Investigating the Corrosive Influence of Chloride Ions on Slag Recovery Machine Inner Guide Wheel in Power Plants.

An important method that coal-fired power plants use to realise low-cost zero discharge of desulfurisation wastewater (FGD wastewater) is to utilise wet slag removal systems. However, the high Cl- content of FGD wastewater in wet slag removal systems causes environmental damage. In this study, the corrosion behaviour of the inner guide wheel material, 20CrMnTi, was studied using dynamic weight loss and electrochemical methods. X-ray diffraction, scanning electron microscopy, and energy spectroscopy were used to analyse the organisational and phase changes on the surfaces and cross sections of the samples at different Cl- concentrations. The corrosion rate increased with the Cl- concentration up to 20 g/L, but it decreased slightly when the Cl- concentration exceeded 20 g/L. In all the cases, the corrosion rate exceeded 0.8 mm/a. The corrosion product film density initially increased and then decreased as the Cl- concentration increased. The corrosion products comprised mainly α-FeOOH, γ-FeOOH, ß-FeOOH, Fe3O4, and γ-Fe2O3.

The Effects of the Pre-Anodized Film Thickness on Growth Mechanism of Plasma Electrolytic Oxidation Coatings on the 1060 Al Substrate.

To increase the density of the micro-arc oxide coating, AA 1060 samples were pretreated with an anodic oxide film in an oxalic acid solution. Plasma electrolytic oxidation (PEO) was performed to investigate the effect of the thickness of the pre-anodic oxide film on the soft-sparking mechanism. The experimental results revealed that the PEO coating phases with different thicknesses of the pre-anodized films contained both Al and gamma-alumina (γ-Al2O3). The pre-anodized film changes the final morphology of the coating, accelerating the soft sparking transition and retaining the soft sparking. At a pre-anodized film thickness of ≤7.7 µm, the anodized films thickened before being broken through. When the pre-anodized film thickness was ≥13.1 µm, partial dissolution of the anodized films occurred before they were struck through. Two growth mechanisms for PEO coatings with different pre-anodized film thicknesses were proposed.

Preparation and Modification of Polydopamine Boron Nitride-Titanium Dioxide Nanohybrid Particles Incorporated into Zinc Phosphating Bath to Enhance Corrosion Performance of Zinc Phosphate-Silane Coated Q235 Steel.

In this work, PDA@BN-TiO2 nanohybrid particles were incorporated chemically into a zinc-phosphating solution to form a robust, low-temperature phosphate-silane coating on Q235 steel specimens. The morphology and surface modification of the coating was characterized by X-Ray Diffraction (XRD), X-ray Spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), and Scanning electron microscopy (SEM). Results demonstrate that the incorporation of PDA@BN-TiO2 nanohybrids produced a higher number of nucleation sites and reduced grain size with a denser, more robust, and more corrosion-resistant phosphate coating compared to pure coating. The coating weight results showed that the PBT-0.3 sample achieved the densest and most uniform coating (38.2 g/m2). The potentiodynamic polarization results showed that the PDA@BN-TiO2 nanohybrid particles increased phosphate-silane films' homogeneity and anti-corrosive capabilities. The 0.3 g/L sample exhibits the best performance with an electric current density of 1.95 × 10-5 A/cm2, an order of magnitude lower than that of the pure coatings. Electrochemical impedance spectroscopy revealed that PDA@BN-TiO2 nanohybrids provided the greatest corrosion resistance compared to pure coatings. The corrosion time for copper sulfate in samples containing PDA@BN/TiO2 prolonged to 285 s, a significantly higher amount of time than the corrosion time found in pure samples.

Decellularized tympanic membrane scaffold with bone marrow mesenchymal stem cells for repairing tympanic membrane perforation.

BACKGROUND: Tympanic membrane perforation (TMP) is a common disease in otology, and few acellular techniques have been reported for repairing this condition. Decellularized extracellular matrix (ECM) scaffolds have been used in organ reconstruction. OBJECTIVE: This study on tissue engineering aimed to develop a tympanic membrane (TM) scaffold prepared using detergent immersion and bone marrow mesenchymal stem cells (BMSCs) as repair materials to reconstruct the TM. RESULTS: General structure was observed that the decellularized TM scaffold with BMSCs retained the original intact anatomical ECM structure, with no cell residue, as observed using scanning electron microscopy (SEM), and exhibited low immunogenicity. Therefore, we seeded the decellularized TM scaffold with BMSCs for recellularization. Histology and eosin staining, SEM and immunofluorescence in vivo showed that the recellularized TM patch had a natural ultrastructure and was suitable for the migration and proliferation of BMSCs. The auditory brainstem response (ABR) evaluated after recellularized TM patch repair was slightly higher than that of the normal TM, but the difference was not significant. CONCLUSION: The synthetic ECM scaffold provides temporary physical support for the three-dimensional growth of cells during the tissue developmental stage. The scaffold stimulates cells to secrete their own ECM required for tissue regeneration. The recellularized TM patch shows potential as a natural, ultrastructure biological material for TM reconstruction.

