Enhanced Tissue Integration During Cartilage RepairIn VitroCan Be Achieved by Inhibiting Chondrocyte Death at the Wound Edge

Objective: Experimental wounding of articular cartilage results in cell death at the lesion edge. The objective of this study was to investigate whether inhibition of this cell death results in enhanced integrative cartilage repair. Methods: Bovine articular cartilage discs (6mm) were incubated in media containing inhibitors of necrosis (Necrostatin-1, Nec-1) or apoptosis (Z-VAD-FMK, ZVF) before cutting a 3mm inner core. This core was left in situ to create disc/ring composites, cultured for up to 6 weeks with the inhibitors, and analyzed for cell death, sulfated glycosaminoglycan release, and tissue integration. Results: Creating the disc/ring composites resulted in a significant increase in necrosis. ZVF significantly reduced necrosis and apoptosis at the wound edge. Nec-1 reduced necrosis. Both inhibitors reduced the level of wound-induced sulfated glycosaminoglycan loss. Toluidine blue staining and electron microscopy of cartilage revealed significant integration of the wound edges in disc/ring composites treated with ZVF. Nec-1 improved integration, but to a lesser extent. Push-out testing revealed that ZVF increased adhesive strength compared to control composites. Conclusions: This study shows that treatment of articular cartilage with cell death inhibitors during wound repair increases the number of viable cells at the wound edge, prevents matrix loss, and results in a significant improvement in cartilage-cartilage integration

Cell growth regulation by muscarinic acetylcholine receptors

The growth response of Chinese hamster ovary (CHO) cells to activation of recombinantly expressed G protein-coupled muscarinic M2 or M3 acetylcholine (ACh) receptors has been assessed. Activation of these receptors leads to divergent growth responses: M2 ACh receptor activation causes an increase in DNA synthesis, whereas M3 ACh receptor activation causes a dramatic inhibition of DNA synthesis.;The M3 ACh receptor-mediated growth inhibition has been characterised, and shown to comprise a G1-phase cell cycle arrest, involving an increase in p21Cip1/Waf1 protein expression. Further, a receptor-mediated increase in p21Cip1/Waf1 association with cyclin-dependent kinase 2 (CDK2) leads to a decrease in CDK2 activity and an accumulation of hypophosphorylated retinoblastoma protein (pRb). The increase p21Cip1/Waf1 expression is due at least in part to an increase p21Cip1/Waf1 mRNA although no receptor-mediated change in candidate transcription factor activities could be detected.;Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) activation profiles suggested two alternative hypotheses to account for the receptor-mediated growth arrest. However, pharmacological and biochemical data demonstrate that ERK, JNK and p38 MAPK are not involved in the growth regulation, whilst inhibition of PKC partially ablates the growth arrest. Data demonstrate that both M3 ACh receptor-mediated ERK and JNK activities may be dependent on liberated G-protein bg subunits, whilst the growth arrest is not perturbed by bg subunit sequestration. Data presented reveal a MAPK-independent mechanism of growth regulation that may involve coping of the M3 ACh receptor to heterotrimeric G-protein families other than Gq/11

Decolonising Indigenous water ‘rights’ in Australia: flow, difference, and the limits of law

This article addresses Indigenous Australian claims to water resources and how they inform and relate to current Australian law and contemporary legal thinking about future possibilities. It adopts a multidisciplinary approach, drawing from historical records, previous ethnographic investigation with Indigenous Australians, current legal scholarship, and social anthropological theory. In doing so, it analyses Indigenous dependencies on water, the history of settler colonial orientations to water bodies, the evolution of settler colonial–Indigenous relations to natural resources, and the development of the Australian legal system’s regulation of water. This provides foundations for a discussion of the limitations of settler colonial notions of property and the failure of settler colonial law to understand and incorporate the dynamism of Indigenous relationships to water, particularly the meaning and productive capacity of water flows within Indigenous cosmologies and sociocultural and ecological systems. Calling for a decolonial turn in legal approaches to Indigenous access and water resource determination, the authors explore the ways in which Australian law may need to ‘unthink’ settler colonial notions of resource ownership as a prerequisite for reformulating future water policy and planning. This reformulation relies on a more extensive legal philosophical engagement with the concept of ‘flow’, a concept that already exists in both water law and planning, but which has not been adequately theorised and enacted. A more comprehensive legal understanding of flow in the context of Indigenous understandings of, and claims to, water provides more sustainable and equitable legal and analytical foundations for managing future water resources issues. The article creates the space for a more culturally relevant notion of ‘Indigenous water rights’ and for new ways of honouring the interrelationship between water flows, meaning-making practices, and cultural continuity.Peter Burdon, Georgina Drew, Matthew Stubbs, Adam Webster and Marcus Barbe