Molecular engineering of PETase for efficient PET biodegradation.

The widespread utilization of polyethylene terephthalate (PET) has caused a variety of environmental and health problems. Compared with traditional thermomechanical or chemical PET cycling, the biodegradation of PET may offer a more feasible solution. Though the PETase from Ideonalla sakaiensis (IsPETase) displays interesting PET degrading performance under mild conditions; the relatively low thermal stability of IsPETase limits its practical application. In this study, enzyme-catalysed PET degradation was investigated with the promising IsPETase mutant HotPETase (HP). On this basis, a carbohydrate-binding module from Bacillus anthracis (BaCBM) was fused to the C-terminus of HP to construct the PETase mutant (HLCB) for increased PET degradation. Furthermore, to effectively improve PET accessibility and PET-degrading activity, the truncated outer membrane hybrid protein (FadL) was used to expose PETase and BaCBM on the surface of E. coli (BL21with) to develop regenerable whole-cell biocatalysts (D-HLCB). Results showed that, among the tested small-molecular weight ester compounds (p-nitrophenyl phosphate (pNPP), p-Nitrophenyl acetate (pNPA), 4-Nitrophenyl butyrate (pNPB)), PETase displayed the highest hydrolysing activity against pNPP. HP displayed the highest catalytic activity (1.94 µM(p-NP)/min) at 50 °C and increased longevity at 40 °C. The fused BaCBM could clearly improve the catalytic performance of PETase by increasing the optimal reaction temperature and improving the thermostability. When HLCB was used for PET degradation, the yield of monomeric products (255.7 µM) was ∼25.5 % greater than that obtained after 50 h of HP-catalysed PET degradation. Moreover, the highest yield of monomeric products from the D-HLCB-mediated system reached 1.03 mM. The whole-cell catalyst D-HLCB displayed good reusability and stability and could maintain more than 54.6 % of its initial activity for nine cycles. Finally, molecular docking simulations were utilized to investigate the binding mechanism and the reaction mechanism of HLCB, which may provide theoretical evidence to further increase the PET-degrading activities of PETases through rational design. The proposed strategy and developed variants show potential for achieving complete biodegradation of PET under mild conditions.

Responses of microRNA in digestive glands of mussel Mytilus galloprovincialis exposed to polystyrene nanoplastics.

Polystyrene nanoplastics (PS-NPs) are typical accumulated nanoplastics in the marine environment and organisms, and have strong potential risks to marine ecological environment and human health. MiRNAs could respond to and participate in the response process of environmental stressors. However, the response of miRNAs to nanoplastics has not been fully explored. In this study, miRNA responses of digestive glands in mussels Mytilus galloprovincialis treated by 200 nm PS-NPs (20, 200, 2000 µg/L) for 7 days were characterized by BGISEQ-500 deep sequencing and bioinformatics analysis, along with histopathological quantification with planimetric parameters on hematoxylin and eosin (H&E) staining. Results showed that one novel miRNA (novel_mir63) and seven known miRNAs (miR-34_2, miR-34_5, miR-281_8, let-7-5p_6, miR-10, miR-124, miR-29b-3p) were significantly (adjusted P-value < 0.05) differentially expressed after PS-NPs treatments, and most of them were down-regulated expect for novel_mir63 and miR-34_2. Function analysis of target genes corresponding to these differentially expressed miRNAs indicated that PS-NPs disturbed the process related to metabolism, aging, cardiac function, neural excitation, and repairment. Among them, acetyl-CoA C-acetyltransferase and purine metabolism pathway played vital connection roles. Meanwhile, significantly morphology changes of digestive tubes obtained from H&E stained sections also implied severely disrupted metabolic capability in digestive glands, reflected by significantly increased mean diverticular radius (MDR) and mean luminal radius (MLR) values and the ratio of MLR to mean epithelial thickness (MET), and significantly decreased MET value and MET/MDR. Overall, these findings have revealed new characterization of miRNAs and their target genes in mussel M. galloprovincialis under PS-NPs stress, and provide important clues to further elucidate the toxicity mechanisms of PS-NPs.

3-dimensional analysis of hard- and soft-tissue symmetry in a Chinese population.

