Construction and evaluation of an antioxidant synergistic system containing vitamin C and vitamin E.

AIMS: The aim of this study is to develop a liposome that could exert unparalleled antioxidant effects. In the present study, a vitamin C (VC)/vitamin E (VE)-co-loaded multivesicular liposome (VCVE-MVL) was constructed. METHODS: Vitamins were encapsulated in soybean phosphatidylcholine (SPC) and cholesterol (CHO) by multi-emulsification method. The concentration of VC was determined by Fast Blue method. The concentration of VE was determined by high performance liquid chromatography (HPLC). Vitamin antioxidant capacity in vitro and in vivo was determined using ß-carotene bleaching. RESULTS: VCVE-MVL with particle diameter of 848.55 ± 0.29 nm and SPAN of 0.16 ± 0.11 were obtained. The encapsulation efficiency of VC reached 48.51% (w/w)±0.15. Compared with VC/VE solution, VCVE-MVL had a higher permeation efficiency. In addition, the in vitro and ex-vivo antioxidant tests verified the adequate antioxidant activity of VCVE-MVL. CONCLUSIONS: In conclusion, the antioxidant synergistic system we constructed and demonstrated its potential applications in the cosmetics industry.

Quantum Interference-Controlled Conductance Enhancement in Stacked Graphene-like Dimers.

Stacking interactions are of significant importance in the fields of chemistry, biology, and material optoelectronics because they determine the efficiency of charge transfer between molecules and their quantum states. Previous studies have proven that when two monomers are π-stacked in series to form a dimer, the electrical conductance of the dimer is significantly lower than that of the monomer. Here, we present a strong opposite case that when two anthanthrene monomers are π-stacked to form a dimer in a scanning tunneling microscopic break junction, the conductance increases by as much as 25 in comparison with a monomer, which originates from a room-temperature quantum interference. Remarkably, both theory and experiment consistently reveal that this effect can be reversed by changing the connectivity of external electrodes to the monomer core. These results demonstrate that synthetic control of connectivity to molecular cores can be combined with stacking interactions between their π systems to modify and optimize charge transfer between molecules, opening up a wide variety of potential applications ranging from organic optoelectronics and photovoltaics to nanoelectronics and single-molecule electronics.

CS/PVP Hydrogel-Based Nanocapillary for Monitoring Bacterial Growth and Rapid Antibiotic Susceptibility Testing.

Infection with drug-resistant bacteria poses a significant threat to human health. Judicious use of antibiotics could reduce the likelihood of bacterial resistance, which can be evaluated through antibiotic susceptibility testing (AST). This paper focuses on the application of a needle-like nanocapillary tip filled with chitosan (CS)/polyethylene pyrrolidone (PVP) hydrogel based on its specific pH-sensitive properties. The gel-filled nanocapillary has the potential to be used for electrical pH detection with a sensitivity of 3.06 nA/pH and a linear range from 7.3 to 4.3. Such sensitivity for pH measurement could be extended for monitoring of bacterial (such as Escherichia coli and Streptococcus salivarius) growth because of the relationship between pH and bacterial growth. Bacterial growth curves obtained using the hydrogel-filled nanocapillary showed good agreement with the OD600 method. Moreover, this device could be applied for rapid AST for tetracycline and norfloxacin on E. coli with minimum inhibitory concentrations of 2 and 0.125 µg/mL, respectively. This study expands the application of the hydrogel-based nanocapillary for bacterial research by monitoring changes in pH values.

[Preparation of cyclosporine A loaded mPEG-PLGA copolymer micelles and study its pharmacokinetics in rats].

To prepare cyclosporine A (CyA) loaded block copolymer micelles and observe its release behaviors in vitro and pharmacokinetics in rats, methoxylpoly (ethylene glycol)-poly (D, L-lactide-co-glycolide) (mPEG-PLGA) was synthesized by ring-opening copolymerization of lactide and glycolide in the presence of methoxylpoly (ethylene glycol) (mPEG) as initiator. The structure of the mPEG-PLGA copolymer was confirmed with 1H NMR and FT-IR. The cyclosporine A loaded micelles (CyA-PM) were prepared by solvent evaporation method and their morphology was observed by the transmission electron microscope (TEM). The mean size and size distribution were determined by dynamic light scattering (DLS). The release behaviors in vitro and pharmacokinetics in rats were investigated by HPLC method using cyclosporine A injection commercial agent, sandimmune, as the reference. The obtained CyA-PM showed spherical shape with the core-shell structure, the mean particle sizes are in the range of 136.1-141.9 nm. The drug loading amount and entrapment efficiency were increased and the particle size became smaller with decreasing the ratio of acetone to water. With the increasing of the amount of cyclosporine A fed the drug loading increased, entrapment efficiency decreased and the particle size had no change. CyA-PM showed significant sustained release behave in vitro compared with sandimmune and only 9.7% of encapsulated cyclosporine A was released after 12 hours, the release characteristics was well fitted with Higuchi equation (r = 0.999). The Pharmacokinetics study at equal administration dosage (5 mg x kg(-1)) in rats showed the half-life (t1/2) of CyA-PM extended and the area under concentration-time curve (AUC) increased compared to sandimmune. The results also showed that cyclosporine A concentration-time data were all in accord with two compartment model. Cyclosporine A loaded mPEG-PLGA micelles showed obviously solubility enhancement, sustained release and overcome the side effect and toxicity of sandimmune resulted from solubiling agent-polyoxyethylene castor oil (Cremophor EL) and might be developed as a novel dosage form of cyclosporine A.

