Exogenous application of urea and a urease inhibitor improves drought stress tolerance in maize (Zea mays L.).

Drought is believed to cause many metabolic changes which affect plant growth and development. However, it might be mitigated by various inorganic substances, such as nitrogen. Thus, the study was carried out to investigate the effect of foliar-applied urea with or without urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on a maize cultivar under drought stress simulated by 15% (w/v) polyethylene glycol 6000. Foliar-applied urea resulted in a significant increase in plant dry weight, relative water content, and photosynthetic pigments under water stress condition. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD), and hydrogen peroxidase (CAT), were enhanced with all spraying treatments under drought stress, which led to decreases in accumulation of hydrogen peroxide (H2O2), superoxide anion ([Formula: see text]) and malondialdehyde (MDA). The contents of soluble protein and soluble sugar accumulated remarkably with urea-applied under drought stress condition. Moreover, a further enhancement in above metabolites was observed by spraying a mixture of urea and urease inhibitor as compared to urea sprayed only. Taken together, our findings show that foliar application of urea and a urease inhibitor could significantly enhance drought tolerance of maize through protecting photosynthetic apparatus, activating antioxidant defense system and improving osmoregulation.

Design, synthesis, and biological characterization of novel PEG-linked dimeric modulators for CXCR4.

CXCR4 dimerization has been widely demonstrated both biologically and structurally. This paper mainly focused on the development of structure-based dimeric ligands that target CXCL12-CXCR4 interaction and signaling. This study presents the design and synthesis of a series of [PEG]n linked dimeric ligands of CXCR4 based on the knowledge of the homodimeric crystal structure of CXCR4 and our well established platform of chemistry and bioassays for CXCR4. These new ligands include [PEG]n linked homodimeric or heterodimeric peptides consisting of either two DV3-derived moieties (where DV3 is an all-d-amino acid analog of N-terminal modules of 1-10 (V3) residues of vMIP-II) or hybrids of DV3 moieties and CXCL121-8. Among a total of 24 peptide ligands, four antagonists and three agonists showed good CXCR4 binding affinity, with IC50 values of <50nM and <800nM, respectively. Chemotaxis and calcium mobilization assays with SUP-T1 cells further identified two promising lead modulators of CXCR4: ligand 4, a [PEG3]2 linked homodimeric DV3, was an effective CXCR4 antagonist (IC50=22nM); and ligand 21, a [PEG3]2 linked heterodimeric DV3-CXCL121-8, was an effective CXCR4 agonist (IC50=407nM). These dimeric CXCR4 modulators represent new molecular probes and therapeutics that effectively modulate CXCL12-CXCR4 interaction and function.

[Evaluation of the effect of invisible correction and SGTB in the treatment of mandibular retrusion].

PURPOSE: To compare the clinical effects of invisible correction and SGTB in two-stage treatment of mandibular retrusion. METHODS: Eighty-five patients with bony mandibular regression who did not pass the peak of growth and development were selected. Among them, 40 cases were guided by invisible correction and 45 cases were guided by SGTB functional correction. Lateral head X-rays before and after treatment were measured, and the effect before and after treatment was compared by SPSS 16.0 software package. RESULTS: After treatment, the SNB angle and NP-FH (face angle) increased and the ANB angle decreased in both groups, all of which had significant changes(P＜0.001). At T1, the changes of SNB angle, ANB angle and NP-FH angle in the invisible group were smaller than those in the SGTB group(P＜0.05). The difference between MP-FH angle and MP-SN angle before and after treatment was greater in the SGTB group than in the invisible group(P＜0.001). CONCLUSIONS: In patients with receding mandible before the peak of growth and development, the mandible was significantly moved forward after orthodontics. Both invisible orthodontics and SGTB promote changes in the position of the mandible, improves coordination between the upper and lower jaws. In the control of the posterior teeth in the vertical direction, the invisible group is stronger than the SGTB group.

MiR-146a-5p Promotes Dental Stem Cells Osteo/odontogenic Differentiation through NF-Kappa B Signaling Pathway by Targeting TRAF6.

