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Inducer
Kinds of Inducer Selected AbstractsTotal Synthesis of (-)-Scabronine G, an Inducer of Neurotrophic Factor Production.CHEMINFORM, Issue 6 2006Stephen P. Waters No abstract is available for this article. [source] Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14 during cardiac remodelling in ratsACTA PHYSIOLOGICA, Issue 1 2010E. Mustonen Abstract Aim:, Accumulating evidence supports the concept that proinflammatory cytokines play an essential role in the failing heart. We examined the concomitant tumour necrosis factor-like weak inducer of apoptosis (TWEAK)/Fn14 expression in myocytes in vitro as well as in vivo in cardiac remodelling. Methods:, We assessed TWEAK and its receptor Fn14 expression in response to angiotensin (Ang) II, myocardial infarction (MI) as well as to local adenovirus-mediated p38 gene transfer in vivo. The effect of various hypertrophic factors and mechanical stretch was studied in neonatal rat ventricular myocyte cell culture. Results:, Ang II increased Fn14 levels from 6 h to 2 weeks, the greatest increase in mRNA levels being observed at 6 h (6.3-fold, P < 0.001) and protein levels at 12 h (4.9-fold, P < 0.01). TWEAK mRNA and protein levels remained almost unchanged during Ang II infusion. Likewise, a rapid and sustained elevation of Fn14 mRNA and protein levels in the left ventricle was observed after experimental MI. Moreover, local p38 gene transfer increased Fn14 mRNA and protein but not TWEAK levels. Fn14 immunoreactive cells were mainly proliferating non-myocytes in the inflammation area while TWEAK immunoreactivity localized to cardiomyocytes and endothelial cells of the coronary arteries. Hypertrophic agonists and lipopolysaccharide increased Fn14 but not TWEAK gene expression in neonatal rat myocytes, while mechanical stretch upregulated Fn14 and downregulated TWEAK gene expression. Conclusions:, In conclusion, the cardiac TWEAK/Fn14 pathway is modified in response to myocardial injury, inflammation and pressure overload. Furthermore, our findings underscore the importance of Fn14 as a mediator of TWEAK/Fn14 signalling in the heart and a potential target for therapeutic interventions. [source] Studies on dentin grafts to bone defects in rabbit tibia and mandible; development of an experimental modelDENTAL TRAUMATOLOGY, Issue 1 2009Lars Andersson This property may possibly be used as an alternative or supplement to bone grafting to defective areas after trauma prior to treatment with osseointegrated implants. Hence, the objective of this study was to investigate if dentin can be used as a graft in bone defects in an experimental rabbit model. Materials and Methods:, Eight New Zealand White Rabbits were used to prepare bone cavities either in the angle of the mandible or tibia. Six of the eight tibial and six of the eight mandibular bone defects were filled with dentin blocks from human premolars which were extracted for orthodontic treatment. Two mandibular and two tibial bone cavities were used as controls and all the rabbits were sacrificed after 3 months. Radiographic and histological examinations were performed. Results:, There was a difference in healing pattern between the mandibular and tibial defects. In the mandible, the dentin blocks were resorbed to a larger extent and more often surrounded by fibrous tissue, probably due to the fact that the dentin blocks were mobile because of the thin mandibles and muscular activity in that area. Only some dentin blocks were ankylosed with the mandibular bone. In the tibia however, all dentin blocks were fused to bone over a large area. Osseous replacement resorption was seen. In control cavities, bone formation was seen but was never complete. No signs of inflammatory changes were seen in any fused grafts. Conclusions:, Dentin grafts have a potential to be incorporated in bone without inflammation and can be used as bone inducer and later replaced by bone. Thus, rabbit tibia served as a better model for further studies of this phenomenon when compared to the mandible. [source] Xenopus Wnt11b is identified as a potential pronephric inducerDEVELOPMENTAL DYNAMICS, Issue 1 2010Stéphanie Tételin Abstract In this study, we aimed to establish if known wnt signaling molecules could be responsible for inducing early pronephros specification, using a novel and effective in vitro bioassay in Xenopus embryos. Anterior somites have the unique biological activity to signal to unspecified intermediate mesoderm to induce pronephros formation in Xenopus embryos. We have used a molecular candidate gene approach to analyze both canonical and noncanonical wnt expression in isolated anterior and posterior somites and dissected presumptive pronephros, pronephric anlagen, and pronephros from stage 12.5,35 embryos. We have identified potential candidate wnt genes expressed in the right time and place to specify pronephric development. These candidates were then directly tested in an in vitro pronephrogenesis assay based on Holtfreter sandwich cultures. Results revealed that noncanonical wnt11b and wnt11 can induce pronephros formation in vitro. Loss-of-function experiments confirmed that these genes are necessary for normal pronephros development. Developmental Dynamics 239:148,159, 2010. © 2009 Wiley-Liss, Inc. [source] Conditional expression of a myocardium-specific transgene in zebrafish transgenic linesDEVELOPMENTAL DYNAMICS, Issue 4 2005Chiu-Ju Huang Abstract To develop the first heart-specific tetracycline (Tet)-On system in zebrafish, we constructed plasmids in which the cardiac myosin light chain 2 promoter of zebrafish was used to drive the reverse Tet-controlled transactivator (rtTA) and the green fluorescent protein (GFP) reporter gene was preceded by an rtTA-responsive element. In the zebrafish fibroblast cell-line, rtTA-M2, one of rtTA's derivatives, demonstrated the highest increase in luciferase activity upon doxycycline (Dox) induction. We then generated two germ lines of transgenic zebrafish: line T03 was derived from microinjection of a plasmid containing rtTA-M2 and a plasmid containing a