Three-Dimensional Finite Element Analysis on En-Masse Retraction of the Maxillary Anterior Teeth With Quantitative Combined Loading Control.

This study aims to elucidate the biomechanical effects of combined loading of maxillary anterior and posterior implants using the sliding method on en-masse retraction of the anterior teeth and to quantify the loading ratio (LR) of anterior and posterior implants to achieve controlled retraction of the maxillary anterior teeth. A three-dimensional finite element model of the maxilla-upper dentition appliance was constructed. Implants were placed on the distal (A) and mesial (B) sides of the lateral incisors as well as on the mesial (C) side of the first molar and different amounts of force were loaded between the implants using 2- or 5-mm traction hooks. The labiolingual movement of the anterior teeth was recorded and the relationship between the LR of the implants and the movement of the central incisors was evaluated. With 2-mm traction hooks, the central incisors exhibited a translation tendency during retraction at lower A/C and B/C LR and labial or lingual crown inclination at higher values. With 5-mm traction hooks, the central incisors, lateral incisors, and canine teeth exhibited a labial crown inclination. The results of this study suggest that 2-mm traction hooks can cause labial crown inclination, translation tendency during retraction, or lingual crown inclination of the central incisors due to alterations in the LR of the anterior and posterior implants. The central incisors only exhibited labial crown inclination during combined loading of the anterior and posterior implants when 5-mm traction hooks were used.

Three-dimensional finite element analysis of the stability of mini-implants close to the roots of adjacent teeth upon application of bite force.

To investigate the cause of mandibular implant loss, we evaluated the stress distribution in the bone under bite force when the miniimplant was near the root using three-dimensional finite element analysis. Our analysis involved four finite element models with different distances between the implant and adjacent tooth root and three loading conditions. With loading of the tooth only or both the tooth and implant, the peak stress within the bone around the implant neck, displacement, and stress surrounding the bone near the root increased as the distance between the implant and root decreased. However, with separate loading of the implant, the stress did not correlate with the distance between the implant and root. Application of bite force increases stress within bones surrounding mini-implants near the roots of adjacent teeth and may threaten implant stability, but simple orthodontic loading has little effect on the stress distribution at the mini-implant-bone interface.

Finite Element Analysis of Bone Stress for Miniscrew Implant Proximal to Root Under Occlusal Force and Implant Loading.

Because of the narrow interradicular spaces and varying oral anatomies of individual patients, there is a very high risk of root proximity during the mini implants inserting. The authors hypothesized that normal occlusal loading and implant loading affected the stability of miniscrew implants placed in proximity or contact with the adjacent root. The authors implemented finite element analysis (FEA) to examine the effectiveness of root proximity and root contact. Stress distribution in the bone was assessed at different degrees of root proximity by generating 4 finite element models: the implant touches the root surface, the implant was embedded in the periodontal membrane, the implant touches the periodontal surface, and the implant touches nothing. Finite element analysis was then carried out with simulations of 2 loading conditions for each model: condition A, involving only tooth loading and condition B, involving both tooth and implant loading. Under loading condition A, the maximum stress on the bone for the implant touching the root was the distinctly higher than that for the other models. For loading condition B, peak stress areas for the implant touching the root were the area around the neck of the mini implant and the point of the mini implant touches the root. The results of this study suggest that normal occlusal loading and implant loading contribute to the instability of the mini implant when the mini implant touches the root.

Dose-dependent targeted knockout methodology combined with deep structure elucidation strategies for Chinese licorice chemical profiling.

One of the limitations with regards to the chemical profiling of Chinese herbs is that low-level compounds are masked by high-level structures. Here, we established a novel methodology based on a dose-dependent targeted knockout (DDTK) technique combined with deep structure elucidation strategies to allow the chemical profiling of Chinese licorice. We employed ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-Q/TOF MS) incorporated with the DDTK technique to identify the compounds in different concentration samples and found that the compounds at the high- or medium-level were detected readily in the sample at a low concentration; subsequently, minor or trace-level constituents were identified in the sample at a high concentration by rejecting high-level constituents detected in the sample at a low concentration based on a heart-cutting technique during analysis. In this study, among the 232 compounds detected, 27 compounds were unequivocally identified and 165 compounds, including 29 new compounds and two new natural products, were tentatively characterized. The novel methodology established in this work paves the way the further identification of compounds from complicated mixtures, especially traditional Chinese medicines.

Liquorice, a unique "guide drug" of traditional Chinese medicine: a review of its role in drug interactions.

