Mechanical properties of skin and responsiveness of slowly adapting type I mechanoreceptors in rats at different ages.

AbstractNowadays, artificial bone materials have been widely applied in the filling of non-weight bearing bone defects, but scarcely ever in weight-bearing bone defects. This study aims to develop an artificial bone with excellent mechanical properties and good osteogenic capability. Firstly, the collagen-thermosensitive hydrogel-calcium phosphate (CTC) composites were prepared as follows: dissolving thermosensitive hydrogel at 4 °C, then mixing with type I collagen as well as tricalcium phosphate (CaP) powder, and moulding the composites at 37 °C. Next, the CTC composites were subjected to evaluate for their chemical composition, micro morphology, pore size, Shore durometer, porosity and water absorption ability. Following this, the CTC composites were implanted into the muscle of mice while the 70% hydroxyapatite/30% β-tricalcium phosphate (HA/TCP) biomaterials were set as the control group; 8 weeks later, the osteoinductive abilities of biomaterials were detected by histological staining. Finally, the CTC and HA/TCP biomaterials were used to fill the large segments of tibia defects in mice. The bone repairing and load-bearing abilities of materials were evaluated by histological staining, X-ray and micro-CT at week 8. Both the CTC and HA/TCP biomaterials could induce ectopic bone formation in mice; however, the CTC composites tended to produce larger areas of bone and bone marrow tissues than HA/TCP. Simultaneously, bone-repairing experiments showed that HA/TCP biomaterials were easily crushed or pushed out by new bone growth as the material has a poor hardness. In comparison, the CTC composites could be replaced gradually by newly formed bone and repair larger segments of bone defects. The CTC composites trialled in this study have better mechanical properties, osteoinductivity and weight-bearing capacity than HA/TCP. The CTC composites provide an experimental foundation for the synthesis of artificial bone and a new option for orthopedic patients.

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Intrinsic mechanical properties of the extracellular matrix affect the behavior of pre-osteoblastic MC3T3-E1 cells

AJP Cell Physiology ◽

10.1152/ajpcell.00455.2005 ◽

2006 ◽

Vol 290 (6) ◽

pp. C1640-C1650 ◽

Cited By ~ 177

Author(s):

Chirag B. Khatiwala ◽

Shelly R. Peyton ◽

Andrew J. Putnam

Keyword(s):

Mechanical Properties ◽

Type I Collagen ◽

Focal Adhesions ◽

Microscopic Analysis ◽

Maximal Activity ◽

Type I ◽

Cell Functions ◽

Collagen Density ◽

Cells Cultured ◽

In Cells

Mechanical cues present in the ECM have been hypothesized to provide instructive signals that dictate cell behavior. We probed this hypothesis in osteoblastic cells by culturing MC3T3-E1 cells on the surface of type I collagen-modified hydrogels with tunable mechanical properties and assessed their proliferation, migration, and differentiation. On gels functionalized with a low type I collagen density, MC3T3-E1 cells cultured on polystyrene proliferated twice as fast as those cultured on the softest substrate. Quantitative time-lapse video microscopic analysis revealed random motility speeds were significantly retarded on the softest substrate (0.25 ± 0.01 μm/min), in contrast to maximum speeds on polystyrene substrates (0.42 ± 0.04 μm/min). On gels functionalized with a high type I collagen density, migration speed exhibited a biphasic dependence on ECM compliance, with maximum speeds (0.34 ± 0.02 μm/min) observed on gels of intermediate stiffness, whereas minimum speeds (0.24 ± 0.03 μm/min) occurred on both the softest and most rigid (i.e., polystyrene) substrates. Immature focal contacts and a poorly organized actin cytoskeleton were observed in cells cultured on the softest substrates, whereas those on more rigid substrates assembled mature focal adhesions and robust actin stress fibers. In parallel, focal adhesion kinase (FAK) activity (assessed by detecting pY397-FAK) was influenced by compliance, with maximal activity occurring in cells cultured on polystyrene. Finally, mineral deposition by the MC3T3-E1 cells was also affected by ECM compliance, leading to the conclusion that altering ECM mechanical properties may influence a variety of MC3T3-E1 cell functions, and perhaps ultimately, their differentiated phenotype.

