Biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition at different heights / 中国组织工程研究

BACKGROUND: In orthodontics, micro-implant anchorage in the infrazygomatic crest that cannot damage the tooth root can achieve an unobstructed overall movement of the upper dentition. However, little is reported on the stress and strain of the tooth and alveolar bone during the distal movement of the upper dentition. OBJECTIVE: To set up a three-dimensional finite element model to perform a biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition at different heights. METHODS: Cone-beam CT data from a female patient admitted for orthodontic treatment was saved in Dicom format, and imported into Mimics 16.01 software. Then, a three-dimensional model of the right maxilla and tooth dentition was made by automatically and manually selecting boundaries. The model was imported into Geomagic8.0 for removal of noise dots and smooth processing, and then it was imported into the Mimics16.01 software and meshed for the surface/body through 3 Matics software. Afterwards, three-dimensional models maxillary denture, archwires and traction hooks and implants were established by ProE5.0, and all the models were imported into ANSYS13.0 and assembled and analyzed for stress and strain analysis. RESULTS AND CONCLUSION: We successfully established the three-dimensional finite element model for biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition at different heights, and this model conformed to the anatomic features. With the increase of the height of traction hooks (1, 4, 7, 10 mm), the vertical stress of the maxillary teeth increased gradually, and had no correlation with the change of the horizontal stress. With the increase of the height of traction hooks, at the sagittal axis, the strain at midpoints of middle incisors, canine teeth, and first molars decreased gradually and the strain at the root of middle incisors and canine teeth also decreased gradually, but there was no change in the strain at the root of first molars. With the increase of the height of traction hooks, at the vertical axis, the strain at the midpoints and tooth root of middle incisors increased, while the strain of canine crown increased gradually and that of the canine root decreased; the strain at the midpoint of first molars changed a little, and the strain of the tooth root decreased gradually. The dentition rotated from clockwise to counterclockwise. To conclude, the three-dimensional finite element model made in the study is consistent with the anatomic structure, which provides a basis for biomechanical analysis of micro-implant anchorage in the infrazygomatic crest for the distal displacement of the upper dentition. The upper dentition impedance center located in the position of 4 to 7 mm of the arch wire can be used as the microimplant support site in the infrazygomatic crest.

Effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats

OBJECTIVE@#To investigate effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats.@*METHODS@#Eighty SD rats were randomly divided into 4 groups, blank control group (group A) with 5 rats, treatment normal group (group B) with 25 rats, inflammation control group (group (group C) with 25 rats, inflammation treatment group (group D) with 25 rats. Immunohistochemistry and histomorphometric analysis was performed to measure the expression of IL-6, IL-8 and the first molar to the recent movement in the distance.@*RESULTS@#The expression of IL-8 reached a maximum on day 5 and declined thereafter in group B; the expression of IL-6 reached a maximum on day 5 in group B. The expression of IL-6 and IL-8 was gradually weakened with time in group C. The expression of IL-6 and IL-8 were high, and reached a maximum on day 5 and declined thereafter in group D. AD of positive cells in group D were higher than group B at each time point (P<0.05). The time which 0.49 N orthodontic force was loaded was longer, orthodontic tooth movement distance was greater. Movement distance in group D were longer than group B (P<0.05).@*CONCLUSIONS@#Orthodontic force as well as inflammatory stimulus can evoke the expression of IL-6 and IL-8. Under the combined effects of inflammation and orthodontic force, the expression of IL-6, IL-8 will increase.

Pitavastatin enhances angiogenesis and perfusion in a murine mode of limb ischemia / 中华心血管病杂志

