OBJECTIVE To develop an in vitro airway epithelial cell model suitable for the large-scale studies of compounds that can suppress lipopolysaccharide(LPS)-and tumor necrosis factor alpha(TNFα)-induced airway inflammat...OBJECTIVE To develop an in vitro airway epithelial cell model suitable for the large-scale studies of compounds that can suppress lipopolysaccharide(LPS)-and tumor necrosis factor alpha(TNFα)-induced airway inflammation.METHODS We have optimized the protocols to culture BEAS-2B,a normal human bronchial epithelial cell line,in glass-bottom 384-well microtiter plates.The cells were stimulated with TNFαand LPS from Pseudomonas aeruginosa,a common lunginfection pathogen in cystic fibrosis and chronic obstructive pulmonary disease.We used ELISA to measure the secretion levels of two pro-inflammatory cytokines,interleukin(IL)-6and-8,after 0,4,8,16,24 hof stimulation;and immunofluorescence microscopy to measure the nuclear translocation of RelA,a subunit of the NF-κB complex,after 0,15,30,60,120 min of stimulation.To suppress the inflammatory response,we pre-treated the cells with a specific IκB kinase-2inhibitor,TPCA-1;the main bioactive component of Andrographis paniculata,andrographolide;and DMSO control for 1h.RESULTS We found that individual stimulant(either TNFα10ng·mL-1 or LPS 10μg·mL-1)increased the IL-6and IL-8 secretion levels by^12-17 foldsas compared to DMSO controls after 8h of stimulation.The combined stimulation(10ng·mL-1 TNFαand 10μg·mL-1 LPS)induced even higher IL-6 and -8 levels(~18-21 folds)at the same time points.Importantly,our imaging study shows that the NF-κB activation is early but transient under TNFαstimulation,late but sustained under LPS stimulation,and early and sustained under the combined stimulation.Finally,we also found that TPCA-1 10μmol·L-1 or andrographolide 30μmol·L-1 drastically reduced the IL-6 and -8 levels down to 4.5-9 folds as compared to the controls.CONCLUSIONThe combined TNFαand LPS stimulations induce faster and more sustained inflammatory responses,which can still be suppressed by anti-inflammatory compounds in our cell model.These more comprehensive activations of inflammatory signaling pathways will enable us to study and distinguish the mechanisms of different anti-inflammatory compounds or natural products.展开更多
Surface enhanced Raman scattering(SERS)is an efficient technique to detect low concentration molecules.In this work,periodical silicon nanowires(Si NWs)integrated with metal-insulator-metal(MIM)layers are employed as ...Surface enhanced Raman scattering(SERS)is an efficient technique to detect low concentration molecules.In this work,periodical silicon nanowires(Si NWs)integrated with metal-insulator-metal(MIM)layers are employed as SERS substrates.Laser interference lithography(LIL)combined with reactive ion etching(RIE)is used to fabricate large-area periodic nanostructures,followed by decorating the MIM layers.Compared to MIM disks array on Si surface,the SERS enhancement factor(EF)of the MIM structures on the Si NWs array can be increased up to 5 times,which is attributed to the enhanced electric field at the boundary of the MIM disks.Furthermore,high density of nanoparticles and nanogaps serving as hot spots on sidewall surfaces also contribute to the enhanced SERS signals.Via changing the thickness of the insulator layer,the plasmonic resonance can be tuned,which provides a new localized surface plasmon resonance(LSPR)characteristic for SERS applications.展开更多
OBJECTIVE Platinum compounds such as cisplatin and carboplatin are frequently used as the first-line chemotherapy for the treatment of the head and neck squamous cell carcinoma(HNSCC).In the present study,we investiga...OBJECTIVE Platinum compounds such as cisplatin and carboplatin are frequently used as the first-line chemotherapy for the treatment of the head and neck squamous cell carcinoma(HNSCC).In the present study,we investigated whether garcinol,apolyisoprenylated benzophenone can chemosensitize HNSCC to cisplatin.METHODS The effect of garcinol and cisplatin on HNSCC was assessed by MTT,Western blotting,real time PCR,FACS,immunohistochemistry,DNA binding assay and xenograft mouse model.RESULTS We found that garcinol inhibited the viability of a panel of diverse HNSCC cell lines,enhanced the apoptotic effect of cisplatin,suppressed constitutive as well as cisplatin-induced NF-κB activation,and downregulated the expression of various oncogenic gene products(cyclin D1,Bcl-2,survivin and VEGF).In vivo study showed that administration of garcinol alone(0.5 mg·kg-1,ip five times/week)significantly suppressed the growth of the tumor,and this effect was further increased by cisplatin.Both the markers of proliferation index(Ki-67)and microvessel density(CD31)were downregulated in tumor tissues by the combination of cisplatin and garcinol.The pharmacokinetic results of garcinol indicated that good systemic exposure was achievable after ip administration of garcinol at 0.5and 2mg·kg-1 with mean peak concentration(cmax)of 1825.4 and 6635.7nmol·L-1 in the mouse serum,respectively.CONCLUSION Overall,our results suggest that garcinol can indeed potentiate the effects of cisplatin by negative regulation of various inflammatory and proliferative biomarkers.展开更多