The Microstructure Evolution Process and Flexural Behaviours of SiC Matrix Ceramic Infiltrated by Aluminium Base Alloy.

In this paper, an infiltration approach was proposed to generate a Ti3Si(Al)C2 transition layer in SiC matrix composites to effectually strengthen SiC ceramics. The infiltration temperature played a significant role in the evolution of the microstructure, phase composition, and flexural behaviours. Molten aluminium base alloy fully penetrated SiC ceramic after infiltration at different experimental temperatures (800-1000 °C). The phases in the reaction layer on the surface of SiC ceramic samples varied with the infiltration temperature. When infiltrated at 800 °C, only SiC and Al phases can be found in SiC composites, whereas at 900 °C, a reaction layer containing Ti3Si(Al)C2 and SiC was produced. The Ti3Si(Al)C2 phase grew in situ on SiC. At 1000 °C, the Ti3Si(Al)C2 phase was unstable and decomposed into TiC and Ti5Si3. The cermet phase Ti3Si(Al)C2 was synthesized at a relatively low temperature. Consequently, the flexural modulus and three-point bending strength of samples infiltrated at 900 °C was enhanced by 1.4 and 2.4 times for the original SiC ceramic, respectively.

Association between Traumatic Subarachnoid Hemorrhage and Acute Respiratory Failure in Moderate-to-Severe Traumatic Brain Injury Patients.

Acute respiratory failure (ARF) with a high incidence among moderate-to-severe traumatic brain injury (M-STBI) patients plays a pivotal role in worsening neurological outcomes. Traumatic subarachnoid hemorrhage (tSAH) is highly prevalent in M-STBI, which is associated with significant adverse outcomes. In this retrospective cohort study, we aimed to explore the association between the severity of the tSAH and ARF in the M-STBI population. A total of 771 subjects were reviewed. Clinical and neuroimaging data of M-STBI patients were retrospectively collected, and ARF was ascertained retrospectively based on their electronic medical record. The degree of tSAH was classified according to Fisher's criteria, and the grade of tSAH was dichotomized to a low Fisher grade (Fisher grade 1-2) and a high Fisher grade (Fisher grade 3-4). After exclusion procedures, the data of 695 M-STBI patients were analyzed. A total of 284 (30.8%) had a high Fisher grade on admission. The overall rate of ARF within 48 h upon admission was 34.4% (239/695); it was 29.5% (142/481) and 46.3% (99/214) for the low and high Fisher groups, respectively. In a full cohort, a high Fisher grade was associated with ARF after adjusting for age, gender, GCS, smoking history, comorbidities, multiple injuries, characteristics of TBI, and pulmonary factors (OR 1.78; 95% CI, 1.11-2.85, p = 0.016). This result remained robust in the comparisons after PSM (71/132, 42.8% vs. 53/132, 31.9%; OR, 1.59; 95% CI, 1.02-2.49, p = 0.042). A high Fisher SAH grade exposure on admission is associated with ARF in M-STBI patients.

Quantifying the Improvement in Dielectric Properties of BaSrTiO3-Based Ceramics by Adding MgO.

Barium titanate (BaTiO3, BT) is the main raw material of multilayer ceramic capacitors. As thinner layers of dielectric elements require smaller BT grain diameters, BT-MgO composites have been widely studied owing to the plasticity of MgO and its inhibition of grain growth. However, further improvements of the dielectric properties of the BT-MgO system are still urgently needed. Herein, composite ceramics of Ba0.7Sr0.3Ti0.9925Tm0.01O3 (BST)-x mol% MgO (x = 1, 2, 3, 4, 5) were prepared. The dielectric constant of BST-1 mol% MgO at room temperature was approximately 3800, which was 1/3 times higher than that of BT-MgO composite ceramics. The dielectric loss was less than 0.004 and 2/3 that of BT-MgO composite ceramics. The Curie temperature of BST doped with MgO was below 0 °C. The anomalous increase in dielectric constant was caused by the co-doping of Sr and Tm with BT, while the reduced dielectric loss was due to the uniform dispersion of MgO at grain boundaries, which hinders grain growth. The Curie temperature shift was mainly due to accumulated oxygen vacancies. Thus, this work provides new solutions to further improve the dielectric properties of the BT-MgO system, including changing the doping elements and adjusting the doping ratio.