responsive reporter gene, whereas line T21 was derived from microinjection of a single dual plasmid. Results showed that line T21 was superior to line T03 in terms of greater GFP intensity after induction and with of minimal leakiness before induction. The photographic images of induced GFP in the heart of F2 larvae showed that the fluorescent level of GFP was dose-responsive. The level of GFP expressed in the F3 3 days postfertilization larvae that were treated with Dox for 1 hr decreased gradually after the withdrawal of the inducer; and the fluorescent signal disappeared after 5 days. The GFP induction and reduction were also tightly controlled by Dox in the F3 adult fish from line T21. This Tet-On system developed in zebrafish shows much promise for the study of the gene function in a specific tissue at the later developmental stage. Developmental Dynamics 233:1294,1303, 2005. © 2005 Wiley-Liss, Inc. [source] Independent induction and formation of the dorsal and ventral fins in Xenopus laevisDEVELOPMENTAL DYNAMICS, Issue 3 2004A.S. Tucker Abstract It has been known since the 1930s that the dorsal fin is induced by the underlying neural crest. The inducer of the ventral fin, however, has remained elusive. We have investigated the source of the inducer of the ventral fin in Xenopus and show that it is the ventral mesoderm and not the neural crest. This induction takes place during mid-neurula stages and is completed by late neurulation. In terms of cell composition, the dorsal fin mesenchyme core arises from neural crest cells, while the mesenchyme of the ventral fin has a dual origin. The ventral fin contains neural crest cells that migrate in from the dorsal side of the embryo, but a contribution is also made by cells from the ventral mesoderm. Developmental Dynamics 230:461,467, 2004. © 2004 Wiley-Liss, Inc. [source] Evaluation of apoptosis in cytologic specimensDIAGNOSTIC CYTOPATHOLOGY, Issue 9 2010Viktor Shtilbans Ph.D. Abstract A hallmark of neoplasia is dysregulated apoptosis, programmed cell death. Apoptosis is crucial for normal tissue homeostasis. Dysregulation of apoptotic pathways leads to reduced cytocidal responses to chemotherapeutic drugs or radiation and is a frequent contributor to therapeutic resistance in cancer. The literature pertaining to detection of apoptotic pathway constituents in cytologic specimens is reviewed herein. Virtually all methods for detecting apoptosis, including classic cytomorphologic evaluation, TUNEL assay, immunocytochemistry, and gene sequence analysis, may be applied to cytologic samples as well as tissue. Components of both intrinsic and extrinsic apoptotic pathways have been studied, including many reports examining p53 and bcl-2, as well as studies of caspase inhibitory proteins XIAP and survivin, death receptors and ligands such as Fas, Fas-ligand, and TRAIL. p53 undergoes oncogenic alteration more than any other protein; its immunocytochemical detection almost always connotes loss of its physiologic role as an inducer of apoptosis in response to a damaged genome. Several reports establish cytologic sampling as being as useful as tissue sampling. In one respect cytologic sampling is superior to tissue sampling in particular, by allowing clinicians to repeat sampling of the same tumor before and after administration of therapy; a number of reports use this approach to attempt to predict tumor response by assaying the effect of chemotherapy on the induction of apoptosis. Diagn. Cytopathol. 2010;38:685,697. © 2010 Wiley-Liss, Inc. [source] Expression of EMMPRIN and matriptase in esophageal squamous cell carcinoma: Correlation with clinicopathological parametersDISEASES OF THE ESOPHAGUS, Issue 6 2006M.-F. Cheng SUMMARY., Extracellular matrix metalloproteinase inducer (EMMPRIN) and the type II transmembrane serine protease, matriptase, are expressed in several human cancers and play an important role in tumor progression. The aim of the present study was to investigate the immuno-staining patterns of EMMPRIN and matriptase in patients with esophageal squamous cell carcinomas (SCC) and correlate the percentage tumor staining with tumor differentiation and clinical parameters. EMMPRIN and matriptase immunoreactivity was seen on the cell membrane and in the cytoplasm of tumor cells in all 41 cases of esophageal SCC evaluated. The percentage tumor staining of EMMPRIN was 48 ± 3% for well differentiated, 73 ± 3% for moderately differentiated, and 92 ± 3% for poorly differentiated esophageal SCC. Higher percentage tumor staining with EMMPRIN correlated significantly with poorly differentiated esophageal SCC (P < 0.05). The percentage tumor staining with matriptase correlated significantly with tumor differentiation (52 ± 3% for well differentiated, 85 ± 2% for moderately differentiated, and 88 ± 3% for poorly differentiated esophageal SCC). Additionally, higher percentage tumor staining with matriptase was significantly correlated with the advanced N and M stages (P < 0.05). Our results demonstrate that EMMPRIN and matriptase are over-expressed in esophageal SCC and are correlated with advanced clinicopathological stages. Pharmacological agents targeting EMMPRIN and matriptase expressions may be beneficial in the treatment of esophageal SCC. [source] Genotoxicity of naturally occurring indole compounds: correlation between covalent DNA binding and other genotoxicity testsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2002M. Vijayaraj Reddy Abstract 3-Methylindole (3MI), melatonin (Mel), serotonin (Ser), and tryptamine (Tryp) were evaluated in vitro for their potential to induce DNA adducts, DNA strand breaks, chromosomal aberrations (Abs), inhibition of DNA synthesis, and mutations. All compounds produced DNA adducts in calf thymus DNA in the presence of rat liver S9. In cultured rat hepatocytes, all produced DNA adducts but none induced DNA strand breaks. In Chinese hamster ovary cells, 3MI and Mel produced DNA adducts, Abs, and inhibition of DNA synthesis with and without S9, except that Mel without S9 did not form adducts. Ser formed DNA adducts, was an equivocal Abs inducer, and suppressed DNA synthesis. Tryp induced neither adducts nor Abs, but did suppress DNA synthesis with S9. Ser and Tryp were less cytotoxic than 3MI and Mel. Mel, Ser, and Tryp failed to induce mutations in Salmonella and E. coli strains with or without S9. 