scholarly journals Bimodal collagen fibril diameter distributions direct age-related variations in tendon resilience and resistance to rupture

2012 ◽  
Vol 113 (6) ◽  
pp. 878-888 ◽  
Author(s):  
K. L. Goh ◽  
D. F. Holmes ◽  
Y. Lu ◽  
P. P. Purslow ◽  
K. E. Kadler ◽  
...  
Keyword(s):  
Collagen Fibril ◽  
Strain Energy ◽  
Age Groups ◽  
Bimodal Distribution ◽  
Tensile Tests ◽  
Age Related ◽  
Transmission Electron ◽  
Rupture Energy ◽  
Tail Tendon ◽  
Fibril Diameter

Scaling relationships have been formulated to investigate the influence of collagen fibril diameter ( D) on age-related variations in the strain energy density of tendon. Transmission electron microscopy was used to quantify D in tail tendon from 1.7- to 35.3-mo-old (C57BL/6) male mice. Frequency histograms of D for all age groups were modeled as two normally distributed subpopulations with smaller ( DD1) and larger ( DD2) mean Ds, respectively. Both DD1 and DD2 increase from 1.6 to 4.0 mo but decrease thereafter. From tensile tests to rupture, two strain energy densities were calculated: 1) uE [from initial loading until the yield stress (σ Y)], which contributes primarily to tendon resilience, and 2) uF [from σ Y through the maximum stress (σ U) until rupture], which relates primarily to resistance of the tendons to rupture. As measured by the normalized strain energy densities uE/σ Y and uF/σ U, both the resilience and resistance to rupture increase with increasing age and peak at 23.0 and 4.0 mo, respectively, before decreasing thereafter. Multiple regression analysis reveals that increases in uE/σ Y (resilience energy) are associated with decreases in DD1 and increases in DD2, whereas uF/σ U (rupture energy) is associated with increases in DD1 alone. These findings support a model where age-related variations in tendon resilience and resistance to rupture can be directed by subtle changes in the bimodal distribution of Ds.

Ageing Changes in the Tensile Properties of Tendons: Influence of Collagen Fibril Volume Fraction

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. L. Goh ◽  
D. F. Holmes ◽  
H.-Y. Lu ◽  
S. Richardson ◽  
K. E. Kadler ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Collagen Fibril ◽  
Volume Fraction ◽  
Area Fraction ◽  
Sectional Area ◽  
Cross Sectional ◽  
P Values ◽  
Age Related ◽  
Fibril Diameter ◽  
Age Related Changes

Connective tissues are biological composites comprising of collagen fibrils embedded in (and reinforcing) the hydrated proteoglycan-rich (PG) gel within the extracellular matrices (ECMs). Age-related changes to the mechanical properties of tissues are often associated with changes to the structure of the ECM, namely, fibril diameter. However, quantitative attempts to correlate fibril diameter to mechanical properties have yielded inconclusive evidence. Here, we described a novel approach that was based on the rule of mixtures for fiber composites to evaluate the dependence of age-related changes in tendon tensile strength (σ) and stiffness (E) on the collagen fibril cross-sectional area fraction (ρ), which is related to the fibril volume fraction. Tail tendons from C57BL6 mice from age groups 1.6–35.3months old were stretched to failure to determine σ and E. Parallel measurements of ρ as a function of age were made using transmission electron microscopy. Mathematical models (rule of mixtures) of fibrils reinforcing a PG gel in tendons were used to investigate the influence of ρ on ageing changes in σ and E. The magnitudes of σ, E, and ρ increased rapidly from 1.6monthsto4.0months (P-values <0.05) before reaching a constant (age independent) from 4.0monthsto29.0months (P-values >0.05); this trend continued for E and ρ (P-values >0.05) from 29.0monthsto35.3months, but not for σ, which decreased gradually (P-values <0.05). Linear regression analysis revealed that age-related changes in σ and E correlated positively to ρ (P-values <0.05). Collagen fibril cross-sectional area fraction ρ is a significant predictor of ageing changes in σ and E in the tail tendons of C57BL6 mice.

