Collagen is the fundamental structural component of a wide range of connective tissues and of the extracellular matrix. It undergoes self-assembly from individual triple-helical proteins into well-ordered fibrils, a process that is key to tissue development and homeostasis, and to processes such as wound healing. Nucleation of this assembly is known to be slowed considerably by pepsin removal of short nonhelical regions that flank collagen's triple helix, known as telopeptides. Using optical tweezers to perform microrheology measurements, we explored the changes in viscoelasticity of solutions of collagen with and without intact telopeptides. Our experiments reveal that intact telopeptides contribute a significant frequency-dependent enhancement of the complex shear modulus. An analytical model of polymers associating to establish chemical equilibrium among higher-order species shows trends in G' and G″ consistent with our experimental observations, including a concentration-dependent crossover in G″/c around 300 Hz. This work suggests that telopeptides facilitate transient intermolecular interactions between collagen proteins, even in the acidic conditions used here.
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http://dx.doi.org/10.1016/j.bpj.2016.10.039 | DOI Listing |
Aging (Albany NY)
January 2025
Department of Medicine, Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City 23142, Taiwan.
Introduction: Bone turnover markers reflected the bone remodeling process and bone health in clinical studies. Studies on variation of bone remodeling markers in different stage CKD were scant, and this study investigated the role of bedside intradialytic cycling in altering concentrations of bone-remodeling markers in patients with end-stage renal disease (ESRD).
Materials And Methods: Participants were segmented into four groups: a group with eGFR >60 ml/min/1.
J Bone Miner Res
January 2025
Radius Health Inc, Boston, MA, United States.
Early increases in bone turnover markers (BTMs) in response to anabolic therapy correlate with 18-month bone mineral density (BMD) increases in postmenopausal women with osteoporosis; however, this relationship has not been assessed in men. In this analysis, the correlation between changes from baseline in fasting intact serum procollagen type I N propeptide (PINP) and serum carboxy-terminal cross-linking telopeptide of type I collagen (CTX) at 1, 3, 6, and 12 months and percent increase from baseline in BMD at 12 months in men from the randomized phase 3 ATOM study (NCT03512262) were evaluated using Pearson's correlation coefficients. The uncoupling index (UI), a measure of the balance between markers of bone formation (PINP) and bone resorption (CTX), with positive UI favoring bone formation, was calculated.
View Article and Find Full Text PDFLife (Basel)
November 2024
Division of Nephrology, Hospital Universitário Clementino Fraga Filho, Federal University of Rio de Janeiro, Rua Prof. Rodolpho Paulo Rocco, 255-Cidade Universitária, Rio de Janeiro 21941-617, RJ, Brazil.
Renal osteodystrophy (ROD) represents histological bone changes in patients with chronic kidney disease and is classified according to turnover and mineralization. This cross-sectional study evaluates several bone biomarkers and their ability to discriminate turnover and mineralization defects in hemodialysis (HD) patients. Bone-specific [BSAP] and total [tAP] alkaline phosphatase, procollagen-1 N-terminal propeptide [P1NP], C-terminal cross-linking telopeptide [CTX], intact [iPTH] and whole [wPTH] parathyroid hormone, sclerostin [SOST], fibroblast growth factor 23 [FGF-23], vitamin D, osteoprotegerin [OPG], and receptor activator of nuclear factor κB ligand [RANKL] were collected before the bone biopsy.
View Article and Find Full Text PDFCureus
November 2024
Department of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, IND.
Background: Disulfiram is widely used to treat alcohol use disorder. Alcohol per se adversely affects bone health. In the experimental study, disulfiram leads to apoptosis of osteoblast and significant osteopenia in adult rats.
View Article and Find Full Text PDFJ Bone Miner Res
December 2024
The Health Research Unit Zimbabwe, Biomedical Research and Training Institute, 8 Ross Avenue, Harare, Zimbabwe.
Vitamin D dysregulation can occur in people living with HIV, disrupting calcium homeostasis, and bone turnover. We aimed to investigate the potential mechanisms by which vitamin D regulates bone turnover in adolescents living with perinatally-acquired HIV (ALWH) in Southern Africa. A pre-planned secondary analysis was performed of baseline data from the vitamin D for adolescents with HIV to reduce musculoskeletal morbidity and immunopathology trial (PACTR20200989766029) which enrolled ALWH (11-19 yr) taking antiretroviral therapy for ≥6 mo, and recorded socio-demographic, clinical and dietary data.
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