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Dazhang Wang

Publications and source records attributed to Dazhang Wang.

15 recordsLinked to original sources
PubMed2004

[A biomechanic study on the relapse after sagittal split and oblique osteotomy of Ramus].

The relapse after orthognathic surgery was frequently reported in recent years. But up to now researches concerning bio-mechanic mechanism of relapse are rare. The purpose of this study, by imitating the operation on monkeys, was to examine the biomechanical properties and histological characteristics after operation in order to investigate the mechanism of the relapse after orthognathic surgery. 20 rhesus monkeys divided into two groups were subjected to bilateral sagittal split and oblique osteotomy, respectively. The broken strength, stress and strain of the operated sites were examined with the use of biomechanical methods, and the healing scab was observed using histological method and SEM at 3, 6, 12, 24 weeks after operation. The results obtained demonstrated that bone healing and biomechanical properties reached certain level after 6 to 12 weeks' recovery in both operation groups; the biomechanical properties and histological characteristics recovered faster in sagittal split group than in oblique osteotomy group. Histological examination also demonstrated similar results. From the data above it is suggested that the higher relapse rate in sagittal split may more closely related to the mechanical effect different from the scab healing, although 8 weeks' fixation may meet the requirement of clinical treatment, accessory fixation method should be adopted after the removal of inter-maxilla fixation.

Animals↗
PubMed2003

[The clinical application and evaluation of combined chemotherapy in comprehensive treatment for oral squamous cell carcinoma].

OBJECTIVE: To study and evaluate the clinical effects of combined preoperative chemotherapy and their relations with multi drug resistance (MDR). METHODS: 102 cases with oral squamous cell carcinoma(OSCC) were included in the study (63 males and 39 females, aged 22 to 67 years). Among the subjects there were 57 cases with cancer of tongue and 45 cases with cancer of buccal mucosa. 27 cases in the group were classified as stage II, 55 as stage III and 20 cases as stage IV according to TNM standard. All cases accepted PYM + 5-Fu + DDP combined chemotherapy pre-operatively. The total given dose was PYM 48 mg, 5-Fu 7.5 g and DDP 300 mg. After the chemotherapy, radical surgery were performed within 2 weeks. The diagnosis of all cases were proved as OSCC by biopsy. RESULTS: Total effective rate of the combined chemotherapy was 82.4%. All of the cases were followed up and their 3 years' survival rate was 67.6%. CONCLUSION: The combined chemotherapy of PYM + 5-Fu + DDP is effective in using as one of comprehensive treatment for OSCC.

Adult↗
PubMed2003

[Reversal effect of hyperthemia on multidrug resistant phenomena].

OBJECTIVE: The purpose of this study was investigate the effect of hyperthemia on multidrug resistance in K562/ADM cell. METHODS: The MDR1 (mulitdrug resistance gene) and MRP (multidrug resistant associated gene) gene expressions in Tca8113 and K562/ADM cell lines were analyzed by RT-PCR after treated with different cytotoxic drugs and different temperature (37 degrees C and 41 degrees C). The function and expression of Pgp and MRP were detected by fluorescence photometeric assays. RESULTS: Inhibition rate of both cells was significantly enhanced by exposure to chemotherapeutic drugs and 41 degrees C temperature; Exposing to 41 degrees C hyperthemia reduced MDR1 and MRP expression and enhanced intracellular drug concentration as well in K562/ADM. CONCLUSION: 41 degrees C hyperthemia could effectively enhance the inhibition rate of chemotherapeutic drugs and partially reverse the multidrug resistance. It is suggested that hyperthemia could be used as a method to overcome multidrug resistance.

Antineoplastic Agents↗
PubMed2003

Temporospatial expression of vascular endothelial growth factor and basic fibroblast growth factor during mandibular distraction osteogenesis.