<p><b>OBJECTIVE</b>We investigated the effects of pitavastatin on angiogenesis and perfusion in C3H/He mice with unilateral hind limb ischemia.</p><p><b>METHODS</b>C3H/He mice treated with saline (n = 15) or pitavastatin (1 mg.kg(-1).d(-1), n = 15) per gavage for 1 week underwent unilateral hind limb ischemia surgery and were treated for another 5 weeks. Hind-limb blood flow was measured by Laser Doppler perfusion imager (LDPI, ischemic/nonischemic limb, %) at baseline, immediately after ischemia and weekly thereafter for 5 weeks. Endpoints included local vessel counts by immunofluorescence, phospho-Akt positive cell counts by immunoenzyme histochemical technique, vascular endothelial growth factors (VEGFs) expression in ischemic limbs by Western blot and serum nitric oxide metabolite (NOx) by chrome dioxide Griess method.</p><p><b>RESULTS</b>Lower extremity perfusion was significantly improved in pitavastatin treated mice vs. controls as measured by LDPI% at 1 week post ischemia and thereafter (P < 0.05). Pitavastatin treatment was associated with significantly increased capillary count [(47 +/- 11) vs. (26 +/- 14)/per high-power field (x 200), P < 0.05] and greater percentage of phospho-Akt positive cells [(6 +/- 1) vs. (2 +/- 0)/per high-power field (x 200), P < 0.05] in ischemic limbs. Serum NOx [(77.3 +/- 21.8) vs. (52.1 +/- 11.2) mol/L, P < 0.05) and VEGF protein expression in ischemic limbs were also significantly increased in pitavastatin group than those in control group.</p><p><b>CONCLUSIONS</b>Pitavastatin enhances angiogenesis and perfusion in CsH/He mice with limb ischemia.</p>

The pro-angiogenesis effect of Pitavastatin in the Klotho gene-knockout mice / 中国应用生理学杂志

<p><b>AIM</b>To discuss the effect of Pitavastatin on angiogenesis in vivo and its mechanism in Klotho heterozygous deficient mice.</p><p><b>METHODS</b>The heterozygous deficient Klotho mice (kl +/-) and wild mice (kl +/+) from the same litter were used to establish the animal model of hind-limb ischemia and grouped into control and Pitavastatin group, respectively. Hind-limb blood flow was evaluated using Laser Doppler perfusion imager (LDPI) before treatment and after operation of hind-limbs. The capillaries in muscle of limbs were counted by means of CD-31 labeled immuno-fluorescence. The phosphorylation of Akt (Protein kinase B) in cells was measured by direct immunohistochemical technique. The expression of vascular endothelial growth factors (VEGFs) in muscle of limbs was assessed using Western blotting.</p><p><b>RESULTS</b>After treatment of Pitavastatin, the blood flow in ischemic limbs of the Kl +/- and wild mice improved obviously, the ratio of blood flow area in ischemic limb to that in non-ischemic limb increased and the density of capillaries increased in ischemic limbs of the Kl +/- and wild mice. Pitavastatin enhanced the phosphorylation of Akt and the expression of VEGF in ischemic limbs of the Kl +/- and wild mice.</p><p><b>CONCLUSION</b>Pitavastatin has the pro-angiogenesis effect in vivo and the VEGF-p-Akt-NO pathway may be involved in the mechanism of the effect of Pitavastatin.</p>

Effect of changes in pH on intracellular Ca2+ and cell length of myocytes / 中国应用生理学杂志

<p><b>AIM</b>To examine the effects of pHi on [Ca2+]i, cell length and Ca2+ sensitivity of myofilaments in rat myocyte.</p><p><b>METHODS</b>We used microscopic spectral imaging approach to monitor simultaneously [Ca2+]i, pHi and cell length with fluorescent indicator indo-1 and SNARF-1 in isolated single rat myocyte.</p><p><b>RESULTS</b>Exposure of cell to 20 mmol/L Sodium Propionate induced an intracellular acidosis which increased slightly systolic and diastolic [Ca2+]i, decreased the cell shortening (CS) and Ca2+ sensitivity of myofilament (P < 0.01). Exposure of cell to 15 mmol/L NH4Cl induced an intracellular alkalosis which decreased systolic and diastolic [Ca2+]i, increased the cell shortening and Ca2+ sensitivity of myofilament (P < 0.01).</p><p><b>CONCLUSIONS</b>In the early time of acidosis, [Ca2+]i, as well as cell length increases respectively. While alkalosis, [Ca2+]i and cell length decreases respectively. The effect of acidosis and alkalosis on Ca2+ sensitivity presents non-linear relationship, i.e. the effect of acidosis on sensitivity, caused by pHi change, is less than that of alkalosis.</p>