Methabenzthiazuron Research Articles

Chemical and physical characterization of a natural clay and its use as photocatalyst for the degradation of the methabenzthiazuron herbicide in water

An Algerian, natural clay was investigated and used as a catalyst for the degradation of an aquatic harmful pollutant: Methabenzthiazuron (MBTU) herbicide. The clay was brought from a location near Tamanrasset city in southern Algeria. The natural clay was characterised by XRF and XRD analyses, SEM-EDS and UVvis absorption spectroscopy. This characterisation revealed that the clay contains mainly SiO2, Al2O3 and Fe2O3. Moreover, density functional theory (DFT) reactivity parameters have been calculated and rationalised for the MBTU. The effect on the MBTU photodegradation was studied in function of various parameters including: the carboxylic acid nature, oxalic acid concentration, pH, pollutant concentration, clay concentration and methanol presence. The results showed that the MBTU photodegradation by MBTU/Clay/OA/UV365 nm system was significant in the experimental optimal conditions: [clay] = 1 g/L, [MBTU] = 5 mg/L, pH = 1.5 in the presence of oxalic acid.

ADAM28 dramatically regulates the biological features of human gingival fibroblasts.

This study was to explore the effects of a disintegrin and metalloproteinase 28 (ADAM28) on the proliferation, differentiation, and apoptosis of human gingival fibroblasts (HGFs) and probable mechanism. After ADAM28 antisense oligodeoxynucleotide (AS-ODN) and sense oligodeoxynucleotide (S-ODN) were transfected into HGFs by Lipofectamine 2000, respectively, the expression discrepancies of ADAM28 among various groups were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and Western-blotting. Methabenzthiazuron (MTT) and cell-cycle assays were used to test the HGFs proliferation activity. Annexin V fluorescein isothiocyanate (FITC)/propidium iodide (PI) and alkaline phosphatase (ALP) analysis were performed separately to measure apoptosis and the cytodifferentiation standard. Immunocytochemistry and Western-blotting were carried out to determine the influence of ADAM28 AS-ODN on HGFs expressing core binding factor α1 (Cbfα1), cementum protein 1 (CEMP1), osteopontin (OPN) and dentin matrix protein 1 (DMP1). The AS-ODN group displayed the lowest expression level in HGFs, meanwhile the ADAM28 S-ODN group showed the highest. Furthermore, blocking of ADAM28 could inhibit the proliferation of HGFs, enhance HGFs differentiation and induce apoptosis of HGFs. Whereas, overexpression of ADAM28 generated the opposite effects and inhibited apoptosis. ADAM28 AS-ODN was able to notably suppress the expressions of Cbfα1 and CEMP1, and ADAM28 had positive correlations with cbfα1 and CEMP1. These provided conspicuous evidence that ADAM28 may play a crucial role in root development as a potential regulator of growth, differentiation, and apoptosis of HGFs.

Resveratrol abrogates the effects of hypoxia on cell proliferation, invasion and EMT in osteosarcoma cells through downregulation of the HIF-1α protein.

Resveratrol has been shown to have antineoplastic effects in vivo and in vitro. However, the effect of resveratrol on the hypoxia-enhanced proliferation and invasion of osteosarcoma cells remains unclear. In this study, we investigated the role of resveratrol on regulating proliferation and invasion of osteosarcoma cells under hypoxic conditions. Saos-2 cells were cultured under controlled hypoxic conditions (3% O2) or normoxic conditions. Resveratrol (50 µM) was added in the medium, and hypoxia inducible factor-1α (HIF-1α) siRNA was used to inhibit HIF-1α transcription. Proliferation of Saos-2 cells was evaluated by the methabenzthiazuron (MTT) assay. The invasive ability of Saos-2 cells was determined by a Transwell assay. HIF-1α, E-cadherin and vimentin protein levels were detected by western blot analysis. HIF-1α, E-cadherin and vimentin mRNA levels were assessed by RT-PCR. Compared to the control group, hypoxia significantly increased the proliferation rate and invasive ability of Saos-2 cells. Moreover, hypoxia markedly increased the E-cadherin level and decreased vimentin expression. However, resveratrol or HIF-1α silencing reverted all the above effects of hypoxia in Saos-2 cells. Moreover, resveratrol inhibited HIF-1α protein accumulation without affecting the HIF-1α mRNA level. These data suggest that resveratrol can inhibit the hypoxia‑enhanced proliferation, invasion and epithelial to mesenchymal transition process in osteosarcoma via downregulation of the HIF-1α protein. Thus, HIF-1α may be a promising drug target of resveratrol in the context of development of anticancer therapy for human osteosarcoma.