3MI and Mel produced DNA adducts but not mutations in Salmonella TA100 with S9. 3MI and its metabolite indole 3-carbinol also did not induce mutations in a shuttle vector system in human cells. The lack of correlation between DNA adducts and other genotoxicity endpoints for these indole compounds may be due to the higher sensitivity of the 32P-postlabeling adduct assay or it may indicate that the indole-DNA adducts per se are not mutagenic and are not able to induce strand breaks or alkali-labile lesions. The indole-induced Abs may result from cytotoxicity and suppression of DNA synthesis with minimal if any contribution from DNA adducts. Environ. Mol. Mutagen. 40:1,17, 2002. © 2002 Wiley-Liss, Inc. [source] DNA damage assessment by comet assay of human lymphocytes exposed to jet propulsion fuelsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2002Shawna M. Jackman Abstract Exposure to jet fuel damages DNA and results in a number of physiological changes in liver, lung, immune, and neurological tissue. In this study the single-cell gel electrophoresis assay or comet assay was used to compare the DNA damage in human peripheral lymphocytes produced by three jet propulsion fuels: JP-8, JP-5, and JP-8+100. These fuels consist of complex mixtures of aliphatic, aromatic, and substituted naphthalene hydrocarbons. Two exposure times were investigated which correspond to estimated occupational exposure times and concentrations of fuels were used that were based on previous fuel toxicity studies. Analysis of samples for the extent of DNA damage as determined by tail moment and percent tail DNA was performed on exposed cells following a brief recovery time. All fuels produced significant increases in DNA damage; however, only JP-8+100 was genotoxic at the lowest exposure concentration (1:500). At the highest exposure concentration (1:75), the mean tail moments for JP-8 and JP-8+100 (32.041 ± 2.599 and 45.774 ± 4.743, respectively) were significantly greater than for JP-5 (1.314 ± 0.474). These results indicate that JP-8+100 is the most potent inducer of DNA damage in human peripheral lymphocytes and that both JP-8+100 and JP-8 are capable of damaging lymphocyte DNA to a greater extent than JP-5. Environ. Mol. Mutagen. 40:18,23, 2002. © 2002 Wiley-Liss, Inc. [source] Morphological and biochemical changes associated with apoptosis induced by okadaic acid in human amniotic FL cellsENVIRONMENTAL TOXICOLOGY, Issue 5 2009Ming-luan Xing Abstract The marine toxin okadaic acid (OA) is an apoptosis inducer and a tumor promoter. During recent years, extensive studies have demonstrated that OA can induce apoptosis in a wide variety of cell types. In contrast to the relatively longer incubation time or higher treatment concentrations of OA in apoptosis shown previously, relatively lower concentrations (,100 nM) and shorter time (4 h) were designed in the current study to observe the toxic effects of OA in human amniotic cells (FL cells). The present study was undertaken to determine the morphological and biochemical changes of FL cells induced by OA. Results indicated that externalization of phosphatidylserine, cytoskeletal disruption, DNA strand breaks and decrease of Bcl-2 protein expression levels as well as increase of PP2A-A subunit protein were all involved in the apoptosis of FL cells induced by OA. This work not only provided further evidence of apoptosis induced by OA but also suggested that PP2A might play a pivotal role in apoptosis induced by protein phosphatases inhibitors. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] 2,3,4,7,8-pentachlorodibenzofuran is a more potent cytochrome P4501A inducer than 2,3,7,8-tetrachlorodibenzo- p -dioxin in herring gull hepatocyte culturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Jessica C. Hervé Abstract Concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), and 2,3,7,8-tetrachlorodibenzofuran (TCDF) on cytochrome P4501A (CYP1A) induction were determined in primary cultures of embryonic herring gull (Larus argentatus) hepatocytes exposed for 24,h. Based on the concentration that induced 50% of the maximal response (EC50), the relative potencies of TCDD and TCDF did not differ by more than 3.5-fold. However, also based on the EC50, PeCDF was 40-fold, 21-fold, and 9.8-fold more potent for inducing ethoxyresorufin- O -deethylase (EROD) activity, CYP1A4 mRNA expression, and CYP1A5 mRNA expression than TCDD, respectively. The relative CYP1A-inducing potencies of PeCDF and of other dioxin-like chemicals (DLCs) in herring gull hepatocytes (HEH RePs), along with data on concentrations of DLCs in Great Lakes herring gull eggs, were used to calculate World Health Organization toxic equivalent (WHO-TEQ) concentrations and herring gull embryonic hepatocyte toxic equivalent (HEH-TEQ) concentrations. The analysis indicated that, when using avian toxic equivalency factors (TEFs) recommended by the WHO, the relative contribution of TCDD (1.1,10.2%) to total WHO-TEQ concentration was higher than that of PeCDF (1.7,2.9%). These results differ from the relative contribution of TCDD and PeCDF when HEH RePs were used; PeCDF was a major contributor (36.5,52.9%) to total HEH-TEQ concentrations, whereas the contribution by TCDD (1.2,10.3%) was less than that of PeCDF. The WHO TEFs for avian species were largely derived from studies with the domestic chicken (Gallus gallus domesticus). The findings of the present study suggest that it is necessary to determine the relative potencies of DLCs in wild birds and to re-evaluate their relative contributions to the biochemical and toxic effects previously reported in herring gulls and other avian species. Environ. Toxicol. Chem. 2010;29:2088,2095. © 2010 SETAC [source] Altering cytochrome P4501A activity affects polycyclic aromatic hydrocarbon metabolism and toxicity in rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Stephanie