1,720,970 research outputs found
Hormonal control of subcutaneous adipose tissue aquaglyceroporins
No full textGlycerol metabolism in normal condition and in metabolic disorders like type-2 diabetes and obesity could depend at least in part on the transmembrane transport mechanisms of glycerol. Aquaglyceroporins (AQPs) are integral membrane protein belonging to the water channel proteins family (aquaporins) that are permeable to glycerol as well as water. Adipose tissue, the main source of plasma glycerol, expresses high levels of AQP7 but also AQP3, 9, 10. Recently, in adipose tissue was also found AQP11, whose permeability to glycerol is uncertain. However, the hormonal regulation of AQPs in the adipose tissue is not completely characterized. To this purpose we evaluated the effect of insulin, isoproterenol, thyroxin, dexamethasone in human isolated adipose tissue by real time RT-PCR. Immunocytochemistry was also performed to define the localization of the AQPs. Results showed that all the AQPs investigated are expressed in the human subcutaneous adipose tissue with a localization of AQP3,7 and 10 in both plasma membranes and in lipid droplets membranes, AQP9 mainly in the plasma membrane and AQP11 in the lipid droplets membrane. Generally, lipolytic and lipogenic stimuli differently affected the AQPs expression which depicts a complex situation involving, probably, different signaling pathway. These results and other recently described by the literature seem support the existence of different AQPs that under hormonal control and in pathological conditions can modify their expression levels and cellular localization, suggesting them as potential therapeutic targets in obesity and metabolic syndrome
ENDOTHELIAL PROGENITOR CELL ADHESION, GROWTH AND CHARACTERIZATION ON TRABECULAR TITANIUM AND TRABECULAR TITANIUM COATED WITH COLLAGEN OR DECELLULARIZED ECM
Full text linkAdequate blood supply is essential for prosthesis osteointegration and bone healing as it supplies oxygen, nutrition and progenitor cells. The bone healing process and vascularization depend upon the endothelial cells, which speed up implant osteointegration. Endothelial Progenitor Cells (EPC) are a population of stem cells that can reproduce, migrate and acquire mature endothelial phenotype. Their recruitment occurs in the tissue lesion to enhance neovascularization. Trabecular TitaniumTM (TTTM) is a new biomaterial with very interesting biomechanical characteristics and fast osteointegration. This study has investigated adhesion, proliferation and characteristics of EPC on three types of biomaterial: unmodified trabecular titanium, trabecular titanium coated with the ECM deposited by human mesenchymal stem cells isolated from subcutaneous adipose tissue and decellularized and trabecular titanium coated with type I collagen (control scaffold). MTT assay showed similar percentages of EPCs seeded on the different kinds of scaffold: 67% on TT, 70% on decellularized scaffolds and 82% on collagen-coated scaffolds. There were no statistically significant differences between the three groups. We therefore conclude that TTTM allows EPC adhesion and proliferation and, consequently, by permitting vascularization, it favours prosthesis osteointegration
Double-tapered conical taper in primary and revision surgery: rationale and short-term follow-up(Article)
No full textBackground: The new double-conical tapered stem is a novel cementless modular system, which is indicated for both primary and revision surgeries. It has been designed with different angles at the proximal (5°) and distal sections (1° 36’) in order to obtain optimal fixation by proximal and distal fit and fill of the femoral canal. Aim: The aim of this prospective study was to evaluate the short-term clinical and radiographic outcomes of primary and revision hip surgery with the new double-conical stem. Methods: 61 stems were implanted (December 2013 to September 2016) in 42 cases of primary and in 19 cases of revision surgery. The mean age of patients was 64.7 (17–94; standard deviation [SD] 21.9) years. Results: The mean body mass index of the patients was 24.6 (17–34.6). In 3 cases of developmental dysplasia of the hip we performed femoral shortening osteotomy. The mean follow-up was 26 (8–40) months. 3 patients died due to causes unrelated to surgery. Postoperative complications included 3 hip dislocations, 2 infections and 1 case of stem explant for metastatic tumour. For all other cases, at the last follow-up radiographs showed no loosening, no radiolucent lines nor subsidence. The mean Harris Hip Score significantly improved from 45 (range 35–58) preoperatively to 87 (range 75–94). Leg length discrepancy was found in 10% of cases but never >1 cm. Conclusions: Radiographic analysis showed the bone-stem contact full at 2 levels of taper. The double-tapered prosthetic stem can therefore be usefully employed both in primary and in revision surgeries
Effect of hydroxyapatite and pulsed electromagnetic field on osteogenic differentiation of human stem cells seeded onto 3D-printed polycaprolactone scaffolds for future bone graft transplantation
No full textBone graft transplantation is a risky procedure mainly due to postoperative complications. Tissue engineering is an alternative to regenerating bone tissue by seeding mesenchymal stem cells into 3D scaffolds by osteoinductive signaling. Poly(ε-caprolactone) (PCL) is one of the most used biopolymers for fabricating scaffolds for bone tissue engineering. PCL is enriched with hydroxyapatite (HA) to promote the production of the bone-mineralized matrix. Moreover, the application of pulsed electromagnetic fields (PEMFs) on scaffolds loaded with HA can significantly benefit collagen and HA networks favoring the interaction between organic and mineral phases of bones. In this context, we investigated, for the first time, the effect exerted by a PEMF exposure on the osteogenic differentiation of human adipose stem cells (hASCs) seeded onto 3D printed PCL-HA scaffolds and cultured in growth and osteogenic medium (OM). After 21 days of culture, the results showed excellent colonization of scaffolds and the deposition of extracellular matrix (ECM) secreted by hASCs. Immunofluorescence staining confirmed the deposition of collagen type I and osteopontin both on scaffolds. Gene expression analysis indicated that both HA crystal and PEMF treatment were able to trigger osteogenic differentiation, as documented by the increase of osteogenic markers. These results suggest that HA, osteogenic factors, and PEMFs converge on the same signaling pathways as there are no additive effects and no change in protein synthesis between scaffolds with HA or treated with PEMFs for cells cultured in OM. The proposed study lays the foundations for exploring new approaches in bone graft transplantation
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
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