Up-regulation of the long non-coding RNA RMRP contributes to glioma progression and promotes glioma cell proliferation and invasion.

INTRODUCTION: Gliomas are the most common malignant tumors of the brain. Long non-coding RNAs (lncRNAs) play key regulatory roles in various tumors. In this study, we aimed to determine the expression and biological roles of lncRNA RMRP in glioma. MATERIAL AND METHODS: The relative expression level of lncRNA RMRP was determined by quantitative real-time polymerase chain reaction (qRT-PCR) in a total of 39 patients with glioma. RNA interference (RNAi) approaches were used to investigate the biological functions of RMRP. The effect of lncRNA RMRP on proliferation was determined by CCK8 assay. Cell cycle and apoptosis were evaluated by flow cytometry analysis. Cell migration was explored by the wound-healing assay. Cell invasion was investigated by the Transwell invasion assay. RESULTS: LncRNA RMRP was up-regulated in human glioma tissues compared with normal brain tissues (p < 0.05). LncRNA RMRP up-regulation was significantly correlated with advanced tumor grade and low Karnofsky Performance Score (KPS) (p < 0.05). Moreover, patients with a high expression level of lncRNA RMRP had a relatively poor prognosis (p < 0.05). Multivariate analyses revealed that lncRNA RMRP expression served as an independent predictor for overall survival of glioma patients (p < 0.05). In addition, inhibition of lncRNA RMRP by RNAi significantly suppressed the proliferation, migration and invasion of glioma cells in vitro (p < 0.05). CONCLUSIONS: lncRNA RMRP might act as an oncogene and could be used as a therapeutic target for the treatment of glioma. Our findings provide an in-depth insight into the role of lncRNA RMRP in glioma progression.

Long non-coding RNA XIST exerts oncogenic functions in human glioma by targeting miR-137.

Long non-coding RNA (lncRNA) X inactivate-specific transcript (XIST) acts as an important regulator in tumor progression. However, its expression and the underlying mechanism in glioma remain unclear. The aim of this study was to explore the potential function of XIST in glioma progression. In the present study, our data showed that the expression of XIST was significantly up-regulated in glioma tissues and enhanced the proliferation of glioma cells. The expression of miR-137 was significantly decreased in glioma tissues. Further correlation analysis demonstrated that there was a negative correlation between XIST expression and miR-137 expression. Bioinformatics prediction and luciferase reporter assays demonstrated that miR-137 could directly bind to XIST and negatively regulated the expression of miR-137. Additionally, our data further showed that XIST could up-regulate the expression of miR-137 targeted gene Rac1 through acting as an endogenous sponge of miR-137. In addition, we found that Rac1 inhibition or miR-137 overexpression could suppress glioma cells proliferation induced by XIST overexpression. Thus, a novel XIST-miR-137-Rac1 pathway regulatory axis in glioma pathogenesis was revealed in the present study. Overall, our study indicated that XIST could be a potential therapeutic target in the treatment of glioma.

PROX1 promotes human glioblastoma cell proliferation and invasion via activation of the nuclear factor-κB signaling pathway.

Prospero homeobox protein 1 (PROX1) is highly expressed in high-grade malignant astrocytic gliomas. However, the role of PROX1 in the pathogenesis of glioblastoma multiforme (GBM) remains unclear. The present study overexpressed PROX1 in human GBM cell lines and examined its effects on cell growth, tumorigenesis, and invasiveness. In addition, the involvement of the nuclear factor­κB (NF­κB) signaling pathway in the action of PROX1 was examined. It was identified that overexpression of PROX1 significantly increased the proliferation and colony formation of glioblastoma cells, compared with empty vector­transfected controls. Furthermore, ectopic expression of PROX1 promoted the growth of GBM xenograft tumors. Western blot analysis revealed that PROX1 overexpression induced nuclear accumulation of NF­κB p65 and upregulated the expression levels of the NF­κB responsive genes cyclin D1 and matrix metallopeptidase 9. An NF­κB reporter assay demonstrated that PROX1­overexpressing glioblastoma cells had significantly greater NF­κB­dependent reporter activities compared with empty vector­transfected controls. Transfection of a dominant inhibitor of κBα mutant into PROX1­overexpressing cells significantly impaired their proliferation and invasion capacities, which was accompanied by reduced levels of nuclear NF­κB p65. Collectively, these data indicated that PROX1 serves an oncogenic role in GBM and promotes cell proliferation and invasiveness potentially via activation of the NF­κB signaling pathway. Therefore, PROX1 may represent a potential target for the treatment of GBM.