Effect of tumor necrosis factor receptor associated factor 6 gene silencing by small interfering RNA on proliferation of odontoblast cells

To investigate the effect of small interfering RNA (siRNA)-mediated inhibition of tumor necrosis factor receptor associated factor 6(TRAF6) gene on murine odontoblast-like cell line, MDPC-23 cell and the effect of TRAF6 on MDPC-23 cell proliferation. The vectors expressing siRNA against TRAF6 were constructed and introduced into MDPC-23 cell with lipofectin , and the cell line with stable expression of siRNA of TRAF6 was obtained by G418 screening and colony culture. Reverse transcription-PCR (RT-PCR) and Western blotting were performed to detect the expression of TRAF6. The proliferation of transfected MDPC-23 cell was investigated through methabenzthiazuron (MTT) and flow cytometry (FCM) assay. The positive single colony was screened out, and was found to express siRNA against TRAF6 effectively because both TRAF6 mRNA and protein relative expression were significantly decreased in the experimental group (pSUPER-TRAF6siRNA: mRNA 0.163 ± 0.008, protein 0.215 ± 0.006) compared with controls (pSUPER: mRNA 0.778 ± 0.017, protein 0.964 ± 0.007 (P < 0.001). The A value of treated pSUPER-TRAF6siRNA cells (3 d: 0.46 ± 0.03, 5 d: 1.35 ± 0.06) was increased compared with controls (P<0.01). The result of proliferation index (PrI) was also increased compared with controls [pSUPER- TRAF6siRNA: (24.1 ± 2.2)%; pSUPER (11.2 ± 1.0)%; control (10.5 ± 0.7)%, P < 0.01]. The transcription and expression of TRAF6 gene were inhibited. The proliferation ability was increased in MDPC-23 cells by the constructed pSUPER-TRAF6siRNA vector. It may further influence the formation and repair of dentin, and may be involved in the regulation of normal tooth eruption and process of dentin repair after injury.

Minimization of methabenzthiazuron residues in leaching water using amended soils and photocatalytic treatment with TiO2 and ZnO

In the present work, potential groundwater pollution by methabenzthiazuron (MTBU) and the effect of three different amendments (composted sheep manure, composted pine bark and spent coffee grounds) on its mobility were investigated under laboratory conditions. The efficiency of ZnO and TiO2 suspensions in the photocatalytic degradation of MTBU in leaching water was also investigated. The relative and cumulative breakthrough curves were obtained from disturbed soil columns. The presence and/or addition of organic matter drastically reduced the movement of the herbicide. On other hand, photocatalytic experiments showed that the addition of ZnO and TiO2 strongly enhances the degradation rate of this herbicide compared with the results of photolytic experiments under artificial light. ZnO appeared to be more effective in MTBU oxidation than TiO2. The results obtained point to the interest of using organic wastes and heterogeneous photocatalysis for reducing the pollution of groundwater by pesticide drainage.

Dry-wet cycles increase pesticide residue release from soil.