[Preparation of sustained release multivesicular liposome for thymopentin and preliminary study on its pharmacokinetics in rats].

To optimize the formulation and preparation method of multivesicular liposome of thymopentin and to investigate its pharmacokinetics in rats, the multivesicular liposome of thymopentin was prepared by double emulsification method and the formulation was optimized by orthogonal design. The release characteristics of thymopentin from multivesicular liposome in PBS (pH 7.4) and in plasma were investigated. The multivesicular liposome of thymopentin labeled with fluorescein isothiocyanate was prepared by double emulsification method. Its pharmacokinetics was evaluated following intramuscular injection in rats. The optimal formulation of multivesicular liposome of thymopentin were formulated with 7.5% glucose in aqueous phase and 2.25 mol x L(-1) triolein, 2.68 mol x L(-1) DPPG and 16.96 mol x L(-1) DOPC in organic phase. The entrapment efficiency of the multivesicular liposome of thymopentin was above 85% and the mean particle size was about 22 microm. The in vitro release of thymopentin from multivesicular liposome in PBS (pH 7.4) and in plasma was found to be in a sustained manner. The release curves were fitted to Higuchi equation. The pharmacokinetics following intramuscular injection of the multivesicular liposome of thymopentin labeled with fluorescein isothiocyanate in rats showed that the peak concentration of thymopentin was lower and elimination of it was slower significantly than that of thymopentin labeled with fluorescein isothiocyanate solution in the same dose. The plasma concentration of thymopentin maintained above quantitative limitation at 120 h after administration of multivesicular liposome of thymopentin. The optimized formulation and preparation technology of multivesicular liposome of thymopentin with higher entrapment efficiency are feasible with good reproducibility. Multivesicular liposome of thymopentin showed significant sustained-release property following intramuscular injection in rats.

Sec3 promotes the initial binary t-SNARE complex assembly and membrane fusion.

The soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (SNAREs) constitute the core machinery for membrane fusion during eukaryotic cell vesicular trafficking. However, how the assembly of the SNARE complex is initiated is unknown. Here we report that Sec3, a component of the exocyst complex that mediates vesicle tethering during exocytosis, directly interacts with the t-SNARE protein Sso2. This interaction promotes the formation of an Sso2-Sec9 'binary' t-SNARE complex, the early rate-limiting step in SNARE complex assembly, and stimulates membrane fusion. The crystal structure of the Sec3-Sso2 complex suggests that Sec3 binding induces conformational changes of Sso2 that are crucial for the relief of its auto-inhibition. Interestingly, specific disruption of the Sec3-Sso2 interaction in cells blocks exocytosis without affecting the function of Sec3 in vesicle tethering. Our study reveals an activation mechanism for SNARE complex assembly, and uncovers a role of the exocyst in promoting membrane fusion in addition to vesicle tethering.

[Risk factors for the collapse of cemented vertebral bodies after the minimally invasive vertebral augmentation procedures].

