Cartilage biomechanics: A key factor for osteoarthritis regenerative medicine

Osteoarthritis (OA) is a joint disorder that is highly extended in the global population. Several researches and therapeutic strategies have been probed on OA but without satisfactory long-term results in joint replacement. Recent evidences show how the cartilage biomechanics plays a crucial role in tissue development. This review describes how physics alters cartilage and its extracellular matrix (ECM); and its role in OA development. The ECM of the articular cartilage (AC) is widely involved in cartilage turnover processes being crucial in regeneration and joint diseases. We also review the importance of physicochemical pathways following the external forces in AC. Moreover, new techniques probed in cartilage tissue engineering for biomechanical stimulation are reviewed. The final objective of these novel approaches is to create a cellular implant that maintains all the biochemical and biomechanical properties of the original tissue for long-term replacements in patients with OA.     

Major Histocompatibility Complex (MHC) class II sequence polymorphism in long-finned pilot whale (Globicephala melas) from the North Atlantic

Determining how intra-specific genetic diversity is apportioned among natural populations is essential for detecting local adaptation and identifying populations with inherently low levels of extant diversity which may become a conservation concern. Sequence polymorphism at two adaptive loci (MHC DRA and DQB) was investigated in long-finned pilot whales (Globicephala melas) from four regions in the North Atlantic and compared with previous data from New Zealand (South Pacific). Three alleles were resolved at each locus, with trans-species allele sharing and higher levels of non-synonymous to synonymous substitution, especially in the DQB locus. Overall nucleotide diversities of 0.49?±?0.38% and 4.60?±?2.39% were identified for the DRA and DQB loci, respectively, which are relatively low for MHC loci in the North Atlantic, but comparable to levels previously described in New Zealand (South Pacific). There were significant differences in allele frequencies within the North Atlantic and between the North Atlantic and New Zealand. Patterns of diversity and divergence are consistent with the long-term effects of balancing selection operating on the MHC loci, potentially mediated through the effects of host-parasite coevolution. Differences in allele frequency may reflect variation in pathogen communities, coupled with the effects of differential drift and gene flow.     

Trophic level and fatty acids in harp seals compared with common minke whales in the Barents Sea

The objectives of this study were to explore trophic levels and possible diet overlap between harp seals (Pagophilus groenlandicus) and common minke whales (Balaenoptera acutoroostrata) in the Barents Sea using stable isotopes of nitrogen (δ¹⁵N) and carbon (δ¹³C) and fatty acid analyses, and to explore the energy pathways from the plankton to the top predators. Blubber and muscle samples from 93 harp seals and 20 minke whales were collected in the southern Barents Sea in May 2011. The study showed that harp seals were at a higher trophic level than minke whales during spring. This supported previous diet studies suggesting a more fish-dominant diet for seals, as compared with the whales, at this time of the year. The stable isotopes and fatty acids indicated niche separation between the seals and the whales, and between different age groups of the harp seals. Older seals had fatty acid profiles more equal to minke whales as compared with younger seals. Furthermore, while the fatty acid profiles suggested that krill were of particular importance for the young seals, the profiles from older seals and whales suggested that fish dominated their diets.