A. Hawkins Abstract The polycyclic aromatic hydrocarbons (PAHs) phenanthrene and retene (7-isopropyl-1-methyl phenanthrene) are lethal to rainbow trout (Oncorhynchus mykiss) larvae during chronic exposures. Phenanthrene is a low-toxicity, non-cytochrome P4501A (CYP1A),inducing compound that accumulates in fish tissues during exposure to lethal concentrations in water. Retene is a higher toxicity CYP1A-inducing compound that is not detectable in tissue at lethal exposure concentrations. The metabolism, excretion, and toxicity of retene and phenanthrene were examined in juvenile and larval rainbow trout during coexposure to the model CYP1A inducer ,-naphthoflavone (,NF), or to the inducer-inhibitor piperonyl butoxide to determine if modulating CYP1A activity affected PAH metabolism and toxicity. Phenanthrene metabolism, excretion rate, and toxicity increased with coexposure to ,NF. Piperonyl butoxide inhibited phenanthrene metabolism and reduced the excretion of all phenanthrene metabolites. As a consequence, embryo mortality rates increased but rates of sublethal effects did not. Coexposure of trout to retene and ,NF caused no change in retene metabolism and excretion, but retene toxicity increased, perhaps due to additivity. Piperonyl butoxide inhibited retene metabolism, decreased the excretion of some retene metabolites while increasing the excretion of others, and increased the toxicity of retene. These results support the role of CYP1A activity in PAH metabolism and excretion, and the role of the CYP1A-generated metabolites of PAHs in chronic toxicity to larval fish. [source] Plasma Concentrations of Risperidone and Olanzapine during Coadministration with OxcarbazepineEPILEPSIA, Issue 5 2005Maria Rosaria Muscatello Summary:,Purpose: Oxcarbazepine (OZC) is a second-generation antiepileptic drug (AED) that also may be used as a mood stabilizer. Unlike carbamazepine (CBZ), which is an inducer of the cytochrome P-450 isoforms and may accelerate the elimination of several therapeutic agents, OXC seems to have only a modest inducing action. The aim of this investigation was to evaluate the effect of a treatment with OXC on plasma concentrations of the new antipsychotics risperidone and olanzapine. Methods: OXC, at a dosage of 900,1,200 mg/day, was administered for 5 consecutive weeks to 25 outpatients, 10 men and 15 women, aged 25 to 64 years, with bipolar or schizoaffective disorder. Twelve patients were stabilized on risperidone therapy (2,6 mg/day) and 13 on olanzapine (5,20 mg/day). Steady-state plasma concentrations of risperidone and its active metabolite 9-hydroxyrisperidone (9-OH-risperidone) and olanzapine were measured by high-pressure liquid chromatography (HPLC) before addition of OXC and after 5 weeks from the start of adjunctive treatment. Results: OXC caused only minimal and no significant changes in the mean plasma levels of risperidone (from 5.6 ± 3.6 ng/ml at baseline to 4.8 ± 2.6 ng/ml at week 5), 9-OH-risperidone (from 23.6 ± 7.5 to 24.7 ± 7.4 ng/ml), and olanzapine (from 26.5 ± 5.7 ng/ml at baseline to 27.8 ± 5.1 ng/ml). OXC coadministration with either risperidone or olanzapine was well tolerated. Conclusions: Our findings indicate that OXC does not affect the elimination of risperidone and olanzapine, thus confirming its weak inducing effect on hepatic drug-metabolizing enzymes. [source] Effect of drug-induced cytotoxicity on glucose uptake in Hodgkin's lymphoma cellsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 2 2006Ursula Banning Abstract:,Background:,In Hodgkin's lymphoma, F-18-fluoro-deoxy- d -glucose positron emission tomography (FDG-PET) is used for staging and response evaluation after chemotherapy. However, drug-mediated downregulation of glucose uptake in viable Hodgkin's lymphoma cells might limit the use of FDG-PET. Methods:,We analyzed the effect of etoposide on cell viability and uptake of F-18-fluoro-deoxy- d -glucose or the glucose analog 2-[N -(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) in vitro. Results:,Etoposide induced a dose-dependent cytotoxicity in HDLM-2 cells which was significantly correlated with reduced FDG uptake. However, it also significantly increased the portion of viable cells which did not take up 2-NBDG. Interestingly, etoposide-induced cytotoxicity was mainly mediated via caspase-dependent mechanisms, whereas the cell death induced by deprivation of glucose was mediated via caspase-independent mechanisms. Conclusion:,Etoposide-mediated reduction of glucose uptake by Hodgkin's lymphoma cells is mainly caused by cell death. In a small fraction of viable cells, etoposide might downregulate glucose transporters and/or hexokinase activity and by that inhibit glucose uptake. This, however, might not lead to false-negative results of response evaluation in Hodgkin's lymphoma patients after chemotherapy, because inhibition of glucose uptake itself seems to be a strong inducer of cell death. Altogether, this study provides important in vitro evidence to clarify the mechanisms by which FDG-PET monitors the effect of anti-cancer treatment in Hodgkin's lymphoma patients. [source] The Toll-like receptor ligand MALP-2 stimulates dendritic cell maturation and modulates proteasome composition and activityEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2004Claudia Link Abstract A 2-kDa synthetic derivative of the macrophage-activating lipopeptide (MALP-2) from Mycoplasma fermentans is a potent inducer of monocytes/macrophages and improves the immunogenicity of antigens co-administered by systemic and mucosal routes. Dendritic cells (DC) are the most potent antigen-presenting cells, which are able to prime naive T cells in vivo. To elucidate the underlying mechanisms of MALP-2 adjuvanticity, we analyzed its activity on bone marrow-derived murine DC. In vitro stimulation of immature murine DC with MALP-2 resulted in the induction of maturation with up-regulated expression of MHC class II, costimulatory (CD80, CD86) and adhesion (CD40, CD54) molecules. MALP-2 also enhances the secretion of cytokines (IL-1,, IL-6 and IL-12), and increases