BACKGROUND: Facial symmetry severely affects appearance and function. Large numbers of patients seek orthodontic treatment to improve facial symmetry. However, the correlation between hard- and soft-tissue symmetry is still unclear. Our aim was to investigate the hard- and soft-tissue symmetry in subjects with different levels of menton deviation and sagittal skeletal classes with 3D digital analysis and to investigate the relationship between the entire and individual hard- and soft-tissues. METHODS: A total of 270 adults (135 males and 135 females) consisting of 45 subjects of each sex in each sagittal skeletal classification group. All subjects were further classified into relative symmetry (RS), moderate asymmetry (MA) and severe asymmetry (SA) groups based on the degree of menton deviation from the mid-sagittal plane (MSP). The 3D images were segmented into anatomical structures and mirrored across the MSP after establishing a coordinate system. Original and mirrored images were registered by a best-fit algorithm, and the corresponding root mean square (RMS) values and colormap were obtained. The Mann‒Whitney U test and Spearman correlation were conducted for statistical analysis. RESULTS: The RMS increased with greater deviations with regard to the deviation of the menton in most of anatomical structures. Asymmetry was represented in the same way regardless of sagittal skeletal pattern. The soft-tissue asymmetry had a significant correlation with dentition in the RS group (0.409), while in the SA group, it was related to the ramus (0.526) and corpus (0.417) in males and was related to the ramus in the MA (0.332) and SA (0.359) groups in females. CONCLUSIONS: The mirroring method combining CBCT and 3dMD provides a new approach for symmetry analysis. Asymmetry might not be influenced by sagittal skeletal patterns. Soft-tissue asymmetry might be reduced by improving the dentition in individuals with RS group, while among those with MA or SA, whose menton deviation was larger than 2 mm, orthognathic treatment should be considered.

Preparation and in vitro and in vivo evaluation of quercetin-loaded mixed micelles for oral delivery.

Quercetin (QT) is a plant polyphenol with various pharmacological properties. However, the low water solubility limits its therapeutic efficacy. In the present study, QT-loaded sodium taurocholate-Pluronic P123 (QT-loaded ST/P123) mixed micelles were developed and characterized, and the effect of the formulation on improving the water solubility of QT was investigated. QT-loaded ST/P123 mixed micelles were prepared by thin film hydration-direct dissolution and optimized by uniform design. The optimal formulation possessed high drug loading (12.6%) and entrapment efficiency (95.9%) in small (16.20 nm) spherically-shaped micelles. A low critical micelle concentration indicated that the micelles were stable, and they showed a sustained release pattern, as determined in vitro in simulated gastric fluid and intestinal fluid. Pharmacokinetic evaluation showed the Cmax and AUC0-24 were 1.8-fold and 1.6-fold higher than the QT suspension. The present results indicate that QT-loaded ST/P123 micelles are potential candidates to improve the solubility and oral bioavailability of QT.

Planar conjugated polymers containing 9,10-disubstituted phenanthrene units for efficient polymer solar cells.

Four novel conjugated polymers (P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below -5.3 eV), and high hole mobilities (in the range of 3.6 × 10(-3) to 0.02 cm(2) V(-1) s(-1) ). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71 BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs.

Wear analysis of 39 conserve plus metal-on-metal hip resurfacing retrievals.

There have been increasing concerns regarding adverse local tissue reactions (ALTR) following metal-on-metal (MOM) hip arthroplasties. This study examined wear rates in retrievals of one design of MOM resurfacing arthroplasty, and assessed the differences in wear between those with and without ALTR. Wear measurements were made on 39 MOM resurfacing components (30 femoral, 9 acetabular) which were at least 2years in vivo. Seven hips (6 patients; 4 acetabular components, 7 femoral components) were identified to have ALTR. Acetabular component abduction and anteversion angles were determined using EBRA, and the contact-patch-to-rim (CPR) distance was calculated. The ALTR group had higher linear femoral and acetabular wear rates, acetabular anteversion and abduction angles, lower CPR, and longer time to revision. Given the increased risk for ALTR associated with acetabular component malpositioning, patients with malpositioned acetabular components may require closer clinical follow-up and monitoring.

Dynamic response and optimal design of curved metallic sandwich panels under blast loading.

It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a "soft" outer face and a "hard" inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

Anthracene-containing wide-band-gap conjugated polymers for high-open-circuit-voltage polymer solar cells.

The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene-containing wide-band-gap donor and acceptor (D-A) alternating conjugated polymers (P1 and P2) are described. These two polymers absorb in the range of 300-600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1:PC71 BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm(-2) , and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm(-2) ). In addition, P2:PC71 BM blend-based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm(-2) , and an FF of 0.53.

Wear versus thickness and other features of 5-Mrad crosslinked UHMWPE acetabular liners.

