture of physiological human fat tissue and of microvessels that can facilitate vascularization through anastomosis with patients’ own blood vessels. The cytocompatible method used to prepare the gelatin scaffolds showed structural stability over time while allowing for cell infiltration and protease-based remodeling/degradation. Scaffolds’ mechanical properties were also designed to mimic the one of natural breast adipose tissue, a key parameter for AT regeneration. Scaffold's embedded channel (∅ = 300–400 μm) allowed for cell infiltration and enabled blood flow in vitro when an anastomosis with a rat blood artery was performed using surgical glue. In vitro tests with human mesenchymal stem cells (hMSC) showed colonization of the porous structure of the gelatin hydrogels, differentiation into adipocytes and accumulation of lipid droplets, as shown by Oil Red O staining. Statement of Significance: The potential clinical use of scaffolds for adipose tissue (AT) regeneration is currently limited by an unmet simultaneous achievement of adequate structural/morphological properties together with a promoted scaffold vascularization. Sacrificial materials, currently used either to obtain a tissue-mimicking structure or hollow channels to promote scaffold’ vascularization, are powerful versatile tools for the fabrication of scaffolds with desired features. However, an integrated approach by means of sacrificial templates aiming at simultaneously achieving an adequate AT-mimicking structure and hollow channels for vascularization is missing. Here, we prove the suitability of crosslinked gelatin scaffolds obtained by using sacrificial alginate microbeads and 3D printed strands to achieve proper features and hollow channels useful for scaffolds vascularization
Facial-nerve regeneration ability of a hybrid artificial nerve conduit containing uncultured adipose-derived stromal vascular fraction: An experimental study
No full textThis study investigated the potential of uncultured-stromal-vascular-fraction (SVF) cells in promoting facial nerve regeneration in a rat model
Developing evidence-based plastic surgery: the role of research registration, protocols and reporting quality
Get PDFBACKGROUND: Evidence-based medicine has had a profound impact on healthcare. In the field of Plastic surgery, powerful examples include; less radical skin cancer excision margins and skin-sparing or even nipple-sparing mastectomies and microsurgical reconstruction. Sustained progression of the field, relies on the development of a high-quality evidence base, with strong use of peer-reviewed research protocols, which are publicly registered and completed studies transparently reported. The extent of compliance with these principles is currently unknown and the author hypothesised that it would be low. The author further hypothesised that registration could be improved by the development of a new global research registry and reporting quality can be improved by the mandatory implementation of reporting guidelines in a journal.
METHODS: This thesis incorporated 11 studies. The first two studies used a literature review to determine; the levels of evidence, rates of study registration and protocol publication in the recent Plastic Surgery literature. Thirdly, the design, build and launch of a new global research registry to boost compliance with registration and to determine barriers to it using a survey amongst users. This would be followed by systematic reviews to determine compliance with the STROBE and PRISMA guidelines respectively. An analysis of each guide for authors (GFA) of the surgical journals listed in the Thomson Reuters journal citation report for surgery to determine support for reporting guidelines. The impact of the mandatory implementation of reporting guidelines in a surgical journal would be assessed using a before and after design. Finally, to develop a reporting guideline for surgical case reports (SCARE) and surgical case series (PROCESS) using a DELPHI consensus exercise amongst an expert panel.
RESULTS: Protocols were registered in 4% of 595 recent research studies and 0.5% were published. There was a mean compliance of 12/22 for the STROBE guideline (n=94) and 16/27 for the PRISMA guideline (n=79). The Research Registry® was launched in February 2015. Analysis of the first 500 previously unregistered studies, showed they came from 57 countries and included 1.77 million patients. Key barriers to registration were a lack of awareness of the need to register and lack of time (n=149). In addition, 45% registered their study at the time of journal submission. The GFA analysis showed 62% didnât mention reporting guidelines at all (n=193). Subsequent mandatory implementation in a single surgical journal, increased compliance with STROBE by 12% (n=152), with CONSORT by 40% (n=13) and with PRISMA by 58% (n=28). The SCARE and PROCESS reporting guidelines were developed and published in late 2016. According to Google Scholar, they have accumulated over 200 citations at the time of writing.
CONCLUSION: Study registration, protocol use and reporting quality are poor in plastic surgery. Potential solutions to these long-standing problems have been developed and explored within this thesis. These include the development and use of the Research Registry® and the mandatory implementation of reporting guidelines, with both measures front-loaded within a gatekeeper framework for journals. It is now for Plastic Surgeons and the wider surgical community to pick up the gauntlet and drive forward high-quality research, evidence-based surgical practice and better outcomes for their patients and society at large.</p
Skin Substitutes and Bioscaffolds: Temporary and Permanent Coverage
No full textAdvancements in surgical wound treatment have led to skin substitutes and bioscaffolds as temporary and permanent coverage for burn wounds. Skin substitutes are used to improve wound coverage and restore the functional and aesthetic qualities of skin, and help to prevent wound infection and maintain a moist wound healing environment. Although allografts are preferred when autografts are not possible, high costs and limited availability have led to the use of xenografts and the development of skin substitutes and bioscaffolds. Despite constant evolution in the development of these skin substitutes and bioscaffolds, no single product stands out as the gold standard
Adipose-derived aldehyde dehydrogenase-expressing cells promote dermal regenerative potential with collagen-glycosaminoglycan scaffold
No full textAldehyde dehydrogenase (ALDH) is an enzyme that plays an important role in retinoid metabolism and highly expressed in stem cells. This study isolated ALDH-expressing cells from subcutaneous adipose tissue and investigated their potential to enhance healing in a full-thickness skin wound in rats by co-implanting them with collagen-glycosaminoglycan (c-GAG) scaffolds. ALDH-positive cells were isolated by a fluorescence-activated cell sorting technique from Lewis rat's stromal-vascular-fraction (SVF) and transplanted with c-GAG scaffolds in a rat full-thickness skin wound model. At 7 days after surgery, the microscopic appearance of c-GAG scaffolds seeded with ALDH-positive was compared with those of uncultured-SVF, and cultured-SVF adipose-derived stromal cells (ASCs). The thickness of cellular ingrowth in the ASC group (630 ± 180 μm) was significantly thicker than that in the control (390 ± 120 μm) or SVF (380 ± 140 μm) groups, but non-significantly thicker than that in the ALDH-positive group (570 ± 220 μm). The thickness of regenerated collagen layer was significantly thicker in the ALDH-positive group (160 ± 110 μm) than in the ASCs (81 ± 41 μm), the control (65 ± 24 μm), or SVF (64 ± 34 μm) groups. Immunofluorescent staining with CD31 proved that transplanted ALDH-positive cells differentiated into vascular endothelial cells in c-GAG scaffolds. Combined transplantation with c-GAG scaffolds and adipose-derived ALDH-positive cells promoted dermal regeneration, giving a possibility that ALDH-positive cells would greatly shorten the waiting period before secondary autologous skin grafting was possible
Injectable Shape-Memorizing Three-Dimensional Hyaluronic Acid Cryogels for Skin Sculpting and Soft Tissue Reconstruction
Get PDFHyaluronic acid (HA)-based fillers are used for various cosmetic procedures. However, due to filler migration and degradation, reinjections of the fillers are often required. Methacrylated HA (MA-HA) can be made into injectable shape-memorizing fillers (three-dimensional [3D] MA-HA) aimed to address these issues. In this study, shape retention, firmness, and biocompatibility of 3D MA-HA injected subcutaneously in mice were evaluated
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
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
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