Improved understanding of skin elasticity by modelling in vivo mechanical tests

2002 ◽  
pp. 321-323
Author(s):  
A Sirvent ◽  
M Randeau ◽  
C Kurdian ◽  
B Closs ◽  
F Girard
Keyword(s):  
Mechanical Tests ◽  
Skin Elasticity

scholarly journals Multimodal investigation of a keloid scar by combining mechanical tests in vivo with diverse imaging techniques

2019 ◽  
Vol 99 ◽  
pp. 206-215 ◽  
Author(s):  
Jérôme Chambert ◽  
Thomas Lihoreau ◽  
Sylvain Joly ◽  
Brice Chatelain ◽  
Patrick Sandoz ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Mechanical Tests ◽  
Keloid Scar

scholarly journals Biomimetic gradient scaffold of collagen–hydroxyapatite for osteochondral regeneration

2020 ◽  
Vol 11 ◽  
pp. 204173141989606 ◽  
Author(s):  
Cristian Parisi ◽  
Luca Salvatore ◽  
Lorenzo Veschini ◽  
Maria Paola Serra ◽  
Carl Hobbs ◽  
...  
Keyword(s):  
Biological Properties ◽  
Biological Evaluation ◽  
Mechanical Tests ◽  
Host Cells ◽  
Smooth Transition ◽  
Treatment Modalities ◽  
Chemical Compositions ◽  
Osteochondral Defects

Osteochondral defects remain a major clinical challenge mainly due to the combined damage to the articular cartilage and the underlying bone, and the interface between the two tissues having very different properties. Current treatment modalities have several limitations and drawbacks, with limited capacity of restoration; however, tissue engineering shows promise in improving the clinical outcomes of osteochondral defects. In this study, a novel gradient scaffold has been fabricated, implementing a gradient structure in the design to mimic the anatomical, biological and physicochemical properties of bone and cartilage as closely as possible. Compared with the commonly studied multi-layer scaffolds, the gradient scaffold has the potential to induce a smooth transition between cartilage and bone and avoid any instability at the interface, mimicking the natural structure of the osteochondral tissue. The scaffold comprises a collagen matrix with a gradient distribution of low-crystalline hydroxyapatite particles. Physicochemical analyses confirmed phase and chemical compositions of the gradient scaffold and the distribution of the mineral phase along the gradient scaffold. Mechanical tests confirmed the gradient of stiffness throughout the scaffold, according to its mineral content. The gradient scaffold exhibited good biological performances both in vitro and in vivo. Biological evaluation of the scaffold, in combination with human bone-marrow–derived mesenchymal stem cells, demonstrated that the gradient of composition and stiffness preferentially increased cell proliferation in different sub-regions of the scaffold, according to their high chondrogenic or osteogenic characteristics. The in vivo biocompatibility of the gradient scaffold was confirmed by its subcutaneous implantation in rats. The gradient scaffold was significantly colonised by host cells and minimal foreign body reaction was observed. The scaffold’s favourable chemical, physical and biological properties demonstrated that it has good potential as an engineered osteochondral analogue for the regeneration of damaged tissue.

Determination of Layer and Region Specific Mechanical Properties of Intraluminal Thrombus (ILT): The Importance of Biaxial Tensile Testing

2013 ◽  
Author(s):  
S. O’Leary ◽  
E. Kavanagh ◽  
P. Grace ◽  
T. McGloughlin ◽  
B. Doyle
Keyword(s):  
Mechanical Properties ◽  
Endovascular Aneurysm Repair ◽  
Distal Region ◽  
Mechanical Tests ◽  
Biaxial Test ◽  
Clinical Tool ◽  
Intraluminal Thrombus ◽  
Element Analysis ◽  
Aneurysm Wall

Abdominal Aortic Aneurysm (AAA) is the gradual and irreversible local widening of the distal region of the aorta. If undetected or untreated the intramural stress can exceed the strength of the aneurysm wall causing the structure to rupture. Upon rupture, AAA has a 90% mortality rate. It has been hypothesized, and shown in some studies, that regions of elevated stress of the AAA wall may be linked to sites of AAA rupture. In order for Finite Element Analysis (FEA) to be successfully used as a clinical tool, to aid in AAA rupture prediction, it is crucial that the mechanics of both the AAA wall and intraluminal thrombus (ILT) are described accurately. At present it is unclear whether ILT increases or decreases the rupture risk of AAA. This may be due to the lack of available data which can accurately describe its behaviour in vivo. A recent review of AAA mechanics explains how ‘there have been limited studies on the mechanical properties of intraluminal thrombus’. Due to the recent popularity of endovascular aneurysm repair (EVAR) the opportunities to harvest and conduct mechanical tests on this tissue are rare. This study aims to further characterize ILT using both uniaxial and biaxial test methods and where possible determine the layer and region specific mechanical properties of this material.

