Nitric oxide synthase(NOS)and its product nitric oxide are involved in learning and memory functions.Increasing evidence shows that NOS plays an important role in the pathogenesis of Alzheimer's disease,influencing β-amyloid protein(Aβ)deposition,neuroinflammation,oxidative stress,abnormal microglia activation,synapse damage,autophagy,abnormal mitochondrial function of nerve cells,and cerebral hypoperfusion or vascular endothelial cell injury.This review summarizes the recent evidence for the role of NOS in the pathogenesis of Alzheimer's disease and provides new feasible targets for the prevention and treatment of Alzheimer's disease.

Nitric oxide synthase(NOS)and its product nitric oxide are involved in learning and memory functions.Increasing evidence shows that NOS plays an important role in the pathogenesis of Alzheimer's disease,influencing β-amyloid protein(Aβ)deposition,neuroinflammation,oxidative stress,abnormal microglia activation,synapse damage,autophagy,abnormal mitochondrial function of nerve cells,and cerebral hypoperfusion or vascular endothelial cell injury.This review summarizes the recent evidence for the role of NOS in the pathogenesis of Alzheimer's disease and provides new feasible targets for the prevention and treatment of Alzheimer's disease.

BACKGROUND:Some studies have found that local application of alendronate can promote osteogenesis,but less is reported on the process of distraction osteogenesis. OBJECTIVE:To observe the promoting effect of alendronate on rapid mandibular distraction in a rabbit model and explore its possible mechanism. METHODS:Thirty-six male New Zealand white rabbits were randomly divided into groups A,B and C(n=12 per group)after operation and rapid distraction(3-day delay period followed by 3-day distraction at 1.5 mm/12 hours).At the 1st,3rd and 7th days of the consolidation period,animal were injected with 200 μg/kg alendronate in group A and 100 μg/kg alendronate in group B,while those in group C were treated as controls.CT scanning and dual energy X-ray bone mineral density measurement were performed at 4 and 8 weeks of the consolidation period.After the radionuclide scanning was completed at the 4th week,several animals were sacrificed and the samples were collected for western blot assay and tartrate resistant acid phosphatase staining.A three-point bending test was performed after the animals were sacrificed at the 8th week. RESULTS AND CONCLUSION:CT results showed that bone formation in the distraction space of group B was significantly better than that in groups A and C.At the 4th week,the bone mineral density in group B was(0.092±0.010)g/cm2,which was 1.26 times higher than that in group A(P＜0.001)and 1.28 times higher than that in group C(P＜0.001).At the 8th week,the bone mineral density in group B was(0.175±0.029)g/cm2,which was 1.38 times higher than that in group A(P＜0.001)and 1.45 times higher than that in group C(P＜0.001).Tartrate resistant acid phosphatase staining showed that the number of osteoclast-like cells in group C were 2.83 times more than that in group A(P＜0.001)and 2.21 times more than that in group B(P＜0.001).The radionuclide intensity was higher in group C than in groups A and B.Western blot assay results showed that the expression of Runx2 was significantly stronger in group B than in groups A and C.The maximum biomechanical load in group B was(158.48±23.21)N,which was 1.26 times higher than that in group A(P=0.007)and 1.31 times higher than that in group C(P=0.003).To conclude,the low concentration of alendronate may promote rapid distraction osteogenesis of the rabbit mandible by inhibiting osteoclast signals.

Objective To establish a distraction osteogenesis SD rat model for exploring the effect of total flavonoids from Rhizoma Drynariae on the quality of rat bone formation in the process of distraction osteogenesis from the perspective of tomography.Methods Twenty-four rats were randomly divided into experimental group and control group after successful modeling,and were respectively given intragastric administration with total flavonoids from Rhizoma Drynariae(in dose of 77.125 mg/kg) and saline for 8 weeks.Seven days after operation,the tibias of all the rats were given distraction at the speed of 0.2 mm for 20 days.Eight weeks after the operation,X-ray examination for all the rats was performed,and then the rats were killed for obtaining the tibia samples for Micro-CT scanning.The differences of X-ray Lane-Sandhu scores,the bone mineral density and bone mineral content were compared between the two groups.Results The X-ray Lane-Sandhu scores,the bone mineral density and bone mineral contents showed by Micro-CT scanning in the experimental group were higher than those in the control group,and the differences were statistically significant (P ＜ 0.05).Conclusion The total flavonoids from Rhizoma Drynariae can improve the quality of bone formation in the process of distraction osteogenesis in rats.

Objective To explore the effect of the traumatic brain injury on the fracture healing and the related mechanism. Methods 64 12-week-old SD rats were randomly divided into 2 groups: The femoral fracture with a brain injury group and the femoral fracture group. The bone callus was obtained 1, 2, 3 and 4 week after operation respectively, and observed with the HE staining. The vascular endothelial growth factor (VEGF) and VEGF mRNA in the callus were detected with immunohistochemical staining and hybridization in situ. Results The formation and reforming of the callus in group with brain injury were ahead to only fracture. The percentages of the cells positive for VEGF and VEGF mRNA in the callus were more in group with brain injury than in pure fracture group at the same time point (P<0.05). Conclusion Traumatic brain injury can promote the healing of fracture, which is probably related to an increase in the expression of VEGF.

AIM To study the effect of Vit E on the MLCK activity and expression in the liver of atherosclerosis model rabbits. METHODS The MLCK activity of rabbit liver was measured by the method of ?- 32P incorporated and its expression was detected by immunofluorescent. RESULTS The model of atherosclerosis was estabilished. After rabbits were fed with cholesterol for four weeks and twelve weeks, the activity of MLCK increased markedly, and there was significantly statistical difference compared with the normal control (P0.05). MLCK expression increased after the rabbits was fed with cholesterol for four weeks, and this increase became more obvious had been the rabbits was fed with cholesterol for twelve weeks. The expression decreased when vitamin E had been added into the cholesterol fed. CONCLUSION The pathology of liver may be associated with the increase of the activity of MLCK. Vit E may reduce MLCK activity and protect hepatocyte from injury.

Aim To study the effect of melatonin on expression and activity of myosin light chain kinase in the artery wall of atherosclerotic rabbits.Methods The rabbit model of atherosclerosis was induced by a high-cholesterol diet.The blood lipid levels were assayed in the serum of each group.MLCK expression was detected by Western blot and immunohistochemical method.MLCK activity was measured by ?-32P-ATP incorporation into myosin light chain.Results The atherosclerosis model was established successfully.The levels of lipids decreased after MLT treatment.After fed with cholesterol for twelve weeks,the expression and activity of MLCK in the artery of atherosclerotic rabbits increased markedly,whereas there was no obvious difference in expression of MLCK in the artery of atherosclerotic rabbits fed with cholesterol and melatonin for twelve weeks compared with that of control.Conclusions It was suggest that high expression and activity of MLCK in the artery might be closely correlated with the development of atherosclerosis.Melatonin played an important role in inhibiting the development of atherosclerosis by decreasing the expression and activity of MLCK.