OBJECTIVE: To evaluate the incidence rate, the independent factors, and the prevention measures of the collapse of cemented vertebral bodies after minimally invasive vertebral augmentation procedures including percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty(PKP). METHODS: From January 2012 to June 2013, 154 patients with single segmental osteoporotic vertebral compression fractures(OVCF)were treated with PVP or PKP. There were 65 males and 89 females, ranging in age from 57 to 90 years old, with a mean of (76.20±9.35) years old. All the patients were followed up, and the duration ranged from 6 to 30 months, with a mean of (15.43±6.81) months. All the patients were arranged to perform X-ray examination, and some of the patients were arranged to do MRI examination during the follow up period. Possible risk factors were studied including gender, age, surgical approach(PVP or PKP), lumbar spine bone mineral density, treated vertebral level, the presence of osteonecrosis in the vertebral body, filling pattern of the cement, and the restoration of anterior vertebral height. The Chi-square test and the multivariate Logistic regression model were used to analyze the risk factors. RESULTS: The collapse of cemented vertebral bodies were found in 29 patients, and the total incidence rate of following time was 18.83%. A Multivariable Logistic Regression analysis revealed that the independent risk factors affecting the incidence rate of the collapse included surgical approach (OR=0.171, P=0.010), lumbar spine bone mineral density(OR=0.242, P=0.024), the presence of osteonecrosis in the vertebral body(OR=12.225, P=0.003), filling pattern of the cement(OR=10.461, P=0.000), and anterior vertebral height restoration(OR=0.316, P=0.019). CONCLUSIONS: The incidence rate of the collapse was high and was associated with many risk factors. Surgical approach, lumbar spine bone mineral density, the presence of osteonecrosis in the vertebral body, filling pattern of the cement, and anterior vertebral height restoration were the independent risk factors affecting the incidence rate of the collapse. Careful selection of patients before operation, symmetric cement distribution and fluid aspiration during operation, positive treatment of osteoporosis after operation would be the potential ways to avoid collapse of cemented vertebral bodies.

Comparison between ultrasonic irrigation and syringe irrigation in clinical and laboratory studies.

Ultrasonic irrigation and syringe irrigation were compared for their efficacy at cleaning root canal in vivo and in vitro. The in vivo study used 60 anterior teeth or premolars from 60 patients with periapical periodontitis who were randomly assigned to a syringe irrigation group (group S) or an ultrasonic irrigation group (group U). After instrumentation with a K-file using the step-back technique, the two groups received ultrasonic or syringe irrigation using 40 mL of 2.5% NaOCl respectively, followed by conventional lateral compaction. The in vitro study used 60 extracted single-canal premolars, which were also divided into U and S groups, and underwent the same irrigation and compaction. Forty of them were evaluated histologically by light microscopy, and the remaining 20 by scanning electron microscopy. No difference in main root canal filling was observed between the U and S groups. Notably, group U had a larger number of obturated lateral canals than group S. Moreover, a smaller amount of organic debris and more open dentinal tubules were observed in the root canal in group U than in group S. Our findings suggest that ultrasonic irrigation has a greater capacity to clean instrumented root canals than syringe irrigation. (J Oral Sci 58, 373-378, 2016).

[Vertebral internal reinforcement operation for the treatment of osteoporotic vertebral compressive fractures combined with bone cement leakage].

OBJECTIVE: To explore incidence rate, influencing factors, leakage routes,and preventative measures of bone cement leakages in vertebral internal reinforcement operation including percutaneous vertebroplasty and percutaneous kyphoplasty. METHODS: From January 2010 to January 2012,94 patients with osteoporotic vertebral compressive fracture,vertebral metastases and vertebral hemangioma were treated by vertebral internal reinforcement operation. Among them, there were 39 males and 55 females aged 55 to 86 with an average of 69.4 years old. The reasons, types, incidence and complications of bone cement leakage were analyzed. RESULTS: Totally 21 patients (26 vertebral) occurred bone cement leakage, the main routes included basivertebral veins, and bone cortex, which mainly located on adjacent intervertebrae and around vertebral body, and most of them were asymptomatic leakage. For the treatment of OVCFs, incidence of bone cement leakage in PKP was lower than that of PVP (P < 0.05), while incidince of PVP in treating vertebral metastases was worse than in treating OVCFs (P < 0.05). CONCLUSION: Bone cement leakage is a common complication in PVP and PKP. Careful analysis before operation, cautiously monitors and grasp operation indication in operation can decrease incidence of it.

[Clinical anatomy of iliac bone grafts used for mandibular reconstruction and dental implantation].

OBJECTIVE: To investigate the anatomical features of iliac bone grafts used for mandibular reconstruction and dental implantation. METHODS: Sixteen cadavers were dissected. The length, width, height and cortical thickness of the iliac bone were measured with respect to points determined by the relative dimensions of the bone. RESULTS: The length of iliac bone graft was (77.2 ± 6.1) mm. The height was from (38.2 ± 4.2) mm to (41.9 ± 4.7) mm. The width decreased from iliac crest to base line. The least width 10 mm and 15 mm away from iliac crest were (8.4 ± 2.2) mm and (6.5 ± 2.1) mm respectively. The greatest mean cross-sectional cortical thickness at the intermediate line of the iliac crest was (3.4 ± 0.8) mm. CONCLUSIONS: Anatomical features of iliac bone are suitable for designing bone grafts for mandibular reconstruction followed by dental implantation.