Perfluoropolyether phosphate: skin exfoliation after a topical pre-treatment, TEWL and skin elasticity, by in-vivo non-invasive methods

2007 ◽  
Vol 29 (5) ◽  
pp. 391-398 ◽  
Author(s):  
C. Ostacolo ◽  
A. Sacchi ◽  
A. Bernardi ◽  
S. Laneri ◽  
A. Brunetta ◽  
...  
Keyword(s):  
Skin Elasticity ◽  
Non Invasive ◽  
Pre Treatment

In Vivo Evaluation of Porous Titanium Implants with Biomimetic Coating

2008 ◽  
Vol 396-398 ◽  
pp. 179-182 ◽  
Author(s):  
Ana Cristina P. Machado ◽  
Marize Varella de Oliveira ◽  
Robson Pacheco Pereira ◽  
Yasmin R. Carvalho ◽  
Carlos Alberto Alves Cairo
Keyword(s):  
Porous Titanium ◽  
Mechanical Tests ◽  
Titanium Implants ◽  
Powder Metallurgy Method ◽  
Bone Implant ◽  
X Ray ◽  
Biomimetic Coating ◽  
Left And Right ◽  
The Mean

The osseointegration of porous titanium implants was evaluated in the present work. Implants were fabricated from ASTM grade 2 titanium by a powder metallurgy method. Part of these implants were submitted to chemical and thermal treatment in order to deposit a biomimetic coating, aiming to evaluate its influence on the osseointegration of the implants. The implants were characterized by Scanning Electron Microscopy (SEM), Electron Dispersive X-Ray Spectroscopy (EDS) and Raman Spectroscopy. Three coated and three control (uncoated) implants were surgically inserted into thirty albino rabbits’ left and right tibiae, respectively. Tibiae samples were submitted to histological and histomorphometric analyses, utilizing SEM, optical microscopy and mechanical tests. EDS results indicated calcium (Ca) and phosphorous (P) at the surface and Raman spectra exhibited an intense peak, characteristic of hydroxyapatite (HA). Bone neoformation was detected at the bone-implant interface and inside the pores, including the central ones. The mean bone neoformation percentage in the coated implants was statistically higher at 15 days, compared to 30 and 45 days. The mechanical tests showed that coated implants presented higher resistance to displacement, especially after 30 and 45 days.

scholarly journals BIODEGRADABLE VASCULAR GRAFT MODIFIED BY RGD-PEPTIDES: EXPERIMENTAL RESEARCH

2019 ◽  
Vol 34 (2) ◽  
pp. 129-137
Author(s):  
E. O. Krivkina ◽  
V. N. Silnikov ◽  
A. V. Mironov ◽  
E. A. Velikanova ◽  
E. A. Senokosova ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Grafts ◽  
Small Diameter ◽  
Internal Surface ◽  
Mechanical Tests ◽  
Laboratory Animals ◽  
Rgd Peptides ◽  
Peptide Modification

Research goals. To study the effectiveness of RGD-peptide modification of the small-diameter biodegradable vascular grafts depending on the type of a linker and RGD configuration.Material and Methods. Tubular scaffolds with a diameter of 1.5 and 4.0 mm were produced by electrospinning from polyhydroxybutyrate/valerate (PHBV) and polycaprolactone (PCL). The PHBV/PCL grafts were modified with RGD peptides. In vitro experiments showed the degree of erythrocyte hemolysis and adhesion of the platelets and endothelial cells when in contact with a modified surface. The physico-mechanical properties and the structure of graft surface were studied before and after modification. The PHBV/PCL and PHBV/PCL/RGD vascular grafts were implanted into the abdominal aorta of rats for the periods of 1 and 3 months. Explant samples were studied using confocal microscopy and histological methods.Results. The results of physical and mechanical tests showed a significant decrease in the strength properties of the PHBV/PCL/RGD grafts relative to the unmodified analogs. A significant increase in platelet aggregation was found in the modified grafts. The level of adhesion of the endothelial cells on the modified surfaces was higher than that on the unmodified surfaces. Shortterm implantation of the grafts for 1 and 3 months showed that the modified grafts had higher patency and a less tendency to calcification compared with the unmodified grafts. Immunofluorescence study demonstrated the significant superiority of the modified vascular grafts in terms of stimulating the formation of a mature endothelial monolayer. A longer linker of 4,7,10-trioxa-1,13-tridecane diamine was found to increase the bioavailability of RGD peptides; the use of RGDK and c[RGDFK] for surface modification of the grafts stimulated early endothelialization of the internal surface of the implants and reduced the prosthetic wall calcification tendency, which together increased the patency of the implanted grafts.Conclusion. In short-term implantation of biodegradable vascular grafts modified with RGD peptides, the grafts with RGDK and c[RGDFK], attached to the surface of the prostheses through the 4,7,10-triox-1,13-tridecane diamine linker, showed the best results in terms of endothelial adhesion and maintenance of the viability of the endothelial cells in vitro and endothelialization in vivo; these grafts had high patency after implantation into the bloodstream of small laboratory animals and a less tendency to calcification.

scholarly journals PHYSICAL STABILITY TEST AND ETHANOL CREAM IRRITATION TEST OF Moringa oleifera L.

