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Sample records for beta peptide abeta

  1. Identification of distinct physiochemical properties of toxic prefibrillar species formed by A{beta} peptide variants

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    Goeransson, Anna-Lena, E-mail: anngo@ifm.liu.se [Division of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linkoeping University (Sweden); Nilsson, K. Peter R., E-mail: petni@ifm.liu.se [Division of Organic Chemistry, Department of Physics, Chemistry and Biology, Linkoeping University (Sweden); Kagedal, Katarina, E-mail: katarina.kagedal@liu.se [Department of Clinical and Experimental Medicine, Linkoeping University (Sweden); Brorsson, Ann-Christin, E-mail: anki@ifm.liu.se [Division of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linkoeping University (Sweden)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer Identification of toxic prefibrillar A{beta} species. Black-Right-Pointing-Pointer Fluorescence measurements using a combined set of fluorophores. Black-Right-Pointing-Pointer Morphology studies using transmission electron microscopy. -- Abstract: The formation of amyloid-{beta} peptide (A{beta}) aggregates at an early stage during the self-assembly process is an important factor in the development of Alzheimer's disease. The toxic effect is believed to be exerted by prefibrillar species of A{beta}. It is therefore important to identify which prefibrillar species are toxic and characterize their distinct properties. In the present study, we investigated the in vitro aggregation behavior of A{beta}-derived peptides possessing different levels of neurotoxic activity, using fluorescence spectroscopy in combination with transmission electron microscopy. The toxicity of various A{beta} aggregates was assessed by using cultures of human neuroblastoma cells. Through combined use of the fluorescence probe 8-anilino-1-napthalenesulfonate (ANS) and the novel luminescent probe pentamer formyl thiophene acetic acid (p-FTAA), we were able to identify those A{beta} peptide-derived prefibrillar species which exhibited cellular toxicity. In particular, species, which formed early during the aggregation process and showed strong p-FTAA and ANS fluorescence, were the species that possessed toxic activities. Moreover, by manipulating the aggregation conditions, it was possible to change the capacity of the A{beta} peptide to form nontoxic versus toxic species.

  2. Stability of the transthyretin molecule as a key factor in the interaction with a-beta peptide--relevance in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Carlos A Ribeiro

    Full Text Available Transthyretin (TTR protects against A-Beta toxicity by binding the peptide thus inhibiting its aggregation. Previous work showed different TTR mutations interact differently with A-Beta, with increasing affinities correlating with decreasing amyloidogenecity of the TTR mutant; this did not impact on the levels of inhibition of A-Beta aggregation, as assessed by transmission electron microscopy. Our work aimed at probing differences in binding to A-Beta by WT, T119M and L55P TTR using quantitative assays, and at identifying factors affecting this interaction. We addressed the impact of such factors in TTR ability to degrade A-Beta. Using a dot blot approach with the anti-oligomeric antibody A11, we showed that A-Beta formed oligomers transiently, indicating aggregation and fibril formation, whereas in the presence of WT and T119M TTR the oligomers persisted longer, indicative that these variants avoided further aggregation into fibrils. In contrast, L55PTTR was not able to inhibit oligomerization or to prevent evolution to aggregates and fibrils. Furthermore, apoptosis assessment showed WT and T119M TTR were able to protect against A-Beta toxicity. Because the amyloidogenic potential of TTR is inversely correlated with its stability, the use of drugs able to stabilize TTR tetrameric fold could result in increased TTR/A-Beta binding. Here we showed that iododiflunisal, 3-dinitrophenol, resveratrol, [2-(3,5-dichlorophenylamino] (DCPA and [4-(3,5-difluorophenyl] (DFPB were able to increase TTR binding to A-Beta; however only DCPA and DFPB improved TTR proteolytic activity. Thyroxine, a TTR ligand, did not influence TTR/A-Beta interaction and A-Beta degradation by TTR, whereas RBP, another TTR ligand, not only obstructed the interaction but also inhibited TTR proteolytic activity. Our results showed differences between WT and T119M TTR, and L55PTTR mutant regarding their interaction with A-Beta and prompt the stability of TTR as a key factor in this

  3. Oligomerization and toxicity of A{beta} fusion proteins

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    Caine, Joanne M., E-mail: Jo.Caine@csiro.au [CSIRO Materials Science and Engineering and the Preventive Health Flagship, Parkville, Victoria (Australia); Bharadwaj, Prashant R. [CSIRO Materials Science and Engineering and the Preventive Health Flagship, Parkville, Victoria (Australia); Centre for Excellence for Alzheimer' s Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Western Australia (Australia); Sankovich, Sonia E. [CSIRO Materials Science and Engineering and the Preventive Health Flagship, Parkville, Victoria (Australia); Ciccotosto, Giuseppe D. [The Department of Pathology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010 (Australia); Streltsov, Victor A.; Varghese, Jose [CSIRO Materials Science and Engineering and the Preventive Health Flagship, Parkville, Victoria (Australia)

    2011-06-10

    Highlights: {yields} We expressed amyloid-{beta} (A{beta}) peptide as a soluble maltose binding protein fusion (MBP-A{beta}42 and MBP-A{beta}16). {yields} The full length A{beta} peptide fusion, MBP-A{beta}42, forms oligomeric species as determined by SDS-PAGE gels, gel filtration and DLS. {yields} The MBP-A{beta}42, but not MBP-A{beta}16 or MBP alone, is toxic to both yeast and mammalian cells as determined by toxicity assays. -- Abstract: This study has found that the Maltose binding protein A{beta}42 fusion protein (MBP-A{beta}42) forms soluble oligomers while the shorter MBP-A{beta}16 fusion and control MBP did not. MBP-A{beta}42, but neither MBP-A{beta}16 nor control MBP, was toxic in a dose-dependent manner in both yeast and primary cortical neuronal cells. This study demonstrates the potential utility of MBP-A{beta}42 as a reagent for drug screening assays in yeast and neuronal cell cultures and as a candidate for further A{beta}42 characterization.

  4. The tissue plasminogen activator-plasminogen proteolytic cascade accelerates amyloid-beta (Abeta) degradation and inhibits Abeta-induced neurodegeneration.

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    Melchor, Jerry P; Pawlak, Robert; Strickland, Sidney

    2003-10-01

    Accumulation of the amyloid-beta (Abeta) peptide depends on both its generation and clearance. To better define clearance pathways, we have evaluated the role of the tissue plasminogen activator (tPA)-plasmin system in Abeta degradation in vivo. In two different mouse models of Alzheimer's disease, chronically elevated Abeta peptide in the brain correlates with the upregulation of plasminogen activator inhibitor-1 (PAI-1) and inhibition of the tPA-plasmin system. In addition, Abeta injected into the hippocampus of mice lacking either tPA or plasminogen persists, inducing PAI-1 expression and causing activation of microglial cells and neuronal damage. Conversely, Abeta injected into wild-type mice is rapidly cleared and does not cause neuronal degeneration. Thus, the tPA-plasmin proteolytic cascade aids in the clearance of Abeta, and reduced activity of this system may contribute to the progression of Alzheimer's disease.

  5. Ellagic acid promotes A{beta}42 fibrillization and inhibits A{beta}42-induced neurotoxicity

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    Feng, Ying [Department of Histology and Embryology, College of Basic Medical Science, China Medical University, Shenyang 110001 (China); Tsinghua University School of Medicine, Haidian District, Beijing 100084 (China); Yang, Shi-gao; Du, Xue-ting; Zhang, Xi; Sun, Xiao-xia; Zhao, Min [Tsinghua University School of Medicine, Haidian District, Beijing 100084 (China); Sun, Gui-yuan, E-mail: sungy2004@sohu.com [Department of Histology and Embryology, College of Basic Medical Science, China Medical University, Shenyang 110001 (China); Liu, Rui-tian, E-mail: rtliu@tsinghua.edu.cn [Tsinghua University School of Medicine, Haidian District, Beijing 100084 (China)

    2009-12-25

    Smaller, soluble oligomers of {beta}-amyloid (A{beta}) play a critical role in the pathogenesis of Alzheimer's disease (AD). Selective inhibition of A{beta} oligomer formation provides an optimum target for AD therapy. Some polyphenols have potent anti-amyloidogenic activities and protect against A{beta} neurotoxicity. Here, we tested the effects of ellagic acid (EA), a polyphenolic compound, on A{beta}42 aggregation and neurotoxicity in vitro. EA promoted A{beta} fibril formation and significant oligomer loss, contrary to previous results that polyphenols inhibited A{beta} aggregation. The results of transmission electron microscopy (TEM) and Western blot displayed more fibrils in A{beta}42 samples co-incubated with EA in earlier phases of aggregation. Consistent with the hypothesis that plaque formation may represent a protective mechanism in which the body sequesters toxic A{beta} aggregates to render them harmless, our MTT results showed that EA could significantly reduce A{beta}42-induced neurotoxicity toward SH-SY5Y cells. Taken together, our results suggest that EA, an active ingredient in many fruits and nuts, may have therapeutic potential in AD.

  6. Crystallization and preliminary X-ray diffraction analysis of the Fab fragment of WO2, an antibody specific for the A[beta] peptides associated with Alzheimer's disease

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    Wun, Kwok S.; Miles, Luke A.; Crespi, Gabriela A.N.; Wycherley, Kaye; Ascher, David B.; Barnham, Kevin J.; Cappai, Roberto; Beyreuther, Konrad; Masters, Colin L.; Parker, Michael W.; McKinstry, William J. (SVIMR-A); (HeidelbergU); (WEHI); (Melbourne)

    2008-05-28

    The murine monoclonal antibody WO2 specifically binds the N-terminal region of the amyloid {beta} peptide (A{beta}) associated with Alzheimer's disease. This region of A{beta} has been shown to be the immunodominant B-cell epitope of the peptide and hence is considered to be a basis for the development of immunotherapeutic strategies against this prevalent cause of dementia. Structural studies have been undertaken in order to characterize the molecular basis for antibody recognition of this important epitope. Here, details of the crystallization and X-ray analysis of the Fab fragment of the unliganded WO2 antibody in two crystal forms and of the complexes that it forms with the truncated Az{beta} peptides A{beta}{sub 1-16} and A{beta}{sub 1-28} are presented. These crystals were all obtained using the hanging-drop vapour-diffusion method at 295 K. Crystals of WO2 Fab were grown in polyethylene glycol solutions containing ZnSO{sub 4}; they belonged to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1} and diffracted to 1.6 {angstrom} resolution. The complexes of WO2 Fab with either A{beta}{sub 1-16} or A{beta}{sub 1-28} were cocrystallized from polyethylene glycol solutions. These two complex crystals grew in the same space group, P2{sub 1}2{sub 1}2{sub 1}, and diffracted to 1.6 {angstrom} resolution. A second crystal form of WO2 Fab was grown in the presence of the sparingly soluble A{beta}{sub 1-42} in PEG 550 MME. This second form belonged to space group P2{sub 1} and diffracted to 1.9 {angstrom} resolution.

  7. CD45RB is a novel molecular therapeutic target to inhibit Abeta peptide-induced microglial MAPK activation.

    Directory of Open Access Journals (Sweden)

    Yuyan Zhu

    Full Text Available BACKGROUND: Microglial activation, characterized by p38 MAPK or p44/42 MAPK pathway signal transduction, occurs in Alzheimer's disease (AD. Our previous studies demonstrated CD45, a membrane-bound protein tyrosine phosphatase (PTP, opposed beta-amyloid (Abeta peptide-induced microglial activation via inhibition of p44/42 MAPK. Additionally we have shown agonism of the RB isoform of CD45 (CD45RB abrogates lipopolysaccharide (LPS-induced microglial activation. METHODOLOGY AND RESULTS: In this study, CD45RB modulation of Abeta peptide or LPS-activated primary cultured microglial cells was further investigated. Microglial cells were co-treated with "aged" FITC-Abeta(1-42 and multiple CD45 isoform agonist antibodies. Data revealed cross-linking of CD45, particularly the CD45RB isoform, enhances microglial phagocytosis of Abeta(1-42 peptide and inhibits LPS-induced activation of p44/42 and p38 pathways. Co-treatment of microglial cells with agonist CD45 antibodies results in significant inhibition of LPS-induced microglial TNF-alpha and IL-6 release through p44/42 and/or p38 pathways. Moreover, inhibition of either of these pathways augmented CD45RB cross-linking induced microglial phagocytosis of Abeta(1-42 peptide. To investigate the mechanism(s involved, microglial cells were co-treated with a PTP inhibitor (potassium bisperoxo [1,10-phenanthroline oxovanadate; Phen] and Abeta(1-42 peptides. Data showed synergistic induction of microglial activation as evidenced by TNF-alpha and IL-6 release; both of which are demonstrated to be dependent on increased p44/42 and/or p38 activation. Finally, it was observed that cross-linking of CD45RB in the presence of Abeta(1-42 peptide, inhibits co-localization of microglial MHC class II and Abeta peptide; suggesting CD45 activation inhibits the antigen presenting phenotype of microglial cells. CONCLUSION: In summary, p38 MAPK is another novel signaling pathway, besides p44/42, in which CD45RB cross

  8. Cu(II) coordination structure determinants of the fibrillization switch in Abeta peptides

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    Hernandez-Guzman, Jessica; Sun, Li; Mehta, Anil; Lynn, David; Warncke, Kurt

    2010-03-01

    Alzheimer's Disease (AD) is associated with the aggregation and fibrillization of the beta-amyloid protein (Abeta). The coordination of Cu(II) by peptide histidine imidazole sidechains is proposed to play an important role in determining the fibrillization ``switch'' [1]. We have developed techniques of powder X-band electron spin echo envelope modulation (ESEEM) spectroscopy to determine the 3D molecular structure of the Cu(II)-histidine imidazole coordination in cryotrapped soluble and fibrillar forms of Abeta peptides, in order to gain insight into the factors that govern fibrillization. We use hybrid optimization-based OPTESIM [2] simulation of the double quantum harmonic feature to determine the mutual orientation of the imidazole rings in Cu(II)--bis-imidazole complexes and in Abeta(13-21) peptides. The Cu(II) coordination mode and assembly constraints in fibrils are revealed. [1] Dong , J., et al., Proc. Natl. Acad. Sci., 2007, 104, 13313. [2] Sun, L., et al., J. Magn. Reson. 2009, 200, 21.

  9. A neural cell adhesion molecule-derived peptide reduces neuropathological signs and cognitive impairment induced by Abeta25-35

    DEFF Research Database (Denmark)

    Klementiev, B; Novikova, T; Novitskaya, V;

    2007-01-01

    By means of i.c.v. administration of preaggregated oligomeric beta-amyloid (Abeta)25-35 peptide it was possible in rats to generate neuropathological signs related to those of early stages of Alzheimer's disease (AD). Abeta25-35-administration induced the deposition of endogenously produced amyloid...... protein. Furthermore, quantitative immunohistochemistry demonstrated time-related statistically significant increases in amyloid immunoreactivity, tau phosphorylation, microglial activation, and astrocytosis, and stereological investigations demonstrated statistically significant increased neuronal cell...... by intranasal and s.c. administration of the peptide. Furthermore, FGL-treatment was shown to inhibit the activity of GSK3beta, a kinase implicated in signaling regulating cell survival, tau phosphorylation and the processing of the amyloid precursor protein (APP). Thus, the peptide induced a statistically...

  10. MMPBSA decomposition of the binding energy throughout a molecular dynamics simulation of amyloid-beta (Abeta(10-35)) aggregation.

    Science.gov (United States)

    Campanera, Josep M; Pouplana, Ramon

    2010-04-15

    Recent experiments with amyloid-beta (Abeta) peptides indicate that the formation of toxic oligomers may be an important contribution to the onset of Alzheimer's disease. The toxicity of Abeta oligomers depend on their structure, which is governed by assembly dynamics. However, a detailed knowledge of the structure of at the atomic level has not been achieved yet due to limitations of current experimental techniques. In this study, replica exchange molecular dynamics simulations are used to identify the expected diversity of dimer conformations of Abeta(10-35) monomers. The most representative dimer conformation has been used to track the dimer formation process between both monomers. The process has been characterized by means of the evolution of the decomposition of the binding free energy, which provides an energetic profile of the interaction. Dimers undergo a process of reorganization driven basically by inter-chain hydrophobic and hydrophilic interactions and also solvation/desolvation processes.

  11. The hydrophobic environment of Met35 of Alzheimer's Abeta(1-42) is important for the neurotoxic and oxidative properties of the peptide.

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    Kanski, Jaroslaw; Aksenova, Marina; Butterfield, D Allan

    2002-05-01

    In Alzheimer's disease (AD) brain increased lipid peroxidation is found. Amyloid beta-peptide [Abeta(1-42)] induces oxidative stress (including lipid peroxidation) and neurotoxicity, and the single methionine residue (Met35) is important for these properties. In the current study, we tested the hypothesis that removal of Met35 from lipid bilayer would abrogate the oxidative stress and neurotoxic properties of Abeta(1-42), i.e. we tested the hypothesis and found that lipid peroxidation initiated by oxidation of the Met35 is an early event in Abeta(1-42) neurotoxicity. Substitution of negatively charged aspartic acid for glycine residue 37 is not predicted to bring the Met35 residue out of the hydrophobic lipid bilayer. In this study, we showed that G37D substitution in Abeta(1-42) completely abolishes neurotoxic and oxidative processes associated with the parent peptide. This is demonstrated by the lack of cell toxicity and protein oxidation in contrast to the treatment with native Abeta(1-42). Additionally, the G37D peptide does not display the aggregation properties that are associated with native Abeta as seen in the thioflavin T (ThT) assay and fibril morphology. The results presented in this work are thus consistent with the notion of the importance of methionine 35 of Abeta(1-42) in the lipid-initiated oxidative cascade and subsequent neurotoxicity in AD brain.

  12. Overcoming synthetic Abeta peptide aging: a new approach to an age-old problem.

    Science.gov (United States)

    Manzoni, Claudia; Colombo, Laura; Messa, Massimo; Cagnotto, Alfredo; Cantù, Laura; Del Favero, Elena; Salmona, Mario

    2009-01-01

    Investigations of amyloidogenic diseases use synthetic peptides for cell-free and in vitro studies. However, amyloidogenic peptides often show intrinsic variability that markedly affects the reproducibility of experiments. Proof of physicochemical and biological variability with different batches of amyloidogenic peptides have been reported in literature. Here, we show that differences can be observed even within the same batch of Abeta1-42 peptide after storing lyophilised samples at -20 degrees C. This change (referred to as 'peptide aging') was reproduced with Abeta1-40 peptide samples by using a series of lyophilisation cycles, showing that lyophilisation, rather than preserving the physicochemical and biological features of Abeta peptides, introduces wide variability. To counteract synthetic peptide aging, we set up a procedure involving the sequential use of trifluoroacetic acid, formic acid and sodium hydroxide solutions that disaggregate preformed seeds and enriched Abeta peptide solutions into monomers and low-molecular-weight oligomers. This procedure enabled us to obtain reproducible physicochemical and biological features of Abeta peptides, irrespective of their age. PMID:20536398

  13. Influence of hydrophobic Teflon particles on the structure of amyloid beta-peptide

    NARCIS (Netherlands)

    Giacomelli, CE; Norde, W

    2003-01-01

    The amyloid beta-protein (Abeta) constitutes the major peptide component of the amyloid plaque deposits of Alzheimer's disease in humans. The Abeta changes from a nonpathogenic to a pathogenic conformation resulting in self-aggregation and deposition of the peptide. It has been established that dena

  14. Modeling Amyloid Beta Peptide Insertion into Lipid Bilayers

    CERN Document Server

    Mobley, D L; Singh, R R P; Maddox, M W; Longo, M J; Mobley, David L.; Cox, Daniel L.; Singh, Rajiv R. P.; Maddox, Michael W.; Longo, Marjorie L.

    2003-01-01

    Inspired by recent suggestions that the Alzheimer's amyloid beta peptide (A-beta), can insert into cell membranes and form harmful ion channels, we model insertion of the peptide into cell membranes using a Monte Carlo code which is specific at the amino acid level. We examine insertion of the regular A-beta peptide as well as mutants causing familial Alzheimer's disease. We present our results and develop the hypothesis that partial insertion into the membrane, leaving the peptide in one leaflet, increases the probability of harmful channel formation. This hypothesis can partly explain why these mutations are neurotoxic simply due to peptide insertion behavior, and also explains why, normally, A-beta 42 is more toxic to some cultured cells than A-beta 40, but the E22Q mutation reverses this effect. We further apply this model to various artificial A-beta mutants which have been examined experimentally, and offer testable experimental predictions contrasting the roles of aggregation and insertion with regard ...

  15. Key residues for the oligomerization of A{beta}42 protein in Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, Sam [Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095 (United States); Guo, Zhefeng, E-mail: zhefeng@ucla.edu [Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095 (United States)

    2011-10-28

    Highlights: Black-Right-Pointing-Pointer A{beta} oligomers are neurotoxins and likely the causing agents for Alzheimer's disease. Black-Right-Pointing-Pointer A{beta}42 fusion protein form globular oligomers. Black-Right-Pointing-Pointer A{beta}42 fusion protein oligomers contain SDS-resistant tetramers and hexamers. Black-Right-Pointing-Pointer Cysteine substitutions at residues 31, 32, 34, 39-41 disrupt A{beta}42 oligomerization. -- Abstract: Deposition of amyloid fibrils consisting of amyloid {beta} (A{beta}) protein as senile plaques in the brain is a pathological hallmark of Alzheimer's disease. However, a growing body of evidence shows that soluble A{beta} oligomers correlate better with dementia than fibrils, suggesting that A{beta} oligomers may be the primary toxic species. The structure and oligomerization mechanism of these A{beta} oligomers are crucial for developing effective therapeutics. Here we investigated the oligomerization of A{beta}42 in the context of a fusion protein containing GroES and ubiquitin fused to the N-terminus of A{beta} sequence. The presence of fusion protein partners, in combination with a denaturing buffer containing 8 M urea at pH 10, is unfavorable for A{beta}42 aggregation, thus allowing only the most stable structures to be observed. Transmission electron microscopy showed that A{beta}42 fusion protein formed globular oligomers, which bound weakly to thioflavin T and Congo red. SDS-PAGE shows that A{beta}42 fusion protein formed SDS-resistant hexamers and tetramers. In contrast, A{beta}40 fusion protein remained as monomers on SDS gel, suggesting that the oligomerization of A{beta}42 fusion protein is not due to the fusion protein partners. Cysteine scanning mutagenesis at 22 residue positions further revealed that single cysteine substitutions of the C-terminal hydrophobic residues (I31, I32, L34, V39, V40, and I41) led to disruption of hexamer and tetramer formation, suggesting that hydrophobic interactions

  16. Designed amyloid beta peptide fibril - a tool for high-throughput screening of fibril inhibitors.

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    Dolphin, Gunnar T; Ouberai, Myriam; Dumy, Pascal; Garcia, Julian

    2007-11-01

    Amyloid beta peptide (Abeta) fibril formation is widely believed to be the causative event of Alzheimer's disease pathogenesis. Therapeutic approaches are therefore in development that target various sites in the production and aggregation of Abeta. Herein we present a high-throughput screening tool to generate novel hit compounds that block Abeta fibril formation. This tool is an application for our fibril model (Abeta(16-37)Y(20)K(22)K(24))(4), which is a covalent assembly of four Abeta fragments. With this tool, screening studies are complete within one hour, as opposed to days with native Abeta(1-40). A Z' factor of 0.84+/-0.03 was determined for fibril formation and inhibition, followed by the reporter molecule thioflavin T. Herein we also describe the analysis of a broad range of reported inhibitors and non-inhibitors of Abeta fibril formation to test the validity of the system. PMID:17876751

  17. Lower levels of cerebrospinal fluid amyloid beta (Abeta) in non-demented Indian controls.

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    Subramanian, Sarada; Sandhyarani, Boya; Shree, A N Divya; Murthy, K Krishna; Kalyani, K; Kumar, S Praveen; Pradeep; Noone, Mohin Jeslie; Taly, A B

    2006-10-23

    Prevalence of Alzheimer's disease in Indian population is lower than in developed countries. To determine whether limitation of amyloid beta (Abeta) concentration may be responsible for lower rate of incidence, we measured the levels of Abeta in cerebrospinal fluid (CSF) collected from 72 non-demented individuals ranging in the age from 20 years to 65 years. These samples were segregated into three groups ranging from 20-35 years, 36-50 years and 51-65 years of age. Levels of Abeta could be detected in all the age groups and they were much lower than the values reported in literature from the developed countries. No significant difference in the average level of Ass was observed with increase in age. PMID:16978775

  18. The Alzheimer's disease-associated amyloid beta-protein is an antimicrobial peptide.

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    Stephanie J Soscia

    Full Text Available BACKGROUND: The amyloid beta-protein (Abeta is believed to be the key mediator of Alzheimer's disease (AD pathology. Abeta is most often characterized as an incidental catabolic byproduct that lacks a normal physiological role. However, Abeta has been shown to be a specific ligand for a number of different receptors and other molecules, transported by complex trafficking pathways, modulated in response to a variety of environmental stressors, and able to induce pro-inflammatory activities. METHODOLOGY/PRINCIPAL FINDINGS: Here, we provide data supporting an in vivo function for Abeta as an antimicrobial peptide (AMP. Experiments used established in vitro assays to compare antimicrobial activities of Abeta and LL-37, an archetypical human AMP. Findings reveal that Abeta exerts antimicrobial activity against eight common and clinically relevant microorganisms with a potency equivalent to, and in some cases greater than, LL-37. Furthermore, we show that AD whole brain homogenates have significantly higher antimicrobial activity than aged matched non-AD samples and that AMP action correlates with tissue Abeta levels. Consistent with Abeta-mediated activity, the increased antimicrobial action was ablated by immunodepletion of AD brain homogenates with anti-Abeta antibodies. CONCLUSIONS/SIGNIFICANCE: Our findings suggest Abeta is a hitherto unrecognized AMP that may normally function in the innate immune system. This finding stands in stark contrast to current models of Abeta-mediated pathology and has important implications for ongoing and future AD treatment strategies.

  19. MALDI, AP/MALDI and ESI techniques for the MS detection of amyloid [beta]-peptides

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    Grasso, Giuseppe; Mineo, Placido; Rizzarelli, Enrico; Spoto, Giuseppe

    2009-04-01

    Amyloid [beta]-peptides (A[beta]s) are involved in several neuropathological conditions such as Alzheimer's disease and considerable experimental evidences have emerged indicating that different proteases play a major role in regulating the accumulation of A[beta]s in the brain. Particularly, insulin-degrading enzyme (IDE) has been shown to degrade A[beta]s at different cleavage sites, but the experimental results reported in the literature and obtained by mass spectrometry methods are somehow fragmentary. The detection of A[beta]s is often complicated by solubility issues, oxidation artifacts and spontaneous aggregation/cleavage and, in order to rationalize the different reported results, we analyzed A[beta]s solutions by three different MS approaches: matrix assisted laser desorption ionization-time of flight (MALDI-TOF), atmospheric pressure (AP) MALDI ion trap and electrospray ionization (ESI) ion trap. Differences in the obtained results are discussed and ESI is chosen as the most suitable MS method for A[beta]s detection. Finally, cleavage sites produced by interaction of A[beta]s with IDE are identified, two of which had never been reported in the literature.

  20. Nasal administration of amyloid-beta peptide decreases cerebral amyloid burden in a mouse model of Alzheimer's disease

    DEFF Research Database (Denmark)

    Weiner, H L; Lemere, C A; Maron, R;

    2000-01-01

    -implicated proteins can induce antigen-specific anti-inflammatory immune responses in mucosal lymphoid tissue which then act systemically. We hypothesized that chronic mucosal administration of Abeta peptide might induce an anti-inflammatory process in AD brain tissue that could beneficially affect......Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease......-Abeta antibodies of the IgG1 and IgG2b classes, and mononuclear cells in the brain expressing the anti-inflammatory cytokines interleukin-4, interleukin-10, and tumor growth factor-beta. Our results demonstrate that chronic nasal administration of Abeta peptide can induce an immune response to Abeta that decreases...

  1. Alzheimer's Disease Beyond Abeta.

    Science.gov (United States)

    Town, Terrence

    2010-05-01

    Many of the Alzheimer's disease (AD) clinical trials have made it far enough down the pipeline to allow conclusions about targeting the amyloid-beta peptide (Abeta) as a therapeutic approach. Based on these results, it is becoming clear that a multifocal approach to AD treatment is probably necessary. However, critical discussion beyond Abeta is necessary to enable the next wave of AD therapeutic targets. For this reason, the 2010 Keystone Symposium, 'Alzheimer's Disease Beyond Abeta', was organized by JoAnne McLaurin and Tony Wyss-Coray to spark topical discussion and debate. While researchers struggled to get beyond that ever-present pathognomonic feature of AD, new and exciting evidence was presented that raised our awareness of what is around the corner for next-generation AD therapeutics beyond Abeta. This report will describe some of the highlights from Copper Mountain Resort throughout the meeting period of 10-15 January 2010 in Colorado (USA). Despite illuminating scientific presentations and intense discussions, a number of important questions remain concerning the best biomarkers and targets to focus on, and when and how to therapeutically intervene. PMID:20429127

  2. Substitution of isoleucine-31 by helical-breaking proline abolishes oxidative stress and neurotoxic properties of Alzheimer's amyloid beta-peptide.

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    Kanski, Jaroslaw; Aksenova, Marina; Schöneich, Christian; Butterfield, D Allan

    2002-06-01

    Alzheimer's disease (AD) brain is characterized by excess deposition of the 42-amino acid amyloid beta-peptide [A(beta)(1-42)]. AD brain is under intense oxidative stress, and we have previously suggested that A(beta)(1-42) was associated with this increased oxidative stress. In addition, we previously demonstrated that the single methionine residue of A(beta)(1-42), residue 35, was critical for the oxidative stress and neurotoxic properties of this peptide. Others have shown that the C-terminal region of A(beta)(1-42) is helical in aqueous micellar solutions, including that part of the protein containing Met35. Importantly, Cu(II)-binding induces alpha-helicity in A(beta) in aqueous solution. Invoking the i + 4 rule of helices, we hypothesized that the carbonyl oxygen of Ile31 would interact with the S atom of Met35 to change the electronic environment of the sulfur such that molecular oxygen could lead to the production of a sulfuramyl free radical on Met35. If this hypothesis is correct, a prediction would be that breaking the helical interaction of Ile31 and Met35 would abrogate the oxidative stress and neurotoxic properties of A(beta)(1-42). Accordingly, we investigated A(beta)(1-42) in which the Ile31 residue was replaced with the helix-breaking amino acid, proline. The alpha-helical environment around Met35 was completely abolished as indicated by circular dichroism (CD)-spectroscopy. As a consequence, the aggregation, oxidative stress, Cu(II) reduction, and neurotoxic properties of A(beta)(1-42)I31P were completely altered compared to native A(beta)(1-42). The results presented here are consistent with the notion that interaction of Ile31 with Met35 may play an important role in the oxidative processes of Met35 contributing to the toxicity of the peptide.

  3. Immunodominant epitope and properties of pyroglutamate-modified Abeta-specific antibodies produced in rabbits.

    Science.gov (United States)

    Acero, G; Manoutcharian, K; Vasilevko, V; Munguia, M E; Govezensky, T; Coronas, G; Luz-Madrigal, A; Cribbs, D H; Gevorkian, G

    2009-08-18

    N-truncated and N-modified forms of amyloid beta (Abeta) peptide are found in diffused and dense core plaques in Alzheimer's disease (AD) and Down's syndrome patients as well as transgenic mouse models of AD. Although the pathological significance of these shortened forms Abeta is not completely understood, previous studies have demonstrated that these peptides are significantly more resistant to degradation, aggregate more rapidly in vitro and exhibit similar or, in some cases, increased toxicity in hippocampal neuronal cultures compared to the full length peptides. In the present study we further investigated the mechanisms of toxicity of one of the most abundant N-truncated/modified Abeta peptide bearing amino-terminal pyroglutamate at position 3 (AbetaN3(pE)). We demonstrated that AbetaN3(pE) oligomers induce phosphatidyl serine externalization and membrane damage in SH-SY5Y cells. Also, we produced AbetaN3(pE)-specific polyclonal antibodies in rabbit and identified an immunodominant epitope recognized by anti-AbetaN3(pE) antibodies. Our results are important for developing new immunotherapeutic compounds specifically targeting AbetaN3(pE) aggregates since the most commonly used immunogens in the majority of vaccines for AD have been shown to induce antibodies that recognize the N-terminal immunodominant epitope (EFRH) of the full length Abeta, which is absent in N-amino truncated peptides.

  4. Stoichiometric inhibition of amyloid beta-protein aggregation with peptides containing alternating alpha,alpha-disubstituted amino acids.

    Science.gov (United States)

    Etienne, Marcus A; Aucoin, Jed P; Fu, Yanwen; McCarley, Robin L; Hammer, Robert P

    2006-03-22

    We have prepared two peptides based on the hydrophobic core (Lys-Leu-Val-Phe-Phe) of amyloid beta-protein (Abeta) that contain alpha,alpha-disubstituted amino acids at alternating positions, but differ in the positioning of the oligolysine chain (AMY-1, C-terminus; AMY-2, N-terminus). We have studied the effects of AMY-1 and AMY-2 on the aggregation of Abeta and find that, at stoichiometric concentrations, both peptides completely stop Abeta fibril growth. Equimolar mixtures of AMY-1 and Abeta form only globular aggregates as imaged by scanning force microscopy and transmission electron microscopy. These samples show no signs of protofibrillar or fibrillar material even after prolonged periods of time (4.5 months). Also, 10 mol % of AMY-1 prevents Abeta self-assembly for long periods of time; aged samples (4.5 months) show only a few protofibrillar or fibrillar aggregates. Circular dichroism spectroscopy of equimolar mixtures of AMY-1 and Abeta show that the secondary structure of the mixture changes over time and progresses to a predominantly beta-sheet structure, which is consistent with the design of these inhibitors preferring a sheet-like conformation. Changing the position of the charged tail on the peptide, AMY-2 interacts with Abeta differently in that equimolar mixtures form large ( approximately 1 mum) globular aggregates which do not progress to fibrils, but precipitate out of solution. The differences in the aggregation mediated by the two peptides is discussed in terms of a model where the inhibitors act as cosurfactants that interfere with the native ability of Abeta to self-assemble by disrupting hydrophobic interactions either at the C-terminus or N-terminus of Abeta. PMID:16536517

  5. TLR2 is a primary receptor for Alzheimer's amyloid beta peptide to trigger neuroinflammatory activation.

    NARCIS (Netherlands)

    Liu, S.; Liu, Y.; Hao, W.; Wolf, L.; Kiliaan, A.J.; Penke, B.; Rube, C.E.; Walter, J.; Heneka, M.T.; Hartmann, T.; Menger, M.D.; Fassbender, K.

    2012-01-01

    Microglia activated by extracellularly deposited amyloid beta peptide (Abeta) act as a two-edged sword in Alzheimer's disease pathogenesis: on the one hand, they damage neurons by releasing neurotoxic proinflammatory mediators (M1 activation); on the other hand, they protect neurons by triggering an

  6. DCP-LA neutralizes mutant amyloid beta peptide-induced impairment of long-term potentiation and spatial learning.

    Science.gov (United States)

    Nagata, Tetsu; Tomiyama, Takami; Tominaga, Takemi; Mori, Hiroshi; Yaguchi, Takahiro; Nishizaki, Tomoyuki

    2010-01-01

    Long-term potentiation (LTP) was monitored from the CA1 region of the intact rat hippocampus by delivering high frequency stimulation (HFS) to the Schaffer collateral commissural pathway. Intraventricular injection with mutant amyloid beta(1-42) peptide lacking glutamate-22 (Abeta(1-42)E22Delta), favoring oligomerization, 10 min prior to HFS, inhibited expression of LTP, with the potency more than wild-type amyloid beta(1-42) peptide. Intraperitoneal injection with the linoleic acid derivative 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA) 70 min prior to HFS neutralized mutant Abeta(1-42)E22Delta peptide-induced LTP inhibition. In the water maze test, continuous intraventricular injection with mutant Abeta(1-42)E22Delta peptide for 14 days prolonged the acquisition latency as compared with that for control, with the potency similar to wild-type Abeta(1-42) peptide, and intraperitoneal injection with DCP-LA shortened the prolonged latency to control levels. The results of the present study indicate that DCP-LA neutralizes mutant Abeta(1-42)E22Delta peptide-induced impairment of LTP and spatial learning. PMID:19716848

  7. DCP-LA neutralizes mutant amyloid beta peptide-induced impairment of long-term potentiation and spatial learning.

    Science.gov (United States)

    Nagata, Tetsu; Tomiyama, Takami; Tominaga, Takemi; Mori, Hiroshi; Yaguchi, Takahiro; Nishizaki, Tomoyuki

    2010-01-01

    Long-term potentiation (LTP) was monitored from the CA1 region of the intact rat hippocampus by delivering high frequency stimulation (HFS) to the Schaffer collateral commissural pathway. Intraventricular injection with mutant amyloid beta(1-42) peptide lacking glutamate-22 (Abeta(1-42)E22Delta), favoring oligomerization, 10 min prior to HFS, inhibited expression of LTP, with the potency more than wild-type amyloid beta(1-42) peptide. Intraperitoneal injection with the linoleic acid derivative 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA) 70 min prior to HFS neutralized mutant Abeta(1-42)E22Delta peptide-induced LTP inhibition. In the water maze test, continuous intraventricular injection with mutant Abeta(1-42)E22Delta peptide for 14 days prolonged the acquisition latency as compared with that for control, with the potency similar to wild-type Abeta(1-42) peptide, and intraperitoneal injection with DCP-LA shortened the prolonged latency to control levels. The results of the present study indicate that DCP-LA neutralizes mutant Abeta(1-42)E22Delta peptide-induced impairment of LTP and spatial learning.

  8. Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers II: Sigma-2/PGRMC1 receptors mediate Abeta 42 oligomer binding and synaptotoxicity.

    Science.gov (United States)

    Izzo, Nicholas J; Xu, Jinbin; Zeng, Chenbo; Kirk, Molly J; Mozzoni, Kelsie; Silky, Colleen; Rehak, Courtney; Yurko, Raymond; Look, Gary; Rishton, Gilbert; Safferstein, Hank; Cruchaga, Carlos; Goate, Alison; Cahill, Michael A; Arancio, Ottavio; Mach, Robert H; Craven, Rolf; Head, Elizabeth; LeVine, Harry; Spires-Jones, Tara L; Catalano, Susan M

    2014-01-01

    Amyloid beta (Abeta) 1-42 oligomers accumulate in brains of patients with Mild Cognitive Impairment (MCI) and disrupt synaptic plasticity processes that underlie memory formation. Synaptic binding of Abeta oligomers to several putative receptor proteins is reported to inhibit long-term potentiation, affect membrane trafficking and induce reversible spine loss in neurons, leading to impaired cognitive performance and ultimately to anterograde amnesia in the early stages of Alzheimer's disease (AD). We have identified a receptor not previously associated with AD that mediates the binding of Abeta oligomers to neurons, and describe novel therapeutic antagonists of this receptor capable of blocking Abeta toxic effects on synapses in vitro and cognitive deficits in vivo. Knockdown of sigma-2/PGRMC1 (progesterone receptor membrane component 1) protein expression in vitro using siRNA results in a highly correlated reduction in binding of exogenous Abeta oligomers to neurons of more than 90%. Expression of sigma-2/PGRMC1 is upregulated in vitro by treatment with Abeta oligomers, and is dysregulated in Alzheimer's disease patients' brain compared to age-matched, normal individuals. Specific, high affinity small molecule receptor antagonists and antibodies raised against specific regions on this receptor can displace synthetic Abeta oligomer binding to synaptic puncta in vitro and displace endogenous human AD patient oligomers from brain tissue sections in a dose-dependent manner. These receptor antagonists prevent and reverse the effects of Abeta oligomers on membrane trafficking and synapse loss in vitro and cognitive deficits in AD mouse models. These findings suggest sigma-2/PGRMC1 receptors mediate saturable oligomer binding to synaptic puncta on neurons and that brain penetrant, small molecules can displace endogenous and synthetic oligomers and improve cognitive deficits in AD models. We propose that sigma-2/PGRMC1 is a key mediator of the pathological effects of

  9. Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers II: Sigma-2/PGRMC1 receptors mediate Abeta 42 oligomer binding and synaptotoxicity.

    Directory of Open Access Journals (Sweden)

    Nicholas J Izzo

    Full Text Available Amyloid beta (Abeta 1-42 oligomers accumulate in brains of patients with Mild Cognitive Impairment (MCI and disrupt synaptic plasticity processes that underlie memory formation. Synaptic binding of Abeta oligomers to several putative receptor proteins is reported to inhibit long-term potentiation, affect membrane trafficking and induce reversible spine loss in neurons, leading to impaired cognitive performance and ultimately to anterograde amnesia in the early stages of Alzheimer's disease (AD. We have identified a receptor not previously associated with AD that mediates the binding of Abeta oligomers to neurons, and describe novel therapeutic antagonists of this receptor capable of blocking Abeta toxic effects on synapses in vitro and cognitive deficits in vivo. Knockdown of sigma-2/PGRMC1 (progesterone receptor membrane component 1 protein expression in vitro using siRNA results in a highly correlated reduction in binding of exogenous Abeta oligomers to neurons of more than 90%. Expression of sigma-2/PGRMC1 is upregulated in vitro by treatment with Abeta oligomers, and is dysregulated in Alzheimer's disease patients' brain compared to age-matched, normal individuals. Specific, high affinity small molecule receptor antagonists and antibodies raised against specific regions on this receptor can displace synthetic Abeta oligomer binding to synaptic puncta in vitro and displace endogenous human AD patient oligomers from brain tissue sections in a dose-dependent manner. These receptor antagonists prevent and reverse the effects of Abeta oligomers on membrane trafficking and synapse loss in vitro and cognitive deficits in AD mouse models. These findings suggest sigma-2/PGRMC1 receptors mediate saturable oligomer binding to synaptic puncta on neurons and that brain penetrant, small molecules can displace endogenous and synthetic oligomers and improve cognitive deficits in AD models. We propose that sigma-2/PGRMC1 is a key mediator of the pathological

  10. The Structure of the Amyloid-[beta] Peptide High-Affinity Copper II Binding Site in Alzheimer Disease

    Energy Technology Data Exchange (ETDEWEB)

    Streltsov, Victor A.; Titmuss, Stephen J.; Epa, V. Chandana; Barnham, Kevin J.; Masters, Colin L.; Varghese, Joseph N. (CSIRO/MHT)

    2008-11-03

    Neurodegeneration observed in Alzheimer disease (AD) is believed to be related to the toxicity from reactive oxygen species (ROS) produced in the brain by the amyloid-{beta} (A{beta}) protein bound primarily to copper ions. The evidence for an oxidative stress role of A{beta}-Cu redox chemistry is still incomplete. Details of the copper binding site in A{beta} may be critical to the etiology of AD. Here we present the structure determined by combining x-ray absorption spectroscopy (XAS) and density functional theory analysis of A{beta} peptides complexed with Cu{sup 2+} in solution under a range of buffer conditions. Phosphate-buffered saline buffer salt (NaCl) concentration does not affect the high-affinity copper binding mode but alters the second coordination sphere. The XAS spectra for truncated and full-length A{beta}-Cu{sup 2+} peptides are similar. The novel distorted six-coordinated (3N3O) geometry around copper in the A{beta}-Cu{sup 2+} complexes include three histidines: glutamic, or/and aspartic acid, and axial water. The structure of the high-affinity Cu{sup 2+} binding site is consistent with the hypothesis that the redox activity of the metal ion bound to A{beta} can lead to the formation of dityrosine-linked dimers found in AD.

  11. Computational selection of inhibitors of Abeta aggregation and neuronal toxicity.

    Science.gov (United States)

    Chen, Deliang; Martin, Zane S; Soto, Claudio; Schein, Catherine H

    2009-07-15

    Alzheimer's disease (AD) is characterized by the cerebral accumulation of misfolded and aggregated amyloid-beta protein (Abeta). Disease symptoms can be alleviated, in vitro and in vivo, by 'beta-sheet breaker' pentapeptides that reduce plaque load. However the peptide nature of these compounds, made them biologically unstable and unable to penetrate membranes with high efficiency. The main goal of this study was to use computational methods to identify small molecule mimetics with better drug-like properties. For this purpose, the docked conformations of the active peptides were used to identify compounds with similar activities. A series of related beta-sheet breaker peptides were docked to solid state NMR structures of a fibrillar form of Abeta. The lowest energy conformations of the active peptides were used to design three dimensional (3D)-pharmacophores, suitable for screening the NCI database with Unity. Small molecular weight compounds with physicochemical features and a conformation similar to the active peptides were selected, ranked by docking and biochemical parameters. Of 16 diverse compounds selected for experimental screening, 2 prevented and reversed Abeta aggregation at 2-3microM concentration, as measured by Thioflavin T (ThT) fluorescence and ELISA assays. They also prevented the toxic effects of aggregated Abeta on neuroblastoma cells. Their low molecular weight and aqueous solubility makes them promising lead compounds for treating AD.

  12. Role of glycine-33 and methionine-35 in Alzheimer's amyloid beta-peptide 1-42-associated oxidative stress and neurotoxicity.

    Science.gov (United States)

    Kanski, Jaroslaw; Varadarajan, Sridhar; Aksenova, Marina; Butterfield, D Allan

    2002-03-16

    Recent theoretical calculations predicted that Gly33 of one molecule of amyloid beta-peptide (1-42) (Abeta(1-42)) is attacked by a putative sulfur-based free radical of methionine residue 35 of an adjacent peptide. This would lead to a carbon-centered free radical on Gly33 that would immediately bind oxygen to form a peroxyl free radical. Such peroxyl free radicals could contribute to the reported Abeta(1-42)-induced lipid peroxidation, protein oxidation, and neurotoxicity, all of which are prevented by the chain-breaking antioxidant vitamin E. In the theoretical calculations, it was shown that no other amino acid, only Gly, could undergo such a reaction. To test this prediction we studied the effects of substitution of Gly33 of Abeta(1-42) on protein oxidation and neurotoxicity of hippocampal neurons and free radical formation in synaptosomes and in solution. Gly33 of Abeta(1-42) was substituted by Val (Abeta(1-42G33V)). The substituted peptide showed almost no neuronal toxicity compared to the native Abeta(1-42) as well as significantly lowered levels of oxidized proteins. In addition, synaptosomes subjected to Abeta(1-42G33V) showed considerably lower dichlorofluorescein-dependent fluorescence - a measure of reactive oxygen species (ROS) - in comparison to native Abeta(1-42) treatment. The ability of the peptides to generate ROS was also evaluated by electron paramagnetic resonance (EPR) spin trapping methods using the ultrapure spin trap N-tert-butyl-alpha-phenylnitrone (PBN). While Abeta(1-42) gave a strong mixture of four- and six-line PBN-derived spectra, the intensity of the EPR signal generated by Abeta(1-42G33V) was far less. Finally, the ability of the peptides to form fibrils was evaluated by electron microscopy. Abeta(1-42G33V) does not form fibrils nearly as well as Abeta(1-42) after 48 h of incubation. The results suggest that Gly33 may be a possible site of free radical propagation processes that are initiated on Met35 of Abeta(1-42) and that

  13. Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers I: Abeta 42 oligomer binding to specific neuronal receptors is displaced by drug candidates that improve cognitive deficits.

    Directory of Open Access Journals (Sweden)

    Nicholas J Izzo

    Full Text Available Synaptic dysfunction and loss caused by age-dependent accumulation of synaptotoxic beta amyloid (Abeta 1-42 oligomers is proposed to underlie cognitive decline in Alzheimer's disease (AD. Alterations in membrane trafficking induced by Abeta oligomers mediates reduction in neuronal surface receptor expression that is the basis for inhibition of electrophysiological measures of synaptic plasticity and thus learning and memory. We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers. Synthetic Abeta oligomers bind saturably to a single site on neuronal synapses and induce deficits in membrane trafficking in neuronal cultures with an EC50 that corresponds to its binding affinity. The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking. These molecules are highly brain penetrant and prevent and restore cognitive deficits in mouse models of Alzheimer's disease. Counter-screening these compounds against a broad panel of potential CNS targets revealed they are highly potent and specific ligands of the sigma-2/PGRMC1 receptor. Brain concentrations of the compounds corresponding to greater than 80% receptor occupancy at the sigma-2/PGRMC1 receptor restore cognitive function in transgenic hAPP Swe/Ldn mice. These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect. The first-in-class small molecule receptor antagonists described here restore memory to normal in

  14. Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers I: Abeta 42 oligomer binding to specific neuronal receptors is displaced by drug candidates that improve cognitive deficits.

    Science.gov (United States)

    Izzo, Nicholas J; Staniszewski, Agnes; To, Lillian; Fa, Mauro; Teich, Andrew F; Saeed, Faisal; Wostein, Harrison; Walko, Thomas; Vaswani, Anisha; Wardius, Meghan; Syed, Zanobia; Ravenscroft, Jessica; Mozzoni, Kelsie; Silky, Colleen; Rehak, Courtney; Yurko, Raymond; Finn, Patricia; Look, Gary; Rishton, Gilbert; Safferstein, Hank; Miller, Miles; Johanson, Conrad; Stopa, Edward; Windisch, Manfred; Hutter-Paier, Birgit; Shamloo, Mehrdad; Arancio, Ottavio; LeVine, Harry; Catalano, Susan M

    2014-01-01

    Synaptic dysfunction and loss caused by age-dependent accumulation of synaptotoxic beta amyloid (Abeta) 1-42 oligomers is proposed to underlie cognitive decline in Alzheimer's disease (AD). Alterations in membrane trafficking induced by Abeta oligomers mediates reduction in neuronal surface receptor expression that is the basis for inhibition of electrophysiological measures of synaptic plasticity and thus learning and memory. We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers. Synthetic Abeta oligomers bind saturably to a single site on neuronal synapses and induce deficits in membrane trafficking in neuronal cultures with an EC50 that corresponds to its binding affinity. The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking. These molecules are highly brain penetrant and prevent and restore cognitive deficits in mouse models of Alzheimer's disease. Counter-screening these compounds against a broad panel of potential CNS targets revealed they are highly potent and specific ligands of the sigma-2/PGRMC1 receptor. Brain concentrations of the compounds corresponding to greater than 80% receptor occupancy at the sigma-2/PGRMC1 receptor restore cognitive function in transgenic hAPP Swe/Ldn mice. These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect. The first-in-class small molecule receptor antagonists described here restore memory to normal in multiple AD models

  15. Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers I: Abeta 42 oligomer binding to specific neuronal receptors is displaced by drug candidates that improve cognitive deficits.

    Science.gov (United States)

    Izzo, Nicholas J; Staniszewski, Agnes; To, Lillian; Fa, Mauro; Teich, Andrew F; Saeed, Faisal; Wostein, Harrison; Walko, Thomas; Vaswani, Anisha; Wardius, Meghan; Syed, Zanobia; Ravenscroft, Jessica; Mozzoni, Kelsie; Silky, Colleen; Rehak, Courtney; Yurko, Raymond; Finn, Patricia; Look, Gary; Rishton, Gilbert; Safferstein, Hank; Miller, Miles; Johanson, Conrad; Stopa, Edward; Windisch, Manfred; Hutter-Paier, Birgit; Shamloo, Mehrdad; Arancio, Ottavio; LeVine, Harry; Catalano, Susan M

    2014-01-01

    Synaptic dysfunction and loss caused by age-dependent accumulation of synaptotoxic beta amyloid (Abeta) 1-42 oligomers is proposed to underlie cognitive decline in Alzheimer's disease (AD). Alterations in membrane trafficking induced by Abeta oligomers mediates reduction in neuronal surface receptor expression that is the basis for inhibition of electrophysiological measures of synaptic plasticity and thus learning and memory. We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers. Synthetic Abeta oligomers bind saturably to a single site on neuronal synapses and induce deficits in membrane trafficking in neuronal cultures with an EC50 that corresponds to its binding affinity. The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking. These molecules are highly brain penetrant and prevent and restore cognitive deficits in mouse models of Alzheimer's disease. Counter-screening these compounds against a broad panel of potential CNS targets revealed they are highly potent and specific ligands of the sigma-2/PGRMC1 receptor. Brain concentrations of the compounds corresponding to greater than 80% receptor occupancy at the sigma-2/PGRMC1 receptor restore cognitive function in transgenic hAPP Swe/Ldn mice. These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect. The first-in-class small molecule receptor antagonists described here restore memory to normal in multiple AD models

  16. Silibinin attenuates amyloid beta(25-35) peptide-induced memory impairments: implication of inducible nitric-oxide synthase and tumor necrosis factor-alpha in mice.

    Science.gov (United States)

    Lu, P; Mamiya, T; Lu, L L; Mouri, A; Niwa, M; Hiramatsu, M; Zou, L B; Nagai, T; Ikejima, T; Nabeshima, T

    2009-10-01

    In Alzheimer's disease (AD), the deposition of amyloid peptides is invariably associated with oxidative stress and inflammatory responses. Silibinin (silybin), a flavonoid derived from the herb milk thistle, has potent anti-inflammatory and antioxidant activities. However, it remains unclear whether silibinin improves amyloid beta (Abeta) peptide-induced neurotoxicity. In this study, we examined the effect of silibinin on the fear-conditioning memory deficits, inflammatory response, and oxidative stress induced by the intracerebroventricular injection of Abeta peptide(25-35) (Abeta(25-35)) in mice. Mice were treated with silibinin (2, 20, and 200 mg/kg p.o., once a day for 8 days) from the day of the Abeta(25-35) injection (day 0). Memory function was evaluated in cued and contextual fear-conditioning tests (day 6). Nitrotyrosine levels in the hippocampus and amygdala were examined (day 8). The mRNA expression of inducible nitric-oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) in the hippocampus and amygdala was measured 2 h after the Abeta(25-35) injection. We found that silibinin significantly attenuated memory deficits caused by Abeta(25-35) in the cued and contextual fear-conditioning test. Silibinin significantly inhibited the increase in nitrotyrosine levels in the hippocampus and amygdala induced by Abeta(25-35). Nitrotyrosine levels in these regions were negatively correlated with memory performance. Moreover, real-time RT-PCR revealed that silibinin inhibited the overexpression of iNOS and TNF-alpha mRNA in the hippocampus and amygdala induced by Abeta(25-35). These findings suggest that silibinin (i) attenuates memory impairment through amelioration of oxidative stress and inflammatory response induced by Abeta(25-35) and (ii) may be a potential candidate for an AD medication. PMID:19638571

  17. Differential modulation of Alzheimer's disease amyloid beta-peptide accumulation by diverse classes of metal ligands.

    Science.gov (United States)

    Caragounis, Aphrodite; Du, Tai; Filiz, Gulay; Laughton, Katrina M; Volitakis, Irene; Sharples, Robyn A; Cherny, Robert A; Masters, Colin L; Drew, Simon C; Hill, Andrew F; Li, Qiao-Xin; Crouch, Peter J; Barnham, Kevin J; White, Anthony R

    2007-11-01

    Biometals have an important role in AD (Alzheimer's disease) and metal ligands have been investigated as potential therapeutic agents for treatment of AD. In recent studies the 8HQ (8-hydroxyquinoline) derivative CQ (clioquinol) has shown promising results in animal models and small clinical trials; however, the actual mode of action in vivo is still being investigated. We previously reported that CQ-metal complexes up-regulated MMP (matrix metalloprotease) activity in vitro by activating PI3K (phosphoinositide 3-kinase) and JNK (c-jun N-terminal kinase), and that the increased MMP activity resulted in enhanced degradation of secreted Abeta (amyloid beta) peptide. In the present study, we have further investigated the biochemical mechanisms by which metal ligands affect Abeta metabolism. To achieve this, we measured the effects of diverse metal ligands on cellular metal uptake and secreted Abeta levels in cell culture. We report that different classes of metal ligands including 8HQ and phenanthroline derivatives and the sulfur compound PDTC (pyrrolidine dithiocarbamate) elevated cellular metal levels (copper and zinc), and resulted in substantial loss of secreted Abeta. Generally, the ability to inhibit Abeta levels correlated with a higher lipid solubility of the ligands and their capacity to increase metal uptake. However, we also identified several ligands that potently inhibited Abeta levels while only inducing minimal change to cellular metal levels. Metal ligands that inhibited Abeta levels [e.g. CQ, 8HQ, NC (neocuproine), 1,10-phenanthroline and PDTC] induced metal-dependent activation of PI3K and JNK, resulting in JNK-mediated up-regulation of metalloprotease activity and subsequent loss of secreted Abeta. The findings in the present study show that diverse metal ligands with high lipid solubility can elevate cellular metal levels resulting in metalloprotease-dependent inhibition of Abeta. Given that a structurally diverse array of ligands was assessed, the

  18. Methionine residue 35 is critical for the oxidative stress and neurotoxic properties of Alzheimer's amyloid beta-peptide 1-42.

    Science.gov (United States)

    Butterfield, D Allan; Kanski, Jaroslaw

    2002-07-01

    Amyloid beta-peptide 1-42 [Abeta(1-42)] is central to the pathogenesis of Alzheimer's disease (AD), and the AD brain is under intense oxidative stress. Our laboratory combined these two aspects of AD into the Abeta-associated free radical oxidative stress model for neurodegeneration in AD brain. Abeta(1-42) caused protein oxidation, lipid peroxidation, reactive oxygen species formation, and cell death in neuronal and synaptosomal systems, all of which could be inhibited by free radical antioxidants. Recent studies have been directed at discerning molecular mechanisms by which Abeta(1-42)-associated free radical oxidative stress and neurotoxicity arise. The single methionine located in residue 35 of Abeta(1-42) is critical for these properties. This review presents the evidence supporting the role of methionine in Abeta(1-42)-associated free radical oxidative stress and neurotoxicity. This work is of obvious relevance to AD and provides a coupling between the centrality of Abeta(1-42) in the pathogenesis of AD and the oxidative stress under which the AD brain exists.

  19. All-atom molecular dynamics studies of the full-length {beta}-amyloid peptides

    Energy Technology Data Exchange (ETDEWEB)

    Luttmann, Edgar [Department of Chemistry, Faculty of Science, University of Paderborn, Warburgerstr. 100, 33098 Paderborn (Germany); Fels, Gregor [Department of Chemistry, Faculty of Science, University of Paderborn, Warburgerstr. 100, 33098 Paderborn (Germany)], E-mail: fels@uni-paderborn.de

    2006-03-31

    {beta}-Amyloid peptides are believed to play an essential role in Alzheimer's disease (AD), due to their sedimentation in the form of {beta}-amyloid aggregates in the brain of AD-patients, and the in vitro neurotoxicity of oligomeric aggregates. The monomeric peptides come in different lengths of 39-43 residues, of which the 42 alloform seems to be most strongly associated with AD-symptoms. Structural information on these peptides to date comes from NMR studies in acidic solutions, organic solvents, or on shorter fragments of the peptide. In addition X-ray and solid-state NMR investigations of amyloid fibrils yield insight into the structure of the final aggregate and therefore define the endpoint of any conformational change of an A{beta}-monomer along the aggregation process. The conformational changes necessary to connect the experimentally known conformations are not yet understood and this process is an active field of research. In this paper, we report results from all-atom molecular dynamics simulations based on experimental data from four different peptides of 40 amino acids and two peptides consisting of 42 amino acids. The simulations allow for the analysis of intramolecular interactions and the role of structural features. In particular, they show the appearance of {beta}-turn in the region between amino acid 21 and 33, forming a hook-like shape as it is known to exist in the fibrillar A{beta}-structures. This folding does not depend on the formation of a salt bridge between Asp-23 and Lys-28 but requires the A{beta}(1-42) as such structure was not observed in the shorter system A{beta}(1-40)

  20. Alzheimer's disease and amyloid beta-peptide deposition in the brain: a matter of 'aging'?

    DEFF Research Database (Denmark)

    Moro, Maria Luisa; Collins, Matthew J; Cappellini, Enrico

    2010-01-01

    event in AD (Alzheimer's disease) synaptic dysfunctions. Structural alterations introduced by site-specific modifications linked to protein aging may affect Abeta production, polymerization and clearance, and therefore play a pivotal role in the pathogenesis of sporadic and genetic forms of AD. Early......Biomolecules can experience aging processes that limit their long-term functionality in organisms. Typical markers of protein aging are spontaneous chemical modifications, such as AAR (amino acid racemization) and AAI (amino acid isomerization), mainly involving aspartate and asparagine residues....... Since these modifications may affect folding and turnover, they reduce protein functionality over time and may be linked to pathological conditions. The present mini-review describes evidence of AAR and AAI involvement in the misfolding and brain accumulation of Abeta (amyloid beta-peptide), a central...

  1. Mitochondrial Ca2+ overload underlies Abeta oligomers neurotoxicity providing an unexpected mechanism of neuroprotection by NSAIDs.

    Directory of Open Access Journals (Sweden)

    Sara Sanz-Blasco

    Full Text Available Dysregulation of intracellular Ca(2+ homeostasis may underlie amyloid beta peptide (Abeta toxicity in Alzheimer's Disease (AD but the mechanism is unknown. In search for this mechanism we found that Abeta(1-42 oligomers, the assembly state correlating best with cognitive decline in AD, but not Abeta fibrils, induce a massive entry of Ca(2+ in neurons and promote mitochondrial Ca(2+ overload as shown by bioluminescence imaging of targeted aequorin in individual neurons. Abeta oligomers induce also mitochondrial permeability transition, cytochrome c release, apoptosis and cell death. Mitochondrial depolarization prevents mitochondrial Ca(2+ overload, cytochrome c release and cell death. In addition, we found that a series of non-steroidal anti-inflammatory drugs (NSAIDs including salicylate, sulindac sulfide, indomethacin, ibuprofen and R-flurbiprofen depolarize mitochondria and inhibit mitochondrial Ca(2+ overload, cytochrome c release and cell death induced by Abeta oligomers. Our results indicate that i mitochondrial Ca(2+ overload underlies the neurotoxicity induced by Abeta oligomers and ii inhibition of mitochondrial Ca(2+ overload provides a novel mechanism of neuroprotection by NSAIDs against Abeta oligomers and AD.

  2. Molecular Dynamics Simulation of Amyloid Beta Dimer Formation

    CERN Document Server

    Urbanc, B; Ding, F; Sammond, D; Khare, S; Buldyrev, S V; Stanley, H E; Dokholyan, N V

    2004-01-01

    Recent experiments with amyloid-beta (Abeta) peptide suggest that formation of toxic oligomers may be an important contribution to the onset of Alzheimer's disease. The toxicity of Abeta oligomers depends on their structure, which is governed by assembly dynamics. Due to limitations of current experimental techniques, a detailed knowledge of oligomer structure at the atomic level is missing. We introduce a molecular dynamics approach to study Abeta dimer formation: (1) we use discrete molecular dynamics simulations of a coarse-grained model to identify a variety of dimer conformations, and (2) we employ all-atom molecular mechanics simulations to estimate the thermodynamic stability of all dimer conformations. Our simulations of a coarse-grained Abeta peptide model predicts ten different planar beta-strand dimer conformations. We then estimate the free energies of all dimer conformations in all-atom molecular mechanics simulations with explicit water. We compare the free energies of Abeta(1-42) and Abeta(1-40...

  3. Structures of A[beta]-Related Peptide−Monoclonal Antibody Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Gardberg, Anna; Dice, Lezlee; Pridgen, Kathleen; Ko, Jan; Patterson, Paul; Ou, Susan; Wetzel, Ronald; Dealwis, Chris; (Case Western); (CIT); (Tennessee-K)

    2009-06-15

    Passive immunotherapy (PI) is being explored as a potential therapeutic against Alzheimer's disease. The most promising antibodies (Abs) used in PI target the EFRH motif of the A{beta} N-terminus. The monoclonal anti-A{beta} Ab PFA1 recognizes the EFRH epitope of A{beta}. PFA1 has a high affinity for A{beta} fibrils and protofibrils (0.1 nM), as well as good affinity for A{beta} monomers (20 nM). However, PFA1 binds the toxic N-terminally modified pyroglutamate peptide pyro-Glu3-A{beta} with a 77-fold loss in affinity compared to the WT A{beta}(1-8). Furthermore, our earlier work illustrated PFA1's potential for cross-reactivity. The receptor tyrosine kinase Ror2, which plays a role in skeletal and bone formation, possesses the EFRH sequence. PFA1 Fab binds the Ror2(518-525) peptide sequence REEFRHEA with a 3-fold enhancement over WT A{beta}(1-8). In this work, the crystal structures of the hybridoma-derived PFA1 Fab in complex with pyro-Glu3-A{beta} peptide and with a cross-reacting peptide from Ror2 have been determined at resolutions of 1.95 and 2.7 {angstrom}, respectively. As with wild-type A{beta}, these peptides bind to the Fab via a combination of charge- and shape-complementarity, hydrogen-bonding, and hydrophobic interactions. Comparison of the structures of the four peptides A{beta}(1-8), Grip1, pyro-Glu3-A{beta}(3-8), and Ror2 in complex with PFA1 shows that the greatest conformational flexibility occurs at residues 2 to 3 and 8 of the peptide. These structures provide a molecular basis of the specificity tolerance of PFA1 and its ability to recognize A{beta} N-terminal heterogeneity. The structures provide clues to improving mAb specificity and affinity for pyroglutamate A{beta}.

  4. Alzheimer's disease cybrids replicate beta-amyloid abnormalities through cell death pathways.

    Science.gov (United States)

    Khan, S M; Cassarino, D S; Abramova, N N; Keeney, P M; Borland, M K; Trimmer, P A; Krebs, C T; Bennett, J C; Parks, J K; Swerdlow, R H; Parker, W D; Bennett, J P

    2000-08-01

    Alzheimer's disease (AD) is characterized by the deposition in brain of beta-amyloid (Abeta) peptides, elevated brain caspase-3, and systemic deficiency of cytochrome c oxidase. Although increased Abeta deposition can result from mutations in amyloid precursor protein or presenilin genes, the cause of increased Abeta deposition in sporadic AD is unknown. Cytoplasmic hybrid ("cybrid") cells made from mitochondrial DNA of nonfamilial AD subjects show antioxidant-reversible lowering of mitochondrial membrane potential (delta(gYm), secrete twice as much Abeta(1-40) and Abeta(1-42), have increased intracellular Abeta(1-40) (1.7-fold), and develop Congo red-positive Abeta deposits. Also elevated are cytoplasmic cytochrome c (threefold) and caspase-3 activity (twofold). Increased AD cybrid Abeta(1-40) secretion was normalized by inhibition of caspase-3 or secretase and reduced by treatment with the antioxidant S(-)pramipexole. Expression of AD mitochondrial genes in cybrid cells depresses cytochrome c oxidase activity and increases oxidative stress, which, in turn, lowers delta(psi)m. Under stress, cells with AD mitochondrial genes are more likely to activate cell death pathways, which drive caspase 3-mediated Abeta peptide secretion and may account for increased Abeta deposition in the AD brain. Therapeutic strategies for reducing neurodegeneration in sporadic AD can address restoration of delta(psi)m and reduction of elevated Abeta secretion. PMID:10939564

  5. Evidence for novel beta-sheet structures in Iowa mutant beta-amyloid fibrils.

    Science.gov (United States)

    Tycko, Robert; Sciarretta, Kimberly L; Orgel, Joseph P R O; Meredith, Stephen C

    2009-07-01

    Asp23-to-Asn mutation within the coding sequence of beta-amyloid, called the Iowa mutation, is associated with early onset, familial Alzheimer's disease and cerebral amyloid angiopathy, in which patients develop neuritic plaques and massive vascular deposition predominantly of the mutant peptide. We examined the mutant peptide, D23N-Abeta40, by electron microscopy, X-ray diffraction, and solid-state NMR spectroscopy. D23N-Abeta40 forms fibrils considerably faster than the wild-type peptide (k = 3.77 x 10(-3) min(-1) and 1.07 x 10(-4) min(-1) for D23N-Abeta40 and the wild-type peptide WT-Abeta40, respectively) and without a lag phase. Electron microscopy shows that D23N-Abeta40 forms fibrils with multiple morphologies. X-ray fiber diffraction shows a cross-beta pattern, with a sharp reflection at 4.7 A and a broad reflection at 9.4 A, which is notably smaller than the value for WT-Abeta40 fibrils (10.4 A). Solid-state NMR measurements indicate molecular level polymorphism of the fibrils, with only a minority of D23N-Abeta40 fibrils containing the in-register, parallel beta-sheet structure commonly found in WT-Abeta40 fibrils and most other amyloid fibrils. Antiparallel beta-sheet structures in the majority of fibrils are indicated by measurements of intermolecular distances through (13)C-(13)C and (15)N-(13)C dipole-dipole couplings. An intriguing possibility exists that there is a relationship between the aberrant structure of D23N-Abeta40 fibrils and the unusual vasculotropic clinical picture in these patients.

  6. Persistent amyloidosis following suppression of Abeta production in a transgenic model of Alzheimer disease.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available BACKGROUND: The proteases (secretases that cleave amyloid-beta (Abeta peptide from the amyloid precursor protein (APP have been the focus of considerable investigation in the development of treatments for Alzheimer disease. The prediction has been that reducing Abeta production in the brain, even after the onset of clinical symptoms and the development of associated pathology, will facilitate the repair of damaged tissue and removal of amyloid lesions. However, no long-term studies using animal models of amyloid pathology have yet been performed to test this hypothesis. METHODS AND FINDINGS: We have generated a transgenic mouse model that genetically mimics the arrest of Abeta production expected from treatment with secretase inhibitors. These mice overexpress mutant APP from a vector that can be regulated by doxycycline. Under normal conditions, high-level expression of APP quickly induces fulminant amyloid pathology. We show that doxycycline administration inhibits transgenic APP expression by greater than 95% and reduces Abeta production to levels found in nontransgenic mice. Suppression of transgenic Abeta synthesis in this model abruptly halts the progression of amyloid pathology. However, formation and disaggregation of amyloid deposits appear to be in disequilibrium as the plaques require far longer to disperse than to assemble. Mice in which APP synthesis was suppressed for as long as 6 mo after the formation of Abeta deposits retain a considerable amyloid load, with little sign of active clearance. CONCLUSION: This study demonstrates that amyloid lesions in transgenic mice are highly stable structures in vivo that are slow to disaggregate. Our findings suggest that arresting Abeta production in patients with Alzheimer disease should halt the progression of pathology, but that early treatment may be imperative, as it appears that amyloid deposits, once formed, will require additional intervention to clear.

  7. The levels of soluble versus insoluble brain Abeta distinguish Alzheimer's disease from normal and pathologic aging.

    Science.gov (United States)

    Wang, J; Dickson, D W; Trojanowski, J Q; Lee, V M

    1999-08-01

    The abundance and solubility of Abeta peptides are critical determinants of amyloidosis in Alzheimer's disease (AD). Hence, we compared levels of total soluble, insoluble, and total Abeta1-40 and Abeta1-42 in AD brains with those in age-matched normal and pathologic aging brains using a sandwich enzyme-linked immunosorbent assay (ELISA). Since the measurement of Abeta1-40 and Abeta1-42 depends critically on the specificity of the monoclonal antibodies used in the sandwich ELISA, we first demonstrated that each assay is specific for Abeta1-40 or Abeta1-42 and the levels of these peptides are not affected by the amyloid precursor protein in the brain extracts. Thus, this sandwich ELISA enabled us to show that the average levels of total cortical soluble and insoluble Abeta1-40 and Abeta1-42 were highest in AD, lowest in normal aging, and intermediate in pathologic aging. Remarkably, the average levels of insoluble Abeta1-40 were increased 20-fold while the average levels of insoluble Abeta1-42 were increased only 2-fold in the AD brains compared to pathologic aging brains. Further, the soluble pools of Abeta1-40 and Abeta1-42 were the largest fractions of total Abeta in the normal brain (i.e., 50 and 23%, respectively), but they were the smallest in the AD brain (i.e., 2.7 and 0.7%, respectively) and intermediate (i.e., 8 and 0.8%, respectively) in pathologic aging brains. Thus, our data suggest that pathologic aging is a transition state between normal aging and AD. More importantly, our findings imply that a progressive shift of brain Abeta1-40 and Abeta1-42 from soluble to insoluble pools and a profound increase in the levels of insoluble Abeta1-40 plays mechanistic roles in the onset and/or progression of AD.

  8. P-glycoprotein efflux and other factors limit brain amyloid beta reduction by beta-site amyloid precursor protein-cleaving enzyme 1 inhibitors in mice.

    Science.gov (United States)

    Meredith, Jere E; Thompson, Lorin A; Toyn, Jeremy H; Marcin, Lawrence; Barten, Donna M; Marcinkeviciene, Jovita; Kopcho, Lisa; Kim, Young; Lin, Alan; Guss, Valerie; Burton, Catherine; Iben, Lawrence; Polson, Craig; Cantone, Joe; Ford, Michael; Drexler, Dieter; Fiedler, Tracey; Lentz, Kimberley A; Grace, James E; Kolb, Janet; Corsa, Jason; Pierdomenico, Maria; Jones, Kelli; Olson, Richard E; Macor, John E; Albright, Charles F

    2008-08-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disease. Amyloid beta (Abeta) peptides are hypothesized to cause the initiation and progression of AD based on pathologic data from AD patients, genetic analysis of mutations that cause early onset forms of AD, and preclinical studies. Based on this hypothesis, beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) inhibitors are an attractive therapeutic approach for AD because cleavage of the APP by BACE1 is required to form Abeta. In this study, three potent BACE1 inhibitors are characterized. All three inhibitors decrease Abeta formation in cultured cells with IC(50) values less than 10 nM. Analysis of APP C-terminal fragments by immunoblotting and Abeta peptides by mass spectrometry showed that these inhibitors decreased Abeta by inhibiting BACE1. An assay for Abeta1-40 in mice was developed and used to show that these BACE1 inhibitors decreased plasma Abeta1-40, but not brain Abeta1-40, in wild-type mice. Because these BACE1 inhibitors were substrates for P-glycoprotein (P-gp), a member of the ATP-binding cassette superfamily of efflux transporters, these inhibitors were administered to P-gp knockout (KO) mice. These studies showed that all three BACE1 inhibitors decreased brain Abeta1-40 in P-gp KO mice, demonstrating that P-gp is a major limitation for development of BACE1 inhibitors to test the amyloid hypothesis. A comparison of plasma Abeta1-40 and brain Abeta1-40 dose responses for these three compounds revealed differences in relative ED(50) values, indicating that factors other than P-gp can also contribute to poor brain activity by BACE1 inhibitors.

  9. Antibodies targeted to the brain with image-guided focused ultrasound reduces amyloid-beta plaque load in the TgCRND8 mouse model of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Jessica F Jordão

    Full Text Available Immunotherapy for Alzheimer's disease (AD relies on antibodies directed against toxic amyloid-beta peptide (Abeta, which circulate in the bloodstream and remove Abeta from the brain. In mouse models of AD, the administration of anti-Abeta antibodies directly into the brain, in comparison to the bloodstream, was shown to be more efficient at reducing Abeta plaque pathology. Therefore, delivering anti-Abeta antibodies to the brain of AD patients may also improve treatment efficiency. Transcranial focused ultrasound (FUS is known to transiently-enhance the permeability of the blood-brain barrier (BBB, allowing intravenously administered therapeutics to enter the brain. Our goal was to establish that anti-Abeta antibodies delivered to the brain using magnetic resonance imaging-guided FUS (MRIgFUS can reduce plaque pathology. To test this, TgCRND8 mice received intravenous injections of MRI and FUS contrast agents, as well as anti-Abeta antibody, BAM-10. MRIgFUS was then applied transcranially. Within minutes, the MRI contrast agent entered the brain, and BAM-10 was later found bound to Abeta plaques in targeted cortical areas. Four days post-treatment, Abeta pathology was significantly reduced in TgCRND8 mice. In conclusion, this is the first report to demonstrate that MRIgFUS delivery of anti-Abeta antibodies provides the combined advantages of using a low dose of antibody and rapidly reducing plaque pathology.

  10. Anti-Abeta: The good, the bad, and the unforeseen.

    Science.gov (United States)

    Broytman, Oleg; Malter, James S

    2004-02-01

    Alzheimer's disease (AD) is characterized in part by the deposition of amyloid beta protein (Abeta) in compact fibrillar plaques. These structures can induce an innate immune response in the brain, which triggers progressive inflammation, neuronal loss, and further acceleration of Abeta plaque formation. Compared with the case in normal individuals, the T and B lymphocytes in AD patients and murine models are hyporesponsive to Abeta. However, depending on the route of delivery, tolerance can be overcome by vaccination, with the induction of an anti-Abeta-mediated immune response. Through mechanisms that are incompletely understood, immunized APP transgenic animals show markedly reduced Abeta deposition, preservation of normal neuronal architecture, and improved performance in memory and spatial learning tasks. In human trials, Abeta vaccination stabilized cognition and slowed the progression of dementia. Neuropathologic examination of a vaccinated subject showed reduced cortical Abeta without changes in other AD-associated pathology. However, in some patients, vaccination induced severe meningoencephalitis, causing the trial to be terminated. Thus, vaccination appears to activate both beneficial and deleterious anti-Abeta immunity, suggesting that the vaccine can have potent clinical utility if an appropriate immunologic response can be generated.

