Ropizine concurrently enhances and inhibits [3H] dextromethorpan binding to different structures of the guinea pig brain: Autoradiographic evidence for multiple binding sites

International Nuclear Information System (INIS)

Canoll, P.D.; Smith, P.R.; and Musacchio, J.M.

1990-01-01

Ropizine produces a simultaneous enhancement and inhibition of [ 3 H] dextromethorphan (DM) high-affinity binding to different areas of the guinea pig brain. These results imply that there are two distinct types of high-affinity [ 3 H]DM binding sites, which are present in variable proportions in different brain structures. The ropizine-enhances [ 3 H]DM binding type was preferentially inhibited by (+)-pentazocine. This is consistent with the presumption that the (+)-pentazocine-sensitive site is identical with the common site for DM and 3-(-3-Hydroxphenyl)-N-(1-propyl)piperidine ((+)-3-PPP). The second binding type, which is inhibited by ropizine and is not so sensitive to (+)- pentazocine, has not been fully characterized. This study demonstrates that the biphasic effects to ropizine are due, at least in part, to the effects of ropizine on two different types of [ 3 H]DM binding sites. However, this study does not rule out that the common DM/(+)-3-PPP site also might be inhibited by higher concentrations of ropizine

Identification of an allosteric binding site for RORγt inhibition

Energy Technology Data Exchange (ETDEWEB)

Scheepstra, Marcel; Leysen, Seppe; vanAlmen, Geert C.; Miller, J. Richard; Piesvaux, Jennifer; Kutilek, Victoria; van Eenennaam, Hans; Zhang, Hongjun; Barr, Kenneth; Nagpal, Sunil; Soisson, Stephen M.; Kornienko, Maria; Wiley, Kristen; Elsen, Nathaniel; Sharma, Sujata; Correll, Craig C.; Trotter, B. Wesley; van der Stelt, Mario; Oubrie, Arthur; Ottmann, Christian; Parthasarathy, Gopal; Brunsveld, Luc (Merck); (Eindhoven)

2015-12-07

RORγt is critical for the differentiation and proliferation of Th17 cells associated with several chronic autoimmune diseases. We report the discovery of a novel allosteric binding site on the nuclear receptor RORγt. Co-crystallization of the ligand binding domain (LBD) of RORγt with a series of small-molecule antagonists demonstrates occupancy of a previously unreported allosteric binding pocket. Binding at this non-canonical site induces an unprecedented conformational reorientation of helix 12 in the RORγt LBD, which blocks cofactor binding. The functional consequence of this allosteric ligand-mediated conformation is inhibition of function as evidenced by both biochemical and cellular studies. RORγt function is thus antagonized in a manner molecularly distinct from that of previously described orthosteric RORγt ligands. This brings forward an approach to target RORγt for the treatment of Th17-mediated autoimmune diseases. The elucidation of an unprecedented modality of pharmacological antagonism establishes a mechanism for modulation of nuclear receptors.

Molecular definition of multiple sites of antibody inhibition of malaria transmission-blocking vaccine antigen Pfs25.

Science.gov (United States)

Scally, Stephen W; McLeod, Brandon; Bosch, Alexandre; Miura, Kazutoyo; Liang, Qi; Carroll, Sean; Reponen, Sini; Nguyen, Ngan; Giladi, Eldar; Rämisch, Sebastian; Yusibov, Vidadi; Bradley, Allan; Lemiale, Franck; Schief, William R; Emerling, Daniel; Kellam, Paul; King, C Richter; Julien, Jean-Philippe

2017-11-16

The Plasmodium falciparum Pfs25 protein (Pfs25) is a leading malaria transmission-blocking vaccine antigen. Pfs25 vaccination is intended to elicit antibodies that inhibit parasite development when ingested by Anopheles mosquitoes during blood meals. The Pfs25 three-dimensional structure has remained elusive, hampering a molecular understanding of its function and limiting immunogen design. We report six crystal structures of Pfs25 in complex with antibodies elicited by immunization via Pfs25 virus-like particles in human immunoglobulin loci transgenic mice. Our structural findings reveal the fine specificities associated with two distinct immunogenic sites on Pfs25. Importantly, one of these sites broadly overlaps with the epitope of the well-known 4B7 mouse antibody, which can be targeted simultaneously by antibodies that target a non-overlapping site to additively increase parasite inhibition. Our molecular characterization of inhibitory antibodies informs on the natural disposition of Pfs25 on the surface of ookinetes and provides the structural blueprints to design next-generation immunogens.

Inhibition of cortiocosteroidogenesis by delta-9-tetrahydrocannabinol.

Science.gov (United States)

Warner, W; Harris, L S; Carchman, R A

1977-12-01

ACTH, cholera toxin, cyclic AMP but not pregnenolone-induced steroidogenesis in Y-1 functional mouse adrenal tumor cells was significantly inhibited by delta-9-tetrahydrocannabinol, cannabidiol, and cannabinol. The inhibition of steroidogenesis could not be correlated with a general depression in cell function or viability. The data suggest that cannabinoids inhibit corticosteroidogenesis at a site between the synthesis of cAMP and of pregnenolone.

Inhibition of Lassa virus glycoprotein cleavage and multicycle replication by site 1 protease-adapted alpha(1-antitrypsin variants.

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Anna Maisa

2009-06-01

Full Text Available Proteolytic processing of the Lassa virus envelope glycoprotein precursor GP-C by the host proprotein convertase site 1 protease (S1P is a prerequisite for the incorporation of the subunits GP-1 and GP-2 into viral particles and, hence, essential for infectivity and virus spread. Therefore, we tested in this study the concept of using S1P as a target to block efficient virus replication.We demonstrate that stable cell lines inducibly expressing S1P-adapted alpha(1-antitrypsin variants inhibit the proteolytic maturation of GP-C. Introduction of the S1P recognition motifs RRIL and RRLL into the reactive center loop of alpha(1-antitrypsin resulted in abrogation of GP-C processing by endogenous S1P to a similar level observed in S1P-deficient cells. Moreover, S1P-specific alpha(1-antitrypsins significantly inhibited replication and spread of a replication-competent recombinant vesicular stomatitis virus expressing the Lassa virus glycoprotein GP as well as authentic Lassa virus. Inhibition of viral replication correlated with the ability of the different alpha(1-antitrypsin variants to inhibit the processing of the Lassa virus glycoprotein precursor.Our data suggest that glycoprotein cleavage by S1P is a promising target for the development of novel anti-arenaviral strategies.

Reactor design for minimizing product inhibition during enzymatic lignocellulose hydrolysis: I. Significance and mechanism of cellobiose and glucose inhibition on cellulolytic enzymes

DEFF Research Database (Denmark)

Andric, Pavle; Meyer, Anne S.; Jensen, Peter Arendt

2010-01-01

Achievement of efficient enzymatic degradation of cellulose to glucose is one of the main prerequisites and one of the main challenges in the biological conversion of lignocellulosic biomass to liquid fuels and other valuable products. The specific inhibitory interferences by cellobiose and glucose...... on enzyme-catalyzed cellulose hydrolysis reactions impose significant limitations on the efficiency of lignocellulose conversion especially at high-biomass dry matter conditions. To provide the base for selecting the optimal reactor conditions, this paper reviews the reaction kinetics, mechanisms......, and significance of this product inhibition, notably the cellobiose and glucose inhibition, on enzymatic cellulose hydrolysis. Particular emphasis is put on the distinct complexity of cellulose as a substrate, the multi-enzymatic nature of the cellulolytic degradation, and the particular features of cellulase...

Specific mixing facilitates the comparative quantification of phosphorylation sites with significant dysregulations

Energy Technology Data Exchange (ETDEWEB)

Liu, Jing [Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R& A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xu, Bo [Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R& A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023 (China); Liu, Zheyi; Dong, Mingming; Mao, Jiawei; Zhou, Ye; Chen, Jin [Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R& A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Fangjun, E-mail: wangfj@dicp.ac.cn [Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R& A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023 (China); Zou, Hanfa [Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R& A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023 (China)

2017-01-15

Mass spectrometry (MS) based quantitative analyses of proteome and proteome post-translational modifications (PTMs) play more and more important roles in biological, pharmaceutical and clinical studies. However, it is still a big challenge to accurately quantify the proteins or proteins PTM sites with extreme relative abundances in comparative protein samples, such as the significantly dysregulated ones. Herein, a novel quantification strategy, Mixing at Specific Ratio (MaSR) before isotope labeling, had been developed to improve the quantification accuracy and coverage of extreme proteins and protein phosphorylation sites. Briefly, the comparative protein samples were firstly mixed together at specific ratios of 9:1 and 1:9 (w/w), followed with mass differentiate light and heavy isotope labeling, respectively. The extreme proteins and protein phosphorylation sites, even if the newly expressed or disappeared ones, could be accurately quantified due to all of the proteins' relative abundances had been adjusted to 2 orders of magnitude (1/9-9) by this strategy. The number of quantified phosphorylation sites with more than 20 folds changes was improved about 10 times in comparative quantification of pervanadate stimulated phosphoproteome of HeLa cells, and 134 newly generated and 21 disappeared phosphorylation sites were solely quantified by the MaSR strategy. The significantly up-regulated phosphorylation sites were mainly involved in the key phosphoproteins regulating the insulin-related pathways, such as PI3K-AKT and RAS-MAPK pathways. Therefore, the MaSR strategy exhibits as a promising way in elucidating the biological processes with significant dysregulations. - Highlights: • All the proteins' relative abundances were adjusted into 2 orders of magnitude (1/9-9). • The quantification accuracy and coverage of extreme proteins and protein phosphorylation sites had been improved. • The newly expressed or disappeared proteins and protein

Inhibition of human copper trafficking by a small molecule significantly attenuates cancer cell proliferation

Science.gov (United States)

Wang, Jing; Luo, Cheng; Shan, Changliang; You, Qiancheng; Lu, Junyan; Elf, Shannon; Zhou, Yu; Wen, Yi; Vinkenborg, Jan L.; Fan, Jun; Kang, Heebum; Lin, Ruiting; Han, Dali; Xie, Yuxin; Karpus, Jason; Chen, Shijie; Ouyang, Shisheng; Luan, Chihao; Zhang, Naixia; Ding, Hong; Merkx, Maarten; Liu, Hong; Chen, Jing; Jiang, Hualiang; He, Chuan

2015-12-01

Copper is a transition metal that plays critical roles in many life processes. Controlling the cellular concentration and trafficking of copper offers a route to disrupt these processes. Here we report small molecules that inhibit the human copper-trafficking proteins Atox1 and CCS, and so provide a selective approach to disrupt cellular copper transport. The knockdown of Atox1 and CCS or their inhibition leads to a significantly reduced proliferation of cancer cells, but not of normal cells, as well as to attenuated tumour growth in mouse models. We show that blocking copper trafficking induces cellular oxidative stress and reduces levels of cellular ATP. The reduced level of ATP results in activation of the AMP-activated protein kinase that leads to reduced lipogenesis. Both effects contribute to the inhibition of cancer cell proliferation. Our results establish copper chaperones as new targets for future developments in anticancer therapies.

Tiron Inhibits UVB-Induced AP-1 Binding Sites Transcriptional Activation on MMP-1 and MMP-3 Promoters by MAPK Signaling Pathway in Human Dermal Fibroblasts.

Directory of Open Access Journals (Sweden)

Jing Lu

Full Text Available Recent research found that Tiron was an effective antioxidant that could act as the intracellular reactive oxygen species (ROS scavenger or alleviate the acute toxic metal overload in vivo. In this study, we investigated the inhibitory effect of Tiron on matrix metalloproteinase (MMP-1 and MMP-3 expression in human dermal fibroblast cells. Western blot and ELISA analysis revealed that Tiron inhibited ultraviolet B (UVB-induced protein expression of MMP-1 and MMP-3. Real-time quantitative PCR confirmed that Tiron could inhibit UVB-induced mRNA expression of MMP-1 and MMP-3. Furthermore, Tiron significantly blocked UVB-induced activation of the MAPK signaling pathway and activator protein (AP-1 in the downstream of this transduction pathway in fibroblasts. Through the AP-1 binding site mutation, it was found that Tiron could inhibit AP-1-induced upregulation of MMP-1 and MMP-3 expression through blocking AP-1 binding to the AP-1 binding sites in the MMP-1 and MMP-3 promoter region. In conclusion, Tiron may be a novel antioxidant for preventing and treating skin photoaging UV-induced.

Significance of bacterial flora in abdominal irradiation-induced inhibition of lung metastases

International Nuclear Information System (INIS)

Matsumoto, T.; Ando, K.; Koike, S.

1988-01-01

We have previously reported that abdominal irradiation prior to i.v. injection of syngeneic tumor cells reduced metastases in lung. Our report described an investigation of the significance of intestinal organisms in the radiation effect. We found that eliminating intestinal organisms with antibiotics totally abolished the radiation effect. Monoassociation of germ-free mice revealed that the radiation effect was observable only for Enterobacter cloacae, never for Streptococcus faecium, Bifidobacterium adlesentis, or Escherichia coli. After abdominal irradiation of regular mice, E. cloacae multiplied in cecal contents, adhered to mucous membranes, invaded the cecal wall, and translocated to mesenteric lymph nodes. Intravenous administration of E. cloacae in place of abdominal irradiation inhibited metastases. E. cloacae-monoassociated mice developed fewer metastases than germ-free mice, and the reduction was further enhanced by abdominal irradiation. We concluded that abdominal irradiation caused the invasion of E. cloacae from the mucous membrane of the intestine and inhibited formation of lung metastases

Insights into significance of combined inhibition of MEK and m-TOR signalling output in KRAS mutant non-small-cell lung cancer.

Science.gov (United States)

Broutin, Sophie; Stewart, Adam; Thavasu, Parames; Paci, Angelo; Bidart, Jean-Michel; Banerji, Udai

2016-08-23

We aimed to understand the dependence of MEK and m-TOR inhibition in EGFR(WT)/ALK(non-rearranged) NSCLC cell lines. In a panel of KRAS(M) and KRAS(WT) NSCLC cell lines, we determined growth inhibition (GI) following maximal reduction in p-ERK and p-S6RP caused by trametinib (MEK inhibitor) and AZD2014 (m-TOR inhibitor), respectively. GI caused by maximal m-TOR inhibition was significantly greater than GI caused by maximal MEK inhibition in the cell line panel (52% vs 18%, PTOR compared with maximal m-TOR+MEK inhibition. However, GI caused by the combination was significantly greater in the KRAS(M) cell lines (79% vs 61%, P=0.017). m-TOR inhibition was more critical to GI than MEK inhibition in EGFR(WT)/ALK(non-rearranged) NSCLC cells. The combination of MEK and m-TOR inhibition was most effective in KRAS(M) cells.

Target-site resistance to acetolactate synthase (ALS)-inhibiting herbicides in Amaranthus palmeri from Argentina.

Science.gov (United States)

Larran, Alvaro S; Palmieri, Valeria E; Perotti, Valeria E; Lieber, Lucas; Tuesca, Daniel; Permingeat, Hugo R

2017-12-01

Herbicide-resistant weeds are a serious problem worldwide. Recently, two populations of Amaranthus palmeri with suspected cross-resistance to acetolactate synthase (ALS)-inhibiting herbicides (R1 and R2) were found by farmers in two locations in Argentina (Vicuña Mackenna and Totoras, respectively). We conducted studies to confirm and elucidate the mechanism of resistance. We performed in vivo dose-response assays, and confirmed that both populations had strong resistance to chlorimuron-ethyl, diclosulam and imazethapyr when compared with a susceptible population (S). In vitro ALS activity inhibition tests only indicated considerable resistance to imazethapyr and chlorimuron-ethyl, indicating that other non-target mechanisms could be involved in diclosulam resistance. Subsequently, molecular analysis of als nucleotide sequences revealed three single base-pair mutations producing substitutions in amino acids previously associated with resistance to ALS inhibitors, A122, W574, and S653. This is the first report of als resistance alleles in A. palmeri in Argentina. The data support the involvement of a target-site mechanism of resistance to ALS-inhibiting herbicides. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Modulation of post-stroke degenerative and regenerative processes and subacute protection by site-targeted inhibition of the alternative pathway of complement.

Science.gov (United States)

Alawieh, Ali; Elvington, Andrew; Zhu, Hong; Yu, Jin; Kindy, Mark S; Atkinson, Carl; Tomlinson, Stephen

2015-12-30

Complement promotes neuroinflammation and injury in models of stroke. However, complement is also being increasingly implicated in repair and regeneration after central nervous system (CNS) injury, and some complement deficiencies have been shown to provide acute, but not subacute, protection after murine stroke. Here, we investigate the dual role of complement in injury and repair after cerebral ischemia and reperfusion. We used complement-deficient mice and different complement inhibitors in a model of transient middle cerebral artery occlusion to investigate complement-dependent cellular and molecular changes that occur through the subacute phase after stroke. C3 deficiency and site-targeted complement inhibition with either CR2-Crry (inhibits all pathways) or CR2-fH (inhibits alternative pathway) significantly reduced infarct size, reduced apoptotic cell death, and improved neurological deficit score in the acute phase after stroke. However, only in CR2-fH-treated mice was there sustained protection with no evolution of injury in the subacute phase. Whereas both inhibitors significantly reduced microglia/macrophage activation and astrogliosis in the subacute phase, only CR2-fH improved neurological deficit and locomotor function, maintained neurogenesis markers, enhanced neuronal migration, and increased VEGF expression. These findings in CR2-fH-treated mice correlated with improved performance in spatial learning and passive avoidance tasks. The complement anaphylatoxins have been implicated in repair and regenerative mechanisms after CNS injury, and in this context CR2-fH significantly reduced, but did not eliminate the generation of C5a within the brain, unlike CR2-Crry that completely blocked C5a generation. Gene expression profiling revealed that CR2-fH treatment downregulated genes associated with apoptosis, TGFβ signaling, and neutrophil activation, and decreased neutrophil infiltration was confirmed by immunohistochemistry. CR2-fH upregulated genes for

Graphene oxide significantly inhibits cell growth at sublethal concentrations by causing extracellular iron deficiency.

Science.gov (United States)

Yu, Qilin; Zhang, Bing; Li, Jianrong; Du, Tingting; Yi, Xiao; Li, Mingchun; Chen, Wei; Alvarez, Pedro J J

Graphene oxide (GO)-based materials are increasingly being used in medical materials and consumer products. However, their sublethal effects on biological systems are poorly understood. Here, we report that GO (at 10 to 160 mg/L) induced significant inhibitory effects on the growth of different unicellular organisms, including eukaryotes (i.e. Saccharomyces cerevisiae, Candida albicans, and Komagataella pastoris) and prokaryotes (Pseudomonas fluorescens). Growth inhibition could not be explained by commonly reported cytotoxicity mechanisms such as plasma membrane damage or oxidative stress. Based on transcriptomic analysis and measurement of extra- and intracellular iron concentrations, we show that the inhibitory effect of GO was mainly attributable to iron deficiency caused by binding to the O-functional groups of GO, which sequestered iron and disrupted iron-related physiological and metabolic processes. This inhibitory mechanism was corroborated with supplementary experiments, where adding bathophenanthroline disulfonate-an iron chelating agent-to the culture medium exerted similar inhibition, whereas removing surface O-functional groups of GO decreased iron sequestration and significantly alleviated the inhibitory effect. These findings highlight a potential indirect detrimental effect of nanomaterials (i.e. scavenging of critical nutrients), and encourage research on potential biomedical applications of GO-based materials to sequester iron and enhance treatment of iron-dependent diseases such as cancer and some pathogenic infections.

Molecular modeling study on the allosteric inhibition mechanism of HIV-1 integrase by LEDGF/p75 binding site inhibitors.

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Weiwei Xue

Full Text Available HIV-1 integrase (IN is essential for the integration of viral DNA into the host genome and an attractive therapeutic target for developing antiretroviral inhibitors. LEDGINs are a class of allosteric inhibitors targeting LEDGF/p75 binding site of HIV-1 IN. Yet, the detailed binding mode and allosteric inhibition mechanism of LEDGINs to HIV-1 IN is only partially understood, which hinders the structure-based design of more potent anti-HIV agents. A molecular modeling study combining molecular docking, molecular dynamics simulation, and binding free energy calculation were performed to investigate the interaction details of HIV-1 IN catalytic core domain (CCD with two recently discovered LEDGINs BI-1001 and CX14442, as well as the LEDGF/p75 protein. Simulation results demonstrated the hydrophobic domain of BI-1001 and CX14442 engages one subunit of HIV-1 IN CCD dimer through hydrophobic interactions, and the hydrophilic group forms hydrogen bonds with HIV-1 IN CCD residues from other subunit. CX14442 has a larger tert-butyl group than the methyl of BI-1001, and forms better interactions with the highly hydrophobic binding pocket of HIV-1 IN CCD dimer interface, which can explain the stronger affinity of CX14442 than BI-1001. Analysis of the binding mode of LEDGF/p75 with HIV-1 IN CCD reveals that the LEDGF/p75 integrase binding domain residues Ile365, Asp366, Phe406 and Val408 have significant contributions to the binding of the LEDGF/p75 to HIV1-IN. Remarkably, we found that binding of BI-1001 and CX14442 to HIV-1 IN CCD induced the structural rearrangements of the 140 s loop and oration displacements of the side chains of the three conserved catalytic residues Asp64, Asp116, and Glu152 located at the active site. These results we obtained will be valuable not only for understanding the allosteric inhibition mechanism of LEDGINs but also for the rational design of allosteric inhibitors of HIV-1 IN targeting LEDGF/p75 binding site.

Adenovirus delivered short hairpin RNA targeting a conserved site in the 5' non-translated region inhibits all four serotypes of dengue viruses.

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Anil Babu Korrapati

Full Text Available BACKGROUND: Dengue is a mosquito-borne viral disease caused by four closely related serotypes of Dengue viruses (DENVs. This disease whose symptoms range from mild fever to potentially fatal haemorrhagic fever and hypovolemic shock, threatens nearly half the global population. There is neither a preventive vaccine nor an effective antiviral therapy against dengue disease. The difference between severe and mild disease appears to be dependent on the viral load. Early diagnosis may enable timely therapeutic intervention to blunt disease severity by reducing the viral load. Harnessing the therapeutic potential of RNA interference (RNAi to attenuate DENV replication may offer one approach to dengue therapy. METHODOLOGY/PRINCIPAL FINDINGS: We screened the non-translated regions (NTRs of the RNA genomes of representative members of the four DENV serotypes for putative siRNA targets mapping to known transcription/translation regulatory elements. We identified a target site in the 5' NTR that maps to the 5' upstream AUG region, a highly conserved cis-acting element essential for viral replication. We used a replication-defective human adenovirus type 5 (AdV5 vector to deliver a short-hairpin RNA (shRNA targeting this site into cells. We show that this shRNA matures to the cognate siRNA and is able to inhibit effectively antigen secretion, viral RNA replication and infectious virus production by all four DENV serotypes. CONCLUSION/SIGNIFICANCE: The data demonstrate the feasibility of using AdV5-mediated delivery of shRNAs targeting conserved sites in the viral genome to achieve inhibition of all four DENV serotypes. This paves the way towards exploration of RNAi as a possible therapeutic strategy to curtail DENV infection.

Inhibition of sortase A by chalcone prevents Listeria monocytogenes infection.

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Li, Hongen; Chen, Yutao; Zhang, Bing; Niu, Xiaodi; Song, Meng; Luo, Zhaoqing; Lu, Gejin; Liu, Bowen; Zhao, Xiaoran; Wang, Jianfeng; Deng, Xuming

2016-04-15

The critical role of sortase A in gram-positive bacterial pathogenicity makes this protein a good potential target for antimicrobial therapy. In this study, we report for the first time the crystal structure of Listeria monocytogenes sortase A and identify the active sites that mediate its transpeptidase activity. We also used a sortase A (SrtA) enzyme activity inhibition assay, simulation, and isothermal titration calorimetry analysis to discover that chalcone, an agent with little anti-L. monocytogenes activity, could significantly inhibit sortase A activity with an IC50 of 28.41 ± 5.34 μM by occupying the active site of SrtA. The addition of chalcone to a co-culture of L. monocytogenes and Caco-2 cells significantly inhibited bacterial entry into the cells and L. monocytogenes-mediated cytotoxicity. Additionally, chalcone treatment decreased the mortality of infected mice, the bacterial burden in target organs, and the pathological damage to L. monocytogenes-infected mice. In conclusion, these findings suggest that chalcone is a promising candidate for the development of treatment against L. monocytogenes infection. Copyright © 2016 Elsevier Inc. All rights reserved.

Aspirin inhibition of platelet deposition at angioplasty sites: demonstration by platelet scintigraphy

International Nuclear Information System (INIS)

Cuningham, D.A.; Kumar, B.; Siegel, B.A.; Gilula, L.A.; Totty, W.G.; Welch, M.J.

1984-01-01

In-111 platelet scintigraphy was used to evaluate the effects of prior aspirin administration on the accumulation of In-111-labeled autologous platelets at sites of arterial injury resulting from iliac, femoral, or popliteal transluminal angioplasty in a nonrandomized study of 17 men. The degree of platelet localization at angioplasty sites was significantly less in nine men who had received aspirin in varying doses within the 4 days before angioplasty than in eight men who had not received aspirin for at least two weeks. The results suggest that aspirin treatment before angioplasty limits the early platelet deposition at the angioplasty site in men

Heparin octasaccharide decoy liposomes inhibit replication of multiple viruses

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Hendricks, Gabriel L.; Velazquez, Lourdes; Pham, Serena; Qaisar, Natasha; Delaney, James C.; Viswanathan, Karthik; Albers, Leila; Comolli, James C.; Shriver, Zachary; Knipe, David M.; Kurt-Jones, Evelyn A.; Fygenson, Deborah K.; Trevejo, Jose M.

2016-01-01

Heparan sulfate (HS) is a ubiquitous glycosaminoglycan that serves as a cellular attachment site for a number of significant human pathogens, including respiratory syncytial virus (RSV), human parainfluenza virus 3 (hPIV3), and herpes simplex virus (HSV). Decoy receptors can target pathogens by binding to the receptor pocket on viral attachment proteins, acting as ‘molecular sinks’ and preventing the pathogen from binding to susceptible host cells. Decoy receptors functionalized with HS could bind to pathogens and prevent infection, so we generated decoy liposomes displaying HS-octasaccharide (HS-octa). These decoy liposomes significantly inhibited RSV, hPIV3, and HSV infectivity in vitro to a greater degree than the original HS-octa building block. The degree of inhibition correlated with the density of HS-octa displayed on the liposome surface. Decoy liposomes with HS-octa inhibited infection of viruses to a greater extent than either full-length heparin or HS-octa alone. Decoy liposomes were effective when added prior to infection or following the initial infection of cells in vitro. By targeting the well-conserved receptor-binding sites of HS-binding viruses, decoy liposomes functionalized with HS-octa are a promising therapeutic antiviral agent and illustrate the utility of the liposome delivery platform. PMID:25637710

Pharmacological kynurenine 3-monooxygenase enzyme inhibition significantly reduces neuropathic pain in a rat model.

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Rojewska, Ewelina; Piotrowska, Anna; Makuch, Wioletta; Przewlocka, Barbara; Mika, Joanna

2016-03-01

Recent studies have highlighted the involvement of the kynurenine pathway in the pathology of neurodegenerative diseases, but the role of this system in neuropathic pain requires further extensive research. Therefore, the aim of our study was to examine the role of kynurenine 3-monooxygenase (Kmo), an enzyme that is important in this pathway, in a rat model of neuropathy after chronic constriction injury (CCI) to the sciatic nerve. For the first time, we demonstrated that the injury-induced increase in the Kmo mRNA levels in the spinal cord and the dorsal root ganglia (DRG) was reduced by chronic administration of the microglial inhibitor minocycline and that this effect paralleled a decrease in the intensity of neuropathy. Further, minocycline administration alleviated the lipopolysaccharide (LPS)-induced upregulation of Kmo mRNA expression in microglial cell cultures. Moreover, we demonstrated that not only indirect inhibition of Kmo using minocycline but also direct inhibition using Kmo inhibitors (Ro61-6048 and JM6) decreased neuropathic pain intensity on the third and the seventh days after CCI. Chronic Ro61-6048 administration diminished the protein levels of IBA-1, IL-6, IL-1beta and NOS2 in the spinal cord and/or the DRG. Both Kmo inhibitors potentiated the analgesic properties of morphine. In summary, our data suggest that in neuropathic pain model, inhibiting Kmo function significantly reduces pain symptoms and enhances the effectiveness of morphine. The results of our studies show that the kynurenine pathway is an important mediator of neuropathic pain pathology and indicate that Kmo represents a novel pharmacological target for the treatment of neuropathy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of lignin-derived phenolic compounds to cellulase.

Science.gov (United States)

Qin, Lei; Li, Wen-Chao; Liu, Li; Zhu, Jia-Qing; Li, Xia; Li, Bing-Zhi; Yuan, Ying-Jin

2016-01-01

Lignin-derived phenolic compounds are universal in the hydrolysate of pretreated lignocellulosic biomass. The phenolics reduce the efficiency of enzymatic hydrolysis and increase the cost of ethanol production. We investigated inhibition of phenolics on cellulase during enzymatic hydrolysis using vanillin as one of the typical lignin-derived phenolics and Avicel as cellulose substrate. As vanillin concentration increased from 0 to 10 mg/mL, cellulose conversion after 72-h enzymatic hydrolysis decreased from 53 to 26 %. Enzyme deactivation and precipitation were detected with the vanillin addition. The enzyme concentration and activity consecutively decreased during hydrolysis, but the inhibition degree, expressed as the ratio of the cellulose conversion without vanillin to the conversion with vanillin (A 0 /A), was almost independent on hydrolysis time. Inhibition can be mitigated by increasing cellulose loading or cellulase concentration. The inhibition degree showed linear relationship with the vanillin concentration and exponential relationship with the cellulose loading and the cellulase concentration. The addition of calcium chloride, BSA, and Tween 80 did not release the inhibition of vanillin significantly. pH and temperature for hydrolysis also showed no significant impact on inhibition degree. The presence of hydroxyl group, carbonyl group, and methoxy group in phenolics affected the inhibition degree. Besides phenolics concentration, other factors such as cellulose loading, enzyme concentration, and phenolic structure also affect the inhibition of cellulose conversion. Lignin-blocking agents have little effect on the inhibition effect of soluble phenolics, indicating that the inhibition mechanism of phenolics to enzyme is likely different from insoluble lignin. The inhibition of soluble phenolics can hardly be entirely removed by increasing enzyme concentration or adding blocking proteins due to the dispersity and multiple binding sites of phenolics

Novel mode of inhibition by D-tagatose 6-phosphate through a Heyns rearrangement in the active site of transaldolase B variants.

Science.gov (United States)

Stellmacher, Lena; Sandalova, Tatyana; Schneider, Sarah; Schneider, Gunter; Sprenger, Georg A; Samland, Anne K

2016-04-01

Transaldolase B (TalB) and D-fructose-6-phosphate aldolase A (FSAA) from Escherichia coli are C-C bond-forming enzymes. Using kinetic inhibition studies and mass spectrometry, it is shown that enzyme variants of FSAA and TalB that exhibit D-fructose-6-phosphate aldolase activity are inhibited covalently and irreversibly by D-tagatose 6-phosphate (D-T6P), whereas no inhibition was observed for wild-type transaldolase B from E. coli. The crystal structure of the variant TalB(F178Y) with bound sugar phosphate was solved to a resolution of 1.46 Å and revealed a novel mode of covalent inhibition. The sugar is bound covalently via its C2 atom to the ℇ-NH2 group of the active-site residue Lys132. It is neither bound in the open-chain form nor as the closed-ring form of D-T6P, but has been converted to β-D-galactofuranose 6-phosphate (D-G6P), a five-membered ring structure. The furanose ring of the covalent adduct is formed via a Heyns rearrangement and subsequent hemiacetal formation. This reaction is facilitated by Tyr178, which is proposed to act as acid-base catalyst. The crystal structure of the inhibitor complex is compared with the structure of the Schiff-base intermediate of TalB(E96Q) formed with the substrate D-fructose 6-phosphate determined to a resolution of 2.20 Å. This comparison highlights the differences in stereochemistry at the C4 atom of the ligand as an essential determinant for the formation of the inhibitor adduct in the active site of the enzyme.

Site-targeted complement inhibition by a complement receptor 2-conjugated inhibitor (mTT30) ameliorates post-injury neuropathology in mouse brains.

Science.gov (United States)

Rich, Megan C; Keene, Chesleigh N; Neher, Miriam D; Johnson, Krista; Yu, Zhao-Xue; Ganivet, Antoine; Holers, V Michael; Stahel, Philip F

2016-03-23

Intracerebral complement activation after severe traumatic brain injury (TBI) leads to a cascade of neuroinflammatory pathological sequelae that propagate host-mediated secondary brain injury and adverse outcomes. There are currently no specific pharmacological agents on the market to prevent or mitigate the development of secondary cerebral insults after TBI. A novel chimeric CR2-fH compound (mTT30) provides targeted inhibition of the alternative complement pathway at the site of tissue injury. This experimental study was designed to test the neuroprotective effects of mTT30 in a mouse model of closed head injury. The administration of 500 μg mTT30 i.v. at 1 h, 4 h and 24 h after head injury attenuated complement C3 deposition in injured brains, reduced the extent of neuronal cell death, and decreased post-injury microglial activation, compared to vehicle-injected placebo controls. These data imply that site-targeted alternative pathway complement inhibition may represent a new promising therapeutic avenue for the future management of severe TBI. Copyright © 2016. Published by Elsevier Ireland Ltd.

Active-site modification of mammalian DNA polymerase β with pyridoxal 5'-phosphate: Mechanism of inhibition and identification of lysine 71 in the deoxynucleoside triphosphate binding pocket

International Nuclear Information System (INIS)

Basu, A.; Kedar, P.; Wilson, S.H.; Modak, M.J.

1989-01-01

Pyridoxal 5'-phosphate is a potent inhibitor of the DNA polymerase activity of recombinant rat DNA polymerase β. Kinetic studies indicate that the mechanism of PLP inhibition is complex. In a lower range of PLP concentration, inhibition is competitive with respect to substrate dNTP, whereas at higher levels of PLP several forms of enzyme combine with PLP and are involved in the overall inhibition, and a possible model for these interactions during the catalytic process is suggested. Reduction of the PLP-treated enzyme with sodium [ 3 H]borohydride results in covalent incorporation of about 4 mol of PLP/mol of enzyme, and the modified enzyme is not capable of DNA polymerase activity. The presence of dNTP during the modification reaction blocks incorporation of 1 mol of PLP/mol of enzyme, and the enzyme so modified is almost fully active. This protective effect is not observed in the absence of template-primer. Tryptic peptide mapping of the PLP-modified enzyme reveals four major sites of modification. Of these four sites, only one is protected by dNTP from pyridoxylation. Sequence analysis of the tryptic peptide corresponding to the protected site reveals that it spans residues 68-80 in the amino acid sequence of the enzyme, with Lys 71 as the site of pyridoxylation. These results indicate that Lys 71 is at or near the binding pocket for the dNTP substrate

Significance of radon exposures in developing cleanup criteria for radium-contaminated soil at the Weldon Spring Site

International Nuclear Information System (INIS)

Blunt, D.L.; Peterson, J.M.; Hillman, D.J.

1993-10-01

The Weldon Spring site, located in St. Charles County, Missouri, is included on the National Priorities List (NPL) of the US Environmental Protection Agency (EPA), and the US Department of Energy (DOE) is currently conducting cleanup activities at the site. This paper discusses the significance of radon exposures that may result from radium-contaminated soil and the approach currently being taken at the Weldon Spring site to address this issue

Prevalence of Malaria, Dengue, and Chikungunya Significantly Associated with Mosquito Breeding Sites

Science.gov (United States)

Islam, Mohammad Nazrul; ZulKifle, Mohammad; Sherwani, Arish Mohammad Khan; Ghosh, Susanta Kumar; Tiwari, Satyanarayan

2011-01-01

Objectives: To observe the prevalence of malaria, dengue, and chikungunya and their association with mosquito breeding sites. Methods: The study was observational and analytical. A total of 162 houses and 670 subjects were observed during the study period. One hundred forty-two febrile patients were eligible for the study. After obtaining informed consent from all febrile patients, 140 blood samples were collected to diagnose malaria, dengue, and chikungunya. Larval samples were collected by the standard protocol that follows. Correlation of data was performed by Pearson correlation test. Results: Forty-seven blood samples were found positive: 33 for chikungunya, 3 for dengue, and 11 for malaria. Fifty-one out of 224 larval samples were found positive. Out of the 51 positive samples, 37 were positive for Aedes, 12 were positive for Anopheles, and two were positive for Culex larvae. Interpretation and Conclusion: Mosquito-borne fevers, especially malaria, dengue, and chikungunya, have shown a significant relationship with mosquito breeding sites. PMID:23610486

Sites of inhibition of mitochondrial electron transport in macrophage-injured neoplastic cells.

Science.gov (United States)

Granger, D L; Lehninger, A L

1982-11-01

Previous work has shown that injury of neoplastic cells by cytotoxic macrophages (CM) in cell culture is accompanied by inhibition of mitochondrial respiration. We have investigated the nature of this inhibition by studying mitochondrial respiration in CM-injured leukemia L1210 cells permeabilized with digitonin. CM-induced injury affects the mitochondrial respiratory chain proper. Complex I (NADH-coenzyme Q reductase) and complex II (succinate-coenzyme Q reductase) are markedly inhibited. In addition a minor inhibition of cytochrome oxidase was found. Electron transport from alpha-glycerophosphate through the respiratory chain to oxygen is unaffected and permeabilized CM-injured L1210 cells oxidizing this substrate exhibit acceptor control. However, glycerophosphate shuttle activity was found not to occur within CM-injured or uninjured L1210 cells in culture hence, alpha-glycerophosphate is apparently unavailable for mitochondrial oxidation in the intact cell. It is concluded that the failure of respiration of intact neoplastic cells injured by CM is caused by the nearly complete inhibition of complexes I and II of the mitochondrial electron transport chain. The time courses of CM-induced electron transport inhibition and arrest of L1210 cell division are examined and the possible relationship between these phenomena is discussed.

Half-of-the-sites reactivity of outer-membrane phospholipase A against an active-site-directed inhibitor.

Science.gov (United States)

Ubarretxena-Belandia, I; Cox, R C; Dijkman, R; Egmond, M R; Verheij, H M; Dekker, N

1999-03-01

The reaction of a novel active-site-directed phospholipase A1 inhibitor with the outer-membrane phospholipase A (OMPLA) was investigated. The inhibitor 1-p-nitrophenyl-octylphosphonate-2-tridecylcarbamoyl-3-et hanesulfonyl -amino-3-deoxy-sn-glycerol irreversibly inactivated OMPLA. The inhibition reaction did not require the cofactor calcium or an unprotonated active-site His142. The inhibition of the enzyme solubilized in hexadecylphosphocholine micelles was characterized by a rapid (t1/2 = 20 min) and complete loss of enzymatic activity, concurrent with the covalent modification of 50% of the active-site serines, as judged from the amount of p-nitrophenolate (PNP) released. Modification of the remaining 50% occurred at a much lower rate, indicative of half-of-the-sites reactivity against the inhibitor of this dimeric enzyme. Inhibition of monomeric OMPLA solubilized in hexadecyl-N,N-dimethyl-1-ammonio-3-propanesulfonate resulted in an equimolar monophasic release of PNP, concurrent with the loss of enzymatic activity (t1/2 = 14 min). The half-of-the-sites reactivity is discussed in view of the dimeric nature of this enzyme.

Inhibition of eukaryotic translation elongation by the antitumor natural product Mycalamide B.

Science.gov (United States)

Dang, Yongjun; Schneider-Poetsch, Tilman; Eyler, Daniel E; Jewett, John C; Bhat, Shridhar; Rawal, Viresh H; Green, Rachel; Liu, Jun O

2011-08-01

Mycalamide B (MycB) is a marine sponge-derived natural product with potent antitumor activity. Although it has been shown to inhibit protein synthesis, the molecular mechanism of action by MycB remains incompletely understood. We verified the inhibition of translation elongation by in vitro HCV IRES dual luciferase assays, ribosome assembly, and in vivo [(35)S]methinione labeling experiments. Similar to cycloheximide (CHX), MycB inhibits translation elongation through blockade of eEF2-mediated translocation without affecting the eEF1A-mediated loading of tRNA onto the ribosome, AUG recognition, or dipeptide synthesis. Using chemical footprinting, we identified the MycB binding site proximal to the C3993 28S rRNA residue on the large ribosomal subunit. However, there are also subtle, but significant differences in the detailed mechanisms of action of MycB and CHX. First, MycB arrests the ribosome on the mRNA one codon ahead of CHX. Second, MycB specifically blocked tRNA binding to the E-site of the large ribosomal subunit. Moreover, they display different polysome profiles in vivo. Together, these observations shed new light on the mechanism of inhibition of translation elongation by MycB.

Brain sites mediating corticosteroid feedback inhibition of stimulated ACTH secretion

International Nuclear Information System (INIS)

Jacobson, L.

1989-01-01

There is substantial evidence that the brain mediates stress-induced and circadian increases in ACTH secretion and that corticosteroid concentrations which normalize basal plasma ACTH are insufficient to normalize ACTH responses to circadian or stressful stimuli in adrenalectomized rats. To identify brain sites mediating corticosteroid inhibition of stimulated ACTH secretion, two approaches were used. The first compared brain [ 14 C]-2-deoxyglucose uptake in rats with differential ACTH responses to stress. Relative to sham-adrenalectomized (SHAM) rats, adrenalectomized rats replaced with low, constant corticosterone levels via a subcutaneous corticosterone pellet (B-PELLET) exhibited elevated and prolonged ACTH responses to a variety of stimuli. Adrenalectomized rate given a circadian corticosterone rhythm via corticosterone in their drinking water exhibited elevated ACTH levels immediately after stress, but unlike B-PELLET rats, terminated stress induced ACTH secretion normally relative to SHAMS. Therefore, the abnormal ACTH responses to stress in B-PELLET rats were due to the lack of both circadian variations and stress-induced increases in corticosterone. Hypoxia was selected as a standardized stimulus for correlating brain [ 14 C]-2-deoxyglucose uptake with ACTH secretion. In intact rats, increases in plasma ACTH and decreases in arterial PO 2 correlated with the severity of hypoxia at arterial PCO 2 below 60 mm Hg. Hypoxia PELLET vs. SHAM rats. However, in preliminary experiments, although hypoxia increased brain 2-deoxyglucose uptake in most brain regions, plasma ACTH correlated poorly with 2-deoxyglucose uptake at 12% and 10% O 2

Lipopolysaccharide-induced inhibition of transcription of tlr4 in vitro is reversed by dexamethasone and correlates with presence of conserved NFκB binding sites

Energy Technology Data Exchange (ETDEWEB)

Bonin, Camila P., E-mail: mila_bonin@yahoo.com.br [Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-900 (Brazil); Baccarin, Raquel Y.A., E-mail: baccarin@usp.br [Department of Clinics, School of Veterinary Medicine, University of São Paulo, São Paulo 05508-900 (Brazil); Nostell, Katarina, E-mail: katarina.nostell@slu.se [Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 750 07 Uppsala (Sweden); Nahum, Laila A., E-mail: laila@nahum.com.br [Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte 30190-002 (Brazil); Faculdade Infórium de Tecnologia, Belo Horizonte 30130-180 (Brazil); Fossum, Caroline, E-mail: caroline.fossum@bvf.slu.se [Department of Biomedicine and Veterinary Public Health, Section for Immunology, Swedish University of Agricultural Sciences, BMC, Box 588, SE 751 23 Uppsala (Sweden); Camargo, Maristela M. de, E-mail: mmcamar@usp.br [Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-900 (Brazil)

2013-03-08

Highlights: ► Chimpanzees, horses and humans have regions of similarity on TLR4 and MD2 promoters. ► Rodents have few regions of similarity on TLR4 promoter when compared to primates. ► Conserved NFkB binding sites were found in the promoters of TLR4 and MD2. ► LPS-induced inhibition of TLR4 transcription is reversed by dexamethasone. ► LPS-induced transcription of MD2 is inhibited by dexamethasone. -- Abstract: Engagement of Toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) is a master trigger of the deleterious effects of septic shock. Horses and humans are considered the most sensitive species to septic shock, but the mechanisms explaining these phenomena remain elusive. Analysis of tlr4 promoters revealed high similarity among LPS-sensitive species (human, chimpanzee, and horse) and low similarity with LPS-resistant species (mouse and rat). Four conserved nuclear factor kappa B (NFκB) binding sites were found in the tlr4 promoter and two in the md2 promoter sequences that are likely to be targets for dexamethasone regulation. In vitro treatment of equine peripheral blood mononuclear cells (eqPBMC) with LPS decreased transcripts of tlr4 and increased transcription of md2 (myeloid differentiation factor 2) and cd14 (cluster of differentiation 14). Treatment with dexamethasone rescued transcription of tlr4 after LPS inhibition. LPS-induced transcription of md2 was inhibited in the presence of dexamethasone. Dexamethasone alone did not affect transcription of tlr4 and md2.

ATF3 represses PPARγ expression and inhibits adipocyte differentiation

Energy Technology Data Exchange (ETDEWEB)

Jang, Min-Kyung; Jung, Myeong Ho, E-mail: jung0603@pusan.ac.kr

2014-11-07

Highlights: • ATF3 decrease the expression of PPARγ and its target gene in 3T3-L1 adipocytes. • ATF3 represses the promoter activity of PPARγ2 gene. • ATF/CRE (−1537/−1530) is critical for ATF3-mediated downregulation of PPARγ. • ATF3 binds to the promoter region containing the ATF/CRE. • ER stress inhibits adipocyte differentiation through downregulation of PPARγ by ATF3. - Abstract: Activating transcription factor 3 (ATF3) is a stress-adaptive transcription factor that mediates cellular stress response signaling. We previously reported that ATF3 represses CCAAT/enhancer binding protein α (C/EBPα) expression and inhibits 3T3-L1 adipocyte differentiation. In this study, we explored potential role of ATF3 in negatively regulating peroxisome proliferator activated receptor-γ (PPARγ). ATF3 decreased the expression of PPARγ and its target gene in 3T3-L1 adipocytes. ATF3 also repressed the activity of −2.6 Kb promoter of mouse PPARγ2. Overexpression of PPARγ significantly prevented the ATF3-mediated inhibition of 3T3-L1 differentiation. Transfection studies with 5′ deleted-reporters showed that ATF3 repressed the activity of −2037 bp promoter, whereas it did not affect the activity of −1458 bp promoter, suggesting that ATF3 responsive element is located between the −2037 and −1458. An electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that ATF3 binds to ATF/CRE site (5′-TGACGTTT-3′) between −1537 and −1530. Mutation of the ATF/CRE site abrogated ATF3-mediated transrepression of the PPARγ2 promoter. Treatment with thapsigargin, endoplasmic reticulum (ER) stress inducer, increased ATF3 expression, whereas it decreased PPARγ expression. ATF3 knockdown significantly blocked the thapsigargin-mediated downregulation of PPARγ expression. Furthermore, overexpression of PPARγ prevented inhibition of 3T3-L1 differentiation by thapsigargin. Collectively, these results suggest that ATF3-mediated

Identification and Analysis of Significant Factors Influencing Visitor Satisfaction at Heritage Sites – The Case of Serbian Medieval Fortresses

Directory of Open Access Journals (Sweden)

Ivana Blešić

2013-01-01

Full Text Available With increased appreciation of general public, heritage sites gained more attention regarding contemporary tourism and management studies. Accordingly, the assessment of visitors’ satisfaction on these sites is important tool for both financial and organization management. The aim of this research is to identify the main (statistically significant factors that influence visitors’ satisfaction. Data was obtained by survey conducted during the visit of three medieval fortresses in Serbia, with aim to capture tourist’s expectations and perceptions on ten given attributes. The results of factor and descriptive statistical analysis indicate three factors: “regional settings”, “marketing”, “aesthetic appeal” significant for visitors’ satisfaction of the investigated heritage sites.

Finding of No Significant Impact, proposed remediation of the Maybell Uranium Mill Processing Site, Maybell, Colorado

International Nuclear Information System (INIS)

1995-01-01

The U.S. Department of Energy (DOE) has prepared an environmental assessment (EA) (DOE/EA-0347) on the proposed surface remediation of the Maybell uranium mill processing site in Moffat County, Colorado. The mill site contains radioactively contaminated materials from processing uranium ore that would be stabilized in place at the existing tailings pile location. Based on the analysis in the EA, DOE has determined that the proposed action does not constitute a major federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act (NEPA) of 1969, Public Law 91-190 (42 U.S.C. section 4321 et seq.), as amended. Therefore, preparation of an environmental impact statement is not required and DOE is issuing this Finding of No Significant Impact (FONSI)

Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair

Energy Technology Data Exchange (ETDEWEB)

Wang, Ping; Guliaev, Anton B.; Hang, Bo

2006-02-28

Cadmium (Cd{sup 2+}), nickel (Ni{sup 2+}) and cobalt (Co{sup 2+}) are human and/or animal carcinogens. Zinc (Zn{sup 2+}) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (var epsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1000 {micro}M, both Cd{sup 2+} and Zn{sup 2+} showed metal-dependent inhibition of the MPG catalytic activity. Ni{sup 2+} also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co{sup 2+} and Mg{sup 2+} did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the var epsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd{sup 2+}, Zn{sup 2+}, and Ni{sup 2+} at concentrations that show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn{sup 2+} showed that the MPG active site has a potential binding site for Zn{sup 2+}, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.

In-site interaction evaluation of Tn density by inhibition/competition assays

Energy Technology Data Exchange (ETDEWEB)

Robles, Ana [Radiopharmacy Department, Nuclear Research Center, Faculty of Sciences, University of the Republic, Montevideo (Uruguay)], E-mail: anamar@cin.edu.uy; Medeiros, Andrea [Biochemistry Department, Faculty of Medicine, University of the Republic, Montevideo (Uruguay); Berois, Nora [Laboratory of Glycobiology and Tumor Immunology, Pasteur Institute of Montevideo (Uruguay); Balter, Henia S. [Radiopharmacy Department, Nuclear Research Center, Faculty of Sciences, University of the Republic, Montevideo (Uruguay); Pauwels, Ernest K. [University Medical Center Leiden, Department of Radiology, Leiden (Netherlands); Osinaga, Eduardo [Laboratory of Glycobiology and Tumor Immunology, Pasteur Institute of Montevideo (Uruguay); Department of Immunobiology, Faculty of Medicine, University of the Republic, Montevideo (Uruguay)

2010-05-15

The tumor-associated structure N-acetyl-galactosamine-O-Ser/Thr (Tn antigen), which is overexpressed in various tumor cell types, notably of the breast, ovary and colon, is an interesting determinant that is useful for cancer diagnosis and follow-up. The aim of this research was to study different assay strategies in order to determine the most sensitive system for further application in epitope characterization and binding assessment. The tetrameric isolectin obtained from Vicia villosa seeds (VVLB{sub 4}) shows high affinity for the tumor-associated structure. A monoclonal antibody against VVLB{sub 4}, MabVV{sub 34}, was generated, and the interaction between MabVV{sub 34} and VVLB{sub 4} was studied by means of binding and inhibition assays. Several synthetic peptides (10 amino acid sequences) designed from the amino acid sequence of VVLB{sub 4} and obtained from trypsin digestion were tested to determine which amino acids were involved in the interaction between MabVV{sub 34} and VVLB{sub 4}. The further unraveling of this epitope was investigated by inhibition using designed synthetic peptides as well as mixtures mimicking variable density effect. Under the experimental circumstances, MabVV{sub 34} was able to inhibit the binding of VVLB{sub 4} to Tn. Two of the four peptide sequences assayed showed better inhibition properties. Finally, mixtures containing these selected sequences allowed the evaluation of binding and inhibition as a function of Tn density. We conclude that the present study facilitates the further development of a specific Tn marker and may contribute to the development of Tn-like radiolabelled peptides or Tn-specific radiolabelled fragments providing a highly selective tool for cancer diagnosis and treatment. This strategy may contribute to characterize the new generation of radiopharmaceuticals for diagnosis and therapy based on biomolecules like antibodies, fragments or peptides, whose application is directly guided by their specific

Downregulation of miR-29a/b/c in placenta accreta inhibits apoptosis of implantation site intermediate trophoblast cells by targeting MCL1.

Science.gov (United States)

Gu, Yongzhong; Bian, Yuehong; Xu, Xiaofei; Wang, Xietong; Zuo, Changting; Meng, Jinlai; Li, Hongyan; Zhao, Shigang; Ning, Yunnan; Cao, Yongzhi; Huang, Tao; Yan, Junhao; Chen, Zi-Jiang

2016-12-01

Placenta accreta is defined as abnormal adhesion of placental villi to the uterine myometrium. Although this condition has become more common as a result of the increasing rate of cesarean sections, the underlying causative mechanism(s) remain elusive. Because microRNA-29a/b/c (miR-29a/b/c) have been shown to play important roles in placental development, this study evaluated the roles of these microRNAs in placenta accreta. Expression of miR-29a/b/c and myeloid cell leukemia-1 (MCL1) were quantified in patient tissues and HTR8/SVneo trophoblast cells using the real-time quantitative polymerase chain reaction. Western blotting was used to analyze expression of the MCL1 protein in HTR8/SVneo trophoblast cells with altered expression of miR-29a/b/c. To determine their role in apoptosis, miR-29a/b/c were overexpressed in HTR-8/SVneo cells, and levels of apoptosis were analyzed by flow cytometry. Luciferase activity assays were used to determine whether MCL1 is a target gene of miR-29a/b/c. Expression of miR-29a/b/c was significantly lower in creta sites compared to noncreta sites (p = 0.018, 0.041, and 0.022, respectively), but expression of MCL1 was upregulated in creta sites (p = 0.039). MCL1 expression was significantly downregulated in HTR-8/SVneo cells overexpressing miR-29a/b/c (p = 0.002, 0.008, and 0.013, respectively). Luciferase activity assays revealed that miR-29a/b/c directly target the 3' untranslated region of MCL1 in 293T cells. Over-expression of miR-29a/b/c induced apoptosis in the HTR-8/SVneo trophoblast cell line. Moreover, histopathological evaluation revealed that the number of implantation site intermediate trophoblast (ISIT) cells was increased in creta sites and that these cells were positive for MCL1. Our results demonstrate that in placenta accreta, miR-29a/b/c inhibits apoptosis of ISIT cells by targeting MCL1. These findings provide new insights into the pathogenesis of placenta accreta. Copyright © 2016 Elsevier Ltd. All rights

Combination treatment with ionising radiation and gefitinib ('Iressa', ZD1839), an epidermal growth factor receptor (EGFR) inhibitor, significantly inhibits bladder cancer cell growth in vitro and in vivo

International Nuclear Information System (INIS)

Colquhoun, AJ; Mchugh, LA; Tulchinsky, E.; Kriajevska, M.; Mellon, JK

2007-01-01

External beam radiotherapy (EBRT) is the principal bladder-preserving monotherapy for muscle-invasive bladder cancer. Seventy percent of muscle-invasive bladder cancers express epidermal growth factor receptor (EGFR), which is associated with poor prognosis. Ionising radiation (IR) stimulates EGFR causing activation of cytoprotective signalling cascades and thus may be an underlying cause of radioresistance in bladder tumours. We assessed the ability of IR to activate EGFR in bladder cancer cells and the effect of the anti-EGFR therapy, gefitinib on potential radiation-induced activation. Subsequently we assessed the effect of IR on signalling pathways downstream of EGFR. Finally we assessed the activity of gefitinib as a monotherapy, and in combination with IR, using clonogenic assay in vitro, and a murine model in vivo. IR activated EGFR and gefitinib partially inhibited this activation. Radiation-induced activation of EGFR activated the MAPK and Akt pathways. Gefitinib partially inhibited activation of the MAPK pathway but not the Akt pathway. Treatment with combined gefitinib and IR significantly inhibited bladder cancer cell colony formation more than treatment with gefitinib alone (p=0.001-0.03). J82 xenograft tumours treated with combined gefitinib and IR showed significantly greater growth inhibition than tumours treated with IR alone (p=0.04). Combining gefitinib and IR results in significantly greater inhibition of invasive bladder cancer cell colony formation in vitro and significantly greater tumour growth inhibition in vivo. Given the high frequency of EGFR expression by bladder tumours and the low toxicity of gefitinib there is justification to translate this work into a clinical trial. (author)

Active-site-directed inhibition of 3-hydroxy-3-methylglutaryl coenzyme A synthase by 3-chloropropionyl coenzyme A

International Nuclear Information System (INIS)

Miziorko, H.M.; Behnke, C.E.

1985-01-01

3-Chloropropionyl coenzyme A (3-chloropropionyl-CoA) irreversibly inhibits avian liver 3-hydroxy-3-methylglutaryl-CoA synthase (HMG-CoA synthase). Enzyme inactivation follows pseudo-first-order kinetics and is retarded in the presence of substrates, suggesting that covalent labeling occurs at the active site. A typical rate saturation effect is observed when inactivation kinetics are measured as a function of 3-chloropropionyl-CoA concentration. These data indicate a Ki = 15 microM for the inhibitor and a limiting kinact = 0.31 min-1. [1- 14 C]-3-Chloropropionyl-CoA binds covalently to the enzyme with a stoichiometry (0.7 per site) similar to that measured for acetylation of the enzyme by acetyl-CoA. While the acetylated enzyme formed upon incubation of HMG-CoA synthase with acetyl-CoA is labile to performic acid oxidation, the adduct formed upon 3-chloropropionyl-CoA inactivation is stable to such treatment. Therefore, such an adduct cannot solely involve a thio ester linkage. Exhaustive Pronase digestion of [ 14 C]-3-chloropropionyl-CoA-labeled enzyme produces a radioactive compound which cochromatographs with authentic carboxyethylcysteine using reverse-phase/ion-pairing high-pressure liquid chromatography and both silica and cellulose thin-layer chromatography systems. This suggests that enzyme inactivation is due to alkylation of an active-site cysteine residue

Metformin combined with aspirin significantly inhibit pancreatic cancer cell growth in vitro and in vivo by suppressing anti-apoptotic proteins Mcl-1 and Bcl-2

Science.gov (United States)

Yue, Wen; Zheng, Xi; Lin, Yong; Yang, Chung S.; Xu, Qing; Carpizo, Darren; Huang, Huarong; DiPaola, Robert S.; Tan, Xiang-Lin

2015-01-01

Metformin and aspirin have been studied extensively as cancer preventive or therapeutic agents. However, the effects of their combination on pancreatic cancer cells have not been investigated. Herein, we evaluated the effects of metformin and aspirin, alone or in combination, on cell viability, migration, and apoptosis as well as the molecular changes in mTOR, STAT3 and apoptotic signaling pathways in PANC-1 and BxPC3 cells. Metformin and aspirin, at relatively low concentrations, demonstrated synergistically inhibitory effects on cell viability. Compared to the untreated control or individual drug, the combination of metformin and aspirin significantly inhibited cell migration and colony formation of both PANC-1 and BxPC-3 cells. Metformin combined with aspirin significantly inhibited the phosphorylation of mTOR and STAT3, and induced apoptosis as measured by caspase-3 and PARP cleavage. Remarkably, metformin combined with aspirin significantly downregulated the anti-apoptotic proteins Mcl-1 and Bcl-2, and upregulated the pro-apoptotic proteins Bim and Puma, as well as interrupted their interactions. The downregulation of Mcl-1 and Bcl-2 was independent of AMPK or STAT3 pathway but partially through mTOR signaling and proteasome degradation. In a PANC-1 xenograft mouse model, we demonstrated that the combination of metformin and aspirin significantly inhibited tumor growth and downregulated the protein expression of Mcl-1 and Bcl-2 in tumors. Taken together, the combination of metformin and aspirin significantly inhibited pancreatic cancer cell growth in vitro and in vivo by regulating the pro- and anti-apoptotic Bcl-2 family members, supporting the continued investigation of this two drug combination as chemopreventive or chemotherapeutic agents for pancreatic cancer. PMID:26056043

Tarantula huwentoxin-IV inhibits neuronal sodium channels by binding to receptor site 4 and trapping the domain ii voltage sensor in the closed configuration.

Science.gov (United States)

Xiao, Yucheng; Bingham, Jon-Paul; Zhu, Weiguo; Moczydlowski, Edward; Liang, Songping; Cummins, Theodore R

2008-10-03

Peptide toxins with high affinity, divergent pharmacological functions, and isoform-specific selectivity are powerful tools for investigating the structure-function relationships of voltage-gated sodium channels (VGSCs). Although a number of interesting inhibitors have been reported from tarantula venoms, little is known about the mechanism for their interaction with VGSCs. We show that huwentoxin-IV (HWTX-IV), a 35-residue peptide from tarantula Ornithoctonus huwena venom, preferentially inhibits neuronal VGSC subtypes rNav1.2, rNav1.3, and hNav1.7 compared with muscle subtypes rNav1.4 and hNav1.5. Of the five VGSCs examined, hNav1.7 was most sensitive to HWTX-IV (IC(50) approximately 26 nM). Following application of 1 microm HWTX-IV, hNav1.7 currents could only be elicited with extreme depolarizations (>+100 mV). Recovery of hNav1.7 channels from HWTX-IV inhibition could be induced by extreme depolarizations or moderate depolarizations lasting several minutes. Site-directed mutagenesis analysis indicated that the toxin docked at neurotoxin receptor site 4 located at the extracellular S3-S4 linker of domain II. Mutations E818Q and D816N in hNav1.7 decreased toxin affinity for hNav1.7 by approximately 300-fold, whereas the reverse mutations in rNav1.4 (N655D/Q657E) and the corresponding mutations in hNav1.5 (R812D/S814E) greatly increased the sensitivity of the muscle VGSCs to HWTX-IV. Our data identify a novel mechanism for sodium channel inhibition by tarantula toxins involving binding to neurotoxin receptor site 4. In contrast to scorpion beta-toxins that trap the IIS4 voltage sensor in an outward configuration, we propose that HWTX-IV traps the voltage sensor of domain II in the inward, closed configuration.

Resveratrol inhibits PDGF receptor mitogenic signaling in mesangial cells: role of PTP1B

Science.gov (United States)

Venkatesan, Balachandar; Ghosh-Choudhury, Nandini; Das, Falguni; Mahimainathan, Lenin; Kamat, Amrita; Kasinath, Balakuntalam S.; Abboud, Hanna E.; Choudhury, Goutam Ghosh

2008-01-01

Mesangioproliferative glomerulonephritis is associated with overactive PDGF receptor signal transduction. We show that the phytoalexin resveratrol dose dependently inhibits PDGF-induced DNA synthesis in mesangial cells with an IC50 of 10 μM without inducing apoptosis. Remarkably, the increased SIRT1 deacetylase activity induced by resveratrol was not necessary for this inhibitory effect. Resveratrol significantly blocked PDGF-stimulated c-Src and Akt kinase activation, resulting in reduced cyclin D1 expression and attenuated pRb phosphorylation and cyclin-dependent kinase-2 (CDK2) activity. Furthermore, resveratrol inhibited PDGFR phosphorylation at the PI 3 kinase and Grb-2 binding sites tyrosine-751 and tyrosine-716, respectively. This deficiency in PDGFR phosphorylation resulted in significant inhibition of PI 3 kinase and Erk1/2 MAPK activity. Interestingly, resveratrol increased the activity of protein tyrosine phosphatase PTP1B, which dephosphorylates PDGF-stimulated phosphorylation at tyrosine-751 and tyrosine-716 on PDGFR with concomitant reduction in Akt and Erk1/2 kinase activity. PTP1B significantly inhibited PDGF-induced DNA synthesis without inducing apoptosis. These results for the first time provide evidence that the stilbene resveratrol targets PTP1B to inhibit PDGFR mitogenic signaling.—Venkatesan, B., Ghosh-Choudhury, N., Das, F., Mahimainathan, L., Kamat, A., Kasinath, B. S., Abboud, H. E., Choudhury, G. G. Resveratrol inhibits PDGF receptor mitogenic signaling in mesangial cells: role of PTP1B. PMID:18567737

PHLPP1 regulates contact inhibition by dephosphorylating Mst1 at the inhibitory site

International Nuclear Information System (INIS)

Jung, Sujin; Kang, Jeong Gu; Lee, Ju Hee; Song, Kyoung Jin; Ko, Jeong-Heon; Kim, Yong-Sam

2014-01-01

Highlights: • PHLPP1 regulates contact inhibition by dephosphorylating Mst1 at Thr 387 . • Overexpression of PHLPP1 sensitizes contact inhibition. • Tumor cells with suppressed PHLPP1 expression are refractory to apoptosis and highly proliferative. • Loss or down-regulation of PHLPP1 may drive tumor development and progression. - Abstract: Contact inhibition has been largely elusive despite that a loss of contact inhibition is a critical event for cancer development and progression. Here, we report that PHLPP1 is a binding protein for Mst1 and it modulates the Hippo pathway by dephosphorylating Mst1 at the inhibitory Thr 387 of Mst1. Yap1 was localized predominantly in the nucleus but marginally in the cytoplasm in HeLa cells under sparse conditions, whereas the functional protein was more directed to sequestration in the cytoplasm under dense environments. Furthermore, loss of PHLPP1 resulted in a failure of the apoptotic control. It is interesting that down-regulated expression of PHLPP1 appears to mimic the loss of contact inhibition, a hallmark of cancer

PHLPP1 regulates contact inhibition by dephosphorylating Mst1 at the inhibitory site

Energy Technology Data Exchange (ETDEWEB)

Jung, Sujin; Kang, Jeong Gu [Targeted Gene Regulation Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Deajeon (Korea, Republic of); Lee, Ju Hee [Targeted Gene Regulation Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Deajeon (Korea, Republic of); Department of Biomolecular Science, University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Song, Kyoung Jin [Targeted Gene Regulation Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Deajeon (Korea, Republic of); Ko, Jeong-Heon [Targeted Gene Regulation Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Deajeon (Korea, Republic of); Department of Biomolecular Science, University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Kim, Yong-Sam, E-mail: omsys1@kribb.re.kr [Targeted Gene Regulation Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Deajeon (Korea, Republic of); Department of Biomolecular Science, University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of)

2014-01-24

Highlights: • PHLPP1 regulates contact inhibition by dephosphorylating Mst1 at Thr{sup 387}. • Overexpression of PHLPP1 sensitizes contact inhibition. • Tumor cells with suppressed PHLPP1 expression are refractory to apoptosis and highly proliferative. • Loss or down-regulation of PHLPP1 may drive tumor development and progression. - Abstract: Contact inhibition has been largely elusive despite that a loss of contact inhibition is a critical event for cancer development and progression. Here, we report that PHLPP1 is a binding protein for Mst1 and it modulates the Hippo pathway by dephosphorylating Mst1 at the inhibitory Thr{sup 387} of Mst1. Yap1 was localized predominantly in the nucleus but marginally in the cytoplasm in HeLa cells under sparse conditions, whereas the functional protein was more directed to sequestration in the cytoplasm under dense environments. Furthermore, loss of PHLPP1 resulted in a failure of the apoptotic control. It is interesting that down-regulated expression of PHLPP1 appears to mimic the loss of contact inhibition, a hallmark of cancer.

Finding of no significant impact proposed remedial action at two uranium processing sites near Slick Rock, Colorado

International Nuclear Information System (INIS)

1994-01-01

The U.S. Department of Energy (DOE) has prepared an environmental assessment (EA) (DOE/EA-0339) of the proposed remedial action at two uranium processing sites near Slick Rock in San Miguel County, Colorado. These sites contain radioactively contaminated materials that would be removed and stabilized at a remote location. Based on the information and analyses in the EA, the DOE has determined that the proposed action does not constitute a major Federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321 et seq.), as amended. Therefore, preparation of an environmental impact statement is not required, and the DOE is issuing this Finding of No Significant Impact (ONSI)

Structural Basis for the Inhibition of RNase H Activity of HIV-1 Reverse Transcriptase by RNase H Active Site-Directed Inhibitors

Energy Technology Data Exchange (ETDEWEB)

Su, Hua-Poo; Yan, Youwei; Prasad, G. Sridhar; Smith, Robert F.; Daniels, Christopher L.; Abeywickrema, Pravien D.; Reid, John C.; Loughran, H. Marie; Kornienko, Maria; Sharma, Sujata; Grobler, Jay A.; Xu, Bei; Sardana, Vinod; Allison, Timothy J.; Williams, Peter D.; Darke, Paul L.; Hazuda, Daria J.; Munshi, Sanjeev (Merck)

2010-09-02

HIV/AIDS continues to be a menace to public health. Several drugs currently on the market have successfully improved the ability to manage the viral burden in infected patients. However, new drugs are needed to combat the rapid emergence of mutated forms of the virus that are resistant to existing therapies. Currently, approved drugs target three of the four major enzyme activities encoded by the virus that are critical to the HIV life cycle. Although a number of inhibitors of HIV RNase H activity have been reported, few inhibit by directly engaging the RNase H active site. Here, we describe structures of naphthyridinone-containing inhibitors bound to the RNase H active site. This class of compounds binds to the active site via two metal ions that are coordinated by catalytic site residues, D443, E478, D498, and D549. The directionality of the naphthyridinone pharmacophore is restricted by the ordering of D549 and H539 in the RNase H domain. In addition, one of the naphthyridinone-based compounds was found to bind at a second site close to the polymerase active site and non-nucleoside/nucleotide inhibitor sites in a metal-independent manner. Further characterization, using fluorescence-based thermal denaturation and a crystal structure of the isolated RNase H domain reveals that this compound can also bind the RNase H site and retains the metal-dependent binding mode of this class of molecules. These structures provide a means for structurally guided design of novel RNase H inhibitors.

Arborvitae (Thuja plicata essential oil significantly inhibited critical inflammation- and tissue remodeling-related proteins and genes in human dermal fibroblasts

Directory of Open Access Journals (Sweden)

Xuesheng Han

2017-06-01

Full Text Available Arborvitae (Thuja plicata essential oil (AEO is becoming increasingly popular in skincare, although its biological activity in human skin cells has not been investigated. Therefore, we sought to study AEO's effect on 17 important protein biomarkers that are closely related to inflammation and tissue remodeling by using a pre-inflamed human dermal fibroblast culture model. AEO significantly inhibited the expression of vascular cell adhesion molecule 1 (VCAM-1, intracellular cell adhesion molecule 1 (ICAM-1, interferon gamma-induced protein 10 (IP-10, interferon-inducible T-cell chemoattractant (I-TAC, monokine induced by interferon gamma (MIG, and macrophage colony-stimulating factor (M-CSF. It also showed significant antiproliferative activity and robustly inhibited collagen-I, collagen-III, plasminogen activator inhibitor-1 (PAI-1, and tissue inhibitor of metalloproteinase 1 and 2 (TIMP-1 and TIMP-2. The inhibitory effect of AEO on increased production of these protein biomarkers suggests it has anti-inflammatory property. We then studied the effect of AEO on the genome-wide expression of 21,224 genes in the same cell culture. AEO significantly and diversely modulated global gene expression. Ingenuity pathway analysis (IPA showed that AEO robustly affected numerous critical genes and signaling pathways closely involved in inflammatory and tissue remodeling processes. The findings of this study provide the first evidence of the biological activity and beneficial action of AEO in human skin cells.

Enzyme inhibition by iminosugars

DEFF Research Database (Denmark)

López, Óscar; Qing, Feng-Ling; Pedersen, Christian Marcus

2013-01-01

Imino- and azasugar glycosidase inhibitors display pH dependant inhibition reflecting that both the inhibitor and the enzyme active site have groups that change protonation state with pH. With the enzyme having two acidic groups and the inhibitor one basic group, enzyme-inhibitor complexes...

Quantitative PET Imaging of Tissue Factor Expression Using 18F-labled Active Site Inhibited Factor VII

DEFF Research Database (Denmark)

Nielsen, Carsten H; Erlandsson, Maria; Jeppesen, Troels E

2016-01-01

Tissue factor (TF) is up regulated in many solid tumors and its expression is linked to tumor angiogenesis, invasion, metastasis and prognosis. A non-invasive assessment of tumor TF expression status is therefore of obvious clinical relevance. Factor VII (FVII) is the natural ligand to TF. Here we...... report the development of a new PET tracer for specific imaging of TF using an (18)F-labeled derivative of FVII. METHODS: Active site inhibited factor VIIa (FVIIai) was obtained by inactivation with phenylalanine-phenylalanine-arginine-chloromethyl ketone. FVIIai was radiolabeled with N-succinimidyl 4......-[(18)F]-fluorobenzoate ([(18)F]SFB) and purified. The corresponding product, [(18)F]FVIIai, was injected into nude mice with subcutaneous human pancreatic xenograft tumors (BxPC-3) and investigated using small animal PET/CT imaging 1, 2 and 4 hours after injection. Ex vivo biodistribution was performed...

Cladribine and Fludarabine Nucleotides Induce Distinct Hexamers Defining a Common Mode of Reversible RNR Inhibition.

Science.gov (United States)

Wisitpitthaya, Somsinee; Zhao, Yi; Long, Marcus J C; Li, Minxing; Fletcher, Elaine A; Blessing, William A; Weiss, Robert S; Aye, Yimon

2016-07-15

The enzyme ribonucleotide reductase (RNR) is a major target of anticancer drugs. Until recently, suicide inactivation in which synthetic substrate analogs (nucleoside diphosphates) irreversibly inactivate the RNR-α2β2 heterodimeric complex was the only clinically proven inhibition pathway. For instance, this mechanism is deployed by the multifactorial anticancer agent gemcitabine diphosphate. Recently reversible targeting of RNR-α-alone coupled with ligand-induced RNR-α-persistent hexamerization has emerged to be of clinical significance. To date, clofarabine nucleotides are the only known example of this mechanism. Herein, chemoenzymatic syntheses of the active forms of two other drugs, phosphorylated cladribine (ClA) and fludarabine (FlU), allow us to establish that reversible inhibition is common to numerous drugs in clinical use. Enzyme inhibition and fluorescence anisotropy assays show that the di- and triphosphates of the two nucleosides function as reversible (i.e., nonmechanism-based) inhibitors of RNR and interact with the catalytic (C site) and the allosteric activity (A site) sites of RNR-α, respectively. Gel filtration, protease digestion, and FRET assays demonstrate that inhibition is coupled with formation of conformationally diverse hexamers. Studies in 293T cells capable of selectively inducing either wild-type or oligomerization-defective mutant RNR-α overexpression delineate the central role of RNR-α oligomerization in drug activity, and highlight a potential resistance mechanism to these drugs. These data set the stage for new interventions targeting RNR oligomeric regulation.