OBJECTIVE To establish a small compound library via a versatile synthetic route for the investigation of natural-inspiring compounds containing N-hydroxypyridones motif as potential anti-plasmodial,anti-bacterial and ...OBJECTIVE To establish a small compound library via a versatile synthetic route for the investigation of natural-inspiring compounds containing N-hydroxypyridones motif as potential anti-plasmodial,anti-bacterial and iron(Ⅱ)-chelating agents.METHODS An amidation/cyclization approach was adopted to synthesize a library of N-hydroxyquinolinones.The anti-plasmodial susceptibility of lab clone 3D7 P.falciparum was measured using aprotocol modified from the WHO microtest.The minimum bactericidal concentration(MBC)values were determined against Escherichia coli and Staphylococcus arueus.Nine compounds were selected to test their iron(Ⅱ)-chelating abilities.The iron(Ⅱ)-chelating ability was determined by measuring the absorbance of ferrozine-iron complex at 562 nm.RESULTS A new route for the facile synthesis of a library of N-hydroxyquinolinones based on one-pot palladium catalyzed C-N amidation/dehydrocyclizationsequence was implemented.Four compounds show anti-plasmodial activities with the range of 1.1-1.4μmol·L-1,50% chelation abilities of the nine selected compounds were shown to be 0.24-0.29mmol·L-1.CONCLUSION Alibrary of N-hydroxyquinolinones was synthesized via a novel synthetic route.The anti-plasmodial and anti-bacterial activities of these compounds were evaluated.Four compounds show potent anti-plasmodial activities Nine compounds were examined for their propensities to undergo iron chelation and these compounds were shown to be promising iron(Ⅱ)chelators as compared to EDTA.展开更多
In this paper, methods are proposed and validated to determine low and high thresholds to segment out gray matter and white matter for MR images of different pulse sequences of human brain. First, a two-dimensional re...In this paper, methods are proposed and validated to determine low and high thresholds to segment out gray matter and white matter for MR images of different pulse sequences of human brain. First, a two-dimensional reference image is determined to represent the intensity characteristics of the original three-dimensional data. Then a region of interest of the reference image is determined where brain tissues are present. The non-supervised fuzzy c-means clustering is employed to determine: the threshold for obtaining head mask, the low threshold for T2-weighted and PD-weighted images, and the high threshold for T1-weighted, SPGR and FLAIR images. Supervised range-constrained thresholding is employed to determine the low threshold for T1-weighted, SPGR and FLAIR images. Thresholding based on pairs of boundary pixels is proposed to determine the high threshold for T2-and PD-weighted images. Quantification against public data sets with various noise and inhomogeneity levels shows that the proposed methods can yield segmentation robust to noise and intensity inhomogeneity. Qualitatively the proposed methods work well with real clinical data.展开更多
基金The project supported by National Medical Research Council Cooperative Basic Research Grant(CBRG11nov032)the Bioinformatics Institute,Biomedical Research Council,A*STAR,Singapore
文摘OBJECTIVE To develop an in vitro airway epithelial cell model suitable for the large-scale studies of compounds that can suppress lipopolysaccharide(LPS)-and tumor necrosis factor alpha(TNFα)-induced airway inflammation.METHODS We have optimized the protocols to culture BEAS-2B,a normal human bronchial epithelial cell line,in glass-bottom 384-well microtiter plates.The cells were stimulated with TNFαand LPS from Pseudomonas aeruginosa,a common lunginfection pathogen in cystic fibrosis and chronic obstructive pulmonary disease.We used ELISA to measure the secretion levels of two pro-inflammatory cytokines,interleukin(IL)-6and-8,after 0,4,8,16,24 hof stimulation;and immunofluorescence microscopy to measure the nuclear translocation of RelA,a subunit of the NF-κB complex,after 0,15,30,60,120 min of stimulation.To suppress the inflammatory response,we pre-treated the cells with a specific IκB kinase-2inhibitor,TPCA-1;the main bioactive component of Andrographis paniculata,andrographolide;and DMSO control for 1h.RESULTS We found that individual stimulant(either TNFα10ng·mL-1 or LPS 10μg·mL-1)increased the IL-6and IL-8 secretion levels by^12-17 foldsas compared to DMSO controls after 8h of stimulation.The combined stimulation(10ng·mL-1 TNFαand 10μg·mL-1 LPS)induced even higher IL-6 and -8 levels(~18-21 folds)at the same time points.Importantly,our imaging study shows that the NF-κB activation is early but transient under TNFαstimulation,late but sustained under LPS stimulation,and early and sustained under the combined stimulation.Finally,we also found that TPCA-1 10μmol·L-1 or andrographolide 30μmol·L-1 drastically reduced the IL-6 and -8 levels down to 4.5-9 folds as compared to the controls.CONCLUSIONThe combined TNFαand LPS stimulations induce faster and more sustained inflammatory responses,which can still be suppressed by anti-inflammatory compounds in our cell model.These more comprehensive activations of inflammatory signaling pathways will enable us to study and distinguish the mechanisms of different anti-inflammatory compounds or natural products.