Soil drying and rewetting may alter the release and availability of aged pesticide residues in soils. A laboratory experiment was conducted to evaluate the influence of soil drying and wetting on the release of pesticide residues. Soil containing environmentally long-term aged (9–17 years) 14C-labeled residues of the herbicides ethidimuron (ETD) and methabenzthiazuron (MBT) and the fungicide anilazine (ANI) showed a significantly higher release of 14C activity in water extracts of previously dried soil compared to constantly moistened soil throughout all samples (ETD: p < 0.1, MBT and ANI: p < 0.01). The extracted 14C activity accounted for 44% (ETD), 15% (MBT), and 20% (ANI) of total residual 14C activity in the samples after 20 successive dry–wet cycles, in contrast to 15% (ETD), 5% (MBT), and 6% (ANI) in extracts of constantly moistened soils. In the dry–wet soils, the dissolved organic carbon (DOC) content correlated with the measured 14C activity in the aqueous liquids and indicated a potential association of DOC with the pesticide molecules. Liquid chromatography MS/MS analyses of the water extracts of dry–wet soils revealed ETD and MBT in detectable amounts, accounting for 1.83 and 0.01%, respectively, of total applied water-extractable parent compound per soil layer. These findings demonstrate a potential remobilization of environmentally aged pesticide residue fractions from soils due to abiotic stresses such as wet–dry cycles. Environ. Toxicol. Chem. 2012; 31: 1941–1947. © 2012 SETAC

Long-term persistence of various 14C-labeled pesticides in soils

The fate of the 14C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9–17 years) in field based lysimeters subject to crop rotation. Analysis of residual 14C activity in the soils revealed 19% (ETD soil; 0–10 cm depth), 35% (MBT soil; 0–30), and 43% (ANI soil; 0–30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide 14C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials.

Efficient degradation of methabenzthiazuron photoinduced by decatungstate anion in water: Kinetics and mechanistic studies

This study concerns the elimination of methabenzthiazuron (MBTU) photocatalysed by sodium decatungstate salts W 10 O 32 4 - .(DTA) in aqueous solution under irradiation at 365 nm. Ninety percentage of MBTU (10 −4 M) is mineralised in the presence of the photocatalyst (2 × 10 −4 M) after 7 d under exposure and the formation of nitrate, sulphate and ammonium confirmed this phenomenon. In aerated conditions, the photodegradation rate of MBTU clearly increased in the presence of DTA by a factor of 40 when compared to direct photolysis with Φ MBTU = 2.5 × 10 −2 and t 1/2 (MBTU) = 1.4 h. Oxygen appeared essential since 2 times inhibition of MBTU disappearance and the photocatalytic cycle interrupt were observed in the absence of oxygen. The degradation mechanism has been elucidated through the photoproducts identification by LC–ESI-MS analysis. Two processes were implied in the degradation: electron transfer and H atom abstraction reactions both involving W 10 O 32 4 - ∗ excited state species. In the primary steps of the degradation, the aromatic ring hydroxylation was observed by electron transfer leading to OH-MBTU isomers and H atom abstraction reaction gave benzthiazuron and a supposed demethylated product. Secondary oxidations permitted the hydroxylation of both products.

ADAM28 Manipulates Proliferation, Differentiation, and Apoptosis of Human Dental Pulp Stem Cells

Introduction The purpose of this study was to investigate the influence of a disintegrin and metalloproteinase 28 (ADAM28) on the proliferation, differentiation, and apoptosis of human dental pulp stem cells (HDPSCs) and possible mechanism. Methods After ADAM28 eukaryotic plasmid and antisense oligodeoxynucleotides (AS-ODNs) were constructed and respectively transfected into HDPSCs by Lipofectamine 2000, the ADAM28 expression levels among diverse groups were estimated by reverse transcription polymerase chain reaction (RT-PCR) and western blotting. Methabenzthiazuron (MTT) and cell cycle assays were used to test the HDPSCs proliferation activity. Annexin V- fluorescein isothiocyanate (FITC)/propidium iodide and alkaline phosphatase analysis were performed respectively to measure apoptosis and the cytodifferentiation level. Immunocytochemistry and western blotting were performed to determine the effects of ADAM28 eukaryotic plasmid on HDPSCs expressing dentin sialophosphoprotein (DSPP), dentin matrix protein 1, and bone sialoprotein. Results ADAM28 could be correctly transcribed, translated, and expressed in HDPSCs. The ADAM28 AS-ODN group displayed the highest optical density value, whereas the eukaryotic plasmid group showed the lowest, which suggested that ADAM28 had a negative regulatory effect on the proliferation of HDPSCs. ADAM28 eukaryotic plasmid could significantly inhibit the HDPSC proliferation, promote specific differentiation of HDPSCs, induce apoptosis, and enhance the DSPP expression, whereas ADAM28 AS-ODN produced the opposite effects. Conclusions Our results proved that ADAM28 might actively participate in manipulating the proliferation, differentiation, and apoptosis of HDPSCs.

