scholarly journals Regional stiffening with aging in tibialis anterior tendons of mice occurs independent of changes in collagen fibril morphology

2011 ◽  
Vol 111 (4) ◽  
pp. 999-1006 ◽  
Author(s):  
Lauren K. Wood ◽  
Ellen M. Arruda ◽  
Susan V. Brooks
Keyword(s):  
Mechanical Properties ◽  
Old Age ◽  
Collagen Fibril ◽  
Tibialis Anterior ◽  
Isometric Force ◽  
External Loading ◽  
Dependent Manner ◽  
Age Related ◽  
Increased Risk ◽  
Fibril Morphology

The incidence of tendon degeneration and rupture increases with advancing age. The mechanisms underlying this increased risk remain unknown but may arise because of age-related changes in tendon mechanical properties and structure. Our purpose was to determine the effect of aging on tendon mechanical properties and collagen fibril morphology. Regional mechanical properties and collagen fibril characteristics were determined along the length of tibialis anterior (TA) tendons from adult (8- to 12-mo-old) and old (28- to 30-mo-old) mice. Tangent modulus of all regions along the tendons increased in old age, but the increase was substantially greater in the proximal region adjacent to the muscle than in the rest of the tendon. Overall end-to-end modulus increased with old age at maximum tendon strain (799 ± 157 vs. 1,419 ± 91 MPa) and at physiologically relevant strain (377 ± 137 vs. 798 ± 104 MPa). Despite the dramatic changes in tendon mechanical properties from adulthood to old age, collagen fibril morphology and packing fraction remained relatively constant in all tendon regions examined. Since tendon properties are influenced by their external loading environment, we also examined the effect of aging on TA muscle contractile properties. Maximum isometric force did not differ between the age groups. We conclude that TA tendons stiffen in a region-dependent manner throughout the life span, but the changes in mechanical properties are not accompanied by corresponding changes in collagen fibril morphology or force-generating capacity of the TA muscle.

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.

Stress Dependent Collagen Fibril Diameter Distribution in Human Aortic Valves

2007 ◽  
Author(s):  
Angelique Balguid ◽  
Anita Mol ◽  
Niels Driessen ◽  
Carlijn Bouten ◽  
Frank Baaijens
Keyword(s):  
Mechanical Properties ◽  
Collagen Fibril ◽  
Diameter Distribution ◽  
Connective Tissues ◽  
Aortic Valves ◽  
Cross Links ◽  
Fibril Morphology ◽  
Stress Dependent ◽  
Collagenous Tissues ◽  
Fibril Diameter

The mechanical properties of collagenous tissues are known to depend on a wide variety of factors, such as the type of tissue and the composition of its extracellular matrix. Relating mechanical roles to individual matrix components in such a complex system is difficult, if not impossible. However, as collagen is the main load bearing component in connective tissues, the relation between collagen and tissue biomechanics has been studied extensively in various types of tissues. The type of collagen, the amount and type of inter- and intramolecular covalent cross-links and collagen fibril morphology are involved in the tissues mechanical behavior (Beekman et al., 1997; Parry et al., 1978; Avery and Bailey, 2005). From literature it is known that the the collagen fibril diameter distribution can be directly related to the mechanical properties of the tissue. In particular, the diameter distribution of collagen fibrils is largely determined by the tissues requirement for tensile strength and elasticity (Parry et al., 1978).

scholarly journals Nanostructural and mechanical changes in the sclera following proteoglycan depletion

2018 ◽  
Vol 2 (2) ◽  
pp. 14-17
Author(s):  
Zhuola Zhuola ◽  
Steve Barrett ◽  
Yalda Ashraf Kharaz ◽  
Riaz Akhtar
Keyword(s):  
Mechanical Properties ◽  
Collagen Fibril ◽  
Enzymatic Degradation ◽  
Ocular Tissues ◽  
Force Microscopy ◽  
Nanomechanical Properties ◽  
Atomic Force ◽  
Fibril Morphology