Development of a decellularized hypopharynx with vascular pedicle scaffold for use in reconstructing hypopharynx.

BACKGROUND: Hypopharynx reconstruction after hypopharyngectomy is still a great challenge. Perfusion decellularization is for extracellular matrix (ECM) scaffolding and had been used in organ reconstruction. Our study aimed to prepare an acellular, natural, three-dimensional biological hypopharynx with vascular pedicle scaffold as the substitute materials to reconstruct hypopharynx. RESULT: Scanning electron microscope and histology staining showed that the decellularized hypopharynx with vascular pedicle scaffold retained intact native anatomical ECM structure. Myoblasts were observed on the recellularized scaffolds with bone marrow mesenchymal stem cells induced by 5-azacytidine implanted in the rabbit greater omentum by immunohistochemical analysis. CONCLUSION: The decellularized hypopharynx with vascular pedicle scaffold prepared by detergent perfusion in our study has a potential to be an alternative material to pharynx reconstruction.

Erratum: Study on clinical characteristics of 173 cases of COVID-19 and effect of glucocorticoid on nucleic acid negative conversion.

[This corrects the article on p. 4251 in vol. 13, PMID: 34150012.].

Tissue-engineered esophagus: recellular esophageal extracellular matrix based on perfusion-decellularized technique and mesenchymal stem cells.

Perfusion-decellularization was an interesting technique to generate a natural extracellular matrix (ECM) with the complete three-dimensional anatomical structure and vascular system. In this study, the esophageal ECM (E-ECM) scaffold was successfully constructed by perfusion-decellularized technique through the vascular system for the first time. And the physicochemical and biological properties of the E-ECM scaffolds were evaluated. The bone marrow mesenchymal stem cells (BMSCs) were induced to differentiate into myocytesin vitro. E-ECM scaffolds reseeded with myocytes were implanted into the greater omenta to obtain recellular esophageal ECM (RE-ECM), a tissue-engineered esophagus. The results showed that the cells of the esophagi were completely and uniformly removed after perfusion. E-ECM scaffolds retained the original four-layer organizational structure and vascular system with excellent biocompatibility. And the E-ECM scaffolds had no significant difference in mechanical properties comparing with fresh esophagi,p> 0.05. Immunocytochemistry showed positive expression ofα-sarcomeric actin, suggesting that BMSCs had successfully differentiated into myocytes. Most importantly, we found that in the RE-ECM muscularis, the myocytes regenerated linearly and continuously and migrated to the deep, and the tissue vascularization was obvious. The cell survival rates at 1 week and 2 weeks were 98.5 ± 3.0% and 96.4 ± 4.6%, respectively. It was demonstrated that myocytes maintained the ability for proliferation and differentiation for at least 2 weeks, and the cell activity was satisfactory in the RE-ECM. It follows that the tissue-engineered esophagus based on perfusion-decellularized technique and mesenchymal stem cells has great potential in esophageal repair. It is proposed as a promising alternative for reconstruction of esophageal defects in the future.

Study on clinical characteristics of 173 cases of COVID-19 and effect of glucocorticoid on nucleic acid negative conversion.

