Changes in the biomechanical properties of skin and aorta induced by corticotrophin treatment

1980 ◽  
Vol 94 (1) ◽  
pp. 132-137 ◽  
Author(s):  
H. Oxlund
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Connective Tissue ◽  
Thoracic Aorta ◽  
Aortic Wall ◽  
Biomechanical Properties ◽  
Elastic Stiffness ◽  
Collagen Content ◽  
Dorsal Skin ◽  
Biophysical Properties

Abstract. The work presented here is an investigation of the effect of elevated levels of corticosteroids on the biophysical properties of skin, aorta and muscle tendon. Rats were given corticotrophin injections for 10, 30 and 60 days to elevate the level of plasma endogenous corticosteroids. The corticotrophin treatments did not change the water or collagen content of specimens from dorsal skin, thoracic aorta and peroneal muscle tendons, tested mechanically. Changes became evident after longer treatment times. For both skin and aorta, the tensile strength, elastic stiffness and failure energy were increased after 60 days of treatment. The corticotrophin treatment did not influence the mechanical properties of muscle tendons. Complete reversibility of changes in the mechanical properties induced by 30 days of corticotrophin treatment was found after an additional period of 30 days of saline injections. This study indicates that an increased level of plasma corticosteroids elicited by corticotrophin treatment may increase the stiffness of the connective tissue of the organism. In the aorta this results in loss of capacitive function with increased haemodynamic strain on the aortic wall.

scholarly journals Contribution of Collagen Fiber Undulation to Regional Biomechanical Properties Along Porcine Thoracic Aorta

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Shahrokh Zeinali-Davarani ◽  
Yunjie Wang ◽  
Ming-Jay Chow ◽  
Raphaël Turcotte ◽  
Yanhang Zhang
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Thoracic Aorta ◽  
Aortic Wall ◽  
Multiphoton Microscopy ◽  
Constitutive Models ◽  
Tensile Tests ◽  
Biomechanical Properties ◽  
Model Parameters ◽  
Extracellular Matrix Components

As major extracellular matrix components, elastin, and collagen play crucial roles in regulating the mechanical properties of the aortic wall and, thus, the normal cardiovascular function. The mechanical properties of aorta, known to vary with age and multitude of diseases as well as the proximity to the heart, have been attributed to the variations in the content and architecture of wall constituents. This study is focused on the role of layer-specific collagen undulation in the variation of mechanical properties along the porcine descending thoracic aorta. Planar biaxial tensile tests are performed to characterize the hyperelastic anisotropic mechanical behavior of tissues dissected from four locations along the thoracic aorta. Multiphoton microscopy is used to image the associated regional microstructure. Exponential-based and recruitment-based constitutive models are used to account for the observed mechanical behavior while considering the aortic wall as a composite of two layers with independent properties. An elevated stiffness is observed in distal regions compared to proximal regions of thoracic aorta, consistent with sharper and earlier collagen recruitment estimated for medial and adventitial layers in the models. Multiphoton images further support our prediction that higher stiffness in distal regions is associated with less undulation in collagen fibers. Recruitment-based models further reveal that regardless of the location, collagen in the media is recruited from the onset of stretching, whereas adventitial collagen starts to engage with a delay. A parameter sensitivity analysis is performed to discriminate between the models in terms of the confidence in the estimated model parameters.

VASCULAR CONNECTIVE TISSUE UNDER THE INFLUENCE OF THYROXINE

1961 ◽  
Vol 36 (2) ◽  
pp. 197-211 ◽  
Author(s):  
lb Lorenzen
Keyword(s):  
Connective Tissue ◽  
Vessel Wall ◽  
Aortic Wall ◽  
Calcium Content ◽  
Sodium Sulphate ◽  
Collagen Content ◽  
Histological Changes ◽  
Hexosamine Content ◽  
Healing Processes

ABSTRACT Biochemical and histological changes in the aortic wall of rabbits were demonstrated following injection of epinephrine and l-thyroxine during 2 weeks. The widespread gross and microscopic changes were accompanied by an increase in hexosamine content and uptake of 35S labeled sodium sulphate, and an increased calcium content, whereas the collagen content, assessed by determination of hydroxyproline, was reduced. Comparison with the effect of epinephrine injections alone showed that thyroxine intensified the damaging effect of epinephrine on the vessel wall and induced more pronounced mucopolysaccharide changes in the aortic wall, presumably acting as a link in the healing processes.