OBJECTIVE: To screen miRNAs that could simultaneously regulate osteo/odontogenic differentiation of multiple stem cells, including dental pulp stem cells (DPSCs), stem cells from the apical papilla (SCAPs) and periodontal ligament stem cells (PDLSCs). METHODS: Differentially expressed miRNAs analysis on three miRNA microarrays data of dental stem cells undergoing osteo/odontogenic differentiation (GSE138180, GSE154466 and GSE159508) was performed, and miR-146a-5p were identified by bioinformatic prediction, dual-luciferase reporter assay and quantitative real-time polymerase chain reaction (PCR). In addition, differentially expressed genes between miR-146a-5p overexpressed group and control group (GSE79341) were applied for KEGG pathways enrichment analysis. RESULTS: MiR-146a-5p expression increased in the osteo/odontogenic differentiation of DPSCs, SCAPs and PDLSCs. Tumour necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) was identified as the target gene of miR-146a-5p. Furthermore, miR-146a-5p could influence the NF-Kappa B signalling pathway. CONCLUSION: This study suggests that miR-146a-5p could promote differentiation in multiple dental stem cells through the NF-Kappa B signalling pathway by targeting TRAF6.

Cu2+-imprinted cross-linked chitosan resin as micro-column packing materials for online chemiluminescence determination of trace copper.

The Cu(2+)-imprinted cross-linked chitosan resin was synthesized and the binding characteristic of the resin to Cu(2+) was evaluated. The prepared resin was packed into a micro-glass column and used as micro-separating column. The micro-separating column was connected into the chemiluminescence flow system and placed in front of the window of the photomultiplier tube. Based on the luminol-hydrogen peroxide chemiluminescence system, a flow injection online chemiluminescence method for determination of trace copper was developed and trace Cu(2+) in complex samples was successfully determined. The proposed method improved the shortcomings of chemiluminescence method's poor selectivity.

[Changes of the upper airway in children with Class â ¡ mandibular retrusion and snoring during night before and after functional treatment by sagittal-guidance Twin-block appliance].

PURPOSE: To study the changes of dimension and morphology of upper airway in children with ClassⅡ mandibular retrusion after functional treatment by sagittal-guidance Twin-block appliance. METHODS: Cone-beam CT (CBCT) data of upper airway of the subjects were measured by Dolphin 11.5 software and Mimics 17.0 software , and the changes of dimension and morphology of upper airway before and after functional treatment with sagittal-guidance Twin-block(SGTB) appliance were compared. SPSS 16.0 software package was used for data processing. RESULTS: After functional treatment，the volume of total upper airway，nasopharynx airway, oropharynx airway, the sectional area of tip of the epiglotti(TE), the lateral diameter of TE, the base of the epiglottis(EB) significantly increased (P<0.05) in children with SGTB appliance. CONCLUSIONS: SGTB functional treatment is effective in the treatment of skeletal ClassⅡ mandibular retrusion of children by increase of the upper airway and improvement of respiration．.

Role-play in Endodontic Teaching: a Case Study.

Objective: To investigate the role of the application of role-play in endodontic study in improving the communication skills of Chinese dental undergraduates prior to their direct interactions with patients at the Fourth Military Medical University's School of Stomatology, China. Methods: Students were recruited from the 5-year bachelor's programme (n = 36) and randomly divided into six groups, and from the 8-year DDS programme (n = 10) and randomly divided into two groups to participate in the role-play training. Cases selected randomly from the case pool were distributed to the groups. The teacher gave an outline of the roles in the simulation. Each member of each group randomly selected their own role for the role-play. Four types of surveys were distributed to students and faculty members at different points after the role-plays had taken place, to evaluate their attitude towards the use of role-plays in endodontic study. Frequency analysis and a one sample t test were used to describe and analyse students' acceptance of role-play as a teaching technique. The level of statistical significance was set at P < 0.05. Results: Students' performance and satisfaction as well as the supporting faculty responses were very favourable towards role-playing. In total, 93.5% of students responded favourably to the role-play, answering 'strongly agree' or 'agree' to the positive statements about their role-play performance. A total of 95.1% of students stated that they had benefited psychologically and technically from the role-play ('strongly agree' or 'agree') after their 1-year rotating internship. Conclusion: The application of role-play in endodontic study is an effective way of educating Chinese dental undergraduates and can be beneficial for their transition from students to dentists.

[Analysis of the biocompatibility of a new PLGA/fish skin collagen conjugated electrostatic spinning film].

PURPOSE: To study the biocompatibility of a new polylactic acid-glycolic acid(PLGA)/fish skin collagen conjugated electrostatic spinning film. METHODS: PLGA and medical-grade fish skin-I collagen were used as raw materials to prepare nanometer fiber films by conjugated electrostatic spinning technique. Mouse fibroblast L929 was used as a model to evaluate its cell and histocompatibility, which provided experimental basis for application in guided bone regeneration (GBR). RESULTS: Fibroblasts showed good adhesion and growth on the surface of fiber membrane; there were a large number of deep pseudopodias, which were arranged along the orientation of fibers. CONCLUSIONS: PLGA/fish skin collagen conjugated electrostatic spinning membrane is beneficial to fibroblast growth and is expected to be used for GBR.