BACKGROUND: The low wear rates of crosslinked polyethylenes provide the potential to use larger diameters to resist dislocation. However, this requires the use of thinner liners in the acetabular component, with concern that higher contact stresses will increase wear, offsetting the benefits of the crosslinking. QUESTIONS/PURPOSES: We asked the following questions: Is the wear of conventional and crosslinked polyethylene liners affected by ball diameter, rigidity of backing, and liner thickness? Are the stresses in the liner affected by thickness? METHODS: Wear rates were measured in a hip simulator and stresses were calculated using finite element modeling. RESULTS: Without crosslinking, the wear rate was 4% to 10% greater with a 36-mm diameter than a 28-mm diameter. With crosslinking, wear was 9% lower with a 36-mm diameter without metal backing and 4% greater with metal backing. Reducing the thickness from 6 mm to 3 mm increased the contact stress by 46%, but the wear rate decreased by 19%. CONCLUSIONS: The reduction in wear with 5 Mrad of crosslinking was not offset by increasing the diameter from 28 mm to 36 mm or by using a liner as thin as 3 mm. CLINICAL RELEVANCE: The results indicate, for a properly positioned 5-Mrad crosslinked acetabular component and within the range of dimensions evaluated, neither wear nor stresses in the polyethylene are limiting factors in the use of larger-diameter, thinner cups to resist dislocation.

Application of problem-based learning in a large class in stomatology course.

PURPOSE: To determine the feasibility of implementing problem-based learning (PBL) in a large class and whether previous PBL experience is necessary. MATERIALS AND METHODS: A total of 236 students from 2 large classes at China Medical University were enrolled. One class (118 students) had had a previous small-group PBL experience and another class (113 students) had not. Each class was subdivided into 15 groups (7 to 8 students/group) and took 2 separate 100-minute PBL sessions per week with the same teaching faculty. Each PBL class had 2 facilitators, 1 content expert facilitator, and 1 nonexpert facilitator. The results of the theoretical examination and case analysis examinations were analyzed using the t test. Questionnaires were used to evaluate both student and facilitator perceptions. RESULTS: The feedback from both students and facilitators was positive. According to the questionnaires, both experienced and non-experienced students acknowledged that the teaching method was enjoyable and functional. The test results showed students had achieved the learning objectives. The results of the theoretical and case analysis examinations showed no significant difference between the PBL experienced class and the non-experienced class. The mean study hours spent weekly by the students after class on the course were about 6.3 +/- 1.1 hours for the non-experienced students and 4.7 +/- 0.981 hours for the experienced students (t = 11.94, P < .001). The non-experienced students showed more preference for the content expert tutor. CONCLUSION: Implementing PBL in a large class is feasible without extracting great demand on limited educational resources. Previous PBL experience is helpful but not necessary.

Loss of Wnt4 expression inhibits the odontogenic potential of dental pulp stem cells through JNK signaling in pulpitis.

Dental pulp stem cell (DPSC)-based odontogenic regeneration in inflammatory conditions is important in the process of pulpitis. DPSCs have been reported to lose potential for odontogenic regeneration in inflammatory conditions. This study aims to determine the mechanism of impaired odontogenic differentiation of DPSCs in an inflammatory microenvironment. We regulated Wnt4 expression using recombinant lentiviral Wnt4 and Wnt4 siRNA. Alkaline phosphatase (ALP) and Alizarin red S (ARS) staining as well as Real-Time PCR were performed to evaluate the osteogenic differentiation potential of DPSCs with either upregulated or downregulated Wnt4. Furthermore, SP600125 was used to inhibit the potential downstream factor JNK1, and the osteogenic differentiation ability of DPSCs was evaluated. As shown, Wnt4 was downregulated in DPSCs under inflammatory conditions. Inhibition of Wnt4 expression in DPSCs negatively regulated odontogenic differentiation. Overexpression of Wnt4 in LPS-treated DPSCs promoted odontogenic differentiation. In addition, JNK1 was responsible for Wnt4-mediated odontogenic differentiation of DPSCs. Taken together, Wnt4 may function by affecting JNK signaling pathways in the process of impaired odontogenic regeneration by DPSCs under inflammatory conditions.

Blocking of TRPV-1 in the parodontium relieves orthodontic pain by inhibiting the expression of TRPV-1 in the trigeminal ganglion during experimental tooth movement in rats.