Growth and development of collagen fibrils in immature tissues from rat and sheep

1981 ◽  
Vol 212 (1186) ◽  
pp. 85-92 ◽  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Collagen Fibril ◽  
Growth And Development ◽  
Collagen Fibrils ◽  
Diameter Distribution ◽  
Rat Tissues ◽  
Transmission Electron ◽  
The Mean ◽  
Fibril Diameter

The collagen fibril diameter distribution of four immature tissues from both rat and sheep have been determined from transverse sections observed in the transmission electron microscope. In many instances before birth, the form of the distribution for the tissues is both unimodal and sharp and the mean diameters of the distributions lie close to a multiple of 80 Å. For some tissues, the collagen fibril diameter distributions may be resolved into a number of components, each of which represents a population of fibrils with a diameter close to a multiple of 80 Å (8 nm). These data confirm and extend previous observations by the authors that small collagen fibrils all have diameters that are multiples of about 80 Å and that the fibril growth occurs by the accretion of 80 Å units. The form of the collagen fibril diameter distribution at birth is broad for the sheep tissues but narrow for the rat tissues, thus confirming that the range of fibril diameters at this stage of life reflects the differing degree of development of precocious and altricious animals.

scholarly journals Collagen Fibril Ultrastructure in Mice Lacking Discoidin Domain Receptor 1

2016 ◽  
Vol 22 (3) ◽  
pp. 599-611 ◽  
Author(s):  
Jeffrey R. Tonniges ◽  
Benjamin Albert ◽  
Edward P. Calomeni ◽  
Shuvro Roy ◽  
Joan Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Collagen Fibril ◽  
Collagen Fibrils ◽  
Collagen Deposition ◽  
Knock Out ◽  
Discoidin Domain Receptor ◽  
Transmission Electron ◽  
Fibril Diameter ◽  
Discoidin Domain Receptor 1

AbstractThe quantity and quality of collagen fibrils in the extracellular matrix (ECM) have a pivotal role in dictating biological processes. Several collagen-binding proteins (CBPs) are known to modulate collagen deposition and fibril diameter. However, limited studies exist on alterations in the fibril ultrastructure by CBPs. In this study, we elucidate how the collagen receptor, discoidin domain receptor 1 (DDR1) regulates the collagen content and ultrastructure in the adventitia of DDR1 knock-out (KO) mice. DDR1 KO mice exhibit increased collagen deposition as observed using Masson’s trichrome. Collagen ultrastructure was evaluated in situ using transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Although the mean fibril diameter was not significantly different, DDR1 KO mice had a higher percentage of fibrils with larger diameter compared with their wild-type littermates. No significant differences were observed in the length of D-periods. In addition, collagen fibrils from DDR1 KO mice exhibited a small, but statistically significant, increase in the depth of the fibril D-periods. Consistent with these observations, a reduction in the depth of D-periods was observed in collagen fibrils reconstituted with recombinant DDR1-Fc. Our results elucidate how DDR1 modulates collagen fibril ultrastructure in vivo, which may have important consequences in the functional role(s) of the underlying ECM.

scholarly journals Proteoglycan-collagen arrangements in developing rat tail tendon. An electron microscopical and biochemical investigation

1981 ◽  
Vol 195 (3) ◽  
pp. 573-581 ◽  
Author(s):  
J E Scott ◽  
C R Orford ◽  
E W Hughes
Keyword(s):  
Rapid Growth ◽  
Collagen Fibril ◽  
Chondroitin Sulphate ◽  
Post Partum ◽  
Dermatan Sulphate ◽  
Concentration Method ◽  
Sigmoid Curve ◽  
Tail Tendon ◽  
Electron Microscopical ◽  
Fibril Diameter