  11. Polyalanine and Abeta Aggregation Kinetics: Probing Intermediate Oligomer Formation and Structure Using Computer Simulations

    Science.gov (United States)

    Phelps, Erin Melissa

    2011-12-01

    The aggregation of proteins into stable, well-ordered structures known as amyloid fibrils has been associated with many neurodegenerative diseases. Amyloid fibrils are long straight, and un-branched structures containing several proto-filaments, each of which exhibits "cross beta structure," -- ribbon-like layers of large beta sheets whose strands run perpendicular to the fibril axis. It has been suggested in the literature that the pathway to fibril formation has the following steps: unfolded monomers associate into transient unstable oligomers, the oligomers undergo a rearrangement into the cross-beta structure and form into proto-filaments, these proto-filaments then associate and grow into fully formed fibrils. Recent experimental studies have determined that the unstable intermediate structures are toxic to cells and that their presence may play a key role in the pathogenesis of the amyloid diseases. Many efforts have been made to determine the structure of intermediate oligomer aggregates that form during the fibrillization process. The goal of this work is to provide details about the structure and formation kinetics of the unstable oligomers that appear in the fibril formation pathway. The specific aims of this work are to determine the steps in the fibril formation pathway and how the kinetics of fibrillization changes with variations in temperature and concentration. The method used is the application of discontinuous molecular dynamics to large systems of peptides represented with an intermediate resolution model, PRIME, that was previously developed in our group. Three different peptide sequences are simulated: polyalanine (KA14K), Abeta17-40, and Abeta17-42; the latter two are truncated sequences of the Alzheimer's peptide. We simulate the spontaneous assembly of these peptide chains from a random initial configuration of random coils. We investigate aggregation kinetics and oligomer formation of a system of 192 polyalanine (KA14K) chains over a

  12. Amyloid Beta-peptide (25-35) changes (Ca2+) in hippocampal neurons

    DEFF Research Database (Denmark)

    Mogensen, Helle Smidt; Beatty, Diane; Morris, Stephen;

    1998-01-01

    neuroscience, Alzheimer, calcium ion, hippocampal neurons, amyloid-beta-peptide, hydrogen ion, rat......neuroscience, Alzheimer, calcium ion, hippocampal neurons, amyloid-beta-peptide, hydrogen ion, rat...

  13. Method for measurement of the blood-brain barrier permeability in the perfused mouse brain: application to amyloid-beta peptide in wild type and Alzheimer's Tg2576 mice.

    Science.gov (United States)

    LaRue, Barbra; Hogg, Elizabeth; Sagare, Abhay; Jovanovic, Suzana; Maness, Lawrence; Maurer, Calvin; Deane, Rashid; Zlokovic, Berislav V

    2004-09-30

    The role of transport exchanges of neuroactive solutes across the blood-brain barrier (BBB) is increasingly recognized. To take full advantage of genetically altered mouse models of neurodegenerative disorders for BBB transport studies, we adapted a brain perfusion technique to the mouse. During a carotid brain perfusion with a medium containing sheep red blood cells and mock plasma, the physiological parameters in the arterial inflow, regional cerebral blood flow (14C-iodoantipyrine autoradiography), ultrastructural integrity of the tissue, barrier to lanthanum, brain water content, energy metabolites and lactate levels remain unchanged. Amyloid-beta peptides (Abeta) were iodinated by lactoperoxidase method. Non-oxidized mono-iodinated Abeta monomers were separated by HPLC (as confirmed by MALDI-TOF spectrometry) and used in transport measurements. Transport of intact 125I-Abeta40 across the BBB was time- and concentration-dependent in contrast to negligible 14C-inulin uptake. In 5-6 months old Alzheimer's Tg2576 mice, Abeta40 BBB transport was increased by >eight-fold compared to age-matched littermate controls, and was mediated via the receptor for advanced glycation endproducts. We conclude the present arterial brain perfusion method provides strictly controlled environment in cerebral microcirculation suitable for examining transport of rapidly and slowly penetrating molecules across the BBB in normal and transgenic mice.

  14. Tau/Amyloid Beta 42 Peptide Test (Alzheimer Biomarkers)

    Science.gov (United States)

    ... helpful? Also known as: Alzheimer Biomarkers Formal name: Tau Protein and Amyloid Beta 42 Peptide Related tests: Phosporylated ... should know? How is it used? Tests for Tau protein and Aß42 may be used as supplemental tests ...

  15. Enhanced clearance of Abeta in brain by sustaining the plasmin proteolysis cascade.

    Science.gov (United States)

    Jacobsen, J Steven; Comery, Thomas A; Martone, Robert L; Elokdah, Hassan; Crandall, David L; Oganesian, Aram; Aschmies, Suzan; Kirksey, Yolanda; Gonzales, Cathleen; Xu, Jane; Zhou, Hua; Atchison, Kevin; Wagner, Erik; Zaleska, Margaret M; Das, Indranil; Arias, Robert L; Bard, Jonathan; Riddell, David; Gardell, Stephen J; Abou-Gharbia, Magid; Robichaud, Albert; Magolda, Ronald; Vlasuk, George P; Bjornsson, Thorir; Reinhart, Peter H; Pangalos, Menelas N

    2008-06-24

    The amyloid hypothesis states that a variety of neurotoxic beta-amyloid (Abeta) species contribute to the pathogenesis of Alzheimer's disease. Accordingly, a key determinant of disease onset and progression is the appropriate balance between Abeta production and clearance. Enzymes responsible for the degradation of Abeta are not well understood, and, thus far, it has not been possible to enhance Abeta catabolism by pharmacological manipulation. We provide evidence that Abeta catabolism is increased after inhibition of plasminogen activator inhibitor-1 (PAI-1) and may constitute a viable therapeutic approach for lowering brain Abeta levels. PAI-1 inhibits the activity of tissue plasminogen activator (tPA), an enzyme that cleaves plasminogen to generate plasmin, a protease that degrades Abeta oligomers and monomers. Because tPA, plasminogen and PAI-1 are expressed in the brain, we tested the hypothesis that inhibitors of PAI-1 will enhance the proteolytic clearance of brain Abeta. Our data demonstrate that PAI-1 inhibitors augment the activity of tPA and plasmin in hippocampus, significantly lower plasma and brain Abeta levels, restore long-term potentiation deficits in hippocampal slices from transgenic Abeta-producing mice, and reverse cognitive deficits in these mice.

  16. Alzheimer's-associated Abeta oligomers show altered structure, immunoreactivity and synaptotoxicity with low doses of oleocanthal.

    Science.gov (United States)

    Pitt, Jason; Roth, William; Lacor, Pascale; Smith, Amos B; Blankenship, Matthew; Velasco, Pauline; De Felice, Fernanda; Breslin, Paul; Klein, William L

    2009-10-15

    It now appears likely that soluble oligomers of amyloid-beta1-42 peptide, rather than insoluble fibrils, act as the primary neurotoxin in Alzheimer's disease (AD). Consequently, compounds capable of altering the assembly state of these oligomers (referred to as ADDLs) may have potential for AD therapeutics. Phenolic compounds are of particular interest for their ability to disrupt Abeta oligomerization and reduce pathogenicity. This study has focused on oleocanthal (OC), a naturally-occurring phenolic compound found in extra-virgin olive oil. OC increased the immunoreactivity of soluble Abeta species, when assayed with both sequence- and conformation-specific Abeta antibodies, indicating changes in oligomer structure. Analysis of oligomers in the presence of OC showed an upward shift in MW and a ladder-like distribution of SDS-stable ADDL subspecies. In comparison with control ADDLs, oligomers formed in the presence of OC (Abeta-OC) showed equivalent colocalization at synapses but exhibited greater immunofluorescence as a result of increased antibody recognition. The enhanced signal at synapses was not due to increased synaptic binding, as direct detection of fluorescently-labeled ADDLs showed an overall reduction in ADDL signal in the presence of OC. Decreased binding to synapses was accompanied by significantly less synaptic deterioration assayed by drebrin loss. Additionally, treatment with OC improved antibody clearance of ADDLs. These results indicate oleocanthal is capable of altering the oligomerization state of ADDLs while protecting neurons from the synaptopathological effects of ADDLs and suggest OC as a lead compound for development in AD therapeutics. PMID:19631677

  17. Abeta mediated diminution of MTT reduction--an artefact of single cell culture?

    Directory of Open Access Journals (Sweden)

    Raik Rönicke

    Full Text Available The 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl-tetrazoliumbromide (MTT reduction assay is a frequently used and easily reproducible method to measure beta-amyloid (Abeta toxicity in different types of single cell culture. To our knowledge, the influence of Abeta on MTT reduction has never been tested in more complex tissue. Initially, we reproduced the disturbed MTT reduction in neuron and astroglia primary cell cultures from rats as well as in the BV2 microglia cell line, utilizing four different Abeta species, namely freshly dissolved Abeta (25-35, fibrillar Abeta (1-40, oligomeric Abeta (1-42 and oligomeric Abeta (1-40. In contrast to the findings in single cell cultures, none of these Abeta species altered MTT reduction in rat organotypic hippocampal slice cultures (OHC. Moreover, application of Abeta to acutely isolated hippocampal slices from adult rats and in vivo intracerebroventricular injection of Abeta also did not influence the MTT reduction in the respective tissue. Failure of Abeta penetration into the tissue cannot explain the differences between single cells and the more complex brain tissue. Thus electrophysiological investigations disclosed an impairment of long-term potentiation (LTP in the CA1 region of hippocampal slices from rat by application of oligomeric Abeta (1-40, but not by freshly dissolved Abeta (25-35 or fibrillar Abeta (1-40. In conclusion, the experiments revealed a glaring discrepancy between single cell cultures and complex brain tissue regarding the effect of different Abeta species on MTT reduction. Particularly, the differential effect of oligomeric versus other Abeta forms on LTP was not reflected in the MTT reduction assay. This may indicate that the Abeta oligomer effect on synaptic function reflected by LTP impairment precedes changes in formazane formation rate or that cells embedded in a more natural environment in the tissue are less susceptible to damage by Abeta, raising cautions against the

  18. Activation of PERK signaling attenuates Abeta-mediated ER stress.

    Directory of Open Access Journals (Sweden)

    Do Yeon Lee

    Full Text Available Alzheimer's disease (AD is characterized by the deposition of aggregated beta-amyloid (Abeta, which triggers a cellular stress response called the unfolded protein response (UPR. The UPR signaling pathway is a cellular defense system for dealing with the accumulation of misfolded proteins but switches to apoptosis when endoplasmic reticulum (ER stress is prolonged. ER stress is involved in neurodegenerative diseases including AD, but the molecular mechanisms of ER stress-mediated Abeta neurotoxicity still remain unknown. Here, we show that treatment of Abeta triggers the UPR in the SK-N-SH human neuroblastoma cells. Abeta mediated UPR pathway accompanies the activation of protective pathways such as Grp78/Bip and PERK-eIF2alpha pathway, as well as the apoptotic pathways of the UPR such as CHOP and caspase-4. Knockdown of PERK enhances Abeta neurotoxicity through reducing the activation of eIF2alpha and Grp8/Bip in neurons. Salubrinal, an activator of the eIF2alpha pathway, significantly increased the Grp78/Bip ER chaperone resulted in attenuating caspase-4 dependent apoptosis in Abeta treated neurons. These results indicate that PERK-eIF2alpha pathway is a potential target for therapeutic applications in neurodegenerative diseases including AD.

  19. CD147 is a regulatory subunit of the gamma-secretase complex inAlzheimer's disease amyloid beta-peptide production

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shuxia; Zhou, Hua; Walian, Peter J.; Jap, Bing K.

    2005-04-06

    {gamma}-secretase is a membrane protein complex that cleaves the {beta}-amyloid precursor protein (APP) within the transmembrane region, following prior processing by {beta}-secretase, producing amyloid {beta}-peptides (A{beta}{sub 40} and A{beta}{sub 42}). Errant production of A{beta}-peptides that substantially increases A{beta}{sub 42} production has been associated with the formation of amyloid plaques in Alzheimer's disease patients. Biophysical and genetic studies indicate that presenilin-1 (Psn-1), which contains the proteolytic active site, and three other membrane proteins, nicastrin (Nct), APH-1, and PEN-2 are required to form the core of the active {gamma}-secretase complex. Here, we report the purification of the native {gamma}-secretase complexes from HeLa cell membranes and the identification of an additional {gamma}-secretase complex subunit, CD147, a transmembrane glycoprotein with two immunoglobulin-like domains. The presence of this subunit as an integral part of the complex itself was confirmed through co-immunoprecipitation studies of the purified protein from HeLa cells and solubilized complexes from other cell lines such as neural cell HCN-1A and HEK293. Depletion of CD147 by RNA interference was found to increase the production of A{beta} peptides without changing the expression level of the other {gamma}-secretase components or APP substrates while CD147 overexpression had no statistically significant effect on amyloid {beta}-peptide production, other {gamma}-secretase components or APP substrates, indicating that the presence of the CD147 subunit within the {gamma}-secretase complex directly down-modulates the production of A{beta}-peptides. {gamma}-secretase was first recognized through its role in the production of the A{beta} peptides that are pathogenic in Alzheimer's disease (AD) (1). {gamma}-secretase is a membrane protein complex with unusual aspartyl protease activity that cleaves a variety of type I membrane proteins

  20. The structure of Abeta42 C-terminal fragments probed by a combined experimental and theoretical study.

    Science.gov (United States)

    Wu, Chun; Murray, Megan M; Bernstein, Summer L; Condron, Margaret M; Bitan, Gal; Shea, Joan-Emma; Bowers, Michael T

    2009-03-27

    The C-terminus of amyloid beta-protein (Abeta) 42 plays an important role in this protein's oligomerization and may therefore be a good therapeutic target for the treatment of Alzheimer's disease. Certain C-terminal fragments (CTFs) of Abeta42 have been shown to disrupt oligomerization and to strongly inhibit Abeta42-induced neurotoxicity. Here we study the structures of selected CTFs [Abeta(x-42); x=29-31, 39] using replica exchange molecular dynamics simulations and ion mobility mass spectrometry. Our simulations in explicit solvent reveal that the CTFs adopt a metastable beta-structure: beta-hairpin for Abeta(x-42) (x=29-31) and extended beta-strand for Abeta(39-42). The beta-hairpin of Abeta(30-42) is converted into a turn-coil conformation when the last two hydrophobic residues are removed, suggesting that I41 and A42 are critical in stabilizing the beta-hairpin in Abeta42-derived CTFs. The importance of solvent in determining the structure of the CTFs is further highlighted in ion mobility mass spectrometry experiments and solvent-free replica exchange molecular dynamics simulations. A comparison between structures with solvent and structures without solvent reveals that hydrophobic interactions are critical for the formation of beta-hairpin. The possible role played by the CTFs in disrupting oligomerization is discussed.

  1. Mitochondrial mislocalization underlies Abeta42-induced neuronal dysfunction in a Drosophila model of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Kanae Iijima-Ando

    Full Text Available The amyloid-beta 42 (Abeta42 is thought to play a central role in the pathogenesis of Alzheimer's disease (AD. However, the molecular mechanisms by which Abeta42 induces neuronal dysfunction and degeneration remain elusive. Mitochondrial dysfunctions are implicated in AD brains. Whether mitochondrial dysfunctions are merely a consequence of AD pathology, or are early seminal events in AD pathogenesis remains to be determined. Here, we show that Abeta42 induces mitochondrial mislocalization, which contributes to Abeta42-induced neuronal dysfunction in a transgenic Drosophila model. In the Abeta42 fly brain, mitochondria were reduced in axons and dendrites, and accumulated in the somata without severe mitochondrial damage or neurodegeneration. In contrast, organization of microtubule or global axonal transport was not significantly altered at this stage. Abeta42-induced behavioral defects were exacerbated by genetic reductions in mitochondrial transport, and were modulated by cAMP levels and PKA activity. Levels of putative PKA substrate phosphoproteins were reduced in the Abeta42 fly brains. Importantly, perturbations in mitochondrial transport in neurons were sufficient to disrupt PKA signaling and induce late-onset behavioral deficits, suggesting a mechanism whereby mitochondrial mislocalization contributes to Abeta42-induced neuronal dysfunction. These results demonstrate that mislocalization of mitochondria underlies the pathogenic effects of Abeta42 in vivo.

  2. Plasma amyloid beta peptides and oligomers antibodies in Alzheimer's disease

    OpenAIRE

    Zhou, L.; Chu, LW; Kwan, JSC; Ho, JWM; Lam, KSL; Ho, PWL; Chan, KH

    2011-01-01

    INTRODUCTION: Various forms of amyloid beta (Aβ) including Aβ peptides, oligomers, protofibrils and fibrils are thought to be pathogenic in Alzheimer’s disease (AD). The exact pathophysiological role of endogenous Aβ autoantibodies (Ab) in healthy subjects and AD patients are uncertain. Potential protective role ...

  3. Brain beta-amyloid accumulation in transgenic mice expressing mutant superoxide dismutase 1.

    Science.gov (United States)

    Turner, Bradley J; Li, Qiao-Xin; Laughton, Katrina M; Masters, Colin L; Lopes, Elizabeth C; Atkin, Julie D; Cheema, Surindar S

    2004-12-01

    Oxidative stress is implicated in both the deposition and pathogenesis of beta-amyloid (Abeta) protein in Alzheimer's disease (AD). Accordingly, overexpression of the antioxidant enzyme superoxide dismutase 1 (SOD1) in neuronal cells and transgenic AD mice reduces Abeta toxicity and accumulation. In contrast, mutations in SOD1 associated with amyotrophic lateral sclerosis (ALS) confer enhanced pro-oxidative enzyme activities. We therefore examined whether ALS-linked mutant SOD1 overexpression in motor neuronal cells or transgenic ALS mice modulates Abeta toxicity or its accumulation in the brain. Aggregated, but not freshly solubilised, substrate-bound Abeta peptides induced degenerative morphology and cytotoxicity in motor neuron-like NSC-34 cells. Transfection of NSC-34 cells with human wild-type SOD1 attenuated Abeta-induced toxicity, however this neuroprotective effect was also observed for ALS-linked mutant SOD1. Analysis of the cerebral cortex, brainstem, cerebellum and olfactory bulb from transgenic SOD1G93A mice using enzyme-linked immunosorbent assay of acid-guanidine extracts revealed age-dependent elevations in Abeta levels, although not significantly different from wild-type mouse brain. In addition, brain amyloid protein precursor (APP) levels remained unaltered as a consequence of mutant SOD1 expression. We therefore conclude that mutant SOD1 overexpression promotes neither Abeta toxicity nor brain accumulation in these ALS models.

  4. Cu K-edge X-ray Absorption Spectroscopy Reveals Differential Copper Coordimation Within Amyloid-beta Oligomers Compared to Amyloid-beta Monomers

    Energy Technology Data Exchange (ETDEWEB)

    J Shearer; P Callan; T Tran; V Szalai

    2011-12-31

    The fatal neurodegenerative disorder Alzheimer's disease (AD) has been linked to the formation of soluble neurotoxic oligomers of amyloid-{beta} (A{beta}) peptides. These peptides have high affinities for copper cations. Despite their potential importance in AD neurodegeneration few studies have focused on probing the Cu{sup 2+/1+} coordination environment within A{beta} oligomers. Herein we present a Cu K-edge X-ray absorption spectroscopic study probing the copper-coordination environment within oligomers of A{beta}(42) (sequence: DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA). We find that the Cu{sup 2+} cation is contained within a square planar mixed N/O ligand environment within A{beta}(42) oligomers, which is similar to the copper coordination environment of the monomeric forms of {l_brace}Cu{sup II}A{beta}(40){r_brace} and {l_brace}Cu{sup II}A{beta}(16){r_brace}. Reduction of the Cu{sup 2+} cation within the A{beta}(42) oligomers to Cu{sup 1+} yields a highly dioxygen sensitive copper-species that contains Cu{sup 1+} in a tetrahedral coordination geometry. This can be contrasted with monomers of {l_brace}Cu{sup I}A{beta}(40){r_brace} and {l_brace}Cu{sup I}A{beta}(16){r_brace}, which contain copper in a dioxygen inert linear bis-histidine ligand environment [Shearer and Szalai, J. Am. Chem. Soc., 2008, 130, 17826]. The biological implications of these findings are discussed.

  5. Solid-state NMR analysis of the {beta}-strand orientation of the protofibrils of amyloid {beta}-protein

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Takashi [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Masuda, Yuichi, E-mail: masuda@mail.pharm.tohoku.ac.jp [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578 (Japan); Irie, Kazuhiro [Graduate School of Agriculture, Kyoto University, Kyoto 606-8502 (Japan); Akagi, Ken-ichi; Monobe, Youko; Imazawa, Takayoshi [Section of Laboratory Equipment, Division of Biomedical Research, National Institute of Biomedical Innovation, Osaka 567-0085 (Japan); Takegoshi, K. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer The supramolecular structure of A{beta}42 protofibrils was analyzed by solid-state NMR. Black-Right-Pointing-Pointer The Ala-21 residue in the A{beta}42 protofibrils is included in a slightly disordered {beta}-strand. Black-Right-Pointing-Pointer The A{beta}42 protofibrils do not form intermolecular in-register parallel {beta}-sheets. -- Abstract: Alzheimer's disease (AD) is caused by abnormal deposition (fibrillation) of a 42-residue amyloid {beta}-protein (A{beta}42) in the brain. During the process of fibrillation, the A{beta}42 takes the form of protofibrils with strong neurotoxicity, and is thus believed to play a crucial role in the pathogenesis of AD. To elucidate the supramolecular structure of the A{beta}42 protofibrils, the intermolecular proximity of the Ala-21 residues in the A{beta}42 protofibrils was analyzed by {sup 13}C-{sup 13}C rotational resonance experiments in the solid state. Unlike the A{beta}42 fibrils, an intermolecular {sup 13}C-{sup 13}C correlation was not found in the A{beta}42 protofibrils. This result suggests that the {beta}-strands of the A{beta}42 protofibrils are not in an in-register parallel orientation. A{beta}42 monomers would assemble to form protofibrils with the {beta}-strand conformation, then transform into fibrils by forming intermolecular parallel {beta}-sheets.

  6. The novel amyloid-beta peptide aptamer inhibits intracellular amyloid-beta peptide toxicity

    Institute of Scientific and Technical Information of China (English)

    Xu Wang; Yi Yang; Mingyue Jia; Chi Ma; Mingyu Wang; Lihe Che; Yu Yang; Jiang Wu

    2013-01-01

    Amyloid β peptide binding alcohol dehydrogenase (ABAD) decoy peptide (DP) can competitively antagonize binding of amyloid β peptide to ABAD and inhibit the cytotoxic effects of amyloid β peptide. Based on peptide aptamers, the present study inserted ABAD-DP into the disulfide bond of human thioredoxin (TRX) using molecular cloning technique to construct a fusion gene that can express the TRX1-ABAD-DP-TRX2 aptamer. Moreover, adeno-associated virus was used to allow its stable expression. Immunofluorescent staining revealed the co-expression of the transduced fusion gene TRX1-ABAD-DP-TRX2 and amyloid β peptide in NIH-3T3 cells, indicating that the TRX1-ABAD-DP-TRX2 aptamer can bind amyloid β peptide within cells. In addition, cell morphology and MTT results suggested that TRX1-ABAD-DP-TRX2 attenuated amyloid β peptide-induced SH-SY5Y cell injury and improved cell viability. These findings confirmed the possibility of constructing TRX-based peptide aptamer using ABAD-DP. Moreover, TRX1-ABAD-DP-TRX2 inhibited the cytotoxic effect of amyloid β peptide.

  7. Inhibition of aggregation of amyloid peptides by beta-sheet breaker peptides and their binding affinity.

    Science.gov (United States)

    Viet, Man Hoang; Ngo, Son Tung; Lam, Nguyen Sy; Li, Mai Suan

    2011-06-01

    The effects of beta-sheet breaker peptides KLVFF and LPFFD on the oligomerization of amyloid peptides were studied by all-atom simulations. It was found that LPFFD interferes the aggregation of Aβ(16-22) peptides to a greater extent than does KLVFF. Using the molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) method, we found that the former binds more strongly to Aβ(16-22). Therefore, by simulations, we have clarified the relationship between aggregation rates and binding affinity: the stronger the ligand binding, the slower the oligomerization process. The binding affinity of pentapeptides to full-length peptide Aβ(1-40) and its mature fibrils has been considered using the Autodock and MM-PBSA methods. The hydrophobic interaction between ligands and receptors plays a more important role for association than does hydrogen bonding. The influence of beta-sheet breaker peptides on the secondary structures of monomer Aβ(1-40) was studied in detail, and it turns out that, in their presence, the total beta-sheet content can be enhanced. However, the aggregation can be slowed because the beta-content is reduced in fibril-prone regions. Both pentapeptides strongly bind to monomer Aβ(1-40), as well as to mature fibrils, but KLVFF displays a lower binding affinity than LPFFD. Our findings are in accord with earlier experiments that both of these peptides can serve as prominent inhibitors. In addition, we predict that LPFFD inhibits/degrades the fibrillogenesis of full-length amyloid peptides better than KLVFF. This is probably related to a difference in their total hydrophobicities in that the higher the hydrophobicity, the lower the inhibitory capacity. The GROMOS96 43a1 force field with explicit water and the force field proposed by Morris et al. (Morris et al. J. Comput. Chem. 1998, 19, 1639 ) were employed for all-atom molecular dynamics simulations and Autodock experiments, respectively. PMID:21563780

  8. Hydrogen peroxide is generated during the very early stages of aggregation of the amyloid peptides implicated in Alzheimer disease and familial British dementia.

    Science.gov (United States)

    Tabner, Brian J; El-Agnaf, Omar M A; Turnbull, Stuart; German, Matthew J; Paleologou, Katerina E; Hayashi, Yoshihito; Cooper, Leanne J; Fullwood, Nigel J; Allsop, David

    2005-10-28

    Alzheimer disease and familial British dementia are neurodegenerative diseases that are characterized by the presence of numerous amyloid plaques in the brain. These lesions contain fibrillar deposits of the beta-amyloid peptide (Abeta) and the British dementia peptide (ABri), respectively. Both peptides are toxic to cells in culture, and there is increasing evidence that early "soluble oligomers" are the toxic entity rather than mature amyloid fibrils. The molecular mechanisms responsible for this toxicity are not clear, but in the case of Abeta, one prominent hypothesis is that the peptide can induce oxidative damage via the formation of hydrogen peroxide. We have developed a reliable method, employing electron spin resonance spectroscopy in conjunction with the spin-trapping technique, to detect any hydrogen peroxide generated during the incubation of Abeta and other amyloidogenic peptides. Here, we monitored levels of hydrogen peroxide accumulation during different stages of aggregation of Abeta-(1-40) and ABri and found that in both cases it was generated as a short "burst" early on in the aggregation process. Ultrastructural studies with both peptides revealed that structures resembling "soluble oligomers" or "protofibrils" were present during this early phase of hydrogen peroxide formation. Mature amyloid fibrils derived from Abeta-(1-40) did not generate hydrogen peroxide. We conclude that hydrogen peroxide formation during the early stages of protein aggregation may be a common mechanism of cell death in these (and possibly other) neurodegenerative diseases.

  9. Alzheimer's disease amyloid-beta links lens and brain pathology in Down syndrome.

    Directory of Open Access Journals (Sweden)

    Juliet A Moncaster

    Full Text Available Down syndrome (DS, trisomy 21 is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21 encoding the Alzheimer's disease (AD amyloid precursor protein (APP. Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-beta peptides (Abeta, early-onset AD neuropathology, and age-dependent cognitive sequelae. The DS phenotype complex also includes distinctive early-onset cerulean cataracts of unknown etiology. Previously, we reported increased Abeta accumulation, co-localizing amyloid pathology, and disease-linked supranuclear cataracts in the ocular lenses of subjects with AD. Here, we investigate the hypothesis that related AD-linked Abeta pathology underlies the distinctive lens phenotype associated with DS. Ophthalmological examinations of DS subjects were correlated with phenotypic, histochemical, and biochemical analyses of lenses obtained from DS, AD, and normal control subjects. Evaluation of DS lenses revealed a characteristic pattern of supranuclear opacification accompanied by accelerated supranuclear Abeta accumulation, co-localizing amyloid pathology, and fiber cell cytoplasmic Abeta aggregates (approximately 5 to 50 nm identical to the lens pathology identified in AD. Peptide sequencing, immunoblot analysis, and ELISA confirmed the identity and increased accumulation of Abeta in DS lenses. Incubation of synthetic Abeta with human lens protein promoted protein aggregation, amyloid formation, and light scattering that recapitulated the molecular pathology and clinical features observed in DS lenses. These results establish the genetic etiology of the distinctive lens phenotype in DS and identify the molecular origin and pathogenic mechanism by which lens pathology is expressed in this common chromosomal disorder. Moreover, these findings confirm increased Abeta

  10. A comparative analysis of the aggregation behavior of amyloid-beta peptide variants

    NARCIS (Netherlands)

    Vandersteen, A.; Hubin, E.; Sarroukh, R.; Baets, G. de; Schymkowitz, J.; Rousseau, F.; Subramaniam, V.; Raussens, V.; Wenschuh, H.; Wildemann, D.; Broersen, K.

    2012-01-01

    Aggregated forms of the amyloid-beta peptide are hypothesized to act as the prime toxic agents in Alzheimer disease (AD). The in vivo amyloid-beta peptide pool consists of both C- and N-terminally truncated or mutated peptides, and the composition thereof significantly determines AD risk. Other vari

  11. Peripheral elevation of IGF-1 fails to alter Abeta clearance in multiple in vivo models.

    Science.gov (United States)

    Lanz, Thomas A; Salatto, Christopher T; Semproni, Anthony R; Marconi, Michael; Brown, Tracy M; Richter, Karl E G; Schmidt, Kari; Nelson, Frederick R; Schachter, Joel B

    2008-03-01

    Increasing beta-amyloid (Abeta) clearance may alter the course of Alzheimer's disease progression and attenuate amyloid plaque pathology. Insulin-like growth factor I (IGF-1) augmentation has been suggested to increase Abeta clearance by facilitating transport of Abeta out of the brain. The availability of safe agents that increase IGF-1 levels therefore makes IGF-1 elevation an attractive target for disease modifying therapy in AD. The present series of studies sought to replicate published paradigms in which peripheral IGF-1 administration lowered brain Abeta acutely, with reduction in plaque pathology after chronic treatment. Thus Abeta levels were measured in several animal models following treatments that elevated IGF-1. Administration of IGF-1 to young or old rats for up to 3 days had no effect on Abeta levels in brain, CSF, or plasma. In adult beagles, 4 days of dosing with the growth hormone secretagogue, CP-424391, doubled baseline plasma IGF-1 levels, yet failed to alter CSF or plasma Abeta. 5-day treatment of young Tg2576 mice with IGF-1 produced robust elevations of IGF-1 levels in plasma, but no effects on Abeta were detected in brain, CSF, or plasma. Finally, 11-month-old Tg2576 mice were implanted with subcutaneous minipumps delivering IGF-1 for 1 month. No significant changes in Abeta (by ELISA or Western blot), plaque pathology, or phospho-tau epitopes were detected. These results do not demonstrate acute or chronic actions of peripherally administered IGF-1 on Abeta levels or the phosphorylation state of tau and therefore do not suggest any disease-modifying benefits of IGF-1 restorative therapy for AD through these mechanisms.

  12. Inhibition of GSK-3 ameliorates Abeta pathology in an adult-onset Drosophila model of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Oyinkan Sofola

    2010-09-01

    Full Text Available Abeta peptide accumulation is thought to be the primary event in the pathogenesis of Alzheimer's disease (AD, with downstream neurotoxic effects including the hyperphosphorylation of tau protein. Glycogen synthase kinase-3 (GSK-3 is increasingly implicated as playing a pivotal role in this amyloid cascade. We have developed an adult-onset Drosophila model of AD, using an inducible gene expression system to express Arctic mutant Abeta42 specifically in adult neurons, to avoid developmental effects. Abeta42 accumulated with age in these flies and they displayed increased mortality together with progressive neuronal dysfunction, but in the apparent absence of neuronal loss. This fly model can thus be used to examine the role of events during adulthood and early AD aetiology. Expression of Abeta42 in adult neurons increased GSK-3 activity, and inhibition of GSK-3 (either genetically or pharmacologically by lithium treatment rescued Abeta42 toxicity. Abeta42 pathogenesis was also reduced by removal of endogenous fly tau; but, within the limits of detection of available methods, tau phosphorylation did not appear to be altered in flies expressing Abeta42. The GSK-3-mediated effects on Abeta42 toxicity appear to be at least in part mediated by tau-independent mechanisms, because the protective effect of lithium alone was greater than that of the removal of tau alone. Finally, Abeta42 levels were reduced upon GSK-3 inhibition, pointing to a direct role of GSK-3 in the regulation of Abeta42 peptide level, in the absence of APP processing. Our study points to the need both to identify the mechanisms by which GSK-3 modulates Abeta42 levels in the fly and to determine if similar mechanisms are present in mammals, and it supports the potential therapeutic use of GSK-3 inhibitors in AD.

  13. Structure and dynamics of parallel beta-sheets, hydrophobic core, and loops in Alzheimer's A beta fibrils.

    Science.gov (United States)

    Buchete, Nicolae-Viorel; Hummer, Gerhard

    2007-05-01

    We explore the relative contributions of different structural elements to the stability of Abeta fibrils by molecular-dynamics simulations performed over a broad range of temperatures (298 K to 398 K). Our fibril structures are based on solid-state nuclear magnetic resonance experiments of Abeta(1-40) peptides, with sheets of parallel beta-strands connected by loops and stabilized by interior salt bridges. We consider models with different interpeptide interfaces, and different staggering of the N- and C-terminal beta-strands along the fibril axis. Multiple 10-20 ns molecular-dynamics simulations show that fibril segments with 12 peptides are stable at ambient temperature. The different models converge toward an interdigitated side-chain packing, and present water channels solvating the interior D23/K28 salt bridges. At elevated temperatures, we observe the early phases of fibril dissociation as a loss of order in the hydrophilic loops connecting the two beta-strands, and in the solvent-exposed N-terminal beta-sheets. As the most dramatic structural change, we observe collective sliding of the N- and C-terminal beta-sheets on top of each other. The interior C-terminal beta-sheets in the hydrophobic core remain largely intact, indicating that their formation and stability is crucial to the dissociation/elongation and stability of Abeta fibrils. PMID:17293399

  14. Amyloid Beta Peptides Differentially Affect Hippocampal Theta Rhythms In Vitro

    Directory of Open Access Journals (Sweden)

    Armando I. Gutiérrez-Lerma

    2013-01-01

    Full Text Available Soluble amyloid beta peptide (Aβ is responsible for the early cognitive dysfunction observed in Alzheimer's disease. Both cholinergically and glutamatergically induced hippocampal theta rhythms are related to learning and memory, spatial navigation, and spatial memory. However, these two types of theta rhythms are not identical; they are associated with different behaviors and can be differentially modulated by diverse experimental conditions. Therefore, in this study, we aimed to investigate whether or not application of soluble Aβ alters the two types of theta frequency oscillatory network activity generated in rat hippocampal slices by application of the cholinergic and glutamatergic agonists carbachol or DHPG, respectively. Due to previous evidence that oscillatory activity can be differentially affected by different Aβ peptides, we also compared Aβ25−35 and Aβ1−42 for their effects on theta rhythms in vitro at similar concentrations (0.5 to 1.0 μM. We found that Aβ25−35 reduces, with less potency than Aβ1−42, carbachol-induced population theta oscillatory activity. In contrast, DHPG-induced oscillatory activity was not affected by a high concentration of Aβ25−35 but was reduced by Aβ1−42. Our results support the idea that different amyloid peptides might alter specific cellular mechanisms related to the generation of specific neuronal network activities, instead of exerting a generalized inhibitory effect on neuronal network function.

  15. Sex differences between APPswePS1dE9 mice in A-beta accumulation and pancreatic islet function during the development of Alzheimer's disease.

    Science.gov (United States)

    Li, Xin; Feng, Ying; Wu, Wei; Zhao, Jia; Fu, Chunmei; Li, Yang; Ding, Yangnan; Wu, Binghuo; Gong, Yanju; Yang, Guizhi; Zhou, Xue

    2016-08-01

    The pathogenesis of Alzheimer's disease (AD), a type of neurodegenerative disease characterized by learning and memory impairment, is often associated with pathological features, such as amyloid-beta (Aβ) accumulation and insulin resistance. The transgenic mouse, APPswePS1dE9 (APP/PS1), is one of the most commonly used animal models in pathogenesis studies of AD. The purpose of this study is to investigate the sex differences between APP/PS1 mice in the pathogenesis of AD. The impairment of glucose and insulin tolerance was found to develop earlier in male APP/PS1 mice than in females. Plasma insulin levels were significantly decreased in male APP/PS1 mice, while total cholesterol levels in male APP/PS1 mice were higher than those in females. Triglyceride levels in male mice in both the wild-type (WT) and APP/PS1 groups were higher than in their female littermates. Soluble and insoluble Aβ levels in female APP/PS1 mouse brains were higher than those in males. And the learning and memorizing abilities of female APP/PS1 mice were poorer than those of males. Our results concluded that there were sex differences in Aβ formation, pancreatic islet function and insulin sensitivity between male and female APP/PS1 mice during the pathogenesis of AD. PMID:26519428

  16. The conformations of the amyloid-beta (21-30) fragment can be described by three families in solution.

    Science.gov (United States)

    Chen, Wei; Mousseau, Normand; Derreumaux, Philippe

    2006-08-28

    Alzheimer's disease has been linked to the self-assembly of the amyloid-beta protein of 40 and 42 residues. Although monomers are in equilibrium with higher-order species ranging from dimers to heptamers, structural knowledge of the monomeric amyloid-beta (Abeta) peptides is an important issue. Recent experimental data have shown that the fragment (21-30) is protease-resistant within full-length Abeta peptides and displays two structural families in solution. Because the details of the Abeta(21-30) structures found using distinct force fields and protocols differ at various degrees from those of the NMR structures, we revisit the conformational space of this peptide using the activation-relaxation technique (ART nouveau) coupled with a coarse-grained force field (OPEP v.3.0). We find that although Abeta(21-30) does not have a secondary structure, it dominantly populates three structural families, with a loop spanning residues Val24-Lys28. The first two families, which differ in the nature of the electrostatic interactions, satisfy the five interproton rotating frame nuclear Overhauser effect spectroscopy (ROESY) distances and superpose well onto the NMR structures. The third family, which cannot be seen by ROESY NMR experiments, displays a more open structure. This numeric study complements the experimental results by providing a much more detailed description of the dominant structures. Moreover, it provides further evidence of the capability of ART OPEP in providing a reliable conformational picture of peptides in solution.

  17. Acetylcholinesterase, a senile plaque component, affects the fibrillogenesis of amyloid-beta-peptides.

    Science.gov (United States)

    Alvarez, A; Bronfman, F; Pérez, C A; Vicente, M; Garrido, J; Inestrosa, N C

    1995-12-01

    Acetylcholinesterase (AChE) colocalizes with amyloid-beta peptide (A beta) deposits present in the brain of Alzheimer's patients. Recent studies showed that A beta 1-40 can adopt two different conformational states in solution (an amyloidogenic conformer, A beta ac, and a non-amyloidogenic conformer, A beta nac) which have distinct abilities to form amyloid fibrils. We report here that AChE binds A beta nac and accelerates amyloid formation by the same peptide. No such effect was observed with A beta ac, the amyloidogenic conformer, suggesting that AChE acts as a 'pathological chaperone' inducing a conformational transition from A beta nac into A beta ac in vitro.

  18. PARP-1 modulates amyloid beta peptide-induced neuronal damage.

    Directory of Open Access Journals (Sweden)

    Sara Martire

    Full Text Available Amyloid beta peptide (Aβ causes neurodegeneration by several mechanisms including oxidative stress, which is known to induce DNA damage with the consequent activation of poly (ADP-ribose polymerase (PARP-1. To elucidate the role of PARP-1 in the neurodegenerative process, SH-SY5Y neuroblastoma cells were treated with Aβ25-35 fragment in the presence or absence of MC2050, a new PARP-1 inhibitor. Aβ25-35 induces an enhancement of PARP activity which is prevented by cell pre-treatment with MC2050. These data were confirmed by measuring PARP-1 activity in CHO cells transfected with amylod precursor protein and in vivo in brains specimens of TgCRND8 transgenic mice overproducing the amyloid peptide. Following Aβ25-35 exposure a significant increase in intracellular ROS was observed. These data were supported by the finding that Aβ25-35 induces DNA damage which in turn activates PARP-1. Challenge with Aβ25-35 is also able to activate NF-kB via PARP-1, as demonstrated by NF-kB impairment upon MC2050 treatment. Moreover, Aβ25-35 via PARP-1 induces a significant increase in the p53 protein level and a parallel decrease in the anti-apoptotic Bcl-2 protein. These overall data support the hypothesis of PARP-1 involvment in cellular responses induced by Aβ and hence a possible rationale for the implication of PARP-1 in neurodegeneration is discussed.

  19. Influence of the solvent on the self-assembly of a modified amyloid beta peptide fragment. II. NMR and computer simulation investigation.

    Science.gov (United States)

    Hamley, I W; Nutt, D R; Brown, G D; Miravet, J F; Escuder, B; Rodríguez-Llansola, F

    2010-01-21

    The conformation of a model peptide AAKLVFF based on a fragment of the amyloid beta peptide Abeta16-20, KLVFF, is investigated in methanol and water via solution NMR experiments and molecular dynamics computer simulations. In previous work, we have shown that AAKLVFF forms peptide nanotubes in methanol and twisted fibrils in water. Chemical shift measurements were used to investigate the solubility of the peptide as a function of concentration in methanol and water. This enabled the determination of critical aggregation concentrations. The solubility was lower in water. In dilute solution, diffusion coefficients revealed the presence of intermediate aggregates in concentrated solution, coexisting with NMR-silent larger aggregates, presumed to be beta-sheets. In water, diffusion coefficients did not change appreciably with concentration, indicating the presence mainly of monomers, coexisting with larger aggregates in more concentrated solution. Concentration-dependent chemical shift measurements indicated a folded conformation for the monomers/intermediate aggregates in dilute methanol, with unfolding at higher concentration. In water, an antiparallel arrangement of strands was indicated by certain ROESY peak correlations. The temperature-dependent solubility of AAKLVFF in methanol was well described by a van't Hoff analysis, providing a solubilization enthalpy and entropy. This pointed to the importance of solvophobic interactions in the self-assembly process. Molecular dynamics simulations constrained by NOE values from NMR suggested disordered reverse turn structures for the monomer, with an antiparallel twisted conformation for dimers. To model the beta-sheet structures formed at higher concentration, possible model arrangements of strands into beta-sheets with parallel and antiparallel configurations and different stacking sequences were used as the basis for MD simulations; two particular arrangements of antiparallel beta-sheets were found to be stable, one

  20. Microscopic factors that control beta-sheet registry in amyloid fibrils formed by fragment 11-25 of amyloid beta peptide: insights from computer simulations.

    Science.gov (United States)

    Negureanu, Lacramioara; Baumketner, Andrij

    2009-06-26

    Short fragments of amyloidogenic proteins are widely used as model systems in studies of amyloid formation. Fragment 11-25 of the amyloid beta protein involved in Alzheimer's disease (Abeta11-25) was recently shown to form amyloid fibrils composed of anti-parallel beta-sheets. Interestingly, fibrils grown under neutral and acidic conditions were seen to possess different registries of their inter-beta-strand hydrogen bonds. In an effort to explain the microscopic origin of this pH dependence, we studied Abeta11-25 fibrils using methods of theoretical modeling. Several structural models were built for fibrils at low and neutral pH levels and these were examined in short molecular dynamics simulations in explicit water. The models that displayed the lowest free energy, as estimated using an implicit solvent model, were selected as representative of the true fibrillar structure. It was shown that the registry of these models agrees well with the experimental results. At neutral pH, the main contribution to the free energy difference between the two registries comes from the electrostatic interactions. The charge group of the carboxy terminus makes a large contribution to these interactions and thus appears to have a critical role in determining the registry.

  1. Abeta(1-42) injection causes memory impairment, lowered cortical and serum BDNF levels, and decreased hippocampal 5-HT(2A) levels

    DEFF Research Database (Denmark)

    Christensen, R; Marcussen, Anders Bue; Wörtwein, Gitta;

    2008-01-01

    Aggregation of the beta-amyloid protein (Abeta) is a hallmark of Alzheimer's disease (AD) and is believed to be causally involved in a neurodegenerative cascade. In patients with AD, reduced levels of serum Brain Derived Neurotrophic Factor (BDNF) and cortical 5-HT(2A) receptor binding has recently...... been reported but it is unknown how these changes are related to beta-amyloid accumulation. In this study we examined in rats the effect of intrahippocampal injections of aggregated Abeta(1-42) (1 microg/microl) on serum and brain BDNF or 5-HT(2A) receptor levels. A social recognition test paradigm...... was used to monitor Abeta(1-42) induced memory impairment. Memory impairment was seen 22 days after injection of Abeta(1-42) in the experimental group and until termination of the experiments. In the Abeta(1-42) injected animals we saw an abolished increase in serum BDNF levels that was accompanied...

  2. Amyloid Beta Peptide Slows Down Sensory-Induced Hippocampal Oscillations

    Directory of Open Access Journals (Sweden)

    Fernando Peña-Ortega

    2012-01-01

    Full Text Available Alzheimer’s disease (AD progresses with a deterioration of hippocampal function that is likely induced by amyloid beta (Aβ oligomers. Hippocampal function is strongly dependent on theta rhythm, and disruptions in this rhythm have been related to the reduction of cognitive performance in AD. Accordingly, both AD patients and AD-transgenic mice show an increase in theta rhythm at rest but a reduction in cognitive-induced theta rhythm. We have previously found that monomers of the short sequence of Aβ (peptide 25–35 reduce sensory-induced theta oscillations. However, considering on the one hand that different Aβ sequences differentially affect hippocampal oscillations and on the other hand that Aβ oligomers seem to be responsible for the cognitive decline observed in AD, here we aimed to explore the effect of Aβ oligomers on sensory-induced theta rhythm. Our results show that intracisternal injection of Aβ1–42 oligomers, which has no significant effect on spontaneous hippocampal activity, disrupts the induction of theta rhythm upon sensory stimulation. Instead of increasing the power in the theta band, the hippocampus of Aβ-treated animals responds to sensory stimulation (tail pinch with an increase in lower frequencies. These findings demonstrate that Aβ alters induced theta rhythm, providing an in vivo model to test for therapeutic approaches to overcome Aβ-induced hippocampal and cognitive dysfunctions.

  3. ETAS, an enzyme-treated asparagus extract, attenuates amyloid beta-induced cellular disorder in PC12 cells.

    Science.gov (United States)

    Ogasawara, Junetsu; Ito, Tomohiro; Wakame, Koji; Kitadate, Kentaro; Sakurai, Takuya; Sato, Shogo; Ishibashi, Yoshinaga; Izawa, Tetsuya; Takahashi, Kazuto; Ishida, Hitoshi; Takabatake, Ichiro; Kizaki, Takako; Ohno, Hideki

    2014-04-01

    One of the pathological characterizations of Alzheimer's disease (AD) is the deposition of amyloid beta peptide (Abeta) in cerebral cortical cells. The deposition of Abeta in neuronal cells leads to an increase in the production of free radicals that are typified by reactive oxygen species (ROS), thereby inducing cell death. A growing body of evidence now suggests that several plant-derived food ingredients are capable of scavenging ROS in mammalian cells. The purpose of the present study was to investigate whether enzyme-treated asparagus extract (ETAS), which is rich in antioxidants, is one of these ingredients. The pre-incubation of differentiated PC 12 cells with ETAS significantly recovered Abeta-induced reduction of cell viability, which was accompanied by reduced levels of ROS. These results suggest that ETAS may be one of the functional food ingredients with anti-oxidative capacity to help prevent AD.

  4. A mathematical model of the kinetics of beta-amyloid fibril growth from the denatured state.

    Science.gov (United States)

    Pallitto, M M; Murphy, R M

    2001-01-01

    Spontaneous conversion of beta-amyloid peptide (Abeta) from soluble monomer to insoluble fibril may underlie the neurodegeneration associated with Alzheimer's disease. A complete description of Abeta self-association kinetics requires identification of the oligomeric species present and the pathway of association, as well as quantitation of rate constants and reaction order. Abeta was rendered monomeric and denatured by dissolution in 8 M urea, pH 10. "Refolding" and fibrillization were initiated by rapid dilution into phosphate-buffered saline, pH 7.4. The kinetics of growth were followed at three different concentrations, using size exclusion chromatography, dynamic light scattering, and static light scattering. A multi-step pathway for fibril formation and growth was postulated. This pathway included 1) rapid commitment to either stable monomer/dimer or unstable intermediate, 2) cooperative association of intermediate into a multimeric "nucleus," 3) elongation of the "nucleus" into filaments via addition of intermediate, 4) lateral aggregation of filaments into fibrils, and 5) fibril elongation via end-to-end association. Differential and algebraic equations describing this kinetic pathway were derived, and model parameters were determined by fitting the data. The utility of the model for identifying toxic Abeta oligomeric specie(s) is demonstrated. The model should prove useful for designing compounds that inhibit Abeta aggregation and/or toxicity. PMID:11509390

  5. Folding and Unfolding of Light-Triggered beta-Hairpin Model Peptides

    NARCIS (Netherlands)

    Schrader, Tobias E.; Cordes, Thorben; Schreier, Wolfgang J.; Koller, Florian O.; Dong, Shou-Liang; Moroder, Luis; Zinth, Wolfgang

    2011-01-01

    Ultrafast spectroscopy in the visible and mid-infrared is used to study the reaction dynamics of two light-triggered model peptides containing an azobenzene derivative as a switching element. One model peptide, the AzoTrpZip2, forms a beta-hairpin structure in the cis form of the chromophore. This p

  6. Characterization of the fine specificity of peptide antibodies to HLA-DQ beta-chain molecules

    DEFF Research Database (Denmark)

    Petersen, J S; Atar, D; Karlsen, Alan E;

    1990-01-01

    In an attempt to produce epitope specific antisera which could distinguish two closely associated HLA-DQ beta-chain alleles, we immunized 20 rabbits with synthetic peptides representing sequences from the first domain of the HLA-DQw8 and -DQw7 beta-chain molecules, differing only by one amino aci...

  7. Identification of a Novel Parallel beta-Strand Conformation within Molecular Monolayer of Amyloid Peptide

    DEFF Research Database (Denmark)

    Liu, Lei; Li, Qiang; Zhang, Shuai;

    2016-01-01

    technique with force controlled in pico-Newton range, combining with molecular dynamic simulation. The identified parallel beta-strand-like structure of molecular monolayer is distinct from the antiparallel beta-strand structure of A beta(33-42) amyloid fibril. This finding enriches the molecular structures....... In this work, the early A beta(33-42) aggregates forming the molecular monolayer at hydrophobic interface are investigated. The molecular monolayer of amyloid peptide A beta(33-42) consisting of novel parallel beta-strand-like structure is further revealed by means of a quantitative nanomechanical spectroscopy......The differentiation of protein properties and biological functions arises from the variation in the primary and secondary structure. Specifically, in abnormal assemblies of protein, such as amyloid peptide, the secondary structure is closely correlated with the stable ensemble and the cytotoxicity...

  8. Structural Transformation and Aggregation of cc-beta Peptides Into Amyloid Proto-fibrils

    Science.gov (United States)

    Bhandari, Yuba; Steckmann, Timothy; Chapagain, Prem; Gerstman, Bernard

    2013-03-01

    The study of amyloid fibrils has important implications in understanding and treatment of various neurodegenerative diseases such as Alzheimer's and Parkinson's. During the formation of amyloid fibrils, peptide polymers manifest fascinating physical behavior by undergoing complicated structural transformations. We examine the behavior of a small engineered peptide called cc-beta, that was designed to mimic the structural changes of the much larger, naturally occurring amyloid beta proteins. Molecular dynamics (MD) simulations are performed to uncover the underlying physics that is responsible for the large scale structural transformations. By using implicit solvent replica exchange MD simulations, we examined the behavior of 12 peptides, initially arranged in four different cc-beta alpha helix trimers. We observed various intermediate stages of aggregation, as well as an organized proto-fibril beta aggregate. We discuss the time evolution and the various interactions involved in the structural transformation.

  9. Role of acetylation and charge in antimicrobial peptides based on human beta-defensin-3.

    Science.gov (United States)

    Papanastasiou, Emilios Andrew; Hua, Quyen; Sandouk, Aline; Son, U Hyon; Christenson, Andrew James; Van Hoek, Monique Louise; Bishop, Barney Michael

    2009-07-01

    Cationic antimicrobial peptides are an evolutionarily ancient and essential element of innate immunity in higher organisms. The precise mechanism by which these peptides exert their antimicrobial activity on bacteria is not well understood. Decapeptides based on the C-terminus of human beta-defensin-3 were designed and evaluated to study the role of charge in defining the antimicrobial activity and selectivity of these peptides against Escherichia coli. Acetylated derivatives of these peptides were prepared in order to further evaluate how positively charged primary amines contribute to potency in these small antimicrobial peptides. These peptides enabled us to explore the relationship between net charge, charge distribution and antimicrobial activity. While the results indicate that net charge is a major factor in antimicrobial activity in these peptides, the actual relationship between charge and potency appears to be more complex.

  10. Thermodynamics of binding interactions between bovine beta-lactoglobulin A and the antihypertensive peptide beta-Lg f142-148.

    Science.gov (United States)

    Roufik, Samira; Gauthier, Sylvie F; Leng, Xiaojing; Turgeon, Sylvie L

    2006-02-01

    The binding capacity of bovine beta-lactoglobulin variant A (beta-Lg A) for six peptides derived from beta-Lg was evaluated using an ultrafiltration method under the following conditions: pH 6.8, 40 degrees C, and a beta-Lg A/peptide molar ratio of 1:5. Only peptides beta-Lg f102-105, f142-148, and f69-83 bound in significant amounts to beta-Lg A corresponding to 1.5, 1.1, and 0.7 mol of peptide per mole of beta-Lg A, respectively. The interaction between beta-Lg A and the antihypertensive peptide beta-Lg f142-148 was investigated further by isothermal titration calorimetry. The binding isotherms at pH 6.8 and 25 degrees C confirmed that beta-Lg f142-148 bound to beta-Lg A and that the interaction followed a sequential three-site binding model with constants of association of 2 x 10(3), 1 x 10(3), and 0.4 x 10(3) M(-1) for the first, second, and third binding sites, respectively. The enthalpy of binding was exothermic for the first and second binding sites and endothermic for the third binding site. Binding of the peptide to all three sites was spontaneous as shown by the negative free energy values. These results show for the first time that beta-Lg A can bind bioactive peptides. This potential could be exploited to transport bioactive peptides and protect them in the gastrointestinal tract following their oral administration as nutraceuticals.

  11. Insights into the molecular interactions between aminopeptidase and amyloid beta peptide using molecular modeling techniques.

    Science.gov (United States)

    Dhanavade, Maruti J; Sonawane, Kailas D

    2014-08-01

    Amyloid beta (Aβ) peptides play a central role in the pathogenesis of Alzheimer's disease. The accumulation of Aβ peptides in AD brain was caused due to overproduction or insufficient clearance and defects in the proteolytic degradation of Aβ peptides. Hence, Aβ peptide degradation could be a promising therapeutic approach in AD treatment. Recent experimental report suggests that aminopeptidase from Streptomyces griseus KK565 (SGAK) can degrade Aβ peptides but the interactive residues are yet to be known in detail at the atomic level. Hence, we developed the three-dimensional model of aminopeptidase (SGAK) using SWISS-MODEL, Geno3D and MODELLER. Model built by MODELLER was used for further studies. Molecular docking was performed between aminopeptidase (SGAK) with wild-type and mutated Aβ peptides. The docked complex of aminopeptidase (SGAK) and wild-type Aβ peptide (1IYT.pdb) shows more stability than the other complexes. Molecular docking and MD simulation results revealed that the residues His93, Asp105, Glu139, Glu140, Asp168 and His255 are involved in the hydrogen bonding with Aβ peptide and zinc ions. The interactions between carboxyl oxygen atoms of Glu139 of aminopeptidase (SGAK) with water molecule suggest that the Glu139 may be involved in the nucleophilic attack on Ala2-Glu3 peptide bond of Aβ peptide. Hence, amino acid Glu139 of aminopeptidase (SGAK) might play an important role to degrade Aβ peptides, a causative agent of Alzheimer's disease.

  12. Ultrafast Unzipping of a Beta-Hairpin Peptide

    NARCIS (Netherlands)

    Zinth, W.; Schrader, T.E.; Schreier, W.J.; Koller, F.O.; Cordes, T.; Babitzki, G.; Denschlag, R.; Tavan, P.; Löweneck, M.; Dong, Shou-Liang; Moroder, L.; Renner, C.; Corkum, Paul; Jonas, David M.; Miller, R.J. Dwayne; Weiner, Andrew M.

    2007-01-01

    Light induced switching of a beta-hairpin structure is investigated by femtosecond IR spectroscopy. While the unzipping process comprises ultrafast kinetics and is finished within 1 ns, the folding into the hairpin structure is a much slower process.

  13. Beta-amyloid peptides undergo regulated co-secretion with neuropeptide and catecholamine neurotransmitters

    OpenAIRE

    Toneff, Thomas; Funkelstein, Lydiane; Mosier, Charles; Abagyan, Armen; Ziegler, Michael; Hook, Vivian

    2013-01-01

    Beta-amyloid (Aβ) peptides are secreted from neurons, resulting in extracellular accumulation of Aβ and neurodegeneration of Alzheimer's disease. Because neuronal secretion is fundamental for the release of neurotransmitters, this study assessed the hypothesis that Aβ undergoes co-release with neurotransmitters. Model neuronal-like chromaffin cells were investigated, and results illustrate regulated, co-secretion of Aβ(1–40) and Aβ(1–42) with peptide neurotransmitters (galanin, enkephalin, an...

  14. Complement activation by the amyloid proteins A beta peptide and beta 2-microglobulin

    DEFF Research Database (Denmark)

    Nybo, Mads; Nielsen, E H; Svehag, S E

    1999-01-01

    Complement activation (CA) has been reported to play a role in the pathogenesis of Alzheimer's disease (AD). To investigate whether CA may contribute to amyloidogenesis in general, the CA potential of different amyloid fibril proteins was tested. CA induced by A beta preparations containing soluble...... protein, protofilaments and some fibrils or only fibrils in a solid phase system (ELISA) was modest with a slow kinetics compared to the positive delta IgG control. Soluble A beta induced no detectable CA in a liquid phase system (complement consumption assay) while fibrillar A beta caused CA at 200 mg....../ml and higher concentrations. Soluble beta 2-microglobulin (beta 2M) purified from peritoneal dialysates was found to be as potent a complement activator as A beta in both solid and liquid phase systems while beta 2M purified from urine exhibited lower activity, a difference which may be explained...

  15. Antimicrobial peptides initiate IL-1 beta posttranslational processing: a novel role beyond innate immunity.

    Science.gov (United States)

    Perregaux, David G; Bhavsar, Kanan; Contillo, Len; Shi, Jishu; Gabel, Christopher A

    2002-03-15

    Human monocytes stimulated with LPS produce large quantities of prointerleukin-1beta, but little of this cytokine product is released extracellularly as the mature biologically active species. To demonstrate efficient proteolytic cleavage and export, cytokine-producing cells require a secondary effector stimulus. In an attempt to identify agents that may serve as initiators of IL-1beta posttranslational processing in vivo, LPS-activated human monocytes were treated with several individual antimicrobial peptides. Two peptides derived from porcine neutrophils, protegrin (PTG)-1 and PTG-3, promoted rapid and efficient release of mature IL-1beta. The PTG-mediated response engaged a mechanism similar to that initiated by extracellular ATP acting via the P2X(7) receptor. Thus, both processes were disrupted by a caspase inhibitor, both were sensitive to ethacrynic acid and CP-424,174, two pharmacological agents that suppress posttranslational processing, and both were negated by elevation of extracellular potassium. Moreover, the PTGs, like ATP, promoted a dramatic change in monocyte morphology and a loss of membrane latency. The PTG response was concentration dependent and was influenced profoundly by components within the culture medium. In contrast, porcine neutrophil antimicrobial peptides PR-26 and PR-39 did not initiate IL-1beta posttranslational processing. The human defensin HNP-1 and the frog peptide magainin 1 elicited export of 17-kDa IL-1beta, but these agents were less efficient than PTGs. As a result of this ability to promote release of potent proinflammatory cytokines such as IL-1beta, select antimicrobial peptides may possess important immunomodulatory functions that extend beyond innate immunity.

  16. Receptor-associated protein (RAP plays a central role in modulating Abeta deposition in APP/PS1 transgenic mice.

    Directory of Open Access Journals (Sweden)

    Guilian Xu

    Full Text Available BACKGROUND: Receptor associated protein (RAP functions in the endoplasmic reticulum (ER to assist in the maturation of several membrane receptor proteins, including low density lipoprotein receptor-related protein (LRP and lipoprotein receptor 11 (SorLA/LR11. Previous studies in cell and mouse model systems have demonstrated that these proteins play roles in the metabolism of the amyloid precursor protein (APP, including processes involved in the generation, catabolism and deposition of beta-amyloid (Abeta peptides. METHODOLOGY/PRINCIPAL FINDINGS: Mice transgenic for mutant APPswe and mutant presenilin 1 (PS1dE9 were mated to mice with homozygous deletion of RAP. Unexpectedly, mice that were homozygous null for RAP and transgenic for APPswe/PS1dE9 showed high post-natal mortality, necessitating a shift in focus to examine the levels of amyloid deposition in APPswe/PS1dE9 that were hemizygous null for RAP. Immunoblot analysis confirmed 50% reductions in the levels of RAP with modest reductions in the levels of proteins dependent upon RAP for maturation [LRP trend towards a 20% reduction ; SorLA/LR11 statistically significant 15% reduction (p<0.05]. Changes in the levels of these proteins in the brains of [APPswe/PS1dE9](+/-/RAP(+/- mice correlated with 30-40% increases in amyloid deposition by 9 months of age. CONCLUSIONS/SIGNIFICANCE: Partial reductions in the ER chaperone RAP enhance amyloid deposition in the APPswe/PS1dE9 model of Alzheimer amyloidosis. Partial reductions in RAP also affect the maturation of LRP and SorLA/LR11, which are each involved in several different aspects of APP processing and Abeta catabolism. Together, these findings suggest a central role for RAP in Alzheimer amyloidogenesis.

  17. Glucagon-like peptide-1 receptor agonist treatment reduces beta cell mass in normoglycaemic mice

    NARCIS (Netherlands)

    Ellenbroek, J.H.; Tons, H.A.; Westerouen van Meeteren, M.J.; de Graaf, N.; Hanegraaf, M.A.; Rabelink, T.J.; Carlotti, F.; de Koning, E.J.

    2013-01-01

    AIMS/HYPOTHESIS: Incretin-based therapies improve glycaemic control in patients with type 2 diabetes. In animal models of diabetes, glucagon-like peptide-1 receptor agonists (GLP-1RAs) increase beta cell mass. GLP-1RAs are also evaluated in non-diabetic individuals with obesity and cardiovascular di

  18. Lipidated alpha-Peptide/beta-Peptoid Hybrids with Potent Antiinflammatory Activity

    DEFF Research Database (Denmark)

    Skovbakke, Sarah L.; Larsen, Camilla J.; Heegaard, Peter M. H.;

    2015-01-01

    , in contrast to polymyxin B, displayed only minor activity in the Limulus amebocyte lysate assay. Flow cytometry data showed specific interaction of a fluorophore-labeled lipidated a-peptide/beta-peptoid hybrid with monocytes and granulocytes indicating a cellular target expressed by these leukocyte subsets....

  19. PEGylated nanoparticles bind to and alter amyloid-beta peptide conformation

    DEFF Research Database (Denmark)

    Brambilla, Davide; Verpillot, Romain; Le Droumaguet, Benjamin;

    2012-01-01

    We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs...

  20. Pancreatic beta cells synthesize neuropeptide Y and can rapidly release peptide co-transmitters.

    Directory of Open Access Journals (Sweden)

    Matthew D Whim

    Full Text Available BACKGROUND: In addition to polypeptide hormones, pancreatic endocrine cells synthesize a variety of bioactive molecules including classical transmitters and neuropeptides. While these co-transmitters are thought to play a role in regulating hormone release little is known about how their secretion is regulated. Here I investigate the synthesis and release of neuropeptide Y from pancreatic beta cells. METHODOLOGY/PRINCIPAL FINDINGS: NPY appears to be an authentic co-transmitter in neonatal, but not adult, beta cells because (1 early in mouse post-natal development, many beta cells are NPY-immunoreactive whereas no staining is observed in beta cells from NPY knockout mice; (2 GFP-expressing islet cells from an NPY(GFP transgenic mouse are insulin-ir; (3 single cell RT-PCR experiments confirm that the NPY(GFP cells contain insulin mRNA, a marker of beta cells. The NPY-immunoreactivity previously reported in alpha and delta cells is therefore likely to be due to the presence of NPY-related peptides. INS-1 cells, a beta cell line, are also NPY-ir and contain NPY mRNA. Using the FMRFamide tagging technique, NPY secretion was monitored from INS-1 beta cells with high temporal resolution. Peptide release was evoked by brief depolarizations and was potentiated by activators of adenylate cyclase and protein kinase A. Following a transient depolarization, NPY-containing dense core granules fused with the cell membrane and discharged their contents within a few milliseconds. CONCLUSIONS: These results indicate that after birth, NPY expression in pancreatic islets is restricted to neonatal beta cells. The presence of NPY suggests that peptide co-transmitters could mediate rapid paracrine or autocrine signaling within the endocrine pancreas. The FMRFamide tagging technique may be useful in studying the release of other putative islet co-transmitters in real time.

  1. Uptake of {sup 188}Re-{beta}-naphthyl-peptide in cervical carcinoma tumours in athymic mice

    Energy Technology Data Exchange (ETDEWEB)

    Arteaga de Murphy, Consuelo E-mail: cmurphy@data.net.mx; Pedraza-Lopez, Martha; Ferro-Flores, Guillermina; Murphy-Stack, Eduardo; Chavez-Mercado, Leonora; Ascencio, Jorge A.; Garcia-Salinas, Laura; Hernandez-Gutierrez, Salomon

    2001-04-01

    Radiolabelled somatostatin analogues have been used in diagnostic and therapeutic nuclear medicine to treat cancerous tumours. Lanreotide, a cyclic octapeptide, {beta}-naphthyl-peptide, with antiproliferative action on human small cell lung carcinoma was {sup 188}Re labelled and characterised, and its biodistribution was studied in mice. Molecular modelling indicates that the lipophilic radiopharmaceutical might be an oxo-rhenium (V) penta-coordinated complex. The implanted human cervical tumour of epidermoid origin was positive for cytokeratins and Vimentin. Uptake of {sup 188}Re-labelled peptide in the implanted tumour in athymic mice was 6.2{+-}2.9% and was rapidly cleared via the hepatobiliary system. {sup 188}Re-{beta}-naphthyl-peptide might be a potential therapeutic agent.

  2. Characterization of glucagon-like peptide-1 receptor beta-arrestin 2 interaction: a high-affinity receptor phenotype

    DEFF Research Database (Denmark)

    Jorgensen, Rasmus; Martini, Lene; Schwartz, Thue W;

    2005-01-01

    To dissect the interaction between beta-arrestin ((beta)arr) and family B G protein-coupled receptors, we constructed fusion proteins between the glucagon-like peptide 1 receptor and (beta)arr2. The fusion constructs had an increase in apparent affinity selectively for glucagon, suggesting that (...

  3. Binding of an oxindole alkaloid from Uncaria tomentosa to amyloid protein (Abeta1-40).

    Science.gov (United States)

    Frackowiak, Teresa; Baczek, Tomasz; Roman, Kaliszana; Zbikowska, Beata; Gleńsk, Michał; Fecka, Izabela; Cisowski, Wojciech

    2006-01-01

    The primary aim of this work was to determine the interactions of an oxindole alkaloid (mitraphylline) isolated from Uncaria tomentosa with beta-amyloid 1-40 (Abeta1-40 protein) applying the capillary electrophoresis (CE) method. Specifically the Hummel-Dreyer method and Scatchard analysis were performed to study the binding of oxindole alkaloids with Abeta1-40 protein. Prior to these studies extraction of the alkaloid of interest was carried out. Identification of the isolated alkaloid was performed by the use of thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI-MS). The proposed approach was proved to be an efficient and accurate method for specific compound isolation and identification purposes. Moreover, analytical information from the CE approach can be considered as the valuable tool for binding constant determination. The binding constant of mitraphylline with Abeta1-40 protein determined by the Hummel-Dreyer method and Scatchard analysis equals K = 9.95 x 10(5) M(-1). The results obtained showed the significant binding of the tested compound with Abeta1-40 protein. These results are discussed and interpreted in the view of developing a strategy for identification of novel compounds of great importance in Alzheimer disease therapy.

  4. The interaction of beta 2-microglobulin (beta 2m) with mouse class I major histocompatibility antigens and its ability to support peptide binding. A comparison of human and mouse beta 2m

    DEFF Research Database (Denmark)

    Pedersen, L O; Stryhn, A; Holter, T L;

    1995-01-01

    The function of major histocompatibility complex (MHC) class I molecules is to sample peptides derived from intracellular proteins and to present these peptides to CD8+ cytotoxic T lymphocytes. In this paper, biochemical assays addressing MHC class I binding of both peptide and beta 2-microglobul...

  5. Controlled release of TGF-beta 1 from RADA self-assembling peptide hydrogel scaffolds

    Science.gov (United States)

    Zhou, Ao; Chen, Shuo; He, Bin; Zhao, Weikang; Chen, Xiaojun; Jiang, Dianming

    2016-01-01

    Bioactive mediators, cytokines, and chemokines have an important role in regulating and optimizing the synergistic action of materials, cells, and cellular microenvironments for tissue engineering. RADA self-assembling peptide hydrogels have been proved to have an excellent ability to promote cell proliferation, wound healing, tissue repair, and drug delivery. Here, we report that D-RADA16 and L-RADA16-RGD self-assembling peptides can form stable second structure and hydrogel scaffolds, affording the slow release of growth factor (transforming growth factor cytokine-beta 1 [TGF-beta 1]). In vitro tests demonstrated that the plateau release amount can be obtained till 72 hours. Moreover, L-RADA16, D-RADA16, and L-RADA16-RGD self-assembling peptide hydrogels containing TGF-beta 1 were used for 3D cell culture of bone mesenchymal stem cells of rats for 2 weeks. The results revealed that these three RADA16 peptide hydrogels had a significantly favorable influence on proliferation of bone mesenchymal stem cells and hold some promise in slow and sustained release of growth factor. PMID:27703332

  6. The effects of glucagon-like peptide-1 on the beta cell

    DEFF Research Database (Denmark)

    Vilsbøll, Tina

    2009-01-01

    Type 2 diabetes is a progressive disease characterized by insulin resistance and impaired beta-cell function. Treatments that prevent further beta-cell decline are therefore essential for the management of type 2 diabetes. Glucagon-like peptide-1 (GLP-1) is an incretin hormone that is known...... to stimulate glucose-dependent insulin secretion. Furthermore, GLP-1 appears to have multiple positive effects on beta cells. However, GLP-1 is rapidly degraded by dipeptidyl peptidase-4 (DPP-4), which limits the clinical relevance of GLP-1 for the treatment of type 2 diabetes. Two main classes of GLP-1-based...... therapies have now been developed: DPP-4 inhibitors and GLP-1 receptor agonists. Liraglutide and exenatide are examples of GLP-1 receptor agonists that have been developed to mimic the insulinotropic characteristics of endogenous GLP-1. Both have demonstrated improved beta-cell function in patients...

  7. Factors That Affect the Degree of Twist in beta-Sheet Structures : A Molecular Dynamics Simulation Study of a Cross-beta Filament of the GNNQQNY Peptide

    NARCIS (Netherlands)

    Periole, Xavier; Rampioni, Aldo; Vendruscolo, Michele; Mark, Alan E.

    2009-01-01

    By exploiting the recent availability of the crystal structure of a cross-beta filament of the GNNQQNY peptide fragment of the yeast prion protein Sup35, possible factors affecting the twisting of beta-sheets structures have been analyzed. The advantage of this system is that it is composed entirely

  8. Binding of peptides to HLA-DQ molecules: peptide binding properties of the disease-associated HLA-DQ(alpha 1*0501, beta 1*0201) molecule

    DEFF Research Database (Denmark)

    Johansen, B H; Buus, S; Vartdal, F;

    1994-01-01

    Peptide binding to DQ molecules has not previously been described. Here we report a biochemical peptide-binding assay specific for the DQ2 [i.e. DQ(alpha 1*0501, beta 1*0201)] molecule. This molecule was chosen since it shows a strong association to diseases such as celiac disease and insulin...

  9. beta-Scission of C-3 (beta-carbon) alkoxyl radicals on peptides and proteins

    DEFF Research Database (Denmark)

    Headlam, H A; Mortimer, A; Easton, C J;

    2000-01-01

    of methanal (formaldehyde). This product has been quantified with a number of oxidized peptides and proteins, and can account for up to 64% of the initial attacking radicals with some Ala peptides. When quantified together with the hydroperoxide precursors, these species account for up to 80% of the initial...... radicals, confirming that this is a major process. Methanal causes cell toxicity and DNA damage and is an animal carcinogen and a genotoxic agent in human cells. Thus, the formation and subsequent reaction of alkoxyl radicals formed at the C-3 position on aliphatic amino acid side chains on peptides......Exposure of proteins to radicals in the presence of O(2) brings about multiple changes in the target molecules. These alterations include oxidation of side chains, fragmentation, cross-linking, changes in hydrophobicity and conformation, altered susceptibility to proteolytic enzymes, and formation...

  10. Insulin Promotes Survival of Amyloid-Beta Oligomers Neuroblastoma Damaged Cells via Caspase 9 Inhibition and Hsp70 Upregulation

    Directory of Open Access Journals (Sweden)

    M. Di Carlo

    2010-01-01

    Full Text Available Alzheimer's disease (AD and type 2 diabetes are connected in a way that is still not completely understood, but insulin resistance has been implicated as a risk factor for developing AD. Here we show an evidence that insulin is capable of reducing cytotoxicity induced by Amyloid-beta peptides (A-beta in its oligomeric form in a dose-dependent manner. By TUNEL and biochemical assays we demonstrate that the recovery of the cell viability is obtained by inhibition of intrinsic apoptotic program, triggered by A-beta and involving caspase 9 and 3 activation. A protective role of insulin on mitochondrial damage is also shown by using Mito-red vital dye. Furthermore, A-beta activates the stress inducible Hsp70 protein in LAN5 cells and an overexpression is detectable after the addition of insulin, suggesting that this major induction is the necessary condition to activate a cell survival program. Together, these results may provide opportunities for the design of preventive and therapeutic strategies against AD.

  11. Huperzine A protects isolated rat brain mitochondria against beta-amyloid peptide.

    Science.gov (United States)

    Gao, Xin; Zheng, Chun Yan; Yang, Ling; Tang, Xi Can; Zhang, Hai Yan

    2009-06-01

    Our previous work in cells and animals showed that mitochondria are involved in the neuroprotective effect of huperzine A (HupA). In this study, the effects of HupA on isolated rat brain mitochondria were investigated. In addition to inhibiting the Abeta(25-35) (40 microM)-induced decrease in mitochondrial respiration, adenosine 5'-triphosphate (ATP) synthesis, enzyme activity, and transmembrane potential, HupA (0.01 or 0.1 microM) effectively prevented Abeta-induced mitochondrial swelling, reactive oxygen species increase, and cytochrome c release. More interestingly, administration of HupA to isolated mitochondria promoted the rate of ATP production and blocked mitochondrial swelling caused by normal osmosis. These results indicate that HupA protects mitochondria against Abeta at least in part by preserving membrane integrity and improving energy metabolism. These direct effects on mitochondria further extend the noncholinergic functions of HupA. PMID:19272446

  12. A new tool in peptide engineering: a photoswitchable stilbene-type beta-hairpin mimetic.

    Science.gov (United States)

    Erdélyi, Máté; Karlén, Anders; Gogoll, Adolf

    2005-12-23

    Peptide secondary structure mimetics are important tools in medicinal chemistry, as they provide analogues of endogenous peptides with new physicochemical and pharmacological properties. The development, synthesis, photochemical investigation, and conformational analysis of a stilbene-type beta-hairpin mimetic capable of light-triggered conformational changes have been achieved. In addition to standard spectroscopic techniques (nuclear Overhauser effects, amide temperature coefficients, circular dichroism spectroscopy), the applicability of self-diffusion measurements (longitudinal eddy current delay pulsed-field gradient spin echo (LED-PGSE) NMR technique) in conformational studies of oligopeptides is demonstrated. The title compound shows photoisomerization of the stilbene chromophore, resulting in a change in solution conformation between an unfolded structure and a folded beta-hairpin.

