In a discovery that seems counterintuitive, a study appearing in the May 21st Journal of Biological Chemistry has found that tendons in high-stress and strain areas, like the Achilles tendon, actually repair themselves less frequently than low-stress tendons. This study sheds some light on the increased susceptibility of certain tendons to injury during aging.
Tendons, composed of collagen and other proteins, serve to connect muscle to bone and thus are vital for movement. Considering their strenuous activity, tendons need to be continually repairing collagen damage to avoid buildup of degraded proteins that could cause serious complications. Not all tendons are equal though; some tendons, like those in the hand, are primarily used to maintain proper limb placement while others, like the Achilles tendon in humans and the superficial digital flexor tendon (SDFT) in horses, have to bear a lot of weight and strain.
It would be expected that high-strain tendons would repair more frequently, yet Dr Helen Birch at University College London and colleagues examined protein turnover in the tendons of horses of various ages and found that the high-strain SDFT (located at the rear of the limb) repairs much less frequently than the low-strain common digital extensor tendon (CDET, located at the front of the limb). Birch and colleagues used an approach called amino acid racemization to measure protein age in the horse tendons. Amino acids are always incorporated into proteins in a specific orientation called the L-form, but afterwards can spontaneously convert into a mirror image called the D-form. Therefore, by measuring the ratio of L and D amino acids over time, one can estimate the half-life of a protein.
Through this method, the researchers found that non-collagen proteins in tendon have an average half life of 2.2 years in SDFT and 3.5 years in CDET, which would be expected. However, SDFT collagen had a half-life of 198 years, compared to 34 years for CDET collagen. That means that every year, only 0.25% of the injury-prone collagen gets replaced in SDFT tissue. Over time, degraded protein and other mechanically-induced micro-damage could reduce the overall integrity of the tendon, which could lead to large-scale injuries. As to why the body would seemingly put its more important tendons at greater risk, the researchers suggest that it may be a trade off; too much repair may compromise the strength and stiffness of these tendons which are used heavily, so the body tries to preserve their structural integrity at the expense of increased injury risk later in life.
From the article: "Aspartic Acid racemization and collagen degradation markers reveal an accumulation of damage in tendon collagen which is enhanced with aging" by Chavaunne T. Thorpe, Ian Streeter, Gina L. Pinchbeck, Allen E. Goodship, Peter D. Clegg and Helen L. Birch
Corresponding Author: Helen Birch, Institute of Orthopaedics and Musculoskeletal Science, University College London, UK; e-mail: email@example.com
Nick Zagorski | EurekAlert!
During HIV infection, antibody can block B cells from fighting pathogens
14.08.2018 | NIH/National Institute of Allergy and Infectious Diseases
First study on physical properties of giant cancer cells may inform new treatments
14.08.2018 | Brown University
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
14.08.2018 | Information Technology
14.08.2018 | Life Sciences
14.08.2018 | Life Sciences