OBJECTIVE: Distraction osteogenesis is a vascular-dependent process. This study investigated expression patterns of two major angiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), in the distracted calluses following mandibular lengthening in a goat model. MATERIAL AND METHODS: Bilateral mandibular osteotomies were performed in 15 young adult goats. After a latency of 7 days, the mandibles were elongated using custom-made distractors with a rate of 1 mm/day for 10 days. Three animals each were sacrificed at the end of the delay phase, at 0, 7, 14, and 28 days after completion of distraction, respectively. The lengthened mandibles were harvested and processed for histological and immunohistochemical examinations. RESULTS: Elevated cellular expression of VEGF and bFGF, with neovascularization in the distraction gap, was observed following mandibular lengthening. VEGF staining was noted in the endothelial cells and osteoblasts. bFGF staining was seen in the fibroblast-like cells, osteoblasts and immature osteocytes. Their strongest expression was found 0-7 days after the end of distraction, and declined with maturation of the newly formed bone. CONCLUSION: A temporal and spatial expression pattern of VEGF and bFGF was found during distraction osteogenesis in goat mandibles. It suggests that distraction forces can stimulate the production of VEGF and bFGF, which contribute to neovascularization and new bone formation during gradual distraction of the mandible. Application of angiogenic factors may be considered as a potential method to enhance angiogenesis and osteogenesis in osteodistraction, especially in sites without enough vascularization.

Animals↗
PubMed2003

[Clinical characters, diagnosis and treatment of parapharyngeal region neoplasms: a report of 115 cases].

OBJECTIVE: The aim of this study was to analyze the clinical characters, diagnosis and treatment of primary neoplasms in the parapharyngeal regions. METHODS: A total of 115 cases of primary neoplasms in the parapharyngeal regions were included in this study. RESULTS: Disorders of swallowing, breath or speaking were the common symptoms of neoplasms in parapharyngeal regions. The majority of neoplasms parapharyngeal regions were benign. 46 cases were from the deep lobe of the parotid, and 42 cases were neurogenic. CT or MRI provides useful information such as their sizes, shapes and extents. The relationship between the tumor and vessel was shown using super-selective angiography. All the tumors were resected completely by extra-oral approach through the posteroinferior incision of the mandible. The follow-up was carried out from 1 to 10 years, and the data indicated that 2 patients died, 18 cases were lost, and others had no recurrence. CONCLUSION: CT and/or MRI are essentially useful for diagnosis and presurgical planning. Super-selective angiography can be used if the lesions involved carotid artery. Posteroinferior incision of the mandible is a simple, effective and safe approach for excision of neoplasms parapharyngeal regions.

Adolescent↗
PubMed2003

[Induction of multidrug resistance in Tca8113 cells by transient exposure to different chemotherapeutic drugs].

OBJECTIVE: The purpose of this study was to determine the effect of transient exposure to chemotherapeutic drugs on multidrug resistance of Tca8113 cells. METHODS: The MDR1 and MRP gene expressions in Tca8113 and K562/ADM cells lines were analyzed using reverse transcription polymerase chain reaction (RT-PCR), after the cells were treated with different cytotoxic drugs. The function and expressions of P-glycoprotein 170 and multidrug resistant associated protein were studied using fluorescence photometric assays. RESULTS: The inhibitive rate of Tca8113 cells was higher than that of K562/ADM, after exposure to chemotherapeutic drugs. The transient exposure to cytotoxic drugs weakly induced MDR1 and multidrug resistant associated protein expression in Tca8113 cells. The intracellular drug concentration in K562/ADM was lower than that in Tca8113 cells. CONCLUSION: Induction of MDR1 and multidrug resistant associated protein gene expression response to cytotoxic drugs may be related with the increased multidrug resistance in drug-treated human tumor cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

[Regulation of XW630 on estrogen receptor messenger RNA expression in osteoblasts].

This study was performed to investigate the mechanism of an anti-osteoporosis new drug XW630 for promoting the osteogenic action. Osteoblast clone was cultivated from SD adult rat calvaria in vitro, the estrogen receptor messenger RNA(ERmRNA) expression in the osteoblasts of rats was detected directly with high-sensitive RT-PCR firstly. The results indicated that XW630 can significantly promote ERmRNA expression in osteoblasts in the time-dependent manner. Being superior to other two kinds of estrogen in the same concentration (10(-6) mol/L), XW630 probably plays an important role in the bone pathogenesis by means of ER gene regulatory functions.

Animals↗
PubMed2003

[Effects of dexamethasone and vitamin B12 on EGF, TGFalpha, and TGFbeta1 gene expressions of A/J mouse palatal cells in vitro].

