Electrospun chitosan membranes subjected to post-spinning processes using either triethylamine/tert-butyloxycarbonyl (TEA/tBOC) or butyryl-anhydride (BA) modifications to maintain nanofiber structure have exhibited potential for use in guided bone regeneration applications. The aim of this study was to evaluate ability of the modified membranes to support healing of bone-grafted defects as compared to a commercial collagen membrane.
Material properties of bighorn sheep (Ovis canadensis) horncore bone with implications for energy absorption during impacts
Bighorn sheep rams participate in high impact head-butting without overt signs of brain injury, thus providing a naturally occurring animal model for studying brain injury mitigation. Previously published finite element modeling showed that both the horn and bone materials play important roles in reducing brain cavity accelerations during ramming.
Ablation of Enpp6 results in transient bone hypomineralization
Biomineralization is a fundamental process key to the development of the skeleton. The phosphatase orphan phosphatase 1 (PHOSPHO1), which likely functions within extracellular matrix vesicles, has emerged as a critical regulator of biomineralization. The biochemical pathways which generate intravesicular PHOSPHO1 substrates are however currently unknown. We hypothesized that the enzyme ectonucleotide pyrophosphatase/phosphodiesterase (ENPP6) is an upstream source of PHOSPHO1 substrate.
A selected small molecule prevents inflammatory osteolysis through restraining osteoclastogenesis by modulating PTEN activity
Inflammatory osteolysis is a severe infectious bone disorder that occurs during orthopaedic surgery and is caused by disruptions in the dynamic balance of bone matrix homeostasis, which makes this condition a burden on surgical procedures. Developing novel therapeutic drugs about inhibiting excessive osteoclastogenesis acts as an efficient approach to preventing inflammatory bone destruction.
Material properties of bighorn sheep (Ovis canadensis) horncore bone with implications for energy absorption during impacts
AUTHORS
Luca H.Fuller, Seth W.Donahue
ABSTRACT
Bighorn sheep rams participate in high impact head-butting without overt signs of brain injury, thus providing a naturally occurring animal model for studying brain injury mitigation. Previously published finite element modeling showed that both the horn and bone materials play important roles in reducing brain cavity accelerations during ramming. However, in that study the elastic modulus of bone was assumed to be similar to that of human bone since the modulus of ram bone was unknown. Therefore, the goal of this study was to quantify the mechanical properties, mineral content, porosity, and microstructural organization of horncore cortical bone from juvenile and adult rams. Mineral content and elastic modulus increased with horn size, and porosity decreased. However, modulus of toughness did not change with horn size. This latter finding raises the possibility that the horncore cortical bone has not adapted exceptional toughness despite an extreme loading environment and may function primarily as an interface material between the horn and the porous bone within the horncore. Thus, geometric properties of the horn and horncore, including the porous bone architecture, may be more important for energy absorption during ramming than the horncore cortical bone. Results from this study can be used to improve accuracy of finite element models of bighorn sheep ramming to investigate these possibilities moving forward.
Ferroptosis Mediates Cuprizone-Induced Loss of Oligodendrocytes and Demyelination
AUTHORS
Priya Jhelum, Eva Santos-Nogueira, Wulin Teo, Alice Haumont, Isadora Lenoël, Peter K. Stys and Samuel David
ABSTRACT
Multiple sclerosis (MS) is a chronic demyelinating disease of the CNS. Cuprizone (CZ), a copper chelator, is widely used to study demyelination and remyelination in the CNS, in the context of MS. However, the mechanisms underlying oligodendrocyte (OL) cell loss and demyelination are not known. As copper-containing enzymes play important roles in iron homeostasis and controlling oxidative stress, we examined whether chelating copper leads to disruption of molecules involved in iron homeostasis that can trigger iron-mediated OL loss. We show that giving mice (male) CZ in the diet induces rapid loss of OL in the corpus callosum by 2 d, accompanied by expression of several markers for ferroptosis, a relatively newly described form of iron-mediated cell death. In ferroptosis, iron-mediated free radicals trigger lipid peroxidation under conditions of glutathione insufficiency, and a reduced capacity to repair lipid damage. This was further confirmed using a small-molecule inhibitor of ferroptosis that prevents CZ-induced loss of OL and demyelination, providing clear evidence of a copper-iron connection in CZ-induced neurotoxicity. This work has wider implications for disorders, such as multiple sclerosis and CNS injury.