Effect of Wnt6 on human dental papilla cells in vitro.

INTRODUCTION: The Wnt signaling pathway plays an important role in tissue development by acting on proliferation, differentiation, and cell fate decisions. Because the role of Wnt6 in tooth development was still unknown, the purpose of this study was to investigate the role of Wnt6 in tooth morphogenesis and dental tissue mineralization by elucidating its effect on human dental papilla cells (hDPCs) in vitro. METHODS: Human dental papilla cells were enzymatically separated from tooth germs. Recombinant adenovirus encoding full-length Wnt6 cDNA was constructed to overexpress Wnt6, and the biologic effects of Wnt6 on hDPCs were investigated. Wnt6-transduced changes in hDPC proliferation were examined by means of a 5-bromodeoxyuridine (BrdU) incorporation assay and cell cycle analysis. Wnt6-transduced changes in hDPC differentiation were investigated by evaluating alkaline phosphatase (ALPase) activity, by a mineralization assay, and analysis of mineralization-related gene expression including ALP, type I collagen (Col I), osteonectin (ON), osteopontin (OPN), bone sialoprotein (BSP), and dentin matrix protein-1 (DMP-1). RESULTS: Wnt6 overexpression had no significant effect on the proliferation of hDPCs by BrdU incorporation assay and flow cytometric analysis. Wnt6 enhanced differentiation of hDPCs into functional odontoblast-like cells with up-regulated activity of ALPase and the expression of mineralization-related genes such as ALP, Col I, ON, OPN, BSP, and DMP-1. Wnt6 overexpression also promoted the mineralization of hDPCs. CONCLUSIONS: Our findings verified that Wnt6 plays an important role in tooth development by promoting hDPC differentiation, without significant effects on hDPC proliferation.

Cytotoxicity of RealSeal on human osteoblast-like MG63 cells.

INTRODUCTION: The purpose of this study was to compare the cytotoxicity of a new root canal filling material (RealSeal system) with epoxy resin-based root canal sealer (AH Plus) and gutta-percha by using human osteoblast-like MG63 cells. METHODS: Samples of each test material were fabricated in sterile cylindrical Teflon tubes of 4.4 mm diameter and 2 mm height. Extraction of specimens was carried out after setting in cell culture medium by using the ratio of 1.25 cm(2)/mL according to ISO 10993-5. Cytotoxicity was assessed by direct incubation of different extracts with MG63 cells at different time intervals. The dimethylthiazol diphenyltetrazolium bromide assay and flow cytometry were used to test the proliferation of MG63 cells. The results were analyzed with a Tukey test (alpha = 0.05). RESULTS: The gutta-percha was nontoxic to MG63 cells in vitro, whereas RealSeal core material showed initial cytotoxic effect on MG63 cells after 1 day of culture, which disappeared after 3 days of culture. The RealSeal sealer was significantly more cytotoxic than AH Plus (P < .05) within 3 days. Flow cytometry showed that cell proliferation in RealSeal sealer and AH Plus group was inhibited. CONCLUSIONS: The RealSeal sealer was significantly more toxic to MG63 cells than the AH Plus within 3 days, whereas RealSeal core material was similar with gutta-percha. Further research is required to evaluate the biocompatibility of RealSeal system comprehensively.

[Effects of different sterilization methods on mechanical properties of dental fissure bureffects of different sterilization methods on mechanical properties of dental fissure bur].

OBJECTIVE: The purpose was to analyze the effects of three sterilization methods (dry heat sterilization, steam sterilization, and chemical sterilization) on the corrosion of dental fissure bur. METHODS: 200 dental fissure burs were distributed to 10 groups. Bending strength, elastic modulus, and torsional strength were measured by bending and torsional instrument and calculated with special designed software. Among the three sterilization methods, the steam sterilization group showed the most evident. RESULTS: The corrosion was most severe in steam sterilization group, followed by chemical sterilization, dry heat sterilization. With the sterilization time increased, bending strength, elastic modulus, and torsional strength decreased respectively. Of the three sterilization methods, the mechanical properties were decreased most evidently by steam sterilization, followed by chemical sterilization and dry heat sterilization. CONCLUSION: It is proved that the bending strength, elastic modulus and torsional strength have a tight relationship with the corrosion of dental fissure burs. The corrosion was most severe in steam sterilization group, followed by chemical sterilization, dry heat sterilization. In regards of the corrosive effect, the dry heat sterilization might be the best way to sterilize the dental fissure burs.