1. Developing tail tendons from rats (19-day foetal to 126 days post partum) were examined by electron microscopy after staining for proteoglycan with a cationic copper phthalocyanin dye. Cuprolinic Blue, in a “critical electrolyte concentration” method. Hydroxyproline was measured on papain digests of tendons, from which glycosaminoglycuronans were isolated, characterized and quantified. 2. Mean collagen fibril diameters increased more than 10-fold with age according to a sigmoid curve, the rapid growth phase 2 being during 30-90 days after conception. Fibril periodicities were considerably smaller (50-55 nm) in phases 1 and 2 than in phase 3 (greater than 62 nm). 3. Dermatan sulphate is the main glycosaminoglycuronan in mature tendon. Chondroitin sulphate and hyaluronate preponderate in foetal tissue. 4. Proteoglycan was seen around but not inside collagen fibrils. Proteoglycan and collagen were quantified from electron micrographs. Their ratios behaved similarly to uronic acid/hydroxyproline and hyaluronate/hydroxyproline ratios, which decreased rapidly around birth, and then levelled off to a low plateau coincident with the onset of rapid growth in collagen fibril diameter. 5. Dermatan sulphate/hydroxyproline ratios suggest that the proteoglycan orthogonal array around the fibril is largely dermatan sulphate. In the foetus hyaluronate and chondroitin sulphate exceed that expected to be bound to collagen. 6. An inhibiting action of chondroitin sulphate-rich proteoglycan on fibril diameter growth is suggested. 7. The distributions of hyaluronate, chondroitin sulphate and dermatan sulphate are discussed in the light of secondary structures suggested to be present in hyaluronate and chondroitin sulphate, but not in dermatan sulphate.

scholarly journals Diverse effects of Perlecan-HS on cell and matrix regulation: Tendon destabilization in Hspg2 Exon 3 null HS deficient mice reveals essential homeostatic roles for HS in cellular regulation and tendon functionality

2018 ◽  
Author(s):  
Cindy C Shu ◽  
Margaret M Smith ◽  
Richard C Appleyard ◽  
Christopher B Little ◽  
James Melrose
Keyword(s):  
Material Properties ◽  
Tensile Modulus ◽  
Ultimate Tensile Stress ◽  
Cellular Regulation ◽  
Achilles Tenotomy ◽  
Transmission Electron ◽  
Tail Tendon ◽  
Fibril Diameter ◽  
Deficient Mice

The aim of this study was to determine the regulatory role of the perlecan HS side chains on cell and matrix homeostasis in tail and Achilles tendons in 3 and 12 week old Hspg2 exon 3 null HS deficient (Hspg2∆3-/∆3- ) and C57 BL/6 Wild Type (WT) mice. Tendons were biomechanically tested (ultimate tensile stress [UTS], tensile modulus [TM]) and glycosaminoglycan (GAG) and collagen (hydroxyproline) compositional analyses undertaken. Monolayer cultures of Hspg2∆3-/∆3- tenocytes stimulated with FGF-2 showed elevated Adamts4, Mmp2, 3, 13 gene expression compared to WT mice. Col1A1, Vcan, Bgn, Dcn, Lum, Hspg2, Ltbp1, Ltbp2, Eln and Fbn1 showed no major differences between genotypes. Type VI collagen and perlecan were immunolocalised in tail tendon and collagen fibrils imaged using transmission electron microscopy (TEM). The amplified catabolic phenotype of Hspg2∆3-/∆3- mice may account for the age-dependent decline in GAG observed in tail tendon and changes in UTS/TM biomechanics. Collagen fibril diameter increased in WT but decreased in Hspg2∆3-/∆3- tail tendons over 3 to 12 weeks. Achilles tenotomy resulted in changes in tendon material properties in both genotypes but, Hspg2∆3-/∆3- mice had a slower recovery of UTS after tenotomy. HS deficiency in Hspg2∆3-/∆3- tendon impaired tenocyte repair responses to FGF-2 and led to deleterious changes in tendon organization which was reflected in changes in their material properties. .

scholarly journals Diverse effects of Perlecan-HS on cell and matrix regulation: Tendon destabilization in Hspg2 Exon 3 null HS deficient mice reveals essential homeostatic roles for HS in cellular regulation and tendon functionality