scholarly journals Mimicking the Mechanical Properties of Aortic Tissue with Pattern-Embedded 3D Printing for a Realistic Phantom

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5042
Author(s):  
Jaeyoung Kwon ◽  
Junhyeok Ock ◽  
Namkug Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
3D Printing ◽  
Mechanical Characteristics ◽  
Aortic Wall ◽  
Tensile Tests ◽  
Human Aorta ◽  
Aortic Tissue ◽  
Medical Field ◽  
Base Materials

3D printing technology has been extensively applied in the medical field, but the ability to replicate tissues that experience significant loads and undergo substantial deformation, such as the aorta, remains elusive. Therefore, this study proposed a method to imitate the mechanical characteristics of the aortic wall by 3D printing embedded patterns and combining two materials with different physical properties. First, we determined the mechanical properties of the selected base materials (Agilus and Dragonskin 30) and pattern materials (VeroCyan and TPU 95A) and performed tensile testing. Three patterns were designed and embedded in printed Agilus–VeroCyan and Dragonskin 30–TPU 95A specimens. Tensile tests were then performed on the printed specimens, and the stress-strain curves were evaluated. The samples with one of the two tested orthotropic patterns exceeded the tensile strength and strain properties of a human aorta. Specifically, a tensile strength of 2.15 ± 0.15 MPa and strain at breaking of 3.18 ± 0.05 mm/mm were measured in the study; the human aorta is considered to have tensile strength and strain at breaking of 2.0–3.0 MPa and 2.0–2.3 mm/mm, respectively. These findings indicate the potential for developing more representative aortic phantoms based on the approach in this study.

Changes of Biochemical and Biomechanical Properties in Dupuytren Disease

2000 ◽  
Vol 124 (9) ◽  
pp. 1275-1281
Author(s):  
Mahmoud Melling ◽  
Daniela Karimian-Teherani ◽  
Sascha Mostler ◽  
Mark Behnam ◽  
Grazyna Sobal ◽  
...  
Keyword(s):  
Structural Changes ◽  
Clinical Stage ◽  
Young Modulus ◽  
Biomechanical Properties ◽  
Collagen Content ◽  
Type Iii Collagen ◽  
Biophysical Properties ◽  
Type Iii ◽  
Palmar Aponeurosis ◽  
Dupuytren Disease

Abstract Background.—The major biochemical characteristic of Dupuytren disease is the progressive and irreversible deposition of excess fibrous collagen characterized by an enhanced type III collagen proportion. Objective.—To investigate the influence of changes of the collagen spectrum on the biophysical properties of the palmar aponeurosis. Design.—Variably affected palmar regions from 30 individuals with Dupuytren disease were classified according to histologic test results and clinical stage. Biochemical, biomechanical, and thermal contracture studies were performed. Results.—The relative type III collagen content increased with increasing tissue involvement and was found to correlate with calorimetric and biomechanical properties with the exception of the Young modulus. In experiments on the thermal isometric contracture, the collagen denaturation temperature decreased with increasing type III collagen content, ie, increasing involvement. To study the dependence of biophysical properties from the collagen type distribution independent of structural changes, as seen in Dupuytren disease, we investigated rat skins from animals of an age range characterized by dramatic changes in type III collagen content (0–18 months). Biomechanical data also correlated significantly with type III collagen content in rat skin with the exception of the time constant of stress relaxation. Conclusion.—In light of these results, we suggest that structural changes, such as reduced collagen fibril diameters, associated with alterations in the type III collagen proportion may influence biophysical properties of connective tissues in the involved palmar aponeurosis in addition to alterations of the cross-linking pattern.

EFFECTS OF CULTURE PERIODS AND LOADING ON BIOMECHANICAL PROPERTIES OF SHEEP COLLAGEN FASCICLES

2014 ◽  
Vol 14 (06) ◽  
pp. 1440010
Author(s):  
AHMET C. CILINGIR
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Soft Tissues ◽  
Culture Media ◽  
Experimental Studies ◽  
Biomechanical Properties ◽  
Collagen Fibrils ◽  
Tangent Modulus ◽  
Control Group ◽  
Stress Strain