Structural inhibition and reactivation of Escherichia coli septation by elements of the SOS and TER pathways

International Nuclear Information System (INIS)

Dopazo, A.; Tormo, A.; Aldea, M.; Vicente, M.

1987-01-01

The inhibition of cell division caused by induction of the SOS pathway in Escherichia coli structurally blocks septation, as deduced from two sets of results. Potential septation sites active at the time of SOS induction became inactivated, while those initiated during the following doubling time were active. Penicillin resistance increased in wild-type UV light-irradiated cells, a behavior similar to that observed in mutants in which structural blocks were introduced by inactivation of FtsA. Potential septation sites that have been structurally blocked by either the SOS division inhibitor, furazlocillin inhibition of PBP3, or inactivation of a TER pathway component, FtsA3, could be reactivated one doubling time after removal of the inhibitory agent in the presence of an active lon gene product. Reactivation of potential septation sites blocked by the presence of an inactivated FtsA3 was significantly lower when the lon protease was not active, suggesting that Lon plays a role in the removal of inactivated TER pathway products from the blocked potential septation sites

Behavioral inhibition and obsessive-compulsive disorder.

Science.gov (United States)

Coles, Meredith E; Schofield, Casey A; Pietrefesa, Ashley S

2006-01-01

Behavioral inhibition is frequently cited as a vulnerability factor for development of anxiety. However, few studies have examined the unique relationship between behavioral inhibition and obsessive-compulsive disorder (OCD). Therefore, the current study addressed the relationship between behavioral inhibition and OCD in a number of ways. In a large unselected student sample, frequency of current OC symptoms was significantly correlated with retrospective self-reports of total levels of childhood behavioral inhibition. In addition, frequency of current OC symptoms was also significantly correlated with both social and nonsocial components of behavioral inhibition. Further, there was evidence for a unique relationship between behavioral inhibition and OC symptoms beyond the relationship of behavioral inhibition and social anxiety. In addition, results showed that reports of childhood levels of behavioral inhibition significantly predicted levels of OCD symptoms in adulthood. Finally, preliminary evidence suggested that behavioral inhibition may be more strongly associated with some types of OC symptoms than others, and that overprotective parenting may moderate the impact of behavioral inhibition on OC symptoms. The current findings suggest the utility of additional research examining the role of behavioral inhibition in the etiology of OCD.

Mechanism of inhibition of rat brain adenosine triphosphatase by mercuric chloride

International Nuclear Information System (INIS)

Chetty, C.S.; Rajanna, B.; Rajanna, S.

1989-01-01

Mercuric Chloride (Hg), a neurotoxic compound inhibited ATPase system of rat brain microsomes. Membrane bound enzymes, Na + -K + ATPase (IC 50 = 2.35 x 10 -7M ) and K-paranitrophenyl phosphatase (K-PNPPase) (IC 50 = 2.7 x 10 -7M ) and 3 H-Ouabain binding (IC 50 = 3.3 x 10 -7M ) were inhibited by Hg at micromolar concentrations in a dose dependent manner. Hydrolysis of ATP was linear with time with or without Hg in the reaction mixtures. Altered pH or temperature versus enzyme activity showed higher inhibition by Hg at basic pH (8.0-9.0) and at lower temperatures (17-32 degree C). Activation energy (ΔE) values were increased at 27-37 degree C in the presence of Hg. Kinetic studies of cationic-substrate activation of Na + -K + ATPase and K-PNPPase in the presence of Hg showed significant changes in kinetic constant (K m and V max ). Inhibition of Na + -K + ATPase was partially restored by repeated washings of microsomes. Preincubation with sulfhydryl agents protected Na + -K + ATPase from Hg inhibition. Cumulative inhibition studies with Hg and ouabain indicated possible interaction between the two inhibitors of Na + -K + ATPase by interacting at Na + and K + sites

Effects of secondary structure on pre-mRNA splicing: hairpins sequestering the 5' but not the 3' splice site inhibit intron processing in Nicotiana plumbaginifolia.

Science.gov (United States)

Liu, H X; Goodall, G J; Kole, R; Filipowicz, W

1995-01-16

We have performed a systematic study of the effect of artificial hairpins on pre-mRNA splicing in protoplasts of a dicot plant, Nicotiana plumbaginifolia. Hairpins with a potential to form 18 or 24 bp stems strongly inhibit splicing when they sequester the 5' splice site or are placed in the middle of short introns. However, similar 24 bp hairpins sequestering the 3' splice site do not prevent this site from being used as an acceptor. Utilization of the stem-located 3' site requires that the base of the stem is separated from the upstream 5' splice site by a minimum of approximately 45 nucleotides and that another 'helper' 3' splice site is present downstream of the stem. The results indicate that the spliceosome or factors associated with it may have a potential to unfold secondary structure present in the downstream portion of the intron, prior to or at the step of the 3' splice site selection. The finding that the helper 3' site is required for utilization of the stem-located acceptor confirms and extends previous observations, obtained with HeLa cell in vitro splicing systems, indicating that the 3' splice site may be recognized at least twice during spliceosome assembly.

The structure of F₁-ATPase from Saccharomyces cerevisiae inhibited by its regulatory protein IF₁.

Science.gov (United States)

Robinson, Graham C; Bason, John V; Montgomery, Martin G; Fearnley, Ian M; Mueller, David M; Leslie, Andrew G W; Walker, John E

2013-02-13

The structure of F₁-ATPase from Saccharomyces cerevisiae inhibited by the yeast IF₁ has been determined at 2.5 Å resolution. The inhibitory region of IF₁ from residues 1 to 36 is entrapped between the C-terminal domains of the α(DP)- and β(DP)-subunits in one of the three catalytic interfaces of the enzyme. Although the structure of the inhibited complex is similar to that of the bovine-inhibited complex, there are significant differences between the structures of the inhibitors and their detailed interactions with F₁-ATPase. However, the most significant difference is in the nucleotide occupancy of the catalytic β(E)-subunits. The nucleotide binding site in β(E)-subunit in the yeast complex contains an ADP molecule without an accompanying magnesium ion, whereas it is unoccupied in the bovine complex. Thus, the structure provides further evidence of sequential product release, with the phosphate and the magnesium ion released before the ADP molecule.

Indicine N-oxide binds to tubulin at a distinct site and inhibits the assembly of microtubules: a mechanism for its cytotoxic activity.

Science.gov (United States)

Appadurai, Prakash; Rathinasamy, Krishnan

2014-02-10

Indicine N-oxide, a pyrrolizidine alkaloid present in the plant Heliotropium indicum had shown promising cytotoxic activity in various tumor models. The compound exhibited severe toxicity to hepatocytes and bone marrow cells. The present work was aimed to evaluate the molecular mechanism of the toxicity of indicine N-oxide. We found that indicine N-oxide inhibited the proliferation of various cancer cell lines in a concentration dependent manner with IC50 ranging from 46 to 100 μM. At the half maximal inhibitory concentration it blocked the cell cycle progression at mitosis without significantly altering the organization of the spindle and interphase microtubules. The toxicities of the compound at higher concentrations are attributed to its severe depolymerizing effect on both the interphase and spindle microtubules. Binding studies using purified goat brain tubulin indicated that indicine N-oxide binds to tubulin at a distinct site not shared by colchicine or taxol. It decreased the polymer mass of both purified tubulin and MAP-rich tubulin. It was found to induce cleavage of DNA using pUC18 plasmid. The interactions of indicine N-oxide on DNA were also confirmed by computational analysis; which predicted its binding site at the minor groove of DNA. These studies bring to light that the toxicities of indicine N-oxide were due to its DNA damaging effects and depolymerization of microtubules. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

The Kinetics of Carrier Transport Inhibition

DEFF Research Database (Denmark)

Rosenberg, T.; Wilbrandt, Robert Walter

1962-01-01

The kinetical treatment of enzymatic carrier transports as given in previous communications has been extended to conditions of inhibition. Various possible types of inhibitors have been considered differing in the site of attack (enzyme or carrier), in the mode of action (competing with the subst......The kinetical treatment of enzymatic carrier transports as given in previous communications has been extended to conditions of inhibition. Various possible types of inhibitors have been considered differing in the site of attack (enzyme or carrier), in the mode of action (competing...... with the substrate for the enzyme or the carrier or for both, competing with the carrier for the enzyme, or non-competitive) and in the ability of penetrating the membrane. Experiments are reported on the inhibition of glucose and fructose transport across the human red cell membrane by phlorizine, phloretine...... and polyphloretinephosphate. The results of the analysis for these inhibitors indicate a substrate competitive mode of action. The effect of reversing the transport direction by interchanging the substrate concentration has been treated for the case of a non-penetrating substrate competitive inhibitor in the external medium...

Radionuclide migration studies at the Nevada Test Site

International Nuclear Information System (INIS)

Thompson, J.L.

1989-01-01

The United States government routinely tests nuclear devices at the Nevada Test Site (NTS) in southern Nevada. A significant amount of radioactive material exists underground at the NTS with no containers or engineered barriers to inhibit its subsequent migration. The Department of Energy has sponsored for many years a research program on radionuclide movement in the geologic media at this location. Goals of this research program are to measure the extent of movement of radionuclides away from underground explosion sites and to determine the mechanisms by which such movement occurs. This program has acquired significance in another aspect of nuclear waste management because of the Yucca Mountain Project. Yucca Mountain at the NTS is being intensively studied as the possible site for a mined repository for high level nuclear waste. The NTS provides a unique setting for field studies concerning radionuclide migration; there is the potential for greatly increasing our knowledge of the behavior of radioactive materials in volcanogenic media. This review summarizes some of the significant findings made under this research program at the NTS and identifies reports in which the details of the research may be found. 36 refs., 4 figs

Cyclosporine a inhibits apoptosis of rat gingival epithelium.

Science.gov (United States)

Ma, Su; Liu, Peihong; Li, Yanwu; Hou, Lin; Chen, Li; Qin, Chunlin

2014-08-01

The use of cyclosporine A (CsA) induces hyperplasia of the gingival epithelium in a site-specific response manner, but the molecular mechanism via which the lesion occurs is unclear. The present research aims to investigate the site-specific effect of CsA on the apoptosis of gingival epithelium associated with gingival hyperplasia. Forty Wistar rats were divided into CsA-treated and non-treated groups. Paraffin-embedded sections of mandibular first molars were selected for hematoxylin and eosin staining, immunohistochemistry analyses of bcl-2 and caspase-3, and the staining of terminal deoxynucleotidyl transfer-mediated dUTP nick-end labeling (TUNEL). The area of the whole gingival epithelium and the length of rete pegs were measured, and the number of bcl-2- and caspase-3-positive cells in the longest rete peg were counted. The analysis of variance for factorial designs and Fisher least significant difference test for post hoc analysis were used to determine the significance levels. In CsA-treated rats, bcl-2 expression was significantly upregulated, whereas caspase-3 expression was downregulated, along with a reduced number of TUNEL-positive cells. The site-specific distribution of bcl-2 was consistent with the site-specific hyperplasia of the gingival epithelium in CsA-treated rats. CsA inhibited gingival epithelial apoptosis via the mitochondrial pathway and common pathway. The antiapoptotic protein bcl-2 might play a critical role in the pathogenesis of the site-specific hyperplasia of gingival epithelium induced by CsA. There were mechanistic differences in the regulation of apoptosis for cells in the attached gingival epithelium, free gingival epithelium, and junctional epithelium.

Naloxone inhibits superoxide but not enzyme release by human neutrophils

International Nuclear Information System (INIS)

Simpkins, C.; Alailima, S.; Tate, E.

1986-01-01

The release of toxic oxygen metabolites and enzymes by phagocytic cells is thought to play a role in the multisystemic tissue injury of sepsis. Naloxone protects septic animals. We have found that at concentrations administered to animals (10 -7 to 10 -4 M), naloxone inhibited (p 2 - ) by human neutrophils (HN), stimulated with N-formyl methionyl leucyl phenylalanine (FMLP). Naloxone had no effect on cell viability. Maximum inhibition was 65% of the total O 2 - released (13.1 nMoles/8 min/320,000 cells). FMLP-stimulated release of beta-glucoronidase or lysozyme was not altered by naloxone. Naloxone had no effect on the binding of 3 H FMLP to HN. Using 3 H naloxone and various concentrations of unlabeled naloxone higher affinity (K/sub D/ = 12nM) and lower affinity (K/sub D/ = 4.7 x 10 -5 ) binding sites were detected. The K/sub D/ of the low affinity site corresponded to the ED 50 for naloxone inhibition of O 2 - (1 x 10 -5 M). Binding to this low affinity site was decreased by (+) naloxone, beta-endorphin and N acetyl beta-endorphin, but not by leu-enkephalin, thyrotropin releasing factor, prostaglandin D 2 or E 2 . Conclusions: (1) naloxone inhibits FMLP-stimulated O 2 but not enzyme release, (2) this inhibition is not due to alteration of FMLP receptor binding, (3) naloxone may act via a low affinity binding site which is ligand specific, and (4) a higher affinity receptor is present on HN

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition.

Science.gov (United States)

Rajashekar, Yallappa; Shivanandappa, Thimmappa

2017-01-01

Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s) for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation.

Science.gov (United States)

Rich, Joseph O; Leathers, Timothy D; Bischoff, Kenneth M; Anderson, Amber M; Nunnally, Melinda S

2015-11-01

Bacterial contaminants can inhibit ethanol production in biofuel fermentations, and even result in stuck fermentations. Contaminants may persist in production facilities by forming recalcitrant biofilms. A two-year longitudinal study was conducted of bacterial contaminants from a Midwestern dry grind corn fuel ethanol facility. Among eight sites sampled in the facility, the combined liquefaction stream and yeast propagation tank were consistently contaminated, leading to contamination of early fermentation tanks. Among 768 contaminants isolated, 92% were identified as Lactobacillus sp., with the most abundant species being Lactobacillus plantarum, Lactobacillus casei, Lactobacillus mucosae, and Lactobacillus fermentum. Seven percent of total isolates showed the ability to form biofilms in pure cultures, and 22% showed the capacity to significantly inhibit ethanol production. However, these traits were not correlated. Ethanol inhibition appeared to be related to acetic acid production by contaminants, particularly by obligately heterofermentative species such as L. fermentum and L. mucosae. Published by Elsevier Ltd.

Cationic Polymers Inhibit the Conductance of Lysenin Channels

Directory of Open Access Journals (Sweden)

Daniel Fologea

2013-01-01

Full Text Available The pore-forming toxin lysenin self-assembles large and stable conductance channels in natural and artificial lipid membranes. The lysenin channels exhibit unique regulation capabilities, which open unexplored possibilities to control the transport of ions and molecules through artificial and natural lipid membranes. Our investigations demonstrate that the positively charged polymers polyethyleneimine and chitosan inhibit the conducting properties of lysenin channels inserted into planar lipid membranes. The preservation of the inhibitory effect following addition of charged polymers on either side of the supporting membrane suggests the presence of multiple binding sites within the channel's structure and a multistep inhibition mechanism that involves binding and trapping. Complete blockage of the binding sites with divalent cations prevents further inhibition in conductance induced by the addition of cationic polymers and supports the hypothesis that the binding sites are identical for both multivalent metal cations and charged polymers. The investigation at the single-channel level has shown distinct complete blockages of each of the inserted channels. These findings reveal key structural characteristics which may provide insight into lysenin’s functionality while opening innovative approaches for the development of applications such as transient cell permeabilization and advanced drug delivery systems.

A conformational switch high-throughput screening assay and allosteric inhibition of the flavivirus NS2B-NS3 protease.

Directory of Open Access Journals (Sweden)

Matthew Brecher

2017-05-01

Full Text Available The flavivirus genome encodes a single polyprotein precursor requiring multiple cleavages by host and viral proteases in order to produce the individual proteins that constitute an infectious virion. Previous studies have revealed that the NS2B cofactor of the viral NS2B-NS3 heterocomplex protease displays a conformational dynamic between active and inactive states. Here, we developed a conformational switch assay based on split luciferase complementation (SLC to monitor the conformational change of NS2B and to characterize candidate allosteric inhibitors. Binding of an active-site inhibitor to the protease resulted in a conformational change of NS2B and led to significant SLC enhancement. Mutagenesis of key residues at an allosteric site abolished this induced conformational change and SLC enhancement. We also performed a virtual screen of NCI library compounds to identify allosteric inhibitors, followed by in vitro biochemical screening of the resultant candidates. Only three of these compounds, NSC135618, 260594, and 146771, significantly inhibited the protease of Dengue virus 2 (DENV2 in vitro, with IC50 values of 1.8 μM, 11.4 μM, and 4.8 μM, respectively. Among the three compounds, only NSC135618 significantly suppressed the SLC enhancement triggered by binding of active-site inhibitor in a dose-dependent manner, indicating that it inhibits the conformational change of NS2B. Results from virus titer reduction assays revealed that NSC135618 is a broad spectrum flavivirus protease inhibitor, and can significantly reduce titers of DENV2, Zika virus (ZIKV, West Nile virus (WNV, and Yellow fever virus (YFV on A549 cells in vivo, with EC50 values in low micromolar range. In contrast, the cytotoxicity of NSC135618 is only moderate with CC50 of 48.8 μM on A549 cells. Moreover, NSC135618 inhibited ZIKV in human placental and neural progenitor cells relevant to ZIKV pathogenesis. Results from binding, kinetics, Western blot, mass spectrometry and

Finding of no significant impact shipment of stabilized mixed waste from the K-25 Site to an off-site commercial disposal facility, Oak Ridge K-25 Site, Oak Ridge, Tennessee

International Nuclear Information System (INIS)

1994-01-01

The Department of Energy (DOE) has prepared an Environmental Assessment (EA) for the shipment of stabilized mixed waste, removed from K-1407-B and -C ponds, to an off-site commercial disposal facility (Envirocare) for permanent land disposal. Based on the analysis in the EA, DOE has determined that the proposed action is not a major federal action significantly affecting the quality of the human environment, within the meaning of the National Environmental Policy Act (NEPA) of 1969. Therefore, the preparation of an environmental impact statement (EIS) is not required, and DOE is issuing this Finding of No Significant Impact (FONSI)

Fast inhibition of glutamate-activated currents by caffeine.

Directory of Open Access Journals (Sweden)

Nicholas P Vyleta

Full Text Available BACKGROUND: Caffeine stimulates calcium-induced calcium release (CICR in many cell types. In neurons, caffeine stimulates CICR presynaptically and thus modulates neurotransmitter release. METHODOLOGY/PRINCIPAL FINDINGS: Using the whole-cell patch-clamp technique we found that caffeine (20 mM reversibly increased the frequency and decreased the amplitude of miniature excitatory postsynaptic currents (mEPSCs in neocortical neurons. The increase in mEPSC frequency is consistent with a presynaptic mechanism. Caffeine also reduced exogenously applied glutamate-activated currents, confirming a separate postsynaptic action. This inhibition developed in tens of milliseconds, consistent with block of channel currents. Caffeine (20 mM did not reduce currents activated by exogenous NMDA, indicating that caffeine block is specific to non-NMDA type glutamate receptors. CONCLUSIONS/SIGNIFICANCE: Caffeine-induced inhibition of mEPSC amplitude occurs through postsynaptic block of non-NMDA type ionotropic glutamate receptors. Caffeine thus has both pre and postsynaptic sites of action at excitatory synapses.

Naloxone inhibits superoxide but not enzyme release by human neutrophils

Energy Technology Data Exchange (ETDEWEB)

Simpkins, C.; Alailima, S.; Tate, E.

1986-03-01

The release of toxic oxygen metabolites and enzymes by phagocytic cells is thought to play a role in the multisystemic tissue injury of sepsis. Naloxone protects septic animals. We have found that at concentrations administered to animals (10/sup -7/ to 10/sup -4/M), naloxone inhibited (p < .001) the release of superoxide (O/sub 2//sup -/) by human neutrophils (HN), stimulated with N-formyl methionyl leucyl phenylalanine (FMLP). Naloxone had no effect on cell viability. Maximum inhibition was 65% of the total O/sub 2//sup -/ released (13.1 nMoles/8 min/320,000 cells). FMLP-stimulated release of beta-glucoronidase or lysozyme was not altered by naloxone. Naloxone had no effect on the binding of /sup 3/H FMLP to HN. Using /sup 3/H naloxone and various concentrations of unlabeled naloxone higher affinity (K/sub D/ = 12nM) and lower affinity (K/sub D/ = 4.7 x 10/sup -5/) binding sites were detected. The K/sub D/ of the low affinity site corresponded to the ED/sub 50/ for naloxone inhibition of O/sub 2//sup -/ (1 x 10/sup -5/M). Binding to this low affinity site was decreased by (+) naloxone, beta-endorphin and N acetyl beta-endorphin, but not by leu-enkephalin, thyrotropin releasing factor, prostaglandin D/sub 2/ or E/sub 2/. Conclusions: (1) naloxone inhibits FMLP-stimulated O/sub 2/ but not enzyme release, (2) this inhibition is not due to alteration of FMLP receptor binding, (3) naloxone may act via a low affinity binding site which is ligand specific, and (4) a higher affinity receptor is present on HN.

Neural Synchrony during Response Production and Inhibition

Science.gov (United States)

Müller, Viktor; Anokhin, Andrey P.

2012-01-01

Inhibition of irrelevant information (conflict monitoring) and/or of prepotent actions is an essential component of adaptive self-organized behavior. Neural dynamics underlying these functions has been studied in humans using event-related brain potentials (ERPs) elicited in Go/NoGo tasks that require a speeded motor response to the Go stimuli and withholding a prepotent response when a NoGo stimulus is presented. However, averaged ERP waveforms provide only limited information about the neuronal mechanisms underlying stimulus processing, motor preparation, and response production or inhibition. In this study, we examine the cortical representation of conflict monitoring and response inhibition using time-frequency analysis of electroencephalographic (EEG) recordings during continuous performance Go/NoGo task in 50 young adult females. We hypothesized that response inhibition would be associated with a transient boost in both temporal and spatial synchronization of prefrontal cortical activity, consistent with the role of the anterior cingulate and lateral prefrontal cortices in cognitive control. Overall, phase synchronization across trials measured by Phase Locking Index and phase synchronization between electrode sites measured by Phase Coherence were the highest in the Go and NoGo conditions, intermediate in the Warning condition, and the lowest under Neutral condition. The NoGo condition was characterized by significantly higher fronto-central synchronization in the 300–600 ms window, whereas in the Go condition, delta- and theta-band synchronization was higher in centro-parietal regions in the first 300 ms after the stimulus onset. The present findings suggest that response production and inhibition is supported by dynamic functional networks characterized by distinct patterns of temporal and spatial synchronization of brain oscillations. PMID:22745691

Neural synchrony during response production and inhibition.

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Viktor Müller

Full Text Available Inhibition of irrelevant information (conflict monitoring and/or of prepotent actions is an essential component of adaptive self-organized behavior. Neural dynamics underlying these functions has been studied in humans using event-related brain potentials (ERPs elicited in Go/NoGo tasks that require a speeded motor response to the Go stimuli and withholding a prepotent response when a NoGo stimulus is presented. However, averaged ERP waveforms provide only limited information about the neuronal mechanisms underlying stimulus processing, motor preparation, and response production or inhibition. In this study, we examine the cortical representation of conflict monitoring and response inhibition using time-frequency analysis of electroencephalographic (EEG recordings during continuous performance Go/NoGo task in 50 young adult females. We hypothesized that response inhibition would be associated with a transient boost in both temporal and spatial synchronization of prefrontal cortical activity, consistent with the role of the anterior cingulate and lateral prefrontal cortices in cognitive control. Overall, phase synchronization across trials measured by Phase Locking Index and phase synchronization between electrode sites measured by Phase Coherence were the highest in the Go and NoGo conditions, intermediate in the Warning condition, and the lowest under Neutral condition. The NoGo condition was characterized by significantly higher fronto-central synchronization in the 300-600 ms window, whereas in the Go condition, delta- and theta-band synchronization was higher in centro-parietal regions in the first 300 ms after the stimulus onset. The present findings suggest that response production and inhibition is supported by dynamic functional networks characterized by distinct patterns of temporal and spatial synchronization of brain oscillations.

Tyrosine phosphorylation of Jak2 in the JH2 domain inhibits cytokine signaling.

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Feener, Edward P; Rosario, Felicia; Dunn, Sarah L; Stancheva, Zlatina; Myers, Martin G

2004-06-01

Jak family tyrosine kinases mediate signaling by cytokine receptors to regulate diverse biological processes. Although Jak2 and other Jak kinase family members are phosphorylated on numerous sites during cytokine signaling, the identity and function of most of these sites remains unknown. Using tandem mass spectroscopic analysis of activated Jak2 protein from intact cells, we identified Tyr(221) and Tyr(570) as novel sites of Jak2 phosphorylation. Phosphorylation of both sites was stimulated by cytokine treatment of cultured cells, and this stimulation required Jak2 kinase activity. While we observed no gross alteration of signaling upon mutation of Tyr(221), Tyr(570) lies within the inhibitory JH2 domain of Jak2, and mutation of this site (Jak2(Y570F)) results in constitutive Jak2-dependent signaling in the absence of cytokine stimulation and enhances and prolongs Jak2 activation during cytokine stimulation. Mutation of Tyr(570) does not alter the ability of SOCS3 to bind or inhibit Jak2, however. Thus, the phosphorylation of Tyr(570) in vivo inhibits Jak2-dependent signaling independently of SOCS3-mediated inhibition. This Tyr(570)-dependent mechanism of Jak2 inhibition likely represents an important mechanism by which cytokine function is regulated.

Significance of serum tumor markers monitoring in carcinomas of unknown primary site

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Pejčić Ivica

2010-01-01

Full Text Available Background/Aim. Unknown primary tumors represent a heterogeneous group of malignancies that are indicative of ominous prognosis. Cancer of unknown primary site (CUP is defined as the lack of any detectable primary site after full evaluation, and accounts for approximately 3-5% of all newly diagnosed patients with malignancies. The aim of this report was to present the prognostic and predictive value of 8 serum tumor markers in this group of patients. Methods. The study involved 63 patients. On histological examination, all the patients were presented with metastatic tumors whose primary site (origin could not be detected with noninvasive diagnostic techniques. Following the routine light microscopy, all histological findings were classified into one of the following three groups: plano-cellular carcinoma - 8 patients; adenocarcinoma - 33 patients; unclassifiable (undifferentiated carcinoma - 22 patients. In all the cases we evaluated 8 serum tumor markers: alpha-fetoproteins (AFP, chronic gonadotrophin beta submit, human (beta-HCG, neuron specific enolase (NSE, marker of malignant ovarian tumors (CA 125, prostate-specific antigene (PSA, marker of malignant brest tumor (CA 15-3, marker of malignant pancreas tumor and gastrointestinal tumor (Ca 19-9, carcinoembryonic antigen (CEA at the time of diagnosis. The patients on chemotherapy had the markers determined after the third and sixth chemocycle, i.e. at the time of illness progression observation, if present. The patients responding to chemotherapy with complete response (CR, partial response (PR or stable disease (SD had the markers determined after three-month periods until the time of relapse or progression. Chemotherapy was applied in 32 patients (20 females and 12 males, aged 29-70 years, who met the inclusion criteria. The following chemotherapy regimen was used: doxorubicin 50mg/m2 (day 1, cisplatin 60mg/m2 (day 1, and etoposide 120 mg/m2 (days 1-3. The period between two chemotherapy

Picomolar-affinity binding and inhibition of adenylate cyclase activity by melatonin in Syrian hamster hypothalamus

International Nuclear Information System (INIS)

Niles, L.P.; Hashemi, F.

1990-01-01

1. The effect of melatonin on forskolin-stimulated adenylate cyclase activity was measured in homogenates of Syrian hamster hypothalamus. In addition, the saturation binding characteristics of the melatonin receptor ligand, [ 125 I]iodomelatonin, was examined using an incubation temperature (30 degree C) similar to that used in enzyme assays. 2. At concentrations ranging from 10 pM to 1 nM, melatonin caused a significant decrease in stimulated adenylate cyclase activity with a maximum inhibition of approximately 22%. 3. Binding experiments utilizing [ 125 I]iodomelatonin in a range of approximately 5-80 pM indicated a single class of high-affinity sites: Kd = 55 +/- 9 pM, Bmax = 1.1 +/- 0.3 fmol/mg protein. 4. The ability of picomolar concentrations of melatonin to inhibit forskolin-stimulated adenylate cyclase activity suggests that this affect is mediated by picomolar-affinity receptor binding sites for this hormone in the hypothalamus

Curcumin-induced histone acetylation inhibition improves stress-induced gastric ulcer disease in rats.

Science.gov (United States)

He, Ping; Zhou, Renmin; Hu, Guorui; Liu, Zhifeng; Jin, Yu; Yang, Guang; Li, Mei; Lin, Qian

2015-03-01

Curcumin is known to possess anti‑inflammatory properties. Despite the fact that curcumin is known to be a strong inhibitor of H+, K+‑ATPase activity, the mechanism underlying the curcumin‑induced inhibition of the transcription of the H+, K+‑ATPase α subunit in gastric mucosal parietal cells remains unclear. The present study investigated the possible mechanism by which curcumin inhibits stomach H+, K+‑ATPase activity during the acute phase of gastric ulcer disease. A rat model of stress‑induced gastric ulcers was produced, in which the anti‑ulcer effects of curcumin were examined. Curcumin‑induced inhibition of the H+, K+‑ATPase promoter via histone acetylation, was verified using a chromatin immunoprecipitation assay. The results showed that curcumin improved stress‑induced gastric ulcer disease in rats, as demonstrated by increased pH values and reduced gastric mucosal hemorrhage and ulcer index. These effects were accompanied by a significant reduction in the level of histone H3 acetylation at the site of the H+, K+‑ATPase promoter and in the expression of the gastric H+,K+‑ATPase α subunit gene and protein. In conclusion, curcumin downregulated the acetylation of histone H3 at the site of the H+, K+‑ATPase promoter gene, thereby inhibiting the transcription and expression of the H+, K+‑ATPase gene. Curcumin was shown to have a preventive and therapeutic effect in gastric ulcer disease.

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition.

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Yallappa Rajashekar

Full Text Available Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

Interpreting the clinical significance of the differential inhibition of cyclooxygenase-1 and cyclooxygenase-2

NARCIS (Netherlands)

Brooks, P; Emery, P; Evans, JF; Fenner, H; Hawkey, CJ; Patrono, C; Smolen, J; Breeveld, F; Day, R; Dougados, M; Ehrich, EW; Gijon-Banos, J; Kvien, TK; Van Rijswijk, MH; Warner, T; Zeidler, H

The International Consensus Meeting on the Mode of Action of COX-2 Inhibition (ICMMAC) brought together 17 international experts in arthritis, gastroenterology and pharmacology on 5-6 December 1997. The meeting was convened to provide a definition of COX-2 specificity and to consider the clinical

CHROMATE INHIBITION OF THE LOCALIZED CORROSION OF ALUMINUM: MEASUREMENTS OF ELECTROCHEMICAL TRANSIENTS

International Nuclear Information System (INIS)

SASAKI, K.; ISAACS, H.S.

2001-01-01

We investigated the inhibition by chromate ions of the localized corrosion of aluminum by electrochemical transient measurements. In agreement with other work, the measurements demonstrated that chromate is a cathodic inhibitor for aluminum in open circuit. The reduction of hexavalent chromium to trivalent chromium is assumed to take place on catalyzed sites of the surface. The resulting products inhibit oxygen reduction reactions at these sites, thereby retarding pitting corrosion

Finding of no significant impact proposed corrective action for the Northeast Site at the Pinellas Plant in Largo, Florida

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-06-01

The U.S. Department of Energy (DOE) has prepared an Environmental Assessment (EA) (DOE/EA-0976) of the proposed corrective action for the Northeast Site at the Pinellas Plant in Largo, Florida. The Northeast Site contains contaminated groundwater that would be removed, treated, and discharged to the Pinellas County Sewer System. Based on the analyses in the EA, the DOE has determined that the proposed action is not a major Federal action significantly affecting the quality of the human environment, within the meaning of the National Environmental Policy Act of 1969 (NEPA), 42 U.S.C.4321 et.seq. Therefore, the preparation of an environmental impact statement is not required and the DOE is issuing this Finding of No Significant Impact (FONSI).

Protein kinase C epsilon mediates the inhibition of angiotensin II on the slowly activating delayed-rectifier potassium current through channel phosphorylation.

Science.gov (United States)

Gou, Xiangbo; Wang, Wenying; Zou, Sihao; Qi, Yajuan; Xu, Yanfang

2018-03-01

The slowly activating delayed rectifier K + current (I Ks ) is one of the main repolarizing currents in the human heart. Evidence has shown that angiotensin II (Ang II) regulates I Ks through the protein kinase C (PKC) pathway, but the related results are controversial. This study was designed to identify PKC isoenzymes involved in the regulation of I Ks by Ang II and the underlying molecular mechanism. The whole-cell patch-clamp technique was used to record I Ks in isolated guinea pig ventricular cardiomyocytes and in human embryonic kidney (HEK) 293 cells co-transfected with human KCNQ1/KCNE1 genes and Ang II type 1 receptor genes. Ang II inhibited I Ks in a concentration-dependent manner in native cardiomyocytes. A broad PKC inhibitor Gö6983 (not inhibiting PKCε) and a selective cPKC inhibitor Gö6976 did not affect the inhibitory action of Ang II. In contrast, the inhibition was significantly attenuated by PKCε-selective peptide inhibitor εV1-2. However, direct activation of PKC by phorbol 12-myristate 13-acetate (PMA) increased the cloned human I Ks in HEK293 cells. Similarly, the cPKC peptide activator significantly enhanced the current. In contrast, the PKCε peptide activator inhibited the current. Further evidence showed that PKCε knockdown by siRNA antagonized the Ang II-induced inhibition on KCNQ1/KCNE1 current, whereas knockdown of cPKCs (PKCα and PKCβ) attenuated the potentiation of the current by PMA. Moreover, deletion of four putative phosphorylation sites in the C-terminus of KCNQ1 abolished the action of PMA. Mutation of two putative phosphorylation sites in the N-terminus of KCNQ1 and one site in KCNE1 (S102) blocked the inhibition of Ang II. Our results demonstrate that PKCε isoenzyme mediates the inhibitory action of Ang II on I Ks and by phosphorylating distinct sites in KCNQ1/KCNE1, cPKC and PKCε isoenzymes produce the contrary regulatory effects on the channel. These findings have provided new insight into the molecular mechanism

Synthesis and Antimycobacterial and Photosynthesis-Inhibiting Evaluation of 2-[(E-2-Substituted-ethenyl]-1,3-benzoxazoles

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Ales Imramovsky

2014-01-01

Full Text Available A series of twelve 2-[(E-2-substituted-ethenyl]-1,3-benzoxazoles was designed. All the synthesized compounds were tested against three mycobacterial strains. The compounds were also evaluated for their ability to inhibit photosynthetic electron transport (PET in spinach (Spinacia oleracea L. chloroplasts. 2-[(E-2-(4-Methoxyphenylethenyl]-1,3-benzoxazole, 2-[(E-2-(2,3-dihydro-1-benzofuran-5-ylethenyl]-1,3-benzoxazole and 2-{(E-2-[4-(methylsulfanylphenyl]ethenyl}-1,3-benzoxazole showed the highest activity against M. tuberculosis, M. kansasii, and M. avium, and they demonstrated significantly higher activity against M. avium and M. kansasii than isoniazid. The PET-inhibiting activity of the most active ortho-substituted compound 2-[(E-2-(2-methoxyphenylethenyl]-1,3-benzoxazole was IC50 = 76.3 μmol/L, while the PET-inhibiting activity of para-substituted compounds was significantly lower. The site of inhibitory action of tested compounds is situated on the donor side of photosystem II. The structure-activity relationships are discussed.

The structure of F1-ATPase from Saccharomyces cerevisiae inhibited by its regulatory protein IF1

Science.gov (United States)

Robinson, Graham C.; Bason, John V.; Montgomery, Martin G.; Fearnley, Ian M.; Mueller, David M.; Leslie, Andrew G. W.; Walker, John E.

2013-01-01

The structure of F1-ATPase from Saccharomyces cerevisiae inhibited by the yeast IF1 has been determined at 2.5 Å resolution. The inhibitory region of IF1 from residues 1 to 36 is entrapped between the C-terminal domains of the αDP- and βDP-subunits in one of the three catalytic interfaces of the enzyme. Although the structure of the inhibited complex is similar to that of the bovine-inhibited complex, there are significant differences between the structures of the inhibitors and their detailed interactions with F1-ATPase. However, the most significant difference is in the nucleotide occupancy of the catalytic βE-subunits. The nucleotide binding site in βE-subunit in the yeast complex contains an ADP molecule without an accompanying magnesium ion, whereas it is unoccupied in the bovine complex. Thus, the structure provides further evidence of sequential product release, with the phosphate and the magnesium ion released before the ADP molecule. PMID:23407639

COBRA1 inhibits AP-1 transcriptional activity in transfected cells

International Nuclear Information System (INIS)

Zhong Hongjun; Zhu Jianhua; Zhang Hao; Ding Lihua; Sun Yan; Huang Cuifen; Ye Qinong

2004-01-01

Mutations in the breast cancer susceptibility gene (BRCA1) account for a significant proportion of hereditary breast and ovarian cancers. Cofactor of BRCA1 (COBRA1) was isolated as a BRCA1-interacting protein and exhibited a similar chromatin reorganizing activity to that of BRCA1. However, the biological role of COBRA1 remains largely unexplored. Here, we report that ectopic expression of COBRA1 inhibited activator protein 1 (AP-1) transcriptional activity in transfected cells in a dose-dependent manner, whereas reduction of endogenous COBRA1 with a small interfering RNA significantly enhanced AP-1-mediated transcriptional activation. COBRA1 physically interacted with the AP-1 family members, c-Jun and c-Fos, and the middle region of COBRA1 bound to c-Fos. Lack of c-Fos binding site in the COBRA1 completely abolished the COBRA1 inhibition of AP-1 trans-activation. These findings suggest that COBRA1 may directly modulate AP-1 pathway and, therefore, may play important roles in cell proliferation, differentiation, apoptosis, and oncogenesis

Zinc ions bind to and inhibit activated protein C

DEFF Research Database (Denmark)

Zhu, Tianqing; Ubhayasekera, Wimal; Nickolaus, Noëlle

2010-01-01

fold enhanced, presumably due to the Ca2+-induced conformational change affecting the conformation of the Zn2+-binding site. The inhibition mechanism was non-competitive both in the absence and presence of Ca2+. Comparisons of sequences and structures suggested several possible sites for zinc binding...

Large enhancement of functional activity of active site-inhibited factor VIIa due to protein dimerization: insights into mechanism of assembly/disassembly from tissue factor.

Science.gov (United States)

Stone, Matthew D; Harvey, Stephen B; Martinez, Michael B; Bach, Ronald R; Nelsestuen, Gary L

2005-04-26

Active site-inhibited blood clotting factor VIIa (fVIIai) binds to tissue factor (TF), a cell surface receptor that is exposed upon injury and initiates the blood clotting cascade. FVIIai blocks binding of the corresponding enzyme (fVIIa) or zymogen (fVII) forms of factor VII and inhibits coagulation. Although several studies have suggested that fVIIai may have superior anticoagulation effects in vivo, a challenge for use of fVIIai is cost of production. This study reports the properties of dimeric forms of fVIIai that are cross-linked through their active sites. Dimeric wild-type fVIIai was at least 75-fold more effective than monomeric fVIIai in blocking fVIIa association with TF. The dimer of a mutant fVIIai with higher membrane affinity was 1600-fold more effective. Anticoagulation by any form of fVIIai differed substantially from agents such as heparin and showed a delayed mode of action. Coagulation proceeded normally for the first minutes, and inhibition increased as equilibrium binding was established. It is suggested that association of fVIIa(i) with TF in a collision-dependent reaction gives equal access of inhibitor and enzyme to TF. Assembly was not influenced by the higher affinity and slower dissociation of the dimer. As a result, anticoagulation was delayed until the reaction reached equilibrium. Properties of different dissociation experiments suggested that dissociation of fVIIai from TF occurred by a two-step mechanism. The first step was separation of TF-fVIIa(i) while both proteins remained bound to the membrane, and the second step was dissociation of the fVIIa(i) from the membrane. These results suggest novel actions of fVIIai that distinguish it from most of the anticoagulants that block later steps of the coagulation cascade.

Inhibition of neutrophil migration by aggregated immunoglobulin attached to micropore membranes.

Science.gov (United States)

Kemp, A S; Brown, S

1980-01-01

The effect of substrate-bound immunoglobulin on neutrophil migration was examined. Immunoglobulin aggregates bound to micropore membranes inhibited the neutrophil response to a chemotactic stimulus. This inhibition was reversed by the presence of aggregates in suspension suggesting competition between substrate-bound and free aggregates for neutrophil surface binding sites. The immobilization of neutrophils by substrate-bound aggregated immunoglobulin suggests a mechanism for the accumulation of neutrophils at sites of immune complex deposition and tissue-bound antibodies in vivo. PMID:7380477

Molecular basis of inhibition of acid sensing ion channel 1A by diminazene.

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Aram J Krauson

Full Text Available Acid-sensing ion channels (ASICs are trimeric proton-gated cation permeable ion channels expressed primarily in neurons. Here we employed site-directed mutagenesis and electrophysiology to investigate the mechanism of inhibition of ASIC1a by diminazene. This compound inhibits mouse ASIC1a with a half-maximal inhibitory concentration (IC50 of 2.4 μM. At first, we examined whether neutralizing mutations of Glu79 and Glu416 alter diminazene block. These residues form a hexagonal array in the lower palm domain that was previously shown to contribute to pore opening in response to extracellular acidification. Significantly, single Gln substitutions at positions 79 and 416 in ASIC1a reduced diminazene apparent affinity by 6-7 fold. This result suggests that diminazene inhibits ASIC1a in part by limiting conformational rearrangement in the lower palm domain. Because diminazene is charged at physiological pHs, we assessed whether it inhibits ASIC1a by blocking the ion channel pore. Consistent with the notion that diminazene binds to a site within the membrane electric field, diminazene block showed a strong dependence with the membrane potential. Moreover, a Gly to Ala mutation at position 438, in the ion conduction pathway of ASIC1a, increased diminazene IC50 by one order of magnitude and eliminated the voltage dependence of block. Taken together, our results indicate that the inhibition of ASIC1a by diminazene involves both allosteric modulation and blocking of ion flow through the conduction pathway. Our findings provide a foundation for the development of more selective and potent ASIC pore blockers.

Single residue mutation in active site of serine acetyltransferase isoform 3 from Entamoeba histolytica assists in partial regaining of feedback inhibition by cysteine.

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Sudhir Kumar

Full Text Available The cysteine biosynthetic pathway is essential for survival of the protist pathogen Entamoeba histolytica, and functions by producing cysteine for countering oxidative attack during infection in human hosts. Serine acetyltransferase (SAT and O-acetylserine sulfhydrylase (OASS are involved in cysteine biosynthesis and are present in three isoforms each. While EhSAT1 and EhSAT2 are feedback inhibited by end product cysteine, EhSAT3 is nearly insensitive to such inhibition. The active site residues of EhSAT1 and of EhSAT3 are identical except for position 208, which is a histidine residue in EhSAT1 and a serine residue in EhSAT3. A combination of comparative modeling, multiple molecular dynamics simulations and free energy calculation studies showed a difference in binding energies of native EhSAT3 and of a S208H-EhSAT3 mutant for cysteine. Mutants have also been generated in vitro, replacing serine with histidine at position 208 in EhSAT3 and replacing histidine 208 with serine in EhSAT1. These mutants showed decreased affinity for substrate serine, as indicated by K(m, compared to the native enzymes. Inhibition kinetics in the presence of physiological concentrations of serine show that IC50 of EhSAT1 increases by about 18 folds from 9.59 µM for native to 169.88 µM for H208S-EhSAT1 mutant. Similar measurements with EhSAT3 confirm it to be insensitive to cysteine inhibition while its mutant (S208H-EhSAT3 shows a gain of cysteine inhibition by 36% and the IC50 of 3.5 mM. Histidine 208 appears to be one of the important residues that distinguish the serine substrate from the cysteine inhibitor.

Evidence of dopaminergic processing of executive inhibition.

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Rajendra D Badgaiyan

Full Text Available Inhibition of unwanted response is an important function of the executive system. Since the inhibitory system is impaired in patients with dysregulated dopamine system, we examined dopamine neurotransmission in the human brain during processing of a task of executive inhibition. The experiment used a recently developed dynamic molecular imaging technique to detect and map dopamine released during performance of a modified Eriksen's flanker task. In this study, young healthy volunteers received an intravenous injection of a dopamine receptor ligand ((11C-raclopride after they were positioned in the PET camera. After the injection, volunteers performed the flanker task under Congruent and Incongruent conditions in a single scan session. They were required to inhibit competing options to select an appropriate response in the Incongruent but not in the Congruent condition. The PET data were dynamically acquired during the experiment and analyzed using two variants of the simplified reference region model. The analysis included estimation of a number of receptor kinetic parameters before and after initiation of the Incongruent condition. We found increase in the rate of ligand displacement (from receptor sites and decrease in the ligand binding potential in the Incongruent condition, suggesting dopamine release during task performance. These changes were observed in small areas of the putamen and caudate bilaterally but were most significant on the dorsal aspect of the body of left caudate. The results provide evidence of dopaminergic processing of executive inhibition and demonstrate that neurochemical changes associated with cognitive processing can be detected and mapped in a single scan session using dynamic molecular imaging.

Human cytosolic glutathione-S-transferases: quantitative analysis of expression, comparative analysis of structures and inhibition strategies of isozymes involved in drug resistance.

Science.gov (United States)

Mohana, Krishnamoorthy; Achary, Anant

2017-08-01

Glutathione-S-transferase (GST) inhibition is a strategy to overcome drug resistance. Several isoforms of human GSTs are present and they are expressed in almost all the organs. Specific expression levels of GSTs in various organs are collected from the human transcriptome data and analysis of the organ-specific expression of GST isoforms is carried out. The variations in the level of expressions of GST isoforms are statistically significant. The GST expression differs in diseased conditions as reported by many investigators and some of the isoforms of GSTs are disease markers or drug targets. Structure analysis of various isoforms is carried out and literature mining has been performed to identify the differences in the active sites of the GSTs. The xenobiotic binding H site is classified into H1, H2, and H3 and the differences in the amino acid composition, the hydrophobicity and other structural features of H site of GSTs are discussed. The existing inhibition strategies are compared. The advent of rational drug design, mechanism-based inhibition strategies, availability of high-throughput screening, target specific, and selective inhibition of GST isoforms involved in drug resistance could be achieved for the reversal of drug resistance and aid in the treatment of diseases.

Topoisomerase I tyrosine phosphorylation site and the DNA-interactive site

International Nuclear Information System (INIS)

Roll, D.; Durban, E.

1986-01-01

Phosphorylation of topoisomerase I (topo I) at serine by NII kinase is accompanied by stimulation of enzymatic activity. In contrast, phosphorylation at tyrosine by tyrosine kinase seems to inhibit enzymatic activity. This inhibition may be caused by interference of the phosphorylated tyrosine residue with the interaction of topo I with DNA. To test this, topo I was labeled with crude membrane fraction enriched for EGF-receptor kinase in presence of γ-P32-ATP and electrophoresed on SDS-polyacrylamide gels. Stained topo I bands were excised, dried, digested with trypsin and analyzed on a C18 reverse-phase HPLC column. One major peak of radioactivity eluted at fraction 23 with 20% acetonitrile. To obtain the DNA-interactive site, topo I was incubated with pBR322 DNA labeled by nick-translation followed by DNase I treatment, and electrophoresis on SDS-polyacrylamide gels. Tryptic peptides were generated and analyzed by reverse-phase HPLC. A major peak of radioactivity eluted at fraction 16-18 with 15.5-17% acetonitrile. Studies are in progress to resolve whether (a) the two peptides are different, i.e. the tyrosine-P site and DNA-tyrosine interactive site are localized at different regions of the topo I or (b) the peptide sequences are identical but the covalent attachment of deoxynucleotides altered the peptide's elution from the HPLC column

Zinc-mediated Allosteric Inhibition of Caspase-6*

Science.gov (United States)

Velázquez-Delgado, Elih M.; Hardy, Jeanne A.

2012-01-01

Zinc and caspase-6 have independently been implicated in several neurodegenerative disorders. Depletion of zinc intracellularly leads to apoptosis by an unknown mechanism. Zinc inhibits cysteine proteases, including the apoptotic caspases, leading to the hypothesis that zinc-mediated inhibition of caspase-6 might contribute to its regulation in a neurodegenerative context. Using inductively coupled plasma optical emission spectroscopy, we observed that caspase-6 binds one zinc per monomer, under the same conditions where the zinc leads to complete loss of enzymatic activity. To understand the molecular details of zinc binding and inhibition, we performed an anomalous diffraction experiment above the zinc edge. The anomalous difference maps showed strong 5σ peaks, indicating the presence of one zinc/monomer bound at an exosite distal from the active site. Zinc was not observed bound to the active site. The zinc in the exosite was liganded by Lys-36, Glu-244, and His-287 with a water molecule serving as the fourth ligand, forming a distorted tetrahedral ligation sphere. This exosite appears to be unique to caspase-6, as the residues involved in zinc binding were not conserved across the caspase family. Our data suggest that binding of zinc at the exosite is the primary route of inhibition, potentially locking caspase-6 into the inactive helical conformation. PMID:22891250

Thrombin-inhibiting nanoparticles rapidly constitute versatile and detectable anticlotting surfaces

Science.gov (United States)

Wheatley Myerson, Jacob; He, Li; Allen, John Stacy; Williams, Todd; Lanza, Gregory; Tollefsen, Douglas; Caruthers, Shelton; Wickline, Samuel

2014-09-01

Restoring an antithrombotic surface to suppress ongoing thrombosis is an appealing strategy for treatment of acute cardiovascular disorders such as erosion of atherosclerotic plaque. An antithrombotic surface would present an alternative to systemic anticoagulation with attendant risks of bleeding. We have designed thrombin-targeted nanoparticles (NPs) that bind to sites of active clotting to extinguish local thrombin activity and inhibit platelet deposition while exhibiting only transient systemic anticoagulant effects. Perfluorocarbon nanoparticles (PFC NP) were functionalized with thrombin inhibitors (either D-phenylalanyl-L-prolyl-L-arginyl-chloromethyl ketone or bivalirudin) by covalent attachment of more than 15 000 inhibitors to each PFC NP. Fibrinopeptide A (FPA) ELISA demonstrated that thrombin-inhibiting NPs prevented cleavage of fibrinogen by both free and clot-bound thrombin. Magnetic resonance imaging (MRI) confirmed that a layer of thrombin-inhibiting NPs prevented growth of clots in vitro. Thrombin-inhibiting NPs were administered in vivo to C57BL6 mice subjected to laser injury of the carotid artery. NPs significantly delayed thrombotic occlusion of the artery, whereas an equivalent bolus of free inhibitor was ineffective. For thrombin-inhibiting NPs, only a short-lived (˜10 min) systemic effect on bleeding time was observed, despite prolonged clot inhibition. Imaging and quantification of in vivo antithrombotic NP layers was demonstrated by MRI of the PFC NP. 19F MRI confirmed colocalization of particles with arterial thrombi, and quantitative 19F spectroscopy demonstrated specific binding and retention of thrombin-inhibiting NPs in injured arteries. The ability to rapidly form and image a new antithrombotic surface in acute vascular syndromes while minimizing risks of bleeding would permit a safer method of passivating active lesions than current systemic anticoagulant regimes.

Thrombin-inhibiting nanoparticles rapidly constitute versatile and detectable anticlotting surfaces

International Nuclear Information System (INIS)

Myerson, Jacob Wheatley; Lanza, Gregory; Caruthers, Shelton; Wickline, Samuel; He, Li; Allen, John Stacy; Williams, Todd; Tollefsen, Douglas

2014-01-01

Restoring an antithrombotic surface to suppress ongoing thrombosis is an appealing strategy for treatment of acute cardiovascular disorders such as erosion of atherosclerotic plaque. An antithrombotic surface would present an alternative to systemic anticoagulation with attendant risks of bleeding. We have designed thrombin-targeted nanoparticles (NPs) that bind to sites of active clotting to extinguish local thrombin activity and inhibit platelet deposition while exhibiting only transient systemic anticoagulant effects. Perfluorocarbon nanoparticles (PFC NP) were functionalized with thrombin inhibitors (either D-phenylalanyl-L-prolyl-L-arginyl-chloromethyl ketone or bivalirudin) by covalent attachment of more than 15 000 inhibitors to each PFC NP. Fibrinopeptide A (FPA) ELISA demonstrated that thrombin-inhibiting NPs prevented cleavage of fibrinogen by both free and clot-bound thrombin. Magnetic resonance imaging (MRI) confirmed that a layer of thrombin-inhibiting NPs prevented growth of clots in vitro. Thrombin-inhibiting NPs were administered in vivo to C57BL6 mice subjected to laser injury of the carotid artery. NPs significantly delayed thrombotic occlusion of the artery, whereas an equivalent bolus of free inhibitor was ineffective. For thrombin-inhibiting NPs, only a short-lived (∼10 min) systemic effect on bleeding time was observed, despite prolonged clot inhibition. Imaging and quantification of in vivo antithrombotic NP layers was demonstrated by MRI of the PFC NP. 19 F MRI confirmed colocalization of particles with arterial thrombi, and quantitative 19 F spectroscopy demonstrated specific binding and retention of thrombin-inhibiting NPs in injured arteries. The ability to rapidly form and image a new antithrombotic surface in acute vascular syndromes while minimizing risks of bleeding would permit a safer method of passivating active lesions than current systemic anticoagulant regimes. (paper)

A novel mode for transcription inhibition mediated by PNA-induced R-loops with a model in vitro system.

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D'Souza, Alicia D; Belotserkovskii, Boris P; Hanawalt, Philip C

2018-02-01

The selective inhibition of transcription of a chosen gene by an artificial agent has numerous applications. Usually, these agents are designed to bind a specific nucleotide sequence in the promoter or within the transcribed region of the chosen gene. However, since optimal binding sites might not exist within the gene, it is of interest to explore the possibility of transcription inhibition when the agent is designed to bind at other locations. One of these possibilities arises when an additional transcription initiation site (e.g. secondary promoter) is present upstream from the primary promoter of the target gene. In this case, transcription inhibition might be achieved by inducing the formation of an RNA-DNA hybrid (R-loop) upon transcription from the secondary promoter. The R-loop could extend into the region of the primary promoter, to interfere with promoter recognition by RNA polymerase and thereby inhibit transcription. As a sequence-specific R-loop-inducing agent, a peptide nucleic acid (PNA) could be designed to facilitate R-loop formation by sequestering the non-template DNA strand. To investigate this mode for transcription inhibition, we have employed a model system in which a PNA binding site is localized between the T3 and T7 phage RNA polymerase promoters, which respectively assume the roles of primary and secondary promoters. In accord with our model, we have demonstrated that with PNA-bound DNA substrates, transcription from the T7 promoter reduces transcription from the T3 promoter by 30-fold, while in the absence of PNA binding there is no significant effect of T7 transcription upon T3 transcription. Copyright © 2018 Elsevier B.V. All rights reserved.

Statistical significance of cis-regulatory modules

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Smith Andrew D

2007-01-01

Full Text Available Abstract Background It is becoming increasingly important for researchers to be able to scan through large genomic regions for transcription factor binding sites or clusters of binding sites forming cis-regulatory modules. Correspondingly, there has been a push to develop algorithms for the rapid detection and assessment of cis-regulatory modules. While various algorithms for this purpose have been introduced, most are not well suited for rapid, genome scale scanning. Results We introduce methods designed for the detection and statistical evaluation of cis-regulatory modules, modeled as either clusters of individual binding sites or as combinations of sites with constrained organization. In order to determine the statistical significance of module sites, we first need a method to determine the statistical significance of single transcription factor binding site matches. We introduce a straightforward method of estimating the statistical significance of single site matches using a database of known promoters to produce data structures that can be used to estimate p-values for binding site matches. We next introduce a technique to calculate the statistical significance of the arrangement of binding sites within a module using a max-gap model. If the module scanned for has defined organizational parameters, the probability of the module is corrected to account for organizational constraints. The statistical significance of single site matches and the architecture of sites within the module can be combined to provide an overall estimation of statistical significance of cis-regulatory module sites. Conclusion The methods introduced in this paper allow for the detection and statistical evaluation of single transcription factor binding sites and cis-regulatory modules. The features described are implemented in the Search Tool for Occurrences of Regulatory Motifs (STORM and MODSTORM software.

The Mechanistic Basis for Noncompetitive Ibogaine Inhibition of Serotonin and Dopamine Transporters*

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Bulling, Simon; Schicker, Klaus; Zhang, Yuan-Wei; Steinkellner, Thomas; Stockner, Thomas; Gruber, Christian W.; Boehm, Stefan; Freissmuth, Michael; Rudnick, Gary; Sitte, Harald H.; Sandtner, Walter

2012-01-01

Ibogaine, a hallucinogenic alkaloid proposed as a treatment for opiate withdrawal, has been shown to inhibit serotonin transporter (SERT) noncompetitively, in contrast to all other known inhibitors, which are competitive with substrate. Ibogaine binding to SERT increases accessibility in the permeation pathway connecting the substrate-binding site with the cytoplasm. Because of the structural similarity between ibogaine and serotonin, it had been suggested that ibogaine binds to the substrate site of SERT. The results presented here show that ibogaine binds to a distinct site, accessible from the cell exterior, to inhibit both serotonin transport and serotonin-induced ionic currents. Ibogaine noncompetitively inhibited transport by both SERT and the homologous dopamine transporter (DAT). Ibogaine blocked substrate-induced currents also in DAT and increased accessibility of the DAT cytoplasmic permeation pathway. When present on the cell exterior, ibogaine inhibited SERT substrate-induced currents, but not when it was introduced into the cytoplasm through the patch electrode. Similar to noncompetitive transport inhibition, the current block was not reversed by increasing substrate concentration. The kinetics of inhibitor binding and dissociation, as determined by their effect on SERT currents, indicated that ibogaine does not inhibit by forming a long-lived complex with SERT, but rather binds directly to the transporter in an inward-open conformation. A kinetic model for transport describing the noncompetitive action of ibogaine and the competitive action of cocaine accounts well for the results of the present study. PMID:22451652

The mechanistic basis for noncompetitive ibogaine inhibition of serotonin and dopamine transporters.

Science.gov (United States)

Bulling, Simon; Schicker, Klaus; Zhang, Yuan-Wei; Steinkellner, Thomas; Stockner, Thomas; Gruber, Christian W; Boehm, Stefan; Freissmuth, Michael; Rudnick, Gary; Sitte, Harald H; Sandtner, Walter

2012-05-25

Ibogaine, a hallucinogenic alkaloid proposed as a treatment for opiate withdrawal, has been shown to inhibit serotonin transporter (SERT) noncompetitively, in contrast to all other known inhibitors, which are competitive with substrate. Ibogaine binding to SERT increases accessibility in the permeation pathway connecting the substrate-binding site with the cytoplasm. Because of the structural similarity between ibogaine and serotonin, it had been suggested that ibogaine binds to the substrate site of SERT. The results presented here show that ibogaine binds to a distinct site, accessible from the cell exterior, to inhibit both serotonin transport and serotonin-induced ionic currents. Ibogaine noncompetitively inhibited transport by both SERT and the homologous dopamine transporter (DAT). Ibogaine blocked substrate-induced currents also in DAT and increased accessibility of the DAT cytoplasmic permeation pathway. When present on the cell exterior, ibogaine inhibited SERT substrate-induced currents, but not when it was introduced into the cytoplasm through the patch electrode. Similar to noncompetitive transport inhibition, the current block was not reversed by increasing substrate concentration. The kinetics of inhibitor binding and dissociation, as determined by their effect on SERT currents, indicated that ibogaine does not inhibit by forming a long-lived complex with SERT, but rather binds directly to the transporter in an inward-open conformation. A kinetic model for transport describing the noncompetitive action of ibogaine and the competitive action of cocaine accounts well for the results of the present study.

Pilot-scale bioremediation of a petroleum hydrocarbon-contaminated clayey soil from a sub-Arctic site

International Nuclear Information System (INIS)

Akbari, Ali; Ghoshal, Subhasis

2014-01-01

Highlights: • Aeration and moisture addition alone caused extensive hydrocarbon biodegradation. • 30-day slurry reactor remediation endpoints attained in 385 days in biopiles. • High nitrogen concentrations inhibited hydrocarbon degradation. • Inhibition of biodegradation linked to lack of shifts in soil microbial community. - Abstract: Bioremediation is a potentially cost-effective solution for petroleum contamination in cold region sites. This study investigates the extent of biodegradation of petroleum hydrocarbons (C16–C34) in a pilot-scale biopile experiment conducted at 15 °C for periods up to 385 days, with a clayey soil, from a crude oil-impacted site in northern Canada. Although several studies on bioremediation of petroleum hydrocarbon-contaminated soils from cold region sites have been reported for coarse-textured, sandy soils, there are limited studies of bioremediation of petroleum contamination in fine-textured, clayey soils. Our results indicate that aeration and moisture addition was sufficient for achieving 47% biodegradation and an endpoint of 530 mg/kg for non-volatile (C16–C34) petroleum hydrocarbons. Nutrient amendment with 95 mg-N/kg showed no significant effect on biodegradation compared to a control system without nutrient but similar moisture content. In contrast, in a biopile amended with 1340 mg-N/kg, no statistically significant biodegradation of non-volatile fraction was detected. Terminal Restriction Fragment Length Polymorphism (T-RFLP) analyses of alkB and 16S rRNA genes revealed that inhibition of hydrocarbon biodegradation was associated with a lack of change in microbial community composition. Overall, our data suggests that biopiles are feasible for attaining the bioremediation endpoint in clayey soils. Despite the significantly lower biodegradation rate of 0.009 day −1 in biopile tank compared to 0.11 day −1 in slurry bioreactors for C16–C34 hydrocarbons, the biodegradation extents for this fraction were

Inhibition of bovine kidney alpha-ketoglutarate dehydrogenase complex by reduced nicotinamide adenine dinucleotide in the presence or absence of calcium ion and effect of adenosine 5'-diphosphate on reduced nicotinamide adenine dinucleotide inhibition.

Science.gov (United States)

Lawlis, V B; Roche, T E

1981-04-28

Micromolar Ca2+ markedly reduces NADH inhibition of bovine kidney alpha-ketoglutarate dehydrogenase complex [Lawlis, V. B., & Roche, T. E. (1980) Mol. Cell. Biochem. 32, 147-152]. Product inhibition patterns from initial velocity studies conducted at less than 10(-9) M or at 1.5 X 10(-5) M Ca2+ with NAD+, CoA, or alpha-ketoglutarate as the variable substrate showed that NADH was a noncompetitive inhibitor with respect to each of these substrates, except at high NAD+ concentrations, where reciprocal plots were nonlinear and the inhibition pattern for NADH vs. NAD+ changed from a noncompetitive to a competitive pattern. From slope and intercept replots, 2-fold to 12-fold higher inhibition constants were estimated for inhibition by NADH vs. the various substrates in the presence of 1.5 X 10(-5) M Ca2+ than for inhibition at less than 10(-9) M Ca2+. These inhibition patterns and the lack of an effect of Ca2+ on the inhibition of the dihydrolipoyl dehydrogenase component suggested that Ca2+-modulated NADH inhibition occurs at an allosteric site with competitive binding at the site by high levels of NAD+. Decarboxylation of alpha-keto[1-14C]glutarate by the resolved alpha-ketoglutarate dehydrogenase component was investigated in the presence of 5.0 mM glyoxylate which served as an efficient acceptor. NADH (0.2 mM) or 1.0 mM ATP inhibited the partial reaction whereas 15 muM Ca2+, 1.0 mM ADP, or 10 mM NAD+ stimulated the partial reaction and reduced NADH inhibition of this reaction. Thus these effectors alter the activity of the alpha-ketoglutarate dehydrogenase complex by binding at allosteric sites on the alpha-ketoglutarate dehydrogenase component. Inhibition by NADH over a wide range of NADH/NAD+ ratios was measured under conditions in which the level of alpha-ketoglutarate was adjusted to give matching control activities at less than 10(-9) M Ca2+ or 1.5 X 10(-5) M Ca2+ in either the presence or the absence of 1.6 mM ADP. These studies establish that both Ca2+ and ADP

Climate change research methods and its significance in the study of choosing candidate site in nuclear waste disposal sites

International Nuclear Information System (INIS)

Zhao Yong; Zhang Zhanshi

2008-01-01

A high-level nuclear waste is the inevitable product accompanies the development of the nuclear power station. How to dispose it properly has become focused by all over the world. Some of the important progresses have been achieved in the fields of site setting, performance assessment and underground laboratory recently. Palaeoclimate patter and the tendency of climate change are very important aspects for the site setting This paper discussed some of the important progresses on the disposal of unclear wastes, the influence of the climate change on the site setting and main methods such as lake sediments, marine sediment, loess, ancient soil and ice core deal with palaeoclimate and palaeo environment study. (authors)

A novel mouse PKC{delta} splice variant, PKC{delta}IX, inhibits etoposide-induced apoptosis

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung D. [School of Biological Sciences, University of Ulsan, Ulsan (Korea, Republic of); Seo, Kwang W. [Department of Internal Medicines, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of); Lee, Eun A.; Quang, Nguyen N. [School of Biological Sciences, University of Ulsan, Ulsan (Korea, Republic of); Cho, Hong R. [Department of Surgery, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of); Biomedical Research Center, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of); Kwon, Byungsuk, E-mail: bskwon@mail.ulsan.as.kr [School of Biological Sciences, University of Ulsan, Ulsan (Korea, Republic of); Biomedical Research Center, Ulsan University Hospital and School of Medicine, University of Ulsan, Ulsan (Korea, Republic of)

2011-07-01

Highlights: {yields} A novel PKC{delta} isoform, named PKC{delta}IX, that lacks the C1 domain and the ATP-binding site is ubiquitously expressed. {yields} PKC{delta}IX inhibits etoposide-induced apoptosis. {yields} PKC{delta}IX may function as an endogenous dominant negative isoform for PKC{delta}. -- Abstract: Protein kinase C (PKC) {delta} plays an important role in cellular proliferation and apoptosis. The catalytic fragment of PKC{delta} generated by caspase-dependent cleavage is essential for the initiation of etoposide-induced apoptosis. In this study, we identified a novel mouse PKC{delta} isoform named PKC{delta}IX (Genebank Accession No. (HQ840432)). PKC{delta}IX is generated by alternative splicing and is ubiquitously expressed, as seen in its full-length PKC{delta}. PKC{delta}IX lacks the C1 domain, the caspase 3 cleavage site, and the ATP binding site but preserves an almost intact c-terminal catalytic domain and a nuclear localization signal (NLS). The structural characteristics of PKC{delta}IX provided a possibility that this PKC{delta} isozyme functions as a novel dominant-negative form for PKC{delta} due to its lack of the ATP-binding domain that is required for the kinase activity of PKC{delta}. Indeed, overexpression of PKC{delta}IX significantly inhibited etoposide-induced apoptosis in NIH3T3 cells. In addition, an in vitro kinase assay showed that recombinant PKC{delta}IX protein could competitively inhibit the kinase activity of PKC{delta}. We conclude that PKC{delta}IX can function as a natural dominant-negative inhibitor of PKC{delta}in vivo.

Gamabufotalin, a major derivative of bufadienolide, inhibits VEGF-induced angiogenesis by suppressing VEGFR-2 signaling pathway.

Science.gov (United States)

Tang, Ning; Shi, Lei; Yu, Zhenlong; Dong, Peipei; Wang, Chao; Huo, Xiaokui; Zhang, Baojing; Huang, Shanshan; Deng, Sa; Liu, Kexin; Ma, Tonghui; Wang, Xiaobo; Wu, Lijun; Ma, Xiao-Chi

2016-01-19

Gamabufotalin (CS-6), a main active compound isolated from Chinese medicine Chansu, has been shown to strongly inhibit cancer cell growth and inflammatory response. However, its effects on angiogenesis have not been known yet. Here, we sought to determine the biological effects of CS-6 on signaling mechanisms during angiogenesis. Our present results fully demonstrate that CS-6 could significantly inhibit VEGF triggered HUVECs proliferation, migration, invasion and tubulogenesis in vitro and blocked vascularization in Matrigel plugs impregnated in C57/BL6 mice as well as reduced vessel density in human lung tumor xenograft implanted in nude mice. Computer simulations revealed that CS-6 interacted with the ATP-binding sites of VEGFR-2 using molecular docking. Furthermore, western blot analysis indicated that CS-6 inhibited VEGF-induced phosphorylation of VEGFR-2 kinase and suppressed the activity of VEGFR-2-mediated signaling cascades. Therefore, our studies demonstrated that CS-6 inhibited angiogenesis by inhibiting the activation of VEGFR-2 signaling pathways and CS-6 could be a potential candidate in angiogenesis-related disease therapy.

Olive oil compounds inhibit vascular endothelial growth factor receptor-2 phosphorylation

International Nuclear Information System (INIS)

Lamy, Sylvie; Ouanouki, Amira; Béliveau, Richard; Desrosiers, Richard R.

2014-01-01

Vascular endothelial growth factor (VEGF) triggers crucial signaling processes that regulate tumor angiogenesis and, therefore, represents an attractive target for the development of novel anticancer therapeutics. Several epidemiological studies have confirmed that abundant consumption of foods from plant origin is associated with reduced risk of developing cancers. In the Mediterranean basin, the consumption of extra virgin olive oil is an important constituent of the diet. Compared to other vegetable oils, the presence of several phenolic antioxidants in olive oil is believed to prevent the occurrence of a variety of pathological processes, such as cancer. While the strong antioxidant potential of these molecules is well characterized, their antiangiogenic activities remain unknown. The aim of this study is to investigate whether tyrosol (Tyr), hydroxytyrosol (HT), taxifolin (Tax), oleuropein (OL) and oleic acid (OA), five compounds contained in extra virgin olive oil, can affect in vitro angiogenesis. We found that HT, Tax and OA were the most potent angiogenesis inhibitors through their inhibitory effect on specific autophosphorylation sites of VEGFR-2 (Tyr951, Tyr1059, Tyr1175 and Tyr1214) leading to the inhibition of endothelial cell (EC) signaling. Inhibition of VEGFR-2 by these olive oil compounds significantly reduced VEGF-induced EC proliferation and migration as well as their morphogenic differentiation into capillary-like tubular structures in Matrigel. Our study demonstrates that HT, Tax and OA are novel and potent inhibitors of the VEGFR-2 signaling pathway. These findings emphasize the chemopreventive properties of olive oil and highlight the importance of nutrition in cancer prevention. - Highlights: • We investigated five compounds contained in extra virgin olive oil on angiogenesis. • Hydroxytyrosol, taxifolin and oleic acid are the best angiogenesis inhibitors. • Olive oil compounds affect endothelial cell functions essential for

Olive oil compounds inhibit vascular endothelial growth factor receptor-2 phosphorylation

Energy Technology Data Exchange (ETDEWEB)

Lamy, Sylvie, E-mail: lamy.sylvie@uqam.ca; Ouanouki, Amira; Béliveau, Richard; Desrosiers, Richard R.

2014-03-10

Vascular endothelial growth factor (VEGF) triggers crucial signaling processes that regulate tumor angiogenesis and, therefore, represents an attractive target for the development of novel anticancer therapeutics. Several epidemiological studies have confirmed that abundant consumption of foods from plant origin is associated with reduced risk of developing cancers. In the Mediterranean basin, the consumption of extra virgin olive oil is an important constituent of the diet. Compared to other vegetable oils, the presence of several phenolic antioxidants in olive oil is believed to prevent the occurrence of a variety of pathological processes, such as cancer. While the strong antioxidant potential of these molecules is well characterized, their antiangiogenic activities remain unknown. The aim of this study is to investigate whether tyrosol (Tyr), hydroxytyrosol (HT), taxifolin (Tax), oleuropein (OL) and oleic acid (OA), five compounds contained in extra virgin olive oil, can affect in vitro angiogenesis. We found that HT, Tax and OA were the most potent angiogenesis inhibitors through their inhibitory effect on specific autophosphorylation sites of VEGFR-2 (Tyr951, Tyr1059, Tyr1175 and Tyr1214) leading to the inhibition of endothelial cell (EC) signaling. Inhibition of VEGFR-2 by these olive oil compounds significantly reduced VEGF-induced EC proliferation and migration as well as their morphogenic differentiation into capillary-like tubular structures in Matrigel. Our study demonstrates that HT, Tax and OA are novel and potent inhibitors of the VEGFR-2 signaling pathway. These findings emphasize the chemopreventive properties of olive oil and highlight the importance of nutrition in cancer prevention. - Highlights: • We investigated five compounds contained in extra virgin olive oil on angiogenesis. • Hydroxytyrosol, taxifolin and oleic acid are the best angiogenesis inhibitors. • Olive oil compounds affect endothelial cell functions essential for

Allosteric Inhibition of Factor XIIIa. Non-Saccharide Glycosaminoglycan Mimetics, but Not Glycosaminoglycans, Exhibit Promising Inhibition Profile.

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Rami A Al-Horani

Full Text Available Factor XIIIa (FXIIIa is a transglutaminase that catalyzes the last step in the coagulation process. Orthostery is the only approach that has been exploited to design FXIIIa inhibitors. Yet, allosteric inhibition of FXIIIa is a paradigm that may offer a key advantage of controlled inhibition over orthosteric inhibition. Such an approach is likely to lead to novel FXIIIa inhibitors that do not carry bleeding risks. We reasoned that targeting a collection of basic amino acid residues distant from FXIIIa's active site by using sulfated glycosaminoglycans (GAGs or non-saccharide GAG mimetics (NSGMs would lead to the discovery of the first allosteric FXIIIa inhibitors. We tested a library of 22 variably sulfated GAGs and NSGMs against human FXIIIa to discover promising hits. Interestingly, although some GAGs bound to FXIIIa better than NSGMs, no GAG displayed any inhibition. An undecasulfated quercetin analog was found to inhibit FXIIIa with reasonable potency (efficacy of 98%. Michaelis-Menten kinetic studies revealed an allosteric mechanism of inhibition. Fluorescence studies confirmed close correspondence between binding affinity and inhibition potency, as expected for an allosteric process. The inhibitor was reversible and at least 9-fold- and 26-fold selective over two GAG-binding proteins factor Xa (efficacy of 71% and thrombin, respectively, and at least 27-fold selective over a cysteine protease papain. The inhibitor also inhibited the FXIIIa-mediated polymerization of fibrin in vitro. Overall, our work presents the proof-of-principle that FXIIIa can be allosterically modulated by sulfated non-saccharide agents much smaller than GAGs, which should enable the design of selective and safe anticoagulants.

