1,720,970 research outputs found
BMP-2 and type I collagen preservation in human deciduous teeth after demineralization
Full text linkBackground:
Great interest has recently been focused on tooth and tooth derivatives as suitable substrates for the treatment of alveolar bone defects. Here, we propose the use of demineralized baby teeth (BT) as potential grafting materials for bone augmentation procedures.
Methods:
Particles of human BT (Ø < 1 mm) were demineralized by means of a chemical/thermal treatment. Demineralized BT particles were thoroughly characterized by scanning electron microscopy/energy dispersive X-ray analyses to evaluate the effects of the demineralization on BT topography and mineral phase composition, and by enzyme-linked immunosorbent assays (ELISA) to quantify collagen and bone morphogenetic protein-2 (BMP-2) protein contents. The response of SAOS-2 cells to exogenous BMP-2 stimulation was evaluated to identify the minimum BMP-2 concentration able to induce osteodifferentiation in vitro (alkaline phosphatase (ALP) activity).
Results:
The demineralization treatment led to a dramatic decrease in relative Ca and P content (%) of ≈75% with respect to the native BT particles, while preserving native protein conformation and activity. Interestingly, the demineralization process led to a rise in the bioavailability of BMP-2 in BT particles, as compared to the untreated counterparts. The BMP-2 content found in demineralized BT was also proved to be very effective in enhancing ALP activity, thus in the osteodifferentiation of SAOS-2 cells in vitro, as confirmed by cell experiments performed upon exogenously added BMP-2.
Conclusions:
In this study we demonstrate that the BMP-2 content found in demineralized BT is very effective in inducing cell osteodifferentiation, and strengthens the idea that BTs are very attractive bioactive materials for bone-grafting procedures
Developing of a photocatalytic filter for the control of the indoor air quality
No full textBackground: The aim of this work was the development and characterization of a photocatalytic filter for the
treatment of indoor air, characterized by a low pressure drop.
Methods: The filter (photocatalytic filter) was based on a polyester substrate additivated with active carbon
(Carbotex 150-6), treated with a sol of titanium dioxide (Sol 121-AB; NextMaterials Ltd.) and illuminated with UV
LEDs to induce photocatalytic activity.
Results: Tests showed that this filter, used in a suitable device for air circulation with a very low noise level, had
the ability to block solid particulates, to photocatalytically oxidize a major fraction of volatile organic compounds
(VOCs) and deactivate all of the bacteria blocked on the filter, in contrast to traditional commercial air filters on
which the bacteria remain viable.
Conclusions: Activated charcoal filters treated with TiO2 and illuminated by UV LEDs were found to be extremely
effective in killing bacteria and effective in decreasing VOC and total suspended particulates (TSP
Processo di riduzione della carica microbica di materiale cartaceo e inibizione del processo di proliferazione dei microorganismi in seguito a nuova esposizione
No full textRGD-derivatized PEI-PEG copolymers: Influence of the degree of substitution on the targeting behavior
No full textPEGylation is widely used to improve the stability of gene delivery vectors through the decrease of non-specific binding to serum proteins. In order to provide “stealth” vectors with targeting properties, the grafting of specific ligands is mandatory. For instance, the tripeptide arginine-glycine-aspartic acid (RGD) has been shown to confer selectivity towards some integrin-overexpressing tumor cells. Unfortunately, owing to the different RGD grafting degrees, some difference in starting materials and experimental conditions, the literature displays contradictory findings about the efficacy of this strategy.
Starting from branched poly(ethylene imine) (bPEI) transfectant and the heterobifunctional linker N-hydroxy-succinimide-poly(ethylene glycol)-maleimide, a series of variably substituted PEI-PEGs were synthesized and functionalized with linear and cyclic RGDs. bPEI-PEG-RGDs were as effective as bPEI in complexing DNA while derivatization did affect the physicochemical properties of polyplexes. A degree of substitution of 1.31% led to enhanced targeting of cognate receptor-expressing cells without impairing the transfection efficiency of bPEI, even in the presence of serum. Of note, both RGDs were equally effective to confer selectivity to polyplexes.