2018 ◽  
Author(s):  
Cindy C Shu ◽  
Margaret M Smith ◽  
Richard C Appleyard ◽  
Christopher B Little ◽  
James Melrose
Keyword(s):  
Material Properties ◽  
Tensile Modulus ◽  
Ultimate Tensile Stress ◽  
Cellular Regulation ◽  
Achilles Tenotomy ◽  
Transmission Electron ◽  
Tail Tendon ◽  
Fibril Diameter ◽  
Deficient Mice

The aim of this study was to determine the regulatory role of the perlecan HS side chains on cell and matrix homeostasis in tail and Achilles tendons in 3 and 12 week old Hspg2 exon 3 null HS deficient (Hspg2∆3-/∆3- ) and C57 BL/6 Wild Type (WT) mice. Tendons were biomechanically tested (ultimate tensile stress [UTS], tensile modulus [TM]) and glycosaminoglycan (GAG) and collagen (hydroxyproline) compositional analyses undertaken. Monolayer cultures of Hspg2∆3-/∆3- tenocytes stimulated with FGF-2 showed elevated Adamts4, Mmp2, 3, 13 gene expression compared to WT mice. Col1A1, Vcan, Bgn, Dcn, Lum, Hspg2, Ltbp1, Ltbp2, Eln and Fbn1 showed no major differences between genotypes. Type VI collagen and perlecan were immunolocalised in tail tendon and collagen fibrils imaged using transmission electron microscopy (TEM). The amplified catabolic phenotype of Hspg2∆3-/∆3- mice may account for the age-dependent decline in GAG observed in tail tendon and changes in UTS/TM biomechanics. Collagen fibril diameter increased in WT but decreased in Hspg2∆3-/∆3- tail tendons over 3 to 12 weeks. Achilles tenotomy resulted in changes in tendon material properties in both genotypes but, Hspg2∆3-/∆3- mice had a slower recovery of UTS after tenotomy. HS deficiency in Hspg2∆3-/∆3- tendon impaired tenocyte repair responses to FGF-2 and led to deleterious changes in tendon organization which was reflected in changes in their material properties. .

Immigrant Youth in Germany

2013 ◽  
Vol 18 (3) ◽  
pp. 158-168 ◽  
Author(s):  
Emily Frankenberg ◽  
Katharina Kupper ◽  
Ruth Wagner ◽  
Stephan Bongard
Keyword(s):  
School System ◽  
Large Scale ◽  
Age Groups ◽  
Well Being ◽  
Ethnic Discrimination ◽  
Emotional And Behavioral Problems ◽  
Sociocultural Adaptation ◽  
Age Related ◽  
German School ◽  
Transcultural Adaptation

This paper reviews research on young migrants in Germany. Particular attention is given to the question of how Germany’s history of migration, immigration policies, and public attitude toward migrants influence the transcultural adaptation of children and adolescents from different ethnic backgrounds. We combine past research with the results of new empirical studies in order to shed light on migrants’ psychological and sociocultural adaptation. Studies comparing young migrants and their German peers in terms of psychological well-being, life satisfaction, and mental health outcome suggest higher rates of emotional and behavioral problems among migrants of most age groups. With regard to adolescent populations between the ages of 14 and 17 years, however, the existence of differences between migrants and natives appears to be less clear. Research has also yielded inconsistent findings regarding the time trajectory of transcultural adaptation among adolescents. The coincidence of acculturation and age-related change is discussed as a possible source of these inconsistencies. Further, we provide an overview of risk and protective factors such as conflicting role expectations and ethnic discrimination, which may cause heightened vulnerability to adverse adaptation outcomes in some groups. Large-scale studies have repeatedly shown migrants of all age groups to be less successful within the German school system, indicating poor sociocultural adaptation. Possible explanations, such as the idiosyncrasies of the German school system, are presented. Our own studies contribute to the understanding of young migrants’ adaptation process by showing that it is their orientation to German culture, rather than the acculturation strategy of integration, that leads to the most positive psychological and sociocultural outcomes. The paper concludes by discussing implications for future cross-cultural research on young migrants and by suggesting recommendations for multicultural policies.

