3.Three-dimensional finite element analysis of maxillary anterior teeth retraction force system in light wire technique.
Xiangfeng ZHANG ; Chao WANG ; Xi XIA ; Feng DENG ; Yi ZHANG
West China Journal of Stomatology 2015;33(3):291-295
OBJECTIVEThis study aims to construct a three-dimensional finite element model of a maxillary anterior teeth retraction force system in light wire technique and to investigate the difference of hydrostatic pressure and initial displacement of upper anterior teeth under different torque values of tip back bend.
METHODSA geometric three-dimensional model of the maxillary bone, including all the upper teeth, was achieved via CT scan. To construct the force model system, lingual brackets and wire were constructed by using the Solidworks. Brackets software, and wire were assembled to the teeth. ANASYS was used to calculate the hydrostatic pressure and the initial displacement of maxillary anterior teeth under different tip-back bend moments of 15, 30, 45, 60, and 75 Nmm when the class II elastic force was 0.556 N.
RESULTSHydrostatic pressure was concentrated in the root apices and cervical margin of upper anterior teeth. Distal tipping and relative intrusive displacement were observed. The hydrostatic pressure and initial displacement of upper canine were greater than in the central and lateral incisors. This hydrostatic pressure and initial intrusive displacement increased with an increase in tip-back bend moment.
CONCLUSIONLingual retraction force system of maxillary anterior teeth in light wire technique can be applied safely and controllably. The type and quantity of teeth movement can be controlled by the alteration of tip-back bend moment.
Finite Element Analysis ; Humans ; Incisor ; Maxilla ; Tooth Movement Techniques ; methods ; Tooth Root ; Torque
4.Analysis of the statistics of graduates students in PUMC hospital
Xin ZHOU ; Jing WANG ; Zhi-yi ZHANG ; Chao NI
Chinese Journal of Medical Education Research 2011;10(9):1074-1076
The author analyzes the basic information in recent years,including overall students scale,students' age,application trends,etc.Some suggestions are made,regarding to recruiting plan,applicant qualification,recruiting mode,etc,in order to further improve the recruiting and graduate management.
6.Advances in studies on growth metabolism and response mechanisms of medicinal plants under drought stress.
Can SI ; Jun-Yi ZHANG ; Hu-Chao XU
China Journal of Chinese Materia Medica 2014;39(13):2432-2437
Drought stress exerts a considerable effect on growth, physiology and secondary metabolisms of the medicinal plants. It could inhabit the growth of the medicinal plants but promote secretion of secondary metabolites. Other researches indicated that the medicinal plants could depend on the ABA signaling pathway and secreting osmotic substances to resist the drought stress and reduce the damage by it. The article concludes the changes in growth, physiology, secondary metabolisms and response mechanisms of medicinal plants to drought stress that provides a theoretical basis for exploring the relationship between medicinal plants and drought stress.
Abscisic Acid
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metabolism
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Droughts
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Plant Proteins
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genetics
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metabolism
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Plants, Medicinal
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genetics
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growth & development
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metabolism
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Signal Transduction
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Water
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metabolism
7.Morphological changes of enteric deep muscular plexuses interstitial cells of Cajal in rats with multiple organ disfunction syndrome
Yi LI ; Qinghui QI ; Chao YU ; Dongliang ZHANG ; Weiming ZHU
Parenteral & Enteral Nutrition 2009;16(6):338-342
Objective: To observe the morphological changes of enteric deep muscular plexuses interstitial cells of Cajal (ICC-DMP) in rats with multiple organ dysfunction syndrome (MODS). Methods: Forty Wistar rats were randomly divided into control group and MODS model group. The enteric ICC-DMP network was observed using c-kit immunohistochemical staining with whole-mount preparation technique and confocal laser scanning microscopy , and the ultraslructural features of ICC-DMP was evaluated using transmission electron microscope. Results: Compared with those in control group, the distributions and densities of intestine ICC-DMP in MODS group were significantly decreased (P < 0. 05) , the ICC-DMP network was disrupted and the ultrastructural features of ICC-DMP were severely damaged. Conclusion: The ICC-DMP network was severely damaged in rats with MODS, and the mechanism of gastrointestinal dysmotility in MODS may be related to the morphological changes of ICC-DMP.