Ginger extract inhibits LPS induced macrophage activation and function

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Bruch David

2008-01-01

Full Text Available Abstract Background Macrophages play a dual role in host defence. They act as the first line of defence by mounting an inflammatory response to antigen exposure and also act as antigen presenting cells and initiate the adaptive immune response. They are also the primary infiltrating cells at the site of inflammation. Inhibition of macrophage activation is one of the possible approaches towards modulating inflammation. Both conventional and alternative approaches are being studied in this regard. Ginger, an herbal product with broad anti inflammatory actions, is used as an alternative medicine in a number of inflammatory conditions like rheumatic disorders. In the present study we examined the effect of ginger extract on macrophage activation in the presence of LPS stimulation. Methods Murine peritoneal macrophages were stimulated by LPS in presence or absence of ginger extract and production of proinflammatory cytokines and chemokines were observed. We also studied the effect of ginger extract on the LPS induced expression of MHC II, B7.1, B7.2 and CD40 molecules. We also studied the antigen presenting function of ginger extract treated macrophages by primary mixed lymphocyte reaction. Results We observed that ginger extract inhibited IL-12, TNF-α, IL-1β (pro inflammatory cytokines and RANTES, MCP-1 (pro inflammatory chemokines production in LPS stimulated macrophages. Ginger extract also down regulated the expression of B7.1, B7.2 and MHC class II molecules. In addition ginger extract negatively affected the antigen presenting function of macrophages and we observed a significant reduction in T cell proliferation in response to allostimulation, when ginger extract treated macrophages were used as APCs. A significant decrease in IFN-γ and IL-2 production by T cells in response to allostimulation was also observed. Conclusion In conclusion ginger extract inhibits macrophage activation and APC function and indirectly inhibits T cell activation.

Differential 3-bromopyruvate inhibition of cytosolic and mitochondrial human serine hydroxymethyltransferase isoforms, key enzymes in cancer metabolic reprogramming.

Science.gov (United States)

Paiardini, Alessandro; Tramonti, Angela; Schirch, Doug; Guiducci, Giulia; di Salvo, Martino Luigi; Fiascarelli, Alessio; Giorgi, Alessandra; Maras, Bruno; Cutruzzolà, Francesca; Contestabile, Roberto

2016-11-01

The cytosolic and mitochondrial isoforms of serine hydroxymethyltransferase (SHMT1 and SHMT2, respectively) are well-recognized targets of cancer research, since their activity is critical for purine and pyrimidine biosynthesis and because of their prominent role in the metabolic reprogramming of cancer cells. Here we show that 3-bromopyruvate (3BP), a potent novel anti-tumour agent believed to function primarily by blocking energy metabolism, differentially inactivates human SHMT1 and SHMT2. SHMT1 is completely inhibited by 3BP, whereas SHMT2 retains a significant fraction of activity. Site directed mutagenesis experiments on SHMT1 demonstrate that selective inhibition relies on the presence of a cysteine residue at the active site of SHMT1 (Cys204) that is absent in SHMT2. Our results show that 3BP binds to SHMT1 active site, forming an enzyme-3BP complex, before reacting with Cys204. The physiological substrate l-serine is still able to bind at the active site of the inhibited enzyme, although catalysis does not occur. Modelling studies suggest that alkylation of Cys204 prevents a productive binding of l-serine, hampering interaction between substrate and Arg402. Conversely, the partial inactivation of SHMT2 takes place without the formation of a 3BP-enzyme complex. The introduction of a cysteine residue in the active site of SHMT2 by site directed mutagenesis (A206C mutation), at a location corresponding to that of Cys204 in SHMT1, yields an enzyme that forms a 3BP-enzyme complex and is completely inactivated. This work sets the basis for the development of selective SHMT1 inhibitors that target Cys204, starting from the structure and reactivity of 3BP. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthetic, structural mimetics of the β-hairpin flap of HIV-1 protease inhibit enzyme function.

Science.gov (United States)

Chauhan, Jay; Chen, Shen-En; Fenstermacher, Katherine J; Naser-Tavakolian, Aurash; Reingewertz, Tali; Salmo, Rosene; Lee, Christian; Williams, Emori; Raje, Mithun; Sundberg, Eric; DeStefano, Jeffrey J; Freire, Ernesto; Fletcher, Steven

2015-11-01

Small-molecule mimetics of the β-hairpin flap of HIV-1 protease (HIV-1 PR) were designed based on a 1,4-benzodiazepine scaffold as a strategy to interfere with the flap-flap protein-protein interaction, which functions as a gated mechanism to control access to the active site. Michaelis-Menten kinetics suggested our small-molecules are competitive inhibitors, which indicates the mode of inhibition is through binding the active site or sterically blocking access to the active site and preventing flap closure, as designed. More generally, a new bioactive scaffold for HIV-1PR inhibition has been discovered, with the most potent compound inhibiting the protease with a modest K(i) of 11 μM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Harman inhibits the removal of pyrimidine dimers from the DNA of human cells

International Nuclear Information System (INIS)

Castellani, A.; Setlow, R.B.

1981-01-01

Normal human fibroblasts were UV-irradiated and incubated for 6 hr with harman. The losses of sites, in the extracted DNA, sensitive to a UV specific endonuclease were determined as precision measures of the excision of UV-induced pyrimidine dimers. Harman inhibited excision, rising from approx. 30% inhibition at 200 μM to 75% inhibition at 500 μM

Inactivation of Candida albicans by Corona Discharge: The Increase of Inhibition Zones Area After Far Subsequent Exposition

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Vladyslava Fantova

2013-01-01

Full Text Available The cold atmospheric pressure plasma generated by the negative corona discharge has inhibition effect on the microorganism growth. This effect is well-known and it can be demonstrated on the surface of cultivation agar plates by the formation of inhibition zones. We exposed the cultures of Candida albicans to the negative corona discharge plasma in a special arrangement in this study: The equal doses of plasma were applied subsequently twice or four times on the same culture on one Petri dish, while the distance between exposed points was variable. Only small differences were observed in decontaminated zone areas for twice exposed agar at the shortest distance between exposed points (1.5 cm. In case of the four times exposed agars, we observed significant differences in inhibition zone areas, dependent not only on the exposition site distances, but also on the exposition order. The largest inhibition zone size was observed for the first exposition decreasing to the fourth one. To check relevancy of these dependencies, we presume to conduct further set of experiments with lower yeast concentration. In conclusion, significant difference in partial inhibition zone sizes appeared only when four expositions on one Petri dish were carried out, whereas no significant difference was observed for two subsequent expositions. The explanation of this effect may be the subject of subsequent remote exposition(s, when minute amounts of scattered active particles act on the previously exposed areas; the influence of diffused ozone may also take place.

The selenazal drug ebselen potently inhibits indoleamine 2,3-dioxygenase by targeting enzyme cysteine residues.

Science.gov (United States)

Terentis, Andrew C; Freewan, Mohammed; Sempértegui Plaza, Tito S; Raftery, Mark J; Stocker, Roland; Thomas, Shane R

2010-01-26

The heme enzyme indoleamine 2,3-dioxygenase (IDO) plays an important immune regulatory role by catalyzing the oxidative degradation of l-tryptophan. Here we show that the selenezal drug ebselen is a potent IDO inhibitor. Exposure of human macrophages to ebselen inhibited IDO activity in a manner independent of changes in protein expression. Ebselen inhibited the activity of recombinant human IDO (rIDO) with an apparent inhibition constant of 94 +/- 17 nM. Optical and resonance Raman spectroscopy showed that ebselen altered the active site heme of rIDO by inducing a transition of the ferric heme iron from the predominantly high- to low-spin form and by lowering the vibrational frequency of the Fe-CO stretch of the CO complex, indicating an opening of the distal heme pocket. Substrate binding studies showed that ebselen enhanced nonproductive l-tryptophan binding, while circular dichroism indicated that the drug reduced the helical content and protein stability of rIDO. Thiol labeling and mass spectrometry revealed that ebselen reacted with multiple cysteine residues of IDO. Removal of cysteine-bound ebselen with dithiothreitol reversed the effects of the drug on the heme environment and significantly restored enzyme activity. These findings indicate that ebselen inhibits IDO activity by reacting with the enzyme's cysteine residues that result in changes to protein conformation and active site heme, leading to an increase in the level of nonproductive substrate binding. This study highlights that modification of cysteine residues is a novel and effective means of inhibiting IDO activity. It also suggests that IDO is under redox control and that the enzyme represents a previously unrecognized in vivo target of ebselen.

Alzheimer's Disease Brain-Derived Amyloid-{beta}-Mediated Inhibition of LTP In Vivo Is Prevented by Immunotargeting Cellular Prion Protein.

LENUS (Irish Health Repository)

Barry, Andrew E

2011-05-18

Synthetic amyloid-β protein (Aβ) oligomers bind with high affinity to cellular prion protein (PrP(C)), but the role of this interaction in mediating the disruption of synaptic plasticity by such soluble Aβ in vitro is controversial. Here we report that intracerebroventricular injection of Aβ-containing aqueous extracts of Alzheimer\\'s disease (AD) brain robustly inhibits long-term potentiation (LTP) without significantly affecting baseline excitatory synaptic transmission in the rat hippocampus in vivo. Moreover, the disruption of LTP was abrogated by immunodepletion of Aβ. Importantly, intracerebroventricular administration of antigen-binding antibody fragment D13, directed to a putative Aβ-binding site on PrP(C), prevented the inhibition of LTP by AD brain-derived Aβ. In contrast, R1, a Fab directed to the C terminus of PrP(C), a region not implicated in binding of Aβ, did not significantly affect the Aβ-mediated inhibition of LTP. These data support the pathophysiological significance of SDS-stable Aβ dimer and the role of PrP(C) in mediating synaptic plasticity disruption by soluble Aβ.

The stress granule component TIA-1 binds tick-borne encephalitis virus RNA and is recruited to perinuclear sites of viral replication to inhibit viral translation.

Science.gov (United States)

Albornoz, Amelina; Carletti, Tea; Corazza, Gianmarco; Marcello, Alessandro

2014-06-01

Flaviviruses are a major cause of disease in humans and animals worldwide. Tick-borne encephalitis virus (TBEV) is the most important arthropod-borne flavivirus endemic in Europe and is the etiological agent of tick-borne encephalitis, a potentially fatal infection of the central nervous system. However, the contributions of host proteins during TBEV infection are poorly understood. In this work, we investigate the cellular protein TIA-1 and its cognate factor TIAR, which are stress-induced RNA-binding proteins involved in the repression of initiation of translation of cellular mRNAs and in the formation of stress granules. We show that TIA-1 and TIAR interact with viral RNA in TBEV-infected cells. During TBEV infection, cytoplasmic TIA-1 and TIAR are recruited at sites of viral replication with concomitant depletion from stress granules. This effect is specific, since G3BP1, another component of these cytoplasmic structures, remains localized to stress granules. Moreover, heat shock induction of stress granules containing TIA-1, but not G3BP1, is inhibited in TBEV-infected cells. Infection of cells depleted of TIA-1 or TIAR by small interfering RNA (siRNA) or TIA-1(-/-) mouse fibroblasts, leads to a significant increase in TBEV extracellular infectivity. Interestingly, TIAR(-/-) fibroblasts show the opposite effect on TBEV infection, and this phenotype appears to be related to an excess of TIA-1 in these cells. Taking advantage of a TBE-luciferase replicon system, we also observed increased luciferase activity in TIA-1(-/-) mouse fibroblasts at early time points, consistent with TIA-1-mediated inhibition at the level of the first round of viral translation. These results indicate that, in response to TBEV infection, TIA-1 is recruited to sites of virus replication to bind TBEV RNA and modulate viral translation independently of stress granule (SG) formation. This study (i) extends previous work that showed TIA-1/TIAR recruitment at sites of flavivirus replication

Inhibition of a Putative Dihydropyrimidinase from Pseudomonas aeruginosa PAO1 by Flavonoids and Substrates of Cyclic Amidohydrolases.

Directory of Open Access Journals (Sweden)

Cheng-Yang Huang

Full Text Available Dihydropyrimidinase is a member of the cyclic amidohydrolase family, which also includes allantoinase, dihydroorotase, hydantoinase, and imidase. These metalloenzymes possess very similar active sites and may use a similar mechanism for catalysis. However, whether the substrates and inhibitors of other cyclic amidohydrolases can inhibit dihydropyrimidinase remains unclear. This study investigated the inhibition of dihydropyrimidinase by flavonoids and substrates of other cyclic amidohydrolases. Allantoin, dihydroorotate, 5-hydantoin acetic acid, acetohydroxamate, orotic acid, and 3-amino-1,2,4-triazole could slightly inhibit dihydropyrimidinase, and the IC50 values of these compounds were within the millimolar range. The inhibition of dihydropyrimidinase by flavonoids, such as myricetin, quercetin, kaempferol, galangin, dihydromyricetin, and myricitrin, was also investigated. Some of these compounds are known as inhibitors of allantoinase and dihydroorotase. Although the inhibitory effects of these flavonoids on dihydropyrimidinase were substrate-dependent, dihydromyricetin significantly inhibited dihydropyrimidinase with IC50 values of 48 and 40 μM for the substrates dihydrouracil and 5-propyl-hydantoin, respectively. The results from the Lineweaver-Burk plot indicated that dihydromyricetin was a competitive inhibitor. Results from fluorescence quenching analysis indicated that dihydromyricetin could form a stable complex with dihydropyrimidinase with the K(d value of 22.6 μM. A structural study using PatchDock showed that dihydromyricetin was docked in the active site pocket of dihydropyrimidinase, which was consistent with the findings from kinetic and fluorescence studies. This study was the first to demonstrate that naturally occurring product dihydromyricetin inhibited dihydropyrimidinase, even more than the substrate analogs (>3 orders of magnitude. These flavonols, particularly myricetin, may serve as drug leads and dirty drugs (for

Reactor design for minimizing product inhibition during enzymatic lignocellulose hydrolysis II. Quantification of inhibition and suitability of membrane reactors

DEFF Research Database (Denmark)

Andric, Pavle; Meyer, Anne S.; Jensen, Peter Arendt

2010-01-01

conversion are required for alleviation of glucose product inhibition. Supported by numerous calculations this review assesses the quantitative aspects of glucose product inhibition on enzyme-catalyzed cellulose degradation rates. The significance of glucose product inhibition on dimensioning of different......Product inhibition of cellulolytic enzymes affects the efficiency of the biocatalytic conversion of lignocellulosic biomass to ethanol and other valuable products. New strategies that focus on reactor designs encompassing product removal, notably glucose removal, during enzymatic cellulose...... reactor features, including system set-up, dilution rate, glucose output profile, and the problem of cellobiose are examined to illustrate the quantitative significance of the glucose product inhibition and the total glucose concentration on the cellulolytic conversion rate. Comprehensive overviews...

Audit Report The Procurement of Safety Class/Safety-Significant Items at the Savannah River Site

International Nuclear Information System (INIS)

2009-01-01

The Department of Energy operates several nuclear facilities at its Savannah River Site, and several additional facilities are under construction. This includes the National Nuclear Security Administration's Tritium Extraction Facility (TEF) which is designated to help maintain the reliability of the U.S. nuclear stockpile. The Mixed Oxide Fuel Fabrication Facility (MOX Facility) is being constructed to manufacture commercial nuclear reactor fuel assemblies from weapon-grade plutonium oxide and depleted uranium. The Interim Salt Processing (ISP) project, managed by the Office of Environmental Management, will treat radioactive waste. The Department has committed to procuring products and services for nuclear-related activities that meet or exceed recognized quality assurance standards. Such standards help to ensure the safety and performance of these facilities. To that end, it issued Departmental Order 414.1C, Quality Assurance (QA Order). The QA Order requires the application of Quality Assurance Requirements for Nuclear Facility Applications (NQA-1) for nuclear-related activities. The NQA-1 standard provides requirements and guidelines for the establishment and execution of quality assurance programs during the siting, design, construction, operation, and decommissioning of nuclear facilities. These requirements, promulgated by the American Society of Mechanical Engineers, must be applied to 'safety-class' and 'safety-significant' structures, systems and components (SSCs). Safety-class SSCs are defined as those necessary to prevent exposure off site and to protect the public. Safety-significant SSCs are those whose failure could irreversibly impact worker safety such as a fatality, serious injury, or significant radiological or chemical exposure. Due to the importance of protecting the public, workers, and environment, we initiated an audit to determine whether the Department of Energy procured safety-class and safety-significant SSCs that met NQA-1 standards at

Arctigenin Inhibits Liver Cancer Tumorigenesis by Inhibiting Gankyrin Expression via C/EBPα and PPARα

Science.gov (United States)

Sun, Ying; Tan, Yu-jun; Lu, Zhan-zhao; Li, Bing-bing; Sun, Cheng-hong; Li, Tao; Zhao, Li-li; Liu, Zhong; Zhang, Gui-min; Yao, Jing-chun; Li, Jie

2018-01-01

Burdock (Arctium lappa) is a popular vegetable in China and Japan that is consumed for its general health benefits. The principal active component of burdock is arctigenin, which shows a range of bioactivities in vivo and in vitro. Here, we investigated the potential anti-tumor effects of arctigenin using two human hepatocellular carcinoma (HCC) cell lines, HepG2 and Hep3B, and sought to elucidate its potential mechanisms of action. Our results showed that arctigenin treatment inhibited cell growth in both HepG2 and Hep3B cell lines (IC50 of 4.74 nM for HepG2 cells, and of 59.27 nM for Hep3B cells). In addition, migration, invasion, and colony formation by HepG2 cells were significantly inhibited by arctigenin. By contrast, treatment of Hep3B cells with arctigenin did not alter these parameters. Arctigenin also significantly reduced the levels of gankyrin mRNA and protein in HepG2 cells, but not in Hep3B cells. A luciferase assay indicated that arctigenin targeted the -450 to -400 region of the gankyrin promoter. This region is also the potential binding site for both C/EBPα and PPARα, as predicted and confirmed by an online software analysis and ChIP assay. Additionally, a co-immunoprecipitation (Co-IP) assay showed that binding between C/EBPα and PPARα was increased in the presence of arctigenin. However, arctigenin did not increase the expression of C/EBPα or PPARα protein. A binding screening assay and liquid chromatography–mass spectrometry (LC–MS) were performed to identify the mechanisms by which arctigenin regulates gankyrin expression. The results suggested that arctigenin could directly increase C/EBPα binding to the gankyrin promoter (-432 to -422 region), but did not affect PPARα binding. Expression of gankyrin, C/EBPα, and PPARα were analyzed in tumor tissues of patients using real-time PCR. Both C/EBPα and PPARα showed negative correlations with gankyrin. In tumor-bearing mice, arctigenin had a significant inhibitory effect on HCC

Arctigenin Inhibits Liver Cancer Tumorigenesis by Inhibiting Gankyrin Expression via C/EBPα and PPARα

Directory of Open Access Journals (Sweden)

Ying Sun

2018-03-01

Full Text Available Burdock (Arctium lappa is a popular vegetable in China and Japan that is consumed for its general health benefits. The principal active component of burdock is arctigenin, which shows a range of bioactivities in vivo and in vitro. Here, we investigated the potential anti-tumor effects of arctigenin using two human hepatocellular carcinoma (HCC cell lines, HepG2 and Hep3B, and sought to elucidate its potential mechanisms of action. Our results showed that arctigenin treatment inhibited cell growth in both HepG2 and Hep3B cell lines (IC50 of 4.74 nM for HepG2 cells, and of 59.27 nM for Hep3B cells. In addition, migration, invasion, and colony formation by HepG2 cells were significantly inhibited by arctigenin. By contrast, treatment of Hep3B cells with arctigenin did not alter these parameters. Arctigenin also significantly reduced the levels of gankyrin mRNA and protein in HepG2 cells, but not in Hep3B cells. A luciferase assay indicated that arctigenin targeted the -450 to -400 region of the gankyrin promoter. This region is also the potential binding site for both C/EBPα and PPARα, as predicted and confirmed by an online software analysis and ChIP assay. Additionally, a co-immunoprecipitation (Co-IP assay showed that binding between C/EBPα and PPARα was increased in the presence of arctigenin. However, arctigenin did not increase the expression of C/EBPα or PPARα protein. A binding screening assay and liquid chromatography–mass spectrometry (LC–MS were performed to identify the mechanisms by which arctigenin regulates gankyrin expression. The results suggested that arctigenin could directly increase C/EBPα binding to the gankyrin promoter (-432 to -422 region, but did not affect PPARα binding. Expression of gankyrin, C/EBPα, and PPARα were analyzed in tumor tissues of patients using real-time PCR. Both C/EBPα and PPARα showed negative correlations with gankyrin. In tumor-bearing mice, arctigenin had a significant inhibitory

Arctigenin Inhibits Liver Cancer Tumorigenesis by Inhibiting Gankyrin Expression via C/EBPα and PPARα.

Science.gov (United States)

Sun, Ying; Tan, Yu-Jun; Lu, Zhan-Zhao; Li, Bing-Bing; Sun, Cheng-Hong; Li, Tao; Zhao, Li-Li; Liu, Zhong; Zhang, Gui-Min; Yao, Jing-Chun; Li, Jie

2018-01-01

Burdock ( Arctium lappa ) is a popular vegetable in China and Japan that is consumed for its general health benefits. The principal active component of burdock is arctigenin, which shows a range of bioactivities in vivo and in vitro . Here, we investigated the potential anti-tumor effects of arctigenin using two human hepatocellular carcinoma (HCC) cell lines, HepG2 and Hep3B, and sought to elucidate its potential mechanisms of action. Our results showed that arctigenin treatment inhibited cell growth in both HepG2 and Hep3B cell lines (IC 50 of 4.74 nM for HepG2 cells, and of 59.27 nM for Hep3B cells). In addition, migration, invasion, and colony formation by HepG2 cells were significantly inhibited by arctigenin. By contrast, treatment of Hep3B cells with arctigenin did not alter these parameters. Arctigenin also significantly reduced the levels of gankyrin mRNA and protein in HepG2 cells, but not in Hep3B cells. A luciferase assay indicated that arctigenin targeted the -450 to -400 region of the gankyrin promoter. This region is also the potential binding site for both C/EBPα and PPARα, as predicted and confirmed by an online software analysis and ChIP assay. Additionally, a co-immunoprecipitation (Co-IP) assay showed that binding between C/EBPα and PPARα was increased in the presence of arctigenin. However, arctigenin did not increase the expression of C/EBPα or PPARα protein. A binding screening assay and liquid chromatography-mass spectrometry (LC-MS) were performed to identify the mechanisms by which arctigenin regulates gankyrin expression. The results suggested that arctigenin could directly increase C/EBPα binding to the gankyrin promoter (-432 to -422 region), but did not affect PPARα binding. Expression of gankyrin, C/EBPα , and PPARα were analyzed in tumor tissues of patients using real-time PCR. Both C/EBPα and PPARα showed negative correlations with gankyrin. In tumor-bearing mice, arctigenin had a significant inhibitory effect on HCC

Multi-site TBT binding skews the inhibition of oligomycin on the mitochondrial Mg-ATPase in Mytilus galloprovincialis.

Science.gov (United States)

Nesci, Salvatore; Ventrella, Vittoria; Trombetti, Fabiana; Pirini, Maurizio; Pagliarani, Alessandra

2011-07-01

Tributyltin (TBT), a persistent lipophilic contaminant found especially in the aquatic environment, is known to be toxic to mitochondria with the F(1)F(0)-ATPase as main target. Recently our research group pointed out that in mussel digestive gland mitochondria TBT, apart from decreasing the catalytic efficiency of Mg-ATPase activity, at concentrations ≥1.0 μM in the ATPase reaction medium lessens the enzyme inhibition promoted by the specific inhibitor oligomycin. The present work aims at casting light on the mechanisms involved in the TBT-driven enzyme desensitization to inhibitors, a poorly explored field. The mitochondrial Mg-ATPase desensitization is shown to be confined to inhibitors of transmembrane domain F(0), namely oligomycin and N,N'-dicyclohexylcarbodiimide (DCCD). Accordingly, quercetin, which binds to catalytic portion F(1), maintains its inhibitory efficiency in the presence of TBT. Among the possible mechanisms involved in the Mg-ATPase desensitization to oligomycin by ≥1.0 μM TBT concentrations, a structural detachment of the two F(1) and F(0) domains does not occur according to experimental data. On the other hand TBT covalently binds to thiol groups on the enzyme structure, which are apparently only available at TBT concentrations approaching 20 μM. TBT is able to interact with multiple sites on the enzyme structure by bonds of different nature. While electrostatic interactions with F(0) proton channel are likely to be responsible for the ATPase activity inhibition, possible changes in the redox state of thiol groups on the protein structure due to TBT binding may promote structural changes in the enzyme structure leading to the observed F(1)F(0)-ATPase oligomycin sensitivity loss. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Inhibition of [3H]nitrendipine binding by phospholipase A2

International Nuclear Information System (INIS)

Goldman, M.E.; Pisano, J.J.

1985-01-01

Phospholipase A 2 from several sources inhibited [ 3 H]nitrendipine binding to membranes from brain, heart and ileal longitudinal muscle. The enzymes from bee venom and Russell's viper venom were most potent, having IC 50 values of approximately 5 and 14 ng/ml, respectively, in all three membrane preparations. Inhibition of binding by bee venom phospholipase A 2 was time- and dose-dependent. Mastoparan, a known facilitator of phospholipase A 2 enzymatic activity, shifted the bee venom phospholipase A 2 dose-response curve to the left. Pretreatment of brain membranes with bee venom phospholipase A 2 (10 ng/ml) for 15 min caused a 2-fold increase in the K/sub d/ without changing the B/sub max/ compared with untreated membranes. Extension of the preincubation period to 30 min caused no further increase in the K/sub d/ but significantly decreased the B/sub max/ to 71% the value for untreated membranes. [ 3 H]Nitrendipine, preincubated with bee venom phospholipase A 2 , was recovered and found to be fully active, indicating that the phospholipase A 2 did not modify the ligand. It is concluded that phospholipase A 2 acts on the membrane at or near the [ 3 H]nitrendipine binding site and that phospholipids play a key role in the interactions of 1,4 dihydropyridine calcium channel antagonists with the dihydropyridine binding site. 33 references, 3 figures, 1 table

Molecular pharmacology of antihistamines in inhibition of oxidative burst of professional phagocytes.

Science.gov (United States)

Nosáľ, Radomír; Jančinová, Viera; Drábiková, Katarína; Perečko, Tomáš

2015-04-01

Antihistamines of the H₁and H₃/H₄groups interfere with oxidative burst of human professional phagocytes in vitro. In the concentration of 10 μM, H₁antihistamines of the 1st and 2nd generation inhibited oxidative burst of human neutrophils in the rank order of potency: dithiaden > loratadine > brompheniramine > chlorpheniramine > pheniramine. Of the H₁antihistamines, the most effective was dithiaden in suppressing oxidative burst of whole human blood and dose-dependently the chemiluminescence of isolated neutrophils at extra- and intracellular level. Inhibition of free oxygen radical generation in isolated neutrophils by dithiaden resulted from the inhibition of protein kinase C activation. The potentiation of recombinant caspase-3 by dithiaden is supportive of the antiinflammatory effect of dithiaden and suggestive of increasing the apoptosis of professional phagocytes. Of the H₃/H₄antihistamines, the most effective was JNJ7777120 in decreasing chemiluminescence in whole blood and also at extra- and intracellular sites of isolated neutrophils. JNJ 10191584 and thioperamide were less effective and the latter significantly potentiated free oxygen radical generation intracellularly. The results demonstrated that, compared with the H₃/H₄antihistamines investigated, H₁antihistamines were much more potent in inhibiting free oxygen radical generation in human professional phagocytes. This finding should be taken into account therapeutically.

Autoradiographic localization of 3H-paroxetine-labeled serotonin uptake sites in rat brain

International Nuclear Information System (INIS)

De Souza, E.B.; Kuyatt, B.L.

1987-01-01

Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H-paroxetine; 3H-paroxetine binding in slide-mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H-paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H-paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of the thalamus, and the islands of Calleja. High concentrations of 3H-paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H-paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H-paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4-methylenedioxyamphetamine caused large decreases in 3H-paroxetine binding. The autoradiographic distribution of 3H-paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin

Environmental Assessment and Finding of No Significant Impact: Pond B Dam Repair Project at the Savannah River Site

Energy Technology Data Exchange (ETDEWEB)

N/A

1999-09-27

The Department of Energy (DOE) has prepared an environmental assessment (EA) (DOE/EA-1285) for the proposed repair of the Pond B dam at the Savannah River Site (SRS), located near Aiken, South Carolina. Based on the analyses in the EA, DOE has determined that the proposed action is not a major Federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act of 1969 (NEPA). Therefore, the preparation of an environmental impact statement (EIS) is not required, and DOE is issuing this Finding of No Significant Impact (FONSI) and Floodplain Statement of Findings.

Chloride sensing by WNK1 kinase involves inhibition of autophosphorylation

Science.gov (United States)

Piala, Alexander T.; Moon, Thomas M.; Akella, Radha; He, Haixia; Cobb, Melanie H.; Goldsmith, Elizabeth J.

2014-01-01

WNK1 [with no lysine (K)] is a serine-threonine kinase associated with a form of familial hypertension. WNK1 is at the top of a kinase cascade leading to phosphorylation of several cotransporters, in particular those transporting sodium, potassium, and chloride (NKCC), sodium and chloride (NCC), and potassium and chloride (KCC). The responsiveness of NKCC, NCC, and KCC to changes in extracellular chloride parallels their phosphorylation state, provoking the proposal that these transporters are controlled by a chloride-sensitive protein kinase. Here, we found that chloride stabilizes the inactive conformation of WNK1, preventing kinase autophosphorylation and activation. Crystallographic studies of inactive WNK1 in the presence of chloride revealed that chloride binds directly to the catalytic site, providing a basis for the unique position of the catalytic lysine. Mutagenesis of the chloride binding site rendered the kinase less sensitive to inhibition of autophosphorylation by chloride, validating the binding site. Thus, these data suggest that WNK1 functions as a chloride sensor through direct binding of a regulatory chloride ion to the active site, which inhibits autophosphorylation. PMID:24803536

Surface complexation modeling of uranyl adsorption on corrensite from the Waste Isolation Pilot Plant Site

Energy Technology Data Exchange (ETDEWEB)

Park, Sang-Won; Leckie, J.O. [Stanford Univ., CA (United States); Siegel, M.D. [Sandia National Labs., Albuquerque, NM (United States)

1995-09-01

Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption.

Surface complexation modeling of uranyl adsorption on corrensite from the Waste Isolation Pilot Plant Site

International Nuclear Information System (INIS)

Park, Sang-Won; Leckie, J.O.; Siegel, M.D.

1995-09-01

Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption

Inhibition of the primary motor cortex and the upgoing thumb sign

Directory of Open Access Journals (Sweden)

Antonia Nucera

2017-09-01

Full Text Available Background: The upgoing thumb sign has been frequently observed in patients with minor strokes and transient ischemic attacks as an indicator of brain involvement. We assessed the effect of primary motor cortex (M1 inhibition in the development of the upgoing thumb sign. Methods: Used repetitive Transcranial Magnetic Stimulation (rTMS, 1Hz frequency for 15min, 1s ISI, 900 pulses at 60% of resting motor threshold to inhibit the right or left primary motor cortex of 10 healthy individuals. Participants were examined before and after rTMS by a neurologist who was blind to the site of motor cortex inhibition. Results: 10 neurological intact participants (5 women/5 men were recruited for this study. 2 cases were excluded due to pre-existing possible thumb signs. After the inhibition of the primary motor cortex, in 6 subjects out of 8, we observed a thumb sign contralateral to the site of primary motor cortex inhibition. In one subject an ipsilateral thumbs sign was noted. In another case, we did not find an upgoing thumb sign. Conclusion: The upgoing thumb sign is a subtle neurological finding that may be related to the primary motor cortex or corticospinal pathways involvements. Keywords: Corticospinal tract, Upper motor neuron lesions, Primary motor cortex, Transcranial magnetic stimulation

Inhibition of the classical pathway of the complement system by saliva of Amblyomma cajennense (Acari: Ixodidae).

Science.gov (United States)

Franco, Paula F; Silva, Naylene C S; Fazito do Vale, Vladimir; Abreu, Jéssica F; Santos, Vânia C; Gontijo, Nelder F; Valenzuela, Jesus G; Pereira, Marcos H; Sant'Anna, Mauricio R V; Gomes, Alessandra P S; Araujo, Ricardo N

2016-05-01

Inhibition of the complement system during and after haematophagy is of utmost importance for tick success in feeding and tick development. The role of such inhibition is to minimise damage to the intestinal epithelium as well as avoiding inflammation and opsonisation of salivary molecules at the bite site. Despite its importance, the salivary anti-complement activity has been characterised only in species belonging to the Ixodes ricinus complex which saliva is able to inhibit the alternative and lectin pathways. Little is known about this activity in other species of the Ixodidae family. Thus, the aim of this study was to describe the inhibition of the classical pathway of the complement system by the saliva of Amblyomma cajennense at different stages of the haematophagy. The A. cajennense saliva and salivary gland extract (SGE) were able to inhibit the complement classical pathway through haemolytic assays with higher activity observed when saliva was used. The anti-complement activity is present in the salivary glands of starving females and also in females throughout the whole feeding process, with significant higher activity soon after tick detachment. The SGE activity from both females fed on mice or horses had no significant correlation (p > 0.05) with tick body weight. The pH found in the intestinal lumen of A. cajennense was 8.04 ± 0.08 and haemolytic assays performed at pH 8.0 showed activation of the classical pathway similarly to what occurs at pH 7.4. Consequently, inhibition could be necessary to protect the tick enterocytes. Indeed, the inhibition observed by SGE was higher in pH 8.0 in comparison to pH 7.4 reinforcing the role of saliva in protecting the intestinal cells. Further studies should be carried out in order to identify the inhibitor molecule and characterise its inhibition mechanism. Copyright © 2016 Elsevier Inc. All rights reserved.

Modulation of 5' splice site selection using tailed oligonucleotides carrying splicing signals

Directory of Open Access Journals (Sweden)

Elela Sherif

2006-01-01

Full Text Available Abstract Background We previously described the use of tailed oligonucleotides as a means of reprogramming alternative pre-mRNA splicing in vitro and in vivo. The tailed oligonucleotides that were used interfere with splicing because they contain a portion complementary to sequences immediately upstream of the target 5' splice site combined with a non-hybridizing 5' tail carrying binding sites for the hnRNP A1/A2 proteins. In the present study, we have tested the inhibitory activity of RNA oligonucleotides carrying different tail structures. Results We show that an oligonucleotide with a 5' tail containing the human β-globin branch site sequence inhibits the use of the 5' splice site of Bcl-xL, albeit less efficiently than a tail containing binding sites for the hnRNP A1/A2 proteins. A branch site-containing tail positioned at the 3' end of the oligonucleotide also elicited splicing inhibition but not as efficiently as a 5' tail. The interfering activity of a 3' tail was improved by adding a 5' splice site sequence next to the branch site sequence. A 3' tail carrying a Y-shaped branch structure promoted similar splicing interference. The inclusion of branch site or 5' splice site sequences in the Y-shaped 3' tail further improved splicing inhibition. Conclusion Our in vitro results indicate that a variety of tail architectures can be used to elicit splicing interference at low nanomolar concentrations, thereby broadening the scope and the potential impact of this antisense technology.

Ecosystem Model Performance at Wetlands: Results from the North American Carbon Program Site Synthesis

Science.gov (United States)

Sulman, B. N.; Desai, A. R.; Schroeder, N. M.; NACP Site Synthesis Participants

2011-12-01

Northern peatlands contain a significant fraction of the global carbon pool, and their responses to hydrological change are likely to be important factors in future carbon cycle-climate feedbacks. Global-scale carbon cycle modeling studies typically use general ecosystem models with coarse spatial resolution, often without peatland-specific processes. Here, seven ecosystem models were used to simulate CO2 fluxes at three field sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor, sphagnum-dominated bog, from 2002-2006. Flux residuals (simulated - observed) were positively correlated with measured water table for both gross ecosystem productivity (GEP) and ecosystem respiration (ER) at the two fen sites for all models, and were positively correlated with water table at the bog site for the majority of models. Modeled diurnal cycles at fen sites agreed well with eddy covariance measurements overall. Eddy covariance GEP and ER were higher during dry periods than during wet periods, while model results predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP had no significant dependence on water table, while models predicted higher GEP during wet periods. All models significantly over-estimated GEP at the bog site, and all but one over-estimated ER at the bog site. Carbon cycle models in peatland-rich regions could be improved by incorporating better models or measurements of hydrology and by inhibiting GEP and ER rates under saturated conditions. Bogs and fens likely require distinct treatments in ecosystem models due to differences in nutrients, peat properties, and plant communities.

KSHV inhibits stress granule formation by viral ORF57 blocking PKR activation.

Directory of Open Access Journals (Sweden)

Nishi R Sharma

2017-10-01

Full Text Available TIA-1 positive stress granules (SG represent the storage sites of stalled mRNAs and are often associated with the cellular antiviral response. In this report, we provide evidence that Kaposi's sarcoma-associated herpesvirus (KSHV overcomes the host antiviral response by inhibition of SG formation via a viral lytic protein ORF57. By immunofluorescence analysis, we found that B lymphocytes with KSHV lytic infection are refractory to SG induction. KSHV ORF57, an essential post-transcriptional regulator of viral gene expression and the production of new viral progeny, inhibits SG formation induced experimentally by arsenite and poly I:C, but not by heat stress. KSHV ORF37 (vSOX bearing intrinsic endoribonuclease activity also inhibits arsenite-induced SG formation, but KSHV RTA, vIRF-2, ORF45, ORF59 and LANA exert no such function. ORF57 binds both PKR-activating protein (PACT and protein kinase R (PKR through their RNA-binding motifs and prevents PACT-PKR interaction in the PKR pathway which inhibits KSHV production. Consistently, knocking down PKR expression significantly promotes KSHV virion production. ORF57 interacts with PKR to inhibit PKR binding dsRNA and its autophosphorylation, leading to inhibition of eIF2α phosphorylation and SG formation. Homologous protein HSV-1 ICP27, but not EBV EB2, resembles KSHV ORF57 in the ability to block the PKR/eIF2α/SG pathway. In addition, KSHV ORF57 inhibits poly I:C-induced TLR3 phosphorylation. Altogether, our data provide the first evidence that KSHV ORF57 plays a role in modulating PKR/eIF2α/SG axis and enhances virus production during virus lytic infection.

Structure and Inhibition of Microbiome β-Glucuronidases Essential to the Alleviation of Cancer Drug Toxicity

Energy Technology Data Exchange (ETDEWEB)

Wallace, Bret D.; Roberts, Adam B.; Pollet, Rebecca M.; Ingle, James D.; Biernat, Kristen A.; Pellock, Samuel J.; Venkatesh, Madhu Kumar; Guthrie, Leah; O’Neal, Sara K.; Robinson, Sara J.; Dollinger, Makani; Figueroa, Esteban; McShane, Sarah R.; Cohen, Rachel D.; Jin, Jian; Frye, Stephen V.; Zamboni, William C.; Pepe-Ranney, Charles; Mani, Sridhar; Kelly, Libusha; Redinbo, Matthew (Einstein); (UNC); (Cornell)

2015-09-01

The selective inhibition of bacterial β-glucuronidases was recently shown to alleviate drug-induced gastrointestinal toxicity in mice, including the damage caused by the widely used anticancer drug irinotecan. Here, we report crystal structures of representative β-glucuronidases from the Firmicutes Streptococcus agalactiae and Clostridium perfringens and the Proteobacterium Escherichia coli, and the characterization of a β-glucuronidase from the Bacteroidetes Bacteroides fragilis. While largely similar in structure, these enzymes exhibit marked differences in catalytic properties and propensities for inhibition, indicating that the microbiome maintains functional diversity in orthologous enzymes. Small changes in the structure of designed inhibitors can induce significant conformational changes in the β-glucuronidase active site. Finally, we establish that β-glucuronidase inhibition does not alter the serum pharmacokinetics of irinotecan or its metabolites in mice. Together, the data presented advance our in vitro and in vivo understanding of the microbial β-glucuronidases, a promising new set of targets for controlling drug-induced gastrointestinal toxicity.

The mechanism of OTUB1-mediated inhibition of ubiquitination

Energy Technology Data Exchange (ETDEWEB)

Wiener, Reuven; Zhang, Xiangbin; Wang, Tao; Wolberger, Cynthia (JHU)

2013-04-08

Histones are ubiquitinated in response to DNA double-strand breaks (DSB), promoting recruitment of repair proteins to chromatin. UBC13 (also known as UBE2N) is a ubiquitin-conjugating enzyme (E2) that heterodimerizes with UEV1A (also known as UBE2V1) and synthesizes K63-linked polyubiquitin (K63Ub) chains at DSB sites in concert with the ubiquitin ligase (E3), RNF168 (ref. 3). K63Ub synthesis is regulated in a non-canonical manner by the deubiquitinating enzyme, OTUB1 (OTU domain-containing ubiquitin aldehyde-binding protein 1), which binds preferentially to the UBC13-Ub thiolester. Residues amino-terminal to the OTU domain, which had been implicated in ubiquitin binding, are required for binding to UBC13-Ub and inhibition of K63Ub synthesis. Here we describe structural and biochemical studies elucidating how OTUB1 inhibits UBC13 and other E2 enzymes. We unexpectedly find that OTUB1 binding to UBC13-Ub is allosterically regulated by free ubiquitin, which binds to a second site in OTUB1 and increases its affinity for UBC13-Ub, while at the same time disrupting interactions with UEV1A in a manner that depends on the OTUB1 N terminus. Crystal structures of an OTUB1-UBC13 complex and of OTUB1 bound to ubiquitin aldehyde and a chemical UBC13-Ub conjugate show that binding of free ubiquitin to OTUB1 triggers conformational changes in the OTU domain and formation of a ubiquitin-binding helix in the N terminus, thus promoting binding of the conjugated donor ubiquitin in UBC13-Ub to OTUB1. The donor ubiquitin thus cannot interact with the E2 enzyme, which has been shown to be important for ubiquitin transfer. The N-terminal helix of OTUB1 is positioned to interfere with UEV1A binding to UBC13, as well as with attack on the thiolester by an acceptor ubiquitin, thereby inhibiting K63Ub synthesis. OTUB1 binding also occludes the RING E3 binding site on UBC13, thus providing a further component of inhibition. The general features of the inhibition mechanism explain how OTUB1

Comparison of Helicobacter pylori Urease Inhibition by Rhizoma Coptidis, Cortex Phellodendri and Berberine: Mechanisms of Interaction with the Sulfhydryl Group.

Science.gov (United States)

Li, Cailan; Xie, Jianhui; Chen, Xiaoying; Mo, Zhizhun; Wu, Wen; Liang, Yeer; Su, Zuqing; Li, Qian; Li, Yucui; Su, Ziren; Yang, Xiaobo

2016-03-01

Rhizoma Coptidis, Cortex Phellodendri, and berberine were reported to inhibit Helicobacter pylori. However, the underlying mechanism remained elusive. Urease plays a vital role in H. pylori colonization and virulence. In this work, aqueous extracts of Rhizoma Coptidis, Cortex Phellodendri of different origins, and purified berberine were investigated against H. pylori urease and jack bean urease to elucidate the inhibitory capacity, kinetics, and mechanism. Results showed that berberine was the major chemical component in Rhizoma Coptidis and Cortex Phellodendri, and the content of berberine in Rhizoma Coptidis was higher than in Cortex Phellodendri. The IC50 values of Rhizoma Coptidis were significantly lower than those Cortex Phellodendri and purified berberine, of which Coptis chinensis was shown to be the most active concentration- and time-dependent urease inhibitor. The Lineweaver-Burk plot analysis indicated that the inhibition pattern of C. chinensis against urease was noncompetitive for both H. pylori urease and jack bean urease. Thiol protectors (L-cysteine, glutathione, and dithiothreithol) significantly protected urease from the loss of enzymatic activity, while fluoride and boric acid showed weaker protection, indicating the active-site sulfhydryl group was possibly responsible for its inhibition. Furthermore, the urease inhibition proved to be reversible since C. chinensis-blocked urease could be reactivated by glutathione. The results suggested that the anti-urease activity of Rhizoma Coptidis was superior to that of Cortex Phellodendri and berberine, which was believed to be more likely to correlate to the content of total alkaloids rather than berberine monomer. The concentration- and time-dependent, reversible, and noncompetitive inhibition against urease by C. chinensis might be attributed to its interaction with the sulfhydryl group of the active site of urease. Georg Thieme Verlag KG Stuttgart · New York.

The curious case of benzbromarone: insight into super-inhibition of cytochrome P450.

Directory of Open Access Journals (Sweden)

Abhinav Parashar

Full Text Available Cytochrome P450 (CYP family of redox enzymes metabolize drugs and xenobiotics in liver microsomes. Isozyme CYP2C9 is reported to be inhibited by benzbromarone (BzBr and this phenomenon was hitherto explained by classical active-site binding. Theoretically, it was impossible to envisage the experimentally derived sub-nM Ki for an inhibitor, when supra-nM enzyme and 10X KM substrate concentrations were employed. We set out to find a more plausible explanation for this highly intriguing "super-inhibition" phenomenon. In silico docking of various BzBr analogs with known crystal structure of CYP2C9 did not provide any evidence in support of active-site based inhibition hypothesis. Experiments tested the effects of BzBr and nine analogs on CYPs in reconstituted systems of lab-purified proteins, complex baculosomes & crude microsomal preparations. In certain setups, BzBr and its analogs could even enhance reactions, which cannot be explained by an active site hypothesis. Generally, it was seen that Ki became smaller by orders of magnitude, upon increasing the dilution order of BzBr analogs. Also, it was seen that BzBr could also inhibit other CYP isozymes like CYP3A4, CYP2D6 and CYP2E1. Further, amphipathic derivatives of vitamins C & E (scavengers of diffusible reactive oxygen species or DROS effectively inhibited CYP2C9 reactions in different reaction setups. Therefore, the inhibition of CYP activity by BzBr analogs (which are also surface-active redox agents is attributed to catalytic scavenging of DROS at phospholipid interface. The current work expands the scope of interpretations of inhibitions in redox enzymes and ushers in a new cellular biochemistry paradigm that small amounts of DROS may be obligatorily required in routine redox metabolism for constructive catalytic roles.

Pilot-scale bioremediation of a petroleum hydrocarbon-contaminated clayey soil from a sub-Arctic site

Energy Technology Data Exchange (ETDEWEB)

Akbari, Ali; Ghoshal, Subhasis, E-mail: subhasis.ghoshal@mcgill.ca

2014-09-15

Highlights: • Aeration and moisture addition alone caused extensive hydrocarbon biodegradation. • 30-day slurry reactor remediation endpoints attained in 385 days in biopiles. • High nitrogen concentrations inhibited hydrocarbon degradation. • Inhibition of biodegradation linked to lack of shifts in soil microbial community. - Abstract: Bioremediation is a potentially cost-effective solution for petroleum contamination in cold region sites. This study investigates the extent of biodegradation of petroleum hydrocarbons (C16–C34) in a pilot-scale biopile experiment conducted at 15 °C for periods up to 385 days, with a clayey soil, from a crude oil-impacted site in northern Canada. Although several studies on bioremediation of petroleum hydrocarbon-contaminated soils from cold region sites have been reported for coarse-textured, sandy soils, there are limited studies of bioremediation of petroleum contamination in fine-textured, clayey soils. Our results indicate that aeration and moisture addition was sufficient for achieving 47% biodegradation and an endpoint of 530 mg/kg for non-volatile (C16–C34) petroleum hydrocarbons. Nutrient amendment with 95 mg-N/kg showed no significant effect on biodegradation compared to a control system without nutrient but similar moisture content. In contrast, in a biopile amended with 1340 mg-N/kg, no statistically significant biodegradation of non-volatile fraction was detected. Terminal Restriction Fragment Length Polymorphism (T-RFLP) analyses of alkB and 16S rRNA genes revealed that inhibition of hydrocarbon biodegradation was associated with a lack of change in microbial community composition. Overall, our data suggests that biopiles are feasible for attaining the bioremediation endpoint in clayey soils. Despite the significantly lower biodegradation rate of 0.009 day{sup −1} in biopile tank compared to 0.11 day{sup −1} in slurry bioreactors for C16–C34 hydrocarbons, the biodegradation extents for this fraction

Waste management practices to control biological transport of radioactivity at the Hanford Site

International Nuclear Information System (INIS)

Conklin, A.W.

1985-01-01

One of the goals of waste management in the Hanford Site 200 Areas is to prevent biological intrusion into, and transport from, waste storage and disposal sites. Practices established to achieve these goals include the elimination of deep-rooted vegetation on waste sites to prevent plant root intrusion into radioactivity, selective herbicide application to prevent regrowth of these plants, planting of shallow-rooted plants to successfully compete with deep-rooted plants for moisture, surface stabilization, and environmental surveillance. Past biological transport incidents have included transport by Russian thistle by way of physiological plant processes, bird access into exposed contamination, and animals burrowing into radioactive waste disposal sites. Rockwell Hanford Operations, through mitigative actions and continued surveillance, has made significant progress in eliminating, or better isolating source terms, thus preventing or inhibiting problems from recurring. Approximately 60% of source term acreage requiring stabilization or decontamination has been completed

Inhibition of DNA glycosylases via small molecule purine analogs.

Directory of Open Access Journals (Sweden)

Aaron C Jacobs

Full Text Available Following the formation of oxidatively-induced DNA damage, several DNA glycosylases are required to initiate repair of the base lesions that are formed. Recently, NEIL1 and other DNA glycosylases, including OGG1 and NTH1 were identified as potential targets in combination chemotherapeutic strategies. The potential therapeutic benefit for the inhibition of DNA glycosylases was validated by demonstrating synthetic lethality with drugs that are commonly used to limit DNA replication through dNTP pool depletion via inhibition of thymidylate synthetase and dihydrofolate reductase. Additionally, NEIL1-associated synthetic lethality has been achieved in combination with Fanconi anemia, group G. As a prelude to the development of strategies to exploit the potential benefits of DNA glycosylase inhibition, it was necessary to develop a reliable high-throughput screening protocol for this class of enzymes. Using NEIL1 as the proof-of-principle glycosylase, a fluorescence-based assay was developed that utilizes incision of site-specifically modified oligodeoxynucleotides to detect enzymatic activity. This assay was miniaturized to a 1536-well format and used to screen small molecule libraries for inhibitors of the combined glycosylase/AP lyase activities. Among the top hits of these screens were several purine analogs, whose postulated presence in the active site of NEIL1 was consistent with the paradigm of NEIL1 recognition and excision of damaged purines. Although a subset of these small molecules could inhibit other DNA glycosylases that excise oxidatively-induced DNA adducts, they could not inhibit a pyrimidine dimer-specific glycosylase.

The significance of natural ground-water recharge in site selection for mill tailings disposal

International Nuclear Information System (INIS)

Stephens, D.B.

1985-01-01

Milling operations throughout the world have created vast amounts of waste by-products, or tailings, which are often disposed on the land surface. The wastes may be disposed behind dams, on untreated ground, or on compacted clay or synthetic liners of impoundments and trenches. Often one of the principle concerns of environmental regulatory agencies is whether seepage from the waste pile could move through the vadose zone to the water table and possibly contaminate an aquifer. The seepage may be generated by the drainage of liquids initially deposited along with the tailings or by infiltrating meteoric water which leaches soluted from the tailings. The purpose of this article is to discuss some of the commonly held assumptions regarding storage of seepage wastes in the unsaturated zone. The significance of recent studies of water movement in dry climates which pertain to tailings site selection are presented

Inhibition of chrysin on xanthine oxidase activity and its inhibition mechanism.

Science.gov (United States)

Lin, Suyun; Zhang, Guowen; Liao, Yijing; Pan, Junhui

2015-11-01

Chrysin, a bioactive flavonoid, was investigated for its potential to inhibit the activity of xanthine oxidase (XO), a key enzyme catalyzing xanthine to uric acid and finally causing gout. The kinetic analysis showed that chrysin possessed a strong inhibition on XO ability in a reversible competitive manner with IC50 value of (1.26±0.04)×10(-6)molL(-1). The results of fluorescence titrations indicated that chrysin bound to XO with high affinity, and the interaction was predominately driven by hydrogen bonds and van der Waals forces. Analysis of circular dichroism demonstrated that chrysin induced the conformational change of XO with increases in α-helix and β-sheet and reductions in β-turn and random coil structures. Molecular simulation revealed that chrysin interacted with the amino acid residues Leu648, Phe649, Glu802, Leu873, Ser876, Glu879, Arg880, Phe1009, Thr1010, Val1011 and Phe1013 located within the active cavity of XO. The mechanism of chrysin on XO activity may be the insertion of chrysin into the active site occupying the catalytic center of XO to avoid the entrance of xanthine and causing conformational changes in XO. Furthermore, the interaction assays indicated that chrysin and its structural analog apigenin exhibited an additive effect on inhibition of XO. Copyright © 2015 Elsevier B.V. All rights reserved.

AAV-Mediated Gene Targeting Is Significantly Enhanced by Transient Inhibition of Nonhomologous End Joining or the Proteasome In Vivo

Science.gov (United States)

Paulk, Nicole K.; Loza, Laura Marquez; Finegold, Milton J.

2012-01-01

Abstract Recombinant adeno-associated virus (rAAV) vectors have clear potential for use in gene targeting but low correction efficiencies remain the primary drawback. One approach to enhancing efficiency is a block of undesired repair pathways like nonhomologous end joining (NHEJ) to promote the use of homologous recombination. The natural product vanillin acts as a potent inhibitor of NHEJ by inhibiting DNA-dependent protein kinase (DNA-PK). Using a homology containing rAAV vector, we previously demonstrated in vivo gene repair frequencies of up to 0.1% in a model of liver disease hereditary tyrosinemia type I. To increase targeting frequencies, we administered vanillin in combination with rAAV. Gene targeting frequencies increased up to 10-fold over AAV alone, approaching 1%. Fah−/−Ku70−/− double knockout mice also had increased gene repair frequencies, genetically confirming the beneficial effects of blocking NHEJ. A second strategy, transient proteasomal inhibition, also increased gene-targeting frequencies but was not additive to NHEJ inhibition. This study establishes the benefit of transient NHEJ inhibition with vanillin, or proteasome blockage with bortezomib, for increasing hepatic gene targeting with rAAV. Functional metabolic correction of a clinically relevant disease model was demonstrated and provided evidence for the feasibility of gene targeting as a therapeutic strategy. PMID:22486314

Inhibition of ethylene production by putrescine alleviates aluminium-induced root inhibition in wheat plants.

Science.gov (United States)

Yu, Yan; Jin, Chongwei; Sun, Chengliang; Wang, Jinghong; Ye, Yiquan; Zhou, Weiwei; Lu, Lingli; Lin, Xianyong

2016-01-08

Inhibition of root elongation is one of the most distinct symptoms of aluminium (Al) toxicity. Although putrescine (Put) has been identified as an important signaling molecule involved in Al tolerance, it is yet unknown how Put mitigates Al-induced root inhibition. Here, the possible mechanism was investigated by using two wheat genotypes differing in Al resistance: Al-tolerant Xi Aimai-1 and Al-sensitive Yangmai-5. Aluminium caused more root inhibition in Yangmai-5 and increased ethylene production at the root apices compared to Xi Aimai-1, whereas the effects were significantly reversed by ethylene biosynthesis inhibitors. The simultaneous exposure of wheat seedlings to Al and ethylene donor, ethephon, or ethylene biosynthesis precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), increased ethylene production and aggravated root inhibition, which was more pronounced in Xi Aimai-1. In contrast, Put treatment decreased ethylene production and alleviated Al-induced root inhibition in both genotypes, and the effects were more conspicuous in Yangmai-5. Furthermore, our results indicated that Al-induced ethylene production was mediated by ACC synthase (ACS) and ACC oxidase, and that Put decreased ethylene production by inhibiting ACS. Altogether, these findings indicate that ethylene is involved in Al-induced root inhibition and this process could be alleviated by Put through inhibiting ACS activity.

Inhibition Performance in Children with Math Disabilities

OpenAIRE

Winegar, Kathryn Lileth

2013-01-01

This study examined the inhibition deficit hypothesis in children with math disabilities (MD). Children with and without MD were compared on two inhibition tasks that included the random generation of numbers and letters. The results addressed three hypotheses. Weak support was found for the first hypothesis which stated difficulties related to inhibition are significantly related to math performance. I found partial support for this hypothesis in that inhibition was related to math problem s...

Inhibition of the ultrasonic microjet-pits on the carbon steel in the particles-water mixtures

Science.gov (United States)

Yan, Dayun; Wang, Jiadao; Liu, Fengbin

2015-07-01

In the incubation period of ultrasonic cavitation, due to the impact of microjets on the material surface, the needle-like microjet-pits are formed. Because the formation of microjet-pits relates with the evolution of cavitation erosion on engineering materials, corresponding study will promote the understanding on the mechanism of cavitation erosion. However, little study on the microjet-pits has been carried out, especially in the particles-water mixture. In this study, we firstly demonstrated the microjet-pits on the carbon steel would be significantly inhibited by Al particles in water. Such inhibition effect indicated that particular particles might not only provide growth sites for cavitation bubbles but also affect the collapse of cavitation bubbles near a solid surface. Our study deepened the understanding on the ultrasonic cavitation erosion in the particles-water mixture.

Public safety risk management at socio-economic and / or historic-cultural significant dam sites

Energy Technology Data Exchange (ETDEWEB)

Earle, Gordon D.; Ryan, Katherine; Pyykonen, Nicole K.; Pitts, Lucas [Otonabee Region Conservation Authority, Peterborough, (Canada)

2010-07-01

The Lang Dam and adjoining gristmill, located near Peterborough are integral parts of the Lang Pioneer Village museum. Activities occurring within close proximity to the dam have led to safety issues. The owner (ORCA) has developed and implemented public safety management plans (PSMPs) for each of its water control structures, including the Lang Dam. ORCA gave special attention to the social, economic, aesthetic, historic and cultural dimensions associated the implementation of public safety management plans. These factors play a significant role in how well public safety measures (PSMs) are received by stakeholder groups and the general public. This paper reported the challenges of developing and implementing a PSMP for the Lang Dam, with the focus on property site-specific PSMS while preserving socio-economic and historic-cultural character and values. It was demonstrated that the dam owners, regulatory authorities, control agencies and preservationists need to come together to develop a holistic public safety management process.

Caffeine inhibition of GLUT1 is dependent on the activation state of the transporter.

Science.gov (United States)

Gunnink, Leesha K; Busscher, Brianna M; Wodarek, Jeremy A; Rosette, Kylee A; Strohbehn, Lauren E; Looyenga, Brendan D; Louters, Larry L

2017-06-01

Caffeine has been shown to be a robust uncompetitive inhibitor of glucose uptake in erythrocytes. It preferentially binds to the nucleotide-binding site on GLUT1 in its tetrameric form and mimics the inhibitory action of ATP. Here we demonstrate that caffeine is also a dose-dependent, uncompetitive inhibitor of 2-deoxyglucose (2DG) uptake in L929 fibroblasts. The inhibitory effect on 2DG uptake in these cells was reversible with a rapid onset and was additive to the competitive inhibitory effects of glucose itself, confirming that caffeine does not interfere with glucose binding. We also report for the first time that caffeine inhibition was additive to inhibition by curcumin, suggesting distinct binding sites for curcumin and caffeine. In contrast, caffeine inhibition was not additive to that of cytochalasin B, consistent with previous data that reported that these two inhibitors have overlapping binding sites. More importantly, we show that the magnitude of maximal caffeine inhibition in L929 cells is much lower than in erythrocytes (35% compared to 90%). Two epithelial cell lines, HCLE and HK2, have both higher concentrations of GLUT1 and increased basal 2DG uptake (3-4 fold) compared to L929 cells, and subsequently display greater maximal inhibition by caffeine (66-70%). Interestingly, activation of 2DG uptake (3-fold) in L929 cells by glucose deprivation shifted the responsiveness of these cells to caffeine inhibition (35%-70%) without a change in total GLUT1 concentration. These data indicate that the inhibition of caffeine is dependent on the activity state of GLUT1, not merely on the concentration. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Inhibition of Helicobacter pylori and Its Associated Urease by Palmatine: Investigation on the Potential Mechanism.

Science.gov (United States)

Zhou, Jiang-Tao; Li, Cai-Lan; Tan, Li-Hua; Xu, Yi-Fei; Liu, Yu-Hong; Mo, Zhi-Zhun; Dou, Yao-Xing; Su, Rui; Su, Zi-Ren; Huang, Ping; Xie, Jian-Hui

2017-01-01

In this paper, we evaluated the anti-Helicobacter pylori activity and the possible inhibitory effect on its associated urease by Palmatine (Pal) from Coptis chinensis, and explored the potential underlying mechanism. Results indicated that Pal exerted inhibitory effect on four tested H. pylori strains (ATCC 43504, NCTC 26695, SS1 and ICDC 111001) by the agar dilution test with minimum inhibitory concentration (MIC) values ranging from 100 to 200 μg/mL under neutral environment (pH 7.4), and from 75 to 100 μg/mL under acidic conditions (pH 5.3), respectively. Pal was observed to significantly inhibit both H. pylori urease (HPU) and jack bean urease (JBU) in a dose-dependent manner, with IC50 values of 0.53 ± 0.01 mM and 0.03 ± 0.00 mM, respectively, as compared with acetohydroxamic acid, a well-known urease inhibitor (0.07 ± 0.01 mM for HPU and 0.02 ± 0.00 mM for JBU, respectively). Kinetic analyses showed that the type of urease inhibition by Pal was noncompetitive for both HPU and JBU. Higher effectiveness of thiol protectors against urease inhibition than the competitive Ni2+ binding inhibitors was observed, indicating the essential role of the active-site sulfhydryl group in the urease inhibition by Pal. DTT reactivation assay indicated that the inhibition on the two ureases was reversible, further supporting that sulfhydryl group should be obligatory for urease inhibition by Pal. Furthermore, molecular docking study indicated that Pal interacted with the important sulfhydryl groups and inhibited the active enzymatic conformation through N-H ∙ π interaction, but did not interact with the active site Ni2+. Taken together, Pal was an effective inhibitor of H. pylori and its urease targeting the sulfhydryl groups, representing a promising candidate as novel urease inhibitor. This investigation also gave additional scientific support to the use of C. chinensis to treat H. pylori-related gastrointestinal diseases in traditional Chinese medicine. Pal might be

Switch in Site of Inhibition: A Strategy for Structure-Based Discovery of Human Topoisomerase IIα Catalytic Inhibitors

Science.gov (United States)

2015-01-01

A study of structure-based modulation of known ligands of hTopoIIα, an important enzyme involved in DNA processes, coupled with synthesis and in vitro assays led to the establishment of a strategy of rational switch in mode of inhibition of the enzyme’s catalytic cycle. 6-Arylated derivatives of known imidazopyridine ligands were found to be selective inhibitors of hTopoIIα, while not showing TopoI inhibition and DNA binding. Interestingly, while the parent imidazopyridines acted as ATP-competitive inhibitors, arylated derivatives inhibited DNA cleavage similar to merbarone, indicating a switch in mode of inhibition from ATP-hydrolysis to the DNA-cleavage stage of catalytic cycle of the enzyme. The 6-aryl-imidazopyridines were relatively more cytotoxic than etoposide in cancer cells and less toxic to normal cells. Such unprecedented strategy will encourage research on “choice-based change” in target-specific mode of action for rapid drug discovery. PMID:25941559

Discovery and Characterization of Non-ATP Site Inhibitors of the Mitogen Activated Protein (MAP) Kinases

Energy Technology Data Exchange (ETDEWEB)

Comess, Kenneth M.; Sun, Chaohong; Abad-Zapatero, Cele; Goedken, Eric R.; Gum, Rebecca J.; Borhani, David W.; Argiriadi, Maria; Groebe, Duncan R.; Jia, Yong; Clampit, Jill E.; Haasch, Deanna L.; Smith, Harriet T.; Wang, Sanyi; Song, Danying; Coen, Michael L.; Cloutier, Timothy E.; Tang, Hua; Cheng, Xueheng; Quinn, Christopher; Liu, Bo; Xin, Zhili; Liu, Gang; Fry, Elizabeth H.; Stoll, Vincent; Ng, Teresa I.; Banach, David; Marcotte, Doug; Burns, David J.; Calderwood, David J.; Hajduk, Philip J. (Abbott)

2012-03-02

Inhibition of protein kinases has validated therapeutic utility for cancer, with at least seven kinase inhibitor drugs on the market. Protein kinase inhibition also has significant potential for a variety of other diseases, including diabetes, pain, cognition, and chronic inflammatory and immunologic diseases. However, as the vast majority of current approaches to kinase inhibition target the highly conserved ATP-binding site, the use of kinase inhibitors in treating nononcology diseases may require great selectivity for the target kinase. As protein kinases are signal transducers that are involved in binding to a variety of other proteins, targeting alternative, less conserved sites on the protein may provide an avenue for greater selectivity. Here we report an affinity-based, high-throughput screening technique that allows nonbiased interrogation of small molecule libraries for binding to all exposed sites on a protein surface. This approach was used to screen both the c-Jun N-terminal protein kinase Jnk-1 (involved in insulin signaling) and p38{alpha} (involved in the formation of TNF{alpha} and other cytokines). In addition to canonical ATP-site ligands, compounds were identified that bind to novel allosteric sites. The nature, biological relevance, and mode of binding of these ligands were extensively characterized using two-dimensional {sup 1}H/{sup 13}C NMR spectroscopy, protein X-ray crystallography, surface plasmon resonance, and direct enzymatic activity and activation cascade assays. Jnk-1 and p38{alpha} both belong to the MAP kinase family, and the allosteric ligands for both targets bind similarly on a ledge of the protein surface exposed by the MAP insertion present in the CMGC family of protein kinases and distant from the active site. Medicinal chemistry studies resulted in an improved Jnk-1 ligand able to increase adiponectin secretion in human adipocytes and increase insulin-induced protein kinase PKB phosphorylation in human hepatocytes, in

Meisoindigo, but not its core chemical structure indirubin, inhibits zebrafish interstitial leukocyte chemotactic migration.

Science.gov (United States)

Ye, Baixin; Xiong, Xiaoxing; Deng, Xu; Gu, Lijuan; Wang, Qiongyu; Zeng, Zhi; Gao, Xiang; Gao, Qingping; Wang, Yueying

2017-12-01

Inflammatory disease is a big threat to human health. Leukocyte chemotactic migration is required for efficient inflammatory response. Inhibition of leukocyte chemotactic migration to the inflammatory site has been shown to provide therapeutic targets for treating inflammatory diseases. Our study was designed to discover effective and safe compounds that can inhibit leukocyte chemotactic migration, thus providing possible novel therapeutic strategy for treating inflammatory diseases. In this study, we used transgenic zebrafish model (Tg:zlyz-EGFP line) to visualize the process of leukocyte chemotactic migration. Then, we used this model to screen the hit compound and evaluate its biological activity on leukocyte chemotactic migration. Furthermore, western blot analysis was performed to evaluate the effect of the hit compound on the AKT or ERK-mediated pathway, which plays an important role in leukocyte chemotactic migration. In this study, using zebrafish-based chemical screening, we identified that the hit compound meisoindigo (25 μM, 50 μM, 75 μM) can significantly inhibit zebrafish leukocyte chemotactic migration in a dose-dependent manner (p = 0.01, p = 0.0006, p migration (p = 0.43). Furthermore, our results unexpectedly showed that indirubin, the core structure of meisoindigo, had no significant effect on zebrafish leukocyte chemotactic migration (p = 0.6001). Additionally, our results revealed that meisoindigo exerts no effect on the Akt or Erk-mediated signalling pathway. Our results suggest that meisoindigo, but not indirubin, is effective for inhibiting leukocyte chemotactic migration, thus providing a potential therapeutic agent for treating inflammatory diseases.

Antidepressant Binding Site in a Bacterial Homologue of Neurotransmitter Transporters

International Nuclear Information System (INIS)

Singh, S.; Yamashita, A.; Gouaux, E.

2007-01-01

Sodium-coupled transporters are ubiquitous pumps that harness pre-existing sodium gradients to catalyse the thermodynamically unfavourable uptake of essential nutrients, neurotransmitters and inorganic ions across the lipid bilayer. Dysfunction of these integral membrane proteins has been implicated in glucose/galactose malabsorption, congenital hypothyroidism, Bartter's syndrome, epilepsy, depression, autism and obsessive-compulsive disorder. Sodium-coupled transporters are blocked by a number of therapeutically important compounds, including diuretics, anticonvulsants and antidepressants, many of which have also become indispensable tools in biochemical experiments designed to probe antagonist binding sites and to elucidate transport mechanisms. Steady-state kinetic data have revealed that both competitive and noncompetitive modes of inhibition exist. Antagonist dissociation experiments on the serotonin transporter (SERT) have also unveiled the existence of a low-affinity allosteric site that slows the dissociation of inhibitors from a separate high-affinity site. Despite these strides, atomic-level insights into inhibitor action have remained elusive. Here we screen a panel of molecules for their ability to inhibit LeuT, a prokaryotic homologue of mammalian neurotransmitter sodium symporters, and show that the tricyclic antidepressant (TCA) clomipramine noncompetitively inhibits substrate uptake. Cocrystal structures show that clomipramine, along with two other TCAs, binds in an extracellular-facing vestibule about 11 (angstrom) above the substrate and two sodium ions, apparently stabilizing the extracellular gate in a closed conformation. Off-rate assays establish that clomipramine reduces the rate at which leucine dissociates from LeuT and reinforce our contention that this TCA inhibits LeuT by slowing substrate release. Our results represent a molecular view into noncompetitive inhibition of a sodium-coupled transporter and define principles for the rational

Antidepressant Binding Site in a Bacterial Homologue of Neurotransmitter Transporters

Energy Technology Data Exchange (ETDEWEB)

Singh,S.; Yamashita, A.; Gouaux, E.

2007-01-01

Sodium-coupled transporters are ubiquitous pumps that harness pre-existing sodium gradients to catalyse the thermodynamically unfavourable uptake of essential nutrients, neurotransmitters and inorganic ions across the lipid bilayer. Dysfunction of these integral membrane proteins has been implicated in glucose/galactose malabsorption, congenital hypothyroidism, Bartter's syndrome, epilepsy, depression, autism and obsessive-compulsive disorder. Sodium-coupled transporters are blocked by a number of therapeutically important compounds, including diuretics, anticonvulsants and antidepressants, many of which have also become indispensable tools in biochemical experiments designed to probe antagonist binding sites and to elucidate transport mechanisms. Steady-state kinetic data have revealed that both competitive and noncompetitive modes of inhibition exist. Antagonist dissociation experiments on the serotonin transporter (SERT) have also unveiled the existence of a low-affinity allosteric site that slows the dissociation of inhibitors from a separate high-affinity site. Despite these strides, atomic-level insights into inhibitor action have remained elusive. Here we screen a panel of molecules for their ability to inhibit LeuT, a prokaryotic homologue of mammalian neurotransmitter sodium symporters, and show that the tricyclic antidepressant (TCA) clomipramine noncompetitively inhibits substrate uptake. Cocrystal structures show that clomipramine, along with two other TCAs, binds in an extracellular-facing vestibule about 11 {angstrom} above the substrate and two sodium ions, apparently stabilizing the extracellular gate in a closed conformation. Off-rate assays establish that clomipramine reduces the rate at which leucine dissociates from LeuT and reinforce our contention that this TCA inhibits LeuT by slowing substrate release. Our results represent a molecular view into noncompetitive inhibition of a sodium-coupled transporter and define principles for the

Identification of an allosteric binding site for RORγt inhibition

NARCIS (Netherlands)

Scheepstra, M.; Leysen, S.; van Almen, G.; Miller, J.R.; Piesvaux, J.; Kutilek, V.; van Eenennaam, H.; Zhang, H.; Barr, K.; Nagpal, S.; Soisson, S.M.; Kornienko, M.; Wiley, K.; Elsen, N.; Sharma, S.; Correll, C.C.; Trotter, B.W.; Stelt, van der M.; Oubrie, A.; Ottmann, C.; Parthasarathy, G.; Brunsveld, L.

2015-01-01

RORγt is critical for the differentiation and proliferation of Th17 cells associated with several chronic autoimmune diseases. We report the discovery of a novel allosteric binding site on the nuclear receptor RORγt. Co-crystallization of the ligand binding domain (LBD) of RORγt with a series of

Inhibition of telomerase by linear-chain fatty acids: a structural analysis.

Science.gov (United States)

Oda, Masako; Ueno, Takamasa; Kasai, Nobuyuki; Takahashi, Hirotada; Yoshida, Hiromi; Sugawara, Fumio; Sakaguchi, Kengo; Hayashi, Hideya; Mizushina, Yoshiyuki

2002-01-01

In the present study, we have found that mono-unsaturated linear-chain fatty acids in the cis configuration with C(18) hydrocarbon chains (i.e. oleic acid) strongly inhibited the activity of human telomerase in a cell-free enzymic assay, with an IC(50) value of 8.6 microM. Interestingly, fatty acids with hydrocarbon chain lengths below 16 or above 20 carbons substantially decreased the potency of inhibition of telomerase. Moreover, the cis-mono-unsaturated C(18) linear-chain fatty acid oleic acid was the strongest inhibitor of all the fatty acids tested. A kinetic study revealed that oleic acid competitively inhibited the activity of telomerase ( K (i)=3.06 microM) with respect to the telomerase substrate primer. The energy-minimized three-dimensional structure of the linear-chain fatty acid was calculated and modelled. A molecule width of 11.53-14.26 A (where 1 A=0.1 nm) in the C(16) to C(20) fatty acid structure was suggested to be important for telomerase inhibition. The three-dimensional structure of the telomerase active site (i.e. the substrate primer-binding site) appears to have a pocket that could bind oleic acid, with the pocket being 8.50 A long and 12.80 A wide. PMID:12121150

Inhibiting prenylation augments chemotherapy efficacy in renal cell carcinoma through dual inhibition on mitochondrial respiration and glycolysis.