The correlation between the malignant proliferation on cholangiocarcinoma cell lines and in bile from Helicobacter pylori infected patients with biliary tract stones

Helicobacter pylori has been detected in human tissue and is a candidate for etiologic investigations on the causes of hepatic and biliary tract diseases, but reliable serologic tests need to be developed in order to pursue such investigations. The aim of this study was to assess the correlation between the infection of H. pylori in bile from patients with biliary tract stones and the proliferation of human cholangiocarcinoma and its mechanism. Choledocholithiasis bile with positive H. pylori (PCB), Choledocholithiasis bile withnegative H. pylori (NCB) and normal bile (NB) were part of the study. Cholangiocarcinoma cell lines QBC939 and TFK-1 were analyzed. The proliferative effects were measured by methabenzthiazuron (MTT) assay. Cell cycle and apoptosis were analyzed by flow cytometry. Compared with NB and NCB, PCB significantly promoted the proliferation of cholangiocarcinoma cell lines QBC939 and TFK-1. The proliferative index in PCB group was obviously higher than that in NCB group after being treated with 1% PCB for 48 h (p <0.05). As far as the apoptosis rate was concerned, there were no obvious differences between PCB group and NCB group (p < 0.05), same as between PCB group and NB group (p < 0.05). The percentage of S phase increased remarkably in PCB group compared with NCB group, while the percentage of G0/G1 phase decreased remarkably in PCB group compared with NCB group. It was suggested that PCB can greatly promote the malignant proliferation of human cholangiocarcinoma cell lines QBC939 and TFK-1, and the mechanism was affected by the changes of cell cycle. So we can predict that there was perhaps a close relation between H. pylori infection and cholangiocarcinoma. Key words: Malignant proliferation, Helicobacter pylori, cholelithiasis, bile, cholangiocarcinoma.

Effects of protein kinase C inhibitor,chelerythrine chloride,on drug-sensitivity of NSCLC cell lines

Protein kinase C(PKC) is a potentially important target for can-cer therapeutics due to its potential role in carcinogenesis.Abnormal expression and increasing activity of PKC-α are present in non-small cell lung cancer(NSCLC).PKC inhibitor can show anti-tumor effects through inducing tumor cell apoptosis,enhancing cytotoxic effects and down-regulating expressions of multidrug resistance gene.By observing the effects of PKC inhibitor chelerythrine chloride(CH) on drug-sensitivity to cisplatin of four NSCLC cell lines its mechanism of effect initially is explored. NSCLC cell lines(H1299,H460,A549 and cisplatin-resistant A549) were dealed with PKC inhibitor CH respectively.The expressions of PKC-α mRNA and protein in NSCLC cell lines were examined by reverse transcription polymerase chain reaction(RT-PCR) and Western blot.The apoptosis rates of NSCLC cells lines were detected by flow cytometry.The drug-sensitivity to cisplatin of NSCLC cells lines was measured by methabenzthiazuron(MTT) assay. The expression levels of PKC-α mRNA and protein in cisplatin-resistant A549 cell lines were significantly higher than H1299,H460 and parent A549 cell lines(P < 0.05).The expression levels of PKC-α mRNA and protein in four NSCLC cell lines decreased at different extent.The apoptosis rates of cisplatin-resistant A549 cell lines increased obviously after treating with CH for 4 and 24 hours,but it was not seen in H1299,H460 and parent A549 cell lines.The IC50 value of cisplatin of NSCLC cell lines decreased at different degree after treating with CH and it was more obvious in cisplatin-resistant A549 cell lines(P < 0.05). High expressions of PKC-α mRNA and protein exist in all four NSCLC cell lines.PKC inhibitor CH can enhance the drug-sensitivity of NSCLC cell lines to cisplatin by inhibiting their expression of PKC-α mRNA and protein.When compared with parent A549 cell lines,cisplatin-resistant A549 cell line's drug-sensitivity to cisplatin is increasing more efficiently by PKC inhibitor CH through inhibition of PKC-α protein's expression and elevation of tumor cell apoptosis rates.

