Study on the mechanism and response law of fracture movement on the super-high position hard-thick strata.

In this paper, a thick plate structural mechanical model was established for the hard-thick rock strata in the Ordos region, which was characterized by the occurrence of high-energy strong earthquakes caused by the fracture of hard-thick rock strata. Subsequently, based on Vlasov's theory, the evolution process of hard-thick rock strata was analyzed. And the paper validated the analysis results using high-energy mine earthquake and surface subsidence data. The following conclusions were drawn: (1) The hard-thick strata in the cretaceous system will not be broken during the advancing and mining process of the test panel of the Shilawusu coal mine. (2) When the test panel is mined to a distance of two panel widths, no fracture occurred in the lower part of the hard-thick strata, because no separated space was formed. (3) When the test panel was advanced to about 856 m, the hard-thick strata have fractured in a vertical direction. (4) No high-energy mine earthquake event has occurred during mining at test panel, and the amount of surface subsidence is approximately 200 mm. (5) In the mining at test panel, two high-energy mining earthquakes occurred at 837 m, 1153 m away from the initial position of the panel, respectively, and the maximum amount of surface subsidence increased to 1397 mm, which accords with the results of the first and periodic breaks calculated by theory. The research results of this paper are of guiding significance for the study of the breaking law of hard-thick strata under similar engineering geological conditions and disaster pre-control.

Anti-microRNA-21/221 and microRNA-199a transfected by ultrasound microbubbles induces the apoptosis of human hepatoma HepG2 cells.

Gene therapy, particularly microRNA (miRNA), is a promising candidate in the treatment of cancer; however, it is challenging to develop gene delivery systems. Ultrasound microbubbles have been used for gene delivery with excellent results. The present study aimed to investigate the transfection efficiency of HepG2 cells using ultrasound microbubbles. The effects of three miRNAs (miR-21, miR-221 and miR-199a) on HepG2 cells were also determined by performing ultrasound microbubble-mediated gene transfection. Three recombinant plasmids containing anti-miR-21, anti-miR-221 and miR-199a were fused with enhanced green fluorescent protein. For the transfection of genes, the type of contrast agent, the concentration of microbubble contrast agent and the exposure intensity of ultrasound were optimized. The expression of miRNAs was detected using reverse transcription-polymerase chain reaction. To determine the effect of anti-miR-21, anti-miR-221 and miR-199a on HepG2 cells, MTT, cell cycle analysis and Annexin V-PE/7-ADD apoptosis assays were performed. The optimal condition was 10% sulfur hexafluoride microbubbles at an ultrasound frequency of 2.0 MHz and mechanical index of 0.28. When cells were transfected with three recombinant plasmids using ultrasound microbubbles, there was significant downregulation of miR-21 and miR-221 and upregulation of miR-199a (P<0.05). All three treatments inhibited cell proliferation and promoted the apoptosis of cells. The present data indicated that the delivery of anti-miR-21, anti-miR-221 and miR-199a may be mediated by ultrasound microbubble contrast agents. With this approach, cell proliferation may be effectively inhibited and cell apoptosis may be induced. These are novel cancer therapy targets.

Perfusion heterogeneity in breast tumors for assessment of angiogenesis.

OBJECTIVES: The purpose of this study was to investigate the perfusion heterogeneity of malignant and benign breast tumors and assay their vascular architecture changes and molecular expression, thereby evaluating the relevance between imaging and histologic characteristics of angiogenesis. METHODS: Real-time grayscale contrast-enhanced sonography was performed in 310 women with 317 breast tumors. The enhancement patterns and perfusion parameters for malignant and benign tumors were analyzed by contrast-enhanced sonography with microvascular imaging and quantitative time-intensity curve analysis. Structural characteristics were observed by light and electron microscopy. The microvessel density, vascular endothelial growth factor (VEGF) expression, and human kinase insert domain-containing receptor (KDR) expression for all tumors were assessed by immunohistochemical staining of CD31, KDR, and VEGF. RESULTS: Surgical pathologic analysis showed 163 malignant and 154 benign tumors. Significant morphologic differences, including perfusion defects, vessel distortion, vessel dilatation, and heterogeneous enhancement, were observed between the malignant and benign groups (P < .05). The mean perfusion parameters (peak intensity, ascending slope, area under the curve, and wash-out time) were greater in the malignant tumors (P < .05). There were significant differences in the peak intensity, ascending slope, area under the curve, and wash-out time between peripheral and central regions of the malignant tumors (P < .05) but none in the benign tumors. Vessels had various morphologic and distributional characteristics in the peripheral and central regions of the malignant tumors. The microvessel density and VEGF and KDR expression were significantly higher in the malignant group (P < .05), especially in the peripheral regions. CONCLUSIONS: Perfusion heterogeneity was closely associated with the tumor microvascular architecture and molecular expression. Perfusion features, especially regional morphologic and hemodynamic features, can provide valuable information for differentiating malignant from benign breast tumors.