Effects of Er:YAG laser pre-treatment on dentin structure and bonding strength of primary teeth: an in vitro study.

BACKGROUND: To investigate the effects of Er:YAG laser pre-treatment on the dentin structure and shear bond strength of primary teeth. METHODS: Dentin specimens were prepared using freshly extracted intact primary molars and divided randomly into four groups based on the surface treatment applied. The control and etchant groups received no treatment and conventional acid etching treatment, respectively, while the energy and frequency groups received laser surface treatment with variable energy (50-300 mJ) and frequency (5-30 Hz) parameters. The morphology was observed using scanning electron microscopy. The surface-treated dentin slices were bonded to resin tablets, followed by thermocycle treatment. The shear strength was determined using a universal testing machine and de-bonded surfaces were observed using a stereomicroscope. RESULTS: SEM observation showed that the surface morphology of the dentin slices changed after etching as well as after Er:YAG laser pre-treatment with different energy and frequency values. The dentin tubules opened within a specific energy (50-200 mJ) and frequency (5-20 Hz) range. Beyond this range, the intertubular dentin showed cracks and structural disintegration. Shear strength tests showed no significant changes after acid etching. The shear strength increased significantly (P < 0.05) after Er:YAG laser pre-treatment compared with that of the control group. The shear strength increased within the same energy (50-200 mJ) and frequency (5-20 Hz) range as the tubule opening, but not significantly (P > 0.05). The most common mode of interface failure was adhesive (interface) failure, followed by mixed and resin cohesive failure. CONCLUSIONS: Pre-treatment using Er:YAG laser opens the dentinal tubules without the formation of a smear layer and improves the bonding strength between the primary teeth dentin and the resin composites.

Preparation and evaluation of curcumin-loaded self-assembled micelles.

OBJECTIVE: Curcumin being used to treat various chronic diseases while its poor bioavailability issue limited its wide clinical application as a therapeutic agent. The aim of this work was to prepare curcumin-loaded self-assembled micelles using soluplus and solutol®HS15 (SSCMs) to enhance curcumin's solubility and thus oral bioavailability. METHODS: Optimum formulation was investigated and the optimized ratio of drugs and excipients was obtained and the SSCMs were prepared via ethanol solvent evaporation method. The optimal SSCMs were characterized by transmission electron microscopy, drug content analysis including loading efficiency (LE%) and entrapment efficiency (EE%), and the cumulative amount of curcumin released from the micelles were all calculated using HPLC method. The in vitro cytotoxicity and the permeability of SSCMs were measured by Caco-2 cell monolayers and the oral bioavailability was evaluated by SD rats. KEY FINDINGS: The solubility of curcumin in self-assembled micelles was dramatically increased by 4200 times as compared to free curcumin. Caco-2 cells transport experiment exhibited that while soluplus and solutol®HS15 were self-assembled into micelles, it could not only promote the permeability of curcumin across membrane for better absorption, but also could restrain the curcumin pumped outside due to the role of P-gp efflux mechanism of soluplus and solutol®HS15. Furthermore, the prepared SSCMs formulation was almost nontoxic and had safety performance on Caco-2 cells model. Moreover, curcumin's oral bioavailability of SSCMs formulation in SD rats had doubled than that of free curcumin. CONCLUSIONS: The prepared SSCMs were characterized by PS, PDI, LE%, EE% data analysis. After the soluplus and solutol®HS15 were self assembled into micelles, both the solubility and membrane permeability of curcumin were evaluated to have been enhanced, as well as the effect of efflux pump of curcumin was inhibited, hence to promote oral absorption and generate an increased bioavailability.

Stable Co(II)-based coordination polymer as fluorescence sensor for the discriminative sensing of biomarker methylmalonic acid.

Three novel Co-based coordination polymers including {[Co(L)(µ3-O)1/3]2}n (1), {[Co(L)(bimb)]}n (2) and {[Co(L)(bimmb)1/2]}n (3) (H2L = 2,6-di(4-carboxylphenyl)-4-(4-(triazol-1-ylphenyl))pyridine), bimb = 1,4-bis(lmidazol) butane, bimmb = 1,4-bis(imidazole-1-ylmethyl)benzene) were successfully prepared under solvothermal conditions and characterized. Single-crystal X-ray diffraction analyses revealed that 1 possesses a 3D architecture composed of a trinuclear cluster [Co3N3(CO2)6(µ3-O)], 2 exhibits a 2D new topological framework with the point symbol (84·122)(8)2, whereas 3 shows a unique six-fold interpenetrated 3D framework with a (63·82·10)2(63)2(8) topology. Impressively, all of them can function as a highly selective and sensitive fluorescent sensor for the biomarker methylmalonic acid (MMA) via fluorescence quenching. The low detection limit, reusability and high anti-interference performance together make 1-3 become promising sensors for the practical detection of MMA. Furthermore, the successful application of MMA detection in urine sample was demonstrated, which may be a potential candidate for the further development of clinical diagnostic tools.

[Application of objective structured clinical examination system in pediatric dental education for 8-year-program and 5-year-program students].

PURPOSE: To explore a more comprehensive and objective method for dental students examination, and improve the quality of pediatric dental education. METHODS: Fifteen 8-year-program students and 30 5-year-program dental students from School of Stomatology, the Fourth Military Medical University were enrolled in this study. Objective structured clinical examination (OSCE), traditional diadactic test and questionnaires were carried out in all students. The scores of the two testing methods between students in 2 groups were compared using SPSS 11.5 software package. RESULTS: The average score of OSCE for 8-year-program students was significantly higher than that of 5-year-program students. In contrast, the traditional test score of 8-year-program students was significantly lower than that of 5-year-program students. Most students accepted OSCE and approved the evaluation system combining OSCE with traditional test. CONCLUSIONS: As a comprehensive, objective and effective evaluation system, OSCE is helpful for students to master knowledge and improve clinical ability.

