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92篇 您的检索式:作者名="Cheng HK"
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1Effects of quaternary ammonium chain length on the antibacterial and remineralizing effects of a calcium phosphate nanocomposite显示文摘Composites containing nanoparticles of amorphous calcium phosphate(NACP)remineralize tooth lesions and inhibit caries.A recent study synthesized quaternary ammonium methacrylates(QAMs)with chain lengths(CLs)of 3–18 and determined their effects on a bonding agent.This study aimed to incorporate these QAMs into NACP nanocomposites for the first time to simultaneously endow the material with antibacterial and remineralizing capabilities and to investigate the effects of the CL on the mechanical and biofilm properties.Five QAMs were synthesized:DMAPM(CL3),DMAHM(CL6),DMADDM(CL12),DMAHDM(CL16),and DMAODM(CL18).Each QAM was incorporated into a composite containing 20%NACP and 50%glass fillers.A dental plaque microcosm biofilm model was used to evaluate the antibacterial activity.The flexural strength and elastic modulus of nanocomposites with QAMs matched those of a commercial control composite(n 5 6;P.0.1).Increasing the CL from 3 to 16 greatly enhanced the antibacterial activity of the NACP nanocomposite(P,0.05);further increasing the CL to 18 decreased the antibacterial potency.The NACP nanocomposite with a CL of 16 exhibited biofilm metabolic activity and acid production that were 10-fold lesser than those of the control composite.The NACP nanocomposite with a CL of 16 produced 2-log decreases in the colony-forming units(CFU)of total microorganisms,total streptococci,and mutans streptococci.In conclusion,QAMs with CLs of 3–18 were synthesized and incorporated into an NACP nanocomposite for the first time to simultaneously endow the material with antibacterial and remineralization capabilities.Increasing the CL reduced the metabolic activity and acid production of biofilms and caused a 2-log decrease in CFU without compromising the mechanical properties.Nanocomposites exhibiting strong anti-biofilm activity,remineralization effects,and mechanical properties are promising materials for tooth restorations that inhibit caries.Ke Zhang Lei Cheng Michael D Weir Yu-Xing Bai Hockin HK Xu 2016International Journal of Oral Science2016,8,1:13
2A novel protein-repellent dental composite containing 2-methacryloyloxyethyl phosphorylcholine显示文摘Secondary caries due to biofilm acids is a primary cause of dental composite restoration failure.To date,there have been no reports of dental composites that can repel protein adsorption and inhibit bacteria attachment.The objectives of this study were to develop a protein-repellent dental composite by incorporating 2-methacryloyloxyethyl phosphorylcholine(MPC) and to investigate for the first time the effects of MPC mass fraction on protein adsorption,bacteria attachment,biofilm growth,and mechanical properties.Composites were synthesized with 0(control),0.75%,1.5%,2.25%,3%,4.5%and 6%of MPC by mass.A commercial composite was also tested as a control.Mechanical properties were measured in three-point flexure.Protein adsorption onto the composite was determined by the microbicinchoninic acid method.A human saliva microcosm biofilm model was used.Early attachment at 4 h,biofilm at 2 days,live/dead staining and colony-forming units(CFUs) of biofilms grown on the composites were investigated.Composites with MPC of up to 3%had mechanical properties similar to those without MPC and those of the commercial control,whereas 4.5%and 6%MPC decreased the mechanical properties(P<0.05).Increasing MPC from 0 to 3%reduced the protein adsorption on composites(P<0.05).The composite with 3%MPC had protein adsorption that was 1/12 that of the control(P<0.05).Oral bacteria early attachment and biofilm growth were also greatly reduced on the composite with 3%MPC,compared to the control(P<0.05).In conclusion,incorporation of MPC into composites at 3%greatly reduced protein adsorption,bacteria attachment and biofilm CFUs,without compromising mechanical properties.Protein-repellent composites could help to repel bacteria attachment and plaque build-up to reduce secondary caries.The protein-repellent method might be applicable to other dental materials.Ning Zhang Chen Chen Mary AS Melo Yu-Xing Bai Lei Cheng Hockin HK Xu 2015International Journal of Oral Science2015,7,2:8