OBJECTIVE: To investigate the molecular mechanism of congenital cleft palate induced by Dexamethasone (DEX) and the counteractive effect of Vitamin B12. METHODS: The RT-PCR was used to detect the independent and joint effects of DEX and Vitamin B12 on the gene expressions of A/J embryonic mouse palatal cells. RESULTS: DEX stimulated the gene expressions of EGF and TGFbeta1, while the expression of TGFalpha left unchanged in the palatal cells. Vitamin B12 had no direct effects on the gene expressions of EGF, TGFalpha, and TGFbeta1; however, it counteracted the effects of DEX on the palate cells. CONCLUSION: DEX induces cleft palate through increasing some gene expressions of growth factors, which can be inhibited by Vitamin B12.

Animals↗
PubMed2002

Biomechanical properties of regenerated bone by mandibular distraction osteogenesis.

OBJECTIVE: To study the biomechanical properties of the new bone generated by mandibular distraction osteogenesis (DO). METHODS: A total of 11 healthy adult goats were randomly divided into 2 groups, the experimental group (n=9) and the control group (n=2). For the goats in the experimental group, the bilateral mandibles were gradually lengthened for 10 mm with distraction appliances. Three goats were sacrificed respectively at 2, 4 and 8 weeks after completion of distraction. Compressive, three-point bending and shearing tests were conducted on the standard regenerated bone samples and the whole unilateral mandibular specimens. For the goats in the cont rol group, no operation was made and the whole unilateral mandible was taken as the test specimen. RESULTS: The compressive strength and bending stiffness of the new bone reached the normal level at 4 and 8 weeks after completion of distraction, respectively. But the shearing strength remained significantly weaker than that of the controls at 8 weeks after distraction. CONCLUSIONS: The distraction appliance can be removed and the lengthened mandible should be exposed to adaptive functional exercise at 8 weeks after completion of distraction.

Animals↗
PubMed2002

[Study of XW630 in promoting estrogen receptor expression in ovariectomized rats].

We adopted firstly the dextran-coated charcoal(DCC) and SP methods to detect estrogen receptor (ER) expression of bone tissue in ovariectomized(OVX) rats. The results demonstrate that in OVX rats, XW630 can significantly promote ER expression in bone tissue and increase the ER content. XW630 is superior to estrone in effectiveness. The results also reveal that the ER expression in OVX rat bone tissue decreases with the lapse of time, indicating that the expression of ER depends on the existence of estrogen.

Animals↗
PubMed2002

[Distraction osteogenesis for repair of cleft palate: an experimental study].

OBJECTIVE: To observe the repair of cleft palate (CP) bone defect under the application of distraction osteogenesis (DO); to investigate the correction mechanism in thin bone of palatal shelf and to search a possible new treatment approach for repair of CP. METHODS: 14 cats were assigned randomly to 3 groups: (1) Empty control, 2 cats unoperated with euthanasia at the end of 2 weeks; (2) Experimental control, 2 cats underwent 8 mm x 18 mm palatal osteoectomy in saggital direction as the experimental model of CP with euthanasia in 6 weeks; (3) Experimental group, 10 cats were performed the same palatal osteoectomy as group (2), the newly designed and individual manufactured intraoral distractors were fixed to teeth by brackets and to bilateral palate bone across the defect with titanium miniscrews. 4 weeks later the transport disc (TD) osteotomy were performed and gradual distraction was started after 6 days latency period at the rate of 0.4 mm x 2/day till the TD reached the opposite edge of the CP. Roentgenographic, gross meterage and ultrastructural observation were performed 2, 4, 6, 8, 12 weeks after completion of distraction. RESULTS: All the examinations revealed the TD recombination to the opposite bone edge of the CP, simultaneously, the proportional expansion of overlay mucoperiosteal flap was achieved. The bone defect were filled with de move osteogenesis. Roentgenographically, the new bone mineralization was along the DO vector, developed from the bone cut edges bilaterally to the central translucent zone until turned to thin fissure. Comparison of the plaster casts showed no change in the occlusion or dentomaxillofacial framework. CONCLUSIONS: The intraoral distractor is able to get both effective distraction and steady fixation. The examination results suggest that the CP bone and soft tissue defect could be repaired and acheived functional reconstruction under DO, which could be a new treatment approach for repair of CP.