2021 ◽  
Vol 6 (2) ◽  
pp. 186-195
Author(s):  
Nining Sugihartini ◽  
◽  
Zainab Zainab ◽  
Aji Pamungkas ◽  
◽  
...  
Keyword(s):  
Leaf Extract ◽  
Mechanical Test ◽  
Physical Stability ◽  
Ethanol Extract ◽  
Mechanical Tests ◽  
Stability Test ◽  
Irritation Test ◽  
Topical Dosage ◽  
Moringa Leaf Extract

The development of topical dosage forms of Moringa leaf extract cream has been carried out because of its properties that can moisturize the skin. A pharamceutical preparation must meet the requirements of stability and non toxic. The study aimed to determine the effect of variations un the concentration ethanol extract cream of Moringa leaf of physical stability and irritability. Ethanol extract of Moringa leaves was obtained by maceration method with 50% ethanol solvent. The extract was then formulated in the form of O/W base scarring with concentrations of 1% (F1), 3% (F2), and 5% (F3). Creams were evaluated for physical stability including mechanical tests (centrifugation) and physical stability at room temperature (25 ± 2oC) with parameters pH, viscosity on days 1, 7, 14, 21 and 28. In addition, creams were also evaluated for their irritability in vivo with using test animals (rabbits). The data obtained were analyzed using one-way ANOVA test. The results of the physical stability test showed that an increase in the concentration of Moringa leaf extract caused an increase in viscosity (P <0.5) and a decrease in pH (P <0.5) but did not affect physical stability (mechanical test) and its irritating effect. F2 (1%) has a pH of 7.61 while F4 (5%) is 7.01. Based on the results of the study, it is concluded that variations in the concentration of ethanol extract of Moringa leaves can affect the physical stability of the cream and do not affect its irritation properties. Moringa leaf ethanol extract cream with a concentration of 5% (F4) has physical stability and does not irritate the skin better than other formulas.

Local Mechanical Anisotropy in Human Cranial Dura Mater Allografts

1998 ◽  
Vol 120 (4) ◽  
pp. 541-544 ◽  
Author(s):  
M. S. Sacks ◽  
M. C. Jimenez Hamann ◽  
S. E. Otan˜no-Lata ◽  
T. I. Malinin
Keyword(s):  
Dura Mater ◽  
Mechanical Tests ◽  
Mechanical Anisotropy ◽  
Fiber Architecture ◽  
High Mechanical Strength ◽  
Structural Symmetry ◽  
Symmetry Test ◽  
The Right ◽  
High Degree

Human cranial dura mater (CDM) allograft’s success as a repair biomaterial is partly due to its high mechanical strength, which facilitates its ability to form water-tight barriers and resist high in-vivo mechanical loads. Previous studies on CDM allograft mechanical behavior used large test specimens and concluded that the allograft was mechanically isotropic. However, we have quantified CDM microstructure using small angle light scattering (SALS) and found regions of well-aligned fibers displaying structural symmetry between the right and left halves (Jimenez et al., 1998). The high degree of fiber alignment in these regions suggests that they are mechanically anisotropic. However, identification of these regions using SALS requires irreversible tissue dehydration, which may affect mechanical properties. Instead, we utilized CDM structural symmetry to estimate the fiber architecture of one half of the CDM using computer graphics to flip the SALS fiber architecture map of the corresponding half about the plane of symmetry. Test specimens (20 mm × 4 mm) were selected parallel and perpendicular to the preferred fiber directions and subjected to uniaxial mechanical failure testing. CDM allografts were found to be locally anisotropic, having an ultimate tensile strength (UTS) parallel to the fibers of 12.76 ± 1.65 MPa, and perpendicular to the fibers of 5.21 ± 1.01 MPa (mean ± sem). These results indicate that uniaxial mechanical tests on large samples used in previous studies tended to mask the local anisotropic nature of the smaller constituent sections. The testing methods established in this study can be used in the evaluation of new CDM processing methods and post-implant allograft mechanical integrity.

Spline Based Microstructural Mapping for Soft Biological Tissues: Application to Aortic Valves

2013 ◽  
Author(s):  
A. Aggarwal ◽  
V. S. Aguilar ◽  
C. H. Lee ◽  
G. Ferrari ◽  
J. H. Gorman ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Computer Aided Design ◽  
Biological Tissues ◽  
Mechanical Tests ◽  
Aortic Valves ◽  
Element Analysis ◽  
Tissue Microstructure ◽  
Forward And Inverse Modeling

Splines are the standard tools in computer aided design for geometric representations and have been recently integrated into the finite element analysis of structures and fluids [1]. As the biomedical engineering is making progress, there is a need for an integrated tool for expanding the geometrical representation to include the microstructural details specific to soft tissue, e.g. fiber alignment, orientation, crimp and stiffness. In this work, a spline-based method is presented for aortic valves which facilitates mapping of the fiber structure from any aortic valve specimen to any other aortic valve geometry through a common parameter space. This techniques also has the ability to calculate mean tissue microstructure of representative population. Also strain and pre-strain from in-vivo state to the in-vitro state, where all the mechanical tests are done, are calculated for forward and inverse modeling of aortic valves.

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