  13. Bioinspired peptide nanotubes: Deposition technology and physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Shklovsky, J.; Beker, P. [Department of Physical Electronics, School of Electrical Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv (Israel); Amdursky, N. [Department of Physical Electronics, School of Electrical Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv (Israel); Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv (Israel); Gazit, E. [Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv (Israel); Rosenman, G., E-mail: gilr@eng.tau.ac.il [Department of Physical Electronics, the School of Electrical Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv (Israel)

    2010-05-25

    Proteins and peptides have the intrinsic ability to self-assemble into elongated solid nanofibrils, which give rise to amyloid progressive neurodegenerative diseases (Alzheimer's, Parkinson, etc.). It has been found that of the core recognition motif of A{beta} peptide is the diphenylalanine element. The diphenylalanine peptide can self-assemble into well-ordered peptide nanotubes (PNT). In this paper we report on our newly developed process-vapor deposition of PNT and 'bottom-up' nanotechnological techniques of PNT patterning. Study of several physical properties of PNT such as optical and electrochemical are presented. The results may lead to the development of a new generation of PNT-based bioinspired functional nanodevices.

  14. Characterization of the conformational space of a triple-stranded beta-sheet forming peptide with molecular dynamics simulations

    NARCIS (Netherlands)

    Soto, P; Colombo, G

    2004-01-01

    Molecular dynamics (MD) simulations have been performed on a series of mutants of the 20 amino acid peptide Betanova in order to critically assess the ability of MD simulations to reproduce the folding and stability of small beta-sheet-forming peptides on currently accessible timescales. Simulations

  15. Acetylcholinesterase accelerates assembly of amyloid-beta-peptides into Alzheimer's fibrils: possible role of the peripheral site of the enzyme.

    Science.gov (United States)

    Inestrosa, N C; Alvarez, A; Pérez, C A; Moreno, R D; Vicente, M; Linker, C; Casanueva, O I; Soto, C; Garrido, J

    1996-04-01

    Acetylcholinesterase (AChE), an important component of cholinergic synapses, colocalizes with amyloid-beta peptide (A beta) deposits of Alzheimer's brain. We report here that bovine brain AChE, as well as the human and mouse recombinant enzyme, accelerates amyloid formation from wild-type A beta and a mutant A beta peptide, which alone produces few amyloid-like fibrils. The action of AChE was independent of the subunit array of the enzyme, was not affected by edrophonium, an active site inhibitor, but it was affected by propidium, a peripheral anionic binding site ligand. Butyrylcholinesterase, an enzyme that lacks the peripheral site, did not affect amyloid formation. Furthermore, AChE is a potent amyloid-promoting factor when compared with other A beta-associated proteins. Thus, in addition to its role in cholinergic synapses, AChE may function by accelerating A beta formation and could play a role during amyloid deposition in Alzheimer's brain.

  16. Chemokines, macrophage inflammatory protein-2 and stromal cell-derived factor-1{alpha}, suppress amyloid {beta}-induced neurotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Raman, Dayanidhi; Milatovic, Snjezana-Zaja [Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Milatovic, Dejan [Department of Pediatrics/Pediatric Toxicology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Splittgerber, Ryan [Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States); Fan, Guo-Huang [Department of Neurobiology and Neurotoxicology, Meharry Medical College, Nashville, TN 37221 (United States); Richmond, Ann, E-mail: ann.richmond@vanderbilt.edu [VA Medical Center, Nashville, TN 37232 (United States); Department of Cancer Biology, Vanderbilt University, School of Medicine, Nashville, TN 37232 (United States)

    2011-11-15

    Alzheimer's disease (AD) is characterized by a progressive cognitive decline and accumulation of neurotoxic oligomeric peptides amyloid-{beta} (A{beta}). Although the molecular events are not entirely known, it has become evident that inflammation, environmental and other risk factors may play a causal, disruptive and/or protective role in the development of AD. The present study investigated the ability of the chemokines, macrophage inflammatory protein-2 (MIP-2) and stromal cell-derived factor-1{alpha} (SDF-1{alpha}), the respective ligands for chemokine receptors CXCR2 and CXCR4, to suppress A{beta}-induced neurotoxicity in vitro and in vivo. Pretreatment with MIP-2 or SDF-1{alpha} significantly protected neurons from A{beta}-induced dendritic regression and apoptosis in vitro through activation of Akt, ERK1/2 and maintenance of metalloproteinase ADAM17 especially with SDF-1{alpha}. Intra-cerebroventricular (ICV) injection of A{beta} led to reduction in dendritic length and spine density of pyramidal neurons in the CA1 area of the hippocampus and increased oxidative damage 24 h following the exposure. The A{beta}-induced morphometric changes of neurons and increase in biomarkers of oxidative damage, F{sub 2}-isoprostanes, were significantly inhibited by pretreatment with the chemokines MIP-2 or SDF-1{alpha}. Additionally, MIP-2 or SDF-1{alpha} was able to suppress the aberrant mislocalization of p21-activated kinase (PAK), one of the proteins involved in the maintenance of dendritic spines. Furthermore, MIP-2 also protected neurons against A{beta} neurotoxicity in CXCR2-/- mice, potentially through observed up regulation of CXCR1 mRNA. Understanding the neuroprotective potential of chemokines is crucial in defining the role for their employment during the early stages of neurodegeneration. -- Research highlights: Black-Right-Pointing-Pointer Neuroprotective ability of the chemokines MIP2 and CXCL12 against A{beta} toxicity. Black-Right-Pointing-Pointer MIP

  17. Familial Alzheimer's disease-linked presenilin 1 variants elevate Abeta1-42/1-40 ratio in vitro and in vivo.

    Science.gov (United States)

    Borchelt, D R; Thinakaran, G; Eckman, C B; Lee, M K; Davenport, F; Ratovitsky, T; Prada, C M; Kim, G; Seekins, S; Yager, D; Slunt, H H; Wang, R; Seeger, M; Levey, A I; Gandy, S E; Copeland, N G; Jenkins, N A; Price, D L; Younkin, S G; Sisodia, S S

    1996-11-01

    Mutations in the presenilin 1 (PS1) and presenilin 2 genes cosegregate with the majority of early-onset familial Alzheimer's disease (FAD) pedigrees. We now document that the Abeta1-42(43)/Abeta1-40 ratio in the conditioned media of independent N2a cell lines expressing three FAD-linked PS1 variants is uniformly elevated relative to cells expressing similar levels of wild-type PS1. Similarly, the Abeta1-42(43)/Abeta1-40 ratio is elevated in the brains of young transgenic animals coexpressing a chimeric amyloid precursor protein (APP) and an FAD-linked PS1 variant compared with brains of transgenic mice expressing APP alone or transgenic mice coexpressing wild-type human PS1 and APP. These studies provide compelling support for the view that one mechanism by which these mutant PS1 cause AD is by increasing the extracellular concentration of Abeta peptides terminating at 42(43), species that foster Abeta deposition. PMID:8938131

  18. Microwave-assisted click polymerization for the synthesis of Abeta(16-22) cyclic oligomers and their self-assembly into polymorphous aggregates.

    Science.gov (United States)

    Elgersma, Ronald C; van Dijk, Maarten; Dechesne, Annemarie C; van Nostrum, Cornelus F; Hennink, Wim E; Rijkers, Dirk T S; Liskamp, Rob M J

    2009-11-01

    We report on the design, synthesis, and structural analysis of cyclic oligomers with an amyloidogenic peptide sequence as the repeating unit to obtain novel self-assembling bionanomaterials. The peptide was derived from the Alzheimer Abeta(16-22) sequence since its strong tendency to form antiparallel beta-sheets ensured the formation of intermolecular hydrogen bridges on which the supramolecular assembly of the individual cyclic oligomers was based. The synthesis of the cyclic oligomers was performed via a microwave-assisted Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction of azido-Lys-Leu-Val-Phe-Phe-Ala-Glu-propargyl amide as the monomer. The formation of cyclic oligomers, up to pentamers (35 amino acid residues), was verified by MALDI-TOF analysis and the individual cyclic monomer and dimer could be isolated by HPLC. Gelation behavior and the self-assembly of the linear monomer and the cyclic monomer and dimer were studied by TEM, FTIR and CD. Significant differences were observed in the morphology of the supramolecular aggregates of these three peptides that could be explained by alterations of the hydrogen bond network. PMID:19830304

  19. Interaction of amyloid inhibitor proteins with amyloid beta peptides: insight from molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Payel Das

    Full Text Available Knowledge of the detailed mechanism by which proteins such as human αB- crystallin and human lysozyme inhibit amyloid beta (Aβ peptide aggregation is crucial for designing treatment for Alzheimer's disease. Thus, unconstrained, atomistic molecular dynamics simulations in explicit solvent have been performed to characterize the Aβ17-42 assembly in presence of the αB-crystallin core domain and of lysozyme. Simulations reveal that both inhibitor proteins compete with inter-peptide interaction by binding to the peptides during the early stage of aggregation, which is consistent with their inhibitory action reported in experiments. However, the Aβ binding dynamics appear different for each inhibitor. The binding between crystallin and the peptide monomer, dominated by electrostatics, is relatively weak and transient due to the heterogeneous amino acid distribution of the inhibitor surface. The crystallin-bound Aβ oligomers are relatively long-lived, as they form more extensive contact surface with the inhibitor protein. In contrast, a high local density of arginines from lysozyme allows strong binding with Aβ peptide monomers, resulting in stable complexes. Our findings not only illustrate, in atomic detail, how the amyloid inhibitory mechanism of human αB-crystallin, a natural chaperone, is different from that of human lysozyme, but also may aid de novo design of amyloid inhibitors.

  20. A humanin derivative reduces amyloid beta accumulation and ameliorates memory deficit in triple transgenic mice.

    Directory of Open Access Journals (Sweden)

    Takako Niikura

    Full Text Available Humanin (HN, a 24-residue peptide, was identified as a novel neuroprotective factor and shows anti-cell death activity against a wide spectrum of Alzheimer's disease (AD-related cytotoxicities, including exposure to amyloid beta (Abeta, in vitro. We previously demonstrated that the injection of S14G-HN, a highly potent HN derivative, into brain ameliorated memory loss in an Abeta-injection mouse model. To fully understand HN's functions under AD-associated pathological conditions, we examined the effect of S14G-HN on triple transgenic mice harboring APP(swe, tau(P310L, and PS-1(M146V that show the age-dependent development of multiple pathologies relating to AD. After 3 months of intranasal treatment, behavioral analyses showed that S14G-HN ameliorated cognitive impairment in male mice. Moreover, ELISA and immunohistochemical analyses showed that Abeta levels in brains were markedly lower in S14G-HN-treated male and female mice than in vehicle control mice. We also found the expression level of neprilysin, an Abeta degrading enzyme, in the outer molecular layer of hippocampal formation was increased in S14G-HN-treated mouse brains. NEP activity was also elevated by S14G-HN treatment in vitro. These findings suggest that decreased Abeta level in these mice is at least partly attributed to S14G-HN-induced increase of neprilysin level. Although HN was identified as an anti-neuronal death factor, these results indicate that HN may also have a therapeutic effect on amyloid accumulation in AD.

  1. Beta-methyl substitution of cyclohexylalanine in Dmt-Tic-Cha-Phe peptides results in highly potent delta opioid antagonists.

    Science.gov (United States)

    Tóth, Géza; Ioja, Eniko; Tömböly, Csaba; Ballet, Steven; Tourwé, Dirk; Péter, Antal; Martinek, Tamás; Chung, Nga N; Schiller, Peter W; Benyhe, Sándor; Borsodi, Anna

    2007-01-25

    The opioid peptide TIPP (H-Tyr-Tic-Phe-Phe-OH, Tic:1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) was substituted with Dmt (2',6'-dimethyltyrosine) and a new unnatural amino acid, beta-MeCha (beta-methyl-cyclohexylalanine). This double substitution led to a new series of opioid peptides displaying subnanomolar delta antagonist activity and mu agonist or antagonist properties depending on the configuration of the beta-MeCha residue. The most promising analog, H-Dmt-Tic-(2S,3S)-beta-MeCha-Phe-OH was a very selective delta antagonist both in the mouse vas deferens (MVD) assay (Ke = 0.241 +/- 0.05 nM) and in radioligand binding assay (K i delta = 0.48 +/- 0.05 nM, K i mu/K i delta = 2800). The epimeric peptide H-Dmt-Tic-(2S,3R)-beta-MeCha-Phe-OH and the corresponding peptide amide turned out to be mixed partial mu agonist/delta antagonists in the guinea pig ileum and MVD assays. Our results constitute further examples of the influence of Dmt and beta-methyl substitution as well as C-terminal amidation on the potency, selectivity, and signal transduction properties of TIPP related peptides. Some of these compounds represent valuable pharmacological tools for opioid research.

  2. The Structural Basis of [beta]-Peptide-Specific Cleavage by the Serine Protease Cyanophycinase

    Energy Technology Data Exchange (ETDEWEB)

    Law, Adrienne M.; Lai, Sandy W.S.; Tavares, John; Kimber, Matthew S.; (Guelph)

    2010-10-01

    Cyanophycin, or poly-L-Asp-multi-L-Arg, is a non-ribosomally synthesized peptidic polymer that is used for nitrogen storage by cyanobacteria and other select eubacteria. Upon synthesis, it self-associates to form insoluble granules, the degradation of which is uniquely catalyzed by a carboxy-terminal-specific protease, cyanophycinase. We have determined the structure of cyanophycinase from the freshwater cyanobacterium Synechocystis sp. PCC6803 at 1.5-{angstrom} resolution, showing that the structure is dimeric, with individual protomers resembling aspartyl dipeptidase. Kinetic characterization of the enzyme demonstrates that the enzyme displays Michaelis-Menten kinetics with a k{sub cat} of 16.5 s{sup -1} and a k{sub cat}/K{sub M} of 7.5 x 10{sup -6} M{sup -1} s{sup -1}. Site-directed mutagenesis experiments confirm that cyanophycinase is a serine protease and that Gln101, Asp172, Gln173, Arg178, Arg180 and Arg183, which form a conserved pocket adjacent to the catalytic Ser132, are functionally critical residues. Modeling indicates that cyanophycinase binds the {beta}-Asp-Arg dipeptide residue immediately N-terminal to the scissile bond in an extended conformation in this pocket, primarily recognizing this penultimate {beta}-Asp-Arg residue of the polymeric chain. Because binding and catalysis depend on substrate features unique to {beta}-linked aspartyl peptides, cyanophycinase is able to act within the cytosol without non-specific cleavage events disrupting essential cellular processes.

  3. The amyloid beta-peptide is imported into mitochondria via the TOM import machinery and localized to mitochondrial cristae

    DEFF Research Database (Denmark)

    Hansson Petersen, Camilla A; Alikhani, Nyosha; Behbahani, Homira;

    2008-01-01

    by immunoelectron microscopy in human cortical brain biopsies obtained from living subjects with normal pressure hydrocephalus. Thus, we present a unique import mechanism for Abeta in mitochondria and demonstrate both in vitro and in vivo that Abeta is located to the mitochondrial cristae. Importantly, we also show...

  4. Cerebrolysin decreases amyloid-beta production by regulating amyloid protein precursor maturation in a transgenic model of Alzheimer's disease.

    Science.gov (United States)

    Rockenstein, Edward; Torrance, Magdalena; Mante, Michael; Adame, Anthony; Paulino, Amy; Rose, John B; Crews, Leslie; Moessler, Herbert; Masliah, Eliezer

    2006-05-15

    Cerebrolysin is a peptide mixture with neurotrophic effects that might reduce the neurodegenerative pathology in Alzheimer's disease (AD). We have previously shown in an amyloid protein precursor (APP) transgenic (tg) mouse model of AD-like neuropathology that Cerebrolysin ameliorates behavioral deficits, is neuroprotective, and decreases amyloid burden; however, the mechanisms involved are not completely clear. Cerebrolysin might reduce amyloid deposition by regulating amyloid-beta (Abeta) degradation or by modulating APP expression, maturation, or processing. To investigate these possibilities, APP tg mice were treated for 6 months with Cerebrolysin and analyzed in the water maze, followed by RNA, immunoblot, and confocal microscopy analysis of full-length (FL) APP and its fragments, beta-secretase (BACE1), and Abeta-degrading enzymes [neprilysin (Nep) and insulin-degrading enzyme (IDE)]. Consistent with previous studies, Cerebrolysin ameliorated the performance deficits in the spatial learning portion of the water maze and reduced the synaptic pathology and amyloid burden in the brains of APP tg mice. These effects were associated with reduced levels of FL APP and APP C-terminal fragments, but levels of BACE1, Notch1, Nep, and IDE were unchanged. In contrast, levels of active cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3beta [GSK-3beta; but not stress-activated protein kinase-1 (SAPK1)], kinases that phosphorylate APP, were reduced. Furthermore, Cerebrolysin reduced the levels of phosphorylated APP and the accumulation of APP in the neuritic processes. Taken together, these results suggest that Cerebrolysin might reduce AD-like pathology in the APP tg mice by regulating APP maturation and transport to sites where Abeta protein is generated. This study clarifies the mechanisms through which Cerebrolysin might reduce Abeta production and deposition in AD and further supports the importance of this compound in the potential treatment of early AD.

  5. Lipid rafts participate in aberrant degradative autophagic-lysosomal pathway of amyloid-beta peptide in Alzheimer’s disease

    Institute of Scientific and Technical Information of China (English)

    Xin Zhou; Chun Yang; Yufeng Liu; Peng Li; Huiying Yang; Jingxing Dai; Rongmei Qu; Lin Yuan

    2014-01-01

    Amyloid-beta peptide is the main component of amyloid plaques, which are found in Alzhei-mer’s disease. The generation and deposition of amyloid-beta is one of the crucial factors for the onset and progression of Alzheimer’s disease. Lipid rafts are glycolipid-rich liquid domains of the plasma membrane, where certain types of protein tend to aggregate and intercalate. Lipid rafts are involved in the generation of amyloid-beta oligomers and the formation of amyloid-beta peptides. In this paper, we review the mechanism by which lipid rafts disturb the aberrant deg-radative autophagic-lysosomal pathway of amyloid-beta, which plays an important role in the pathological process of Alzheimer’s disease. Moreover, we describe this mechanism from the view of the Two-system Theory of fasciology and thus, suggest that lipid rafts may be a new target of Alzheimer’s disease treatment.

  6. Overexpression of glutaminyl cyclase, the enzyme responsible for pyroglutamate A{beta} formation, induces behavioral deficits, and glutaminyl cyclase knock-out rescues the behavioral phenotype in 5XFAD mice.

    Science.gov (United States)

    Jawhar, Sadim; Wirths, Oliver; Schilling, Stephan; Graubner, Sigrid; Demuth, Hans-Ulrich; Bayer, Thomas A

    2011-02-11

    Pyroglutamate-modified Aβ (AβpE3-42) peptides are gaining considerable attention as potential key players in the pathology of Alzheimer disease (AD) due to their abundance in AD brain, high aggregation propensity, stability, and cellular toxicity. Overexpressing AβpE3-42 induced a severe neuron loss and neurological phenotype in TBA2 mice. In vitro and in vivo experiments have recently proven that the enzyme glutaminyl cyclase (QC) catalyzes the formation of AβpE3-42. The aim of the present work was to analyze the role of QC in an AD mouse model with abundant AβpE3-42 formation. 5XFAD mice were crossed with transgenic mice expressing human QC (hQC) under the control of the Thy1 promoter. 5XFAD/hQC bigenic mice showed significant elevation in TBS, SDS, and formic acid-soluble AβpE3-42 peptides and aggregation in plaques. In 6-month-old 5XFAD/hQC mice, a significant motor and working memory impairment developed compared with 5XFAD. The contribution of endogenous QC was studied by generating 5XFAD/QC-KO mice (mouse QC knock-out). 5XFAD/QC-KO mice showed a significant rescue of the wild-type mice behavioral phenotype, demonstrating the important contribution of endogenous mouse QC and transgenic overexpressed QC. These data clearly demonstrate that QC is crucial for modulating AβpE3-42 levels in vivo and prove on a genetic base the concept that reduction of QC activity is a promising new therapeutic approach for AD.

  7. Effect of graphene oxide on the conformational transitions of amyloid beta peptide: A molecular dynamics simulation study.

    Science.gov (United States)

    Baweja, Lokesh; Balamurugan, Kanagasabai; Subramanian, Venkatesan; Dhawan, Alok

    2015-09-01

    The interactions between nanomaterials (NMs) and amyloid proteins are central to the nanotechnology-based diagnostics and therapy in neurodegenerative disorders such as Alzheimer's and Parkinson's. Graphene oxide (GO) and its derivatives have shown to modulate the aggregation pattern of disease causing amyloid beta (Aβ) peptide. However, the mechanism is still not well understood. Using molecular dynamics simulations, the effect of graphene oxide (GO) and reduced graphene oxide (rGO) having carbon:oxygen ratio of 4:1 and 10:1, respectively, on the conformational transitions (alpha-helix to beta-sheet) and the dynamics of the peptide was investigated. GO and rGO decreased the beta-strand propensity of amino acid residues in Aβ. The peptide displayed different modes of adsorption on GO and rGO. The adsorption on GO was dominated by electrostatic interactions, whereas on rGO, both van der Waals and electrostatic interactions contributed in the adsorption of the peptide. Our study revealed that the slight increase in the hydrophobic patches on rGO made it more effective inhibitor of conformational transitions in the peptide. Alpha helix-beta sheet transition in Aβ peptide could be one of the plausible mechanism by which graphene oxide may inhibit amyloid fibrillation.

  8. "Clicked" bivalent ligands containing curcumin and cholesterol as multifunctional abeta oligomerization inhibitors: design, synthesis, and biological characterization.

    Science.gov (United States)

    Lenhart, James A; Ling, Xiao; Gandhi, Ronak; Guo, Tai L; Gerk, Phillip M; Brunzell, Darlene H; Zhang, Shijun

    2010-08-26

    In our effort to develop multifunctional compounds that cotarget beta-amyloid oligomers (AbetaOs), cell membrane/lipid rafts (CM/LR), and oxidative stress, a series of bivalent multifunctional Abeta oligomerization inhibitors (BMAOIs) containing cholesterol and curcumin were designed, synthesized, and biologically characterized as potential treatments for Alzheimer's disease (AD). The in vitro assay results established that the length of spacer that links cholesterol and curcumin and the attaching position of the spacer on curcumin are important structural determinants for their biological activities. Among the BMAOIs tested, 14 with a 21-atom-spacer was identified to localize to the CM/LR of human neuroblastoma MC65 cells, to inhibit the formation of AbetaOs in MC65 cells, to protect cells from AbetaOs-induced cytotoxicity, and to retain antioxidant properties of curcumin. Furthermore, 14 was confirmed to have the potential to cross the blood-brain barrier (BBB) as demonstrated in a Caco-2 cell model. Collectively, these results strongly encourage further optimization of 14 as a new hit to develop more potent BMAOIs.

  9. The effect of beta-turn structure on the permeation of peptides across monolayers of bovine brain microvessel endothelial cells

    DEFF Research Database (Denmark)

    Sorensen, M; Steenberg, B; Knipp, G T;

    1997-01-01

    PURPOSE: To investigate the effects of the beta-turn structure of a peptide on its permeation via the paracellular and transcellular routes across cultured bovine brain microvessel endothelial cell (BBMEC) monolayers, an in vitro model of the blood-brain barrier (BBB). METHODS: The effective...... permeability coefficients (Peff) of the model peptides were determined across BBMEC monolayers. The dimensions of the aqueous pores in the tight junctions (TJs) of the BBMEC monolayers were determined using a series of hydrophilic permeants. This value and the molecular radius of each peptide were used...... to calculate the theoretical paracellular (PP*) and transcellular (PT*) permeability coefficients for each peptide. RESULTS: A comparison of the theoretical PP* values with the observed Peff values was made for a series of model peptides. For the most hydrophobic peptides (Ac-PheProXaaIle-NH2 and Ac...

  10. Molecular cloning and expression of gene fragments from corynebacteriophage beta encoding enzymatically active peptides of diphtheria toxin.

    OpenAIRE

    Tweten, R K; Collier, R J

    1983-01-01

    Two restriction fragments from corynebacteriophage beta vir tox+ that encode peptides similar to diphtheria toxin fragment A and the chain termination fragment, CRM45, have been cloned into Escherichia coli in plasmid pBR322. Clones containing the recombinant plasmids produced gene products that were active in catalyzing the ADP ribosylation of elongation factor 2 and were reactive with diphtheria toxin antiserum. Toxin-related peptides were found primarily in the periplasmic compartment and ...

  11. Ginkgo biloba extract ameliorates oxidative phosphorylation performance and rescues abeta-induced failure.

    Directory of Open Access Journals (Sweden)

    Virginie Rhein

    Full Text Available BACKGROUND: Energy deficiency and mitochondrial failure have been recognized as a prominent, early event in Alzheimer's disease (AD. Recently, we demonstrated that chronic exposure to amyloid-beta (Abeta in human neuroblastoma cells over-expressing human wild-type amyloid precursor protein (APP resulted in (i activity changes of complexes III and IV of the oxidative phosphorylation system (OXPHOS and in (ii a drop of ATP levels which may finally instigate loss of synapses and neuronal cell death in AD. Therefore, the aim of the present study was to investigate whether standardized Ginkgo biloba extract LI 1370 (GBE is able to rescue Abeta-induced defects in energy metabolism. METHODOLOGY/PRINCIPAL FINDINGS: We used a high-resolution respiratory protocol to evaluate OXPHOS respiratory capacity under physiological condition in control (stably transfected with the empty vector and APP cells after treatment with GBE. In addition, oxygen consumption of isolated mitochondria, activities of mitochondrial respiratory enzymes, ATP and reactive oxygen species (ROS levels as well as mitochondrial membrane mass and mitochondrial DNA content were determined. We observed a general antioxidant effect of GBE leading to an increase of the coupling state of mitochondria as well as energy homeostasis and a reduction of ROS levels in control cells and in APP cells. GBE effect on OXPHOS was even preserved in mitochondria after isolation from treated cells. Moreover, these functional data were paralleled by an up-regulation of mitochondrial DNA. Improvement of the OXPHOS efficiency was stronger in APP cells than in control cells. In APP cells, the GBE-induced amelioration of oxygen consumption most likely arose from the modulation and respective normalization of the Abeta-induced disturbance in the activity of mitochondrial complexes III and IV restoring impaired ATP levels possibly through decreasing Abeta and oxidative stress level. CONCLUSIONS

  12. Identification of a novel angiotensin-I-converting enzyme inhibitory peptide corresponding to a tryptic fragment of bovine beta-lactoglobulin.

    Science.gov (United States)

    Mullally, M M; Meisel, H; FitzGerald, R J

    1997-02-01

    The angiotensin-I-converting enzyme (ACE) inhibitory activity of a tryptic digest of bovine beta-lactoglobulin (beta-lg) was investigated. Intact beta-lg essentially did not inhibit ACE while the tryptic digest gave an 84.3% inhibition of ACE. Peptide material eluting between 20 and 25% acetonitrile during C18 solid-phase extraction of the beta-lg tryptic digest inhibited ACE by 93.6%. This solid-phase extraction fraction was shown by mass spectroscopy to contain beta-lg f(142-148). This peptide had an ACE IC50 value of 42.6 micromol/l. The peptide was resistant to further digestion with pepsin and was hydrolysed to a very low extent with chymotrypsin. The contribution of specific amino acid residues within the peptide to ACE inhibitory activity and the potential application of this peptide as a nutraceutical is discussed.

  13. Differentiation of Boc-protected alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptide positional isomers by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Raju, G; Ramesh, V; Srinivas, R; Sharma, G V M; Shoban Babu, B

    2010-06-01

    Two new series of Boc-N-alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptides containing repeats of L-Ala-delta(5)-Caa/delta(5)-Caa-L-Ala and beta(3)-Caa-delta(5)-Caa/delta(5)-Caa-beta(3)-Caa (L-Ala = L-alanine, Caa = C-linked carbo amino acid derived from D-xylose) have been differentiated by both positive and negative ion electrospray ionization (ESI) ion trap tandem mass spectrometry (MS/MS). MS(n) spectra of protonated isomeric peptides produce characteristic fragmentation involving the peptide backbone, the Boc-group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated peptides. The loss of 2-methylprop-1-ene is more pronounced for Boc-NH-L-Ala-delta-Caa-OCH(3) (1), whereas it is totally absent for its positional isomer Boc-NH-delta-Caa-L-Ala-OCH(3) (7), instead it shows significant loss of t-butanol. On the other hand, second isomeric pair shows significant loss of t-butanol and loss of acetone for Boc-NH-delta-Caa-beta-Caa-OCH(3) (18), whereas these are insignificant for its positional isomer Boc-NH-beta-Caa-delta-Caa-OCH(3) (13). The tetra- and hexapeptide positional isomers also show significant differences in MS(2) and MS(3) CID spectra. It is observed that 'b' ions are abundant when oxazolone structures are formed through five-membered cyclic transition state and cyclization process for larger 'b' ions led to its insignificant abundance. However, b(1)(+) ion is formed in case of delta,alpha-dipeptide that may have a six-membered substituted piperidone ion structure. Furthermore, ESI negative ion MS/MS has also been found to be useful for differentiating these isomeric peptide acids. Thus, the results of MS/MS of pairs of di-, tetra-, and hexapeptide positional isomers provide peptide sequencing information and distinguish the positional isomers.

  14. Protein kinase C betaII peptide inhibitor exerts cardioprotective effects in rat cardiac ischemia/reperfusion injury.

    Science.gov (United States)

    Omiyi, Didi; Brue, Richard J; Taormina, Philip; Harvey, Margaret; Atkinson, Norrell; Young, Lindon H

    2005-08-01

    Ischemia followed by reperfusion (I/R) in the presence of polymorphonuclear leukocytes (PMNs) results in a marked cardiac contractile dysfunction. A cell-permeable protein kinase C (PKC) betaII peptide inhibitor was used to test the hypothesis that PKC betaII inhibition could attenuate PMN-induced cardiac dysfunction by suppression of superoxide production from PMNs and increase NO release from vascular endothelium. The effects of the PKC betaII peptide inhibitor were examined in isolated ischemic (20 min) and reperfused (45 min) rat hearts with PMNs. The PKC betaII inhibitor (10 microM; n = 7) significantly attenuated PMN-induced cardiac dysfunction compared with I/R hearts (n = 9) receiving PMNs alone in left ventricular developed pressure (LVDP) and the maximal rate of LVDP (+dP/dt(max)) cardiac function indices (p < 0.01). The PKC betaII inhibitor at 10 microM significantly increased endothelial NO release from a basal value of 1.85 +/- 0.18 pmol NO/mg tissue to 3.49 +/- 0.62 pmol NO/mg tissue from rat aorta. It also significantly inhibited superoxide release (i.e., absorbance) from N-formyl-L-methionyl-L-leucyl-L-phenylalanine-stimulated rat PMNs from 0.13 +/- 0.01 to 0.02 +/- 0.004 (p < 0.01) at 10 microM. Histological analysis of the left ventricle of representative rat hearts from each group showed that the PKC betaII peptide inhibitor-treated hearts experienced a marked reduction in PMN vascular adherence and infiltration into the postreperfused cardiac tissue compared with I/R + PMN hearts (p < 0.01). These results suggest that the PKC betaII peptide inhibitor attenuates PMN-induced post-I/R cardiac contractile dysfunction by increasing endothelial NO release and by inhibiting superoxide release from PMNs. PMID:15878997

  15. Molecular dynamics simulation of {beta}-sheet formation in self-assembled peptide amphiphile fibers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, One-Sun; Liu Yamei; Schatz, George C., E-mail: schatz@chem.northwestern.edu [Northwestern University, Department of Chemistry (United States)

    2012-08-15

    The influence of amino acid sequence on the secondary structure of peptide amphiphile (PAs) cylindrical micelles and fibers that are self-assembled in solution is studied using molecular dynamics simulations. Simulations for two choices of PAs were performed, starting with structures that have the correct overall shape, but which restructure considerably during the simulation, with one fiber being composed of valine rich PAs and the other of alanine rich PAs. Self-assembly is similar in both simulations, with stable fibers (diameter is 7.7-8 nm) obtained after 40 ns. We find that the valine rich PA fiber has a higher {beta}-sheet population than the alanine rich fiber, and that the number of hydrogen bonds is higher. This behavior of the valine rich fiber is consistent with experimental measurements of higher stiffness, and it shows that stiffness can be varied while still maintaining self-assembly.

  16. Cholesterol enhances amyloid {beta} deposition in mouse retina by modulating the activities of A{beta}-regulating enzymes in retinal pigment epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiying [Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Ohno-Matsui, Kyoko, E-mail: k.ohno.oph@tmd.ac.jp [Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Morita, Ikuo [Section of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan)

    2012-08-10

    Highlights: Black-Right-Pointing-Pointer Cholesterol-treated RPE produces more A{beta} than non-treated RPE. Black-Right-Pointing-Pointer Neprilysin expression and activity decreased in cholesterol-treated RPE. Black-Right-Pointing-Pointer {alpha}-Secretase expression and activity decreased in cholesterol-treated RPE. Black-Right-Pointing-Pointer Cholesterol-enriched diet induced subRPE deposits in aged mice. Black-Right-Pointing-Pointer A{beta} were present in cholesterol-enriched-diet-induced subRPE deposits in aged mice. -- Abstract: Subretinally-deposited amyloid {beta} (A{beta}) is a main contributor of developing age-related macular degeneration (AMD). However, the mechanism causing A{beta} deposition in AMD eyes is unknown. Hypercholesterolemia is a significant risk for developing AMD. Thus, we investigated the effects of cholesterol on A{beta} production in retinal pigment epithelial (RPE) cells in vitro and in the mouse retina in vivo. RPE cells isolated from senescent (12-month-old) C57BL/6 mice were treated with 10 {mu}g/ml cholesterol for 48 h. A{beta} amounts in culture supernatants were measured by ELISA. Activity and expression of enzymes and proteins that regulate A{beta} production were examined by activity assay and real time PCR. The retina of mice fed cholesterol-enriched diet was examined by transmission electron microscopy. Cholesterol significantly increased A{beta} production in cultured RPE cells. Activities of A{beta} degradation enzyme; neprilysin (NEP) and anti-amyloidogenic secretase; {alpha}-secretase were significantly decreased in cell lysates of cholesterol-treated RPE cells compared to non-treated cells, but there was no change in the activities of {beta}- or {gamma}-secretase. mRNA levels of NEP and {alpha}-secretase (ADAM10 and ADAM17) were significantly lower in cholesterol-treated RPE cells than non-treated cells. Senescent (12-month-old) mice fed cholesterol-enriched chow developed subRPE deposits containing A{beta}, whereas

  17. PET imaging of alpha(v)beta(3) integrin expression in tumours with Ga-68-labelled mono-, di- and tetrameric RGD peptides

    NARCIS (Netherlands)

    Dijkgraaf, Ingrid; Yim, Cheng-Bin; Franssen, Gerben M.; Schuit, Robert C.; Luurtsema, Gert; Liu, Shuang; Oyen, Wim J. G.; Boerman, Otto C.

    2011-01-01

    Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3)-binding characteristics of Ga-68-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their I

  18. Scutellaria baicalensis stem-leaf total flavonoid reduces neuronal apoptosis induced by amyloid beta-peptide (25-35)

    Institute of Scientific and Technical Information of China (English)

    Ruiting Wang; Xingbin Shen; Enhong Xing; Lihua Guan; Lisheng Xin

    2013-01-01

    Scutellaria baicalensis stem-leaf total flavonoid might attenuate learning/memory impairment and neuronal loss in rats induced by amyloid beta-peptide. This study aimed to explore the effects of Scutellaria baicalensis stem-leaf total flavonoid on amyloid beta-peptide-induced neuronal apoptosis and the expression of apoptosis-related proteins in the rat hippocampus. Male Wistar rats were given intragastric administration of Scutellaria baicalensis stem-leaf total flavonoid, 50 or 100 mg/kg, once per day. On day 8 after administration, 10 μg amyloid beta-peptide (25–35) was injected into the bilateral hippocampus of rats to induce neuronal apoptosis. On day 20, hippocampal tissue was harvested and probed with the terminal deoxyribonucleotidyl transferase-mediated biotin-16-dUTP nick-end labeling assay. Scutellaria baicalensis stem-leaf total flavonoid at 50 and 100 mg/kg reduced neuronal apoptosis induced by amyloid beta-peptide (25–35) in the rat hippocampus. Immunohistochemistry and western blot assay revealed that expression of the pro-apoptotic protein Bax, cytochrome c and caspase-3 was significantly diminished by 50 and 100 mg/kg Scutellaria baicalensis stem-leaf total flavonoid, while expression of the anti-apoptotic protein Bcl-2 was increased. Moreover, 100 mg/kg Scutellaria baicalensis stem-leaf total flavonoid had a more dramatic effect than the lower dosage. These experimental findings indicate that Scutellaria baicalensis stem-leaf total flavonoid dose-dependently attenuates neuronal apoptosis induced by amyloid beta-peptide in the hippocampus, and it might mediate this by regulating the expression of Bax, cytochrome c, caspase-3 and Bcl-2.

  19. Cerebral microvascular amyloid beta protein deposition induces vascular degeneration and neuroinflammation in transgenic mice expressing human vasculotropic mutant amyloid beta precursor protein.

    NARCIS (Netherlands)

    Miao, J.; Xu, F.; Davis, J.; Otte-Holler, I.; Verbeek, M.M.; Nostrand, W.E. van

    2005-01-01

    Cerebral vascular amyloid beta-protein (Abeta) deposition, also known as cerebral amyloid angiopathy, is a common pathological feature of Alzheimer's disease. Additionally, several familial forms of cerebral amyloid angiopathy exist including the Dutch (E22Q) and Iowa (D23N) mutations of Abeta. Incr

  20. C-peptide reverses TGF-beta1-induced changes in renal proximal tubular cells: implications for treatment of diabetic nephropathy.

    Science.gov (United States)

    Hills, Claire E; Al-Rasheed, Nawal; Al-Rasheed, Nouf; Willars, Gary B; Brunskill, Nigel J

    2009-03-01

    The crucial pathology underlying progressive chronic kidney disease in diabetes is tubulointerstitial fibrosis. Central to this process is epithelial-mesenchymal transformation (EMT) of proximal tubular epithelial cells driven by maladaptive transforming growth factor-beta1 (TGF-beta1) signaling. Novel signaling roles for C-peptide have recently been discovered with evidence emerging that C-peptide may mitigate microvascular complications of diabetes. We studied the potential for C-peptide to interrupt injurious TGF-beta1 signaling pathways and thus block development of EMT in HK2 human kidney proximal tubular cells. Cells were incubated with TGF-beta1 either alone or with C-peptide in low or high glucose. Changes in cell morphology, TGF-beta1 receptor expression, vimentin, E-cadherin, and phosphorylated Smads were assessed. Luciferase reporters were used to assess Smad activity. The cytoskeleton was visualized by TRITC-phalloidin staining. The typical TGF-beta1-stimulated, EMT-associated morphological alterations of proximal tubular cells, including increased vimentin expression, decreased E-cadherin expression, and cytoskeletal rearrangements, were prevented by C-peptide treatment. C-peptide also blocked TGF-beta1-induced upregulation of expression of both type I and type II TGF-beta1 receptors and attenuated TGF-beta1-mediated Smad phosphorylation and Smad transcriptional activity. These effects of C-peptide were inhibited by pertussis toxin. The results demonstrate that C-peptide almost completely reversed the morphological changes in PT cells induced by TGF-beta1 and suggest a role or C-peptide as a renoprotective agent in diabetic nephropathy. PMID:19091788

  1. Parathyroid Hormone-Related Peptide (1-36) Enhances Beta Cell Regeneration and Increases Beta Cell Mass in a Mouse Model of Partial Pancreatectomy

    Science.gov (United States)

    Mozar, Anaïs; Lin, Hugo; Williams, Katoura; Chin, Connie; Li, Rosemary; Kondegowda, Nagesha Guthalu; Stewart, Andrew F.; Garcia-Ocaña, Adolfo; Vasavada, Rupangi Chhaya

    2016-01-01

    Aims/Hypothesis Finding ways to stimulate the regeneration of endogenous pancreatic beta cells is an important goal in the treatment of diabetes. Parathyroid hormone-related protein (PTHrP), the full-length (1–139) and amino-terminal (1–36) peptides, enhance beta cell function, proliferation, and survival. Therefore, we hypothesize that PTHrP(1–36) has the potential to regenerate endogenous beta cells. Methods The partial pancreatectomy (PPx) mouse model of beta cell injury was used to test this hypothesis. Male Balb/c mice underwent either sham-operation or PPx, and were subsequently injected with PTHrP(1–36) (160μg/kg) or vehicle (veh), for 7, 30, or 90 days. The four groups of mice, sham-veh, sham-PTHrP, PPx-veh, and PPx-PTHrP were assessed for PTHrP and receptor expression, and glucose and beta cell homeostasis. Results PTHrP-receptor, but not the ligand, was significantly up-regulated in islets from mice that underwent PPx compared to sham-operated mice. This suggests that exogenous PTHrP could further enhance beta cell regeneration after PPx. PTHrP did not significantly affect body weight, blood glucose, plasma insulin, or insulin sensitivity, in either sham or PPx mice. Glucose tolerance improved in the PPx-PTHrP versus PPx-veh mice only in the early stages of treatment. As hypothesized, there was a significant increase in beta cell proliferation in PPx-PTHrP mice at days 7 and 30; however, this was normalized by day 90, compared to PPx-veh mice. Enhanced beta cell proliferation translated to a marked increase in beta cell mass at day 90, in PPx-PTHrP versus PPx-veh mice. Conclusions PTHrP(1–36) significantly enhances beta cell regeneration through increased beta cell proliferation and beta cell mass after PPx. Future studies will determine the potential of PTHrP to enhance functional beta cell mass in the setting of diabetes. PMID:27391423

  2. A Simulation Model of Periarterial Clearance of Amyloid-beta from the Brain

    Directory of Open Access Journals (Sweden)

    Alexandra Katharina Diem

    2016-02-01

    Full Text Available The accumulation of soluble and insoluble amyloid-beta (A-beta in the brain indicates failure of elimination of A-beta from the brain with age and Alzheimer's disease. There is a variety of mechanisms for elimination of A-beta from the brain. They include the action of microglia and enzymes together with receptor-mediated absorption of A-beta into the blood and periarterial lymphatic drainage of A-beta. Although the brain possesses no conventional lymphatics, experimental studies have shown that fluid and solutes, such as A-beta, are eliminated from the brain along 100 nm wide basement membranes in the walls of cerebral capillaries and arteries. This lymphatic drainage pathway is reflected in the deposition of A-beta in the walls of human arteries with age and Alzheimer's disease as cerebral amyloid angiopathy (CAA. Initially, A-beta diffuses through the extracellular spaces of grey matter in the brain and then enters basement membranes in capillaries and arteries to flow out of the brain. Although diffusion through the extracellular spaces of the brain has been well characterised, the exact mechanism whereby perivascular elimination of A-beta occurs has not been resolved. Here we use a computational model to describe the process of periarterial drainage in the context of diffusion in the brain, demonstrating that periarterial drainage along basement membranes is very rapid compared with diffusion. Our results are a validation of experimental data and are significant in the context of failure of periarterial drainage as a mechanism underlying the pathogenesis of AD as well as complications associated with its immunotherapy.

  3. Proinsulin C-peptide antagonizes the profibrotic effects of TGF-beta1 via up-regulation of retinoic acid and HGF-related signaling pathways.

    Science.gov (United States)

    Hills, Claire E; Willars, Gary B; Brunskill, Nigel J

    2010-04-01

    Novel signaling roles for C-peptide have recently been discovered with evidence that it can ameliorate complications of type 1 diabetes. Here we sought to identify new pathways regulated by C-peptide of relevance to the pathophysiology of diabetic nephropathy. Microarray analysis was performed to identify genes regulated by either C-peptide and/or TGF-beta1 in a human proximal tubular cell line, HK-2. Expression of retinoic acid receptor beta (RARbeta), hepatocyte growth factor (HGF), cellular retinoic acid-binding protein II (CRABPII), vimentin, E-cadherin, Snail, and beta-catenin was assessed by immunoblotting. The cellular localization of vimentin and beta-catenin was determined by immunocytochemistry. Changes in cell morphology were assessed by phase contrast microscopy. Gene expression profiling demonstrated differential expression of 953 and 1458 genes after C-peptide exposure for 18 h or 48 h, respectively. From these, members of the antifibrotic retinoic acid (RA)- and HGF-signaling pathways were selected. Immunoblotting demonstrated that C-peptide increased RARbeta, CRABPII, and HGF. We confirmed a role for RA in reversal of TGF-beta1-induced changes associated with epithelial-mesenchymal transition, including expression changes in Snail, E-cadherin, vimetin, and redistribution of beta-catenin. Importantly, these TGF-beta1-induced changes were inhibited by C-peptide. Further, effects of TGF-beta1 on Snail and E-cadherin expression were blocked by HGF, and inhibitory effects of C-peptide were removed by blockade of HGF activity. This study identifies a novel role for HGF as an effector of C-peptide, possibly via an RA-signaling pathway, highlighting C-peptide as a potential therapy for diabetic nephropathy. PMID:20197308

  4. Aloe arborescens Extract Protects IMR-32 Cells against Alzheimer Amyloid Beta Peptide via Inhibition of Radical Peroxide Production.

    Science.gov (United States)

    Clementi, Maria Elisabetta; Tringali, Giuseppe; Triggiani, Doriana; Giardina, Bruno

    2015-11-01

    Aloe arborescens is commonly used as a pharmaceutical ingredient for its effect in burn treatment and ability to increase skin wound healing properties. Besides, it is well known to have beneficial phytotherapeutic, anticancer, and radio-protective properties. In this study, we first provided evidence that A. arborescens extract protects IMR32, a neuroblastoma human cellular line, from toxicity induced by beta amyloid, the peptide responsible for Alzheimer's disease. In particular, pretreatment with A. arborescens maintains an elevated cell viability and exerts a protective effect on mitochondrial functionality, as evidenced by oxygen consumption experiments. The protective mechanism exerted by A. arborescens seems be related to lowering of oxidative potential of the cells, as demonstrated by the ROS measurement compared with the results obtained in the presence of amyloid beta (1-42) peptide alone. Based on these preliminary observations we suggest that use ofA. arborescens extract could be developed as agents for the management of AD. PMID:26749845

  5. Elevation in sphingomyelin synthase activity is associated with increases in amyloid-beta peptide generation.

    Directory of Open Access Journals (Sweden)

    Jen-Hsiang T Hsiao

    Full Text Available A pathological hallmark of Alzheimer's disease (AD is the presence of amyloid-beta peptide (Aβ plaques in the brain. Aβ is derived from a sequential proteolysis of the transmenbrane amyloid precursor protein (APP, a process which is dependent on the distribution of lipids present in the plasma membrane. Sphingomyelin is a major membrane lipid, however its role in APP processing is unclear. Here, we assessed the expression of sphingomyelin synthase (SGMS1; the gene responsible for sphingomyelin synthesis in human brain and found that it was significantly elevated in the hippocampus of AD brains, but not in the cerebellum. Secondly, we assessed the impact of altering SGMS activity on Aβ generation. Inhibition of SGMS activity significantly reduced the level of Aβ in a dose- and time dependent manner. The decrease in Aβ level occurred without changes in APP expression or cell viability. These results when put together indicate that SGMS activity impacts on APP processing to produce Aβ and it could be a contributing factor in Aβ pathology associated with AD.

  6. Inhibitory Effect of Curcumin-Cu(II) and Curcumin-Zn(II) Complexes on Amyloid-Beta Peptide Fibrillation

    OpenAIRE

    Rona Banerjee

    2014-01-01

    Mononuclear complexes of Curcumin with Cu(II) and Zn(II) have been synthesized and, characterized and their effects on the fibrillization and aggregation of amyloid-beta (Aβ) peptide have been studied. FTIR spectroscopy and atomic force microscopy (AFM) observations demonstrate that the complexes can inhibit the transition from less structured oligomers to β-sheet rich protofibrils which act as seeding factors for further fibrillization. The metal complexes also impart more improved inhibitor...

  7. Improved targeting of the alpha(v)beta (3) integrin by multimerisation of RGD peptides.

    NARCIS (Netherlands)

    Dijkgraaf, I.; Kruijtzer, J.A.; Liu, S.; Soede, A.C.; Oyen, W.J.G.; Corstens, F.H.M.; Liskamp, R.M.; Boerman, O.C.

    2007-01-01

    PURPOSE: The integrin alpha(v)beta(3) is expressed on sprouting endothelial cells and on various tumour cell types. Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3) binding charac

  8. Molecular dynamics simulation and molecular docking studies of Angiotensin converting enzyme with inhibitor lisinopril and amyloid Beta Peptide.

    Science.gov (United States)

    Jalkute, Chidambar Balbhim; Barage, Sagar Hindurao; Dhanavade, Maruti Jayram; Sonawane, Kailas Dasharath

    2013-06-01

    Angiotensin converting enzyme (ACE) cleaves amyloid beta peptide. So far this cleavage mechanism has not been studied in detail at atomic level. Keeping this view in mind, we performed molecular dynamics simulation of crystal structure complex of testis truncated version of ACE (tACE) and its inhibitor lisinopril along with Zn(2+) to understand the dynamic behavior of active site residues of tACE. Root mean square deviation results revealed the stability of tACE throughout simulation. The residues Ala 354, Glu 376, Asp 377, Glu 384, His 513, Tyr 520 and Tyr 523 of tACE stabilized lisinopril by hydrogen bonding interactions. Using this information in subsequent part of study, molecular docking of tACE crystal structure with Aβ-peptide has been made to investigate the interactions of Aβ-peptide with enzyme tACE. The residues Asp 7 and Ser 8 of Aβ-peptide were found in close contact with Glu 384 of tACE along with Zn(2+). This study has demonstrated that the residue Glu 384 of tACE might play key role in the degradation of Aβ-peptide by cleaving peptide bond between Asp 7 and Ser 8 residues. Molecular basis generated by this attempt could provide valuable information towards designing of new therapies to control Aβ concentration in Alzheimer's patient.

  9. Nonstereogenic alpha-aminoisobutyryl-glycyl dipeptidyl unit nucleates type I' beta-turn in linear peptides in aqueous solution.

    Science.gov (United States)

    Masterson, Larry R; Etienne, Marcus A; Porcelli, Fernando; Barany, George; Hammer, Robert P; Veglia, Gianluigi

    2007-01-01

    The use of alpha,alpha-disubstituted amino acids represents a valuable strategy to exercise conformational control in peptides. Incorporation of the nonstereogenic alpha-aminoisobutyryl-glycyl (Aib-Gly) dipeptidyl sequence into i+1 and i+2 positions of an acyclic peptide sequence, originally designed and investigated by Gellman and coworkers, [H-Arg-Tyr-Val-Glu-Val-Yyy-Xxx-Orn-Lys-Ile-Leu-Gln-NH2] nucleates a stable [2:4] left-handed type I' beta-turn in water. NMR spectra show that this newly designed beta-hairpin does not aggregate in water up to a concentration of approximately 1 mM, and that its backbone conformation is superimposable on corresponding hairpins containing the DPro-Gly (literature) and Aib-DAla (this work) sequences. The Aib-Gly turn-inducer sequence eliminates complications because of cis-trans isomerization of Zzz-Pro bonds, and constitutes an attractive alternative to the proteogenic Asn-Gly and nonproteogenic DPro-Gly motifs previously suggested as turn-inducer sequences. These design principles could be exploited to prepare water-soluble beta-hairpin peptides with robust structures and novel function. PMID:17427180

  10. Apolipoprotein E modulates Alzheimer's Abeta(1-42)-induced oxidative damage to synaptosomes in an allele-specific manner.

    Science.gov (United States)

    Lauderback, Christopher M; Kanski, Jaroslaw; Hackett, Janna M; Maeda, Noboyo; Kindy, Mark S; Butterfield, D Allan

    2002-01-01

    Several functional differences have been reported among the three human e2, e3, and e4 alleles of apolipoprotein E (apoE). One functional difference lies in the antioxidant potential of these alleles; e4 has the poorest potential. Interestingly, e4 also correlates with increased oxidative damage in the Alzheimer's disease (AD) brain, which may explain why the inheritance of the e4 allele is a risk factor for the onset of AD. Beta-amyloid (Abeta) is also intimately involved in AD and promotes oxidative damage in vitro; therefore, we have examined the role of the different apoE alleles in modulating Abeta(1-42)-induced oxidation to synaptosomes. Measurement of specific markers of oxidation in synaptosomes isolated from mice that express one of the human apoE alleles indicates that Abeta-induced increases of these markers can be modulated by apoE in an allele-dependent manner (e2>e3>e4). Increases in reactive oxygen species formation and protein and lipid oxidation were always greatest in e4 synaptosomes as compared to e2 and e3 synaptosomes. Our data support the role of apoE as a modulator of Abeta toxicity and, consistent with the antioxidant potentials of the three alleles, suggest that the e4 allele may not be as effective in this role as the e2 or e3 alleles of apoE. These results are discussed with reference to mechanistic implications for neurodegeneration in the AD brain.

  11. Targeted correction of a thalassemia-associated beta-globin mutation induced by pseudo-complementary peptide nucleic acids

    DEFF Research Database (Denmark)

    Lonkar, Pallavi; Kim, Ki-Hyun; Kuan, Jean Y;

    2009-01-01

    Beta-thalassemia is a genetic disorder caused by mutations in the beta-globin gene. Triplex-forming oligonucleotides and triplex-forming peptide nucleic acids (PNAs) have been shown to stimulate recombination in mammalian cells via site-specific binding and creation of altered helical structures...... that provoke DNA repair. However, the use of these molecules for gene targeting requires homopurine tracts to facilitate triple helix formation. Alternatively, to achieve binding to mixed-sequence target sites for the induced gene correction, we have used pseudo-complementary PNAs (pcPNAs). Due to steric...... hindrance, pcPNAs are unable to form pcPNA-pcPNA duplexes but can bind to complementary DNA sequences via double duplex-invasion complexes. We demonstrate here that pcPNAs, when co-transfected with donor DNA fragments, can promote single base pair modification at the start of the second intron of the beta...

  12. How can a beta-sheet peptide be both a potent antimicrobial and harmfully toxic? Molecular dynamics simulations of protegrin-1 in micelles

    DEFF Research Database (Denmark)

    Langham, Allison A; Khandelia, Himanshu; Kaznessis, Yiannis N

    2006-01-01

    In this work, the naturally occurring beta-hairpin antimicrobial peptide protegrin-1 (PG-1) is studied by molecular dynamics simulation in all-atom sodium dodecylsulfate and dodecylphosphocholine micelles. These simulations provide a high-resolution picture of the interactions between the peptide...

  13. Abeta-induced meningoencephalitis is IFN-gamma-dependent and is associated with T cell-dependent clearance of Abeta in a mouse model of Alzheimer's disease

    DEFF Research Database (Denmark)

    Monsonego, Alon; Imitola, Jaime; Petrovic, Sanja;

    2006-01-01

    an myelin basic protein (MBP) promoter. Furthermore, immune infiltrates were targeted primarily to sites of Abeta plaques in the brain and were associated with clearance of Abeta. Immune infiltrates were not targeted to the spinal cord, consistent with what was observed in AD patients vaccinated with Abeta...... epitope and that epitopes differ depending on MHC genetic background. Moreover, we show that a single immunization with the dominant T cell epitope Abeta10-24 induced transient meningoencephalitis only in amyloid precursor protein (APP)-transgenic (Tg) mice expressing limited amounts of IFN-gamma under...

  14. Mechanism of neuronal versus endothelial cell uptake of Alzheimer's disease amyloid beta protein.

    Directory of Open Access Journals (Sweden)

    Karunya K Kandimalla

    Full Text Available Alzheimer's disease (AD is characterized by significant neurodegeneration in the cortex and hippocampus; intraneuronal tangles of hyperphosphorylated tau protein; and accumulation of beta-amyloid (Abeta proteins 40 and 42 in the brain parenchyma as well as in the cerebral vasculature. The current understanding that AD is initiated by the neuronal accumulation of Abeta proteins due to their inefficient clearance at the blood-brain-barrier (BBB, places the neurovascular unit at the epicenter of AD pathophysiology. The objective of this study is to investigate cellular mechanisms mediating the internalization of Abeta proteins in the principle constituents of the neurovascular unit, neurons and BBB endothelial cells. Laser confocal micrographs of wild type (WT mouse brain slices treated with fluorescein labeled Abeta40 (F-Abeta40 demonstrated selective accumulation of the protein in a subpopulation of cortical and hippocampal neurons via nonsaturable, energy independent, and nonendocytotic pathways. This groundbreaking finding, which challenges the conventional belief that Abeta proteins are internalized by neurons via receptor mediated endocytosis, was verified in differentiated PC12 cells and rat primary hippocampal (RPH neurons through laser confocal microscopy and flow cytometry studies. Microscopy studies have demonstrated that a significant proportion of F-Abeta40 or F-Abeta42 internalized by differentiated PC12 cells or RPH neurons is located outside of the endosomal or lysosomal compartments, which may accumulate without degradation. In contrast, BBME cells exhibit energy dependent uptake of F-Abeta40, and accumulate the protein in acidic cell organelle, indicative of endocytotic uptake. Such a phenomenal difference in the internalization of Abeta40 between neurons and BBB endothelial cells may provide essential clues to understanding how various cells can differentially regulate Abeta proteins and help explain the vulnerability of cortical

  15. Correction of a splice-site mutation in the beta-globin gene stimulated by triplex-forming peptide nucleic acids

    OpenAIRE

    Chin, Joanna Y; Kuan, Jean Y.; Lonkar, Pallavi S.; Krause, Diane S.; Seidman, Michael M.; Peterson, Kenneth R.; Nielsen, Peter E.; Kole, Ryszard; Glazer, Peter M.

    2008-01-01

    Splice-site mutations in the beta-globin gene can lead to aberrant transcripts and decreased functional beta-globin, causing beta-thalassemia. Triplex-forming DNA oligonucleotides (TFOs) and peptide nucleic acids (PNAs) have been shown to stimulate recombination in reporter gene loci in mammalian cells via site-specific binding and creation of altered helical structures that provoke DNA repair. We have designed a series of triplex-forming PNAs that can specifically bind to sequences in the hu...

  16. Improved targeting of the {alpha}{sub v}{beta}{sub 3} integrin by multimerisation of RGD peptides

    Energy Technology Data Exchange (ETDEWEB)

    Dijkgraaf, Ingrid [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Utrecht University, Department of Medicinal Chemistry, Utrecht Institute for Pharmaceutical Sciences, P.O. Box 80082, Utrecht (Netherlands); Kruijtzer, John A.W.; Liskamp, Rob M.J. [Utrecht University, Department of Medicinal Chemistry, Utrecht Institute for Pharmaceutical Sciences, P.O. Box 80082, Utrecht (Netherlands); Liu, Shuang [Purdue University, School of Health Sciences, West Lafayette, IN (United States); Soede, Annemieke C.; Oyen, Wim J.G.; Corstens, Frans H.M.; Boerman, Otto C. [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands)

    2007-02-15

    The integrin {alpha}{sub v}{beta}{sub 3} is expressed on sprouting endothelial cells and on various tumour cell types. Due to the restricted expression of {alpha}{sub v}{beta}{sub 3} in tumours, {alpha}{sub v}{beta}{sub 3} is considered a suitable receptor for tumour targeting. In this study the {alpha}{sub v}{beta}{sub 3} binding characteristics of an {sup 111}In-labelled monomeric, dimeric and tetrameric RGD analogue were compared. A monomeric (E-c(RGDfK)), dimeric (E-[c(RGDfK)]{sub 2}), and tetrameric (E{l_brace}E[c(RGDfK)]{sub 2}{r_brace}{sub 2}) RGD peptide were synthesised, conjugated with DOTA and radiolabelled with {sup 111}In. In vitro {alpha}{sub v}{beta}{sub 3} binding characteristics were determined in a competitive binding assay. In vivo {alpha}{sub v}{beta}{sub 3} targeting characteristics of the compounds were assessed in mice with SK-RC-52 xenografts. The IC{sub 50} values for DOTA-E-c(RGDfK), DOTA-E-[c(RGDfK)]{sub 2}, and DOTA-E{l_brace}E[c(RGDfK)]{sub 2}{r_brace}{sub 2}were 120 nM, 69.9 nM and 19.6 nM, respectively. At all time points, the tumour uptake of the dimer was significantly higher as compared to that of the monomer. At 8 h p.i., tumour uptake of the tetramer (7.40 {+-}1.12%ID/g) was significantly higher than that of the monomer (2.30 {+-}0.34%ID/g), p <0.001, and the dimer (5.17 {+-}1.22%ID/g), p <0.05. At 24 h p.i., the tumour uptake was significantly higher for the tetramer (6.82 {+-}1.41%ID/g) than for the dimer (4.22 {+-}0.96%ID/g), p <0.01, and the monomer (1.90 {+-}0.29%ID/g), p <0.001. Multimerisation of c(RGDfK) resulted in enhanced affinity for {alpha}{sub v}{beta}{sub 3} as determined in vitro. Tumour uptake of a tetrameric RGD peptide was significantly higher than that of the monomeric and dimeric analogues, presumably owing to the enhanced statistical likelihood for rebinding to {alpha}{sub v}{beta}{sub 3}. (orig.)

  17. Protective spin-labeled fluorenes maintain amyloid beta peptide in small oligomers and limit transitions in secondary structure

    Energy Technology Data Exchange (ETDEWEB)

    Altman, Robin [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Ly, Sonny [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Science Directorate; Hilt, Silvia [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Petrlova, Jitka [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Maezawa, Izumi [Univ. of California Davis, Sacramento, CA (United States). MIND Inst. and Dept. of Pathology and Laboratory Medicine; Kálai, Tamás [Univ. of Pecs (Hungary). Inst. of Organic and Medicinal Chemistry; Hideg, Kálmán [Univ. of Pecs (Hungary). Inst. of Organic and Medicinal Chemistry; Jin, Lee-Way [Univ. of California Davis, Sacramento, CA (United States). MIND Inst. and Dept. of Pathology and Laboratory Medicine; Laurence, Ted A. [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Voss, John C. [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine

    2015-12-01

    Alzheimer’s disease is characterized by the presence of extracellular plaques comprised of amyloid beta (Aβ) peptides. Soluble oligomers of the Aβ peptide underlie a cascade of neuronal loss and dysfunction associated with Alzheimer's disease. Single particle analyses of Aβ oligomers in solution by fluorescence correlation spectroscopy (FCS) were used to provide real-time descriptions of how spin-labeled fluorenes (SLFs; bi-functional small molecules that block the toxicity of Aβ) prevent and disrupt oligomeric assemblies of Aβ in solution. The FCS results, combined with electron paramagnetic resonance spectroscopy and circular dichroism spectroscopy, demonstrate SLFs can inhibit the growth of Aβ oligomers and disrupt existing oligomers while retaining Aβ in a largely disordered state. Furthermore, while the ability of SLF to block Aβ toxicity correlates with a reduction in oligomer size, our results suggest the conformation of Aβ within the oligomer determines the toxicity of the species. Attenuation of Aβ toxicity, which has been associated primarily with the soluble oligomeric form, can be achieved through redistribution of the peptides into smaller oligomers and arrest of the fractional increase in beta secondary structure.

  18. An X11alpha/FSBP complex represses transcription of the GSK3beta gene promoter.

    LENUS (Irish Health Repository)

    Lau, Kwok-Fai

    2010-08-04

    X11alpha is a neuronal adaptor protein that interacts with the amyloid precursor protein (APP) through a centrally located phosphotyrosine binding domain to inhibit the production of Abeta peptide that is deposited in Alzheimer\\'s disease brains. X11alpha also contains two C-terminal postsynaptic density-95, large discs, zona occludens 1 (PDZ) domains, and we show here that through its PDZ domains, X11alpha interacts with a novel transcription factor, fibrinogen silencer binding protein. Moreover, we show that an X11alpha\\/fibrinogen silencer binding protein complex signals to the nucleus to repress glycogen synthase kinase-3beta promoter activity. Glycogen synthase kinase-3beta is a favoured candidate kinase for phosphorylating tau in Alzheimer\\'s disease. Our findings show a new function for X11alpha that may impact on Alzheimer\\'s disease pathogenesis.

  19. Beta-secretase-cleaved amyloid precursor protein in Alzheimer brain: a morphologic study

    DEFF Research Database (Denmark)

    Sennvik, Kristina; Bogdanovic, N; Volkmann, Inga;

    2004-01-01

    beta-amyloid (Abeta) is the main constituent of senile plaques seen in Alzheimer's disease. Abeta is derived from the amyloid precursor protein (APP) via proteolytic cleavage by proteases beta- and gamma-secretase. In this study, we examined content and localization of beta-secretase-cleaved APP...... the beta-sAPP immunostaining to be stronger and more extensive in gray matter in Alzheimer disease (AD) cases than controls. The axonal beta-sAPP staining was patchy and unevenly distributed for the AD cases, indicating impaired axonal transport. beta-sAPP was also found surrounding senile plaques...

  20. The nicotinic alpha7 acetylcholine receptor agonist ssr180711 is unable to activate limbic neurons in mice overexpressing human amyloid-beta1-42

    DEFF Research Database (Denmark)

    Soderman, A.; Spang-Thomsen, Mogens; Hansen, H.;

    2008-01-01

    Recent studies have demonstrated that amyloid-beta1-42 (Abeta1-42) binds to the nicotinergic alpha7 acetylcholine receptor (alpha7 nAChR) and that the application of Abeta1-42 to cells inhibits the function of the alpha7 nAChR. The in vivo consequences of the pharmacological activation of the alpha...

  1. Beta-Sheet-Forming, Self-Assembled Peptide Nanomaterials towards Optical, Energy, and Healthcare Applications.

    Science.gov (United States)

    Kim, Sungjin; Kim, Jae Hong; Lee, Joon Seok; Park, Chan Beum

    2015-08-12

    Peptide self-assembly is an attractive route for the synthesis of intricate organic nanostructures that possess remarkable structural variety and biocompatibility. Recent studies on peptide-based, self-assembled materials have expanded beyond the construction of high-order architectures; they are now reporting new functional materials that have application in the emerging fields such as artificial photosynthesis and rechargeable batteries. Nevertheless, there have been few reviews particularly concentrating on such versatile, emerging applications. Herein, recent advances in the synthesis of self-assembled peptide nanomaterials (e.g., cross β-sheet-based amyloid nanostructures, peptide amphiphiles) are selectively reviewed and their new applications in diverse, interdisciplinary fields are described, ranging from optics and energy storage/conversion to healthcare. The applications of peptide-based self-assembled materials in unconventional fields are also highlighted, such as photoluminescent peptide nanostructures, artificial photosynthetic peptide nanomaterials, and lithium-ion battery components. The relation of such functional materials to the rapidly progressing biomedical applications of peptide self-assembly, which include biosensors/chips and regenerative medicine, are discussed. The combination of strategies shown in these applications would further promote the discovery of novel, functional, small materials. PMID:25929870

  2. Cross-strand coupling of a beta-hairpin peptide stabilized with an Aib-Gly turn studied using isotope-edited IR spectroscopy.

    Science.gov (United States)

    Huang, Rong; Setnicka, Vladimir; Etienne, Marcus A; Kim, Joohyun; Kubelka, Jan; Hammer, Robert P; Keiderling, Timothy A

    2007-11-01

    Isotope-edited IR spectroscopy was used to study a series of singly and doubly 13C=O-labeled beta-hairpin peptides stabilized by an Aib-Gly turn sequence. The double-labeled peptides have amide I' IR spectra that show different degrees of vibrational coupling between the 13C-labeled amides due to variations in the local geometry of the peptide structure. The single-labeled peptides provide controls to determine frequencies characteristic of the diagonal force field (FF) contributions at each position for the uncoupled 13C=O modes. Separation of diagonal FF and coupling effects on the spectra are used to explain the cross-strand labeled spectral patterns. DFT calculations based on an idealized model beta-hairpin peptide correctly predict the vibrational coupling patterns. Extending these model results by consideration of frayed ends and the hairpin conformational flexibility yields an alternate interpretation of details of the spectra. Temperature-dependent isotopically labeled IR spectra reveal differences in the thermal stabilities of the individual isotopically labeled sites. This is the first example of using an IR-based isotopic labeling technique to differentiate structural transitions at specific sites along the peptide backbone in model beta-hairpin peptides.

  3. Amyloid beta-peptide worsens cognitive impairment following cerebral ischemia-reperfusion injury*****

    Institute of Scientific and Technical Information of China (English)

    Bo Song; Qiang Ao; Ying Niu; Qin Shen; Huancong Zuo; Xiufang Zhang; Yandao Gong

    2013-01-01

    Amyloid β-peptide, a major component of senile plaques in Alzheimer’s disease, has been impli-cated in neuronal cel death and cognitive impairment. Recently, studies have shown that the pathogenesis of cerebral ischemia is closely linked with Alzheimer’s disease. In this study, a rat model of global cerebral ischemia-reperfusion injury was established via occlusion of four arteries;meanwhile, fibril ar amyloid β-peptide was injected into the rat lateral ventricle. The Morris water maze test and histological staining revealed that administration of amyloid β-peptide could further aggravate impairments to learning and memory and neuronal cel death in the hippocampus of rats subjected to cerebral ischemia-reperfusion injury. Western blot showed that phosphorylation of tau protein and the activity of glycogen synthase kinase 3β were significantly stronger in cerebral is-chemia-reperfusion injury rats subjected to amyloidβ-peptide administration than those undergoing cerebral ischemia-reperfusion or amyloidβ-peptide administration alone. Conversely, the activity of protein phosphatase 2A was remarkably reduced in rats with cerebral ischemia-reperfusion injury fol owing amyloidβ-peptide administration. These findings suggest that amyloidβ-peptide can po-tentiate tau phosphorylation induced by cerebral ischemia-reperfusion and thereby aggravate cog-nitive impairment.

  4. In silico analysis of the apolipoprotein E and the amyloid beta peptide interaction: misfolding induced by frustration of the salt bridge network.

    Directory of Open Access Journals (Sweden)

    Jinghui Luo

    2010-02-01

    Full Text Available The relationship between Apolipoprotein E (ApoE and the aggregation processes of the amyloid beta (A beta peptide has been shown to be crucial for Alzheimer's disease (AD. The presence of the ApoE4 isoform is considered to be a contributing risk factor for AD. However, the detailed molecular properties of ApoE4 interacting with the A beta peptide are unknown, although various mechanisms have been proposed to explain the physiological and pathological role of this relationship. Here, computer simulations have been used to investigate the process of A beta interaction with the N-terminal domain of the human ApoE isoforms (ApoE2, ApoE3 and ApoE4. Molecular docking combined with molecular dynamics simulations have been undertaken to determine the A beta peptide binding sites and the relative stability of binding to each of the ApoE isoforms. Our results show that from the several ApoE isoforms investigated, only ApoE4 presents a misfolded intermediate when bound to A beta. Moreover, the initial alpha-helix used as the A beta peptide model structure also becomes unstructured due to the interaction with ApoE4. These structural changes appear to be related to a rearrangement of the salt bridge network in ApoE4, for which we propose a model. It seems plausible that ApoE4 in its partially unfolded state is incapable of performing the clearance of A beta, thereby promoting amyloid forming processes. Hence, the proposed model can be used to identify potential drug binding sites in the ApoE4-A beta complex, where the interaction between the two molecules can be inhibited.

  5. The tumor suppressor PP2A Abeta regulates the RalA GTPase.

    Science.gov (United States)

    Sablina, Anna A; Chen, Wen; Arroyo, Jason D; Corral, Laura; Hector, Melissa; Bulmer, Sara E; DeCaprio, James A; Hahn, William C

    2007-06-01

    The serine-threonine protein phosphatase 2A (PP2A) is a heterotrimeric enzyme family that regulates numerous signaling pathways. Biallelic mutations of the structural PP2A Abeta subunit occur in several types of human tumors; however, the functional consequences of these cancer-associated PP2A Abeta mutations in cell transformation remain undefined. Here we show that suppression of PP2A Abeta expression permits immortalized human cells to achieve a tumorigenic state. Cancer-associated Abeta mutants fail to reverse tumorigenic phenotype induced by PP2A Abeta suppression, indicating that these mutants function as null alleles. Wild-type PP2A Abeta but not cancer-derived Abeta mutants form a complex with the small GTPase RalA. PP2A Abeta-containing complexes dephosphorylate RalA at Ser183 and Ser194, inactivating RalA and abolishing its transforming function. These observations identify PP2A Abeta as a tumor suppressor gene that transforms immortalized human cells by regulating the function of RalA. PMID:17540176

  6. Cytocompatibility, antibacterial activity and biodegradability of self-assembling beta-hairpin peptide-based hydrogels for tissue regenerative applications

    Science.gov (United States)

    Salick, Daphne Ann

    Every year, millions of people suffer from tissue loss or failure. One approach to repair damaged or diseased tissue is through tissue/organ transplantation. However, one of the major problems which exist with this approach is that there are more people in need of a transplant than there are donors. Over the past several decades, scientists and doctors have come together to find a way to overcome this challenge. This collaboration has led to the development of biomimetic scaffolds, which closely mimic the desired tissue of interest to act as a substitute for the unfunctional tissue, with hopes to improve the quality of life. The Schneider and Pochan labs have developed a biomimetic scaffold using self-assembling beta-hairpin peptides. The self-assembly event can be triggered in response to physiological conditions, which is dictated by the monomer, to form non covalently crosslinked mechanically rigid hydrogels. In vitro studies showed that hydrogels were cytocompatible and may not elicit a pro-inflammatory response from murine macrophages. These material properties show promise for the use of these hydrogels in tissue engineering. When implanting a material into a host, a major concern is the introduction of infection. Infection, if not prevented or halted, results in poor tissue integration and function, ultimately leading to implant removal from the host. Interestingly, the beta-hairpin hydrogels were shown to exhibit antibacterial properties against pathogens commonly found in hospital environments. This inherently antibacterial hydrogel is advantageous because it may help decrease or diminish bacterial contamination when implanted in vivo, which may help to increase the success of implants. Also, a unique and exciting feature of these peptide-based hydrogels is their ability to shear-thin and self-heal. Hydrogels can be directly formed in a syringe and be subsequently delivered to a tissue defect in a minimally invasive manner where they will recover to their

  7. Islet distribution of Peptide YY and its regulatory role in primary mouse islets and immortalised rodent and human beta-cell function and survival.

    Science.gov (United States)

    Khan, Dawood; Vasu, Srividya; Moffett, R Charlotte; Irwin, Nigel; Flatt, Peter R

    2016-11-15

    Recent evidence suggests that the classic gut peptide, Peptide YY (PYY), could play a fundamental role in endocrine pancreatic function. In the present study expression of PYY and its NPY receptors on mouse islets and immortalised rodent and human beta-cells was examined together with the effects of both major circulating forms of PYY, namely PYY(1-36) and PYY(3-36), on beta-cell function, murine islet adaptions to insulin deficiency/resistance, as well as direct effects on cultured beta-cell proliferation and apoptosis. In vivo administration of PYY(3-36), but not PYY(1-36), markedly (p food intake in overnight fasted mice. Neither form of PYY affected glucose disposal or insulin secretion following an i.p. glucose challenge. However, in vitro, PYY(1-36) and PYY(3-36) inhibited (p preservation of beta-cell mass in diabetes. PMID:27465830

  8. X11beta rescues memory and long-term potentiation deficits in Alzheimer's disease APPswe Tg2576 mice.

    LENUS (Irish Health Repository)

    Mitchell, Jacqueline C

    2009-12-01

    Increased production and deposition of amyloid beta-protein (Abeta) are believed to be key pathogenic events in Alzheimer\\'s disease. As such, routes for lowering cerebral Abeta levels represent potential therapeutic targets for Alzheimer\\'s disease. X11beta is a neuronal adaptor protein that binds to the intracellular domain of the amyloid precursor protein (APP). Overexpression of X11beta inhibits Abeta production in a number of experimental systems. However, whether these changes to APP processing and Abeta production induced by X11beta overexpression also induce beneficial effects to memory and synaptic plasticity are not known. We report here that X11beta-mediated reduction in cerebral Abeta is associated with normalization of both cognition and in vivo long-term potentiation in aged APPswe Tg2576 transgenic mice that model the amyloid pathology of Alzheimer\\'s disease. Overexpression of X11beta itself has no detectable adverse effects upon mouse behaviour. These findings support the notion that modulation of X11beta function represents a therapeutic target for Abeta-mediated neuronal dysfunction in Alzheimer\\'s disease.

  9. Amyloid beta-peptide(25-35) changes [Ca2+] in hippocampal neurons

    DEFF Research Database (Denmark)

    Mogensen, Helle Smidt; Beatty, D M; Morris, S J;

    1998-01-01

    of A beta(25-35) on [Ca2+]i and intracellular H+ concentration ([H+]i) in single hippocampal neurons by real time fluorescence imaging using the Ca(2+)- and H(+)-specific ratio dyes, indo-1 and SNARF-1. Incubation of these cultures with A beta(25-35) for 3-12 days in vitro increased [Ca2+]i and [H......+]i in large, NMDA-responsive neurons....

