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Bones and fractures
Published in Henry J. Woodford, Essential Geriatrics, 2022
Plain X-rays of the thoracic and lumbar spine can be used to detect vertebral fractures in people reporting height loss or with clinical evidence of kyphosis. Quantitative computerised tomography (CT) measurements allow accurate bone density assessment but its use is associated with increased costs and radiation exposure. Quantitative ultrasound measurements are taken at peripheral sites, such as the calcaneum. It is a simple, quick and radiation-free technique but its accuracy has not been fully proven. A bone biopsy may be considered when there is diagnostic uncertainty. This can exclude certain conditions, including malignancy, but is rarely performed. Biochemical markers of bone turnover have been detected in serum and urine samples. They may have the advantage of reflecting responses to treatment before BMD changes are detectable on DEXA scans. They include bone-specific ALP, various breakdown products of collagen and the non-collagenous bone protein called osteocalcin. They are often utilised in the setting of clinical trials but are not recommended for use in routine clinical practice.21
Diabetic Nephropathy
Published in Jahangir Moini, Matthew Adams, Anthony LoGalbo, Complications of Diabetes Mellitus, 2022
Jahangir Moini, Matthew Adams, Anthony LoGalbo
There may be abnormalities of calcium, parathyroid hormone (PTH), phosphate, and vitamin D metabolism. Renal osteodystrophy is also possible. Reduced renal production of the active vitamin D hormone calcitriol adds to hypocalcemia. Reduced renal excretion of phosphate causes hyperphosphatemia. Secondary hyperparathyroidism is often seen, developing in kidney failure prior to abnormal calcium or phosphate concentrations manifesting. Therefore, it is important to monitor PTH in patients with moderate CKS prior to hyperphosphatemia occurring. Renal osteodystrophy is abnormal bone mineralization. It occurs because of a deficiency of calcitriol, hyperparathyroidism, excessive serum phosphate, or low to normal serum calcium. There is usually increased bone turnover because of osteitis fibrosa, a hyperparathyroid bone disease. There may be decreased bone turnover, however, caused by an adynamic disease from increased suppression of the parathyroid glands, or osteomalacia. If there is a calcitriol deficiency, this may result in osteomalacia or osteopenia.
Biochemistry of Exercise Training: Effects on Bone
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Panagiota Klentrou, Rozalia Kouvelioti
In understanding the pathophysiology of osteoporosis, bone turnover is an essential concept because it is this process which governs how bone is replaced, lost, or gained at certain sites and ultimately determines bone's three-dimensional structure (35). Bone turnover is considered a continuous process of constant removal and replacement of volumes of bone tissue, conducted by osteoclasts and osteoblasts, in both cortical and trabecular bone (35). Under normal conditions, the processes of bone formation and resorption are coupled to one another, and the maintenance of skeletal balance is achieved through the action of various hormones and local mediators (140). Osteoclasts burrow into bone, forming cavities where osteoblasts can deposit new bone resulting in the formation of new osteons. This process also results in the liberation of calcium and phosphate into the bloodstream. Bone homeostasis is achieved when the amount of bone resorbed is replaced by a similar amount of newly synthesized bone. A sustained increase in the ratio of osteoclast to osteoblast activity may eventually result in osteoporosis. Therefore, the activity of osteoclasts and osteoblasts is not only important in establishing the calcium and phosphate levels necessary for particular bodily functions but also in maintaining the structural integrity of bone.
Isoorientin ameliorates osteoporosis and oxidative stress in postmenopausal rats
Published in Pharmaceutical Biology, 2022
Zhilin Cao, Wei Liu, Benjun Bi, Hao Wu, Gong Cheng, Zhongyuan Zhao
Bone metabolism mainly involves osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Bone metabolism can reflect changes in bone turnover, metabolism, and remodelling (Hou et al. 2020). Osteoblasts secrete BGP. Changes in serum BGP levels reflect osteoblasts activity. TRACP-5b reflects the number and functional activity of osteoclasts (Yang et al. 2018). The levels of ALP, TRACP-5b, and CTx-I in the model control group increased, while the level of BGP decreased, indicating that after ovariectomy, the activities of osteoclasts and osteoblasts increased, and the rate of bone turnover increased, leading to increased bone loss. After medication intervention, compared with the model control group, the serum ALP, TRACP-5b, and CTx-I levels of the oestradiol and isoorientin groups were significantly reduced, and the level of BGP was decreased, suggesting that oestradiol and isoorientin treatment can affect osteoclast and osteoblast activities and improve bone metabolism. A previous study investigated the effective components of Acer palmatum cv. Atropurpureum (Sapindaceae) leaves, including isoorientin, which has health-promoting effects that help prevent osteoporosis by inhibiting osteoclastogenesis and facilitating osteoblastogenesis (Kuriya et al. 2019). Our study also indicated that isoorientin treatment inhibited osteoclastogenesis and enhanced osteoblastogenesis.
Irradiation affects the structural, cellular and molecular components of jawbones
Published in International Journal of Radiation Biology, 2022
Sridhar Reddy Padala, Bina Kashyap, Hannah Dekker, Jopi J. W. Mikkonen, Anni Palander, Nathalie Bravenboer, Arja M. Kullaa
Bone remodeling is a dynamic process; it occurs throughout the lifetime of an organism in a coordinated and tightly regulated manner in order to maintain a functional skeletal system. The bone remodeling process involves two opposing processes – bone resorption and bone formation (Mello et al. 2018) executed by three distinct cell types present in bone cells; osteoclasts, osteoblasts, and osteocytes. The physiological process of bone remodeling is based on the interactions not only between these cells but also multiple molecular agents including hormones, growth factors, and cytokines (Feng and McDonald 2011). Bone turnover is necessary to allow new bone to replace the existing bone, ensuring the adaptation of the newly formed bone to its microenvironment (Misch et al. 2001). Exposure to radiation causes a deterioration of the quantity and quality of bone by interfering with bone remodeling/turnover activity which ultimately impacts on the bone’s microstructure (Costa and Reagan 2019).
Three-year results of denosumab treatment for osteoporosis in women with rheumatoid arthritis and primary osteoporosis: A clinical observational study
Published in Modern Rheumatology, 2021
Takeshi Mochizuki, Koichiro Yano, Katsunori Ikari, Ryo Hiroshima, Yuki Nasu, Ken Okazaki
The present study could not identify any predictors of efficacy for the increase in lumbar spine BMD in both groups. Previous reports on patients with RA showed that an increase in the lumbar spine BMD was related to its BMD at baseline and P1NP from baseline to year 1 and ΔP1NP from month 6 to year 2 [18,20,33]. It may have been difficult to identify long-term predictors of improvement in the lumbar spine BMD using observed case analysis in this study. In contrast, in the RA group, total hip BMD and T-score at baseline and ΔP1NP at year 3 were predictors of efficacy for the increase in total hip BMD, whereas TRACP-5b at baseline was a predictor of efficacy for the increase in femoral neck BMD. Based on the present results, changes in bone turnover marker levels tend to vary at different sites. These results may be associated with the different proportions of cortical and trabecular bones in the lumbar spine, total hip and femoral neck.