DC stimulatory activity on naive and antigen-specific T cells. Further studies demonstrated that MALP-2 treatment of DC results in a dose-dependent shift from the protein pattern of proteasomes to immunoproteasomes (up-regulation of LMP2, LMP7 and MECL1), which correlates with an increased proteolytic activity. Thus, the adjuvanticity of MALP-2 can be mediated, at least in part, by the stimulation of DC maturation, which in turn leads to an improved antigen presentation. Therefore, MALP-2 is a promising molecule for the development of immune therapeutic or prophylactic interventions. [source] Microwave-Assisted Paal,Knorr Reaction , Three-Step Regiocontrolled Synthesis of Polysubstituted Furans, Pyrroles and ThiophenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2005Giacomo Minetto Abstract An efficient and highly versatile synthesis of furans, pyrroles and thiophenes is described. Starting from commercially available or easily prepared ,-keto esters, functional homologation provides differently substituted 1,4-diketones that can be transformed, through a microwave-assisted Paal,Knorr condensation, into the corresponding methoxycarbonyl heterocycles. The methoxycarbonyl moiety can be directly transformed into an NH2 group by hydrolysis to carboxylic acid and Curtius rearrangement or into an amide by reaction with a primary amine in the presence of Me3Al. The method is compatible with the presence of a CbzNH group so that the final heterocycle can be inserted into a peptide sequence as a turn inducer. By using this procedure, a collection of more than 60 different tetrasubstitued pyrroles or trisubstituted thiophenes has been prepared. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Solvent-Dependent Conformational Behaviour of Model Tetrapeptides Containing a Bicyclic Proline MimeticEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2004Andrea Trabocchi Abstract Two model tetrapeptides containing bicyclic analogues of either D - or L -proline were synthesised and their conformational properties were studied by NMR in different solvent systems and by molecular modelling techniques. Compound 1, with the bicyclic D -proline mimetic in the i+1 position, generated a unique trans isomer, and the peptide showed a well organised structure, in accordance with the tendency of D -proline to act as a good turn inducer with respect to its enantiomer. Peptide 2 displayed structures equilibrating from type I,II to type VI ,-turns, thus confirming the hypothesised relationship between the chirality of BGS/Bgs and proline enantiomers on nucleating compact turns. Moreover, such behaviour suggested a tool for peptidomimetic design of reverse turn peptides containing BGS/Bgs bicyclic proline mimetics, as the choice of chirality might influence the generation either of compact ,- and ,-turns or of flexible equilibrating reverse turn structures. The effect of solvent on conformational behaviour was also studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Transcriptional upregulation of inflammatory cytokines in human intestinal epithelial cells following Vibrio cholerae infectionFEBS JOURNAL, Issue 17 2007Arunava Bandyopadhaya Coordinated expression and upregulation of interleukin-1,, interleukin-1,, tumor necrosis factor-,, interleukin-6, granulocyte,macrophage colony-stimulating factor, interleukin-8, monocyte chemotactic protein-1 (MCP-1) and epithelial cell derived neutrophil activator-78, with chemoattractant and proinflammatory properties of various cytokine families, were obtained in the intestinal epithelial cell line Int407 upon Vibrio cholerae infection. These proinflammatory cytokines also showed increased expression in T84 cells, except for interleukin-6, whereas a striking dissimilarity in cytokine expression was observed in Caco-2 cells. Gene expression studies of MCP-1, granulocyte,macrophage colony-stimulating factor, interleukin-1,, interleukin-6 and the anti-inflammatory cytokine transforming growth factor-, in Int407 cells with V. cholerae culture supernatant, cholera toxin, lipopolysaccharide and ctxA mutant demonstrated that, apart from cholera toxin and lipopolysaccharide, V. cholerae culture supernatant harbors strong inducer(s) of interleukin-6 and MCP-1 and moderate inducer(s) of interleukin-1, and granulocyte,macrophage colony-stimulating factor. Cholera toxin- or lipopolysaccharide-induced cytokine expression is facilitated by activation of nuclear factor-,B (p65 and p50) and cAMP response element-binding protein in Int407 cells. Studies with ctxA mutants of V. cholerae revealed that the mutant activates the p65 subunit of nuclear factor-,B and cAMP response element-binding protein, and as such the activation is mediated by cholera toxin-independent factors as well. We conclude that V. cholerae elicits a proinflammatory response in Int407 cells that is mediated by activation of nuclear factor-,B and cAMP response element-binding protein by cholera toxin, lipopolysaccharide and/or other secreted products of V. cholerae. [source] Relationships between the ethanol utilization (alc) pathway and unrelated catabolic pathways in Aspergillus nidulansFEBS JOURNAL, Issue 17 2003Michel Flipphi The ethanol utilization pathway in Aspergillus nidulans is a model system, which has been thoroughly elucidated at the biochemical, genetic and molecular levels. Three main elements are involved: (a) high level expression of the positively autoregulated activator AlcR; (b) the strong promoters of the structural genes for alcohol dehydrogenase (alcA) and aldehyde dehydrogenase (aldA); and (c) powerful activation of AlcR by the physiological inducer, acetaldehyde, produced from growth substrates such as ethanol and l -threonine. We have previously characterized the chemical features of direct inducers of the alc regulon. These studies allowed us to predict which type of carbonyl compounds might induce the system. In this study we have determined that catabolism of different amino acids, such as l -valine, l -isoleucine, l -arginine and l -proline, produces aldehydes that are either not accumulated or fail to induce the alc