  10. Multiscale MD Simulations of Folding Dynamics and Mobility of Beta-Amyloid Peptide on Lipid Bilayer Surfaces

    Science.gov (United States)

    van Tilburg, Scott; Cheng, Kelvin

    2013-03-01

    Early interaction events of beta-amyloid peptides with the neuronal membranes play a key role in the pathogenesis of Alzheimer's disease. We have used multiscale Molecular Dynamics (MD) simulations to study the protein folding dynamics and lateral mobility of beta-amyloid protein on the cholesterol-enriched and -depleted lipid nano-domains. Several independent simulation replicates of all-atom and coarse-grained MD simulations of beta-amyloid on different lipid bilayer nano-domains have been generated. Using Define Secondary Structure of Proteins (DSSP) algorithm and mean-square-distance (MSD) analysis, the protein conformation and the lateral diffusion coefficients of protein, as well as the lipid and water, were calculated as a function of simulation time up to 200 nanoseconds for atomistic and 2 microseconds for coarse-grained simulations per replicate in different bilayer systems. Subtle differences in the conformation and mobility of the protein were observed in lipid bilayers with and without cholesterol. The structural dynamics information obtained from this work will provide useful insights into understanding the role of protein/lipid interactions in the membrane-associated aggregation of protein on neuronal membranes. HHMI-Trinity University and NIH RC1-GM090897-02

  11. Glucagon-Like Peptide-1 Triggers Protective Pathways in Pancreatic Beta-Cells Exposed to Glycated Serum

    Directory of Open Access Journals (Sweden)

    Alessandra Puddu

    2013-01-01

    Full Text Available Advanced glycation end products (AGEs might play a pathophysiological role in the development of diabetes and its complications. AGEs negatively affect pancreatic beta-cell function and the expression of transcriptional factors regulating insulin gene. Glucagon-like peptide-1 (GLP-1, an incretin hormone that regulates glucose homeostasis, might counteract the harmful effects of AGEs on the beta cells in culture. The aim of this study was to identify the intracellular mechanisms underlying GLP-1-mediated protection from AGE-induced detrimental activities in pancreatic beta cells. HIT-T15 cells were cultured for 5 days with glycated serum (GS, consisting in a pool of AGEs, in the presence or absence of 10 nmol/L GLP-1. After evaluation of oxidative stress, we determined the expression and subcellular localization of proteins involved in maintaining redox balance and insulin gene expression, such as nuclear factor erythroid-derived 2 (Nrf2, glutathione reductase, PDX-1, and MafA. Then, we investigated proinsulin production. The results showed that GS increased oxidative stress, reduced protein expression of all investigated factors through proteasome activation, and decreased proinsulin content. Furthermore, GS reduced ability of PDX-1 and MafA to bind DNA. Coincubation with GLP-1 reversed these GS-mediated detrimental effects. In conclusion, GLP-1, protecting cells against oxidants, triggers protective intercellular pathways in HIT-T15 cells exposed to GS.

  12. Structural basis for distinctive recognition of fibrinogen [gamma]C peptide by the platelet integrin [alpha][subscript IIb][beta]3

    Energy Technology Data Exchange (ETDEWEB)

    Springer, Timothy A.; Zhu, Jianghai; Xiao, Tsan (Harvard-Med)

    2009-01-12

    Hemostasis and thrombosis (blood clotting) involve fibrinogen binding to integrin {alpha}{sub IIb}{beta}{sub 3} on platelets, resulting in platelet aggregation. {alpha}{sub v}{beta}{sub 3} binding fibrinogen via an Arg-Asp-Gly (RGD) motif in fibrinogen's {alpha} subunit. {alpha}{sub IIb}{beta}{sub 3} also binds to fibrinogen; however, it does so via an unstructured RGD-lacking C-terminal region of the {gamma} subunit ({gamma}C peptide). These distinct modes of fibrinogen binding enable {alpha}{sub IIb}{beta}{sub 3} and {alpha}{sub v}{beta}{sub 3} to function cooperatively in hemostasis. In this study, crystal structures reveal the integrin {alpha}{sub IIb}{beta}{sub 3}-{gamma}C peptide interface, and, for comparison, integrin {alpha}{sub IIb}{beta}{sub 3} bound to a lamprey {gamma}C primordial RGD motif. Compared with RGD, the GAKQAGDV motif in {gamma}C adopts a different backbone configuration and binds over a more extended region. The integrin metal ion-dependent adhesion site (MIDAS) Mg{sup 2+} ion binds the {gamma}C Asp side chain. The adjacent to MIDAS (ADMIDAS) Ca{sup 2+} ion binds the {gamma}C C terminus, revealing a contribution for ADMIDAS in ligand binding. Structural data from this natively disordered {gamma}C peptide enhances our understanding of the involvement of {gamma}C peptide and integrin {alpha}{sub IIb}{beta}{sub 3} in hemostasis and thrombosis.

  13. Beta amyloid and hyperphosphorylated tau deposits in the pancreas in type 2 diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Miklossy, J.; Miller, L.; Qing, H.; Radenovic, A.; Kis, A.; Vileno, B.; Laszlo, F.; Martins, R.N.; Waeber, G.; Mooser, V.; Bosman, F.; Khalili, K.; Darbinian, N.; McGeer, P.L.

    2008-08-25

    Strong epidemiologic evidence suggests an association between Alzheimer disease (AD) and type 2 diabetes. To determine if amyloid beta (A{beta}) and hyperphosphorylated tau occurs in type 2 diabetes, pancreas tissues from 21 autopsy cases (10 type 2 diabetes and 11 controls) were analyzed. APP and tau mRNAs were identified in human pancreas and in cultured insulinoma beta cells (INS-1) by RT-PCR. Prominent APP and tau bands were detected by Western blotting in pancreatic extracts. Aggregated A{beta}, hyperphosphorylated tau, ubiquitin, apolipoprotein E, apolipoprotein(a), IB1/JIP-1 and JNK1 were detected in Langerhans islets in type 2 diabetic patients. A{beta} was co-localized with amylin in islet amyloid deposits. In situ beta sheet formation of islet amyloid deposits was shown by infrared microspectroscopy (SIRMS). LPS increased APP in non-neuronal cells as well. We conclude that A{beta} deposits and hyperphosphorylated tau are also associated with type 2 diabetes, highlighting common pathogenetic features in neurodegenerative disorders, including AD and type 2 diabetes and suggesting that A{beta} deposits and hyperphosphorylated tau may also occur in other organs than the brain.

  14. Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

    LENUS (Irish Health Repository)

    Hampel, Harald

    2010-06-01

    Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

  15. Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

    LENUS (Irish Health Repository)

    Hampel, Harald

    2012-02-01

    Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

  16. Modeling peptide formation during the hydrolysis of beta-casein by Lactococcus lactis

    NARCIS (Netherlands)

    Munoz-Tamayo, R.; Groot, de J.; Wierenga, P.A.; Gruppen, H.; Zwietering, M.H.; Sijtsma, L.

    2012-01-01

    Hydrolysis of milk proteins by lactic acid bacteria leads to the formation of a large number of peptides. In this work, the hydrolysis of ß-casein by the protease PrtPI of Lactococcus lactis was studied. Experiments were carried out at different initial enzyme/substrate ratios. Identification and qu

  17. Iron and aluminum interaction with amyloid-beta peptides associated with Alzheimer’s disease

    International Nuclear Information System (INIS)

    An elevation in the concentration of heavy metal ions in Alzheimer’s disease (AD) brain has been demonstrated in many studies. Aβ precipitation and toxicity in AD brains seem to be caused by abnormal interactions with neocortical metal ions, especially iron, copper, zinc, and aluminum [1–3]. There is increasing evidence that iron and aluminum ions are involved in the mechanisms that underlie the neurodegenerative diseases [4,5]. However, evidence was brought to demonstrate that some Aβ fragments, at physiological pH, are not able to form binary complexes with Fe(III) ions of sufficient stability to compete with metal hydroxide precipitation [6]. On the contrary, multiple metal ions are known to interact with Aβ peptides [7]. Consequently, we investigated here the interaction of Fe(II/III) and Al(III) ions with some amyloid-β peptides and fragments that results in peptide aggregation and fibrillation [8,9]. Infrared spectroscopy, atomic force microscopy, scanning electron microscopy, electrophoresis and mass spectrometry demonstrated conformational changes of peptides in the presence of such metals

  18. Iron and aluminum interaction with amyloid-beta peptides associated with Alzheimer’s disease

    Energy Technology Data Exchange (ETDEWEB)

    Drochioiu, Gabi; Ion, Laura [Alexandru Ioan Cuza University of Iasi, 11 Carol I, Iasi 700506 (Romania); Murariu, Manuela; Habasescu, Laura [Petru Poni Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, Iasi 700487 (Romania)

    2014-10-06

    An elevation in the concentration of heavy metal ions in Alzheimer’s disease (AD) brain has been demonstrated in many studies. Aβ precipitation and toxicity in AD brains seem to be caused by abnormal interactions with neocortical metal ions, especially iron, copper, zinc, and aluminum [1–3]. There is increasing evidence that iron and aluminum ions are involved in the mechanisms that underlie the neurodegenerative diseases [4,5]. However, evidence was brought to demonstrate that some Aβ fragments, at physiological pH, are not able to form binary complexes with Fe(III) ions of sufficient stability to compete with metal hydroxide precipitation [6]. On the contrary, multiple metal ions are known to interact with Aβ peptides [7]. Consequently, we investigated here the interaction of Fe(II/III) and Al(III) ions with some amyloid-β peptides and fragments that results in peptide aggregation and fibrillation [8,9]. Infrared spectroscopy, atomic force microscopy, scanning electron microscopy, electrophoresis and mass spectrometry demonstrated conformational changes of peptides in the presence of such metals.

  19. Correction of a splice-site mutation in the beta-globin gene stimulated by triplex-forming peptide nucleic acids

    DEFF Research Database (Denmark)

    Chin, Joanna Y; Kuan, Jean Y; Lonkar, Pallavi S;

    2008-01-01

    Splice-site mutations in the beta-globin gene can lead to aberrant transcripts and decreased functional beta-globin, causing beta-thalassemia. Triplex-forming DNA oligonucleotides (TFOs) and peptide nucleic acids (PNAs) have been shown to stimulate recombination in reporter gene loci in mammalian...... DNA fragments, can promote single base-pair modification at the start of the second intron of the beta-globin gene, the site of a common thalassemia-associated mutation. This single base pair change was detected by the restoration of proper splicing of transcripts produced from a green fluorescent...... cells via site-specific binding and creation of altered helical structures that provoke DNA repair. We have designed a series of triplex-forming PNAs that can specifically bind to sequences in the human beta-globin gene. We demonstrate here that these PNAs, when cotransfected with recombinatory donor...

  20. Immature transformed rat islet beta-cells differentially express C-peptides derived from the genes coding for insulin I and II as well as a transfected human insulin gene

    DEFF Research Database (Denmark)

    Blume, N; Petersen, J S; Andersen, L C;

    1992-01-01

    Synthetic peptides representing unique sequences in rat proinsulin C-peptide I and II were used to generate highly specific antisera, which, when applied on sections of normal rat pancreas, confirm a homogeneous coexpression of the two C-peptides in all islet beta-cells. Insulin gene expression...... of transcription.(ABSTRACT TRUNCATED AT 250 WORDS)...

  1. Amorphous Aggregation of Amyloid Beta 1-40 Peptide in Confined Space.

    Science.gov (United States)

    Foschi, Giulia; Albonetti, Cristiano; Liscio, Fabiola; Milita, Silvia; Greco, Pierpaolo; Biscarini, Fabio

    2015-11-16

    The amorphous aggregation of Aβ1-40 peptide is addressed by using micromolding in capillaries. Both the morphology and the size of the aggregates are modulated by changing the contact angle of the sub-micrometric channel walls. Upon decreasing the hydrophilicity of the channels, the aggregates change their morphology from small aligned drops to discontinuous lines, thereby keeping their amorphous structure. Aβ1-40 fibrils are observed at high contact angles.

  2. Control of Alzheimer's amyloid beta toxicity by the high molecular weight immunophilin FKBP52 and copper homeostasis in Drosophila.

    Directory of Open Access Journals (Sweden)

    Reiko Sanokawa-Akakura

    Full Text Available FK506 binding proteins (FKBPs, also called immunophilins, are prolyl-isomerases (PPIases that participate in a wide variety of cellular functions including hormone signaling and protein folding. Recent studies indicate that proteins that contain PPIase activity can also alter the processing of Alzheimer's Amyloid Precursor Protein (APP. Originally identified in hematopoietic cells, FKBP52 is much more abundantly expressed in neurons, including the hippocampus, frontal cortex, and basal ganglia. Given the fact that the high molecular weight immunophilin FKBP52 is highly expressed in CNS regions susceptible to Alzheimer's, we investigated its role in Abeta toxicity. Towards this goal, we generated Abeta transgenic Drosophila that harbor gain of function or loss of function mutations of FKBP52. FKBP52 overexpression reduced the toxicity of Abeta and increased lifespan in Abeta flies, whereas loss of function of FKBP52 exacerbated these Abeta phenotypes. Interestingly, the Abeta pathology was enhanced by mutations in the copper transporters Atox1, which interacts with FKBP52, and Ctr1A and was suppressed in FKBP52 mutant flies raised on a copper chelator diet. Using mammalian cultures, we show that FKBP52 (-/- cells have increased intracellular copper and higher levels of Abeta. This effect is reversed by reconstitution of FKBP52. Finally, we also found that FKBP52 formed stable complexes with APP through its FK506 interacting domain. Taken together, these studies identify a novel role for FKBP52 in modulating toxicity of Abeta peptides.

  3. Coupling of importin beta binding peptide on plasmid DNA: transfection efficiency is increased by modification of lipoplex's physico-chemical properties

    Directory of Open Access Journals (Sweden)

    Escriou Virginie

    2003-09-01

    Full Text Available Abstract Background Non-viral vectors for gene transfer are less immunogenic than viral vectors but also less efficient. Significant effort has focused on enhancing non-viral gene transfer efficiency by increasing nuclear import of plasmid DNA, particularly by coupling nuclear localization peptidic sequences to plasmid DNA. Results We have coupled a 62-aminoacid peptide derived from hSRP1α importin beta binding domain, called the IBB peptide to plasmid DNA by using the heterobifunctional linker N-(4-azido-2,3,5,6 tetrafluorobenzyl-6-maleimidyl hexanamide (TFPAM-6. When covalently coupled to plasmid DNA, IBB peptide did not increase the efficiency of cationic lipid mediated transfection. The IBB peptide was still able to interact with its nuclear import receptor, importin β, but non-specifically. However, we observed a 20-fold increase in reporter gene expression with plasmid DNA / IBB peptide complexes under conditions of inefficient transfection. In which case, IBB was associated with plasmid DNA through self assembling ionic interaction. Conclusions The improvement of transfection activity was not due to an improved nuclear import of DNA, but rather by the modification of physicochemical properties of IBB peptide / plasmid complexes. IBB peptide increased lipoplex size and these larger complexes were more efficient for gene transfer.

  4. Simulation of infrared spectra for beta-hairpin peptides stabilized by an Aib-Gly turn sequence: correlation between conformational fluctuation and vibrational coupling.

    Science.gov (United States)

    Kim, Joohyun; Huang, Rong; Kubelka, Jan; Bou Rcaron, Petr; Keiderling, Timothy A

    2006-11-23

    Vibrational spectra of a 12-residue beta-hairpin peptide, RYVEVBGKKILQ (HBG), stabilized by an Aib-Gly turn sequence (B = Aib) were investigated theoretically using a combination of molecular dynamics (MD) and density functional theory (DFT) calculations. Selected conformations of HBG were extracted from a classical MD trajectory and used for spectral simulations. DFT calculations, based on the Cartesian coordinate spectral property transfer protocol, were carried out for peptide structures in which all residues are replaced with Ala, except for the Aib and Gly residues, but the backbone (phi, psi, omega) structure of the original configuration is retained. The simulations provide a basis for interpretation of the HBG amide I infrared spectra in terms of structural variables such as detailed secondary structure and thermal conformational fluctuation as well as vibrational coupling as indicated by spectra of 13C isotope-labeled variants. The characteristic amide I band shape of such small beta-hairpin peptides appears to arise from the structure of the short antiparallel beta-sheet strands. The role of structural parameter fluctuation in vibrational coupling is evaluated by comparison of DFT-derived amide coupling constants for selected configurations and from transition dipole coupling calculations of coupling parameters between (13)C isotopically labeled residues for a MD-derived ensemble of configurations. Calculated results were compared with the experimentally obtained spectra for several (13)C isotope-labeled peptides of this sequence.

  5. Study of the BPP7a peptide and its {beta}-cyclodextrin complex: physicochemical characterization and complete sequence specific NMR assignments

    Energy Technology Data Exchange (ETDEWEB)

    Lula, Ivana; Sousa, Frederico B. de; Denadai, Angelo M.L.; Sinisterra, Ruben D.; Ianzer, Danielle; Santos, Robson A.S., E-mail: sinisterra@ufmg.br [Departamento de Quimica, Instituto de Ciencias Exatas and Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, (Brazil); Camargo, Antonio C.M. de [Center for Applied Toxinology (CAT-CEPID), Instituto Butantan, Sao Paulo, SP (Brazil)

    2011-09-15

    The BPP7a heptapeptide, p-Glu1Asp2Gly3Pro4Ile5Pro6Pro7, forms an association complex with {beta}-cyclodextrin in a 1:1 molar ratio. The peptide and its complex were characterized by circular dichroism (CD) and isothermal titration calorimetry (ITC), which showed a very weak interaction between the {beta}-cyclodextrin and the peptide. Assignments of all hydrogen resonances of the peptide alone and as a complex were made using {sup 1}H nuclear magnetic resonance (NMR) experiments at 400 and 600 MHz. High resolution diffusion ordered spectroscopy (HR-DOSY) experiments were carried out to establish the self-aggregation state of BPP7a. It was also shown that the {beta}-cyclodextrin breaks the molecular clusters leading to complex formation. In addition, the anti-hypertensive activity of the BPP7a/{beta}-cyclodextrin complex was evaluated in spontaneous hypertensive rats (SHR), showing increased activity compared to that of pure BPP7a. (author)

  6. Synthetic peptides corresponding to human follicle-stimulating hormone (hFSH)-beta-(1-15) and hFSH-beta-(51-65) induce uptake of 45Ca++ by liposomes: evidence for calcium-conducting transmembrane channel formation

    International Nuclear Information System (INIS)

    We have previously described FSH receptor-mediated influx of 45Ca++ in cultured Sertoli cells from immature rats and receptor-enriched proteoliposomes via activation of voltage-sensitive and voltage-independent calcium channels. We have further shown that this effect of FSH does not require cholera toxin- or pertussis toxin-sensitive guanine nucleotide binding protein or activation of adenylate cyclase. In the present study, we have identified regions of human FSH-beta-subunit which appear to be involved in mediating calcium influx. We screened 11 overlapping peptide amides representing the entire primary structure of hFSH-beta-subunit for their effects on 45Ca++ flux in FSH receptor-enriched proteoliposomes. hFSH-beta-(1-15) and hFSH-beta-(51-65) induced uptake of 45Ca++ in a concentration-related manner. This effect of hFSH-beta-(1-15) and hFSH-beta-(51-65) was also observed in liposomes lacking incorporated FSH receptor. Reducing membrane fluidity by incubating liposomes (containing no receptor) with hFSH-beta-(1-15) or hFSH-beta-(51-65) at temperatures lower than the transition temperatures of their constituent phospholipids resulted in no significant (P greater than 0.05) difference in 45Ca++ uptake. The effectiveness of the calcium ionophore A23187, however, was abolished. Ruthenium red, a voltage-independent calcium channel antagonist, was able to completely block uptake of 45Ca++ induced by hFSH-beta-(1-15) and hFSH-beta-(51-65) whereas nifedipine, a calcium channel blocker specific for L-type voltage-sensitive calcium channels, was without effect. These results suggest that in addition to its effect on voltage-sensitive calcium channel activity, interaction of FSH with its receptor may induce formation of transmembrane aqueous channels which also facilitate influx of extracellular calcium

  7. Probing the Orientation and Conformation of alpha-Helix and beta-Strand Model Peptides on Self-Assembled Monolayers Using Sum Frequency Generation and NEXAFS Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weidner, T.; Apte, J; Gamble, L; Castner, D

    2010-01-01

    The structure and orientation of amphiphilic {alpha}-helix and {beta}-strand model peptide films on self-assembled monolayers (SAMs) have been studied with sum frequency generation (SFG) vibrational spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The {alpha}-helix peptide is a 14-mer, and the {beta}-strand is a 15-mer of hydrophilic lysine and hydrophobic leucine residues with hydrophobic periodicities of 3.5 and 2, respectively. These periodicities result in the leucine side chains located on one side of the peptides and the lysine side chains on the other side. The SAMs were prepared from the assembly of either carboxylic acid- or methyl-terminated alkyl thiols onto gold surfaces. For SFG studies, the deuterated analog of the methyl SAM was used. SFG vibrational spectra in the C-H region of air-dried peptides films on both SAMs exhibit strong peaks near 2965, 2940, and 2875 cm{sup -1} related to ordered leucine side chains. The orientation of the leucine side chains was determined from the phase of these features relative to the nonresonant gold background. The relative phase for both the {alpha}-helix and {beta}-strand peptides showed that the leucine side chains were oriented away from the carboxylic acid SAM surface and oriented toward the methyl SAM surface. Amide I peaks observed near 1656 cm{sup -1} for the {alpha}-helix peptide confirm that the secondary structure is preserved on both SAMs. Strong linear dichroism related to the amide {pi}* orbital at 400.8 eV was observed in the nitrogen K-edge NEXAFS spectra for the adsorbed {beta}-strand peptides, suggesting that the peptide backbones are oriented parallel to the SAM surface with the side chains pointing toward or away from the interface. For the {alpha}-helix the dichroism of the amide {pi}* is significantly weaker, probably because of the broad distribution of amide bond orientations in the {alpha}-helix secondary structure.

  8. A photoaffinity analogue of discodermolide specifically labels a peptide in beta-tubulin.

    Science.gov (United States)

    Xia, Shujun; Kenesky, Craig S; Rucker, Paul V; Smith, Amos B; Orr, George A; Horwitz, Susan Band

    2006-10-01

    Discodermolide is a potentially important antitumor agent that stabilizes microtubules and blocks cells at the G2/M phase of the cell cycle in a manner similar to that of Taxol. Discodermolide also has unique properties that distinguish it from Taxol. In the present study, photoaffinity-labeled discodermolide analogues are used to investigate their binding site in tubulin. Three photoaffinity-labeled discodermolide analogues were synthesized, all of which promoted microtubule polymerization in the absence of GTP. The analogue, C19-[4-(4-(3)H-benzoyl-phenyl)-carbamate]-discodermolide (C19-[3H]BPC-discodermolide), was selected for photolabeling studies because it had the highest extent of photoincorporation, approximately 1%, of the three radiolabeled discodermolide analogues explored. Although compared to discodermolide, C19-BPC-discodermolide revealed no hypernucleation effect in the in vitro microtubule polymerization assay, it was more cytotoxic than discodermolide, and, like discodermolide, demonstrated synergism with Taxol. These results suggest that the hypernucleation effect of discodermolide is not involved in its cytotoxic activity. Similar to discodermolide, C19-BPC-discodermolide can effectively displace [3H]Taxol from microtubules, but Taxol cannot effectively displace C19-[3H]BPC-discodermolide binding. Discodermolide can effectively displace C19-[3H]BPC-discodermolide binding. Formic acid hydrolysis, immunoprecipitation experiments, and subtilisin digestion indicate that C19-BPC-discodermolide labels amino acid residues 305-433 in beta-tubulin. Further digestion with Asp-N and Arg-C enzymes suggested that C19-BPC-discodermolide binds to amino acid residues, 355-359, in beta-tubulin, which is in close proximity to the Taxol binding site. Molecular modeling guided by the above evidence led to a putative binding model for C19-BPC-discodermolide in tubulin.

  9. Correction of a splice-site mutation in the beta-globin gene stimulated by triplex-forming peptide nucleic acids.

    Science.gov (United States)

    Chin, Joanna Y; Kuan, Jean Y; Lonkar, Pallavi S; Krause, Diane S; Seidman, Michael M; Peterson, Kenneth R; Nielsen, Peter E; Kole, Ryszard; Glazer, Peter M

    2008-09-01

    Splice-site mutations in the beta-globin gene can lead to aberrant transcripts and decreased functional beta-globin, causing beta-thalassemia. Triplex-forming DNA oligonucleotides (TFOs) and peptide nucleic acids (PNAs) have been shown to stimulate recombination in reporter gene loci in mammalian cells via site-specific binding and creation of altered helical structures that provoke DNA repair. We have designed a series of triplex-forming PNAs that can specifically bind to sequences in the human beta-globin gene. We demonstrate here that these PNAs, when cotransfected with recombinatory donor DNA fragments, can promote single base-pair modification at the start of the second intron of the beta-globin gene, the site of a common thalassemia-associated mutation. This single base pair change was detected by the restoration of proper splicing of transcripts produced from a green fluorescent protein-beta-globin fusion gene. The ability of these PNAs to induce recombination was dependent on dose, sequence, cell-cycle stage, and the presence of a homologous donor DNA molecule. Enhanced recombination, with frequencies up to 0.4%, was observed with use of the lysomotropic agent chloroquine. Finally, we demonstrate that these PNAs were effective in stimulating the modification of the endogenous beta-globin locus in human cells, including primary hematopoietic progenitor cells. This work suggests that PNAs can be effective tools to induce heritable, site-specific modification of disease-related genes in human cells. PMID:18757759

  10. Effect of copper (II) ion against elongation behavior of amyloid {beta} fibrils on liposome membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shimanouchi, T.; Onishi, R.; Kitaura, N.; Umakoshi, H.; Kuboi, R. [Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka (Japan)

    2012-01-15

    The fibril growth behavior of amyloid {beta} protein (A{beta}) on cell membranes is relating to the progression of Alzheimer's disease. This growth behavior of A{beta} fibrils is sensitively affected by the metal ions, neurotransmitters, or bioreactive substrate. The inhibitory effect of those materials was quantitatively estimated from the viewpoints of ''crystal growth''. In a bulk aqueous solution, copper (II) ion showed the strong inhibitory effect on the growth of A{beta} fibrils. Meanwhile, the addition of a closed-phospholipid bilayer membrane (liposome) could reduce the above inhibitory effect of copper (II) ion. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Activation of epidermal growth factor receptor by metal-ligand complexes decreases levels of extracellular amyloid beta peptide.

    Science.gov (United States)

    Price, Katherine A; Filiz, Gulay; Caragounis, Aphrodite; Du, Tai; Laughton, Katrina M; Masters, Colin L; Sharples, Robyn A; Hill, Andrew F; Li, Qiao-Xin; Donnelly, Paul S; Barnham, Kevin J; Crouch, Peter J; White, Anthony R

    2008-01-01

    The epidermal growth factor receptor is a receptor tyrosine kinase expressed in a range of tissues and cell-types. Activation of the epidermal growth factor receptor by a number of ligands induces downstream signalling that modulates critical cell functions including growth, survival and differentiation. Abnormal epidermal growth factor receptor expression and activation is also involved in a number of cancers. In addition to its cognate ligands, the epidermal growth factor receptor can be activated by metals such as zinc (Zn) and copper (Cu). Due to the important role of these metals in a number of diseases including neurodegenerative disorders, therapeutic approaches are being developed based on the use of lipid permeable metal-complexing molecules. While these agents are showing promising results in animal models and clinical trials, little is known about the effects of metal-ligand complexes on cell signalling pathways. In this study, we investigated the effects of clioquinol (CQ)-metal complexes on activation of epidermal growth factor receptor. We show here that CQ-Cu complexes induced potent epidermal growth factor receptor phosphorylation resulting in downstream activation of extracellular signal-regulated kinase. Similar levels of epidermal growth factor receptor activation were observed with alternative lipid permeable metal-ligands including neocuproine and pyrrolidine dithiocarbamate. We found that CQ-Cu complexes induced a significant reduction in the level of extracellular Abeta1-40 in cell culture. Inhibition of epidermal growth factor receptor activation by PD153035 blocked extracellular signal-regulated kinase phosphorylation and restored Abeta1-40 levels. Activation of the epidermal growth factor receptor by CQ-Cu was mediated through up-regulation of src kinase activity by a cognate ligand-independent process involving membrane integrins. These findings provide the first evidence that metal-ligand complexes can activate the epidermal growth

  12. PET imaging of {alpha}{sub v}{beta}{sub 3} integrin expression in tumours with {sup 68}Ga-labelled mono-, di- and tetrameric RGD peptides

    Energy Technology Data Exchange (ETDEWEB)

    Dijkgraaf, Ingrid; Franssen, Gerben M.; Oyen, Wim J.G.; Boerman, Otto C. [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Yim, Cheng-Bin [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Utrecht University, Department of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht (Netherlands); Schuit, Robert C. [VU University Medical Centre, Department of Nuclear Medicine and PET Research, P.O. Box 7057, Amsterdam (Netherlands); Luurtsema, Gert [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Hanzeplein 1, P.O. Box 30.001, Groningen (Netherlands); Liu, Shuang [Purdue University, School of Health Sciences, West Lafayette, IN (United States)

    2011-01-15

    Due to the restricted expression of {alpha}{sub v}{beta}{sub 3} in tumours, {alpha}{sub v}{beta}{sub 3} is considered a suitable receptor for tumour targeting. In this study the {alpha}{sub v}{beta}{sub 3}-binding characteristics of {sup 68}Ga-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared with their {sup 111}In-labelled counterparts. A monomeric (E-c(RGDfK)), a dimeric (E-[c(RGDfK)]{sub 2}) and a tetrameric (E{l_brace}E[c(RGDfK)]{sub 2}{r_brace}{sub 2}) RGD peptide were synthesised, conjugated with DOTA and radiolabelled with {sup 68}Ga. In vitro {alpha}{sub v}{beta}{sub 3}-binding characteristics were determined in a competitive binding assay. In vivo {alpha}{sub v}{beta}{sub 3}-targeting characteristics of the compounds were assessed in mice with subcutaneously growing SK-RC-52 xenografts. In addition, microPET images were acquired using a microPET/CT scanner. The IC{sub 50} values for the Ga(III)-labelled DOTA-E-c(RGDfK), DOTA-E-[c(RGDfK)]{sub 2} and DOTA-E{l_brace}E[c(RGDfK)]{sub 2}{r_brace}{sub 2} were 23.9 {+-} 1.22, 8.99 {+-} 1.20 and 1.74 {+-} 1.18 nM, respectively, and were similar to those of the In(III)-labelled mono-, di- and tetrameric RGD peptides (26.6 {+-} 1.15, 3.34 {+-} 1.16 and 1.80 {+-} 1.37 nM, respectively). At 2 h post-injection, tumour uptake of the {sup 68}Ga-labelled mono-, di- and tetrameric RGD peptides (3.30 {+-} 0.30, 5.24 {+-} 0.27 and 7.11 {+-} 0.67%ID/g, respectively) was comparable to that of their {sup 111}In-labelled counterparts (2.70 {+-} 0.29, 5.61 {+-} 0.85 and 7.32 {+-} 2.45%ID/g, respectively). PET scans were in line with the biodistribution data. On all PET scans, the tumour could be clearly visualised. The integrin affinity and the tumour uptake followed the order of DOTA-tetramer > DOTA-dimer > DOTA-monomer. The {sup 68}Ga-labelled tetrameric RGD peptide has excellent characteristics for imaging of {alpha}{sub v} {beta}{sub 3} expression with PET. (orig.)

  13. Monomeric Amyloid Beta Peptide in Hexafluoroisopropanol Detected by Small Angle Neutron Scattering.

    Directory of Open Access Journals (Sweden)

    Bo Zhang-Haagen

    Full Text Available Small proteins like amyloid beta (Aβ monomers are related to neurodegenerative disorders by aggregation to insoluble fibrils. Small angle neutron scattering (SANS is a nondestructive method to observe the aggregation process in solution. We show that SANS is able to resolve monomers of small molecular weight like Aβ for aggregation studies. We examine Aβ monomers after prolonged storing in d-hexafluoroisopropanol (dHFIP by using SANS and dynamic light scattering (DLS. We determined the radius of gyration from SANS as 1.0±0.1 nm for Aβ1-40 and 1.6±0.1 nm for Aβ1-42 in agreement with 3D NMR structures in similar solvents suggesting a solvent surface layer with 5% increased density. After initial dissolution in dHFIP Aβ aggregates sediment with a major component of pure monomers showing a hydrodynamic radius of 1.8±0.3 nm for Aβ1-40 and 3.2±0.4 nm for Aβ1-42 including a surface layer of dHFIP solvent molecules.

  14. Monomeric Amyloid Beta Peptide in Hexafluoroisopropanol Detected by Small Angle Neutron Scattering

    Science.gov (United States)

    Zhang-Haagen, Bo; Biehl, Ralf; Nagel-Steger, Luitgard; Radulescu, Aurel; Richter, Dieter; Willbold, Dieter

    2016-01-01

    Small proteins like amyloid beta (Aβ) monomers are related to neurodegenerative disorders by aggregation to insoluble fibrils. Small angle neutron scattering (SANS) is a nondestructive method to observe the aggregation process in solution. We show that SANS is able to resolve monomers of small molecular weight like Aβ for aggregation studies. We examine Aβ monomers after prolonged storing in d-hexafluoroisopropanol (dHFIP) by using SANS and dynamic light scattering (DLS). We determined the radius of gyration from SANS as 1.0±0.1 nm for Aβ1–40 and 1.6±0.1 nm for Aβ1–42 in agreement with 3D NMR structures in similar solvents suggesting a solvent surface layer with 5% increased density. After initial dissolution in dHFIP Aβ aggregates sediment with a major component of pure monomers showing a hydrodynamic radius of 1.8±0.3 nm for Aβ1–40 and 3.2±0.4 nm for Aβ1–42 including a surface layer of dHFIP solvent molecules. PMID:26919121

  15. Guanylin peptides regulate electrolyte and fluid transport in the Gulf toadfish (Opsanus beta) posterior intestine.

    Science.gov (United States)

    Ruhr, Ilan M; Bodinier, Charlotte; Mager, Edward M; Esbaugh, Andrew J; Williams, Cameron; Takei, Yoshio; Grosell, Martin

    2014-11-01

    The physiological effects of guanylin (GN) and uroguanylin (UGN) on fluid and electrolyte transport in the teleost fish intestine have yet to be thoroughly investigated. In the present study, the effects of GN, UGN, and renoguanylin (RGN; a GN and UGN homolog) on short-circuit current (Isc) and the transport of Cl-, Na+, bicarbonate (HCO3-), and fluid in the Gulf toadfish (Opsanus beta) intestine were determined using Ussing chambers, pH-stat titration, and intestinal sac experiments. GN, UGN, and RGN reversed the Isc of the posterior intestine (absorptive-to-secretory), but not of the anterior intestine. RGN decreased baseline HCO3- secretion, but increased Cl- and fluid secretion in the posterior intestine. The secretory response of the posterior intestine coincides with the presence of basolateral NKCC1 and apical cystic fibrosis transmembrane conductance regulator (CFTR), the latter of which is lacking in the anterior intestine and is not permeable to HCO3- in the posterior intestine. However, the response to RGN by the posterior intestine is counterintuitive given the known role of the marine teleost intestine as a salt- and water-absorbing organ. These data demonstrate that marine teleosts possess a tissue-specific secretory response, apparently associated with seawater adaptation, the exact role of which remains to be determined.

  16. Structural and pathway complexity of beta-strand reorganization within aggregates of human transthyretin(105-115) peptide.

    Science.gov (United States)

    Li, Da-Wei; Han, Li; Huo, Shuanghong

    2007-05-17

    Interstrand conformational rearrangements of human transthyretin peptide (TTR(105-115)) within dimeric aggregates were simulated by means of molecular dynamics (MD) with implicit solvation model for a total length of 48 micros. The conformations sampled in the MD simulations were clustered to identify free energy minima without any projections of free energy surface. A connected graph was constructed with nodes (=clusters) and edges corresponding to free energy minima and transitions between nodes, respectively. This connected graph which reflects the complexity of the free energy surface was used to extract the transition disconnectivity graph, which reflects the overall free energy barriers between pairs of free energy minima but does not contain information on transition paths. The routes of transitions between important free energy minima were obtained by further processing the original graph and the MD data. We have found that both parallel and antiparallel aggregates are populated. The parallel aggregates with different alignment patterns are separated by nonnegligible free energy barriers. Multiroutes exist in the interstrand conformational reorganization. Most visited routes do not dominant the kinetics, while less visited routes contribute a little each but they are numerous and their total contributions are actually dominant. There are various kinds of reptation motions, including those through a beta-bulge, side-chain aided reptation, and flipping or rotation of a hairpin formed by one strand.

  17. Role of Notch-1 signaling pathway in PC12 cell apoptosis induced by amyloid beta-peptide (25-35)

    Institute of Scientific and Technical Information of China (English)

    Huimin Liang; Yaozhou Zhang; Xiaoyan Shi; Tianxiang Wei; Jiyu Lou

    2014-01-01

    Recent studies have demonstrated that Notch-1 expression is increased in the hippocampus of Alzheimer’s disease patients. We speculate that Notch-1 signaling may be involved in PC12 cell apoptosis induced by amyloid beta-peptide (25-35) (Aβ25-35). In the present study, PC12 cells were cultured with different doses (0, 0.1, 1.0, 10 and 100 nmol/L) of N-[N-(3,5-Dilfuorophen-acetyl)-L-alanyl]-S-phenylglycine t-butyl ester, a Notch-1 signaling pathway inhibitor, for 30 minutes. Then cultured cells were induced with Aβ25-35 for 48 hours. Pretreatment of PC12 cells with high doses of N-[N-(3,5-Dilfuorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (> 10 nmol/L) prolonged the survival of PC12 cells after Aβ25-35 induction, decreased the expression of apoptosis-related proteins caspase-3, -8, -9, increased the activity of oxidative stress-related su-peroxide dismutase and catalase, inhibited the production of active oxygen, and reduced nuclear factor kappa B expression. This study indicates that the Notch-1 signaling pathway plays a pivotal role in Aβ25-35-induced PC12 apoptosis.

  18. Metabolic changes may precede proteostatic dysfunction in a Drosophila model of amyloid beta peptide toxicity.

    Science.gov (United States)

    Ott, Stanislav; Vishnivetskaya, Anastasia; Malmendal, Anders; Crowther, Damian C

    2016-05-01

    Amyloid beta (Aβ) peptide aggregation is linked to the initiation of Alzheimer's disease; accordingly, aggregation-prone isoforms of Aβ, expressed in the brain, shorten the lifespan of Drosophila melanogaster. However, the lethal effects of Aβ are not apparent until after day 15. We used shibire(TS) flies that exhibit a temperature-sensitive paralysis phenotype as a reporter of proteostatic robustness. In this model, we found that increasing age but not Aβ expression lowered the flies' permissive temperature, suggesting that Aβ did not exert its lethal effects by proteostatic disruption. Instead, we observed that chemical challenges, in particular oxidative stressors, discriminated clearly between young (robust) and old (sensitive) flies. Using nuclear magnetic resonance spectroscopy in combination with multivariate analysis, we compared water-soluble metabolite profiles at various ages in flies expressing Aβ in their brains. We observed 2 genotype-linked metabolomic signals, the first reported the presence of any Aβ isoform and the second the effects of the lethal Arctic Aβ. Lethality was specifically associated with signs of oxidative respiration dysfunction and oxidative stress. PMID:27103517

  19. Molecular simulations of beta-amyloid protein near hydrated lipids (PECASE).

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Aidan Patrick; Han, Kunwoo (Texas A& M University, College Station, TX); Ford, David M. (Texas A& M University, College Station, TX)

    2005-12-01

    We performed molecular dynamics simulations of beta-amyloid (A{beta}) protein and A{beta} fragment(31-42) in bulk water and near hydrated lipids to study the mechanism of neurotoxicity associated with the aggregation of the protein. We constructed full atomistic models using Cerius2 and ran simulations using LAMMPS. MD simulations with different conformations and positions of the protein fragment were performed. Thermodynamic properties were compared with previous literature and the results were analyzed. Longer simulations and data analyses based on the free energy profiles along the distance between the protein and the interface are ongoing.

  20. [Protective effects of glucagon-like peptide-1 on beta-cells: preclinical and clinical data].

    Science.gov (United States)

    Consoli, Agostino; Di Biagio, Rosamaria

    2011-12-01

    Dipartimento di Medicina Interna e Scienze dell'Invecchiamento, Università degli Studi "G. d'Annunzio", Chieti Continuing b-cell mass and function loss represents the key mechanism for the pathogenesis and the progression of type 2 diabetes mellitus. Drugs capable of arresting b-cell loss and eventually able to bring b-cell function close to be back to normal would then be a formidable help in type 2 diabetes mellitus treatment. The glucagon-like peptide-1 (GLP-1) receptor agonists exenatide and liraglutide can stimulate in vitro neogenesis and prevent apoptosis in b-cell-like cell lines. Consistently, treatment with GLP-1 receptor agonists ameliorates glucose metabolism, preserves b-cell mass and improves b-cell function in several animal models of diabetes. For instance, in the db/db mice, liraglutide protects the b-cell from oxidative stress and endoplasmic reticulum stress-related damage. Data in humans, in vivo, are less definitive and often based on scarcely reliable indexes of b-cell function. However, short-term treatment (14 weeks) with liraglutide increased b-cell maximal response capacity in a dose-response fashion. A longer (1 year) exenatide treatment also was able to increase b-cell maximal response capacity, but the effect was no longer there after a 4-week washout period. However, a marginal, although significant as compared to glargine treatment, improvement in another b-cell function index (disposition index) was observed after a 4-week washout period following 3-year exenatide treatment. Finally, although no clinical trials with a long enough follow-up period are presently available, durable glucose control has been obtained during 2 years of liraglutide treatment in monotherapy. Since the durability of good control is strictly dependent upon a lack of further b-cell function deterioration, these clinical data may foster hope that GLP-1 receptor antagonist treatment might help preserving b-cell function also in individuals affected by type 2

  1. Membrane-bound structure and alignment of the antimicrobial {beta}-sheet peptide gramicidin S derived from angular and distance constraints by solid state 19F-NMR

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Jesus; Grage, Stephan L. [University of Jena, Department of Molecular Biology (Germany); Kondejewski, Leslie H. [University of Alberta, Protein Engineering Network of Centres of Excellence (Canada); Hodges, Robert S.; McElhaney, Ronald N. [University of Alberta, Department of Biochemistry (Canada); Ulrich, Anne S. [University of Jena, Department of Molecular Biology (Germany)

    2001-11-15

    The antimicrobial properties of the cyclic {beta}-sheet peptide gramicidin S are attributed to its destabilizing effect on lipid membranes. Here we present the membrane-bound structure and alignment of a derivative of this peptide, based on angular and distance constraints. Solid-state {sup 19}F-NMR was used to study a {sup 19}F-labelled gramicidin S analogue in dimyristoylphosphatidylcholine bilayers at a lipid:peptide ratio of 80:1 and above. Two equivalent leucine side chains were replaced by the non-natural amino acid 4F-phenylglycine, which serves as a highly sensitive reporter on the structure and dynamics of the peptide backbone. Using a modified CPMG multipulse sequence, the distance between the two {sup 19}F-labels was measured from their homonuclear dipolar coupling as 6 A, in good agreement with the known backbone structure of natural gramicidin S in solution. By analyzing the anisotropic chemical shift of the {sup 19}F-labels in macroscopically oriented membrane samples, we determined the alignment of the peptide in the bilayer and described its temperature-dependent mobility. In the gel phase, the {sup 19}F-labelled gramicidin S is aligned symmetrically with respect to the membrane normal, i.e., with its cyclic {beta}-sheet backbone lying flat in the plane of the bilayer, which is fully consistent with its amphiphilic character. Upon raising the temperature to the liquid crystalline state, a considerable narrowing of the {sup 19}F-NMR chemical shift dispersion is observed, which is attributed the onset of global rotation of the peptide and further wobbling motions. This study demonstrates the potential of the {sup 19}F nucleus to describe suitably labelled polypeptides in membranes, requiring only little material and short NMR acquisition times.

  2. Characteristics of Amyloid-Related Oligomers Revealed by Crystal Structures of Macrocyclic [beta]-Sheet Mimics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong; Sawaya, Michael R.; Cheng, Pin-Nan; Zheng, Jing; Nowick, James S.; Eisenberg, David (UCI); (UCLA)

    2011-09-20

    Protein amyloid oligomers have been strongly linked to amyloid diseases and can be intermediates to amyloid fibers. {beta}-Sheets have been identified in amyloid oligomers. However, because of their transient and highly polymorphic properties, the details of their self-association remain elusive. Here we explore oligomer structure using a model system: macrocyclic peptides. Key amyloidogenic sequences from A{beta} and tau were incorporated into macrocycles, thereby restraining them to {beta}-strands, but limiting the growth of the oligomers so they may crystallize and cannot fibrillate. We determined the atomic structures for four such oligomers, and all four reveal tetrameric interfaces in which {beta}-sheet dimers pair together by highly complementary, dry interfaces, analogous to steric zippers found in fibers, suggesting a common structure for amyloid oligomers and fibers. In amyloid fibers, the axes of the paired sheets are either parallel or antiparallel, whereas the oligomeric interfaces display a variety of sheet-to-sheet pairing angles, offering a structural explanation for the heterogeneity of amyloid oligomers.

  3. Is Abeta a sufficient Biomarker for monitoring anti-Abeta clinical studies? A critical review.

    Directory of Open Access Journals (Sweden)

    Jens eMoreth

    2013-07-01

    Full Text Available Amyloid-beta (Aβ in Alzheimer’s disease (AD appeared to be a promising target for disease-modifying therapeutic strategies like passive immunotherapy with anti-Aβ monoclonal antibodies (mAbs. Biochemical markers in cerebrospinal fluid (CSF include alterations of Aβ that allow the diagnosis of AD. Biomarker strategies, such as the levels of Aβ in CSF and plasma, currently play an important role in early clinical trials for AD. Indeed, these strategies have a relevant impact on the outcome of such studies, since the biomarkers are used to monitor the bioactivity of anti-Aβ mAbs. The clinical trials of Solanezumab were mainly based on the readout of Aβ levels in CSF and plasma, whereas those of Bapineuzumab were based on cognition; however, little is known about the mechanisms altering these biomarker levels, and no biomarker has yet been proven to be a successful predictor for AD therapy. In addition, the Aβ biomarkers allow for the determination of free and bound anti-Aβ mAb in order to monitor the available amount of bioactive drug and could give hints to the mechanism of action. In this review, we discuss clinical Aβ biomarker data and the latest regulatory strategies.

  4. Modeling the interactions of a peptide-major histocompatibility class I ligand with its receptors. II. Cross-reaction between a monoclonal antibody and two alpha beta T cell receptors

    DEFF Research Database (Denmark)

    Rognan, D; Engberg, J; Stryhn, A;

    2000-01-01

    -peptide pair into the Fab combining site. Interestingly, the most energetically favored binding mode shows numerous analogies to the recently determined recognition of class I MHC-peptide complexes by alpha beta T cell receptors (TCRs). The pSAN13.4.1 also binds diagonally across the MHC binding groove...

  5. Mapping binding sites for the PDE4D5 cAMP-specific phosphodiesterase to the N- and C-domains of {beta}-arrestin using spot-immobilized peptide arrays

    OpenAIRE

    Baillie, G. S.; Adams, D. R.; Bhari, N.; Houslay, T.M.; Vadrevu, S.; Meng, D.; Li, X.; Dunlop, A.; Milligan, G.; Bolger, G.B.; Klussmann, E; Houslay, M.D.

    2007-01-01

    Beta2-ARs (beta2-adrenoceptors) become desensitized rapidly upon recruitment of cytosolic beta-arrestin. PDE4D5 (family 4 cAMP-specific phosphodiesterase, subfamily D, isoform 5) can be recruited in complex with beta-arrestin, whereupon it regulates PKA (cAMP-dependent protein kinase) phosphorylation of the beta2-AR. In the present study, we have used novel technology, employing a library of overlapping peptides (25-mers) immobilized on cellulose membranes that scan the entire sequence of bet...

  6. Expressions of Antimicrobial Peptides LL-37, Human Beta Defensin-2 and-3 in the Lesions of Cutaneous Tuberculosis and Tuberculids

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhao; Zhang-Lei Mu; Xi-Wan Liu; Xiao-Jing Liu; Jun Jia; Lin Cai; Jian-Zhong Zhang

    2016-01-01

    Background:Antimicrobial peptides,including cathelicidin LL-37,human beta defensin (HBD)-2,and HBD-3,are important elements of the innate immune response and involved in modulation of the adaptive immunity,and they also play an important role in cutaneous defense against Mycobacterium tuberculosis.Methods:The fresh skin tissues and paraffin-embedded biopsy samples from three cutaneous tuberculosis,two tuberculids,and ten healthy individuals were collected.The expressions of LL-37,HBD-2,and HBD-3 mRNA in the lesions of three cutaneous tuberculosis and two tuberculids were detected by quantitative real-time polymerase chain reaction;the protein expressions were detected by immunohistochemistry and Western blotting methods.Results:The expressions of LL-37 mRNA and protein in the lesions of cutaneous tuberculosis and tuberculids were similar to that of normal skin.The expression of HBD-2 mRNA had an increasing trend in the lesions of cutaneous tuberculosis and tuberculids compared with that of normal skin;however,the expression of HBD-2 protein in the lesions of cutaneous tuberculosis had a decreasing trend compared with that of normal skin,and the expression of HBD-2 protein in the lesions of tuberculids was similar to that of normal skin.The expressions of HBD-3 mRNA and protein in lesions of cutaneous tuberculosis and tuberculids were similar to that of normal skin.Conclusions:Our study indicated that the expression of HBD-2 and HBD-3 mRNA and protein in lesions of cutaneous tuberculosis may be not consistent with that oftuberculids.However,an inherent limitation of the present study was that the sample size was small,and the roles and regulation mechanisms ofLL-37,HBD-2,and HBD-3 in cutaneous tuberculosis and tuberculids need to be further investigated.

  7. Immunoreactive atrial natriuretic peptide and dopamine beta-hydroxylase in myocytes and chromaffin cells of the heart of the African lungfish, Protopterus aethiopicus.

    Science.gov (United States)

    Larsen, T H; Helle, K B; Saetersdal, T

    1994-07-01

    The heart of the African lungfish, Protopterus aethiopicus, was examined for immunoreactive atrial natriuretic peptide (ANP) and dopamine beta-hydroxylase (D beta H) as markers for hormone secreting myocytes and chromaffin cells, respectively. Specific antibodies raised against rat alpha-ANP and rat D beta H were used for immunofluorescence microscopy and immunogold electron microscopy. D beta H-immunoreactive cells were restricted to subendocardial areas of the atrium whereas ANP immunoreactivity occurred throughout both the atrial and the ventricular myocardium, showing particularly strong staining intensity in the atrial myocytes. The granular ANP immunostaining in the atrial myocytes was frequently accumulated in the sarcoplasm. In the ventricular myocytes ANP immunoreactivity occurred as scattered granular staining throughout the sarcoplasm. ANP and D beta H immunofluorescence staining coincided with the presence of immunoreactive specific granules and secretory vesicles in the cardiac myocytes and chromaffin cells, respectively, as revealed by electron microscopy. The number of ANP-containing specific granules was generally high in the atrial myocytes, and they were frequently observed in clusters in subsarcolemmal areas. Granular frequency was considerably lower and the mean granular diameter was smaller (0.142 +/- 0.045 micron versus 0.213 +/- 0.049 micron) in the ventricular than in the atrial myocytes. The present results indicate that ANP and D beta H are phylogenetically highly conserved proteins from the dipnoi to the rat. The large amounts of ANP and of specific granules are consistent with an endocrine myocardium in the Protopterus heart. The presence of D beta H and secretory vesicles in the subendocardial chromaffin cells of the atrium suggests a local production of catecholamines from dopamine in the heart of this dipnoan. PMID:7926645

  8. A highly sensitive peptide substrate for detecting two Aß-degrading enzymes: neprilysin and insulin-degrading enzyme.

    Science.gov (United States)

    Chen, Po-Ting; Liao, Tai-Yan; Hu, Chaur-Jong; Wu, Shu-Ting; Wang, Steven S-S; Chen, Rita P-Y

    2010-06-30

    Neprilysin has been singled out as the most promising candidate for use in the degradation of Abeta as a therapy for Alzheimer's disease. In this study, a quenched fluorogenic peptide substrate containing the first seven residues of the Abeta peptide plus a C-terminal Cysteine residue was synthesized to detect neprilysin activity. A fluorophore was attached to the C-terminal Cysteine and its fluorescence was quenched by a quencher linked to the N-terminus of the peptide. When this peptide substrate was degraded by an endopeptidase, fluorescence was produced and proved to be a sensitive detection system for endopeptidase activity. Our results showed that this assay system was extremely sensitive to neprilysin and insulin-degrading enzyme, but insensitive, or much less sensitive, to other Abeta-degrading enzymes. As low as 0.1 nM of neprilysin and 0.2 nM of insulin-degrading enzyme can be detected.

  9. Ciprofloxacin Affects Host Cells by Suppressing Expression of the Endogenous Antimicrobial Peptides Cathelicidins and Beta-Defensin-3 in Colon Epithelia

    Directory of Open Access Journals (Sweden)

    Protim Sarker

    2014-07-01

    Full Text Available Antibiotics exert several effects on host cells including regulation of immune components. Antimicrobial peptides (AMPs, e.g., cathelicidins and defensins display multiple functions in innate immunity. In colonic mucosa, cathelicidins are induced by butyrate, a bacterial fermentation product. Here, we investigated the effect of antibiotics on butyrate-induced expression of cathelicidins and beta-defensins in colon epithelial cells. Real-time PCR analysis revealed that ciprofloxacin and clindamycin reduce butyrate-induced transcription of the human cathelicidin LL-37 in the colonic epithelial cell line HT-29. Suppression of LL-37 peptide/protein by ciprofloxacin was confirmed by Western blot analysis. Immunohistochemical analysis demonstrated that ciprofloxacin suppresses the rabbit cathelicidin CAP-18 in rectal epithelia of healthy and butyrate-treated Shigella-infected rabbits. Ciprofloxacin also down-regulated butyrate-induced transcription of the human beta-defensin-3 in HT-29 cells. Microarray analysis of HT-29 cells revealed upregulation by butyrate with subsequent down-regulation by ciprofloxacin of additional genes encoding immune factors. Dephosphorylation of histone H3, an epigenetic event provided a possible mechanism of the suppressive effect of ciprofloxacin. Furthermore, LL-37 peptide inhibited Clostridium difficile growth in vitro. In conclusion, ciprofloxacin and clindamycin exert immunomodulatory function by down-regulating AMPs and other immune components in colonic epithelial cells. Suppression of AMPs may contribute to the overgrowth of C. difficile, causing antibiotic-associated diarrhea.

  10. Brain alterations and clinical symptoms of dementia in diabetes: Abeta/tau-dependent and independent mechanisms

    Directory of Open Access Journals (Sweden)

    Naoyuki eSato

    2014-09-01

    Full Text Available Emerging evidence suggests that diabetes affects cognitive function and increases the incidence of dementia. However, the mechanisms by which diabetes modifies cognitive function still remains unclear. Morphologically, diabetes is associated with neuronal loss in the frontal and temporal lobes including the hippocampus, and aberrant functional connectivity of the posterior cingulate cortex and medial frontal/temporal gyrus. Clinically, diabetic patients show decreased executive function, information processing, planning, visuospatial construction, and visual memory. Therefore, in comparison with the characteristics of AD brain structure and cognition, diabetes seems to affect cognitive function through not only simple AD pathological feature-dependent mechanisms, but also independent mechanisms. As an Abeta/tau-independent mechanism, diabetes compromises cerebrovascular function, increases subcortical infarction and might alter the blood brain barrier (BBB. Diabetes also affects glucose metabolism, insulin signaling and mitochondrial function in the brain. Diabetes also modifies metabolism of Abeta and tau and causes Abeta/tau-dependent pathological changes. Moreover, there is evidence that suggests an interaction between Abeta/tau-dependent and independent mechanisms. Therefore, diabetes modifies cognitive function through Abeta/tau-dependent and independent mechanisms. Interaction between these two mechanisms forms a vicious cycle.

  11. Cryogenic solid state NMR studies of fibrils of the Alzheimer's disease amyloid-{beta} peptide: perspectives for DNP

    Energy Technology Data Exchange (ETDEWEB)

    Lopez del Amo, Juan-Miguel [CIC Energigune (Spain); Schneider, Dennis [Bruker BioSpin (Germany); Loquet, Antoine; Lange, Adam [Max-Planck-Institut fuer Biophysikalische Chemie (Germany); Reif, Bernd, E-mail: reif@tum.de [Deutsches Forschungszentrum fuer Gesundheit und Umwelt, Helmholtz-Zentrum Muenchen (HMGU) (Germany)

    2013-08-15

    Dynamic Nuclear Polarization solid-state NMR holds the potential to enable a dramatic increase in sensitivity by exploiting the large magnetic moment of the electron. However, applications to biological solids are hampered in uniformly isotopically enriched biomacromolecules due to line broadening which yields a limited spectral resolution at cryogenic temperatures. We show here that high magnetic fields allow to overcome the broadening of resonance lines often experienced at liquid nitrogen temperatures. For a fibril sample of the Alzheimer's disease {beta}-amyloid peptide, we find similar line widths at low temperature and at room temperature. The presented results open new perspectives for structural investigations in the solid-state.

  12. Effects of beta-amyloid protein on M1 and M2 subtypes of muscarinic acetylcholine receptors in the medial septum-diagonal band complex of the rat: relationship with cholinergic, GABAergic, and calcium-binding protein perikarya.

    Science.gov (United States)

    González, Iván; Arévalo-Serrano, Juan; Sanz-Anquela, José Miguel; Gonzalo-Ruiz, Alicia

    2007-06-01

    Cortical cholinergic dysfunction has been correlated with the expression and processing of beta-amyloid precursor protein. However, it remains unclear as to how cholinergic dysfunction and beta-amyloid (Abeta) formation and deposition might be related to one another. Since the M1- and M2 subtypes of muscarinic acetylcholine receptors (mAChRs) are considered key molecules that transduce the cholinergic message, the purpose of the present study was to assess the effects of the injected Abeta peptide on the number of M1mAchR- and M2mAChR-immunoreactive cells in the medial septum-diagonal band (MS-nDBB) complex of the rat. Injections of Abeta protein into the retrosplenial cortex resulted in a decrease in M1mAChR and M2mAChR immunoreactivity in the MS-nDBB complex. Quantitative analysis revealed a significant reduction in the number of M1mAChR- and M2mAChR-immunoreactive cells in the medial septum nucleus (MS) and in the horizontal nucleus of the diagonal band of Broca (HDB) as compared to the corresponding hemisphere in control animals and with that seen in the contralateral hemisphere, which corresponds to the PBS-injected side. Co-localization studies showed that the M1mAChR protein is localized in GABA-immunoreactive cells of the MS-nDBB complex, in particular those of the MS nucleus, while M2mAChR protein is localized in both the cholinergic and GABAergic cells. Moreover, GABAergic cells containing M2mAChR are mainly localized in the MS nucleus, while cholinergic cells containing M2mAChR are localized in the MS and the HDB nuclei. Our findings suggest that Abeta induces a reduction in M1mAChR- and M2mAChR-containing cells, which may contribute to impairments of cholinergic and GABAergic transmission in the MS-nDBB complex.

  13. Differential protection among fractionated blueberry polyphenolic families against DA-, Abeta(42)- and LPS-induced decrements in Ca(2+) buffering in primary hippocampal cells.

    Science.gov (United States)

    Joseph, James A; Shukitt-Hale, Barbara; Brewer, Gregory J; Weikel, Karen A; Kalt, Wilhelmina; Fisher, Derek R

    2010-07-28

    It has been postulated that at least part of the loss of cognitive function in aging may be the result of deficits in Ca(2+) recovery (CAR) and increased oxidative/inflammatory (OX/INF) stress signaling. However, previous research showed that aged animals supplemented with blueberry (BB) extract showed fewer deficits in CAR, as well as motor and cognitive functional deficits. A recent subsequent experiment has shown that DA- or Abeta(42)-induced deficits in CAR in primary hippocampal neuronal cells (HNC) were antagonized by BB extract, and (OX/INF) signaling was reduced. The present experiments assessed the most effective BB polyphenol fraction that could protect against OX/INF-induced deficits in CAR, ROS generation, or viability. HNCs treated with BB extract, BB fractions (e.g., proanthocyanidin, PAC), or control medium were exposed to dopamine (DA, 0.1 mM), amyloid beta (Abeta(42), 25 muM) or lipopolysaccharide (LPS, 1 microg/mL). The results indicated that the degree of protection against deficits in CAR varied as a function of the stressor and was generally greater against Abeta(42) and LPS than DA. The whole BB, anthocyanin (ANTH), and PRE-C18 fractions offered the greatest protection, whereas chlorogenic acid offered the lowest protection. Protective capabilities of the various fractions against ROS depended upon the stressor, where the BB extract and the combined PAC (high and low molecular weight) fraction offered the best protection against LPS and Abeta(42) but were less effective against DA-induced ROS. The high and low molecular weight PACs and the ANTH fractions enhanced ROS production regardless of the stressor used, and this reflected increased activation of stress signals (e.g., P38 MAPK). The viability data indicated that the whole BB and combined PAC fraction showed greater protective effects against the stressors than the more fractionated polyphenolic components. Thus, these results suggest that, except for a few instances, the lesser the

  14. Improving cognitive impairment by Tongxinluo via inhibiting expression of beta-secretase 1/beta-amyloid peptide in experimental vascular dementia

    Institute of Scientific and Technical Information of China (English)

    Jia Jia; Wenbin Zhu; Lihui Wang; Yun Xu

    2008-01-01

    BACKGROUND: Tongxinluo has been clinically proven to be effective in improving memory and cognitive function in patients with post-stroke vascular dementia. Is the mechanism related to the deposition of beta-amyloid peptide (Aβ) in hippocampus? OBJECTIVE: To observe the effect of Tongxinluo on cognitive impairment in a mouse model with vascular dementia and the changes of Aβ deposition andβ-secretase 1 (BACE1) expression.DESIGN: Randomized controlled study.SETTING: State Key Laboratory of Pharmaceutical Biotechnology of Nanjing University and Affiliated Drum Tower Hospital of Nanjing University Medical School.MATERIALS: The experiment was carried out in the State Key Laboratory of Pharmaceutical Biotechnology of Nanjing University and Affiliated Drum Tower Hospital of Nanjing University Medical School from March 2006 to January 2007. A total of 36 healthy Kunming mice, 18 of each gender, were chosen. The study was conducted in accordance with the National Regulations of Experimental Animal Administration, and all animal experiments were approved by the Committee of Experimental Animal Administration of Nanjing University. Tongxinluo was provided by Shijiazhuang Yiling Pharmaceutical Co., Ltd.METHODS: All mice were randomly divided into 6 groups, including naive control (n=6), sham-operated control (n=6) and experimental groups treated with different doses of Tongxinluo (0.2, 0.4, and 0.6 g/kg/d; n=6 for each group) or vehicle (n=6). Five groups were subjected to bilateral common carotid arteries (2-VO) occlusion to produce a vascular dementia model(noocclusion was performed in sham-operated group). The mice in the Tongxinluo treatment groups were intragastricly administered daily with a Tongxinluo suspension (40 g/L in distilled water) at doses of 0.2, 0.4 or 0.6 g/kg/d from day 1 to day 30 post-surgery. The animals in vehicle, sham-operated and naive groups were administered an equal volume of distilled water. MAIN OUTCOME MEASURES: ①Escape latency time

  15. Glucagon-like peptide-1 induced signaling and insulin secretion do not drive fuel and energy metabolism in primary rodent pancreatic beta-cells.

    Directory of Open Access Journals (Sweden)

    Marie-Line Peyot

    Full Text Available BACKGROUND: Glucagon like peptide-1 (GLP-1 and its analogue exendin-4 (Ex-4 enhance glucose stimulated insulin secretion (GSIS and activate various signaling pathways in pancreatic beta-cells, in particular cAMP, Ca(2+ and protein kinase-B (PKB/Akt. In many cells these signals activate intermediary metabolism. However, it is not clear whether the acute amplification of GSIS by GLP-1 involves in part metabolic alterations and the production of metabolic coupling factors. METHODOLOGY/PRINICIPAL FINDINGS: GLP-1 or Ex-4 at high glucose caused release (approximately 20% of the total rat islet insulin content over 1 h. While both GLP-1 and Ex-4 markedly potentiated GSIS in isolated rat and mouse islets, neither had an effect on beta-cell fuel and energy metabolism over a 5 min to 3 h time period. GLP-1 activated PKB without changing glucose usage and oxidation, fatty acid oxidation, lipolysis or esterification into various lipids in rat islets. Ex-4 caused a rise in [Ca(2+](i and cAMP but did not enhance energy utilization, as neither oxygen consumption nor mitochondrial ATP levels were altered. CONCLUSIONS/SIGNIFICANCE: The results indicate that GLP-1 barely affects beta-cell intermediary metabolism and that metabolic signaling does not significantly contribute to GLP-1 potentiation of GSIS. The data also indicate that insulin secretion is a minor energy consuming process in the beta-cell, and that the beta-cell is different from most cell types in that its metabolic activation appears to be primarily governed by a "push" (fuel substrate driven process, rather than a "pull" mechanism secondary to enhanced insulin release as well as to Ca(2+, cAMP and PKB signaling.

  16. Injectable hydrogel as cell carriers: Mechanism of beta-hairpin peptide hydrogel shear thinning, immediate recovery and effects on encapsulated cell payload

    Science.gov (United States)

    Yan, Congqi

    To facilitate future biomedical treatment with localized delivery and higher therapy efficacy, much research effort has been devoted recently to the development of hydrogel biomaterials to transport a therapy to in vivo target sites via simple syringe or catheter injection. Most injectable hydrogel materials are free flowing precursor solutions ex vivo that become crosslinked into hydrogels once injected in vivo in response to exposure to environmental stimuli. However, properties of the final hydrogel formed in vivo are unpredictable due to possible leakage, dilution or change of injected gel precursor solution. As an alternate, more recent strategy for injectable hydrogel therapies, beta-hairpin peptide-based hydrogels are a class of injectable hydrogel solids with significant potential use in injectable therapies. These physical hydrogels can shear-thin and consequently flow as a low-viscosity material under a sufficient shear stress but immediately recover back into a solid upon removal of the stress, allowing them to be injected as preformed gel solids. The shear-thinning and immediate self-healing properties of self-assembled beta-hairpin peptide hydrogels enable a direct delivery of gel-encapsulated cells via benign injection to tissue defect sites with well-defined final gel properties in vivo. In this dissertation, mechanisms of gel shear-thinning and immediate recovery were elucidated by investigating gel behavior during and after flow via mechanical and structural characterizations. All studied beta-hairpin hydrogels shear-thin during flow (gel network fracture into large hydrogel domains) and instantly recover after cessation of flow (gel domains are percolated which immediately reforms the solid hydrogel). Importantly, hydrogel flow behavior was further studied in a capillary geometry that mimicked the actual situation of syringe injection. It was observed that all beta-hairpin peptide hydrogels investigated displayed a promising flow profile for

  17. Enhancement of Neurogenesis and Memory by a Neurotrophic Peptide in Mild to Moderate Traumatic Brain Injury

    Science.gov (United States)

    Chohan, Muhammad Omar; Bragina, Olga; Kazim, Syed Faraz; Statom, Gloria; Baazaoui, Narjes; Bragin, Denis; Iqbal, Khalid; Nemoto, Edwin; Yonas, Howard

    2016-01-01

    Background Traumatic Brain Injury (TBI) is a risk factor for Alzheimer disease (AD), a neurocognitive disorder with similar cellular abnormalities. We recently discovered a small molecule (Peptide 6) corresponding to an active region of human ciliary neurotrophic factor, with neurogenic and neurotrophic properties in mouse models of AD and Down syndrome. Objective To describe hippocampal abnormalities in a mouse model of mild to moderate TBI and their reversal by Peptide 6. Methods TBI was induced in adult C57Bl6 mice using controlled cortical impact (CCI) with 1.5 mm of cortical penetration. The animals were treated with 50 nmol/animal/day of Peptide 6 or saline for 30 days. Dentate gyrus (DG) neurogenesis, dendritic and synaptic density and AD biomarkers were quantitatively analyzed and behavioral tests were performed. Results Ipsilateral neuronal loss in CA1 and parietal cortex, and elevation of Alzheimer-type hyperphosphorylated tau and A-beta were seen in TBI-mice. When compared to saline, Peptide 6 treatment increased number of newborn neurons, but not uncommitted progenitors, in DG by 80%. Peptide 6 treatment also reversed TBI-induced dendritic and synaptic density loss while increasing activity in tri-synaptic hippocampal circuitry, ultimately leading to improvement in memory recall on behavioral testing. Conclusion Long-term treatment with Peptide 6 enhances the pool of newborn neurons in DG, prevents neuronal loss in CA1 and parietal cortex, preserves dendritic and synaptic architecture in the hippocampus, and improves performance on a hippocampus-dependent memory task in TBI mice. These findings necessitate further inquiry into therapeutic potential of small molecules based on neurotrophic factors. PMID:25255260

  18. Systematic determination of the peptide acceptor preferences for the human UDP-Gal:glycoprotein-alpha-GalNAc beta 3 galactosyltransferase (T-synthase).

    Science.gov (United States)

    Perrine, Cynthia; Ju, Tongzhong; Cummings, Richard D; Gerken, Thomas A

    2009-03-01

    Mucin-type protein O-glycosylation is initiated by the addition of alpha-GalNAc to Ser/Thr residues of a polypeptide chain. The addition of beta-Gal to GalNAc by the UDP-Gal:glycoprotein-alpha-GalNAc beta 3 galactosyltransferase (T-synthase), forming the Core 1 structure (beta-Gal(1-3)-alpha-GalNAc-O-Ser/Thr), is a common and biologically significant subsequent step in O-glycan biosynthesis. What dictates the sites of Core 1 glycosylation is poorly understood; however, the peptide sequence and neighboring glycosylation effects have been implicated. To systematically address the role of the peptide sequence on the specificity of T-synthase, we used the oriented random glycopeptide: GAGAXXXX(T-O-GalNAc)XXXXAGAG (where X = G, A, P, V, I, F, Y, S, N, D, E, H, R, and K) as a substrate. The Core 1 glycosylated product was isolated on immobilized PNA (Arachis hypogaea) lectin and its composition determined by Edman amino acid sequencing for comparison with the initial substrate composition, from which transferase preferences were obtained. From these studies, elevated preferences for Gly at the +1 position with moderately high preferences for Phe and Tyr in the +3 position relative to the acceptor Thr-O-GalNAc were found. A number of smaller Pro enhancements were also observed. Basic residues, i.e., Lys, Arg, and His, in any position were disfavored, suggesting electrostatic interactions as an additional important component modulating transferase specificity. This work suggests that there are indeed subtle specific and nonspecific protein-targeting sequence motifs for this transferase.

  19. Mapping binding sites for the PDE4D5 cAMP-specific phosphodiesterase to the N- and C-domains of beta-arrestin using spot-immobilized peptide arrays.

    Science.gov (United States)

    Baillie, George S; Adams, David R; Bhari, Narinder; Houslay, Thomas M; Vadrevu, Suryakiran; Meng, Dong; Li, Xiang; Dunlop, Allan; Milligan, Graeme; Bolger, Graeme B; Klussmann, Enno; Houslay, Miles D

    2007-05-15

    Beta2-ARs (beta2-adrenoceptors) become desensitized rapidly upon recruitment of cytosolic beta-arrestin. PDE4D5 (family 4 cAMP-specific phosphodiesterase, subfamily D, isoform 5) can be recruited in complex with beta-arrestin, whereupon it regulates PKA (cAMP-dependent protein kinase) phosphorylation of the beta2-AR. In the present study, we have used novel technology, employing a library of overlapping peptides (25-mers) immobilized on cellulose membranes that scan the entire sequence of beta-arrestin 2, to define the interaction sites on beta-arrestin 2 for binding of PDE4D5 and the cognate long isoform, PDE4D3. We have identified a binding site in the beta-arrestin 2 N-domain for the common PDE4D catalytic unit and two regions in the beta-arrestin 2 C-domain that confer specificity for PDE4D5 binding. Alanine-scanning peptide array analysis of the N-domain binding region identified severely reduced interaction with PDE4D5 upon R26A substitution, and reduced interaction upon either K18A or T20A substitution. Similar analysis of the beta-arrestin 2 C-domain identified Arg286 and Asp291, together with the Leu215-His220 region, as being important for binding PDE4D5, but not PDE4D3. Transfection with wild-type beta-arrestin 2 profoundly decreased isoprenaline-stimulated PKA phosphorylation of the beta2-AR in MEFs (mouse embryo fibroblasts) lacking both beta-arrestin 1 and beta-arrestin 2. This effect was negated using either the R26A or the R286A mutant form of beta-arrestin 2 or a mutant with substitution of an alanine cassette for Leu215-His220, which showed little or no PDE4D5 binding, but was still recruited to the beta2-AR upon isoprenaline challenge. These data show that the interaction of PDE4D5 with both the N- and C-domains of beta-arrestin 2 are essential for beta2-AR regulation. PMID:17288540

  20. Protective effects of Lingguizhugan decoction on amyloid-beta peptide (25-35)-induced cell injury Anti-inflammatory effects

    Institute of Scientific and Technical Information of China (English)

    Feifei Xi; Feng Sang; Chunxiang Zhou; Yun Ling

    2012-01-01

    In the present study, a human neuroblastoma cell line (SH-SY5Y) and BV-2 microglia were treated with amyloid-β peptide (25-35), as a model of Alzheimer's disease, to evaluate the protective effects of 10-3-10-8 g/mL Lingguizhugan decoction and to examine the underlying anti-inflammatory mechanism. Lingguizhugan decoction significantly enhanced the viability of SH-SY5Y cells with amyloid-β peptide-induced injury, and lowered levels of interleukin-1β, interleukin-6, tumor necrosis factor-α and nitric oxide in the culture supernatant of activated BV-2 microglia. The effects of 10-3 g/mL Lingguizhugan decoction were more significant. These results suggest that Lingguizhugan decoction can protect SH-SY5Y cells against amyloid-β peptide (25-35)-induced injury in a dose-dependent manner by inhibiting overexpression of inflammatory factors by activated microglia.

  1. Local atomic structure and oxidation processes of Cu(I) binding site in amyloid beta peptide: XAS Study

    Science.gov (United States)

    Kremennaya, M. A.; Soldatov, M. A.; Stretsov, V. A.; Soldatov, A. V.

    2016-05-01

    There are two different motifs of X-ray absorption spectra for Cu(I) K-edge in amyloid-β peptide which could be due to two different configurations of local Cu(I) environment. Two or three histidine ligands can coordinate copper ion in varying conformations. On the other hand, oxidation of amyloid-β peptide could play an additional role in local copper environment. In order to explore the peculiarities of local atomic and electronic structure of Cu(I) binding sites in amyloid-β peptide the x-ray absorption spectra were simulated for various Cu(I) environments including oxidized amyloid-β and compared with experimental data.

  2. Inhibition of cytosolic Phospholipase A2 prevents prion peptide-induced neuronal damage and co-localisation with Beta III Tubulin

    Directory of Open Access Journals (Sweden)

    Last Victoria

    2012-08-01

    Full Text Available Abstract Background Activation of phospholipase A2 (PLA2 and the subsequent metabolism of arachidonic acid (AA to prostaglandins have been shown to play an important role in neuronal death in neurodegenerative disease. Here we report the effects of the prion peptide fragment HuPrP106-126 on the PLA2 cascade in primary cortical neurons and translocation of cPLA2 to neurites. Results Exposure of primary cortical neurons to HuPrP106-126 increased the levels of phosphorylated cPLA2 and caused phosphorylated cPLA2 to relocate from the cell body to the cellular neurite in a PrP-dependent manner, a previously unreported observation. HuPrP106-126 also induced significant AA release, an indicator of cPLA2 activation; this preceded synapse damage and subsequent cellular death. The novel translocation of p-cPLA2 postulated the potential for exposure to HuPrP106-126 to result in a re-arrangement of the cellular cytoskeleton. However p-cPLA2 did not colocalise significantly with F-actin, intermediate filaments, or microtubule-associated proteins. Conversely, p-cPLA2 did significantly colocalise with the cytoskeletal protein beta III tubulin. Pre-treatment with the PLA2 inhibitor, palmitoyl trifluoromethyl ketone (PACOCF3 reduced cPLA2 activation, AA release and damage to the neuronal synapse. Furthermore, PACOCF3 reduced expression of p-cPLA2 in neurites and inhibited colocalisation with beta III tubulin, resulting in protection against PrP-induced cell death. Conclusions Collectively, these findings suggest that cPLA2 plays a vital role in the action of HuPrP106-126 and that the colocalisation of p-cPLA2 with beta III tubulin could be central to the progress of neurodegeneration caused by prion peptides. Further work is needed to define exactly how PLA2 inhibitors protect neurons from peptide-induced toxicity and how this relates to intracellular structural changes occurring in neurodegeneration.

