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Biomedical subjects

Zheng Sun

Publications and source records attributed to Zheng Sun.

26 records · Page 2Linked to original sources
PubMed2005

Overexpression of 5-lipoxygenase and cyclooxygenase 2 in hamster and human oral cancer and chemopreventive effects of zileuton and celecoxib.

PURPOSE: Previous studies have suggested an important role of aberrant arachidonic acid metabolism, especially the cyclooxygenase (Cox) pathway, in oral carcinogenesis. However, it is unknown whether the 5-lipoxygenase (5-Lox) pathway contributes to oral carcinogenesis, and whether combination of inhibitors of both pathways may have synergistic or additive effects of chemoprevention. EXPERIMENTAL DESIGN: 5-Lox expression was examined in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster and human oral cancer tissues by immunohistochemistry, and Cox2 expression was investigated in hamster oral tissues using in situ hybridization. Zileuton (a specific 5-Lox inhibitor) and celecoxib (a specific Cox2 inhibitor), either alone or in combination, were investigated for their chemopreventive effects on the DMBA-induced hamster model at the post-initiation stage through topical application. RESULTS: 5-Lox was overexpressed during oral carcinogenesis in hamsters and humans, as well as Cox2 in the hamster tissues. In a chemoprevention study using the post-initiation DMBA model, incidence of hamster oral squamous cell carcinoma was reduced from 76.9% (20 of 26) to 45.8% (11 of 24, P < 0.05) and 32.1% (9 of 28, P < 0.01) by 3% and 6% topical zileuton, respectively; and to 57.6% (15 of 26, P > 0.05) and 50% (12 of 24, P < 0.05) by 3% and 6% topical celecoxib, respectively. When used in combination, celecoxib and zileuton (3% of each) had an additive inhibitory effect on the incidence of squamous cell carcinoma (36%, 9 of 25, P < 0.01). Other pathologic variables and the levels of leukotriene B4 and prostaglandin E2 of the hamster tissues were reduced as well. CONCLUSIONS: The results clearly showed that both 5-Lox and Cox2 played important roles in oral carcinogenesis. Zileuton and celecoxib prevented oral carcinogenesis at the post-initiation stage through their inhibitory effects on arachidonic acid metabolism.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2005

[The possibility of hepatitis B virus transmission through dental handpieces].

OBJECTIVE: To discuss the possibility of hepatitis B virus (HBV) transmission through dental handpieces. METHODS: Investigation was carried on methods for disinfecting and sterilizing dental handpieces and the condition of HBsAg contamination on dental handpieces before and after disinfection and sterilization by randomly sampling all special stomatological hospitals and dental clinics in a same city and 10 dental departments from the third, second and first class hospitals. The possibility of HBV transmission through dental handpieces was probed by investigating whether ducks can be infected by bath liquid of dental handpieces contaminated by DHBV, while in such bath liquid, DHBV can not be detected by serum dot hybridization. RESULTS: From 2001 to 2004, in methods to disposing dental handpieces, the use of autoclave was remarkably increased while of the disinfectant wipe, immersion and other methods was remarkably decreased. The positive rate of HBsAg from dental handpieces in practice was 1.65%. It was evident that the bath liquid of dental handpieces contaminated by DHBV can conduct infection in vivo test of duck, while DHBV can not be detected in such bath liquid by serum dot hybridization, it is proved that the negative result of HBsAg in non-sterilized dental handpieces can not eliminate the possibility of HBV transmission through dental handpieces. CONCLUSION: There might exist the possibility of HBV transmission through dental handpieces however, the autoclaves might kill the virus contaminating on dental handpieces.

Animals↗
PubMed2005

[Coronary artery motion estimation using X-ray cineangiogram].

This paper presents an approach for estimating the non-rigid motion of coronary arteries using digital angiographic images. Displacement vectors of vessel points are obtained by finding points correspondences in two successive frames. Smoothness of motion field and vessel deformation measurement are considered in matching, and unmatched regions are also dealt with in the fact that the vessel after deformation may have different size with its original station. The search strategy for optimal matching is carried out using dynamic programming (DP) so that computing cost is reduced. Results of this motion estimation method applied to synthetic and clinical images have shown that the method is accurate, with a root mean square error about one pixel for simulated data. For the case of actual X-ray coronary angiographic images, visual inspection of the detected pairs of points shows that the results are very encouraging.

Angiography, Digital Subtraction↗
PubMed2005

[Gene expression of epidermal growth factor and epidermal growth factor receptor in oral lichen planus].

OBJECTIVE: To explore the expression of epidermal growth factor (EGF), epidermal growth factor receptor (EGFR), c-fos and c-jun in oral lichen planus (OLP). METHODS: The levels of gene expression of EGF, EGFR, c-fos and c-jun were detected with reverse transcription-polymerase chain reaction (RT-PCR) in 10 cases of erosive OLP, 12 cases of reticular OLP and 9 cases of normal oral mucosa. Protein contents and distribution of EGF, EGFR, C-fos and C-jun were examined with immunohistochemical technique in different tissues. RESULTS: The endogenous levels of EGFR mRNA and protein in erosive OLP were (55.9 +/- 23.1)% and (71.1 +/- 10.1)%, respectively, and significantly higher than those in reticular OLP and normal oral mucosa. The mRNA contents of c-fos and c-jun were significantly higher in erosive OLP than in normal oral mucosa. The positive cell rates of c-fos and c-jun protein in erosive OLP were 1.3 and 1.5 times of those in normal oral mucosa, respectively (P < 0.05). CONCLUSIONS: The probability of carcinomatous change of erosive OLP might be higher than that of reticular OLP, in which EGF and EGFR might play an important role.