Biotoxic Effects of Herbicides on Growth, Nodulation, Nitrogenase Activity, and Seed Production in Chickpeas

The effects of pre‐emergent (PRE) application of methabenzthiazuron (MBT), terbutryn, and linuron on plant vigor, number of nodules formed, nitrogenase activity (NA), chlorophyll contents, nitrogen (N) uptake, and seed yield were assessed in inoculated chickpeas, grown in sandy clay loam soil, in a controlled environment. The PRE application of MBT, terbutryn, and linuron at 2.5, 1.25 and 2 g a.i. kg−1, respectively, had no significant adverse effect on plant vitality, yield, and NA of excised nodules in inoculated chickpea plants, but reduced these parameters at 7.5, 3.75, and 6 g a.i. kg−1 of soil. Among the herbicides tested, linuron at each dose rates significantly (P≤0.05) decreased the grain yield, whereas terbutryn at 1.25 and 2.5 g a.i. kg−1 improved the grain yield by 19.4% and 11%, respectively, relative to the nonherbicide control. While comparing the sum of mean values of toxicity of all dose rates of each herbicide on grain yield, the toxicity increased in the following order: control=linuron>methabenzthiazuron>terbutryn. Nodulation (nodule number per plant and their dry mass) and chlorophyll contents per plant decreased consistently with increased herbicide rates, except linuron, which at 2 g a.i. kg−1 improved nodulation at both 45 and 90 days after seeding and corresponded with Mesorhizobium activity. The N content in grain and straw significantly decreased at the highest tested rates of each herbicide. Linuron at 2 and 4 g a.i. kg−1 improved N content in straw, whereas at 4 g a.i. kg−1 it significantly reduced N content in grain.

Inhibitory effect of caffeic acid phenethyl ester on the growth of SW480 colorectal tumor cells involves β-catenin associated signaling pathway down-regulation

To study the anti-tumor effect of caffeic acid phenethyl ester (CAPE) and the influence of CAPE on beta-catenin associated signaling pathway in SW480 colorectal cancer (CRC) cells. SW480 cells were treated with CAPE at serial concentrations. The proliferative status of cells was measured by methabenzthiazuron (MTT) assay. Cell cycle and cell apoptosis were analyzed using flow cytometry (FCM). Western blotting assay was used to evaluate the protein level of beta-catenin, c-myc and cyclinD1. Beta-catenin localization was determined by indirect immunofluorescence. CAPE displayed a strong inhibitory effect in a significant dose- and time-dependent manner on SW480 cell growth. FCM analysis showed that the ratio of G0/G1 phase cells increased, S phase ratio decreased and apoptosis rate increased after SW480 cells were exposed to CAPE for 24 h. Pretreatment of SW480 cells with CAPE significantly suppressed beta-catenin, c-myc and cyclinD1 protein expression. CAPE treatment was associated with decreased accumulation of beta-catenin protein in nucleus and cytoplasm, and concurrently increased its accumulation on the surface of cell membrane. CAPE can inhibit SW480 cell proliferation by inducing cell cycle arrest and apoptosis. Decreased beta-catenin and the associated signaling pathway target gene expression may mediate the anti-tumor effects of CAPE.