[POSTERIOR ATLANTOAXIAL LATERAL MASS SCREW FIXATION AND SUBOCCIPITAL DECOMPRESSION FOR TREATMENT OF Arnold-Chiari MALFORMATION ASSOCIATED WITH ATLANTOAXIAL DISLOCATION].

OBJECTIVE: To evaluate the effectiveness of the posterior atlantoaxial lateral mass screw fixation and suboccipital decompression in the treatment of Arnold-Chiari malformation associated with atlantoaxial joint dislocation. METHODS: Between September 2012 and November 2015, 17 cases of Arnold-Chiari malformation associated with atlantoaxial dislocation were treated by the posterior atlantoaxial lateral mass screw fixation and suboccipital decompression and expansion to repair the dura mater and bone graft fusion. There were 10 males and 7 females, aged 35-65 years (mean, 51.4 years). The disease duration was 14 months to 15 years with an average of 7.4 years. According to Arnold-Chiari malformation classification, 13 cases were rated as type I, 3 cases as type II, and 1 case as type III-IV. Cervical nerve root stimulation and compression symptoms were observed in 12 cases, occipital foramen syndrome in 11 cases, cerebellar compression symptoms in 6 cases, and syringomyelia in 10 cases. RESULTS: Primary healing of incision was obtained in the other patients except 1 patient who had postoperative cerebrospinal fluid leakage after removal of drainage tube at 3 days after operation, which was cured after 7 days. All patients were followed up 6 months to 2 years, with an average of 18.4 months. The neurological dysfunction was improved in different degrees after operation. The Japanese Orthopedic Association (JOA) score was significantly increased to 16.12±1.11 at 6 months from preoperative 11.76±2.01 (t=13.596, P=0.000); compression of spinal cord and medulla was improved. X-ray examination showed bone graft fusion at 6 months after operation. In 10 patients with spinal cord cavity, MRI showed empty disappearance in 3 cases, empty cavity lessening in 6 cases, and no obvious change in 1 case at 6 months. CONCLUSIONS: Atlantoaxial lateral mass screw fixation and suboccipital decompression and expansion to repair the dura mater can obtain good effectiveness in the treatment of Arnold Chiari malformation associated with atlantoaxial transarticular dislocation.

DRIFTS study of ammonia activation over CaO and sulfated CaO for NO reduction by NH3.

CaO catalyzes NH(3) oxidation, while sulfated CaO catalyzes NO reduction by NH(3) in the presence of O(2), and the adsorption and transformation of ammonia over CaO and sulfated CaO has been investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to understand their catalytic mechanism. It has been found that ammonia is first adsorbed over Lewis or Brönsted acid sites, and later undergoes hydrogen abstraction giving rise to either NH(2) amide or NH imide intermediates. The intermediates react with NO or lattice O to produce N(2) or NO. Comparing the DRIFTS of NH(3) adsorption over CaO and sulfated CaO, it is obvious that ammonia adsorbed over CaO is activated mainly in NH form apt to react with surface oxygen to produce NO, while ammonia adsorbed over sulfated CaO is activated mainly in NH(2) form apt to reduce NO. The DRIFTS results agree with experimental data and explain the catalytic mechanisms of CaO and sulfated CaO.

Utilization of ventilation air methane as a supplementary fuel at a circulating fluidized bed combustion boiler.

Ventilation air methane (VAM) accounts for 60-80% of the total emissions from coal mining activities in China, which is of serious greenhouse gas concerns as well as a waste of valuable fuel sources. This contribution evaluates the use of the VAM utilization methods as a supplementary fuel at a circulating fluidized bed combustion boiler. The paper describes the system design and discusses some potential technical challenges such as methane oxidation rate, corrosion, and efficiency. Laboratory experimentation has shown that the VAM can be burnt completely in circulated fluidized bed furnaces, and the VAM oxidation does not obviously affect the boiler operation when the methane concentration is less than 0.6%. The VAM decreased the incomplete combustion loss for the circulating fluidized bed combustion furnace. The economic benefit from the coal saving insures that the proposed system is more economically feasible.

Effect of near-wall air curtain on the wall deposition of droplets in a semidry flue gas desulfurization reactor.

