A biomechanical case study on the optimal orthodontic force on the maxillary canine tooth based on finite element analysis / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Excessive forces may cause root resorption and insufficient forces would introduce no effect in orthodontics. The objective of this study was to investigate the optimal orthodontic forces on a maxillary canine, using hydrostatic stress and logarithmic strain of the periodontal ligament (PDL) as indicators. Finite element models of a maxillary canine and surrounding tissues were developed. Distal translation/tipping forces, labial translation/tipping forces, and extrusion forces ranging from 0 to 300 g (100 g=0.98 N) were applied to the canine, as well as the force moment around the canine long axis ranging from 0 to 300 g·mm. The stress/strain of the PDL was quantified by nonlinear finite element analysis, and an absolute stress range between 0.47 kPa (capillary pressure) and 12.8 kPa (80% of human systolic blood pressure) was considered to be optimal, whereas an absolute strain exceeding 0.24% (80% of peak strain during canine maximal moving velocity) was considered optimal strain. The stress/strain distributions within the PDL were acquired for various canine movements, and the optimal orthodontic forces were calculated. As a result the optimal tipping forces (40-44 g for distal-direction and 28-32 g for labial-direction) were smaller than the translation forces (130-137 g for distal-direction and 110-124 g for labial-direction). In addition, the optimal forces for labial-direction motion (110-124 g for translation and 28-32 g for tipping) were smaller than those for distal-direction motion (130-137 g for translation and 40-44 g for tipping). Compared with previous results, the force interval was smaller than before and was therefore more conducive to the guidance of clinical treatment. The finite element analysis results provide new insights into orthodontic biomechanics and could help to optimize orthodontic treatment plans.

Protective effect of dexmedetomidine against perioperative inflammation and on pulmonary function in patients undergoing radical resection of lung cancer / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the protective effect of dexmedetomidine against perioperative inflammation and on pulmonary function in patients undergoing radical resection of lung cancer.</p><p><b>METHODS</b>From May, 2014 to May, 2016, 124 patients with lung cancer receiving radical surgeries were randomized into experimental group (n=62) and control group (n=62). The patients in the control group received a single anesthetic agent for anesthesia, and additional dexmedetomidine was given in the experimental group. The levels of serum interleukin-1β (IL-1β), IL-10, and tumor necrosis factor-alpha (TNF-α) were measured before the operation (T), at 30 min (T) and 60 min (T) during one lung ventilation (OLV) and at the end of operation (T). Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of malondialdehyde (MDA), myeloperoxidase (MPO) and xanthine oxidase (XOD), and the arterial oxygen partial pressure (PaO), oxygenation index (OI), airway plateau pressure (APP) and airway resistance (AR) were also recorded.</p><p><b>RESULTS</b>At the time points of Tand T, IL-1β, IL-10, MDA, MPO, TNF-α, and XOD levels were significantly increased in both of the groups, but the levels of IL-1, IL-10, TNF-α and MDA were significantly lower and MPO and XOD levels significantly higher in the experimental group than in the control group (P<0.05). In both groups, PaOand OI decreased and APP and AR increased significantly at Tand T, but APP and AR were significantly lower and PaOand OI significantly higher in the experimental group than in the control group (P<0.05).</p><p><b>CONCLUSION</b>Anesthesia with dexmedetomidine in lung cancer patients undergoing radical surgery can effectively reduce the inflammatory response of the lungs and protect the lung function of the patients.</p>

Features of preoperative contrast-enhanced ultrasound of breast cancer: relationship with the syndrome classification in traditional Chinese medicine / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the relationship between the features of preoperative contrast-enhanced ultrasound and the differentiation of symptoms and signs for syndrome classification by traditional Chinese medicine (TCM).</p><p><b>METHODS</b>Eighty-two patients with malignant breast tumor were examined with contrast-enhanced ultrasound before the operation. The tumor diameter was greater than 2.0 cm in 48 cases and below 2.0 cm in 34 cases. According to the curative effect standard of TCM disorder, differentiation of symptoms and signs for classification of syndrome were performed, and the ultrasonic manifestations of different syndrome types were compared.</p><p><b>RESULTS</b>In patients with maximum tumor diameter < or = 2 cm, Chong and Ren disorder type and liver Qi stagnation type were prevalent. In those with tumor diameter of <2 cm, Zeyi liver Qi stagnation type and virtual drug junction were more common. The mass peak intensity, slope of increase, enhancement intensity index and time-intensity curve of ultrasound differed significant between different syndrome types (P<0.05).</p><p><b>CONCLUSION</b>The preoperative ultrasound features of breast cancer are associated with the syndrome types in TCM.</p>