system. On the other hand, catabolism of d -galacturonic acid and putrescine, during which aldehydes are transiently accumulated, gives rise to induction of the alc genes. We show that the formation of a direct inducer from carboxylic esters does not depend on alcA -encoded alcohol dehydrogenase I or on AlcR, and suggest that a cytochrome P450 might be responsible for the initial formation of a physiological aldehyde inducer. [source] Tetranectin binds hepatocyte growth factor and tissue-type plasminogen activatorFEBS JOURNAL, Issue 8 2003Uffe B. Westergaard In the search for new ligands for the plasminogen kringle 4 binding-protein tetranectin, it has been found by ligand blot analysis and ELISA that tetranectin specifically bound to the plasminogen-like hepatocyte growth factor and tissue-type plasminogen activator. The dissociation constants of these complexes were found to be within the same order of magnitude as the one for the plasminogen-tetranectin complex. The study also revealed that tetranectin did not interact with the kindred proteins: macrophage-stimulating protein, urokinase-type plasminogen activator and prothrombin. In order to examine the function of tetranectin, a kinetic analysis of the tPA-catalysed plasminogen activation was performed. The kinetic parameters of the tetranectin-stimulated enhancement of tPA were comparable to fibrinogen fragments, which are so far the best inducer of tPA-catalysed plasminogen activation. The enhanced activation was suggested to be caused by tetranectin's ability to bind and accumulate tPA in an active conformation. [source] Connection of transport and sensing by UhpC, the sensor for external glucose-6-phosphate in Escherichia coliFEBS JOURNAL, Issue 7 2003Christian Schwöppe UhpC is a membrane-bound sensor protein in Escherichia coli required for recognizing external glucose-6-phosphate (Glc6P) and induction of the transport protein UhpT. Recently, it was shown that UhpC is also able to transport Glc6P. In this study we investigated whether these transport and sensing activities are obligatorily coupled in UhpC. We expressed a His-UhpC protein in a UhpC-deficient E. coli strain and verified that this construct does not alter the basic biochemical properties of the Glc6P sensor system. The effects of arginine replacements, mutations of the central loop, and introduction of a salt bridge in UhpC on transport and sensing were compared. The exchanges R46C, R266C and R149C moderately affected transport by UhpC but strongly decreased the sensing ability. This suggested that the affinity for Glc6P as a transported substrate is uncoupled in UhpC from its affinity for Glc6P as an inducer. Four of the 11 arginine mutants showed a constitutive phenotype but had near wild-type transport activity suggesting that Glc6P can be transported by a molecule locked in the inducing conformation. Introduction of an intrahelical salt bridge increased the transport activity of UhpC but abolished sensing. Three conserved residues from the central loop were mutated and although none of these showed transport, one exhibited increased affinity for sensing. Taken together, these data show that transport by UhpC is not required for sensing, that conserved arginine residues are important for sensing and not for transport, and that residues located in the central hydrophilic loop are critical for transport and for sensing. [source] A Gene Therapy Technology-Based Biomaterial for the Trigger-Inducible Release of Biopharmaceuticals in MiceADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Michael M. Kämpf Abstract Gene therapy scientists have developed expression systems for therapeutic transgenes within patients, which must be seamlessly integrated into the patient's physiology by developing sophisticated control mechanisms to titrate expression levels of the transgenes into the therapeutic window. However, despite these efforts, gene-based medicine still faces security concerns related to the administration of the therapeutic transgene vector. Here, molecular tools developed for therapeutic transgene expression can readily be transferred to materials science to design a humanized drug depot that can be implanted into mice and enables the trigger-inducible release of a therapeutic protein in response to a small-molecule inducer. The drug depot is constructed by embedding the vascular endothelial growth factor (VEGF121) as model therapeutic protein into a hydrogel consisting of linear polyacrylamide crosslinked with a homodimeric variant of the human FK-binding protein 12 (FM), originally developed for gene therapeutic applications, as well as with dimethylsuberimidate. Administrating increasing concentrations of the inducer molecule FK506 triggers the dissociation of FM thereby loosening the hydrogel structure and releasing the VEGF121 payload in a dose-adjustable manner. Subcutaneous implantation of the drug depot into mice and subsequent administration of the inducer by injection or by oral intake triggers the release of VEGF121 as monitored in the mouse serum. This study is the first demonstration of a stimuli-responsive hydrogel that can be used in mammals to release a therapeutic protein on demand by the application of a small-molecule stimulus. This trigger-inducible release is a starting point for the further development of externally controlled drug depots for patient-compliant administration of biopharmaceuticals. [source] The epigenetic calnexin-independent state is induced in response to environmental changesFEMS YEAST RESEARCH, Issue 8 2009Renée Guérin Abstract Yeasts have evolved numerous responsive pathways to survive in fluctuating and stressful environments. The endoplasmic reticulum (ER) is sensitive to adverse conditions, which are detected by response pathways to ensure correct protein folding. Calnexin is an ER transmembrane chaperone acting in both quality control of folding and response to persistent stress. Calnexin is a key protein required for viability in certain organisms such as mammals and the fission yeast Schizosaccharomyces pombe. Nevertheless, S. pombe calnexin-independent (Cin) cells were obtained after transient expression of a particular calnexin mutant. The Cin state is dominant, is stably propagated by an epigenetic mechanism and segregates in a non-Mendelian fashion to the meiotic progeny. The nucleolar protein Cif1p was identified as an inducer of the Cin state in a previous genetic screen. Here, we report the identification of novel inducers isolated in an overexpression genetic screen: pyruvate kinase (Pyk1p) and phosphoglycerate kinase (Pgk1p). Addition of pyruvate, the end product of pyruvate kinase and glycolysis, also induced calnexin independence in a dose-dependent manner. Remarkably, growth in respiration media or cold temperatures induced the appearance of Cin cells at high frequencies. Taken together, our results indicate that the Cin state can be triggered by extracellular changes, suggesting that this state represents an epigenetic adaptative response to environmental modifications. [source] Dynamics of in vitro acquisition of resistance by Candida parapsilosis to different azolesFEMS YEAST RESEARCH, Issue 4 2009Ana Teresa Pinto e Silva Abstract Candida parapsilosis is a common isolate from clinical fungal infectious episodes. Resistance of C. parapsilosis to azoles has been increasingly reported. To analyse the development of resistance in C. parapsilosis, four azole-susceptible clinical strains and one American Type Culture Collection type strain were cultured in the presence of fluconazole, voriconazole and posaconazole at different concentrations. The isolates developed variable degrees of azole resistance according to the antifungal used. Fluconazole was the fastest inducer while posaconazole was the slowest. Fluconazole and voriconazole induced resistance to themselves and each other, but not to posaconazole. Posaconazole induced resistance to all azoles. Developed resistance was stable; it could be confirmed after 30 days of subculture in drug-free medium. Azole-resistant isolates revealed a homogeneous population structure; the role of azole transporter efflux pumps was minor after evaluation by microdilution and cytometric assays with efflux pump blockers (verapamil, ibuprofen and carbonyl cyanide 3-chloro-phenylhydrazone). We conclude that the rapid development of azole resistance occurs by a mechanism that might involve mutation of genes responsible for ergosterol biosynthesis pathway, stressed by exposure to antifungals. [source] In vitro characterization of Inocutis jamaicensis and experimental inoculation of Eucalyptus globulus standing treesFOREST PATHOLOGY, Issue 5 2009S. Lupo Summary Lesions of variable size, associated with the hymenomycete Inocutis jamaicensis, a white-rot fungus, have been observed on the stems of Eucalyptus globulus trees in Uruguay. The aim of this study was to evaluate some ecophysiological characteristics of I. jamaicensis and assess its ability to colonize E. globulus trees of two different seed origins (Geeveston and Jeeralang) and the clone, 334-1-AR, obtained by micropropagation (ENCE, Spain). The growth of an I. jamaicensis isolate (MVHC11379) was evaluated at 25°C in a medium with a water potential of 0 (, = 0). The growth rate did not vary significantly with a growth medium pH of between 4 and 7. I. jamaicensis showed no growth at either 5 or 37°C at any pH or , tested. Weight loss of heartwood and sapwood of different plant provenances inoculated with I. jamaicensis under laboratory conditions was evaluated, and significant differences observed. Lignin-modifying enzyme activity was evaluated in culture medium with or without E. globulus sawdust as substrate or inducer. Laccase activity was observed with sawdust and manganese peroxidase activity with and without sawdust. Only slight activity of aryl-alcohol oxidase and lignin peroxidase was detected without sawdust. Experimental inoculation with I. jamaicensis of 3-year-old Geeveston and Jeeralang, and of 4-year-old 334-1-AR stems, resulted in successful fungal colonization of 56% of the 334-1-AR, 50% of Geeveston and 25% of Jeeralang trees. Only the heartwood was decayed. In 334-1-AR, the rotted wood was delimited by a reaction zone. Wood characteristics and the ability of I. jamaicensis to overcome the chemical reactions in the tree could partially explain differences in susceptibility to the fungus among provenances observed under natural and laboratory conditions. [source] Mutant protein kinase C gamma that causes spinocerebellar ataxia type 14 (SCA14) is selectively degraded by autophagyGENES TO CELLS, Issue 5 2010Kazuhiro Yamamoto Several causal missense mutations in the protein kinase C, (,PKC) gene have been found in spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously showed that mutant ,PKC found in SCA14 is susceptible to aggregation and causes apoptosis. Aggregation of misfolded proteins is generally involved in the pathogenesis of many neurodegenerative diseases. Growing evidence indicates that macroautophagy (autophagy) is important for the degradation of misfolded proteins and the prevention of neurodegenerative diseases. In the present study, we examined whether autophagy is involved in the degradation of the mutant ,PKC that causes SCA14. Mutant ,PKC-GFP was transiently expressed in SH-SY5Y cells by using an adenoviral tetracycline-regulated system. Subsequently, temporal changes in clearance of aggregates and degradation of ,PKC-GFP were evaluated. Rapamycin, an autophagic inducer, accelerated clearance of aggregates and promoted degradation of mutant ,PKC-GFP, but it did not affect degradation of wild-type ,PKC-GFP. These effects of rapamycin were not observed in embryonic fibroblast cells from Atg5-deficient mice, which are not able to perform autophagy. Furthermore, lithium, another type of autophagic inducer, also promoted the clearance of mutant ,PKC aggregates. These results indicate that autophagy contributes to the degradation of mutant ,PKC, suggesting that autophagic inducers could provide therapeutic potential for SCA14. [source] Microglial expression of ,v,3 and ,v,5 integrins is regulated by cytokines and the extracellular matrix: ,5 Integrin