Orthodontic pain has confused the orthodontics for a long time, and recent research demonstrated that transient receptor potential vanilloid type 1 (TRPV1) had crucial functions in transduction of painful stimuli. The present research investigated the analgesia effects of the blocking TRPV1 on orthodontic pain during experimental tooth movement. Under challenge with experimental tooth movement, the expression of TRPV1 in the parodontium was increased in a time-dependent and force-dependent manner. And treatment with selective TRPV1 antagonist AMG-9810 in the parodontium reduced the expression of TRPV1 in the trigeminal ganglion (TG) and decreased the secretion of IL-1ß in the gingival crevicular fluid. Furthermore, AMG-9810 could relieve orthodontic pain arising from experimental tooth movement in rats. We suggest that TRPV1 both in the parodontium and trigeminal ganglion are involved in orthodontic pain, and TRPV1 in the parodontium influence on orthodontic pain through reducing the expression of TRPV1 in trigeminal ganglion. Our finding may help to develop strategies for relieving orthodontic pain after orthodontics.

[Expression of TRPV1 and CGRP in rat trigeminal ganglion during orthodontic tooth movement].

PURPOSE: Sprague-Dawley rat models of tooth movement were established to investigate the expression of transient receptor potential vanilloid 1 (TRPV1) and calcitonin gene related peptide (CGRP) in rat trigeminal ganglion during orthodontic tooth movement, and to explore the roles of TRPV1 and CGRP in orthodontic pain. METHODS: Sixty-six Sprague-Dawley rats were randomly divided into control group (n=6), sham operation group (n=6), and experimental group (n=54). Tooth movement models were established, orthodontic force (50 g) was applied on the maxillary first molar in the rats of experimental group, and then the trigeminal ganglia were collected at 4, 8 h, 1 d (3 subgroups were set up according to the force: 1 d-30 g, 1 d-50 g, 1 d-80 g), 3, 5, 7, 14 d after tooth movement. The changes of TRPV1 and CGRP expression were detected by immunofluorescence staining. SPSS16.0 software package was used for statistical analysis. RESULTS: According to immunofluorescence staining, the TRPV1-IR and CGRP-IR neurons were mostly small to medium sized. The percentages of TRPV1-IR and CGRP-IR neurons in trigeminal ganglion increased after applying force, and reached the peak at 1-3 d and then fell to the initial level gradually. In addition, the application of greater force during experimental tooth movement induced higher percentages of TRPV1-IR and CGRP-IR neurons in trigeminal ganglion. CONCLUSIONS: Experimental tooth movement leads to the regular changes of TRPV1-IR and CGRP-IR neurons in trigeminal ganglion, indicating that TRPV1 and CGRP may play important roles in orthodontic pain.

[Investigation of dental manpower in non-public dental institutions in Liaoning province].

PURPOSE: To investigate the non-public oral medical institutions in Liaoning province in 2011, and to analyze the status of dental manpower in non-public dental institutions in Liaoning province. METHODS: A mass survey on dental manpower was made in non-public dental institutions in Liaoning province in 2011 by means of questionnaire investigation, which included the institution type, dental devices, and the number, structure, composition, distribution of dental manpower in non-public dental institutions in Liaoning province. Data was entered with EpiData 3.0 and analyzed with SPSS 13.0 software package. RESULTS: There were 1649 non-public dental institutions with 3132 dentists, 1265 nurses, 540 technicians and 3490 dental chairs in Liaoning province. 85.69% of the dental manpower were young and middle-aged. 33.17% of the dentists had primary professional titles, 42.53% of them had college degree and 87.96% of the dentists was general dentistry. In the dental auxiliaries, the primary professional title accounted for the majority. 95.97% of the nurses majored in general dentistry and 60.40% of the nurses' educational background were below junior college degree. 72.59% of the technicians majored in prosthetic dentistry and 67.78% of their educational background were below junior college degree. The ratio of the dentists to nurses to technicians was 6:2:1. The ratio of the nurses to dental chairs was 1:2.76. CONCLUSIONS: The distribution and composition of dental manpower are not reasonable in non-public dental institutions in Liaoning province. We should strengthen effective utilization of oral health resources and the oral health service ability of non -public dental institutions in Liaoning province. Supported by Key Science and Technology Projects of Liaoning Province (2012225015).

Enhancing the performance of polymer photovoltaic cells by using an alcohol soluble fullerene derivative as the interfacial layer.

