Astragalus Polysaccharide Promotes Neuronal Injury Repair via the Notch1/NFκB Signaling Axis in the Ventroposterior Thalamic Nucleus in Rats with Focal Cerebral Ischemia.

BACKGROUND: Ischemic stroke is the most common form of stroke and the second most common cause of death and incapacity worldwide. Its pathogenesis and treatment have been the focus of considerable research. In traditional Chinese medicine, the root of Mongolian astragalus has been important in the treatment of stroke since ancient times. Astragalus polysaccharide (APS) is a key active ingredient of astragalus and offers therapeutic potential for conditions affecting the neurological system, the heart, cancer, and other disorders. However, it is not yet known how APS works to protect against ischemic stroke. METHODS: Rats were subjected to middle cerebral artery occlusion (MCAO) to imitate localized cerebral ischemia. Each of four experimental groups (normal, sham, MCAO, and MCAO+APS) contained 12 adult male Sprague-Dawley (SD) rats selected randomly from a total of 48 rats. Following successful establishment of the model, rats in the MCAO+APS group received intraperitoneal injection of APS (50 mg/kg) once daily for 14 days, whereas all other groups received no APS. The Bederson nerve function score and the forelimb placement test were used to detect motor and sensory function defects, while Nissl staining was used to investigate pathological defects in the ventroposterior thalamic nucleus (VPN). Immunohistochemical staining and Western blot were used to evaluate the expression of Neurogenic locus notch homolog protein 1 (Notch1), hairy and enhancer of split 1 (Hes1), phospho-nuclear factor-κB p65 (p-NFκB p65), and nuclear factor-κB p65 (NFκB p65) proteins in the VPN on the ischemic side of MCAO rats. RESULTS: APS promoted the recovery of sensory and motor function, enhanced neuronal morphology, increased the number of neurons, and inhibited the expression of Notch1/NFκB signaling pathway proteins in the VPN of rats with cerebral ischemia. CONCLUSION: After cerebral ischemia, APS can alleviate symptoms of secondary damage to the VPN, which may be attributed to the suppression of the Notch1/NFκB pathway.

Spalling Criterion of Hard Brittle Rock Mass Based on Dilatation Lateral Strain.

Spalling failure is a typical failure phenomenon after excavation and unloading of a deep, hard brittle rock mass, which seriously threatens the safe construction of deep roadways (tunnels) and other projects. From the engineering viewpoint, it is essential to accurately evaluate the range and depth of surrounding rock spalling failure. From the perspective of the laboratory and engineering site, the strength and formation mechanism of hard rock spalling failure were statistically summarized and analyzed. Under uniaxial and low confining pressure conditions, when the load reached the rock damage stress, cracks in the rock penetrated to form a failure plane approximately parallel to the axial loading direction, and the strength of rock mass spalling was much smaller than that of intact rock spalling. A triaxial compression test was conducted to analyze the dilatation axial strain and dilatation lateral strain characteristics of gneiss. The results showed that dilatation axial strain gradually increased with the increase of confining pressure, whereas dilatation lateral strain was almost unchanged. Therefore, a safety factor (FS) based on dilatation lateral strain was developed. Through comparison with other strain-based spalling criteria, the establishment and physical meaning of the method were described in detail. In addition, FS was applied to analyze the deep roadway of the Hongtoushan Copper Mine in China and the Rm415 test tunnel in Canada. The results showed that the spalling criterion could accurately indicate the range and depth of the surrounding rock spalling failure, which verified the rationality and applicability of the new spalling criterion. Thus, FS can be utilized as a new theory and analysis tool for the assessment and prevention of spalling failure in deep hard rock roadways.