Objective: To study the clinical characteristics, changes in relevant test parameters, time of nucleic acid negative conversion, and effect of glucocorticoid treatment in Wuhan area patients with the novel coronavirus pneumonia (COVID-19). Methods: Data of 173 inpatients at Huoshenshan Hospital from February 10 to March 17, 2020, were analyzed retrospectively. Clinical characteristics, partial test results, and the influence of glucocorticoid therapy on the clinical outcomes of nucleic acid negative conversion and changes in lung CT images were compared. The patients were divided at admission into 4 groups according to the course of disease and glucocorticoid treatment. Differences among the groups were analyzed statistically. Results: The median age of 173 patients was 62 years, and 91.3% were over 40 years old. Underlying diseases occurred in 50.3% of patients, 32.6% had family gatherings, and 24.3% had exposure while shopping or at a hospital. Median times of nucleic acid negative conversion in group A+B (course of disease < 3 weeks) and group C+D (course of disease ≥ 3 weeks) were 23 days and 37 days, respectively (P < 0.05). Other group comparisons, i.e., of A+C with B+D, A with B, or C with D, were not statistically different. One week after reexamination, chest CT lesion area had changed by 52% in group C and 50% in group D (P > 0.05). In some patients, administration of glucocorticoid for more than 4 weeks significantly promoted the reduction of inflammatory shadow in the lung. Conclusion: Most patients hospitalized with COVID-19 in Wuhan were middle-aged and elderly people with underlying diseases and a history of family gatherings. Glucocorticoid therapy did not affect nor prolong the duration of nucleic acid negative conversion. Glucocorticoid therapy could promote improvement of lung lesions within 3 weeks after disease onset. Beyond 3 weeks, the treatment did not promote reduction in lung shadow area, however the density of shadow did decrease.

Risk Factors for COVID-19 in Patients with Hypertension.

BACKGROUND: Hypertension, as the most common comorbidity for patients with coronavirus disease 19 (COVID-19), has resulted in cases with more severe symptoms and higher mortality. The risk factors associated with COVID-19 in patients with hypertension are unknown. METHODS: All the available and confirmed patients with COVID-19 from February 3 to March 10, 2020, were enrolled from Huoshenshan Hospital, Wuhan, China. The demographic characteristics, clinical manifestations, laboratory data, radiological assessments, and treatments on admission were extracted and compared. Univariate and multivariate logistic regression methods were used to explore risk factors associated with COVID-19 in patients with hypertension and the severity of the cohort. RESULTS: A total of 430 available patients with COVID-19 were enrolled in the study, including 151 eligible patients with COVID-19 and hypertension. After PSM analysis, 141 patients without hypertension and 141 cases with hypertension were well matched. Compared with cases without hypertension, patients with hypertension were more severe (28.4% vs. 12.1%, p=0.001). In multivariate analysis, we found that neutrophil count (OR: 1.471; p=0.001), coronary heart disease (OR: 5.281; p=0.011), and the level of K+ (OR: 0.273; p < 0.001) were associated with patients with hypertension. In addition, the percentage of pulmonary infection volume was larger in cases with hypertension (4.55 vs. 5.8, p=0.017) and was a high risk factor for severe COVID-19 in patients with hypertension (OR: 1.084; p < 0.001). CONCLUSION: On admission, coronary heart disease, neutrophil count, and the level of K+ were associated with COVID-19 patients with hypertension. The percentage of the pulmonary infection volume was significantly larger in COVID-19 patients with hypertension and was a risk factor for COVID-19 severity of the cohort.

Biomechanical changes of freezer-storaged and decellularized pig tracheal scaffoldings.

BACKGROUND: As an excellent xenotransplant, the pig trachea can be decellularized and cryopreserved to reduce its immunogenicity. However, few reports are found on the changes of its mechanical properties after cryopreservation and decellularization. OBJECTIVE: To evaluate the structure and biomechanical properties in pig tracheal scaffolds resulting from decellularized and cryopreserved. MATERIAL AND METHODS: Twenty-five pig tracheal segments were separated into five groups: untreated (group A), only decellularized (group B), only cryopreserved (group C), decellularized after cryopreserved (group D) and cryopreserved after decellularized (group E). Tracheal segments were subjected to uniaxial tension or compression using a universal testing machine to determine structural biomechanical changes. RESULTS: It showed that there was no statistically significant difference in the tensile strength of the trachea in each group. The compressive strength of group B, C and D were same as the group A (P > 0.05), while the group E was lower than that of the group A (P < 0.05).Conclusions and significance: The histological examination of the decellularization after cryopreservation shows that the removal of epithelial cells and submucosal cells is more thorough, and the biomechanical structure of the trachea is better preserved. This proved to be a new method to prepare xenotransplantation of trachea graft.

De-Epithelialized Heterotopic Tracheal Allografts without Immunosuppressants in Dogs: Long-Term Results for Cartilage Viability and Structural Integrity.