基金financial support from A*STAR,SERC 2014 Public Sector Research Funding (PSF) Grant (SERC Project No. 1421200080)
文摘Surface enhanced Raman scattering(SERS)is an efficient technique to detect low concentration molecules.In this work,periodical silicon nanowires(Si NWs)integrated with metal-insulator-metal(MIM)layers are employed as SERS substrates.Laser interference lithography(LIL)combined with reactive ion etching(RIE)is used to fabricate large-area periodic nanostructures,followed by decorating the MIM layers.Compared to MIM disks array on Si surface,the SERS enhancement factor(EF)of the MIM structures on the Si NWs array can be increased up to 5 times,which is attributed to the enhanced electric field at the boundary of the MIM disks.Furthermore,high density of nanoparticles and nanogaps serving as hot spots on sidewall surfaces also contribute to the enhanced SERS signals.Via changing the thickness of the insulator layer,the plasmonic resonance can be tuned,which provides a new localized surface plasmon resonance(LSPR)characteristic for SERS applications.
基金The project supported by National Medical Research Council of Singapore and NUS Academic Research fund
文摘OBJECTIVE Platinum compounds such as cisplatin and carboplatin are frequently used as the first-line chemotherapy for the treatment of the head and neck squamous cell carcinoma(HNSCC).In the present study,we investigated whether garcinol,apolyisoprenylated benzophenone can chemosensitize HNSCC to cisplatin.METHODS The effect of garcinol and cisplatin on HNSCC was assessed by MTT,Western blotting,real time PCR,FACS,immunohistochemistry,DNA binding assay and xenograft mouse model.RESULTS We found that garcinol inhibited the viability of a panel of diverse HNSCC cell lines,enhanced the apoptotic effect of cisplatin,suppressed constitutive as well as cisplatin-induced NF-κB activation,and downregulated the expression of various oncogenic gene products(cyclin D1,Bcl-2,survivin and VEGF).In vivo study showed that administration of garcinol alone(0.5 mg·kg-1,ip five times/week)significantly suppressed the growth of the tumor,and this effect was further increased by cisplatin.Both the markers of proliferation index(Ki-67)and microvessel density(CD31)were downregulated in tumor tissues by the combination of cisplatin and garcinol.The pharmacokinetic results of garcinol indicated that good systemic exposure was achievable after ip administration of garcinol at 0.5and 2mg·kg-1 with mean peak concentration(cmax)of 1825.4 and 6635.7nmol·L-1 in the mouse serum,respectively.CONCLUSION Overall,our results suggest that garcinol can indeed potentiate the effects of cisplatin by negative regulation of various inflammatory and proliferative biomarkers.
基金The project supported by the Agency for Science Technology and Research(A*STAR)(JCO-10/03/FG/06/02)
文摘OBJECTIVE To establish a small compound library via a versatile synthetic route for the investigation of natural-inspiring compounds containing N-hydroxypyridones motif as potential anti-plasmodial,anti-bacterial and iron(Ⅱ)-chelating agents.METHODS An amidation/cyclization approach was adopted to synthesize a library of N-hydroxyquinolinones.The anti-plasmodial susceptibility of lab clone 3D7 P.falciparum was measured using aprotocol modified from the WHO microtest.The minimum bactericidal concentration(MBC)values were determined against Escherichia coli and Staphylococcus arueus.Nine compounds were selected to test their iron(Ⅱ)-chelating abilities.The iron(Ⅱ)-chelating ability was determined by measuring the absorbance of ferrozine-iron complex at 562 nm.RESULTS A new route for the facile synthesis of a library of N-hydroxyquinolinones based on one-pot palladium catalyzed C-N amidation/dehydrocyclizationsequence was implemented.Four compounds show anti-plasmodial activities with the range of 1.1-1.4μmol·L-1,50% chelation abilities of the nine selected compounds were shown to be 0.24-0.29mmol·L-1.CONCLUSION Alibrary of N-hydroxyquinolinones was synthesized via a novel synthetic route.The anti-plasmodial and anti-bacterial activities of these compounds were evaluated.Four compounds show potent anti-plasmodial activities Nine compounds were examined for their propensities to undergo iron chelation and these compounds were shown to be promising iron(Ⅱ)chelators as compared to EDTA.
文摘In this paper, methods are proposed and validated to determine low and high thresholds to segment out gray matter and white matter for MR images of different pulse sequences of human brain. First, a two-dimensional reference image is determined to represent the intensity characteristics of the original three-dimensional data. Then a region of interest of the reference image is determined where brain tissues are present. The non-supervised fuzzy c-means clustering is employed to determine: the threshold for obtaining head mask, the low threshold for T2-weighted and PD-weighted images, and the high threshold for T1-weighted, SPGR and FLAIR images. Supervised range-constrained thresholding is employed to determine the low threshold for T1-weighted, SPGR and FLAIR images. Thresholding based on pairs of boundary pixels is proposed to determine the high threshold for T2-and PD-weighted images. Quantification against public data sets with various noise and inhomogeneity levels shows that the proposed methods can yield segmentation robust to noise and intensity inhomogeneity. Qualitatively the proposed methods work well with real clinical data.