Animals↗
PubMed2002

[Effects of epidermal growth factors on the proliferation and metabolism of A/J mouse embryonic palatal cells].

OBJECTIVE: The purpose of this study was to investigate the effects of epidermal growth factors (EGFs) with different concentration on the OD, DNA, protein, and PGE2 of A/J mouse embryonic palatal shelves cells (A/J MEPC) isolated from embryonic palatal shelves. METHODS: The mouse embryonic palatal shelves cells were grown in different 39 pores (or bottles) with 9 gradient concentrations of EGF (0.005, 0.010, 0.050, 0.100, 0.500, 1.000, 5.000, 10.000, 50.000 ng/ml), and four pores were prepared for the same concentration, then the OD, DNA, protein and PGE2 of A/J MEPC were measured after 1 day, 3 days and 5 days. RESULTS: EGFs stimulated DNA and PGE2 synthesis of A/J MEPC, and augmented proliferation index (PIX). Their effects were very obvious in promoting the proliferation of A/J MEPC, when the concentration was 10.000 ng/ml. CONCLUSION: EGF may be important in regulating proliferation and metabolism of embryonic palatal shelves cells.

Animals↗
PubMed2002

[Distraction osteogenesis for the repair of cleft palate--an ultrastructural study].

OBJECTIVE: The aim of this study was to explore ultrastructural characters of the newly formed bone in the correction of cleft palate (CP) bone defect by distraction osteogenesis (DO). METHODS: The CP experimental animal models (12 cats) were established surgically, and were divided randomly into the experimental group (10 cats), in which the hard palate bone defects were corrected with DO procedure at the rate of 0.4 mm x 2/day. The specimen retrieval with euthanasia was carried out at 2, 4, 6, 8, 12 weeks after completion of distraction. Ultrastructural study was then performed; the experimental control group (2 cats) was kept for 6 weeks before euthanasia without any correction, the other extra 2 cats were used as the negative control. RESULTS: New bone formation appeared in early 2 weeks. Exclusively intramembranous bone formation was observed in all specimens. The remodeling activities were keep observed throughout the period of study, and the bone structure matured gradually till 12 weeks after the completion of DO. No repair was observed in experimental control group. CONCLUSION: The reconstruction of CP bone defect by means of DO could get active intramembranous bone formation and remodeling, which adapted to normal functional activities.

Animals↗
PubMed2002

[Characteristics of BMP expression and X-ray films in distraction osteogenesis for repair of cleft palate--an immunohistochemical and roentgenographic study].

OBJECTIVE: The purpose of this study was to observe the roentgenographic characters of distraction osteogenesis (DO) correction of cleft palate (CP), to study the expression of BMP proportional to fixation period time intervals, and to explore the new bone formation mechanism in Cleft Palate bone shelf. METHODS: 12 cats were used to establish the CP animal model surgically, and then were assigned randomly to (1) Experimental group (12 cats): CP defects were DO repaired at the rate and rhythm of 0.4 mm x 2/day. Specimen retrieval at 2, 4, 6, 8, 12 weeks after completion of distraction, roentgenography and Anti-BMP immunohistochemistry studies were performed; (2) Experimental control group (2 cats): CP defects without any treatment procedures, and (3) Empty control group of 2 cats. RESULTS: Anti-BMP immunohistochemistry study showed positive DAB dye in early 2 weeks and most extensively positive expression of BMP in 4 to 6 weeks. The expression of BMP wore off gradually through 8 to 12 weeks. The roentgenography showed that the newly mineralized bone was developed from the cut bone edges bilaterally to the central transparent zone, and the newly formed bone bridged the defect area completely at the end of the study. The CP bone defect was reconstructed and the distraction gap was filled with de nove osteogenesis. No new bone formation was observed in experimental control group. CONCLUSION: The process of new bone formation in the distraction area is dynamic. Being stimulated primarily, the process was kept highly active till quiescence phase finally. The X-ray examination shows that there is distinctively low roentgenopeque. Nevertheless, roentgenography is so far a very effective and convenient method to evaluate and monitor the DO correction efficiency.

Animals↗