  3. Expression of secreted human single-chain fragment variable antibody against human amyloid beta peptide in Pichia pastoris

    Institute of Scientific and Technical Information of China (English)

    Jiong Cai; Fang Li; Shizhen Wang

    2008-01-01

    BACKGROUND: Studies have shown that monoclonal or polyclonal antibody injections ofamyloid β peptide arc effective in removing amyloid β peptide overload in the brain.OBJECTIVE: Based on successful screening of a human single-chain fragment variable antibody specific to amyloid β peptide, this paper aimed to express recombinant human single-chain variable antibody against amyloid β peptide.DESIGN, TIME AND SETTING: A single sample experiment was performed at the Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Hospital (Beijing, China) from January to July 2006.MATERIALS: Human single-chain fragment variable antibody gene against amyloid β peptide was screened from a human phage-display antibody library.METHODS: Human single-chain fragment variable antibody gene was mutated to eliminate a BamHI restriction site and cloned into a Teasy plasmid for pT-seFvAβ construction, which was identified by PCR amplification and endonuclease digestion. Plasmid pT-scFvA β was cut by EcoRl and Notl endonucleases, and the antibody gene was cloned into pPIC9K plasmid to construct pPIC9K-scFvA β expression vector, which was confirmed by gene sequencing. Linearized pPICgK-scFvA β was used to transform a Pichia pastoris GS115 cell line, and the recombinant was induced by 0.5 % methanol to express human single-chain fragment variable antibody specific to amyloid β peptide.MAIN OUTCOME MEASURES: Protein electrophoresis was used to identify PCR products, gene sequencing was uscd to verify the pPIC9K-scFvA sequence, and SDS-PAGE was used to detect recombinant expression of human single-chain fragment variable antibody specific to amyloid β peptide in Pichia pastoris.RESULTS: Gene sequencing confirmed pPICgK-scFvA β orientation. Rccomhinants were obtained by lineadzed pPIC9K-scFvA β transformation. After induction with 0.5% methanol, the recombinant yeast cells secreted proteins of 33-ku size

  4. Protective effects of Lingguizhugan decoction on amyloid-beta peptide (25-35)-induced cell injury: Anti-inflammatory effects☆

    OpenAIRE

    Xi, Feifei; Sang, Feng; Zhou, Chunxiang; Ling, Yun

    2012-01-01

    In the present study, a human neuroblastoma cell line (SH-SY5Y) and BV-2 microglia were treated with amyloid-β peptide (25–35), as a model of Alzheimer’s disease, to evaluate the protective effects of 10-3–10-8 g/mL Lingguizhugan decoction and to examine the underlying anti-inflammatory mechanism. Lingguizhugan decoction significantly enhanced the viability of SH-SY5Y cells with amyloid-β peptide-induced injury, and lowered levels of interleukin-1β, interleukin-6, tumor necrosis factor-α and ...

  5. Oxyntomodulin differentially affects glucagon-like peptide-1 receptor beta-arrestin recruitment and signaling through Galpha(s)

    DEFF Research Database (Denmark)

    Jorgensen, Rasmus; Kubale, Valentina; Vrecl, Milka;

    2007-01-01

    The glucagon-like peptide (GLP)-1 receptor is a promising target for the treatment of type 2 diabetes and obesity, and there is great interest in characterizing the pharmacology of the GLP-1 receptor and its ligands. In the present report, we have applied bioluminescence resonance energy transfer...

  6. Role of T-cell receptor V beta 8.3 peptide vaccine in the prevention of experimental autoimmune uveoretinitis

    NARCIS (Netherlands)

    Zhang, R.; Yang, P.Z.; Wu, C.Y.; Jin, H.L.; Li, B.; Huang, X.; Zhou, H.; Gao, Y.; Zhu, L.; Kijlstra, A.

    2006-01-01

    T-cell receptor (TCR) plays an important role in the development of autoimmune diseases. Recently, it was reported that immunization of animals with TCR peptide derived from the pathogenic cells could prevent autoimmune diseases. The aim of this study was to investigate whether vaccination with a sy

  7. Oxidative stress induces macroautophagy of amyloid beta-protein and ensuing apoptosis

    DEFF Research Database (Denmark)

    Zheng, Lin; Kågedal, Katarina; Dehvari, Nodi;

    2009-01-01

    There is increasing evidence for the toxicity of intracellular amyloid beta-protein (Abeta) to neurons and the involvement of lysosomes in this process in Alzheimer disease (AD). We have recently shown that oxidative stress, a recognized determinant of AD, enhances macroautophagy and leads to int...

  8. Peptide-beta2-microglobulin-major histocompatibility complex expressing cells are potent antigen-presenting cells that can generate specific T cells.

    Science.gov (United States)

    Obermann, Sonja; Petrykowska, Susanne; Manns, Michael P; Korangy, Firouzeh; Greten, Tim F

    2007-09-01

    Adoptive T-cell therapy represents a promising therapeutic approach for the treatment of cancer. Successful adoptive immunotherapy depends on the ex vivo priming and expansion of antigen-specific T cells. However, the in vitro generation of adequate numbers of functional antigen-specific T cell remains a major obstacle. It is important to develop efficient and reproducible methods to generate high numbers of antigen-specific T cells for adoptive T-cell transfer. We have developed a new artificial antigen-presenting cell (aAPC) by transfection of major histocompatibility (MHC) class I negative Daudi cells with a peptide-beta2-microglobulin-MHC fusion construct (single-chain aAPC) ensuring presentation of the peptide-MHC complex of interest. Using this artificial antigen-presenting cell, we could generate up to 9.2 x 10(8) antigen-specific cytotoxic CD8(+) T cells from 10 ml blood. In vitro generated T cells lysed endogenously presented antigens. Direct comparison of the single-chain aAPC with autologous monocyte-derived dendritic cells demonstrated that these cells were equally efficient in stimulation of T cells. Finally, we were able to generate antigen-specific T cell lines from perpheral blood mononuclear cells of patients receiving cytotoxic chemotherapy. The use of single-chain aAPC represent a promising option for the generation of antigen-specific CD8(+) T cells, which could be used for adoptive T-cell therapy.

  9. Regulation of adenosine triphosphate-sensitive potassium channels suppresses the toxic effects of amyloid-beta peptide (25-35)

    Institute of Scientific and Technical Information of China (English)

    Min Kong; Maowen Ba; Hui Liang; Peng Shao; Tianxia Yu; Ying Wang

    2013-01-01

    In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide (25-35) for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide (25-35) decreased PC12 cell viability, but adenosine triphosphate-sensitive potassium channel activator diazoxide suppressed the decrease reactive oxygen species levels. These protective effects were reversed by the selective mitochondrial adenosine triphosphate-sensitive potassium channel blocker 5-hydroxydecanoate. An inducible nitric oxide synthase inhibitor, Nω-nitro-L-arginine, also protected PC12 cells from intracellular reactive oxygen species levels. However, the H2O2-degrading enzyme catalase could that the increases in both mitochondrial membrane potential and reactive oxygen species levels adenosine triphosphate-sensitive potassium channels and nitric oxide. Regulation of adenosine triphosphate-sensitive potassium channels suppresses PC12 cell cytotoxicity induced by amyloid-β

  10. Amyloid-Beta Peptide, Oxidative Stress and Inflammation in Alzheimer's Disease: Potential Neuroprotective Effects of Omega-3 Polyunsaturated Fatty Acids

    OpenAIRE

    S. C. Dyall

    2010-01-01

    Alzheimer's disease is the most common form of dementia in the elderly and is a progressive neurodegenerative disorder characterised by a decline in cognitive function and also profound alterations in mood and behaviour. The pathology of the disease is characterised by the presence of extracellular amyloid peptide deposits and intracellular neurofibrillary tangles in the brain. Although many hypotheses have been put forward for the aetiology of the disease, increased inflammation and oxidativ...

  11. Glucagon-like peptide-1 counteracts the detrimental effects of Advanced Glycation End-Products in the pancreatic beta cell line HIT-T 15

    Energy Technology Data Exchange (ETDEWEB)

    Puddu, A., E-mail: alep100@hotmail.com [University of Genova, Department of Internal Medicine and Medical Specialties, Viale Benedetto XV, 16132 Genova (Italy); Storace, D.; Durante, A.; Odetti, P.; Viviani, G.L. [University of Genova, Department of Internal Medicine and Medical Specialties, Viale Benedetto XV, 16132 Genova (Italy)

    2010-07-30

    Research highlights: {yields} GLP-1 prevents AGEs-induced cell death. {yields} GLP-1 prevents AGEs-induced oxidative stress. {yields} GLP-1 ameliorated AGEs-induced cell dysfunction. {yields} GLP-1 attenuates AGEs-induced RAGE increment. {yields} GLP-1 counteracts AGEs-induced pancreatic cell death and dysfunction. -- Abstract: Advanced Glycation End-Products (AGEs), a group of compounds resulting from the non-enzymatic reaction of reducing sugars with the free amino group of proteins, are implicated in diabetic complications. We previously demonstrated that exposure of the pancreatic islet cell line HIT-T 15 to high concentrations of AGEs significantly decreases cell proliferation and insulin secretion, and affects transcription factors regulating insulin gene transcription. The glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases proinsulin biosynthesis, stimulates insulin secretion, and improves pancreatic beta-cell viability. The aim of this work was to investigate the effects of GLP-1 on the function and viability of HIT-T 15 cells cultured with AGEs. HIT-T 15 cells were cultured for 5 days in presence of AGEs alone, or supplemented with 10 nmol/l GLP-1. Cell viability, insulin secretion, redox balance, and expression of the AGEs receptor (RAGE) were then determined. The results showed that GLP-1 protected beta cell against AGEs-induced cell death preventing both apoptosis and necrosis. Moreover, addition of GLP-1 to the AGEs culture medium restored the redox balance, improved the responsiveness to glucose, and attenuated AGEs-induced RAGE expression. These findings provide evidence that GLP-1 protects beta cells from the dangerous effects of AGEs.

  12. Glucagon-like peptide-1 counteracts the detrimental effects of Advanced Glycation End-Products in the pancreatic beta cell line HIT-T 15

    International Nuclear Information System (INIS)

    Research highlights: → GLP-1 prevents AGEs-induced cell death. → GLP-1 prevents AGEs-induced oxidative stress. → GLP-1 ameliorated AGEs-induced cell dysfunction. → GLP-1 attenuates AGEs-induced RAGE increment. → GLP-1 counteracts AGEs-induced pancreatic cell death and dysfunction. -- Abstract: Advanced Glycation End-Products (AGEs), a group of compounds resulting from the non-enzymatic reaction of reducing sugars with the free amino group of proteins, are implicated in diabetic complications. We previously demonstrated that exposure of the pancreatic islet cell line HIT-T 15 to high concentrations of AGEs significantly decreases cell proliferation and insulin secretion, and affects transcription factors regulating insulin gene transcription. The glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases proinsulin biosynthesis, stimulates insulin secretion, and improves pancreatic beta-cell viability. The aim of this work was to investigate the effects of GLP-1 on the function and viability of HIT-T 15 cells cultured with AGEs. HIT-T 15 cells were cultured for 5 days in presence of AGEs alone, or supplemented with 10 nmol/l GLP-1. Cell viability, insulin secretion, redox balance, and expression of the AGEs receptor (RAGE) were then determined. The results showed that GLP-1 protected beta cell against AGEs-induced cell death preventing both apoptosis and necrosis. Moreover, addition of GLP-1 to the AGEs culture medium restored the redox balance, improved the responsiveness to glucose, and attenuated AGEs-induced RAGE expression. These findings provide evidence that GLP-1 protects beta cells from the dangerous effects of AGEs.

  13. A systematic review of amyloid-beta peptides as putative mediators of the association between affective disorders and Alzheimer's disease

    DEFF Research Database (Denmark)

    Abbasowa, L.; Heegaard, N. H. H.

    2014-01-01

    to the application of different assay formats, study results indicate a potentially altered amyloid-beta metabolism in affective disorder. Limitations: Since most studies used a cross-sectional design, causality is difficult to establish. Moreover, methodological rigor of included studies varied and several studies......-beta concentrations change over time and are associated with cognition as well as affective symptomatology, future research should include prospective, longitudinal studies, implemented in large study populations, where peripheral and central amyloid-p ratios are quantified concomitantly and continuously across...... various affective phases. Also, to enable inter survey comparisons, the use of standardized pre-analytical/analytical procedures is crucial. (C) 2014 Elsevier B.V. All rights reserved....

  14. An Investigation on the Fundamental Interaction between Abeta Peptides and the AT-Rich DNA.

    Science.gov (United States)

    Zhao, Li Na; Zheng, Jie; Chew, Lock Yue; Mu, Yuguang

    2015-07-01

    DNA damage is ubiquitous in all mammalian cells with the occurrence of more than 60,000 times per day per cell. In particular, DNA damage in neurons is found to accumulate with age and has been suggested to interfere with the synthesis of functional proteins. Moreover, recent studies have found through transgenic mice that human amyloid precursor protein causes an increase in DNA double-strand breaks (DSBs) with the effect of a prolongation in DNA repair. It is surmised that amyloid β (Aβ) exacerbates the DNA DSBs in neurons, possibly engendering neuronal dysfunction as a result. However, a good understanding on the holistic interaction mechanisms and the manner in which Aβ intertwines with DNA damage is still in its infancy. In our study, we found that DNA with an AT-rich sequence has a very low binding affinity toward Aβ by means of molecular dynamics simulation. While we have pursued a particular sequence of DNA in this study, other DNA sequences are expected to affect the interaction and binding affinity between DNA and Aβ, and will be pursued in our further research. Nonetheless, we have uncovered favorable interaction between the positively charged side chain of Aβ and the two ends of DNA. The latest experiment reveals that many of the double-stranded breaks in neurons can be fixed via DNA repair mechanisms but not in the case that Aβs are present. It is found that the increased numbers of DSBs prevail in active neurons. Here, on the basis of the favorable interaction between Aβ and the two ends of DNA, we propose the possibility that Aβ prevents DNA repair via binding directly to the break ends of the DNA, which further exacerbates DNA damage. Moreover, we have found that the base pair oxygen of the DNA has a greater preference to form hydrogen bonds than the backbone oxygen with Aβ at the two ends. Thus, we postulate that Aβ could serve to prevent the repair of AT-rich DNA, and it is unlikely to cause its breakage or affect its binding toward histone. Another important observation from our study is that AT-rich DNA has very little or no influence on Aβ oligomerization. Finally, even though we do not observe any dramatic DNA conformational change in the presence of Aβ, we do observe an increase in diversity of the DNA structural parameters such as groove width, local base step, and torsional angles in lieu of Aβ interactions.

  15. Identification of a cell-penetrating peptide domain from human beta-defensin 3 and characterization of its anti-inflammatory activity

    Directory of Open Access Journals (Sweden)

    Lee JY

    2015-08-01

    Full Text Available Jue Yeon Lee,1,* Jin Sook Suh,2,* Jung Min Kim,1 Jeong Hwa Kim,1 Hyun Jung Park,1 Yoon Jeong Park,1,2 Chong Pyoung Chung1 1Central Research Institute, Nano Intelligent Biomedical Engineering Corporation (NIBEC, Chungcheongbuk-do, Republic of Korea; 2Dental Regenerative Biotechnology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea *These authors contributed equally to this work Abstract: Human beta-defensins (hBDs are crucial factors of intrinsic immunity that function in the immunologic response to a variety of invading enveloped viruses, bacteria, and fungi. hBDs can cause membrane depolarization and cell lysis due to their highly cationic nature. These molecules participate in antimicrobial defenses and the control of adaptive and innate immunity in every mammalian species and are produced by various cell types. The C-terminal 15-mer peptide within hBD3, designated as hBD3-3, was selected for study due to its cell- and skin-penetrating activity, which can induce anti-inflammatory activity in lipopolysaccharide-treated RAW 264.7 macrophages. hBD3-3 penetrated both the outer membrane of the cells and mouse skin within a short treatment period. Two other peptide fragments showed poorer penetration activity compared to hBD3-3. hBD3-3 inhibited the lipopolysaccharide-induced production of inducible nitric oxide synthase, nitric oxide, and secretory cytokines, such as interleukin-6 and tumor necrosis factor in a concentration-dependent manner. Moreover, hBD3-3 reduced the interstitial infiltration of polymorphonuclear leukocytes in a lung inflammation model. Further investigation also revealed that hBD3-3 downregulated nuclear factor kappa B-dependent inflammation by directly suppressing the degradation of phosphorylated-IκBα and by downregulating active nuclear factor kappa B p65. Our findings indicate that hBD3-3 may be conjugated with drugs of interest to ensure their proper translocation to

  16. Molecular Bases for the Recognition of Short Peptide Substrates and Cysteine-Directed Modifications of Human Insulin-Degrading Enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Malito, Enrico; Ralat, Luis A.; Manolopoulou, Marika; Tsay, Julie L.; Wadlington, Natasha L.; Tang, Wei-Jen (UC)

    2009-12-01

    Insulin degrading enzyme (IDE) utilizes a large catalytic chamber to selectively bind and degrade peptide substrates such as insulin and amyloid {beta} (A{beta}). Tight interactions with substrates occur at an exosite located 30 {angstrom} away from the catalytic center that anchors the N-terminus of substrates to facilitate binding and subsequent cleavages at the catalytic site. However, IDE also degrades peptide substrates that are too short to occupy both the catalytic site and the exosite simultaneously. Here, we use kinins as a model system to address the kinetics and regulation of human IDE with short peptides. IDE specifically degrades bradykinin and kallidin at the Pro/Phe site. A 1.9 {angstrom} crystal structure of bradykinin-bound IDE reveals the binding of bradykinin to the exosite and not to the catalytic site. In agreement with observed high K{sub m} values, this suggests low affinity of bradykinin for IDE. This structure also provides the molecular basis on how the binding of short peptides at the exosite could regulate substrate recognition. We also found that human IDE is potently inhibited by physiologically relevant concentrations of S-nitrosylation and oxidation agents. Cysteine-directed modifications play a key role, since an IDE mutant devoid of all 13 cysteines is insensitive to the inhibition by S-nitrosoglutathione, hydrogen peroxide, or N-ethylmaleimide. Specifically, cysteine 819 of human IDE is located inside the catalytic chamber pointing toward an extended hydrophobic pocket and is critical for the inactivation. Thiol-directed modification of this residue likely causes local structural perturbation to reduce substrate binding and catalysis.

  17. Association of cardiovascular factors and Alzheimer's disease plasma amyloid-beta protein in subjective memory complainers.

    Science.gov (United States)

    Bates, Kristyn A; Sohrabi, Hamid R; Rodrigues, Mark; Beilby, John; Dhaliwal, Satvinder S; Taddei, Kevin; Criddle, Arthur; Wraith, Megan; Howard, Matthew; Martins, Georgia; Paton, Athena; Mehta, Pankaj; Foster, Jonathan K; Martins, Ian J; Lautenschlager, Nicola T; Mastaglia, Frank L; Laws, Simon M; Gandy, Samuel E; Martins, Ralph N

    2009-01-01

    A strong link is indicated between cardiovascular disease (CVD) and risk for developing Alzheimer's disease (AD), which may be exacerbated by the major AD genetic risk factor apolipoprotein Eepsilon4 (APOEepsilon4). Since subjective memory complaint (SMC) may potentially be an early indicator for cognitive decline, we examined CVD risk factors in a cohort of SMC. As amyloid-beta (Abeta) is considered to play a central role in AD, we hypothesized that the CVD risk profile (increased LDL, reduced HDL, and increased body fat) would be associated with plasma Abeta levels. We explored this in 198 individuals with and without SMC (average age = 63 years). Correlations between Abeta40 and HDL were observed, which were stronger in non-APOEepsilon4 carriers (rho = -0.315, p association between HDL and Abeta, which if demonstrated to be causal has implications for the development of lifestyle interventions and/or novel therapeutics. The relationship between HDL and Abeta and the potential significance of such an association needs to be validated in a larger longitudinal study.

  18. Dipolar recoupling NMR of biomolecular self-assemblies : determining inter- and intrastrand distances in fibrilized Alzheimer's {betta}-amyloid peptide.

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, D. M.; Senzinger, T. L. S.; Burkoth, T. S.; Miller-Auer, H.; Lynn, D. G.; Meredith, S. C.; Botto, R. E.; Chemistry; Univ. of Chicago

    1998-12-01

    We demonstrate a new method for investigating the structure of self-associating biopolymers using dipolar recoupling NMR techniques. This approach was applied to the study of fibrillar {beta}-amyloid (A{beta}) peptides (the primary component of the plaques of Alzheimer's disease) containing only a single isotopic spin label ({sup 13}C), by employing the DRAWS (dipolar recoupling with a windowless sequence) technique to measure {sup 13}C-{sup 13}C distances. The 'single-label' approach simplified analysis of DRAWS data, since only interstrand contacts are present, without the possibility of any intrastrand contacts. As previously reported [T.L.S. Benzinger, D.M. Gregory, T.S. Burkoth, H. Miller-Auer, D.G. Lynn, R.E. Botto, S.C. Meredith, Proc. Natl. Acad. Sci. 95 (1998) 13407.], contacts of approximately 5 {angstrom} were observed at all residues studied, consistent with an extended parallel {beta}-sheet structure with each amino acid in exact register. Here, we propose that our strategy is completely generalizable, and provides a new approach for characterizing any iterative, self-associating biopolymer. Towards the end of generalizing and refining our approach, in this paper we evaluate several issues raised by our previous analyses. First, we consider the effects of double-quantum (DQ) transverse relaxation processes. Next, we discuss the effects of various multiple-spin geometries on modeling of DRAWS data. Several practical issues are also discussed: these include (1) the use of DQ filtering experiments, either to corroborate DRAWS data, or as a rapid screening assessment of the proper placement of isotopic spin labels; and (2) the comparison of solid samples prepared by either lyophilization or freezing. Finally, data obtained from the use of single labels is compared with that obtained in doubly {sup 13}C-labeled model compounds of known crystal structure. It is shown that such data are obtainable in far more complex peptide molecules. These

  19. Radioiodinated benzimidazole derivatives as single photon emission computed tomography probes for imaging of {beta}-amyloid plaques in Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Cui Mengchao [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Ono, Masahiro, E-mail: ono@pharm.kyoto-u.ac.j [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Kimura, Hiroyuki; Kawashima, Hidekazu [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Liu Boli [Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875 (China); Saji, Hideo, E-mail: hsaji@pharm.kyoto-u.ac.j [Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan)

    2011-04-15

    Five iodinated 2-phenyl-1H-benzo[d]imidazole derivatives were synthesized and evaluated as potential probes for {beta}-amyloid (A{beta}) plaques. One of the compounds, 4-(6-iodo-1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (12), showed excellent affinity for A{beta}{sub 1-42} aggregates (K{sub i}=9.8 nM). Autoradiography with sections of postmortem Alzheimer's disease (AD) brain revealed that a radioiodinated probe [{sup 125}I]12, labeled A{beta} plaques selectively with low nonspecific binding. Biodistribution experiments with normal mice injected intravenously with [{sup 125}I]12 showed high uptake [4.14 percent injected dose per gram (% ID/g) at 2 min] into and rapid clearance (0.15% ID/g at 60 min) from the brain, which may bring about a good signal-to-noise ratio and therefore achieve highly sensitive detection of A{beta} plaques. In addition, [{sup 125}I]12 labeled amyloid plaques in vivo in an AD transgenic model. The preliminary results strongly suggest that [{sup 125}I]12 bears characteristics suitable for detecting amyloid plaques in vivo. When labeled with {sup 123}I, it may be a useful SPECT imaging agent for A{beta} plaques in the brain of living AD patients.

  20. Amyloid beta protein and tau in cerebrospinal fluid and plasma as biomarkers for dementia: a review of recent literature.

    NARCIS (Netherlands)

    Frankfort, S.V.; Tulner, L.R.; Campen, J.P. van; Verbeek, M.M.; Jansen, R.W.; Beijnen, J.H.

    2008-01-01

    This review addresses recent developments in amyloid beta (Abeta), total tau (t-tau), and phosporylated tau (p-tau) protein analysis, in cerebrospinal fluid (CSF) and plasma as biomarkers for dementia. Recent research focused on the protection of patients with mild cognitive impairment (MCI) into de

  1. Characterization of the pattern of alphas1- and beta-casein breakdown and release of a bioactive peptide by a cell envelope proteinase from Lactobacillus delbrueckii subsp. lactis CRL 581.

    Science.gov (United States)

    Hebert, Elvira María; Mamone, Gianfranco; Picariello, Gianluca; Raya, Raúl R; Savoy, Graciela; Ferranti, Pasquale; Addeo, Francesco

    2008-06-01

    The cell envelope-associated proteinases (CEPs) of the lactobacilli have key roles in bacterial nutrition and contribute to the development of the organoleptic properties of fermented milk products as well, as they can release bioactive health-beneficial peptides from milk proteins. The influence of the peptide supply, carbohydrate source, and osmolites on the CEP activity of the cheese starter Lactobacillus delbrueckii subsp. lactis CRL 581 was investigated. The CEP activity levels were controlled by the peptide content of the growth medium. The maximum activity was observed in a basal minimal defined medium, whereas in the presence of Casitone, Casamino Acids, or yeast extract, the synthesis of CEP was inhibited 99-, 70-, and 68-fold, respectively. The addition of specific di- or tripeptides containing branched-chain amino acids, such as leucylleucine, prolylleucine, leucylglycylglycine, or leucylproline, to the growth medium negatively affected CEP activity, whereas dipeptides without branched-chain amino acids had no effect on the enzyme's production. The carbon source and osmolites did not affect CEP activity. The CEP of L. delbrueckii subsp. lactis CRL 581 exhibited a mixed-type CEP(I/III) variant caseinolytic specificity. Mass-spectrometric screening of the main peptide peaks isolated by reverse-phase high-pressure liquid chromatography allowed the identification of 33 and 32 peptides in the alpha(s1)- and beta-casein hydrolysates, respectively. By characterizing the peptide sequence in these hydrolysates, a pattern of alpha(s1)- and beta-casein breakdown was defined and is reported herein, this being the first report for a CEP of L. delbrueckii subsp. lactis. In this pattern, a series of potentially bioactive peptides (antihypertensive and phosphopeptides) which are encrypted within the precursor protein could be visualized. PMID:18424544

  2. Transforming growth factor-beta inhibition reduces progression of early choroidal neovascularization lesions in rats: P17 and P144 peptides.

    Directory of Open Access Journals (Sweden)

    Javier Zarranz-Ventura

    Full Text Available The purpose of this study was to assess the effects of transforming growth factor beta (TGF-β inhibitor peptides (P17 & P144 on early laser-induced choroidal neovascularization (LI-CNV lesions in rats, two weeks after laser CNV induction. Seventy-one Long Evans rats underwent diode laser application in an established LI-CNV model. Baseline fluorescein angiography (FA was performed 14 days following laser procedure, and treatments were administered 16 days post-laser application via different administration routes. Intravenous groups included control (IV-Control, P17 (IV-17, and P144 (IV-144 groups, whereas intravitreal groups included P17 (IVT-17, P144 (IVT-144, and a mixture of both peptides (IVT-17+144 (with fellow eyes receiving vehicle alone. CNV evolution was assessed using FA performed weekly for four weeks after treatment. Following sacrifice, VEGF, TGF-β, COX-2, IGF-1, PAI-1, IL-6, MMP-2, MMP-9, and TNF-α gene expression was assessed using RT-PCR. VEGF and p-SMAD2 protein levels were also assessed by western-blot, while MMP-2 activity was assessed with gelatin zymography. Regarding the FA analysis, the mean CNV area was lower from the 3(rd week in IVT-17 and IVT-144 groups, and also from the 2(nd week in IVT-17+144. Biochemical analysis revealed that gene expression was lower for VEGF and COX-2 genes in IV-17 and IV-144 groups, VEGF gene in IVT-17+144 group and MMP-2 gene in IVT-17 and IVT-144 groups. VEGF protein expression was also decreased in IV-17, IV-144, IVT-17 and IVT-144, whereas pSMAD-2 levels were lower in IV-17, IV-144 and IVT-17+144 groups. Zymogram analysis revealed decreased MMP-2 activity in IV-17, IV-144, IVT-17 and IVT-144 groups. These data suggest that the use of TGF-β inhibitor peptides (P17 & P144 decrease the development of early CNV lesions by targeting different mediators than those typically affected using current anti-angiogenic therapies. Its potential role in the treatment of early CNV appears promising

  3. 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR attenuates the expression of LPS- and Aβ peptide-induced inflammatory mediators in astroglia

    Directory of Open Access Journals (Sweden)

    Giri Shailendra

    2005-09-01

    Full Text Available Abstract Background Alzheimer's disease (AD pathology shows characteristic 'plaques' rich in amyloid beta (Aβ peptide deposits. Inflammatory process-related proteins such as pro-inflammatory cytokines have been detected in AD brain suggesting that an inflammatory immune reaction also plays a role in the pathogenesis of AD. Glial cells in culture respond to LPS and Aβ stimuli by upregulating the expression of cytokines TNF-α, IL-1β, and IL-6, and also the expression of proinflammatory genes iNOS and COX-2. We have earlier reported that LPS/Aβ stimulation-induced ceramide and ROS generation leads to iNOS expression and nitric oxide production in glial cells. The present study was undertaken to investigate the neuroprotective function of AICAR (a potent activator of AMP-activated protein kinase in blocking the pro-oxidant/proinflammatory responses induced in primary glial cultures treated with LPS and Aβ peptide. Methods To test the anti-inflammatory/anti-oxidant functions of AICAR, we tested its inhibitory potential in blocking the expression of pro-inflammatory cytokines and iNOS, expression of COX-2, generation of ROS, and associated signaling following treatment of glial cells with LPS and Aβ peptide. We also investigated the neuroprotective effects of AICAR against the effects of cytokines and inflammatory mediators (released by the glia, in blocking neurite outgrowth inhibition, and in nerve growth factor-(NGF induced neurite extension by PC-12 cells. Results AICAR blocked LPS/Aβ-induced inflammatory processes by blocking the expression of proinflammatory cytokine, iNOS, COX-2 and MnSOD genes, and by inhibition of ROS generation and depletion of glutathione in astroglial cells. AICAR also inhibited down-stream signaling leading to the regulation of transcriptional factors such as NFκB and C/EBP which are critical for the expression of iNOS, COX-2, MnSOD and cytokines (TNF-α/IL-1β and IL-6. AICAR promoted NGF-induced neurite growth

  4. Imaging integrin alpha-v-beta-3 expression in tumors with an 18F-labeled dimeric RGD peptide

    Science.gov (United States)

    Dijkgraaf, Ingrid; Terry, Samantha; McBride, William J.; Goldenberg, David M.; Laverman, Peter; Franssen, Gerben M.; Oyen, Wim J. G.; Boerman, Otto C.

    2014-01-01

    Integrin αvβ3 receptors are expressed on activated endothelial cells during neovascularization to maintain tumor growth. Many radiolabeled probes utilize the tight and specific association between the arginine-glycine-aspartatic acid (RGD) peptide and integrin αvβ3, but one main obstacle for any clinical application of these probes is the laborious multistep radiosynthesis of 18F. In this study, the dimeric RGD peptide, E-[c(RGDfK)]2, was conjugated with NODAGA and radiolabeled with 18F in a simple one-pot process with a radiolabeling yield of 20%; the whole process lasting only 45 min. NODAGA-E-[c(RGDfK)]2 labeled with 18F at a specific activity of 1.8 MBq/nmol and a radiochemical purity of 100% could be achieved. Log P value of 18F-labeled NODAGA-E-[c(RGDfK)]2 was −4.26 ± 0.02. In biodistribution studies, 18F-NODAGA-E-[c(RGDfK)]2 cleared rapidly from the blood with 0.03 ± 0.01 %ID/g in the blood at 2 h p.i., mainly via the kidneys and showed good in vivo stability. Tumor uptake of 18F-NODAGA-E-[c(RGDfK)]2 (3.44 ± 0.20 %ID/g, 2 h p.i.) was significantly lower than that of reference compounds 68Ga-labeled NODAGA-E-[c(RGDfK)]2 (6.26 ± 0.76 %ID/g; P <0.001) and 111In-labeled NODAGA-E-[c(RGDfK)]2 (4.99 ± 0.64 %ID/g; P < 0.01). Co-injection of an excess of unlabeled NODAGA-E-[c(RGDfK)]2 along with 18F-NODAGA-E-[c(RGDfK)]2 resulted in significantly reduced radioactivity concentrations in the tumor (0.85 ± 0.13 %ID/g). The αvβ3 integrin-expressing SK-RC-52 tumor could be successfully visualized by microPET with 18F-labeled NODAGA-E-[c(RGDfK)]2. In conclusion, NODAGA-E-[c(RGDfK)]2 could be labeled rapidly with 18F using a direct aqueous, one-pot method and it accumulated specifically in αvβ3 integrin-expressing SK-RC-52 tumors, allowing for visualization by microPET. PMID:23606427

  5. In vivo labelling of hippocampal beta-amyloid in triple-transgenic mice with a fluorescent acetylcholinesterase inhibitor released from nanoparticles.

    Science.gov (United States)

    Härtig, Wolfgang; Kacza, Johannes; Paulke, Bernd-Reiner; Grosche, Jens; Bauer, Ute; Hoffmann, Anke; Elsinghorst, Paul W; Gütschow, Michael

    2010-01-01

    The drastic loss of cholinergic projection neurons in the basal forebrain is a hallmark of Alzheimer's disease (AD), and drugs most frequently applied for the treatment of dementia include inhibitors of the acetylcholine-degrading enzyme acetylcholinesterase (AChE). This protein is known to act as a ligand of beta-amyloid (Abeta) in senile plaques, a further neuropathological sign of AD. Recently, we have shown that the fluorescent, heterodimeric AChE inhibitor PE154 allows for the histochemical staining of cortical Abeta plaques in triple-transgenic (TTG) mice with age-dependent beta-amyloidosis and tau hyperphosphorylation, an established animal model for aspects of AD. In the present study, we have primarily demonstrated the targeting of Abeta-immunopositive plaques with PE154 in vivo for 4 h up to 1 week after injection into the hippocampi of 13-20-month-old TTG mice. Numerous plaques, double-stained for PE154 and Abeta-immunoreactivity, were revealed by confocal laser-scanning microscopy. Additionally, PE154 targeted hippocampal Abeta deposits in aged TTG mice after injection of carboxylated polyglycidylmethacrylate nanoparticles delivering the fluorescent marker in vivo. Furthermore, biodegradable core-shell polystyrene/polybutylcyanoacrylate nanoparticles were found to be suitable, alternative vehicles for PE154 as a useful in vivo label of Abeta. Moreover, we were able to demonstrate that PE154 targeted Abeta, but neither phospho-tau nor reactive astrocytes surrounding the plaques. In conclusion, nanoparticles appear as versatile carriers of AChE inhibitors and other promising drugs for the treatment of AD.

  6. Glucagon Like Peptide-1 Promotes Adipocyte Differentiation via the Wnt4 Mediated Sequestering of Beta-Catenin.

    Science.gov (United States)

    Liu, Rui; Li, Na; Lin, Yi; Wang, Mei; Peng, Yongde; Lewi, Keidren; Wang, Qinghua

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) plays a role in the regulation of adipogenesis; however, the precise underlying molecular mechanism has not been fully defined. Wnt was recently identified as an important regulator of adipogenesis. This study aimed to investigate the involvement of the Wnt signaling pathway in the effects of GLP-1 on adipocyte differentiation. 3T3-L1 cells were induced to differentiate. The changes in the expression levels of adipogenic transcription factors and Wnts and the phosphorylation level and subcellular localization of β-catenin were quantified after GLP-1 treatment. GLP-1 stimulated adipocyte differentiation and lipid accumulation, which were accompanied by the expression of adipocyte marker genes. The expression of Wnt4 was upregulated in the process of adipocyte differentiation, which was further enhanced by treatment with GLP-1. β-catenin, an important mediator of the Wnt pathway, was immediately dephosphorylated and translocated from cytoplasm to nucleus when differentiation was induced. In the presence of GLP-1, however, β-catenin was redirected to the cell plasma membrane leading to its decreased accumulation in the nucleus. Knockdown of Wnt4 blocked the effect of GLP-1 on the cellular localization of β-catenin and expression level of adipogenic transcription factors. Our findings showed that GLP-1 promoted adipogenesis through the modulation of the Wnt4/β-catenin signaling pathway, suggesting that the GLP-1-Wntβ-catenin system might be a new target for the treatment of metabolic disease. PMID:27504979

  7. Accumulation of Exogenous Amyloid-Beta Peptide in Hippocampal Mitochondria Causes Their Dysfunction: A Protective Role for Melatonin

    Science.gov (United States)

    Rosales-Corral, Sergio; Acuna-Castroviejo, Dario; Tan, Dun Xian; López-Armas, Gabriela; Cruz-Ramos, José; Munoz, Rubén; Melnikov, Valery G.; Manchester, Lucien C.; Reiter, Russel J.

    2012-01-01

    Amyloid-beta (Aβ) pathology is related to mitochondrial dysfunction accompanied by energy reduction and an elevated production of reactive oxygen species (ROS). Monomers and oligomers of Aβ have been found inside mitochondria where they accumulate in a time-dependent manner as demonstrated in transgenic mice and in Alzheimer's disease (AD) brain. We hypothesize that the internalization of extracellular Aβ aggregates is the major cause of mitochondrial damage and here we report that following the injection of fibrillar Aβ into the hippocampus, there is severe axonal damage which is accompanied by the entrance of Aβ into the cell. Thereafter, Aβ appears in mitochondria where it is linked to alterations in the ionic gradient across the inner mitochondrial membrane. This effect is accompanied by disruption of subcellular structure, oxidative stress, and a significant reduction in both the respiratory control ratio and in the hydrolytic activity of ATPase. Orally administrated melatonin reduced oxidative stress, improved the mitochondrial respiratory control ratio, and ameliorated the energy imbalance. PMID:22666521

  8. Accumulation of Exogenous Amyloid-Beta Peptide in Hippocampal Mitochondria Causes Their Dysfunction: A Protective Role for Melatonin

    Directory of Open Access Journals (Sweden)

    Sergio Rosales-Corral

    2012-01-01

    Full Text Available Amyloid-beta (Aβ pathology is related to mitochondrial dysfunction accompanied by energy reduction and an elevated production of reactive oxygen species (ROS. Monomers and oligomers of Aβ have been found inside mitochondria where they accumulate in a time-dependent manner as demonstrated in transgenic mice and in Alzheimer’s disease (AD brain. We hypothesize that the internalization of extracellular Aβ aggregates is the major cause of mitochondrial damage and here we report that following the injection of fibrillar Aβ into the hippocampus, there is severe axonal damage which is accompanied by the entrance of Aβ into the cell. Thereafter, Aβ appears in mitochondria where it is linked to alterations in the ionic gradient across the inner mitochondrial membrane. This effect is accompanied by disruption of subcellular structure, oxidative stress, and a significant reduction in both the respiratory control ratio and in the hydrolytic activity of ATPase. Orally administrated melatonin reduced oxidative stress, improved the mitochondrial respiratory control ratio, and ameliorated the energy imbalance.

  9. P144, a Transforming Growth Factor beta inhibitor peptide, generates antitumoral effects and modifies SMAD7 and SKI levels in human glioblastoma cell lines.

    Science.gov (United States)

    Gallo-Oller, Gabriel; Vollmann-Zwerenz, Arabel; Meléndez, Bárbara; Rey, Juan A; Hau, Peter; Dotor, Javier; Castresana, Javier S

    2016-10-10

    Glioblastoma (GBM) is the most prevalent malignant primary brain tumor, accounting for 60-70% of all gliomas. Current median patient survival time is 14-16 months after diagnosis. Numerous efforts in therapy have not significantly altered the nearly uniform lethality of this malignancy. The Transforming Growth Factor beta (TGF-β) signaling pathway plays a key role in GBM and is implicated in proliferation, invasion and therapy resistance. Several inhibitors of the TGF-β pathway have entered clinical trials or are under development. In this work, the therapeutic potential of P144, a TGF-β inhibitor peptide, was analyzed. P144 decreased proliferation, migration, invasiveness, and tumorigenicity in vitro, whereas apoptosis and anoikis were significantly increased for GBM cell lines. SMAD2 phosphorylation was reduced, together with a downregulation of SKI and an upregulation of SMAD7 at both transcriptional and translational levels. Additionally, P144 was able to impair tumor growth and increase survival in an in vivo flank model. Our findings suggest a potential effect of P144 in vitro and in vivo that is mediated by regulation of transcriptional target genes of the TGF-β pathway, suggesting a therapeutic potential of P144 for GBM treatment.

  10. Effects of Low-Dose Pioglitazone on Serum Levels of Adiponectin, Dehydroepiandrosterone, Amyloid Beta Peptide, and Lipid Profile in Elderly Japanese People with Type 2 Diabetes

    Directory of Open Access Journals (Sweden)

    Yuji Aoki

    2015-01-01

    Full Text Available This study was performed to see how pioglitazone at low doses could affect blood biomarkers related to atherosclerosis and aging. The effects of an add-on treatment with pioglitazone (15 mg for males and 7.5 mg for females for 6 months were assessed in 24 outpatients (12 males, 12 females with type 2 diabetes aged ≥ 70 years. As doses of sulfonylurea were reduced in 10 patients, no significant differences in HbA1c and glucose levels were seen. After the treatment, serum levels of HDL cholesterol, arachidonic acid (predominant in males, and high-molecular-weight adiponectin significantly increased. The level of dehydroepiandrosterone sulfate significantly decreased. No significant changes were seen in those of small dense LDL cholesterol, high-sensitivity C-reactive protein, and amyloid beta peptides 1–40 and 1–42. There was a slight but significant increase in body weight, but apparent adverse effects were not observed. In conclusion, pioglitazone at low doses increased serum adiponectin, HDL cholesterol, and arachidonic acid levels but decreased serum dehydroepiandrosterone level, not associated with glycemia, in elderly Japanese people with type 2 diabetes. An optimal dose of pioglitazone should be sought for to minimize its adverse effects and to fully exert its pleiotropic effects such as antiatherosclerotic and antiaging effects.

  11. Effect of vasoactive intestinal peptide and naloxone combination on urinary N-acetyl-beta-D-glucosaminidase level and kidney histology of rats exposed to severe hemorrhage.

    Science.gov (United States)

    Akin, M Z; Tunçel, N; Gürer, F; Kural, N; Uslu, S

    1993-09-01

    Renal hypoperfusion which occurs in hemorrhagic shock creates an environment in which cellular injury and organ dysfunction can occur during the episode of shock as well as reoxygenation and reperfusion. At the same time, mast cell degranulation which is observed during hemorrhage may have an additional deleterious effect on the kidney. Twenty-two (Mus norvegicus albinos) rats (200-250 g) of either sex were used. The animals were divided into three groups. Group 1, the control group, was exposed to a 40% hemorrhage. Group 2 was exposed to 40% hemorrhage and then shed blood reperfused. Group 3 was exposed to 40% hemorrhage, and in addition to shed blood reperfusion 25 ng kg-1 vasoactive intestinal peptide (VIP) + 5 mg kg-1 naloxone (NLX) were given. At the end of the experiment the kidneys were evaluated either histologically or by measurement of the urinary N-acetyl-beta-D-glucosaminidase (NAG) activity. Shed blood reperfusion caused continuation of ischemic tissue damage and elevation of urinary NAG activity. Addition of VIP and NLX to the blood reperfusion caused a decrease in urinary NAG excretion, and the histology of renal tissue was almost normal.

  12. Progressive effect of beta amyloid peptides accumulation on CA1 pyramidal neurons: a model study suggesting possible treatments

    Directory of Open Access Journals (Sweden)

    Viviana eCulmone

    2012-07-01

    Full Text Available Several independent studies show that accumulation of β-amyloid (Aβ peptides , one of the characteristic hallmark of Alzheimer’s Disease (AD, can affect normal neuronal activity in different ways. However, in spite of intense experimental work to explain the possible underlying mechanisms of action, a comprehensive and congruent understanding is still lacking. Part of the problem might be the opposite ways in which Aβ have been experimentally found to affect the normal activity of a neuron; for example, making a neuron more excitable (by reducing the A- or DR-type K+ currents or less excitable (by reducing synaptic transmission and Na+ current. The overall picture is therefore confusing, since the interplay of many mechanisms makes it difficult to link individual experimental findings with the more general problem of understanding the progression of the disease. This is an important issue, especially for the development of new drugs trying to ameliorate the effects of the disease. We addressed these paradoxes through computational models. We first modeled the different stages of AD by progressively modifying the intrinsic membrane and synaptic properties of a realistic model neuron, while accounting for multiple and different experimental findings and by evaluating the contribution of each mechanism to the overall modulation of the cell’s excitability. We then tested a number of manipulations of channel and synaptic activation properties that could compensate for the effects of Aβ. The model predicts possible therapeutic treatments in terms of pharmacological manipulations of channels’ kinetic and activation properties. The results also suggest how and which mechanisms can be targeted by a drug to restore the original firing conditions.

  13. Measurement of the Interaction Between Recombinant I-domain from Integrin alpha 2 beta 1 and a Triple Helical Collagen Peptide with the GFOGER Binding Motif Using Molecular Force Spectroscopy

    Directory of Open Access Journals (Sweden)

    Mark E. Welland

    2013-01-01

    Full Text Available The role of the collagen-platelet interaction is of crucial importance to the haemostatic response during both injury and pathogenesis of the blood vessel wall. Of particular interest is the high affinity interaction of the platelet transmembrane receptor, alpha 2 beta 1, responsible for firm attachment of platelets to collagen at and around injury sites. We employ single molecule force spectroscopy (SMFS using the atomic force microscope (AFM to study the interaction of the I-domain from integrin alpha 2 beta 1 with a synthetic collagen related triple-helical peptide containing the high-affinity integrin-binding GFOGER motif, and a control peptide lacking this sequence, referred to as GPP. By utilising synthetic peptides in this manner we are able to study at the molecular level subtleties that would otherwise be lost when considering cell-to-collagen matrix interactions using ensemble techniques. We demonstrate for the first time the complexity of this interaction as illustrated by the complex multi-peaked force spectra and confirm specificity using control blocking experiments. In addition we observe specific interaction of the GPP peptide sequence with the I-domain. We propose a model to explain these observations.

  14. Levels of alpha- and beta-secretase cleaved amyloid precursor protein in the cerebrospinal fluid of Alzheimer's disease patients

    DEFF Research Database (Denmark)

    Sennvik, K; Fastbom, J; Blomberg, M;

    2000-01-01

    Alternative cleavage of the amyloid precursor protein (APP) results in generation and secretion of both soluble APP (sAPP) and beta-amyloid (Abeta). Abeta is the main component of the amyloid depositions in the brains of Alzheimer's disease (AD) patients. Using Western blotting, we compared the...... levels of alpha-secretase cleaved sAPP, beta-secretase cleaved sAPP and total sAPP, in cerebrospinal fluid (CSF) from 13 sporadic AD patients and 13 healthy controls. Our findings show significant amounts of beta-secretase cleaved sAPP in CSF. There was no statistically significant difference in the...... levels of beta-secretase cleaved sAPP between AD patients and controls. The levels of alpha-secretase cleaved sAPP and total sAPP were, however, found to be significantly lower in the AD patients than in the controls....

  15. Hydrogen sulfide inhibits beta-amyloid peptide-induced apoptosis in PC12 cells and the underlying mechanisms

    Institute of Scientific and Technical Information of China (English)

    Xiuqin Chen; Jingtian Li; Jinhui Zou; Bailing Li; Meng Wang

    2008-01-01

    BACKGROUND: Studies have demonstrated that hydrogen sulfide (H2S) levels are 55% lower in brains of Alzheimer's disease (AD) patients than in age-matched normal individuals, which suggests that H2S might be involved in some aspects of AD pathogenesis.OBJECTIVE: To observe the protective mechanisms of varied concentrations of H2S against β -amyloid-peptide (A β) induced apoptosis in pheochromoytoma (PC12) cells, and to analyze the pathway of action.DESIGN, TIME AND SETTING: A controlled, observational, in vitro experiment was performed at Nenrophysiology Laboratory in Zhougshan Medical School, Sun Yat-sen University between July 2006 and May 2007.MATERIALS: PC12 cells were provided by the Animal Experimental Center of Medical School of Sun Yat-sen University. Glybenclamide, rhodamine123, and dihydrorhodamine123 were purchased from Sigma (USA).METHODS: PCI2 cells were incubated at 37℃ in a 5% CO2-enriched incubator with RPMI-1640 medium, supplemented with 5% horse-serum and 10% fetal bovine serum. Cells in logarithmic growth curves received different treatment: The PC12 cells were maintains at 37℃ with the original medium, then incubated in A β 25-35, sodium hydrosulfide (NariS), glybenclamide, NailS+ A β 25-35, or pretreated with glybenelamide 30 minutes prior to administration of and A β 25-35, respectively. MAIN OUTCOME MEASURES: (1) The survival rate of PC12 cells was detected by MTT assay and Hoechst staining. (2) The apoptosis rate of PC12 cells was detected utilizing flow cytometry with propidium iodide staining, and morphological changes of apoptotic cells were observed. (3) The mitochondrial membrane potential was detected by Rhodamine 123-combined flow cytometry. (4) The intracellular reactive oxygen species content was detected by dihydrorhodamine123-combined flow cytometry. RESULTS: A β 25-35 induced significantly decreased viability and increased percentage of apoptosis in PC 12 cells, as well as dissipated mitochondrial membrane potential

  16. The ability of apolipoprotein E fragments to promote intraneuronal accumulation of amyloid beta peptide 42 is both isoform and size-specific

    Science.gov (United States)

    Dafnis, Ioannis; Argyri, Letta; Sagnou, Marina; Tzinia, Athina; Tsilibary, Effie C.; Stratikos, Efstratios; Chroni, Angeliki

    2016-01-01

    The apolipoprotein (apo) E4 isoform is the strongest risk factor for late-onset Alzheimer’s disease (AD). ApoE4 is more susceptible to proteolysis than apoE2 and apoE3 isoforms and carboxyl-terminal truncated apoE4 forms have been found in AD patients’ brain. We have previously shown that a specific apoE4 fragment, apoE4-165, promotes amyloid-peptide beta 42 (Aβ42) accumulation in human neuroblastoma SK-N-SH cells and increased intracellular reactive oxygen species formation, two events considered to occur early in AD pathogenesis. Here, we show that these effects are allele-dependent and absolutely require the apoE4 background. Furthermore, the exact length of the fragment is critical since longer or shorter length carboxyl-terminal truncated apoE4 forms do not elicit the same effects. Structural and thermodynamic analyses showed that apoE4-165 has a compact structure, in contrast to other carboxyl-terminal truncated apoE4 forms that are instead destabilized. Compared however to other allelic backgrounds, apoE4-165 is structurally distinct and less thermodynamically stable suggesting that the combination of a well-folded structure with structural plasticity is a unique characteristic of this fragment. Overall, our findings suggest that the ability of apoE fragments to promote Aβ42 intraneuronal accumulation is specific for both the apoE4 isoform and the particular structural and thermodynamic properties of the fragment. PMID:27476701

  17. Effect of 1 night of total sleep deprivation on cerebrospinal fluid beta-amyloid 42 in healthy middle-aged men: a randomized clinical trial

    NARCIS (Netherlands)

    Ooms, S.; Overeem, S.; Besse, K.; Olde Rikkert, M.G.M.; Verbeek, M.M.; Claassen, J.A.

    2014-01-01

    IMPORTANCE: Increasing evidence suggests a relationship between poor sleep and the risk of developing Alzheimer disease. A previous study found an effect of sleep on beta-amyloid (Abeta), which is a key protein in Alzheimer disease pathology. OBJECTIVE: To determine the effect of 1 night of total sl

  18. CD4+CD25- T cells that express latency-associated peptide on the surface suppress CD4+CD45RBhigh-induced colitis by a TGF-beta-dependent mechanism.

    Science.gov (United States)

    Oida, Takatoku; Zhang, Xingmin; Goto, Masao; Hachimura, Satoshi; Totsuka, Mamoru; Kaminogawa, Shuichi; Weiner, Howard L

    2003-03-01

    Murine CD4(+)CD25(+) regulatory cells have been reported to express latency-associated peptide (LAP) and TGF-beta on the surface after activation, and exert regulatory function by the membrane-bound TGF-beta in vitro. We have now found that a small population of CD4(+) T cells, both CD25(+) and CD25(-), can be stained with a goat anti-LAP polyclonal Ab without being stimulated. Virtually all these LAP(+) cells are also positive for thrombospondin, which has the ability to convert latent TGF-beta to the active form. In the CD4(+)CD45RB(high)-induced colitis model of SCID mice, regulatory activity was exhibited not only by CD25(+)LAP(+) and CD25(+)LAP(-) cells, but also by CD25(-)LAP(+) cells. CD4(+)CD25(-)LAP(+) T cells were part of the CD45RB(low) cell fraction. CD4(+)CD25(-)LAP(-)CD45RB(low) cells had minimal, if any, regulatory activity in the colitis model. The regulatory function of CD25(-)LAP(+) cells was abrogated in vivo by anti-TGF-beta mAb. These results identify a new TGF-beta-dependent regulatory CD4(+) T cell phenotype that is CD25(-) and LAP(+). PMID:12594277

  19. Amyloid-beta induced CA1 pyramidal cell loss in young adult rats is alleviated by systemic treatment with FGL, a neural cell adhesion molecule-derived mimetic peptide.

    Directory of Open Access Journals (Sweden)

    Nicola J Corbett

    Full Text Available Increased levels of neurotoxic amyloid-beta in the brain are a prominent feature of Alzheimer's disease. FG-Loop (FGL, a neural cell adhesion molecule-derived peptide that corresponds to its second fibronectin type III module, has been shown to provide neuroprotection against a range of cellular insults. In the present study impairments in social recognition memory were seen 24 days after a 5 mg/15 µl amyloid-beta(25-35 injection into the right lateral ventricle of the young adult rat brain. This impairment was prevented if the animal was given a systemic treatment of FGL. Unbiased stereology was used to investigate the ability of FGL to alleviate the deleterious effects on CA1 pyramidal cells of the amyloid-beta(25-35 injection. NeuN, a neuronal marker (for nuclear staining was used to identify pyramidal cells, and immunocytochemistry was also used to identify inactive glycogen synthase kinase 3beta (GSK3β and to determine the effects of amyloid-beta(25-35 and FGL on the activation state of GSK3β, since active GSK3β has been shown to cause a range of AD pathologies. The cognitive deficits were not due to hippocampal atrophy as volume estimations of the entire hippocampus and its regions showed no significant loss, but amyloid-beta caused a 40% loss of pyramidal cells in the dorsal CA1 which was alleviated partially by FGL. However, FGL treatment without amyloid-beta was also found to cause a 40% decrease in CA1 pyramidal cells. The action of FGL may be due to inactivation of GSK3β, as an increased proportion of CA1 pyramidal neurons contained inactive GSK3β after FGL treatment. These data suggest that FGL, although potentially disruptive in non-pathological conditions, can be neuroprotective in disease-like conditions.

  20. Reduced amyloidogenic processing of the amyloid beta-protein precursor by the small-molecule Differentiation Inducing Factor-1.

    Science.gov (United States)

    Myre, Michael A; Washicosky, Kevin; Moir, Robert D; Tesco, Giuseppina; Tanzi, Rudolph E; Wasco, Wilma

    2009-04-01

    The detection of cell cycle proteins in Alzheimer's disease (AD) brains may represent an early event leading to neurodegeneration. To identify cell cycle modifiers with anti-Abeta properties, we assessed the effect of Differentiation-Inducing Factor-1 (DIF-1), a unique, small-molecule from Dictyostelium discoideum, on the proteolysis of the amyloid beta-protein precursor (APP) in a variety of different cell types. We show that DIF-1 slows cell cycle progression through G0/G1 that correlates with a reduction in cyclin D1 protein levels. Western blot analysis of DIF-treated cells and conditioned medium revealed decreases in the levels of secreted APP, mature APP, and C-terminal fragments. Assessment of conditioned media by sandwich ELISA showed reduced levels of Abeta40 and Abeta42, also demonstrating that treatment with DIF-1 effectively decreases the ratio of Abeta42 to Abeta40. In addition, DIF-1 significantly diminished APP phosphorylation at residue T668. Interestingly, site-directed mutagenesis of APP residue Thr668 to alanine or glutamic acid abolished the effect of DIF-1 on APP proteolysis and restored secreted levels of Abeta. Finally, DIF-1 prevented the accumulation of APP C-terminal fragments induced by the proteasome inhibitor lactacystin, and calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal (ALLN). Our findings suggest that DIF-1 affects G0/G1-associated amyloidogenic processing of APP by a gamma-secretase-, proteasome- and calpain-insensitive pathway, and that this effect requires the presence of residue Thr668. PMID:19154786

  1. Caspase cleaved presenilin-1 is part of active gamma-secretase complexes

    DEFF Research Database (Denmark)

    Hansson, Camilla A; Popescu, Bogdan O; Laudon, Hanna;

    2006-01-01

    gamma-Secretase is a key enzyme involved in the processing of the beta-amyloid precursor protein into amyloid beta-peptides (Abeta). Abeta accumulates and forms plaques in Alzheimer's disease (AD) brains. A progressive neurodegeneration and cognitive decline occurs during the course of the diseas...

  2. Altered beta-endorphin, Met- and Leu-enkephalins, and enkephalin-containing peptides in pancreas and pituitary of genetically obese diabetic (db/db) mice during development of diabetic syndrome.

    Science.gov (United States)

    Timmers, K; Voyles, N R; Zalenski, C; Wilkins, S; Recant, L

    1986-10-01

    We have recently shown that in addition to beta-endorphin the opioid peptides Met- and Leu-enkephalin and their apparent precursors are localized in islet endocrine cells of the rat pancreas. To begin evaluating a possible role for these pancreatic opiates in the pathophysiology of genetic diabetes in rodents, immunoreactive beta-endorphin and Met- and Leu-enkephalins were measured in acetic acid extracts of pancreas and pituitary of C57BL/KsJ db/db mice and their lean littermates. Groups of animals were studied during three phases of development of the diabetic syndrome in the mutant mice: at 4 (hyperinsulinemic and prediabetic); 6, 9, and 12 (frankly obese and diabetic); and 30 (hypoinsulinemic) wk of age. Elevations or decreases (P less than .05) were found in db/db mice (vs. lean littermates) as follows: pituitary content of Met-enkephalin was twofold higher at all ages studied; pituitary free Leu-enkephalin was lower at 4 wk and reversed to higher at 6-30 wk; pancreatic beta-endorphin was 30% lower at 4 wk and reversed to threefold higher at 6-12 wk; Met- and Leu-enkephalin-containing larger peptides were elevated at one or more points between 6 and 12 wk in both the pancreas and the pituitary. Thus, the onset of overt obesity between 4 and 6 wk of age was accompanied by a marked rise in both pancreatic beta-endorphin and pituitary Leu-enkephalin; similar elevations in these parameters have been reported previously in C57BL/6J ob/ob mice at approximately 12 wk of age.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2944783

  3. A single-chain fusion molecule consisting of peptide, major histocompatibility gene complex class I heavy chain and beta2-microglobulin can fold partially correctly, but binds peptide inefficiently

    DEFF Research Database (Denmark)

    Sylvester-Hvid, C; Buus, S

    1999-01-01

    The function of major histocompatibility complex class I (MHC-I) molecules is to sample peptides from the intracellular environment and present these peptides to CD8+ cytotoxic T lymphocytes (CTL). We have attempted to develop a general approach to produce large amounts of pure and active...

  4. Plaque deposition dependent decrease in 5-HT2A serotonin receptor in AbetaPPswe/PS1dE9 amyloid overexpressing mice

    DEFF Research Database (Denmark)

    Holm, Peter; Ettrup, Anders; Klein, Anders B;

    2010-01-01

    -HT2A receptor regulation in double transgenic AbetaPPswe/PS1dE9 mice which display excess production of Abeta and age-dependent increase in amyloid plaques. Three different age-groups, 4-month-old, 8- month-old, and 11-month-old were included in the study. [3H]-MDL100907, [3H]-escitalopram, and [11C...

  5. Glucagon-like peptide 1 (7-36) amide stimulates exocytosis in human pancreatic beta-cells by both proximal and distal regulatory steps in stimulus-secretion coupling

    DEFF Research Database (Denmark)

    Gromada, J; Bokvist, K; Ding, W G;

    1998-01-01

    The effect of glucagon-like peptide 1(7-36) amide [GLP-1(7-36) amide] on membrane potential, whole-cell ATP-sensitive potassium channel (K[ATP]) and Ca2+ currents, cytoplasmic Ca2+ concentration, and exocytosis was explored in single human beta-cells. GLP-1(7-36) amide induced membrane depolariza...... incretin. The present data suggest that the strong insulinotropic action of GLP-1(7-36) amide and GIP in humans results from its interaction with several proximal as well as distal important regulatory steps in the stimulus-secretion coupling.......The effect of glucagon-like peptide 1(7-36) amide [GLP-1(7-36) amide] on membrane potential, whole-cell ATP-sensitive potassium channel (K[ATP]) and Ca2+ currents, cytoplasmic Ca2+ concentration, and exocytosis was explored in single human beta-cells. GLP-1(7-36) amide induced membrane...... depolarization that was associated with inhibition of whole-cell K(ATP) current. In addition, GLP-1(7-36) amide (and forskolin) produced greater than fourfold potentiation of Ca2+-dependent exocytosis. The latter effect resulted in part (40%) from acceleration of Ca2+ influx through voltage-dependent (L-type) Ca...

  6. BETASCAN: probable beta-amyloids identified by pairwise probabilistic analysis.

    Directory of Open Access Journals (Sweden)

    Allen W Bryan

    2009-03-01

    Full Text Available Amyloids and prion proteins are clinically and biologically important beta-structures, whose supersecondary structures are difficult to determine by standard experimental or computational means. In addition, significant conformational heterogeneity is known or suspected to exist in many amyloid fibrils. Recent work has indicated the utility of pairwise probabilistic statistics in beta-structure prediction. We develop here a new strategy for beta-structure prediction, emphasizing the determination of beta-strands and pairs of beta-strands as fundamental units of beta-structure. Our program, BETASCAN, calculates likelihood scores for potential beta-strands and strand-pairs based on correlations observed in parallel beta-sheets. The program then determines the strands and pairs with the greatest local likelihood for all of the sequence's potential beta-structures. BETASCAN suggests multiple alternate folding patterns and assigns relative a priori probabilities based solely on amino acid sequence, probability tables, and pre-chosen parameters. The algorithm compares favorably with the results of previous algorithms (BETAPRO, PASTA, SALSA, TANGO, and Zyggregator in beta-structure prediction and amyloid propensity prediction. Accurate prediction is demonstrated for experimentally determined amyloid beta-structures, for a set of known beta-aggregates, and for the parallel beta-strands of beta-helices, amyloid-like globular proteins. BETASCAN is able both to detect beta-strands with higher sensitivity and to detect the edges of beta-strands in a richly beta-like sequence. For two proteins (Abeta and Het-s, there exist multiple sets of experimental data implying contradictory structures; BETASCAN is able to detect each competing structure as a potential structure variant. The ability to correlate multiple alternate beta-structures to experiment opens the possibility of computational investigation of prion strains and structural heterogeneity of amyloid

  7. Measurement of the beta-nu correlation coefficient a(beta nu) in the beta decay of trapped He-6(+) ions

    OpenAIRE

    Fléchard, X.; Velten, P.; Liénard, E.; Méry, A.; D. Rodríguez; Ban, G.; Durand, D.; Mauger, F.; O. Naviliat-Cuncic; Thomas, J C

    2011-01-01

    IOP Sciences Highlights of 2011; We have measured the β-ν angular correlation in the β decay of 6He+ ions using a transparent Paul trap. The 6He+ ions, produced at GANIL, were first cooled and bunched before being injected in the LPCTrap setup. The angular correlation was inferred from the time of flight of recoil nuclei detected in coincidence with the β particles. The detection system gives access to the full β decay kinematics, providing means to check the data reliability and to reject a ...

  8. Mutation-based structural modification and dynamics study of amyloid beta peptide (1–42: An in-silico-based analysis to cognize the mechanism of aggregation

    Directory of Open Access Journals (Sweden)

    Pritam Kumar Panda

    2016-03-01

    Full Text Available Alzheimer's disease is the prevalent cause of premature senility, a progressive mental disorder due to degeneration in brain and deposition of amyloid β peptide (1–42, a misfolded protein in the form of aggregation that prevails for a prolonged time and obstructs every aspect of life. One of the primary hallmarks of the neuropathological disease is the accretion of amyloid β peptide in the brain that leads to Alzheimer's disease, but the mechanism is still a mystery. Several investigations have shown that mutations at specific positions have a significant impact in stability of the peptide as predicted from aggregation profiles. Here in our study, we have analyzed the mutations by substituting residues at position A22G, E22G, E22K, E22Q, D23N, L34V and molecular dynamics have been performed to check the deviation in stability and conformation of the peptide. The results validated that the mutations at specific positions lead to instability and the proline substitution at E22P and L34P stalled the aggregation of the peptide.

  9. Comparison of the amyloid pore forming properties of rat and human Alzheimer's beta-amyloid peptide 1-42: Calcium imaging data.

    Science.gov (United States)

    Di Scala, Coralie; Yahi, Nouara; Flores, Alessandra; Boutemeur, Sonia; Kourdougli, Nazim; Chahinian, Henri; Fantini, Jacques

    2016-03-01

    The data here consists of calcium imaging of human neuroblastoma SH-SY5Y cells treated with the calcium-sensitive dye Fluo-4AM and then incubated with nanomolar concentrations of either human or rat Alzheimer's β-amyloid peptide Aβ1-42. These data are both of a qualitative (fluorescence micrographs) and semi-quantitative nature (estimation of intracellular calcium concentrations of cells probed by Aβ1-42 peptides vs. control untreated cells). Since rat Aβ1-42 differs from its human counterpart at only three amino acid positions, this comparative study is a good assessment of the specificity of the amyloid pore forming assay. The interpretation of this dataset is presented in the accompanying study "Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides" [1]. PMID:26909380

  10. Similar peptides from two beta cell autoantigens, proinsulin and glutamic acid decarboxylase, stimulate T cells of individuals at risk for insulin-dependent diabetes.

    OpenAIRE

    Rudy, G; N. Stone; Harrison, L C; Colman, P. G.; McNair, P; Brusic, V.; French, M. B.; Honeyman, M. C.; Tait, B.; Lew, A M

    1995-01-01

    BACKGROUND: Insulin (1) and glutamic acid decarboxylase (GAD) (2) are both autoantigens in insulin-dependent diabetes mellitus (IDDM), but no molecular mechanism has been proposed for their association. We have identified a 13 amino acid peptide of proinsulin (amino acids 24-36) that bears marked similarity to a peptide of GAD65 (amino acids 506-518) (G. Rudy, unpublished). In order to test the hypothesis that this region of similarity is implicated in the pathogenesis of IDDM, we assayed T c...

  11. Hydrogen sulfide prevents Abeta-induced neuronal apoptosis by attenuating mitochondrial translocation of PTEN.

    Science.gov (United States)

    Cui, Weigang; Zhang, Yinghua; Yang, Chenxi; Sun, Yiyuan; Zhang, Min; Wang, Songtao

    2016-06-14

    Neuronal cell apoptosis is an important pathological change in Alzheimer's disease (AD). Hydrogen sulfide (H(2)S) is known to be a novel gaseous signaling molecule and a cytoprotectant in many diseases including AD. However, the molecular mechanism of the antiapoptosis activity of H(2)S in AD is not yet fully understood. The aim of the present study is to evaluate the inhibitory effects of H(2)S on Abeta (Aβ)-induced apoptosis and the molecular mechanisms underlying primary neuron cells. Our results showed that sodium hydrosulfide (NaHS), a donor of H(2)S, significantly ameliorated Aβ-induced cell apoptosis. NaHS also reversed the Aβ-induced translocation of the phosphatase and tensin homologs deleted on chromosome 10 (PTEN) from the cytosol to the mitochondria. Furthermore, H(2)S increased the level of p-AKT/AKT significantly. Interestingly, the antiapoptosis effects of H(2)S were blocked down by specific PI3K/AKT inhibitor wortmannin. In conclusion, these data indicate that H(2)S inhibits Aβ-induced neuronal apoptosis by attenuating mitochondrial translocation of PTEN and that activation of PI3K/AKT signaling pathway plays a critical role in H(2)S-mediated neuronal protection. Our findings provide a novel route into the molecular mechanisms of neuronal apoptosis in AD.

  12. Modeling the interactions of a peptide-major histocompatibility class I ligand with its receptors. I. Recognition by two alpha beta T cell receptors

    DEFF Research Database (Denmark)

    Rognan, D; Stryhn, A; Fugger, L;

    2000-01-01

    A three-dimensional model of the complex between an Influenza Hemagglutinin peptide, Ha255-262, and its restricting element, the mouse major histocompatibility complex (MHC) class I molecule, Kk, was built by homology modeling and subsequently refined by simulated annealing and restrained molecular...

  13. Valine pyrrolidide preserves intact glucose-dependent insulinotropic peptide and improves abnormal glucose tolerance in minipigs with reduced beta-cell mass

    DEFF Research Database (Denmark)

    Larsen, Marianne Olholm; Rolin, Bidda; Ribel, Ulla;

    2003-01-01

    for type 2 diabetes was evaluated in a new large animal model of insulin-deficient diabetes and reduced beta-cell mass, the nicotinamide (NIA) (67 mg/kg) and streptozotocin (STZ) (125 mg/kg)-treated minipig, using the DPPIV inhibitor, valine pyrrolidide (VP) (50 mg/kg). VP did not significantly affect...

  14. Study of Intermediate Products from the Cross-linking Reactions of Genipin with Beta-Lactoglobulin and Related Peptides by MALDI-TOF/TOF Mass Spectrometry

    Science.gov (United States)

    Genipin, methyl-1R,2R,6S-2-hydroxy-9-(hydroxymethyl)-3-oxabicyclo[4.3.0]nona-4,8-diene-5-carboxylate, is an aglycone derivative from geniposide found in the Gardenia jasminoides fruits, obtained through enzymatic hydrolysis with beta-glucosidase. Genipin has been shown to be capable of cross-linking...

  15. Alzheimer Disease: Crosstalk between the Canonical Wnt/Beta-Catenin Pathway and PPARs Alpha and Gamma

    Science.gov (United States)

    Vallée, Alexandre; Lecarpentier, Yves

    2016-01-01

    The molecular mechanisms underlying the pathophysiology of Alzheimer's disease (AD) are still not fully understood. In AD, Wnt/beta-catenin signaling has been shown to be downregulated while the peroxisome proliferator-activated receptor (PPAR) gamma (mARN and protein) is upregulated. Certain neurodegenerative diseases share the same Wnt/beta-catenin/PPAR gamma profile, such as bipolar disorder and schizophrenia. Conversely, other NDs share an opposite profile, such as amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, multiple sclerosis, and Friedreich's ataxia. AD is characterized by the deposition of extracellular Abeta plaques and the formation of intracellular neurofibrillary tangles in the central nervous system (CNS). Activation of Wnt signaling or inhibition of both glycogen synthase kinase-3beta and Dickkopf 1, two key negative regulators of the canonical Wnt pathway, are able to protect against Abeta neurotoxicity and to ameliorate cognitive performance in AD patients. Although PPAR gamma is upregulated in AD patients, and despite the fact that it has been shown that the PPAR gamma and Wnt/beta catenin pathway systems work in an opposite manner, PPAR gamma agonists diminish learning and memory deficits, decrease Abeta activation of microglia, and prevent hippocampal and cortical neurons from dying. These beneficial effects observed in AD transgenic mice and patients might be partially due to the anti-inflammatory properties of PPAR gamma agonists. Moreover, activation of PPAR alpha upregulates transcription of the alpha-secretase gene and represents a new therapeutic treatment for AD. This review focuses largely on the behavior of two opposing pathways in AD, namely Wnt/beta-catenin signaling and PPAR gamma. It is hoped that this approach may help to develop novel AD therapeutic strategies integrating PPAR alpha signaling.

  16. Involvement of formyl peptide receptors in receptor for advanced glycation end products (RAGE - and amyloid beta 1-42-induced signal transduction in glial cells

    Directory of Open Access Journals (Sweden)

    Slowik Alexander

    2012-11-01

    Full Text Available Abstract Background Recent studies suggest that the chemotactic G-protein-coupled-receptor (GPCR formyl-peptide-receptor-like-1 (FPRL1 and the receptor-for-advanced-glycation-end-products (RAGE play an important role in the inflammatory response involved in neurodegenerative disorders such as Alzheimer’s disease (AD. Therefore, the expression and co-localisation of mouse formyl peptide receptor (mFPR 1 and 2 as well as RAGE in an APP/PS1 transgenic mouse model using immunofluorescence and real-time RT-PCR were analysed. The involvement of rat or human FPR1/FPRL1 (corresponds to mFPR1/2 and RAGE in amyloid-β 1–42 (Aβ1-42-induced signalling were investigated by extracellular signal regulated kinase 1/2 (ERK1/2 phosphorylation. Furthermore, the cAMP level in primary rat glial cells (microglia and astrocytes and transfected HEK 293 cells was measured. Formyl peptide receptors and RAGE were inhibited by a small synthetic antagonist WRW4 and an inactive receptor variant delta-RAGE, lacking the intracytoplasmatic domains. Results We demonstrated a strong increase of mFPR1/2 and RAGE expression in the cortex and hippocampus of APP/PS1 transgenic mice co-localised to the glial cells. In addition, the Aβ1-42-induced signal transduction is dependant on FPRL1, but also on FPR1. For the first time, we have shown a functional interaction between FPRL1/FPR1 and RAGE in RAGE ligands S100B- or AGE-mediated signalling by ERK1/2 phosphorylation and cAMP level measurement. In addition a possible physical interaction between FPRL1 as well as FPR1 and RAGE was shown with co-immunoprecipitation and fluorescence microscopy. Conclusions The results suggest that both formyl peptide receptors play an essential role in Aβ1-42-induced signal transduction in glial cells. The interaction with RAGE could explain the broad ligand spectrum of formyl peptide receptors and their important role for inflammation and the host defence against infections.

  17. Peptoid-Peptide hybrid backbone architectures

    DEFF Research Database (Denmark)

    Olsen, Christian Adam

    2010-01-01

    -amino acids (alpha/beta-peptides) have been investigated in some detail as well. The present Minireview is a survey of the literature concerning hybrid structures of alpha-amino acids and peptoids, including beta-peptoids (N-alkyl-beta-alanine oligomers), and is intended to give an overview of this area......Peptidomimetic oligomers and foldamers have received considerable attention for over a decade, with beta-peptides and the so-called peptoids (N-alkylglycine oligomers) representing prominent examples of such architectures. Lately, hybrid or mixed backbones consisting of both alpha- and beta...