Contrast-enhanced ultrasound findings of breast cancer / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the manifestation of breast cancers of different sizes in contrast-enhanced sonography.</p><p><b>METHODS</b>Eighty-four patients with breast cancers were examined by contrast-enhanced ultrasound. Among them, the tumor diameter was beyond 2.0 cm in 50 cases, and no greater than 2.0 cm in the rest cases. The time-intensity curve (TIC) on the enhanced images was analyzed quantitatively, and the relations between the type of TIC and the enhancement patterns of the tumors were analyzed.</p><p><b>RESULTS</b>The enhancement patterns of the breast cancers showed significant difference between patients with tumor diameter beyond 2.0 cm and those with smaller tumors (P<0.01), but the other parameters were comparable between the two groups (P>0.05).</p><p><b>CONCLUSION</b>The enhancement patterns of breast cancers differ between tumors with sizes over 2.0 cm and smaller tumors, and differential analysis is suggested in the diagnosis of breast cancer using contrast-enhanced ultrasound.</p>

Effect of continuously compressive pressure on the expression of RANKL mRNA in human periodontal ligament cells in vitro / 中南大学学报(医学版)

OBJECTIVE@#To determine the effect of continuously compressive pressure (CCP) on the expression of receptor activator of nuclear factor kappa B ligand (RANKL) in human periodontal ligament cells (HPDLCs) and to investigate the role of RANKL in alveolar bone rebuilding during orthodontic tooth movement.@*METHODS@#The primary HPDLCs were isolated from human periodontal ligament by explanting enzymatic digestion with trypsin and collagenase to establish a pressure model. Top-bottom axial pressures (1, 2, and 3 g/cm(2)) were laid on HPDLCs for 0.5, 1.5, 6, 12, 24, and 48 h, respectively. The RANKL expression was identified by the reverse transcription-polymerase chain reaction (RT-PCR) at the mRNA level.@*RESULTS@#The expression of RANKL mRNA significantly increased in a time-dependent manner (P<0.01), so did the value of pressure, especially in the 2 g/cm(2) group (P<0.05).@*CONCLUSION@#CCP can up-regulate the expression of RANKL mRNA in human periodontal ligament cells.

Tension-force induced cyclooxygenase-2 expression mediated by microfilament in human periodontal ligament fibroblast / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the role of microfilament polymerization in menchanotransduction by human periodontal ligament fibroblast (hPDLFs).</p><p><b>METHODS</b>In tension-force group, hPDLFs were treated by tension-force values of 18% for 8 h, 16 h, 24 h. In tension-force and inhibitor group, the sample was treated with 5 microg/mL cytochalasin B before using tension-forece. Each sample was collected and the expression of cyclooxygenase-2 was measured by using immunohistoche staining.</p><p><b>RESULTS</b>In tension-force group, the expression of cyclooxygenase-2 enhanced with the extension of loading time. In tension-force and inhibitor group, cyclooxygenase-2 expression was depressed and had no relation with loading time.</p><p><b>CONCLUSION</b>Tension-force induced cyclooxygenase-2 expression is mediated by microfilament, disruption of the microfilament polymerization will destroy mechanotransduction in hPDLFs.</p>

Effect of erigeron breviscapus on the expression of vascular endothelial growth factor in the periodontal tissues of rabbits during orthodontic tooth movement / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To detect the effect of erigeron breviscapus on the expression of vascular endothelial growth factor (VEGF) in the periodontal tissues during orthodontic tooth movement.</p><p><b>METHODS</b>45 rabbits were divided into 3 groups (groups A, B and C). Groups A and B included experimental group of 1, 3, 7 and 14 days respectively. The mandibular first molar of each experimental rabbit was observed. The rabbits of group A and group B received iontophoresis with erigeron breviscapus into the right (group A-R and group B-R) and with normal sodium into the left as the control (group A-L and group B-L). Additionally, the rabbits of group B were designed orthodontic appliance, by which 0.78 N mesial force was applied to pull the mandibular first molars. Group C, group of 0 day, was no iontophoresis and orthodontic appliance as the control. After killed on schedule, the amount of experimental tooth movement was measured and the expression of VEGF was examined by immunohistochemical method.</p><p><b>RESULTS</b>The amount of experimental tooth movement increased successively from 1 to 14 days. The differences among days 3, 7 and 14 were significant in the comparison between group B-R and group B -L (P < 0.01). The expression of VEGF in groups A-R and B-L enhanced apparently compared with that in groups C and A-L (P < 0.01), but that in group B-R was the most apparent (P < 0.01). The expression of VEGF reached the peak level on day 3 in groups A-R and B-R (P < 0.01), but it reached the peak level on day 7 in group B-L (P < 0.01).</p><p><b>CONCLUSION</b>Erigeron breviscapus by iontophoresis can accelerate orthodontic tooth movement, and can meanwhile up-regulate the expression of VEGF in periodontium in the earlier period of orthodontic tooth movement. Thus it can be presumed that one of its mechanisms for erigeron breviscapus to accelerate orthodontic tooth movement is erigeron breviscapus effects the metabolism and differentiation of osteoblast and osteoclast through up-regulating the expression of VEGF in periodontium.</p>