Effects of cyclooxygenase-2 antisense vector on proliferation and sensitivity to cisplatin of H1299 cells

At present, it has been known that cyclooxygenase-2 (COX-2) plays a crucial role in invasion, development and metastasis of non-small cell lung cancer (NSCLC). In order to explore whether the expression of COX-2 inhibits the occurrence and development of NSCLC, antisense vector of human COX-2 gene is transfected into COX-2 highly expressing NSCLC cell line H1299 and its effects on proliferation and sensitivity to cisplatin of H1299 are analysed. H1299 cells were transfected with antisense vector of human COX-2 gene using LipoVecTM transfecting technique. Transfected cells were selected with Geneticin (G418). The COX-2 mRNA level was examined by using reverse polymerase chain reaction (RT-PCR). The COX-2 protein level was examined by Western Blot. The proliferative status and sensitivity to cisplatin of cells was measured by methabenzthiazuron (MTT) assay. RT-PCR showed a lower COX-2 mRNA level in transfected cells. The level of COX-2 protein was decreased apparently. The proliferative index of the transfected cells decreased significantly (P < 0.05). The IC50 value of cisplatin decreased remarkably in transfected cells (1.8mg/l) compared with that in H1299 cells without transfection (3.8mg/l) (P < 0.05). Transfection with antisense vector of human COX-2 gene can not only inhibit the proliferation of H1299 cells, but also increase the sensitivity to cisplatin of H1299 cells.

Intercomparison of Flow and Transport Models Applied to Vertical Drainage in Cropped Lysimeters

Models predicting flow and transport in the vadose zone differ in their conceptual approach, their complexity, and their mathematical formulation. Four models (MARTHE, TRACE, ANSWERS, and MACRO), which differ significantly in their model concepts and complexity, were applied to a common data set to evaluate and compare the different model approaches. Five free‐draining lysimeters, cropped with winter wheat, barley, and oat were used to monitor actual evapotranspiration, soil moisture, and drainage for 627 d. One of the five lysimeters was also treated with methabenzthiazuron (MBT), and soil residues as well as leaching were experimentally determined. In Europe, MBT has been commonly used as a herbicide for almost 30 years. Generally, the use of given model inputs is recommended, apart from plant parameters, which need calibration. The use of validation criteria revealed proper simulation of water flow for the four models. After calibration, the Richards' equation–based models MARTHE, TRACE, and MACRO performed better for water flow predictions than the capacity‐based ANSWERS. A small amount of preferential flow, which is not included in the model structures of MARTHE, TRACE, and ANSWERS, did not influence the simulation of water flow significantly. But preferential flow was associated with the leaching of 0.0059% of the applied mass of MBT, causing relevant concentrations in the leachate. Leaching could be described well with MACRO after calibration. The difficulty of estimating parameters for modeling macropore transport is seen as an obstacle to common application.

Celecoxib inhibits proliferation and induces apoptosis via cyclooxygenase-2 pathway in human pancreatic carcinoma cells.

In order to evaluate the effects and mechanisms of celecoxib in inhibiting proliferation and inducing apoptosis on human pancreatic carcinoma cells, the anti-proliferative effect was measured by using methabenzthiazuron (MTT) assay. Cell cycle and apoptosis were analyzed by using flow cytometry (FCM), and the PGE2 levels in the supernatant of cultured pancreatic carcinoma cells were quantitated by enzyme-linked immunoabsordent assay (ELISA). Our results showed that celecoxib suppressed the production of PGE2 and inhibited the growth of JF-305 cells, and the anti-proliferative effect of celecoxib could be abolished by addition of PGE2. FCM revealed that celecoxib could inhibit proliferation and induce apoptosis by Gl- S cell cycle arrest. It was concluded that cyclooxygenase-2 specific inhibitor celecoxib could inhibit proliferation and induced apoptosis of human pancreatic carcinoma cells via suppression of PGE2 production in vitro.

