Skeletal Growth Rates in Porites lutea Corals from Pulau Tinggi, Malaysia

Skeletal records of massive Porites lutea corals sampled from reefs around Malaysia have previously shown average decadal declines in growth rates associated with sea warming. However, there was a variability in growth declines between sites that warrant the need for investigations into more site-specific variations. This study analyzed decade-long (December 2004–November 2014) annual growth records (annual linear extension rate, skeletal bulk density, calcification rate) reconstructed from five massive P. lutea colonies from Pulau Tinggi, Malaysia. Significant non-linear changes in inter-annual trends of linear extension and calcification rates were found, with notable decreases that corresponded to the 2010 El Niño thermal stress episode and a pan-tropical mass coral bleaching event. Coral linear extension and calcification were observed to return to pre-2010 rates by 2012, suggesting the post-stress recovery of P. lutea corals at the study site within 2 years. Although no long-term declines in linear extension and calcification rates were detected, a linear decrease in annual skeletal bulk density by ≈9.5% over the 10-year study period was found. This suggests that although coral calcification rates are retained, the skeletal integrity of P. lutea corals may be compromised with potential implications for the strength of the overall reef carbonate framework. The correlation of coral calcification rates with sea surface temperature also demonstrated site-specific thermal threshold at 29 °C, which is comparable to the regional thermal threshold previously found for the Thai-Malay Peninsula.

The Effect of Space Travel on Bone Metabolism: Considerations on Today’s Major Challenges and Advances in Pharmacology

Microgravity-induced bone loss is currently a significant and unresolved health risk for space travelers, as it raises the likelihood for irreversible changes that weaken skeletal integrity and the incremental onset of fracture injuries and renal stone formation. Another issue related to bone tissue homeostasis in microgravity is its capacity to regenerate following fractures due to weakening of the tissue and accidental events during the accomplishment of particularly dangerous tasks. Today, several pharmacological and non-pharmacological countermeasures to this problem have been proposed, including physical exercise, diet supplements and administration of antiresorptive or anabolic drugs. However, each class of pharmacological agents presents several limitations as their prolonged and repeated employment is not exempt from the onset of serious side effects, which limit their use within a well-defined range of time. In this review, we will focus on the various countermeasures currently in place or proposed to address bone loss in conditions of microgravity, analyzing in detail the advantages and disadvantages of each option from a pharmacological point of view. Finally, we take stock of the situation in the currently available literature concerning bone loss and fracture healing processes. We try to understand which are the critical points and challenges that need to be addressed to reach innovative and targeted therapies to be used both in space missions and on Earth.

Morphological and genomic shifts in mole-rat 'queens' increase fecundity but reduce skeletal integrity

In some mammals and many social insects, highly cooperative societies are characterized by reproductive division of labor, in which breeders and nonbreeders become behaviorally and morphologically distinct. While differences in behavior and growth between breeders and nonbreeders have been extensively described, little is known of their molecular underpinnings. Here, we investigate the consequences of breeding for skeletal morphology and gene regulation in highly cooperative Damaraland mole-rats. By experimentally assigning breeding 'queen' status versus nonbreeder status to age-matched littermates, we confirm that queens experience vertebral growth that likely confers advantages to fecundity. However, they also up-regulate bone resorption pathways and show reductions in femoral mass, which predicts increased vulnerability to fracture. Together, our results show that, as in eusocial insects, reproductive division of labor in mole-rats leads to gene regulatory rewiring and extensive morphological plasticity. However, in mole-rats, concentrated reproduction is also accompanied by costs to bone strength.

Relationship between Bone Quality, Egg Production and Eggshell Quality in Laying Hens at the End of an Extended Production Cycle (105 Weeks)

(1) Background: Nowadays the industry aims to improve lay persistency for extended cycles (100 weeks or longer) to make egg production more sustainable. However, intensive egg production challenges hen health, inducing severe osteoporosis and the incidence of bone fractures. In this study, the relationship between bone quality and egg production, and/or eggshell quality, was evaluated at the end of an extended laying cycle of 100 weeks, comparing groups of hens with different production and eggshell quality parameters; (2) Methods: Quality parameters of egg (as weight, egg white height), eggshell (as thickness, weight, breaking strength, elasticity and microstructure) and tibiae bone (weight, diameter, cortical thickness, ash weight, breaking strength, medullary bone) were determined; (3) Results: Hens from groups with a high egg production and good eggshell quality have poorer bone quality (lower ash weight and lesser amount of medullary bone). However, Pearson’s correlation analysis shows no clear relationship between bone and egg/eggshell parameters. (4) Conclusions: Bone and egg production/eggshell quality are independent and can be improved separately. Medullary bone has an important contribution to bone mechanical properties, being important to accumulate enough bone medullary bone early in life to maintain skeletal integrity and eggshell quality in old hens.

Eph-Ephrin Signaling Mediates Cross-Talk Within the Bone Microenvironment

Skeletal integrity is maintained through the tightly regulated bone remodeling process that occurs continuously throughout postnatal life to replace old bone and to repair skeletal damage. This is maintained primarily through complex interactions between bone resorbing osteoclasts and bone forming osteoblasts. Other elements within the bone microenvironment, including stromal, osteogenic, hematopoietic, endothelial and neural cells, also contribute to maintaining skeletal integrity. Disruption of the dynamic interactions between these diverse cellular systems can lead to poor bone health and an increased susceptibility to skeletal diseases including osteopenia, osteoporosis, osteoarthritis, osteomalacia, and major fractures. Recent reports have implicated a direct role for the Eph tyrosine kinase receptors and their ephrin ligands during bone development, homeostasis and skeletal repair. These membrane-bound molecules mediate contact-dependent signaling through both the Eph receptors, termed forward signaling, and through the ephrin ligands, referred to as reverse signaling. This review will focus on Eph/ ephrin cross-talk as mediators of hematopoietic and stromal cell communication, and how these interactions contribute to blood/ bone marrow function and skeletal integrity during normal steady state or pathological conditions.

State of Fragility Fractures Management during the COVID-19 Pandemic

Osteoporosis is a public health concern all over the world. As a chronic condition, it generally requires prolonged medical interventions to limit the risks of further bone loss, impaired skeletal integrity and the onset of fractures. This problem is further complicated by the fact that the abrupt cessation of some therapies may be associated with an increased risk of harm. It is in this context that the COVID-19 pandemic has caused an unprecedented disruption to the provision of healthcare worldwide, exceeding our worst expectations in terms of the number of lives lost and the rapidity at which consolidated economies and healthcare systems are being significantly damaged. In this review, we assessed the challenges and strategies used in the management of osteoporosis and fragility fracture care during the COVID-19 pandemic. We also examined the available evidence and provided clinical recommendations that will require reassessment as the worldwide response to COVID-19 evolves.