Xueyong Li

Antibacterial activity of nanofibrous mats coated with lysozyme-layered silicate composites via electrospraying.

A mixture of positively charged lysozyme (LY) and rectorite (REC) composites was electrosprayed onto negatively charged electrospun cellulose acetate (CA) nanofibrous mats. The morphology and average diameter of CA mats and the mats coated with LY-REC were investigated by scanning electron microscopy. The composite mats were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy, and the results confirmed that LY and REC were successfully immobilized on the surface of CA mats via electrospraying technique. The small-angle X-ray diffraction results showed that the silicate layers of REC were completely exfoliated. The enzyme activity and bacterial inhibition analysis verified that the antimicrobial effect of the composite fibrous mats was enhanced with the addition of REC. The protein delivery properties and the bound enzyme activity after removal of unbound lysozyme from fibers were measured and showed that the electrospraying technique was suitable for enzyme immobilization.

The status of microRNA-21 expression and its clinical significance in human cutaneous malignant melanoma.

Dysregulation of microRNA-21 plays critical roles in tumor initiation and progression. The purpose of this study was to investigate the status of microRNA-21 expression in human cutaneous malignant melanoma and determine its clinical significance. TaqMan(®) real-time RT-PCR assay was performed to examine the expression of microRNA-21 in 10 cases of dysplastic nevi, 86 cases of primary cutaneous melanomas, 10 cases of melanoma metastases. The correlation of microRNA-21 expression with clinicopathological factors or prognosis of patients with cutaneous melanoma was statistically analyzed. Additionally, the effects of microRNA-21 expression on growth, apoptosis and chemo- or radiosensitivity of melanoma cells were also investigated by transfection of microRNA-21 inhibitor. We firstly showed that increased levels of microRNA-21 expression were shown from dysplastic nevi to primary cutaneous melanomas to melanoma metastases. Moreover, high miR-21 expression was found to be correlated with Breslow thickness and advanced clinical stage. Patients with high microRNA-21 expression showed shorter 5-year disease-free or overall survival than those with low microRNA-21 expression. Furthermore, multivariate regression analysis showed that the status of microRNA-21 expression was an independent prognostic factor for overall survival of patients. Antisense-mediated microRNA-21 inhibition could significantly suppress growth, increase apoptosis and enhance chemo- or radiosensitivity of human cutaneous melanoma cells by inducing the increased Bax/Bcl-2 ratio. Thus, the status of microRNA-21 might be an independent prognostic factor for patients with cutaneous melanoma, and microRNA-21 has the potential of being a novel molecular target for the treatment of human cutaneous melanoma.

Poly(vinyl alcohol)/sodium alginate/layered silicate based nanofibrous mats for bacterial inhibition

Poly(vinyl alcohol) (PVA)/sodium alginate (ALG)/organic rectorite (OREC) composite nanofibrous mats are fabricated by electrospinning aqueous solutions with different mixing ratios. Both good fiber shape and three-dimensional structure of nanofibrous mats can be observed by Field Emission Scanning Electron Microscopy. Energy-dispersive X-ray spectroscopy shows the existence of OREC in the as-spun composite mats. In addition, small-angle X-ray diffraction confirms that the interlayer of OREC is intercalated by ALG/PVA chains, and the distance between OREC interlayers is increased from 4.50 to 4.74 nm. Wide angle X-ray diffraction and Fourier transform infrared spectra further verify the intercalation is between polymers and layered silicate. Moreover, the thermal gravimetric analysis shows that the addition of OREC has only a small effect on the thermal stability of composites. Furthermore, the antibacterial experiments illustrate that OREC can enhance the bacterial inhibition ability of nanofibrous mats against Escherichia coli and Staphylococcus aureus.

Characterization and cytotoxicity study of nanofibrous mats incorporating rectorite and carbon nanotubes

In order to investigate whether the incorporation of multi-walled carbon nanotubes (MWCNTs) and rectorite (REC) could improve and extend the properties of nanofibrous mats, poly(lactic acid)/MWCNTs/REC ternary composite nanofibrous mats were fabricated via an electrospinning technique. The composite mats still kept a typical electrospun fiber shape and possessed a three-dimensional structure. X-ray photoelectron spectroscopy verified that the addition of MWCNTs and REC was successful. The surface structure of the mats was also analyzed by Raman spectroscopy. Besides, the poly(lactic acid) (PLA) chains could enlarge the interlayer distance of REC, which was confirmed by small-angle X-ray diffraction. Wide-angle X-ray diffraction showed that a higher content of MWCNTs could improve the crystallization of PLA. Thermal analysis results demonstrated that MWCNTs and REC could increase the thermal stability of the composite mats. The cell experiment results indicated that the incorporation of both MWCNTs and REC had little influence on the cell compatibility of the resultant composite mats.

Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro.

Aim:To examine the changes in electrolyte concentrations after addition of zeolite-based hemostat QuikClot in blood and the effects of zeolite on blood coagulation in vitro.Methods:Fresh blood was taken from healthy adult volunteers and sheep, and the electrolyte concentrations in blood were measured using a blood electrolyte analyzer. Zeolite Saline Solution (ZSS) was prepared by addition of 2 g zeolite to 0.9% NaCl solution (4, 8, or 16 mL). The electrolytes in ZSS were measured using inductively coupled plasma atomic emission spectroscopy. The prothrombin time (PT) and activated partial thromboplastin time (APTT) of blood were measured using the test tube method. The activated clotting time (ACT) and clotting rate (CR) of blood were measured with Sonoclot Coagulation and Platelet Function Analyzer.Results:Addition of zeolite (50 and 100 mg) in 2 mL human blood significantly increased Ca2+ concentration, while Na+ and K+ concentrations were significantly decreased. Addition of zeolite (50 and 100 mg) in 0.9% NaCl solution (2 mL) caused similar changes in Ca2+ and Na+ concentrations. Si4+ (0.2434 g/L) and Al3+ (0.2575 g/L) were detected in ZSS (2 g/8 mL). Addition of ZSS in sheep blood shortened APTT in a concentration dependent manner, without changing PT. ZSS or aqueous solution of CaCl2 that contained Ca2+ concentration identical to that of ZSS significantly shortened ACT in human blood without significantly changing CR, and the effect of ZSS on ACT was not significantly different from that of CaCl2.Conclusion:Zeolite releases Ca2+ into blood, thus accelerating the intrinsic pathway of blood coagulation and shortening the clot formation time.

Cytotoxicity and antibacterial ability of scaffolds immobilized by polysaccharide/layered silicate composites.

Chitosan and pectin/organic rectorite (OREC) were initially deposited on the surface of cellulose acetate electrospun nanofibers by a layer-by-layer (LBL) technique to fabricate scaffolds for bacterial inhibition, and the cytotoxicity of the LBL structured scaffolds was also investigated. A couple of opposite charged material, pectin and OREC, were firstly used to fabricate the intercalated composites. The intercalated structure was determined by selected area electron diffraction. Field-emission scanning electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy were applied for the characterization of LBL structured nanofibrous scaffolds. Antibacterial assay results showed that the diameters of the inhibition zone increased from 7.6 to 15.8 mm for Escherichia coli, as well as from 7.4 to 14.2 mm for Staphylococcus aureus. Finally, human epidermal (EP) cells grew well on the LBL films coating. These novel scaffolds could be an ideal candidate for wound dressings and food packaging.

Epidemiological studies of electrical injuries in Shaanxi Province of China: A retrospective report of 383 cases

A statistical survey was conducted at the Burn Unit of the Tangdu Hospital, Shaanxi, China, during the 10-year period from January 2000 to December 2009. In this retrospective study, 383 patients who admitted to our burn unit because of electrical trauma were included. Data including the patients general condition, clinical presentation, complications and operation times was collected retrospectively and analyzed with epidemiological methods. Subjects in our collective were predominantly male (90.3%, n=346/383) and were composed by those who injured in work-related incidents (78.3%, n=300/383), rural individuals (58.2%, n=223/383) and students (9.4%, n=36/383). High voltage was directly correlated to severity clinical complications, and amputation. The percentage of myocardial impairment was 79.3% (n=92/116) among patients who suffered with electrical current through heart tissue. Along with the more developed east area of China, electrical injuries are becoming a growing concern of the developing West part in China as well. Electrical injuries induce serious tissue damage, need long hospital stay, and result in high rate of permanent disability and economic hardship for the afflicted families. A competent prevention program needs to be developed to address this problem.

