Mechanical properties of a biodegradable self-expandable polydioxanone monofilament stent: In vitro force relaxation and its clinical relevance

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.

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Anti-Inflammatory Properties of Injectable Betamethasone-Loaded Tyramine-Modified Gellan Gum/Silk Fibroin Hydrogels

Biomolecules ◽

10.3390/biom10101456 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1456

Author(s):

Isabel Matos Oliveira ◽

Cristiana Gonçalves ◽

Myeong Eun Shin ◽

Sumi Lee ◽

Rui Luis Reis ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Mechanical Properties ◽

Silk Fibroin ◽

Therapeutic Efficacy ◽

Composite Structures ◽

Gelation Time ◽

Polymeric Materials ◽

Gellan Gum ◽

Traditional Use

Rheumatoid arthritis is a rheumatic disease for which a healing treatment does not presently exist. Silk fibroin has been extensively studied for use in drug delivery systems due to its uniqueness, versatility and strong clinical track record in medicine. However, in general, natural polymeric materials are not mechanically stable enough, and have high rates of biodegradation. Thus, synthetic materials such as gellan gum can be used to produce composite structures with biological signals to promote tissue-specific interactions while providing the desired mechanical properties. In this work, we aimed to produce hydrogels of tyramine-modified gellan gum with silk fibroin (Ty–GG/SF) via horseradish peroxidase (HRP), with encapsulated betamethasone, to improve the biocompatibility and mechanical properties, and further increase therapeutic efficacy to treat rheumatoid arthritis (RA). The Ty–GG/SF hydrogels presented a β-sheet secondary structure, with gelation time around 2–5 min, good resistance to enzymatic degradation, a suitable injectability profile, viscoelastic capacity with a significant solid component and a betamethasone-controlled release profile over time. In vitro studies showed that Ty–GG/SF hydrogels did not produce a deleterious effect on cellular metabolic activity, morphology or proliferation. Furthermore, Ty–GG/SF hydrogels with encapsulated betamethasone revealed greater therapeutic efficacy than the drug applied alone. Therefore, this strategy can provide an improvement in therapeutic efficacy when compared to the traditional use of drugs for the treatment of rheumatoid arthritis.

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Collagen fibril diameter distribution does not reflect changes in the mechanical properties of in vitro stress-deprived tendons

Journal of Biomechanics ◽

10.1016/j.jbiomech.2004.03.035 ◽

2005 ◽

Vol 38 (1) ◽

pp. 69-75 ◽

Cited By ~ 65

Author(s):

Michael Lavagnino ◽

Steven P. Arnoczky ◽

Katherine Frank ◽

Tao Tian

Keyword(s):

Mechanical Properties ◽

Collagen Fibril ◽

Diameter Distribution ◽

In Vitro Stress ◽

Fibril Diameter

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Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

Coatings ◽

10.3390/coatings11050505 ◽

2021 ◽

Vol 11 (5) ◽

pp. 505

Author(s):

Krzysztof Aniołek ◽

Bożena Łosiewicz ◽

Julian Kubisztal ◽

Patrycja Osak ◽

Agnieszka Stróż ◽

...

Keyword(s):

Mechanical Properties ◽

Corrosion Resistance ◽

Contact Potential Difference ◽

Isothermal Oxidation ◽

Potential Method ◽

Open Circuit ◽

Kelvin Probe ◽

Contact Potential ◽

Oxide Layers

Titanium and its alloys are among the most promising biomaterials for medical applications. In this work, the isothermal oxidation of Ti-6Al-7Nb biomedical alloy towards improving its mechanical properties, corrosion resistance, and bioactivity has been developed. The oxide layers were formed at 600, 700, and 800 °C for 72 h. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), 3D profilometry, and microindentation test, were used to characterize microstructure, surface geometrical structure, and the hardness of the diphase (α + β) Ti-6Al-7Nb alloy after oxidation, respectively. In vitro corrosion resistance tests were carried out in a saline solution at 37 °C using the open-circuit potential method and potentiodynamic measurements. Electronic properties in the air were studied using the Scanning Kelvin Probe (SKP) technique. The bioactivity test was conducted by soaking the alkali- and heat-treated samples in simulated body fluid for 7 days. The presence of apatite was confirmed using SEM/EDS and Fourier Transform Infrared Spectroscopy (FTIR) studies. The thickness of oxide layers formed increased with the temperature growth from 0.25 to 5.48 µm. It was found that with increasing isothermal oxidation temperature, the surface roughness, hardness, corrosion resistance, and contact potential difference increased. The Ti-6Al-7Nb alloy after oxidation revealed the HAp-forming ability in a biological environment.

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Development of Biopolymeric Hybrid Scaffold-Based on AAc/GO/nHAp/TiO2 Nanocomposite for Bone Tissue Engineering: In-Vitro Analysis

Nanomaterials ◽

10.3390/nano11051319 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1319

Author(s):

Muhammad Umar Aslam Khan ◽

Wafa Shamsan Al-Arjan ◽

Mona Saad Binkadem ◽

Hassan Mehboob ◽

Adnan Haider ◽

...