3One-year water-ageing of calcium phosphate composite containing nano-silver and quaternary ammonium to inhibit biofilms显示文摘Dental composites are commonly used restorative materials; however, secondary caries due to bio?lm acids remains a major problem. The objectives of this study were(1) to develop a composite containing quaternary ammonium dimethacrylate(QADM),nanoparticles of silver(NAg), and nanoparticles of amorphous calcium phosphate(NACP), and(2) to conduct the ?rst investigation of the mechanical properties, bio?lm response and acid production vs water-ageing time from 1 day to 12 months.A 4 × 5 design was utilized, with four composites(NACP-QADM composite, NACP-NAg composite, NACP-QADM-NAg composite,and a commercial control composite), and ?ve water-ageing time periods(1 day, and 3, 6, 9, and 12 months). After each waterageing period, the mechanical properties of the resins were measured in a three-point ?exure, and antibacterial properties were tested via a dental plaque bio?lm model using human saliva as an inoculum. After 12 months of water-ageing, NACP-QADMNAg had a ?exural strength and elastic modulus matching those of the commercial control(P40.1). Incorporation of QADM or NAg into the NACP composite greatly reduced bio?lm viability, metabolic activity and acid production. A composite containing both QADM and NAg possessed a stronger antibacterial capability than one with QADM or NAg alone(Po0.05). The anti-bio?lm activity was maintained after 12 months of water-ageing and showed no signi?cant decrease with increasing time(P40.1). In conclusion, the NACP-QADM-NAg composite decreased bio?lm viability and lactic acid production, while matching the loadbearing capability of a commercial composite. There was no decrease in its antibacterial properties after 1 year of water-ageing.The durable antibacterial and mechanical properties indicate that NACP-QADM-NAg composites may be useful in dental restorations to combat caries.Lei Cheng Ke Zhang Chen-Chen Zhou Michael D Weir Xue-Dong Zhou Hockin HK Xu 2016International Journal of Oral Science2016,8,3:8
4Effect of anti-biofilm glass–ionomer cement on Streptococcus mutans biofilms显示文摘Dental restorative materials with antimicrobial properties can inhibit bacterial colonization, which may result in a reduction of caries at tooth-filling interaction zones. This study aimed to develop antibacterial glass–ionomer cements(GIC) containing a quaternary ammonium monomer(dimethylaminododecyl methacrylate, DMADDM), and to investigate their effect on material performance and antibacterial properties. Different mass fractions(0, 1.1% and 2.2%) of DMADDM were incorporated into the GIC. The flexure strength, surface charge density, surface roughness and fluoride release were tested. A Streptococcus mutans biofilm model was used. Exopolysaccharides(EPS) staining was used to analyze the inhibitory effect of DMADDM on the biofilm matrix. In addition, biofilm metabolic activity, lactic acid metabolism and the expression of glucosyltransferase genes gtf B, gtf C and gtf D were measured. GIC containing 1.1% and 2.2% DMADDM had flexural strengths matching those of the commercial control(P40.1). DMADDM was able to increase the surface charge density but reduced surface roughness(Po0.05). The incorporation of 1.1% and 2.2% DMADDM elevated the release of fluoride by the GIC in the first 2 days(Po0.05). The novel DMADDM-modified GIC significantly reduced biofilm metabolic activity(Po0.05) and decreased lactic acid production(Po0.05). The quantitative polymerase chain reaction(q PCR) results showed that the expression of gtf B, gtf C and gtf D decreased when mass fractions of DMADDM increased(Po0.05). EPS staining showed that both the bacteria and EPS in biofilm decreased in the DMADDM groups. The incorporation of DMADDM could modify the properties of GIC to influence the development of S. mutans biofilms. In this study, we investigated the interface properties of antibacterial materials for the first time. GIC containing DMADDM can improve material performance and antibacterial properties and may contribute to the better management of secondary caries.Su-Ping Wang Yang Ge Xue-Dong Zhou Hockin HK Xu Michael D Weir Ke-Ke Zhang Hao-Hao Wang Matthias Hannig Stefan Rupf Qian Li Lei Cheng 2016International Journal of Oral Science2016,8,2:5
5Primer containing dimethylaminododecyl methacrylate kills bacteria impregnated in human dentin blocks显示文摘Antibacterial dimethylaminododecyl methacrylate(DMADDM) was recently synthesized. The objectives of this study were to:(1)investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and(2) compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate(QADM).Scotchbond Multi-Purpose(SBMP) bonding agent was used. DMADDM and QADM were mixed into SBMP primer. Six primers were tested: SBMP control primer P, P+2.5% DMADDM, P+5% DMADDM, P+7.5% DMADDM, P+10% DMADDM, and P+10% QADM.S. mutans were impregnated into human dentin blocks, and each primer was applied to dentin to test its ability to kill bacteria in dentinal tubules. Bacteria in dentin were collected via a sonication method, and the colony-forming units(CFU) and inhibition zones were measured. The bacterial inhibition zone of P+10% DMADDM was 10 times that of control primer(Po0.05). CFU in dentin with P+10% DMADDM was reduced by three orders of magnitude, compared with control. DMADDM had a much stronger antibacterial effect than QADM, and antibacterial efficacy increased with increasing DMADDM concentration. Dentin shear bond strengths were similar among all groups(P40.1). In conclusion, antibacterial DMADDM-containing primer was validated to kill bacteria inside dentin blocks, possessing a much stronger antibacterial potency than the previous QADM. DMADDM-containing bonding agent was effective in eradicating bacteria in dentin, and its efficacy was directly proportional to DMADDM mass fraction. Therefore, DMADDM may be promising for use in bonding agents as well as in other restorative and preventive materials to inhibit bacteria.Chen Chen Lei Cheng Michael D Weir Nancy J Lin Sheng Lin-Gibson Xue-Dong Zhou Hockin HK Xu 2016International Journal of Oral Science2016,8,4:4