The wall deposition of droplets is an important issue affecting the desulfurization efficiency and operating stability of semidry flue gas desulfurization (FGD) reactors. Various near-wall air velocities, near-wall air flow inlet heights, and spray characteristics were analyzed numerically to investigate their effect on the gas-liquid flow and droplet deposition characteristics. The analytical results show that the near-wall air curtain effectively reduces the wall deposition of droplets in the semidry FGD reactor. The droplet deposition ratio decreased rapidly with increasing near-wall air velocity due to the increased gas flow rates and the altered gas velocity distribution. The near-wall air flow inlet height had an optimum value due to the rapid decline of the near-wall air momentum along the reactor height. The optimum distance between the near-wall air inlet height and the droplet injection height was 1.2 times that of the droplet vertical movement distance before deposition based on the linear droplet movement. For commonly used spray characteristics in the semidry FGD process, i.e., droplet diameters of 50-150 microm, spray angles of 10-70 degrees and droplet initial velocities of 20-100 m/s, the droplet deposition ratio with the addition of the near-wall air curtain varied slightly with the droplet diameter and the spray angle but increased rapidly with the initial droplet velocity. Therefore, for the semidry FGD processes, the near-wall air curtain is an effective method to reduce the wall deposition of droplets for various droplet diameters and spray angles while the initial droplet velocity should be carefully controlled to reduce the wall deposition of droplets and improve the operating stability.

Simultaneous removal of SO2 and trace As2O3 from flue gas: mechanism, kinetics study, and effect of main gases on arsenic capture.

Sulfur dioxide (SO2) and trace elements are pollutants derived from coal combustion. This study focuses on the simultaneous removal of S02 and trace arsenic oxide (As2O3) from flue gas by calcium oxide (CaO) adsorption in the moderate temperature range. Experiments have been performed on a thermogravimetric analyzer (TGA). The interaction mechanism between As2O3 and CaO is studied via XRD detection. Calcium arsenate [Ca3(AsO4)2] is found to be the reaction product in the range of 600-1000 degrees C. The ability of CaO to absorb As2O3 increases with the increasing temperature over the range of 400-1000 degrees C. Through kinetics analysis, it has been found that the rate constant of arsenate reaction is much higher than that of sulfate reaction. SO2 presence does not affect the trace arsenic capture either in the initial reaction stage when CaO conversion is relatively low or in the later stage when CaO conversion is very high. The product of sulfate reaction, CaS04, is proven to be able to absorb As2O3. The coexisting CO2 does not weaken the trace arsenic capture either.

Effect of solids concentration distribution on the flue gas desulfurization process.

A dry flue gas desulfurization (FGD) process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. Various fresh sorbent distribution types and internal structures were modeled numerically to investigate their effect on the gas-solid flow and sulfate reaction characteristics. Experimental results show that, after the fresh sorbent supply was stopped, the desulfurization efficiency declined rapidly even though the sorbent recirculation was maintained. Therefore, the fresh sorbent is the main contributor to the desulfurization process and the primary effect of the recirculated sorbent was to evenly distribute the fresh sorbent and to prolong the sorbent particle residence time. The numerical results demonstrate thatthe desulfurization efficiency varied greatly for the various fresh sorbent bottom injection methods. The desulfurization efficiency of the bottom-even injection method was 1.5 times that of the bottom two-sided injection method. Internal structures effectively improved the fresh sorbent solids concentration distribution and the desulfurization efficiency. Optimized internal structures increased the desulfurization efficiency of the bottom two-sided injection method by 46%, so that it was very close to that of the bottom-even injection method with only a 4.6% difference.

Effect of operating parameters and reactor structure on moderate temperature dry desulfurization.

A moderate temperature dry desulfurization process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed flue gas desulfurization (CFB-FGD) experimental facility. The desulfurization efficiency was investigated for various operating parameters, such as bed temperature, CO2 concentration, and solids concentration. In addition, structural improvements in key parts of the CFB-FGD system, i.e., the cyclone separator and the distributor, were made to improve the desulfurization efficiency and flow resistance. The experimental results show that the desulfurization efficiency increased rapidly with increasing temperature above 600 degrees C due to enhanced gas diffusion and the shift of the equilibrium for the carbonate reaction. The sorbent sulfated gradually after quick carbonation of the sorbent with a long particle residence time necessary to realize a high desulfurization ratio. A reduced solids concentration in the bed reduced the particle residence time and the desulfurization efficiency. A single-stage cyclone separator produced no improvement in the desulfurization efficiency compared with a two-stage cyclone separator. Compared with a wind cap distributor, a large hole distributor reduced the flow resistance which reduced the desulfurization efficiency due to the reduced bed pressure drop and worsened bed fluidization. The desulfurization efficiency can be improved by increasing the collection efficiency of fine particles to prolong their residence time and by improving the solids concentration distribution to increase the gas-solid contact surface area.

