Biochemical markers of bone turnover and osteoporosis management

Microwave-assisted synthesis of novel steroidal heterocyclic analogs as potent inhibitors of RANKL-induced osteoclastogenesis

Osteoporosis is a significant public health issue in our aging population. It is an excessive bone resorption condition brought on by osteoclastogenesis, which makes bones more brittle. In the present work, a series of novel heterosteroidal derivatives have been synthesized using the microwave technique and were evaluated as antiosteoclastogenic agents. The structures of the newly synthesized compounds have been confirmed using analytical and spectral data. The antiosteoclastogenic activity of the newly synthesized compounds was estimated in vitro against osteoclast-differentiated cells from the RAW 264.7 cell line. The pregnenolone dimer 10, the pyridinotestosterone derivative 2, and the phenylnicotinonitrile pregnenolone derivative 8a attained the most promising antiosteoclastogenic activity displaying IC50 (the half maximal inhibitory concentration) values of 5.45 ± 5.30, 11.88 ± 2.09, and 13.40 ± 3.00 µM, respectively, in comparison with dimethyl itaconate (IC50  = 17.76 ± 3.20 µM) and alendronate (IC50  = 4.48 ± 1.89 µM) as reference compounds. Finally, an in silico ADME (Absorption, Distribution, Metabolism, and Excretion) study was conducted to evaluate the synthesized compounds' pharmacokinetic and drug-likeness properties. The results manifested that almost all the investigated compounds' properties were compatible with the specified optimal range, which indicates their reassuring pharmacokinetic properties.

Effects of excessive or restricted phosphorus and calcium intake during early life on markers of bone architecture and composition in pigs

Sufficient supply of pigs with calcium (Ca) and phosphorus (P) is essential for animal health and welfare during the growth period. However, the P content in animal manure is considered as a cause of massive environmental problems in soil and aquatic ecosystems. To complement previous findings, the objective of this study is the investigation of effects of a reduced and increased Ca and P supplementation on bone mineralization and bone structure compared with the current dietary recommendation. Another aim is to find possible serum markers that would allow the assessment of adequacy of P supply for bone health during growth. The result validated that the recommended Ca and P supply is sufficient, without the addition of microbial phytases. However, addition of P has no further beneficial effects on bone stability, while P supplementation below the recommended level affects bone development and growth performance. Reduced P levels have consequences for cancellous bone density and trabecular architecture. Further fine-tuning of the P supply in conjunction with an appropriate Ca supply will contribute to a reduction in P waste and associated environmental impact while maintaining animal health and welfare.

Japanese medaka: a non-mammalian vertebrate model for studying sex and age-related bone metabolism in vivo

Background

In human, a reduction in estrogen has been proposed as one of the key contributing factors for postmenopausal osteoporosis. Rodents are conventional models for studying postmenopausal osteoporosis, but the major limitation is that ovariectomy is needed to mimic the estrogen decline after menopause. Interestingly, in medaka fish (Oryzias latipes), we observed a natural drop in plasma estrogen profile in females during aging and abnormal spinal curvature was apparent in old fish, which are similar to postmenopausal women. It is hypothesized that estrogen associated disorders in bone metabolism might be predicted and prevented by estrogen supplement in aging O. latipes, which could be corresponding to postmenopausal osteoporosis in women.

Principal findings

In O. latipes, plasma estrogen was peaked at 8 months old and significantly declined after 10, 11 and 22 months in females. Spinal bone mineral density (BMD) and micro-architecture by microCT measurement progressively decreased and deteriorated from 8 to 10, 12 and 14 months old, which was more apparent in females than the male counterparts. After 10 months old, O. latipes were supplemented with 17α-ethinylestradiol (EE2, a potent estrogen mimic) at 6 and 60 ng/mg fish weight/day for 4 weeks, both reduction in spinal BMD and deterioration in bone micro-architecture were significantly prevented. The estrogenic effect of EE2 in O. latipes was confirmed by significant up-regulation of four key estrogen responsive genes in the liver. In general, bone histomorphometric analyses indicated significantly lowered osteoblasts and osteoclasts numbers and surfaces on vertebrae of EE2-fed medaka.

Significance

We demonstrate osteoporosis development associated with natural drop in estrogen level during aging in female medaka, which could be attenuated by estrogen treatment. This small size fish is a unique alternative non-mammalian vertebrate model for studying estrogen-related molecular regulation in postmenopausal skeletal disorders in vivo without ovariectomy.

Urbanization of black South African women may increase risk of low bone mass due to low vitamin D status, low calcium intake, and high bone turnover

Globally, rural to urban migration is accompanied by changes in dietary patterns and lifestyle that have serious health implications, including development of low bone mass. We hypothesized that serum 25 (OH) vitamin D3 (25[OH]D3) levels will be lower, bone turnover higher, and nutrition inadequate in urban postmenopausal black women, increasing risk for low bone mass. We aimed to assess the prevalence of risk factors for low bone mass in 1261 black women from rural and urban areas in the North West Province of South Africa (Prospective Urban and Rural Epidemiology-South Africa project). Fasting blood samples were taken; and participants were interviewed to complete questionnaires on self-reported diseases, fractures, and dietary intakes. Bone health markers were assessed in a subgroup of 658 women older than 45 years. Specific lifestyle risk factors identified were inactivity, smoking, injectable progestin contraception use, and high alcohol consumption. Dietary risk factors identified were low calcium and high animal protein, phosphorous, and sodium intakes. The 25(OH)D3 and C-terminal telopeptide (CTX) levels were significantly higher in the rural vs the urban women older than 50 years. Parathyroid hormone (PTH) levels increased with age in both groups. The 25(OH)D levels were inversely correlated with CTX and PTH in rural women. In urban women, PTH and CTX were correlated while dietary calcium was inversely correlated with CTX and PTH with 25(OH)D3. The combination of low dietary calcium (<230 mg/d), marginally insufficient 25(OH)D3 status, and raised PTH may result in increased bone resorption. Further research is required to assess bone health and fracture risk in black African women.