Science.gov (United States)

Huang, Jiangrong; Yang, Xiaoyu; Peng, Xiaochun; Huang, Wei

2017-11-18

Prenylation is a posttranslational lipid modification required for the proper functions of a number of proteins involved in cell regulation. Here, we show that prenylation inhibition is important for renal cell carcinoma (RCC) growth, survival and response to chemotherapy, and its underlying mechanism may be contributed to mitochondrial dysfunction. We first demonstrated that a HMG-CoA reductase inhibitor pitavastatin inhibited mevalonate pathway and thereby prenylation in RCC cells. In addition, pitavastatin is effective in inhibiting growth and inducing apoptosis in a panel of RCC cell lines. Combination of pitavastatin and paclitaxel is significantly more effective than pitavastatin or paclitaxel alone as shown by both in vitro cell culture system and in vivo RCC xenograft model. Importantly, pitavastatin treatment inhibits mitochondrial respiration via suppressing mitochondrial complex I and II enzyme activities. Interestingly, different from mitochondrial inhibitor phenformin that inhibits mitochondrial respiration but activates glycolytic rate in RCC cells, pitavastatin significantly decreases glycolytic rate. The dual inhibitory action of pitavastatin on mitochondrial respiration and glycolysis results in remarkable energy depletion and oxidative stress in RCC cells. In addition, inhibition of prenylation by depleting Isoprenylcysteine carboxylmethyltransferase (Icmt) also mimics the inhibitory effects of pitavastatin in RCC cells. Our work demonstrates the previously unappreciated association between prenylation inhibition and energy metabolism in RCC, which can be therapeutically exploited, likely in tumors that largely rely on energy metabolism. Copyright © 2017 Elsevier Inc. All rights reserved.

Site-discrimination by molecular imposters at dissymmetric molecular crystal surfaces

Science.gov (United States)

Poloni, Laura N.

The organization of atoms and molecules into crystalline forms is ubiquitous in nature and has been critical to the development of many technologies on which modern society relies. Classical crystal growth theory can describe atomic crystal growth, however, a description of molecular crystal growth is lacking. Molecular crystals are often characterized by anisotropic intermolecular interactions and dissymmetric crystal surfaces with anisotropic growth rates along different crystallographic directions. This thesis describes combination of experimental and computational techniques to relate crystal structure to surface structure and observed growth rates. Molecular imposters, also known as tailor-made impurities, can be used to control crystal growth for practical applications such as inhibition of pathological crystals, but can also be used to understand site specificity at crystal growth surfaces. The first part of this thesis builds on previous real-time in situ atomic force microscopy (AFM) observations of dislocation-actuated growth on the morphologically significant face of hexagonal L-cystine crystals, which aggregate in vivo to form kidney stones in patients suffering from cystinuria. The inhibitory effect of various L-cystine structural mimics (a.k.a. molecular imposters) was investigated through experimental and computational methods to identify the key structural factors responsible for molecular recognition between molecular imposters and L-cystine crystal surface sites. The investigation of L-cystine crystal growth in the presence of molecular imposters through a combination of kinetic analysis using in situ AFM, morphology analysis and birefringence measurements of bulk crystals, and molecular modeling of imposter binding to energetically inequivalent surface sites revealed that different molecular imposters inhibited crystal growth by a Cabrera-Vermilyea pinning mechanism and that imposters bind to a single binding site on the dissymmetric {1000} L

Aqueous extracts of a Mars analogue regolith that mimics the Phoenix landing site do not inhibit spore germination or growth of model spacecraft contaminants Bacillus subtilis 168 and Bacillus pumilus SAFR-032

Science.gov (United States)

Nicholson, Wayne L.; McCoy, Lashelle E.; Kerney, Krystal R.; Ming, Douglas W.; Golden, D. C.; Schuerger, Andrew C.

2012-08-01

Because Mars is a primary target for life detection and habitability assessment missions, its exploration is also by necessity a Planetary Protection issue. The recent finding of significant levels of perchlorate (ClO4-) in regolith sampled from the Phoenix landing site raises the question of its potential biotoxicity to putative indigenous martian life, microbial forward contaminants from Earth, or future human visitors. To address this issue, an analogue regolith was constructed based on regolith chemistry data from the Phoenix landing site. A Mars Aqueous Regolith Extract (MARE) was prepared from the Phoenix analogue regolith and analyzed by ion chromatography. The MARE contained (mg/L) the cations Na+ (1411 ± 181), Mg2+ (1051 ± 160), Ca2+ (832 ± 125), and K+ (261 ± 29), and the anions SO42-(5911±993), ClO4-(5316±1767), Cl(171±25) and F- (2.0 ± 0.4). Nitrogen-containing species NO3-(773±113) and NO2-(6.9±2.3) were also present as a result of regolith preparation procedures, but their relevance to Mars is at present unknown. The MARE was tested for potential toxic effects on two model spacecraft contaminants, the spore-forming bacteria Bacillus subtilis strain 168 and Bacillus pumilus strain SAFR-032. In B. subtilis, spore germination and initial vegetative growth (up to ˜5 h) was not inhibited in a rich complex medium prepared with the MARE, but growth after 5 h was significantly suppressed in medium prepared using the MARE. Both B. subtilis and B. pumilus exhibited significantly higher rates of spore germination and growth in the MARE vs. DW with no additions (likely due to endogenous spore nutrients), but germination and growth was further stimulated by addition of glucose and a combination of buffered inorganic salts (K2HPO4, KH2PO4, (NH4)2SO4, and MgSO4). The data indicate that the aqueous environment in the regolith from the Phoenix landing site containing high levels of perchlorate does not pose a significant barrier to growth of putative

Photoinhibition in common atlantic macroalgae measured on site in Gran Canaria

Science.gov (United States)

Häder, D.-P.; Porst, M.; Lebert, M.

2001-03-01

The photosynthetic quantum yield was analysed in four common atlantic macroalgae, the Rhodophytes Gelidium arbuscula and Halopithys incurvus and the Phaeophytes Halopteris scoparia and Lobophora variegata in Gran Canaria, Canary Islands at their growth site. The fluorescence parameters were measured using a portable pulse amplitude modulated (PAM) fluorometer (PAM 2000) instrument and a diving PAM under water without removing the thalli from their growth sites. Solar radiation was monitored continuously above and under water during the whole experimental period using two three-channel dosimeters (European light dosimeter network; ELDONET) (Real Time Computer, Möhrendorf, Germany). These instruments measure solar radiation in three wavelength ranges, ultraviolet (UV)-A, UV-B and photosynthetic active radiation (PAR). In all four algae the effective photosynthetic quantum yield decreased significantly from the optimal values measured after dark adaptation due to exposure to 15 min solar radiation, but at least partially recovered subsequently in the shade within several hours. Increasing the exposure period to 30 min intensified the photoinhibition. In some algae no recovery was observed after this treatment and in others no significant recovery could be detected. Exposure to unfiltered solar radiation caused a significantly higher photoinhibition than PAR-only radiation or PAR plus UV-A. A substantial inhibition was found in all algae at their growth sites in the water column when the sun was at high angles, as measured with the diving PAM.

Prediction of FAD binding sites in electron transport proteins according to efficient radial basis function networks and significant amino acid pairs.

Science.gov (United States)

Le, Nguyen-Quoc-Khanh; Ou, Yu-Yen

2016-07-30

Cellular respiration is a catabolic pathway for producing adenosine triphosphate (ATP) and is the most efficient process through which cells harvest energy from consumed food. When cells undergo cellular respiration, they require a pathway to keep and transfer electrons (i.e., the electron transport chain). Due to oxidation-reduction reactions, the electron transport chain produces a transmembrane proton electrochemical gradient. In case protons flow back through this membrane, this mechanical energy is converted into chemical energy by ATP synthase. The convert process is involved in producing ATP which provides energy in a lot of cellular processes. In the electron transport chain process, flavin adenine dinucleotide (FAD) is one of the most vital molecules for carrying and transferring electrons. Therefore, predicting FAD binding sites in the electron transport chain is vital for helping biologists understand the electron transport chain process and energy production in cells. We used an independent data set to evaluate the performance of the proposed method, which had an accuracy of 69.84 %. We compared the performance of the proposed method in analyzing two newly discovered electron transport protein sequences with that of the general FAD binding predictor presented by Mishra and Raghava and determined that the accuracy of the proposed method improved by 9-45 % and its Matthew's correlation coefficient was 0.14-0.5. Furthermore, the proposed method enabled reducing the number of false positives significantly and can provide useful information for biologists. We developed a method that is based on PSSM profiles and SAAPs for identifying FAD binding sites in newly discovered electron transport protein sequences. This approach achieved a significant improvement after we added SAAPs to PSSM features to analyze FAD binding proteins in the electron transport chain. The proposed method can serve as an effective tool for predicting FAD binding sites in electron

Escherichia coli DinB inhibits replication fork progression without significantly inducing the SOS response.

Science.gov (United States)

Mori, Tetsuya; Nakamura, Tatsuro; Okazaki, Naoto; Furukohri, Asako; Maki, Hisaji; Akiyama, Masahiro Tatsumi

2012-01-01

The SOS response is readily triggered by replication fork stalling caused by DNA damage or a dysfunctional replicative apparatus in Escherichia coli cells. E. coli dinB encodes DinB DNA polymerase and its expression is upregulated during the SOS response. DinB catalyzes translesion DNA synthesis in place of a replicative DNA polymerase III that is stalled at a DNA lesion. We showed previously that DNA replication was suppressed without exogenous DNA damage in cells overproducing DinB. In this report, we confirm that this was due to a dose-dependent inhibition of ongoing replication forks by DinB. Interestingly, the DinB-overproducing cells did not significantly induce the SOS response even though DNA replication was perturbed. RecA protein is activated by forming a nucleoprotein filament with single-stranded DNA, which leads to the onset of the SOS response. In the DinB-overproducing cells, RecA was not activated to induce the SOS response. However, the SOS response was observed after heat-inducible activation in strain recA441 (encoding a temperature-sensitive RecA) and after replication blockage in strain dnaE486 (encoding a temperature-sensitive catalytic subunit of the replicative DNA polymerase III) at a non-permissive temperature when DinB was overproduced in these cells. Furthermore, since catalytically inactive DinB could avoid the SOS response to a DinB-promoted fork block, it is unlikely that overproduced DinB takes control of primer extension and thus limits single-stranded DNA. These observations suggest that DinB possesses a feature that suppresses DNA replication but does not abolish the cell's capacity to induce the SOS response. We conclude that DinB impedes replication fork progression in a way that does not activate RecA, in contrast to obstructive DNA lesions and dysfunctional replication machinery.

Inhibition of the ultrasonic microjet-pits on the carbon steel in the particles-water mixtures

Directory of Open Access Journals (Sweden)

Dayun Yan

2015-07-01

Full Text Available In the incubation period of ultrasonic cavitation, due to the impact of microjets on the material surface, the needle-like microjet-pits are formed. Because the formation of microjet-pits relates with the evolution of cavitation erosion on engineering materials, corresponding study will promote the understanding on the mechanism of cavitation erosion. However, little study on the microjet-pits has been carried out, especially in the particles-water mixture. In this study, we firstly demonstrated the microjet-pits on the carbon steel would be significantly inhibited by Al particles in water. Such inhibition effect indicated that particular particles might not only provide growth sites for cavitation bubbles but also affect the collapse of cavitation bubbles near a solid surface. Our study deepened the understanding on the ultrasonic cavitation erosion in the particles-water mixture.

An Ectosteric Inhibitor of Cathepsin K Inhibits Bone Resorption in Ovariectomized Mice

DEFF Research Database (Denmark)

Panwar, Preety; Xue, Liming; Søe, Kent

2017-01-01

The potent cathepsin K (CatK) inhibitor, Tanshinone IIA sulfonic sodium (T06), was tested for its in vitro and in vivo antiresorptive activities. T06 binds in an ectosteric site of CatK remote from its active site and selectively inhibits collagen degradation with an IC50 value of 2.7±0.2μM (CatK...

Effects of kinase inhibitors and potassium phosphate (KPi) on site-specific phosphorylation of branched chain α-ketoacid dehydrogenase (BCKDH)

International Nuclear Information System (INIS)

Kuntz, M.J.; Shimomura, Y.; Ozawa, T.; Harris, R.A.

1987-01-01

BCKDH is phosphorylated by a copurifying kinase at two serine residues on the Elα subunit. Phosphorylation of both sites occurs at about the same rate initially, but inactivation is believed associated only with site 1 phosphorylation. The effects of KPi and known inhibitors of BCKDH kinase, α-chloroisocaproate (CIC) and branched chain α-ketoacids (BCKA), on the phosphorylation of purified rat liver BCKDH were studied. Site-specific phosphorylation was quantitated by thin-layer electrophoresis of tryptic peptides followed by densitometric scanning of autoradiograms. Addition of 5 mM KPi was found necessary to stabilize the BCKDH activity at 37 0 C. Increasing the KPi to 50 mM dramatically increased the CIC and BCKA inhibition of site 1 and site 2 phosphorylation. The finding of enhanced sensitivity of inhibitors with 50 mM KPi may facilitate identification of physiologically important kinase effectors. Regardless of the KPi concentration, CIC and the BCKA showed much more effective inhibition of site 2 than site 1 phosphorylation. Although site 1 is the primary inactivating site, predominant inhibition of site 2 phosphorylation may provide a means of modulating kinase/phosphatase control of BCKDH activity under steady state conditions

Exposure of nonbreeding migratory shorebirds to cholinesterase-inhibiting contaminants in the western hemisphere

Science.gov (United States)

Strum, K.M.; Hooper, M.J.; Johnson, K.A.; Lanctot, Richard B.; Zaccagnini, M.E.; Sandercock, B.K.

2010-01-01

Migratory shorebirds frequently forage and roost in agricultural habitats, where they may be exposed to cholinesterase-inhibiting pesticides. Exposure to organophosphorus and carbamate compounds, common anti-cholinesterases, can cause sublethal effects, even death. To evaluate exposure of migratory shorebirds to organophosphorus and carbamates, we sampled birds stopping over during migration in North America and wintering in South America. We compared plasma cholinesterase activities and body masses of individuals captured at sites with no known sources of organophosphorus or carbamates to those captured in agricultural areas where agrochemicals were recommended for control of crop pests. In South America, plasma acetylcholinesterase and butyrylcholinesterase activity in Buff-breasted Sandpipers was lower at agricultural sites than at reference sites, indicating exposure to organophosphorus and carbamates. Results of plasma cholinesterase reactivation assays and foot-wash analyses were inconclusive. A meta-analysis of six species revealed no widespread effect of agricultural chemicals on cholinesterase activity. however, four of six species were negative for acetylcholinesterase and one of six for butyrylcholinesterase, indicating negative effects of pesticides on cholinesterase activity in a subset of shorebirds. Exposure to cholinesterase inhibitors can decrease body mass, but comparisons between treatments and hemispheres suggest that agrochemicals did not affect migratory shorebirds' body mass. Our study, one of the first to estimate of shorebirds' exposure to cholinesterase-inhibiting pesticides, suggests that shorebirds are being exposed to cholinesterase- inhibiting pesticides at specific sites in the winter range but not at migratory stopover sites. future research should examine potential behavioral effects of exposure and identify other potential sitesand levels of exposure. ?? The Cooper Ornithological Society 2010.

Inhibition of plasma butyrylcholinesterase activity in the lizard Gallotia galloti palmae by pesticides: a field study

International Nuclear Information System (INIS)

Sanchez-Hernandez, Juan C.; Carbonell, R.; Henriquez Perez, A.; Montealegre, M.; Gomez, L.

2004-01-01

A field study was performed to evaluate the effect of exposure to organophosphorus (OP) and carbamate (CB) pesticides on the lizard Gallotia galloti palmae. Butyrylcholinesterase (BChE) activity was measured in the plasma of 420 lizards collected from agricultural and reference areas on the Island of La Palma (Canary Islands, Spain) in two sampling periods. Exposure to cholinesterase-inhibiting pesticides was evaluated by a statistical criterion based on a threshold value (two standard deviations below the mean enzyme activity) calculated for the reference group, and a chemical criterion based on the in vitro reactivation of BChE activity using pyridine-2-aldoxime methochloride (2-PAM) or after water dilution of the sample. Mean (±SD) BChE activity for lizards from agricultural areas was significantly lower (Fuencaliente site = 2.00 ± 0.98 μmol min -1 ml -1 , Tazacorte site = 2.88 ± 1.08) than that for lizards from the reference areas (Los Llanos site = 3.06 ± 1.17 μmol min -1 ml -1 , Tigalate site = 3.96 ± 1.62). According to the statistical criterion, the number of lizards with BChE depressed was higher at Fuencaliente (22% of males and 25.4% of females) than that sampled at Tazacorte (7.8% of males and 6.2% of females). According to the chemical criterion, Fuencaliente also yielded a higher number of individuals (112 males and 47 females) with BChE activity inhibited by both OP and CB pesticides. CBs appeared to be the pesticides most responsible for BChE inhibition because most of the samples showed reactivation of BChE activity after water treatment (63.3% from Fuencaliente and 29% from Tazacorte). We concluded that the use of reactivation techniques on plasma BChE activity is a better and more accurate method for assessing field exposure to OP/CB pesticides in this lizard species than making direct comparisons of enzyme activity levels between sampling areas. - Capsule: Chemical reactivation of lizard BChE activity is a suitable diagnostic method for

Migration of allosensitized helper but not cytolytic T-lymphocyte clones is inhibited by prostaglandin E2

International Nuclear Information System (INIS)

Jordan, M.L.; Hoffman, R.A.; Simmons, R.L.

1986-01-01

The authors have previously reported that random migration of one clone of C57BL/6 anti DBA/2 helper lymphocytes is significantly inhibited by physiologic concentrations of prostaglandin E 2 (PGE 2 ). The present studies were designed to determine if lymphocyte locomotor responses to PGE 2 are dictated by (1) clone effector function and/or (2) the presence of specific cell surface binding sites for PGE 2 . Random locomotion of eight different lymphocyte clones (all C57BL/6 anti DBA/2) was studied in a modified Boyden chamber assay. Clone function was characterized as helper (H, n = 3), cytolytic (C, n = 4) or cytolytic only in the presence of lectin (L, n = 1). Random migration of all H clones was consistently inhibited by PGE 2 . However, none of the clones possessing a lytic mechanism (C or L) were inhibited by even the highest (1000 ng/ml) concentration of PGE 2 tested. Incubation of clones with 3 H-PGE 2 in the presence of excess unlabelled PGE 2 did not demonstrate specific binding of PGE 2 to either H or C clones. The authors conclude that (1) the effects of PGE 2 on lymphocyte random migration are effector function specific and (2) these responses do not appear to be mediated by specialized cell surface receptors for PGE 2 . Subset specific locomotor responses to PGE 2 may constitute a mechanism whereby lymphocytes with distinct effector functions may differentially accumulate at sites of inflammation

Environmental Assessment and Finding of No Significant Impact: Implementation of the Wetland Mitigation Bank Program at the Savannah River Site

Energy Technology Data Exchange (ETDEWEB)

N/A

1999-04-28

The Department of Energy (DOE) has prepared an environmental assessment (EA) (DOE/EA-1205) for the proposed implementation of a wetland mitigation bank program at the Savannah River Site (SRS), located near Aiken, South Carolina. Based on the analyses in the EA, DOE has determined that the proposed action is not a major Federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act of 1969 (NEPA). Therefore, the preparation of an environmental impact statement (EIS) is not required, and DOE is issuing this Finding of No Significant Impact (FONSI) and Floodplain Statement of Findings.

Kinetics and Mechanism Study of Competitive Inhibition of Jack-Bean Urease by Baicalin

Science.gov (United States)

Tan, Lirong; Su, Jiyan; Wu, Dianwei; Yu, Xiaodan; Su, Zuqing; Wu, Xiaoli; Kong, Songzhi; Lai, Xiaoping; Lin, Ji; Su, Ziren

2013-01-01

Baicalin (BA) is the principal component of Radix Scutellariae responsible for its pharmacological activity. In this study, kinetics and mechanism of inhibition by BA against jack-bean urease were investigated for its therapeutic potential. It was revealed that the IC50 of BA against jack-bean urease was 2.74 ± 0.51 mM, which was proved to be a competitive and concentration-dependent inhibition with slow-binding progress curves. The rapid formation of initial BA-urease complex with an inhibition constant of K i = 3.89 × 10−3 mM was followed by a slow isomerization into the final complex with an overall inhibition constant of K i* = 1.47 × 10−4 mM. High effectiveness of thiol protectors against BA inhibition indicated that the strategic role of the active-site sulfhydryl group of the urease was involved in the blocking process. Moreover, the inhibition of BA was proved to be reversible due to the fact that urease could be reactivated by dithiothreitol but not reactant dilution. Molecular docking assay suggested that BA made contacts with the important activating sulfhydryl group Cys-592 residues and restricted the mobility of the active-site flap. Taken together, it could be deduced that BA was a competitive inhibitor targeting thiol groups of urease in a slow-binding manner both reversibly and concentration-dependently, serving as a promising urease inhibitor for treatments on urease-related diseases. PMID:24198731

Ebselen: Mechanisms of Glutamate Dehydrogenase and Glutaminase Enzyme Inhibition.

Science.gov (United States)

Yu, Yan; Jin, Yanhong; Zhou, Jie; Ruan, Haoqiang; Zhao, Han; Lu, Shiying; Zhang, Yue; Li, Di; Ji, Xiaoyun; Ruan, Benfang Helen

2017-12-15

Ebselen modulates target proteins through redox reactions with selenocysteine/cysteine residues, or through binding to the zinc finger domains. However, a recent contradiction in ebselen inhibition of kidney type glutaminase (KGA) stimulated our interest in investigating its inhibition mechanism with glutamate dehydrogenase (GDH), KGA, thioredoxin reductase (TrxR), and glutathione S-transferase. Fluorescein- or biotin-labeled ebselen derivatives were synthesized for mechanistic analyses. Biomolecular interaction analyses showed that only GDH, KGA, and TrxR proteins can bind to the ebselen derivative, and the binding to GDH and KGA could be competed off by glutamine or glutamate. From the gel shift assays, the fluorescein-labeled ebselen derivative could co-migrate with hexameric GDH and monomeric/dimeric TrxR in a dose-dependent manner; it also co-migrated with KGA but disrupted the tetrameric form of the KGA enzyme at a high compound concentration. Further proteomic analysis demonstrated that the ebselen derivative could cross-link with proteins through a specific cysteine at the active site of GDH and TrxR proteins, but for KGA protein, the binding site is at the N-terminal appendix domain outside of the catalytic domain, which might explain why ebselen is not a potent KGA enzyme inhibitor in functional assays. In conclusion, ebselen could inhibit enzyme activity by binding to the catalytic domain or disruption of the protein complex. In addition, ebselen is a relatively potent selective GDH inhibitor that might provide potential therapeutic opportunities for hyperinsulinism-hyperammonemia syndrome patients who have the mutational loss of GTP inhibition.

Vanadate monomers and dimers both inhibit the human prostatic acid phosphatase.

Science.gov (United States)

Crans, D C; Simone, C M; Saha, A K; Glew, R H

1989-11-30

A combination of enzyme kinetics and 51V NMR spectroscopy was used to identify the species of vanadate that inhibits acid phosphatases. Monomeric vanadate was shown to inhibit wheat germ and potato acid phosphatases. At pH 5.5, the vanadate dimer inhibits the human prostatic acid phosphatase whereas at pH 7.0 it is the vanadate monomer that inhibits this enzyme. The pH-dependent shift in the affinity of the prostatic phosphatase for vanadate is presumably due to deprotonation of an amino acid side chain in or near the binding site resulting in a conformational change in the protein. pH may be a subtle effector of the insulin-like vanadate activity in biological systems and may explain some of the differences in selectivity observed with the protein phosphatases.

Tandem-pore K+ channels mediate inhibition of orexin neurons by glucose

DEFF Research Database (Denmark)

Burdakov, Denis; Jensen, Lise T; Alexopoulos, Haris

2006-01-01

Glucose-inhibited neurons orchestrate behavior and metabolism according to body energy levels, but how glucose inhibits these cells is unknown. We studied glucose inhibition of orexin/hypocretin neurons, which promote wakefulness (their loss causes narcolepsy) and also regulate metabolism...... and reward. Here we demonstrate that their inhibition by glucose is mediated by ion channels not previously implicated in central or peripheral glucose sensing: tandem-pore K(+) (K(2P)) channels. Importantly, we show that this electrical mechanism is sufficiently sensitive to encode variations in glucose...... levels reflecting those occurring physiologically between normal meals. Moreover, we provide evidence that glucose acts at an extracellular site on orexin neurons, and this information is transmitted to the channels by an intracellular intermediary that is not ATP, Ca(2+), or glucose itself...

Time course of the antiproteinuric and antihypertensive effects of direct renin inhibition in type 2 diabetes

DEFF Research Database (Denmark)

Persson, F; Rossing, P; Schjoedt, K J

2008-01-01

Inhibition of renin with an active site inhibitor, aliskiren, lowers blood pressure (BP) in diabetic patients. Here, we studied the time course of the antihypertensive and antiproteinuric effect of renin inhibition in 15 patients with type 2 diabetes and elevated urinary albumin/creatinine ratios...

Molecular sites for the positive allosteric modulation of glycine receptors by endocannabinoids.

Directory of Open Access Journals (Sweden)

Gonzalo E Yévenes

Full Text Available Glycine receptors (GlyRs are transmitter-gated anion channels of the Cys-loop superfamily which mediate synaptic inhibition at spinal and selected supraspinal sites. Although they serve pivotal functions in motor control and sensory processing, they have yet to be exploited as drug targets partly because of hitherto limited possibilities for allosteric control. Endocannabinoids (ECs have recently been characterized as direct allosteric GlyR modulators, but the underlying molecular sites have remained unknown. Here, we show that chemically neutral ECs (e.g. anandamide, AEA are positive modulators of α(1, α(2 and α(3 GlyRs, whereas acidic ECs (e.g. N-arachidonoyl-glycine; NA-Gly potentiate α(1 GlyRs but inhibit α(2 and α(3. This subunit-specificity allowed us to identify the underlying molecular sites through analysis of chimeric and mutant receptors. We found that alanine 52 in extracellular loop 2, glycine 254 in transmembrane (TM region 2 and intracellular lysine 385 determine the positive modulation of α(1 GlyRs by NA-Gly. Successive substitution of non-conserved extracellular and TM residues in α(2 converted NA-Gly-mediated inhibition into potentiation. Conversely, mutation of the conserved lysine within the intracellular loop between TM3 and TM4 attenuated NA-Gly-mediated potentiation of α(1 GlyRs, without affecting inhibition of α(2 and α(3. Notably, this mutation reduced modulation by AEA of all three GlyRs. These results define molecular sites for allosteric control of GlyRs by ECs and reveal an unrecognized function for the TM3-4 intracellular loop in the allosteric modulation of Cys-loop ion channels. The identification of these sites may help to understand the physiological role of this modulation and facilitate the development of novel therapeutic approaches to diseases such as spasticity, startle disease and possibly chronic pain.

Bilobalide, a unique constituent of Ginkgo biloba, inhibits inflammatory pain in rats.

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Goldie, Michelle; Dolan, Sharron

2013-08-01

Standardized Ginkgo biloba extract EGb 761 has been shown to inhibit inflammatory hyperalgesia in rats; however, the mechanism of action is not known. This study set out to investigate the anti-inflammatory and analgesic potential of bilobalide, a unique G. biloba constituent, in three well-characterized models of acute inflammatory pain. The effect of oral, intraplantar or intrathecal administration of bilobalide or drug-vehicle (0.25% agar; 10% ethanol in H2O) on responses to noxious thermal and mechanical stimulation of the hindpaw, and paw oedema were assessed in adult male Wistar rats before and after intradermal hindpaw injection of carrageenan (3%; 50 μl) or capsaicin (10 μg; 50 μl) or after hindpaw incision (n=6-8/group). Oral administration of bilobalide (10-30 mg/kg) significantly inhibited thermal hyperalgesia in response to carrageenan, capsaicin and paw incision, independent of dose, with an efficacy similar to that of diclofenac. In the carrageenan model, mechanical hypersensitivity and paw oedema were also significantly reduced after treatment with bilobalide (10-30 mg/kg). Intrathecal administration of bilobalide (0.5-1 μg) inhibited carrageenan-induced thermal hyperalgesia, but had no effect on mechanical hypersensitivity or paw oedema (application≥2 μg induced adverse effects, precluding testing of higher doses). Intraplantar administration of bilobalide (30-100 μg) had no effect. These data show that bilobalide is a potent anti-inflammatory and antihyperalgesic agent, the therapeutic effects of which are mediated in part through a central site of action, and may account for the therapeutic action of the whole extract G. biloba.

Structural basis for cyclophellitol inhibition of a β-glucosidase

DEFF Research Database (Denmark)

Gloster, Tracey M.; Madsen, Robert; Davies, Gideon J.

2007-01-01

The structural basis for b-glucosidase inhibition by cyclophellitol is demonstrated using X-ray crystallography, enzyme kinetics and mass spectrometry. The natural product was shown to bind by a covalent bond in the active site of the enzyme. This bond is formed by ring-opening of the epoxide...

Prolonged pharmacological inhibition of cathepsin C results in elimination of neutrophil serine proteases

DEFF Research Database (Denmark)

Guarino, Carla; Hamon, Yveline; Croix, Cécile

2017-01-01

cyclopropyl nitrile CatC inhibitor almost totally lack elastase. We confirmed the elimination of neutrophil elastase-like proteases by prolonged inhibition of CatC in a non-human primate. We also showed that neutrophils lacking elastase-like protease activities were still recruited to inflammatory sites....... These preclinical results demonstrate that the disappearance of neutrophil elastase-like proteases as observed in PLS patients can be achieved by pharmacological inhibition of bone marrow CatC. Such a transitory inhibition of CatC might thus help to rebalance the protease load during chronic inflammatory diseases...

The binding sites for cocaine and dopamine in the dopamine transporter overlap

DEFF Research Database (Denmark)

Beuming, Thijs; Kniazeff, Julie; Bergmann, Marianne L

2008-01-01

Cocaine is a widely abused substance with psychostimulant effects that are attributed to inhibition of the dopamine transporter (DAT). We present molecular models for DAT binding of cocaine and cocaine analogs constructed from the high-resolution structure of the bacterial transporter homolog Leu......T. Our models suggest that the binding site for cocaine and cocaine analogs is deeply buried between transmembrane segments 1, 3, 6 and 8, and overlaps with the binding sites for the substrates dopamine and amphetamine, as well as for benztropine-like DAT inhibitors. We validated our models by detailed...... inhibition of dopamine transport by cocaine....

Online Transcranial Magnetic Stimulation Protocol for Measuring Cortical Physiology Associated with Response Inhibition.

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Guthrie, Michael D; Gilbert, Donald L; Huddleston, David A; Pedapati, Ernest V; Horn, Paul S; Mostofsky, Stewart H; Wu, Steve W

2018-02-08

We describe the development of a reproducible, child-friendly motor response inhibition task suitable for online Transcranial Magnetic Stimulation (TMS) characterization of primary motor cortex (M1) excitability and inhibition. Motor response inhibition prevents unwanted actions and is abnormal in several neuropsychiatric conditions. TMS is a non-invasive technology that can quantify M1 excitability and inhibition using single- and paired-pulse protocols and can be precisely timed to study cortical physiology with high temporal resolution. We modified the original Slater-Hammel (S-H) stop signal task to create a "racecar" version with TMS pulses time-locked to intra-trial events. This task is self-paced, with each trial initiating after a button push to move the racecar towards the 800 ms target. GO trials require a finger-lift to stop the racecar just before this target. Interspersed randomly are STOP trials (25%) during which the dynamically adjusted stop signal prompts subjects to prevent finger-lift. For GO trials, TMS pulses were delivered at 650 ms after trial onset; whereas, for STOP trials, the TMS pulses occurred 150 ms after the stop signal. The timings of the TMS pulses were decided based on electroencephalography (EEG) studies showing event-related changes in these time ranges during stop signal tasks. This task was studied in 3 blocks at two study sites (n=38) and we recorded behavioral performance and event-related motor-evoked potentials (MEP). Regression modelling was used to analyze MEP amplitudes using age as a covariate with multiple independent variables (sex, study site, block, TMS pulse condition [single- vs. paired-pulse], trial condition [GO, successful STOP, failed STOP]). The analysis showed that TMS pulse condition (p<0.0001) and its interaction with trial condition (p=0.009) were significant. Future applications for this online S-H/TMS paradigm include the addition of simultaneous EEG acquisition to measure TMS-evoked EEG potentials. A

Nickel Inhibits Mitochondrial Fatty Acid Oxidation

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Uppala, Radha; McKinney, Richard W.; Brant, Kelly A.; Fabisiak, James P.; Goetzman, Eric S.

2015-01-01

Nickel exposure is associated with changes in cellular energy metabolism which may contribute to its carcinogenic properties. Here, we demonstrate that nickel strongly represses mitochondrial fatty acid oxidation—the pathway by which fatty acids are catabolized for energy—in both primary human lung fibroblasts and mouse embryonic fibroblasts. At the concentrations used, nickel suppresses fatty acid oxidation without globally suppressing mitochondrial function as evidenced by increased glucose oxidation to CO2. Pre-treatment with L-carnitine, previously shown to prevent nickel-induced mitochondrial dysfunction in neuroblastoma cells, did not prevent the inhibition of fatty acid oxidation. The effect of nickel on fatty acid oxidation occurred only with prolonged exposure (>5 hr), suggesting that direct inhibition of the active sites of metabolic enzymes is not the mechanism of action. Nickel is a known hypoxia-mimetic that activates hypoxia inducible factor-1α (HIF1α). Nickel-induced inhibition of fatty acid oxidation was blunted in HIF1α knockout fibroblasts, implicating HIF1α as one contributor to the mechanism. Additionally, nickel down-regulated the protein levels of the key fatty acid oxidation enzyme very long-chain acyl-CoA dehydrogenase (VLCAD) in a dose-dependent fashion. In conclusion, inhibition of fatty acid oxidation by nickel, concurrent with increased glucose metabolism, represents a form of metabolic reprogramming that may contribute to nickel-induced carcinogenesis. PMID:26051273

Inhibition of colorectal cancer genomic copy number alterations and chromosomal fragile site tumor suppressor FHIT and WWOX deletions by DNA mismatch repair

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Gelincik, Ozkan; Blecua, Pedro; Edelmann, Winfried; Kucherlapati, Raju; Zhou, Kathy; Jasin, Maria; Gümüş, Zeynep H.; Lipkin, Steven M.

2017-01-01

Homologous recombination (HR) enables precise DNA repair after DNA double strand breaks (DSBs) using identical sequence templates, whereas homeologous recombination (HeR) uses only partially homologous sequences. Homeologous recombination introduces mutations through gene conversion and genomic deletions through single-strand annealing (SSA). DNA mismatch repair (MMR) inhibits HeR, but the roles of mammalian MMR MutL homologues (MLH1, PMS2 and MLH3) proteins in HeR suppression are poorly characterized. Here, we demonstrate that mouse embryonic fibroblasts (MEFs) carrying Mlh1, Pms2, and Mlh3 mutations have higher HeR rates, by using 7,863 uniquely mapping paired direct repeat sequences (DRs) in the mouse genome as endogenous gene conversion and SSA reporters. Additionally, when DSBs are induced by gamma-radiation, Mlh1, Pms2 and Mlh3 mutant MEFs have higher DR copy number alterations (CNAs), including DR CNA hotspots previously identified in mouse MMR-deficient colorectal cancer (dMMR CRC). Analysis of The Cancer Genome Atlas CRC data revealed that dMMR CRCs have higher genome-wide DR HeR rates than MMR proficient CRCs, and that dMMR CRCs have deletion hotspots in tumor suppressors FHIT/WWOX at chromosomal fragile sites FRA3B and FRA16D (which have elevated DSB rates) flanked by paired homologous DRs and inverted repeats (IR). Overall, these data provide novel insights into the MMR-dependent HeR inhibition mechanism and its role in tumor suppression. PMID:29069730

Significance of the evaluation of radiation dose at the site boundary

International Nuclear Information System (INIS)

Takitani, Koichi

2013-01-01

Nuclear Regulation Authority, Japan, is drawing up new regulation standards for the light water reactors. The focal point of the new regulation drawing is how 'the safeguard against the release of radioactive materials at possible severe accident' should be shaped up. Checking the radiation dose rate at the site boundary is indispensable for the evaluation of the efficiency of measures against the severe accident. 'Avoiding radiation hazard on habitants' should be included in the regulation. The critical dose may be 100mSv for whole body and 1000mSv for the children's thyroid gland. (J.P.N.)

Atomic-scale insight into the origin of pyridine inhibition of MoS2-based hydrotreating catalysts

DEFF Research Database (Denmark)

Temel, Burcin; Tuxen, Anders K.; Kibsgaard, Jakob

2010-01-01

in earlier IR experiments on high surface alumina-supported MoS2 catalyst. The adsorption sites appear to be very similar to the brim sites involved in hydrogenation reactions in HDS. Thus, the combined STM and DFT results provide new atomic-scale insight into the inhibition effect of basic N......-compounds in HDS and the first direct observation of the adsorption mode of basic N-compounds on the catalytically active MoS2 edges. Our results lend further support to previously reported correlations between inhibiting strength and proton affinity for the N-containing compounds....

Mutation of androgen receptor N-terminal phosphorylation site Tyr-267 leads to inhibition of nuclear translocation and DNA binding.

Directory of Open Access Journals (Sweden)

Mehmet Karaca

Full Text Available Reactivation of androgen receptor (AR may drive recurrent prostate cancer in castrate patients. Ack1 tyrosine kinase is overexpressed in prostate cancer and promotes castrate resistant xenograft tumor growth and enhances androgen target gene expression and AR recruitment to enhancers. Ack1 phosphorylates AR at Tyr-267 and possibly Tyr-363, both in the N-terminal transactivation domain. In this study, the role of these phosphorylation sites was investigated by characterizing the phosphorylation site mutants in the context of full length and truncated AR lacking the ligand-binding domain. Y267F and Y363F mutants showed decreased transactivation of reporters. Expression of wild type full length and truncated AR in LNCaP cells increased cell proliferation in androgen-depleted conditions and increased colony formation. However, the Y267F mutant of full length and truncated AR was defective in stimulating cell proliferation. The Y363F mutant was less severely affected than the Y267F mutant. The full length AR Y267F mutant was defective in nuclear translocation induced by androgen or Ack1 kinase. The truncated AR was constitutively localized to the nucleus. Chromatin immunoprecipitation analysis showed that it was recruited to the target enhancers without androgen. The truncated Y267F AR mutant did not exhibit constitutive nuclear localization and androgen enhancer binding activity. These results support the concept that phosphorylation of Tyr-267, and to a lesser extent Tyr-363, is required for AR nuclear translocation and recruitment and DNA binding and provide a rationale for development of novel approaches to inhibit AR activity.

Motility and chemotaxis mediate the preferential colonization of gastric injury sites by Helicobacter pylori.

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Eitaro Aihara

2014-07-01

Full Text Available Helicobacter pylori (H. pylori is a pathogen contributing to peptic inflammation, ulceration, and cancer. A crucial step in the pathogenic sequence is when the bacterium first interacts with gastric tissue, an event that is poorly understood in vivo. We have shown that the luminal space adjacent to gastric epithelial damage is a microenvironment, and we hypothesized that this microenvironment might enhance H. pylori colonization. Inoculation with 106 H. pylori (wild-type Sydney Strain 1, SS1 significantly delayed healing of acetic-acid induced ulcers at Day 1, 7 and 30 post-inoculation, and wild-type SS1 preferentially colonized the ulcerated area compared to uninjured gastric tissue in the same animal at all time points. Gastric resident Lactobacillus spp. did not preferentially colonize ulcerated tissue. To determine whether bacterial motility and chemotaxis are important to ulcer healing and colonization, we analyzed isogenic H. pylori mutants defective in motility (ΔmotB or chemotaxis (ΔcheY. ΔmotB (10(6 failed to colonize ulcerated or healthy stomach tissue. ΔcheY (10(6 colonized both tissues, but without preferential colonization of ulcerated tissue. However, ΔcheY did modestly delay ulcer healing, suggesting that chemotaxis is not required for this process. We used two-photon microscopy to induce microscopic epithelial lesions in vivo, and evaluated accumulation of fluorescently labeled H. pylori at gastric damage sites in the time frame of minutes instead of days. By 5 min after inducing damage, H. pylori SS1 preferentially accumulated at the site of damage and inhibited gastric epithelial restitution. H. pylori ΔcheY modestly accumulated at the gastric surface and inhibited restitution, but did not preferentially accumulate at the injury site. H. pylori ΔmotB neither accumulated at the surface nor inhibited restitution. We conclude that bacterial chemosensing and motility rapidly promote H. pylori colonization of injury sites

Motility and Chemotaxis Mediate the Preferential Colonization of Gastric Injury Sites by Helicobacter pylori

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Aihara, Eitaro; Closson, Chet; Matthis, Andrea L.; Schumacher, Michael A.; Engevik, Amy C.; Zavros, Yana; Ottemann, Karen M.; Montrose, Marshall H.

2014-01-01

Helicobacter pylori (H. pylori) is a pathogen contributing to peptic inflammation, ulceration, and cancer. A crucial step in the pathogenic sequence is when the bacterium first interacts with gastric tissue, an event that is poorly understood in vivo. We have shown that the luminal space adjacent to gastric epithelial damage is a microenvironment, and we hypothesized that this microenvironment might enhance H. pylori colonization. Inoculation with 106 H. pylori (wild-type Sydney Strain 1, SS1) significantly delayed healing of acetic-acid induced ulcers at Day 1, 7 and 30 post-inoculation, and wild-type SS1 preferentially colonized the ulcerated area compared to uninjured gastric tissue in the same animal at all time points. Gastric resident Lactobacillus spp. did not preferentially colonize ulcerated tissue. To determine whether bacterial motility and chemotaxis are important to ulcer healing and colonization, we analyzed isogenic H. pylori mutants defective in motility (ΔmotB) or chemotaxis (ΔcheY). ΔmotB (106) failed to colonize ulcerated or healthy stomach tissue. ΔcheY (106) colonized both tissues, but without preferential colonization of ulcerated tissue. However, ΔcheY did modestly delay ulcer healing, suggesting that chemotaxis is not required for this process. We used two-photon microscopy to induce microscopic epithelial lesions in vivo, and evaluated accumulation of fluorescently labeled H. pylori at gastric damage sites in the time frame of minutes instead of days. By 5 min after inducing damage, H. pylori SS1 preferentially accumulated at the site of damage and inhibited gastric epithelial restitution. H. pylori ΔcheY modestly accumulated at the gastric surface and inhibited restitution, but did not preferentially accumulate at the injury site. H. pylori ΔmotB neither accumulated at the surface nor inhibited restitution. We conclude that bacterial chemosensing and motility rapidly promote H. pylori colonization of injury sites, and thereby biases

Quantitative inhibition of soil C and N cycling by ectomycorrhizal fungi under field condition

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Averill, C.; Hawkes, C.

2014-12-01

Ectomycorrhizal (ECM) ecosystems store more carbon than non-ectomycorrhizal ecosystems at global scale. Recent theoretical and empirical work suggests the presence of ECM fungi allows plants to compete directly with decomposers for soil nitrogen (N) via exo-enzyme synthesis. Experimental ECM exclusion often results in a release from competition of saprotrophic decomposers, allowing for increased C-degrading enzyme production, increased microbial biomass, and eventually declines in soil C stocks. Our knowledge of this phenomenon is limited, however, to the presence or absence of ECM fungi. It remains unknown if competitive repression of saprotrophic microbes and soil C cycling by ECM fungi varies with ECM abundance. This is particularly relevant to global change experiments when manipulations alter plant C allocation to ECM symbionts. To test if variation in ECM abundance alters the competitive inhibition of saprotrophic soil microbes (quantitative inhibition) we established experimental ECM exclusion treatments along an ECM abundance gradient. We dug trenches to experimentally exclude ECM fungi, allowing us to test for competitive release of soil saprotrophs from competition. To control for disturbance we placed in-growth bags both inside and outside of trenches. Consistent with the quantitative inhibition hypothesis, sites with more ECM fungi had significantly less microbial biomass per unit soil C and lower rates of N mineralization. Consistent with a release from competition, C-degrading enzyme activities were higher and gross proteolytic rates were lower per unit microbial biomass inside compared to outside trenches. We interpret this to reflect increased microbial investment in C-acquisition and decreased investment in N-acquisition in the absence of ECM fungi. Furthermore, the increase in C-degrading enzymes per unit microbial biomass was significantly greater in sites with the most abundant ECM fungi. Based on these results, ECM-saprotroph competition does

Global phosphotyrosine proteomics identifies PKCδ as a marker of responsiveness to Src inhibition in colorectal cancer.

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Eliot T McKinley

Full Text Available Sensitive and specific biomarkers of protein kinase inhibition can be leveraged to accelerate drug development studies in oncology by associating early molecular responses with target inhibition. In this study, we utilized unbiased shotgun phosphotyrosine (pY proteomics to discover novel biomarkers of response to dasatinib, a small molecule Src-selective inhibitor, in preclinical models of colorectal cancer (CRC. We performed unbiased mass spectrometry shotgun pY proteomics to reveal the pY proteome of cultured HCT-116 colonic carcinoma cells, and then extended this analysis to HCT-116 xenograft tumors to identify pY biomarkers of dasatinib-responsiveness in vivo. Major dasatinib-responsive pY sites in xenograft tumors included sites on delta-type protein kinase C (PKCδ, CUB-domain-containing protein 1 (CDCP1, Type-II SH2-domain-containing inositol 5-phosphatase (SHIP2, and receptor protein-tyrosine phosphatase alpha (RPTPα. The pY313 site PKCδ was further supported as a relevant biomarker of dasatinib-mediated Src inhibition in HCT-116 xenografts by immunohistochemistry and immunoblotting with a phosphospecific antibody. Reduction of PKCδ pY313 was further correlated with dasatinib-mediated inhibition of Src and diminished growth as spheroids of a panel of human CRC cell lines. These studies reveal PKCδ pY313 as a promising readout of Src inhibition in CRC and potentially other solid tumors and may reflect responsiveness to dasatinib in a subset of colorectal cancers.

Inhibition of Urease by Disulfiram, an FDA-Approved Thiol Reagent Used in Humans.

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Díaz-Sánchez, Ángel Gabriel; Alvarez-Parrilla, Emilio; Martínez-Martínez, Alejandro; Aguirre-Reyes, Luis; Orozpe-Olvera, Jesica Aline; Ramos-Soto, Miguel Armando; Núñez-Gastélum, José Alberto; Alvarado-Tenorio, Bonifacio; de la Rosa, Laura Alejandra

2016-11-26

Urease is a nickel-dependent amidohydrolase that catalyses the decomposition of urea into carbamate and ammonia, a reaction that constitutes an important source of nitrogen for bacteria, fungi and plants. It is recognized as a potential antimicrobial target with an impact on medicine, agriculture, and the environment. The list of possible urease inhibitors is continuously increasing, with a special interest in those that interact with and block the flexible active site flap. We show that disulfiram inhibits urease in Citrullus vulgaris (CVU), following a non-competitive mechanism, and may be one of this kind of inhibitors. Disulfiram is a well-known thiol reagent that has been approved by the FDA for treatment of chronic alcoholism. We also found that other thiol reactive compounds (l-captopril and Bithionol) and quercetin inhibits CVU. These inhibitors protect the enzyme against its full inactivation by the thiol-specific reagent Aldrithiol (2,2'-dipyridyl disulphide, DPS), suggesting that the three drugs bind to the same subsite. Enzyme kinetics, competing inhibition experiments, auto-fluorescence binding experiments, and docking suggest that the disulfiram reactive site is Cys592, which has been proposed as a "hinge" located in the flexible active site flap. This study presents the basis for the use of disulfiram as one potential inhibitor to control urease activity.

MgATP-concentration dependence of protection of yeast vacuolar V-ATPase from inactivation by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole supports a bi-site catalytic mechanism of ATP hydrolysis

International Nuclear Information System (INIS)

Milgrom, Elena M.; Milgrom, Yakov M.

2012-01-01

Highlights: ► MgATP protects V-ATPase from inactivation by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole. ► V-ATPase activity saturation with MgATP is not sufficient for complete protection. ► The results support a bi-site catalytic mechanism for V-ATPase. -- Abstract: Catalytic site occupancy of the yeast vacuolar V-ATPase during ATP hydrolysis in the presence of an ATP-regenerating system was probed using sensitivity of the enzyme to inhibition by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). The results show that, regardless of the presence or absence of the proton-motive force across the vacuolar membrane, saturation of V-ATPase activity at increasing MgATP concentrations is accompanied by only partial protection of the enzyme from inhibition by NBD-Cl. Both in the presence and absence of an uncoupler, complete protection of V-ATPase from inhibition by NBD-Cl requires MgATP concentrations that are significantly higher than those expected from the K m values for MgATP. The results are inconsistent with a tri-site model and support a bi-site model for a mechanism of ATP hydrolysis by V-ATPase.

Inhibition of (/sup 3/H)nitrendipine binding by phospholipase A/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Goldman, M.E.; Pisano, J.J.

1985-10-07

Phospholipase A/sub 2/ from several sources inhibited (/sup 3/H)nitrendipine binding to membranes from brain, heart and ileal longitudinal muscle. The enzymes from bee venom and Russell's viper venom were most potent, having IC/sub 50/ values of approximately 5 and 14 ng/ml, respectively, in all three membrane preparations. Inhibition of binding by bee venom phospholipase A/sub 2/ was time- and dose-dependent. Mastoparan, a known facilitator of phospholipase A/sub 2/ enzymatic activity, shifted the bee venom phospholipase A/sub 2/ dose-response curve to the left. Pretreatment of brain membranes with bee venom phospholipase A/sub 2/ (10 ng/ml) for 15 min caused a 2-fold increase in the K/sub d/ without changing the B/sub max/ compared with untreated membranes. Extension of the preincubation period to 30 min caused no further increase in the K/sub d/ but significantly decreased the B/sub max/ to 71% the value for untreated membranes. (/sup 3/H)Nitrendipine, preincubated with bee venom phospholipase A/sub 2/, was recovered and found to be fully active, indicating that the phospholipase A/sub 2/ did not modify the ligand. It is concluded that phospholipase A/sub 2/ acts on the membrane at or near the (/sup 3/H)nitrendipine binding site and that phospholipids play a key role in the interactions of 1,4 dihydropyridine calcium channel antagonists with the dihydropyridine binding site. 33 references, 3 figures, 1 table.

Inhibition of parathyroid hormone release by maitotoxin, a calcium channel activator

International Nuclear Information System (INIS)

Fitzpatrick, L.A.; Yasumoto, T.; Aurbach, G.D.

1989-01-01

Maitotoxin, a toxin derived from a marine dinoflagellate, is a potent activator of voltage-sensitive calcium channels. To further test the hypothesis that inhibition of PTH secretion by calcium is mediated via a calcium channel we studied the effect of maitotoxin on dispersed bovine parathyroid cells. Maitotoxin inhibited PTH release in a dose-dependent fashion, and inhibition was maximal at 1 ng/ml. Chelation of extracellular calcium by EGTA blocked the inhibition of PTH by maitotoxin. Maitotoxin enhanced the effects of the dihydropyridine calcium channel agonist (+)202-791 and increased the rate of radiocalcium uptake in parathyroid cells. Pertussis toxin, which ADP-ribosylates and inactivates a guanine nucleotide regulatory protein that interacts with calcium channels in the parathyroid cell, did not affect the inhibition of PTH secretion by maitotoxin. Maitotoxin, by its action on calcium channels allows entry of extracellular calcium and inhibits PTH release. Our results suggest that calcium channels are involved in the release of PTH. Inhibition of PTH release by maitotoxin is not sensitive to pertussis toxin, suggesting that maitotoxin may act distal to the site interacting with a guanine nucleotide regulatory protein, or maitotoxin could interact with other ions or second messengers to inhibit PTH release

Structure-dependent inhibition of the ETS-family transcription factor PU.1 by novel heterocyclic diamidines

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Munde, Manoj; Wang, Shuo; Kumar, Arvind; Stephens, Chad E.; Farahat, Abdelbasset A.; Boykin, David W.; Wilson, W. David; Poon, Gregory M. K.

2014-01-01

ETS transcription factors mediate a wide array of cellular functions and are attractive targets for pharmacological control of gene regulation. We report the inhibition of the ETS-family member PU.1 with a panel of novel heterocyclic diamidines. These diamidines are derivatives of furamidine (DB75) in which the central furan has been replaced with selenophene and/or one or both of the bridging phenyl has been replaced with benzimidazole. Like all ETS proteins, PU.1 binds sequence specifically to 10-bp sites by inserting a recognition helix into the major groove of a 5′-GGAA-3′ consensus, accompanied by contacts with the flanking minor groove. We showed that diamidines target the minor groove of AT-rich sequences on one or both sides of the consensus and disrupt PU.1 binding. Although all of the diamidines bind to one or both of the expected sequences within the binding site, considerable heterogeneity exists in terms of stoichiometry, site–site interactions and induced DNA conformation. We also showed that these compounds accumulate in live cell nuclei and inhibit PU.1-dependent gene transactivation. This study demonstrates that heterocyclic diamidines are capable of inhibiting PU.1 by targeting the flanking sequences and supports future efforts to develop agents for inhibiting specific members of the ETS family. PMID:24157839

Metabonomics-based analysis of Brachyspira pilosicoli's response to tiamulin reveals metabolic activity despite significant growth inhibition.

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Le Roy, Caroline Ivanne; Passey, Jade Louise; Woodward, Martin John; La Ragione, Roberto Marcello; Claus, Sandrine Paule

2017-06-01

Pathogenic anaerobes Brachyspira spp. are responsible for an increasing number of Intestinal Spirochaetosis (IS) cases in livestock against which few approved treatments are available. Tiamulin is used to treat swine dysentery caused by Brachyspira spp. and recently has been used to handle avian intestinal spirochaetosis (AIS). The therapeutic dose used in chickens requires further evaluation since cases of bacterial resistance to tiamulin have been reported. In this study, we evaluated the impact of tiamulin at varying concentrations on the metabolism of B. pilosicoli using a 1 H-NMR-based metabonomics approach allowing the capture of the overall bacterial metabolic response to antibiotic treatment. Based on growth curve studies, tiamulin impacted bacterial growth even at very low concentration (0.008 μg/mL) although its metabolic activity was barely affected 72 h post exposure to antibiotic treatment. Only the highest dose of tiamulin tested (0.250 μg/mL) caused a major metabolic shift. Results showed that below this concentration, bacteria could maintain a normal metabolic trajectory despite significant growth inhibition by the antibiotic, which may contribute to disease reemergence post antibiotic treatment. Indeed, we confirmed that B. pilosicoli remained viable even after exposition to the highest antibiotic dose. This paper stresses the need to ensure new evaluation of bacterial viability post bacteriostatic exposure such as tiamulin to guarantee treatment efficacy and decrease antibiotic resistance development. Copyright © 2017 Elsevier Ltd. All rights reserved.

Targeting fibroblast growth factor receptor signaling inhibits prostate cancer progression.

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Feng, Shu; Shao, Longjiang; Yu, Wendong; Gavine, Paul; Ittmann, Michael

2012-07-15

Extensive correlative studies in human prostate cancer as well as studies in vitro and in mouse models indicate that fibroblast growth factor receptor (FGFR) signaling plays an important role in prostate cancer progression. In this study, we used a probe compound for an FGFR inhibitor, which potently inhibits FGFR-1-3 and significantly inhibits FGFR-4. The purpose of this study is to determine whether targeting FGFR signaling from all four FGFRs will have in vitro activities consistent with inhibition of tumor progression and will inhibit tumor progression in vivo. Effects of AZ8010 on FGFR signaling and invasion were analyzed using immortalized normal prostate epithelial (PNT1a) cells and PNT1a overexpressing FGFR-1 or FGFR-4. The effect of AZ8010 on invasion and proliferation in vitro was also evaluated in prostate cancer cell lines. Finally, the impact of AZ8010 on tumor progression in vivo was evaluated using a VCaP xenograft model. AZ8010 completely inhibits FGFR-1 and significantly inhibits FGFR-4 signaling at 100 nmol/L, which is an achievable in vivo concentration. This results in marked inhibition of extracellular signal-regulated kinase (ERK) phosphorylation and invasion in PNT1a cells expressing FGFR-1 and FGFR-4 and all prostate cancer cell lines tested. Treatment in vivo completely inhibited VCaP tumor growth and significantly inhibited angiogenesis and proliferation and increased cell death in treated tumors. This was associated with marked inhibition of ERK phosphorylation in treated tumors. Targeting FGFR signaling is a promising new approach to treating aggressive prostate cancer.

Ebselen Reversibly Inhibits Human Glutamate Dehydrogenase at the Catalytic Site.

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Jin, Yanhong; Li, Di; Lu, Shiying; Zhao, Han; Chen, Zhao; Hou, Wei; Ruan, Benfang Helen

Human glutamate dehydrogenase (GDH) plays an important role in neurological diseases, tumor metabolism, and hyperinsulinism-hyperammonemia syndrome (HHS). However, there are very few inhibitors known for human GDH. Recently, Ebselen was reported to crosslink with Escherichia coli GDH at the active site cysteine residue (Cys321), but the sequence alignment showed that the corresponding residue is Ala329 in human GDH. To investigate whether Ebselen could be an inhibitor for human GDH, we cloned and expressed an N-terminal His-tagged human GDH in E. coli. The recombinant human GDH enzyme showed expected properties such as adenosine diphosphate activation and nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate dual recognition. Further, we developed a 2-(3-(2-methoxy-4-nitrophenyl)-2-(4-nitrophenyl)-2H-tetrazol-3-ium-5-yl) benzenesulfonate sodium salt (EZMTT)-based assay for human GDH, which was highly sensitive and is suitable for high-throughput screening for potent GDH inhibitors. In addition, ForteBio binding assays demonstrated that Ebselen is a reversible active site inhibitor for human GDH. Since Ebselen is a multifunctional organoselenium compound in Phase III clinical trials for inflammation, an Ebselen-based GDH inhibitor might be valuable for future drug discovery for HHS patients.

Substrate- and Cofactor-independent Inhibition of Histone Demethylase KDM4C

DEFF Research Database (Denmark)

Leurs, Ulrike; Lohse, Brian; Rand, Kasper Dyrberg

2014-01-01

Inhibition of histone demethylases has within recent years advanced into a new strategy for treating cancer and other diseases. Targeting specific histone demethylases can be challenging as the active sites of KDM1A-B and KDM-4A-D histone demethylases, respectively, are highly conserved. Most...... inhibitors developed up-to-date target either the cofactor- or substrate-binding sites of these enzymes, resulting in a lack of selectivity and off-target effects. This study describes the discovery of the first peptide-based inhibitors of KDM4 histone demethylases that do not share the histone peptide...... sequence, or inhibit through substrate competition. Through screening of DNA-encoded peptide libraries against KDM1 and -4 histone demethylases by phage display, two cyclic peptides targeting the histone demethylase KDM4C were identified and developed as inhibitors by amino acid replacement, truncation...

Downregulation of a tumor suppressor RECK by hypoxia through recruitment of HDAC1 and HIF-1alpha to reverse HRE site in the promoter.

Science.gov (United States)

Lee, Kyung Ju; Lee, Kwang Youl; Lee, You Mie

2010-05-01

Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) is a tumor suppressor and the suppression of RECK is induced by Ras or Her-2/neu oncogenes. However, regulation of RECK under hypoxic microenvironment is largely unknown. Here, we identified that hypoxia significantly downregulates RECK mRNA and protein expression using semiquantitative RT-PCR, real-time RT-PCR and western blot analysis. This repression was reversed by the HDAC inhibitor, trichostatin A (TSA) and HIF-1 inhibitor, YC-1. Hypoxia-induced downregulation of RECK was abolished by knockdown of HDAC1 and HIF-1alpha with respective small interfering RNAs (siRNAs), whereas overexpression of HDAC1 and HIF-1alpha suppressed RECK expression similar to the level under hypoxic conditions. Transfection of a deletion mutant of the second reverse HRE (rHRE2, -2345 to -2333) site of RECK promoter completely removed RECK suppression under hypoxia, indicating that the rHRE2 site is responsible for the inhibition of RECK. Chromatin immunoprecipitation and DNA affinity precipitation assays demonstrated that HDAC1 and HIF-1alpha were recruited to the rHRE2 region of RECK promoter under hypoxic conditions, but the treatment of TSA or YC-1 inhibited their binding to the rHRE2 site. Moreover, TSA and YC-1 inhibited hypoxia-induced cancer cell migration, invasion and MMPs secretion. Taken together, we can conclude that hypoxia induces RECK downregulation through the recruitment of HDAC1 and HIF-1alpha to the rHRE2 site in the promoter and the inhibition of hypoxic RECK silencing would be a therapeutic and preventive target for early tumorigenesis. Copyright 2010 Elsevier B.V. All rights reserved.

PET Imaging of Tissue Factor in Pancreatic Cancer Using 64Cu-Labeled Active Site-Inhibited Factor VII.

Science.gov (United States)

Nielsen, Carsten H; Jeppesen, Troels E; Kristensen, Lotte K; Jensen, Mette M; El Ali, Henrik H; Madsen, Jacob; Wiinberg, Bo; Petersen, Lars C; Kjaer, Andreas

2016-07-01

Tissue factor (TF) is the main initiator of the extrinsic coagulation cascade. However, TF also plays an important role in cancer. TF expression has been reported in 53%-89% of all pancreatic adenocarcinomas, and the expression level of TF has in clinical studies correlated with advanced stage, increased microvessel density, metastasis, and poor overall survival. Imaging of TF expression is of clinical relevance as a prognostic biomarker and as a companion diagnostic for TF-directed therapies currently under clinical development. Factor VII (FVII) is the natural ligand to TF. The purpose of this study was to investigate the possibility of using active site-inhibited FVII (FVIIai) labeled with (64)Cu for PET imaging of TF expression. FVIIai was conjugated to 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) and labeled with (64)Cu ((64)Cu-NOTA-FVIIai). Longitudinal in vivo PET imaging was performed at 1, 4, 15, and 36 h after injection of (64)Cu-NOTA-FVIIai in mice with pancreatic adenocarcinomas (BxPC-3). The specificity of TF imaging with (64)Cu-NOTA-FVIIai was investigated in subcutaneous pancreatic tumor models with different levels of TF expression and in a competition experiment. In addition, imaging of orthotopic pancreatic tumors was performed using (64)Cu-NOTA-FVIIai and PET/MRI. In vivo imaging data were supported by ex vivo biodistribution, flow cytometry, and immunohistochemistry. Longitudinal PET imaging with (64)Cu-NOTA-FVIIai showed a tumor uptake of 2.3 ± 0.2, 3.7 ± 0.3, 3.4 ± 0.3, and 2.4 ± 0.3 percentage injected dose per gram at 1, 4, 15, and 36 h after injection, respectively. An increase in tumor-to-normal-tissue contrast was observed over the imaging time course. Competition with unlabeled FVIIai significantly (P < 0.001) reduced the tumor uptake. The tumor uptake observed in models with different TF expression levels was significantly different from each other (P < 0.001) and was in agreement with

Antiangiogenic and Antitumor Effects of Src Inhibition in Ovarian Carcinoma

Science.gov (United States)

Han, Liz Y.; Landen, Charles N.; Trevino, Jose G.; Halder, Jyotsnabaran; Lin, Yvonne G.; Kamat, Aparna A.; Kim, Tae-Jin; Merritt, William M.; Coleman, Robert L.; Gershenson, David M.; Shakespeare, William C.; Wang, Yihan; Sundaramoorth, Raji; Metcalf, Chester A.; Dalgarno, David C.; Sawyer, Tomi K.; Gallick, Gary E.; Sood, Anil K.

2011-01-01

Src, a nonreceptor tyrosine kinase, is a key mediator for multiple signaling pathways that regulate critical cellular functions and is often aberrantly activated in a number of solid tumors, including ovarian carcinoma. The purpose of this study was to determine the role of activated Src inhibition on tumor growth in an orthotopic murine model of ovarian carcinoma. In vitro studies on HeyA8 and SKOV3ip1 cell lines revealed that Src inhibition by the Src-selective inhibitor, AP23846, occurred within 1 hour and responded in a dose-dependent manner. Furthermore, Src inhibition enhanced the cytotoxicity of docetaxel in both chemosensitive and chemoresistant ovarian cancer cell lines, HeyA8 and HeyA8-MDR, respectively. In vivo, Src inhibition by AP23994, an orally bioavailable analogue of AP23846, significantly decreased tumor burden in HeyA8 (P = 0.02), SKOV3ip1 (P = 0.01), as well as HeyA8-MDR (P < 0.03) relative to the untreated controls. However, the greatest effect on tumor reduction was observed in combination therapy with docetaxel (P < 0.001, P = 0.002, and P = 0.01, for the above models, respectively). Proliferating cell nuclear antigen staining showed that Src inhibition alone (P = 0.02) and in combination with docetaxel (P = 0.007) significantly reduced tumor proliferation. In addition, Src inhibition alone and in combination with docetaxel significantly down-regulated tumoral production of vascular endothelial growth factor and interleukin 8, whereas combination therapy decreased the microvessel density (P = 0.02) and significantly affected vascular permeability (P < 0.05). In summary, Src inhibition with AP23994 has potent antiangiogenic effects and significantly reduces tumor burden in preclinical ovarian cancer models. Thus, Src inhibition may be an attractive therapeutic approach for patients with ovarian carcinoma. PMID:16951177

Engineering D-Amino Acid Containing Collagen Like Peptide at the Cleavage Site of Clostridium histolyticum Collagenase for Its Inhibition.

Directory of Open Access Journals (Sweden)

Punitha Velmurugan

Full Text Available Collagenase is an important enzyme which plays an important role in degradation of collagen in wound healing, cancer metastasis and even in embryonic development. However, the mechanism of this degradation has not yet been completely understood. In the field of biomedical and protein engineering, the design and development of new peptide based materials is of main concern. In the present work an attempt has been made to study the effect of DAla in collagen like peptide (imino-poor region of type I collagen on the structure and stability of peptide against enzyme hydrolysis. Effect of replacement of DAla in the collagen like peptide has been studied using circular dichroic spectroscopy (CD. Our findings suggest that, DAla substitution leads to conformational changes in the secondary structure and favours the formation of polyproline II conformation than its L-counterpart in the imino-poor region of collagen like peptides. Change in the chirality of alanine at the cleavage site of collagenase in the imino-poor region inhibits collagenolytic activity. This may find application in design of peptides and peptidomimics for enzyme-substrate interaction, specifically with reference to collagen and other extra cellular matrix proteins.

Prevalence of Malaria, Dengue, and Chikungunya Significantly Associated with Mosquito Breeding Sites

OpenAIRE

Islam, Mohammad Nazrul; ZulKifle, Mohammad; Sherwani, Arish Mohammad Khan; Ghosh, Susanta Kumar; Tiwari, Satyanarayan

2011-01-01

Objectives: To observe the prevalence of malaria, dengue, and chikungunya and their association with mosquito breeding sites. Methods: The study was observational and analytical. A total of 162 houses and 670 subjects were observed during the study period. One hundred forty-two febrile patients were eligible for the study. After obtaining informed consent from all febrile patients, 140 blood samples were collected to diagnose malaria, dengue, and chikungunya. Larval samples were collected by ...

Inhibition of MMPs by alcohols

Science.gov (United States)

Tezvergil-Mutluay, Arzu; Agee, Kelli A.; Hoshika, Tomohiro; Uchiyama, Toshikazu; Tjäderhane, Leo; Breschi, Lorenzo; Mazzoni, Annalisa; Thompson, Jeremy M.; McCracken, Courtney E.; Looney, Stephen W.; Tay, Franklin R.; Pashley, David H.

2011-01-01

Objectives While screening the activity of potential inhibitors of matrix metalloproteinases (MMPs), due to the limited water solubility of some of the compounds, they had to be solubilized in ethanol. When ethanol solvent controls were run, they were found to partially inhibit MMPs. Thus, the purpose of this study was to compare the MMP-inhibitory activity of a series of alcohols. Methods The possible inhibitory activity of a series of alcohols was measured against soluble rhMMP-9 and insoluble matrix-bound endogenous MMPs of dentin in completely demineralized dentin. Increasing concentrations (0.17, 0.86, 1.71 and 4.28 moles/L) of a homologous series of alcohols (i.e. methanol, ethanol, propanols, butanols, pentanols, hexanols, the ethanol ester of methacrylic acid, heptanols and octanol) were compared to ethanediol, and propanediol by regression analysis to calculate the molar concentration required to inhibit MMPs by 50% (i.e. the IC50). Results Using two different MMP models, alcohols were shown to inhibit rhMMP-9 and the endogenous proteases of dentin matrix in a dose-dependent manner. The degree of MMP inhibition by alcohols increased with chain length up to 4 methylene groups. Based on the molar concentration required to inhibit rhMMP-9 fifty percent, 2-hydroxyethylmethacrylate (HEMA), 3-hexanol, 3-heptanol and 1-octanol gave the strongest inhibition. Significance The results indicate that alcohols with 4 methylene groups inhibit MMPs more effectively than methanol or ethanol. MMP inhibition was inversely related to the Hoy's solubility parameter for hydrogen bonding forces of the alcohols (i.e. to their hydrophilicity). PMID:21676453

Impact of hydrological variations on modeling of peatland CO2 fluxes: Results from the North American Carbon Program site synthesis

Science.gov (United States)

Sulman, Benjamin N.; Desai, Ankur R.; Schroeder, Nicole M.; Ricciuto, Dan; Barr, Alan; Richardson, Andrew D.; Flanagan, Lawrence B.; Lafleur, Peter M.; Tian, Hanqin; Chen, Guangsheng; Grant, Robert F.; Poulter, Benjamin; Verbeeck, Hans; Ciais, Philippe; Ringeval, Bruno; Baker, Ian T.; Schaefer, Kevin; Luo, Yiqi; Weng, Ensheng

2012-03-01

Northern peatlands are likely to be important in future carbon cycle-climate feedbacks due to their large carbon pools and vulnerability to hydrological change. Use of non-peatland-specific models could lead to bias in modeling studies of peatland-rich regions. Here, seven ecosystem models were used to simulate CO2fluxes at three wetland sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor,sphagnum-dominated bog, over periods between 1999 and 2007. Models consistently overestimated mean annual gross ecosystem production (GEP) and ecosystem respiration (ER) at all three sites. Monthly flux residuals (simulated - observed) were correlated with measured water table for GEP and ER at the two fen sites, but were not consistently correlated with water table at the bog site. Models that inhibited soil respiration under saturated conditions had less mean bias than models that did not. Modeled diurnal cycles agreed well with eddy covariance measurements at fen sites, but overestimated fluxes at the bog site. Eddy covariance GEP and ER at fens were higher during dry periods than during wet periods, while models predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP did not depend on water table, while simulated GEP was higher during wet periods. Carbon cycle modeling in peatland-rich regions could be improved by incorporating wetland-specific hydrology and by inhibiting GEP and ER under saturated conditions. Bogs and fens likely require distinct plant and soil parameterizations in ecosystem models due to differences in nutrients, peat properties, and plant communities.

Stereoselective inhibition of thromboxane-induced coronary vasoconstriction by 1,4-dihydropyridine calcium channel antagonists

International Nuclear Information System (INIS)

Eltze, M.; Boer, R.; Sanders, K.H.; Boss, H.; Ulrich, W.R.; Flockerzi, D.

1990-01-01

The biological activity of the (+)-S- and (-)-R-enantiomers of niguldipine, of the (-)-S- and (+)-R-enantiomers of felodipine and nitrendipine, and of rac-nisoldipine and rac-nimodipine was investigated in vitro and in vivo. Inhibition of coronary vasoconstriction due to the thromboxane A2 (TxA2)-mimetic U-46619 in guinea pig Langendorff hearts, displacement of (+)-[ 3 H]isradipine from calcium channel binding sites of guinea pig skeletal muscle T-tubule membranes, and blood pressure reduction in spontaneously hypertensive rats were determined. The enantiomers were obtained by stereoselective synthesis. Cross-contamination was less than 0.5% for both S- and R-enantiomers of niguldipine and nitrendipine and less than 1% for those of felodipine. From the doses necessary for a 50% inhibition of coronary vasoconstriction, stereoselectivity ratios for (+)-(S)-/(-)-(R)-niguldipine, (-)-(S)-/(+)-(R)-felodipine, and (-)-(S)-/(+)-(R)-nitrendipine of 28, 13, and 7, respectively, were calculated. The potency ratio rac-nisoldipine/rac-nimodipine was 3.5. Ratios obtained from binding experiments and antihypertensive activity were (+)-(S)-/(-)-(R)-niguldipine = 45 and 35, (-)-(S)-/(+)-(R)-felodipine = 12 and 13, (-)-(S)-/(+)-(R)-nitrendipine = 8 and 8, and rac-nisoldipine/rac-nimodipine = 8 and 7, respectively. Highly significant correlations were found between the in vitro potency of the substances to prevent U-46619-induced coronary vasoconstriction and their affinity for calcium channel binding sites as well as their antihypertensive activity

Calcium Occupancy of N-terminal Sites within Calmodulin Induces Inhibition of the Ryanodine Receptor Calcium Release Channel

Energy Technology Data Exchange (ETDEWEB)

Boschek, Curt B; Jones, Terry E; Squier, Thomas C; Bigelow, Diana J

2007-08-01

Calmodulin (CaM) regulates calcium release from intracellular stores in skeletal muscle through its association with the ryanodine receptor (RyR1) calcium release channel, where CaM association enhances channel opening at resting calcium levels and its closing at micromolar calcium levels associated with muscle contraction. A high-affinity CaM-binding sequence (RyRp) has been identified in RyR1, which corresponds to a 30-residue sequence (i.e., K3614 – N3643) located within the central portion of the primary sequence. However, it is currently unclear whether the identified CaM-binding sequence a) senses calcium over the physiological range of calcium-concentrations associated with RyR1 regulation or b) plays a structural role unrelated to the calcium-dependent modulation of RyR1 function. Therefore, we have measured the calcium-dependent activation of the individual domains of CaM in association with RyRp and their relationship to the CaM-dependent regulation of RyR1. These measurements utilize an engineered CaM, permitting the site-specific incorporation of N-(1-pyrene) maleimide at either T34C (PyN-CaM) or T110C (PyC-CaM) in the N- and C-domains, respectively. Consistent with prior measurements, we observe a high-affinity association between both apo- and calcium-activated CaM and RyRp. Upon association with RyRp, fluorescence changes in PyN-CaM or PyC-CaM permit the measurement of the calcium-activation of these individual domains. Fluorescence changes upon calcium-activation of PyC-CaM in association with RyRp are indicative of high-affinity calcium-dependent activation of the C-terminal domain of CaM bound to RyRp at resting calcium levels and the activation of the N-terminal domain at levels of calcium associated cellular activation. In comparison, occupancy of calcium-binding sites in the N-domain of CaM mirrors the calcium-dependence of RyR1 inhibition observed at activating calcium levels, where [Ca]1/2 = 4.3 0.4 μM, suggesting a direct regulation of Ry

In vitro evaluation of single- and multi-strain probiotics: Inter-species inhibition between probiotic strains, and inhibition of pathogens.