ETHNOPHARMACOLOGICAL RELEVANCE: Liquorice is the root of Glycyrrhiza uralensis Fisch. or Glycyrrhiza glabra L., Leguminosae. It is a widely used herbal medicine native to southern Europe and parts of Asia and has beneficial applications in both the medicinal and the confectionery sectors. Unlike its usage in Europe, liquorice in traditional Chinese medicine is commonly combined with other herbs in a single prescription, as a unique "guide drug" to enhance the effectiveness of other ingredients, to reduce toxicity, and to improve flavor in almost half of Chinese herbal formulas. A review on phytochemical and pharmacological research to explain this unique "guide" effect is suggested for future investigations. MATERIALS AND METHODS: The information was collected from scientific journals, books, and pharmacopeia. The studies about the traditional uses, randomized controlled trials, chemical, pharmacological and pharmacokinetic data related to liquorice-herb/drug interaction or combination were included in the review. RESULTS: According to recent reports, the "guide" effect of liquorice is partially through components transformed in liquorice-drug interaction; altering enzyme activity of P450 isoforms, as evidenced by induction of model probe substrates; and modulation of drug transporter proteins such as intestinal P-glycoprotein. CONCLUSION: The overview and comparison of traditional uses of liquorice with recent pharmacological studies and randomized controlled trials provide new insights into this ancient drug for future investigations and clinical use, especially in drug combination.

[Mini-implant stability analysis at different healing times before loading].

OBJECTIVE: This study aims to biomechanically analyze a mini-implant at different healing times before loading. METHODS: Sixty-four mini-implants with (12 +/- 1) N x cm insertion torque were placed in the low jaw of eight beagle dogs. The test mini-implants remained in the low jaw for 0, 1, 3, and 8 weeks of bone healing and for an additional 10 weeks under a force of 0.98 N. The unloaded control implants were further divided into four groups (1, 3, 8, and 10 weeks). Maximum removal torque (MRT) testing was performed to evaluate the interfacial share strength of each group. Surface analysis of the removed implants was performed by scanning electric microscope (SEM). RESULTS: The MRT for the loading implants at 0, 1, 3, and 8 weeks of healing were 4.10, 4.25, 2.42, and 4.42 N x cm, respectively. During the healing process, the removal torque values of the 3-week implants were significantly lower than those of the other healing groups (P < 0.05). The unloaded 3-week implants also had lower removal torques (P < 0.05). The implant surface of the 3-week test group showed more fibrous bone. However, the other loading implants had more lamellar-like tissue. CONCLUSION: A stable dangerous period occurred approximately 3 weeks after mini-implant insertion. A 3-week healing is disadvantageous to the stability of the implant. Orthodontics loading occurred immediately or after 1 week as a function of the healing time. The 8-week implant appeared to have a positive effect on peri-implant bone remodeling and implant stability.

Sec14l3 is specifically expressed in mouse airway ciliated cells.

Airway epithelium is a key component for airway integrity. Previously, we found that expression of the Sec14l3 gene that encodes a 45-kDa secretory protein is inversely associated with the progression of experimentally induced airway inflammation and degeneration/necrosis of alveolar epithelium. In this report, using in situ hybridization we demonstrated that the ciliated cells in mouse lung selectively express Sec14l3 mRNA. In a three-dimensional culture of mouse tracheal epithelial cells, levels of the Sec14l3 mRNA correlated with the differentiation of ciliated cells. Intranasal infection of adult mice with influenza virus resulted in a 20-fold, progressive decrease in Sec14l3 mRNA expression over 10 days post infection. These results enhance the potential value of Sec14l3 as a ciliated epithelial cell-specific biomarker for the progression of airway inflammations such as airway viral infection and asthma.

[The effect of mini-implant lengths on stress distributions in peri-implant surface].

OBJECTIVE: To observe the effect of mini-implant lengths on stress distribution in peri-implant surface. METHODS: The 3D finite element analysis mandible and mini-implant models with diameter of 1.6 mm, lengths of 6, 8, 10 and 12 mm were established. The mini-implants were inserted into designed site of mandibular vertically, respectively. A force of 1.96 N were applied mesioly and 45 degrees tilted mesio-vertically in models. The stress distribution under every condition was recorded and analyzed. RESULTS: When load was applied mesially, the maximum stress varied from 3.500 to 3.765 MPa, the maximum displacement varied from 1.266 to 1.288 microm. When load was applied 45 degrees tilted mesio-vertically, the maximum stress varied from 4.075 to 4.510 MPa, the maximum displacement varied from 1.668 to 1.694 microm. All of the maximum stress and displacement of loading mesially were lower than loading mesio-vertically. CONCLUSION: The change of the mini-implant length within 6-12 mm don't show much influence on the stress distribution. The loading type is an important factor influencing stress and displacement of peri-implant bone.