Soft tissues (e.g., tendon, skin, cartilage) change their dimensions and properties in response to applied mechanical stress/strain, which is called remodeling. Experimental studies using tissue cultures were performed to understand the biomechanical properties of collagen fascicles under mechanical loads. Collagen fascicles were dissected from sheep Achilles tendons and loaded under 1, 2, and 3 kg for 2, 4, and 6 days under culture. The mechanical properties of collagen fascicles after being loaded into the culture media were determined using tensile tester, and resultant stress–strain curves, tangent modulus, tensile strength, and strain at failure values were compared with those in a non-loaded and non-cultured control group of fascicles. The tangent modulus and tensile strength of the collagen fascicles increased with the increasing remodeling load after two days of culture. However, these values gradually decreased with the increasing culture period compared with the control group. According to the results obtained in this study, the mechanical properties of collagen fascicles were improved by loading at two days of culture, most likely due to the remodeling of collagen fibers. However, after a period of remodeling, local strains on the collagen fibrils increased, and finally, the collagen fibrils broke down, decreasing the mechanical properties of the tissue.

scholarly journals Biomechanical properties of the rectovaginal fascia. Is it really a fascia?

2011 ◽  
Vol 25 (1) ◽  
pp. 11
Author(s):  
Karin Glavind ◽  
Janus Bo Jespersen ◽  
Mikkel Seyer-Hansen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Mechanical Testing ◽  
Biomechanical Properties ◽  
Abdominal Hysterectomy ◽  
Collagen Content ◽  
Significant Difference ◽  
Testing And Measurement ◽  
Abdominal Fascia

<em>Background</em>. The aim of this study was to find out whether the rectovaginal fascia was really a true fascia by comparing the mechanical properties and collagen content of the rectovaginal fascia in women operated for rectoceles to the abdominal fascia in patients having an abdominal hysterectomy. <em>Materials and Methods</em>. Thirty patients were included. During operation for rectocele or hysterectomy a biopsy measuring 8 x 15 mm was taken from the rectovaginal fascia or abdominal fascia. Mechanical testing and measurement of collagen content was performed. <em>Results</em>. A significant difference in mechanical strength of the tissue was found. If, however, the strength was corrected for collagen content there was no difference between the two groups. <em>Conclusion</em>. The quality of collagen was comparable in the two groups. This adds further evidence to the existence of a distinct rectovaginal fascia.

Biomechanical changes of freezer-storaged and decellularized pig tracheal scaffoldings

2021 ◽  
pp. 088532822098566
Author(s):  
Jinping Wang ◽  
Haixiang Zhang ◽  
Yangmeng Feng ◽  
Yang Sun ◽  
Ruina Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Testing Machine ◽  
Biomechanical Properties ◽  
Universal Testing ◽  
Significant Difference ◽  
Group A ◽  
Biomechanical Changes ◽  
Group B ◽  
Group D

Background As an excellent xenotransplant, the pig trachea can be decellularized and cryopreserved to reduce its immunogenicity. However, few reports are found on the changes of its mechanical properties after cryopreservation and decellularization. Objective To evaluate the structure and biomechanical properties in pig tracheal scaffolds resulting from decellularized and cryopreserved. Material and methods Twenty-five pig tracheal segments were separated into five groups: untreated (group A), only decellularized (group B), only cryopreserved (group C), decellularized after cryopreserved (group D) and cryopreserved after decellularized (group E). Tracheal segments were subjected to uniaxial tension or compression using a universal testing machine to determine structural biomechanical changes. Results It showed that there was no statistically significant difference in the tensile strength of the trachea in each group. The compressive strength of group B, C and D were same as the group A ( P > 0.05), while the group E was lower than that of the group A ( P < 0.05). Conclusions and significance: The histological examination of the decellularization after cryopreservation shows that the removal of epithelial cells and submucosal cells is more thorough, and the biomechanical structure of the trachea is better preserved. This proved to be a new method to prepare xenotransplantation of trachea graft.