Self-assembling HA/PEI/dsRNA-p21 ternary complexes for CD44 mediated small active RNA delivery to colorectal cancer.

Our previous work proved that sequence specific double strand RNA (dsRNA-p21) effectively activated p21 gene expression of colorectal cancer (CRC) cells and consequently suppressed CRC growth. However, efficient delivery system is a significant challenge to achieve sufficient therapy. In this study, a self-assembled HA/PEI/dsRNA-p21 ternary complex (TC-dsRNA-p21) was developed for the tumor-target delivery of dsRNA-p21 into CRC cells. Hyaluronic acid (HA) was introduced to shield the PEI/dsRNA-p21 binary complexes (BC-dsRNA-p21) for reducing the cytotoxicity of PEI and for increasing the tumor-targeted intracellular uptake by cancer cells through HA-CD44 mediated endocytosis. Comparing to the BC-dsRNA-p21, the TC-dsRNA-p21 showed increase in size, decrease in zeta potential, low cytotoxicity as well as high stability in physiological conditions due to the anionic shielding. Confocal microscopy analysis and flow cytometry confirmed that TC-dsRNA-p21 had high transfection efficiency in the CD44-abundant Lovo cells, as compared with binary complex. In vitro physiological experiment showed that, comparing to the control group, the TC-dsRNA-p21 effectively activated the expression of p21 mRNA and P21 protein, causing blockage of cell cycle at G0/G1 phase and suppression of cancer cell proliferation as well as colony formation. Furthermore, in vivo distribution experiment demonstrated that the TC-dsRNA-p21 could effectively accumulate at rectal wall for up to 10 h, following in situ application. These findings indicated that TC-dsRNA-p21 might hold great potential for delivering dsRNA-p21 to treat CRC.

Development of in situ gelling and bio adhesive 5-Fluorouracil enema.

In this study, a novel 5-Fluorouracil (5-FU) enema with good bio adhesion and temperature sensitivity was developed using in situ gelling technology. The preparation was formulated as a free-flowing liquid before use, while a layer of gel film was quickly formed when administered in the rectum, with a large contact surface area. It also demonstrated good biocompatibility, appropriate gel strength and bio adhesive force with excellent adhesion to rectal mucosa and prolonged action time, allowing more effective drug absorption and diffusion to surrounding tissues. Poloxamer 407 and poloxamer 188 were applied to adjust the gelling temperature. With the addition of carbopol and polycarbophil (bio adhesive substances), the solubility of 5-FU and gel strength increased, the temperature of gelation and the surface area of drug contact on mucous epithelium decreased. Decreased adhesive force between the preparation and the mucous membrane of the rectum was demonstrated with improving carbopol and polycarbophil's concentration. In vitro release demonstrated that 5-FU in situ gelling enema with different bases had a rapid and almost complete drug release. We used an optimized formulation of P407/P188/polycarbophil/5-FU (17/2.5/0.2/1.0) for animal experiments. The result showed that the drug evenly covered the surface of the rectum and there was no leakage in 6 hours. The in situ gelling enema showed significantly higher rectal tissue levels of 5-FU compared with suppository and intravenous administration, indicating that 5-FU could be well absorbed due to the enlarged releasing area, longer retention time and larger amount of dissolved active ingredients. Systemically, 5-FU levels in the enema group were similar to those in the suppository group and significantly lower than the intravenous group. The enema was not associated with morphological damage to rectal tissue. These results suggest that the bio adhesive and in situ gelling enema could be a more effective rectal delivery system of 5-FU.

Preparation and quality assessment of itraconazole transfersomes.

Drug-loading transfersomes were prepared with itraconazole, a lipophilic drug, as a model drug to investigate the key factor affecting transfersomes quality and to evaluate their qualities. Drug-loading transfersomes were prepared using film dispersion method. The quality of transfersomes was evaluated by HPLC, transmission electron microscope, particle size analyzer and in vitro release. Itraconazole transfersomes was transparent solution in ivory white color with a mean entrapment efficiency of about 80%. The shape of hollow vesicles was spheroidal with the diameter of approximately 100 nm, and the zeta potential of 45 mV, which had a good transdermal effect. It can be concluded via single-factor investigation that the quality of transfersomes is significantly affected by solvent, salt ion concentration and homogenization pressure and so on. The preparation method obtained through screening and optimizing formulation and technology is feasible and the quality can be controlled.

[Surgical management of traumatic injury of upper cervical spine].

OBJECTIVE: To analyze retrospectively the clinical outcome of surgical management for upper cervical spine injury caused by trauma. METHODS: From January 2005 to March 2007, 16 patients with injury of upper cervical spine were treated by different management. There were 11 males and 5 females with an average age of 44 years ranging from 24 to 75. Of all, 5 cases were the odontoid fracture, 3 were atlas fracture, 5 were Hangman's fracture, 3 were atlanto-axial dislocation. MR imaging of cervical spine showed cervical cord compression and changes of T2 high signal in 5 cases. According to the injury mechanism, the imageological appearance, fracture classification, the methods of treatment were selected. RESULTS: Seven patients received non-operative treatment and nine patients underwent operation. Sixteen patients were followed up for 7 to 34 months (means 10.5 months). All fractures were healing or bone graft fusion and no internal fixation was lossing. There were no injuries of vertebral artery, nerve root or spinal cord. CONCLUSION: CT and MRI are required in the course of diagnosis for the traumatic injury of upper cervical spine. The optimal modus operandi should be choose to retain upper cervical spine, meanwhile, can reserve the cervical movement.