Inverse relationship between Sec14l3 mRNA/protein expression and allergic airway inflammation.

Bronchial asthma is an inflammatory disease of the airways. The Sec14l3 gene, encoding a 45-kDa secretory protein, is specifically expressed in airway epithelium. Here, we report on the kinetics of Sec14l3 expression following allergic inflammation of the lung. Brown Norway rats were sensitized by intraperitoneal injection of ovalbumin, followed by challenge with aerosolized ovalbumin after a 3-week interval. This animal model showed many features similar to human allergic asthma: an increase in inflammatory cells such as eosinophils, lymphocytes and neutrophils in bronchoalveolar lavage (BAL) fluid and histopathological alteration of lung tissue, exhibiting infiltration of these inflammatory cells and degeneration and necrosis of alveolar epithelium. These parameters reached their maximal level 24h after allergen challenge. In contrast, quantitative polymerase chain reaction analyses demonstrated a rapid and significant reduction of Sec14l3 mRNA in lung tissue and maximum reduction (to 1.4% of the control) was observed at 24h. Pretreatment with dexamethasone significantly suppressed both the Sec14I3 mRNA reduction and all of the inflammatory changes. The 45-kDa secretory protein was identified in the supernatant of BAL fluids. Two-dimensional gel images of the supernatant proteome also revealed down-regulation of the protein following inflammation (to approximately 30% of the control at 24h). Thus, Sec14l3 expression is highly and inversely associated with the progression of airway inflammation. Sec14l3 mRNA and protein may function in the homeostasis of airway epithelial cells under normal conditions.

T cells are involved in the development of arthritis induced by anti-type II collagen antibody.

T cells play an important role in initiating autoimmune responses and maintaining synovial inflammation in rheumatoid arthritis. Although, anti-type II collagen antibody-induced arthritis (CAIA) is generally believed to be a T cell- and B cell-independent model, the detailed pathogenesis of CAIA remains unclear. In the present study, to elucidate the contribution of T cells to the pathogenesis of CAIA, we evaluated the effects of CTLA4 Ig and cyclosporin (CsA). Arthritis was induced in mice by intravenous injection of anti-type II collagen antibody followed by intraperitoneal injection of lipopolysaccharide. CTLA4 Ig was intraperitoneally administered and CsA was subcutaneously administered; then the severity of arthritis was evaluated by scoring the edema and erythema of paws and by measuring hind paw thickness. Paw samples were collected 12 days after the antibody injection, and the mRNA expression levels were analyzed by real-time quantitative polymerase chain reaction. Administration of CTLA4 Ig ameliorated the increases in arthritic score and paw thickness in the later phase, but not in the early phase of arthritis. CsA suppressed the increases in arthritic score and paw thickness in both the early and later phases of arthritis. CTLA4 Ig and CsA suppressed mRNA up-regulation of T-cell markers, CD3 and CD25, and immune response-related mediators, IFN-gamma and IL-12. They also suppressed the up-regulation of macrophage marker, F4/80, and proinflammatory cytokines, TNF-alpha, IL-1beta and IL-6. The results provide direct evidence that arthritis in this model is T-cell activation dependent.

Validation of universal conditions for duplex quantitative reverse transcription polymerase chain reaction assays.

Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) is widely used for measuring mRNA in biological materials. Multiplex qRT-PCR provides advantages for gene expression analysis by reducing sample requirements, saving time, and lowering experimental cost. However, there are currently no universal qRT-PCR experimental conditions validated as applicable to a large set of genes. We report here on the standardized condition for two-color real-time qRT-PCR with the Quantitect Multiplex PCR kit. We first verified lack of interferential effects of gene abundance on the efficiency of PCR amplification by an 8x8 checkerboard validation method, in which combinations of the plasmids encoding either fibronectin1 or cyclophilin mixed at 64 different ratios were amplified with the Quantitect Multiplex PCR kit. Then, a duplex analysis for 69 genes was performed to verify the universality of the reaction condition. The results were consistent with corresponding data obtained from the singleplex format, and their intra- and interassay coefficients of variance were sufficient for performing reliable quantitative analysis. This duplex format was also applicable to samples from animal experiments, with a good correlation between singleplex and duplex-assay (R(2)>0.92) observed. This duplex assay system is ready for use in high-throughput gene expression analysis without any gene-pair compatibility restrictions limiting its use.