Because changes in the mechanical properties of bone are closely related to trabecular bone remodeling, methods that consider the temporal morphological changes induced by adaptive remodeling of trabecular bone are needed to estimate long-term fracture risk and bone quality in osteoporosis. We simulated bone remodeling using simplified and pig trabecular bone models and estimated the morphology of healthy and osteoporotic cases. We then displayed the fracture risk of the remodeled models based on a cumulative histogram from high stress. The histogram showed more elements had higher stresses in the osteoporosis model, indicating that the osteoporosis model had a greater risk. 相似文献
The SPO11-generated DNA double-strand breaks (DSBs) that initiate meiotic recombination occur non-randomly across genomes, but mechanisms shaping their distribution and repair remain incompletely understood. Here, we expand on recent studies of nucleotide-resolution DSB maps in mouse spermatocytes. We find that trimethylation of histone H3 lysine 36 around DSB hotspots is highly correlated, both spatially and quantitatively, with trimethylation of H3 lysine 4, consistent with coordinated formation and action of both PRDM9-dependent histone modifications. In contrast, the DSB-responsive kinase ATM contributes independently of PRDM9 to controlling hotspot activity, and combined action of ATM and PRDM9 can explain nearly two-thirds of the variation in DSB frequency between hotspots. DSBs were modestly underrepresented in most repetitive sequences such as segmental duplications and transposons. Nonetheless, numerous DSBs form within repetitive sequences in each meiosis and some classes of repeats are preferentially targeted. Implications of these findings are discussed for evolution of PRDM9 and its role in hybrid strain sterility in mice. Finally, we document the relationship between mouse strain-specific DNA sequence variants within PRDM9 recognition motifs and attendant differences in recombination outcomes. Our results provide further insights into the complex web of factors that influence meiotic recombination patterns. 相似文献
Transient ischaemia and reperfusion in liver tissue induce hepatic ischaemia/reperfusion (I/R) tissue injury and a profound inflammatory response in vivo. Hepatic I/R can be classified into warm I/R and cold I/R and is characterized by three main types of cell death, apoptosis, necrosis and autophagy, in rodents or patients following I/R. Warm I/R is observed in patients or animal models undergoing liver resection, haemorrhagic shock, trauma, cardiac arrest or hepatic sinusoidal obstruction syndrome when vascular occlusion inhibits normal blood perfusion in liver tissue. Cold I/R is a condition that affects only patients who have undergone liver transplantation (LT) and is caused by donated liver graft preservation in a hypothermic environment prior to entering a warm reperfusion phase. Under stress conditions, autophagy plays a critical role in promoting cell survival and maintaining liver homeostasis by generating new adenosine triphosphate (ATP) and organelle components after the degradation of macromolecules and organelles in liver tissue. This role of autophagy may contribute to the protection of hepatic I/R-induced liver injury; however, a considerable amount of evidence has shown that autophagy inhibition also protects against hepatic I/R injury by inhibiting autophagic cell death under specific circumstances. In this review, we comprehensively discuss current strategies and underlying mechanisms of autophagy regulation that alleviates I/R injury after liver resection and LT. Directed autophagy regulation can maintain liver homeostasis and improve liver function in individuals undergoing warm or cold I/R. In this way, autophagy regulation can contribute to improving the prognosis of patients undergoing liver resection or LT. 相似文献
Teeth resection is a method of controlling the injurious effects of the aggression displayed when newborn piglets fight to establish a teat order. Recent European legislation discourages the practice. The objective of this study was to assess the effect of clipping and grinding piglets’ needle teeth, compared to leaving them intact, on the welfare of piglets in farrowing crates.
Six days pre-partum, 60 sows were assigned to one of three treatments. Litters had their teeth clipped (C), ground (G) or left intact (I) at birth. The time taken to carry out each procedure was recorded. Piglet weights and facial lesions, which were scored according to severity, were recorded on days 1, 4, 11, 18 and 27. Piglet weights were also recorded at birth. Mouth lesions were recorded on days 1, 4 and 27. Instantaneous scan samples of piglet behaviour were carried out for 30 min post-teeth resection procedure (1 min intervals), and for 6 h on days 1, 4, 8, 14, 21 and 26 (5 min intervals). One male and one female piglet per litter were chosen as focal animals and observed for 5 min each post-procedure and for 10 min each twice per day on days 1, 5, 12, 20 and 26. Mortalities were recorded throughout lactation.
Grinding took significantly longer than clipping the teeth or leaving them intact (F = 638.87, P < 0.001). I piglets had higher facial lesion scores than C and G piglets (F = 10.58, P < 0.001). A smaller proportion of piglets in I litters than C and G litters and a smaller proportion of piglets in G litters than C litters had at least one mouth lesion (F = 4.74, P < 0.001). During 30 min post-procedure, I piglets were active on the heatpad in more observations than C and G piglets (F = 3.49, P < 0.05). During 5 min post-procedure C piglets spent longer chomping than I piglets (F = 5.92, P = 0.05). On day 21, I piglets were active in more observations than G piglets (F = 2.11, P < 0.05). On day 26, G piglets were inactive in more observations than C and I piglets (F = 5.02, P < 0.05). On days 14 and 26, C piglets were sleeping in more observations than G piglets (F = 2.87, P = 0.05). There was a tendency for a larger proportion of I than C piglets to die due to overlying (F = 2.68, P = 0.08).
In conclusion, although all three options were associated with welfare problems, grinding can be recommended in preference to clipping or leaving the teeth intact. 相似文献