  18. Pharmacokinetics of [{sup 18}F]flutemetamol in wild-type rodents and its binding to beta amyloid deposits in a mouse model of Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Snellman, Anniina; Lopez-Picon, Francisco R.; Haaparanta-Solin, Merja [University of Turku, MediCity/PET Preclinical Laboratory, Turku PET Centre, Turku (Finland); Rokka, Johanna; Eskola, Olli [University of Turku, Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, Turku (Finland); Wilson, Ian; Farrar, Gill [GE Healthcare Medical Diagnostics, Little Chalfont, Buckinghamshire (United Kingdom); Scheinin, Mika [University of Turku, Department of Pharmacology, Drug Development and Therapeutics, Turku (Finland); Turku University Hospital, Unit of Clinical Pharmacology, Turku (Finland); Solin, Olof [University of Turku, Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, Turku (Finland); Aabo Akademi University, Accelerator Laboratory, Turku PET Centre, Turku (Finland); Rinne, Juha O. [University of Turku and Turku University Hospital, Turku PET Centre, Turku (Finland)

    2012-11-15

    The aim of this study was to investigate the potential of [{sup 18}F]flutemetamol as a preclinical PET tracer for imaging {beta}-amyloid (A{beta}) deposition by comparing its pharmacokinetics to those of [{sup 11}C]Pittsburgh compound B ([{sup 11}C]PIB) in wild-type Sprague Dawley rats and C57Bl/6N mice. In addition, binding of [{sup 18}F]flutemetamol to A{beta} deposits was studied in the Tg2576 transgenic mouse model of Alzheimer's disease. [{sup 18}F]Flutemetamol biodistribution was evaluated using ex vivo PET methods and in vivo PET imaging in wild-type rats and mice. Metabolism and binding of [{sup 11}C]PIB and [{sup 18}F]flutemetamol to plasma proteins were analysed using thin-layer chromatography and ultrafiltration methods, respectively. Radiation dose estimates were calculated from rat ex vivo biodistribution data. The binding of [{sup 18}F]flutemetamol to A{beta} deposits was also studied using ex vivo and in vitro autoradiography. The location of A{beta} deposits in the brain was determined with thioflavine S staining and immunohistochemistry. The pharmacokinetics of [{sup 18}F]flutemetamol resembled that of [{sup 11}C]PIB in rats and mice. In vivo studies showed that both tracers readily entered the brain, and were excreted via the hepatobiliary pathway in both rats and mice. The metabolism of [{sup 18}F]flutemetamol into radioactive metabolites was faster than that of [{sup 11}C]PIB. [{sup 18}F]Flutemetamol cleared more slowly from the brain than [{sup 11}C]PIB, particularly from white matter, in line with its higher lipophilicity. Effective dose estimates for [{sup 11}C]PIB and [{sup 18}F]flutemetamol were 2.28 and 6.65 {mu}Sv/MBq, respectively. Autoradiographs showed [{sup 18}F]flutemetamol binding to fibrillar A{beta} deposits in the brain of Tg2576 mice. Based on its pharmacokinetic profile, [{sup 18}F]flutemetamol showed potential as a PET tracer for preclinical imaging. It showed good brain uptake and was bound to A{beta} deposits in the

  19. Concordant association of insulin degrading enzyme gene (IDE variants with IDE mRNA, Abeta, and Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Minerva M Carrasquillo

    Full Text Available BACKGROUND: The insulin-degrading enzyme gene (IDE is a strong functional and positional candidate for late onset Alzheimer's disease (LOAD. METHODOLOGY/PRINCIPAL FINDINGS: We examined conserved regions of IDE and its 10 kb flanks in 269 AD cases and 252 controls thereby identifying 17 putative functional polymorphisms. These variants formed eleven haplotypes that were tagged with ten variants. Four of these showed significant association with IDE transcript levels in samples from 194 LOAD cerebella. The strongest, rs6583817, which has not previously been reported, showed unequivocal association (p = 1.5x10(-8, fold-increase = 2.12,; the eleven haplotypes were also significantly associated with transcript levels (global p = 0.003. Using an in vitro dual luciferase reporter assay, we found that rs6583817 increases reporter gene expression in Be(2-C (p = 0.006 and HepG2 (p = 0.02 cell lines. Furthermore, using data from a recent genome-wide association study of two Croatian isolated populations (n = 1,879, we identified a proxy for rs6583817 that associated significantly with decreased plasma Abeta40 levels (ss = -0.124, p = 0.011 and total measured plasma Abeta levels (b = -0.130, p = 0.009. Finally, rs6583817 was associated with decreased risk of LOAD in 3,891 AD cases and 3,605 controls. (OR = 0.87, p = 0.03, and the eleven IDE haplotypes (global p = 0.02 also showed significant association. CONCLUSIONS: Thus, a previously unreported variant unequivocally associated with increased IDE expression was also associated with reduced plasma Abeta40 and decreased LOAD susceptibility. Genetic association between LOAD and IDE has been difficult to replicate. Our findings suggest that targeted testing of expression SNPs (eSNPs strongly associated with altered transcript levels in autopsy brain samples may be a powerful way to identify genetic associations with LOAD that would otherwise be difficult to detect.

  20. Exploring Beta-Amyloid Protein Transmembrane Insertion Behavior and Residue-Specific Lipid Interactions in Lipid Bilayers Using Multiscale MD Simulations

    Science.gov (United States)

    Qiu, Liming; Vaughn, Mark; Cheng, Kelvin

    2013-03-01

    Beta-amyloid (Abeta) interactions with neurons are linked to Alzheimer's. Using a multiscale MD simulation strategy that combines the high efficiency of phase space sampling of coarse-grained MD (CGD) and the high spatial resolution of Atomistic MD (AMD) simulations, we studied the Abeta insertion dynamics in cholesterol-enriched and -depleted lipid bilayers that mimic the neuronal membranes domains. Forward (AMD-CGD) and reverse (CGD-AMD) mappings were used. At the atomistic level, cholesterol promoted insertion of Abeta with high (folded) or low (unfolded) helical contents of the lipid insertion domain (Lys28-Ala42), and the insertions were stabilized by the Lys28 snorkeling and Ala42-anchoring to the polar lipid groups of the bilayer up to 200ns. After the forward mapping, the folded inserted state switched to a new extended inserted state with the Lys28 descended to the middle of the bilayer while the unfolded inserted state migrated to the membrane surface up to 4000ns. The two new states remained stable for 200ns at the atomistic scale after the reverse mapping. Our results suggested that different Abeta membrane-orientation states separated by free energy barriers can be explored by the multiscale MD more effectively than by Atomistic MD simulations alone. NIH RC1-GM090897-02

  1. Beta-scission of side-chain alkoxyl radicals on peptides and proteins results in the loss of side-chains as aldehydes and ketones

    DEFF Research Database (Denmark)

    Headlam, Henrietta A; Davies, Michael Jonathan

    2002-01-01

    Exposure of proteins to radicals in the presence of O(2) results in side-chain oxidation and backbone fragmentation; the interrelationship between these processes is not fully understood. Recently, initial attack on Ala side-chains was shown to give alpha-carbon radicals (and hence backbone...... for Val, and these sites, plus C-5, for Leu. The detection of glyoxylic acid and CO(2)(-*) from Asp demonstrates the occurrence of competing beta-scission processes for the Asp C-3 alkoxyl radical. The yield of hydroperoxides and released carbonyls account for 10-145% of the initial HO(*). The greater...

  2. The inhibition of autoreactive T cell functions by a peptide based on the CDR1 of an anti-DNA autoantibody is via TGF-beta-mediated suppression of LFA-1 and CD44 expression and function.

    Science.gov (United States)

    Sela, Uri; Mauermann, Nora; Hershkoviz, Rami; Zinger, Heidy; Dayan, Molly; Cahalon, Liora; Liu, Jian Ping; Mozes, Edna; Lider, Ofer

    2005-12-01

    Systemic lupus erythematosus (SLE), which is characterized by the increased production of autoantibodies and defective T cell responses, can be induced in mice by immunization with a human anti-DNA mAb that expresses a major Id, designated 16/6Id. A peptide based on the sequence of the CDR1 of the 16/6Id (human CDR1 (hCDR1)) ameliorated the clinical manifestations of SLE and down-regulated, ex vivo, the 16/6Id-induced T cell proliferation. In this study, we examined the mechanism responsible for the hCDR1-induced modulation of T cell functions related to the pathogenesis of SLE. We found that injection of hCDR1 into BALB/c mice concomitant with their immunization with 16/6Id resulted in a marked elevation of TGF-beta secretion 10 days later. Addition of TGF-beta suppressed the 16/6Id-stimulated T cell proliferation similarly to hCDR1. In addition, we provide evidence that one possible mechanism underlying the hCDR1- and TGFbeta-induced inhibition of T cell proliferation is by down-regulating the expression, and therefore the functions, of a pair of key cell adhesion receptors, LFA-1 (alphaLbeta2) and CD44, which operate as accessory molecules in mediating APC-T cell interactions. Indeed, T cells of mice treated with hCDR1 showed a TGF-beta-induced suppression of adhesion to the LFA-1 and CD44 ligands, hyaluronic acid and ICAM-1, respectively, induced by stromal cell-derived factor-1alpha and PMA. The latter suppression is through the inhibition of ERK phosphorylation. Thus, the down-regulation of SLE-associated responses by hCDR1 treatment may be due to the effect of the up-regulated TGF-beta on the expression and function of T cell adhesion receptors and, consequently, on T cell stimulation, adhesion, and proliferation. PMID:16301630

  3. Protective effects of testosterone on cognitive dysfunction in Alzheimer's disease model rats induced by oligomeric beta amyloid peptide 1-42.

    Science.gov (United States)

    Huo, Dong-Sheng; Sun, Jian-Fang; Zhang, Baifeng; Yan, Xu-Sheng; Wang, He; Jia, Jian-Xin; Yang, Zhan-Jun

    2016-01-01

    Cognitive dysfunction is known to be influenced by circulating sex steroidal hormones. The aim of this study was to examine the protective effect and possible protective mechanism of testosterone (T) on cognitive performance in male rats induced by intrahippocampal injections of beta amyloid 1-42 oligomers (Aβ1-42). Treatment with T as evidenced by the Morris water maze (MWM) test significantly shortened escape latency and reduced path length to reach the platform compared to the control (C). During probe trials, the T group displayed a significantly greater percent of time in the target quadrant and improved the number of platform crossings compared with C, flutamide (F), an antiandrogen, and a combined F and T group. Flutamide markedly inhibited the influence of T on cognitive performance. Following Nissl staining, the number of intact pyramidal cells was significantly elevated in the T group, and the effect of T was blocked by F. Immunohistochemisty and Western blot analysis showed that the protein expression level of Aβ 1-42 was markedly decreased and expression levels of synaptophysin (SYN) significantly increased with T, while F inhibited all T-mediated effects. Our data suggest that the influence of T on cognitive performance was mediated via androgen receptors (AR) to remove beta amyloid, which leads to enhanced synaptic plasticity. PMID:27599231

  4. Conformational preferences of heterochiral peptides. Crystal structures of heterochiral peptides Boc-(D) Val-(D) Ala-Leu-Ala-OMe and Boc-Val-Ala-Leu-(D) Ala-OMe--enhanced stability of beta-sheet through C-H...O hydrogen bonds.

    Science.gov (United States)

    Fabiola, G F; Bobde, V; Damodharan, L; Pattabhi, V; Durani, S

    2001-02-01

    The crystal structures of Boc-(D) Val-(D) Ala-Leu-Ala-OMe (vaLA) and Boc-Val-Ala-Leu-(D) Ala-OMe (VALa) have been determined. vaLA crystallises in space group P2(1),2(1),2(1), with a = 9.401 (4), b = 17.253 (5), c = 36.276 (9)A. V = 5,884 (3) A3, Z = 8, R = 0.086. VALa crystallises in space group P2(1) with a = 9.683 (9), b = 17.355 (7), c = 18.187 (9) A, beta = 95.84 (8) degrees , V = 3,040(4) A3, Z = 4, R = 0.125. There are two molecules in the asymmetric unit in antiparallel beta-sheet arrangement in both the structures. Several of the Calpha hydrogens are in hydrogen bonding contact with the carbonyl oxygen in the adjacent strand. An analysis of the observed conformational feature of D-chiral amino acid residues in oligopeptides, using coordinates of 123 crystal structures selected from the 1998 release of CSD has been carried out. This shows that all the residues except D-isoleucine prefer both extended and alphaL conformation though the frequence of occurence may not be equal. In addition to this, D-leucine, valine, proline and phenylalanine have assumed alphaR conformations in solid state. D-leucine has a strong preference for helical conformation in linear peptides whereas they prefer an extended conformation in cyclic peptides. PMID:11245253

  5. Effect of beta-blockade and ACE inhibition on B-type natriuretic peptides in stable patients with systolic heart failure

    DEFF Research Database (Denmark)

    Rosenberg, J.; Gustafsson, F.; Remme, W.J.;

    2008-01-01

    treatment allocation: Carvedilol, enalapril or carvedilol+enalapril. Changes in BNP and NT-proBNP from baseline to 6 months maintenance visit were evaluated in each treatment arm. Furthermore, the prognostic value of BNP and NT-proBNP during monotherapy with carvedilol was assessed with univariate Cox...... (1.005-1.032), BNP 1.171 (1.088-1.260)). Conclusion Treatment of HF patients with carvedilol alone does not reduce levels of natriuretic peptides, but treatment with enalapril does. Both BNP and NT-proBNP predict death and hospitalisation in HF patients treated with carvedilol for six months....... The clinical implication of our results is that NT-proBNP and BNP can be used as risk markers of death and cardiovascular hospitalisations in systolic HF patients receiving carvedilol without ACE inhibition Udgivelsesdato: 2008/8...

  6. Rescue of amyloid-Beta-induced inhibition of nicotinic acetylcholine receptors by a peptide homologous to the nicotine binding domain of the alpha 7 subtype.

    Directory of Open Access Journals (Sweden)

    Arthur A Nery

    Full Text Available Alzheimer's disease (AD is characterized by brain accumulation of the neurotoxic amyloid-β peptide (Aβ and by loss of cholinergic neurons and nicotinic acetylcholine receptors (nAChRs. Recent evidence indicates that memory loss and cognitive decline in AD correlate better with the amount of soluble Aβ than with the extent of amyloid plaque deposits in affected brains. Inhibition of nAChRs by soluble Aβ40 is suggested to contribute to early cholinergic dysfunction in AD. Using phage display screening, we have previously identified a heptapeptide, termed IQ, homologous to most nAChR subtypes, binding with nanomolar affinity to soluble Aβ40 and blocking Aβ-induced inhibition of carbamylcholine-induced currents in PC12 cells expressing α7 nAChRs. Using alanine scanning mutagenesis and whole-cell current recording, we have now defined the amino acids in IQ essential for reversal of Aβ40 inhibition of carbamylcholine-induced responses in PC12 cells, mediated by α7 subtypes and other endogenously expressed nAChRs. We further investigated the effects of soluble Aβ, IQ and analogues of IQ on α3β4 nAChRs recombinantly expressed in HEK293 cells. Results show that nanomolar concentrations of soluble Aβ40 potently inhibit the function of α3β4 nAChRs, and that subsequent addition of IQ or its analogues does not reverse this effect. However, co-application of IQ makes the inhibition of α3β4 nAChRs by Aβ40 reversible. These findings indicate that Aβ40 inhibits different subtypes of nAChRs by interacting with specific receptor domains homologous to the IQ peptide, suggesting that IQ may be a lead for novel drugs to block the inhibition of cholinergic function in AD.

  7. Engineering Metal Ion Coordination to Regulate Amyloid Fibril Assembly And Toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Dong, J.; Canfield, J.M.; Mehta, A.K.; Shokes, J.E.; Tian, B.; Childers, W.S.; Simmons, J.A.; Mao, Z.; Scott, R.A.; Warncke, K.; Lynn, D.G.

    2009-06-02

    Protein and peptide assembly into amyloid has been implicated in functions that range from beneficial epigenetic controls to pathological etiologies. However, the exact structures of the assemblies that regulate biological activity remain poorly defined. We have previously used Zn{sup 2+} to modulate the assembly kinetics and morphology of congeners of the amyloid {beta} peptide (A{beta}) associated with Alzheimer's disease. We now reveal a correlation among A{beta}-Cu{sup 2+} coordination, peptide self-assembly, and neuronal viability. By using the central segment of A{beta}, HHQKLVFFA or A{beta}(13-21), which contains residues H13 and H14 implicated in A{beta}-metal ion binding, we show that Cu{sup 2+} forms complexes with A{beta}(13-21) and its K16A mutant and that the complexes, which do not self-assemble into fibrils, have structures similar to those found for the human prion protein, PrP. N-terminal acetylation and H14A substitution, Ac-A{beta}(13-21)H14A, alters metal coordination, allowing Cu{sup 2+} to accelerate assembly into neurotoxic fibrils. These results establish that the N-terminal region of A{beta} can access different metal-ion-coordination environments and that different complexes can lead to profound changes in A{beta} self-assembly kinetics, morphology, and toxicity. Related metal-ion coordination may be critical to the etiology of other neurodegenerative diseases.

  8. Beta-scission of alkoxyl radicals on peptides and proteins can give rise to backbone cleavage and loss of side-chains

    International Nuclear Information System (INIS)

    Full text: Exposure of proteins to radicals in the presence of O2 brings about multiple changes including side-chain oxidation, backbone fragmentation, cross-linking, unfolding, changes in hydrophobicity and conformation, altered susceptibility to proteolytic enzymes and formation of new reactive groups (e.g. hydroperoxides and 3,4-dihydroxyphenylalanine). All of these processes can result in loss of structural or enzymatic activity. The mechanisms that give rise to backbone cleavage are only partly understood. Whilst it is known that direct hydrogen atom abstraction at a-carbon sites gives backbone cleavages it has also been proposed that initial attack at side-chain sites might also give rise to backbone cleavage. In this study we have examined whether initial attack at the β- (C-3) position can give rise to α-carbon radicals (and hence backbone cleavage) via the formation, and subsequent β- scission, of C-3 alkoxyl radicals. This process has been observed previously with protected amino acids in organic solvents (J. Chem. Soc. Perkin Trans. 2, 1997, 503-507) but the occurrence of such reactions with proteins in aqueous solution has not been explored. Alkoxyl radicals were generated at the C-3 position of a variety of protected amino acids and small peptides by two methods: metal-ion catalysed decomposition of hydroperoxides formed as a result of γ-radiolysis in the presence of O2, and UV photolysis of nitrate esters. In most cases radicals have been detected by EPR spectroscopy using nitroso and nitrone spin traps, which can be assigned by comparison with literature data to α-carbon radicals; in some case assignments were confirmed by the generation of the putative species by other routes. With Ala peptide hydroperoxides and nitrate esters, and MNP as the spin trap, the major radical detected in each case has been assigned to the adduct of an α-carbon radical with partial structure - NH-.CH-C(O) - consistent with the rapid occurrence of the above reaction

  9. Design of small molecules that target metal-A{beta} species and regulate metal-induced A{beta} aggregation and neurotoxicity.

    Science.gov (United States)

    Choi, Jung-Suk; Braymer, Joseph J; Nanga, Ravi P R; Ramamoorthy, Ayyalusamy; Lim, Mi Hee

    2010-12-21

    The accumulation of metal ions and amyloid-β (Aβ) aggregates found in the brain of patients with Alzheimer's disease (AD) has been suggested to be involved in AD pathogenesis. To investigate metal-Aβ-associated pathways in AD, development of chemical tools to target metal-Aβ species is desired. Only a few efforts, however, have been reported. Here, we report bifunctional small molecules, N-(pyridin-2-ylmethyl)aniline (L2-a) and N(1),N(1)-dimethyl-N(4)-(pyridin-2-ylmethyl)benzene-1,4-diamine (L2-b) that can interact with both metal ions and Aβ species, as determined by spectroscopic methods including high-resolution NMR spectroscopy. Using the bifunctional compound L2-b, metal-induced Aβ aggregation and neurotoxicity were modulated in vitro as well as in human neuroblastoma cells. Furthermore, treatment of human AD brain tissue homogenates containing metal ions and Aβ species with L2-b showed disassembly of Aβ aggregates. Therefore, our studies presented herein demonstrate the value of bifunctional compounds as chemical tools for investigating metal-Aβ-associated events and their mechanisms in the development and pathogenesis of AD and as potential therapeutics.

  10. Some commonly used brominated flame retardants cause Ca2+-ATPase inhibition, beta-amyloid peptide release and apoptosis in SH-SY5Y neuronal cells.

    Directory of Open Access Journals (Sweden)

    Fawaz Al-Mousa

    Full Text Available Brominated flame retardants (BFRs are chemicals commonly used to reduce the flammability of consumer products and are considered pollutants since they have become widely dispersed throughout the environment and have also been shown to bio-accumulate within animals and man. This study investigated the cytotoxicity of some of the most commonly used groups of BFRs on SH-SY5Y human neuroblastoma cells. The results showed that of the BFRs tested, hexabromocyclododecane (HBCD, tetrabromobisphenol-A (TBBPA and decabromodiphenyl ether (DBPE, all are cytotoxic at low micromolar concentrations (LC(50 being 2.7 ± 0.7 µM, 15 ± 4 µM and 28 ± 7 µM, respectively. They induced cell death, at least in part, by apoptosis through activation of caspases. They also increased intracellular [Ca(2+] levels and reactive-oxygen-species within these neuronal cells. Furthermore, these BFRs also caused rapid depolarization of the mitochondria and cytochrome c release in these neuronal cells. Elevated intracellular [Ca(2+] levels appear to occur through a mechanism involving microsomal Ca(2+-ATPase inhibition and this maybe responsible for Ca(2+-induced mitochondrial dysfunction. In addition, µM levels of these BFRs caused β-amyloid peptide (Aβ-42 processing and release from these cells with a few hours of exposure. These results therefore shows that these pollutants are both neurotoxic and amyloidogenic in-vitro.

  11. {beta} - amyloid imaging probes

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

  12. Peripheral beta-endorphin and pain modulation.

    OpenAIRE

    Hartwig, A. C.

    1991-01-01

    Beta-endorphin is a peptide with morphine-like effects produced primarily in the anterior lobe of the pituitary gland. After its cleavage from the parent molecule, proopiomelanocortin, beta-endorphin is circulated via the blood stream to interact with specific opioid receptors located throughout the body. The peptide produces analgesia by inhibiting the firing of peripheral somatosensory fibers. It also affects other senses, such as vision, hearing, and smell. Whereas the ability to increase ...

  13. β-淀粉样蛋白对小胶质细胞合成一氧化氮的影响%Effect of amyloid beta-peptide on activated microglial cell excreting nitric oxide

    Institute of Scientific and Technical Information of China (English)

    韩笑峰; 吕丽; 葛汝丽; 唐荣华

    2008-01-01

    目的 探讨β-淀粉样蛋白(arnyloid beta-peptide,AB)诱导小胶质细胞活化后K轻链核因子(nuclear factor-kappa B,NF-kB)的表达及一氧化氮(NO)水平的变化.方法 Ap干预纯化培养的小胶质细胞,观察其形态学变化,采用镉还原法测定NO水平,免疫细胞化学方法研究NF-KB的表达.结果 500 nmol/L及1000 mnol/L AB干预组细胞形态呈"阿米巴样",细胞核内NF-kB的表达增加(P<0.05),培养基中NO浓度升高(P<0.05).结论 AB激活小胶质细胞NF-kB途径大量合成NO,可能参与阿尔茨海默病(Alzheimer's disease,AD)的致病过程.

  14. Protective effect of cyclophilin A against Alzheimer's amyloid beta-peptide (25-35)-induced oxidative stress in PC12 cells

    Institute of Scientific and Technical Information of China (English)

    GE Yu-song; TENG Wei-yu; ZHANG Chao-dong

    2009-01-01

    Background β-amyloid peptide (Aβ) is considered responsible for the pathogenesis of Alzheimer's disease (AD). Possible mechanisms underlying Aβ-induced neuronal cytotoxicity include excessive production of reactive oxidative species (ROS) and apoptosis. Cyclophilin A (CypA), exhibits antioxidant properties and protects neurons against oxidative stress induced injury. This study was conducted to demonstrate whether CyPA added to cultured PC12 cells could alleviate Aβ-induced oxidative stress and protect them from apoptosis.Methods PC12 cells were pre-incubated for 30 minutes with recombinant human cyclophilin A (rhCyPA) in 0.1 nmol/L, 1.0 nmol/L, 10 nmol/L and 100 nmol/L and then incubated with 10 umol/L Aβ25-35. In every group, cell viability, apoptotic morphology, apoptotic rate, intracellular ROS accumulation, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) of PC12 cells and mitochondrial transmembrane potential were detected. Subsequently, the expression of the active form of caspase-3 was determined by Western blotting.Results It was shown that cultures treated with 1.0 nmol/L, 10 nmol/L or 100 nmol/L rhCyPA + Aβ25-35 had significantly higher cell viability and a lower rate of apoptosis compared with the cultures exposed only to Aβ25-35. In addition, rhCyPA attenuated Aβ25-35-induced overproduction of intracellular ROS and Aβ25-35-induced a decrease in activity of the key antioxidant enzymes SOD and GSH-Px. Furthermore, rhCyPA also attenuated Aβ25-35-induced mitochondrial dysfunction and the activation of caspase-3.Conclusion CyPA may act as an ROS scavenger, and prevent Aβ25-35-induced neurotoxicity through attenuating oxidative stress induced by Aβ25-35.

  15. [Compensatory mechanisms to heal neuroplasticity impairment under Alzheiemer's disease neurodegeneration. I: The role of amyloid beta and its' precursor protein].

    Science.gov (United States)

    Kudinov, A R; Kudinova, N V; Kezlia, E V; Kozyrev, K M; Medvedev, A E; Berezov, T T

    2012-01-01

    In-depth scholar literature analysis of Alzheimer's disease neurodegenerative features of amyloid beta protein neurochemistry modification and excessive phosphorylation of tau protein (and associated neuronal cytoskeleton rearrangements) are secondary phenomena. At early disease stage these neurobiochemical mechanisms are reversible and serve to heal an impairment of biophysical properties of neuronal membranes, neurotransmission, basic neuronal function and neuroplasticity, while preserving anatomical and functional brain fields. Abeta and tau could well serve to biochemically restore physico-chemical properties of neual membranes due to a role these proteins play in lipid metabolism. Under such scenario therapeutic block of aggregation and plaque formation of Abeta and inhibition of tau phosphorylation, as well as pharmaceutical modification of other secondary neurodegenerative features (such as a cascade of oxidative stress reactions) are unable to provide an effective cure of Alzheimer's disease and related pathologies of the Central and peripheral nervous systems, because they are not arraying primary pathagenetic cause. We review the role of Abeta in compensatory mechanisms of neuroplasticity restoration under normal physiological condition and Alzheimer's disease.

  16. Effects of L-3-n-butylphthalide on caspase-3 and nuclear factor kappa-B expression in primary basal forebrain and hippocampal cultures after beta-amyloid peptide 1-42 treatment

    Institute of Scientific and Technical Information of China (English)

    Ruixia Wang; Yong Zhang; Liangliang Jiang; Guozhao Ma; Qingxi Fu; Jialong Li; Peng Yan; Lunqian Shen; Yabo Feng; Chunxia Li; Zaiying Pang; Yuanxiao Cui; Chunfu Chen; Yifeng Du; Zhaokong Liu

    2009-01-01

    BACKGROUND: L-3-n-butylphthalide (L-NBP) can inhibit phosphorylation of tau protein and reduce the neurotoxicity of beta-amyloid peptide 1-42 (Aβ1-42).OBJECTIVE: To observe the neuroprotective effects of L-NBP on caspase-3 and nuclear factor kappa-B (NF-кB) expression in a rat model of Alzheimer's disease.DESIGN, TIME AND SETTING: A cell experiment was performed at the Central Laboratory of Provincial Hospital affiliated to Shandong University between January 2008 and August 2008.MATERIALS: L-NBP (purity>98%) was provided by Shijiazhuang Pharma Group NBP Pharmaceutical Company Limited. Aβ1-42, 3-[4,5-dimethylthiazolo-2]-2,5 iphenyltetrazolium bromide (MTT), and rabbit anti-Caspase-3 polyclonal antibody were provided by Cell Signaling, METHODS: Primary cultures were generated from rat basal forebrain and hippocampal neurons at 17 or 19 days of gestation. The cells were assigned into five groups: the control group, the Aβ1-42 group (2μmol/L), the Aβ1-42+0.1μmol/L L-NBP group, the Aβ1-42+1 μmol/L L-NBP group, and the Aβ1-42 + 10μmol/L L-NBP group. The neurons were treated with Aβ1-42 (2 μmol/L) alone or in combination with L-NBP (0.1, 1, 10μmol/L) for 48 hours. Cells in the control group were incubated in PBS.MAIN OUTCOME MEASURES: Morphologic changes were evaluated using inverted microscopy, Western blot.RESULTS: Induction with Aβ1-42 for 48 hours caused cell death and soma atrophy, and increased the high dose (P<0.05).CONCLUSION: Aβ1-42 is toxic to basal forebrain and hippocampal primary neurons; L-NBP protects against this toxicity and inhibits the induction of caspase-3 and NF-κB expression.

  17. Mechanisms of beta-amyloid neurotoxicity : Perspectives of pharmacotherapy

    NARCIS (Netherlands)

    Harkany, T; Abraham, [No Value; Konya, C; Nyakas, C; Zarandi, M; Penke, B; Luiten, PGM

    2000-01-01

    One of the characteristic neuropathological hallmarks of Alzheimer's disease (AD) is the extracellular accumulation of beta -amyloid peptides (A beta) in neuritic plaques, Experimental data indicate that different molecular forms of A beta affect a wide array of neuronal and glial functions and ther

  18. Evidence for Novel [beta]-Sheet Structures in Iowa Mutant [beta]-Amyloid Fibrils

    Energy Technology Data Exchange (ETDEWEB)

    Tycko, Robert; Sciarretta, Kimberly L.; Orgel, Joseph P.R.O.; Meredith, Stephen C.; (IIT); (NIH); (UC)

    2009-07-24

    Asp23-to-Asn mutation within the coding sequence of {beta}-amyloid, called the Iowa mutation, is associated with early onset, familial Alzheimer's disease and cerebral amyloid angiopathy, in which patients develop neuritic plaques and massive vascular deposition predominantly of the mutant peptide. We examined the mutant peptide, D23N-A{beta}40, by electron microscopy, X-ray diffraction, and solid-state NMR spectroscopy. D23N-A{beta}40 forms fibrils considerably faster than the wild-type peptide (k = 3.77 x 10{sup -3} min{sup -1} and 1.07 x 10{sup -4} min{sup -1} for D23N-A{beta}40 and the wild-type peptide WT-A{beta}40, respectively) and without a lag phase. Electron microscopy shows that D23N-A{beta}40 forms fibrils with multiple morphologies. X-ray fiber diffraction shows a cross-{beta} pattern, with a sharp reflection at 4.7 {angstrom} and a broad reflection at 9.4 {angstrom}, which is notably smaller than the value for WT-A{beta}40 fibrils (10.4 {angstrom}). Solid-state NMR measurements indicate molecular level polymorphism of the fibrils, with only a minority of D23N-A{beta}40 fibrils containing the in-register, parallel {beta}-sheet structure commonly found in WT-A{beta}40 fibrils and most other amyloid fibrils. Antiparallel {beta}-sheet structures in the majority of fibrils are indicated by measurements of intermolecular distances through 13C-13C and 15N-13C dipole-dipole couplings. An intriguing possibility exists that there is a relationship between the aberrant structure of D23N-A{beta}40 fibrils and the unusual vasculotropic clinical picture in these patients.

  19. Therapeutics for Alzheimer's disease based on the metal hypothesis.

    Science.gov (United States)

    Bush, Ashley I; Tanzi, Rudolph E

    2008-07-01

    Alzheimer's disease is the most common form of dementia in the elderly, and it is characterized by elevated brain iron levels and accumulation of copper and zinc in cerebral beta-amyloid deposits (e.g., senile plaques). Both ionic zinc and copper are able to accelerate the aggregation of Abeta, the principle component of beta-amyloid deposits. Copper (and iron) can also promote the neurotoxic redox activity of Abeta and induce oxidative cross-linking of the peptide into stable oligomers. Recent reports have documented the release of Abeta together with ionic zinc and copper in cortical glutamatergic synapses after excitation. This, in turn, leads to the formation of Abeta oligomers, which, in turn, modulates long-term potentiation by controlling synaptic levels of the NMDA receptor. The excessive accumulation of Abeta oligomers in the synaptic cleft would then be predicted to adversely affect synaptic neurotransmission. Based on these findings, we have proposed the "Metal Hypothesis of Alzheimer's Disease," which stipulates that the neuropathogenic effects of Abeta in Alzheimer's disease are promoted by (and possibly even dependent on) Abeta-metal interactions. Increasingly sophisticated pharmaceutical approaches are now being implemented to attenuate abnormal Abeta-metal interactions without causing systemic disturbance of essential metals. Small molecules targeting Abeta-metal interactions (e.g., PBT2) are currently advancing through clinical trials and show increasing promise as disease-modifying agents for Alzheimer's disease based on the "metal hypothesis."

  20. Peripheral beta-endorphin and pain modulation.

    Science.gov (United States)

    Hartwig, A C

    1991-01-01

    Beta-endorphin is a peptide with morphine-like effects produced primarily in the anterior lobe of the pituitary gland. After its cleavage from the parent molecule, proopiomelanocortin, beta-endorphin is circulated via the blood stream to interact with specific opioid receptors located throughout the body. The peptide produces analgesia by inhibiting the firing of peripheral somatosensory fibers. It also affects other senses, such as vision, hearing, and smell. Whereas the ability to increase beta-endorphin secretion during times of surgical stress is positively correlated with amelioration of pain, the administration of exogenous opioids, such as fentanyl, reduces plasma beta-endorphin. Decreased beta-endorphin concentrations may play a role in trigeminal neuralgia, migraine headache, and rheumatoid arthritis. PMID:1814247

  1. Antioxidant activity of X-34 in synaptosomal and neuronal systems.

    Science.gov (United States)

    Kanski, Jaroslaw; Sultana, Rukhsana; Klunk, William; Butterfield, D Allan

    2003-10-24

    Inhibiting aggregation and deposition of amyloid beta-peptide (Abeta) in brain is a therapeutic strategy for Alzheimer's disease (AD). A Congo-red-like molecule, X-34, is reported to bind to Abeta deposits. Oxidative stress associated with Abeta is hypothesized to be critical for the neurotoxic properties of this peptide. The present study was undertaken to test the hypothesis that X-34, with its salicylate groups, would act as an antioxidant. When challenged by hydroxyl or peroxyl free radicals or Abeta(1-42), oxidative stress and neurotoxicity occurred in neural systems as assessed by several indices. However, pretreatment of synaptosomes and primary neuronal cell culture with X-34 greatly ameliorated lipid peroxidation induced by these free radicals and Abeta(1-42). Protein oxidation was not prevented by X-34. These results are discussed in terms of potential therapeutic use of X-34 and related compounds in AD.

  2. Production of peptide antisera specific for mouse and rat proinsulin C-peptide 2

    DEFF Research Database (Denmark)

    Blume, N; Madsen, O D; Kofod, Hans;

    1990-01-01

    not seem to increase the end point titre as tested in direct ELISA. The specificity of the antiserum was determined by competitive ELISA and histochemistry on pancreas sections. Only the synthetic C-peptide 2, but not the homologous synthetic C-peptide 1 from mouse and rat competed efficiently in ELISA...... for antibody binding to the immunizing antigen. Antisera to C-peptide 2, stained islet beta-cells on mouse and rat, but not monkey pancreas sections in immunocytochemical analysis. Preabsorption to the synthetic C-peptide 2, but not the synthetic mouse and rat C-peptide 1 abolished staining. In conclusion we...

  3. Pore-forming scissors? A first structural glimpse of gamma-secretase.

    Science.gov (United States)

    Steiner, Harald; Than, Manuel; Bode, Wolfram; Haass, Christian

    2006-09-01

    Amyloid plaques, which are composed of amyloid-beta peptide (Abeta), signify Alzheimer's disease pathology. Secretases generate Abeta by processing the beta-amyloid precursor protein. gamma-Secretase, a complex comprising four different proteins, liberates Abeta from its precursor by intramembrane proteolysis. The first impression of the shape of gamma-secretase has recently been revealed by electron microscopy. It indicates a spherical transmembrane particle with an interior chamber that, presumably, accommodates its catalytic residues, and two openings that might be exit sites for the cleavage products.

  4. Pore-forming scissors? A first structural glimpse of gamma-secretase.

    Science.gov (United States)

    Steiner, Harald; Than, Manuel; Bode, Wolfram; Haass, Christian

    2006-09-01

    Amyloid plaques, which are composed of amyloid-beta peptide (Abeta), signify Alzheimer's disease pathology. Secretases generate Abeta by processing the beta-amyloid precursor protein. gamma-Secretase, a complex comprising four different proteins, liberates Abeta from its precursor by intramembrane proteolysis. The first impression of the shape of gamma-secretase has recently been revealed by electron microscopy. It indicates a spherical transmembrane particle with an interior chamber that, presumably, accommodates its catalytic residues, and two openings that might be exit sites for the cleavage products. PMID:16890442

  5. Antimicrobial peptides in Echinoderms

    Directory of Open Access Journals (Sweden)

    C Li

    2010-05-01

    Full Text Available Antimicrobial peptides (AMPs are important immune effector molecules for invertebrates, including echinoderms, which lack a vertebrate-type adaptive immune system. Here we summarize the knowledge of such peptides in echinoderms. Strongylocins are a novel family of cysteine-rich AMPs, recently identified in the sea urchins, Strongylocentrotus droebachiensis and S. purpuratus. Although these molecules present diverse amino acid sequences, they share an identical cysteine arrangement pattern, dissimilar to other known AMPs. A family of heterodimeric AMPs, named centrocins, are also present in S. droebachiensis. Lysozymes and fragments of larger proteins, such as beta-thymocins, actin, histone 2A and filamin A have also been shown to display antimicrobial activities in echinoderms. Future studies on AMPs should be aimed in revealing how echinoderms use these AMPs in the immune response against microbial pathogens.

  6. Mechanism of inactivation of alanine racemase by beta, beta, beta-trifluoroalanine

    International Nuclear Information System (INIS)

    The alanine racemases are a group of PLP-dependent bacterial enzymes that catalyze the racemization of alanine, providing D-alanine for cell wall synthesis. Inactivation of the alanine racemases from the Gram-negative organism Salmonella typhimurium and Gram-positive organism Bacillus stearothermophilus with beta, beta, beta-trifluoroalanine has been studied. The inactivation occurs with the same rate constant as that for formation of a broad 460-490-nm chromophore. Loss of two fluoride ions per mole of inactivated enzyme and retention of [1-14C]trifluoroalanine label accompany inhibition, suggesting a monofluoro enzyme adduct. Partial denaturation (1 M guanidine) leads to rapid return of the initial 420-nm chromophore, followed by a slower (t1/2 approximately 30 min-1 h) loss of the fluoride ion and 14CO2 release. At this point, reduction by NaB3H4 and tryptic digestion yield a single radiolabeled peptide. Purification and sequencing of the peptide reveals that lysine-38 is covalently attached to the PLP cofactor. A mechanism for enzyme inactivation by trifluoroalanine is proposed and contrasted with earlier results on monohaloalanines, in which nucleophilic attack of released aminoacrylate on the PLP aldimine leads to enzyme inactivation. For trifluoroalanine inactivation, nucleophilic attack of lysine-38 on the electrophilic beta-difluoro-alpha, beta-unsaturated imine provides an alternative mode of inhibition for these enzymes

  7. A chemical analog of curcumin as an improved inhibitor of amyloid Abeta oligomerization.

    Directory of Open Access Journals (Sweden)

    Robert A Orlando

    Full Text Available Amyloid-like plaques are characteristic lesions defining the neuropathology of Alzheimer's disease (AD. The size and density of these plaques are closely associated with cognitive decline. To combat this disease, the few therapies that are available rely on drugs that increase neurotransmission; however, this approach has had limited success as it has simply slowed an imminent decline and failed to target the root cause of AD. Amyloid-like deposits result from aggregation of the Aβ peptide, and thus, reducing amyloid burden by preventing Aβ aggregation represents an attractive approach to improve the therapeutic arsenal for AD. Recent studies have shown that the natural product curcumin is capable of crossing the blood-brain barrier in the CNS in sufficient quantities so as to reduce amyloid plaque burden. Based upon this bioactivity, we hypothesized that curcumin presents molecular features that make it an excellent lead compound for the development of more effective inhibitors of Aβ aggregation. To explore this hypothesis, we screened a library of curcumin analogs and identified structural features that contribute to the anti-oligomerization activity of curcumin and its analogs. First, at least one enone group in the spacer between aryl rings is necessary for measureable anti-Aβ aggregation activity. Second, an unsaturated carbon spacer between aryl rings is essential for inhibitory activity, as none of the saturated carbon spacers showed any margin of improvement over that of native curcumin. Third, methoxyl and hydroxyl substitutions in the meta- and para-positions on the aryl rings appear necessary for some measure of improved inhibitory activity. The best lead inhibitors have either their meta- and para-substituted methoxyl and hydroxyl groups reversed from that of curcumin or methoxyl or hydroxyl groups placed in both positions. The simple substitution of the para-hydroxy group on curcumin with a methoxy substitution improved

  8. Casein kinase 2 down-regulation and activation by polybasic peptides are mediated by acidic residues in the 55-64 region of the beta-subunit. A study with calmodulin as phosphorylatable substrate

    DEFF Research Database (Denmark)

    Meggio, F; Boldyreff, B; Issinger, O G;

    1994-01-01

    The noncatalytic beta-subunit is responsible for the latency of casein kinase 2 (CK2) activity toward calmodulin. Twenty-one mutants of the beta-subunit bearing either deletions or Ala substitutions for charged residues in the 5-6, 55-70, and 171-178 sequences have been assayed for their ability...... insensitive to 42 nM polylysine, which conversely promotes a more than 10-fold increase of calmodulin phosphorylation with wild-type beta.(ABSTRACT TRUNCATED AT 250 WORDS)...

  9. Dietary deficiency increases presenilin expression, gamma-secretase activity and Abeta levels: potentiation by ApoE genotype and alleviation by S-adenosyl methionine

    OpenAIRE

    Chan, Amy; Tchantchou, Flaubert; Eugene J. Rogers; Shea, Thomas B

    2009-01-01

    Apolipoprotein E4 (ApoE4) is a risk factor for Alzheimer's disease (AD). Whether this risk arises from a deficient function of E4 or the lack of protection provided by E2 ir E3 is unclear. Previous studies demonstrate that deprivation of folate and vitamin E, coupled with dietary iron as a pro-oxidant, for 1 month displayed increased PS-1 expression, gamma-secretase and Abeta generation in mice lacking ApoE (ApoE-/- mice). While ApoE-/- mice are a model for ApoE deficiency, they may not refle...

  10. Dietary deficiency increases presenilin expression, gamma-secretase activity, and Abeta levels: potentiation by ApoE genotype and alleviation by S-adenosyl methionine.

    Science.gov (United States)

    Chan, Amy; Tchantchou, Flaubert; Rogers, Eugene J; Shea, Thomas B

    2009-08-01

    Apolipoprotein E4 (ApoE4) is a risk factor for Alzheimer's disease (AD). Whether this risk arises from a deficient function of E4 or the lack of protection provided by E2 or E3 is unclear. Previous studies demonstrate that deprivation of folate and vitamin E, coupled with dietary iron as a pro-oxidant, for 1 month displayed increased presenilin 1 (PS-1) expression, gamma-secretase, and Abeta generation in mice lacking ApoE (ApoE-/- mice). While ApoE-/- mice are a model for ApoE deficiency, they may not reflect the entire range of consequences of E4 expression. We therefore compared herein the impact of the above deficient diet on mice expressing human E2, E3, or E4. As folate deficiency is accompanied by a decrease in the major methyl donor, S-adenosyl methionine (SAM), additional mice received the deficient diet plus SAM. E2 was more protective than murine ApoE or E3 and E4. Surprisingly, PS-1 and gamma-secretase were over-expressed in E3 to the same extent as in E4 even under a complete diet, and were not alleviated by SAM supplementation. Abeta increased only in E4 mice maintained under the complete diet, and was alleviated by SAM supplementation. These findings suggest dietary compromise can potentiate latent risk factors for AD. PMID:19457069

  11. Delayed onset of changes in soma action potential genesis in nociceptive A-beta DRG neurons in vivo in a rat model of osteoarthritis

    Directory of Open Access Journals (Sweden)

    Henry James L

    2009-09-01

    Full Text Available Abstract Background Clinical data on osteoarthritis (OA suggest widespread changes in sensory function that vary during the progression of OA. In previous studies on a surgically-induced animal model of OA we have observed that changes in structure and gene expression follow a variable trajectory over the initial days and weeks. To investigate mechanisms underlying changes in sensory function in this model, the present electrophysiological study compared properties of primary sensory nociceptive neurons at one and two months after model induction with properties in naïve control animals. Pilot data indicated no difference in C- or Aδ-fiber associated neurons and therefore the focus is on Aβ-fiber nociceptive neurons. Results At one month after unilateral derangement of the knee by cutting the anterior cruciate ligament and removing the medial meniscus, the only changes observed in Aβ-fiber dorsal root ganglion (DRG neurons were in nociceptor-like unresponsive neurons bearing a hump on the repolarization phase; these changes consisted of longer half width, reflecting slowed dynamics of AP genesis, a depolarized Vm and an increased AP amplitude. At two months, changes observed were in Aβ-fiber high threshold mechanoreceptors, which exhibited shorter AP duration at base and half width, shorter rise time and fall time, and faster maximum rising rate/maximum falling rate, reflecting accelerated dynamics of AP genesis. Conclusion These data indicate that Aβ nociceptive neurons undergo significant changes that vary in time and occur later than changes in structure and in nociceptive scores in this surgically induced OA model. Thus, if changes in Aβ-fiber nociceptive neurons in this model reflect a role in OA pain, they may relate to mechanisms underlying pain associated with advanced OA.

  12. Advances in the pathogenesis of Alzheimer’s disease: a re-evaluation of amyloid cascade hypothesis

    Directory of Open Access Journals (Sweden)

    Dong Suzhen

    2012-09-01

    Full Text Available Abstract Alzheimer’s disease (AD is a common neurodegenerative disease characterized clinically by progressive deterioration of memory, and pathologically by histopathological changes including extracellular deposits of amyloid-beta (A-beta peptides forming senile plaques (SP and the intracellular neurofibrillary tangles (NFT of hyperphosphorylated tau in the brain. This review focused on the new developments of amyloid cascade hypothesis with details on the production, metabolism and clearance of A-beta, and the key roles of some important A-beta-related genes in the pathological processes of AD. The most recent research advances in genetics, neuropathology and pathogenesis of the disease were also discussed.

  13. Bioactive peptides released during of digestion of processed milk

    Science.gov (United States)

    Most of the proteins contained in milk consist of alpha-s1-, alpha-s2-, beta- and kappa-casein, and some of the peptides contained in these caseins may impart health benefits. To determine if processing affected release of peptides, samples of raw (R), homogenized (H), homogenized and pasteurized (...

  14. Isolation and characterization of testis-specific cDNAs for luteinizing hormone beta-subunit in the rat.

    Science.gov (United States)

    Zhang, F P; Rannikko, A; Huhtaniemi, I

    1995-05-25

    To study further the unexpected expression of the luteinizing hormone (LH) beta-subunit in the rat testis, we identified in a rat testicular cDNA library three LH beta clones with lengths of 3.2, 2.4 and 0.86 kb (TLH beta 1, TLH beta 2 and TLH beta 3). The clones were identified using a 32P-labeled cDNA probe complimentary to the known rat pituitary LH beta mRNA. Clone TLH beta 2 corresponds in size to the main LH beta mRNA species (2.7 kb) detected by Northern hybridization in the rat testis. Sequence analysis indicated that the different sizes of the three clones are due to alternative RNA splicing and differences at the 5' ends of transcripts. The sequence of one open reading frame deduced from TLH beta 1 is almost identical with the pituitary LH beta peptide, differing only in three amino acids in the putative signal peptide. It might encode a functional testis-specific LH beta peptide. Shorter transcripts from clones TLH beta 2 and TLH beta 3 may correspond to short testicular LH beta peptides. The present findings provide further evidence in the rat for expression of testis-specific mRNA variants of the LH beta gene. Their translation products may form a novel class of testicular para/autocrine factors. PMID:7763258

  15. Neuroprotective approaches in experimental models of beta-amyloid neurotoxicity : Relevance to Alzheimer's disease

    NARCIS (Netherlands)

    Harkany, T; Hortobagyi, T; Sasvari, M; Konya, C; Penke, B; Luiten, PGM; Nyakas, C

    1999-01-01

    1. beta-Amyloid peptides (A beta s) accumulate abundantly in the Alzheimer's disease (AD) brain in areas subserving information acquisition arid processing, and memory formation. A beta fragments are producedin a process of abnormal proteolytic cleavage of their precursor, the amyloid precursor prot

  16. Structural flexibility of Aib-containing peptides: the N-terminal tripeptide of trichotoxin.

    Science.gov (United States)

    Gessmann, R; Brueckner, H; Kokkinidis, M

    1991-01-31

    The sequence Aib-Gly-Aib which corresponds to the N-terminus of the microheterogeneous peptide antibiotic trichotoxin has been studied crystallographically in the context of different protecting groups. Peptides Ac-Aib-Gly-Aib-OH (A) and Z-Aib-Gly-Aib-OH (B) form beta-turns. Both peptides show a remarkable conformational flexibility forming a large variety of beta-turns of different types.

  17. Improved tumor targeting of radiolabeled RGD peptides using rapid dose fractionation.

    NARCIS (Netherlands)

    Janssen, M.; Frielink, C.; Dijkgraaf, I.; Oyen, W.J.G.; Edwards, D.S.; Liu, S.; Rajopadhye, M.; Massuger, L.F.A.G.; Corstens, F.H.M.; Boerman, O.C.

    2004-01-01

    Arginine-glycine-aspartic acid (RGD) peptides preferentially bind to alphavbeta3 integrin, an integrin expressed on newly formed endothelial cells and on various tumor cells. When labeled with beta-emitting radionuclides, these peptides can be used for peptide-receptor radionuclide therapy of malign

  18. Multifunctional hybrid networks based on self assembling peptide sequences

    Science.gov (United States)

    Sathaye, Sameer

    The overall aim of this dissertation is to achieve a comprehensive correlation between the molecular level changes in primary amino acid sequences of amphiphilic beta-hairpin peptides and their consequent solution-assembly properties and bulk network hydrogel behavior. This has been accomplished using two broad approaches. In the first approach, amino acid substitutions were made to peptide sequence MAX1 such that the hydrophobic surfaces of the folded beta-hairpins from the peptides demonstrate shape specificity in hydrophobic interactions with other beta-hairpins during the assembly process, thereby causing changes to the peptide nanostructure and bulk rheological properties of hydrogels formed from the peptides. Steric lock and key complementary hydrophobic interactions were designed to occur between two beta-hairpin molecules of a single molecule, LNK1 during beta-sheet fibrillar assembly of LNK1. Experimental results from circular dichroism, transmission electron microscopy and oscillatory rheology collectively indicate that the molecular design of the LNK1 peptide can be assigned the cause of the drastically different behavior of the networks relative to MAX1. The results indicate elimination or significant reduction of fibrillar branching due to steric complementarity in LNK1 that does not exist in MAX1, thus supporting the original hypothesis. As an extension of the designed steric lock and key complementarity between two beta-hairpin molecules of the same peptide molecule. LNK1, three new pairs of peptide molecules LP1-KP1, LP2-KP2 and LP3-KP3 that resemble complementary 'wedge' and 'trough' shapes when folded into beta-hairpins were designed and studied. All six peptides individually and when blended with their corresponding shape complement formed fibrillar nanostructures with non-uniform thickness values. Loose packing in the assembled structures was observed in all the new peptides as compared to the uniform tight packing in MAX1 by SANS analysis. This

  19. New Alzheimer amyloid beta responsive genes identified in human neuroblastoma cells by hierarchical clustering.

    Directory of Open Access Journals (Sweden)

    Markus Uhrig

    Full Text Available Alzheimer's disease (AD is characterized by neuronal degeneration and cell loss. Abeta(42, in contrast to Abeta(40, is thought to be the pathogenic form triggering the pathological cascade in AD. In order to unravel overall gene regulation we monitored the transcriptomic responses to increased or decreased Abeta(40 and Abeta(42 levels, generated and derived from its precursor C99 (C-terminal fragment of APP comprising 99 amino acids in human neuroblastoma cells. We identified fourteen differentially expressed transcripts by hierarchical clustering and discussed their involvement in AD. These fourteen transcripts were grouped into two main clusters each showing distinct differential expression patterns depending on Abeta(40 and Abeta(42 levels. Among these transcripts we discovered an unexpected inverse and strong differential expression of neurogenin 2 (NEUROG2 and KIAA0125 in all examined cell clones. C99-overexpression had a similar effect on NEUROG2 and KIAA0125 expression as a decreased Abeta(42/Abeta(40 ratio. Importantly however, an increased Abeta(42/Abeta(40 ratio, which is typical of AD, had an inverse expression pattern of NEUROG2 and KIAA0125: An increased Abeta(42/Abeta(40 ratio up-regulated NEUROG2, but down-regulated KIAA0125, whereas the opposite regulation pattern was observed for a decreased Abeta(42/Abeta(40 ratio. We discuss the possibilities that the so far uncharacterized KIAA0125 might be a counter player of NEUROG2 and that KIAA0125 could be involved in neurogenesis, due to the involvement of NEUROG2 in developmental neural processes.

  20. New Alzheimer amyloid beta responsive genes identified in human neuroblastoma cells by hierarchical clustering.

    Science.gov (United States)

    Uhrig, Markus; Ittrich, Carina; Wiedmann, Verena; Knyazev, Yuri; Weninger, Annette; Riemenschneider, Matthias; Hartmann, Tobias

    2009-01-01

    Alzheimer's disease (AD) is characterized by neuronal degeneration and cell loss. Abeta(42), in contrast to Abeta(40), is thought to be the pathogenic form triggering the pathological cascade in AD. In order to unravel overall gene regulation we monitored the transcriptomic responses to increased or decreased Abeta(40) and Abeta(42) levels, generated and derived from its precursor C99 (C-terminal fragment of APP comprising 99 amino acids) in human neuroblastoma cells. We identified fourteen differentially expressed transcripts by hierarchical clustering and discussed their involvement in AD. These fourteen transcripts were grouped into two main clusters each showing distinct differential expression patterns depending on Abeta(40) and Abeta(42) levels. Among these transcripts we discovered an unexpected inverse and strong differential expression of neurogenin 2 (NEUROG2) and KIAA0125 in all examined cell clones. C99-overexpression had a similar effect on NEUROG2 and KIAA0125 expression as a decreased Abeta(42)/Abeta(40) ratio. Importantly however, an increased Abeta(42)/Abeta(40) ratio, which is typical of AD, had an inverse expression pattern of NEUROG2 and KIAA0125: An increased Abeta(42)/Abeta(40) ratio up-regulated NEUROG2, but down-regulated KIAA0125, whereas the opposite regulation pattern was observed for a decreased Abeta(42)/Abeta(40) ratio. We discuss the possibilities that the so far uncharacterized KIAA0125 might be a counter player of NEUROG2 and that KIAA0125 could be involved in neurogenesis, due to the involvement of NEUROG2 in developmental neural processes. PMID:19707560

  1. Measurement of the Interaction Between Recombinant I-domain from Integrin alpha 2 beta 1 and a Triple Helical Collagen Peptide with the GFOGER Binding Motif Using Molecular Force Spectroscopy

    OpenAIRE

    Welland, Mark E.; Farndale, Richard W.; Dominique Bihan; Debdulal Roy; Simon J Attwood; Simpson, Anna M. C.; Hamaia, Samir W.

    2013-01-01

    The role of the collagen-platelet interaction is of crucial importance to the haemostatic response during both injury and pathogenesis of the blood vessel wall. Of particular interest is the high affinity interaction of the platelet transmembrane receptor, alpha 2 beta 1, responsible for firm attachment of platelets to collagen at and around injury sites. We employ single molecule force spectroscopy (SMFS) using the atomic force microscope (AFM) to study the interaction of the I-domain from i...

  2. Antimicrobial peptides.

    Science.gov (United States)

    Zhang, Ling-Juan; Gallo, Richard L

    2016-01-11

    Antimicrobial peptides and proteins (AMPs) are a diverse class of naturally occurring molecules that are produced as a first line of defense by all multicellular organisms. These proteins can have broad activity to directly kill bacteria, yeasts, fungi, viruses and even cancer cells. Insects and plants primarily deploy AMPs as an antibiotic to protect against potential pathogenic microbes, but microbes also produce AMPs to defend their environmental niche. In higher eukaryotic organisms, AMPs can also be referred to as 'host defense peptides', emphasizing their additional immunomodulatory activities. These activities are diverse, specific to the type of AMP, and include a variety of cytokine and growth factor-like effects that are relevant to normal immune homeostasis. In some instances, the inappropriate expression of AMPs can also induce autoimmune diseases, thus further highlighting the importance of understanding these molecules and their complex activities. This Primer will provide an update of our current understanding of AMPs. PMID:26766224

  3. Antimicrobial Peptides

    Directory of Open Access Journals (Sweden)

    Ali Adem Bahar

    2013-11-01

    Full Text Available The rapid increase in drug-resistant infections has presented a serious challenge to antimicrobial therapies. The failure of the most potent antibiotics to kill “superbugs” emphasizes the urgent need to develop other control agents. Here we review the history and new development of antimicrobial peptides (AMPs, a growing class of natural and synthetic peptides with a wide spectrum of targets including viruses, bacteria, fungi, and parasites. We summarize the major types of AMPs, their modes of action, and the common mechanisms of AMP resistance. In addition, we discuss the principles for designing effective AMPs and the potential of using AMPs to control biofilms (multicellular structures of bacteria embedded in extracellular matrixes and persister cells (dormant phenotypic variants of bacterial cells that are highly tolerant to antibiotics.

  4. Peptidomic Identification of Serum Peptides Diagnosing Preeclampsia.

    Directory of Open Access Journals (Sweden)

    Qiaojun Wen

    Full Text Available We sought to identify serological markers capable of diagnosing preeclampsia (PE. We performed serum peptide analysis (liquid chromatography mass spectrometry of 62 unique samples from 31 PE patients and 31 healthy pregnant controls, with two-thirds used as a training set and the other third as a testing set. Differential serum peptide profiling identified 52 significant serum peptides, and a 19-peptide panel collectively discriminating PE in training sets (n = 21 PE, n = 21 control; specificity = 85.7% and sensitivity = 100% and testing sets (n = 10 PE, n = 10 control; specificity = 80% and sensitivity = 100%. The panel peptides were derived from 6 different protein precursors: 13 from fibrinogen alpha (FGA, 1 from alpha-1-antitrypsin (A1AT, 1 from apolipoprotein L1 (APO-L1, 1 from inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4, 2 from kininogen-1 (KNG1, and 1 from thymosin beta-4 (TMSB4. We concluded that serum peptides can accurately discriminate active PE. Measurement of a 19-peptide panel could be performed quickly and in a quantitative mass spectrometric platform available in clinical laboratories. This serum peptide panel quantification could provide clinical utility in predicting PE or differential diagnosis of PE from confounding chronic hypertension.

  5. Thymosin beta 4 and thymosin beta 10 expression in hepatocellular carcinoma

    Directory of Open Access Journals (Sweden)

    W. Theunissen

    2014-03-01

    Full Text Available Thymosin beta 4 (Tβ4 and thymosin beta 10 (Tβ10 are two members of the beta-thymosin family involved in many cellular processes such as cellular motility, angiogenesis, inflammation, cell survival and wound healing. Recently, a role for beta-thymosins has been proposed in the process of carcinogenesis as both peptides were detected in several types of cancer. The aim of the present study was to investigate the expression pattern of Tβ4 and Tβ10 in hepatocellular carcinoma (HCC. To this end, the expression pattern of both peptides was analyzed in liver samples obtained from 23 subjects diagnosed with HCC. Routinely formalin-fixed and paraffin-embedded liver samples were immunostained by indirect immunohistochemistry with polyclonal antibodies to Tβ4 and Tβ10. Immunoreactivity for Tβ4 and Tβ10 was detected in the liver parenchyma of the surrounding tumor area. Both peptides showed an increase in granular reactivity from the periportal to the periterminal hepatocytes. Regarding HCC, Tβ4 reactivity was detected in 7/23 cases (30% and Tβ10 reactivity in 22/23 (97% cases analyzed, adding HCC to human cancers that express these beta-thymosins. Intriguing finding was seen looking at the reactivity of both peptides in tumor cells infiltrating the surrounding liver. Where Tβ10 showed a strong homogeneous expression, was Tβ4 completely absent in cells undergoing stromal invasion. The current study shows expression of both beta-thymosins in HCC with marked differences in their degree of expression and frequency of immunoreactivity. The higher incidence of Tβ10 expression and its higher reactivity in tumor cells involved in stromal invasion indicate a possible major role for Tβ10 in HCC progression.

  6. BETA-S, Multi-Group Beta-Ray Spectra

    International Nuclear Information System (INIS)

    1 - Description of program or function: BETA-S calculates beta-decay source terms and energy spectra in multigroup format for time-dependent radionuclide inventories of actinides, fission products, and activation products. Multigroup spectra may be calculated in any arbitrary energy-group structure. The code also calculates the total beta energy release rate from the sum of the average beta-ray energies as determined from the spectral distributions. BETA-S also provides users with an option to determine principal beta-decaying radionuclides contributing to each energy group. The CCC-545/SCALE 4.3 (or SCALE4.2) code system must be installed on the computer before installing BETA-S, which requires the SCALE subroutine library and nuclide-inventory generation from the ORIGEN-S code. 2 - Methods:Well-established models for beta-energy distributions are used to explicitly represent allowed, and 1., 2. - and 3. -forbidden transition types. Forbidden non-unique transitions are assumed to have a spectral shape of allowed transitions. The multigroup energy spectra are calculated by numerically integrating the energy distribution functions using an adaptive Simpson's Rule algorithm. Nuclide inventories are obtained from a binary interface produced by the ORIGEN-S code. BETA-S calculates the spectra for all isotopes on the binary interface that have associated beta-decay transition data in the ENSDF-95 library, developed for the BETA-S code. This library was generated from ENSDF data and contains 715 materials, representing approximately 8500 individual beta transition branches. 3 - Restrictions on the complexity of the problem: The algorithms do not treat positron decay transitions or internal conversion electrons. The neglect of positron transitions in inconsequential for most applications involving aggregate fission products, since most of the decay modes are via electrons. The neglect of internal conversion electrons may impact on the accuracy of the spectrum in the low

  7. A beta-induced meningoencephalitis is IFN-gammadependent and is associated with T cell-dependent clearance of A beta in a mouse model of Alzheimer's disease

    DEFF Research Database (Denmark)

    Monsonego, Alon; Imitola, Jaime; Petrovic, Sanja;

    2006-01-01

    an myelin basic protein (MBP) promoter. Furthermore, immune infiltrates were targeted primarily to sites of Abeta plaques in the brain and were associated with clearance of Abeta. Immune infiltrates were not targeted to the spinal cord, consistent with what was observed in AD patients vaccinated with Abeta...... epitope and that epitopes differ depending on MHC genetic background. Moreover, we show that a single immunization with the dominant T cell epitope Abeta10-24 induced transient meningoencephalitis only in amyloid precursor protein (APP)-transgenic (Tg) mice expressing limited amounts of IFN-gamma under...

  8. Affinity purification of copper chelating peptides from chickpea protein hydrolysates.

    Science.gov (United States)

    Megías, Cristina; Pedroche, Justo; Yust, Maria M; Girón-Calle, Julio; Alaiz, Manuel; Millan, Francisco; Vioque, Javier

    2007-05-16

    Chickpea protein hydrolysates obtained with alcalase and flavourzyme were used for purification of copper chelating peptides by affinity chromatography using copper immobilized on solid supports. The chelating activity of purified peptides was indirectly measured by the inhibition of beta-carotene oxidation in the presence of copper. Two protein hydrolysates, obtained after 10 and 100 min of hydrolysis, were the most inhibitory of beta-carotene oxidation. Purified copper chelating peptides from these protein hydrolysates contained 19.7 and 35.1% histidine, respectively, in comparison to 2.7 and 2.6% in the protein hydrolysates. Chelating peptides from hydrolysate obtained after 10 min of hydrolysis were the most antioxidative being 8.3 times more antioxidative than the hydrolysate, while chelating peptides purified from protein hydrolysate obtained after 100 min were 3.1 times more antioxidative than its hydrolysate. However, the histidine content was higher in peptides derived from the 100 min hydrolysate (19.7 against 35.1% in 10 min hydrolysate), indicating that this amino acid is not the only factor involved in the antioxidative activity, and other factors such as peptide size or amino acid sequence are also determinant. This manuscript shows that affinity chromatography is a useful procedure for purification of copper chelating peptides. This method can be extended to other metals of interest in nutrition, such as calcium, iron, or zinc. Purified chelating peptides, in addition to their antioxidative properties, may also be useful in food mineral fortification for increasing the bioavailability of these metals.

  9. Down-regulation of stromal cell-derived factor-1alpha-induced T cell chemotaxis by a peptide based on the complementarity-determining region 1 of an anti-DNA autoantibody via up-regulation of TGF-beta secretion.

    Science.gov (United States)

    Sela, Uri; Hershkoviz, Rami; Cahalon, Liora; Lider, Ofer; Mozes, Edna

    2005-01-01

    Systemic lupus erythematosus (SLE) can be induced in mice by immunizing them with a monoclonal human anti-DNA Ab that expresses a major Id, designated 16/6Id. In addition, a peptide based on the sequence of the CDR 1 (hCDR1) of the 16/6Id ameliorated the clinical manifestations of SLE in experimental models. In this study we examined the effects of treating mice with human complementary-determining region 1 (hCDR1) on the subsequent chemotaxis of T cells derived from 16/6Id-primed mice. First we demonstrated elevated levels of stromal cell-derived factor-1alpha (SDF-1alpha) in the sera of SLE-afflicted mice and in the sera and lymphoid tissues of 16/6Id-immunized BALB/c mice shortly after the immunization. We then found that administration of hCDR1 to 16/6Id-immunized mice specifically down-regulated SDF1alpha-induced T cell chemotaxis through fibronectin and collagen type I. This was accompanied by diminished SDF1-alpha-induced T cell adhesion and ERK phosphorylation. Treatment with hCDR1 up-regulated TGF-beta secretion, which, in turn, inhibited the murine T cell adhesion to and chemotaxis through fibronectin as well as their ERK phosphorylation. Thus, the secretion of TGF-beta after treatment of 16/6Id-immunized mice with hCDR1 plays an important role in the down-regulation of SDF-1alpha-mediated T cell activation and the interactions with extracellular matrix moieties observed in the present study. PMID:15611253

  10. GMP-compliant automated synthesis of [{sup 18}F]AV-45 (Florbetapir F 18) for imaging {beta}-amyloid plaques in human brain

    Energy Technology Data Exchange (ETDEWEB)

    Yao, C.-H. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Lin, K.-J. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Weng, C.-C. [Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Hsiao, I.-T. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Ting, Y.-S. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Yen, T.-C. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China); Jan, T.-R. [Department and Graduate Institute of Veterinary Medicine, National Taiwan University, Taipei, Taiwan (China); Skovronsky, Daniel [Avid Radiopharmaceuticals, Inc., Philadelphia, PA 19104 (United States); Kung, M.-P. [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Wey, S.-P., E-mail: spwey@mail.cgu.edu.t [Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan 333, Taiwan (China)

    2010-12-15

    We report herein the Good Manufacturing Practice (GMP)-compliant automated synthesis of {sup 18}F-labeled styrylpyridine, AV-45 (Florbetapir), a novel tracer for positron emission tomography (PET) imaging of {beta}-amyloid (A{beta}) plaques in the brain of Alzheimer's disease patients. [{sup 18}F]AV-45 was prepared in 105 min using a tosylate precursor with Sumitomo modules for radiosynthesis under GMP-compliant conditions. The overall yield was 25.4{+-}7.7% with a final radiochemical purity of 95.3{+-}2.2% (n=19). The specific activity of [{sup 18}F]AV-45 reached as high as 470{+-}135 TBq/mmol (n=19). The present studies show that [{sup 18}F]AV-45 can be manufactured under GMP-compliant conditions and could be widely available for routine clinical use.

  11. Antimicrobial actions of the human epididymis 2 (HE2 protein isoforms, HE2alpha, HE2beta1 and HE2beta2

    Directory of Open Access Journals (Sweden)

    French Frank S

    2004-08-01

    Full Text Available Abstract Background The HE2 gene encodes a group of isoforms with similarities to the antimicrobial beta-defensins. We demonstrated earlier that the antimicrobial activity of HE2 proteins and peptides is salt resistant and structure dependent and involves permeabilization of bacterial membranes. In this study, we further characterize the antimicrobial properties of HE2 peptides in terms of the structural changes induced in E. coli and the inhibition of macromolecular synthesis. Methods E. coli treated with 50 micro g/ml of HE2alpha, HE2beta1 or HE2beta2 peptides for 30 and 60 min were visualized using transmission and scanning electron microscopy to investigate the impact of these peptides on bacterial internal and external structure. The effects of HE2alpha, HE2beta1 and HE2beta2 on E. coli macromolecular synthesis was assayed by incubating the bacteria with 2, 10 and 25 micro g/ml of the individual peptides for 0–60 min and measuring the incorporation of the radioactive precursors [methyl-3H]thymidine, [5-3H]uridine and L-[4,5-3H(N]leucine into DNA, RNA and protein. Statistical analyses using Student's t-test were performed using Sigma Plot software. Values shown are Mean ± S.D. Results E. coli treated with HE2alpha, HE2beta1 and HE2beta2 peptides as visualized by transmission electron microscopy showed extensive damage characterized by membrane blebbing, thickening of the membrane, highly granulated cytoplasm and appearance of vacuoles in contrast to the smooth and continuous membrane structure of the untreated bacteria. Similarly, bacteria observed by scanning electron microscopy after treating with HE2alpha, HE2beta1 or HE2beta2 peptides exhibited membrane blebbing and wrinkling, leakage of cellular contents, especially at the dividing septa, and external accumulation of fibrous materials. In addition, HE2alpha, HE2beta1 and HE2beta2 peptides inhibited E. coli DNA, RNA and protein synthesis. Conclusions The morphological changes observed

  12. Proteomic analysis of transducin beta-subunit structural heterogeneity.

    Science.gov (United States)

    Clack, James W; Juhl, Martha; Rice, Carol A; Li, Junyu; Witzmann, Frank A

    2003-10-01

    Partially purified transducin was resolved using two-dimensional gel electrophoresis (2-DE). Peptide mass fingerprinting of several different spots believed to correspond to the 37 kDa beta-subunit of transducin (T(beta)) was performed. Spots were excised and proteolyzed using modified trypsin. Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was performed on the peptide mixture resulting from each spot. As many as six spots with different pI, ranging from 5.2 to 6.1, were observed when separated using 2-DE. MALDI peptide mass fingerprinting determined with high probability that all of the spots were the same gene product, guanine nucleotide-binding protein G(I)/G(S)/G(T) beta-subunit 1 (GNB1; T(beta1)). This suggested that post-translational modification was responsible for the differences in pI. Phosphorylation experiments showed that at least one T(beta1) spot was phosphorylated in vitro with [gamma-(32)P]ATP by an endogenous kinase. Treatment of T(beta) with alkaline phosphatase caused a large change in the spot pattern of T(beta), suggesting that phosphorylated T(beta) is a substrate for alkaline phosphatase. We conclude that T(beta1) constitutes over 99% of the T(beta) expressed in bovine rod outer segments and displays structural heterogeneity that is due to post-translational modification. We also conclude that some, but not all, of the heterogeneity observed is due to phosphorylation of Tb1. PMID:14595696

  13. Hydrophobic interactions and hydrogen bonds in \\beta-sheet formation

    CERN Document Server

    Narayanan, Chitra

    2013-01-01

    In this study, we investigate interactions of extended conformations of homodimeric peptides made of small (glycine or alanine) and large hydrophobic (valine or leucine) sidechains using all-atom molecular dynamics simulations to decipher driving forces for \\beta-sheet formation. We make use of a periodic boundary condition setup in which individual peptides are infinitely long and stretched. Dimers adopt \\beta-sheet conformations at short interpeptide distances (\\xi ~ 0.5 nm) and at intermediate distances (~ 0.8 nm), valine and leucine homodimers assume cross-\\beta-like conformations with side chains interpenetrating each other. These two states are identified as minima in the Potential of Mean Force (PMF). While the number of interpeptide hydrogen bonds increases with decreasing interpeptide distance, the total hydrogen bond number in the system does not change significantly, suggesting that formation of \\beta-sheet structures from extended conformations is not driven by hydrogen bonds. This is supported by...

  14. Fibrillar beta-amyloid peptide Aβ1–40 activates microglial proliferation via stimulating TNF-α release and H2O2 derived from NADPH oxidase: a cell culture study

    Directory of Open Access Journals (Sweden)

    Sharpe Martyn

    2006-09-01

    Full Text Available Abstract Background Alzheimer's disease is characterized by the accumulation of neuritic plaques, containing activated microglia and β-amyloid peptides (Aβ. Fibrillar Aβ can activate microglia, resulting in production of toxic and inflammatory mediators like hydrogen peroxide, nitric oxide, and cytokines. We have recently found that microglial proliferation is regulated by hydrogen peroxide derived from NADPH oxidase. Thus, in this study, we investigated whether Aβ can stimulate microglial proliferation and cytokine production via activation of NADPH oxidase to produce hydrogen peroxide. Methods Primary mixed glial cultures were prepared from the cerebral cortices of 7-day-old Wistar rats. At confluency, microglial cells were isolated by tapping, replated, and treated either with or without Aβ. Hydrogen peroxide production by cells was measured with Amplex Red and peroxidase. Microglial proliferation was assessed under a microscope 0, 24 and 48 hours after plating. TNF-α and IL-1β levels in the culture medium were assessed by ELISA. Results We found that 1 μM fibrillar (but not soluble Aβ1–40 peptide induced microglial proliferation and caused release of hydrogen peroxide, TNF-α and IL-1β from microglial cells. Proliferation was prevented by the NADPH oxidase inhibitor apocynin (10 μM, by the hydrogen peroxide-degrading enzyme catalase (60 U/ml, and by its mimetics EUK-8 and EUK-134 (20 μM; as well as by an antibody against TNF-α and by a soluble TNF receptor inhibitor. Production of TNF-α and IL-1β, measured after 24 hours of Aβ treatment, was also prevented by apocynin, catalase and EUKs, but the early release (measured after 1 hour of Aβ treatment of TNF-α was insensitive to apocynin or catalase. Conclusion These results indicate that Aβ1–40-induced microglial proliferation is mediated both by microglial release of TNF-α and production of hydrogen peroxide from NADPH oxidase. This suggests that TNF-α and NADPH

  15. Bradykinin antagonists modified with dipeptide mimetic beta-turn inducers.

    Science.gov (United States)

    Alcaro, Maria C; Vinci, Valerio; D'Ursi, Anna M; Scrima, Mario; Chelli, Mario; Giuliani, Sandro; Meini, Stefania; Di Giacomo, Marcello; Colombo, Lino; Papini, Anna Maria

    2006-05-01

    Bradykinin (BK) is involved in a wide variety of pathophysiological processes. Potent BK peptide antagonists can be developed introducing constrained unnatural amino acids, necessary to force the secondary structure of the molecule. In this paper, we report a structure-activity relationship study of two peptide analogues of the potent B2 antagonist HOE 140 by replacing the D-Tic-Oic dipeptide with conformationally constrained dipeptide mimetic beta-turn inducers. PMID:16504505

  16. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    Science.gov (United States)

    Rexeisen, Emilie Lynn

    Many therapeutic strategies incorporate peptides into their designs to mimic the natural protein ligands found in vivo. A few examples are the short peptide sequences RGD and PHSRN that mimic the primary and synergy-binding domains of the extracellular matrix protein, fibronectin, which is recognized by the cell surface receptor, alpha5beta 1 integrin. Even though scaffold modification with biomimetic peptides remains one of the most promising approaches for tissue engineering, the use of these peptides in therapeutic tissue-engineered products and drug delivery systems available on the commercial market is limited because the peptides are not easily able to mimic the natural protein. The design of a peptide that can effectively target the alpha5beta1 integrin would greatly increase biomimetic scaffold therapeutic potential. A novel peptide containing both the RGD primary binding domain and PHSRN synergy-binding domain for fibronectin joined with the appropriate linker should bind alpha 5beta1 integrin more efficiently and lead to greater cell adhesion over RGD alone. Several fibronectin mimetic peptides were designed and coupled to dialkyl hydrocarbon tails to make peptide-amphiphiles. The peptides contained different linkers connecting the two binding domains and different spacers separating the hydrophobic tails from the hydrophilic headgroups. The peptide-amphiphiles were deposited on mica substrates using the Langmuir-Blodgett technique. Langmuir isotherms indicated that the peptide-amphiphiles that contained higher numbers of serine residues formed a more tightly packed monolayer, but the increased number of serines also made transferring the amphiphiles to the mica substrate more difficult. Atomic force microscopy (AFM) images of the bilayers showed that the headgroups might be bent, forming small divots in the surface. These divots may help expose the PHSRN synergy-binding domain. Parallel studies undertaken by fellow group members showed that human

  17. PET imaging of alphavbeta integrin expression in tumours with Ga-labelled mono-, di- and tetrameric RGD peptides

    NARCIS (Netherlands)

    Dijkgraaf, I.; Yim, C.B.; Franssen, G.M.; Schuit, R.C.; Luurtsema, G.; Liu, S.; Oyen, W.J.G.; Boerman, O.C.