The influence of osteopathic correction on the rate of various rhythms of the body

2019 ◽  
pp. 64-71 ◽  
Author(s):  
A. E. Chernikova ◽  
Yu. P. Potekhina
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Age Groups ◽  
Biomechanical Properties ◽  
Dispersion Analysis ◽  
The Body ◽  
Body Tissues ◽  
Age Related ◽  
Significant Difference ◽  
Before And After

Introduction. An osteopathic examination determines the rate, the amplitude and the strength of the main rhythms (cardiac, respiratory and cranial). However, there are relatively few studies in the available literature dedicated to the influence of osteopathic correction (OC) on the characteristics of these rhythms.Goal of research — to study the influence of OC on the rate characteristics of various rhythms of the human body.Materials and methods. 88 adult osteopathic patients aged from 18 to 81 years were examined, among them 30 men and 58 women. All patients received general osteopathic examination. The rate of the cranial rhythm (RCR), respiratory rate (RR) heart rate (HR), the mobility of the nervous processes (MNP) and the connective tissue mobility (CTM) were assessed before and after the OC session.Results. Since age varied greatly in the examined group, a correlation analysis of age-related changes of the assessed rhythms was carried out. Only the CTM correlated with age (r=–0,28; p<0,05) in a statistically significant way. The rank dispersion analysis of Kruskal–Wallis also showed statistically significant difference in this indicator in different age groups (p=0,043). With the increase of years, the CTM decreases gradually. After the OC, the CTM, increased in a statistically significant way (p<0,0001). The RCR varied from 5 to 12 cycles/min in the examined group, which corresponded to the norm. After the OC, the RCR has increased in a statistically significant way (p<0,0001), the MNP has also increased (p<0,0001). The initial heart rate in the subjects varied from 56 to 94 beats/min, and in 15 % it exceeded the norm. After the OC the heart rate corresponded to the norm in all patients. The heart rate and the respiratory rate significantly decreased after the OC (р<0,0001).Conclusion. The described biorhythm changes after the OC session may be indicative of the improvement of the nervous regulation, of the normalization of the autonomic balance, of the improvement of the biomechanical properties of body tissues and of the increase of their mobility. The assessed parameters can be measured quickly without any additional equipment and can be used in order to study the results of the OC.

Age related volume of cadaver-prostates in Bangladesh

1970 ◽  
Vol 4 (2) ◽  
pp. 74-77
Author(s):  
Rukshana Ahmed ◽  
Shamim Ara
Keyword(s):  
Prostate Gland ◽  
Age Groups ◽  
Clinical Settings ◽  
Cross Sectional ◽  
Medical College ◽  
Age Related ◽  
Group A ◽  
Key Words Prostate ◽  
The Mean ◽  
Group B

Pathological changes in the prostate gland occur commonly with advancing age including inflammation, atrophy, hyperplasia and carcinoma and a change in volume is also evident. Estimation of volume of prostate may be useful in a variety of clinical settings. A cross-sectional descriptive study was designed to see the changes in volume of the prostate with advancing age and done in the Department of Anatomy, Dhaka Medical College, Dhaka from August 2006 to June 2007. The study was performed on 70 post-mortem human prostates collected from the unclaimed dead bodies that were under examination in the Department of Forensic Medicine, Dhaka Medical College, Dhaka. The samples were divided into three age groups; group A (10-20 years), group B (21-40 years) and group C (41-70 years). Volume of the sample was measured by using the ellipsoid formula. The mean ± SD volume of prostate was 7.68 ± 3.64 cm3 in group A, 10.61 ± 3.99 cm3 in group B and 15.40 ± 6.31 cm3 in group C. Mean difference in volume between group A and group C, group B and group C were statistically significant (p<0.001). Statistically significant positive correlation was found between age and volume of prostate (r = + 0.579, p < 0.001). Key Words: Prostate; volume; Bangladeshi. DOI: 10.3329/imcj.v4i2.6501Ibrahim Med. Coll. J. 2010; 4(2): 74-77

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