Science.gov (United States)

Chapman, C M C; Gibson, G R; Rowland, I

2012-08-01

Many studies comparing the effects of single- and multi-strain probiotics on pathogen inhibition compare treatments with different concentrations. They also do not examine the possibility of inhibition between probiotic strains with a mixture. We tested the ability of 14 single-species probiotics to inhibit each other using a cross-streak assay, and agar spot test. We then tested the ability of 15 single-species probiotics and 5 probiotic mixtures to inhibit Clostridium difficile, Escherichia coli and S. typhimurium, using the agar spot test. Testing was done with mixtures created in two ways: one group contained component species incubated together, the other group of mixtures was made using component species which had been incubated separately, equalised to equal optical density, and then mixed in equal volumes. Inhibition was observed for all combinations of probiotics, suggesting that when used as such there may be inhibition between probiotics, potentially reducing efficacy of the mixture. Significant inter-species variation was seen against each pathogen. When single species were tested against mixtures, the multi-species preparations displayed significantly (p probiotic species will inhibit each other when incubated together in vitro, in many cases a probiotic mixture was more effective at inhibiting pathogens than its component species when tested at approximately equal concentrations of biomass. This suggests that using a probiotic mixture might be more effective at reducing gastrointestinal infections, and that creating a mixture using species with different effects against different pathogens may have a broader spectrum of action that a single provided by a single strain. Copyright © 2012 Elsevier Ltd. All rights reserved.

Quantitative PET Imaging of Tissue Factor Expression Using 18F-Labeled Active Site-Inhibited Factor VII.

Science.gov (United States)

Nielsen, Carsten H; Erlandsson, Maria; Jeppesen, Troels E; Jensen, Mette M; Kristensen, Lotte K; Madsen, Jacob; Petersen, Lars C; Kjaer, Andreas

2016-01-01

Tissue factor (TF) is upregulated in many solid tumors, and its expression is linked to tumor angiogenesis, invasion, metastasis, and prognosis. A noninvasive assessment of tumor TF expression status is therefore of obvious clinical relevance. Factor VII is the natural ligand to TF. Here we report the development of a new PET tracer for specific imaging of TF using an (18)F-labeled derivative of factor VII. Active site-inhibited factor VIIa (FVIIai) was obtained by inactivation with phenylalanine-phenylalanine-arginine-chloromethyl ketone. FVIIai was radiolabeled with N-succinimidyl 4-(18)F-fluorobenzoate and purified. The corresponding product, (18)F-FVIIai, was injected into nude mice with subcutaneous human pancreatic xenograft tumors (BxPC-3) and investigated using small-animal PET/CT imaging 1, 2, and 4 h after injection. Ex vivo biodistribution was performed after the last imaging session, and tumor tissue was preserved for molecular analysis. A blocking experiment was performed in a second set of mice. The expression pattern of TF in the tumors was visualized by immunohistochemistry and the amount of TF in tumor homogenates was measured by enzyme-linked immunosorbent assay and correlated with the uptake of (18)F-FVIIai in the tumors measured in vivo by PET imaging. The PET images showed high uptake of (18)F-FVIIai in the tumor regions, with a mean uptake of 2.5 ± 0.3 percentage injected dose per gram (%ID/g) (mean ± SEM) 4 h after injection of 7.3-9.3 MBq of (18)F-FVIIai and with an average maximum uptake in the tumors of 7.1 ± 0.7 %ID/g at 4 h. In comparison, the muscle uptake was 0.2 ± 0.01 %ID/g at 4 h. At 4 h, the tumors had the highest uptake of any organ. Blocking with FVIIai significantly reduced the uptake of (18)F-FVIIai from 2.9 ± 0.1 to 1.4 ± 0.1 %ID/g (P < 0.001). The uptake of (18)F-FVIIai measured in vivo by PET imaging correlated (r = 0.72, P < 0.02) with TF protein level measured ex vivo. (18)F-FVIIai is a promising PET tracer for

Triazoles inhibit cholesterol export from lysosomes by binding to NPC1.

Science.gov (United States)

Trinh, Michael N; Lu, Feiran; Li, Xiaochun; Das, Akash; Liang, Qiren; De Brabander, Jef K; Brown, Michael S; Goldstein, Joseph L

2017-01-03

Niemann-Pick C1 (NPC1), a membrane protein of lysosomes, is required for the export of cholesterol derived from receptor-mediated endocytosis of LDL. Lysosomal cholesterol export is reportedly inhibited by itraconazole, a triazole that is used as an antifungal drug [Xu et al. (2010) Proc Natl Acad Sci USA 107:4764-4769]. Here we show that posaconazole, another triazole, also blocks cholesterol export from lysosomes. We prepared P-X, a photoactivatable cross-linking derivative of posaconazole. P-X cross-linked to NPC1 when added to intact cells. Cross-linking was inhibited by itraconazole but not by ketoconazole, an imidazole that does not block cholesterol export. Cross-linking of P-X was also blocked by U18666A, a compound that has been shown to bind to NPC1 and inhibit cholesterol export. P-X also cross-linked to purified NPC1 that was incorporated into lipid bilayer nanodiscs. In this in vitro system, cross-linking of P-X was inhibited by itraconazole, but not by U18666A. P-X cross-linking was not prevented by deletion of the N-terminal domain of NPC1, which contains the initial binding site for cholesterol. In contrast, P-X cross-linking was reduced when NPC1 contained a point mutation (P691S) in its putative sterol-sensing domain. We hypothesize that the sterol-sensing domain has a binding site that can accommodate structurally different ligands.

An evaluation of the inhibition of human butyrylcholinesterase and acetylcholinesterase by the organophosphate chlorpyrifos oxon

International Nuclear Information System (INIS)

Shenouda, Josephine; Green, Paula; Sultatos, Lester

2009-01-01

Acetylcholinesterase (EC 3.1.1.7) and butyrylcholinesterase (EC 3.1.1.8) are enzymes that belong to the superfamily of α/β-hydrolase fold proteins. While they share many characteristics, they also possess many important differences. For example, whereas they have about 54% amino acid sequence identity, the active site gorge of acetylcholinesterase is considerably smaller than that of butyrylcholinesterase. Moreover, both have been shown to display simple and complex kinetic mechanisms, depending on the particular substrate examined, the substrate concentration, and incubation conditions. In the current study, incubation of butyrylthiocholine in a concentration range of 0.005-3.0 mM, with 317 pM human butyrylcholinesterase in vitro, resulted in rates of production of thiocholine that were accurately described by simple Michaelis-Menten kinetics, with a K m of 0.10 mM. Similarly, the inhibition of butyrylcholinesterase in vitro by the organophosphate chlorpyrifos oxon was described by simple Michaelis-Menten kinetics, with a k i of 3048 nM -1 h -1 , and a K D of 2.02 nM. In contrast to inhibition of butyrylcholinesterase, inhibition of human acetylcholinesterase by chlorpyrifos oxon in vitro followed concentration-dependent inhibition kinetics, with the k i increasing as the inhibitor concentration decreased. Chlorpyrifos oxon concentrations of 10 and 0.3 nM gave k i s of 1.2 and 19.3 nM -1 h -1 , respectively. Although the mechanism of concentration-dependent inhibition kinetics is not known, the much smaller, more restrictive active site gorge of acetylcholinesterase almost certainly plays a role. Similarly, the much larger active site gorge of butyrylcholinesterase likely contributes to its much greater reactivity towards chlorpyrifos oxon, compared to acetylcholinesterase.

ETMB-RBF: discrimination of metal-binding sites in electron transporters based on RBF networks with PSSM profiles and significant amino acid pairs.

Science.gov (United States)

Ou, Yu-Yen; Chen, Shu-An; Wu, Sheng-Cheng

2013-01-01

Cellular respiration is the process by which cells obtain energy from glucose and is a very important biological process in living cell. As cells do cellular respiration, they need a pathway to store and transport electrons, the electron transport chain. The function of the electron transport chain is to produce a trans-membrane proton electrochemical gradient as a result of oxidation-reduction reactions. In these oxidation-reduction reactions in electron transport chains, metal ions play very important role as electron donor and acceptor. For example, Fe ions are in complex I and complex II, and Cu ions are in complex IV. Therefore, to identify metal-binding sites in electron transporters is an important issue in helping biologists better understand the workings of the electron transport chain. We propose a method based on Position Specific Scoring Matrix (PSSM) profiles and significant amino acid pairs to identify metal-binding residues in electron transport proteins. We have selected a non-redundant set of 55 metal-binding electron transport proteins as our dataset. The proposed method can predict metal-binding sites in electron transport proteins with an average 10-fold cross-validation accuracy of 93.2% and 93.1% for metal-binding cysteine and histidine, respectively. Compared with the general metal-binding predictor from A. Passerini et al., the proposed method can improve over 9% of sensitivity, and 14% specificity on the independent dataset in identifying metal-binding cysteines. The proposed method can also improve almost 76% sensitivity with same specificity in metal-binding histidine, and MCC is also improved from 0.28 to 0.88. We have developed a novel approach based on PSSM profiles and significant amino acid pairs for identifying metal-binding sites from electron transport proteins. The proposed approach achieved a significant improvement with independent test set of metal-binding electron transport proteins.

Osthole inhibits bone metastasis of breast cancer

OpenAIRE

Wu, Chunyu; Sun, Zhenping; Guo, Baofeng; Ye, Yiyi; Han, Xianghui; Qin, Yuenong; Liu, Sheng

2017-01-01

Bone is one of the most common sites for breast cancer metastasis, which greatly contributes to patient morbidity and mortality. Osthole, a major extract from Cnidium monnieri (L.), exhibits many biological and pharmacological activities, however, its potential as a therapeutic agent in the treatment of breast cancer bone metastases remain poorly understood. In this study, we set out to investigate whether osthole could inhibit breast cancer metastasis to bone in mice and clarified the potent...

Desleucyl-Oritavancin with a Damaged d-Ala-d-Ala Binding Site Inhibits the Transpeptidation Step of Cell-Wall Biosynthesis in Whole Cells of Staphylococcus aureus.

Science.gov (United States)

Kim, Sung Joon; Singh, Manmilan; Sharif, Shasad; Schaefer, Jacob

2017-03-14

We have used solid-state nuclear magnetic resonance to characterize the exact nature of the dual mode of action of oritavancin in preventing cell-wall assembly in Staphylococcus aureus. Measurements performed on whole cells labeled selectively in vivo have established that des-N-methylleucyl-N-4-(4-fluorophenyl)benzyl-chloroeremomycin, an Edman degradation product of [ 19 F]oritavancin, which has a damaged d-Ala-d-Ala binding aglycon, is a potent inhibitor of the transpeptidase activity of cell-wall biosynthesis. The desleucyl drug binds to partially cross-linked peptidoglycan by a cleft formed between the drug aglycon and its biphenyl hydrophobic side chain. This type of binding site is present in other oritavancin-like glycopeptides, which suggests that for these drugs a similar transpeptidase inhibition occurs.

Design, synthesis and biological activity of novel donepezil derivatives bearing N-benzyl pyridinium moiety as potent and dual binding site acetylcholinesterase inhibitors.

Science.gov (United States)

Lan, Jin-Shuai; Zhang, Tong; Liu, Yun; Yang, Jing; Xie, Sai-Sai; Liu, Jing; Miao, Ze-Yang; Ding, Yue

2017-06-16

A series of new donepezil derivatives were designed synthesized and evaluated as multifunctional cholinesterase inhibitors against Alzheimer's disease (AD). In vitro studies showed that most of them exhibited significant potency to inhibit acetylcholinesterase and self-induced β-amyloid (Aβ) aggregation, and moderate antioxidant activity. Especially, compound 5b presented the greatest ability to inhibit cholinesterase (IC 50 , 1.9 nM for eeAChE and 0.8 nM for hAChE), good inhibition of Aβ aggregation (53.7% at 20 μM) and good antioxidant activity (0.54 trolox equivalents). Kinetic and molecular modeling studies indicated that compound 5b was a mixed-type inhibitor, binding simultaneously to the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. In addition, compound 5b could reduce PC12 cells death induced by oxidative stress and Aβ (1-42). Moreover, in vivo experiments showed that compound 5b was nontoxic and tolerated at doses up to 2000 mg/kg. These results suggested that compound 5b might be an excellent multifunctional agent for AD treatment. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Expansion of access tunnels and active-site cavities influence activity of haloalkane dehalogenases in organic cosolvents.

Science.gov (United States)

Stepankova, Veronika; Khabiri, Morteza; Brezovsky, Jan; Pavelka, Antonin; Sykora, Jan; Amaro, Mariana; Minofar, Babak; Prokop, Zbynek; Hof, Martin; Ettrich, Rudiger; Chaloupkova, Radka; Damborsky, Jiri

2013-05-10

The use of enzymes for biocatalysis can be significantly enhanced by using organic cosolvents in the reaction mixtures. Selection of the cosolvent type and concentration range for an enzymatic reaction is challenging and requires extensive empirical testing. An understanding of protein-solvent interaction could provide a theoretical framework for rationalising the selection process. Here, the behaviour of three model enzymes (haloalkane dehalogenases) was investigated in the presence of three representative organic cosolvents (acetone, formamide, and isopropanol). Steady-state kinetics assays, molecular dynamics simulations, and time-resolved fluorescence spectroscopy were used to elucidate the molecular mechanisms of enzyme-solvent interactions. Cosolvent molecules entered the enzymes' access tunnels and active sites, enlarged their volumes with no change in overall protein structure, but surprisingly did not act as competitive inhibitors. At low concentrations, the cosolvents either enhanced catalysis by lowering K(0.5) and increasing k(cat), or caused enzyme inactivation by promoting substrate inhibition and decreasing k(cat). The induced activation and inhibition of the enzymes correlated with expansion of the active-site pockets and their occupancy by cosolvent molecules. The study demonstrates that quantitative analysis of the proportions of the access tunnels and active-sites occupied by organic solvent molecules provides the valuable information for rational selection of appropriate protein-solvent pair and effective cosolvent concentration. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inhibition of DNA repair in ultraviolet-irradiated human cells by hydroxyurea

International Nuclear Information System (INIS)

Francis, A.A.; Carrier, W.L.; Smith, D.P.; Regan, J.D.; Blevins, R.D.

1979-01-01

The effect on DNA repair in ultraviolet-irradiated human skin fibroblasts by hydroxyurea has been examined in this study using three independent methods for measuring DNA repair: the 5-bromodeoxyuridine photolysis assay which measures DNA repair replication, chromatographic measurement of thymine-containing dimers, and measurement of specific ultraviolet-endonuclease-sensitive sites in irradiated DNA. Little effect on hydroxyurea was observed at the concentration of 2mM, which is often used to inhibit semiconservative DNA synthesis; however, 10 mM hydroxyurea resulted in marked inhibition (65-70%) of excision repair. This inhibition was accompanied by a possible doubling in the size of the repaired region. The accumulation of large numbers of single-strand breaks following ultraviolet irradiation and hydroxyurea incubation seen by other investigators was not observed with the normal skin fibroblasts used in this study. A comparison of hydroxyurea effects on the different DNA repair assays indicates inhibition of one step in DNA repair also results in varying degrees of inhibition of other steps as well. (Auth.)

Inhibition of DNA repair in ultraviolet-irradiated human cells by hydroxyurea

Energy Technology Data Exchange (ETDEWEB)

Francis, A.A. (Oak Ridge National Lab., TN); Blevins, R.D.; Carrier, W.L.; Smith, D.P.; Regan, J.D.

1979-01-01

The effect on DNA repair in ultraviolet-irradiated human skin fibroblasts by hydroxyurea has been examined in this study using three independent methods for measuring DNA repair: the 5-bromodeoxyuridine photolysis assay which measures DNA repair replication, chromatographic measurement of thymine-containing dimers, and measurement of specific ultraviolet-endonuclease-sensitive sites in irradiated DNA. Little effect of hydroxyurea was observed at the concentration of 2 mM, which is often used to inhibit semiconservative DNA synthesis; however, 10 mM hydroxyurea resulted in marked inhibition (65 to 70%) of excision repair. This inhibition was accompanied by a possible doubling in the size of the repaired region. The accumulation of large numbers of single-strand breaks following ultraviolet irradiation and hydroxyurea incubation seen by other investigators was not observed with the normal skin fibroblasts used in this study. A comparison of hydroxyurea effects on the different DNA repair assays indicates inhibition of one step in DNA repair also results in varying degrees of inhibition of other steps as well.

α-Iso-Cubebene Inhibits PDGF-Induced Vascular Smooth Muscle Cell Proliferation by Suppressing Osteopontin Expression

Science.gov (United States)

Jang, Min A.; Lee, Seung Jin; Baek, Seung Eun; Park, So Youn; Choi, Young Whan; Kim, Chi Dae

2017-01-01

α-Iso-cubebene (ICB) is a dibenzocyclooctadiene lignin contained in Schisandra chinensis (SC), a well-known medicinal herb that ameliorates cardiovascular symptoms. Thus, we examined the effect of ICB on vascular smooth muscle cell (VSMC) proliferation, a key feature of diverse vascular diseases. When VSMCs primary cultured from rat thoracic aorta were stimulated with PDGF (1–10 ng/ml), cell proliferation and osteopontin (OPN) expression were concomitantly up-regulated, but these effects were attenuated when cells were treated with MPIIIB10, a neutralizing monoclonal antibody for OPN. In aortic tissues exposed to PDGF, sprouting VSMC numbers increased, which was attenuated in tissues from OPN-deficient mice. Furthermore, VSMC proliferation and OPN expression induced by PDGF were attenuated dose-dependently by ICB (10 or 30 μg/ml). Reporter assays conducted using OPN promoter-luciferase constructs showed that the promoter region 538–234 bp of the transcription start site was responsible for transcriptional activity enhancement by PDGF, which was significantly inhibited by ICB. Putative binding sites for AP-1 and C/EBPβ in the indicated promoter region were suggested by TF Search, and increased binding of AP-1 and C/EBPβ in PDGF-treated VSMCs was demonstrated using a ChIP assay. The increased bindings of AP-1 and C/EBPβ into OPN promoter were attenuated by ICB. Moreover, the PDGF-induced expression of OPN was markedly attenuated in VSMCs transfected with siRNA for AP-1 and C/EBPβ. These results indicate that ICB inhibit VSMC proliferation by inhibiting the AP-1 and C/EBPβ signaling pathways and thus downregulating OPN expression. PMID:28114367

Kindergarteners' self-reported social inhibition and observed social reticence: moderation by adult-reported social inhibition and social anxiety disorder symptoms.

Science.gov (United States)

Kiel, Elizabeth J; Buss, Kristin A; Molitor, Joseph G

2015-04-01

Prevention of later anxiety problems would best be accomplished by identifying at-risk children early in development. For example, children who develop Social Anxiety Disorder (SAD) may show social withdrawal in the form of social inhibition (i.e., shyness with unfamiliar adults and peers) at school entry. Although the use of children's perceptions of their own social inhibition would provide insight into early risk, the utility of young children's self-reports remains unclear. The current study examined whether children deemed more extreme on social inhibition or social anxiety by adult report provided self-report of social inhibition that related to observed social reticence in the laboratory. Participants included 85 kindergarten children (36 female, 49 male), their parents, and their teachers. Moderation analyses revealed that children's self-reported social inhibition related significantly to observed social reticence under the conditions of high parent-reported social inhibition, high teacher-reported social inhibition, and high SAD symptoms. These results suggest that the most inhibited children are aware of their behavior and can report it in a meaningfully way as young as kindergarten age.

Acetylcholinesterase-Inhibiting Activity of Salicylanilide N-Alkylcarbamates and Their Molecular Docking

Directory of Open Access Journals (Sweden)

Josef Jampilek

2012-08-01

Full Text Available A series of twenty-five novel salicylanilide N-alkylcarbamates were investigated as potential acetylcholinesterase inhibitors. The compounds were tested for their ability to inhibit acetylcholinesterase (AChE from electric eel (Electrophorus electricus L.. Experimental lipophilicity was determined, and the structure-activity relationships are discussed. The mode of binding in the active site of AChE was investigated by molecular docking. All the discussed compounds expressed significantly higher AChE inhibitory activity than rivastigmine and slightly lower than galanthamine. Disubstitution by chlorine in C'_(3,4 of the aniline ring and the optimal length of hexyl-undecyl alkyl chains in the carbamate moiety provided the most active AChE inhibitors. Monochlorination in C'₍₄ exhibited slightly more effective AChE inhibitors than in C'₍₃. Generally it can be stated that compounds with higher lipophilicity showed higher inhibition, and the activity of the compounds is strongly dependent on the length of the N-alkyl chain.

The Italian forest sites of FunDivEUROPE: a new FP7 project on the functional significance of forest biodiversity in Europe

Directory of Open Access Journals (Sweden)

Bussotti F

2012-12-01

Full Text Available The Italian forest sites of FunDivEUROPE: a new FP7 project on the functional significance of forest biodiversity in Europe. FunDivEUROPE is a new project aiming at a deeper understanding of the role of forest diversity on ecosystem functions and service provisioning for society. This project combines three scientific platforms: experimental, exploratory and inventory. The exploratory platform is based on the observation of a broad range of properties, traits and ecological processes on a network of ca. 240 natural forest sites representing a gradient of tree species diversity in six focal regions of Europe (Spain, Italy, Germany, Poland, Finland and Romania. The Italian sites are located on the hills of central and Southern Tuscany and represent the category “thermophilous deciduous forest”. Almost one year of fieldwork was needed to select and characterize 36 plots measuring 30 x 30 m. Selection was based on criteria concerning tree mixtures and richness, structural parameters and main environmental variables. The main features of these sites are synthetically presented in this paper together with a short description of the project structure and scope. The aim is also to enhance dissemination of the potential implications for a sustainable forest management in Italy.

Irreversible inhibition of RANK expression as a possible mechanism for IL-3 inhibition of RANKL-induced osteoclastogenesis

Energy Technology Data Exchange (ETDEWEB)

Khapli, Shruti M.; Tomar, Geetanjali B.; Barhanpurkar, Amruta P.; Gupta, Navita; Yogesha, S.D.; Pote, Satish T. [National Center for Cell Science, University of Pune Campus, Pune 411 007 (India); Wani, Mohan R., E-mail: mohanwani@nccs.res.in [National Center for Cell Science, University of Pune Campus, Pune 411 007 (India)

2010-09-03

Research highlights: {yields} IL-3 inhibits receptor activator of NF-{kappa}B ligand (RANKL)-induced osteoclastogenesis. {yields} IL-3 inhibits RANKL-induced JNK activation. {yields} IL-3 down-regulates expression of c-Fos and NFATc1 transcription factors. {yields} IL-3 down-regulates RANK expression posttranscriptionally and irreversibly. {yields} IL-3 inhibits in vivo RANK expression. -- Abstract: IL-3, a cytokine secreted by activated T lymphocytes, stimulates the proliferation, differentiation and survival of pluripotent hematopoietic stem cells. In this study, we investigated the mechanism of inhibitory action of IL-3 on osteoclast differentiation. We show here that IL-3 significantly inhibits receptor activator of NF-{kappa}B (RANK) ligand (RANKL)-induced activation of c-Jun N-terminal kinase (JNK). IL-3 down-regulates expression of c-Fos and nuclear factor of activated T cells (NFATc1) transcription factors. In addition, IL-3 down-regulates RANK expression posttranscriptionally in both purified osteoclast precursors and whole bone marrow cells. Furthermore, the inhibitory effect of IL-3 on RANK expression was irreversible. Interestingly, IL-3 inhibits in vivo RANK expression in mice. Thus, we provide the first evidence that IL-3 irreversibly inhibits RANK expression that results in inhibition of important signaling molecules induced by RANKL.

Irreversible inhibition of RANK expression as a possible mechanism for IL-3 inhibition of RANKL-induced osteoclastogenesis

International Nuclear Information System (INIS)

Khapli, Shruti M.; Tomar, Geetanjali B.; Barhanpurkar, Amruta P.; Gupta, Navita; Yogesha, S.D.; Pote, Satish T.; Wani, Mohan R.

2010-01-01

Research highlights: → IL-3 inhibits receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis. → IL-3 inhibits RANKL-induced JNK activation. → IL-3 down-regulates expression of c-Fos and NFATc1 transcription factors. → IL-3 down-regulates RANK expression posttranscriptionally and irreversibly. → IL-3 inhibits in vivo RANK expression. -- Abstract: IL-3, a cytokine secreted by activated T lymphocytes, stimulates the proliferation, differentiation and survival of pluripotent hematopoietic stem cells. In this study, we investigated the mechanism of inhibitory action of IL-3 on osteoclast differentiation. We show here that IL-3 significantly inhibits receptor activator of NF-κB (RANK) ligand (RANKL)-induced activation of c-Jun N-terminal kinase (JNK). IL-3 down-regulates expression of c-Fos and nuclear factor of activated T cells (NFATc1) transcription factors. In addition, IL-3 down-regulates RANK expression posttranscriptionally in both purified osteoclast precursors and whole bone marrow cells. Furthermore, the inhibitory effect of IL-3 on RANK expression was irreversible. Interestingly, IL-3 inhibits in vivo RANK expression in mice. Thus, we provide the first evidence that IL-3 irreversibly inhibits RANK expression that results in inhibition of important signaling molecules induced by RANKL.

Cre recombinase activity is inhibited in vivo but not ex vivo by a mutation in the asymmetric spacer region of the distal loxP site.

Science.gov (United States)

Arguello, Tania; Moraes, Carlos T

2015-11-01

The cre/loxP recombination system is a valuable tool used to generate tissue specific genomic rearrangements in mouse models. The deletion of a region of interest flanked by two loxP sites is accomplished by the recombinase (cre) enzyme, which binds to the inverted repeat segments of two loxP sites and recognition of a conserved TA sequence in the asymmetric central spacer region "ATAACTTCGTATA -NNNTANNN-TATACGAAGTTAT. In vivo, we found that a single T to C mutation at position 4 of the central spacer region in the distal (3') loxP site, completely inhibited the recombination reaction in two conditional mouse models. These mice were generated using a mitochondrial methionyl-tRNA formyltransferase (Mtfmt) gene targeted construct and cre transgene under the control of tissue-specific promoters: calcium/calmodulin-dependent kinase II alpha (Camk2a-cre) and myosin light polypeptide 1 (Myl1-cre). Surprisingly, transient transfection of a plasmid expressing cre in dermal fibroblasts derived from the same mutant floxed Mtfmt((loxP/loxP)) mice line, successfully deleted the region of interest. This study demonstrates the sequence specificity required in vivo, the possibility of bypassing this limitation by expressing high levels of cre recombinase ex vivo and raises concerns related to the quality control of large scale production of gene targeted constructs and mice. genesis 53:695-700, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Alkylation of amide linkages and cleavage of the C chain in the enzyme-activated-substrate inhibition of alpha-chymotrypsin with N-nitrosamides

International Nuclear Information System (INIS)

Donadio, S.; Perks, H.M.; Tsuchiya, K.; White, E.H.

1985-01-01

Active-site-directed N-nitrosamides inhibit alpha-chymotrypsin through an enzyme-activated-substrate mechanism. In this work, the activation results in the release--in the active site--of benzyl carbonium ions, which alkylate and inhibit the enzyme. The final ratio of benzyl groups to enzyme molecules is 1.0, but the alkyl groups are scattered over a number of sites. Reduction and alkylation of the inhibited enzyme generate peptides insoluble in most media. Guanidine hydrochloride at 6 M proved a good solvent, and its use as an eluant on G-75 Sephadex permitted separation of the peptides. In the case of 14 C-labeled enzyme, such an approach has shown that all of the alkylation occurs on the C chain of the enzyme, the chain of which the active site is constructed. Chemical modification of the peptides with ethylenediamine and N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide rendered them soluble in dilute acid, permitting high-performance liquid chromatographic separation. Model studies have shown that the benzyl carbonium ions are highly reactive, alkylating amide linkages at both oxygen and nitrogen. Chromatography of this mixture and also 13 C NMR spectroscopy of the intact inhibited enzyme have shown that three major N-alkylations have occurred. Tryptic digestion of the C chain of chymotrypsin, which contains all of the alkylation sites, provides evidence that the stable N sites are principally located between residue 216 and residue 230

Adenoviral gene transfer of angiostatic ATF-BPTI inhibits tumour growth

International Nuclear Information System (INIS)

Lefesvre, Pierre; Attema, Joline; Bekkum, Dirk van

2002-01-01

The outgrowth of new vessels – angiogenesis – in the tumour mass is considered to be a limiting factor of tumour growth. To inhibit the matrix lysis that is part of the tumour angiogenesis, we employed the chimeric protein mhATF-BPTI, composed of the receptor binding part of the urokinase (ATF) linked to an inhibitor of plasmin (BPTI). For delivery, recombinant adenovirus encoding the transgene of interest was injected intravenously or locally into the tumour. The anti tumour effect of this compound was compared to that of human endostatin and of mhATF alone in two different rat bronchial carcinomas growing either as subcutaneous implants or as metastases. Significant inhibition of the tumour growth and decrease of the number of lung metastasis was achieved when the concentration of mhATF-BPTI at the tumour site was above 400 of ng / g tissue. This concentration could be achieved via production by the liver, only if permissive to the recombinant adenovirus. When the tumour cells could be transduced, local delivery of the vector was enough to obtain a response. In the case of metastasis, the capacity of the lung tissue to concentrate the encoded protein was essential to reach the required therapeutic levels. Further, endostatin or mhATF could not reproduce the effects of mhATF-BPTI, at similar concentrations (mhATF) and even at 10-fold higher concentration (endostatin). The ATF-BPTI was shown to inhibit tumour growth of different rat lung tumours when critical concentration was reached. In these tumour models, endostatin or ATF induce almost no tumour response

Photolytic inhibition and labeling of proteins with aryl diazonium compounds

International Nuclear Information System (INIS)

Tometsko, A.M.; Turula, J.; Comstock, J.

1978-01-01

In the course of preparing aryl azide derivatives for use as photoprobes, we have observed significant light sensitivity in the precursor aryl diazonium compounds. The photosensitive properties of this class of compounds are of interest since they will seek out cationic binding sites in biological targets, and can be employed to inhibit complementary targets at acid pH. The relationship between photolytic change in the structure of diazonium compounds and the corresponding change in function of a biological target are presented. Experiments are described in which the dark and light sensitive properties of a model diazonium compound, diazobenzene sulfonate (DBS), were determined. The ultraviolet spectra were used to evaluate the dark stability and light sensitivity og DBS. Chymotrypsin and trypsin served as functioning targets for further evaluation of the photochemical properties. Both enzymes are stable to the probe in the dark at acid pH. A rapid loss of enzyme activity was observed following flash photolysis of DBS-enzyme solutions. Photolytic incorporation of radioactive DBS into chymotrypsin was observed. Aryl diazonium salts can be employed to probe the availability of complementary sites in biological targets at different acid pH values. (Author)

Regulating gonad inhibition and vitellogenin/vitellin induction in Penaeus monodon using mature GIH fusion protein and polyclonal antisera

Digital Repository Service at National Institute of Oceanography (India)

Vrinda, S.; Jasmin, C.; Sivakumar, K.C.; Jose, S.; Jose, B.; Philip, R; BrightSingh, I

September 2016 Available online 15 September 2016 Keywords: Gonad-inhibiting hormone (GIH) Fusion/chimeric proteinaa r t i c l e i n f o b s t r a c tRegulating gonad inhibition and vitellogen Penaeus monodon using mature GIH fusion polyclonal antisera... restriction site overhangs to match with that of the expression vector; pET32a+. The forward primer (GIH-F- 5′-GAAT TCAACATCCTGGACAGCAAATGCAGGGGTGC-3′) contained EcoR I site (italics) and 29 nucleotide residues encoding the N terminal amino acid residues...

Trophic significance of the kelp Laminaria digitata (Lamour.) for the associated food web: a between-sites comparison

Science.gov (United States)

Schaal, Gauthier; Riera, Pascal; Leroux, Cédric

2009-12-01

This study aimed at establishing the trophic significance of the kelp Laminaria digitata for consumers inhabiting two rocky shores of Northern Brittany (France), displaying contrasted ecological conditions. The general trophic structure did not vary between these two sites, with a wide diversity of filter-feeders and predators, and only 14% of the species sampled belonging to the grazers' trophic group. The diversity of food sources fueling the food web appeared also similar. The food webs comprised four trophic levels and the prevalence of omnivory appeared relatively low compared to previous studies in the same area. Conversely, to the food web structure, which did not differ, the biochemical composition of L. digitata differed between the two sites, and was correlated to a larger diversity of grazers feeding on this kelp in sheltered conditions. This indicated that the spatial variability occurring in the nutritive value of L. digitata is likely to deeply affect the functioning of kelp-associated food webs. The contribution of L. digitata-derived organic matter to the diet of filter-feeders inhabiting these two environments was assessed using the mixing model Isosource, which showed the higher contribution of kelp matter in sheltered conditions. These results highlight the spatial variability that may occur in the functioning of kelp-associated food webs. Moreover, this suggests that hydrodynamics is likely to control the availability of kelp-derived organic matter to local filter-feeders, probably through an increase of detritus export in exposed areas.

Native and tabun-inhibited cholinesterase interactions with oximes

International Nuclear Information System (INIS)

Kovarik, Z.; Katalinic, M.; Sinko, G.

2009-01-01

The phosphorylation of the serine hydroxyl group in the active site of acetylcholinesterase (AChE) inactivates this essential enzyme in neurotransmission. Its related enzyme butyrylcholinesterase (BChE) also interacts with organophosphorus compounds (OP) scavenging anti-cholinesterase agents and protects synaptic AChE from inhibition. Oximes are reactivators of AChE phosphorylated by OP including insecticides and nerve agents. The effectiveness of oxime-assisted reactivation is primarily attributed to the nucleophilic displacement rate of organophosphate, but efficiency varies with the structure of the bound organophosphate, the structure of the oxime as well as rates of several other cholinesterase's reactions. Besides reactivating cholinesterases, oximes also reversibly inhibit both cholinesterases and protect them from phosphorylation by OP. We tested oximes varying in the type of ring (pyridinium and/or imidazolium), the length and type of the linker between rings, and in the position of the oxime group on the ring to find more effective oximes to reactivate tabun-inhibited human erythrocyte AChE and plasma BChE. Herein we bring an overview of in vitro interactions of native and tabun-inhibited AChE and BChE with oximes together with conformational analysis of the oximes relating molecular properties to their reactivation potency.(author)

Structural Requirements for Yersinia YopJ Inhibition of MAP Kinase Pathways

Science.gov (United States)

Burdette, Dara; Mukherjee, Sohini; Keitany, Gladys; Goldsmith, Elizabeth; Orth, Kim

2008-01-01

MAPK signaling cascades are evolutionally conserved. The bacterial effector, YopJ, uses the unique activity of Ser/Thr acetylation to inhibit the activation of the MAPK kinase (MKK) and prevent activation by phosphorylation. YopJ is also able to block yeast MAPK signaling pathways using this mechanism. Based on these observations, we performed a genetic screen to isolate mutants in the yeast MKK, Pbs2, that suppress YopJ inhibition. One suppressor contains a mutation in a conserved tyrosine residue and bypasses YopJ inhibition by increasing the basal activity of Pbs2. Mutations on the hydrophobic face of the conserved G α-helix in the kinase domain prevent both binding and acetylation by YopJ. Corresponding mutants in human MKKs showed that they are conserved not only structurally, but also functionally. These studies reveal a conserved binding site found on the superfamily of MAPK kinases while providing insight into the molecular interactions required for YopJ inhibition. PMID:18167536

Structural requirements for Yersinia YopJ inhibition of MAP kinase pathways.

Directory of Open Access Journals (Sweden)

Yi-Heng Hao

2008-01-01

Full Text Available MAPK signaling cascades are evolutionally conserved. The bacterial effector, YopJ, uses the unique activity of Ser/Thr acetylation to inhibit the activation of the MAPK kinase (MKK and prevent activation by phosphorylation. YopJ is also able to block yeast MAPK signaling pathways using this mechanism. Based on these observations, we performed a genetic screen to isolate mutants in the yeast MKK, Pbs2, that suppress YopJ inhibition. One suppressor contains a mutation in a conserved tyrosine residue and bypasses YopJ inhibition by increasing the basal activity of Pbs2. Mutations on the hydrophobic face of the conserved G alpha-helix in the kinase domain prevent both binding and acetylation by YopJ. Corresponding mutants in human MKKs showed that they are conserved not only structurally, but also functionally. These studies reveal a conserved binding site found on the superfamily of MAPK kinases while providing insight into the molecular interactions required for YopJ inhibition.

Effects of High-Definition and Conventional tDCS on Response Inhibition.

Science.gov (United States)

Hogeveen, J; Grafman, J; Aboseria, M; David, A; Bikson, M; Hauner, K K

2016-01-01

Response inhibition is a critical executive function, enabling the adaptive control of behavior in a changing environment. The inferior frontal cortex (IFC) is considered to be critical for response inhibition, leading researchers to develop transcranial direct current stimulation (tDCS) montages attempting to target the IFC and improve inhibitory performance. However, conventional tDCS montages produce diffuse current through the brain, making it difficult to establish causality between stimulation of any one given brain region and resulting behavioral changes. Recently, high-definition tDCS (HD-tDCS) methods have been developed to target brain regions with increased focality relative to conventional tDCS. Remarkably few studies have utilized HD-tDCS to improve cognitive task performance, however, and no study has directly compared the behavioral effects of HD-tDCS to conventional tDCS. In the present study, participants received either HD-tDCS or conventional tDCS to the IFC during performance of a response inhibition task (stop-signal task, SST) or a control task (choice reaction time task, CRT). A third group of participants completed the same behavioral protocols, but received tDCS to a control site (mid-occipital cortex). Post-stimulation improvement in SST performance was analyzed as a function of tDCS group and the task performed during stimulation using both conventional and Bayesian parameter estimation analyses. Bayesian estimation of the effects of HD- and conventional tDCS to IFC relative to control site stimulation demonstrated enhanced response inhibition for both conditions. No improvements were found after control task (CRT) training in any tDCS condition. Results support the use of both HD- and conventional tDCS to the IFC for improving response inhibition, providing empirical evidence that HD-tDCS can be used to facilitate performance on an executive function task. Copyright © 2016 Elsevier Inc. All rights reserved.

Kinase inhibition by the Jamaican ball moss, Tillandsia recurvata L.

Science.gov (United States)

Lowe, Henry I C; Watson, Charah T; Badal, Simone; Toyang, Ngeh J; Bryant, Joseph

2012-10-01

This research was undertaken in order to investigate the inhibitory potential of the Jamaican ball moss, Tillandsia recurvata against several kinases. The inhibition of these kinases has emerged as a potential solution to restoring the tight regulation of normal cellular growth, the loss of which leads to cancer cell formation. Kinase inhibition was investigated using competition binding (to the ATP sites) assays, which have been previously established and authenticated. Four hundred and fifty one kinases were tested against the Jamaican ball moss extract and a dose-response was tested on 40 kinases, which were inhibited by more than 35% compared to the control. Out of the 40 kinases, the Jamaican ball moss selectively inhibited 5 (CSNK2A2, MEK5, GAK, FLT and DRAK1) and obtained Kd(50)s were below 20 μg/ml. Since MEK5 and GAK kinases have been associated with aggressive prostate cancer, the inhibitory properties of the ball moss against them, coupled with its previously found bioactivity towards the PC-3 cell line, makes it promising in the arena of drug discovery towards prostate cancer.

Inhibition of basophil histamine release by gangliosides. Further studies on the significance of cell membrane sialic acid in the histamine release process

DEFF Research Database (Denmark)

Jensen, C; Norn, S; Thastrup, Ole

1987-01-01

with the glucolipid mixture increased the sialic acid content of the cells, and this increase was attributed to an insertion of gangliosides into the cell membrane. The inhibition of histamine release was abolished by increasing the calcium concentration, which substantiates our previous findings that cell membrane......Histamine release from human basophils was inhibited by preincubation of the cells with a glucolipid mixture containing sialic acid-containing gangliosides. This was true for histamine release induced by anti-IgE, Concanavalin A and the calcium ionophore A23187, whereas the release induced by S....... aureus Wood 46 was not affected. It was demonstrated that the inhibitory capacity of the glucolipid mixture could be attributed to the content of gangliosides, since no inhibition was obtained with cerebrosides or with gangliosides from which sialic acid was removed. Preincubation of the cells...

Substrate-dependent inhibition of human MATE1 by cationic ionic liquids.

Science.gov (United States)

Martínez-Guerrero, Lucy J; Wright, Stephen H

2013-09-01

The multidrug and toxin extruders 1- and 2-K (MATE1 and MATE2-K) are expressed in the luminal membrane of renal proximal tubule cells and provide the active step in the secretion of molecules that carry a net positive charge at physiologic pH, so-called organic cations. The present study tested whether structurally distinct MATE substrates can display different quantitative profiles of inhibition when interacting with structurally distinct ligands. The tested ligands were three structurally similar cationic ionic liquids (ILs, salts in the liquid state: N-butylpyridinium, NBuPy; 1-methyl-3-butylimidazolium, Bmim; and N-butyl-N-methylpyrrolidinium, BmPy). Uptake was measured using Chinese hamster ovary cells that stably expressed MATE1 or MATE2-K. By trans-stimulation, all three ILs were transported by both MATE transporters. The three ILs also inhibited uptake of three structurally distinct MATE substrates: 1-methyl-4-phenylpyridinium (MPP), triethylmethylammonium (TEMA), and N,N,N-trimethyl-2-[methyl(7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)amino]ethanaminium (NBD-MTMA). MATE1 displayed a higher affinity for the pyridinium-based NBuPy (IC50 values, 2-4 µM) than for either the pyrrolidinium- (BmPy; 20-70 µM) or imidazolium-based ILs (Bmim; 15-60 µM). Inhibition of MPP, TEMA, and NBD-MTMA transport by NBuPy was competitive, with comparable Ki values against all substrates. Bmim also competitively blocked the three substrates but with Ki values that differed significantly (20 µM against MPP and 30 µM against NBD-MTMA versus 60 µM against TEMA). Together, these data indicate that renal secretion of ILs by the human kidney involves MATE transporters and suggest that the mechanism of transport inhibition is ligand-dependent, supporting the hypothesis that the binding of substrates to MATE transporters involves interaction with a binding surface with multiple binding sites.

Kindergarteners’ Self-Reported Social Inhibition and Observed Social Reticence: Moderation by Adult-Reported Social Inhibition and Social Anxiety Disorder Symptoms

Science.gov (United States)

Kiel, Elizabeth J.; Buss, Kristin A.; Molitor, Joseph G.

2014-01-01

Prevention of later anxiety problems would best be accomplished by identifying at-risk children early in development. For example, children who develop Social Anxiety Disorder (SAD) may show social withdrawal in the form of social inhibition (i.e., shyness with unfamiliar adults and peers) at school entry. Although the use of children’s perceptions of their own social inhibition would provide insight into early risk, the utility of young children’s self-reports remains unclear. The current study examined whether children deemed more extreme on social inhibition or social anxiety by adult report provided self-report of social inhibition that related to observed social reticence in the laboratory. Participants included 85 kindergarten children (36 female, 49 male), their parents, and their teachers. Moderation analyses revealed that children’s self-reported social inhibition related significantly to observed social reticence under the conditions of high parent-reported social inhibition, high teacher-reported social inhibition, and high SAD symptoms. These results suggest that the most inhibited children are aware of their behavior and can report it in a meaningfully way as young as kindergarten age. PMID:25113397

Furan- and Thiophene-2-Carbonyl Amino Acid Derivatives Activate Hypoxia-Inducible Factor via Inhibition of Factor Inhibiting Hypoxia-Inducible Factor-1

Directory of Open Access Journals (Sweden)

Shin-ichi Kawaguchi

2018-04-01

Full Text Available Induction of a series of anti-hypoxic proteins protects cells during exposure to hypoxic conditions. Hypoxia-inducible factor-α (HIF-α is a major transcription factor that orchestrates this protective effect. To activate HIF exogenously, without exposing cells to hypoxic conditions, many small-molecule inhibitors targeting prolyl hydroxylase domain-containing protein have been developed. In addition, suppression of factor inhibiting HIF-1 (FIH-1 has also been shown to have the potential to activate HIF-α. However, few small-molecule inhibitors of FIH-1 have been developed. In this study, we synthesized a series of furan- and thiophene-2-carbonyl amino acid derivatives having the potential to inhibit FIH-1. The inhibitory activities of these compounds were evaluated in SK-N-BE(2c cells by measuring HIF response element (HRE promoter activity. Several furan- and thiophene-2-carbonyl amino acid derivatives inhibited FIH-1 based on correlations among the docking score of the FIH-1 active site, the chemical structure of the compounds, and biological HIF-α/HRE transcriptional activity.

LIGAND-BINDING SITES ON THE MYCOBACTERIUM TUBERCULOSIS UREASE

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Lisnyak Yu. V.

2017-10-01

Full Text Available Introduction. Mycobacterium tuberculosis is the causative agent of tuberculosis that remains a serious medical and social health problem. Despite intensive efforts have been made in the past decade, there are no new efficient anti-tuberculosis drugs today, and that need is growing due to the spread of drug-resistant strains of M.tuberculosis. M. tuberculosis urease (MTU, being an important factor of the bacterium viability and virulence, is an attractive target for anti-tuberculosis drugs acting by inhibition of urease activity. However, the commercially available urease inhibitors are toxic and unstable, that prevent their clinical use. Therefore, new more potent anti-tuberculosis drugs inhibiting new targets are urgently needed. A useful tool for the search of novel inhibitors is a computational drug design. The inhibitor design is significantly easier if binding sites on the enzyme are identified in advance. This paper aimed to determine the probable ligand binding sites on the surface of M. tuberculosis urease. Methods. To identify ligand binding sites on MTU surface, сomputational solvent mapping method FTSite was applied by the use of MTU homology model we have built earlier. The method places molecular probes (small organic molecules containing various functional groups on a dense grid defined around the enzyme, and for each probe finds favorable positions. The selected poses are refined by free energy minimization, the low energy conformations are clustered, and the clusters are ranked on the basis of the average free energy. FTSite server outputs the protein residues delineating a binding sites and the probe molecules representing each cluster. To predict allosteric pockets on MTU, AlloPred and AlloSite servers were applied. AlloPred uses the normal mode analysis (NMA and models how the dynamics of a protein would be altered in the presence of a modulator at a specific pocket. Pockets on the enzyme are predicted using the Fpocket

Structural Basis for Specific Inhibition of tRNA Synthetase by an ATP Competitive Inhibitor.

Science.gov (United States)

Fang, Pengfei; Han, Hongyan; Wang, Jing; Chen, Kaige; Chen, Xin; Guo, Min

2015-06-18

Pharmaceutical inhibitors of aminoacyl-tRNA synthetases demand high species and family specificity. The antimalarial ATP-mimetic cladosporin selectively inhibits Plasmodium falciparum LysRS (PfLysRS). How the binding to a universal ATP site achieves the specificity is unknown. Here we report three crystal structures of cladosporin with human LysRS, PfLysRS, and a Pf-like human LysRS mutant. In all three structures, cladosporin occupies the class defining ATP-binding pocket, replacing the adenosine portion of ATP. Three residues holding the methyltetrahydropyran moiety of cladosporin are critical for the specificity of cladosporin against LysRS over other class II tRNA synthetase families. The species-exclusive inhibition of PfLysRS is linked to a structural divergence beyond the active site that mounts a lysine-specific stabilizing response to binding cladosporin. These analyses reveal that inherent divergence of tRNA synthetase structural assembly may allow for highly specific inhibition even through the otherwise universal substrate binding pocket and highlight the potential for structure-driven drug development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Selective labeling of serotonin uptake sites in rat brain by [3H]citalopram contrasted to labeling of multiple sites by [3H]imipramine

International Nuclear Information System (INIS)

D'Amato, R.J.; Largent, B.L.; Snowman, A.M.; Snyder, S.H.

1987-01-01

Citalopram is a potent and selective inhibitor of neuronal serotonin uptake. In rat brain membranes [ 3 H]citalopram demonstrates saturable and reversible binding with a KD of 0.8 nM and a maximal number of binding sites (Bmax) of 570 fmol/mg of protein. The drug specificity for [ 3 H]citalopram binding and synaptosomal serotonin uptake are closely correlated. Inhibition of [ 3 H]citalopram binding by both serotonin and imipramine is consistent with a competitive interaction in both equilibrium and kinetic analyses. The autoradiographic pattern of [ 3 H]citalopram binding sites closely resembles the distribution of serotonin. By contrast, detailed equilibrium-saturation analysis of [ 3 H]imipramine binding reveals two binding components, i.e., high affinity (KD = 9 nM, Bmax = 420 fmol/mg of protein) and low affinity (KD = 553 nM, Bmax = 8560 fmol/mg of protein) sites. Specific [ 3 H]imipramine binding, defined as the binding inhibited by 100 microM desipramine, is displaced only partially by serotonin. Various studies reveal that the serotonin-sensitive portion of binding corresponds to the high affinity sites of [ 3 H]imipramine binding whereas the serotonin-insensitive binding corresponds to the low affinity sites. Lesioning of serotonin neurons with p-chloroamphetamine causes a large decrease in [ 3 H]citalopram and serotonin-sensitive [ 3 H]imipramine binding with only a small effect on serotonin-insensitive [ 3 H]imipramine binding. The dissociation rate of [ 3 H]imipramine or [ 3 H]citalopram is not altered by citalopram, imipramine or serotonin up to concentrations of 10 microM. The regional distribution of serotonin sensitive [ 3 H]imipramine high affinity binding sites closely resembles that of [ 3 H]citalopram binding

Inhibition of the Vacuolar-like ATPase from Halobacterium saccharovorum by Thiol Reagents: Evidence for Different Functional Thiols

Science.gov (United States)

Hochstein, L. I.; Stanlotter, H.; Emrich, E.; Morrison, David (Technical Monitor)

1994-01-01

N-Ethylmaleimide (NEM) inhibited the vacuolar-like ATPase from Halobacterium saccharovorum (K(sub i) approximately 1 mM) by modifying one or more of the thiols located on the largest of the subunit. ATP protected against inhibition and coincidentally prevented NEM binding which suggested that NEM acts at or near the catalytic site. p-Chloromercuriphenylsulfonate (PCMS) also inhibited this ATPase (K(sub i) approximately 90 microM). ATP did not protect against PCMS inhibition. Dithiothreitol (DTT) partially reversed PCMS inhibition and restored approximately half of the initial activity of 90% inhibited enzyme. DTT did not restore activity of the NEM-inhibited enzyme or the PCMS-inhibited enzyme when it was subsequently incubated with NEM. The failure of ATP to protect against PCMS inhibition and the inability of DTT to restore activity of enzyme incubated in the presence of PCMS and NEM suggests these reagents react with different thiols and that the PCMS-sensitive thiol may have a structural role.

Downregulation of CCR1 inhibits human hepatocellular carcinoma cell invasion

International Nuclear Information System (INIS)

Wu Xiaofeng; Fan Jia; Wang Xiaoying; Zhou Jian; Qiu Shuangjian; Yu Yao; Liu Yinkun; Tang Zhaoyou

2007-01-01

CC chemokine receptor 1 (CCR1) has an important role in the recruitment of leukocytes to the site of inflammation. The migration and metastasis of tumor cells shares many similarities with leukocyte trafficking, which is mainly regulated by chemokine receptor-ligand interactions. CCR1 is highly expressed in hepatocellular carcinoma (HCC) cells and tissues with unknown functions. In this study, we silenced CCR1 expression in the human HCC cell line HCCLM3 using artificial microRNA (miRNA)-mediated RNA interference (RNAi) and examined the invasiveness and proliferation of CCR1-silenced HCCLM3 cells and the matrix metalloproteinase (MMP) activity. The miRNA-mediated knockdown expression of CCR1 significantly inhibited the invasive ability of HCCLM3 cells, but had only a minor effect on the cellular proliferation rate. Moreover, CCR1 knockdown significantly reduced the secretion of MMP-2. Together, these findings indicate that CCR1 has an important role in HCCLM3 invasion and that CCR1 might be a new target of HCC treatment

Transcutaneous Electrical Nerve Stimulation (TENS) reduces pain, fatigue, and hyperalgesia while restoring central inhibition in primary fibromyalgia

Science.gov (United States)

Dailey, Dana L; Rakel, Barbara A; Vance, Carol GT; Liebano, Richard E; Anand, Amrit S; Bush, Heather M; Lee, Kyoung S; Lee, Jennifer E; Sluka, Kathleen A

2014-01-01

Because TENS works by reducing central excitability and activating central inhibition pathways, we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition. The current study used a double-blinded randomized, placebo controlled cross-over design to test effects of a single treatment of TENS in people with fibromyalgia. Three treatments were assessed in random order: active TENS, placebo TENS, no TENS. The following measures were assessed before and after each TENS treatment: pain and fatigue at rest and movement, pressure pain thresholds (PPTs), 6 minute walk test (6MWT), range of motion (ROM), five time sit to stand test (FTSTS), and single leg stance (SLS). Conditioned pain modulation (CPM) was completed at end of testing. There was a significant decrease in pain and fatigue with movement for active TENS compared to placebo and no TENS. PPTs increased at site of TENS (spine) and outside site of TENS (leg) when compared to placebo TENS or no TENS. During Active TENS CPM was significantly stronger compared to placebo TENS and no TENS. No changes in functional tasks were observed with TENS. Thus, the current study suggests TENS has short-term efficacy in relieving symptoms of fibromyalgia while the stimulator is active. Future clinical trials should examine the effects of repeated daily delivery of TENS, similar to how TENS is used clinically, on pain, fatigue, function and quality of life in individuals with fibromyalgia. PMID:23900134

Translational inhibition of CTX M extended spectrum β-lactamase in clinical strains of Escherichia coli by synthetic antisense oligonucleotides partially restores sensitivity to cefotaxime.

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John Benedict Readman

2016-03-01

Full Text Available Synthetic antisense oligomers are DNA mimics that can specifically inhibit gene expression at the translational level by ribosomal steric hindrance. They bind to their mRNA targets by Watson Crick base pairing and are resistant to degradation by both nucleases and proteases. A 25 mer phosphorodiamidate morpholino oligomer (PMO and a 13 mer polyamide (peptide nucleic acid (PNA were designed to target mRNA (positions -4 to +21, and –17 to –5 respectively close to the translational initiation site of the extended spectrum β lactamase resistance genes of CTX M group 1. These antisense oligonucleotides were found to inhibit β lactamase activity by up to 96% in a cell free translation transcription coupled system using an expression vector carrying a blaCTX-M-15 gene cloned from a clinical isolate. Despite evidence for up regulation of CTX-M gene expression, they were both found to significantly restore sensitivity to cefotaxime in E. coli AS19, an atypical cell wall permeable mutant, in a dose dependant manner (0 - 40 nM. The PMO and PNA were covalently bound to the cell penetrating peptide (KFF3K and both significantly (P<0.05 increased sensitivity to cefotaxime in a dose dependent manner (0 - 40 nM in field isolates harbouring CTX-M group 1 β-lactamases. Antisense oligonucleotides targeted to the translational initiation site and Shine Dalgarno region of blaCTX-M-15 inhibited gene expression, and when conjugated to a cell penetrating delivery vehicle, partially restored antibiotic sensitivity to both field and clinical isolates.

Use of bacillus subtilis strains to inhibit postharvest pathogenic fungi

International Nuclear Information System (INIS)

Arras, G.; Gambella, F.; Demontis, S.; Petretto, A.

1995-01-01

An isolate (87) of the bacillus subtilis strains isolated from cold stored citrus fruit 13 proved to inhibit the growth in vitro of the penicillium italicum used in the experiment (from 50.6% to 92.2%) and to inhibit botrytis cinerea (from 65.3% to 95.9%). A further test, superimposing on plates containing PDA strains Nos. 13, 173, and 160, totally inhibited the fungi. Tested in vivo on artificially bruised oranges, they significantly inhibited two fungi

A novel approach to inhibit bone resorption

DEFF Research Database (Denmark)

Panwar, Preety; Søe, Kent; Guido, Rafael VC

2016-01-01

BACKGROUND AND PURPOSE: Cathepsin K (CatK) is a major drug target for the treatment of osteoporosis. Potent active site-directed inhibitors have been developed and showed variable success in clinical trials. These inhibitors block the entire activity of CatK and thus may interfere with other...... pathways. The present study investigates the antiresorptive effect of an exosite inhibitor that selectively inhibits only the therapeutically relevant collagenase activity of CatK. EXPERIMENTAL APPROACH: Human osteoclasts and fibroblasts were used to analyse the effect of the exosite inhibitor, ortho......-dihydrotanshinone (DHT1), and the active site inhibitor, odanacatib (ODN), on bone resorption and TGF-ß1 degradation. Cell cultures, Western blot, light and scanning electron microscopy as well as energy dispersive X-ray spectroscopy, molecular modelling and enzymatic assays were used to evaluate the inhibitors. KEY...

Significance of Cuscutain, a cysteine protease from Cuscuta reflexa, in host-parasite interactions.

Science.gov (United States)

Bleischwitz, Marc; Albert, Markus; Fuchsbauer, Hans-Lothar; Kaldenhoff, Ralf

2010-10-22

Plant infestation with parasitic weeds like Cuscuta reflexa induces morphological as well as biochemical changes in the host and the parasite. These modifications could be caused by a change in protein or gene activity. Using a comparative macroarray approach Cuscuta genes specifically upregulated at the host attachment site were identified. One of the infestation specific Cuscuta genes encodes a cysteine protease. The protein and its intrinsic inhibitory peptide were heterologously expressed, purified and biochemically characterized. The haustoria specific enzyme was named cuscutain in accordance with similar proteins from other plants, e.g. papaya. The role of cuscutain and its inhibitor during the host parasite interaction was studied by external application of an inhibitor suspension, which induced a significant reduction of successful infection events. The study provides new information about molecular events during the parasitic plant--host interaction. Inhibition of cuscutain cysteine proteinase could provide means for antagonizing parasitic plants.

Remediation options and the significance of water treatment at former uranium production sites in Eastern Germany

International Nuclear Information System (INIS)

Gatzweiler, R.; Jakubick, A.T.; Kiessig, G.

2000-01-01

The WISMUT remediation project in the States of Saxony and Thuringia, Germany, comprises several mine and mill sites including large volumes of production residues. Due to the climate, the intensive land use and the regulatory conditions, the water path is most important in evaluating remediation options. Water treatment is an integral part of mine flooding, mine dump and tailings remediation, and treatment costs represent a major portion of the overall costs of the project. Uncertainties in the estimations of quantities of mine and seepage waters, variations in quality from site to site, and changing conditions in time demand a strategic approach to the selection and optimization of water treatment methods. The paper describes options considered and experience gained including efforts to limit long-term treatment costs by developing and applying passive treatment systems and negotiating acceptable discharge limits. (author)

Disulfide bond within mu-calpain active site inhibits activity and autolysis.

Science.gov (United States)

Lametsch, René; Lonergan, Steven; Huff-Lonergan, Elisabeth

2008-09-01

Oxidative processes have the ability to influence mu-calpain activity. In the present study the influence of oxidation on activity and autolysis of mu-calpain was examined. Furthermore, LC-MS/MS analysis was employed to identify and characterize protein modifications caused by oxidation. The results revealed that the activity of mu-calpain is diminished by oxidation with H2O2 in a reversible manner involving cysteine and that the rate of autolysis of mu-calpain concomitantly slowed. The LC-MS/MS analysis of the oxidized mu-calpain revealed that the amino acid residues 105-133 contained a disulfide bond between Cys(108) and Cys(115). The finding that the active site cysteine in mu-calpain is able to form a disulfide bond has, to our knowledge, not been reported before. This could be part of a unique oxidation mechanism for mu-calpain. The results also showed that the formation of the disulfide bond is limited in the control (no oxidant added), and further limited in a concentration-dependent manner when beta-mercaptoethanol is added. However, the disulfide bond is still present to some extent in all conditions indicating that the active site cysteine is potentially highly susceptible to the formation of this intramolecular disulfide bond.

Irradiation inhibits vascular anastomotic stenosis in a canine model

International Nuclear Information System (INIS)

Saito, Takeshi; Iguchi, Atsushi; Tabayashi, Koichi

2009-01-01

The graft patency rate after coronary artery bypass grafting (CABG) correlates with anastomotic stenosis. Intracoronary radiation therapy is effective for preventing restenosis after percutaneous coronary intervention (PCI). We postulated that intracoronary radiation therapy could prevent anastomotic stenosis and tested this hypothesis in an animal model. Femoral arteries and veins of beagle dogs were harvested, and composite arterioarterial and arteriovenous grafts were prepared. After external irradiation of the anastomotic sites, these composite grafts were transplanted into femoral arteries. Histomorphometric and immunohistological analyses of the anastomotic sites were performed. The study groups consisted of controls and animals exposed to 10 Gy, 20 Gy, and 30 Gy (n=5, in each group). In the artery graft model, the ratio of negative remodeling was significantly increased in all groups exposed to ≥10 Gy. The ratio of neointimal hyperplasia was significantly decreased in all groups exposed to ≥10 Gy. Cell density of anti-α-actin antibody-positive cells and anti-proliferating cell nuclear antigen (PCNA) antibody-positive cells was highest in the adventitial layer, and the density decreased as the dosage increased. Experimental results were almost the same in the vein graft models as in the artery graft models. With double immunohistostaining, the anti-PCNA antibody-positive cells expressed α-actin. Irradiation can inhibit anastomotic stenosis in a canine model. Adventitia is a factor in the creation of stenosis, and irradiation appears to target the adventitia. We speculate that there might be a possible role for intracoronary irradiation in the future to prevent anastomotic stenosis. (author)

A speculated cause of respiratory inhibition in infants.

Science.gov (United States)

Minowa, Hideki; Arai, Ikuyo; Yasuhara, Hajime; Ebisu, Reiko; Ohgitani, Ayako

2018-10-01

In our previous studies, we documented that threatened premature labor and asymmetrical intrauterine growth restriction were risk factors for respiratory inhibition. The goal of this study was to determine the cause of respiratory inhibition by considering perinatal risk factors. We examined 1497 infants with a gestational age of 36 weeks or greater. All infants were monitored using pulse oximetry and examined via cranial sonography. Respiratory inhibition was defined as severe hypoxemia caused by respiratory inhibition immediately after crying or gastroesophageal reflux or as a respiratory pause during feeding. We examined the relationships between respiratory inhibition and perinatal factors and speculated on the cause of respiratory inhibition. The median gestational age, birth weight, Apgar score at 1 min, and Apgar score at 5 min of the subjects were 38.9 weeks, 2930 g, 8.0 points, and 9.0 points, respectively. Respiratory inhibition was observed in 422 infants. Lateral ventricle enlargement and increased echogenicity in the ganglionic eminence were observed in 417 and 516 infants, respectively. Respiratory inhibition was significantly correlated with shorter gestational periods, twin pregnancies, lateral ventricle enlargement, and increased echogenicity in the ganglionic eminence. We speculate that umbilical cord compression is a major cause of respiratory inhibition.

Inhibition of coagulation factors by recombinant barley serpin BSZx

DEFF Research Database (Denmark)

Dahl, Søren Weis; Rasmussen, S.K.; Petersen, L..C.

1996-01-01

Barley serpin BSZx is a potent inhibitor of trypsin and chymotrypsin at overlapping reactive sites (Dahl, S.W., Rasmussen, S.K. and Hejgaard, J. (1996) J. Biol, Chem., in press), We have now investigated the interactions of BSZx with a range of serine proteinases from human plasma, pancreas......, urokinase and tissue type plasminogen activator, plasmin and pancreas kallikrein and elastase were not or only weakly affected, The inhibition pattern with mammalian proteinases reveal a specificity of BSZx similar to that of antithrombin III. Trypsin from Fusarium was not inhibited while interaction...... with subtilisin Carlsberg and Novo was rapid but most BSZx was cleaved as a substrate, Identification of a monoclonal antibody specific for native BSZx indicate that complex formation and loop cleavage result in similar conformational changes....

Opioid receptors in human neuroblastoma SH-SY5Y cells: evidence for distinct morphine (. mu. ) and enkephalin (delta) binding sites

Energy Technology Data Exchange (ETDEWEB)

Kazmi, S.M.I.; Mishra, R.K.

1986-06-13

Human neuroblastoma SH-SY5Y cells exhibited a heterogeneous population of ..mu.. and delta types of opioid binding sites. These specific binding sites displayed the characteristic saturability, stereospecificity and reversibility, expected of a receptor. Scatchard analysis of (/sup 3/H)-D-Ala/sup 2/-D-Leu/sup 5/-enkephalin (DADLE) in the presence of 10/sup -5/M D-Pro/sup 4/-morphiceptin (to block the ..mu.. receptors) and the competitive displacement by various highly selective ligands yielded the binding parameters of delta sites which closely resemble those of the delta receptors in brain and mouse neuroblastoma clones. Similarly, the high affinity binding of (/sup 3/H)-dihydromorphine, together with the higher potency of morphine analogues to displace (/sup 3/H)-naloxone binding established the presence of ..mu.. sites. Guanine nucleotides and NaCl significantly inhibited the association and increased the dissociation of (/sup 3/H)-DADLE binding.

Polypyridylruthenium(II complexes exert anti-schistosome activity and inhibit parasite acetylcholinesterases.

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Madhu K Sundaraneedi

2017-12-01

Full Text Available Schistosomiasis affects over 200 million people and there are concerns whether the current chemotherapeutic control strategy (periodic mass drug administration with praziquantel (PZQ-the only licenced anti-schistosome compound is sustainable, necessitating the development of new drugs.We investigated the anti-schistosome efficacy of polypyridylruthenium(II complexes and showed they were active against all intra-mammalian stages of S. mansoni. Two compounds, Rubb12-tri and Rubb7-tnl, which were among the most potent in their ability to kill schistosomula and adult worms and inhibit egg hatching in vitro, were assessed for their efficacy in a mouse model of schistosomiasis using 5 consecutive daily i.v. doses of 2 mg/kg (Rubb12-tri and 10 mg/kg (Rubb7-tnl. Mice treated with Rubb12-tri showed an average 42% reduction (P = 0.009, over two independent trials, in adult worm burden. Liver egg burdens were not significantly decreased in either drug-treated group but ova from both of these groups showed significant decreases in hatching ability (Rubb12-tri-68%, Rubb7-tnl-56% and were significantly morphologically altered (Rubb12-tri-62% abnormal, Rubb7-tnl-35% abnormal. We hypothesize that the drugs exerted their activity, at least partially, through inhibition of both neuronal and tegumental acetylcholinesterases (AChEs, as worms treated in vitro showed significant decreases in activity of these enzymes. Further, treated parasites exhibited a significantly decreased ability to uptake glucose, significantly depleted glycogen stores and withered tubercules (a site of glycogen storage, implying drug-mediated interference in this nutrient acquisition pathway.Our data provide compelling evidence that ruthenium complexes are effective against all intra-mammalian stages of schistosomes, including schistosomula (refractory to PZQ and eggs (agents of disease transmissibility. Further, the results of this study suggest that schistosome AChE is a target of

Insight to structural subsite recognition in plant thiol protease-inhibitor complexes : Understanding the basis of differential inhibition and the role of water

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Mukhopadhayay Bishnu P

2001-09-01

Full Text Available Abstract Background This work represents an extensive MD simulation / water-dynamics studies on a series of complexes of inhibitors (leupeptin, E-64, E-64-C, ZPACK and plant cysteine proteases (actinidin, caricain, chymopapain, calotropin DI of papain family to understand the various interactions, water binding mode, factors influencing it and the structural basis of differential inhibition. Results The tertiary structure of the enzyme-inhibitor complexes were built by visual interactive modeling and energy minimization followed by dynamic simulation of 120 ps in water environment. DASA study with and without the inhibitor revealed the potential subsite residues involved in inhibition. Though the interaction involving main chain atoms are similar, critical inspection of the complexes reveal significant differences in the side chain interactions in S2-P2 and S3-P3 pairs due to sequence differences in the equivalent positions of respective subsites leading to differential inhibition. Conclusion The key finding of the study is a conserved site of a water molecule near oxyanion hole of the enzyme active site, which is found in all the modeled complexes and in most crystal structures of papain family either native or complexed. Conserved water molecules at the ligand binding sites of these homologous proteins suggest the structural importance of the water, which changes the conventional definition of chemical geometry of inhibitor binding domain, its shape and complimentarity. The water mediated recognition of inhibitor to enzyme subsites (Pn...H2O....Sn of leupeptin acetyl oxygen to caricain, chymopapain and calotropinDI is an additional information and offer valuable insight to potent inhibitor design.

Inhibition of biological activity of staphylococcal enterotoxin A (SEA) by apple juice and apple polyphenols.

Science.gov (United States)

Rasooly, Reuven; Do, Paula M; Friedman, Mendel

2010-05-12

The foodborne pathogen Staphylococcus aureus produces the virulent staphylococcal enterotoxin A (SEA), a single-chain protein that consists of 233 amino acid residues with a molecular weight of 27 078 Da. SEA is a superantigen that is reported to contribute to animal (mastitis) and human (emesis, diarrhea, atopic dermatitis, arthritis, and toxic shock) syndromes. Changes of the native structural integrity may inactivate the toxin by preventing molecular interaction with cell membrane receptor sites of their host cells. In the present study, we evaluated the ability of one commercial and two freshly prepared apple juices and a commercial apple polyphenol preparation (Apple Poly) to inhibit the biological activity of SEA. Dilutions of freshly prepared apple juices and Apple Poly inhibited the biological activity of SEA without any significant cytotoxic effect on the spleen cells. Additional studies with antibody-coated immunomagnetic beads bearing specific antibodies against the toxin revealed that SEA added to apple juice appears to be largely irreversibly bound to the juice constituents. The results suggest that food-compatible and safe anti-toxin phenolic compounds can be used to inactivate SEA in vitro and possibly also in vivo, even after induction of T-cell proliferation by long-term exposure to SEA. The significance of the results for microbial food safety and human health is discussed.

One-site versus two-site phacotrabeculectomy: a prospective randomized study

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Moschos MM

2015-08-01

Full Text Available Marilita M Moschos,1 Irini P Chatziralli,2 Michael Tsatsos3 1First Department of Ophthalmology, University of Athens, 2Second Department of Ophthalmology, Ophthalmiatrion Athinon, Athens, Greece; 3Department of Ophthalmology, Cambridge University Hospital NHS, Cambridge, UK Purpose: The purpose of this study is to compare the efficacy and safety of one-site and two-site combined phacotrabeculectomy with foldable posterior chamber intraocular lens implantation.Methods: Thirty-four patients (41 eyes with glaucoma and cataract were randomly assigned to undergo either a one-site (22 eyes or a two-site (19 eyes combined procedure. One-site approach consisted of a standard superior phacotrabeculectomy with a limbus-based conjunctival flap, while two-site approach consisted of a clear cornea phacoemulsification and a separate superior trabeculectomy with a limbus-based conjunctival flap.Results: Mean follow-up period was 54 months (standard deviation [SD] 2.3. Mean preoperative intraocular pressure (IOP in the one-site group was 21.3 mmHg (SD 2.8 and in the two-site group was 21.8 mmHg (SD 3.0 (P>0.1. Mean postoperative IOP significantly decreased in both groups compared to the preoperative level and was 15.6 mmHg (SD 3.5 in the one-site group and 14.9 mmHg (SD 2.7 in the two-site group. Three months later, the difference between the two groups was not statistically significant (P=0.058. The one-site group required significantly more medications than the two-site group (P=0.03. Best-corrected visual acuity (BCVA improved similarly in both groups, but there was less postoperative (induced astigmatism in the two-site group in a marginal statistical level (P=0.058. Intra- and postoperative complications were comparable in the two groups.Conclusion: Both techniques yielded similar results concerning final BCVA and IOP reduction. However, the two-site group had less induced astigmatism and a better postoperative IOP control with less required

Lipopolysaccharide inhibits colonic biotin uptake via interference with membrane expression of its transporter: a role for a casein kinase 2-mediated pathway.

Science.gov (United States)

Lakhan, Ram; Said, Hamid M

2017-04-01

Biotin (vitamin B7), an essential micronutrient for normal cellular functions, is obtained from both dietary sources as well as gut microbiota. Absorption of biotin in both the small and large intestine is via a carrier-mediated process that involves the sodium-dependent multivitamin transporter (SMVT). Although different physiological and molecular aspects of intestinal biotin uptake have been delineated, nothing is known about the effect of LPS on the process. We addressed this issue using in vitro (human colonic epithelial NCM460 cells) and in vivo (mice) models of LPS exposure. Treating NCM460 cells with LPS was found to lead to a significant inhibition in carrier-mediated biotin uptake. Similarly, administration of LPS to mice led to a significant inhibition in biotin uptake by native colonic tissue. Although no changes in total cellular SMVT protein and mRNA levels were observed, LPS caused a decrease in the fraction of SMVT expressed at the cell surface. A role for casein kinase 2 (CK2) (whose activity was also inhibited by LPS) in mediating the endotoxin effects on biotin uptake and on membrane expression of SMVT was suggested by findings that specific inhibitors of CK2, as well as mutating the putative CK2 phosphorylation site (Thr 78 Ala) in the SMVT protein, led to inhibition in biotin uptake and membrane expression of SMVT. This study shows for the first time that LPS inhibits colonic biotin uptake via decreasing membrane expression of its transporter and that these effects likely involve a CK2-mediated pathway.