Effect of caffeic acid phenethyl ester on proliferation and apoptosis of colorectal cancer cellsin vitro

To study the effect of caffeic acid phenethyl ester (CAPE) on proliferation, cell cycle, apoptosis and expression of beta-catenin in cultured human colorectal cancer (CRC) cell line HCT116. HCT116 cells were treated with CAPE at serial concentrations of 80, 40, 20, 10, 5, 2.5 mg/L. The proliferative status of HCT116 cells was measured by using methabenzthiazuron (MTT) assay. Cell cycle was analyzed by using flow cytometry (FCM) with propidium iodide (PI) labeling method. The rate of apoptosis was detected by using FCM with annexin V-FITC and PI double labeling method. beta-catenin levels were determined by Western blotting. beta-catenin localization in HCT116 was determined by indirect immunofluorescence. After HCT116 cells were exposed to CAPE (80, 40, 20, 10, 5, and 2.5 mg/L) for 24, 48, 72, 96 h, CAPE displayed a strong growth inhibitory effect in a dose- and time-dependent manner against HCT116 cells. FCM analysis showed that the ratio of G(0)/G(1) phase cells increased, S phase ratio decreased and apoptosis rate increased after HCT116 cells were exposed to CAPE (10, 5, and 2.5 mg/L) for 24 h. CAPE treatment was associated with decreased cytoplasmic beta-catenin, nuclear beta-catenin and a concurrent increase in beta-catenin protein expression at cell-cell junctions. CAPE could inhibit HCT116 cell proliferation and induce cell cycle arrest and apoptosis. Decreased beta-catenin protein expression may mediate the anti-proliferative effects of CAPE.

Celecoxib inhibits proliferation and induces apoptosis via prostaglandin E2 pathway in human cholangiocarcinoma cell lines.

To evaluate the roles and mechanisms of celecoxib in inducing proliferation inhibition and apoptosis of human cholangiocarcinoma cell lines. Cyclooxygenase-2-overexpressing human cholangiocarcinoma cell line QBC939 and cyclooxygenase-2-deficient human cholangiocarcinoma cell line SK-CHA-1 were used in the present study. The anti-proliferative effect was measured by methabenzthiazuron (MTT) assay; apoptosis was determined by transferase-mediated dUTP nick end labeling (TUNEL) detection and transmission electron microscopy (TEM). Cell cycle was analyzed by flow cytometry (FCM). The PGE(2) levels in the supernatant of cultured cholangiocarcinoma cells were quantitated by enzyme-linked immunoabsordent assay (ELISA). Celecoxib suppressed the production of PGE(2) and inhibited the growth of QBC939 cells. Celecoxib at 10, 20, and 40 micromol/L inhibited PGE(2) production by 26 %, 58 %, and 74 % in QBC939 cells. The PGE(2) level was much lower constitutively in SK-CHA-1 cells (18.6+/-3.2) compared with that in QBC939 (121.9+/-5.6) cells (P<0.01) and celecoxib had no significant influence on PGE(2) level in the SK-CHA-1 cells. The PGE(2) concentration in SK-CHA-1 cells also reduced but not significantly after treatment with celecoxib. The PGE(2) concentration in SK-CHA-1 cells was (16.5+/-2.9) ng/well, (14.8+/-3.4) ng/well, (13.2+/-2.0) ng/well and (12.6+/-3.1) ng/well respectively, when pre-treated with 1 micromol/L, 10 micromol/L, 20 micromol/L and 40 micromol/L of celecoxib for 48 h (P>0.05, vs control). The anti-proliferation effect of celecoxib (20 micromol/L) on QBC939 cells was time-dependent, it was noticeable on day 2 (OD490=0.23+/-0.04) and became obvious on day 3 (OD490=0.31+/-0.07) to day 4 (OD490= 0.25+/-0.06), and the OD490 in the control group (day 1) was 0.12+/-0.03 (P<0.01, vs control). The anti-proliferation effect of celecoxib could be abolished by the addition of 200 pg/mL PGE(2). The proliferation of SK-CHA-1 cells was inhibited slightly by celecoxib, the cell density OD490 in the presence of celecoxib and in control group was 0.31+/-0.04 and 0.42+/-0.03 respectively on day 2 (P>0.05), 0.58+/-0.07 and 0.67+/-0.09 respectively on day 3 (P>0.05), and 0.71+/-0.08 and 0.78+/-0.06 respectively on day 4 (P>0.05). Celecoxib induced proliferation inhibition and apoptosis by G(1)-S cell cycle arrest: the percentage of QBC939 cells in G(0)-G(1) phase after treatment with 40 micromol/L (74.66+/-6.21) and 20 micromol/L (68.63+/-4.36) celecoxib increased significantly compared with control cells (54.41+/-5.12, P<0.01). The percentage of SK-CHA-1 cells in G(0)-G(1) phase after treatment with various concentrations of celecoxib didn't change significantly compared with control cells. The TUNEL index was much higher in QBC939 cells treated with 20 micromol/L celecoxib for 2 d (0.063+/-0.018) and for 4 d (0.102+/-0.037) compared with control cells (0.017+/-0.004, P<0.01). The current in vitro study indicates that inhibition of proliferation and induction of apoptosis in human cholangiocarcinoma cells by cyclooxygenase-2 specific inhibitor celecoxib may involve in COX-dependent mechanisms and PGE(2) pathway. Celecoxib as a chemopreventive and chemotherapeutic agent might be effective primarily on COX-2-expressing cholangiocarcinoma.