    2011-01-01

    PURPOSE: Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3)-binding characteristics of (68)Ga-labelled monomeric, dimeric and tetrameric RGD peptides were determined and compared wi

  18. Proinsulin C-peptide interferes with insulin fibril formation

    Energy Technology Data Exchange (ETDEWEB)

    Landreh, Michael [Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm (Sweden); Stukenborg, Jan-Bernd [Department of Women' s and Children' s Health, Astrid Lindgren Children' s Hospital, Pediatric Endocrinology Unit, Karolinska Institutet and University Hospital, S-17176 Stockholm (Sweden); Willander, Hanna [KI-Alzheimer' s Disease Research Center, NVS Department, Karolinska Institutet, S-141 86 Stockholm (Sweden); Soeder, Olle [Department of Women' s and Children' s Health, Astrid Lindgren Children' s Hospital, Pediatric Endocrinology Unit, Karolinska Institutet and University Hospital, S-17176 Stockholm (Sweden); Johansson, Jan [KI-Alzheimer' s Disease Research Center, NVS Department, Karolinska Institutet, S-141 86 Stockholm (Sweden); Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, S-751 23 Uppsala (Sweden); Joernvall, Hans, E-mail: Hans.Jornvall@ki.se [Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm (Sweden)

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer Insulin and C-peptide can interact under insulin fibril forming conditions. Black-Right-Pointing-Pointer C-peptide is incorporated into insulin aggregates and alters aggregation lag time. Black-Right-Pointing-Pointer C-peptide changes insulin fibril morphology and affects backbone accessibility. Black-Right-Pointing-Pointer C-peptide may be a regulator of fibril formation by {beta}-cell granule proteins. -- Abstract: Insulin aggregation can prevent rapid insulin uptake and cause localized amyloidosis in the treatment of type-1 diabetes. In this study, we investigated the effect of C-peptide, the 31-residue peptide cleaved from proinsulin, on insulin fibrillation at optimal conditions for fibrillation. This is at low pH and high concentration, when the fibrils formed are regular and extended. We report that C-peptide then modulates the insulin aggregation lag time and profoundly changes the fibril appearance, to rounded clumps of short fibrils, which, however, still are Thioflavine T-positive. Electrospray ionization mass spectrometry also indicates that C-peptide interacts with aggregating insulin and is incorporated into the aggregates. Hydrogen/deuterium exchange mass spectrometry further reveals reduced backbone accessibility in insulin aggregates formed in the presence of C-peptide. Combined, these effects are similar to those of C-peptide on islet amyloid polypeptide fibrillation and suggest that C-peptide has a general ability to interact with amyloidogenic proteins from pancreatic {beta}-cell granules. Considering the concentrations, these peptide interactions should be relevant also during physiological secretion, and even so at special sites post-secretory or under insulin treatment conditions in vivo.

  19. Human peptide transporters

    DEFF Research Database (Denmark)

    Nielsen, Carsten Uhd; Brodin, Birger; Jørgensen, Flemming Steen;

    2002-01-01

    Peptide transporters are epithelial solute carriers. Their functional role has been characterised in the small intestine and proximal tubules, where they are involved in absorption of dietary peptides and peptide reabsorption, respectively. Currently, two peptide transporters, PepT1 and PepT2...

  20. The interaction of bioactive peptides with an immobilized phosphatidylcholine monolayer.

    OpenAIRE

    Mozsolits, H; Lee, T. H.; Wirth, H J; Perlmutter, P; Aguilar, M I

    1999-01-01

    The interaction of three bioactive peptides, bombesin, beta-endorphin, and glucagon with a phosphatidylcholine monolayer that was immobilized to porous silica particles and packed into a stainless steel column cartridge, has been studied using dynamic elution techniques. This immobilized lipid monolayer provides a biophysical model system with which to study the binding of peptides to a lipid membrane. In particular, the influence of temperature and methanol concentration on the affinity of e...

  1. Effects of opioid peptides on thermoregulation

    Energy Technology Data Exchange (ETDEWEB)

    Clark, W.G.

    1981-11-01

    In a given species, injected opioid peptides usually cause changes in temperature similar to those caused by nonpeptide opioids. The main effect in those species most studied, the cat, rat, and mouse, is an increase in the level about which body temperature is regulated; there is a coordinated change in the activity of thermoregulatory effectors such that hyperthermia is produced in both hot and cold environments. Larger doses may depress thermoregulation, thereby causing body temperature to decrease in the cold. Elicitation of different patterns of response over a range of environmental temperatures and studies with naloxone and naltrexone indicate that stimulation of a number of different receptors by both peptide and nonpeptide opioids can evoke thermoregulatory responses. ..beta..-Endorphin is readily antagonized by naloxone whereas methionine-enkephalin can act on naloxone-insensitive receptors. Moreover, synthetic peptide analogs do not necessarily evoke the same response as does the related endogenous peptide. The lack of effect of naloxone on body temperature of subjects housed at usual laboratory temperature or on pyrogen-induced increases in body temperature indicates that an action of endogenous peptides on naloxone-sensitive receptors plays little, if any, role in normal thermoregulation or in fever. However, there is some evidence that such an action may be involved in responses to restraint or ambient temperature-induced stress. Further evaluation of possible physiological roles of endogenous opioid peptides will be facilitated when specific antagonists at other types of opioid receptors become available.

  2. Alzheimer's disease and Down's syndrome: treating two paths to dementia

    NARCIS (Netherlands)

    Weksler, M.E.; Szabo, P.; Relkin, N.R.; Reidenberg, M.M.; Weksler, B.B.; Coppus, A.M.W.

    2013-01-01

    Successful therapy of dementia, like any disease, depends upon understanding its pathogenesis. This review contrasts the dominant pathways to dementia which differ in Alzheimer's disease (AD) and in Down's syndrome (DS). Impaired clearance of neurotoxic amyloid beta peptides (Abeta) leads to dementi

  3. Immunocytochemical localization of latent transforming growth factor-beta1 activation by stimulated macrophages

    Science.gov (United States)

    Chong, H.; Vodovotz, Y.; Cox, G. W.; Barcellos-Hoff, M. H.; Chatterjee, A. (Principal Investigator)

    1999-01-01

    Transforming growth factor-beta1 (TGF-beta) is secreted in a latent form consisting of mature TGF-beta noncovalently associated with its amino-terminal propeptide, which is called latency associated peptide (LAP). Biological activity depends upon the release of TGF-beta from the latent complex following extracellular activation, which appears to be the key regulatory mechanism controlling TGF-beta action. We have identified two events associated with latent TGF-beta (LTGF-beta) activation in vivo: increased immunoreactivity of certain antibodies that specifically detect TGF-beta concomitant with decreased immunoreactivity of antibodies to LAP. Macrophages stimulated in vitro with interferon-gamma and lipopolysaccharide reportedly activate LTGF-beta via cell membrane-bound protease activity. We show through dual immunostaining of paraformaldehyde-fixed macrophages that such physiological TGF-beta activation is accompanied by a loss of LAP immunoreactivity with concomitant revelation of TGF-beta epitopes. The induction of TGF-beta immunoreactivity colocalized with immunoreactive betaglycan/RIII in activated macrophages, suggesting that LTGF-beta activation occurs on the cell surface. Confocal microscopy of metabolically active macrophages incubated with antibodies to TGF-beta and betaglycan/RIII prior to fixation supported the localization of activation to the cell surface. The ability to specifically detect and localize LTGF-beta activation provides an important tool for studies of its regulation.

  4. Evaluation of beta defensin 2 production by chicken heterophils using direct MALDI mass spectrometry

    Science.gov (United States)

    Beta defensins (BD) are cysteine rich, cationic antimicrobial peptides (AMP) produced mainly by epithelial and myeloid cells such as neutrophils. In birds, the equivalent of neutrophils, heterophils produce avian beta defensins (AvBD) of which AvBD2 is the major isoform. Heterophils recognize patho...

  5. Profiling the Changes in Signaling Pathways in Ascorbic Acid/beta-Glycerophosphate-Induced Osteoblastic Differentiation

    NARCIS (Netherlands)

    Chaves Neto, Antonio Hernandes; Queiroz, Karla Cristiana; Milani, Renato; Paredes-Gamero, Edgar Julian; Justo, Giselle Zenker; Peppelenbosch, Maikel P.; Ferreira, Carmen Verissima

    2011-01-01

    Despite numerous reports on the ability of ascorbic acid and beta-glycerophosphate (AA/beta-GP) to induce osteoblast differentiation, little is known about the molecular mechanisms involved in this phenomenon. In this work, we used a peptide array containing specific consensus sequences (potential s

  6. Chromopeptides from C-phycocyanin. Structure and linkage of a phycocyanobilin bound to the. beta. subunit

    Energy Technology Data Exchange (ETDEWEB)

    Lagarias, J.C.; Glazer, A.N.; Rapoport, H.

    1979-08-15

    The smallest cyanogen bromide fragment derived from the ..beta.. subunit of Synechococcus sp. 6301 C-phycocyanin, the blue heptapeptide 2, has been investigated by 360-MHz /sup 1/H NMR spectroscopy. The peptide portion, heptapeptide 3, was synthesized independently and used in comparative spectroscopic analysis. These studies have led to complete assignment of the structure of the peptide-linked phycocyanobilin and elucidation of the nature of the thioether chromophore-peptide linkage.

  7. Novel antifungal peptides from Ceylon spinach seeds.

    Science.gov (United States)

    Wang, H; Ng, T B

    2001-11-01

    Two novel antifungal peptides, designated alpha- and beta-basrubrins, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure involved saline extraction, (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose and FPLC-gel filtration on Superdex peptide column. alpha- and beta-basrubrins exhibited a molecular weight of 4.3 and 5 kDa, respectively. They inhibited translation in a rabbit reticulocyte system with an IC(50) value of 400 and 100 nM, respectively. alpha- and beta-basrubrin inhibited HIV-1 reverse transcriptase by (79.4 +/- 7.8)% and (54.6 +/- 3.6)%, respectively, at a concentration of 400 microM, and (10.56 +/- 0.92)% and (2.12 +/- 0.81)%, respectively, at a concentration of 40 microM. Both alpha- and beta-basrubrins exerted potent antifungal activity toward Botrytis cinerea, Mycosphaerella arachidicola, and Fusarium oxysporum. PMID:11688973

  8. Levered and unlevered Beta

    OpenAIRE

    Fernandez, Pablo

    2003-01-01

    We prove that in a world without leverage cost the relationship between the levered beta ( L) and the unlevered beta ( u) is the No-costs-of-leverage formula: L = u + ( u - d) D (1 - T) / E. We also analyze 6 alternative valuation theories proposed in the literature to estimate the relationship between the levered beta and the unlevered beta (Harris and Pringle (1985), Modigliani and Miller (1963), Damodaran (1994), Myers (1974), Miles and Ezzell (1980), and practitioners) and prove that all ...

  9. Practical synthesis of enantiomerically pure beta2-amino acids via proline-catalyzed diastereoselective aminomethylation of aldehydes.

    Science.gov (United States)

    Chi, Yonggui; English, Emily P; Pomerantz, William C; Horne, W Seth; Joyce, Leo A; Alexander, Lane R; Fleming, William S; Hopkins, Elizabeth A; Gellman, Samuel H

    2007-05-01

    Proline-catalyzed diastereoselective aminomethylation of aldehydes using a chiral iminium ion, generated from a readily prepared precursor, provides alpha-substituted-beta-amino aldehydes with 85:15 to 90:10 dr. The alpha-substituted-beta-amino aldehydes can be reduced to beta-substituted-gamma-amino alcohols, the major diastereomer of which can be isolated via crystallization or column chromatography. The amino alcohols are efficiently transformed to protected beta2-amino acids, which are valuable building blocks for beta-peptides, natural products, and other interesting molecules. Because conditions for the aminomethylation and subsequent reactions are mild, beta2-amino acid derivatives with protected functional groups in the side chain, such as beta2-homoglutamic acid, beta2-homotyrosine, and beta2-homolysine, can be prepared in this way. The synthetic route is short, and purifications are simple; therefore, this method enables the preparation of protected beta2-amino acids in useful quantities.

  10. Realized Beta GARCH

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger; Voev, Valeri Radkov

    2014-01-01

    as the beta. We apply the model to a large set of assets and find the conditional betas to be far more variable than usually found with rolling-window regressions based exclusively on daily returns. In the empirical part of the paper, we examine the cross-sectional as well as the time variation...... of the conditional beta series during the financial crises....

  11. Antimicrobial peptides in human sepsis

    Directory of Open Access Journals (Sweden)

    Lukas eMartin

    2015-08-01

    Full Text Available Nearly 100 years ago, antimicrobial peptides (AMPs were identified as an important part of innate immunity. They exist in species from bacteria to mammals and can be isolated in body fluids and on surfaces constitutively or induced by inflammation. Defensins have anti-bacterial effects against Gram-positive and Gram-negative bacteria as well as anti-viral and anti-yeast effects. Human neutrophil peptides (HNP 1-3 and human beta-defensins (HBDs 1-3 are some of the most important defensins in humans. Recent studies have demonstrated higher levels of HNP -1-3 and HBD-2 in sepsis. The bactericidal/permeability increasing protein (BPI attenuates local inflammatory response and decreases systemic toxicity of endotoxins. Moreover, BPI might reflect the severity of organ dysfunction in sepsis. Elevated plasma lactoferrin is detected in patients with organ failure. HNP-1-3, lactoferrin, BPI and heparin-binding protein (HBP are increased in sepsis. Human lactoferrin peptide 1-11 (hLF 1-11 possesses antimicrobial activity and modulates inflammation. The recombinant form of lactoferrin (talactoferrin alpha, TLF has been shown to decrease mortality in critically ill patients. A phase II/III study with TLF in sepsis did not confirm this result. The growing number of multiresistant bacteria is an ongoing problem in sepsis therapy. Furthermore, antibiotics are known to promote the liberation of pro-inflammatory cell components and thus augment the severity of sepsis. Compared to antibiotics, AMPs kill bacteria but also neutralize pathogenic factors such as lipopolysaccharide (LPS. The obstacle to applying naturally occurring AMPs is their high nephro- and neurotoxicity. Therefore, the challenge is to develop peptides to treat septic patients effectively without causing harm. This overview focuses on natural and synthetic AMPs in human and experimental sepsis and their potential to provide significant improvements in the treatment of critically ill with severe

  12. Cloning and sequencing of the gene encoding thermophilic beta-amylase of Clostridium thermosulfurogenes.

    OpenAIRE

    Kitamoto, N; Yamagata, H; Kato, T; Tsukagoshi, N; Udaka, S

    1988-01-01

    A gene coding for thermophilic beta-amylase of Clostridium thermosulfurogenes was cloned into Bacillus subtilis, and its nucleotide sequence was determined. The nucleotide sequence suggested that the thermophilic beta-amylase is translated from monocistronic mRNA as a secretory precursor with a signal peptide of 32 amino acid residues. The deduced amino acid sequence of the mature beta-amylase contained 519 residues with a molecular weight of 57,167. The amino acid sequence of the C. thermosu...

  13. PET imaging of brain with the {beta}-amyloid probe, [{sup 11}C]6-OH-BTA-1, in a transgenic mouse model of Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, Hiroshi [Fujita Health University, Department of Radiology, Aichi (Japan); National Institutes of Health, Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland (United States); Ye, Daniel; Cohen, Robert M. [National Institutes of Health, Geriatric Psychiatry Branch, National Institute of Mental Health, Bethesda, Maryland (United States); Ichise, Masanori; Liow, Jeih-San; Cai, Lisheng; Musachio, John L.; Hong, Jinsoo; Crescenzo, Mathew; Tipre, Dnyanesh; Lu, Jian-Qiang; Zoghbi, Sami; Vines, Douglass C.; Pike, Victor W.; Innis, Robert B. [National Institutes of Health, Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland (United States); Jacobowitz, David [USUHS, Department of Anatomy, Physiology, and Genetics, Bethesda, Maryland (United States); Seidel, Jurgen; Green, Michael V. [National Institutes of Health, Department of Nuclear Medicine, Warren Grant Magnuson Clinical Center, Bethesda, Maryland (United States); Katada, Kazuhiro [Fujita Health University, Department of Radiology, Aichi (Japan)

    2005-04-01

    The purpose of this study was to evaluate the capacity of [{sup 11}C]6-OH-BTA-1 and positron emission tomography (PET) to quantify {beta}-amyloid (A{beta}) plaques in the Tg2576 mouse model of Alzheimer's disease (AD). PET imaging was performed with the NIH ATLAS small animal scanner in six elderly transgenic mice (Tg2576; age 22.0{+-}1.8 months; 23.6{+-}2.6 g) overexpressing a mutated form of human {beta}-amyloid precursor protein (APP) known to result in the production of A{beta} plaques, and in six elderly wild-type litter mates (age 21.8{+-}1.6 months; 29.5{+-}4.7 g). Dynamic PET scans were performed for 30 min in each mouse under 1% isoflurane inhalation anesthesia after a bolus injection of 13-46 MBq of [{sup 11}C]6-OH-BTA-1. PET data were reconstructed with 3D OSEM. On the coronal PET image, irregular regions of interest (ROIs) were placed on frontal cortex (FR), parietal cortex (PA), striatum (ST), thalamus (TH), pons (PO), and cerebellum (CE), guided by a mouse stereotaxic atlas. Time-activity curves (TACs) (expressed as percent injected dose per gram normalized to body weight: % ID-kg/g) were obtained for FR, PA, ST, TH, PO, and CE. ROI-to-CE radioactivity ratios were also calculated. Following PET scans, sections of mouse brain prepared from anesthetized and fixative-perfused mice were stained with thioflavin-S. TACs for [{sup 11}C]6-OH-BTA-1 in all ROIs peaked early (at 30-55 s), with radioactivity washing out quickly thereafter in both transgenic and wild-type mice. Peak uptake in all regions was significantly lower in transgenic mice than in wild-type mice. During the later part of the washout phase (12-30 min), the mean FR/CE and PA/CE ratios were higher in transgenic than in wild-type mice (1.06{+-}0.04 vs 0.98{+-}0.07, p=0.04; 1.06{+-}0.09 vs 0.93{+-}0.08 p=0.02) while ST/CE, TH/CE, and PO/CE ratios were not. Ex vivo staining revealed widespread A{beta} plaques in cortex, but not in cerebellum of transgenic mice or in any brain regions of wild

  14. Latency and activation in the control of TGF-beta

    Science.gov (United States)

    Barcellos-Hoff, M. H.; Chatterjee, A. (Principal Investigator)

    1996-01-01

    The biological activity of the transforming growth factor-beta's (TGF-beta)3 is tightly controlled by their persistence in the extracellular compartment as latent complexes. Each of the three mammalian isoform genes encodes a product that is cleaved intracellularly to form two polypeptides, each of which dimerizes. Mature TGF-beta, a 24 kD homodimer, is noncovalently associated with the 80 kD latency-associated peptide (LAP). LAP is a fundamental component of TGF-beta that is required for its efficient secretion, prevents it from binding to ubiquitous cell surface receptors, and maintains its availability in a large extracellular reservoir that is readily accessed by activation. This latent TGF-beta complex (LTGF-beta) is secreted by all cells and is abundant both in circulating forms and bound to the extracellular matrix. Activation describes the collective events leading to the release of TGF-beta. Despite the importance of TGF-beta regulation of growth and differentiation in physiological and malignant tissue processes, remarkably little is known about the mechanisms of activation in situ. Recent studies of irradiated mammary gland reveal certain features of TGF-beta 1 activation that may shed light on its regulation and potential roles in the normal and neoplastic mammary gland.

  15. A novel affinity purification method to isolate peptide specific antibodies

    DEFF Research Database (Denmark)

    Karlsen, Alan E; Lernmark, A; Kofod, Hans;

    1990-01-01

    with the beads and after a wash step the bound antibodies were eluted in 1 M acetic acid. The eluted material was composed predominantly of intact immunoglobulin as evidenced by the presence of heavy and light chain bands in SDS-PAGE. The eluted antibodies were peptide specific in ELISA and bound only to intact......Site-specific, high affinity polyclonal antisera are effectively and successfully produced by immunizing rabbits with synthetic peptides. The use of these antisera in subsequent immune analysis is often limited because of non-specific binding. We describe a new and simple method to effectively...... affinity-purify anti-peptide antibodies. To test our system, rabbits were immunized with model peptides representing sequences of the putative rabbit growth hormone receptor and several HLA-DQ beta-chain molecules. Polystyrene plastic beads were coated with peptides. Immune serum was incubated...

  16. Peptides and aging: Their role in anorexia and memory.

    Science.gov (United States)

    Morley, John E

    2015-10-01

    The rapid aging of the world's population has led to a need to increase our understanding of the pathophysiology of the factors leading to frailty and cognitive decline. Peptides have been shown to be involved in the pathophysiology of frailty and cognitive decline. Weight loss is a major component of frailty. In this review, we demonstrate a central role for both peripheral peptides (e.g., cholecystokinin and ghrelin) and neuropeptides (e.g., dynorphin and alpha-MSH) in the pathophysiology of the anorexia of aging. Similarly, peripheral peptides (e.g., ghrelin, glucagon-like peptide 1, and cholecystokinin) are modulators of memory. A number of centrally acting neuropeptides have also been shown to modulate cognitive processes. Amyloid-beta peptide in physiological levels is a memory enhancer, while in high (pathological) levels, it plays a key role in the development of Alzheimer's disease.

  17. Immunohistochemical detection of active transforming growth factor-beta in situ using engineered tissue

    Science.gov (United States)

    Barcellos-Hoff, M. H.; Ehrhart, E. J.; Kalia, M.; Jirtle, R.; Flanders, K.; Tsang, M. L.; Chatterjee, A. (Principal Investigator)

    1995-01-01

    The biological activity of transforming growth factor-beta 1 (TGF-beta) is governed by dissociation from its latent complex. Immunohistochemical discrimination of active and latent TGF-beta could provide insight into TGF-beta activation in physiological and pathological processes. However, evaluation of immunoreactivity specificity in situ has been hindered by the lack of tissue in which TGF-beta status is known. To provide in situ analysis of antibodies to differentiate between these functional forms, we used xenografts of human tumor cells modified by transfection to overexpress latent TGF-beta or constitutively active TGF-beta. This comparison revealed that, whereas most antibodies did not differentiate between TGF-beta activation status, the immunoreactivity of some antibodies was activation dependent. Two widely used peptide antibodies to the amino-terminus of TGF-beta, LC(1-30) and CC(1-30) showed marked preferential immunoreactivity with active TGF-beta versus latent TGF-beta in cryosections. However, in formalin-fixed, paraffin-embedded tissue, discrimination of active TGF-beta by CC(1-30) was lost and immunoreactivity was distinctly extracellular, as previously reported for this antibody. Similar processing-dependent extracellular localization was found with a neutralizing antibody raised to recombinant TGF-beta. Antigen retrieval recovered cell-associated immunoreactivity of both antibodies. Two antibodies to peptides 78-109 showed mild to moderate preferential immunoreactivity with active TGF-beta only in paraffin sections. LC(1-30) was the only antibody tested that discriminated active from latent TGF-beta in both frozen and paraffin-embedded tissue. Thus, in situ discrimination of active versus latent TGF-beta depends on both the antibody and tissue preparation. We propose that tissues engineered to express a specific form of a given protein provide a physiological setting in which to evaluate antibody reactivity with specific functional forms of a

  18. The Promiscuity of [beta]-Strand Pairing Allows for Rational Design of [beta]-Sheet Face Inversion

    Energy Technology Data Exchange (ETDEWEB)

    Makabe, Koki; Koide, Shohei (UC)

    2009-06-17

    Recent studies suggest the dominant role of main-chain H-bond formation in specifying {beta}-sheet topology. Its essentially sequence-independent nature implies a large degree of freedom in designing {beta}-sheet-based nanomaterials. Here we show rational design of {beta}-sheet face inversions by incremental deletions of {beta}-strands from the single-layer {beta}-sheet of Borrelia outer surface protein A. We show that a {beta}-sheet structure can be maintained when a large number of native contacts are removed and that one can design large-scale conformational transitions of a {beta}-sheet such as face inversion by exploiting the promiscuity of strand-strand interactions. High-resolution X-ray crystal structures confirmed the success of the design and supported the importance of main-chain H-bonds in determining {beta}-sheet topology. This work suggests a simple but effective strategy for designing and controlling nanomaterials based on {beta}-rich peptide self-assemblies.

  19. PeptideAtlas

    Data.gov (United States)

    U.S. Department of Health & Human Services — PeptideAtlas is a multi-organism, publicly accessible compendium of peptides identified in a large set of tandem mass spectrometry proteomics experiments. Mass...

  20. Role of the beta subunit of casein kinase-2 on the stability and specificity of the recombinant reconstituted holoenzyme

    DEFF Research Database (Denmark)

    Meggio, F; Boldyreff, B; Marin, O;

    1992-01-01

    Recombinant human alpha subunit from casein kinase-2 (CK-2) was subjected, either alone or in combination with recombinant human beta subunit, to high temperature, tryptic digestion and urea treatment. In all three cases, it was shown that the presence of the beta subunit could drastically reduce...... alpha subunit. Therefore, a dual function for the beta subunit is proposed which confers both specificity and stability to the catalytic alpha subunit within the CK-2 holoenzyme complex. The peptide DLEPDEELEDNPNQSDL, reproducing the highly acidic amino acid 55-71 segment of the human beta subunit......, counteracts the stimulatory effect of the beta subunit on the alpha subunit activity and partially substitutes the beta subunit in conferring thermal stability to the alpha subunit. No such effect is induced by the peptide MSSSEEVSW, reproducing the N-terminal segment of the beta subunit including...

  1. In vitro proliferation of adult human beta-cells.

    Directory of Open Access Journals (Sweden)

    Sabine Rutti

    Full Text Available A decrease in functional beta-cell mass is a key feature of type 2 diabetes. Glucagon-like peptide 1 (GLP-1 analogues induce proliferation of rodent beta-cells. However, the proliferative capacity of human beta-cells and its modulation by GLP-1 analogues remain to be fully investigated. We therefore sought to quantify adult human beta-cell proliferation in vitro and whether this is affected by the GLP-1 analogue liraglutide.Human islets from 7 adult cadaveric organ donors were dispersed into single cells. Beta-cells were purified by FACS. Non-sorted cells and the beta-cell enriched ("beta-cells" population were plated on extracellular matrix from rat (804G and human bladder carcinoma cells (HTB9 or bovine corneal endothelial ECM (BCEC. Cells were maintained in culture+/-liraglutide for 4 days in the presence of BrdU.Rare human beta-cell proliferation could be observed either in the purified beta-cell population (0.051±0.020%; 22 beta-cells proliferating out of 84'283 beta-cells counted or in the non-sorted cell population (0.055±0.011%; 104 proliferating beta-cells out of 232'826 beta-cells counted, independently of the matrix or the culture conditions. Liraglutide increased human beta-cell proliferation on BCEC in the non-sorted cell population (0.082±0.034% proliferating beta-cells vs. 0.017±0.008% in control, p<0.05.These results indicate that adult human beta-cell proliferation can occur in vitro but remains an extremely rare event with these donors and particular culture conditions. Liraglutide increases beta-cell proliferation only in the non-sorted cell population and only on BCEC. However, it cannot be excluded that human beta-cells may proliferate to a greater extent in situ in response to natural stimuli.

  2. Peptide-binding motif prediction by using phage display library for SasaUBA*0301, a resistance haplotype of MHC class I molecule from Atlantic Salmon (Salmo salar)

    DEFF Research Database (Denmark)

    Zhao, Heng; Hermsen, Trudi; Stet, Rene J M;

    2008-01-01

    -terminus. Meanwhile, phage display peptide library encoding random 12mer peptides was also screened against beta(2)m/SasaUBA*0301. Eighty-five percentages of the corresponding peptides have an enrichment of leucine, methionine, valine, or isoleucine at the C-terminus. We predict that this particular allele of Salmon...

  3. Glucagon-like peptide-1, glucose homeostasis and diabetes

    DEFF Research Database (Denmark)

    Holst, Jens Juul; Deacon, Carolyn F; Vilsbøll, Tina;

    2008-01-01

    pancreatic beta cells, and inhibits glucagon secretion, gastric emptying and food intake, leading to weight loss. GLP-1 mimetics, which are stable-peptide-based activators of the GLP-1 receptor, and incretin enhancers, which inhibit the incretin-degrading enzyme dipeptidyl peptidase-4, have emerged...

  4. Anesthesia and stimulation of pituitary beta-endorphin release in rats.

    Science.gov (United States)

    Maiewski, S; Muldoon, S; Mueller, G P

    1984-07-01

    The effects of several anesthetic drugs and artificial respiration on the release of pituitary beta-endorphin-like immunoreactivity (beta-END-LI) were examined in rats. Plasma beta-END-LI responses to halothane and pentobarbital were similar in magnitude and duration, being maximal (2- to 3-fold) by 10 min and returning to control values by 30 min after induction. Urethane anesthesia was associated with an 8-fold increase in plasma beta-END-LI throughout the 30-min treatment period. In comparison to anesthesia alone, anesthesia plus intubation with artificial respiration (standard parameters) was associated with considerably greater elevations in plasma beta-END-LI (up to 30-fold). Further, intubation and artificial respiration appear to have contributed separately, and in an additive fashion, to the overall beta-END-LI responses observed. As compared to halothane anesthesia alone, intubation evoked a 4-fold increase in circulating beta-END-LI, whereas intubation plus ventilation was associated with a 12-fold increase. Treatment with morphine (1 or 5 mg/kg), but not pancuronium (0.3 mg/kg), attenuated the plasma beta-END-LI response to mechanical ventilation, suggesting that a subconscious phenomenon, perhaps related to pain, was partially responsible for the profound release of pituitary beta-END-LI associated with artificial respiration. Chromatographic analysis of the molecular forms of beta-END-LI released into plasma revealed that both beta-END- and beta-lipotropin (beta-LPH)-sized peptides were secreted under the present experimental conditions. Since the analgesic form of beta-END (beta- END1 -31) is cosecreted with beta-LPH from the pars distalis, increases in the fraction of plasma beta-END-LI corresponding to beta-END in size were probably due to the release of opiate active beta- END1 -31. PMID:6328533

  5. PH dependent adhesive peptides

    Science.gov (United States)

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  6. Antimicrobial Peptides in 2014

    Directory of Open Access Journals (Sweden)

    Guangshun Wang

    2015-03-01

    Full Text Available This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms.

  7. Peptide Nucleic Acid Synthons

    DEFF Research Database (Denmark)

    2004-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  8. Peptide Nucleic Acids

    DEFF Research Database (Denmark)

    2003-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  9. Peptide Nucleic Acids

    DEFF Research Database (Denmark)

    1998-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  10. Peptide Nucleic Acids (PNA)

    DEFF Research Database (Denmark)

    2002-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  11. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    2015-01-01

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

  12. Antagonist of the amylin receptor blocks beta-amyloid toxicity in rat cholinergic basal forebrain neurons.

    Science.gov (United States)

    Jhamandas, Jack H; MacTavish, David

    2004-06-16

    Salvage of cholinergic neurons in the brain through a blockade of the neurotoxic effects of amyloidbeta protein (Abeta) is one of the major, but still elusive, therapeutic goals of current research in Alzheimer's disease (AD). To date, no receptor has been unequivocally identified for Abeta. Human amylin, which acts via a receptor composed of the calcitonin receptor-like receptor and a receptor-associated membrane protein, possesses amyloidogenic properties and has a profile of neurotoxicity that is strikingly similar to Abeta. In this study, using primary cultures of rat cholinergic basal forebrain neurons, we show that acetyl-[Asn30, Tyr32] sCT(8-37) (AC187), an amylin receptor antagonist, blocks Abeta-induced neurotoxicity. Treatment of cultures with AC187 before exposure to Abeta results in significantly improved neuronal survival as judged by MTT and live-dead cell assays. Quantitative measures of Abeta-evoked apoptotic cell death, using Hoechst and phosphotidylserine staining, confirm neuroprotective effects of AC187. We also demonstrate that AC187 attenuates the activation of initiator and effector caspases that mediate Abeta-induced apoptotic cell death. These data are the first to show that expression of Abeta toxicity may occur through the amylin receptor and suggest a novel therapeutic target for the treatment of AD. PMID:15201330

  13. 依据B型钠尿肽水平调整急性冠脉综合征患者β受体阻滞剂使用的临床研究%Clinical research of beta receptor blocker in acute coronary syndrome patients based on the level of B-type natriuretic peptide

    Institute of Scientific and Technical Information of China (English)

    郭明; 杨杰; 张亚梅; 郑霞飞; 张宗辉; 蒋国军

    2015-01-01

    目的:探讨不同B型钠尿肽(BNP)水平下急性冠脉综合征(ACS)患者使用β受体阻滞剂的安全性。方法依据入院后即时BNP水平将231例ACS患者分3组:对照组(<100μg/L)64例、灰带组(100~400μg/L)78例、升高组(>400μg/L)89例。三组患者给予ACS常规治疗及初始剂量的β受体阻滞剂6.25 mg,每日2次。观察记录三组患者BNP浓度变化,血压、心率、心律、killip心功能分级,以及是否并发胸腔积液、下肢水肿和急性左侧心力衰竭。依据各组患者观察治疗期间出现的病情变化不同将其分为A、B和C事件,并根据不同事件确定是否继续使用β受体阻滞剂及其用量。结果三组间A事件和C事件发生率差异均有统计学意义(χ2=28.528、32.608,P均<0.001),其中对照组A事件发生率最低,升高组A事件发生率最高;C事件在对照组中发生率最高,在升高组中发生率最低(P均<0.017)。三组胸腔积液发生率差异有统计学意义,对照组最低,升高组最高(F=35.408,P<0.001)。而下肢水肿的发生数三组相比差异没有统计学意义(χ2=2.973,P=0.226)。对照组β受体阻滞剂使用量最大,升高组最低,三组间差异有统计学意义(F=8.670,P<0.001)。结论 ACS患者BNP水平越高,发生严重不良事件以及心功能下降和胸腔积液的风险也越高,依据BNP水平调整β受体阻滞剂使用剂量可以降低ACS患者并发症和严重不良事件的发生率。%Objective To investigate the safety of beta receptor blocker in acute coronary syndrome (ACS) patients based on the level of B-type natriuretic peptide (BNP). Methods A total of 231 ACS patients were classified into three groups according to their BNP level::control group (BNP400μg/L, n=89). All patients were treated with routine therapy plus beta receptor blocker (6.25 mg each time, twice a day). The BNP level, blood pressure

  14. Betting Against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model’s five central predictions: (1) Since constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for U.......S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return...... of the BAB factor is low; (4) Increased funding liquidity risk compresses betas toward one; (5) More constrained investors hold riskier assets....

  15. Betting against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    2014-01-01

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model's five central predictions: (1) Because constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically...... for US equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures. (2) A betting against beta (BAB) factor, which is long leveraged low-beta assets and short high-beta assets, produces significant positive risk-adjusted returns. (3) When funding constraints tighten......, the return of the BAB factor is low. (4) Increased funding liquidity risk compresses betas toward one. (5) More constrained investors hold riskier assets....

  16. Roughing up Beta

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor

    Motivated by the implications from a stylized equilibrium pricing framework, we investigate empirically how individual equity prices respond to continuous, or \\smooth," and jumpy, or \\rough," market price moves, and how these different market price risks, or betas, are priced in the cross......-section of expected returns. Based on a novel highfrequency dataset of almost one-thousand individual stocks over two decades, we find that the two rough betas associated with intraday discontinuous and overnight returns entail significant risk premiums, while the intraday continuous beta is not priced in the cross......-section. An investment strategy that goes long stocks with high jump betas and short stocks with low jump betas produces significant average excess returns. These higher risk premiums for the discontinuous and overnight market betas remain significant after controlling for a long list of other firm characteristics...

  17. Peptide and non-peptide opioid-induced hyperthermia in rabbits

    Science.gov (United States)

    Kandasamy, S. B.; Williams, B. A.

    1983-01-01

    The intracerebroventricular administration of prototype nonpeptide opioid receptor (mu, kappa, and sigma) agonists, morphine, ketocyclazocine, and N-allyl-normetazocine was found to induce hyperthermia in rabbits. The similar administration of peptide opioids like beta-endorphin (BE), methionine-enkephalin (ME), and its synthetic analogue D-ala2-methionine-enkephalinamide (DAME) was also found to cause hyperthermia. Results indicate that only the liver-like transport system is important to the ventricular inactivation of BE and DAME. Prostaglandins and norepinephrine were determined not to be involved in peptide and nonpeptide opioid-induced hyperthermia. In addition, cAMP was not required since a phosphodiesterase inhibitor, theophylline, did not accentuate the hyperthermia due to peptide and nonpeptide opioids. Naloxone-sensitive receptors were found to be involved in the induction of hyperthermia by morphine, BE, ME, and DAME since naloxone attenuated them. However, the hyperthermic response to ketocyclazocine and N-allyl-normetazocine was not antagonized by naloxone.

  18. Trefoil peptides promote restitution of wounded corneal epithelial cells.

    Science.gov (United States)

    Göke, M N; Cook, J R; Kunert, K S; Fini, M E; Gipson, I K; Podolsky, D K

    2001-04-01

    The ocular surface shares many characteristics with mucosal surfaces. In both, healing is regulated by peptide growth factors, cytokines, and extracellular matrix proteins. However, these factors are not sufficient to ensure most rapid healing. Trefoil peptides are abundantly expressed epithelial cell products which exert protective effects and are key regulators of gastrointestinal epithelial restitution, the critical early phase of cell migration after mucosal injury. To assess the role of trefoil peptides in corneal epithelial wound healing, the effects of intestinal trefoil factor (ITF/TFF3) and spasmolytic polypeptide (SP/TFF2) on migration and proliferation of corneal epithelial cells were analyzed. Both ITF and SP enhanced restitution of primary rabbit corneal epithelial cells in vitro. While the restitution-enhancing effects of TGF-alpha and TGF-beta were both inhibited by neutralizing anti-TGF-beta-antibodies, trefoil peptide stimulation of restitution was not. Neither trefoil peptide significantly affected proliferation of primary corneal epithelial cells. ITF but not SP or pS2 mRNA was present in rabbit corneal and conjunctival tissues. In summary, the data indicate an unanticipated role of trefoil peptides in healing of ocular surface and demand rating their functional actions beyond the gastrointestinal tract.

  19. Sulfonated dyes attenuate the toxic effects of beta-amyloid in a structure-specific fashion.

    Science.gov (United States)

    Pollack, S J; Sadler, I I; Hawtin, S R; Tailor, V J; Shearman, M S

    1995-09-15

    We recently reported that several sulfate-containing glycosaminoglycans, a class of compounds associated with the beta-amyloid plaques of Alzheimer's disease, attenuate the toxic effects of beta-amyloid fragments beta 25-35 and beta 1-40. The amyloid-binding sulfonated dye Congo Red was shown to have a similar effect. Using two clonal cell lines, we now demonstrate that several sulfonated dyes attenuate beta-amyloid toxicity and that the protective effect appears specific for compounds whose sulfonate groups can interact with the beta-pleated structure of aggregated amyloid. These results suggest that by binding beta-amyloid these compounds may prevent toxic interactions of the peptide with cells.

  20. A molecular dynamics and circular dichroism study of a novel synthetic antimicrobial peptide

    Science.gov (United States)

    Rodina, N. P.; Yudenko, A. N.; Terterov, I. N.; Eliseev, I. E.

    2013-08-01

    Antimicrobial peptides are a class of small, usually positively charged amphiphilic peptides that are used by the innate immune system to combat bacterial infection in multicellular eukaryotes. Antimicrobial peptides are known for their broad-spectrum antimicrobial activity and thus can be used as a basis for a development of new antibiotics against multidrug-resistant bacteria. The most challengeous task on the way to a therapeutic use of antimicrobial peptides is a rational design of new peptides with enhanced activity and reduced toxicity. Here we report a molecular dynamics and circular dichroism study of a novel synthetic antimicrobial peptide D51. This peptide was earlier designed by Loose et al. using a linguistic model of natural antimicrobial peptides. Molecular dynamics simulation of the peptide folding in explicit solvent shows fast formation of two antiparallel beta strands connected by a beta-turn that is confirmed by circular dichroism measurements. Obtained from simulation amphipatic conformation of the peptide is analysed and possible mechanism of it's interaction with bacterial membranes together with ways to enhance it's antibacterial activity are suggested.

  1. Interaction between bradykinin potentiating nonapeptide (BPP9a) and {beta}-cyclodextrin: A structural and thermodynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Lula, Ivana; De Sousa, Frederico B. [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901, Belo Horizonte, MG (Brazil); Denadai, Angelo M.L. [Centro Federal de Educacao Tecnologica de Minas Gerais, CEFET-MG, Campus VII, 35.183-006, Timoteo, MG (Brazil); Ferreira de Lima, Guilherme; Duarte, Helio Anderson [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 31270-901, Belo Horizonte, MG (Brazil); Mares Guia, Thiago R. dos [Departamento de Bioquimica e Imunologia, ICB, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, MG (Brazil); Faljoni-Alario, Adelaide [Departamento de Bioquimica, Instituto de Quimica, Universidade de Sao Paulo, 05508-900, Sao Paulo, SP (Brazil); Santoro, Marcelo M. [Departamento de Bioquimica e Imunologia, ICB, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, MG (Brazil); Camargo, Antonio C.M. de [Center for Applied Toxinology CAT-CEPID, Laboratorio Especial de Toxicologia Aplicada, Instituto Butantan, 05503-900, Sao Paulo, SP (Brazil); Santos, Robson A.S. dos [Departamento de Fisiologia e Biofisica, ICB, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, MG (Brazil); and others

    2012-02-01

    Herein, we demonstrate the physical and chemical characterizations of the supramolecular complex formed between {beta}-cyclodextrin ({beta}CD) and bradykinin potentiating nonapeptide (BPP9a), an endogenous toxin found in Bothrops jararaca. Circular dichroism results indicate a conformational change in the BPP9a secondary structure upon its complexation with {beta}CD. Nuclear magnetic resonance results, mainly from NOESY experiments, and theoretical calculations showed a favorable interaction between the tryptophan residue of BPP9a and the {beta}CD cavity. Thermodynamic inclusion parameters were investigated by isothermal titration calorimetry, demonstrating that {beta}CD/BPP9a complex formation is an exothermic process that results in a reduction in entropy. Additionally, in vitro degradation study of BPP9a against trypsin (37 Degree-Sign C, pH 7.2) showed higher stability of peptide in presence of {beta}CD. This {beta}CD/BPP9a complex, which presents new chemical properties arising from the peptide inclusion process, may be useful as an antihypertensive drug in oral pharmaceutical formulations. Highlights: Black-Right-Pointing-Pointer Cd and NMR showed evidences for the existence of more than one structure in solution. Black-Right-Pointing-Pointer Complexation with {beta}CD reduces the conformational rigidity of the peptide. Black-Right-Pointing-Pointer {beta}CD cavity recognize Trp and/or Pro segments of BPP9a. Black-Right-Pointing-Pointer Interactions involving disaggregation of BPP9a assemblies and binding with {beta}CD.

  2. Activation of multiple mitogen-activated protein kinases by recombinant calcitonin gene-related peptide receptor.

    Science.gov (United States)

    Parameswaran, N; Disa, J; Spielman, W S; Brooks, D P; Nambi, P; Aiyar, N

    2000-02-18

    Calcitonin gene-related peptide is a 37-amino-acid neuropeptide and a potent vasodilator. Although calcitonin gene-related peptide has been shown to have a number of effects in a variety of systems, the mechanisms of action and the intracellular signaling pathways, especially the regulation of mitogen-activated protien kinase (MAPK) pathway, is not known. In the present study we investigated the role of calcitonin gene-related peptide in the regulation of MAPKs in human embryonic kidney (HEK) 293 cells stably transfected with a recombinant porcine calcitonin gene-related peptide-1 receptor. Calcitonin gene-related peptide caused a significant dose-dependent increase in cAMP response and the effect was inhibited by calcitonin gene-related peptide(8-37), the calcitonin gene-related peptide-receptor antagonist. Calcitonin gene-related peptide also caused a time- and concentration-dependent increase in extracellular signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (P38 MAPK) activities, with apparently no significant change in cjun-N-terminal kinase (JNK) activity. Forskolin, a direct activator of adenylyl cyclase also stimulated ERK and P38 activities in these cells suggesting the invovement of cAMP in this process. Calcitonin gene-related peptide-stimulated ERK and P38 MAPK activities were inhibited significantly by calcitonin gene-related peptide receptor antagonist, calcitonin gene-related peptide-(8-37) suggesting the involvement of calcitonin gene-related peptide-1 receptor. Preincubation of the cells with the cAMP-dependent protein kinase inhibitor, H89 [¿N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide, hydrochloride¿] inhibited calcitonin gene-related peptide-mediated activation of ERK and p38 kinases. On the other hand, preincubation of the cells with wortmannin ¿[1S-(1alpha,6balpha,9abeta,11alpha, 11bbeta)]-11-(acetyloxy)-1,6b,7,8,9a,10,11, 11b-octahydro-1-(methoxymethyl)-9a,11b-dimethyl-3H-furo[4,3, 2-de]indeno[4,5-h]-2

  3. Antimicrobial beta-peptides and alpha-peptoids

    DEFF Research Database (Denmark)

    Godballe, Troels; Nilsson, Line L.; Petersen, Pernille D.;

    2011-01-01

    The field of drug discovery and development has seen tremendous activity over the past decade to better tackle the increasing occurrence of drugresistant bacterial infections and to alleviate some of the pressure we put on the last-resort drugs on the market. One of the new and promising drug...

  4. Astrocytic expression of the Alzheimer's disease beta-secretase (BACE1) is stimulus-dependent

    DEFF Research Database (Denmark)

    Hartlage-Rübsamen, Maike; Zeitschel, Ulrike; Apelt, Jenny;

    2003-01-01

    The beta-site APP-cleaving enzyme (BACE1) is a prerequisite for the generation of beta-amyloid peptides, which give rise to cerebrovascular and parenchymal beta-amyloid deposits in the brain of Alzheimer's disease patients. BACE1 is neuronally expressed in the brains of humans and experimental...... paradigms studied. In contrast, BACE1 expression by reactive astrocytes was evident in chronic but not in acute models of gliosis. Additionally, we observed BACE1-immunoreactive astrocytes in proximity to beta-amyloid plaques in the brains of aged Tg2576 mice and Alzheimer's disease patients....

  5. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    -looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta...

  6. Calcium signaling and amyloid toxicity in Alzheimer disease.

    Science.gov (United States)

    Demuro, Angelo; Parker, Ian; Stutzmann, Grace E

    2010-04-23

    Intracellular Ca(2+) signaling is fundamental to neuronal physiology and viability. Because of its ubiquitous roles, disruptions in Ca(2+) homeostasis are implicated in diverse disease processes and have become a major focus of study in multifactorial neurodegenerative diseases such as Alzheimer disease (AD). A hallmark of AD is the excessive production of beta-amyloid (Abeta) and its massive accumulation in amyloid plaques. In this minireview, we highlight the pathogenic interactions between altered cellular Ca(2+) signaling and Abeta in its different aggregation states and how these elements coalesce to alter the course of the neurodegenerative disease. Ca(2+) and Abeta intersect at several functional levels and temporal stages of AD, thereby altering neurotransmitter receptor properties, disrupting membrane integrity, and initiating apoptotic signaling cascades. Notably, there are reciprocal interactions between Ca(2+) pathways and amyloid pathology; altered Ca(2+) signaling accelerates Abeta formation, whereas Abeta peptides, particularly in soluble oligomeric forms, induce Ca(2+) disruptions. A degenerative feed-forward cycle of toxic Abeta generation and Ca(2+) perturbations results, which in turn can spin off to accelerate more global neuropathological cascades, ultimately leading to synaptic breakdown, cell death, and devastating memory loss. Although no cause or cure is currently known, targeting Ca(2+) dyshomeostasis as an underlying and integral component of AD pathology may result in novel and effective treatments for AD.

  7. Specific recognition of the C-terminal end of A beta 42 by a high affinity monoclonal antibody

    DEFF Research Database (Denmark)

    Axelsen, T.V.; Holm, A.; Birkelund, S.;

    2009-01-01

    The neurotoxic peptide A beta(42) is derived from the amyloid precursor protein by proteolytic cleavage and is deposited in the brain of patients suffering from Alzheimer's disease (AD). In this study we generate a high affinity monoclonal antibody that targets the C-terminal end of A beta(42) with...

  8. Amyloid-beta(29-42) dimer formations studied by a multicanonical-multioverlap molecular dynamics simulation.

    Science.gov (United States)

    Itoh, Satoru G; Okamoto, Yuko

    2008-03-13

    Amyloid-beta peptides are known to form amyloid fibrils and are considered to play an important role in Alzheimer's disease. Amyloid-beta(29-42) is a fragment of the amyloid-beta peptide and also has a tendency to form amyloid fibrils. In order to study the mechanism of amyloidogenesis of this fragment, we applied one of the generalized-ensemble algorithms, the multicanonical-multioverlap algorithm, to amyloid-beta(29-42) dimer in aqueous solution. We obtained a detailed free-energy landscape of the dimer system. From the detailed free-energy landscape, we examined monomer and dimer formations of amyloid-beta(29-42) and deduced dimerization processes, which correspond to seeding processes in the amyloidogenesis of amyloid-beta(29-42).

  9. Di/tri-peptide transporters as drug delivery targets

    DEFF Research Database (Denmark)

    Nielsen, C U; Brodin, Birger

    2003-01-01

    Two human di/tri-peptide transporters, hPepT1 and hPepT2 have been identified and functionally characterized. In the small intestine hPepT1 is exclusively expressed, whereas both PepT1 and PepT2 are expressed in the proximal tubule. The transport via di/tri-peptide transporters is proton-dependen....../tri-peptide transporters from vesicular storages 3) changes in gene transcription/mRNA stability. The aim of the present review is to discuss physiological, patho-physiological and drug-induced regulation of di/tri-peptide transporter mediated transport.......-dependent, and the transporters thus belong to the Proton-dependent Oligopeptide Transporter (POT)-family. The transporters are not drug targets per se, however due to their uniquely broad substrate specificity; they have proved to be relevant drug targets at the level of drug transport. Drug molecules such as oral active beta...

  10. Plant signalling peptides

    OpenAIRE

    Wiśniewska, Justyna; Trejgell, Alina; Tretyn, Andrzej

    2003-01-01

    Biochemical and genetic studies have identified peptides that play crucial roles in plant growth and development, including defence mechanisms in response to wounding by pests, the control of cell division and expansion, and pollen self-incompatibility. The first two signalling peptides to be described in plants were tomato systemin and phytosulfokine (PSK). There is also biochemical evidence that natriuretic peptide-like molecules, immunologically-relatedt o those found ...

  11. Polycyclic peptide therapeutics.

    Science.gov (United States)

    Baeriswyl, Vanessa; Heinis, Christian

    2013-03-01

    Owing to their excellent binding properties, high stability, and low off-target toxicity, polycyclic peptides are an attractive molecule format for the development of therapeutics. Currently, only a handful of polycyclic peptides are used in the clinic; examples include the antibiotic vancomycin, the anticancer drugs actinomycin D and romidepsin, and the analgesic agent ziconotide. All clinically used polycyclic peptide drugs are derived from natural sources, such as soil bacteria in the case of vancomycin, actinomycin D and romidepsin, or the venom of a fish-hunting coil snail in the case of ziconotide. Unfortunately, nature provides peptide macrocyclic ligands for only a small fraction of therapeutic targets. For the generation of ligands of targets of choice, researchers have inserted artificial binding sites into natural polycyclic peptide scaffolds, such as cystine knot proteins, using rational design or directed evolution approaches. More recently, large combinatorial libraries of genetically encoded bicyclic peptides have been generated de novo and screened by phage display. In this Minireview, the properties of existing polycyclic peptide drugs are discussed and related to their interesting molecular architectures. Furthermore, technologies that allow the development of unnatural polycyclic peptide ligands are discussed. Recent application of these technologies has generated promising results, suggesting that polycyclic peptide therapeutics could potentially be developed for a broad range of diseases. PMID:23355488

  12. Mouse egg integrin alpha 6 beta 1 functions as a sperm receptor.

    Science.gov (United States)

    Almeida, E A; Huovila, A P; Sutherland, A E; Stephens, L E; Calarco, P G; Shaw, L M; Mercurio, A M; Sonnenberg, A; Primakoff, P; Myles, D G; White, J M

    1995-06-30

    Binding between sperm and egg plasma membranes is an essential step in fertilization. Whereas fertilin, a mammalian sperm surface protein, is involved in this crucial interaction, sperm receptors on the egg plasma membrane have not been identified. Because fertilin contains a predicted integrin ligand domain, we investigated the expression and function of integrin subunits in unfertilized mouse eggs. Polymerase chain reactions detected mRNAs for alpha 5, alpha 6, alpha v, beta 1, beta 3, and beta 5. Immunofluorescence revealed alpha 6 beta 1 and alpha v beta 3 on the plasma membrane. GoH3, a function-blocking anti-alpha 6 monoclonal antibody, abolished sperm binding, but a nonfunction-blocking anti-alpha 6 monoclonal antibody, a function-blocking anti-alpha v beta 3 polyclonal antibody, and an RGD peptide had no effect. Somatic cells bound sperm avidly, but only if they expressed alpha 6 beta 1. A peptide analog of the fertilin integrin ligand domain inhibited sperm binding to eggs and alpha 6 beta 1+ cells and diminished GoH3 staining of eggs. Our results indicate a novel role for the integrin alpha 6 beta 1 as a cell-cell adhesion receptor that mediates sperm-egg binding. PMID:7600577

  13. Effects of linker variation on the in vitro and in vivo characteristics of an 111In-labeled RGD peptide.

    NARCIS (Netherlands)

    Dijkgraaf, I.; Liu, S.; Kruijtzer, J.A.; Soede, A.C.; Oyen, W.J.G.; Liskamp, R.M.; Corstens, F.H.M.; Boerman, O.C.

    2007-01-01

    INTRODUCTION: Due to the selective expression of the alpha(v)beta3 integrin in tumors, radiolabeled arginine-glycine-aspartic acid (RGD) peptides are attractive candidates for tumor targeting. Minor modifications of these peptides could have a major impact on in vivo characteristics. In this study,

  14. Asymmetric azidation-cycloaddition with open-chain peptide-based catalysts. A sequential enantioselective route to triazoles.

    Science.gov (United States)

    Guerin, David J; Miller, Scott J

    2002-03-13

    A family of beta-substituted histidine-containing peptides has been synthesized to probe the effect of noncovalent conformational rigidification on catalyst enantioselectivity. Unambiguous enhancement of enantioselectivity in the conjugate addition of azide to alpha,beta-unsaturated carboxylate derivatives has been achieved, enabling application to a sequential asymmetric azidation/cycloaddition for the synthesis of optically enriched triazoles and triazolines. PMID:11878965

  15. Increased renal gene transcription of protein kinase C-beta in human diabetic nephropathy: relationship to long-term glycaemic control

    DEFF Research Database (Denmark)

    Langham, R.G.; Kelly, D.J.; Gow, R.M.;

    2008-01-01

    was examined in renal biopsies (n=25) with classical histological features of diabetic nephropathy and compared with that in normal control tissue (n=6). Peptide localisation of PKC-alpha, PKC-beta and the activated forms phosphorylated PKC-alpha and -beta was also performed on matched paraffin......-embedded sections of renal biopsies using immunohistochemistry. The effects of high glucose on PRKC-beta expression and peptide production in cultured human proximal tubular epithelial cells were assessed. RESULTS: Quantitative real-time PCR demonstrated a 9.9-fold increase in PRKC-beta mRNA in kidney biopsies...

  16. Insulin C-peptide test

    Science.gov (United States)

    C-peptide ... the test depends on the reason for the C-peptide measurement. Ask your health care provider if ... C-peptide is measured to tell the difference between insulin the body produces and insulin someone injects ...

  17. Peptide Nucleic Acids

    DEFF Research Database (Denmark)

    2004-01-01

    A novel class of compounds known as peptide nucleic acids, bind complementary DNA and RNA strands, and generally do so more strongly than the corresponding DNA or RNA strands while exhibiting increased sequence specificity and solubility. The peptide nucleic acids comprise ligands selected from...

  18. Neutrinoless double beta decay

    Indian Academy of Sciences (India)

    Kai Zuber

    2012-10-01

    The physics potential of neutrinoless double beta decay is discussed. Furthermore, experimental considerations as well as the current status of experiments are presented. Finally, an outlook towards the future, work on nuclear matrix elements and alternative processes is given.

  19. Beta-carotene

    Science.gov (United States)

    ... chemotherapy for a blood cancer called lymphoblastic leukemia. Mental performance. Some evidence suggests that taking beta-carotene ... One is water-based, and the other is oil-based. Studies show that the water-based version ...

  20. Heterologous amyloid seeding: revisiting the role of acetylcholinesterase in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Létitia Jean

    Full Text Available Neurodegenerative diseases associated with abnormal protein folding and ordered aggregation require an initial trigger which may be infectious, inherited, post-inflammatory or idiopathic. Proteolytic cleavage to generate vulnerable precursors, such as amyloid-beta peptide (Abeta production via beta and gamma secretases in Alzheimer's Disease (AD, is one such trigger, but the proteolytic removal of these fragments is also aetiologically important. The levels of Abeta in the central nervous system are regulated by several catabolic proteases, including insulysin (IDE and neprilysin (NEP. The known association of human acetylcholinesterase (hAChE with pathological aggregates in AD together with its ability to increase Abeta fibrilization prompted us to search for proteolytic triggers that could enhance this process. The hAChE C-terminal domain (T40, AChE(575-614 is an exposed amphiphilic alpha-helix involved in enzyme oligomerisation, but it also contains a conformational switch region (CSR with high propensity for conversion to non-native (hidden beta-strand, a property associated with amyloidogenicity. A synthetic peptide (AChE(586-599 encompassing the CSR region shares homology with Abeta and forms beta-sheet amyloid fibrils. We investigated the influence of IDE and NEP proteolysis on the formation and degradation of relevant hAChE beta-sheet species. By combining reverse-phase HPLC and mass spectrometry, we established that the enzyme digestion profiles on T40 versus AChE(586-599, or versus Abeta, differed. Moreover, IDE digestion of T40 triggered the conformational switch from alpha- to beta-structures, resulting in surfactant CSR species that self-assembled into amyloid fibril precursors (oligomers. Crucially, these CSR species significantly increased Abeta fibril formation both by seeding the energetically unfavorable formation of amyloid nuclei and by enhancing the rate of amyloid elongation. Hence, these results may offer an explanation

  1. [High beta tokamak research

    International Nuclear Information System (INIS)

    Our activities on High Beta Tokamak Research during the past 20 months of the present grant period can be divided into six areas: reconstruction and modeling of high beta equilibria in HBT; measurement and analysis of MHD instabilities observed in HBT; measurements of impurity transport; diagnostic development on HBT; numerical parameterization of the second stability regime; and conceptual design and assembly of HBT-EP. Each of these is described in some detail in the sections of this progress report

  2. Plasma levels of vasoactive regulatory peptides in patients receiving regular hemodialysis treatment.

    Science.gov (United States)

    Hegbrant, J; Thysell, H; Ekman, R

    1992-01-01

    The fasting plasma levels of 10 vasoactive regulatory peptides were measured by radioimmunoassay in 23 stable patients with chronic renal failure receiving regular hemodialysis treatment (RDT) and compared with those of healthy controls. The plasma concentrations of arginine vasopressin, atrial natriuretic peptide, beta-endorphin, methionine-enkephalin, motilin, neuropeptide Y, substance P, and vasoactive intestinal peptide were increased. The plasma level of calcitonin gene-related peptide was not statistically different from that of the controls. The plasma concentration of gamma 2-melanocyte-stimulating hormone was lowered in the RDT-patients. The arterial blood pressure correlated with the plasma levels of motilin and neuropeptide Y. We conclude that patients with chronic renal failure receiving RDT have increased concentrations of 8 out of 10 measured vasoactive regulatory peptides. The elevated levels of vasoactive peptides may contribute to the adaptation of the cardiovascular system to impaired renal function.

  3. Multipin peptide synthesis at the micromole scale using 2-hydroxyethyl methacrylate grafted polyethylene supports

    Energy Technology Data Exchange (ETDEWEB)

    Valerio, R.M.; Bray, A.M.; Campbell, R.A.; Dipasquale, A.; Margellis, C.; Rodda, S.J.; Geysen, H.M.; Maeji, N.J. (Chiron Mimotopes Pty Ltd., Clayton, Victoria (Australia))

    1993-01-01

    The multipin peptide synthesis procedure has been adapted to allow the synthesis of peptides at micromole loadings. The original solid pin support was replaced with a detachable crown-shaped polyethylene support with an increased surface area. In addition, the polyethylene crowns were radiation-grafted with 2-hydroxyethyl methacrylate monomer instead of acrylic acid to yield hydroxy functionalised supports with a larger concentration of polymer and hence a large peptide capacity. Fmoc-[beta]-Alanine was directly esterified to the HEMA hydroxy groups with subsequent addition of a diketopiperazine-forming handle for peptide attachment. Peptides varying in lenght from 10 to 25 residues were assembled at a number of loadings from 1.0 to 2.2 [mu]md. Purity of peptides at all loadings was equal to, and in some instances superior to, that achieved on conventional solid-phase supports. (au) (17 refs.).

  4. 康复训练对血管性痴呆大鼠海马β淀粉样多肽及胰岛素降解酶的影响%The effects of rehabilitation training on amyloid-beta peptide and insulin-degrading enzyme levels in the hippocampus of rats with vascular dementia

    Institute of Scientific and Technical Information of China (English)

    叶青; 王红卫; 游咏; 黄海芬; 廖慧颖; 潘思; 黄雁

    2012-01-01

    Objective To investigate the effects of rehabilitation training on hippocampal amyloid-beta peptide (Aβ) and insulin-degrading enzyme (IDE) levels in vascular dementia (VD).Methods Thirty female Sprague-Dawley rats were randomly assigned to a rehabilitation group (n =10),a model group (n =10) or a sham-operation group (n =10).An experimental VD model was established in the rats of the first 2 groups by bilateral common carotid artery permanent ligation.The rats in the rehabilitation group then received 1 h of rehabilitation training daily.Learning and memory were assessed at 4 weeks aftet the operation.Immunohistochemical staining was used to detect Aβ and IDE expression in the hippocampus dentate gyrus (DG) area.Results The rats in the rehabilitation group showed significantly better learning ability compared with the model group.The expression of Aβ in the rehabilitation group was significantly less than in the model group.The expression of IDE in the rehabilitation group was significantly greater Conclusion Rehabilitation can accelerate the recovery of learning and memory in VD,at least in rats The mechanism is possibly related to decreased accumulation of Aβ in the hippocampus due to up-regulation of the expression of IDE.%目的 观察康复训练对血管性痴呆(VD)大鼠海马β-淀粉样多肽(Aβ)及胰岛素降解酶(IDE)的影响.方法 共选取30只SD大鼠,采用随机数字表法将其分为康复组、模型组及假手术组.选用结扎双侧颈总动脉方法制成VD大鼠模型,康复组每天进行1h康复训练.于术后第4周进行行为学测试,以评估各组大鼠学习记忆能力;待行为学测试结束后采用免疫组化法检测各组大鼠海马(DG)区Aβ及IDE表达.结果 术后第4周时发现康复组大鼠学习记忆功能明显优于模型组(P<0.05);且康复组大鼠海马区Aβ表达较模型组显著降低(P<0.05),IDE表达则较模型组明显增高(P<0.05).结论 康复训练能改善VD大鼠学习

  5. JNK/p38 MAPK involves in ginsenoside Rb1 attenuating beta-amyloid peptide (25-35)-induced tau protein hyperphosphorylation in embryo rat cortical neurons%人参皂苷Rb1通过JNK/p38 MAPK途径减轻Aβ25-35诱导的胎鼠皮层神经元tau蛋白过度磷酸化

    Institute of Scientific and Technical Information of China (English)

    宋锦秋; 陈晓春; 张静; 黄天文; 曾育琦; 沈杰; 陈丽敏

    2008-01-01

    探讨在Aβ25-35(beta-amyloid peptide (25-35),Aβ25-35)诱导的拟阿尔茨海默病样胎鼠皮层神经元tau蛋白过度磷酸化中,人参皂苷Rb1对tau蛋白磷酸化及JNK/p38 MAPK的可能作用.应用蛋白免疫印迹和免疫细胞化学染色的方法,观察tau蛋白磷酸化和JNK(c-jun N-terminal kinase)/p38 MAPK的表达情况.凝聚态Aβ25-35(20 μmol·L-1)作用于皮层神经元12 h,tau蛋白的磷酸化水平明显增高,同时JNK/p38 MAPK的总量及其活性形式--磷酸化JNK/p38 MAPK的蛋白表达水平也增加,人参皂苷Rb1可以减轻tau蛋白的磷酸化水平及JNK/p38 MAPK的蛋白水平.人参皂苷Rb1可通过JNK/p38 MAPK途径减轻Aβ25-35诱导的tau蛋白过度磷酸化.

  6. Clearance of beta-2-microglobulin and middle molecules in haemodiafiltration.

    Science.gov (United States)

    Tattersall, James

    2007-01-01

    Middle molecules, consisting mostly of peptides and small proteins with molecular weight the range of 500-60,000 Da, accumulate in renal failure and contribute to the uraemic toxic state. Beta2-microglobulin (beta2-MG) with a molecular weight of 11,000 is considered representative of these middle molecules. These solutes are not well cleared by low-flux dialysis. High-flux dialysis will clear middle molecules, partly by internal filtration. This convective component of high-flux dialysis can be enhanced in a predictable way by haemodiafiltration (HDF). The convective and diffusive clearance rates of any middle molecule across any haemodiafilter can be predicted from known or measurable factors such as its sieving coefficient, bound fraction and molecular weight. The removal of middle molecules is also influenced by factors within the patient. Beta2-MG is distributed within the extracellular fluid. During HDF, beta2-MG must transfer into the intravascular compartment across the capillary walls. This transcapillary transfer at a rate of approximately 100 ml/min slows beta2-MG removal from the body. Continuing transfer after the end of a treatment session results in a significant rebound of beta2-MG levels. This intercompartment transfer and its effect on beta2-MG clearance and concentration can be predicted by a 2-compartment model. By extrapolation, the behaviour of other middle molecules can be predicted. The 2-compartment model, which takes non-dialytic beta2-MG clearance at a rate of 3 ml/min and beta2-MG generation at a rate of 0.1 mg/min into account, can predict the effect of any HDF schedule on beta2-MG levels. Low-flux dialysis results in a beta2-MG level of around 40 mg/l. Three times weekly, 4-hour HDF can reduce beta2-MG levels to around 20 mg/l. Long (nocturnal) HDF can reduce beta2-MG levels to around 10 mg/l, compared to physiological levels of less than 5 mg/l.

  7. PNA Peptide chimerae

    DEFF Research Database (Denmark)

    Koch, T.; Næsby, M.; Wittung, P.;

    1995-01-01

    Radioactive labelling of PNA has been performed try linking a peptide segment to the PNA which is substrate for protein kinase A. The enzymatic phosphorylation proceeds in almost quantitative yields....

  8. Tumor penetrating peptides

    Directory of Open Access Journals (Sweden)

    Tambet eTeesalu

    2013-08-01

    Full Text Available Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC, contains the integrin-binding RGD motif. RGD mediates tumor homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular zip code of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is

  9. Antimicrobial peptides in echinoderm host defense.

    Science.gov (United States)

    Li, Chun; Blencke, Hans-Matti; Haug, Tor; Stensvåg, Klara

    2015-03-01

    Antimicrobial peptides (AMPs) are important effector molecules in innate immunity. Here we briefly summarize characteristic traits of AMPs and their mechanisms of antimicrobial activity. Echinoderms live in a microbe-rich marine environment and are known to express a wide range of AMPs. We address two novel AMP families from coelomocytes of sea urchins: cysteine-rich AMPs (strongylocins) and heterodimeric AMPs (centrocins). These peptide families have conserved preprosequences, are present in both adults and pluteus stage larvae, have potent antimicrobial properties, and therefore appear to be important innate immune effectors. Strongylocins have a unique cysteine pattern compared to other cysteine-rich peptides, which suggests a novel AMP folding pattern. Centrocins and SdStrongylocin 2 contain brominated tryptophan residues in their native form. This review also includes AMPs isolated from other echinoderms, such as holothuroidins, fragments of beta-thymosin, and fragments of lectin (CEL-III). Echinoderm AMPs are crucial molecules for the understanding of echinoderm immunity, and their potent antimicrobial activity makes them potential precursors of novel drug leads. PMID:25445901

  10. Antimicrobial peptides in echinoderm host defense.

    Science.gov (United States)

    Li, Chun; Blencke, Hans-Matti; Haug, Tor; Stensvåg, Klara

    2015-03-01

    Antimicrobial peptides (AMPs) are important effector molecules in innate immunity. Here we briefly summarize characteristic traits of AMPs and their mechanisms of antimicrobial activity. Echinoderms live in a microbe-rich marine environment and are known to express a wide range of AMPs. We address two novel AMP families from coelomocytes of sea urchins: cysteine-rich AMPs (strongylocins) and heterodimeric AMPs (centrocins). These peptide families have conserved preprosequences, are present in both adults and pluteus stage larvae, have potent antimicrobial properties, and therefore appear to be important innate immune effectors. Strongylocins have a unique cysteine pattern compared to other cysteine-rich peptides, which suggests a novel AMP folding pattern. Centrocins and SdStrongylocin 2 contain brominated tryptophan residues in their native form. This review also includes AMPs isolated from other echinoderms, such as holothuroidins, fragments of beta-thymosin, and fragments of lectin (CEL-III). Echinoderm AMPs are crucial molecules for the understanding of echinoderm immunity, and their potent antimicrobial activity makes them potential precursors of novel drug leads.

  11. Introduction to Peptide Synthesis

    OpenAIRE

    Stawikowski, Maciej; Fields, Gregg B.

    2002-01-01

    A number of synthetic peptides are significant commercial or pharmaceutical products, ranging from the dipeptide sugar-substitute aspartame to clinically used hormones, such as oxytocin, adrenocorticotropic hormone, and calcitonin. This unit provides an overview of the field of synthetic peptides and proteins. It discusses selecting the solid support and common coupling reagents. Additional information is provided regarding common side reactions and synthesizing modified residues.

  12. Role of MicroRNAs in Islet Beta-Cell Compensation and Failure during Diabetes

    Directory of Open Access Journals (Sweden)

    Valérie Plaisance

    2014-01-01

    Full Text Available Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes.

  13. Dysferlin-peptides reallocate mutated dysferlin thereby restoring function.

    Directory of Open Access Journals (Sweden)

    Verena Schoewel

    Full Text Available Mutations in the dysferlin gene cause the most frequent adult-onset limb girdle muscular dystrophy, LGMD2B. There is no therapy. Dysferlin is a membrane protein comprised of seven, beta-sheet enriched, C2 domains and is involved in Ca(2+dependent sarcolemmal repair after minute wounding. On the protein level, point mutations in DYSF lead to misfolding, aggregation within the endoplasmic reticulum, and amyloidogenesis. We aimed to restore functionality by relocating mutant dysferlin. Therefore, we designed short peptides derived from dysferlin itself and labeled them to the cell penetrating peptide TAT. By tracking fluorescently labeled short peptides we show that these dysferlin-peptides localize in the endoplasmic reticulum. There, they are capable of reducing unfolded protein response stress. We demonstrate that the mutant dysferlin regains function in membrane repair in primary human myotubes derived from patients' myoblasts by the laser wounding assay and a novel technique to investigate membrane repair: the interventional atomic force microscopy. Mutant dysferlin abuts to the sarcolemma after peptide treatment. The peptide-mediated approach has not been taken before in the field of muscular dystrophies. Our results could redirect treatment efforts for this condition.

  14. Dysferlin-peptides reallocate mutated dysferlin thereby restoring function.

    Science.gov (United States)

    Schoewel, Verena; Marg, Andreas; Kunz, Severine; Overkamp, Tim; Carrazedo, Romy Siegert; Zacharias, Ute; Daniel, Peter T; Spuler, Simone

    2012-01-01

    Mutations in the dysferlin gene cause the most frequent adult-onset limb girdle muscular dystrophy, LGMD2B. There is no therapy. Dysferlin is a membrane protein comprised of seven, beta-sheet enriched, C2 domains and is involved in Ca(2+)dependent sarcolemmal repair after minute wounding. On the protein level, point mutations in DYSF lead to misfolding, aggregation within the endoplasmic reticulum, and amyloidogenesis. We aimed to restore functionality by relocating mutant dysferlin. Therefore, we designed short peptides derived from dysferlin itself and labeled them to the cell penetrating peptide TAT. By tracking fluorescently labeled short peptides we show that these dysferlin-peptides localize in the endoplasmic reticulum. There, they are capable of reducing unfolded protein response stress. We demonstrate that the mutant dysferlin regains function in membrane repair in primary human myotubes derived from patients' myoblasts by the laser wounding assay and a novel technique to investigate membrane repair: the interventional atomic force microscopy. Mutant dysferlin abuts to the sarcolemma after peptide treatment. The peptide-mediated approach has not been taken before in the field of muscular dystrophies. Our results could redirect treatment efforts for this condition. PMID:23185377

  15. Radioimmunoassay for C-peptide in diabetic children

    International Nuclear Information System (INIS)

    Direct insulin radioimmunoassay (RIA) studies in a diabetic are no longer meaningful once insulin therapy has been instituted. For this reason, use is made of RIA for blood C-peptide, a proinsulin component reflecting endogenous insulin secretion independently of insulin therapy. The paper reports experience with C-peptide RIA studies carried out on blood from 273 diabetic children of normal body weight and 11.3 years average age, as well as 31 healthy children (control group). Diabetes duration ranged from 7 days to 14 years. The basic level of C-peptide in diabetic children is lower than that of healthy ones. Glucose stimulation produces C-peptide elevation in healthy but not in diabetic children. Glucagon stimulation produced a further rise of blood C-peptide in the healthy children. Diabetics showed very modest response to glucagon stimulation. C-peptide secretion in diabetic children proved to be inversely proportional to the duration of the diabetes. These findings in children with diabetes mellitus indicated their insulin secretion by beta cells of the pancreatic islets of Langerhans to be substantially decreased and unresponsive to glucose and glucagon stimulation. 3 figs, 1 tab

  16. Beta and Gamma Gradients

    DEFF Research Database (Denmark)

    Løvborg, Leif; Gaffney, C. F.; Clark, P. A.;

    1985-01-01

    Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...

  17. Double beta decay experiments

    International Nuclear Information System (INIS)

    The great sensitivity of double beta decay to neutrino mass and right handed currents has motivated many new and exciting attempts to observe this elusive nuclear phenomenon directly. Experiments in operation and other coming on line in the next one or two years are expected to result in order-of-magnitude improvements in detectable half lives for both the two-neutrino and no-neutrino modes. A brief history of double beta decay experiments is presented together with a discussion of current experimental efforts, including a gas filled time projection chamber being used to study selenium-82. (author)

  18. Molecular cloning and characterization of three beta-defensins from canine testes.

    Science.gov (United States)

    Sang, Yongming; Ortega, M Teresa; Blecha, Frank; Prakash, Om; Melgarejo, Tonatiuh

    2005-05-01

    Mammalian beta-defensins are small cationic peptides possessing broad antimicrobial and physiological activities. Because dogs are particularly resilient to sexually transmitted diseases, it has been proposed that their antimicrobial peptide repertoire might provide insight into novel antimicrobial therapeutics and treatment regimens. To investigate this proposal, we cloned the full-length cDNA of three canine beta-defensin isoforms (cBD-1, -2, and -3) from canine testicular tissues. Their predicted peptides share identical N-terminal 65-amino-acid residues, including the beta-defensin consensus six-cysteine motif. The two longer isoforms, cBD-2 and -3, possess 4 and 34 additional amino acids, respectively, at the C terminus. To evaluate the antimicrobial activity of cBD, a 34-amino-acid peptide derived from the shared mature peptide region was synthesized. Canine beta-defensin displayed broad antimicrobial activity against gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus; MICs of 6 and 100 mug/ml, respectively), gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, and Neisseria gonorrhoeae; MICs of 20 to 50, 20, and 50 mug/ml, respectively), and yeast (Candida albicans; MIC of 5 to 50 mug/ml) and lower activity against Ureaplasma urealyticum and U. canigenitalium (MIC of 200 mug/ml). Antimicrobial potency was significantly reduced at salt concentrations higher than 140 mM. All three canine beta-defensins were highly expressed in testis. In situ hybridization indicated that cBD-1 was expressed primarily in Sertoli cells within the seminiferous tubules. In contrast, cBD-2 was located primarily within Leydig cells. The longest isoform, cBD-3, was detected in Sertoli cells and to a lesser extent in the interstitium. The tissue-specific expression and broad antimicrobial activity suggest that canine beta-defensins play an important role in host defense and other physiological functions of the male reproductive system. PMID:15845463

  19. Changes in the processing of beta-endorphin in the hypothalamus and pituitary gland of female rats during sexual maturation.