THE EFFECT OF FREEZING ON BIOMECHANICAL PROPERTIES OF THE CARPAL TUNNEL SUBSYNOVIAL CONNECTIVE TISSUE

2015 ◽  
Vol 18 (04) ◽  
pp. 1550019 ◽  
Author(s):  
Anika Filius ◽  
Andrew Thoreson ◽  
Abhishek Dharan ◽  
Kristin Mara ◽  
Kai-Nan An ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Connective Tissue ◽  
Mechanical Testing ◽  
Carpal Tunnel ◽  
Repeated Measures ◽  
Damage Threshold ◽  
Biomechanical Properties ◽  
Fresh Frozen ◽  
Tunnel Syndrome ◽  
Subsynovial Connective Tissue

Biomechanical evaluation of the subsynovial connective tissue (SSCT) provides insight into the causes of carpal tunnel syndrome. Studies of carpal tunnel mechanics have been performed using fresh-frozen cadaver tissue. Freezing can affect mechanical properties of some tissues, but its effect on SSCT is unknown. A total of 16 rabbit paws were harvested from eight New Zealand rabbits and subjected to mechanical testing consisting of three repeated tendon excursions in sets of three different excursion magnitudes. One paw from each animal was unfrozen. The contralateral paw was frozen and thawed before testing. Force, energy and stiffness of the first cycle of each set were evaluated, as were ratios of the second to first cycle for each parameter. Two-factor ANOVA with repeated measures over both factors was performed. No significant interactions between factors were found. There were no significant differences between fresh and frozen paws for any parameters, though there were significant differences between excursion amplitudes. The damage threshold was not different between fresh and frozen paws. This study demonstrated that freezing rabbit subsynovial connective tissue does not significantly change its mechanical properties. The same may be true for human cadaver tissues. Results of cadaver mechanical testing may not be influenced by this preservation technique.

scholarly journals MECHANICAL PROPERTIES OF PVA NANOFIBER TEXTILES WITH INCORPORATED NANODIAMONDS, COPPER AND SILVER IONS

2015 ◽  
Vol 55 (1) ◽  
pp. 14-21
Author(s):  
Kateřina Indrová ◽  
Zdeněk Prošek ◽  
Jaroslav Topič ◽  
Pavla Ryparová ◽  
Václav Nežerka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Thermal Stabilization ◽  
Silver Ions ◽  
Elastic Stiffness ◽  
Poly Vinyl Alcohol ◽  
Minor Effect ◽  
Electrospinning Method ◽  
A Minor ◽  
Cu Ions

The unique properties of nanotextiles based on poly(vinyl-alcohol) (PVA) manufactured using electrospinning method have been known and exploited for many years. Recently, the enrichment of nanofiber textiles with nanoparticles, such as ions or nanodiamond particles (NDP), has become a popular way to modify the textile mechanical, chemical and physical properties. The aim of our study is to investigate the macromechanical properties of PVA nanotextiles enriched with NDP, silver (Ag) and copper (Cu) ions. The nanofiber textiles of a various surface weight were prepared from 16% PVA solution, while glyoxal and phosphoric acid were used as cross-linking agents. The copper and silver ions were diluted in aqueous solution and NDP were dispersed into the fibers by ultrasound homogenization. All but one set of samples were exposed to the temperature of 140 °C for 10 minutes. The samples without thermal stabilization exhibited significantly lower elastic stiffness and tensile strength. Moreover, the results of tensile testing indicate that the addition of dispersed nanoparticles has a minor effect on the mechanical properties of textiles and contributes rather to their reinforcement. On the other hand, the lack of thermal stabilization results in a poor interconnection of individual nanofiber layers and the non-stabilized textiles exhibit a lower elastic stiffness and reduced tensile strength.

Spatial Variations in the Mechanical Properties of the Porcine Thoracic Aorta

2011 ◽  
Author(s):  
Jungsil Kim ◽  
Seungik Baek
Keyword(s):  
Mechanical Properties ◽  
Vascular Disease ◽  
Thoracic Aorta ◽  
Aortic Wall ◽  
Vascular Tissue ◽  
Experimental Studies ◽  
Wall Stress ◽  
Clinical Decision ◽  
Arterial Tree

Characterization of the mechanical properties of a blood vessel is essential in understanding the progression of a vascular disease and for computational studies of vascular adaptation. For example, stiffness of vascular tissue is one of the major indicators to diagnose the vascular disease and make a clinical decision. Although previous studies reported the heterogeneity of the mechanical properties of arterial wall along the arterial tree [2], little was taken account for its circumferential variations. With the lack of experimental studies for investigating the circumferential variation, the aortic wall is typically assumed to have uniform deformation. Our previous study, however, has observed that there are circumferential variations in aortic wall stress and stiffness [1]. In addition to our previous study, we investigate further regional variations of the porcine thoracic aorta in both circumferential and longitudinal directions during the inflation test. Hence, we additionally test the distal thoracic aorta at each anterior and posterior side, respectively, and compare with the proximal thoracic aorta.

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