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

Bone Tissue Engineering ◽

Bone Tissue ◽

Guar Gum ◽

Porous Scaffolds ◽

Vitro Assay ◽

Vitro Analysis ◽

Nanocomposite Scaffolds

Bone tissue engineering is an advanced field for treatment of fractured bones to restore/regulate biological functions. Biopolymeric/bioceramic-based hybrid nanocomposite scaffolds are potential biomaterials for bone tissue because of biodegradable and biocompatible characteristics. We report synthesis of nanocomposite based on acrylic acid (AAc)/guar gum (GG), nano-hydroxyapatite (HAp NPs), titanium nanoparticles (TiO2 NPs), and optimum graphene oxide (GO) amount via free radical polymerization method. Porous scaffolds were fabricated through freeze-drying technique and coated with silver sulphadiazine. Different techniques were used to investigate functional group, crystal structural properties, morphology/elemental properties, porosity, and mechanical properties of fabricated scaffolds. Results show that increasing amount of TiO2 in combination with optimized GO has improved physicochemical and microstructural properties, mechanical properties (compressive strength (2.96 to 13.31 MPa) and Young’s modulus (39.56 to 300.81 MPa)), and porous properties (pore size (256.11 to 107.42 μm) and porosity (79.97 to 44.32%)). After 150 min, silver sulfadiazine release was found to be ~94.1%. In vitro assay of scaffolds also exhibited promising results against mouse pre-osteoblast (MC3T3-E1) cell lines. Hence, these fabricated scaffolds would be potential biomaterials for bone tissue engineering in biomedical engineering.

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Goldmann Tonometry and Corneal Biomechanics

Applied Sciences ◽

10.3390/app11094025 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4025

Author(s):

Dario Messenio ◽

Marco Ferroni ◽

Federica Boschetti

Keyword(s):

Mechanical Properties ◽

Anterior Chamber ◽

Pressure Transducer ◽

Pearson Correlation ◽

Corneal Thickness ◽

Applanation Tonometry ◽

In Vitro Tests ◽

Goldmann Tonometry ◽

The Difference

Glaucoma is the second cause of irreversible blindness in the world. Intraocular pressure (IOP) is a recognized major risk factor for the development and progression of glaucomatous damage. Goldmann applanation tonometry (GAT) is internationally accepted as the gold standard for the measurement of IOP. The purpose of this study was to search for correlations between Goldmann tonometry and corneal mechanical properties and thickness by means of in vitro tests. IOP was measured by the Goldmann applanation tonometer (GIOP), and by a pressure transducer inserted in the anterior chamber of the eye (TIOP), at increasing pressure levels by addition of saline solution in the anterior chamber of enucleated pig eyes (n = 49). Mechanical properties were also determined by inflation tests. The GAT underestimated the real measurements made by the pressure transducer, with most common differences in the range 15–28 mmHg. The difference between the two instruments, highlighted by the Bland–Altman test, was confirmed by ANOVA, normality tests, and Mann–Whitney’s tests, both on the data arranged for infusions and for the data organized by pressure ranges. Pearson correlation tests revealed a negative correlation between (TIOP-GIOP) and both corneal stiffness and corneal thickness. In conclusion, data obtained showed a discrepancy between GIOP and TIOP more evident for softer and thinner corneas, that is very important for glaucoma detection.

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Homozygous MTAP deletion in primary human glioblastoma is not associated with elevation of methylthioadenosine

Nature Communications ◽

10.1038/s41467-021-24240-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yasaman Barekatain ◽

Jeffrey J. Ackroyd ◽

Victoria C. Yan ◽

Sunada Khadka ◽

Lin Wang ◽

...

Keyword(s):

Clinical Relevance ◽

Homozygous Deletion ◽

In Vitro Models ◽

Arginine Methyltransferase ◽

Human Glioblastoma ◽

Primary Glioblastoma ◽

Methylthioadenosine Phosphorylase ◽

Metabolomic Profiling

AbstractHomozygous deletion of methylthioadenosine phosphorylase (MTAP) in cancers such as glioblastoma represents a potentially targetable vulnerability. Homozygous MTAP-deleted cell lines in culture show elevation of MTAP’s substrate metabolite, methylthioadenosine (MTA). High levels of MTA inhibit protein arginine methyltransferase 5 (PRMT5), which sensitizes MTAP-deleted cells to PRMT5 and methionine adenosyltransferase 2A (MAT2A) inhibition. While this concept has been extensively corroborated in vitro, the clinical relevance relies on exhibiting significant MTA accumulation in human glioblastoma. In this work, using comprehensive metabolomic profiling, we show that MTA secreted by MTAP-deleted cells in vitro results in high levels of extracellular MTA. We further demonstrate that homozygous MTAP-deleted primary glioblastoma tumors do not significantly accumulate MTA in vivo due to metabolism of MTA by MTAP-expressing stroma. These findings highlight metabolic discrepancies between in vitro models and primary human tumors that must be considered when developing strategies for precision therapies targeting glioblastoma with homozygous MTAP deletion.

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