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Assembly of type I collagen: fusion of fibril subunits and the influence of fibril diameter on mechanical properties

Matrix Biology ◽

10.1016/s0945-053x(00)00089-5 ◽

2000 ◽

Vol 19 (5) ◽

pp. 409-420 ◽

Cited By ~ 208

Author(s):

David L. Christiansen ◽

Eric K. Huang ◽

Frederick H. Silver

Keyword(s):

Mechanical Properties ◽

Type I Collagen ◽

Type I ◽

Fibril Diameter

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Mechanical Properties of Native and Cross-linked Type I Collagen Fibrils

Biophysical Journal ◽

10.1529/biophysj.107.111013 ◽

2008 ◽

Vol 94 (6) ◽

pp. 2204-2211 ◽

Cited By ~ 126

Author(s):

Lanti Yang ◽

Kees O. van der Werf ◽

Carel F.C. Fitié ◽

Martin L. Bennink ◽

Pieter J. Dijkstra ◽

...

Keyword(s):

Mechanical Properties ◽

Type I Collagen ◽

Collagen Fibrils ◽

Type I

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Regenerative Rehabilitation in Injuries of Tendons

Physical and rehabilitation medicine, medical rehabilitation ◽

10.36425/rehab70760 ◽

2021 ◽

Vol 3 (2) ◽

pp. 192-206

Author(s):

Sergey G. Sсherbak ◽

Stanislav V. Makarenko ◽

Olga V. Shneider ◽

Tatyana A. Kamilova ◽

Alexander S. Golota

Keyword(s):

Mechanical Properties ◽

Type I Collagen ◽

Transforming Growth Factor ◽

Healing Process ◽

Tendon Healing ◽

Tendon Injuries ◽

Type I ◽

Differentiation Markers ◽

Postoperative Rehabilitation ◽

Potent Inducer

The mechanical properties of tendons are thought to be affected by different loading levels. Changes in the mechanical properties of tendons, such as stiffness, have been reported to influence the risk of tendon injuries chiefly in athletes and the elderly, thereby affecting motor function execution. Unloading resulted in reduced tendons stiffness, and resistance exercise exercise counteracts this. Transforming growth factor-1 is a potent inducer of type I collagen and mechanosensitive genes encoding tenogenic differentiation markers expression which play critical roles in tendon tissue formation, tendon healing and their adaptation during exercise. In recent years, our understanding of the molecular biology of tendons growth and repair has expanded. It is probable that the next advance in the treatment of tendon injuries will result from the application of this basic science knowledge and the clinical solution will encompass not only the the best postoperative rehabilitation protocols, but also the optimal biological modulation of the healing process.

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Some discriminatory characteristics of earthquakes near the Kariba, Kremasta, and Koyna artificial lakes

Bulletin of the Seismological Society of America ◽

10.1785/bssa0620020493 ◽

1972 ◽

Vol 62 (2) ◽

pp. 493-507 ◽

Cited By ~ 1

Author(s):

Harsh K. Gupta ◽

B. K. Rastogi ◽

Hari Narain

Keyword(s):

Mechanical Properties ◽

Time Distribution ◽

Focal Mechanisms ◽

Type I ◽

Type Ii ◽

B Values ◽

Artificial Lakes ◽

Earthquake Sequences ◽

Frequency Magnitude

abstract The behavior of earthquakes near the artificial lakes at Kariba, Kremasta, and Koyna, where earthquakes of magnitude exceeding 6 have occurred, is examined. Foreshock-aftershock patterns of these earthquake sequences correspond with Mogi's type II model, whereas the normal earthquakes of these regions belong to type I. Three similar relations could be fitted in the time distribution of aftershocks of the main earthquakes. Quite contrary to normal earthquakes, foreshock b values are found to be comparable with the aftershock b values in the frequency-magnitude relations. Focal mechanisms of the largest earthquakes of these sequences have been determined and compared. Dip-slip components of the motion are such that the lakes are situated on the downthrown blocks. These regions are characterized by a volcanic past and the presence of rocks such as limestones and red boles which are easily affected by water. These findings are useful in distinguishing the reservoir-associated earthquakes from normal earthquakes and suggest that the artificial lakes are responsible for changing the mechanical properties of the strata and releasing the accumulated strains.