OBJECTIVES: Reconstruction of long segmental tracheal defects is difficult because no ideal tracheal substitutes are currently available. Tracheal allotransplantation maintains cartilage and epithelium viability but requires immunosuppression because of epithelial immunogenicity. We aimed to obtain an epithelium-decellularized allograft that maintains cartilage viability and to evaluate long-term outcomes of such allografts implanted on dog backs without immunosuppressants. METHODS: Twenty-five tracheas harvested from mongrel dogs were used to explore the period of epithelium decellularization by combined use of 1% sodium dodecyl sulfate and an organ preservation solution and to assess the chondrocyte viability and immunogenicity of the tracheas after decellularization. Sixteen epithelium-decellularized tracheal allografts and 10 fresh tracheal segments (6 cm long) were implanted in 26 beagles for durations of 10 days and 1, 3, 6, and 12 months. Macroscopic and microscopic examinations were used to evaluate the morphology, viability, and immune rejection of the allografts. Safranin-O staining was used to detect glycosaminoglycans. RESULTS: The epithelium disappeared after 24 hours of decellularization. At 72 hours, almost no nuclei remained in the mucosa, while the mean survival rate of chondrocytes was 88.1%. Histological analysis demonstrated that the allograft retained intact tracheal rings and viable cartilage after heterotopic implantation for 1 year, with no immunological rejection. There were no significant differences in the glycosaminoglycan contents among the implanted epithelium-decellularized allografts. CONCLUSIONS: Epithelium-decellularized tracheal allografts with chondrocyte viability can be achieved by combined use of a detergent and organ preservation solution, which showed satisfactory cartilage viability and structural integrity after long-term heterotopic transplantation. Further studies on orthotopic transplantation are needed to assess the feasibility of allografts in reconstructing long segmental tracheal defects.

Automated detection and quantification of COVID-19 pneumonia: CT imaging analysis by a deep learning-based software.

BACKGROUND: The novel coronavirus disease 2019 (COVID-19) is an emerging worldwide threat to public health. While chest computed tomography (CT) plays an indispensable role in its diagnosis, the quantification and localization of lesions cannot be accurately assessed manually. We employed deep learning-based software to aid in detection, localization and quantification of COVID-19 pneumonia. METHODS: A total of 2460 RT-PCR tested SARS-CoV-2-positive patients (1250 men and 1210 women; mean age, 57.7 ± 14.0 years (age range, 11-93 years) were retrospectively identified from Huoshenshan Hospital in Wuhan from February 11 to March 16, 2020. Basic clinical characteristics were reviewed. The uAI Intelligent Assistant Analysis System was used to assess the CT scans. RESULTS: CT scans of 2215 patients (90%) showed multiple lesions of which 36 (1%) and 50 patients (2%) had left and right lung infections, respectively (> 50% of each affected lung's volume), while 27 (1%) had total lung infection (> 50% of the total volume of both lungs). Overall, 298 (12%), 778 (32%) and 1300 (53%) patients exhibited pure ground glass opacities (GGOs), GGOs with sub-solid lesions and GGOs with both sub-solid and solid lesions, respectively. Moreover, 2305 (94%) and 71 (3%) patients presented primarily with GGOs and sub-solid lesions, respectively. Elderly patients (≥ 60 years) were more likely to exhibit sub-solid lesions. The generalized linear mixed model showed that the dorsal segment of the right lower lobe was the favoured site of COVID-19 pneumonia. CONCLUSION: Chest CT combined with analysis by the uAI Intelligent Assistant Analysis System can accurately evaluate pneumonia in COVID-19 patients.

Etiology of Community-Acquired Pneumonia Requiring Hospital Admission in Adults with and Without Cancers: A Single-Center Retrospective Study in China.