These results highlight the key role of the degree of substitution on the effectiveness and selectivity of bPEI-PEG-RGDs, suggesting that a systematic approach is needed for the development of more effective targeted transfectants
Demineralized dentin and enamel matrices as suitable substrates for bone regeneration
Full text linkBackground: In recent decades, tooth derivatives such as dentin (D) and enamel (E) have been considered as potential graft biomaterials to treat bone defects. This study aimed to investigate the effects of demineralization on the physical-chemical and biological behavior of D and E. Methods: Human D and E were minced into particles (à <1 mm), demineralized and sterilized. Thorough physicalchemical and biochemical characterizations of native and demineralized materials were performed by SEM and EDS analysis and ELISA kits to determine mineral, collagen type I and BMP-2 contents. In addition, MG63 and SAOS-2 cells were seeded on tooth-derived materials and Bio-Oss®, and a comparison of cell responses in terms of adhesion and proliferation was carried out. Results: The sterilization process, as a combination of chemical and thermal treatments, was found to be effective for all materials. On the other hand, D demineralization allowed preserving the collagen content, while increasing BMP-2 bioavailability. D and demineralized D (dD) displayed excellent biocompatibility, even greater than Bio-Oss®. Conversely, the high mineral content displayed by E, as confirmed by EDS analysis, inhibited cell proliferation. Of note, even though the demineralization process was somehow less effective in E than in D, demineralized E (dE) displayed increased BMP-2 bioavailability and improved performance in vitro compared with native E. Conclusions: Our results substantiate the idea that the demineralization process lead to an increase of BMP-2 bioavailability, thus paving the way toward development of more effective, osteoinductive tooth-derived materials for bone regeneration and replacement
Three-dimensional printing of chemically crosslinked gelatin hydrogels for adipose tissue engineering
No full textDespite their outstanding potential and the success that has already been achieved with three-dimensional (3D) printed hydrogel scaffolds, there has been little investigation into their application in the regeneration of damaged or missing adipose tissue (AT). Due to their macroscopic shape, microarchitecture, extracellular matrix-mimicking structure, degradability and soft tissue biomimetic mechanical properties, 3D printed hydrogel scaffolds have great potential for use in aesthetic, structural and functional restoration of AT. Here, we propose a simple and cost-effective 3D printing strategy using gelatin-based ink to fabricate scaffolds suitable for AT engineering. The ink, successfully printed here for the first time, was prepared by mixing gelatin and methylenebisacrylamide (a crosslinker) to initiate the crosslinking reaction. The solution was then loaded into the cartridge (temperature T = 35 °C) of a pneumatic extrusion-based 3D printer and printed on a cooled surface (T = 4 °C) in the appropriate time window for ink printability as verified by rheological tests. Subsequently, the printed gelatin hydrogels were crosslinked at different temperatures to optimize their stability and fix the printed structure. The gelatin scaffolds crosslinked at 20 °C remained stable for 21 days at physiological temperature, with compressive mechanical properties mimicking those of AT (i.e. elastic modulus = 20 kPa). The 3D printed scaffolds showed no indirect cytotoxic effects on a 3T3-L1 pre-adipocyte cell line. Moreover, the printed scaffolds successfully promoted adhesion and proliferation of primary human pre-adipocytes, as demonstrated by LIVE/DEAD staining and Alamar Blue assay. The differentiation of primary human pre-adipocytes isolated from three different donors according to adipogenic phenotype was demonstrated by an increase in PPARγ gene expression detected by real-time PCR and accumulated lipid droplets stained by Oil Red O, thus proving the potential of the 3D printed gelatin hydrogels as scaffolds for AT engineering
N-Hydroxyphthalimide catalysts as bioactive pro-oxidants
No full textThe catalytic role of N-hydroxyphthalimide (NHPI) in promoting free-radical hydrogen atom transfer (HAT) reactions, well-documented for processes of industrial and synthetic interest, is here investigated for the first time in a biological environment. While NHPI by itself did not show any bioactivity, selected NHPI-derivatives (NHPIDs) revealed the ability to activate the intracellular formation of reactive oxygen species (ROS), causing the depletion of glutathione (GSH) levels and an increase in oxidative stress (OS). The evident bioactivity of some of these derivatives resulted in a significant reduction of the viability in osteosarcoma MG-63, suggesting a new, potential role of NHPIDs as pro-oxidant drugs. The key role of the N–OH group in promoting oxidative stress is demonstrated
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
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