Alcohol soluble fullerene derivative (FN-C60) has been synthesized and used as a cathode interfacial layer for high-efficiency polymer solar cells (PSCs). To examine the function of the FN-C60 interfacial layer, polymer solar cells were fabricated with blends of P3:PC71BM, HXS-1:PC71BM, PDFCDTBT:PC71BM, and PDPQTBT:PC71BM as the active layer. In comparison to the bare Al electrode, power conversion efficiencies (PCEs) of P3:PC71BM, HXS-1:PC71BM, PDFCDTBT:PC71BM, and PDPQTBT:PC71BM based PSCs were increased from 3.50 to 4.64%, 4.69 to 5.25%, 2.70 to 4.60%, and 1.52 to 2.29%, respectively, when FN-C60/Al was used as the electrode. Moreover, the overall photovoltaic performances of PSCs with the FN-C60/Al electrode were better than those of cells with LiF/Al electrode, indicating that FN-C60 is a potential interfacial layer material to replace LiF.

[Investigation of the medical institutions of stomatology and dental manpower distribution in Liaoning province].

PURPOSE: The aim of this investigation was to determine and analyze the distribution of the medical institutions of stomatology and dental manpower in Liaoning province. METHODS: The data of institutions and manpower was collected by mass examination using tables filled by every institution and personally. Epidata 3.02 database was used to input the data and statistical analysis was performed using the SPSS12.0 software package. RESULTS: The results showed that there were 2155 dental institutions and 5617 dentists in Liaoning province. Among all the institutes, 71.0% was private clinics. About 80.5% of institutions and 87.8% of dentists were in the urban area, which was significantly higher than the percent of dentists working in the rural area. The ratio between dentists and the general population was about 13.02/10 million. There were fewer dental auxiliary in dental institutions, the ratio between dentists, nurses and dental technician was 6:2:1. The title and degree of the dentists in the rural area were lower than those in urban area, but the dentists in the rural area provided service for a large population. CONCLUSION: The results suggest that the distribution of oral health resource in Liaoning province should be rationally readjusted, and continuing education and training should be strengthened in order to improve the efficiency of oral health service and social health justice. Supported by Key Medical Professional Construction Project of Liaoning Province (Grant No.200809).

[Difference between dental caries and oral health behavior of family in primary dentition].

OBJECTIVE: To study the dental caries status in the primary dentition of 5-year-old children and analyze the difference of oral health behavior of family between urban and rural in Liaoning province. METHODS: The representative samples were selected by multi-stage, stratified and random sampling from Liaoning province. Dental caries of 792 children at five years were recorded according to World Health Organization criteria. The questionnaries were finished by 396 parents of the children and analyzed the oral health behavior of family in urban and rural by chi-squre test. RESULTS: The prevalence and dmft of dental caries of 5-year-old children in Liaoning province was 73.86% and 4.38, respectively. The prevalence of dental caries in 5-year-old children was 64.14% in urban and 83.59% in rural. There was significant difference on the consumption of sweets, chocolate, water with sugar and beverage between the children in urban and rural. More urban children had good toothbrushing behavior such as the time of beginning brush tooth, the frequency of brushing and daily use of fluoridated toothpaste compared with the rural children. The parents in urban had high level of education and incomes and there were more children in urban have regular dental visit pattern than in rural. CONCLUSION: This study has shown that there is an urgent need for the implementation of a systematic education on oral health behavior of family on rural children in Liaoning province.

[The prevalence and trends of caries in Liaoning province].

PURPOSE: The aim of this investigation was to analyse the dental caries prevalence, patterns and trends of all age groups in Liaoning province. METHODS: The representative samples were selected by multi-stage, stratified and random sampling, which included subjects aged 5,12,35-44 and 65-74 years. Clinical examination was based on WHO methodology(4th Ed). Student's t test and Chi-square test were applied for statistical evaluation of the mean caries experience(DMFT/dmft) and the prevalence proportion rates of dental caries (PP) between 1995 and 2005 using SPSS 12.0 software package. RESULTS: At age 5,12,35-44, the PP was 73.86%,30.05% and 63.89% respectively,which was lower than in 1995, the number being 89.49%, 59.19% and 70.26%. However, at 65-74 years, the PP was 67.40% in 2005, and there was no significant difference compared with 1995. For the two national survey, the PP and DMFT were higher in urban than in rural area. But the dmft in 5-year-old in urban was lower than in rural in 2005. CONCLUSIONS: The trend of dental caries in children and adults was declined in 2005, but it was still higher. It is essential to strengthen oral health education and promotion and continuously implement preventive oral care technique in Liaoning province.