6Quaternary ammonium-induced multidrug tolerant Streptococcus mutans persisters elevate cariogenic virulence in vitro显示文摘Dental caries are the most prevalent chronic infections in the oral cavity, and Streptococcus mutans acts as the main cariogenic bacterial species. Antibacterial quaternary ammonium compounds(QAs) have been developed to preve Fnt or treat dental caries.However, there is no report on the tolerance of S. mutans to QAs. In this study, we investigated the development of S. mutans persistence induced by a novel dental caries defensive agent, dimethylaminododecyl methacrylate(DMADDM), for the first time.Typical biphasic killing kinetics for persisters were observed in both S. mutans planktonic and biofilm cultures challenged by DMADDM at concentrations of 20 and 200 μg·m L^(-1), respectively. The persisters tolerated six other antibiotics with different antibacterial mechanisms, while only daptomycin and vancomycin could slightly reduce the persister numbers in planktonic cultures. The distribution of persisters in DMADDM-treated biofilms was similar to that in the untreated control, except that the total biomass and biofilm height were significantly reduced. A higher exopolysaccharides(EPS):bacteria ratio was observed in DMADDM-treated biofilms. Persisters in biofilms significantly upregulated gtf gene expression, indicating an increase in the bacteria's ability to produce EPS and an elevated capability of cariogenic virulence. Carbon source metabolism was significantly reduced, as related metabolic genes were all downregulated in persisters. Concentrations of 0.1 m M, 1 m M and 10 m M of extra glucose significantly reduced the number of persisters both in planktonic and biofilm conditions. The formation of noninheritable and multidrug tolerant persisters induced by DMADDM suggested that drug tolerance and new persistent eradication strategies should be considered for oral antibacterial agents.Ya-Ling Jiang Wei Qiu Xue-Dong Zhou Hao Li Jun-Zhuo Lu Hockin HK Xu Xian Peng Ming-Yun Li Ming-Ye Feng Lei Cheng Biao Ren 2017International Journal of Oral Science2017,9,4:2
7Molecular analysis of microdissected de novo glioblastoma and paired astrocytid tumors 显示文摘Cheng Y Ng HK Ding M 1999J Neuropathol Exp Neurol1999,58,:1
8Depigmentation effect of Kadsuralignan F on Melan-A murine melanocytes and human skin equivalents 显示文摘Goh M J Lee HK Cheng L 2013Int J Mol Sei2013,14,1:1
9Recommendations are needed for adolescent and adult pertussis immunization: rationale and strategies for consideration 显示文摘Campins-Marti M Cheng HK Forsyth K 2001Vaccine2001,20,56:1
10Transvenous embalization of dural carotid cavernous fistulae with transfacial catheterization through the superior ophthalmic vein 显示文摘Yu SC Cheng HK Wong GK 2007Neurosurgery2007,60,:1
11Upper aerodigestive tract squelac in severe enterovirus 71 infection:Predictors and outcome显示文摘Tsou YA Cheng YK Chung HK 2008Int J Pediatric Otorhinolaryngol2008,72,1:1
12Identification of genes expressed in the epithelium of porcine oviduct containing early embryos at various stages of development显示文摘Chang HS Cheng WT Wu HK 2000Mol Reprod Dev2000,56,3:1
13Quantitative nanoproteomics for protein complexes (QNanoPX) related to estrogen transcriptional action显示文摘Cheng PC Chang HK Chen SH 2010Mol Cell Proteomics2010,9,2:1
14Angioplasty and stenting for intracranial atherosclerotic stenosis: position statement of the Hong Kong Society of Interventional and Therapeutic Neuroradiology显示文摘Yu SC Cheng HK Cheng PW 2013Hong Kong Med J2013,19,1:1
15IsdA and IsdB antibodies protect mice against Staphylococcus aureus abscess formation and lethal challenge显示文摘Kim HK DeDent A Cheng AG 2010Vaccine2010,28,38:1
16Pilocytic astrocytomas do not show most of genetic changes commonly seen in diffuse astrocytoms显示文摘Cheng Y Pang JCS Ng HK 2000Histopathology2000,37,5:1
17Recommendations are needed for adolescent and adult pertussis immunization:rationale and strategies for consideration显示文摘Campins-Martí M Cheng HK Forsyth K 2001Vaccine2001,20,:1
18New testing approach in HLA genotyping helps overcome harriers in effective clinical practice 显示文摘Cheng SH Kwan P Ng HK 2009Clin Chem2009,55,8:1
19Decoy receptor 3 attenuates col- lagen induced arthritisby modulating T cell activation and B cell expansion显示文摘Cheng CP Sytwu HK Chang DM 2011J Rheumatol2011,38,12:1
20Upper aerodiges- tive tract sequelae in severe enterovirus 71 infection: pre- dictors and outcome 显示文摘Tsou YA Cheng YK Chung HK 2008Int J Pediatr Otorhinolaryngol2008,72,1:1
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