Microwave-assisted solvent extraction of the herbicide methabenzthiazuron from soils and some soil natural organic and inorganic constituents. Influence of environmental factors on its extractability.

A microwave-assisted solvent extraction (MASE) method for the determination of methabenzthiazuron (MBT) in soil samples by HPLC-DAD (diode array detection) was evaluated. Spiked soil samples having different physico-chemical properties, and selected soil-derived matrices with diverse MBT adsorption capacity, characterized by their Freundlich equation Kf values, were used to verify the method applicability to a broad range of different soils. The spiking procedure was considered a crucial point to reproduce as closely as possible the solute-soil adsorption taking place in the natural environment. Ageing effects, where the compound could diffuse into inaccessible locations within the soil matrix in view of its great stability, were considered of particular concern. In spite of the heterogeneous physico-chemical properties of soils under study, recoveries were greater than 90%. Performance of the MASE procedure correlated highly with the adsorption capacity of soil-derived matrices: the lowest recoveries were for illite (67-73%), among the mineral surfaces, and for a humic acid (67-72%), among the organic fractions. Intra-assay variation for each type of sample soil range from 0.40 to 3.89%(RSD). Limits of detection and quantification were 0.047 and 0.15 microg g(-1), respectively. Analyte residence time was not a very significant factor on the extractability.

Proliferative activity of bile from congenital choledochal cyst patients.

To explore the potential carcinogenicity of bile from congenital choledochal cyst (CCC) patients and the mechanism of the carcinogenesis in congenital choledochal cyst patients. 20 bile samples from congenital choledochal cyst patients and 10 normal control bile samples were used for this study. The proliferative effect of bile was measured by using Methabenzthiazuron (MTT) assay; Cell cycle and apoptosis were analyzed by using flow cytometry (FCM), and the PGE(2) levels in the supernatant of cultured cholangiocarcinoma cells were quantitated by enzyme-linked immunoabsorbent assay (ELISA). CCC bile could significantly promote the proliferation of human cholangiocarcinoma QBC939 cells compared with normal bile (P=0.001) and negative control group (P=0.002), and the proliferative effect of CCC bile could be abolished by addition of cyclooxygenase-2 specific inhibitor celecoxib (20 microM). The QBC939 cells proliferative index was increased significantly after treated with 1 % bile from CCC patient (P=0.008) for 24 h, the percentage of S phase (29.48+/-3.27)% was increased remarkably (P<0.001) compared with normal bile (11.72+/-2.70) %, and the percentage of G0/G1 phase (54.19+/-9.46) % was decreased remarkably (P=0.042) compared with normal bile (69.16+/-10.88) %, however, bile from CCC patient had no significant influence on apoptosis of QBC939 cells (P=0.719). Bile from congenital choledochal cyst patients can promote the proliferation of human cholangiocarcinoma QBC939 cells via COX-2 and PGE(2) pathway.