PRL-3 siRNA inhibits the metastasis of B16-BL6 mouse melanoma cells in vitro and in vivo.

Science.gov (United States)

Qian, Feng; Li, Yu-Pei; Sheng, Xia; Zhang, Zi-Chao; Song, Ran; Dong, Wei; Cao, Shao-Xian; Hua, Zi-Chun; Xu, Qiang

2007-01-01

Phosphatase of regenerating liver-3 (PRL-3) has been proposed to promote the invasion of tumor cells to metastasis sites. However, the effect of PRL-3 on spontaneous metastasis has not been clearly demonstrated, and whether PRL-3 could become a new therapeutic target in malignant tumor is still unknown. In this study, we used PRL-3 siRNA as a molecular medicine to specifically reduce the expression of PRL-3 in B16-BL6 cells, a highly metastatic melanoma cell line. In vitro, PRL-3 siRNA significantly inhibited cell adhesion and migration, but had no effect on cell proliferation. In the spontaneous metastatic tumor model in vivo, PRL-3 siRNA treatment remarkably inhibited the proliferation of primary tumor, prevented tumor cells from invading the draining lymph nodes, and prolonged the life span of mice. Therefore, our results indicate that PRL-3 plays a critical role in promoting the whole process of spontaneous metastasis and tumor growth initiation, and that inhibiting PRL-3 will improve malignant tumor therapy.

Anxiety and retrieval inhibition: support for an enhanced inhibition account.

Science.gov (United States)

Nuñez, Mia; Gregory, Josh; Zinbarg, Richard E

2017-02-01

Retrieval inhibition of negative associations is important for exposure therapy for anxiety, but the relationship between memory inhibition and anxiety is not well understood-anxiety could either be associated with enhanced or deficient inhibition. The present study tested these two competing hypotheses by measuring retrieval inhibition of negative stimuli by related neutral stimuli. Non-clinically anxious undergraduates completed measures of trait and state anxiety and completed a retrieval induced forgetting task. Adaptive forgetting varied with state anxiety. Low levels of state anxiety were associated with no evidence for retrieval inhibition for either threatening or non-threatening categories. Participants in the middle tertile of state anxiety scores exhibited retrieval inhibition for non-threatening categories but not for threatening categories. Participants in the highest tertile of state anxiety, however, exhibited retrieval inhibition for both threatening and non-threatening categories with the magnitude of retrieval inhibition being greater for threatening than non-threatening categories. The data are in line with the avoidance aspect of the vigilance-avoidance theory of anxiety and inhibition. Implications for cognitive behavioural therapy practices are discussed.

Albumin-binding of diclofenac and the effect of a site II inhibitor in the aqueous humor of cataract patients with the instillation of diclofenac.

Science.gov (United States)

Osaki, Takashi; Ozaki, Mineo; Takamura, Norito; Ogata, Kenji; Tokunaga, Jin; Setoguchi, Nao; Arimori, Kazuhiko

2014-05-01

Diclofenac instillation has been used widely in cataract surgery to prevent postoperative inflammation. Since diclofenac binds strongly to albumin in the circulation, it does not have a sufficient effect on patients in whom diclofenac binds strongly to albumin in the aqueous humor. A decrease in diclofenac binding and an increase in free diclofenac levels are necessary in these patients. The binding of diclofenac to albumin was investigated in the aqueous humor. In a diclofenac binding assay with albumin in the aqueous humor of individual patients, diclofenac was extracted from aliquots of the aqueous humor, and its total levels were measured using ultra high performance liquid chromatography (UHPLC). Free diclofenac levels were measured using ultrafiltration and UHPLC. The albumin-binding fraction of diclofenac was 0.8 or higher in the aqueous humor of some patients. Ibuprofen significantly inhibited diclofenac binding to site II of albumin in mimic aqueous humor, but not in pooled aqueous humor. This difference may have been due to the weak binding of diclofenac to site II in the pooled aqueous humor. Flurbiprofen was used instead of diclofenac. Flurbiprofen has been shown to bind more strongly than diclofenac to the same site of albumin. Thus, the inhibitory effect of ibuprofen on the binding of flurbiprofen to albumin was investigated in pooled aqueous humor. The results indicated that ibuprofen significantly inhibited the flurbiprofen binding. An effective diclofenac administration method may be established for clinical application by the instillation of an appropriate inhibitor of binding to the albumin site II. Copyright © 2014 John Wiley & Sons, Ltd.

Nitrosoureas inhibit the stathmin-mediated migration and invasion of malignant glioma cells.

Science.gov (United States)

Liang, Xing-Jie; Choi, Yong; Sackett, Dan L; Park, John K

2008-07-01

Malignant gliomas are the most common primary intrinsic brain tumors and are highly lethal. The widespread migration and invasion of neoplastic cells from the initial site of tumor formation into the surrounding brain render these lesions refractory to definitive surgical treatment. Stathmin, a microtubule-destabilizing protein that mediates cell cycle progression, can also regulate directed cell movement. Nitrosoureas, traditionally viewed as DNA alkylating agents, can also covalently modify proteins such as stathmin. We therefore sought to establish a role for stathmin in malignant glioma cell motility, migration, and invasion and determine the effects of nitrosoureas on these cell movement-related processes. Scratch wound-healing recovery, Boyden chamber migration, Matrigel invasion, and organotypic slice invasion assays were performed before and after the down-regulation of cellular stathmin levels and in the absence and presence of sublethal nitrosourea ([1-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea]; CCNU) concentrations. We show that decreases in stathmin expression lead to significant decreases in malignant glioma cell motility, migration, and invasion. CCNU, at a concentration of 10 micromol/L, causes similar significant decreases, even in the absence of any effects on cell viability. The direct inhibition of stathmin by CCNU is likely a contributing factor. These findings suggest that the inhibition of stathmin expression and function may be useful in limiting the spread of malignant gliomas within the brain, and that nitrosoureas may have therapeutic benefits in addition to their antiproliferative effects.

Nitrosoureas Inhibit the Stathmin Mediated Migration and Invasion of Malignant Glioma Cells

Science.gov (United States)

Liang, Xing-Jie; Choi, Yong; Sackett, Dan L.; Park, John K.

2008-01-01

Malignant gliomas are the most common primary intrinsic brain tumors and are highly lethal. The widespread migration and invasion of neoplastic cells from the initial site of tumor formation into the surrounding brain render these lesions refractory to definitive surgical treatment. Stathmin, a microtubule destabilizing protein that mediates cell cycle progression, can also regulate directed cell movement. Nitrosoureas, traditionally viewed as DNA alkylating agents, can also covalently modify proteins such as stathmin. We therefore sought to establish a role for stathmin in malignant glioma cell motility, migration, and invasion and determine the effects of nitrosoureas on these cell movement related processes. Scratch-wound healing recovery, Boyden chamber migration, Matrigel invasion, and organotypic slice invasion assays were performed before and after the down regulation of cellular stathmin levels and in the absence and presence of sub-lethal nitrosourea (CCNU; [1-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea]) concentrations. We demonstrate that decreases in stathmin expression lead to significant decreases in malignant glioma cell motility, migration, and invasion. CCNU, at a concentration of 10 μM, causes similar significant decreases, even in the absence of any effects on cell viability. The direct inhibition of stathmin by CCNU is likely a contributing factor. These findings suggest that the inhibition of stathmin expression and function may be useful in limiting the spread of malignant gliomas within the brain and that nitrosoureas may have therapeutic benefits in addition to their anti-proliferative effects. PMID:18593927

Inhibiting Effect of Nicotinic Acid Hydrazide on Corrosion of Aluminum and Mild Steel in Acidic Medium

Energy Technology Data Exchange (ETDEWEB)

Bhat, J. Ishwara [Mangalore Univ., Karnataka (India); Alva, Vijaya D. P. [Shree Devi Institute of Technology, Karnataka (India)

2014-02-15

The corrosion behavior of aluminum and mild steel in hydrochloric acid medium was studied using a nicotinic acid hydrazide as inhibitor by potentiodynamic polarization, electrochemical impedance spectroscopy technique and gravimetric methods. The effects of inhibitor concentration and temperature were investigated. The experimental results suggested, nicotinic acid hydrazide is a good corrosion inhibitor for both aluminum and mild steel in hydrochloric acid medium and the inhibition efficiency increased with increase in the inhibitor concentration. The polarization studies revealed that nicotinic acid hydrazide exhibits mixed type of inhibition. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the aluminum and mild steel surface and inhibits corrosion by blocking the reaction sites on the surface of aluminum.

Inhibiting Effect of Nicotinic Acid Hydrazide on Corrosion of Aluminum and Mild Steel in Acidic Medium

International Nuclear Information System (INIS)

Bhat, J. Ishwara; Alva, Vijaya D. P.

2014-01-01

The corrosion behavior of aluminum and mild steel in hydrochloric acid medium was studied using a nicotinic acid hydrazide as inhibitor by potentiodynamic polarization, electrochemical impedance spectroscopy technique and gravimetric methods. The effects of inhibitor concentration and temperature were investigated. The experimental results suggested, nicotinic acid hydrazide is a good corrosion inhibitor for both aluminum and mild steel in hydrochloric acid medium and the inhibition efficiency increased with increase in the inhibitor concentration. The polarization studies revealed that nicotinic acid hydrazide exhibits mixed type of inhibition. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the aluminum and mild steel surface and inhibits corrosion by blocking the reaction sites on the surface of aluminum

Porcine deltacoronavirus nsp5 inhibits interferon-β production through the cleavage of NEMO.

Science.gov (United States)

Zhu, Xinyu; Fang, Liurong; Wang, Dang; Yang, Yuting; Chen, Jiyao; Ye, Xu; Foda, Mohamed Frahat; Xiao, Shaobo

2017-02-01

Porcine deltacoronavirus (PDCoV) causes acute enteric disease and mortality in seronegative neonatal piglets. Previously we have demonstrated that PDCoV infection suppresses the production of interferon-beta (IFN-β), while the detailed mechanisms are poorly understood. Here, we demonstrate that nonstructural protein 5 (nsp5) of PDCoV, the 3C-like protease, significantly inhibits Sendai virus (SEV)-induced IFN-β production by targeting the NF-κB essential modulator (NEMO), confirmed by the diminished function of NEMO cleaved by PDCoV. The PDCoV nsp5 cleavage site in the NEMO protein was identified as glutamine 231, and was identical to the porcine epidemic diarrhea virus nsp5 cleavage site, revealing the likelihood of a common target in NEMO for coronaviruses. Furthermore, this cleavage impaired the ability of NEMO to activate the IFN response and downstream signaling. Taken together, our findings reveal PDCoV nsp5 to be a newly identified IFN antagonist and enhance the understanding of immune evasion by deltacoronaviruses. Copyright © 2016 Elsevier Inc. All rights reserved.

Curcumin Inhibits Tau Aggregation and Disintegrates Preformed Tau Filaments in vitro.

Science.gov (United States)

Rane, Jitendra Subhash; Bhaumik, Prasenjit; Panda, Dulal

2017-01-01

The pathological aggregation of tau is a common feature of most of the neuronal disorders including frontotemporal dementia, Parkinson's disease, and Alzheimer's disease. The inhibition of tau aggregation is considered to be one of the important strategies for treating these neurodegenerative diseases. Curcumin, a natural polyphenolic molecule, has been reported to have neuroprotective ability. In this work, curcumin was found to bind to adult tau and fetal tau with a dissociation constant of 3.3±0.4 and 8±1 μM, respectively. Molecular docking studies indicated a putative binding site of curcumin in the microtubule-binding region of tau. Using several complementary techniques, including dynamic light scattering, thioflavin S fluorescence, 90° light scattering, electron microscopy, and atomic force microscopy, curcumin was found to inhibit the aggregation of tau. The dynamic light scattering analysis and atomic force microscopic images revealed that curcumin inhibits the oligomerization of tau. Curcumin also disintegrated preformed tau oligomers. Using Far-UV circular dichroism, curcumin was found to inhibit the β-sheets formation in tau indicating that curcumin inhibits an initial step of tau aggregation. In addition, curcumin inhibited tau fibril formation. Furthermore, the effect of curcumin on the preformed tau filaments was analyzed by atomic force microscopy, transmission electron microscopy, and 90° light scattering. Curcumin treatment disintegrated preformed tau filaments. The results indicated that curcumin inhibited the oligomerization of tau and could disaggregate tau filaments.

Synthetic secoisolariciresinol diglucoside (LGM2605) inhibits myeloperoxidase activity in inflammatory cells.

Science.gov (United States)

Mishra, Om P; Popov, Anatoliy V; Pietrofesa, Ralph A; Nakamaru-Ogiso, Eiko; Andrake, Mark; Christofidou-Solomidou, Melpo

2018-06-01

Myeloperoxidase (MPO) generates hypochlorous acid (HOCl) during inflammation and infection. We showed that secoisolariciresinol diglucoside (SDG) scavenges radiation-induced HOCl in physiological solutions. However, the action of SDG and its synthetic version, LGM2605, on MPO-catalyzed generation of HOCl is unknown. The present study evaluated the effect of LGM2605 on human MPO, and murine MPO from macrophages and neutrophils. MPO activity was determined fluorometrically using hypochlorite-specific 3'-(p-aminophenyl) fluorescein (APF). The effect of LGM2605 on (a) the peroxidase cycle of MPO was determined using Amplex Red while the effect on (b) the chlorination cycle was determined using a taurine chloramine assay. Using electron paramagnetic resonance (EPR) spectroscopy we determined the effect of LGM2605 on the EPR signals of MPO. Finally, computational docking of SDG was used to identify energetically favorable docking poses to enzyme's active site. LGM2605 inhibited human and murine MPO activity. MPO inhibition was observed in the absence and presence of Cl - . EPR confirmed that LGM2605 suppressed the formation of Compound I, an oxoiron (IV) intermediate [Fe(IV)O] containing a porphyrin π-radical of MPO's catalytic cycle. Computational docking revealed that SDG can act as an inhibitor by binding to the enzyme's active site. We conclude that LGM2605 inhibits MPO activity by suppressing both the peroxidase and chlorination cycles. EPR analysis demonstrated that LGM2605 inhibits MPO by decreasing the formation of the highly oxidative Compound I. This study identifies a novel mechanism of LGM2605 action as an inhibitor of MPO and indicates that LGM2605 may be a promising attenuator of oxidant-dependent inflammatory tissue damage. Copyright © 2018 Elsevier B.V. All rights reserved.

The reciprocal iso-inhibition volume concept: A procedure for the evaluation in effect-directed analysis with thin-layer chromatography - using the thin-layer chromatography-luminescent bacteria assay as an example.

Science.gov (United States)

Schulz, Wolfgang; Weiss, Stefan C; Weber, Walter H; Winzenbacher, Rudi

2017-10-13

In effect-directed analysis (EDA) with high-performance thin-layer chromatography (HPTLC), the effect is often detected using images. Thus, an approach to create inhibition chromatograms from these images was developed using the example of the HPTLC- bioluminescence inhibition test. A comparison between the cuvette test and the HPTLC test shows that the test on the plate is significantly more sensitive. To describe the strength of the effect, the EC 50 value is determined from the dose-response relationship. However, the inhibiting compounds are generally unknown and thus their concentrations are also unknown. Therefore, instead of the concentration, the known application volumes are used. This enables the calculation of the application volume necessary to achieve 50% inhibition. Since the volume is inversely proportional to the concentration, the reciprocal value of the calculated volume is indicated and is referred to as the reciprocal iso-inhibition volume (RIV). Using this RIV-concept, it is now possible to compare inhibition bands within and between plates. The entire evaluation is described by the means of two samples from a contaminated site using the bioluminescence inhibition. Copyright © 2017 Elsevier B.V. All rights reserved.

High Concentrations of Tranexamic Acid Inhibit Ionotropic Glutamate Receptors.

Science.gov (United States)

Lecker, Irene; Wang, Dian-Shi; Kaneshwaran, Kirusanthy; Mazer, C David; Orser, Beverley A

2017-07-01

The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors. Tranexamic acid modulation of NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptors was studied using whole cell voltage-clamp recordings of current from cultured mouse hippocampal neurons. Tranexamic acid rapidly and reversibly inhibited NMDA receptors (half maximal inhibitory concentration = 241 ± 45 mM, mean ± SD; 95% CI, 200 to 281; n = 5) and shifted the glycine concentration-response curve for NMDA-evoked current to the right. Tranexamic acid also inhibited α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (half maximal inhibitory concentration = 231 ± 91 mM; 95% CI, 148 to 314; n = 5 to 6) and kainate receptors (half maximal inhibitory concentration = 90 ± 24 mM; 95% CI, 68 to 112; n = 5). Tranexamic acid inhibits NMDA receptors likely by reducing the binding of the co-agonist glycine and also inhibits α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors. Receptor blockade occurs at high millimolar concentrations of tranexamic acid, similar to the concentrations that occur after topical application to peripheral tissues. Glutamate receptors in tissues including bone, heart, and nerves play various physiologic roles, and tranexamic acid inhibition of these receptors may contribute to adverse drug effects.

Transcriptional and post-transcriptional upregulation of p27 mediates growth inhibition of isorhapontigenin (ISO) on human bladder cancer cells.

Science.gov (United States)

Jiang, Guosong; Huang, Chao; Li, Jingxia; Huang, Haishan; Wang, Jingjing; Li, Yawei; Xie, Fei; Jin, Honglei; Zhu, Junlan; Huang, Chuanshu

2018-03-08

There are few approved drugs available for the treatment of muscle-invasive bladder cancer (MIBC). Recently, we have demonstrated that isorhapontigenin (ISO), a new derivative isolated from the Chinese herb Gnetum cleistostachyum, effectively induces cell-cycle arrest at the G0/G1 phase and inhibits anchorage-independent cell growth through the miR-137/Sp1/cyclin D1 axis in human MIBC cells. Herein, we found that treatment of bladder cancer (BC) cells with ISO resulted in a significant upregulation of p27, which was also observed in ISO-treated mouse BCs that were induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Importantly, knockdown of p27 caused a decline in the ISO-induced G0-G1 growth arrest and reversed ISO suppression of anchorage-independent growth in BC cells. Mechanistic studies revealed that ISO promoted p27 expression at mRNA transcription level through increasing direct binding of forkhead box class O1 (FOXO1) to its promoter, while knockdown of FOXO1 attenuated ISO inhibition of BC cell growth. On the other hand, ISO upregulated the 3'-untranslated region (3'-UTR) activity of p27, which was accompanied by a reduction of miR-182 expression. In line with these observations, ectopic expression of miR-182 significantly blocked p27 3'-UTR activity, whereas mutation of the miR-182-binding site at p27 mRNA 3'-UTR effectively reversed this inhibition. Accordingly, ectopic expression of miR-182 also attenuated ISO upregulation of p27 expression and impaired ISO inhibition of BC cell growth. Our results not only provide novel insight into understanding of the underlying mechanism related to regulation of MIBC cell growth but also identify new roles and mechanisms underlying ISO inhibition of BC cell growth.

Molecular mechanism of pancreatic tumor metastasis inhibition by Gd@C₈₂(OH)₂₂ and its implication for de novo design of nanomedicine

Energy Technology Data Exchange (ETDEWEB)

Kang, S. -g.; Zhou, G.; Yang, P.; Liu, Y.; Sun, B.; Huynh, T.; Meng, H.; Zhao, L.; Xing, G.; Chen, C.; Zhao, Y.; Zhou, R.

2012-09-18

Pancreatic adenocarcinoma is the most lethal of the solid tumors and the fourth-leading cause of cancer-related death in North America. Matrix metalloproteinases (MMPs) have long been targeted as a potential anticancer therapy because of their seminal role in angiogenesis and extracellular matrix (ECM) degradation of tumor survival and invasion. However, the inhibition specificity to MMPs and the molecular-level understanding of the inhibition mechanism remain largely unresolved. Here, we found that endohedral metallofullerenol Gd@C₈₂(OH)₂₂ can successfully inhibit the neoplastic activity with experiments at animal, tissue, and cellular levels. Gd@C₈₂(OH)₂₂ effectively blocks tumor growth in human pancreatic cancer xenografts in a nude mouse model. Enzyme activity assays also show Gd@C₈₂(OH)₂₂ not only suppresses the expression of MMPs but also significantly reduces their activities. We then applied large-scale molecular-dynamics simulations to illustrate the molecular mechanism by studying the Gd@C₈₂(OH)₂₂–MMP-9 interactions in atomic detail. Our data demonstrated that Gd@C₈₂(OH)₂₂ inhibits MMP-9 mainly via an exocite interaction, whereas the well-known zinc catalytic site only plays a minimal role. Steered by nonspecific electrostatic, hydrophobic, and specific hydrogen-bonding interactions, Gd@C₈₂(OH)₂₂ exhibits specific binding modes near the ligand-specificity loop S1', thereby inhibiting MMP-9 activity. Both the suppression of MMP expression and specific binding mode make Gd@C₈₂(OH)₂₂ a potentially more effective nanomedicine for pancreatic cancer than traditional medicines, which usually target the proteolytic sites directly but fail in selective inhibition. Finally, our findings provide insights for de novo design of nanomedicines for fatal diseases such as pancreatic cancer.

Site-directed mutational analysis of structural interactions of low molecule compounds binding to the N-terminal 8 kDa domain of DNA polymerase β

International Nuclear Information System (INIS)

Murakami, Shizuka; Kamisuki, Shinji; Takata, Kei-ichi; Kasai, Nobuyuki; Kimura, Seisuke; Mizushina, Yoshiyuki; Ohta, Keisuke; Sugawara, Fumio; Sakaguchi, Kengo

2006-01-01

We previously reported the mode of inhibition of DNA polymerase β (pol. β) by long chain fatty acids and a bile acid, involving binding analyses to the N-terminal 8-kDa DNA binding domain. Here we describe a site-directed mutational analysis in which the key amino acids (L11, K35, H51, K60, L77, and T79), which are direct interaction sites in the domain, were substituted with K, A, A, A, K, and A, respectively. And their pol. β interactions with a C24-long chain fatty acid, nervonic acid (NA), and a bile acid, lithocholic acid (LCA), were investigated by gel mobility shift assay and NMR spectroscopy. In the case of K35A, there was complete loss of DNA binding activity while K60A hardly has any activity. In contrast the other mutations had no appreciable effects. Thus, K35 and K60 are key amino acid sites for binding to template DNA. The DNA binding activities of L11K, H51A, and T79A as well as the wild type were inhibited by NA to the same extent. T79A demonstrated a disturbed interaction with LCA. 1 H- 15 N HSQC NMR analysis indicated that despite their many similarities, the wild-type and the mutant proteins displayed some significant chemical shift differences. Not only were the substituted amino acid residues three-dimensionally shifted, but some amino acids which are positioned far distant from the key amino acids showed a shift. These results suggest that the interaction surface was significantly distorted with the result that LCA could not bind to the domain. These findings confirm our previous biochemical and 3D structural proposals concerning inhibition by NA and LCA

Characterization of four arginine kinases in the ciliate Paramecium tetraurelia: Investigation on the substrate inhibition mechanism.

Science.gov (United States)

Yano, Daichi; Suzuki, Takaya; Hirokawa, Saki; Fuke, Kyoko; Suzuki, Tomohiko

2017-08-01

The ciliate Paramecium tetraurelia contains four arginine kinase genes (AK1-4). We detected cDNA for only three of the AKs (AK1-3) via PCR. Recombinant AK1-4 were expressed in Escherichia coli and their kinetics parameters determined. AK3 showed typical substrate inhibition toward arginine, and enzymatic activity markedly decreased when arginine concentration increased. This is the first example of substrate inhibition in wild-type phosphagen kinases. To explore the substrate inhibition mechanism, site-directed mutations were generated, targeting the amino acid sequence D-D-S-Q-V at positions 77-81 in P. tetraurelia AK3. Among the mutants, substrate inhibition was lost remarkably in the S79A mutant. In spite of high amino acid sequence identity (91%) between P. tetraurelia AK3 and AK4, the enzymatic activity of AK4 was less by 3% than that of AK3. We noticed that the conservative G298 was unusually replaced by R in P. tetraurelia AK4, and we constructed two mutants, R298G/AK4 and G298R/AK3. Enzymatic activity of the former mutant was comparable with that of the wild-type AK3, whereas that of the latter mutant was dramatically reduced. Thus, we concluded that the significantly low activity of P. tetraurelia AK4 is due to the residue R298. Copyright © 2017 Elsevier B.V. All rights reserved.

Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range.

Science.gov (United States)

Vowles, Tage; Gunnarsson, Bengt; Molau, Ulf; Hickler, Thomas; Klemedtsson, Leif; Björk, Robert G

2017-11-01

One of the most palpable effects of warming in Arctic ecosystems is shrub expansion above the tree line. However, previous studies have found that reindeer can influence plant community responses to warming and inhibit shrubification of the tundra.We revisited grazed (ambient) and ungrazed study plots (exclosures), at the southern as well as the northern limits of the Swedish alpine region, to study long-term grazing effects and vegetation changes in response to increasing temperatures between 1995 and 2011, in two vegetation types (shrub heath and mountain birch forest).In the field layer at the shrub heath sites, evergreen dwarf shrubs had increased in cover from 26% to 49% but were unaffected by grazing. Deciduous dwarf and tall shrubs also showed significant, though smaller, increases over time. At the birch forest sites, the increase was similar for evergreen dwarf shrubs (20-48%) but deciduous tall shrubs did not show the same consistent increase over time as in the shrub heath.The cover and height of the shrub layer were significantly greater in exclosures at the shrub heath sites, but no significant treatment effects were found on species richness or diversity.July soil temperatures and growing season thawing degree days (TDD) were higher in exclosures at all but one site, and there was a significant negative correlation between mean shrub layer height and soil TDD at the shrub heath sites. Synthesis . This study shows that shrub expansion is occurring rapidly in the Scandes mountain range, both above and below the tree line. Tall, deciduous shrubs had benefitted significantly from grazing exclosure, both in terms of cover and height, which in turn lowered summer soil temperatures. However, the overriding vegetation shift across our sites was the striking increase in evergreen dwarf shrubs, which were not influenced by grazing. As the effects of an increase in evergreen dwarf shrubs and more recalcitrant plant litter may to some degree counteract some of

Toxicity of nano-TiO2 on algae and the site of reactive oxygen species production

International Nuclear Information System (INIS)

Li, Fengmin; Liang, Zhi; Zheng, Xiang; Zhao, Wei; Wu, Miao; Wang, Zhenyu

2015-01-01

Highlights: • The growth of two species of algae was inhibited under nano-TiO 2 exposure. • Oxidative stress was one of the mechanisms of toxicity of nano-TiO 2 on algae. • The site of ROS production was the electron transfer chain of chloroplast. - Abstract: Given the extensive use of nanomaterials, they may enter aquatic environments and harm the growth of algae, which are primary producers in an aquatic ecosystem. Thus, the balance of an aquatic ecosystem may be destroyed. In this study, Karenia brevis and Skeletonema costatum were exposed to nano-TiO 2 (anatase, average particle size of 5–10 nm, specific surface area of 210 ± 10 m 2 g −1 ) to assess the effects of nano-TiO 2 on algae. The findings of transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX) and scanning electron microscopy (SEM) demonstrate aggregation of nano-TiO 2 in the algal suspension. Nano-TiO 2 was also found to be inside algal cells. The growth of the two species of algae was inhibited under nano-TiO 2 exposure. The 72 h EC 50 values of nano-TiO 2 to K. brevis and S. costatum were 10.69 and 7.37 mg L −1 , respectively. TEM showed that the cell membrane of K. brevis was destroyed and its organelles were almost undistinguished under nano-TiO 2 exposure. The malondialdehyde (MDA) contents of K. brevis and S. costatum significantly increased compared with those of the control (p < 0.05). Meanwhile, superoxide dismutase (SOD) and catalase activities (CAT) of K. brevis and S. costatum changed in different ways. The reactive oxygen species (ROS) levels in both species were significantly higher than those of the control (p < 0.05). The site of ROS production and accumulation in K. brevis and S. costatum under nano-TiO 2 exposure was explored with the addition of inhibitors of different electron transfer chains. This study indicated that nano-TiO 2 in algal suspensions inhibited the growth of K. brevis and S. costatum. This effect was attributed to oxidative

Inhibition of HIV-1 Integrase gene expression by 10-23 DNAzyme

Indian Academy of Sciences (India)

We have designed three novel DNAzymes, DIN54, DIN116, and DIN152, against HIV-1 Integrase gene using Mfold software and evaluated them for target site cleavage activity on the in vitro transcribed mRNA. All DNAzymes were tested for its inhibition of expression of HIV Integrase protein in the transiently transfected cell ...

Pseudomonas aeruginosa inhibits the growth of Cryptococcus species.

Science.gov (United States)

Rella, Antonella; Yang, Mo Wei; Gruber, Jordon; Montagna, Maria Teresa; Luberto, Chiara; Zhang, Yong-Mei; Del Poeta, Maurizio

2012-06-01

Pseudomonas aeruginosa is a ubiquitous and opportunistic bacterium that inhibits the growth of different microorganisms, including Gram-positive bacteria and fungi such as Candida spp. and Aspergillus fumigatus. In this study, we investigated the interaction between P. aeruginosa and Cryptococcus spp. We found that P. aeruginosa PA14 and, to a lesser extent, PAO1 significantly inhibited the growth of Cryptococcus spp. The inhibition of growth was observed on solid medium by the visualization of a zone of inhibition of yeast growth and in liquid culture by viable cell counting. Interestingly, such inhibition was only observed when P. aeruginosa and Cryptococcus were co-cultured. Minimal inhibition was observed when cell-cell contact was prevented using a separation membrane, suggesting that cell contact is required for inhibition. Using mutant strains of Pseudomonas quinoline signaling, we showed that P. aeruginosa inhibited the growth of Cryptococcus spp. by producing antifungal molecules pyocyanin, a redox-active phenazine, and 2-heptyl-3,4-dihydroxyquinoline (PQS), an extracellular quorum-sensing signal. Because both P. aeruginosa and Cryptococcus neoformans are commonly found in lung infections of immunocompromised patients, this study may have important implication for the interaction of these microbes in both an ecological and a clinical point of view.

Inhibition of platelet [3H]- imipramine binding by human plasma protein fractions

International Nuclear Information System (INIS)

Strijewski, A.; Chudzik, J.; Tang, S.W.

1988-01-01

Inhibition of high-affinity [ 3 H]-imipramine binding to platelet membranes by human plasma fractions and isolated plasma proteins was investigated. Several plasma proteins were found to contribute to the observed apparent inhibition and this contribution was assessed in terms of inhibitor units. Alpha 1 acid glycoprotein, high density and low density lipoprotein, IgG and α 1 -antitrypsin were identified as effective non-specific inhibitors. Alpha-1-acid glycoprotein was confirmed to be the most potent plasma protein inhibitor. Cohn fractions were evaluated for the presence of the postulated endocoid of [ 3 H]-imipramine binding site

Structural basis of kynurenine 3-monooxygenase inhibition.

Science.gov (United States)

Amaral, Marta; Levy, Colin; Heyes, Derren J; Lafite, Pierre; Outeiro, Tiago F; Giorgini, Flaviano; Leys, David; Scrutton, Nigel S

2013-04-18

Inhibition of kynurenine 3-monooxygenase (KMO), an enzyme in the eukaryotic tryptophan catabolic pathway (that is, kynurenine pathway), leads to amelioration of Huntington's-disease-relevant phenotypes in yeast, fruitfly and mouse models, as well as in a mouse model of Alzheimer's disease. KMO is a flavin adenine dinucleotide (FAD)-dependent monooxygenase and is located in the outer mitochondrial membrane where it converts l-kynurenine to 3-hydroxykynurenine. Perturbations in the levels of kynurenine pathway metabolites have been linked to the pathogenesis of a spectrum of brain disorders, as well as cancer and several peripheral inflammatory conditions. Despite the importance of KMO as a target for neurodegenerative disease, the molecular basis of KMO inhibition by available lead compounds has remained unknown. Here we report the first crystal structure of Saccharomyces cerevisiae KMO, in the free form and in complex with the tight-binding inhibitor UPF 648. UPF 648 binds close to the FAD cofactor and perturbs the local active-site structure, preventing productive binding of the substrate l-kynurenine. Functional assays and targeted mutagenesis reveal that the active-site architecture and UPF 648 binding are essentially identical in human KMO, validating the yeast KMO-UPF 648 structure as a template for structure-based drug design. This will inform the search for new KMO inhibitors that are able to cross the blood-brain barrier in targeted therapies against neurodegenerative diseases such as Huntington's, Alzheimer's and Parkinson's diseases.

Site Closure Strategy Model for Creosote Site

International Nuclear Information System (INIS)

Coll, F.R.; Gray, D.R.

2009-01-01

In conjunction with RCRA site corrective action at an active wood preserving facility, a risk-based site closure strategy was developed and incorporated the performance of a dense non-aqueous phase liquid (DNAPL) source recovery remedy, a monitored natural attenuation (MNA) remedy for dissolved phase groundwater, and institutional controls. Innovative creosote DNAPL source recovery has been undertaken at the Site since 1998. Pooled creosote DNAPL is present 90 feet below ground within a transmissive sand and gravel aquifer with a saturated thickness of approximately 80 feet. The creosote DNAPL source is situated on the property boundary of the site and has generated a 1/2 mile off-site dissolved phase plume, creating significant NAPL management and remedial technology verification issues. To date, over 120,000 gallons of creosote DNAPL have been recovered from the subsurface utilizing a modified circulation well technology. A mass discharge flux protocol was developed to serve as a major performance metrics for the continuation of source removal efforts and to support the application of monitored natural attenuation as an associated remedial technology for groundwater. The mass removal success has supported the MNA remedy for dissolved phase groundwater and the associated development of institutional controls. The enacted site management strategy outlines the current and future risk management activities for the Site and represents an appropriate site closure strategy for the Site. (authors)

Prostaglandin A1 metabolism and inhibition of cyclic AMP extrusion by avian erythrocytes

International Nuclear Information System (INIS)

Heasley, L.E.; Brunton, L.L.

1985-01-01

Prostaglandins (PG) inhibit active cyclic AMP export from pigeon red cells, PGA1 and PGA2 most potently. To probe the mechanism of this action of PGA1, the authors have studied the interaction of [ 3 H]PGA1 with suspensions of pigeon red cells. The interaction of PGA1 with pigeon red cells is a multistep process of uptake, metabolism, and secretion. [ 3 H] PGA1 rapidly enters red cells and is promptly metabolized to a compound(s) that remains in the aqueous layer after ethylacetate extraction. The glutathione-depleting agent, diamide, inhibits formation of the PGA1 metabolite. The red cells secrete the polar metabolite of PGA1 by a saturable mechanism that lowered temperatures inhibit. Because uptake and metabolism progress with much greater rates than metabolite secretion, red cells transiently concentrate the polar compound intracellularly. Onset and reversal of inhibition of cyclic AMP export by PGA1 coincide with accumulation and secretion of PGA1 metabolite, suggesting that the polar metabolite acts at an intracellular site to inhibit cyclic AMP efflux

N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor.

Science.gov (United States)

Zhang, Hao; Jing, Xigang; Shi, Yang; Xu, Hao; Du, Jianhai; Guan, Tongju; Weihrauch, Dorothee; Jones, Deron W; Wang, Weiling; Gourlay, David; Oldham, Keith T; Hillery, Cheryl A; Pritchard, Kirkwood A

2013-11-01

Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (≤4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HOCl generation by phorbol myristate acetate (PMA)-stimulated neutrophils and human promyelocytic leukemia (HL-60) cells but not superoxide generation by PMA-stimulated HL-60 cells. KYC inhibits MPO-mediated HOCl formation in BAEC culture and protects BAECs from MPO-induced injury. KYC inhibits MPO-mediated lipid peroxidation of LDL whereas tyrosine (Tyr) and tryptophan (Trp) enhance oxidation. KYC is unique as its isomers do not inhibit MPO activity, or are much less effective. Ultraviolet-visible spectral studies indicate KYC binds to the active site of MPO and reacts with compounds I and II. Docking studies show the Tyr of KYC rests just above the heme of MPO. Interestingly, KYC increases MPO-dependent H₂O₂ consumption. These data indicate KYC is a novel and specific inhibitor of MPO activity that is nontoxic to endothelial cell cultures. Accordingly, KYC may be useful for treating MPO-mediated vascular disease.

The Nizhegorodsky Kremlin Armory, a Cultural Heritage Site of Federal Significance. Restoration and Adjustment for the Volgo-Vyatsky Branch of the State Center of Modern Art (2004-2014

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Anna Gor

2016-10-01

Full Text Available The article observes the peculiarities of the realized restoration of the Nizhegorodsky Kremlin Armory, a cultural heritage site of federal significance. The restoration concept was based on the principles of scientificity and authenticity. Its purpose was to retain the parameters and historical look of the Armory, as well as its aesthetic and historical value as much as possible, causing the least interference in the historical material of the site. The article demonstrates the appropriateness of restoration and all design decisions, which made it possible to reveal the historical and cultural value of the site, to improve its maintenance, to provide conditions for modern use of the building, and to make the cultural heritage site available to the public.

Application for Permit to Operate a Class III Solid Waste Disposal Site at the Nevada Test Site - U10c Disposal Site

Energy Technology Data Exchange (ETDEWEB)

NSTec Environmental Programs

2010-08-05

The NTS is located approximately 105 km (65 mi) northwest of Las Vegas, Nevada. NNSA/NSO is the federal lands management authority for the NTS and NSTec is the Management & Operations contractor. Access on and off the NTS is tightly controlled, restricted, and guarded on a 24-hour basis. The NTS is posted with signs along its entire perimeter. NSTec is the operator of all solid waste disposal sites on the NTS. The U10C Disposal Site is located in the northwest corner of Area 9 at the NTS (Figure 1) and is located in a subsidence crater created by two underground nuclear events, one in October 1962 and another in April 1964. The disposal site opened in 1971 for the disposal of rubbish, refuse, pathological waste, asbestos-containing material, and industrial solid waste. A Notice of Intent form to operate the disposal site as a Class II site was submitted to the state of Nevada on January 26, 1994, and was acknowledged in a letter to the DOE on February 8, 1994. It operated as a state of Nevada Class II Solid Waste Disposal Site (SWDS) until it closed on October 5, 1995, for retrofit as a Class III SWDS. The retrofit consisted of the installation of a minimum four-foot compacted soil layer to segregate the different waste types and function as a liner to inhibit leachate and water flow into the lower waste zone. Five neutron monitoring tubes were installed in this layer to monitor possible leachate production and water activity. Upon acceptance of the installed barrier and approval of an Operating Plan by NDEP/BFF, the site reopened in January 1996 as a Class III SWDS for the disposal of industrial solid waste and other inert waste.

Anxiety Impacts Cognitive Inhibition in Remitted Anorexia Nervosa.

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Ely, Alice V; Wierenga, Christina E; Kaye, Walter H

2016-07-01

Eating disorders are complex psychiatric disorders, associated with alterations in neural and cognitive functioning. Research suggests inhibition and set-shifting deficits in anorexia nervosa (AN), but less is known about the persistence of these deficits after recovery, or their relationship to comorbid psychiatric symptoms. Women aged 19-45 remitted from AN (RAN, N = 47) and controls (CW, N = 24) completed the Delis-Kaplan Executive Function System Color-Word Interference Test. It was hypothesized that RAN, and those with higher anxiety or depression, would demonstrate worse Inhibition and Switching task performance than CW. Differences in performance between groups trended toward significance on Inhibition Ratio (p = 0.08) but were nonsignificant on Inhibition/Switching Ratio (p = 0.93). A model including State Anxiety and diagnosis revealed a significant independent effect of State Anxiety (p = 0.026), but not of diagnosis nor their interaction. Regressing State Anxiety on Color-Word Interference Test Inhibition among just the RAN group was significant [β = 0.37, t(46) = 2.63, p = 0.012] but among just CW was not (p = 0.54). Interference control for neutral stimuli is influenced by anxiety in women with a history of AN. Anxiety is linked with greater symptom severity among AN individuals, and state anxiety may account for larger deficits seen on tasks using disorder-specific stimuli. Future research is warranted to elucidate the nature of neuropsychological deficits in eating disorders. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Arctigenin, a phenylpropanoid dibenzylbutyrolactone lignan, inhibits type I-IV allergic inflammation and pro-inflammatory enzymes.

Science.gov (United States)

Lee, Ji Yun; Kim, Chang Jong

2010-06-01

We previously reported that arctigenin, a phenylpropanoid dibenzylbutyrolactone lignan isolated from Forsythia koreana, exhibits anti-inflammatory, antioxidant, and analgesic effects in animal models. In addition, arctigenin inhibited eosinophil peroxidase and activated myeloperoxidase in inflamed tissues. In this study, we tested the effects of arctigenin on type I-IV allergic inflammation and pro-inflammatory enzymes in vitro and in vivo. Arctigenin significantly inhibited the heterologous passive cutaneous anaphylaxis induced by ovalbumin in mice at 15 mg/kg, p.o., and compound 48/80-induced histamine release from rat peritoneal mast cells at 10 microM. Arctigenin (15 mg/kg, p.o.) significantly inhibited reversed cutaneous anaphylaxis. Further, arctigenin (15 mg/kg, p.o.) significantly inhibited the Arthus reaction to sheep's red blood cells, decreasing the hemolysis titer, the hemagglutination titer, and the plaque-forming cell number for SRBCs. In addition, arctigenin significantly inhibited delayed type hypersensitivity at 15 mg/kg, p.o. and the formation of rosette-forming cells at 45 mg/kg, p.o. Contact dermatitis induced by picrylchloride and dinitrofluorobenzene was significantly (p arctigenin (0.3 mg/ear). Furthermore, arctigenin dose-dependently inhibited pro-inflammatory enzymes, such as cyclooxygenase-1 and 2, 5-lipoxygenase, phospholipase A2, and phosphodiesterase. Our results show that arctigenin significantly inhibited B- and T-cell mediated allergic inflammation as well as pro-inflammatory enzymes.

Increased expression of microRNA-221 inhibits PAK1 in endothelial progenitor cells and impairs its function via c-Raf/MEK/ERK pathway

International Nuclear Information System (INIS)

Zhang, Xiaoping; Mao, Haian; Chen, Jin-yuan; Wen, Shengjun; Li, Dan; Ye, Meng; Lv, Zhongwei

2013-01-01

Highlights: ► MicroRNA-221 is upregulated in the endothelial progenitor cells of atherosclerosis patients. ► PAK1 is a direct target of microRNA-221. ► MicroRNA-221 inhibits EPCs proliferation through c-Raf/MEK/ERK pathway. -- Abstract: Coronary artery disease (CAD) is associated with high mortality and occurs via endothelial injury. Endothelial progenitor cells (EPCs) restore the integrity of the endothelium and protect it from atherosclerosis. In this study, we compared the expression of microRNAs (miRNAs) in EPCs in atherosclerosis patients and normal controls. We found that miR-221 expression was significantly up-regulated in patients compared with controls. We predicted and identified p21/Cdc42/Rac1-activated kinase 1 (PAK1) as a novel target of miR-221 in EPCs. We also demonstrated that miR-221 targeted a putative binding site in the 3′UTR of PAK1, and absence of this site was inversely associated with miR-221 expression in EPCs. We confirmed this relationship using a luciferase reporter assay. Furthermore, overexpression of miR-221 in EPCs significantly decreased EPC proliferation, in accordance with the inhibitory effects induced by decreased PAK1. Overall, these findings demonstrate that miR-221 affects the MEK/ERK pathway by targeting PAK1 to inhibit the proliferation of EPCs

Specificity of cellular DNA-binding sites of microbial populations in a Florida reservoir

International Nuclear Information System (INIS)

Paul, J.H.; Pichard, S.L.

1989-01-01

The substrate specificity of the DNA-binding mechanism(s) of bacteria in a Florida reservoir was investigated in short- and long-term uptake studies with radiolabeled DNA and unlabeled competitors. Thymine oligonucleotides ranging in size from 2 base pairs to 19 to 24 base pairs inhibited DNA binding in 20-min incubations by 43 to 77%. Deoxynucleoside monophosphates, thymidine, and thymine had little effect on short-term DNA binding, although several of these compounds inhibited the uptake of the radiolabel from DNA in 4-h incubations. Inorganic phosphate and glucose-1-phosphate inhibited neither short- nor long-term binding of [ 3 H]- or [ 32 P]DNA, indicating that DNA was not utilized as a phosphorous source in this reservoir. RNA inhibited both short- and long-term radiolabeled DNA uptake as effectively as unlabeled DNA. Collectively these results indicate that aquatic bacteria possess a generalized nuclei acid uptake/binding mechanism specific for compounds containing phosphodiester bonds and capable of recognizing oligonucleotides as short as dinucleotides. This binding site is distinct from nucleoside-, nucleotide-, phosphomonoester-, and inorganic phosphate-binding sites. Such a nucleic acid-binding mechanism may have evolved for the utilization of extracellular DNA (and perhaps RNA), which is abundant in many marine and freshwater environments

Madecassoside Inhibits Melanin Synthesis by Blocking Ultraviolet-Induced Inflammation

Directory of Open Access Journals (Sweden)

Eunsun Jung

2013-12-01

Full Text Available Madecassoside (MA, a pentacyclic triterpene isolated from Centella asitica (L., is used as a therapeutic agent in wound healing and also as an anti-inflammatory and anti-aging agent. However, the involvement of MA in skin-pigmentation has not been reported. This study was conducted to investigate the effects of MA on ultraviolet (UV-induced melanogenesis and mechanisms in a co-culture system of keratinocytes and melanocytes. MA significantly inhibited UVR-induced melanin synthesis and melanosome transfer in the co-culture system. These effects were further demonstrated by the MA-induced inhibition of protease-activated receptor-2 expression and its signaling pathway, cyclooxygenase-2, prostaglandin E2 and prostaglandin F2 alpha in keratinocytes. The clinical efficacy of MA was confirmed on artificially tanned human skin. MA significantly reduced UV-induced melanin index at 8 weeks after topical application. Overall, the study demonstrated significant benefits of MA use in the inhibition of hyperpigmentation caused by UV irradiation.

Two classes of ouabain binding sites in ferret heart and two forms of Na+-K+-ATPase

Energy Technology Data Exchange (ETDEWEB)

Ng, Y.C.; Akera, T.

1987-05-01

In partially purified Na+-K+-adenosinetriphosphatase (ATPase) obtained from ferret heart, ouabain produced a monophasic inhibition curve; however, the curve spanned over 5 logarithmic units, indicating the presence of more than one classes of enzyme. (/sup 3/H)ouabain binding studies revealed high-and low-affinity binding sites in approximately equal abundance, with apparent dissociation constants of 10 and 230 nM, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of phosphoenzyme formed from (gamma-/sup 32/P)ATP showed two distinct K+-sensitive bands of approximately 100,000 molecular weight. Phosphoenzyme formation from the high-molecular-weight alpha(+) form was selectively inhibited by N-ethylmaleimide. Ouabain caused a 50% inhibition of phosphorylation of the alpha(+) form at 40 nM and the lower-molecular-weight alpha form at 300 nM. In papillary muscle preparations, 1-30 nM ouabain produced a modest positive inotropic effect that reached an apparent plateau at 30 nM. Further increases in ouabain concentrations, however, produced additional and prominent inotropic effects at 0.1-10 microM. These results indicate for the first time in cardiac muscle that the high- and low-affinity ouabain binding sites are associated with the alpha(+) and alpha forms of the Na+-K+-ATPase, respectively, and that binding of ouabain to either of these sites causes enzyme inhibition and the positive inotropic effect.

Significance of Cuscutain, a cysteine protease from Cuscuta reflexa, in host-parasite interactions

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Fuchsbauer Hans-Lothar

2010-10-01

Full Text Available Abstract Background Plant infestation with parasitic weeds like Cuscuta reflexa induces morphological as well as biochemical changes in the host and the parasite. These modifications could be caused by a change in protein or gene activity. Using a comparative macroarray approach Cuscuta genes specifically upregulated at the host attachment site were identified. Results One of the infestation specific Cuscuta genes encodes a cysteine protease. The protein and its intrinsic inhibitory peptide were heterologously expressed, purified and biochemically characterized. The haustoria specific enzyme was named cuscutain in accordance with similar proteins from other plants, e.g. papaya. The role of cuscutain and its inhibitor during the host parasite interaction was studied by external application of an inhibitor suspension, which induced a significant reduction of successful infection events. Conclusions The study provides new information about molecular events during the parasitic plant - host interaction. Inhibition of cuscutain cysteine proteinase could provide means for antagonizing parasitic plants.

Advanced Glycation End Products Inhibit the Proliferation of Human Umbilical Vein Endothelial Cells by Inhibiting Cathepsin D

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Yuan Li

2017-02-01

Full Text Available We aimed to investigate the effect of advanced glycation end products (AGEs on the proliferation and migration ability of human umbilical vein endothelial cells (HUVECs. Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT assay, real-time cell analyzer and 5-Ethynyl-2′-deoxyuridine (EdU staining. Cell migration was detected by wound-healing and transwell assay. AGEs significantly inhibited the proliferation and migration of HUVECs in a time-and dose-dependent way. Western blotting revealed that AGEs dramatically increased the expression of microtubule-associated protein 1 light chain 3 (LC3 II/I and p62. Immunofluorescence of p62 and acridine orange staining revealed that AGEs significantly increased the expression of p62 and the accumulation of autophagic vacuoles, respectively. Chloroquine (CQ could further promote the expression of LC3 II/I and p62, increase the accumulation of autophagic vacuoles and promote cell injury induced by AGEs. In addition, AGEs reduced cathepsin D (CTSD expression in a time-dependent way. Overexpression of wild-type CTSD significantly decreased the ratio of LC 3 II/I as well as p62 accumulation induced by AGEs, but overexpression of catalytically inactive mutant CTSD had no such effects. Only overexpression of wild-type CTSD could restore the proliferation of HUVECs inhibited by AGEs. However, overexpression of both wild-type CTSD and catalytically inactive mutant CTSD could promote the migration of HUVECs inhibited by AGEs. Collectively, our study found that AGEs inhibited the proliferation and migration in HUVECs and promoted autophagic flux, which in turn played a protective role against AGEs-induced cell injury. CTSD, in need of its catalytic activity, may promote proliferation in AGEs-treated HUVECs independent of the autophagy-lysosome pathway. Meanwhile, CTSD could improve the migration of AGEs-treated HUVECs regardless of its enzymatic activity.

Advanced Glycation End Products Inhibit the Proliferation of Human Umbilical Vein Endothelial Cells by Inhibiting Cathepsin D.

Science.gov (United States)

Li, Yuan; Chang, Ye; Ye, Ning; Dai, Dongxue; Chen, Yintao; Zhang, Naijin; Sun, Guozhe; Sun, Yingxian

2017-02-17

We aimed to investigate the effect of advanced glycation end products (AGEs) on the proliferation and migration ability of human umbilical vein endothelial cells (HUVECs). Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay, real-time cell analyzer and 5-Ethynyl-2'-deoxyuridine (EdU) staining. Cell migration was detected by wound-healing and transwell assay. AGEs significantly inhibited the proliferation and migration of HUVECs in a time-and dose-dependent way. Western blotting revealed that AGEs dramatically increased the expression of microtubule-associated protein 1 light chain 3 (LC3) II/I and p62. Immunofluorescence of p62 and acridine orange staining revealed that AGEs significantly increased the expression of p62 and the accumulation of autophagic vacuoles, respectively. Chloroquine (CQ) could further promote the expression of LC3 II/I and p62, increase the accumulation of autophagic vacuoles and promote cell injury induced by AGEs. In addition, AGEs reduced cathepsin D (CTSD) expression in a time-dependent way. Overexpression of wild-type CTSD significantly decreased the ratio of LC 3 II/I as well as p62 accumulation induced by AGEs, but overexpression of catalytically inactive mutant CTSD had no such effects. Only overexpression of wild-type CTSD could restore the proliferation of HUVECs inhibited by AGEs. However, overexpression of both wild-type CTSD and catalytically inactive mutant CTSD could promote the migration of HUVECs inhibited by AGEs. Collectively, our study found that AGEs inhibited the proliferation and migration in HUVECs and promoted autophagic flux, which in turn played a protective role against AGEs-induced cell injury. CTSD, in need of its catalytic activity, may promote proliferation in AGEs-treated HUVECs independent of the autophagy-lysosome pathway. Meanwhile, CTSD could improve the migration of AGEs-treated HUVECs regardless of its enzymatic activity.

Site-specific effects of the nonsteroidal anti-inflammatory drug lysine clonixinate on rat brain opioid receptors.

Science.gov (United States)

Ortí, E; Coirini, H; Pico, J C

1999-04-01

In addition to effects in the periphery through inhibition of prostaglandin synthesis, several lines of evidence suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) act in the central nervous system. The possibility that the central action of NSAIDs involves regulation of opioid receptors was investigated by quantitative autoradiography of mu, delta, and kappa sites in rat brain slices. Increased (p lysine clonixinate. Labeling of delta receptors was lower in the lateral septum, and kappa sites decreased in thalamic nuclei. These effects were not mediated through direct interaction with opioid-binding sites, since receptor-binding assays using rat brain membranes confirmed that clonixinate up to 1 x 10(-4) mol/l does not inhibit mu, delta, and kappa receptor specific binding. Central effects of NSAIDs might, therefore, involve interaction with the opioid receptor system through indirect mechanisms.

Site specific information in site selection

International Nuclear Information System (INIS)

Aeikaes, T.; Hautojaervi, A.

1998-01-01

The programme for the siting of a deep repository for final disposal of spent nuclear fuel was started already in 1983 and is carried out today by Posiva Oy which continues the work started by Teollisuuden Voima Oy. The programme aims at site selection by the end of the year 2000. The programme has progressed in successive interim stages with defined goals. After an early phase for site identification, five sites were selected in 1987 for preliminary site characterisation. Three of these were selected and judged to be best suited for the more detailed characterisation in 1992. An additional new site was included into the programme based on a separate feasibility study in the beginning of 1997. Since the year 1983 several safety assessments together with technical plans of the facility have been completed. When approaching the site selection the needs for more detailed consideration of the site specific properties in the safety assessment have been increased. The Finnish regulator STUK has published a proposal for general safety requirements for the final disposal of spent nuclear fuel in Finland. This set of requirements has been projected to be used in conjunction of the decision making by the end 2000. Based on the site evaluation all sites can provide a stable environment and there is evidence that the requirements for the longevity of the canister can be fulfilled at each site. In this manner the four candidate sites do not differ too much from each other. The main difference between the sites is in the salinity of the deep groundwater. The significance of differences in the salinity for the long-term safety cannot be defined yet. The differences may contribute to the discussion of the longevity of the bentonite buffer and also to the modelling of the groundwater flow and transport. The use of the geosphere as a transport barrier is basically culminated on the questions about sparse but fast flow routes and 'how bad channeling can be'. To answer these questions

Interactions of dopaminergic agonists and antagonists with dopaminergic D3 binding sites in rat striatum. Evidence that [3H]dopamine can label a high affinity agonist-binding state of the D1 dopamine receptor

International Nuclear Information System (INIS)

Leff, S.E.; Creese, I.

1985-01-01

The interactions of dopaminergic agonists and antagonists with 3 H-agonist labeled D3 dopaminergic binding sites of rat striatum have been characterized by radioligand-binding techniques. When the binding of [ 3 H]dopamine and [ 3 H]apomorphine to D2 dopamine receptors is blocked by the inclusion of D2 selective concentrations of unlabeled spiroperidol or domperidone, these ligands appear to label selectively the previously termed D3 binding site. Antagonist/[ 3 H]dopamine competition curves are of uniformly steep slope (nH . 1.0), suggesting the presence of a single D3 binding site. The relative potencies of antagonists to inhibit D3 specific [ 3 H]dopamine binding are significantly correlated with their potencies to block D1 dopamine receptors as measured by the inhibition of both dopamine-stimulated adenylate cyclase and [ 3 H]flupentixol-binding activities. The affinities of agonists to inhibit D3 specific [ 3 H]dopamine binding are also correlated with estimates of these agonists affinities for the high affinity binding component of agonist/[ 3 H]flupentixol competition curves. Both D3 specific [ 3 H] dopamine binding and the high affinity agonist-binding component of dopamine/[ 3 H]flupentixol competition curves show a similar sensitivity to guanine nucleotides. Taken together, these data strongly suggest that the D3 binding site is related to a high affinity agonist-binding state of the D1 dopamine receptor

Structural insights into mechanisms for inhibiting amyloid β42 aggregation by non-catechol-type flavonoids.

Science.gov (United States)

Hanaki, Mizuho; Murakami, Kazuma; Akagi, Ken-ichi; Irie, Kazuhiro

2016-01-15

The prevention of 42-mer amyloid β-protein (Aβ42) aggregation is promising for the treatment of Alzheimer's disease. We previously described the site-specific inhibitory mechanism for Aβ42 aggregation by a catechol-type flavonoid, (+)-taxifolin, targeting Lys16,28 after its autoxidation. In contrast, non-catechol-type flavonoids (morin, datiscetin, and kaempferol) inhibited Aβ42 aggregation without targeting Lys16,28 with almost similar potencies to that of (+)-taxifolin. We herein provided structural insights into their mechanisms for inhibiting Aβ42 aggregation. Physicochemical analyses revealed that their inhibition did not require autoxidation. The (1)H-(15)N SOFAST-HMQC NMR of Aβ42 in the presence of morin and datiscetin revealed the significant perturbation of chemical shifts of His13,14 and Gln15, which were close to the intermolecular β-sheet region, Gln15-Ala21. His13,14 also played a role in radical formation at Tyr10, thereby inducing the oxidation of Met35, which has been implicated in Aβ42 aggregation. These results suggest the direct interaction of morin and datiscetin with the Aβ42 monomer. Although only kaempferol was oxidatively-degraded during incubation, its degradation products as well as kaempferol itself suppressed Aβ42 aggregation. However, neither kaempferol nor its decomposed products perturbed the chemical shifts of the Aβ42 monomer. Aggregation experiments using 1,1,1,3,3,3-hexafluoro-2-propanol-treated Aβ42 demonstrated that kaempferol and its degradation products inhibited the elongation rather than nucleation phase, implying that they interacted with small aggregates of Aβ42, but not with the monomer. In contrast, morin and datiscetin inhibited both phases. The position and number of hydroxyl groups on the B-ring of non-catechol-type flavonoids could be important for their inhibitory potencies and mechanisms against Aβ42 aggregation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of lysine to alanine mutations on the phosphate activation and BPTES inhibition of glutaminase.

Science.gov (United States)

McDonald, Charles J; Acheff, Eric; Kennedy, Ryan; Taylor, Lynn; Curthoys, Norman P

2015-09-01

The GLS1 gene encodes a mitochondrial glutaminase that is highly expressed in brain, kidney, small intestine and many transformed cells. Recent studies have identified multiple lysine residues in glutaminase that are sites of N-acetylation. Interestingly, these sites are located within either a loop segment that regulates access of glutamine to the active site or the dimer:dimer interface that participates in the phosphate-dependent oligomerization and activation of the enzyme. These two segments also contain the binding sites for bis-2[5-phenylacetamido-1,2,4-thiadiazol-2-yl]ethylsulfide (BPTES), a highly specific and potent uncompetitive inhibitor of this glutaminase. BPTES is also the lead compound for development of novel cancer chemotherapeutic agents. To provide a preliminary assessment of the potential effects of N-acetylation, the corresponding lysine to alanine mutations were constructed in the hGACΔ1 plasmid. The wild type and mutated proteins were purified by Ni(+)-affinity chromatography and their phosphate activation and BPTES inhibition profiles were analyzed. Two of the alanine substitutions in the loop segment (K311A and K328A) and the one in the dimer:dimer interface (K396A) form enzymes that require greater concentrations of phosphate to produce half-maximal activation and exhibit greater sensitivity to BPTES inhibition. By contrast, the K320A mutation results in a glutaminase that exhibits near maximal activity in the absence of phosphate and is not inhibited by BPTES. Thus, lysine N-acetylation may contribute to the acute regulation of glutaminase activity in various tissues and alter the efficacy of BPTES-type inhibitors. Copyright © 2014 Elsevier Ltd. All rights reserved.

A chimeric peptide of intestinal trefoil factor containing cholesteryl ester transfer protein B cell epitope significantly inhibits atherosclerosis in rabbits after oral administration.

Science.gov (United States)

Qi, Gaofu; Li, Jingjing; Wang, Shengying; Xin, Shanshan; Du, Peng; Zhang, Qingye; Zhao, Xiuyun

2011-04-01

Vaccination against cholesteryl ester transfer protein (CETP) is proven to be effective for inhibiting atherosclerosis in animal models. In this study, the proteases-resistant intestinal trefoil factor (TFF3) was used as a molecular vehicle to construct chimeric TFF3 (cTFF3) containing CETP B cell epitope and tetanus toxin helper T cell epitope. It was found that cTFF3 still preserved a trefoil structure, and can resist proteases digestion in vitro. After oral immunization with cTFF3, the CETP-specific IgA and IgG could be found in intestine lavage fluid and serum, and the anti-CETP antibodies could inhibit partial CETP activity to increase high-density lipoprotein cholesterol, decrease low-density lipoprotein cholesterol, and inhibit atherosclerosis in animals. Therefore, TFF3 is a potential molecular vehicle for developing oral peptide vaccines. Our research highlights a novel strategy for developing oral peptide vaccines in the future. Copyright © 2010 Elsevier Inc. All rights reserved.

Redox-responsive microbeads containing thiolated pectin-doxorubicin conjugate inhibit tumor growth and metastasis: An in vitro and in vivo study.

Science.gov (United States)

Cheewatanakornkool, Kamonrak; Niratisai, Sathit; Dass, Crispin R; Sriamornsak, Pornsak

2018-07-10

The objective of this study was to investigate the in vitro cytotoxicity and in vivo anticancer efficacy of redox-responsive microbeads containing thiolated pectin-doxorubicin (DOX) conjugate. Oral microbeads were coated with an enteric polymer to protect the drug from release in the upper gastrointestinal (GI) tract and allow redox-triggered drug release in the colon. Morphology, particle size, drug content, and in vitro drug release behavior of the microbeads were characterized; in vitro cytotoxicity was tested on mouse colon carcinoma, human colorectal adenocarcinoma, and human bone osteosarcoma cell lines. In vivo anticancer efficacy of coated microbeads was examined in BALB/c mice with murine colon carcinoma. These coated microbeads significantly inhibited the growth of all cell lines. The in vivo study confirmed delivery of DOX to the colorectal tumor site, redox-responsiveness, and anticancer efficacy of coated microbeads. Coated microbeads also effectively inhibited primary tumor growth and suppressed tumor metastases without gross toxicity to the non-target tissue. No noticeable damage was found in mouse GI tissues, indicating lack of DOX toxicity. These novel coated microbeads containing thiolated pectin-DOX conjugate may be a promising vehicle for targeted clinical delivery of DOX to the colorectal cancer site by oral administration. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Toxicity of nano-TiO{sub 2} on algae and the site of reactive oxygen species production

Energy Technology Data Exchange (ETDEWEB)

Li, Fengmin, E-mail: lifengmin@ouc.edu.cn [Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Technology, Ocean University of China, Qingdao 266100 (China); Liang, Zhi [Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Technology, Ocean University of China, Qingdao 266100 (China); Zheng, Xiang, E-mail: zhengxiang7825@sina.com [School of Environment and Natural Resources, Renmin University of China, Beijing 100872 (China); Zhao, Wei; Wu, Miao; Wang, Zhenyu [Key Laboratory of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Technology, Ocean University of China, Qingdao 266100 (China)

2015-01-15

Highlights: • The growth of two species of algae was inhibited under nano-TiO{sub 2} exposure. • Oxidative stress was one of the mechanisms of toxicity of nano-TiO{sub 2} on algae. • The site of ROS production was the electron transfer chain of chloroplast. - Abstract: Given the extensive use of nanomaterials, they may enter aquatic environments and harm the growth of algae, which are primary producers in an aquatic ecosystem. Thus, the balance of an aquatic ecosystem may be destroyed. In this study, Karenia brevis and Skeletonema costatum were exposed to nano-TiO{sub 2} (anatase, average particle size of 5–10 nm, specific surface area of 210 ± 10 m{sup 2} g{sup −1}) to assess the effects of nano-TiO{sub 2} on algae. The findings of transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX) and scanning electron microscopy (SEM) demonstrate aggregation of nano-TiO{sub 2} in the algal suspension. Nano-TiO{sub 2} was also found to be inside algal cells. The growth of the two species of algae was inhibited under nano-TiO{sub 2} exposure. The 72 h EC{sub 50} values of nano-TiO{sub 2} to K. brevis and S. costatum were 10.69 and 7.37 mg L{sup −1}, respectively. TEM showed that the cell membrane of K. brevis was destroyed and its organelles were almost undistinguished under nano-TiO{sub 2} exposure. The malondialdehyde (MDA) contents of K. brevis and S. costatum significantly increased compared with those of the control (p < 0.05). Meanwhile, superoxide dismutase (SOD) and catalase activities (CAT) of K. brevis and S. costatum changed in different ways. The reactive oxygen species (ROS) levels in both species were significantly higher than those of the control (p < 0.05). The site of ROS production and accumulation in K. brevis and S. costatum under nano-TiO{sub 2} exposure was explored with the addition of inhibitors of different electron transfer chains. This study indicated that nano-TiO{sub 2} in algal suspensions inhibited the growth

Griseofulvin stabilizes microtubule dynamics, activates p53 and inhibits the proliferation of MCF-7 cells synergistically with vinblastine

International Nuclear Information System (INIS)

Rathinasamy, Krishnan; Jindal, Bhavya; Asthana, Jayant; Singh, Parminder; Balaji, Petety V; Panda, Dulal

2010-01-01

Griseofulvin, an antifungal drug, has recently been shown to inhibit proliferation of various types of cancer cells and to inhibit tumor growth in athymic mice. Due to its low toxicity, griseofulvin has drawn considerable attention for its potential use in cancer chemotherapy. This work aims to understand how griseofulvin suppresses microtubule dynamics in living cells and sought to elucidate the antimitotic and antiproliferative action of the drug. The effects of griseofulvin on the dynamics of individual microtubules in live MCF-7 cells were measured by confocal microscopy. Immunofluorescence microscopy, western blotting and flow cytometry were used to analyze the effects of griseofulvin on spindle microtubule organization, cell cycle progression and apoptosis. Further, interactions of purified tubulin with griseofulvin were studied in vitro by spectrophotometry and spectrofluorimetry. Docking analysis was performed using autodock4 and LigandFit module of Discovery Studio 2.1. Griseofulvin strongly suppressed the dynamic instability of individual microtubules in live MCF-7 cells by reducing the rate and extent of the growing and shortening phases. At or near half-maximal proliferation inhibitory concentration, griseofulvin dampened the dynamicity of microtubules in MCF-7 cells without significantly disrupting the microtubule network. Griseofulvin-induced mitotic arrest was associated with several mitotic abnormalities like misaligned chromosomes, multipolar spindles, misegregated chromosomes resulting in cells containing fragmented nuclei. These fragmented nuclei were found to contain increased concentration of p53. Using both computational and experimental approaches, we provided evidence suggesting that griseofulvin binds to tubulin in two different sites; one site overlaps with the paclitaxel binding site while the second site is located at the αβ intra-dimer interface. In combination studies, griseofulvin and vinblastine were found to exert synergistic

Calcite growth-rate inhibition by fulvic acid and magnesium ion—Possible influence on biogenic calcite formation

Science.gov (United States)

Reddy, Michael M.

2012-01-01

Increases in ocean surface water dissolved carbon dioxide (CO2) concentrations retard biocalcification by reducing calcite supersaturation (Ωc). Reduced calcification rates may influence growth-rate dependent magnesium ion (Mg) incorporation into biogenic calcite modifying the use of calcifying organisms as paleoclimate proxies. Fulvic acid (FA) at biocalcification sites may further reduce calcification rates. Calcite growth-rate inhibition by FA and Mg, two common constituents of seawater and soil water involved in the formation of biogenic calcite, was measured separately and in combination under identical, highly reproducible experimental conditions. Calcite growth rates (pH=8.5 and Ωc=4.5) are reduced by FA (0.5 mg/L) to 47% and by Mg (10−4 M) to 38%, compared to control experiments containing no added growth-rate inhibitor. Humic acid (HA) is twice as effective a calcite growth-rate inhibitor as FA. Calcite growth rate in the presence of both FA (0.5 mg/L) and Mg (10−4 M) is reduced to 5% of the control rate. Mg inhibits calcite growth rates by substitution for calcium ion at the growth site. In contrast, FA inhibits calcite growth rates by binding multiple carboxylate groups on the calcite surface. FA and Mg together have an increased affinity for the calcite growth sites reducing calcite growth rates.

Novel nootropic drug sunifiram enhances hippocampal synaptic efficacy via glycine-binding site of N-methyl-D-aspartate receptor.

Science.gov (United States)

Moriguchi, Shigeki; Tanaka, Tomoya; Narahashi, Toshio; Fukunaga, Kohji

2013-10-01

Sunifiram is a novel pyrrolidone nootropic drug structurally related to piracetam, which was developed for neurodegenerative disorder like Alzheimer's disease. Sunifiram is known to enhance cognitive function in some behavioral experiments such as Morris water maze task. To address question whether sunifiram affects N-methyl-D-aspartate receptor (NMDAR)-dependent synaptic function in the hippocampal CA1 region, we assessed the effects of sunifiram on NMDAR-dependent long-term potentiation (LTP) by electrophysiology and on phosphorylation of synaptic proteins by immunoblotting analysis. In mouse hippocampal slices, sunifiram at 10-100 nM significantly enhanced LTP in a bell-shaped dose-response relationship which peaked at 10 nM. The enhancement of LTP by sunifiram treatment was inhibited by 7-chloro-kynurenic acid (7-ClKN), an antagonist for glycine-binding site of NMDAR, but not by ifenprodil, an inhibitor for polyamine site of NMDAR. The enhancement of LTP by sunifilam was associated with an increase in phosphorylation of α-amino-3-hydroxy-5-methylisozazole-4-propionate receptor (AMPAR) through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) and an increase in phosphorylation of NMDAR through activation of protein kinase Cα (PKCα). Sunifiram treatments at 1-1000 nM increased the slope of field excitatory postsynaptic potentials (fEPSPs) in a dose-dependent manner. The enhancement was associated with an increase in phosphorylation of AMPAR receptor through activation of CaMKII. Interestingly, under the basal condition, sunifiram treatments increased PKCα (Ser-657) and Src family (Tyr-416) activities with the same bell-shaped dose-response curve as that of LTP peaking at 10 nM. The increase in phosphorylation of PKCα (Ser-657) and Src (Tyr-416) induced by sunifiram was inhibited by 7-ClKN treatment. The LTP enhancement by sunifiram was significantly inhibited by PP2, a Src family inhibitor. Finally, when pretreated with a high

A new method to characterize the kinetics of cholinesterases inhibited by carbamates.

Science.gov (United States)

Xiao, Qiaoling; Zhou, Huimin; Wei, Hong; Du, Huaqiao; Tan, Wen; Zhan, Yiyi; Pistolozzi, Marco

2017-09-10

The inhibition of cholinesterases (ChEs) by carbamates includes a carbamylation (inhibition) step, in which the drug transfers its carbamate moiety to the active site of the enzyme and a decarbamylation (activity recovery) step, in which the carbamyl group is hydrolyzed from the enzyme. The carbamylation and decarbamylation kinetics decide the extent and the duration of the inhibition, thus the full characterization of candidate carbamate inhibitors requires the measurement of the kinetic constants describing both steps. Carbamylation and decarbamylation rate constants are traditionally measured by two separate set of experiments, thus making the full characterization of candidate inhibitors time-consuming. In this communication we show that by the analysis of the area under the inhibition-time curve of cholinesterases inhibited by carbamates it is possible to calculate the decarbamylation rate constant from the same data traditionally used to characterize only the carbamylation kinetics, therefore it is possible to obtain a full characterization of the inhibition with a single set of experiments. The characterization of the inhibition kinetics of human and dog plasma butyrylcholinesterase and of human acetylcholinesterase by bambuterol and bambuterol monocarbamate enantiomers was used to demonstrate the validity of the approach. The results showed that the proposed method provides reliable estimations of carbamylation and decarbamylation rate constants thus representing a simple and useful approach to reduce the time required for the characterization of carbamate inhibitors. Copyright © 2017 Elsevier B.V. All rights reserved.

Inhibition by etomoxir of rat liver carnitine octanoyltransferase is produced through the co-ordinate interaction with two histidine residues.

Science.gov (United States)

Morillas, M; Clotet, J; Rubí, B; Serra, D; Ariño, J; Hegardt, F G; Asins, G

2000-10-15

Rat peroxisomal carnitine octanoyltransferase (COT), which facilitates the transport of medium-chain fatty acids through the peroxisomal membrane, is irreversibly inhibited by the hypoglycaemia-inducing drug etomoxir. To identify the molecular basis of this inhibition, cDNAs encoding full-length wild-type COT, two different variant point mutants and one variant double mutant from rat peroxisomal COT were expressed in Saccharomyces cerevisiae, an organism devoid of endogenous COT activity. The recombinant mutated enzymes showed activity towards both carnitine and decanoyl-CoA in the same range as the wild type. Whereas the wild-type version expressed in yeast was inhibited by etomoxir in an identical manner to COT from rat liver peroxisomes, the activity of the enzyme containing the double mutation H131A/H340A was completely insensitive to etomoxir. Individual point mutations H131A and H340A also drastically reduced sensitivity to etomoxir. Taken together, these results indicate that the two histidine residues, H131 and H340, are the sites responsible for inhibition by etomoxir and that the full inhibitory properties of the drug will be shown only if both histidines are intact at the same time. Our data demonstrate that both etomoxir and malonyl-CoA inhibit COT by interacting with the same sites.

The development of children's inhibition: does parenting matter?