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Pathomechanics of Hallux Valgus: Biomechanical and Immunohistochemical Study

Foot & Ankle International ◽

10.1177/107110070502600911 ◽

2005 ◽

Vol 26 (9) ◽

pp. 732-738 ◽

Cited By ~ 30

Author(s):

Eiichi Uchiyama ◽

Harold B. Kitaoka ◽

Zong-Ping Luo ◽

Joseph P. Grande ◽

Hideji Kura ◽

...

Keyword(s):

Mechanical Properties ◽

Hallux Valgus ◽

Tensile Modulus ◽

Metatarsophalangeal Joint ◽

Collagen Fibers ◽

Collagen I ◽

Type Iii Collagen ◽

Type I ◽

First Metatarsophalangeal Joint ◽

Collagen Iii

Background: One factor believed to contribute to the development of hallux valgus is an abnormality in collagen structure and makeup of the medial collateral ligament (MCL) of the first metatarsophalangeal joint (MTPJ). We hypothesized that the mechanical properties of the MCL in feet with hallux valgus are significantly different from those in normal feet and that these differences may be related to alterations in the type or distribution of collagen fibers at the interface between the MCL and the bone. Materials and Methods: Seven normal fresh-frozen cadaver feet were compared to four cadaver feet that had hallux valgus deformities. The MCL mechanical properties, structure of collagen fibers, and content proportion of type I and type III collagen were determined. Results: The load-deformation and stress-strain curves were curvilinear with three regions: laxity, toe, and linear regions. Laxity of the MCL in feet with hallux valgus was significantly larger than that of normal feet ( p = 0.022). Stiffness and tensile modulus in the toe region in feet with hallux valgus were significantly smaller than those in normal feet ( p = 0.004); however, stiffness and tensile modulus in the linear region were not significantly different. The MCL collagen fibrils in the feet with hallux valgus had a more wavy distribution than the fibrils in the normal feet. Conclusions: In general, strong staining for collagen III and to a lesser extent, collagen I was observed at the interface between the MCL and bone in the feet with hallux valgus but not in the normal feet. These results indicate that the abnormal mechanical properties of the MCL in feet with hallux valgus may be related to differences in the organization of collagen I and collagen III fibrils.

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An Experimental Study of Carbon Nanotube Reinforcements

Volume 11: Nano and Micro Materials, Devices and Systems; Microsystems Integration ◽

10.1115/imece2011-64021 ◽

2011 ◽

Author(s):

Lauren Patrin ◽

Frank Chow ◽

Gabriela Philippart ◽

Feridun Delale ◽

Benjamin Liaw ◽

...

Keyword(s):

Mechanical Properties ◽

Young’S Modulus ◽

Room Temperature ◽

Elevated Temperatures ◽

Young's Modulus ◽

Testing Machine ◽

Type I ◽

Electrical Measurements ◽

Standard Type ◽

Reinforcement Percentage

Due to their high strength and stiffness carbon nanotubes (CNTs) have been considered as candidates for reinforcement of polymeric resins. It is also known that the addition of CNTs to polymeric matrix results in highly conductive nanocomposites, making the material multifunctional. Most of the CNT reinforced polymeric nanocomposite systems reported in the literature have been studied at room temperature. However, in many applications, materials may be subjected from low to elevated temperatures. Thus, the aim of this research is to study CNT reinforced polypropylene (PP) specimens at room, elevated and low temperatures. ASTM standard Type I specimens manufactured via injection molding and reinforced with 0.2%, 1%, 3%, and 6% CNTs were first subjected to tensile loads in a universal testing machine at room temperature. Neat PP resin specimens were also tested to provide baseline data. The tests were repeated at −54°C (−65°F), −20°C (−4°F), 49°C (120°F) and 71°C (160°F). The results were plotted as stress-strain curves and analyzed to delineate the effect of CNT reinforcement percentage and temperature on the mechanical properties. It was noted that as the percentage of CNT reinforcement increases, the resulting nanocomposite becomes stiffer (higher Young’s modulus), has higher strength and becomes more brittle. Temperature has a drastic effect on the behavior of the nanocomposite. As the temperature increases, at a given reinforcement percentage the material becomes more ductile with significantly lower Young’s modulus and strength compared to room temperature. At lower temperatures, the nanocomposite becomes more brittle with higher stiffness and strength, but significantly reduced failure strain. Also electrical measurements were conducted on the specimens to measure their resistance. For specimens reinforced with up to 3% of CNTs no electrical conductivity was detected. As expected at 6% CNT reinforcement (which is above the approximately 4% percolation limit reported in the literature), the specimens became electrically conductive. To predict the mechanical properties obtained experimentally, a micromechanics based model is presented and compared with the experimental results.

