Objective To investigate the changing law of mechanical responses of herniated lumbar intervertebral disc under automobile vibration.Methods Herniated and healthy intervertebral disc specimens were made using the sheep lumbar spines.The specimens were compressed in flexion/vertical posture to simulate the stress state of the driver's lumbar spine in different sitting positions,and then the creep experiments were carried out on this basis.The viscoelastic mechanical behaviour of lumbar intervertebral discs during dynamic creep was described using a standard linear solid model,the dynamic creep strain,strain rate,elastic modulus were calculated,and the physical significance of the constitutive equations was analyzed.Results The dynamic creep strain of the herniated lumbar disc specimen was significantly larger than that of the healthy specimen,while the amplitude was basically unchanged;the vibration acceleration had basically no effects on the dynamic creep strain,while it had a significant effect on the amplitude;the forward flexion mode had a slight effect on the dynamic creep strain,while it had a significant effect on the amplitude.The results of the present constitutive equation calculations were in agreement with the results of the experimental tests.Conclusions This study provides important theoretical guidance for the prevention of low back pain diseases in car drivers.

Objective To investigate the changing law of mechanical responses of herniated lumbar intervertebral disc under automobile vibration.Methods Herniated and healthy intervertebral disc specimens were made using the sheep lumbar spines.The specimens were compressed in flexion/vertical posture to simulate the stress state of the driver's lumbar spine in different sitting positions,and then the creep experiments were carried out on this basis.The viscoelastic mechanical behaviour of lumbar intervertebral discs during dynamic creep was described using a standard linear solid model,the dynamic creep strain,strain rate,elastic modulus were calculated,and the physical significance of the constitutive equations was analyzed.Results The dynamic creep strain of the herniated lumbar disc specimen was significantly larger than that of the healthy specimen,while the amplitude was basically unchanged;the vibration acceleration had basically no effects on the dynamic creep strain,while it had a significant effect on the amplitude;the forward flexion mode had a slight effect on the dynamic creep strain,while it had a significant effect on the amplitude.The results of the present constitutive equation calculations were in agreement with the results of the experimental tests.Conclusions This study provides important theoretical guidance for the prevention of low back pain diseases in car drivers.

Gut microbiota(GM)consists of a complex community of microorganism species that live in the digestive tracts of animals including humans. Dysbiosis is believed to involve in the development of some diseases. Recently dysbiosis in the patients with Alzheimer′s disease(AD)and AD rat models was reported. GM may influence the pathogenesis and development of AD in several ways. Some neurotoxic substances produced by GM can invade into the brain via circulation and impair the neural functions. These sub?stances include ammonia,cyanobacteria-producedβ-N-methylamino-L-alanine,saxitoxin,anatoxin-αand amyloid. The decrease in brain-derived neurotrophic factor(BDNF)in hippocampus and cerebral cortex induced by dysbiosis contributes to the cognitive dys?function. Dysbiosis related endotoxin can induce inflammation,which is one important risk factor for obesity,insulin resistance(IR) and type 2 diabetes mellitus(TIDM). AD and diabetes have good correlation and similarity. Probiotics,prebiotics and Chinese herbal medicines can rebuild GM and have been reported to ameliorate the memory loss of AD patients or model rats. However ,whether and how their preventative and therapeutic effects on AD mediated by GM are worthy of further investigation.