Science.gov (United States)

Roskam, Isabelle; Stievenart, Marie; Meunier, Jean-Christophe; Noël, Marie-Pascale

2014-06-01

Whereas a large body of research has investigated the maturation of inhibition in relation to the prefrontal cortex, far less research has been devoted to environmental factors that could contribute to inhibition improvement. The aim of the current study was to test whether and to what extent parenting matters for inhibition development from 2 to 8years of age. Data were collected from 421 families, with 348 mother-child dyads and 342 father-child dyads participating. Children's inhibition capacities and parenting behaviors were assessed in a three-wave longitudinal data collection. The main analyses examined the impact of parenting on the development of children's inhibition capacities. They were conducted using a multilevel modeling (MLM) framework. The results lead to the conclusion that both mothers and fathers contribute through their child-rearing behavior to their children's executive functioning, even when controlling for age-related improvement (maturation) and important covariates such as gender, verbal IQ, and place of enrollment. More significant relations between children's inhibition development and parenting were displayed for mothers than for fathers. More precisely, parenting behaviors that involve higher monitoring, lower discipline, inconsistency and negative controlling, and a positive parenting style are associated with good development of inhibition capacities in children. Copyright © 2014 Elsevier Inc. All rights reserved.

Action of insecticidal N-alkylamides at site 2 of the voltage-sensitive sodium channel

International Nuclear Information System (INIS)

Ottea, J.A.; Payne, G.T.; Soderlund, D.M.

1990-01-01

Nine synthetic N-alkylamides were examined as inhibitors of the specific binding of [ 3 H]batrachotoxinin A 20α-benzoate ([ 3 H]BTX-B) to sodium channels and as activators of sodium uptake in mouse brain synaptoneurosomes. In the presence of scorpion (Leiurus quinquestriatus) venom, the six insecticidal analogues were active as both inhibitors of [ 3 H]BTX-B binding and stimulators of sodium uptake. These findings are consistent with an action of these compounds at the alkaloid activator recognition site (site 2) of the voltage-sensitive sodium channel. The three noninsecticidal N-alkylamides also inhibited [ 3 H]BTX-B binding but were ineffective as activators of sodium uptake. Concentration-response studies revealed that some of the insecticidal amides also enhanced sodium uptake through a second, high-affinity interaction that does not involve site 2, but this secondary effect does not appear to be correlated with insecticidal activity. The activities of N-alkylamides as sodium channel activators were influenced by the length of the alkenyl chain and the location of unsaturation within the molecule. These results further define the actions of N-alkylamides on sodium channels and illustrate the significance of the multiple binding domains of the sodium channel as target sites for insect control agents

Dual Inhibition of AChE and BChE with the C-5 Substituted Derivative of Meldrum’s Acid: Synthesis, Structure Elucidation, and Molecular Docking Studies

Directory of Open Access Journals (Sweden)

Haroon Mehfooz

2017-07-01

Full Text Available Alzheimer’s disease (AD lies in the category of those diseases which are still posing challenges to medicinal chemists, and the search for super-effective drugs for the treatment of AD is a work in progress. The inhibition of cholinesterase is considered a viable strategy to enhance the level of acetylcholine in the brain. The C-5 substituted derivative of Meldrum’s acid was synthesized and screened against acetylcholinesterase (AChE and butyrylcholinesterase (BChE enzyme inhibition activity. The simple and unique structure of synthesized derivative 3 was found to be good for the dual inhibition of both enzymes (AChE and BChE. 2,2-Dimethyl-5-(([2-(trifluoromethyl phenyl]aminomethylidene-1,3-dioxane-4,6-dione (3 showed significant inhibition against AChE, with an IC50 value of 1.13 ± 0.03 µ M (Standard Neostigmine 22.2 ± 3.2 µM, and moderate inhibition against BChE, with an IC50 value of 2.12 ± 1.22 µM (Standard Neostigmine 49.6 ± 6.11 µM. The structural insights reveal that compound 3 possesses intriguing reactive groups, which can potentially evoke the non-covalent interactions and possibly assist by binding in the active site of the target protein. Docking simulations revealed that the compound 3 showed binding inside the active site gorges of both AChE and BChE. An excellent agreement was obtained, as the best docked poses showed important binding features mostly based on interactions due to oxygen atoms and the aromatic moieties of the compound. The docking computations coupled with the experimental findings ascertained that the compound 3 can serve as a scaffold for the dual inhibitors of the human acetylcholine esterases.

Inhibition of the immune response to experimental fresh osteoarticular allografts

International Nuclear Information System (INIS)

Rodrigo, J.J.; Schnaser, A.M.; Reynolds, H.M. Jr.; Biggart, J.M. III; Leathers, M.W.; Chism, S.E.; Thorson, E.; Grotz, T.; Yang, Q.M.

1989-01-01

The immune response to osteoarticular allografts is capable of destroying the cartilage--a tissue that has antigens on its cells identical to those on the bone and marrow cells. Osteoarticular allografts of the distal femur were performed in rats using various methods to attempt to temporarily inhibit the antibody response. The temporary systemic immunosuppressant regimens investigated were cyclophosphamide, azathioprine and prednisolone, cyclosporine A, and total lymphoid irradiation. The most successful appeared to be cyclosporine A, but significant side effects were observed. To specifically inhibit the immune response in the allograft antigens without systemically inhibiting the entire immune system, passive enhancement and preadministration of donor blood were tried. Neither was as effective as coating the donor bone with biodegradable cements, a method previously found to be successful. Cyclosporine A was investigated in dogs in a preliminary study of medial compartmental knee allografts and was found to be successful in inhibiting the antibody response and in producing a more successful graft; however, some significant side effects were similarly observed

Confidence assessment. Site-descriptive modelling SDM-Site Laxemar

International Nuclear Information System (INIS)

2009-06-01

The objective of this report is to assess the confidence that can be placed in the Laxemar site descriptive model, based on the information available at the conclusion of the surface-based investigations (SDM-Site Laxemar). In this exploration, an overriding question is whether remaining uncertainties are significant for repository engineering design or long-term safety assessment and could successfully be further reduced by more surface-based investigations or more usefully by explorations underground made during construction of the repository. Procedures for this assessment have been progressively refined during the course of the site descriptive modelling, and applied to all previous versions of the Forsmark and Laxemar site descriptive models. They include assessment of whether all relevant data have been considered and understood, identification of the main uncertainties and their causes, possible alternative models and their handling, and consistency between disciplines. The assessment then forms the basis for an overall confidence statement. The confidence in the Laxemar site descriptive model, based on the data available at the conclusion of the surface based site investigations, has been assessed by exploring: - Confidence in the site characterization data base, - remaining issues and their handling, - handling of alternatives, - consistency between disciplines and - main reasons for confidence and lack of confidence in the model. Generally, the site investigation database is of high quality, as assured by the quality procedures applied. It is judged that the Laxemar site descriptive model has an overall high level of confidence. Because of the relatively robust geological model that describes the site, the overall confidence in the Laxemar Site Descriptive model is judged to be high, even though details of the spatial variability remain unknown. The overall reason for this confidence is the wide spatial distribution of the data and the consistency between

Confidence assessment. Site-descriptive modelling SDM-Site Laxemar

Energy Technology Data Exchange (ETDEWEB)

2008-12-15

The objective of this report is to assess the confidence that can be placed in the Laxemar site descriptive model, based on the information available at the conclusion of the surface-based investigations (SDM-Site Laxemar). In this exploration, an overriding question is whether remaining uncertainties are significant for repository engineering design or long-term safety assessment and could successfully be further reduced by more surface-based investigations or more usefully by explorations underground made during construction of the repository. Procedures for this assessment have been progressively refined during the course of the site descriptive modelling, and applied to all previous versions of the Forsmark and Laxemar site descriptive models. They include assessment of whether all relevant data have been considered and understood, identification of the main uncertainties and their causes, possible alternative models and their handling, and consistency between disciplines. The assessment then forms the basis for an overall confidence statement. The confidence in the Laxemar site descriptive model, based on the data available at the conclusion of the surface based site investigations, has been assessed by exploring: - Confidence in the site characterization data base, - remaining issues and their handling, - handling of alternatives, - consistency between disciplines and - main reasons for confidence and lack of confidence in the model. Generally, the site investigation database is of high quality, as assured by the quality procedures applied. It is judged that the Laxemar site descriptive model has an overall high level of confidence. Because of the relatively robust geological model that describes the site, the overall confidence in the Laxemar Site Descriptive model is judged to be high, even though details of the spatial variability remain unknown. The overall reason for this confidence is the wide spatial distribution of the data and the consistency between

Inhibition of autophagy induced by proteasome inhibition increases cell death in human SHG-44 glioma cells.

Science.gov (United States)

Ge, Peng-Fei; Zhang, Ji-Zhou; Wang, Xiao-Fei; Meng, Fan-Kai; Li, Wen-Chen; Luan, Yong-Xin; Ling, Feng; Luo, Yi-Nan

2009-07-01

The ubiquitin-proteasome system (UPS) and lysosome-dependent macroautophagy (autophagy) are two major intracellular pathways for protein degradation. Recent studies suggest that proteasome inhibitors may reduce tumor growth and activate autophagy. Due to the dual roles of autophagy in tumor cell survival and death, the effect of autophagy on the destiny of glioma cells remains unclear. In this study, we sought to investigate whether inhibition of the proteasome can induce autophagy and the effects of autophagy on the fate of human SHG-44 glioma cells. The proteasome inhibitor MG-132 was used to induce autophagy in SHG-44 glioma cells, and the effect of autophagy on the survival of SHG-44 glioma cells was investigated using an autophagy inhibitor 3-MA. Cell viability was measured by MTT assay. Apoptosis and cell cycle were detected by flow cytometry. The expression of autophagy related proteins was determined by Western blot. MG-132 inhibited cell proliferation, induced cell death and cell cycle arrest at G(2)/M phase, and activated autophagy in SHG-44 glioma cells. The expression of autophagy-related Beclin-1 and LC3-I was significantly up-regulated and part of LC3-I was converted into LC3-II. However, when SHG-44 glioma cells were co-treated with MG-132 and 3-MA, the cells became less viable, but cell death and cell numbers at G(2)/M phase increased. Moreover, the accumulation of acidic vesicular organelles was decreased, the expression of Beclin-1 and LC3 was significantly down-regulated and the conversion of LC3-II from LC3-I was also inhibited. Inhibition of the proteasome can induce autophagy in human SHG-44 glioma cells, and inhibition of autophagy increases cell death. This discovery may shed new light on the effect of autophagy on modulating the fate of SHG-44 glioma cells.Acta Pharmacologica Sinica (2009) 30: 1046-1052; doi: 10.1038/aps.2009.71.

Simvastatin inhibits Candida albicans biofilm in vitro.

Science.gov (United States)

Liu, Geoffrey; Vellucci, Vincent F; Kyc, Stephanie; Hostetter, Margaret K

2009-12-01

By inhibiting the conversion of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) to mevalonate, statins impair cholesterol metabolism in humans. We reasoned that statins might similarly interfere with the biosynthesis of ergosterol, the major sterol of the yeast cell membrane. As assessed by spectrophotometric and microscopic analysis, significant inhibition of biofilm production was noted after 16-h incubation with 1, 2.5, and 5 muM simvastatin, concentrations that did not affect growth, adhesion, or hyphal formation by C. albicans in vitro. Higher concentrations (10, 20, and 25 muM simvastatin) inhibited biofilm by >90% but also impaired growth. Addition of exogenous ergosterol (90 muM) overcame the effects of 1 and 2.5 muM simvastatin, suggesting that at least one mechanism of inhibition is interference with ergosterol biosynthesis. Clinical isolates from blood, skin, and mucosal surfaces produced biofilms; biofilms from bloodstream isolates were similarly inhibited by simvastatin. In the absence of fungicidal activity, simvastatin's interruption of a critical step in an essential metabolic pathway, highly conserved from yeast to man, has unexpected effects on biofilm production by a eukaryotic pathogen.

Okadaic acid inhibits cell growth and photosynthetic electron transport in the alga Dunaliella tertiolecta

Energy Technology Data Exchange (ETDEWEB)

Perreault, Francois; Matias, Marcelo Seleme; Oukarroum, Abdallah [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada); Matias, William Gerson [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada); Laboratorio de Toxicologia Ambiental, LABTOX, Depto. de Engenharia Sanitaria e Ambiental, Universidade Federal de Santa Catarina, Campus Universitario, CEP: 88040-970, Florianopolis, SC (Brazil); Popovic, Radovan, E-mail: popovic.radovan@uqam.ca [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada)

2012-01-01

Okadaic acid (OA), which is produced by several dinoflagellate species, is a phycotoxin known to induce a decrease of biomass production in phytoplankton. However, the mechanisms of OA cytotoxicity are still unknown in microalgae. In this study, we exposed the green microalga Dunaliella tertiolecta to OA concentrations of 0.05 to 0.5 {mu}M in order to evaluate its effects on cell division, reactive oxygen species production and photosynthetic electron transport. After 72 h of treatment under continuous illumination, OA concentrations higher than 0.10 {mu}M decreased culture cell density, induced oxidative stress and inhibited photosystem II electron transport capacity. OA effect in D. tertiolecta was strongly light dependent since no oxidative stress was observed when D. tertiolecta was exposed to OA in the dark. In the absence of light, the effect of OA on culture cell density and photosystem II activity was also significantly reduced. Therefore, light appears to have a significant role in the toxicity of OA in microalgae. Our results indicate that the site of OA interaction on photosynthetic electron transport is likely to be at the level of the plastoquinone pool, which can lead to photo-oxidative stress when light absorbed by the light-harvesting complex of photosystem II cannot be dissipated via photochemical pathways. These findings allowed for a better understanding of the mechanisms of OA toxicity in microalgae. - Highlights: Black-Right-Pointing-Pointer Exposition of Dunaliella tertiolecta to okadaic acid in light conditions results in reactive oxygen species formation. Black-Right-Pointing-Pointer Inhibition of photosystem II is dependent on oxidative stress and effects of okadaic acid on the plastoquinone pool. Black-Right-Pointing-Pointer Oxidative stress and inhibition of photosynthesis increase okadaic acid effect on cell density in light conditions. Black-Right-Pointing-Pointer Okadaic acid induces toxicity in algae via both light-dependent and light

New Developments in 1,4 Dioxane Site Management

Science.gov (United States)

2016-11-01

developed biomarkers to assess aerobic 1,4-dioxane degradation because it may be an important contributor to site-specific natural attenuation capacity...survey corroborate the results of the lab-based research showing that 1,4-dioxane degradation is favored under aerobic conditions but is inhibited by...oxidative attack. In situ oxidation technologies (e.g., chemical oxidation, enhanced aerobic biodegradation) should degrade 1,4-dioxane but each has

Fusion of protegrin-1 and plectasin to MAP30 shows significant inhibition activity against dengue virus replication.

Directory of Open Access Journals (Sweden)

Hussin A Rothan

Full Text Available Dengue virus (DENV broadly disseminates in tropical and sub-tropical countries and there are no vaccine or anti-dengue drugs available. DENV outbreaks cause serious economic burden due to infection complications that requires special medical care and hospitalization. This study presents a new strategy for inexpensive production of anti-DENV peptide-fusion protein to prevent and/or treat DENV infection. Antiviral cationic peptides protegrin-1 (PG1 and plectasin (PLSN were fused with MAP30 protein to produce recombinant antiviral peptide-fusion protein (PG1-MAP30-PLSN as inclusion bodies in E. coli. High yield production of PG1-MAP30-PLSN protein was achieved by solubilization of inclusion bodies in alkaline buffer followed by the application of appropriate refolding techniques. Antiviral PG1-MAP30-PLSN protein considerably inhibited DENV protease (NS2B-NS3pro with half-maximal inhibitory concentration (IC50 0.5±0.1 μM. The real-time proliferation assay (RTCA and the end-point proliferation assay (MTT assay showed that the maximal-nontoxic dose of the peptide-fusion protein against Vero cells is approximately 0.67±0.2 μM. The cell-based assays showed considerable inhibition of the peptide-fusion protein against binding and proliferating stages of DENV2 into the target cells. The peptide-fusion protein protected DENV2-challeged mice with 100% of survival at the dose of 50 mg/kg. In conclusion, producing recombinant antiviral peptide-fusion protein by combining short antiviral peptide with a central protein owning similar activity could be useful to minimize the overall cost of short peptide production and take advantage of its synergistic antiviral activities.

Serum amyloid P component inhibits influenza A virus infections: in vitro and in vivo studies

DEFF Research Database (Denmark)

Horvath, A; Andersen, I; Junker, K

2001-01-01

. These studies were extended to comprise five mouse-adapted influenza A strains, two swine influenza A strains, a mink influenza A virus, a ferret influenza A reassortant virus, a influenza B virus and a parainfluenza 3 virus. The HA activity of all these viruses was inhibited by SAP. Western blotting showed......Serum amyloid P component (SAP) binds in vitro Ca(2+)-dependently to several ligands including oligosaccharides with terminal mannose and galactose. We have earlier reported that SAP binds to human influenza A virus strains, inhibiting hemagglutinin (HA) activity and virus infectivity in vitro...... that SAP bound to HA trimers, monomers and HA1 and HA2 subunits of influenza A virus. Binding studies indicated that galactose, mannose and fucose moieties contributed to the SAP reacting site(s). Intranasal administration of human SAP to mice induced no demonstrable toxic reactions, and circulating...

Are US utility standby rates inhibiting diffusion of customer-owned generating systems?

International Nuclear Information System (INIS)

Jackson, Jerry

2007-01-01

New, small-scale electric generation technologies permit utility customers to generate some of their own electric power and to utilize waste heat for space heating and other applications at the building site. This combined heat and power (CHP) characteristic can provide significant energy-cost savings. However, most current US utility regulations leave CHP standby rate specification largely to utility discretion resulting in claims by CHP advocates that excessive standby rates are significantly reducing CHP-related savings and inhibiting CHP diffusion. The impacts of standby rates on the adoption of CHP are difficult to determine; however, because of the characteristically slow nature of new technology diffusion. This study develops an agent-based microsimulation model of CHP technology choice using cellular automata to represent new technology information dispersion and knowledge acquisition. Applying the model as an n-factorial experiment quantifies the impacts of standby rates on CHP technologies under alternative diffusion paths. Analysis of a sample utility indicates that, regardless of the likely diffusion process, reducing standby rates to reflect the cost of serving a large number of small, spatially clustered CHP systems significantly increases the adoption of these technologies

sigma opiates and certain antipsychotic drugs mutually inhibit (+)-[3H]SKF 10,047 and [3H]haloperidol binding in guinea pig brain membranes

International Nuclear Information System (INIS)

Tam, S.W.; Cook, L.

1984-01-01

The relationship between binding of antipsychotic drugs and sigma psychotomimetic opiates to binding sites for the sigma agonist (+)-[ 3 H]SKF 10,047 (N-allylnormetazocine) and to dopamine D 2 sites was investigated. In guinea pig brain membranes, (+)-[ 3 H]SKF 10,047 bound to single class of sites with a K/sub d/ of 4 x 10 -8 M and a B/sub max/ of 333 fmol/mg of protein. This binding was different from μ, kappa, or delta opiate receptor binding. It was inhibited by opiates that produce psychotomimetic activities but not by opiates that lack such activities. Some antipsychotic drugs inhibited (+)-[ 3 H]SKF 10,047 binding with high to moderate affinities in the following order of potency: haloperidol > perphenazine > fluphenazine > acetophenazine > trifluoperazine > molindone greater than or equal to pimozide greater than or equal to thioridazine greater than or equal to chlorpromazine greater than or equal to triflupromazine. However, there were other antipsychotic drugs such as spiperone and clozapine that showed low affinity for the (+)-[ 3 H]SKF 10,047 binding sites. Affinities of antipsychotic drugs for (+)-[ 3 H]SKF 10,047 binding sites did not correlate with those for [ 3 H]spiperone (dopamine D 2 ) sites. [ 3 H]-Haloperidol binding in whole brain membranes was also inhibited by the sigma opiates pentazocine, cyclazocine, and (+)-[ 3 H]SKF 10,047. In the striatum, about half of the saturable [ 3 H]haloperidol binding was to [ 3 H]spiperone (D 2 ) sites and the other half was to sites similar to (+)-[ 3 H]SKF 10,047 binding sites. 15 references, 4 figures, 1 table

Amyloid-β secretion, generation, and lysosomal sequestration in response to proteasome inhibition

DEFF Research Database (Denmark)

Agholme, Lotta; Hallbeck, Martin; Benedikz, Eirikur

2012-01-01

, as the autophagosome has been suggested as a site of amyloid-β (Aβ) generation. In this study, we investigated the effect of proteasome inhibition on Aβ accumulation and secretion, as well as the processing of amyloid-β protein precursor (AβPP) in AβPP(Swe) transfected SH-SY5Y neuroblastoma cells. We show...

pH- and NIR Light-Responsive Polymeric Prodrug Micelles for Hyperthermia-Assisted Site-Specific Chemotherapy to Reverse Drug Resistance in Cancer Treatment.

Science.gov (United States)

Li, Zuhong; Wang, Haibo; Chen, Yangjun; Wang, Yin; Li, Huan; Han, Haijie; Chen, Tingting; Jin, Qiao; Ji, Jian

2016-05-01

Despite the exciting advances in cancer chemotherapy over past decades, drug resistance in cancer treatment remains one of the primary reasons for therapeutic failure. IR-780 loaded pH-responsive polymeric prodrug micelles with near infrared (NIR) photothermal effect are developed to circumvent the drug resistance in cancer treatment. The polymeric prodrug micelles are stable in physiological environment, while exhibit fast doxorubicin (DOX) release in acidic condition and significant temperature elevation under NIR laser irradiation. Phosphorylcholine-based biomimetic micellar shell and acid-sensitive drug conjugation endow them with prolonged circulation time and reduced premature drug release during circulation to conduct tumor site-specific chemotherapy. The polymeric prodrug micelles combined with NIR laser irradiation could significantly enhance intracellular DOX accumulation and synergistically induce the cell apoptosis in DOX-resistant MCF-7/ADR cells. Meanwhile, the tumor site-specific chemotherapy combined with hyperthermia effect induces significant inhibition of MCF-7/ADR tumor growth in tumor-bearing mice. These results demonstrate that the well-designed IR-780 loaded polymeric prodrug micelles for hyperthermia-assisted site-specific chemotherapy present an effective approach to reverse drug resistance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Allosteric Inhibition of Bcr-Abl Kinase by High Affinity Monobody Inhibitors Directed to the Src Homology 2 (SH2)-Kinase Interface*

Science.gov (United States)

Wojcik, John; Lamontanara, Allan Joaquim; Grabe, Grzegorz; Koide, Akiko; Akin, Louesa; Gerig, Barbara; Hantschel, Oliver; Koide, Shohei

2016-01-01

Bcr-Abl is a constitutively active kinase that causes chronic myelogenous leukemia. We have shown that a tandem fusion of two designed binding proteins, termed monobodies, directed to the interaction interface between the Src homology 2 (SH2) and kinase domains and to the phosphotyrosine-binding site of the SH2 domain, respectively, inhibits the Bcr-Abl kinase activity. Because the latter monobody inhibits processive phosphorylation by Bcr-Abl and the SH2-kinase interface is occluded in the active kinase, it remained undetermined whether targeting the SH2-kinase interface alone was sufficient for Bcr-Abl inhibition. To address this question, we generated new, higher affinity monobodies with single nanomolar KD values targeting the kinase-binding surface of SH2. Structural and mutagenesis studies revealed the molecular underpinnings of the monobody-SH2 interactions. Importantly, the new monobodies inhibited Bcr-Abl kinase activity in vitro and in cells, and they potently induced cell death in chronic myelogenous leukemia cell lines. This work provides strong evidence for the SH2-kinase interface as a pharmacologically tractable site for allosteric inhibition of Bcr-Abl. PMID:26912659

Allosteric Inhibition of Bcr-Abl Kinase by High Affinity Monobody Inhibitors Directed to the Src Homology 2 (SH2)-Kinase Interface.

Science.gov (United States)

Wojcik, John; Lamontanara, Allan Joaquim; Grabe, Grzegorz; Koide, Akiko; Akin, Louesa; Gerig, Barbara; Hantschel, Oliver; Koide, Shohei

2016-04-15

Bcr-Abl is a constitutively active kinase that causes chronic myelogenous leukemia. We have shown that a tandem fusion of two designed binding proteins, termed monobodies, directed to the interaction interface between the Src homology 2 (SH2) and kinase domains and to the phosphotyrosine-binding site of the SH2 domain, respectively, inhibits the Bcr-Abl kinase activity. Because the latter monobody inhibits processive phosphorylation by Bcr-Abl and the SH2-kinase interface is occluded in the active kinase, it remained undetermined whether targeting the SH2-kinase interface alone was sufficient for Bcr-Abl inhibition. To address this question, we generated new, higher affinity monobodies with single nanomolar KD values targeting the kinase-binding surface of SH2. Structural and mutagenesis studies revealed the molecular underpinnings of the monobody-SH2 interactions. Importantly, the new monobodies inhibited Bcr-Abl kinase activity in vitro and in cells, and they potently induced cell death in chronic myelogenous leukemia cell lines. This work provides strong evidence for the SH2-kinase interface as a pharmacologically tractable site for allosteric inhibition of Bcr-Abl. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Oridonin inhibits breast cancer growth and metastasis through blocking the Notch signaling

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Shixin Xia

2017-05-01

Full Text Available Background: Oridonin is a diterpenoid isolated from Rabdosia rubescens with potent anticancer activity. The aim of our study is to investigate the role of oridonin to inhibit growth and metastasis of human breast cancer cells. Methods: The effect of oridonin on proliferation was evaluated by MTT assay, cell migration and invasion were evaluated by transwell migration and invasion assays in human breast cancer cells. The inhibitive effect of oridonin in vivo was determined by using xenografted nude mice. In addition, the expression of Notch receptors (Notch 1–4 was detected by western blot. Results: Oridonin inhibited human breast cancer cells in vitro and in vivo. In addition, oridonin significantly induced human breast cancer cells apoptosis. Furthermore, the oridonin treatment not only inhibited cancer cell migration and invasion, but more significantly, decreased the expression of Notch 1-4 protein. Conclusion: Our results suggest that the inhibitive effect of oridonin is likely to be driven by the inhibition of Notch signaling pathway and the resulting increased apoptosis.

Selective inhibition by harmane of the apurinic apyrimidinic endonuclease activity of phage T4-induced UV endonuclease.

Science.gov (United States)

Warner, H R; Persson, M L; Bensen, R J; Mosbaugh, D W; Linn, S

1981-11-25

1-Methyl-9H-pyrido-[3,4-b]indole (harmane) inhibits the apurinic/apyrimidinic (AP) endonuclease activity of the UV endonuclease induced by phage T4, whereas it stimulates the pyrimidine dimer-DNA glycosylase activity of that enzyme. E. coli endonuclease IV, E. coli endonuclease VI (the AP endonuclease activity associated with E. coli exonuclease III), and E. coli uracil-DNA glycosylase were not inhibited by harmane. Human fibroblast AP endonucleases I and II also were only slightly inhibited. Therefore, harmane is neither a general inhibitor of AP endonucleases, nor a general inhibitor of Class I AP endonucleases which incise DNA on the 3'-side of AP sites. However, E. coli endonuclease III and its associated dihydroxythymine-DNA glycosylase activity were both inhibited by harmane. This observation suggests that harmane may inhibit only AP endonucleases which have associated glycosylase activities.

Targeting GLI by GANT61 involves mechanisms dependent on inhibition of both transcription and DNA licensing.

Science.gov (United States)

Zhang, Ruowen; Wu, Jiahui; Ferrandon, Sylvain; Glowacki, Katie J; Houghton, Janet A

2016-12-06

The GLI genes are transcription factors and in cancers are oncogenes, aberrantly and constitutively activated. GANT61, a specific GLI inhibitor, has induced extensive cytotoxicity in human models of colon cancer. The FOXM1 promoter was determined to be a transcriptional target of GLI1. In HT29 cells, inhibition of GLI1 binding at the GLI consensus sequence by GANT61 led to inhibited binding of Pol II, the pause-release factors DSIF, NELF and p-TEFb. The formation of R-loops (RNA:DNA hybrids, ssDNA), were reduced by GANT61 at the FOXM1 promoter. Pretreatment of HT29 cells with α-amanitin reduced GANT61-induced γH2AX foci. Co-localization of GLI1 and BrdU foci, inhibited by GANT61, indicated GLI1 and DNA replication to be linked. By co-immunoprecipitation and confocal microscopy, GLI1 co-localized with the DNA licensing factors ORC4, CDT1, and MCM2. Significant co-localization of GLI1 and ORC4 was inhibited by GANT61, and enrichment of ORC4 occurred at the GLI binding site in the FOXM1 promoter. CDT1 was found to be a transcription target of GLI1. Overexpression of CDT1 in HT29 and SW480 cells reduced GANT61-induced cell death, gH2AX foci, and cleavage of caspase-3. Data demonstrate involvement of transcription and of DNA replication licensing factors by non-transcriptional and transcriptional mechanisms in the GLI-dependent mechanism of action of GANT61.

Mutational analysis to identify the residues essential for the inhibition of N-acetyl glutamate kinase of Corynebacterium glutamicum.

Science.gov (United States)

Huang, Yuanyuan; Zhang, Hao; Tian, Hongming; Li, Cheng; Han, Shuangyan; Lin, Ying; Zheng, Suiping

2015-09-01

N-acetyl glutamate kinase (NAGK) is a key enzyme in the synthesis of L-arginine that is inhibited by its end product L-arginine in Corynebacterium glutamicum (C. glutamicum). In this study, the potential binding sites of arginine and the residues essential for its inhibition were identified by homology modeling, inhibitor docking, and site-directed mutagenesis. The allosteric inhibition of NAGK was successfully alleviated by a mutation, as determined through analysis of mutant enzymes, which were overexpressed in vivo in C. glutamicum ATCC14067. Analysis of the mutant enzymes and docking analysis demonstrated that residue W23 positions an arginine molecule, and the interaction between arginine and residues L282, L283, and T284 may play an important role in the remote inhibitory process. Based on the results of the docking analysis of the effective mutants, we propose a linkage mechanism for the remote allosteric regulation of NAGK activity, in which residue R209 may play an essential role. In this study, the structure of the arginine-binding site of C. glutamicum NAGK (CgNAGK) was successfully predicted and the roles of the relevant residues were identified, providing new insight into the allosteric regulation of CgNAGK activity and a solid platform for the future construction of an optimized L-arginine producing strain.

Affinity labeling and resonance energy transfer studies of the reduced coenzyme regulatory site of bovine liver glutamate dehydrogenase

International Nuclear Information System (INIS)

Lark, R.H.

1988-01-01

Bovine liver glutamate dehydrogenase was studied by affinity labeling and resonance energy transfer. The enzyme uses the 2', 3'-dialdehyde derivative of NADPH (oNADPH) in the reductive amination of α-ketoglutarate. A 300 min enzyme incubation with 250 μM oNADPH at pH 8.0 leads to a covalent incorporation of 1 mol oNADPH/mol enzyme subunit. Similar rate constants are measured when assaying the change in inhibition by 600 μM NADH or by 1 μM GTP, suggesting that inhibition loss at the two regulatory sites results from oNADPH reaction at one location. oNADPH-modified enzyme is still 93% inhibited by saturating GTP concentrations. The presence of 5 mM NADS(P)H plus 200 μM GTP prevents the kinetic changes and reduces the incorporation of oNADPH. oNADPH is concluded to modify the reduced coenzyme regulatory site, and GTP affects the binding of ligands to this site. The linkage between glutamate dehydrogenase and [ 14 C]oNADPH proved too labile to allow isolation of a radioactive modified peptide. Three corrections in the amino acid sequence were made after sequencing peptides. Resonance energy transfer was used to measure the distance between sites on the enzyme

Molecular Basis for Allosteric Inhibition of Acid-Sensing Ion Channel 1a by Ibuprofen

DEFF Research Database (Denmark)

Lynagh, Timothy; Romero-Rojo, José Luis; Lund, Camilla

2017-01-01

-clamp fluorometry. Our results show that ibuprofen is an allosteric inhibitor of ASIC1a, which binds to a crucial site in the agonist transduction pathway and causes conformational changes that oppose channel activation. Ibuprofen inhibits several ASIC subtypes, but certain ibuprofen derivatives show some...

A rhodanine derivative CCR-11 inhibits bacterial proliferation by inhibiting the assembly and GTPase activity of FtsZ.

Science.gov (United States)

Singh, Parminder; Jindal, Bhavya; Surolia, Avadhesha; Panda, Dulal

2012-07-10

A perturbation of FtsZ assembly dynamics has been shown to inhibit bacterial cytokinesis. In this study, the antibacterial activity of 151 rhodanine compounds was assayed using Bacillus subtilis cells. Of 151 compounds, eight strongly inhibited bacterial proliferation at 2 μM. Subsequently, we used the elongation of B. subtilis cells as a secondary screen to identify potential FtsZ-targeted antibacterial agents. We found that three compounds significantly increased bacterial cell length. One of the three compounds, namely, CCR-11 [(E)-2-thioxo-5-({[3-(trifluoromethyl)phenyl]furan-2-yl}methylene)thiazolidin-4-one], inhibited the assembly and GTPase activity of FtsZ in vitro. CCR-11 bound to FtsZ with a dissociation constant of 1.5 ± 0.3 μM. A docking analysis indicated that CCR-11 may bind to FtsZ in a cavity adjacent to the T7 loop and that short halogen-oxygen, H-bonding, and hydrophobic interactions might be important for the binding of CCR-11 with FtsZ. CCR-11 inhibited the proliferation of B. subtilis cells with a half-maximal inhibitory concentration (IC(50)) of 1.2 ± 0.2 μM and a minimal inhibitory concentration of 3 μM. It also potently inhibited proliferation of Mycobacterium smegmatis cells. Further, CCR-11 perturbed Z-ring formation in B. subtilis cells; however, it neither visibly affected nucleoid segregation nor altered the membrane integrity of the cells. CCR-11 inhibited HeLa cell proliferation with an IC(50) value of 18.1 ± 0.2 μM (∼15 × IC(50) of B. subtilis cell proliferation). The results suggested that CCR-11 inhibits bacterial cytokinesis by inhibiting FtsZ assembly, and it can be used as a lead molecule to develop FtsZ-targeted antibacterial agents.

Unbiased proteomics analysis demonstrates significant variability in mucosal immune factor expression depending on the site and method of collection.

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Kenzie M Birse

Full Text Available Female genital tract secretions are commonly sampled by lavage of the ectocervix and vaginal vault or via a sponge inserted into the endocervix for evaluating inflammation status and immune factors critical for HIV microbicide and vaccine studies. This study uses a proteomics approach to comprehensively compare the efficacy of these methods, which sample from different compartments of the female genital tract, for the collection of immune factors. Matching sponge and lavage samples were collected from 10 healthy women and were analyzed by tandem mass spectrometry. Data was analyzed by a combination of differential protein expression analysis, hierarchical clustering and pathway analysis. Of the 385 proteins identified, endocervical sponge samples collected nearly twice as many unique proteins as cervicovaginal lavage (111 vs. 61 with 55% of proteins common to both (213. Each method/site identified 73 unique proteins that have roles in host immunity according to their gene ontology. Sponge samples enriched for specific inflammation pathways including acute phase response proteins (p = 3.37×10(-24 and LXR/RXR immune activation pathways (p = 8.82×10(-22 while the role IL-17A in psoriasis pathway (p = 5.98×10(-4 and the complement system pathway (p = 3.91×10(-3 were enriched in lavage samples. Many host defense factors were differentially enriched (p<0.05 between sites including known/potential antimicrobial factors (n = 21, S100 proteins (n = 9, and immune regulatory factors such as serpins (n = 7. Immunoglobulins (n = 6 were collected at comparable levels in abundance in each site although 25% of those identified were unique to sponge samples. This study demonstrates significant differences in types and quantities of immune factors and inflammation pathways collected by each sampling technique. Therefore, clinical studies that measure mucosal immune activation or factors assessing HIV transmission should utilize

Attention Inhibition Training Can Reduce Betel-Nut Chewing Time

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Ming-Chou Ho

2011-05-01

Full Text Available Betel nut (or areca is the fourth most commonly used drug worldwide after tobacco, alcohol, and caffeine. Many chemical ingredients of betel nut are carcinogenic. We examined whether the manipulation of attentional inhibition toward the areca-related stimuli could affect betel-nut chewing time. Three matched groups of habitual chewers were recruited: inhibit-areca, inhibit-non-areca, and control. This study consisted of a Go/No-Go task for inhibition training, followed by a taste test for observing chewing behavior. The Go/No-Go task constituted three phases (pretest, training and posttest. In the taste test, the habitual chewers were asked to rate the flavors of one betel nut and one gum. The purpose (blind to the chewers of this taste test was to observe whether their picking order and chewing time were affected by experimental manipulation. Results from the Go/No-Go task showed successful training. Further, the training groups (the inhibit-areca and inhibit-non-areca groups showed a significant reduction in betel nut chewing time, in comparison to the control group. Since both training groups showed reduced chewing time, the inhibition training may affect general control ability, in regardless of the stimulus (areca or not to be inhibited. Reduced chewing time is important for reducing areca-related diseases.

Na-K pump site density and ouabain binding affinity in cultured chick heart cells

International Nuclear Information System (INIS)

Lobaugh, L.A.; Lieberman, M.

1987-01-01

The possible existence of multiple [ 3 H]ouabain binding sites and the relationship between ouabain binding and Na-K pump inhibition in cardiac muscle were studied using cultured embryonic chick heart cells. [ 3 H]ouabain bound to a single class of sites in 0.5 mM K (0.5 Ko) with an association rate constant (k+1) of 3.4 X 10(4) M-1.s-1 and a dissociation rate constant (k-1) of 0.0095 s. Maximal specific [ 3 H]ouabain binding RT to myocyte-enriched cultures is 11.7 pmol/mg protein and Kd is 0.43 microM in 0.5 Ko, whereas Kd,apparent is 6.6 microM in 5.4 Ko. The number of binding sites per myocyte was calculated by correcting for the contribution of fibroblasts in myocyte-enriched cultures using data from homogeneous fibroblast cultures (RT = 3.3 pmol/mg protein; Kd = 0.19 microM in 0.5 Ko). Equivalence of [ 3 H]ouabain binding sites and Na-K pumps was implied by agreement between maximal specific binding of [ 3 H]ouabain and 125 I-labeled monoclonal antibody directed against Na+-K+-ATPase (approximately 2 X 10(6) sites/cell). However, [ 3 H]ouabain binding occurred at lower concentrations than inhibition of ouabain-sensitive 42 K uptake in 0.5 Ko. Further studies in both 0.5 K and 5.4 Ko showed that ouabain caused cell Na content Nai to increase over the same range of concentrations that binding occurred, implying that increased Nai may stimulate unbound Na-K pumps and prevent a proportional decrease in 42 K uptake rate. The results show that Na-K pump inhibition occurs as a functional consequence of specific ouabain binding and indicate that the Na-K pump is the cardiac glycoside receptor in cultured heart cells

Emodin reverses leukemia multidrug resistance by competitive inhibition and downregulation of P-glycoprotein.

Directory of Open Access Journals (Sweden)

Hongping Min

Full Text Available Development of multidrug resistance (MDR is a continuous clinical challenge partially due to the overexpression of P-glycoprotein (P-gp for chronic myelogenous leukemia (CML patients. Herein, we evaluated the inhibitory potency of emodin, a natural anthraquinone derivative isolated from Rheum palmatum L, on P-gp in P-gp positive K562/ADM cells. Competition experiments combined with molecular docking analysis were utilized to investigate the binding modes between emodin and binding sites of P-gp. Emodin reversed adriamycin resistance in K562/ADM cells accompanied with the decrease of P-gp protein expression, further increasing the uptake of rhodamine123 in both K562/ADM and Caco-2 cells, indicating the inhibition of P-gp efflux function. Moreover, when incubated with emodin under different conditions where P-gp was inhibited, K562/ADM cells displayed increasing intracellular uptake of emodin, suggesting that emodin may be the potential substrate of P-gp. Importantly, rhodamine 123 could increase the Kintrinsic (Ki value of emodin linearly, whereas, verapamil could not, implying that emodin competitively bound to the R site of P-gp and noncompetition existed between emodin and verapamil at the M site, in a good accordance with the results of molecular docking that emodin bound to the R site of P-gp with higher affinity. Based on our results, we suggest that emodin might be used to modulate P-gp function and expression.

MCBS Sites of Biodiversity Significance

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Minnesota Department of Natural Resources — This data layer represents areas with varying levels of native biodiversity that may contain high quality native plant communities, rare plants, rare animals, and/or...

Locally limited inhibition of bone resorption and orthodontic relapse by recombinant osteoprotegerin protein.

Science.gov (United States)

Schneider, D A; Smith, S M; Campbell, C; Hayami, T; Kapila, S; Hatch, N E

2015-04-01

To determine minimal dose levels required for local inhibition of orthodontic relapse by recombinant OPG protein (OPG-Fc), while also determining effects of injected OPG-Fc on alveolar bone and long bone. The Department of Orthodontics and Pediatric Dentistry at the University of Michigan. Eighteen male Sprague Dawley rats. Maxillary molars were moved with nickel-titanium springs and then allowed to relapse in Sprague Dawley rats. Upon appliance removal, animals were injected with a single dose of 1.0 mg/kg OPG-Fc, 0.1 mg/kg OPG-Fc, or phosphate-buffered saline (vehicle) just distal to the molar teeth. Tooth movement measurements were made from stone casts, which were scanned and digitally measured. Alveolar tissues were examined by histology. Micro-computed tomography was used to quantify changes in alveolar and femur bone. Local injection of OPG-Fc inhibited molar but not incisor relapse, when compared to vehicle-injected animals. No significant differences in alveolar or femur bone were seen between the three treatment groups after 24 days of relapse. Our results demonstrate that a single local injection of OPG-Fc effectively inhibits orthodontic relapse, with minimal systemic bone metabolic effects. Our results also show that a single injection of OPG-Fc will influence tooth movement only in teeth close to the injection site. These findings indicate that OPG-Fc has potential as a safe and effective pharmacological means to locally control osteoclasts, for uses such as maintaining anchorage during orthodontic tooth movement and preventing orthodontic relapse in humans. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

SRS Process Facility Significance Fire Frequency

Energy Technology Data Exchange (ETDEWEB)

Sarrack, A.G. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1995-10-01

This report documents the method and assumptions of a study performed to determine a site generic process facility significant fire initiator frequency and explains the proper way this value should be used.

SRS Process Facility Significance Fire Frequency

International Nuclear Information System (INIS)

Sarrack, A.G.

1995-10-01

This report documents the method and assumptions of a study performed to determine a site generic process facility significant fire initiator frequency and explains the proper way this value should be used

Transient expression of protein tyrosine phosphatases encoded in Cotesia plutellae bracovirus inhibits insect cellular immune responses

Science.gov (United States)

Ibrahim, Ahmed M. A.; Kim, Yonggyun

2008-01-01

Several immunosuppressive factors are associated with parasitism of an endoparasitoid wasp, Cotesia plutellae, on the diamondback moth, Plutella xylostella. C. plutellae bracovirus (CpBV) encodes a large number of putative protein tyrosine phosphatases (PTPs), which may play a role in inhibiting host cellular immunity. To address this inhibitory hypothesis of CpBV-PTPs, we performed transient expression of individual CpBV-PTPs in hemocytes of the beet armyworm, Spodoptera exigua, and analyzed their cellular immune responses. Two different forms of CpBV-PTPs were chosen and cloned into a eukaryotic expression vector under the control of the p10 promoter of baculovirus: one with the normal cysteine active site (CpBV-PTP1) and the other with a mutated active site (CpBV-PTP5). The hemocytes transfected with CpBV-PTP1 significantly increased in PTP activity compared to control hemocytes, but those with CpBV-PTP5 exhibited a significant decrease in the PTP activity. All transfected hemocytes exhibited a significant reduction in both cell spreading and encapsulation activities compared to control hemocytes. Co-transfection of CpBV-PTP1 together with its double-stranded RNA reduced the messenger RNA (mRNA) level of CpBV-PTP1 and resulted in recovery of both hemocyte behaviors. This is the first report demonstrating that the polydnaviral PTPs can manipulate PTP activity of the hemocytes to interrupt cellular immune responses.

Direct interaction between caffeic acid phenethyl ester and human neutrophil elastase inhibits the growth and migration of PANC-1 cells.

Science.gov (United States)

Duan, Jianhui; Xiaokaiti, Yilixiati; Fan, Shengjun; Pan, Yan; Li, Xin; Li, Xuejun

2017-05-01

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant tumors of the digestive system, but the mechanisms of its development and progression are unclear. Inflammation is thought to be fundamental to pancreatic cancer development and caffeic acid phenethyl ester (CAPE) is an active component of honey bee resin or propolis with anti-inflammatory and anticancer activities. We investigated the inhibitory effects of CAPE on cell growth and migration induced by human neutrophil elastase (HNE) and report that HNE induced cancer cell migration at low doses and growth at higher doses. In contrast, lower CAPE doses inhibited migration and higher doses of CAPE inhibited the growth induced by HNE. HNE activity was significantly inhibited by CAPE (7.5-120 µM). Using quantitative real-time PCR and western blotting, we observed that CAPE (18-60 µM) did not affect transcription and translation of α1-antitrypsin (α1-AT), an endogenous HNE inhibitor. However, in an in silico drug target docking model, we found that CAPE directly bound to the binding pocket of HNE (25.66 kcal/mol) according to CDOCKER, and the residue of the catalytic site stabilized the interaction between CAPE and HNE as evidenced by molecular dynamic simulation. Response unit (RU) values of surface plasmon resonance (SPR) significantly increased with incremental CAPE doses (7.5-120 µM), indicating that CAPE could directly bind to HNE in a concentration-dependent manner. Thus, CAPE is an effective inhibitor of HNE via direct interaction whereby it inhibits the migration and growth of PANC-1 cells in a dose-dependent manner.

Topography of the high-affinity lysine binding site of plasminogen as defined with a specific antibody probe

International Nuclear Information System (INIS)

Miles, L.A.; Plow, E.F.

1986-01-01

An antibody population that reacted with the high-affinity lysine binding site of human plasminogen was elicited by immunizing rabbits with an elastase degradation product containing kringles 1-3 (EDP I). This antibody was immunopurified by affinity chromatography on plasminogen-Sepharose and elution with 0.2 M 6-aminohexanoic acid. The eluted antibodies bound [ 125 I]EDP I, [ 125 I]Glu-plasminogen, and [ 125 I]Lys-plasminogen in radioimmunoassays, and binding of each ligand was at least 99% inhibited by 0.2 M 6-aminohexanoic acid. The concentrations for 50% inhibition of [ 125 I]EDP I binding by tranexamic acid, 6-aminohexanoic acid, and lysine were 2.6, 46, and l730 μM, respectively. Similar values were obtained with plasminogen and suggested that an unoccupied high-affinity lysine binding site was required for antibody recognition. The antiserum reacted exclusively with plasminogen derivatives containing the EDP I region and did not react with those lacking an EDP I region, or with tissue plasminogen activator or prothrombin, which also contains kringles. By immunoblotting analyses, a chymotryptic degradation product of M/sub r/ 20,000 was derived from EDP I that retained reactivity with the antibody. α 2 -Antiplasmin inhibited the binding of radiolabeled EDP I, Glu-plasminogen, or Lys-plasminogen by the antiserum, suggesting that the recognized site is involved in the noncovalent interaction of the inhibitor with plasminogen. The binding of [ 125 I]EDP I to fibrin was also inhibited by the antiserum. The observations provide independent evidence for the role of the high-affinity lysine binding site in the functional interactions of plasminogen with its primary substrate and inhibitor

The role of organic load and ammonia inhibition in anaerobic digestion of tannery fleshing

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Cecilia Polizzi

2018-06-01

Full Text Available In this study, batch tests on anaerobic digestion of tannery fleshing (skin-residue waste from hides’ tanning process, as sole substrate, have been performed with the purpose of assessing the effects of high substrate concentration and consequent ammonia inhibition on the process. Co-digestion with tannery primary sludge was also evaluated. According to the results, no inhibition occurred at initial organic load up to 5 gVS/l; an inhibited steady state was observed at 10 gVS/l, and system failure and instability was showed at the highest load of 20 gVS/l. Co-digestion with tannery primary sludge proved feasible, probably due to dilution effect. The observed ammonia and VFA accumulation over the experimental time-lapse is also discussed. Results are intended to increase knowledge on the technological application of anaerobic digestion of sole tannery fleshing, in the perspective of its application as on-site treatment solution for decentralised tanneries. Keywords: Anaerobic digestion, Tannery waste, Ammonia inhibition, Organic load

Inhibition of existing denitrification enzyme activity by chloramphenicol

Science.gov (United States)

Brooks, M.H.; Smith, R.L.; Macalady, D.L.

1992-01-01

Chloramphenicol completely inhibited the activity of existing denitrification enzymes in acetylene-block incubations with (i) sediments from a nitrate-contaminated aquifer and (ii) a continuous culture of denitrifying groundwater bacteria. Control flasks with no antibiotic produced significant amounts of nitrous oxide in the same time period. Amendment with chloramphenicol after nitrous oxide production had begun resulted in a significant decrease in the rate of nitrous oxide production. Chloramphenicol also decreased (>50%) the activity of existing denitrification enzymes in pure cultures of Pseudomonas denitrificans that were harvested during log- phase growth and maintained for 2 weeks in a starvation medium lacking electron donor. Short-term time courses of nitrate consumption and nitrous oxide production in the presence of acetylene with P. denitrificans undergoing carbon starvation were performed under optimal conditions designed to mimic denitrification enzyme activity assays used with soils. Time courses were linear for both chloramphenicol and control flasks, and rate estimates for the two treatments were significantly different at the 95% confidence level. Complete or partial inhibition of existing enzyme activity is not consistent with the current understanding of the mode of action of chloramphenicol or current practice, in which the compound is frequently employed to inhibit de novo protein synthesis during the course of microbial activity assays. The results of this study demonstrate that chloramphenicol amendment can inhibit the activity of existing denitrification enzymes and suggest that caution is needed in the design and interpretation of denitrification activity assays in which chloramphenicol is used to prevent new protein synthesis.

Inhibition of SIRT1 combined with gemcitabine therapy for pancreatic carcinoma

Directory of Open Access Journals (Sweden)

Gong DJ

2013-07-01

Full Text Available Dao-Jun Gong,1 Jia-Min Zhang,1 Min Yu,1 Bo Zhuang,1 Qing-Qu Guo21Department of Hepatobiliary-Pancreatic Surgery, Jinhua Hospital of Zhejiang University, Jinhua, People's Republic of China; 2Department of Surgery, Second Affiliated Hospital of Zhejiang University College of Medicine, Hangzhou, People's Republic of ChinaBackground: Pancreatic carcinoma possesses one of the highest lethality rates, highest drug-resistance, and highest incidence rates. The objective of this research was to enhance the efficacy and drug-resistance for pancreatic carcinoma by using inhibition of SIRT1 combined with gemcitabine therapy methods.Methods: Three pancreatic carcinoma cells (PANC-1 cells, BxPC-3 cells, and SW1990 cells received treatment with physiological saline, inhibition of SIRT1, gemcitabine, and combination therapy with inhibition of SIRT1 and gemcitabine in vitro; then BxPC-3 pancreatic cancer xenogeneic mice also received treatment with physiological saline, inhibition of SIRT1, gemcitabine, and combination therapy with inhibition of SIRT1 and gemcitabine in vivo.Results: The cleaved poly ADP ribose polymerase (PARP-1 effect of drug in pancreatic carcinoma cells was significantly different (P < 0.05 and the efficacy in descending order was the combination therapy with inhibition of SIRT1 and gemcitabine, inhibition of SIRT1, and gemcitabine. The BxPC-3 pancreatic cancer xenogeneic mice model received treatment with physiological saline, inhibition of SIRT1, gemcitabine, and combination therapy with inhibition of SIRT1 and gemcitabine in vivo and the results showed that the tumor volumes decreased and the survival rate within 45 days increased according to the order of the given drugs and the difference was significant (P < 0.05.Conclusion: Combination therapy with inhibition of SIRT1 and gemcitabine could improve efficacy and survival time in a BxPC-3 pancreatic cancer xenogeneic mice model, compared with single inhibition of SIRT1, or single

Effects of Afternoon Nap Deprivation on Adult Habitual Nappers’ Inhibition Functions

Directory of Open Access Journals (Sweden)

Qingwei Chen

2018-01-01

Full Text Available Multiple studies have established the effects of afternoon naps on cognition. However, relatively few studies have investigated the domain of executive functions. Moreover, the effects of napping on inhibition are far from conclusive. The present study employed adult habitual nappers to investigate the effects of afternoon nap deprivation on response-based inhibition assessed by a Go/No-go task and stimulus-based inhibition assessed by a Flanker task and on alertness assessed by a psychomotor vigilance test (PVT and the Karolinska Sleepiness Scale (KSS. The results showed that afternoon nap deprivation significantly decreased participants’ accuracy and reaction speed for the Go/No-go task but not for the Flanker task. In addition, participants’ alertness was significantly impaired after nap deprivation in terms of increased subjective sleepiness and worse PVT performance. Task-specific effects of napping on inhibition were demonstrated. The implications of the results are discussed.

Noncompetitive inhibition of indolethylamine-N-methyltransferase by N,N-dimethyltryptamine and N,N-dimethylaminopropyltryptamine.

Science.gov (United States)

Chu, Uyen B; Vorperian, Sevahn K; Satyshur, Kenneth; Eickstaedt, Kelsey; Cozzi, Nicholas V; Mavlyutov, Timur; Hajipour, Abdol R; Ruoho, Arnold E

2014-05-13

Indolethylamine-N-methyltransferase (INMT) is a Class 1 transmethylation enzyme known for its production of N,N-dimethyltryptamine (DMT), a hallucinogen with affinity for various serotonergic, adrenergic, histaminergic, dopaminergic, and sigma-1 receptors. DMT is produced via the action of INMT on the endogenous substrates tryptamine and S-adenosyl-l-methionine (SAM). The biological, biochemical, and selective small molecule regulation of INMT enzyme activity remain largely unknown. Kinetic mechanisms for inhibition of rabbit lung INMT (rabINMT) by the product, DMT, and by a new novel tryptamine derivative were determined. After Michaelis-Menten and Lineweaver-Burk analyses had been applied to study inhibition, DMT was found to be a mixed competitive and noncompetitive inhibitor when measured against tryptamine. The novel tryptamine derivative, N-[2-(1H-indol-3-yl)ethyl]-N',N'-dimethylpropane-1,3-diamine (propyl dimethyl amino tryptamine or PDAT), was shown to inhibit rabINMT by a pure noncompetitive mechanism when measured against tryptamine with a Ki of 84 μM. No inhibition by PDAT was observed at 2 mM when it was tested against structurally similar Class 1 methyltransferases, such as human phenylethanolamine-N-methyltransferase (hPNMT) and human nicotinamide-N-methyltransferase (hNNMT), indicating selectivity for INMT. The demonstration of noncompetitive mechanisms for INMT inhibition implies the presence of an inhibitory allosteric site. In silico analyses using the computer modeling software Autodock and the rabINMT sequence threaded onto the human INMT (hINMT) structure (Protein Data Bank entry 2A14 ) identified an N-terminal helix-loop-helix non-active site binding region of the enzyme. The energies for binding of DMT and PDAT to this region of rabINMT, as determined by Autodock, were -6.34 and -7.58 kcal/mol, respectively. Assessment of the allosteric control of INMT may illuminate new biochemical pathway(s) underlying the biology of INMT.

The inhibition of subchondral bone lesions significantly reversed the weight-bearing deficit and the overexpression of CGRP in DRG neurons, GFAP and Iba-1 in the spinal dorsal horn in the monosodium iodoacetate induced model of osteoarthritis pain.

Directory of Open Access Journals (Sweden)

Degang Yu

Full Text Available Chronic pain is the most prominent and disabling symptom of osteoarthritis (OA. Clinical data suggest that subchondral bone lesions contribute to the occurrence of joint pain. The present study investigated the effect of the inhibition of subchondral bone lesions on joint pain.Osteoarthritic pain was induced by an injection of monosodium iodoacetate (MIA into the rat knee joint. Zoledronic acid (ZOL, a third generation of bisphosphonate, was used to inhibit subchondral bone lesions. Joint histomorphology was evaluated using X-ray micro computed tomography scanning and hematoxylin-eosin staining. The activity of osteoclast in subchondral bone was evaluated using tartrate-resistant acid phosphatase staining. Joint pain was evaluated using weight-bearing asymmetry, the expression of calcitonin gene-related peptide (CGRP in the dorsal root ganglion (DRG, and spinal glial activation status using glial fibrillary acidic protein (GFAP and ionized calcium binding adaptor molecule-1 (Iba-1 immunofluorescence. Afferent neurons in the DRGs that innervated the joints were identified using retrograde fluorogold labeling.MIA injections induced significant histomorphological alterations and joint pain. The inhibition of subchondral bone lesions by ZOL significantly reduced the MIA-induced weight-bearing deficit and overexpression of CGRP in DRG neurons, GFAP and Iba-1 in the spinal dorsal horn at 3 and 6 weeks after MIA injection; however, joint swelling and synovial reaction were unaffected.The inhibition of subchondral bone lesions alleviated joint pain. Subchondral bone lesions should be a key target in the management of osteoarthritic joint pain.

Peripheral site ligand conjugation to a non-quaternary oxime enhances reactivation of nerve agent-inhibited human acetylcholinesterase

NARCIS (Netherlands)

Koning, M.C. de; Grol, M. van; Noort, D.

2011-01-01

Commonly employed pyridinium-oxime (charged) reactivators of nerve agent inhibited acetylcholinesterase (AChE) do not readily pass the blood brain barrier (BBB) because of the presence of charge(s). Conversely, non-ionic oxime reactivators often suffer from a lack of reactivating potency due to a

Experimental study on the effect of ingested lead shot on Estuarine crocodiles: significance for Finniss River field studies

International Nuclear Information System (INIS)

Hammerton, K.M.

2002-01-01

Lead has long been recognised as a cumulative metabolic poison in humans, domestic animals and wildlife. Because of the many industrial activities that have brought about its widespread distribution, lead is ubiquitous in the environment. For example, uranium mining at the Rum Jungle site on the Finniss River, Northern Territory, resulted in contamination of river sediments with lead. Today, lead levels remain at about 250 mg kg-1 of wet river sediment within the immediate vicinity of the mine. Another potential source of lead poisoning in wildlife is the use of lead gunshot for hunting. Mortality in wild waterfowl caused by the ingestion of spent lead shot has been recognised in North America and Europe for over a century. An experimental study was undertaken to assess the above hypothesis on the effects of lead in the environs of crocodiles. The specific effects of lead intoxication arise mainly from the interaction of lead with the enzymatic processes in the haem biosynthetic pathway. One of these enzymes, δ-aminolevulinic acid dehydratase (ALAD), catalyses the condensation of two molecules of aminolevulinic acid to produce the pyrrole, porphobilinogen, the building block of the haem molecule. ALAD is a metalloenzyme requiring zinc for activity and is inhibited by lead displacing the essential zinc. This inhibition of ALAD by lead has been used as a specific biomarker for lead poisoning in fish, birds and mammals. An assay system was developed for the measurement of ALAD activity in crocodilian blood. It was found that ALAD was inhibited by up to 90% during the first week after exposure of the crocodiles to lead shot. There was an inverse correlation between BPb and ALAD activity throughout the 42 week experimental period. BPb concentrations greater than 100 mg dL-1 produced significant inhibition of ALAD. The results indicated that ALAD inhibition could be used as a specific biomarker of lead toxicity in crocodiles

Differential modulation of the N2 and P3 event-related potentials by response conflict and inhibition.

Science.gov (United States)

Groom, Madeleine J; Cragg, Lucy

2015-07-01

Developing reliable and specific neural markers of cognitive processes is essential to improve understanding of healthy and atypical brain function. Despite extensive research there remains uncertainty as to whether two electrophysiological markers of cognitive control, the N2 and P3, are better conceptualised as markers of response inhibition or response conflict. The present study aimed to directly compare the effects of response inhibition and response conflict on the N2 and P3 event-related potentials, within-subjects. A novel hybrid go/no-go flanker task was performed by 19 healthy adults aged 18-25 years while EEG data were collected. The response congruence of a central target stimulus and 4 flanking stimuli was manipulated between trials to vary the degree of response conflict. Response inhibition was required on a proportion of trials. N2 amplitude was measured at two frontal electrode sites; P3 amplitude was measured at 4 midline electrode sites. N2 amplitude was greater on incongruent than congruent trials but was not enhanced by response inhibition when the stimulus array was congruent. P3 amplitude was greater on trials requiring response inhibition; this effect was more pronounced at frontal electrodes. P3 amplitude was also enhanced on incongruent compared with congruent trials. The findings support a role for N2 amplitude as a marker of response conflict and for the frontal shift of the P3 as a marker of response inhibition. This paradigm could be applied to clinical groups to help clarify the precise nature of impaired action control in disorders such as attention deficit/hyperactivity disorders (ADHD). Copyright © 2015 Elsevier Inc. All rights reserved.

Drug-protein hydrogen bonds govern the inhibition of the ATP hydrolysis of the multidrug transporter P-glycoprotein.

Science.gov (United States)

Chufan, Eduardo E; Kapoor, Khyati; Ambudkar, Suresh V

2016-02-01

P-glycoprotein (P-gp) is a member of the ATP-binding cassette transporter superfamily. This multidrug transporter utilizes energy from ATP hydrolysis for the efflux of a variety of hydrophobic and amphipathic compounds including anticancer drugs. Most of the substrates and modulators of P-gp stimulate its basal ATPase activity, although some inhibit it. The molecular mechanisms that are in play in either case are unknown. In this report, mutagenesis and molecular modeling studies of P-gp led to the identification of a pair of phenylalanine-tyrosine structural motifs in the transmembrane region that mediate the inhibition of ATP hydrolysis by certain drugs (zosuquidar, elacridar and tariquidar), with high affinity (IC50's ranging from 10 to 30nM). Upon mutation of any of these residues, drugs that inhibit the ATPase activity of P-gp switch to stimulation of the activity. Molecular modeling revealed that the phenylalanine residues F978 and F728 interact with tyrosine residues Y953 and Y310, respectively, in an edge-to-face conformation, which orients the tyrosines in such a way that they establish hydrogen-bond contacts with the inhibitor. Biochemical investigations along with transport studies in intact cells showed that the inhibitors bind at a high affinity site to produce inhibition of ATP hydrolysis and transport function. Upon mutation, they bind at lower affinity sites, stimulating ATP hydrolysis and only poorly inhibiting transport. These results also reveal that screening chemical compounds for their ability to inhibit the basal ATP hydrolysis can be a reliable tool to identify modulators with high affinity for P-gp. Published by Elsevier Inc.

Inhibition of the Secretory pathway by Foot-and-Mouth disease virus 2BC protein is reproduced by co-expression of 2B with 2C, and the site of inhibition is determined by the subcellular location of 2C

DEFF Research Database (Denmark)

Moffat, Katy; Knox, Caroline; Howell, Gareth

2007-01-01

immune responses in vivo. Foot-and-mouth disease virus (FMDV), another picornavirus, can cause persistent infection of ruminants, suggesting it too may inhibit immune responses. Endoplasmic reticulum (ER)-to-Golgi apparatus transport of proteins is blocked by the FMDV 2BC protein. The observation that 2...... blocked in FMDV-infected cells. The block could be reconstituted by coexpression of 2B and 2C, showing that processing of 2BC did not compromise the ability of FMDV to slow secretion. Under these conditions, 2C was located to the Golgi apparatus, and the block in transport also occurred in the Golgi...... apparatus. Interestingly, the block in transport could be redirected to the ER when 2B was coexpressed with a 2C protein fused to an ER retention element. Thus, for FMDV a block in secretion is dependent on both 2B and 2C, with the latter determining the site of the block....

Innovative Strategies for Selective Inhibition of Histone Deacetylases

DEFF Research Database (Denmark)

Maolanon, Alex Ramalak; Madsen, Andreas Stahl; Olsen, Christian Adam

2016-01-01

Histone deacetylases (HDAC) are a family of closely related enzymes involved in epigenetic and posttranscriptional regulation of numerous genes and proteins. Their deregulation is associated with a number of diseases, and a handful of HDAC inhibitors have been approved for cancer treatment. None......, functionally important, features. Based on this analysis, we suggest alternative strategies to achieve selective HDAC inhibition that does not rely on chelation of the zinc ion in the active site but rather on disruption of protein-protein interactions important for HDAC activity. We believe that, although...

Camptothecin inhibits platelet-derived growth factor-BB-induced proliferation of rat aortic vascular smooth muscle cells through inhibition of PI3K/Akt signaling pathway

Energy Technology Data Exchange (ETDEWEB)

Park, Eun-Seok [Department of Applied Biochemistry, Division of Life Science, College of Health and Biomedical Science, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Kang, Shin-il [College of Pharmacy Medical Research Center, Chungbuk National University, Cheongju (Korea, Republic of); Yoo, Kyu-dong [Hazardous Substances Analysis Division, Gwangju Regional Food and Drug Administration, Gwangju (Korea, Republic of); Lee, Mi-Yea [Department of Nursing Kyungbok University, Pocheon (Korea, Republic of); Yoo, Hwan-Soo; Hong, Jin-Tae [College of Pharmacy Medical Research Center, Chungbuk National University, Cheongju (Korea, Republic of); Shin, Hwa-Sup [Department of Applied Biochemistry, Division of Life Science, College of Health and Biomedical Science, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Kim, Bokyung [Department of Physiology, Konkuk Medical School, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Yun, Yeo-Pyo, E-mail: ypyun@chungbuk.ac.kr [College of Pharmacy Medical Research Center, Chungbuk National University, Cheongju (Korea, Republic of)

2013-04-15

The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial wall is a major cause of vascular disorders such as atherosclerosis and restenosis after angioplasty. In this study, we investigated not only the inhibitory effects of camptothecin (CPT) on PDGF-BB-induced VSMC proliferation, but also its molecular mechanism of this inhibition. CPT significantly inhibited proliferation with IC50 value of 0.58 μM and the DNA synthesis of PDGF-BB-stimulated VSMCs in a dose-dependent manner (0.5–2 μM ) without any cytotoxicity. CPT induced the cell cycle arrest at G0/G1 phase. Also, CPT decreased the expressions of G0/G1-specific regulatory proteins including cyclin-dependent kinase (CDK)2, cyclin D1 and PCNA in PDGF-BB-stimulated VSMCs. Pre-incubation of VSMCs with CPT significantly inhibited PDGF-BB-induced Akt activation, whereas CPT did not affect PDGF-receptor beta phosphorylation, extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and phospholipase C (PLC)-γ1 phosphorylation in PDGF-BB signaling pathway. Our data showed that CPT pre-treatment inhibited VSMC proliferation, and that the inhibitory effect of CPT was enhanced by LY294002, a PI3K inhibitor, on PDGF-BB-induced VSMC proliferation. In addition, inhibiting the PI3K/Akt pathway by LY294002 significantly enhanced the suppression of PCNA expression and Akt activation by CPT. These results suggest that the anti-proliferative activity of CPT is mediated in part by downregulating the PI3K/Akt signaling pathway. - Highlights: ► CPT inhibits proliferation of PDGF-BB-induced VSMC without cytotoxicity. ► CPT arrests the cell cycle in G0/G1 phase by downregulation of cyclin D1 and CDK2. ► CPT significantly attenuates Akt phosphorylation in PDGF-BB signaling pathway. ► LY294002 enhanced the inhibitory effect of CPT on VSMC proliferation. ► Thus, CPT is mediated by downregulating the PI3K/Akt signaling pathway.

Camptothecin inhibits platelet-derived growth factor-BB-induced proliferation of rat aortic vascular smooth muscle cells through inhibition of PI3K/Akt signaling pathway

International Nuclear Information System (INIS)

Park, Eun-Seok; Kang, Shin-il; Yoo, Kyu-dong; Lee, Mi-Yea; Yoo, Hwan-Soo; Hong, Jin-Tae; Shin, Hwa-Sup; Kim, Bokyung; Yun, Yeo-Pyo

2013-01-01

The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial wall is a major cause of vascular disorders such as atherosclerosis and restenosis after angioplasty. In this study, we investigated not only the inhibitory effects of camptothecin (CPT) on PDGF-BB-induced VSMC proliferation, but also its molecular mechanism of this inhibition. CPT significantly inhibited proliferation with IC50 value of 0.58 μM and the DNA synthesis of PDGF-BB-stimulated VSMCs in a dose-dependent manner (0.5–2 μM ) without any cytotoxicity. CPT induced the cell cycle arrest at G0/G1 phase. Also, CPT decreased the expressions of G0/G1-specific regulatory proteins including cyclin-dependent kinase (CDK)2, cyclin D1 and PCNA in PDGF-BB-stimulated VSMCs. Pre-incubation of VSMCs with CPT significantly inhibited PDGF-BB-induced Akt activation, whereas CPT did not affect PDGF-receptor beta phosphorylation, extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and phospholipase C (PLC)-γ1 phosphorylation in PDGF-BB signaling pathway. Our data showed that CPT pre-treatment inhibited VSMC proliferation, and that the inhibitory effect of CPT was enhanced by LY294002, a PI3K inhibitor, on PDGF-BB-induced VSMC proliferation. In addition, inhibiting the PI3K/Akt pathway by LY294002 significantly enhanced the suppression of PCNA expression and Akt activation by CPT. These results suggest that the anti-proliferative activity of CPT is mediated in part by downregulating the PI3K/Akt signaling pathway. - Highlights: ► CPT inhibits proliferation of PDGF-BB-induced VSMC without cytotoxicity. ► CPT arrests the cell cycle in G0/G1 phase by downregulation of cyclin D1 and CDK2. ► CPT significantly attenuates Akt phosphorylation in PDGF-BB signaling pathway. ► LY294002 enhanced the inhibitory effect of CPT on VSMC proliferation. ► Thus, CPT is mediated by downregulating the PI3K/Akt signaling pathway

Mechanism of inhibition of the tumor suppressor Patched by Sonic Hedgehog.

Science.gov (United States)

Tukachinsky, Hanna; Petrov, Kostadin; Watanabe, Miyako; Salic, Adrian

2016-10-04

The Hedgehog cell-cell signaling pathway is crucial for animal development, and its misregulation is implicated in numerous birth defects and cancers. In unstimulated cells, pathway activity is inhibited by the tumor suppressor membrane protein, Patched. Hedgehog signaling is triggered by the secreted Hedgehog ligand, which binds and inhibits Patched, thus setting in motion the downstream events in signal transduction. Despite its critical importance, the mechanism by which Hedgehog antagonizes Patched has remained unknown. Here, we show that vertebrate Patched1 inhibition is caused by direct, palmitate-dependent interaction with the Sonic Hedgehog ligand. We find that a short palmitoylated N-terminal fragment of Sonic Hedgehog binds Patched1 and, strikingly, is sufficient to inhibit it and to activate signaling. The rest of Sonic Hedgehog confers high-affinity Patched1 binding and internalization through a distinct binding site, but, surprisingly, it is not absolutely required for signaling. The palmitate-dependent interaction with Patched1 is specifically impaired in a Sonic Hedgehog mutant causing human holoprosencephaly, the most frequent congenital brain malformation, explaining its drastically reduced potency. The palmitate-dependent interaction is also abolished in constitutively inhibited Patched1 point mutants causing the Gorlin cancer syndrome, suggesting that they might adopt a conformation distinct from the wild type. Our data demonstrate that Sonic Hedgehog signals via the palmitate-dependent arm of a two-pronged contact with Patched1. Furthermore, our results suggest that, during Hedgehog signaling, ligand binding inhibits Patched by trapping it in an inactive conformation, a mechanism that explains the dramatically reduced activity of oncogenic Patched1 mutants.

An antitubulin agent BCFMT inhibits proliferation of cancer cells and induces cell death by inhibiting microtubule dynamics.

Directory of Open Access Journals (Sweden)

Ankit Rai

Full Text Available Using cell based screening assay, we identified a novel anti-tubulin agent (Z-5-((5-(4-bromo-3-chlorophenylfuran-2-ylmethylene-2-thioxothiazolidin-4-one (BCFMT that inhibited proliferation of human cervical carcinoma (HeLa (IC(50, 7.2 ± 1.8 µM, human breast adenocarcinoma (MCF-7 (IC(50, 10.0 ± 0.5 µM, highly metastatic breast adenocarcinoma (MDA-MB-231 (IC(50, 6.0 ± 1 µM, cisplatin-resistant human ovarian carcinoma (A2780-cis (IC(50, 5.8 ± 0.3 µM and multi-drug resistant mouse mammary tumor (EMT6/AR1 (IC(50, 6.5 ± 1 µM cells. Using several complimentary strategies, BCFMT was found to inhibit cancer cell proliferation at G2/M phase of the cell cycle apparently by targeting microtubules. In addition, BCFMT strongly suppressed the dynamics of individual microtubules in live MCF-7 cells. At its half maximal proliferation inhibitory concentration (10 µM, BCFMT reduced the rates of growing and shortening phases of microtubules in MCF-7 cells by 37 and 40%, respectively. Further, it increased the time microtubules spent in the pause (neither growing nor shortening detectably state by 135% and reduced the dynamicity (dimer exchange per unit time of microtubules by 70%. In vitro, BCFMT bound to tubulin with a dissociation constant of 8.3 ± 1.8 µM, inhibited tubulin assembly and suppressed GTPase activity of microtubules. BCFMT competitively inhibited the binding of BODIPY FL-vinblastine to tubulin with an inhibitory concentration (K(i of 5.2 ± 1.5 µM suggesting that it binds to tubulin at the vinblastine site. In cultured cells, BCFMT-treatment depolymerized interphase microtubules, perturbed the spindle organization and accumulated checkpoint proteins (BubR1 and Mad2 at the kinetochores. BCFMT-treated MCF-7 cells showed enhanced nuclear accumulation of p53 and its downstream p21, which consequently activated apoptosis in these cells. The results suggested that BCFMT inhibits proliferation of several types of cancer cells including drug

Guanine nucleotide binding to the Bateman domain mediates the allosteric inhibition of eukaryotic IMP dehydrogenases

Science.gov (United States)

Buey, Rubén M.; Ledesma-Amaro, Rodrigo; Velázquez-Campoy, Adrián; Balsera, Mónica; Chagoyen, Mónica; de Pereda, José M.; Revuelta, José L.

