Experimental investigation on permeability and mechanical deformation of coal containing gas under load

Coalbed effective permeability is widely used as a primary index to evaluate gas-drainage effect in CBM exploitation field. However, it seems to be difficult to obtain by the reason of dynamic change in close relationship with crustal stress, methane pressure, porosity, and adsorption. Due to their dissimilar adsorption properties and tectonic deformation degrees, different types of coal containing gas have various stress-strain and gas seepage curves. The paper presents the experimental investigations of the dynamic relationship between coal permeability and deformation under load. In this work, stress-strain and permeability investigations were performed using anthracite lump with a vitrinite reflectance of about 3.24% at various pressures and temperatures. The permeability (including the initial, minimum, and maximum) decreased with increasing temperature. At a constant confining pressure, the strains in different directions almost all increased with increasing axial stress and decreased with increasing pore methane pressure during the prefracture stage. At a constant pore pressure, the compression strength of the coal specimens increased approximately linearly during the prefracture stage and sharply decreased during the postfracture stage, while the permeability decreased rapidly and then increased slowly during the prefracture and remained stable during the postfracture stage. The permeability of the coal specimens mainly depended on the inner fissures. The permeability was greater during the postfracture than that during the prefracture stage. At the same temperature, the gas seepage curve of each coal specimen could be divided into three sections: decreasing, increasing, and constant sections. The necessary time for the permeability to reach a steady state increased as the confining and pore pressures increased. At high confining pressures (i.e., 6 MPa and 8 MPa), no significant differences between the methane seepage velocities of the specimens were evident, and their seepage curves were similar to prefracture. However, clear differences were observable at the postfracture stage. The seepage abilities of the coal specimens were more sensitive to stress than temperature in the same condition

Analysis of 116 cases of rectal cancer treated by transanal local excision

BACKGROUND: The purpose of this research was to evaluate the therapeutic effects and prognostic factors of transanal local excision (TAE) for rectal cancer. METHODS: We retrospectively analyzed 116 cases that underwent TAE for rectal cancer from 1995 to 2008. A Cox regression analysis was used to analyze prognostic factors. RESULTS: The survival times for the patients were from 14 to 160.5 months (median time, 58.5 months). The 5-year and 10-year overall survival rates were 72% and 53%, respectively. In all 16 cases experienced local recurrence (13.8%). Pathological type, recurrence or metastasis, and depth of infiltration (T stage) were the prognostic factors according to the univariate analysis, and the latter two were independent factors affecting patient prognosis. For patients with T1 stage who underwent adjuvant radiotherapy, there was no local recurrence; for those in T2 stage, the local recurrence rate was 14.6%. In addition, there was no difference between the patients who received radiotherapy and those who did not (T1: P = 0.260, T2: P = 0.262 for survival rate and T1: P = 0.480, T2: P = 0.560 for recurrence). CONCLUSIONS: The result of TAE for rectal cancer is satisfactory for T1 stage tumors, but it is not suitable for T2 stage tumors

Inhibition of miR-665 alleviates neuropathic pain by targeting SOCS1

Purpose: To investigate the effect of miR-665 in neuropathic pain and the possible molecular mechanism involved.Methods: A neuropathic pain model was established using chronic constriction injury (CCI) methods in Sprague Dawley (SD) rats. Mechanical and thermal hyperalgesia were measured using paw withdrawal threshold (PWT) and paw withdrawal latency (PWL), respectively. The inflammation response was determined by assessing the production of inflammation factors. The target relationship of miR-665 and suppressor of cytokine signaling 1 (SOCS1) was verified by luciferase assay.Results: In the CCI rat model, PWT and PWL decreased following treatment with miR-665 (p < 0.01). MiR-665 was elevated in the spinal cord and microglia of CCI rats at different time points (p < 0.01). Down-regulation of miR-665 increased PWT and PWL and inhibited the production of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in CCI rats (p < 0.01). Luciferase assay results indicate that SOCS1 was the target of miR-665 (p < 0.01). SOCS1 decreased in CCI rats (p < 0.01) after treatment with miR-665. MiR-665 negatively regulated the expression of SOCS1 (p < 0.01). Down-regulation of SOCS1 reversed the alleviating effect of decreased miR-665 on pain sensitivity and inflammationresponse (p < 0.01).Conclusion: Down-regulation of miR-665 alleviates neuropathic pain by targeting SOCS1, and hence making miR-665 a promising therapeutic target for neuropathic pain. Keywords: MiR-665, SOCS1, Neuropathic pain, CCI, Spinal cor

Regulated proteolysis of the alternative sigma factor SigX in Streptococcus mutans: implication in the escape from competence

BACKGROUND: SigX (σ(X)), the alternative sigma factor of Streptococcus mutans, is the key regulator for transcriptional activation of late competence genes essential for taking up exogenous DNA. Recent studies reveal that adaptor protein MecA and the protease ClpC act as negative regulators of competence by a mechanism that involves MecA-mediated proteolysis of SigX by the ClpC in S. mutans. However, the molecular detail how MecA and ClpC negatively regulate competence in this species remains to be determined. Here, we provide evidence that adaptor protein MecA targets SigX for degradation by the protease complex ClpC/ClpP when S. mutans is grown in a complex medium. RESULTS: By analyzing the cellular levels of SigX, we demonstrate that the synthesis of SigX is transiently induced by competence-stimulating peptide (CSP), but the SigX is rapidly degraded during the escape from competence. A deletion of MecA, ClpC or ClpP results in the cellular accumulation of SigX and a prolonged competence state, while an overexpression of MecA enhances proteolysis of SigX and accelerates the escape from competence. In vitro protein-protein interaction assays confirm that MecA interacts with SigX via its N-terminal domain (NTD(1–82)) and with ClpC via its C-terminal domain (CTD(123–240)). Such an interaction mediates the formation of a ternary SigX-MecA-ClpC complex, triggering the ATP-dependent degradation of SigX in the presence of ClpP. A deletion of the N-terminal or C-terminal domain of MecA abolishes its binding to SigX or ClpC. We have also found that MecA-regulated proteolysis of SigX appears to be ineffective when S. mutans is grown in a chemically defined medium (CDM), suggesting the possibility that an unknown mechanism may be involved in negative regulation of MecA-mediated proteolysis of SigX under this condition. CONCLUSION: Adaptor protein MecA in S. mutans plays a crucial role in recognizing and targeting SigX for degradation by the protease ClpC/ClpP. Thus, MecA actually acts as an anti-sigma factor to regulate the stability of SigX during competence development