Simple synthesis of hierarchical AuPt alloy nanochains for construction of highly sensitive hydrazine and nitrite sensors.

Herein, a single-step co-reduction aqueous route was designed for preparation of hierarchical AuPt alloy nanochains, firstly using amprolium hydrochloride as a new stabilizing agent and structure-director. The morphology, structure, composition, and size of the products were characterized by a series of technique. The growth mechanism of AuPt nanochains was discussed in details. The AuPt nanochains modified glassy carbon electrode showed the improved analytical performances for determination of nitrite and hydrazine. The linear ranges of nitrite are 0.5-366.4µM and 466.4-2666.4µM for the two segments, and the detection limit is 0.03µM (S/N=3). The linear ranges of hydrazine are 5.0-116.4µM and 166.4-2666.4µM for the two segments, along with the low detection limit of 0.26µM (S/N=3). The performances of AuPt nanochains were superior to those of individual Pt and Au nanoparticles. It is ascribed to the specific hierarchical structures and synergistic effects of the bimetals.

[Morphological characteristics of upper alveolar bone around central incisor in Class II division 1 and division 2 malocclusion on cone-beam CT].

PURPOSE: During orthodontic treatment, the incisors in patients with Class II division 1 and division 2 malocclusion showed different clinical features, which determine the different ways to move the teeth to the suitable position. This study analyzed the morphology of alveolar bone around upper central incisor with cone-beam CT (CBCT). METHODS: The sample consisted of 20 normal malocclusion and 40 patients with Class II malocclusion （division 1 20 cases and division 2 20 cases）. CBCT images before orthodontic treatment were reconstructed by INVIVO 5.0 image processing software. Paired t test was used for statistical analysis with SPSS 19.0 software package. RESULTS: At the upper central incisors, the alveolar thickness between normal malocclusion and Class II division 1 and division 2 malocclusion had significant difference except the palate thickness between normal malocclusion and Class II division 2 malocclusion (P<0.05). CONCLUSIONS: Orthodontist should consider the relationship between the teeth position and alveolar bone shape comprehensively, choose the correct plan in order to avoid root desorption, alveolar bone loss, fenestration and other adverse reactions.

[Comparison of condylar position between Angle Class I and Class II malocclusion in teenagers].

PURPOSE: To analyze and compare the difference of condylar position between Angle Class I and Class II malocclusion patients using cone-beam CT (CBCT). METHODS: Thirty Class I patients, 30 Class II division 1 patients and 30 Class II division 2 patients were selected in this study. Each patient underwent CBCT. The images in the oblique position perpendicular to the condyloid process were reconstructed by Examvision software. The joint space was measured by Exam Vision software. The data were processed with SPSS17.0 software package. RESULTS: The upper joint space was larger in Class II, the posterior joint space was smaller in Class II patients; and in Class II division 1 patients, both of the upper and anterior joint spaces were larger than in Class II division 2 patients，the differences were significant (P<0.05). The length of condyle was longer in Class I patients than in Class II patients. CONCLUSIONS: The condylar position in Class II division 2 patients was lower and further backward. The length of condyle is shortest in Class II division 2 patients.

[Preliminary study of bonding strength between diatomite-based dental ceramic and veneering porcelains].

PURPOSE: In order to choose the best veneering porcelain for diatomite-based dental ceramic substrate, the bonding strength between diatomite-based dental ceramics and veneering porcelains was measured, and the microstructure and elements distribution of interface were analyzed. METHODS: The coefficient of thermal expansion (CTE) of diatomite-based dental ceramics was detected by dilatometry. Three veneering porcelain materials were selected with the best CTE matching including alumina veneering porcelain (group A), titanium porcelain veneering porcelain (group B), and E-max veneering porcelain (group C). Shear bonding strength was detected. SEM and EDS were used to observe the interface microstructure and element distribution. Statistical analysis was performed using SPSS 17.0 software package. RESULTS: The CTE of diatomite-based dental ceramics at 25-500 degrees centigrade was 8.85×10-6K-1. The diatomite-based substrate ceramics combined best with group C. Shear bonding strength between group A and C and group B and C both showed significant differences(P<0.05). SEM and EDS showed that the interface of group C sintered tightly and elements permeated on both sides of the interface. CONCLUSIONS: The diatomite-based substrate ceramics combines better with E-max porcelain veneer.

[The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

PURPOSE: To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. METHODS: Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. RESULTS: With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. CONCLUSIONS: Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

[A study on the thickness of buccal bone in the mandible of different vertical facial type in adults using cone-beam CT].

