Bone
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Comparative Study
Comparison of effects of alfacalcidol and alendronate on mechanical properties and bone collagen cross-links of callus in the fracture repair rat model.
Both bone density and quality are important determinants of bone strength. Bone quality is prescribed by matrix characteristic including collagen cross-linking and bone structural characteristics and is important in reinforcement of bone strength. We investigated the effects of alfacalcidol (ALF), a prodrug of calcitriol, and alendronate (ALN), a bisphosphanate, on the mechanical properties and content of enzymatic cross-links in femoral bone using a fracture repair rat model. ⋯ Of particular interest, the Pyr-to-Dpyr ratio was significantly decreased by ALF administration, suggesting that ALF but not ALN normalized the enzymatic cross-link patterns in fractured bone to the control level. In conclusion, ALN and ALF treatment increased bone strength via the distinctive effect on bone mass and quality. ALN formed larger calluses and increased enzymatic cross-links despite delayed woven bone remodeling into lamellar bone, whereas ALF treatment induced lamellar bone formation coincided with increasing in the enzymatic cross-linking and normalizing the cross-link pattern in callus to native bone pattern.
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Comparative Study
Intermittent PTH(1-34) does not increase union rates in open rat femoral fractures and exhibits attenuated anabolic effects compared to closed fractures.
Intermittent Parathyroid Hormone (PTH)((1-34)) has an established place in osteoporosis treatment, but also shows promising results in models of bone repair. Previous studies have been dominated by closed fracture models, where union is certain. One of the major clinical needs for anabolic therapies is the treatment of open and high energy fractures at risk of non-union. ⋯ In conclusion, intermittent PTH((1-34)) produced significant increases in callus size and strength in closed fractures, but failed to increase the rate of union in an open fracture model. In the open fractures that did unite, a muted response to PTH was seen compared to closed fractures. Further research is required to determine if PTH((1-34)) is an appropriate anabolic treatment for open fractures.
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Comparative Study
Hydrolyzed collagen improves bone metabolism and biomechanical parameters in ovariectomized mice: an in vitro and in vivo study.
Collagen has an important structural function in several organs of the body, especially in bone and cartilage. The aim of this study was to investigate the effect of hydrolyzed collagen on bone metabolism, especially in the perspective of osteoporosis treatment and understanding of its mechanism of action. An in vivo study was carried out in 12-week-old female C3H/HeN mice. ⋯ Hydrolyzed collagens (2 or 5 kDa) in the tissue culture medium did not have any significant effects on cell growth as compared to controls. However, there was a significant and dose-dependent increase in ALP activity, a well-known marker of osteogenesis, and a decrease in octeoclast activity in primary culture of bone cells cultured with hydrolyzed collagens (2 kDa only) as compared to the control. It is concluded that dietary hydrolyzed collagen increases osteoblast activity (as measured in primary tissue culture), which acts on bone remodeling and increases the external diameter of cortical areas of the femurs.
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Comparative Study
A phenotypically restricted set of primary afferent nerve fibers innervate the bone versus skin: therapeutic opportunity for treating skeletal pain.
Although musculoskeletal pain is one of the most common causes of chronic pain and physical disability in both developing and developed countries, relatively little is known about the nerve fibers and mechanisms that drive skeletal pain. Small diameter sensory nerve fibers, most of which are C-fiber nociceptors, can be separated into two broad populations: the peptide-rich and peptide-poor nerve fibers. Peptide-rich nerve fibers express substance P (SP) and calcitonin gene-related peptide (CGRP). ⋯ Whereas the skin is richly innervated by CGRP(+), SP(+), P(2)X(3)(+) and Mrgprd(+) sensory nerve fibers, the bone marrow, mineralized bone and periosteum receive a significant innervation by SP(+) and CGRP(+), but not Mrgprd(+) and P(2)X(3)(+) nerve fibers. This lack of redundancy in the populations of C-fibers that innervate the bone may present a unique therapeutic opportunity for targeting skeletal pain as the peptide-rich and peptide-poor sensory nerve fibers generally express a different repertoire of receptors and channels to detect noxious stimuli. Thus, therapies that target the specific types of C-nerve fibers that innervate the bone may be uniquely effective in attenuating skeletal pain as compared to skin pain.
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During childhood and adolescence, bone mass and lean body mass (LBM) increase till a plateau is reached. In this longitudinal and cross-sectional study, the age of reaching the plateau was evaluated for lumbar spine and total body bone mass measurements and lean body mass. The association between fractures and bone mineral density (BMD) was studied. ⋯ Peak BMD and peak LBM were attained between 18 and 20 years in females and between 18 and 23 years in males in this study using longitudinal and cross sectional data in the age range of 4 to 30 years. A significantly lower total body BMD was seen in participants who had had a fracture and a lower lumbar spine BMD and BMAD in females who had had a fracture. Lumbar spine BMAD Z-score seems to be a good predictor for future fractures.