BACKGROUND: The etiology and distribution of community-acquired pneumonia (CAP) vary periodically and geographically. The clinical evaluation of CAP among patients with cancers remains unknown. PATIENTS AND METHODS: This retrospective hospital-based study on adult CAP was conducted in Tang Du Hospital, China, from September 2018 to August 2019. The demographic characteristics, clinical manifestations and laboratory data were extracted from medical records and compared between CAP patients with and without cancers. Univariable and multivariable logistic regression methods were used to explore risk factors associated with CAP patients with and without cancers. RESULTS: Data from 149 CAP patients with cancers and 268 CAP patients without cancers were analyzed. Patients without cancers were more likely to show fever, cough and yellow sputum, higher level of neutrophil count than the cancer patients. Klebsiella pneumoniae (K. pneumoniae 14.77% vs 9.33%, p = 0.093) and Streptococcus pneumoniae (S. pneumoniae 16.11% vs 11.57%, p = 0.189) were among the most commonly encountered pathogens in both the groups. Pseudomonas aeruginosa (P. pneumoniae 26.50% vs 11.41%, p < 0.001), Mycoplasma pneumoniae (M. pneumoniae 8.21% vs 1.34%, p = 0.003), and filamentous fungi (10.82% vs 4.7%, p = 0.033) were predominant in CAP patients without cancers. Haemophilus influenzae (H. influenzae 22.15% vs 14.18%, p = 0.038) and methicillin-resistant Staphylococci (MRS 23.49 vs 15.68, p = 0.049) were more prevalent for CAP cancer patients. Certain pathogens were increasing in a cold season. In patients without cancers, MRS, H. influenzae and P. aeruginosa were associated with central nervous system (CNS) disease, connective tissue disease, bronchiectasis, respectively. In addition, healthy adults were likely to be infected with M. pneumoniae showing fever. CONCLUSION: CAP patients with cancers had atypical clinical manifestations and showed no distinct increase in inflammatory markers. The predominant pathogens differed as well as similar between the CAP patients with and without cancers. Certain pathogens follow a seasonal pattern. CNS disease, connective tissue disease and bronchiectasis were associated with the predominant pathogens in patients without cancers.

Effect of Ti Addition on the Microstructure and Mechanical Properties of SiC Matrix Composites Infiltrated by Al⁻Si (10 wt.%)⁻xTi Alloy.

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al⁻Si (10 wt.%)⁻xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al⁻Si (10 wt.%)⁻Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti3Si(Al)C2 phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti⁻Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti3Si(Al)C2 and Ti⁻Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti3Si(Al)C2 phase and small amounts of Ti⁻Al intermetallic compounds.

[RESEARCH PROGRESS OF TISSUE ENGINEERING TECHNIQUE IN ESOPHAGEAL DEFECT REPAIR AND RECONSTRUCTION].

OBJECTIVE: To review the research progress of the tissue engineering technique in the esophageal defect repair and reconstruction. METHODS: The recently published clinical and experimental literature at home and abroad on the scaffold materials and the seeding cells used in the tissue engineered esophageal reconstruction was consulted and summarized. RESULTS: A large number of basic researches and clinical applications show that the effect of the tissue engineered esophagus is close to the autologous structure and function of the esophagus and it could be used for the repair of the esophageal defect. However, those techniques have a long distance from the clinical application and need an acknowledged rule of technology. CONCLUSION: Tissue engineering technique could provide an innovative theory for the esophageal defect reconstruction, but its clinical application need further research.

MicroRNA-24 inhibits growth, induces apoptosis, and reverses radioresistance in laryngeal squamous cell carcinoma by targeting X-linked inhibitor of apoptosis protein.

BACKGROUND: Increasing evidence indicates that dysregulation of microRNAs is involved in tumor progression and development. The aim of this study was to investigate the expression of microRNA-24 (miR-24) and its function in laryngeal squamous cell carcinoma (LSCC). METHODS: Quantitative RT-PCR (qRT-PCR) was used to detect miR-24 expression in LSCC cell lines and tissue samples. MTT, colony formation, and flow cytometry was performed to analyze the effects of miR-24 expression on growth, apoptosis, and radiosensitivity of LSCC cells. Dual-luciferase reporter assays were performed to examine regulation of putative miR-24 targets. Expression of X-linked inhibitor of apoptosis protein (XIAP) mRNA and protein, cleaved or total caspase-3, and cleaved or total PARP protein were detected by qRT-PCR and western blotting assays, respectively. RESULTS: miR-24 expression levels in LSCC cell lines or tissue were significantly lower than in a normal human keratinocyte cell line or adjacent normal tissues. Functional analyses indicated that re-expression of miR-24 inhibits growth, reduces colony formation, and enhances apoptosis in LSCC cells. In addition, miR-24 upregulation increases LSCC sensitivity to irradiation by enhancing irradiation-induced apoptosis, and luciferase activity indicated that miR-24 binds to the 3'-untranslated region (3'-UTR) of XIAP mRNA. Upregulation of miR-24 inhibits XIAP protein expression in LSCC cells, and silencing of XIAP mimics the effects of miR-24 upregulation on LSCC cells. In addition, XIAP mRNA expression significantly increases in LSCC tissues and is inversely correlated with miR-24 expression. CONCLUSIONS: Our data suggest that miR-24 inhibits growth, increases apoptosis, and enhances radiosensitivity in LSCC cells by targeting XIAP. Therefore, miR-24 may be a potential molecular target for the treatment of human LSCC.