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Collagen Network Topology is Influenced by Collagen Concentration, But Not by Co-Gelation With Fibrin

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53239 ◽

2011 ◽

Author(s):

Victor K. Lai ◽

Edward A. Sander ◽

Spencer P. Lake ◽

Robert T. Tranquillo ◽

Victor H. Barocas

Keyword(s):

Mechanical Properties ◽

Healing Process ◽

Biological Tissues ◽

Wound Healing Process ◽

Type I ◽

Collagen Gels ◽

Collagen Network ◽

Modeling Framework ◽

Collagen Concentration ◽

Cardiovascular Tissue

Extracellular matrix (ECM) proteins (e.g. collagen, elastin) play an important role in biological tissues. In addition to conferring mechanical strength to a tissue, the ECM provides a biochemical environment essential for modulation of cellular responses such as growth and migration. Collagens are the dominant protein of the ECM, with collagen type I being most abundant. Our group and others have shown that the mechanical properties of a collagen I matrix change with collagen concentration, and when formed in the presence of a secondary fibril network such as fibrin [1]. We are interested in collagen-fibrin systems because our group uses fibrin as the starting scaffold material for cardiovascular tissue engineering, which produces interpenetrating collagen-fibrin matrices during the remodeling process as the fibrin network is degraded and replaced with cell-deposited collagen [2]. Fibrin and collagen networks are also present together around the thrombus during the wound healing process. Research has shown that ECM mechanical properties are correlated with their overall network structure characteristics such as fibril diameter [3]. Currently we have a modeling framework that generates an ECM microstructural network which can be used to predict the overall properties of a bioengineered tissue [4]. This framework allows exploration of the structure-function relation, but how the structure depends on composition remains poorly understood, especially in multi-component gels. Thus, the objective of this work was to quantify the collagen network architecture in pure collagen gels of different concentrations and in collagen-fibrin co-gels.

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Influence of fibrillin-1 genotype on aortic stiffness in men: a note of caution

Journal of Applied Physiology ◽

10.1152/japplphysiol.01408.2005 ◽

2006 ◽

Vol 100 (4) ◽

pp. 1431-1432

Author(s):

Yasmin ◽

Ian B. Wilkinson ◽

Kevin M. O’Shaughnessy

Keyword(s):

Mechanical Properties ◽

Pulse Pressure ◽

Aortic Stiffness ◽

Collagen Type ◽

Collagen Type I ◽

Type I ◽

Increased Risk ◽

Fibrillin 1 ◽

Echo Tracking

Aortic stiffness is a predictor of cardiovascular mortality. The mechanical properties of the arterial wall depend on the connective tissue framework, with variation in fibrillin-1 and collagen I genes being associated with aortic stiffness and/or pulse pressure elevation. The aim of this study was to investigate whether variation in fibrillin-1 genotype was associated with aortic stiffness in men. The mechanical properties of the abdominal aorta of 79 healthy men (range 28–81 yr) were investigated by ultrasonographic phase-locked echo tracking. Fibrillin-1 genotype, characterized by the variable tandem repeat in intron 28, and collagen type I alpha 1 genotype characterized by the 2,064 G\?\T polymorphism, were determined by using DNA from peripheral blood cells. Three common fibrillin-1 genotypes, 2-2, 2-3, and 2-4, were observed in 50 (64%), 10 (13%), and 11 (14%) of the men, respectively. Those of 2-3 genotype had higher pressure strain elastic modulus and aortic stiffness compared with men of 2-2 or 2-4 genotype ( P = 0.005). Pulse pressure also was increased in the 2-3 genotype ( P = 0.04). There was no significant association between type 1 collagen genotype and aortic stiffness in this cohort. In conclusion, the fibrillin-1 2-3 genotype in men was associated with increased aortic stiffness and pulse pressure, indicative of an increased risk for cardiovascular disease.

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