PURPOSE: To provide some references of using micro-implant anchorage in clinical orthodontic treatment, the thickness of buccal bone of mandible of different vertical facial type in adults with cone-beam CT (CBCT) were measured. METHODS: Initial 3-dimensional images of 45 adult patients (15 men, 30 women)were reoriented by using a standardized protocol, and divided into 3 groups by angle of mandibular plane (G1: high angle, 15 patients; G2: average angle, 15 patients; G3: low angle, 15 patients). After signing the informed consent form, three measurement points were defined at 4, 6, and 8mm from the alveolar crest in each measurement area. Statistical analysis was performed with SPSS11.0 software package. RESULTS: The thickness of buccal bone in mandible was thinner in G1 than in G2, and was thinnest in G3. The cortical bone thickness was thickest at the 8 mm level and thinnest at the 4mm level. CONCLUSIONS: The study suggested that the cortical bone thickness at 4mm level from the alveolar crest was safe for implantation. It is more stable when the distance of implants was more away from the alveolar crest. Patients with low mandibular plane angle should use self-tapping micro-implant anchorage. Supported by Nantong Science and Technology Fund (HS2013033).

[Clinical effect of premolar extraction with high torque self-locking appliances].

PURPOSE: To analyze the clinical effect of extraction correction of patients with maxillary protrusion by using Damon high torque appliances. METHODS: Forty patients with extraction of four first premolars due to orthodontic treatment were selected. They had protrusion of maxilla and were randomly divided into two groups. Both arches of Damon group were treated with Damon high torque appliances and MBT group were corrected with traditional MBT straight wire appliance; patients in two groups received sliding mechanics for adduction of upper anterior teeth. Cephalometric radiophotographs were analyzed before（T0）and after adduction of upper anterior teeth（T1）. The difference between the two groups was analyzed with SPSS15.0 software package. RESULTS: The upper incisors showed a more retruded position in the two groups at T1,although they showed a similar amount in both groups. The backward movement of upper lip was 2.31mm in Damon group, which was significantly less than that of 2.81mm in MBT group(P<0.05). No significant difference in the first molar mesialization was detected between Damon group(2.33 mm) and MBT group(2.36mm) (P>0.05). For anterior teeth retraction, nasolabial angle (NLA) in MBT and Damon group were 107.44°and 106.33°, increase of NLA in MBT group was 9.17°,which was significantly larger than that of 7.22°in Damon group (P<0.05). U1-MxP in MBT and Damon were 110.61°and 114.11°. U1-MxP decreased 12.06°in MBT group, while significant change was deteced in Damon group of 7.61°(P<0.05). CONCLUSIONS: Application of Damon high torque appliances in extraction treatment of maxillary protrusion patients yielded better control of the labial crown torque of anterior teeth, and avoided excessive lingual inclination of anterior teeth compared with MBT in adduction of upper anterior teeth.

[Finite element analysis of mechanical characteristics during retracting mandibular incisors through sliding mechanics].

PURPOSE: To analyze the mechanical characteristic changes of teeth and arch under different loading direction during retracting mandibular incisors through implant, simulating clinical loading system. METHODS: Three- dimensional finite element model, including brackets, archwire, crampable hooks and implants, was reconstructed. The force direction was determined by connecting the points in crampable hook and the center point of implant, and the force point and force direction were changed with the adjustment of the height of crampable hook and the height of implant. Then three-dimensional movement trend of teeth, stress distribution in periodontal membrane and the largest displacement of archwire nodes in each group were calculated and analyzed. SPSS13.0 software package was used for statistical analysis. RESULTS: It was found that the height of implant and the height of crampable hook were correlated with the movement of teeth and stress distribution in periodontal membrane (P<0.01). The movement trend of teeth in the condition of different height of implant and different height of crampable hook was illustrated as follows:(1)with the height increase of crampable hook, the movement trend of the central and lateral incisors varied from mesial lingual tipping to mesial labial tipping. However, canines tipped distally and lingually; the second premolars tipped mesially and lingually, and the first molar roots tipped distally and buccally with decreasing tipping angle. (2) The largest stress distribution in the whole arch was located in the labial apical one-third area of the lateral incisors, while that of canines and the first molars was located in the alveolar ridges and root bifurcations. CONCLUSIONS: These findings indicate that the different movement trend during retracting anterior teeth can be achieved through the adjustment of the height of crampable hook, and implant, anchorage can effectively control anterior movement of the posterior teeth. Supported by Research Fund of Bureau of Science and Technology of Nantong City (Grant No. S40023).