Expression of MicroRNA-301a and its Functional Roles in Malignant Melanoma

Background/Aims: Although microRNA-301a has been reported to function as an oncogene in many human cancers, the roles of miR-301a in malignant melanoma (MM) is unclear. The present study aims to investigate the functional roles of miR-301a in MM and its possible molecular mechanisms. Methods: Quantitative real-time PCR (qRT-PCR) assay was performed to detect the expression of miR-301a in MM tissues, and analyze its correlation with metastasis and prognosis of MM patients. In vitro, miR-301a was ectopically expressed using overexpression and knock-down strategies, and the effects of miR-301a expression on growth, apoptosis, migration, invasion and chemosensitivity of MM cells were further investigated. Furthermore, the potential and functional target gene was identified by luciferase reporter, qRT-PCR, Western blot assays. Results: We showed that the expression of miR-301a was significantly upregulated in MM tissues, and upregulation of miR-301a correlated with metastasis and poor prognosis of MM patients. Transfection of miR-301a/inhibitor significantly inhibited growth, colony formation, migration, invasion and enhanced apoptosis and chemosensitivity in MM cells, while transfection of miR-301a/mimic could induce the inverse effects on phenotypes of MM cells. Luciferase reporter, qRT-PCR and Western blot assays showed that phosphatase and tensin homolog (PTEN) was a direct and functional target of miR-301a. It was also observed that the Akt and FAK signaling pathways were involved in miR-301/PTEN-promoting MM progression. Conclusion: Taken together, our study suggests that miR-301a may be used as a potential therapeutic target in the treatment of human MM.

Treatment of infected soft tissue blast injury in swine by regulated negative pressure wound therapy.

Objective: This study was designed to investigate the therapeutic potential of regulated negative pressure wound therapy (RNPT) in treating infected blast injuries in swine. Background: Approximately 30% to 80% of blast injuries develop infection, which increases the morbidity and mortality of these casualties. RNPT has been used in US military operations in Iraq; however, no randomized controlled study has been conducted on the use of RNPT to treat infected war injuries. Methods: Infected soft tissue blast injuries were treated with gauze dressings or RNPT with different pressures ranging from −5 to −35 kPa. To evaluate the wound healing process, the wound area, wound depth, the number of proliferative cells, and the vascular endothelial cells in the granulation tissue were measured at different time points. Furthermore, to evaluate the infection and inflammation of the blast injury, the bacterial load, bacterial species, and several inflammatory markers were detected. Results: Compared with gauze dressing treatments, RNPT reduced bacterial load more efficiently, initiated granulation tissue formation earlier, and increased the inflammation faster. Negative pressures ranging from −10 to −25 kPa applied on the RNPT group showed beneficial effects in treating the infected soft tissue blast injury. RNPT did not significantly change both the aerobic and anaerobic bacterial composition compared with those of the gauze dressing group. Conclusions: RNPT clearly shows beneficial effects in treating the infected soft tissue blast injury in comparison with the gauze dressing therapy in swine.

Human acellular dermal matrix allograft: A randomized, controlled human trial for the long-term evaluation of patients with extensive burns

The potential of acellular dermal matrix (ADM) to improve cosmetic and functional outcomes has been demonstrated; however, there have been few clinical comparative studies assessing the long-term morphological, histological and functional changes after ADM placement. This study was designed to retrospectively evaluate the long-term outcomes of the cograft acellular dermal matrix with autologous thin split-thickness skin for the coverage of wounds in extensively burned patients. Thirty burn patients treated with a composite graft of ADM with autologous split-thickness skin from January 2007 to December 2009 were enrolled in this study. Another group of thirty patients who received only an autogenous split-thickness skin implant served as the control. Our study revealed that the collagen in the dermis treated with ADM were ordered, and the proportion of collagen III/I was much higher in the control group than in the ADM group. The basement membrane was prominent and continuous. Meanwhile, the VBSS (Vancouver Burn Skin Score) was used to evaluate skin quality, which shows a significant differences between the two group (P<0.001). Then the functional level was evaluated by the BI (Barthel Index), and the ADM group was much better than the control group (P=0.005). Based on these results, we concluded that the composite graft of ADM with autologous thin split-thickness skin was suitable for repairing the defects in functional areas after a burn. This technique might facilitate wound management with acceptable esthetic outcomes, good functional recovery and less scar hyperplasia at the donor site.