The mechanical properties of ocular tissues, such as the sclera, have a major impact on healthy eye function, and are governed by the properties and composition of the microstructural components. For example, biomechanical degradation associated with myopia occurs alongside a reduction of proteoglycans (PGs). In this study, the role of PG degradation in the nanomechanical properties of the porcine sclera is explored. In-vitro enzymatic degradation of PGs was conducted with α-amylase and chondroitinase ABC enzymes. Collagen fibril morphology and nanomechanical stiffness were measured with atomic force microscopy (AFM). The elastic modulus of the tissue was reduced in all enzyme-treated samples relative to controls. In addition, collagen fibril organization was disrupted by PG depletion. Our data demonstrate that PGs play an important role in determining not only the mechanical properties at these length scales, but also collagen fibril arrangement.

Balance Decrements Are Associated With Age-Related Muscle Property Changes

2014 ◽  
Vol 30 (4) ◽  
pp. 555-562 ◽  
Author(s):  
Christopher J. Hasson ◽  
Richard E.A. van Emmerik ◽  
Graham E. Caldwell
Keyword(s):  
Mechanical Properties ◽  
Older Adults ◽  
Comprehensive Evaluation ◽  
Isometric Force ◽  
Dynamic Balance ◽  
Balance Performance ◽  
Age Related ◽  
Ankle Muscle ◽  
Property Changes ◽  
Maximal Isometric Force

In this study, a comprehensive evaluation of static and dynamic balance abilities was performed in young and older adults and regression analysis was used to test whether age-related variations in individual ankle muscle mechanical properties could explain differences in balance performance. The mechanical properties included estimates of the maximal isometric force capability, force-length, force-velocity, and series elastic properties of the dorsiflexors and individual plantarflexor muscles (gastrocnemius and soleus). As expected, the older adults performed more poorly on most balance tasks. Muscular maximal isometric force, optimal fiber length, tendon slack length, and velocity-dependent force capabilities accounted for up to 60% of the age-related variation in performance on the static and dynamic balance tests. In general, the plantarflexors had a stronger predictive role than the dorsiflexors. Plantarflexor stiffness was strongly related to general balance performance, particularly in quiet stance; but this effect did not depend on age. Together, these results suggest that age-related differences in balance performance are explained in part by alterations in muscular mechanical properties.

Gastrointestinal Microbiota and Their Contribution to Healthy Aging

2016 ◽  
Vol 34 (3) ◽  
pp. 194-201 ◽  
Author(s):  
Anna Maria Mello ◽  
Giulia Paroni ◽  
Julia Daragjati ◽  
Alberto Pilotto
Keyword(s):  
Old Age ◽  
Healthy Aging ◽  
Adverse Outcomes ◽  
Microbiota Composition ◽  
Older Individuals ◽  
Gastrointestinal Microbiota ◽  
Targeted Interventions ◽  
Age Related ◽  
Increased Risk ◽  
Older Subjects

Studies on populations at different ages have shown that after birth, the gastrointestinal (GI) microbiota composition keeps evolving, and this seems to occur especially in old age. Significant changes in GI microbiota composition in older subjects have been reported in relation to diet, drug use and the settings where the older subjects are living, that is, in community nursing homes or in a hospital. Moreover, changes in microbiota composition in the old age have been related to immunosenescence and inflammatory processes that are pathophysiological mechanisms involved in the pathways of frailty. Frailty is an age-related condition of increased vulnerability to stresses due to the impairment in multiple inter-related physiologic systems that are associated with an increased risk of adverse outcomes, such as falls, delirium, institutionalization, hospitalization and death. Preliminary data suggest that changes in microbiota composition may contribute to the variations in the biological, clinical, functional and psycho-social domains that occur in the frail older subjects. Multidimensional evaluation tools based on a Comprehensive Geriatric Assessment (CGA) have demonstrated to be useful in identifying and measuring the severity of frailty in older subjects. Thus, a CGA approach should be used more widely in clinical practice to evaluate the multidimensional effects potentially related to GI microbiota composition of the older subjects. Probiotics have been shown to be effective in restoring the microbiota changes of older subjects, promoting different aspects of health in elderly people as improving immune function and reducing inflammation. Whether modulation of GI microbiota composition, with multi-targeted interventions, could have an effect on the prevention of frailty remains to be further investigated in the perspective of improving the health status of frail ‘high risk' older individuals.