Simultaneous removal of SO2 and trace SeO2 from flue gas: effect of product layer on mass transfer.

Sulfur dioxide (SO2) and trace elements are all pollutants derived from coal combustion. This study relates to the simultaneous removal of sulfur and trace selenium dioxide (SeO2) by calcium oxide (CaO) adsorption in the medium temperature range, especially the mass transfer effect of sulfate product layer on trace elements. Through experiments on CaO adsorbing different concentrations of SO2 gases, conclusions can be drawn that although the product layer introduces extra mass transfer resistance into the sorbent-gas reaction process, the extent of CaO adsorption ability loss due to this factor decreases with decreasing SO2 concentration. When the gas concentration is at trace level, the loss of CaO adsorption ability can be neglected. Subsequent experiments on CaO adsorbing trace SeO2 gas suggest that the sulfate product layer, whether it is thick or thin, has no obvious effect on the CaO ability to adsorb trace SeO2 gas.

Simultaneous removal of SO2 and trace SeO2 from flue gas: effect of SO2 on selenium capture and kinetics study.

Sulfur dioxide (SO2) and trace elements are all pollutants derived from coal combustion. This study relates to the simultaneous removal of SO2 and trace selenium dioxide (SeO2) from flue gas by calcium oxide (CaO) adsorption in the moderate temperature range, especially the effect of SO2 presence on selenium capture. Experiments performed on a thermogravimetric analyzer (TGA) can reach the following conclusions. When the CaO conversion is relatively low and the reaction rate is controlled by chemical kinetics, the SO2 presence does not affect the selenium capture. When the CaO conversion is very high and the reaction rate is controlled by product layer diffusion, the SO2 presence and the product layer diffusion resistance jointly reduce the selenium capture. On the basis of the kinetics study, a method to estimate the trace selenium removal efficiency using kinetic parameters and the sulfur removal efficiency is developed.

Novel dry-desulfurization process using Ca(OH)2/fly ash sorbent in a circulating fluidized bed.

A dry-desulfurization process using Ca(OH)2/fly ash sorbent and a circulating fluidized bed (CFB) was developed. Its aim was to achieve high SO2 removal efficiency without humidification and production of CaSO4 as the main byproduct. The CaSO4 produced could be used to treat alkalized soil. An 83% SO2 removal rate was demonstrated, and a byproduct with a high CaSO4 content was produced through baghouse ash. These results indicated that this process could remove SO2 in flue gas with a high efficiency under dry conditions and simultaneously produce soil amendment. It was shown that NO and NO2 enhanced the SO2 removal rate markedly and that NO2 increased the amount of CaSO4 in the final product more than NO. These results confirmed that the significant effects of NO and NO2 on the SO2 removal rate were due to chain reactions that occurred under favorable conditions. The amount of baghouse ash produced increased as the reaction progressed, indicating that discharge of unreacted Ca(OH)2 from the reactor was suppressed. Hence, unreacted Ca(OH)2 had a long residence time in the CFB, resulting in a high SO2 removal rate. It was also found that 350 degrees C is the optimum reaction temperature for dry desulfurization in the range tested (320-380 degrees C).

[A novel calibration technique for quantitative analysis of FTIR spectra].

Fourier transform infrared spectroscopy (FTIR) can be used for the continuously on-line quantitative determination of the concentrations of several gas components in smoke gas. The process of acquiring accurate calibration of spectra is one of the most important steps in the quantitative analysis. In the present paper, a novel calibration technique was proposed and evaluated by the results of CO and HCl. Data obtained by this new technique were compared to those of conventional concentration-based calibration. The results showed that this calibration technique is feasible, and its reliability and validity were also confirmed. Further more, it has several other advantages, which will also be discussed here. Finally, the calibration problem that the substances are liquid at ambient temperature was solved by this technique.