Adult↗
PubMed2004

[A new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique: a case report].

OBJECTIVE: To design and manufacture a new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique and explore a method to solve the necroses of allocartilage in hemi joint allotransplantation. METHODS: Design the new custom-made artificial articular cartilage of femoral condyle. The allograft and the patient distal femurs were scanned with Picker 6000 spiral computed tomography (CT) with 1.0 slice thickness and pitch of 1.5, reconstructed the distal femurs in Voxel Q image workstation with volume rendering technique. Then downloaded the transaxial 2D image data to personal computer at 0.1 mm interval and converted it into 2D digitized contour data by using image processing software developed by our team. The 3D wire frame and solid images of femoral condyle could be reconstructed when the 2D digitized contour data were input into image processing software Surfacer 9.0 (Imageware Company, USA). Subsequently based on the clinical experience and the need of design, the 3D contour image of articular cartilage was extracted from the surrounding. Based on the extracted 3D contour image, the computer-aided design (CAD) of the custom-made artificial articular cartilage was accomplished in Surfacer software, converted the CAD model into RP data format. Standard triangularization language, imported into the LPS600 rapid prototyping machine (Hengtong Company, Xi'an Jiaotong University, China), and the resin prototype was achieved. Then the resin model was used as a positive mould to build up a silica gel negative mould, the negative mould was sent to the factory to manufacture Ti-6Al-4V alloy articular cartilage through ordinary mould-melted founding process. Finally, the whole metal cartilage was completed after melting two special cages on it. A patient was selected to clinical applying. RESULTS: A new custom-made artificial articular cartilage of femoral condyle was made. It was press-fit well to the subchondral bone of the allograft bone. The patient's one and half year follow-up result was excellent. CONCLUSIONS: We design and manufacture a new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique. The result shows that the manufacturing process has the advantage of rapidness and precision that are very important for individualized artificial implant manufacturing. The artificial articular cartilage is press-fit well and could be a good idea to solve the necroses of allocartilage in hemijoint allotransplantation.

Adolescent↗
PubMed2004

[Current status of disinfection and sterilization for dental handpieces in the hospitals].

OBJECTIVE: To understand current status of the uses of dental handpieces, methods of disinfection and sterilization and their effectiveness in dental-care hospitals and out-patient departments of stomatology in general hospitals. METHODS: Ten dental-care hospitals and departments of stomatology in general hospitals at varied levels were randomly sampled during 2000 to 2001 to investigate the uses of dental handpieces and means of their disinfection and sterilization. One used dental handpiece from each hospital or department of stomatology in general hospital selected was detected for possible contamination of bacteria by aerobic bacterial count and Coliform bacterial examinations and hepatitis B surface antigen (HBsAg) on it, based on "The Technical Standards for Disinfection" set by the Ministry of Health of China, and the effectiveness of its disinfection and sterilization was evaluated as well. RESULTS: Anti-suction handpieces were used only in 5.9% of the hospitals or departments, 94.1% of them without anti-suction devices. Cleansing disinfection was applied for used dental handpieces in 62.9% of the dental-care hospitals and the departments of stomatology, with an effective rate of 26.17%, immersing disinfection in 10.0%, with an effective rate of 55.88%, and autoclave in 27.1%, with an effective rate of 80.43%. Used dental handpieces in the hospitals and departments of stomatology in general hospitals were all contaminated by bacteria and HBsAg could be detected in 1.67% of them. CONCLUSIONS: Dental handpieces without anti-suction should be replaced soon by those with it or comprehensive dental unit with anti-suction device should be used. Used dental handpieces must be sterilized effectively before next use. Awareness on prevention from cross-infection should be improved for dental-care professional staff and operation of sterilization should be standardized.

Cross Infection↗
PubMed2003

Distribution, levels, and activation of MEK1 in Alzheimer's disease.

Extracellular-signal-regulated kinase (ERK) has been implicated in the pathogenesis of Alzheimer's disease (AD), but the upstream cascade leading to ERK activation has not been elucidated. In this study, we focused on one of the physiological activators of ERK, mitogen-activated protein kinase (MAPK)/ERK kinase 1 (MEK1). Although there was no significant difference in the level and distribution of total MEK1 between AD and age-matched control cases, increased levels of activated phospho-MEK1 were specifically localized to neuronal intracytoplasmic granular structures in severe AD (Braak stage V-VI). The considerable overlap between MEK1 and its downstream effector, phospho-ERK, suggests both a functional and mechanistic link. Nuclear localization of phospho-MEK1 was a prominent feature in both mild AD cases (Braak stage III-IV) and control cases with limited pathology (Braak stage I-II). Since MEK1 is normally cytoplasmic due to the active export from nucleus because of the presence of nuclear export signal in its amino-terminus, we suspect that the apparent nuclear accumulation of phospho-MEK1 in AD patients at early stages suggests that abnormal nuclear trafficking may contribute to the pathogenesis of AD. By immunoblot analyses, phospho-MEK1 was significantly increased in AD over control cases. Together, these findings lend further credence to the notion that the ERK pathway is dysregulated in AD and also indicate an active role for this pathway in disease pathogenesis.

Active Transport, Cell Nucleus↗