2015-11-01

Inosine-5'-monophosphate dehydrogenase (IMPDH) plays key roles in purine nucleotide metabolism and cell proliferation. Although IMPDH is a widely studied therapeutic target, there is limited information about its physiological regulation. Using Ashbya gossypii as a model, we describe the molecular mechanism and the structural basis for the allosteric regulation of IMPDH by guanine nucleotides. We report that GTP and GDP bind to the regulatory Bateman domain, inducing octamers with compromised catalytic activity. Our data suggest that eukaryotic and prokaryotic IMPDHs might have developed different regulatory mechanisms, with GTP/GDP inhibiting only eukaryotic IMPDHs. Interestingly, mutations associated with human retinopathies map into the guanine nucleotide-binding sites including a previously undescribed non-canonical site and disrupt allosteric inhibition. Together, our results shed light on the mechanisms of the allosteric regulation of enzymes mediated by Bateman domains and provide a molecular basis for certain retinopathies, opening the door to new therapeutic approaches.

Inhibition of neutral sphingomyelinase decreases elevated levels of inducible nitric oxide synthase and apoptotic cell death in ocular hypertensive rats

Energy Technology Data Exchange (ETDEWEB)

Aslan, Mutay, E-mail: mutayaslan@akdeniz.edu.tr [Department of Medical Biochemistry, Akdeniz University Faculty of Medicine, Antalya (Turkey); Basaranlar, Goksun [Department of Biophysics, Akdeniz University Faculty of Medicine, Antalya (Turkey); Unal, Mustafa [Department of Ophthalmology, Akdeniz University Faculty of Medicine, Antalya (Turkey); Ciftcioglu, Akif [Department of Pathology, Akdeniz University Faculty of Medicine, Antalya (Turkey); Derin, Narin [Department of Biophysics, Akdeniz University Faculty of Medicine, Antalya (Turkey); Mutus, Bulent [Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario (Canada)

2014-11-01

Endoplasmic reticulum (ER) stress and excessive nitric oxide production via induction of inducible nitric oxide synthase (NOS2) have been implicated in the pathogenesis of neuronal retinal cell death in ocular hypertension. Neutral sphingomyelinase (N-SMase)/ceramide pathway can regulate NOS2 expression, hence this study determined the role of selective neutral sphingomyelinase (N-SMase) inhibition on retinal NOS2 levels, ER stress, apoptosis and visual evoked potentials (VEPs) in a rat model of elevated intraocular pressure (EIOP). NOS2 expression and retinal protein nitration were significantly greater in EIOP and significantly decreased with N-SMase inhibition. A significant increase was observed in retinal ER stress markers pPERK, CHOP and GRP78 in EIOP, which were not significantly altered by N-SMase inhibition. Retinal TUNEL staining showed increased apoptosis in all EIOP groups; however N-SMase inhibition significantly decreased the percent of apoptotic cells in EIOP. Caspase-3, -8 and -9 activities were significantly increased in EIOP and returned to baseline levels following N-SMase inhibition. Latencies of all VEP components were significantly prolonged in EIOP and shortened following N-SMase inhibition. Data confirm the role of nitrative injury in EIOP and highlight the protective effect of N-SMase inhibition in EIOP via down-regulation of NOS2 levels and nitrative stress. - Highlights: • Inhibition of N-SMase decreases NOS2 levels in ocular hypertension. • Inhibition of N-SMase decreases protein nitration in ocular hypertension. • Inhibition of N-SMase decreases caspase activation in ocular hypertension. • Inhibition of N-SMase decreases apoptosis in ocular hypertension.

Characterization of melatonin binding sites in the Harderian gland and median eminence of the rat

International Nuclear Information System (INIS)

Lopez-Gonzalez, M.A.; Calvo, J.R.; Rubio, A.; Goberna, R.; Guerrero, J.M.

1991-01-01

The characterization of specific melatonin binding sites in the Harderian gland (HG) and median eminence (ME) of the rat was studied using [ 125 I]melatonin. Binding of melatonin to membrane crude preparations of both tissues was dependent on time and temperature. Thus, maximal binding was obtained at 37 degree C after 30-60 min incubation. Binding was also dependent on protein concentration. The specific binding of [ 125 I]melatonin was saturable, exhibiting only the class of binding sites in both tissues. The dissociation constants (Kd) were 170 and 190 pM for ME and HG, respectively. The concentration of the binding sites in ME was 8 fmol/mg protein, and in the HG 4 fmol/mg protein. In competition studies, binding of [ 125 I]melatonin to ME or HG was inhibited by increasing concentration of native melatonin; 50% inhibition was observed at about 702 and 422 nM for ME and HG, respectively. Additionally, the [ 125 I]melatonin binding to the crude membranes was not affected by the addition of different drugs such as norepinephrine, isoproterenol, phenylephrine, propranolol, or prazosin. The results confirm the presence of melatonin binding sites in median eminence and show, for the first time, the existence of melatonin binding sites in the Harderian gland

Polysulfonate suramin inhibits Zika virus infection.

Science.gov (United States)

Tan, Chee Wah; Sam, I-Ching; Chong, Wei Lim; Lee, Vannajan Sanghiran; Chan, Yoke Fun

2017-07-01

Zika virus (ZIKV) is an arthropod-borne flavivirus that causes newborn microcephaly and Guillian-Barré syndrome in adults. No therapeutics are available to treat ZIKV infection or other flaviviruses. In this study, we explored the inhibitory effect of glycosaminoglycans and analogues against ZIKV infection. Highly sulfated heparin, dextran sulfate and suramin significantly inhibited ZIKV infection in Vero cells. De-sulfated heparin analogues lose inhibitory effect, implying that sulfonate groups are critical for viral inhibition. Suramin, an FDA-approved anti-parasitic drug, inhibits ZIKV infection with 3-5 log 10  PFU viral reduction with IC 50 value of ∼2.5-5 μg/ml (1.93 μM-3.85 μM). A time-of-drug-addition study revealed that suramin remains potent even when administrated at 1-24 hpi. Suramin inhibits ZIKV infection by preventing viral adsorption, entry and replication. Molecular dynamics simulation revealed stronger interaction of suramin with ZIKV NS3 helicase than with the envelope protein. Suramin warrants further investigation as a potential antiviral candidate for ZIKV infection. Heparan sulfate (HS) is a cellular attachment receptor for multiple flaviviruses. However, no direct ZIKV-heparin interaction was observed in heparin-binding analysis, and downregulate or removal of cellular HS with sodium chlorate or heparinase I/III did not inhibit ZIKV infection. This indicates that cell surface HS is not utilized by ZIKV as an attachment receptor. Copyright © 2017 Elsevier B.V. All rights reserved.

Overlapping binding sites for trypsin and papain on a Kunitz-type proteinase inhibitor from Prosopis juliflora.

Science.gov (United States)

Franco, Octávio L; Grossi de Sá, Maria F; Sales, Maurício P; Mello, Luciane V; Oliveira, Adeliana S; Rigden, Daniel J

2002-11-15

Proteinase inhibitors are among the most promising candidates for expression by transgenic plants and consequent protection against insect predation. However, some insects can respond to the threat of the proteinase inhibitor by the production of enzymes insensitive to inhibition. Inhibitors combining more than one favorable activity are therefore strongly favored. Recently, a known small Kunitz trypsin inhibitor from Prosopis juliflora (PTPKI) has been shown to possess unexpected potent cysteine proteinase inhibitory activity. Here we show, by enzyme assay and gel filtration, that, unlike other Kunitz inhibitors with dual activities, this inhibitor is incapable of simultaneous inhibition of trypsin and papain. These data are most readily interpreted by proposing overlapping binding sites for the two enzymes. Molecular modeling and docking experiments favor an interaction mode in which the same inhibitor loop that interacts in a canonical fashion with trypsin can also bind into the papain catalytic site cleft. Unusual residue substitutions at the proposed interface can explain the relative rarity of twin trypsin/papain inhibition. Other changes seem responsible for the relative low affinity of PTPKI for trypsin. The predicted coincidence of trypsin and papain binding sites, once confirmed, would facilitate the search, by phage display for example, for mutants highly active against both proteinases. Copyright 2002 Wiley-Liss, Inc.

Quantifying siting difficulty: a case study of US transmission line siting

Energy Technology Data Exchange (ETDEWEB)

Vajjhala, S.P. [Resources for the Future, Washington DC (United States); Fischbeck, P.S. [Carnegie Mellon University, Pittsburgh, PA (United States). Departments of Social and Decision Sciences and Engineering and Public Policy

2007-01-15

The worldwide demand for new energy infrastructures has been paralleled in recent years by the increasing difficulty of siting major facilities. Siting difficulty is the subject of widespread discussion, but because of the complexity of the problem, potential solutions are not obvious or well understood. This paper presents a two-step policy-level framework that first develops an empirical measure of siting difficulty and then qualitatively assesses its major causes. The approach is based on the creation and aggregation of four siting indicators that are independent of the common causes and localized effects of siting problems. The proposed framework is demonstrated for the case of US transmission line siting. Results of the analyses reveal significant variations in state siting difficulty and industry experts' perceptions of its dominant causes, with implications for the long-term success of Regional Transmission Organizations (RTOs) and knowledge transfer among siting professionals in the deregulated industry. (author)

Environmental Regulatory Compliance Plan for site: Draft characterization of the Yucca Mountain site:Draft

International Nuclear Information System (INIS)

1988-01-01

The objective of the EMMP is to document compliance with the NWPA. To do so, a summary description of site characterization activites is provided, based on the consultation draft of the SCP. Subsequent chpaters identify those technical areas having the potential to be impacted by site characterization activities and the monitoring plans proposed to identify whether those impacts acutally occur. Should monitoring confirm the potential for significant adverse impact, mitigative measures will be developed. In the context of site characterization, mitigation is defined as those changes in site characterization activities that serve to avoid or minimize, to the maximum extent practicle, any significant adverse environmental impacts. Although site characterization activies involve both surface and subsurface activities, it is the surface-based aspect of site characterization that is addressed in detailed by the EMMP. The schedule and duration of these activities is given in the consultation draft of the SCP. A breif summary of all proposed activities is given in the EMMP. 10 refs., 8 figs

Inhibition of Ku70 acetylation by INHAT subunit SET/TAF-Iβ regulates Ku70-mediated DNA damage response.

Science.gov (United States)

Kim, Kee-Beom; Kim, Dong-Wook; Park, Jin Woo; Jeon, Young-Joo; Kim, Daehwan; Rhee, Sangmyung; Chae, Jung-Il; Seo, Sang-Beom

2014-07-01

DNA double-strand breaks (DSBs) can cause either cell death or genomic instability. The Ku heterodimer Ku70/80 is required for the NHEJ (non-homologous end-joining) DNA DSB repair pathway. The INHAT (inhibitor of histone acetyltransferases) complex subunit, SET/TAF-Iβ, can inhibit p300- and PCAF-mediated acetylation of both histone and p53, thereby repressing general transcription and that of p53 target genes. Here, we show that SET/TAF-Iβ interacts with Ku70/80, and that this interaction inhibits CBP- and PCAF-mediated Ku70 acetylation in an INHAT domain-dependent manner. Notably, DNA damage by UV disrupted the interaction between SET/TAF-Iβ and Ku70. Furthermore, we demonstrate that overexpressed SET/TAF-Iβ inhibits recruitment of Ku70/80 to DNA damage sites. We propose that dysregulation of SET/TAF-Iβ expression prevents repair of damaged DNA and also contributes to cellular proliferation. All together, our findings indicate that SET/TAF-Iβ interacts with Ku70/80 in the nucleus and inhibits Ku70 acetylation. Upon DNA damage, SET/TAF-Iβ dissociates from the Ku complex and releases Ku70/Ku80, which are then recruited to DNA DSB sites via the NHEJ DNA repair pathway.

Thienoquinolins exert diuresis by strongly inhibiting UT-A urea transporters

Science.gov (United States)

Ren, Huiwen; Wang, Yanhua; Xing, Yongning; Ran, Jianhua; Liu, Ming; Lei, Tianluo; Zhou, Hong; Li, Runtao; Sands, Jeff M.

2014-01-01

Urea transporters (UT) play an important role in the urine concentration mechanism by mediating intrarenal urea recycling, suggesting that UT inhibitors could have therapeutic use as a novel class of diuretic. Recently, we found a thienoquinolin UT inhibitor, PU-14, that exhibited diuretic activity. The purpose of this study was to identify more potent UT inhibitors that strongly inhibit UT-A isoforms in the inner medullary collecting duct (IMCD). Efficient thienoquinolin UT inhibitors were identified by structure-activity relationship analysis. Urea transport inhibition activity was assayed in perfused rat terminal IMCDs. Diuretic activity of the compound was determined in rats and mice using metabolic cages. The results show that the compound PU-48 exhibited potent UT-A inhibition activity. The inhibition was 69.5% with an IC50 of 0.32 μM. PU-48 significantly inhibited urea transport in perfused rat terminal IMCDs. PU-48 caused significant diuresis in UT-B null mice, which indicates that UT-A is the target of PU-48. The diuresis caused by PU-48 did not change blood Na+, K+, or Cl− levels or nonurea solute excretion in rats and mice. No toxicity was detected in cells or animals treated with PU-48. The results indicate that thienoquinolin UT inhibitors induce a diuresis by inhibiting UT-A in the IMCD. This suggests that they may have the potential to be developed as a novel class of diuretics with fewer side effects than classical diuretics. PMID:25298523

Combination of rapamycin, CI-1040, and 17-AAG inhibits metastatic capacity of prostate cancer via Slug inhibition.

Directory of Open Access Journals (Sweden)

Guanxiong Ding

Full Text Available Though prostate cancer (PCa has slow progression, the hormone refractory (HRCP and metastatic entities are substantially lethal and lack effective treatments. Transcription factor Slug is critical in regulating metastases of various tumors including PCa. Here we studied targeted therapy against Slug using combination of 3 drugs targeting 3 pathways respectively converging via Slug and further regulating PCa metastasis. Using in vitro assays we confirmed that Slug up-regulation incurred inhibition of E-cadherin that was anti-metastatic, and inhibited Bim-regulated cell apoptosis in PCa. Upstream PTEN/Akt, mTOR, Erk, and AR/Hsp90 pathways were responsible for Slug up-regulation and each of these could be targeted by rapamycin, CI-1040, and 17-AAG respectively. In 4 PCa cell lines with different traits in terms of PTEN loss and androgen sensitivity we tested the efficacy of mono- and combined therapy with the drugs. We found that metastatic capacity of the cells was maximally inhibited only when all 3 drugs were combined, due to the crosstalk between the pathways. 17-AAG decreases Slug expression via blockade of HSP90-dependent AR stability. Combination of rapamycin and CI-1040 diminishes invasiveness more potently in PCa cells that are androgen insensitive and with PTEN loss. Slug inhibited Bim-mediated apoptosis that could be rescued by mTOR/Erk/HSP90 inhibitors. Using mouse models for circulating PCa DNA quantification, we found that combination of mTOR/Erk/HSP90 inhibitors reduced circulating PCa cells in vivo significantly more potently than combination of 2 or monotherapy. Conclusively, combination of mTOR/Erk/Hsp90 inhibits metastatic capacity of prostate cancer via Slug inhibition.

Exposure to waterborne Cu inhibits cutaneous Na⁺ uptake in post-hatch larval rainbow trout (Oncorhynchus mykiss).

Science.gov (United States)

Zimmer, Alex M; Brauner, Colin J; Wood, Chris M

2014-05-01

In freshwater rainbow trout (Oncorhynchus mykiss), two common responses to acute waterborne copper (Cu) exposure are reductions in ammonia excretion and Na(+) uptake at the gills, with the latter representing the likely lethal mechanism of action for Cu in adult fish. Larval fish, however, lack a functional gill following hatch and rely predominantly on cutaneous exchange, yet represent the most Cu-sensitive life stage. It is not known if Cu toxicity in larval fish occurs via the skin or gills. The present study utilized divided chambers to assess cutaneous and branchial Cu toxicity over larval development, using disruptions in ammonia excretion (Jamm) and Na(+) uptake (Jin(Na)) as toxicological endpoints. Early in development (early; 3 days post-hatch; dph), approximately 95% of Jamm and 78% of Jin(Na) occurred cutaneously, while in the late developmental stage (late; 25 dph), the gills were the dominant site of exchange (83 and 87% of Jamm and Jin(Na), respectively). Exposure to 50 μg/l Cu led to a 49% inhibition of Jamm in the late developmental stage only, while in the early and middle developmental (mid; 17 dph) stages, Cu had no effect on Jamm. Jin(Na), however, was significantly inhibited by Cu exposure at the early (53% reduction) and late (47% reduction) stages. Inhibition at the early stage of development was mediated by a reduction in cutaneous uptake, representing the first evidence of cutaneous metal toxicity in an intact aquatic organism. The inhibitions of both Jamm and Jin(Na) in the late developmental stage occurred via a reduction in branchial exchange only. The differential responses of the skin and gills to Cu exposure suggest that the mechanisms of Jamm and Jin(Na) and/or Cu toxicity differ between these tissues. Exposure to 20μg/l Cu revealed that Jamm is the more Cu-sensitive process. The results presented here have important implications in predicting metal toxicity in larval fish. The Biotic Ligand Model (BLM) is currently used to predict

LRP-mediated clearance of Abeta is inhibited by KPI-containing isoforms of APP.

Science.gov (United States)

Moir, Robert D; Tanzi, Rudolph E

2005-04-01

The pathogenesis of Alzheimer's disease (AD) involves the abnormal accumulation and deposition of beta-amyloid in cerebral blood vessels and in the brain parenchyma. Critical in modulating beta-amyloid deposition in brain is the flux of Abeta across the blood brain barrier. The low-density lipoprotein receptor-related protein (LRP), is a large endocytic receptor that mediates the efflux of Abeta out of brain and into the periphery. The first step in the LRP-mediated clearance of Abeta involves the formation of a complex between Abeta and the LRP ligands apolipoprotein E (apoE) or alpha(2)-macroglobulin (alpha(2)M). The Abeta/chaperone complexes then bind to LRP via binding sites on apoE or alpha(2)M. The efflux of Abeta/chaperone complexes out of the neuropil and into the periphery may be attenuated by LRP-ligands that compete with apoE or alpha(2)M for LRP binding. LRP is also the cell surface receptor for Kunitz Protease Inhibitor (KPI) containing isoforms of Abeta's parent protein, the amyloid protein precursor (APP). Protein and mRNA levels of KPI-containing APP isoforms (APP-KPI) are elevated in AD brain and are associated with increased Abeta production. In this study we show that soluble non-amyloidogenic APP-KPI can also inhibit the uptake of Abeta/alpha(2)M in a cell culture model of LRP mediated Abeta clearance. Clearance of Abeta/apoE complexes was not inhibited by APP-KPI. Our findings are consistent with studies showing that apoE and alpha(2)M have discrete binding sites on LRP. Most significantly, our data suggests that the elevated levels of APP-KPI in AD brain may attenuate the clearance of Abeta, the proteins own amyloidogenic catabolic product.

Polypyridylruthenium(II complexes exert in vitro and in vivo nematocidal activity and show significant inhibition of parasite acetylcholinesterases

Directory of Open Access Journals (Sweden)

Madhu Sundaraneedi

2018-04-01

Full Text Available Over 4.5 billion people are at risk of infection with soil transmitted helminths and there are concerns about the development of resistance to the handful of frontline nematocides in endemic populations. We investigated the anti-nematode efficacy of a series of polypyridylruthenium(II complexes and showed they were active against L3 and adult stages of Trichuris muris, the rodent homologue of the causative agent of human trichuriasis, T. trichiura. One of the compounds, Rubb12-mono, which was among the most potent in its ability to kill L3 (IC50 = 3.1 ± 0.4 μM and adult (IC50 = 5.2 ± 0.3 μM stage worms was assessed for efficacy in a mouse model of trichuriasis by administering 3 consecutive daily oral doses of the drug 3 weeks post infection with the murine whipworm Trichuris muris. Mice treated with Rubb12-mono showed an average 66% reduction (P = 0.015 in faecal egg count over two independent trials. The drugs partially exerted their activity through inhibition of acetylcholinesterases, as worms treated in vitro and in vivo showed significant decreases in the activity of this class of enzymes. Our data show that ruthenium complexes are effective against T. muris, a model gastro-intestinal nematode and soil-transmitted helminth. Further, knowledge of the target of ruthenium drugs can facilitate modification of current compounds to identify analogues which are even more effective and selective against Trichuris and other helminths of human and veterinary importance. Keywords: Acetylcholinesterase, Trichuris muris, Ruthenium complex, Anthelmintic

Cardiovirus Leader proteins bind exportins: Implications for virus replication and nucleocytoplasmic trafficking inhibition

Energy Technology Data Exchange (ETDEWEB)

Ciomperlik, Jessica J. [Institute for Molecular Virology and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706 (United States); Basta, Holly A. [Department of Biology, Rocky Mountain College, Billings, MT (United States); Palmenberg, Ann C., E-mail: acpalmen@wisc.edu [Institute for Molecular Virology and Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706 (United States)

2016-01-15

Cardiovirus Leader proteins (L{sub X}) inhibit cellular nucleocytoplasmic trafficking by directing host kinases to phosphorylate Phe/Gly-containing nuclear pore proteins (Nups). Resolution of the Mengovirus L{sub M} structure bound to Ran GTPase, suggested this complex would further recruit specific exportins (karyopherins), which in turn mediate kinase selection. Pull-down experiments and recombinant complex reconstitution now confirm that Crm1 and CAS exportins form stable dimeric complexes with encephalomyocarditis virus L{sub E}, and also larger complexes with L{sub E}:Ran. shRNA knockdown studies support this idea. Similar activities could be demonstrated for recombinant L{sub S} and L{sub T} from Theiloviruses. When mutations were introduced to alter the L{sub E} zinc finger domain, acidic domain, or dual phosphorylation sites, there was reduced exportin selection. These regions are not involved in Ran interactions, so the Ran and Crm1 binding sites on L{sub E} must be non-overlapping. The involvement of exportins in this mechanism is important to viral replication and the observation of trafficking inhibition by L{sub E}.

TNF-α inhibits trophoblast integration into endothelial cellular networks.

Science.gov (United States)

Xu, B; Nakhla, S; Makris, A; Hennessy, A

2011-03-01

Preeclampsia has been linked to shallow trophoblast invasion and failure of uterine spiral artery transformation. Interaction between trophoblast cells and maternal uterine endothelium is critically important for this remodelling. The aim of our study was to investigate the effect of TNF-α on the interactions of trophoblast-derived JEG-3 cells into capillary-like cellular networks. We have employed an in vitro trophoblast-endothelial cell co-culture model to quantify trophoblast integration into endothelial cellular networks and to investigate the effects of TNF-α. Controlled co-cultures were also treated with anti-TNF-α antibody (5 μg/ml) to specifically block the effect of TNF-α. The invasion was evaluated by performing quantitative PCR (Q-PCR) to analyse gene expression of matrix metalloproteinases-2 (MMP-2), MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1, integrins (α(1)β(1) and α(6)β(4)), plasminogen activator inhibitor (PAI)-1, E-cadherin and VE-cadherin. JEG-3 cell integration into endothelial networks was significantly inhibited by exogenous TNF-α. The inhibition was observed in the range of 0.2-5 ng/ml, to a maximum 56% inhibition at the highest concentration. This inhibition was reversed by anti-TNF-α antibody. Q-PCR analysis showed that mRNA expression of integrins α(1)β(1) and MMP-2 was significantly decreased. VE-cadherin mRNA expression was significantly up-regulated (32-80%, p integration into maternal endothelial cellular networks, and this process involves the inhibition of MMP-2 and a failure of integrins switch from α(6)β(4) to α(1)β(1.) These molecular correlations reflect the changes identified in human preeclampsia. Copyright © 2011 Elsevier Ltd. All rights reserved.

Inhibition of protein kinase A activity interferes with long-term, but not short-term, memory of conditioned taste aversions.

Science.gov (United States)

Koh, Ming Teng; Thiele, Todd E; Bernstein, Ilene L

2002-12-01

The present experiments examined whether inhibition of cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) activity interferes with conditioned taste aversion (CTA) memories. Rats were centrally infused with the selective PKA inhibitor Rp-adenosine 3',5'-cyclic monophosphothioate triethylamine (Rp-cAMPS) before conditioning. Direct infusions of Rp-cAMPS into the amygdala showed no interference with short-term memory but did show significant attenuation of long-term memory and more rapid extinction. Results suggest that PKA activity is involved in the consolidation of long-term memory of CTAs, and that the amygdala may be 1 site that is important for this activity.

Aspergillus ficuum phytase activity is inhibited by cereal grain components.

Science.gov (United States)

Bekalu, Zelalem Eshetu; Madsen, Claus Krogh; Dionisio, Giuseppe; Brinch-Pedersen, Henrik

2017-01-01

In the current study, we report for the first time that grain components of barley, rice, wheat and maize can inhibit the activity of Aspergillus ficuum phytase. The phytase inhibition is dose dependent and varies significantly between cereal species, between cultivars of barley and cultivars of wheat and between Fusarium graminearum infected and non-infected wheat grains. The highest endpoint level of phytase activity inhibition was 90%, observed with grain protein extracts (GPE) from F. graminearum infected wheat. Wheat GPE from grains infected with F. graminearum inhibits phytase activity significantly more than GPE from non-infected grains. For four barley cultivars studied, the IC50 value ranged from 0.978 ± 0.271 to 3.616 ± 0.087 mg×ml-1. For two non-infected wheat cultivars investigated, the IC50 values were varying from 2.478 ± 0.114 to 3.038 ± 0.097 mg×ml-1. The maize and rice cultivars tested gaveIC50 values on 0.983 ± 0.205 and 1.972 ± 0.019 mg×ml-1, respectively. After purifying the inhibitor from barley grains via Superdex G200, an approximately 30-35 kDa protein was identified. No clear trend for the mechanism of inhibition could be identified via Michaelis-Menten kinetics and Lineweaver-Burk plots. However, testing of the purified phytase inhibitor together with the A. ficuum phytase and the specific protease inhibitors pepstatin A, E64, EDTA and PMSF revealed that pepstatin A repealed the phytase inhibition. This indicates that the observed inhibition of A. ficuum phytase by cereal grain extracts is caused by protease activity of the aspartic proteinase type.

Global inhibition of reactive oxygen species (ROS inhibits paclitaxel-induced painful peripheral neuropathy.

Directory of Open Access Journals (Sweden)

Mehmet Fidanboylu

Full Text Available Paclitaxel (Taxol® is a widely used chemotherapeutic agent that has a major dose limiting side-effect of painful peripheral neuropathy. Currently there is no effective therapy for the prevention or treatment of chemotherapy-induced painful peripheral neuropathies. Evidence for mitochondrial dysfunction during paclitaxel-induced pain was previously indicated with the presence of swollen and vacuolated neuronal mitochondria. As mitochondria are a major source of reactive oxygen species (ROS, the aim of this study was to examine whether pharmacological inhibition of ROS could reverse established paclitaxel-induced pain or prevent the development of paclitaxel-induced pain. Using a rat model of paclitaxel-induced pain (intraperitoneal 2 mg/kg paclitaxel on days 0, 2, 4 & 6, the effects of a non-specific ROS scavenger, N-tert-Butyl-α-phenylnitrone (PBN and a superoxide selective scavenger, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL were compared. Systemic 100 mg/kg PBN administration markedly inhibited established paclitaxel-induced mechanical hypersensitivity to von Frey 8 g and 15 g stimulation and cold hypersensitivity to plantar acetone application. Daily systemic administration of 50 mg/kg PBN (days -1 to 13 completely prevented mechanical hypersensitivity to von Frey 4 g and 8 g stimulation and significantly attenuated mechanical hypersensitivity to von Frey 15 g. Systemic 100 mg/kg TEMPOL had no effect on established paclitaxel-induced mechanical or cold hypersensitivity. High dose (250 mg/kg systemic TEMPOL significantly inhibited mechanical hypersensitivity to von Frey 8 g & 15 g, but to a lesser extent than PBN. Daily systemic administration of 100 mg/kg TEMPOL (day -1 to 12 did not affect the development of paclitaxel-induced mechanical hypersensitivity. These data suggest that ROS play a causal role in the development and maintenance of paclitaxel-induced pain, but such effects cannot be attributed to superoxide radicals

Zoledronic acid inhibits pulmonary metastasis dissemination in a preclinical model of Ewing’s sarcoma via inhibition of cell migration

International Nuclear Information System (INIS)

Odri, Guillaume; Kim, Pui-Pui; Lamoureux, François; Charrier, Céline; Battaglia, Séverine; Amiaud, Jérôme; Heymann, Dominique; Gouin, François; Redini, Françoise

2014-01-01

Ewing’s sarcoma (ES) is the second most frequent primitive malignant bone tumor in adolescents with a very poor prognosis for high risk patients, mainly when lung metastases are detected (overall survival <15% at 5 years). Zoledronic acid (ZA) is a potent inhibitor of bone resorption which induces osteoclast apoptosis. Our previous studies showed a strong therapeutic potential of ZA as it inhibits ES cell growth in vitro and ES primary tumor growth in vivo in a mouse model developed in bone site. However, no data are available on lung metastasis. Therefore, the aim of this study was to determine the effect of ZA on ES cell invasion and metastatic properties. Invasion assays were performed in vitro in Boyden’s chambers covered with Matrigel. Matrix Metalloproteinase (MMP) activity was analyzed by zymography in ES cell culture supernatant. In vivo, a relevant model of spontaneous lung metastases which disseminate from primary ES tumor was induced by the orthotopic injection of 10 6 human ES cells in the tibia medullar cavity of nude mice. The effect of ZA (50 μg/kg, 3x/week) was studied over a 4-week period. Lung metastases were observed macroscopically at autopsy and analysed by histology. ZA induced a strong inhibition of ES cell invasion, probably due to down regulation of MMP-2 and −9 activities as analyzed by zymography. In vivo, ZA inhibits the dissemination of spontaneous lung metastases from a primary ES tumor but had no effect on the growth of established lung metastases. These results suggest that ZA could be used early in the treatment of ES to inhibit bone tumor growth but also to prevent the early metastatic events to the lungs

Photoaffinity labeling of the lumenal K+ site of the gastric (H+ + K+)-ATPase

International Nuclear Information System (INIS)

Keeling, D.J.; Fallowfield, C.; Lawrie, K.M.; Saunders, D.; Richardson, S.; Ife, R.J.

1989-01-01

A photoaffinity label for the lumenal K+ site of the gastric (H+ + K+)-ATPase has been identified. Seven azido derivatives based upon the reversible K+ site inhibitor SCH 28080 were studied, one of which, m-ATIP (8-(3-azidophenylmethoxy)-1,2,3-trimethylimidazo[1,2-a] pyridinium iodide), was subsequently synthesized in radiolabeled form. In the absence of UV irradiation, m-ATIP inhibited K+ -stimulated ATPase activity in lyophilized gastric vesicles competitively with respect to K+, with a Ki value of 2.4 microM at pH 7.0. Irradiation of lyophilized gastric vesicles at pH 7.0 with [ 14 C]m-ATIP in the presence of 0.2 mM ATP resulted in a time-dependent inactivation of ATPase activity that was associated with an incorporation of radioactivity into a 100-kDa polypeptide representing the catalytic subunit of the (H+ + K+)-ATPase. Both inactivation and incorporation were blocked in the presence of 10 mM KCl but not with 10 mM NaCl, consistent with interaction at the K+ site. The level of incorporation required to produce complete inhibition of ATPase activity was 1.9 +/- 0.2 times the number of catalytic phosphorylation sites in the same preparation. Tryptic digestion of gastric vesicle membranes, labeled with [ 14 C]m-ATIP, failed to release the radioactivity from the membranes suggesting that the site of interaction was close to or within the membrane-spanning sections of this ion pump

Proactive modulation of long-interval intracortical inhibition during response inhibition

Science.gov (United States)

Cowie, Matthew J.; MacDonald, Hayley J.; Cirillo, John

2016-01-01

Daily activities often require sudden cancellation of preplanned movement, termed response inhibition. When only a subcomponent of a whole response must be suppressed (required here on Partial trials), the ensuing component is markedly delayed. The neural mechanisms underlying partial response inhibition remain unclear. We hypothesized that Partial trials would be associated with nonselective corticomotor suppression and that GABAB receptor-mediated inhibition within primary motor cortex might be responsible for the nonselective corticomotor suppression contributing to Partial trial response delays. Sixteen right-handed participants performed a bimanual anticipatory response inhibition task while single- and paired-pulse transcranial magnetic stimulation was delivered to elicit motor evoked potentials in the left first dorsal interosseous muscle. Lift times, amplitude of motor evoked potentials, and long-interval intracortical inhibition were examined across the different trial types (Go, Stop-Left, Stop-Right, Stop-Both). Go trials produced a tight distribution of lift times around the target, whereas those during Partial trials (Stop-Left and Stop-Right) were substantially delayed. The modulation of motor evoked potential amplitude during Stop-Right trials reflected anticipation, suppression, and subsequent reinitiation of movement. Importantly, suppression was present across all Stop trial types, indicative of a “default” nonselective inhibitory process. Compared with blocks containing only Go trials, inhibition increased when Stop trials were introduced but did not differ between trial types. The amount of inhibition was positively correlated with lift times during Stop-Right trials. Tonic levels of inhibition appear to be proactively modulated by task context and influence the speed at which unimanual responses occur after a nonselective “brake” is applied. PMID:27281744

Inhibition of the Ras-Net (Elk-3) pathway by a novel pyrazole that affects microtubules.

Science.gov (United States)

Wasylyk, Christine; Zheng, Hong; Castell, Christelle; Debussche, Laurent; Multon, Marie-Christine; Wasylyk, Bohdan

2008-03-01

Net (Elk-3/SAP-2/Erp) is a transcription factor that is phosphorylated and activated by the Ras-extracellular signal-regulated kinase (Erk) signaling pathway and is involved in wound healing, angiogenesis, and tumor growth. In a cell-based screen for small molecule inhibitors of Ras activation of Net transcriptional activity, we identified a novel pyrazole, XRP44X. XRP44X inhibits fibroblast growth factor 2 (FGF-2)-induced Net phosphorylation by the Ras-Erk signaling upstream from Ras. It also binds to the colchicine-binding site of tubulin, depolymerizes microtubules, stimulates cell membrane blebbing, and affects the morphology of the actin skeleton. Interestingly, Combretastin-A4, which produces similar effects on the cytoskeleton, also inhibits FGF-2 Ras-Net signaling. This differs from other classes of agents that target microtubules, which have either little effect (vincristine) or no effect (docetaxel and nocodazole) on the Ras-Net pathway. XRP44X inhibits various cellular properties, including cell growth, cell cycle progression, and aortal sprouting, similar to other molecules that bind to the tubulin colchicine site. XRP44X has the potentially interesting property of connecting two important pathways involved in cell transformation and may thereby represent an interesting class of molecules that could be developed for cancer treatment.

Structural basis for alpha fetoprotein-mediated inhibition of caspase-3 activity in hepatocellular carcinoma cells.

Science.gov (United States)

Lin, Bo; Zhu, Mingyue; Wang, Wenting; Li, Wei; Dong, Xu; Chen, Yi; Lu, Yan; Guo, Junli; Li, Mengsen

2017-10-01

Alpha-fetoprotein (AFP) is an early serum growth factor in the foetal liver development and hepatic carcinogenesis; However, the precise biological role of cytoplasmic AFP remains elusive. Although we recently demonstrated that cytoplasmic AFP might interact with caspase-3 and inhibit the signal transduction of apoptosis in human hepatocellular carcinoma (HCC) cells, the details of this interaction are not clear. To reveal the molecular relationship between AFP and caspase-3, we performed molecular docking, co-immunoprecipitation (Co-IP), laser confocal microscopy, site-directed mutagenesis and functional experiments to analyse the key amino acid residues in the binding site of caspase-3. The results of Co-IP, laser confocal microscopy and functional analyses were consistent with the computational model. We also used the model to explain why AFP cannot bind to caspase-8. These results provide the molecular basis for the AFP-mediated inhibition of caspase-3 activity in HCC cells. Altogether, we found that AFP interacts with caspase-3 through precise amino acids, namely loop-4 residues Glu-248, Asp-253 and His-257. The results further demonstrated that AFP plays a critical role in the inhibition of the apoptotic signal transduction that mediated by caspase-3. Thus, AFP might represent a novel biotarget for the therapy of HCC patients. © 2017 UICC.

Angiotensin-converting enzyme inhibition in diabetic nephropathy

DEFF Research Database (Denmark)

Parving, H H; Rossing, P; Hommel, E

1995-01-01

The aim of our prospective study was to evaluate putative progression promoters, kidney function, and prognosis during long-term treatment with angiotensin-converting enzyme inhibition in insulin-dependent diabetes mellitus patients suffering from diabetic nephropathy. Eighteen consecutive......, albuminuria (geometric mean +/- antilog SE) 982 +/- 1.2 micrograms/min, and GFR 98 +/- 5 mL/min/1.73 m2. Angiotensin-converting enzyme inhibition induced a significant reduction during the whole treatment period of blood pressure (137/85 +/- 3/1 mm Hg; P ....01), and the rate of decline in GFR was 4.4 +/- 0.7 mL/min/yr, in contrast to previous reports of 10 to 14 mL/min/yr (natural history). Univariate analysis revealed a significant correlation between the rate of decline in GFR and mean arterial blood pressure (r = 0.58, P = 0.01), albuminuria (r = 0.67, P

Plant-microbial association in petroleum and gas exploration sites in the state of Assam, north-east India-significance for bioremediation.

Science.gov (United States)

Sarma, Hemen; Islam, N F; Prasad, M N V

2017-03-01

The state of Assam in north-east India gained popularity in Asia because of discovery of oil. Pollution due to petroleum and gas exploration is a serious problem in Assam. Oil and gas exploration by various agencies in Assam resulted in soil pollution due to hydrocarbons (HCs) and heavy metals (HMs). Bioremediation gained considerable significance in addressing petroleum hydrocarbon polluted sites in various parts of the world. In this investigation, we have observed 15 species of plants belonging to grass growing on the contaminated soils. Among 15 species of grasses, 10 species with high important value index (IVI) were found to be better adapted. The highest IVI is exhibited by Axonopus compressus (21.41), and this grass can be identified as key ecological tool in the rehabilitation of the degraded site. But no definite correlation between the IVI and the biomass of the various grass existed in the study sites. Chemical study of rhizosphere (RS) and non-rhizosphere (NRS) soil of these grasses revealed both aromatic and aliphatic compounds (M.W. 178-456). Four-ring pyrene was detected in NRS soil but not in RS soil. Microbiological study of RS and NRS soil showed high colony-forming unit (CFU) of HC-degrading microbes in RS compared to NRS. The increased microbial catabolism in RS soil established the fact that pyrene is transformed to aliphatic compounds. Metals in RS soil ranged from (in mg kg -1 ) 222.6 to 267.3 (Cr), 854 to 956 (Pb) and 180 to 247 (Ni), but despite the very high total metal concentration in RS and NRS soil, the CaCl 2 -extracted metals were relatively low in RS soil (1.04 for Cr, 0.56 for Pb, 0.35 for Ni). Plants with the highest uptake of metals were Leersia hexandra (36.43 mg Cr kg -1 ) and Kyllinga brevifolia (67.73 mg Pb kg -1 and 40.24 mg Ni kg -1 ). These plant species could be potentially exploited for biomonitoring and bioremediation. Out of 15 plant species, 8 of them have high percentages of cellulose, crude fibres, lignin

Inhibition of Collagenase by Mycosporine-like Amino Acids from Marine Sources

Science.gov (United States)

Hartmann, Anja; Gostner, Johanna; Fuchs, Julian E.; Chaita, Eliza; Aligiannis, Nektarios; Skaltsounis, Leandros; Ganzera, Markus

2015-01-01

Matrix metalloproteinases (MMP) play an important role in extracellular matrix remodeling. Excessive activity of these enzymes can be induced by UV light and leads to skin damage, a process known as photoaging. In this study we investigated the collagenase inhibition potential of mycosporine-like amino acids (MAA), compounds that have been isolated from marine organisms and are known photoprotectants against UV-A and UV-B. For this purpose the commonly used collagenase assay was optimized and for the first time validated in terms of relationships between enzyme-substrate concentrations, temperature, incubation time and enzyme stability. Three compounds were isolated from the marine red algae Porphyra sp. and Palmaria palmata, and evaluated for their inhibitory properties against Chlostridium histolyticum collagenase (Chc). A dose-dependent, but very moderate inhibition was observed for all substances and IC50 values of 104.0 μM for shinorine, 105.9 μM for porphyra and 158.9 μM for palythine were determined. Additionally, computer-aided docking models suggested that the MAA binding to the active site of the enzyme is a competitive inhibition. PMID:26039265

Targeting the SH2-kinase interface in Bcr-Abl inhibits leukemogenesis.

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Grebien, Florian; Hantschel, Oliver; Wojcik, John; Kaupe, Ines; Kovacic, Boris; Wyrzucki, Arkadiusz M; Gish, Gerald D; Cerny-Reiterer, Sabine; Koide, Akiko; Beug, Hartmut; Pawson, Tony; Valent, Peter; Koide, Shohei; Superti-Furga, Giulio

2011-10-14

Chronic myelogenous leukemia (CML) is caused by the constitutively active tyrosine kinase Bcr-Abl and treated with the tyrosine kinase inhibitor (TKI) imatinib. However, emerging TKI resistance prevents complete cure. Therefore, alternative strategies targeting regulatory modules of Bcr-Abl in addition to the kinase active site are strongly desirable. Here, we show that an intramolecular interaction between the SH2 and kinase domains in Bcr-Abl is both necessary and sufficient for high catalytic activity of the enzyme. Disruption of this interface led to inhibition of downstream events critical for CML signaling and, importantly, completely abolished leukemia formation in mice. Furthermore, disruption of the SH2-kinase interface increased sensitivity of imatinib-resistant Bcr-Abl mutants to TKI inhibition. An engineered Abl SH2-binding fibronectin type III monobody inhibited Bcr-Abl kinase activity both in vitro and in primary CML cells, where it induced apoptosis. This work validates the SH2-kinase interface as an allosteric target for therapeutic intervention. Copyright © 2011 Elsevier Inc. All rights reserved.

SKLB060 Reversibly Binds to Colchicine Site of Tubulin and Possesses Efficacy in Multidrug-Resistant Cell Lines.

Science.gov (United States)

Yan, Wei; Yang, Tao; Yang, Jianhong; Wang, Taijin; Yu, Yamei; Wang, Yuxi; Chen, Qiang; Bai, Peng; Li, Dan; Ye, Haoyu; Qiu, Qiang; Zhou, Yongzhao; Hu, Yiguo; Yang, Shengyong; Wei, Yuquan; Li, Weimin; Chen, Lijuan

2018-05-22

Many tubulin inhibitors are in clinical use as anti-cancer drugs. In our previous study, a novel series of 4-substituted coumarins derivatives were identified as novel tubulin inhibitors. Here, we report the anti-cancer activity and underlying mechanism of one of the 4-substituted coumarins derivatives (SKLB060). The anti-cancer activity of SKLB060 was tested on 13 different cancer cell lines and four xenograft cancer models. Immunofluorescence staining, cell cycle analysis, and tubulin polymerization assay were employed to study the inhibition of tubulin. N, N '-Ethylenebis(iodoacetamide) assay was used to measure binding to the colchicine site. Wound-healing migration and tube formation assays were performed on human umbilical vascular endothelial cells to study anti-vascular activity (the ability to inhibit blood vessel growth). Mitotic block reversibility and structural biology assays were used to investigate the SKLB060-tubulin bound model. SKLB060 inhibited tubulin polymerization and subsequently induced G2/M cell cycle arrest and apoptosis in cancer cells. SKLB060 bound to the colchicine site of β-tubulin and showed antivascular activity in vitro. Moreover, SKLB060 induced reversible cell cycle arrest and reversible inhibition of tubulin polymerization. A mitotic block reversibility assay showed that the effects of SKLB060 have greater reversibility than those of colcemid (a reversible tubulin inhibitor), indicating that SKLB060 binds to tubulin in a totally reversible manner. The crystal structures of SKLB060-tubulin complexes confirmed that SKLB060 binds to the colchicine site, and the natural coumarin ring in SKLB060 enables reversible binding. These results reveal that SKLB060 is a powerful and reversible microtubule inhibitor that binds to the colchicine site and is effective in multidrug-resistant cell lines. © 2018 The Author(s). Published by S. Karger AG, Basel.

Inhibition of glycolysis by misonidazole in hypoxic cells

International Nuclear Information System (INIS)

Ling, L.; Sutherland, R.

1984-01-01

Inhibition of glycolysis has been postulated to be a mechanism of misonidazole (MISO) toxicity in hypoxic cells. To investigate the effect of MISO on glycolysis, glucose transport and its consumption and lactate formation were measured. Exponential EMT6 cells (10/sup 6/ cells/ml) were made hypoxix by continuous gassing in 3% CO/sub 2/ in N/sub 2/. They were then treated with 5mM MISO for various times, then washed and analysed for their rates of anaerobic glycolysis. Glucose and lactate content were determined enzymatically. The rates of both glucose consumption and lactate formation decreased after 30 min hypoxic incubation with MISO. After 90 min, the rates were not measurable even though the cells still excluded Trypan Blue. There was, however, a parallel decrease in plating efficiency. These data suggest that the inhibition of glycolysis is an important mechanism of hypoxic toxicity of MISO. To locate the site of inhibition, studies were initiated to look at glucose transport by following the uptake of /sup 14/-C-3-0-methyl-glucose, a nonmetabolised glucose analog. Results obtained so far indicate that up to 90 min of hypoxic incubation with MISO, there was no change in the kinetics of the uptake of his analog. Therefore, the results showed that in hypoxic cells treated with MISO, the glucose transport system was unaffected. However, there was a rapid decrease in anaerobic glycolysis

N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor1[S

Science.gov (United States)

Zhang, Hao; Jing, Xigang; Shi, Yang; Xu, Hao; Du, Jianhai; Guan, Tongju; Weihrauch, Dorothee; Jones, Deron W.; Wang, Weiling; Gourlay, David; Oldham, Keith T.; Hillery, Cheryl A.; Pritchard, Kirkwood A.

2013-01-01

Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (⩽4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HOCl generation by phorbol myristate acetate (PMA)-stimulated neutrophils and human promyelocytic leukemia (HL-60) cells but not superoxide generation by PMA-stimulated HL-60 cells. KYC inhibits MPO-mediated HOCl formation in BAEC culture and protects BAECs from MPO-induced injury. KYC inhibits MPO-mediated lipid peroxidation of LDL whereas tyrosine (Tyr) and tryptophan (Trp) enhance oxidation. KYC is unique as its isomers do not inhibit MPO activity, or are much less effective. Ultraviolet-visible spectral studies indicate KYC binds to the active site of MPO and reacts with compounds I and II. Docking studies show the Tyr of KYC rests just above the heme of MPO. Interestingly, KYC increases MPO-dependent H2O2 consumption. These data indicate KYC is a novel and specific inhibitor of MPO activity that is nontoxic to endothelial cell cultures. Accordingly, KYC may be useful for treating MPO-mediated vascular disease. PMID:23883583

Sugar-binding sites of the HA1 subcomponent of Clostridium botulinum type C progenitor toxin.

Science.gov (United States)

Nakamura, Toshio; Tonozuka, Takashi; Ide, Azusa; Yuzawa, Takayuki; Oguma, Keiji; Nishikawa, Atsushi

2008-02-22

Clostridium botulinum type C 16S progenitor toxin contains a hemagglutinin (HA) subcomponent, designated HA1, which appears to play an important role in the effective internalization of the toxin in gastrointestinal epithelial cells and in creating a broad specificity for the oligosaccharide structure that corresponds to various targets. In this study, using the recombinant protein fused to glutathione S-transferase, we investigated the binding specificity of the HA1 subcomponent to sugars and estimated the binding sites of HA1 based on X-ray crystallography and soaking experiments using various sugars. N-Acetylneuraminic acid, N-acetylgalactosamine, and galactose effectively inhibited the binding that occurs between glutathione S-transferase-HA1 and mucins, whereas N-acetylglucosamine and glucose did not inhibit it. The crystal structures of HA1 complex with N-acetylneuraminic acid, N-acetylgalactosamine, and galactose were also determined. There are two sugar-binding sites, sites I and II. Site I corresponds to the electron densities noted for all sugars and is located at the C-terminal beta-trefoil domain, while site II corresponds to the electron densities noted only for galactose. An aromatic amino acid residue, Trp176, at site I has a stacking interaction with the hexose ring of the sugars. On the other hand, there is no aromatic residue at site II; thus, the interaction with galactose seems to be poor. The double mutant W176A at site I and D271F at site II has no avidity for N-acetylneuraminic acid but has avidity for galactose. In this report, the binding specificity of botulinum C16S toxin HA1 to various sugars is demonstrated based on its structural features.

Bacteroides gingivalis and Bacteroides intermedius recognize different sites on human fibrinogen

Energy Technology Data Exchange (ETDEWEB)

Lantz, M.S.; Allen, R.D.; Bounelis, P.; Switalski, L.M.; Hook, M. (Univ. of Alabama, Birmingham (USA))

1990-02-01

Bacteroides (Porphyromonas) gingivalis and Bacteroides (Porphyromonas) intermedius have been implicated in the etiology of human periodontal diseases. These organisms are able to bind and degrade human fibrinogen, and these interactions may play a role in the pathogenesis of periodontal disease. In attempts to map the bacterial binding sites along the fibrinogen molecule, we have found that strains of B. gingivalis and B. intermedius, respectively, recognize spatially distant and distinct sites on the fibrinogen molecule. Isolated reduced and alkylated alpha-, beta-, and gamma-fibrinogen chains inhibited binding of 125I-fibrinogen to both Bacteroides species in a concentration-dependent manner. Plasmin fragments D and to some extent fragment E, however, produced a concentration-dependent inhibition of 125I-fibrinogen binding to B. intermedius strains but did not affect binding of 125I-fibrinogen to B. gingivalis strains. Radiolabeled fibrinogen chains and fragments were compared with 125I-fibrinogen with respect to specificity and reversibility of binding to bacteria. According to these criteria, gamma chain most closely resembled the native fibrinogen molecule in behavior toward B. gingivalis strains and fragments D most closely resembled fibrinogen in behavior toward B. intermedius strains. The ability of anti-human fibrinogen immunoglobulin G (IgG) to inhibit binding of 125I-fibrinogen to B. intermedius strains was greatly reduced by absorbing the IgG with fragments D. Absorbing the IgG with fragments D had no effect on the ability of the antibody to inhibit binding of 125I-fibrinogen to B. gingivalis strains. A purified staphylococcal fibrinogen-binding protein blocked binding of 125I-fibrinogen to B. intermedius strains but not to B. gingivalis strains.

Bacteroides gingivalis and Bacteroides intermedius recognize different sites on human fibrinogen

International Nuclear Information System (INIS)

Lantz, M.S.; Allen, R.D.; Bounelis, P.; Switalski, L.M.; Hook, M.

1990-01-01

Bacteroides (Porphyromonas) gingivalis and Bacteroides (Porphyromonas) intermedius have been implicated in the etiology of human periodontal diseases. These organisms are able to bind and degrade human fibrinogen, and these interactions may play a role in the pathogenesis of periodontal disease. In attempts to map the bacterial binding sites along the fibrinogen molecule, we have found that strains of B. gingivalis and B. intermedius, respectively, recognize spatially distant and distinct sites on the fibrinogen molecule. Isolated reduced and alkylated alpha-, beta-, and gamma-fibrinogen chains inhibited binding of 125I-fibrinogen to both Bacteroides species in a concentration-dependent manner. Plasmin fragments D and to some extent fragment E, however, produced a concentration-dependent inhibition of 125I-fibrinogen binding to B. intermedius strains but did not affect binding of 125I-fibrinogen to B. gingivalis strains. Radiolabeled fibrinogen chains and fragments were compared with 125I-fibrinogen with respect to specificity and reversibility of binding to bacteria. According to these criteria, gamma chain most closely resembled the native fibrinogen molecule in behavior toward B. gingivalis strains and fragments D most closely resembled fibrinogen in behavior toward B. intermedius strains. The ability of anti-human fibrinogen immunoglobulin G (IgG) to inhibit binding of 125I-fibrinogen to B. intermedius strains was greatly reduced by absorbing the IgG with fragments D. Absorbing the IgG with fragments D had no effect on the ability of the antibody to inhibit binding of 125I-fibrinogen to B. gingivalis strains. A purified staphylococcal fibrinogen-binding protein blocked binding of 125I-fibrinogen to B. intermedius strains but not to B. gingivalis strains

Peptide inhibition of human cytomegalovirus infection

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Morris Cindy A

2011-02-01

Full Text Available Abstract Background Human cytomegalovirus (HCMV is the most prevalent congenital viral infection in the United States and Europe causing significant morbidity and mortality to both mother and child. HCMV is also an opportunistic pathogen in immunocompromised individuals, including human immunodeficiency virus (HIV- infected patients with AIDS, and solid organ and allogeneic stem cell transplantation recipients. Current treatments for HCMV-associated diseases are insufficient due to the emergence of drug-induced resistance and cytotoxicity, necessitating novel approaches to limit HCMV infection. The aim of this study was to develop therapeutic peptides targeting glycoprotein B (gB, a major glycoprotein of HCMV that is highly conserved across the Herpesviridae family, that specifically inhibit fusion of the viral envelope with the host cell membrane preventing HCMV entry and infection. Results Using the Wimley-White Interfacial Hydrophobicity Scale (WWIHS, several regions within gB were identified that display a high potential to interact with lipid bilayers of cell membranes and hydrophobic surfaces within proteins. The ability of synthetic peptides analogous to WWIHS-positive sequences of HCMV gB to inhibit viral infectivity was evaluated. Human foreskin fibroblasts (HFF were infected with the Towne-GFP strain of HCMV (0.5 MOI, preincubated with peptides at a range of concentrations (78 nm to 100 μM, and GFP-positive cells were visualized 48 hours post-infection by fluorescence microscopy and analyzed quantitatively by flow cytometry. Peptides that inhibited HCMV infection demonstrated different inhibitory concentration curves indicating that each peptide possesses distinct biophysical properties. Peptide 174-200 showed 80% inhibition of viral infection at a concentration of 100 μM, and 51% and 62% inhibition at concentrations of 5 μM and 2.5 μM, respectively. Peptide 233-263 inhibited infection by 97% and 92% at concentrations of 100 �

Local Delivery Is Critical for Monocyte Chemotactic Protein-1 Mediated Site-Specific Murine Aneurysm Healing.

Science.gov (United States)

Hourani, Siham; Motwani, Kartik; Wajima, Daisuke; Fazal, Hanain; Jones, Chad H; Doré, Sylvain; Hosaka, Koji; Hoh, Brian L

2018-01-01

Local delivery of monocyte chemotactic protein-1 (MCP-1/CCL2) via our drug-eluting coil has been shown to promote intrasaccular aneurysm healing via an inflammatory pathway. In this study, we validate the importance of local MCP-1 in murine aneurysm healing. Whether systemic, rather than local, delivery of MCP-1 can direct site-specific aneurysm healing has significant translational implications. If systemic MCP-1 is effective, then MCP-1 could be administered as a pill rather than by endovascular procedure. Furthermore, we confirm that MCP-1 is the primary effector in our MCP-1 eluting coil-mediated murine aneurysm healing model. We compare aneurysm healing with repeated intraperitoneal MCP-1 versus vehicle injection, in animals with control poly(lactic-co-glycolic) acid (PLGA)-coated coils. We demonstrate elimination of the MCP-1-associated tissue-healing response by knockout of MCP-1 or CCR2 (MCP-1 receptor) and by selectively inhibiting MCP-1 or CCR2. Using immunofluorescent probing, we explore the cell populations found in healed aneurysm tissue following each intervention. Systemically administered MCP-1 with PLGA coil control does not produce comparable aneurysm healing, as seen with MCP-1 eluting coils. MCP-1-directed aneurysm healing is eliminated by selective inhibition of MCP-1 or CCR2 and in MCP-1-deficient or CCR2-deficient mice. No difference was detected in M2 macrophage and myofibroblast/smooth muscle cell staining with systemic MCP-1 versus vehicle in aneurysm wall, but a significant increase in these cell types was observed with MCP-1 eluting coil implant and attenuated by MCP-1/CCR2 blockade or deficiency. We show that systemic MCP-1 concurrent with PLGA-coated platinum coil implant is not sufficient to produce site-specific aneurysm healing. MCP-1 is a critical, not merely complementary, actor in the aneurysm healing pathway.

Novel package for inhibition of aluminium corrosion in alkaline solutions

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Abdel-Gaber, A.M., E-mail: ashrafmoustafa@yahoo.com [Chemistry Department, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt); Khamis, E.; Abo-Eldahab, H.; Adeel, Sh. [Chemistry Department, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt)

2010-11-01

Inhibition of aluminium corrosion in 2 M sodium hydroxide solution by a package composed of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) and lupine seed extract has been investigated employing different electrochemical techniques and chemical gasometry measurements. Potentiodynamic polarization curve measurements showed that lupine seed extract controls both the anodic dissolution of aluminium and the hydrogen gas evolved at the cathodic sites of aluminium surface. Nyquist plots showed two capacitive semicircles in the high and low frequency regions separated by an inductive loop at intermediate frequencies. The inductive loop may be explained by the occurrence of adsorbed intermediates on the surface. A proposed equivalent circuit was used to analyse the impedance spectra for aluminium in NaOH solutions. The corrosion inhibition data have been analysed using different isotherms. The results showed excellent agreement between the kinetic-thermodynamic model and Flory-Huggins isotherm. Gasometry measurements showed that the Inhibitive effect of the surfactant increases at a composition around its critical micelle concentration (cmc). The presence of both the surfactant and lupine seed extract did not indicate synergistic action between them. The mode of adsorption of the surfactant molecules corresponding to their structure is also discussed.

Novel package for inhibition of aluminium corrosion in alkaline solutions

International Nuclear Information System (INIS)

Abdel-Gaber, A.M.; Khamis, E.; Abo-Eldahab, H.; Adeel, Sh.

2010-01-01

Inhibition of aluminium corrosion in 2 M sodium hydroxide solution by a package composed of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) and lupine seed extract has been investigated employing different electrochemical techniques and chemical gasometry measurements. Potentiodynamic polarization curve measurements showed that lupine seed extract controls both the anodic dissolution of aluminium and the hydrogen gas evolved at the cathodic sites of aluminium surface. Nyquist plots showed two capacitive semicircles in the high and low frequency regions separated by an inductive loop at intermediate frequencies. The inductive loop may be explained by the occurrence of adsorbed intermediates on the surface. A proposed equivalent circuit was used to analyse the impedance spectra for aluminium in NaOH solutions. The corrosion inhibition data have been analysed using different isotherms. The results showed excellent agreement between the kinetic-thermodynamic model and Flory-Huggins isotherm. Gasometry measurements showed that the Inhibitive effect of the surfactant increases at a composition around its critical micelle concentration (cmc). The presence of both the surfactant and lupine seed extract did not indicate synergistic action between them. The mode of adsorption of the surfactant molecules corresponding to their structure is also discussed.

Protein thiophosphorylation associated with secretory inhibition in permeabilized chromaffin cells

International Nuclear Information System (INIS)

Brooks, J.C.; Brooks, M.

1985-01-01

Permeabilized cells treated with the adenosine triphosphate analog, ( 35 S)adenosine-5'-0-3(3-thiotriphosphate) ((γ- 35 S)ATP), showed thiophosphorylation of a small number of cellular proteins. A 54 kilodalton (kDa) protein was heavily thiophosphorylated in unstimulated control cells and a 43 kilodalton protein was more heavily thiophosphorylated in calcium stimulated cells. Intact cells incorporated 35 S into a series of higher molecular weight proteins. Stimulation of prelabelled, permeabilized cells resulted in a loss of 35 S from the cells over a 20 min period. Treatment of permeabilized cells with ATPγS inhibited secretion and 35 S incorporation into the cells. Pretreatment with ATPγS resulted in subsequent inhibition of both secretion and the ability of the cells to incorporate 35 S from (γ- 35 S)ATP. These results indicate that the sites normally available for phosphorylation were inactivated by thiophosphorylation and were unavailable to participate in the secretory process. The inhibition of secretion associated with thiophosphorylation of these proteins suggests that they may play a role in the control of secretion by chromaffin cells. 15 references, 1 figure, 3 tables

Allosteric Inhibition of Macrophage Migration Inhibitory Factor Revealed by Ibudilast

Energy Technology Data Exchange (ETDEWEB)

Cho, Y.; Crichlow, G; Vermeire, J; Leng, L; Du, X; Hodsdon, M; Bucala, R; Cappello, M; Gross, M; et al.

2010-01-01

AV411 (ibudilast; 3-isobutyryl-2-isopropylpyrazolo-[1,5-a]pyridine) is an antiinflammatory drug that was initially developed for the treatment of bronchial asthma but which also has been used for cerebrovascular and ocular indications. It is a nonselective inhibitor of various phosphodiesterases (PDEs) and has varied antiinflammatory activity. More recently, AV411 has been studied as a possible therapeutic for the treatment of neuropathic pain and opioid withdrawal through its actions on glial cells. As described herein, the PDE inhibitor AV411 and its PDE-inhibition-compromised analog AV1013 inhibit the catalytic and chemotactic functions of the proinflammatory protein, macrophage migration inhibitory factor (MIF). Enzymatic analysis indicates that these compounds are noncompetitive inhibitors of the p-hydroxyphenylpyruvate (HPP) tautomerase activity of MIF and an allosteric binding site of AV411 and AV1013 is detected by NMR. The allosteric inhibition mechanism is further elucidated by X-ray crystallography based on the MIF/AV1013 binary and MIF/AV1013/HPP ternary complexes. In addition, our antibody experiments directed against MIF receptors indicate that CXCR2 is the major receptor for MIF-mediated chemotaxis of peripheral blood mononuclear cells.

Structural basis for the mechanism of inhibition of uridine phosphorylase from Salmonella typhimurium

Energy Technology Data Exchange (ETDEWEB)

Lashkov, A. A.; Zhukhlistova, N. E.; Sotnichenko, S. E.; Gabdulkhakov, A. G.; Mikhailov, A. M., E-mail: amm@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2010-01-15

The three-dimensional structures of three complexes of Salmonella typhimurium uridine phosphorylase with the inhibitor 2,2'-anhydrouridine, the substrate PO{sub 4}, and with both the inhibitor 2,2'-anhydrouridine and the substrate PO{sub 4} (a binary complex) were studied in detail by X-ray diffraction. The structures of the complexes were refined at 2.38, 1.5, and 1.75 A resolution, respectively. Changes in the three-dimensional structure of the subunits in different crystal structures are considered depending on the presence or absence of the inhibitor molecule and (or) the phosphate ion in the active site of the enzyme. The presence of the phosphate ion in the phosphate-binding site was found to substantially change the orientations of the side chains of the amino-acid residues Arg30, Arg91, and Arg48 coordinated to this ion. A comparison showed that the highly flexible loop L9 is unstable. The atomic coordinates of the refined structures of the complexes and the corresponding structure factors were deposited in the Protein Data Bank (their PDB ID codes are 3DD0 and 3C74). The experimental data on the spatial reorganization of the active site caused by changes in its functional state from the unligated to the completely inhibited state suggest the structural basis for the mechanism of inhibition of Salmonella typhimurium uridine phosphorylase.

Conserved nucleation sites reinforce the significance of Phi value analysis in protein-folding studies.

Science.gov (United States)

Gianni, Stefano; Jemth, Per

2014-07-01

The only experimental strategy to address the structure of folding transition states, the so-called Φ value analysis, relies on the synergy between site directed mutagenesis and the measurement of reaction kinetics. Despite its importance, the Φ value analysis has been often criticized and its power to pinpoint structural information has been questioned. In this hypothesis, we demonstrate that comparing the Φ values between proteins not only allows highlighting the robustness of folding pathways but also provides per se a strong validation of the method. © 2014 International Union of Biochemistry and Molecular Biology.

Identification of the quinolinedione inhibitor binding site in Cdc25 phosphatase B through docking and molecular dynamics simulations

Science.gov (United States)

Ge, Yushu; van der Kamp, Marc; Malaisree, Maturos; Liu, Dan; Liu, Yi; Mulholland, Adrian J.

2017-11-01

Cdc25 phosphatase B, a potential target for cancer therapy, is inhibited by a series of quinones. The binding site and mode of quinone inhibitors to Cdc25B remains unclear, whereas this information is important for structure-based drug design. We investigated the potential binding site of NSC663284 [DA3003-1 or 6-chloro-7-(2-morpholin-4-yl-ethylamino)-quinoline-5, 8-dione] through docking and molecular dynamics simulations. Of the two main binding sites suggested by docking, the molecular dynamics simulations only support one site for stable binding of the inhibitor. Binding sites in and near the Cdc25B catalytic site that have been suggested previously do not lead to stable binding in 50 ns molecular dynamics (MD) simulations. In contrast, a shallow pocket between the C-terminal helix and the catalytic site provides a favourable binding site that shows high stability. Two similar binding modes featuring protein-inhibitor interactions involving Tyr428, Arg482, Thr547 and Ser549 are identified by clustering analysis of all stable MD trajectories. The relatively flexible C-terminal region of Cdc25B contributes to inhibitor binding. The binding mode of NSC663284, identified through MD simulation, likely prevents the binding of protein substrates to Cdc25B. The present results provide useful information for the design of quinone inhibitors and their mechanism of inhibition.

Identification of the quinolinedione inhibitor binding site in Cdc25 phosphatase B through docking and molecular dynamics simulations.

Science.gov (United States)

Ge, Yushu; van der Kamp, Marc; Malaisree, Maturos; Liu, Dan; Liu, Yi; Mulholland, Adrian J

2017-11-01

Cdc25 phosphatase B, a potential target for cancer therapy, is inhibited by a series of quinones. The binding site and mode of quinone inhibitors to Cdc25B remains unclear, whereas this information is important for structure-based drug design. We investigated the potential binding site of NSC663284 [DA3003-1 or 6-chloro-7-(2-morpholin-4-yl-ethylamino)-quinoline-5, 8-dione] through docking and molecular dynamics simulations. Of the two main binding sites suggested by docking, the molecular dynamics simulations only support one site for stable binding of the inhibitor. Binding sites in and near the Cdc25B catalytic site that have been suggested previously do not lead to stable binding in 50 ns molecular dynamics (MD) simulations. In contrast, a shallow pocket between the C-terminal helix and the catalytic site provides a favourable binding site that shows high stability. Two similar binding modes featuring protein-inhibitor interactions involving Tyr428, Arg482, Thr547 and Ser549 are identified by clustering analysis of all stable MD trajectories. The relatively flexible C-terminal region of Cdc25B contributes to inhibitor binding. The binding mode of NSC663284, identified through MD simulation, likely prevents the binding of protein substrates to Cdc25B. The present results provide useful information for the design of quinone inhibitors and their mechanism of inhibition.

Systemic EP4 Inhibition Increases Adhesion Formation in a Murine Model of Flexor Tendon Repair.

Directory of Open Access Journals (Sweden)

Michael B Geary

Full Text Available Flexor tendon injuries are a common clinical problem, and repairs are frequently complicated by post-operative adhesions forming between the tendon and surrounding soft tissue. Prostaglandin E2 and the EP4 receptor have been implicated in this process following tendon injury; thus, we hypothesized that inhibiting EP4 after tendon injury would attenuate adhesion formation. A model of flexor tendon laceration and repair was utilized in C57BL/6J female mice to evaluate the effects of EP4 inhibition on adhesion formation and matrix deposition during flexor tendon repair. Systemic EP4 antagonist or vehicle control was given by intraperitoneal injection during the late proliferative phase of healing, and outcomes were analyzed for range of motion, biomechanics, histology, and genetic changes. Repairs treated with an EP4 antagonist demonstrated significant decreases in range of motion with increased resistance to gliding within the first three weeks after injury, suggesting greater adhesion formation. Histologic analysis of the repair site revealed a more robust granulation zone in the EP4 antagonist treated repairs, with early polarization for type III collagen by picrosirius red staining, findings consistent with functional outcomes. RT-PCR analysis demonstrated accelerated peaks in F4/80 and type III collagen (Col3a1 expression in the antagonist group, along with decreases in type I collagen (Col1a1. Mmp9 expression was significantly increased after discontinuing the antagonist, consistent with its role in mediating adhesion formation. Mmp2, which contributes to repair site remodeling, increases steadily between 10 and 28 days post-repair in the EP4 antagonist group, consistent with the increased matrix and granulation zones requiring remodeling in these repairs. These findings suggest that systemic EP4 antagonism leads to increased adhesion formation and matrix deposition during flexor tendon healing. Counter to our hypothesis that EP4 antagonism

Knockdown of stat3 expression by RNAi inhibits in vitro growth of human ovarian cancer

International Nuclear Information System (INIS)

Zhao, Shu-Hua; Zhao, Fan; Zheng, Jing-Ying; Gao, Li-Fang; Zhao, Xue-Jian; Cui, Man-Hua

2011-01-01

The aim of the study was to investigate the suppressive effects of pSilencer2.1-U6-siRNA-stat3 recombinant plasmids on the growth of ovarian cancer in vitro. Three pairs of DNA template (stat3-1, stat3-2, stat3-3) specific for different target sites on stat3 mRNA were synthesized to reconstruct pSilencer2.1-U6-siRNA-stat3s, which were transfected into SKOV3 cells. The expressions of STAT3, BcL-2, cyclin D1 and C-myc in these cells were detected by Western blot and Northern blot. The cell cycle and the growth were determined by flow cytometry (FCM) and MTT assay, respectively. Cell apoptosis was determined by TUNEL staining. Of the three siRNAs, only siRNA targeting stat3-3 markedly suppressed the protein expression of stat3 in SKOV3 cells; MTT assay and FCM showed that transfection of stat3-3 siRNA could significantly suppress the growth of SKOV3 cells and arrest the cell cycle in vitro. TUNEL staining also showed massive apoptosis in SKOV3 cells transfected with stat3-3 siRNA. pSilencer2.1-U6-siRNA-stat3-3 can significantly inhibit the STAT3 expression in human ovarian cancer cells resulting in the inhibition of the cancer growth and the increase of apoptosis of cancer cells

Andrographolide suppresses high glucose-induced fibronectin expression in mesangial cells via inhibiting the AP-1 pathway.

Science.gov (United States)

Lan, Tian; Wu, Teng; Gou, Hongju; Zhang, Qianqian; Li, Jiangchao; Qi, Cuiling; He, Xiaodong; Wu, Pingxiang; Wang, Lijing

2013-11-01

Mesangial cells (MCs) proliferation and accumulation of glomerular matrix proteins such as fibronectin (FN) are the early features of diabetic nephropathy, with MCs known to upregulate matrix protein synthesis in response to high glucose. Recently, it has been found that andrographolide has renoprotective effects on diabetic nephropathy. However, the molecular mechanism underlying these effects remains unclear. Cell viability and proliferation was evaluated by MTT. FN expression was examined by immunofluorescence and immunoblotting. Activator protein-1 (AP-1) activation was assessed by immunoblotting, luciferase reporter and electrophoretic mobility shift assays. Andrographolide significantly decreased high glucose-induced cell proliferation and FN expression in MCs. Exposure of MCs to high glucose markedly stimulated the expression of phosphorylated c-jun, whereas the stimulation was inhibited by andrographolide. Plasmid pAP-1-Luc luciferase reporter assay showed that andrographolide blocked high glucose-induced AP-1 transcriptional activity. EMSA assay demonstrated that increased AP-1 binding to an AP-1 binding site at -1,029 in the FN gene promoter upon high glucose stimulation, and the binding were disrupted by andrographolide treatment. These data indicate that andrographolide suppresses high glucose-induced FN expression by inhibiting AP-1-mediated pathway. © 2013 Wiley Periodicals, Inc.

Calcium phosphate coating containing silver shows high antibacterial activity and low cytotoxicity and inhibits bacterial adhesion

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Ando, Yoshiki, E-mail: andoy@jmmc.jp [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Miyamoto, Hiroshi [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Noda, Iwao; Sakurai, Nobuko [Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Akiyama, Tomonori [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Yonekura, Yutaka; Shimazaki, Takafumi; Miyazaki, Masaki; Mawatari, Masaaki; Hotokebuchi, Takao [Department of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan)

2010-01-01

Surgical site infection is one of the serious complications of orthopedic implants. In order to reduce the incidence of implant-associated infections, we developed a novel coating technology of calcium phosphate (CP) containing silver (Ag), designated Ag-CP coating, using a thermal spraying technique. In this study, we evaluated the antibacterial efficacy and biological safety of this coating. In vitro antibacterial activity tests showed that the growths of Escherichia coli, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) are completely suppressed on Ag-CP coating. In vitro bacterial adherence tests revealed that the number of adherent bacteria on the surface of this coating is significantly less (p < 0.02) than that on the surface of the CP coating. Moreover, the Ag-CP coating completely inhibits MRSA adhesion [<10 colony-forming units (CFU)] when 10{sup 2} CFU MRSA is inoculated. On the other hand, V79 Chinese hamster lung cells were found to grow on the Ag-CP coating as well as on the CP coating in a cytotoxicity test. These results indicate that the Ag-CP coating on the surface of orthopedic implants exhibits antibacterial activity and inhibits bacterial adhesion without cytotoxicity.

New Cinchona Oximes Evaluated as Reactivators of Acetylcholinesterase and Butyrylcholinesterase Inhibited by Organophosphorus Compounds

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Maja Katalinić

2017-07-01

Full Text Available For the last six decades, researchers have been focused on finding efficient reactivators of organophosphorus compound (OP-inhibited acetylcholinesterase (AChE and butyrylcholinesterase (BChE. In this study, we have focused our research on a new oxime scaffold based on the Cinchona structure since it was proven to fit the cholinesterases active site and reversibly inhibit their activity. Three Cinchona oximes (C1, C2, and C3, derivatives of the 9-oxocinchonidine, were synthesized and investigated in reactivation of various OP-inhibited AChE and BChE. As the results showed, the tested oximes were more efficient in the reactivation of BChE and they reactivated enzyme activity to up to 70% with reactivation rates similar to known pyridinium oximes used as antidotes in medical practice today. Furthermore, the oximes showed selectivity towards binding to the BChE active site and the determined enzyme-oxime dissociation constants supported work on the future development of inhibitors in other targeted studies (e.g., in treatment of neurodegenerative disease. Also, we monitored the cytotoxic effect of Cinchona oximes on two cell lines Hep G2 and SH-SY5Y to determine the possible limits for in vivo application. The cytotoxicity results support future studies of these compounds as long as their biological activity is targeted in the lower micromolar range.