scholarly journals Inactivity and Skeletal Muscle Metabolism: A Vicious Cycle in Old Age

2020 ◽  
Vol 21 (2) ◽  
pp. 592 ◽  
Author(s):  
Elena Rezuş ◽  
Alexandra Burlui ◽  
Anca Cardoneanu ◽  
Ciprian Rezuş ◽  
Cătălin Codreanu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Old Age ◽  
Muscle Metabolism ◽  
The Elderly ◽  
Low Grade ◽  
Skeletal Muscle Metabolism ◽  
Telomere Attrition ◽  
Age Related ◽  
Increased Risk ◽  
Effects Of Aging

Aging is an inevitable and gradually progressive process affecting all organs and systems. The musculoskeletal system makes no exception, elderly exhibit an increased risk of sarcopenia (low muscle mass),dynapenia (declining muscle strength), and subsequent disability. Whereas in recent years the subject of skeletal muscle metabolic decline in the elderly has been gathering interest amongst researchers, as well as medical professionals, there are many challenges yet to be solved in order to counteract the effects of aging on muscle function efficiently. Noteworthy, it has been shown that aging individuals exhibit a decline in skeletal muscle metabolism, a phenomenon which may be linked to a number of predisposing (risk) factors such as telomere attrition, epigenetic changes, mitochondrial dysfunction, sedentary behavior (leading to body composition alterations), age-related low-grade systemic inflammation (inflammaging), hormonal imbalance, as well as a hypoproteic diet (unable to counterbalance the repercussions of the age-related increase in skeletal muscle catabolism). The present review aims to discuss the relationship between old age and muscle wasting in an effort to highlight the modifications in skeletal muscle metabolism associated with aging and physical activity.

scholarly journals Awareness of Age-Related Change as a Behavioral Determinant of Survival Time in Very Old Age

2021 ◽  
Vol 12 ◽  
Author(s):  
Roman Kaspar ◽  
Hans-Werner Wahl ◽  
Manfred Diehl
Keyword(s):  
Survival Time ◽  
Old Age ◽  
Perceived Control ◽  
Panel Study ◽  
Late Life ◽  
Independent Effect ◽  
Very Old ◽  
Age Related ◽  
Increased Risk ◽  
Perceived Age

Although research on the association between subjective views of aging (VOA) and survival is scarce, more negative VOA have been found to be associated with increased all-cause mortality, even after controlling for possible confounders. Longitudinal studies on the predictive association of VOA with survival in individuals aged 80 years or older are, however, very limited. Thus, the aim of this study was to link adults’ awareness of age-related change (AARC), a multidimensional measure of adults’ subjective VOA, to survival time across a 3.5-year observation interval in advanced old age. To put the AARC construct in context, the study also considered related psychosocial concepts (i.e., perceived control and appraisal of life) essential for coping with late-life challenges as potential behavioral predictors of longevity. Data came from a representative panel study that included persons living in community and institutional settings. A total of 1,863 interviews were conducted at wave 1. This study used meta-data from wave 2 fieldwork 2 years after the initial assessment and death records obtained during panel maintenance after 3.5 years to estimate determinants of survival. Results showed that loss-related VOA indicated increased risk to survival, whereas gain-related VOA were predictive of longer survival. Both perceived age-related losses and perceived age-related gains exerted a significant independent effect on late-life mortality over and above socio-demographic background characteristics, perceived control, engagement with life, as well as health status. These findings suggest that the multidimensional examination of very old adults’ VOA may help to better understand successful longevity in the Fourth Age.

scholarly journals Age-related dataset on the mechanical properties and collagen fibril structure of tendons from a murine model

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Kheng Lim Goh ◽  
David F. Holmes ◽  
Yin Hui Lu ◽  
Karl E. Kadler ◽  
Peter P. Purslow
Keyword(s):  
Mechanical Properties ◽  
Murine Model ◽  
Collagen Fibril ◽  
Fibril Structure ◽  
Age Related
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