8.Expression of AKT2 gene in human liver cancer and its clinical significance
Yi XIE ; Xin CHEN ; Haixin QIAN ; Wanghe WANG ; Chao ZHANG
Chinese Journal of Hepatobiliary Surgery 2012;18(1):34-36
ObjectiveTo study the expression of AKT2 gene in liver cancer and its relationship to tumor progression.MethodsThe expression of AKT2 in liver cancer was detected by SP immunohistochemical stainin and reverse transcription polymerase chain reaction (RT-PCR).Four patients with benign liver tumors were used as control.ResultsThe positive rates of AKT2 in liver cancer tissue and benign control tissue were 62.5% (28/32) and 0% (0/4),respectively.The difference was significant.In addition,a positive expression of AKT2 correlated significantly with poor differentiation,positive lymph node and distant metastasis.The median survival after surgery was significantly shorter in patients with positive than with negative AKT2 (76d vs 463d).ConclusionThe detection of AKT2 was useful in assessing the progression of liver cancer,in determining prognosis and eventually in rendering a possible target for novel therapeutic strategies.
9.Clinical analysis of 41 cases of Hashimoto's disease accompanying with thyroid cancer
Zhipeng ZHANG ; Yi XIA ; Huijun LIAO ; Chao DONG ; Shi CHANG
Journal of Endocrine Surgery 2013;7(4):281-283
Objective To analyze the clinical characteristics of Hashimoto's disease(HD) accompanying with thyroid cancer,and to explore the experience of diagnosis and treatment.Methods Clinical data of 41 cases of HD accompanying with thyroid cancer were retrospectively analyzed.The patients were diagnosed by postoperative paraffin pathological examination from Jan.2002 to July 2011.Results 10 cases of HD,37cases of thyroid cancer,and 8 cases HD accompanying with thyroid cancer were diagnosed before operation.The rate of preoperative diagnosis was only 19.51%.All patients underwent surgical treatment,including 22 cases total thyroidectomy,14 cases subtotal thyroidectomy,and 5 cases lesion side lobe resection.24 cases underwent ipsilateral neck dissection,and 4 cases underwent bilateral neck dissection (ipsilateral radical resection,contralateral selective resection).Postoperative paraffin pathological examination proved that there were 39 cases of HD accompanying with thyroid cancer,1 case of focal cancer and 1 case of B-cell lymphoma of mucosa-associated thyroid.All patients were followed up.Conclusions The preoperative diagnosis rate of HD accompanying with thyroid cancer is low and great attention should be paid to its diagnosis.For HD patients,if carcinoma can not be excluded,surgical exploration is recommended.Appropriate surgical method should be chosen according to intraoperative frozen section results.Postoperative thyroid hormone treatment is usually taken.
10.In vivo killing effects of nanosecond pulsed electric fields on mouse breast cancer
Yi LIU ; Zhixiao XUE ; Chao WANG ; Haixia ZHANG ; Donghao LV
International Journal of Biomedical Engineering 2015;(3):165-167,171
Objective To explore the in vivo killing effects of nanosecond pulsed electric fields on mouse breast cancer in tumor bearing BALB/c mice. Methods Twenty four BALB/c mice models with subcutaneous EMT-6 breast cancer were prepared and divided into experimental group and control group (n=12). In experimental group, the mice were treated by the pulsed electric fields with peak voltage of 700 V/cm, rise times of 57 ns, durations of 70μs and duty ratio of 50%on the tumor tissue with two parallel electrodes under anaesthesia. One hundred pulses were given and the energy was just 9.75 J with effective action period of 7 ms. Tumor volume, animal weight and histopathologic changes after 1, 3, 5 and 7 d were observed after irreversible electroporation. Results The tumor volume in experimental group increased more slowly than that in control group, especially at the 1-3 d after treatment with a standstill. Histopathological examination results showed that the tumor tissue had obvious coagulation necrosis and tissue edema after electrical stimulation treatment, and mass vacuole like structure appeared in tumor tissue from the third day after treatment and vascular injury occurred at the early stage. Conclusions In the given field conditions, steep pulsed electric field has inhibitory effect on tumor growth. In order to achieve more ideal tumor therapy effect, further studies on steep pulse dose are needed.