null microglia show no defects in adhesion or MMP-9 expression on vitronectinGLIA, Issue 7 2009Richard Milner Abstract As the primary immune effector cells in the CNS, microglia play a central role in regulating inflammation. The extracellular matrix (ECM) protein vitronectin is a strong inducer of microglial activation, switching microglia from a resting into an activated potentially destructive phenotype. As the activating effect of vitronectin is mediated by ,v integrins, the aim of the current study was to evaluate the requirement of the ,v,5 integrin in mediating microglial adhesion and activation to vitronectin, by studying these events in ,5 integrin-null murine microglia. Surprisingly, ,5 integrin null microglia were not defective in adhesion to vitronectin. Further analysis showed that microglia express the ,v,3 integrin, in addition to ,v,5. Flow cytometry revealed that microglial ,v integrin expression is regulated by cytokines and ECM proteins. ,v,3 integrin expression was downregulated by IFN-,, TNF, LPS, and TGF-,1. ,v,5 expression was also reduced by IFN-,, TNF, and LPS, but strongly increased by the antiactivating factors TGF-,1 and laminin. Gel zymography revealed that ,5 integrin null microglia showed no deficiency in their expression of matrix metalloproteinase (MMP)-9 in response to vitronectin. Taken together, these data show that microglia express two different ,v integrins, ,v,3 and ,v,5, and that expression of these integrins is independently regulated by cytokines and ECM proteins. Furthermore, it reveals that the ,v,5 integrin is not essential for mediating microglial adhesion and MMP-9 expression in response to vitronectin. © 2008 Wiley-Liss, Inc. [source] Tumor necrosis factor,like weak inducer of apoptosis is a mitogen for liver progenitor cells,,HEPATOLOGY, Issue 1 2010Janina E. E. Tirnitz-Parker Liver progenitor cells (LPCs) represent the cell compartment facilitating hepatic regeneration during chronic injury while hepatocyte-mediated repair mechanisms are compromised. LPC proliferation is frequently observed in human chronic liver diseases such as hereditary hemochromatosis, fatty liver disease, and chronic hepatitis. In vivo studies have suggested that a tumor necrosis factor family member, tumor necrosis factor,like weak inducer of apoptosis (TWEAK), is promitotic for LPCs; whether it acts directly is not known. In our murine choline-deficient, ethionine-supplemented (CDE) model of chronic liver injury, TWEAK receptor [fibroblast growth factor-inducible 14 (Fn14)] expression in the whole liver is massively upregulated. We therefore set out to investigate whether TWEAK/Fn14 signaling promotes the regenerative response in CDE-induced chronic liver injury by mitotic stimulation of LPCs. Fn14 knockout (KO) mice showed significantly reduced LPC numbers and attenuated inflammation and cytokine production after 2 weeks of CDE feeding. The close association between LPC proliferation and activation of hepatic stellate cells in chronic liver injury prompted us to investigate whether fibrogenesis was also modulated in Fn14 KO animals. Collagen deposition and expression of key fibrogenesis mediators were reduced after 2 weeks of injury, and this correlated with LPC numbers. Furthermore, the injection of 2-week-CDE-treated wildtype animals with TWEAK led to increased proliferation of nonparenchymal pan cytokeratin,positive cells. Stimulation of an Fn14-positive LPC line with TWEAK led to nuclear factor kappa light chain enhancer of activated B cells (NF,B) activation and dose-dependent proliferation, which was diminished after targeting of the p50 NF,B subunit by RNA interference. Conclusion: TWEAK acts directly and stimulates LPC mitosis in an Fn14-dependent and NF,B-dependent fashion, and signaling via this pathway mediates the LPC response to CDE-induced injury and regeneration. (HEPATOLOGY 2010) [source] HuR regulates gap junctional intercellular communication by controlling ,-catenin levels and adherens junction integrity,HEPATOLOGY, Issue 5 2009Niloofar Ale-Agha Gap junctional intercellular communication (GJIC) plays a critical role in the regulation of tissue homeostasis and carcinogenesis and is modulated by the levels, subcellular localization, and posttranslational modification of gap junction proteins, the connexins (Cx). Here, using oval cell-like rat liver epithelial cells, we demonstrate that the RNA-binding protein HuR promotes GJIC through two mechanisms. First, HuR silencing lowered the levels of Cx43 protein and Cx43 messenger RNA (mRNA), and decreased Cx43 mRNA half-life. This regulation was likely due to the direct stabilization of Cx43 mRNA by HuR, because HuR associated directly with Cx43 mRNA, a transcript that bears signature adenylate-uridylate-rich (AU-rich) and uridylate-rich (U-rich) sequences in its 3,-untranslated region. Second, HuR silencing reduced both half-life and the levels of ,-catenin mRNA, also a target of HuR; accordingly, HuR silencing lowered the levels of whole-cell and membrane-associated ,-catenin. Coimmunoprecipitation experiments showed a direct interaction between ,-catenin and Cx43. Small interfering RNA (siRNA)-mediated depletion of ,-catenin recapitulated the effects of decreasing HuR levels: it attenuated GJIC, decreased Cx43 levels, and redistributed Cx43 to the cytoplasm, suggesting that depletion of ,-catenin in HuR-silenced cells contributed to lowering Cx43 levels at the membrane. Finally, HuR was demonstrated to support GJIC after exposure to a genotoxic agent, doxorubicin, or an inducer of differentiation processes, retinoic acid, thus pointing to a crucial role of HuR in the cellular response to stress and in physiological processes modulated by GJIC. Conclusion: HuR promotes gap junctional intercellular communication in rat liver epithelial cells through two related regulatory processes, by enhancing the expression of Cx43 and by increasing the expression of ,-catenin, which, in turn, interacts with Cx43 and is required for proper positioning of Cx43 at the plasma membrane. (HEPATOLOGY 2009.) [source] | |||||||||||||||||||||||||||||||||||||