    Science.gov (United States)

    Martensz, N D

    1985-11-01

    Puberty in the female rat is accompanied by a marked attenuation of the opioid inhibition of luteinizing hormone secretion. One factor which may contribute to this altered role is a change in the metabolism of opioid peptides during sexual maturation. beta-Endorphin undergoes a considerable degree of metabolism through both C-terminal proteolysis and N-acetylation, and these metabolites do not possess opioid activity. The processing of beta-endorphin in the hypothalamus and in the anterior and neurointermediate lobes of the pituitary gland in prepubertal and adult female rats was studied using gel filtration and high performance liquid chromatography coupled with radioimmunoassay. In the anterior lobe, high molecular weight precursors of beta-endorphin (pro-opiomelanocortin and beta-lipotropin) were present in prepubertal (28 days old) rats, but little authentic beta-endorphin was detected. In contrast, only beta-lipotropin and beta-endorphin were present in mature (70 days old) animals. Only beta-endorphin-sized peptides were present in the neurointermediate lobes of both prepubertal and adult rats. However, the proportion of N-acetylated metabolites was higher in sexually mature animals. In the hypothalamus, only beta-endorphin-sized peptides were present in both juvenile and adult animals. However, C-terminal proteolysis increased with age (no acetylated metabolites were detectable in this tissue). The proportion of the total beta-endorphin-like immunoreactivity attributable to beta-endorphin was lower in young adult (first dioestrus after vaginal opening) (55%) and mature (dioestrus, 61-64 days old) rats (56%) compared to prepubertal (30 days old) animals (75%) and the proportions of non-acetylated metabolites [beta-endorphin-(1-27) in young adults and beta-endorphin-(1-26) in adults] were increased concomitantly. These changes were correlated with a reduced luteinizing hormone response to the opiate antagonist naloxone in adult compared to prepubertal rats

  20. Release of salusin-beta from human monocytes/macrophages.

    Science.gov (United States)

    Sato, Kengo; Fujimoto, Kazumi; Koyama, Takatoshi; Shichiri, Masayoshi

    2010-06-01

    Salusin-alpha and salusin-beta are related bioactive peptides biosynthesized from the same precursor, prosalusin. Despite the potent hemodynamic and proatherosclerotic activities of salusin-beta, its exact distribution and biological functions remain largely undetermined because of technical difficulties associated with its unique physicochemical characteristics, such as marked adhesiveness to polypropylene and polystyrene. By circumventing these problems, we recently established a specific radioimmunoassay for detecting immunoreactive human salusin-beta. In the current study, we demonstrated the release of salusin-beta from the human monoblastic leukemia cell lines, THP-1 and U937. Dilution curves of extracted conditioned media from both cells were parallel with those of standard human salusin-beta by radioimmunoassay. Reverse-phase high performance liquid chromatography coupled with radioimmunoassay detection of the culture supernatants revealed a major immunoreactive component that co-eluted with authentic salusin-beta. Both cell lines secreted salusin-beta-like immunoreactivity (LI) into serum-free media as a function of time (1234.3 + or - 122.7 and 186.7 + or - 9.1 fmol/10(5) cells per 24h). When THP-1 and U937 cells differentiated into macrophages after incubation with 2-O-tetradecanoylphorbol-13-acetate (TPA), they secreted far greater amounts of salusin-beta-LI into the culture supernatant (3351.9 + or - 899.3 and 1545.8 + or - 183.3 fmol/10(5) cells per 24h). TPA treatment accelerated the processing of prosalusin into its cleaved fragments, suggesting that the increased secretion of salusin-beta-LI in THP-1-derived macrophages was caused by the enhanced intracellular processing of prosalusin. Stimulation with the inflammatory cytokines, tumor necrosis factor alpha (TNF-alpha) and lipopolysaccharide (LPS), resulted in increased secretion of salusin-beta without inducing expression of the gene for preprosalusin, suggesting that TNF-alpha and LPS stimulated

  1. Microwave-assisted click polymerization for the synthesis of A beta(16-22) cyclic oligomers and their self-assembly into polymorphous aggregates

    NARCIS (Netherlands)

    Elgersma, R.C.; van Dijk, M.; Dechesne, A.C.; van Nostrum, C.F.; Hennink, W.E.; Rijkers, D.T.S.; Liskamp, R.M.J.

    2009-01-01

    We report on the design, synthesis, and structural analysis of cyclic oligomers with an amyloidogenic peptide sequence as the repeating unit to obtain novel self-assembling bionanomaterials. The peptide was derived from the Alzheimer A beta(16-22) sequence since its strong tendency to form antiparal

  2. Brain natriuretic peptide and optimal management of heart failure

    Institute of Scientific and Technical Information of China (English)

    LI Nan; WANG Jian-an

    2005-01-01

    Aside from the important role of brain natriuretic peptide (BNP) in diagnosis, and differential diagnosis of heart failure, this biological peptide has proved to be an independent surrogate marker of rehospitalization and death of the fatal disease.Several randomized clinical trials demonstrated that drugs such as beta blocker, angiotensin converting enzyme inhibitor, spironolactone and amiodarone have beneficial effects in decreasing circulating BNP level during the management of chronic heart failure. The optimization of clinical decision-making appeals for a representative surrogate marker for heart failure prognosis. The serial point-of-care assessments of BNP concentration provide a therapeutic goal of clinical multi-therapy and an objective guidance for optimal treatment of heart failure. Nevertheless new questions and problems in this area remain to be clarified. On the basis of current research advances, this article gives an overview of BNP peptide and its property and role in the management of heart failure.

  3. Evaluation of neutrino masses from $m_{\\beta\\beta}$ values

    CERN Document Server

    Khrushchov, V V

    2008-01-01

    A neutrino mass matrix is considered under conditions of the CP invariance and the negligible reactor mixing $\\theta_{13}$ angle. Absolute mass values for three neutrinos are evaluated in normal and inverted hierarchy spectra on the ground of data for oscillation mixing neutrino parameters and effective neutrino mass entering into a probability of neutrinoless two beta decay $m_{\\beta\\beta}$ values.

  4. Trichoderma .beta.-glucosidase

    Science.gov (United States)

    Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yao, Jian

    2006-01-03

    The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl3, and the corresponding BGL3 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL3, recombinant BGL3 proteins and methods for producing the same.

  5. Applied Beta Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Rich, B.L.

    1986-01-01

    Measurements of beta and/or nonpenetrating exposure results is complicated and past techniques and capabilities have resulted in significant inaccuracies in recorded results. Current developments have resulted in increased capabilities which make the results more accurate and should result in less total exposure to the work force. Continued development of works in progress should provide equivalent future improvements.

  6. Neutrinoless Double Beta Decay

    CERN Document Server

    Päs, Heinrich

    2015-01-01

    We review the potential to probe new physics with neutrinoless double beta decay $(A,Z) \\to (A,Z+2) + 2 e^-$. Both the standard long-range light neutrino mechanism as well as short-range mechanisms mediated by heavy particles are discussed. We also stress aspects of the connection to lepton number violation at colliders and the implications for baryogenesis.

  7. beta-endorphin modulates the acute response to a social conflict in male mice but does not play a role in stress-induced changes in sleep

    NARCIS (Netherlands)

    Vaanholt, LM; Turek, FW; Meerlo, P

    2003-01-01

    beta-Endorphin is an endogenous opioid peptide that is released during stress and has been associated with many physiological functions. In this experiment beta-endorphin deficient mice were used to study the role of endorphins in the acute physiological and behavioral responses to a social conflict

  8. Effects of ORP150 on appearance and function of pancreatic beta cells following acute necrotizing pancreatitis.

    Science.gov (United States)

    Deng, Wen-Hong; Chen, Chen; Wang, Wei-Xing; Yu, Jia; Li, Jin-You; Liu, Lei

    2011-06-15

    Pancreatic beta cells produce and release insulin, which decreases the blood glucose level. Endoplasmic reticulum stress caused pancreatic beta cell dysfunction and death in acute necrotizing pancreatitis (ANP). The 150kD oxygen-regulated protein (ORP150) took part in the process of endoplasmic reticulum stress. This study investigated the effect of ORP150 on appearance and function of pancreatic beta cells in ANP. Acute necrotizing pancreatitis relied on retrograde infusion of 5% sodium taurocholate into the bile-pancreatic duct. The severity of ANP was estimated by serum amylase, secretory phospholipase A(2,) and pancreatic histopathology. The changes in appearance and function of pancreatic beta cells were detected by light and electron microscopy and the levels of serum glucose, insulin, and C-peptide. ORP150 expression was studied using western blot and immunohistochemisty assay. The expression of ORP150 mainly appeared on pancreatic beta cells and decreased gradually during the pathogenesis of ANP. The results of light and electron microscopy indicated pancreatic beta cell dysfunction and death, concomitant with elevation of serum glucose, insulin, and C-peptide in ANP. These results imply a probable role of ORP150 in the changes in appearance and function of pancreatic beta cells following acute necrotizing pancreatitis, through the pathway of endoplasmic reticulum stress.

  9. Amino acid preference against beta sheet through allowing backbone hydration enabled by the presence of cation

    CERN Document Server

    Sharley, John N

    2016-01-01

    It is known that steric blocking by peptide sidechains of hydrogen bonding, HB, between water and peptide groups, PGs, in beta sheets accords with an amino acid intrinsic beta sheet preference. The present observations with Quantum Molecular Dynamics, QMD, simulation with quantum mechanical treatment of every water molecule solvating a beta sheet that would be transient in nature suggest that this steric blocking is not applicable in a hydrophobic region unless a cation is present, so that the amino acid beta sheet preference due to this steric blocking is only effective in the presence of a cation. We observed backbone hydration in a polyalanine and to a lesser extent polyvaline alpha helix without a cation being present, but a cation could increase the strength of these HBs. Parallel beta sheets have a greater tendency than antiparallel beta sheets of equivalent small size to retain regular structure in solvated QMD, and a 4 strand 4 inter-PG HB chain parallel beta sheet was used. Stability was reinforced b...

  10. Interferon Beta-1b Injection

    Science.gov (United States)

    Interferon beta-1b injection is used to reduce episodes of symptoms in patients with relapsing-remitting (course ... and problems with vision, speech, and bladder control). Interferon beta-1b is in a class of medications ...

  11. Genetics Home Reference: beta thalassemia

    Science.gov (United States)

    ... for Disease Control and Prevention Centre for Genetics Education (Australia) Cold Spring Harbor Laboratory: Your Genes Your Health Disease InfoSearch: Beta Thalassemia Genomics Education Programme (UK) MalaCards: dominant beta-thalassemia Merck Manual ...

  12. Rat Cardiomyocytes Express a Classical Epithelial Beta-Defensin

    Directory of Open Access Journals (Sweden)

    Annika Linde

    2008-01-01

    Full Text Available Beta-defensins (BDs are classical epithelial antimicrobial peptides of immediate importance in innate host defense. Since recent studies have suggested that certain BDs are also expressed in non-traditional tissues, including whole heart homogenate and because effector molecules of innate immunity and inflammation can influence the development of certain cardiovascular disease processes, we hypothesized that BDs are produced by cardiomyocytes as a local measure of cardioprotection against danger signals. Here we report that at least one rat beta-defensin, rBD1, is expressed constitutively in cardiomyocytes specifically isolated using position-ablation-laser-microdissection (P.A.L.M. Microlaser Technologies. RT-PCR analysis showed expression of a single 318 bp transcript in adult rat heart (laser-excised cardiomyocytes and H9c2 cells (neonatal rat heart myoblasts. Moreover, the full length cDNA of rBD1 was established and translated into a putative peptide with 69 amino acid residues. The predicted amino acid sequence of the adult rat cardiac BD-1 peptide displayed 99% identity with the previously reported renal rBD1 and 88, 53, 53 and 50% identity with mouse, human, gorilla and rhesus monkey BD1 respectively. Furthermore, structural analysis of the cardiac rBD1 showed the classical six-cysteine conserved motif of the BD family with an alpha-helix and three beta-sheets. Additionally, rBD1 displayed a significantly greater number of amphoteric residues than any of the human analogs, indicating a strong pH functional dependence in the rat. We suggest that rBD1, which was initially believed to be a specific epithelium-derived peptide, may be also involved in local cardiac innate immune defense mechanisms.

  13. Beta emitters and radiation protection

    DEFF Research Database (Denmark)

    Jødal, Lars

    2009-01-01

    BACKGROUND. Beta emitters, such as 90Y, are increasingly being used for cancer treatment. However, beta emitters demand other precautions than gamma emitters during preparation and administration, especially concerning shielding. AIM. To discuss practical precautions for handling beta emitters...... on the outside of the primary shielding material. If suitable shielding is used and larger numbers of handlings are divided among several persons, then handling of beta emitters can be a safe procedure....

  14. Antimicrobial Peptides from Plants

    Science.gov (United States)

    Tam, James P.; Wang, Shujing; Wong, Ka H.; Tan, Wei Liang

    2015-01-01

    Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms. PMID:26580629

  15. Antimicrobial Peptides from Plants

    Directory of Open Access Journals (Sweden)

    James P. Tam

    2015-11-01

    Full Text Available Plant antimicrobial peptides (AMPs have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic, lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms.

  16. Electron transfer in peptides.

    Science.gov (United States)

    Shah, Afzal; Adhikari, Bimalendu; Martic, Sanela; Munir, Azeema; Shahzad, Suniya; Ahmad, Khurshid; Kraatz, Heinz-Bernhard

    2015-02-21

    In this review, we discuss the factors that influence electron transfer in peptides. We summarize experimental results from solution and surface studies and highlight the ongoing debate on the mechanistic aspects of this fundamental reaction. Here, we provide a balanced approach that remains unbiased and does not favor one mechanistic view over another. Support for a putative hopping mechanism in which an electron transfers in a stepwise manner is contrasted with experimental results that support electron tunneling or even some form of ballistic transfer or a pathway transfer for an electron between donor and acceptor sites. In some cases, experimental evidence suggests that a change in the electron transfer mechanism occurs as a result of donor-acceptor separation. However, this common understanding of the switch between tunneling and hopping as a function of chain length is not sufficient for explaining electron transfer in peptides. Apart from chain length, several other factors such as the extent of the secondary structure, backbone conformation, dipole orientation, the presence of special amino acids, hydrogen bonding, and the dynamic properties of a peptide also influence the rate and mode of electron transfer in peptides. Electron transfer plays a key role in physical, chemical and biological systems, so its control is a fundamental task in bioelectrochemical systems, the design of peptide based sensors and molecular junctions. Therefore, this topic is at the heart of a number of biological and technological processes and thus remains of vital interest.

  17. Electromembrane extraction of peptides.

    Science.gov (United States)

    Balchen, Marte; Reubsaet, Léon; Pedersen-Bjergaard, Stig

    2008-06-20

    Rapid extraction of eight different peptides using electromembrane extraction (EME) was demonstrated for the first time. During an extraction time of 5 min, the model peptides migrated from a 500 microL aqueous acidic sample solution, through a thin supported liquid membrane (SLM) of an organic liquid sustained in the pores in the wall of a porous hollow fiber, and into a 25 microL aqueous acidic acceptor solution present inside the lumen of the hollow fiber. The driving force of the extraction was a 50 V potential sustained across the SLM, with the positive electrode in the sample and the negative electrode in the acceptor solution. The nature and the composition of the SLM were highly important for the EME process, and a mixture of 1-octanol and 15% di(2-ethylhexyl) phosphate was found to work properly. Using 1mM HCl as background electrolyte in the sample and 100 mM HCl in the acceptor solution, and agitation at 1050 rpm, enrichment up to 11 times was achieved. Recoveries were found to be dependent on the structure of the peptide, indicating that the polarity and the number of ionized groups were important parameters affecting the extraction efficiency. The experimental findings suggested that electromembrane extraction of peptides is possible and may be a valuable tool for future extraction of peptides. PMID:18479691

  18. Human beta 2 chain of laminin (formerly S chain): cDNA cloning, chromosomal localization, and expression in carcinomas

    DEFF Research Database (Denmark)

    Wewer, U M; Gerecke, D R; Durkin, M E;

    1994-01-01

    Overlapping cDNA clones that encode the full-length human laminin beta 2 chain, formerly called the S chain, were isolated. The cDNA of 5680 nt contains a 5391-nt open reading frame encoding 1797 amino acids. At the amino terminus is a 32-amino-acid signal peptide that is followed by the mature...... beta 2 chain polypeptide of 1765 amino acids with a calculated molecular mass of 192,389 Da. The human beta 2 chain is predicted to have all of the seven structural domains typical of the beta chains of laminin, including the short cysteine-rich alpha region. The amino acid sequence of human beta 2...... chain showed 86.1% sequence identity to the rat beta 2 chain, 50.0% to the human beta 1 chain, and 36.3% to the human beta 3 chain. The greatest sequence identity was in domains VI, V, and III. The sequence of a 24-amino-acid peptide fragment isolated from the beta 2 chain of laminin purified from human...

  19. Misleading Betas: An Educational Example

    Science.gov (United States)

    Chong, James; Halcoussis, Dennis; Phillips, G. Michael

    2012-01-01

    The dual-beta model is a generalization of the CAPM model. In the dual-beta model, separate beta estimates are provided for up-market and down-market days. This paper uses the historical "Anscombe quartet" results which illustrated how very different datasets can produce the same regression coefficients to motivate a discussion of the…

  20. TGF-beta and osteoarthritis.

    NARCIS (Netherlands)

    Blaney Davidson, E.N.; Kraan, P.M. van der; Berg, W.B. van den

    2007-01-01

    OBJECTIVE: Cartilage damage is a major problem in osteoarthritis (OA). Growth factors like transforming growth factor-beta (TGF-beta) have great potential in cartilage repair. In this review, we will focus on the potential therapeutic intervention in OA with TGF-beta, application of the growth facto

  1. Effects of meal size and composition on incretin, alpha-cell, and beta-cell responses

    DEFF Research Database (Denmark)

    Rijkelijkhuizen, Josina M; McQuarrie, Kelly; Girman, Cynthia J;

    2009-01-01

    The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) regulate postprandial insulin release from the beta-cells. We investigated the effects of 3 standardized meals with different caloric and nutritional content in terms of postprandial glucose, insu...

  2. Pseudosubstrate regulation of the SCF(beta-TrCP) ubiquitin ligase by hnRNP-U

    DEFF Research Database (Denmark)

    Davis, Matti; Hatzubai, Ada; Andersen, Jens S;

    2002-01-01

    by competition with a pIkappaB(alpha) peptide, or by a specific point mutation in the E3RS WD region, indicating an E3-substrate-type interaction. However, unlike pI(kappa)Balpha, which is targeted by SCF(beta-TrCP) for degradation, the E3-bound hnRNP-U is stable and is, therefore, a pseudosubstrate...

  3. Proteins differentially expressed in human beta-cells-enriched pancreatic islet cultures and human insulinomas

    DEFF Research Database (Denmark)

    Terra, Letícia F; Teixeira, Priscila C; Wailemann, Rosangela A M;

    2013-01-01

    In view of the great demand for human beta-cells for physiological and medical studies, we generated cell lines derived from human insulinomas which secrete insulin, C-peptide and express neuroendocrine and islet markers. In this study, we set out to characterize their proteomes, comparing them t...

  4. New insights in dihydropyrimidine dehydrogenase deficiency: a pivotal role for beta-aminoisobutyric acid?

    Science.gov (United States)

    Van Kuilenburg, André B P; Stroomer, Alida E M; Van Lenthe, Henk; Abeling, Nico G G M; Van Gennip, Albert H

    2004-04-01

    DPD (dihydropyrimidine dehydrogenase) constitutes the first step of the pyrimidine degradation pathway, in which the pyrimidine bases uracil and thymine are catabolized to beta-alanine and the R-enantiomer of beta-AIB (beta-aminoisobutyric acid) respectively. The S-enantiomer of beta-AIB is predominantly derived from the catabolism of valine. It has been suggested that an altered homoeostasis of beta-alanine underlies some of the clinical abnormalities encountered in patients with a DPD deficiency. In the present study, we demonstrated that only a slightly decreased concentration of beta-alanine was present in the urine and plasma, whereas normal levels of beta-alanine were present in the cerebrospinal fluid of patients with a DPD deficiency. Therefore the metabolism of beta-alanine-containing peptides, such as carnosine, may be an important factor involved in the homoeostasis of beta-alanine in patients with DPD deficiency. The mean concentration of beta-AIB was approx. 2-3-fold lower in cerebrospinal fluid and urine of patients with a DPD deficiency, when compared with controls. In contrast, strongly decreased levels (10-fold) of beta-AIB were present in the plasma of DPD patients. Our results demonstrate that, under pathological conditions, the catabolism of valine can result in the production of significant amounts of beta-AIB. Furthermore, the observation that the R-enantiomer of beta-AIB is abundantly present in the urine of DPD patients suggests that significant cross-over exists between the thymine and valine catabolic pathways. PMID:14705962

  5. Aumento en la prevalencia de estreptococos beta hemolíticos en hisopados faríngeos en Buenos Aires High prevalence of beta hemolytic streptococci isolated from throat swabs in Buenos Aires

    Directory of Open Access Journals (Sweden)

    Hugo E. Villar

    2005-08-01

    Full Text Available El estreptococo beta hemolítico grupo A (EBHGA es el agente bacteriano más frecuentemente aislado en casos de faringoamigdalitis. Otros estreptococos beta hemolíticos no A también pueden producir esta enfermedad. Ante el elevado número de aislamientos obtenidos en el año 2004 decidimos realizar un estudio con el objeto de evaluar la prevalencia de estos microorganismos durante un período de 5 años. Se incluyeron todos los cultivos de hisopados faríngeos que se realizaron con idéntica metodología. Se consideró niños a los comprendidos entre 6 meses y 18 años de edad, y adultos a los mayores de 18 años. Los aislamientos fueron identificados según la metodología habitual. La determinación de grupo se realizó mediante la aglutinación con partículas de látex. La recuperación de EBHGA fue significativamente mayor en niños en relación a los adultos. En el año 2004 se obtuvo una recuperación significativamente mayor de EBHGA, EBHGC y EBHGG en niños y de EBHGA y EBHGG en adultos respecto de los años anteriores. El aislamiento de EBHGG fue mayor en adultos. El 18.9% y el 5.8% de los estreptococos beta hemolíticos aislados en niños y adultos respectivamente no pertenecieron al grupo A. El incremento en la prevalencia de estreptococos beta hemolíticos refuerza la buena práctica de realizar cultivos en adultos y niños así como la correcta búsqueda en el laboratorio de bacteriología de los estreptococos beta hemolíticos no pertenecientes al grupo A.Beta hemolytic streptococci, particulary group A, are the most frequently isolated pathogens in cases of pharyngoamigdalitis. Other beta hemolytic streptococci also produce this pathology. An increase of positive cultures for group A streptococci was detected during 2004 in relation to previous years. The aim of this study was to determine the isolation rates of beta hemolytic streptococci groups A, C and G during a period of 5 years. Pharyngeal exudates were obtained from

  6. Three-dimensional structure in lipid micelles of the pediocin-like antimicrobial peptide curvacin A.

    Science.gov (United States)

    Haugen, Helen Sophie; Fimland, Gunnar; Nissen-Meyer, Jon; Kristiansen, Per Eugen

    2005-12-13

    The 3D structure of the membrane-permeabilizing 41-mer pediocin-like antimicrobial peptide curvacin A produced by lactic acid bacteria has been studied by NMR spectroscopy. In DPC micelles, the cationic and hydrophilic N-terminal half of the peptide forms an S-shaped beta-sheet-like domain stabilized by a disulfide bridge and a few hydrogen bonds. This domain is followed by two alpha-helices: a hydrophilic 6-mer helix between residues 19 and 24 and an amphiphilic/hydrophobic 11-mer helix between residues 29 and 39. There are two hinges in the peptide, one at residues 16-18 between the N-terminal S-shaped beta-sheet-like structure and the central 6-mer helix and one at residues 26-28 between the central helix and the 11-mer C-terminal helix. The latter helix is the only amphiphilic/hydrophobic part of the peptide and is thus presumably the part that penetrates into the hydrophobic phase of target-cell membranes. The hinge between the two helices may introduce the flexibility that allows the helix to dip into membranes. The helix-hinge-helix structure in the C-terminal half of curvacin A clearly distinguishes this peptide from the other pediocin-like peptides whose structures have been analyzed and suggests that curvacin A along with the structural homologues enterocin P and carnobacteriocin BM1 belong to a subgroup of the pediocin-like family of antimicrobial peptides. PMID:16331975

  7. Pregnancy-induced rise in serum C-peptide concentrations in women with type 1 diabetes

    DEFF Research Database (Denmark)

    Nielsen, Lene Ringholm; Rehfeld, Jens F; Pedersen-Bjergaard, Ulrik;

    2009-01-01

    OBJECTIVE: The purpose of this study was to investigate whether pregnancy induces increased insulin production as a marker of improved beta-cell function in women with long-term type 1 diabetes. RESEARCH DESIGN AND METHODS: This was a prospective study of 90 consecutive pregnant women with type 1...... diabetes. At 8, 14, 21, 27, and 33 weeks blood samples were drawn for measurements of A1C, C-peptide, and serum glucose. C-peptide (detection limit: 6 pmol/l) was considered stimulated at a corresponding serum glucose concentration >or=5.0 mmol/l. GAD antibody concentration was determined at 8 and 33 weeks...... in 35 women. RESULTS: C-peptide concentrations gradually increased throughout pregnancy regardless of serum glucose concentrations in the 90 women with a median duration of diabetes of 17 years (range 1-36 years). Among 35 women with paired recordings of stimulated C-peptide, C-peptide production...

  8. Effect of Curcumin on the metal ion induced fibrillization of Amyloid-β peptide

    Science.gov (United States)

    Banerjee, Rona

    2014-01-01

    The effect of Curcumin on Cu(II) and Zn(II) induced oligomerization and protofibrillization of the amyloid-beta (Aβ) peptide has been studied by spectroscopic and microscopic methods. Curcumin could significantly reduce the β-sheet content of the peptide in a time dependent manner. It also plays an antagonistic role in β-sheet formation that is promoted by metal ions like Cu(II) and Zn(II) as observed by Circular Dichroism (CD) spectroscopy. Atomic force microscopic (AFM) images show that spontaneous fibrillization of the peptide occurs in presence of Cu(II) and Zn(II) but is inhibited on incubation of the peptide with Curcumin indicating the beneficial role of Curcumin in preventing the aggregation of Aβ peptide.

  9. Peptide transport through the blood-brain barrier. Final report 1 Jul 87-31 Dec 90

    Energy Technology Data Exchange (ETDEWEB)

    Partridge, W.M.

    1991-01-15

    Most neuropeptides are incapable of entering the brain from blood owing to the presence of unique anatomical structures in the brain capillary wall, which makes up the blood-brain barrier (BBB). Such neuropeptides could be introduced into the bloodstream by intranasal insufflation and, thus, could have powerful medicinal properties (e.g., Beta-endorphin for the treatment of pain, vasopressin analogues for treatment of memory, ACTH analogues for treatment of post-traumatic epilepsy), should these peptides be capable of traversing the BBB. One such strategy for peptide delivery through the BBB is the development of chimeric peptides, which is the basis of the present contract. The production of chimeric peptides involves the covalent coupling of a nontransportable peptide (e.g., Beta-endorphin, vasopressin) to a transportable vector peptide (e.g., insulin, transferrin, cationized albumin, histone). The transportable peptide is capable of penetrating the BBB via receptor-mediated or absorptive-mediated transcytosis. Therefore, the introduction of chimeric peptides allows the nontransportable peptide to traverse the BBB via a physiologic piggy back mechanism.

  10. Therapeutic HIV Peptide Vaccine

    DEFF Research Database (Denmark)

    Fomsgaard, Anders

    2015-01-01

    infection directed to subdominant conserved HIV-1 epitopes restricted to frequent HLA supertypes. The rationale for selecting HIV peptides and adjuvants are provided. Peptide subunit vaccines are regarded as safe due to the simplicity, quality, purity, and low toxicity. The caveat is reduced immunogenicity......Therapeutic vaccines aim to control chronic HIV infection and eliminate the need for lifelong antiretroviral therapy (ART). Therapeutic HIV vaccine is being pursued as part of a functional cure for HIV/AIDS. We have outlined a basic protocol for inducing new T cell immunity during chronic HIV-1...... and hence adjuvants are included to enhance and direct the immune response. Although the vaccine has been tested in ART naïve individuals, we recommend future testing of the vaccine during (early started) ART that improves immune function and to select individuals likely to benefit. Peptides representing...

  11. Synthetic antibiofilm peptides.

    Science.gov (United States)

    de la Fuente-Núñez, César; Cardoso, Marlon Henrique; de Souza Cândido, Elizabete; Franco, Octavio Luiz; Hancock, Robert E W

    2016-05-01

    Bacteria predominantly exist as multicellular aggregates known as biofilms that are associated with at least two thirds of all infections and exhibit increased adaptive resistance to conventional antibiotic therapies. Therefore, biofilms are major contributors to the global health problem of antibiotic resistance, and novel approaches to counter them are urgently needed. Small molecules of the innate immune system called host defense peptides (HDPs) have emerged as promising templates for the design of potent, broad-spectrum antibiofilm agents. Here, we review recent developments in the new field of synthetic antibiofilm peptides, including mechanistic insights, synergistic interactions with available antibiotics, and their potential as novel antimicrobials against persistent infections caused by biofilms. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. PMID:26724202

  12. Effect of botulinum toxin type A on the expression of substance P, calcitionin gene-related peptide,transforming growth factor beta-1 and alpha smooth muscle actin A in wound healing in rats%肉毒毒素A对大鼠皮肤及创面组织中SP、CGRP、TGF-β1和α-SMA的影响

    Institute of Scientific and Technical Information of China (English)

    王琳; 邰宁正; 范志宏

    2009-01-01

    Objective To investigate the effect of botulinum toxin type A on the expression of substance P(SP),calcitionin gene-related peptide(CGRP), transforming growth factor beta-1 (TGF-β1) and alpha smooth muscle actin A(α-SMA) in wound healing. Methods 60 rats were randomly divided into group C (control)、 group L (low-dose) and group H (high-dose), with 20 rats in each group. The wound-healing model was established by excision of four full-thickness skin(1 cm×1 cm, around the injection site) on the back of all SD rats on the 7th day after BTA injection. The wound size was measured and the expression of SP, CGRP, TGF-β1 and α-SMA in wound granulation tissue was assayed by immanohistocbemical staining and computerized image analysis before operation, and 3 days, 7 days and 14 days after operation. Results All the wounds healed 14 days after operation. The wound size in L and H group was not significantly different with that in C group on the 3rd day and 7th day after operation. The positive immuno-staining of SP, CGRP, TGF-β1 and α-SMA in group L and H was significantly weaker than those in C group. Meanwhile, the positive immuno-staining of all above substances in H group was weaker than those in L group significantly. Conclusions Botulinum toxin type A can decrease the expression of SP, CGRP, TGF-β1 and α-SMA in wound healing in a dose-dependent manner with no effect on the healing time.%目的 探讨肉毒毒素A对周围神经末梢释放的感觉神经肽P物质、降钙素基因相关肽及创面组织表达TGF-β1和α-平滑肌肌动蛋白的影响. 方法 60只SD大鼠随机分为空白对照组(C组)、低剂量组(L组)和高剂量组(H组),每组加只大鼠.肉毒毒素A预注射后7 d,在鼠背部建立以4个注射点为中心的创面模型,创面面积1 cm×1 cm.于术前及术后3、7、14 d,测量创面面积,免疫组织化学和Axioplan 2 Imaging图像分析软件检测多聚甲醛灌注后创面P物质、降钙素基因相关肽以及创

  13. The Study of Protection and Mechanism Effect of CJY Flavanoid on the Beta-amy-loid Peptide 25-35-induced Injury in PC12%黄酮类化合物对 Aβ25-35介导的 PC12细胞损伤的保护及机制研究

    Institute of Scientific and Technical Information of China (English)

    樊茹

    2016-01-01

    目的:探讨黄酮类化合物(CJY)对β-淀粉样蛋白25-35(Aβ25-35)介导的 PC12细胞(大鼠嗜铬细胞瘤细胞)氧化损伤的保护作用及其可能机制。方法:对 PC12细胞采用不同浓度的 Aβ25-35进行损伤,MTT 法测定PC12细胞的损伤率和存活率;采用 SOD 试剂盒检测 Aβ25-35对 PC12细胞的氧化损伤;使用 DCFH-DA 结合活细胞高内涵成像系统检测细胞内 ROS 的水平。结果:经终浓度为10μM的 Aβ25-35对 PC12细胞损伤后,可降低细胞的存活率,而浓度为5μM,10μM,50μM的 CJY 呈浓度依赖性地提高 PC12细胞的存活率,并明显改善细胞形态。Aβ25-35可触发细胞内的氧化应激反应,造成细胞氧化损伤,提高细胞内 ROS 水平,降低细胞内 SOD 的活性;CJY 则降低细胞内 ROS 水平,升高 SOD 的活性,具有明显的抗氧化损伤作用。结论:通过离体实验证明黄酮类化合物CJY 对 Aβ25-35诱导的 PC12细胞损伤有保护作用,为进一步研究黄酮类化合物在阿尔茨海默病中的应用提供实验依据。%Objective:To explore the the protective effects and the potential mechanism of CJY flavanoids on inju-ries induced by the beta-amyloid peptide25-35( Aβ25-35 )in rat pheochromocytoma cells( PC12 cells). Methods:The Aβ25-35 with different concentrations were used to cause injuries in PC12 cells by the same way. The damage and survival rate of PC12 cells were detected by MTT as well as Oxidative damage by SOD and the content level of ROS in cells by DCFH-DA combined with living cells high content imaging system. Results:The injuries induced by the Aβ25-35 with the concentration of 10 μM resulted in the significant decrease of the survival rate of PC12 cells. CJY flavonoids(concentra-tions:5 μM,10 μM,50 μM)could markedly improve damage cells form and the survival rate of PC12 cells,which was dose-dependent. The oxidative stress in cells could be triggered by the Aβ25

  14. Biomimetic peptide nanosensors.

    Science.gov (United States)

    Cui, Yue; Kim, Sang N; Naik, Rajesh R; McAlpine, Michael C

    2012-05-15

    The development of a miniaturized sensing platform tailored for sensitive and selective detection of a variety of biochemical analytes could offer transformative fundamental and technological opportunities. Due to their high surface-to-volume ratios, nanoscale materials are extremely sensitive sensors. Likewise, peptides represent robust substrates for selective recognition due to the potential for broad chemical diversity within their relatively compact size. Here we explore the possibilities of linking peptides to nanosensors for the selective detection of biochemical targets. Such systems raise a number of interesting fundamental challenges: What are the peptide sequences, and how can rational design be used to derive selective binders? What nanomaterials should be used, and what are some strategies for assembling hybrid nanosensors? What role does molecular modeling play in elucidating response mechanisms? What is the resulting performance of these sensors, in terms of sensitivity, selectivity, and response time? What are some potential applications? This Account will highlight our early attempts to address these research challenges. Specifically, we use natural peptide sequences or sequences identified from phage display as capture elements. The sensors are based on a variety of nanomaterials including nanowires, graphene, and carbon nanotubes. We couple peptides to the nanomaterial surfaces via traditional surface functionalization methods or self-assembly. Molecular modeling provides detailed insights into the hybrid nanostructure, as well as the sensor detection mechanisms. The peptide nanosensors can distinguish chemically camouflaged mixtures of vapors and detect chemical warfare agents with sensitivities as low as parts-per-billion levels. Finally, we anticipate future uses of this technology in biomedicine: for example, devices based on these sensors could detect disease from the molecular components in human breath. Overall, these results provide a

  15. Dicyclopropylmethyl peptide backbone protectant.

    Science.gov (United States)

    Carpino, Louis A; Nasr, Khaled; Abdel-Maksoud, Adel Ali; El-Faham, Ayman; Ionescu, Dumitru; Henklein, Peter; Wenschuh, Holger; Beyermann, Michael; Krause, Eberhard; Bienert, Michael

    2009-08-20

    The N-dicyclopropylmethyl (Dcpm) residue, introduced into amino acids via reaction of dicyclopropylmethanimine hydrochloride with an amino acid ester followed by sodium cyanoborohydride or triacetoxyborohydride reduction, can be used as an amide bond protectant for peptide synthesis. Examples which demonstrate the amelioration of aggregation effects include syntheses of the alanine decapeptide and the prion peptide (106-126). Avoidance of cyclization to the aminosuccinimide followed substitution of Fmoc-(Dcpm)Gly-OH for Fmoc-Gly-OH in the assembly of sequences containing the sensitive Asp-Gly unit.

  16. Invertebrate FMRFamide related peptides.

    Science.gov (United States)

    Krajniak, Kevin G

    2013-06-01

    In 1977 the neuropeptide FMRFamide was isolated from the clam, Macrocallista nimbosa. Since then several hundred FMRFamide-related peptides (FaRPs) have been isolated from invertebrate animals. Precursors to the FaRPs likely arose in the cnidarians. With the transition to a bilateral body plan FaRPs became a fixture in the invertebrate phyla. They have come to play a critical role as neurotransmitters, neuromodulators, and neurohormones. FaRPs regulate a variety of body functions including, feeding, digestion, circulation, reproduction, movement. The evolution of the molecular form and function of these omnipresent peptides will be considered.

  17. Beta-thalassemia.

    Science.gov (United States)

    Galanello, Renzo; Origa, Raffaella

    2010-05-21

    Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC) transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis). Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely, deletions in the beta

  18. Beta-thalassemia

    Directory of Open Access Journals (Sweden)

    Origa Raffaella

    2010-05-01

    Full Text Available Abstract Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands, dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes, gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely

  19. An expanded set of amino acid analogs for the ribosomal translation of unnatural peptides.

    Directory of Open Access Journals (Sweden)

    Matthew C T Hartman

    Full Text Available BACKGROUND: The application of in vitro translation to the synthesis of unnatural peptides may allow the production of extremely large libraries of highly modified peptides, which are a potential source of lead compounds in the search for new pharmaceutical agents. The specificity of the translation apparatus, however, limits the diversity of unnatural amino acids that can be incorporated into peptides by ribosomal translation. We have previously shown that over 90 unnatural amino acids can be enzymatically loaded onto tRNA. METHODOLOGY/PRINCIPAL FINDINGS: We have now used a competition assay to assess the efficiency of tRNA-aminoacylation of these analogs. We have also used a series of peptide translation assays to measure the efficiency with which these analogs are incorporated into peptides. The translation apparatus tolerates most side chain derivatives, a few alpha,alpha disubstituted, N-methyl and alpha-hydroxy derivatives, but no beta-amino acids. We show that over 50 unnatural amino acids can be incorporated into peptides by ribosomal translation. Using a set of analogs that are efficiently charged and translated we were able to prepare individual peptides containing up to 13 different unnatural amino acids. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that a diverse array of unnatural building blocks can be translationally incorporated into peptides. These building blocks provide new opportunities for in vitro selections with highly modified drug-like peptides.

  20. Characterization of a new beta-lactamase gene from isolates of Vibrio spp. in Korea.

    Science.gov (United States)

    Jun, Lyu Jin; Kim, Jae Hoon; Jin, Ji Woong; Jeong, Hyun Do

    2012-04-01

    PCR was performed to analyze the beta-lactamase genes carried by ampicillin-resistant Vibrio spp. strains isolated from marine environments in Korea between 2006 and 2009. All 36 strains tested showed negative results in PCR with the primers designed from the nucleotide sequences of various known beta-lactamase genes. This prompted us to screen new beta-lactamase genes. A novel beta-lactamase gene was cloned from Vibrio alginolyticus KV3 isolated from the aquaculture water of Geoje Island of Korea. The determined nucleotide sequence (VAK-3 beta-lactamase) revealed an open reading frame (ORF) of 852 bp, encoding a protein of 283 amino acids (aa), which displayed low homology to any other beta-lactamase genes reported in public databases. The deduced 283 aa sequence of VAK-3, consisting of a 19 aa signal peptide and a 264 aa mature protein, contained highly conserved peptide segments specific to class A beta-lactamases including the specific amino acid residues STFK (62-65), SDN (122-124), E (158), and RTG (226-228). Results from PCR performed with primers specific to the VAK-3 beta-lactamase gene identified 3 of the 36 isolated strains as V. alginolyticus, Vibrio cholerae, and Photobacterium damselae subsp. damselae, indicating the utilization of various beta-lactamase genes including unidentified ones in ampicillin-resistant Vibrio spp. strains from the marine environment. In a mating experiment, none of the isolates transfered the VAK-3 beta-lactamase gene to the Escherichia coli recipient. This lack of mobility, and the presence of a chromosomal acyl-CoA flanking sequence upstream of the VAK-3 beta- lactamase gene, led to the assumption that the location of this new beta-lactamase gene was in the chromosome, rather than the mobile plasmid. Antibiotic susceptibility of VAK-3 beta-lactamase was indicated by elevated levels of resistance to penicillins, but not to cephalosporins in the wild type and E. coli harboring recombinant plasmid pKV-3, compared with those of

  1. Coroutine Sequencing in BETA

    DEFF Research Database (Denmark)

    Kristensen, Bent Bruun; Madsen, Ole Lehrmann; Møller-Pedersen, Birger;

    In object-oriented programming, a program execution is viewed as a physical model of some real or imaginary part of the world. A language supporting object-oriented programming must therefore contain comprehensive facilities for modeling phenomena and concepts form the application domain. Many ap...... applications in the real world consist of objects carrying out sequential processes. Coroutines may be used for modeling objects that alternate between a number of sequential processes. The authors describe coroutines in BETA...

  2. Beta decay for pedestrians

    CERN Document Server

    Lipkin, Harry Jeannot

    1962-01-01

    The ""pedestrian approach"" was developed to describe some essentially simple experimental results and their theoretical implications in plain language. In this graduate-level text, Harry J. Lipkin presents simply, but without oversimplification, the aspects of beta decay that can be understood without reference to the formal theory; that is, the reactions that follow directly from conservation laws and elementary quantum mechanics.The pedestrian treatment is neither a substitute for a complete treatment nor a watered-down version.

  3. Integration of BETA with Eclipse

    DEFF Research Database (Denmark)

    Andersen, Peter; Madsen, Ole Lehrmann; Enevoldsen, Mads Brøgger

    2004-01-01

    This paper presents language interoperability issues appearing in order to implement support for the BETA language in the Java-based Eclipse integrated development environment. One of the challenges is to implement plug-ins in BETA and be able to load them in Eclipse. In order to do this, some form...... of language interoperability between Java and BETA is required. The first approach is to use the Java Native Interface and use C to bridge between Java and BETA. This results in a workable, but complicated solution. The second approach is to let the BETA compiler generate Java class files. With this approach...... it is possible to implement plug-ins in BETA and even inherit from Java classes. In the paper the two approaches are described together with part of the mapping from BETA to Java class files. http://www.sciencedirect.com/science/journal/15710661...

  4. Regulation of beta cell replication

    DEFF Research Database (Denmark)

    Lee, Ying C; Nielsen, Jens Høiriis

    2008-01-01

    Beta cell mass, at any given time, is governed by cell differentiation, neogenesis, increased or decreased cell size (cell hypertrophy or atrophy), cell death (apoptosis), and beta cell proliferation. Nutrients, hormones and growth factors coupled with their signalling intermediates have been...... suggested to play a role in beta cell mass regulation. In addition, genetic mouse model studies have indicated that cyclins and cyclin-dependent kinases that determine cell cycle progression are involved in beta cell replication, and more recently, menin in association with cyclin-dependent kinase...... inhibitors has been demonstrated to be important in beta cell growth. In this review, we consider and highlight some aspects of cell cycle regulation in relation to beta cell replication. The role of cell cycle regulation in beta cell replication is mostly from studies in rodent models, but whether...

  5. Beta cell adaptation in pregnancy

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    2016-01-01

    Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin...... and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades......, but the mechanisms involved are still not clarified. In this review the information obtained in previous studies is recapitulated together with some of the current attempts to resolve the controversy in the field: identification of the putative progenitor cells, identification of the factors involved...

  6. LHCb: $2\\beta_s$ measurement at LHCb

    CERN Multimedia

    Conti, G

    2009-01-01

    A measurement of $2\\beta_s$, the phase of the $B_s-\\bar{B_s}$ oscillation amplitude with respect to that of the ${\\rm b} \\rightarrow {\\rm c^{+}}{\\rm W^{-}}$ tree decay amplitude, is one of the key goals of the LHCb experiment with first data. In the Standard Model (SM), $2\\beta_s$ is predicted to be $0.0360^{+0.0020}_{-0.0016} \\rm rad$. The current constraints from the Tevatron are: $2\\beta_{s}\\in[0.32 ; 2.82]$ at 68$\\%$CL from the CDF experiment and $2\\beta_{s}=0.57^{+0.24}_{-0.30}$ from the D$\\oslash$ experiment. Although the statistical uncertainties are large, these results hint at the possible contribution of New Physics in the $B_s-\\bar{B_s}$ box diagram. After one year of data taking at LHCb at an average luminosity of $\\mathcal{L}\\sim2\\cdot10^{32}\\rm cm^{-2} \\rm s^{-1}$ (integrated luminosity $\\mathcal{L}_{\\rm int}\\sim 2 \\rm fb^{-1}$), the expected statistical uncertainty on the measurement is $\\sigma(2\\beta_s)\\simeq 0.03$. This uncertainty is similar to the $2\\beta_s$ value predicted by the SM.

  7. Radiolabeled antibodies and RGD-peptides for the treatment of ovarian cancer

    NARCIS (Netherlands)

    Janssen, M.L.H.

    2004-01-01

    In this thesis, preclinical studies on new treatment modalities for ovarian cancer are descibed, applying radiolabeled antibodies and radiolabeled RGD-peptides. In chapter 2 a study is described comparing the therapeutic efficacy of the antibody HMFG1 radiolabeled with several beta-emitting radionuc

  8. alpha 11beta 1 integrin recognizes the GFOGER sequence in interstitial collagens.

    Science.gov (United States)

    Zhang, Wan-Ming; Kapyla, Jarmo; Puranen, J Santeri; Knight, C Graham; Tiger, Carl-Fredrik; Pentikainen, Olli T; Johnson, Mark S; Farndale, Richard W; Heino, Jyrki; Gullberg, Donald

    2003-02-28

    The integrins alpha(1)beta(1), alpha(2)beta(1), alpha(10)beta(1), and alpha(11)beta(1) are referred to as a collagen receptor subgroup of the integrin family. Recently, both alpha(1)beta(1) and alpha(2)beta(1) integrins have been shown to recognize triple-helical GFOGER (where single letter amino acid nomenclature is used, O = hydroxyproline) or GFOGER-like motifs found in collagens, despite their distinct binding specificity for various collagen subtypes. In the present study we have investigated the mechanism whereby the latest member in the integrin family, alpha(11)beta(1), recognizes collagens using C2C12 cells transfected with alpha(11) cDNA and the bacterially expressed recombinant alpha(11) I domain. The ligand binding properties of alpha(11)beta(1) were compared with those of alpha(2)beta(1). Mg(2+)-dependent alpha(11)beta(1) binding to type I collagen required micromolar Ca(2+) but was inhibited by 1 mm Ca(2+), whereas alpha(2)beta(1)-mediated binding was refractory to millimolar concentrations of Ca(2+). The bacterially expressed recombinant alpha(11) I domain preference for fibrillar collagens over collagens IV and VI was the same as the alpha(2) I domain. Despite the difference in Ca(2+) sensitivity, alpha(11)beta(1)-expressing cells and the alpha(11) I domain bound to helical GFOGER sequences in a manner similar to alpha(2)beta(1)-expressing cells and the alpha(2) I domain. Modeling of the alpha I domain-collagen peptide complexes could partially explain the observed preference of different I domains for certain GFOGER sequence variations. In summary, our data indicate that the GFOGER sequence in fibrillar collagens is a common recognition motif used by alpha(1)beta(1), alpha(2)beta(1), and also alpha(11)beta(1) integrins. Although alpha(10) and alpha(11) chains show the highest sequence identity, alpha(2) and alpha(11) are more similar with regard to collagen specificity. Future studies will reveal whether alpha(2)beta(1) and alpha(11)beta(1

  9. Natriuretic peptides and cerebral hemodynamics

    DEFF Research Database (Denmark)

    Guo, Song; Barringer, Filippa; Zois, Nora Elisabeth;

    2014-01-01

    Natriuretic peptides have emerged as important diagnostic and prognostic tools for cardiovascular disease. Plasma measurement of the bioactive peptides as well as precursor-derived fragments is a sensitive tool in assessing heart failure. In heart failure, the peptides are used as treatment...

  10. Hydrogels constructed via self-assembly of beta-hairpin molecules

    Science.gov (United States)

    Ozbas, Bulent

    There is a recent and growing interest in hydrogel materials that are formed via peptide self-assembly for tissue engineering applications. Peptide based materials are excellent candidates for diverse applications in biomedical field due to their responsive behavior and complex self-assembled structures. However, there is very limited information on the self-assembly and resultant network and mechanical properties of these types of hydrogels. The main goal of this dissertation is to investigate the self-assembly mechanism and viscoelastic properties of hydrogels that can be altered by changing solution conditions as well as the primary structure of the peptide. These hydrogels are formed via intramolecular folding and consequent self-assembly of 20 amino acid long beta-hairpin peptide molecules (Max1). The peptide molecules are locally amphiphilic with two linear strands of alternating hydrophobic valine and hydrophilic lysine amino acids connected with a Dproline-LProline turn sequence. Circular dichroism and FTIR spectroscopy show that at physiological conditions peptides are unfolded in the absence of salt. By raising the ionic strength of the solution electrostatic interactions between charged lysines are screened and the peptide arms are forced into a beta-sheet secondary structure stabilized by the turn sequence. These folded molecules intermolecularly assemble via hydrophobic collapse and hydrogen bonding into a three dimensional network. Folding and self-assembly of these molecules can also be triggered by increasing temperature and/or pH of the peptide solution. In addition, the random-coil to beta-sheet transition of the beta-hairpin peptides is pH and, with proper changes in the peptide sequence, thermally reversible. Rheological measurements demonstrate that the resultant supramolecular structure forms an elastic material, whose structure, and thus modulus, can be tuned by magnitude of the stimulus. Hydrogels recover their initial viscoelastic

  11. Descriptors for antimicrobial peptides

    DEFF Research Database (Denmark)

    Jenssen, Håvard

    2011-01-01

    Introduction: A frightening increase in the number of isolated multidrug resistant bacterial strains linked to the decline in novel antimicrobial drugs entering the market is a great cause for concern. Cationic antimicrobial peptides (AMPs) have lately been introduced as a potential new class of ...

  12. Immunoreactivity for thymosin beta 4 and thymosin beta 10 in the adult rat oro-gastro-intestinal tract

    Directory of Open Access Journals (Sweden)

    S. Nemolato

    2013-05-01

    Full Text Available Thymosin beta 4 (Tβ4 and thymosin beta 10 (Tβ10 are two members of the β-thymosin family, involved in multiple cellular activities in different organs in multiple animal species. Here we report the expression pattern of Tβ4 and Tβ10 in rat tissues, in the gut and in annexed glands. The two peptide were differently expressed: Tβ4 was absent in salivary glands whereas Tβ10 was expressed in parotid and in submandibular glands. Tβ4 was mildly expressed in the tongue and in the oesophagus, where Tβ10 was absent. A similar expression was found in the stomach, ileum and colon mucosa. In pancreas Tβ4 reactivity was restricted to the Langerhans islet cells; Tβ4 was also detected in the exocrine cells. Both peptide were not expressed in liver cells. When the rat expression pattern in rat organs was compared to reactivity for Tβ4 and Tβ10 in humans, marked differences were found. Our data clearly indicate a species-specific expression of Tβ4 and Tβ10, characterized by the actual unpredictability of the expression of these peptides in different cells and tissues. The common high expression of Tβ4 in mast cells, both in humans and in rats, represents one of the few similarities between these two species.

  13. Immunoreactivity for Thymosin Beta 4 and Thymosin Beta 10 in the Adult Rat Oro-Gastro-Intestinal tract

    Science.gov (United States)

    Nemolato, S; Ekstrom, J.; Cabras, T.; Gerosa, C.; Fanni, D.; Di Felice, E.; Locci, A.; Messana, I.; Castagnola, M.; Faa, G.

    2013-01-01

    Thymosin beta 4 (Tβ4) and thymosin beta 10 (Tβ10) are two members of the β-thymosin family, involved in multiple cellular activities in different organs in multiple animal species. Here we report the expression pattern of Tβ4 and Tβ10 in rat tissues, in the gut and in annexed glands. The two peptide were differently expressed: Tβ4 was absent in salivary glands whereas Tβ10 was expressed in parotid and in submandibular glands. Tβ4 was mildly expressed in the tongue and in the esophagus, where Tβ10 was absent. A similar expression was found in the stomach, ileum and colon mucosa. In pancreas Tβ4 reactivity was restricted to the Langerhans islet cells; Tβ4 was also detected in the exocrine cells. Both peptide were not expressed in liver cells. When the rat expression pattern in rat organs was compared to reactivity for Tβ4 and Tβ10 in humans, marked differences were found. Our data clearly indicate a species-specific expression of Tβ4 and Tβ10, characterized by the actual unpredictability of the expression of these peptides in different cells and tissues. The common high expression of Tβ4 in mast cells, both in humans and in rats, represents one of the few similarities between these two species. PMID:23807296

  14. Radiolabeled peptides for diagnostic imaging and radiotherapy of tumors; Radiomarkierte Peptide zur bildgebenden Diagnostik und Radiotherapie von Tumoren

    Energy Technology Data Exchange (ETDEWEB)

    Friebe, M.; Bugaj, J.E.; Srinivasan, A.; Dinkelborg, L.M. [Research Lab. of Schering AG (Belgium)

    2005-03-01

    Radioactively labeled peptides are powerful tools for an individualized, patient based treatment of oncological diseases. The excellent targeting concomittant with the easy radiolabeling enable such fully synthetic molecules for patient selection (diagnosis) and internal irradiation (therapy). Peptides labeled with radiohalogenes as well as radiometals were used successfully for the diagnosis and therapy of numerous malignancies. The use of {sup 90}Y-DOTATOC and {sup 177}Lu-DOTATATE for the treatment of patients with neuroendocrine tumors, refrectory to chemotherapy, underline the potential of radiopeptides. {sup 99m}Tc-NeoTect registered, another somatostatin targeting peptide-radiometal conjugate, detects lung lesions with 97% sensitivity and > 70% specificity employing SPECT. Pre-clinical results of {sup 188}Re-NeoTide registered, the radiotherapeutic counterpart of {sup 99m}Tc-NeoTect registered, indicate significant tumor regression in lung tumor models. The {alpha}{sub v}{beta}{sub 3}-targeted detection of neoangiogenesis proves radiopeptides to be valuable tools for the diagnostic imaging of multiple tumor entities, since {alpha}{sub v}{beta}{sub 3}-receptors are overexpressed in a variety of tumors undergoing new blood-vessel formation. The application of ({sup 18}F)-Galacto-RGD, a high-affinity binder for {alpha}{sub v}{beta}{sub 3}-receptors, pinpoints the potential of peptides for tumor detection (Fig. 5) and staging. The successful use of {sup 99m}Tc-Demogastrin registered for detection of medullary thyroid carcinoma and its multiple metastases opens a new field in diagnosis and therapy of solid tumors. (orig.)

  15. Induction of peripheral tolerance with peptide-specific anergy in experimental autoimmune neuritis.

    Science.gov (United States)

    Gregorian, S K; Clark, L; Heber-Katz, E; Amento, E P; Rostami, A

    1993-09-01

    Neuritogenic T cells specific for SP-26, a synthetic peptide (residue 53-78) of myelin P2 protein that causes experimental autoimmune neuritis (EAN), use the same T cell receptor (TCR) V gene family (V beta 8) that can induce experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Tolerance to autoregulatory T cells may be induced in rats by intravenous (iv) administration of antigen-coupled splenocytes; however, the mechanisms that lead to altered immune reactivity are not well understood. Here we demonstrate that SP-26, when coupled to syngeneic spleen cells and administered iv, either before or after disease induction, markedly inhibited development and expression of clinical signs and histological changes of EAN. The induction of tolerance by this method was peptide-specific and MHC-restricted. We showed previously that T cells involved in EAN utilize the T cell antigen receptor V beta 8, whereas less than 5% of normal rat peripheral T cells express V beta 8. We have examined T lymphocytes from tolerized rats to determine the presence or absence of V beta 8(+)-bearing cells in order to determine the mechanism of tolerance. V beta 8 cells were undetectable by Northern blot analysis in the lymph nodes of unimmunized animals but easily detected in SP-26-primed and tolerized rats. In addition, spleen cells isolated from tolerized animals were anergic and failed to proliferate in response to SP-26, but retained responsiveness to IL-2 and Con A stimulation. Thus, the peptide-specific unresponsiveness that can be induced in rats with EAN, a T-cell-mediated process that is MHC-restricted and utilizes the T cell receptor V beta 8, occurs while V beta 8 transcripts remain readily detectable in spleen and lymph node cells. The detection of V beta 8-bearing T cells requires the development of antibodies specific for this rat surface protein. PMID:7690307

  16. Random length assortment of human and mouse T cell receptor for antigen alpha and beta chain CDR3.

    Science.gov (United States)

    Johnson, G; Wu, T T

    1999-10-01

    In view of the recently determined three-dimensional structures of complexes formed by the T cell receptor for antigen (TCR), the processed peptide and the MHC class I molecule, it is expected that the combined configuration formed by the third complementarity determining regions (CDR3) of TCR alpha and beta chains will be very restricted in size and shape due to the limited length variations of the processed peptides. Thus, the combined TCR alpha and beta chain CDR3 lengths should have a fairly narrow distribution. This feature can be due to the selective association of long alpha chain CDR3 with short beta chain CDR3 and vice versa or due to random assortment of alpha and beta chain CDR3 of even narrower length distribution. Based on existing translated amino acid sequence data, it has been found that the latter mechanism is responsible.

  17. IMPY, a potential {beta}-amyloid imaging probe for detection of prion deposits in scrapie-infected mice

    Energy Technology Data Exchange (ETDEWEB)

    Song, P.-J. [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Bernard, Serge [IFR135, F-37000 Tours (France); INRA, UR1282, IASP, 37380 Nouzilly (France)], E-mail: bernard@tours.inra.fr; Sarradin, Pierre [INRA, UR1282, IASP, 37380 Nouzilly (France); Vergote, Jackie [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Barc, Celine [INRA, UR1282, IASP, 37380 Nouzilly (France); Chalon, Sylvie [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France); Kung, M.-P.; Kung, Hank F. [Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Guilloteau, Denis [INSERM, U619, F-37000 Tours (France); Universite Francois-Rabelais, F-37000 Tours (France); IFR135, F-37000 Tours (France)

    2008-02-15

    Introduction: A potential single-photon emission computed tomography imaging agent for labeling of A{beta} plaques of Alzheimer's disease, IMPY (2-(4'-dimethylaminophenyl)-6-iodo-imidazo[1,2-a]pyridine), would be effective in detection of prion amyloid deposits in transmissible spongiform encephalopathies (TSEs). Methods: In vitro autoradiographic studies were carried out with [{sup 125}I]IMPY on brain sections from scrapie-infected mice and age-matched controls. Competition study was performed to evaluate the prion deposit binding specificity with nonradioactive IMPY. Results: Binding of [{sup 125}I]IMPY was observed in infected brain sections, while on age-matched control brain sections, there was no or very low labeling. Prion deposit binding was confirmed by histoblots with prion protein-specific monoclonal antibody 2D6. In the presence of nonradioactive IMPY, the binding of [{sup 125}I]IMPY was significantly inhibited in all regions studied. Conclusions: These findings indicate that IMPY can detect the prion deposits in vitro in scrapie-infected mice. Labeled with {sup 123}I, this ligand may be useful to quantitate prion deposit burdens in TSEs by in vivo imaging.

  18. Molecular self-assembly: Design, synthesis, and characterization of peptidic materials for bio- and nano-technologies

    Science.gov (United States)

    Lamm, Matthew S.

    The research presented in this dissertation focuses on the design, synthesis, and characterization of amphiphilic peptides capable of self-assembling into beta-sheet fibrils under specific aqueous solution conditions. The peptide design consists of two beta-sheet forming strands of alternating valine and lysine residues, flanking a central tetrapeptide sequence that contains a diproline. Depending on the chirality of the prolines the peptide can assume either an intramolecularly folded or an extended conformation in the self-assembled state. For the peptide where intramolecular folding is designed against, the self-assembled nanostructure was found to exhibit a unique, nontwisted laminated morphology. Experimental techniques including transmission electron microscopy, atomic force microscopy, circular dichroism spectroscopy, Fourier transform infra-red spectroscopy and x-ray diffraction were employed to characterize the self-assembled structure and kinetics. With the understanding of the self-assembly process gained from these first peptides, other peptide sequences were rationally designed to assemble with a desired nanostructure. For example, the effect of peptide strand length in conserving the laminated morphology and controlling the fibril height was investigated. In addition, other peptides were designed so as to affect the self-assembled nanostructure by enforcing a parallel versus anti-parallel beta-sheet or by disrupting the registry of laminating beta-sheet filaments. In some cases, the peptides assembled into structures predicted by the initial design while other peptides assembled into unexpected fibril morphologies. The major conclusions from the research on these peptides is that the diproline sequence plays an important role in disrupting the beta-strand twist thereby resulting in a nontwisted laminated morphology. However, when the flanking beta-strands become long enough, the effect of the diproline sequence becomes diminished and the fibrils do

  19. Biochemical functionalization of peptide nanotubes with phage displayed peptides

    Science.gov (United States)

    Swaminathan, Swathi; Cui, Yue

    2016-09-01

    The development of a general approach for the biochemical functionalization of peptide nanotubes (PNTs) could open up existing opportunities in both fundamental studies as well as a variety of applications. PNTs are spontaneously assembled organic nanostructures made from peptides. Phage display has emerged as a powerful approach for identifying selective peptide binding motifs. Here, we demonstrate for the first time the biochemical functionalization of PNTs via peptides identified from a phage display peptide library. The phage-displayed peptides are shown to recognize PNTs. These advances further allow for the development of bifunctional peptides for the capture of bacteria and the self-assembly of silver particles onto PNTs. We anticipate that these results could provide significant opportunities for using PNTs in both fundamental studies and practical applications, including sensors and biosensors nanoelectronics, energy storage devices, drug delivery, and tissue engineering.

  20. Biochemical functionalization of peptide nanotubes with phage displayed peptides.

    Science.gov (United States)

    Swaminathan, Swathi; Cui, Yue

    2016-09-01

    The development of a general approach for the biochemical functionalization of peptide nanotubes (PNTs) could open up existing opportunities in both fundamental studies as well as a variety of applications. PNTs are spontaneously assembled organic nanostructures made from peptides. Phage display has emerged as a powerful approach for identifying selective peptide binding motifs. Here, we demonstrate for the first time the biochemical functionalization of PNTs via peptides identified from a phage display peptide library. The phage-displayed peptides are shown to recognize PNTs. These advances further allow for the development of bifunctional peptides for the capture of bacteria and the self-assembly of silver particles onto PNTs. We anticipate that these results could provide significant opportunities for using PNTs in both fundamental studies and practical applications, including sensors and biosensors nanoelectronics, energy storage devices, drug delivery, and tissue engineering. PMID:27479451

  1. Molecular cloning of the first metazoan beta-1,3 glucanase from eggs of the sea urchin Strongylocentrotus purpuratus.

    OpenAIRE

    Bachman, E S; McClay, D R

    1996-01-01

    We report the molecular cloning of the first beta-1,3 glucanase from animal tissue. Three peptide sequences were obtained from beta-1,3 glucanase that had been purified from eggs of the sea urchin Strongylocentrotus purpuratus and the gene was cloned by PCR using oligonucleotides deduced from the peptide sequences. The full-length cDNA shows a predicted enzyme structure of 499 aa with a hydrophobic signal sequence. A 3.2-kb message is present in eggs, during early embryogenesis, and in adult ...

  2. Treatment of Alzheimer's Disease with Anti-Homocysteic Acid Antibody in 3xTg-AD Male Mice

    OpenAIRE

    Tohru Hasegawa; Nobuyuki Mikoda; Masashi Kitazawa; LaFerla, Frank M.

    2010-01-01

    Alzheimer's disease (AD) is an age-associated progressive neurodegenerative disorder with dementia, the exact pathogenic mechanisms of which remain unknown. We previously reported that homocysteic acid (HA) may be one of the pathological biomarkers in the brain with AD and that the increased levels of HA may induce the accumulation of intraneuronal amyloid-beta (Abeta) peptides. In this study, we further investigated the pathological role of HA in a mouse model of AD. Four-month-old prepathol...

  3. APP17肽调节胰岛素受体底物1在糖尿病小鼠脑内分布及对脑海马区神经元退行性变的作用%Effects of amyloid beta protein precursor 17 peptide on distribution of insulin receptor substrate-1 in brain and degeneration of neurons in hippocampus of diabetic mice

    Institute of Scientific and Technical Information of China (English)

    陆珊; 雷亚平; 崔艳君; 王蓬文; 盛树力

    2006-01-01

    BACKGROUND: In brain insulin does its work through the insulin receptor substrate (IRS). Amyloid beta protein precursor 17 (APP17) peptide has the neurotrophic function, which may improve diabetic encephalopathy resulted from insulin deficiency by affecting insulin receptor substrate.OBJECTIVE: The mouse diabetic model was produced to observe the effect of APP17 peptide on the distribution of IRS-1 in brain tissues.DESIGN: Randomized control animal experiment.SETTING: Staff Room of Pathology, College of Basic Medical Sciences,Capital University of Medical Sciences; Beijing Research Laboratory for Brain Aging of Xuanwu Hospital.MATERIALS: The experiment was performed in Staff Room of Pathology,College of Basic Medical Sciences, Capital University of Medical Sciences and Beijing Research Laboratory for Brain Aging of Xuanwu Hospital from September to October 2003. Totally 18 male kunming mice were employed,and randomly assigned into control group, diabetic group and APP17 peptide treatment group with 6 mice in each group.METHODS: ①The mice were subjected to intraperitoneal injection of streptozotocin (STZ, Sigma) by 200 mg/kg, and 3 days later, the tail blood was sampled to examine non-fasting blood glucose, and the blood glucose over 15 mmol/L was set as the criteria for successful diabetic model establishment. ②In APP17 + diabetes mellitus group, the mice received subcutaneous injection of 0.35 μg APP17 peptide once daily for 2 weeks. The mice in the normal control group were not interfered. ③Then brain was removed and crystat sections were prepared. Immunohistochemical staining was done for IRS-1 at four weeks after giving streptozotocin.MAIN OUTCOME MEASURES: Pattern and distribution of IRS-1 positive cells of mice in each group.RESULTS: Totally 18 mice were involved in the result analysis. ①In the brains of diabetic mice the IRS-1 immunohistochemical positive cells distributed at cortex, hippocampus, thalamus, hypothalamus and so on, while the positive

  4. 心肺复苏大鼠海马神经元磷脂酰肌醇-3-激酶、蛋白激酶B和磷酸化cAMP应答元件结合蛋白表达的变化及APP17肽的影响%The effect of beta-amyloid precursor protein peptide on the expressions of PDK, PKB, p-CREB in the neurons of hippocampal gyrus in rats after cardiopulmonary resuscitation

    Institute of Scientific and Technical Information of China (English)

    王晶; 路毅; 赵妍; 秦俭; 王蓉; 赵志炜

    2009-01-01

    Objective To explore the effects of beta-amyloid precursor protein (APP17) peptide on the changes in the expressions of phosphoinositide 3-kinase(PI3K), protein kinase B(PKB) and phosphorylation of cAMP response element binding protein (p-CREB) in the neurons of hippocampal gyms in rats after cardiopulmonary resuscitation. Method Twenty-one Wistar rats were randomly divided into three groups, namely the sham-operated control group, the resuscitation group and resuscitation with APP17 peptide-treated group. The rat model of asphyxial cardiac arrest was made by clamping the endotracheal tube and the standard external cardiopulmonary resuscitation ( CPR) was performed until the restoration of spontaneous circulation ( ROSC) observed.ROSC was defined by the appearance of normal QRS waves of electrocardiogram and mean artery pressure ( MAP)≥60 mmHg for more than 10 minutes. Rats of resuscitation group and control group received intravenous 0.9%NaCl, and the rats of the APP17 peptide group were treated with APP17 peptide(10μg·300 g~(-1), i. v.) after ROSC. Rats were sacrificed by decapitation after reperfusion 2 hours and then the cerebral hippocampal gyrus was immediately separated to detect PI3K, PKB and p-CREB by immunohistochemistry ( IHC) and Western-blot analysis. Statistical comparisons were made by one-way analysis of variance (ANOVA) . Results IHC showed that there was no significant difference in PDK positive cells between resuscitation group and control group (2.75 ±1.80 vs. 2.53 ± 1.53, P > 0.05) . The PDK obviously more increased in the APP17 peptide group than in resuscitation group(5.85 ± 2.83 vs. 2.75 ± 1.80, P < 0.01) .The counts of PKB and p-CREB positive cells were obviously lower in resuscitation group than those in control group (2.45 ± 1.36 vs. 5.22 ± 2.50, P < 0.05);(2.41 ± 1.11 vs. 8.31 ±3.02, P < 0.01 ). The PKB and p-CREB positive cells were significantly higher in the APP17 peptide group than in resuscitation group (9.66±4.32 vs. 2

  5. Radiolabelled peptides for oncological diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Laverman, Peter; Boerman, Otto C.; Oyen, Wim J.G. [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, Nijmegen (Netherlands); Sosabowski, Jane K. [Queen Mary University of London, Centre for Molecular Oncology, Barts Cancer Institute, London (United Kingdom)

    2012-02-15

    Radiolabelled receptor-binding peptides targeting receptors (over)expressed on tumour cells are widely under investigation for tumour diagnosis and therapy. The concept of using radiolabelled receptor-binding peptides to target receptor-expressing tissues in vivo has stimulated a large body of research in nuclear medicine. The {sup 111}In-labelled somatostatin analogue octreotide (OctreoScan trademark) is the most successful radiopeptide for tumour imaging, and was the first to be approved for diagnostic use. Based on the success of these studies, other receptor-targeting peptides such as cholecystokinin/gastrin analogues, glucagon-like peptide-1, bombesin (BN), chemokine receptor CXCR4 targeting peptides, and RGD peptides are currently under development or undergoing clinical trials. In this review, we discuss some of these peptides and their analogues, with regard to their potential for radionuclide imaging of tumours. (orig.)

  6. Xeroradiography in. beta. -thalassaemia

    Energy Technology Data Exchange (ETDEWEB)

    Scutellari, P.N.; Orzincolo, C.; Tamarozzi, R.

    1985-01-01

    Xeroradiographic investigations of the skull, hand, and elbow were performed on 27 patients with homozygous ..beta..-thalassaemia. The results were compared with plain radiographic examinations. Xeroradiography, because of its technical properties (i.e. edge contrast enhancement and wide latitude), was shown to demonstrate cortical thinning of long bones, swelling of the diploic space in the skull, and reticulated patterns in the elbow better than standard radiography. Moreover, the use of 'positive' mode imaging was shown to have advantages in the study of the skull and extremities.

  7. Orthogonally protected cyclo-beta-tetrapeptides as solid-supported scaffolds for the synthesis of glycoclusters.

    Science.gov (United States)

    Virta, Pasi; Karskela, Marika; Lönnberg, Harri

    2006-03-01

    Two novel peptide scaffolds, viz. cyclo[(N(alpha)-Alloc)Dpr-beta-Ala-(N(alpha)-Fmoc)Dpr-beta-Ala] (1) and cyclo[(N(alpha)-Alloc)Dpr-alpha-azido-beta-aminopropanoyl-(N(alpha)-Fmoc)Dpr-beta-Ala] (2), composed of orthogonally protected 2,3-diaminopropanoyl (Dpr) and beta-alanyl residues, have been described. Fmoc chemistry on a backbone amide linker derivatized resin has been used for the chain assembly. Selective removal of the 4-methyltrityl (Mtt) and 1-methyl-1-phenylethyl protections (PhiPr) exposes the beta-amino and carboxyl terminus, respectively, and on-resin cyclization then gives the desired orthogonally protected cyclo-beta-tetrapeptides (1 and 2). The alpha-amino groups, bearing the Fmoc and Alloc protections and the azide mask, allow stepwise orthogonal derivatization of these solid-supported cyclo-beta-tetrapeptide cores (1 and 2). This has been demonstrated by attachments of various sugar units [viz., acetyl- or toluoyl-protected carboxymethyl alpha-d-glycopyranosides (13-15) and methyl 6-O-(4-nitrophenoxycarbonyl)-alpha-d-glycopyranosides (22-24)] to obtain diverse di- and trivalent glycoclusters (33-42). Acidolytic release (TFA) from the support, followed by conventional NaOMe-catalyzed transesterification (33-40) or hydrazine-induced acyl substitution in DMF (41 and 42), gives the fully deprotected clusters (43-52) as final products.

  8. Targeting amyloid-degrading enzymes as therapeutic strategies in neurodegeneration.

    Science.gov (United States)

    Turner, Anthony J; Fisk, Lilia; Nalivaeva, Natalia N

    2004-12-01

    The levels of amyloid beta-peptides (Abeta) in the brain represent a dynamic equilibrium state as a result of their biosynthesis from the amyloid precursor protein (APP) by beta- and gamma-secretases, their degradation by a team of amyloid-degrading enzymes, their subsequent oligomerization, and deposition into senile plaques. While most therapeutic attention has focused on developing inhibitors of secretases to prevent Abeta formation, enhancing the rate of Abeta degradation represents an alternative and viable strategy. Current evidence both in vivo and in vitro suggests that there are three major players in amyloid turnover: neprilysin, endothelin converting enzyme(s), and insulin-degrading enzyme, all of which are zinc metallopeptidases. Other proteases have also been implicated in amyloid metabolism, including angiotensin-converting enzyme, and plasmin but for these the evidence is less compelling. Neprilysin and endothelin converting enzyme(s) are homologous membrane proteins of the M13 peptidase family, which normally play roles in the biosynthesis and/or metabolism of regulatory peptides. Insulin-degrading enzyme is structurally and mechanistically distinct. The regional, cellular, and subcellular localizations of these enzymes differ, providing an efficient and diverse mechanism for protecting the brain against the normal accumulation of toxic Abeta peptides. Reduction in expression levels of some of these proteases following insults (e.g., hypoxia and ischemia) or aging might predispose to the development of Alzheimer's disease. Conversely, enhancement of their levels by gene delivery or pharmacological means could be neuroprotective. Even a relatively small enhancement of Abeta metabolism could slow the inexorable progression of the disease. The relative merits of targeting these enzymes for the treatment of Alzheimer's disease will be reviewed and possible side-effects of enhancing their activity evaluated.

  9. Isolation and characterization of a cDNA from Cuphea lanceolata encoding a beta-ketoacyl-ACP reductase.

    Science.gov (United States)

    Klein, B; Pawlowski, K; Höricke-Grandpierre, C; Schell, J; Töpfer, R

    1992-05-01

    A cDNA encoding beta-ketoacyl-ACP reductase (EC 1.1.1.100), an integral part of the fatty acid synthase type II, was cloned from Cuphea lanceolata. This cDNA of 1276 bp codes for a polypeptide of 320 amino acids with 63 N-terminal residues presumably representing a transit peptide and 257 residues corresponding to the mature protein of 27 kDa. The encoded protein shows strong homology with the amino-terminal sequence and two tryptic peptides from avocado mesocarp beta-ketoacyl-ACP reductase, and its total amino acid composition is highly similar to those of the beta-ketoacyl-ACP reductases of avocado and spinach. Amino acid sequence homologies to polyketide synthase, beta-ketoreductases and short-chain alcohol dehydrogenases are discussed. An engineered fusion protein lacking most of the transit peptide, which was produced in Escherichia coli, was isolated and proved to possess beta-ketoacyl-ACP reductase activity. Hybridization studies revealed that in C. lanceolata beta-ketoacyl-ACP reductase is encoded by a small family of at least two genes and that members of this family are expressed in roots, leaves, flowers and seeds.

  10. Antifungal peptides, a heat shock protein-like peptide, and a serine-threonine kinase-like protein from Ceylon spinach seeds.

    Science.gov (United States)

    Wang, Hexiang; Ng, Tzi Bun

    2004-07-01

    Two antifungal peptides (designated alpha- and beta-basrubrins) with molecular masses of 4-5 kDa and distinct N-terminal sequences, and a peptide and a protein with N-terminal sequences resembling heat shock protein (hsp) and serine-threonine kinase, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure entailed saline extraction, (NH4)2SO4 precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, and FPLC-gel filtration on a Superdex peptide column. alpha- and beta-basrubrins inhibited mycelial growth in Botrytis cirerea with an IC50 value of 7.5 and 14.7 microM, respectively, Mycosphaerella arachidicola with an IC50 of 12.4 and 6.9 microM, and Fusarium oxysporum with an IC50 of 5.8 and 6.2 microM. Neither alpha-basrubrin nor beta-basrubin exhibited DNase, RNase, lectin or protease activity, indicating that their antifungal action is not due to these activities. HIV-1 reverse transcriptase was inhibited by alpha- and beta-basrubrins with an IC50 of 246 and 370 microM, respectively. Translation in rabbit reticulocyte lysate was inhibited by alpha- and beta-basrubrins with an IC50 of 400 and 100 nM. The heat shock protein-like peptide and serine-threonine kinase-like protein exhibited a molecular mass of 3 and 30 kDa, respectively. They inhibited neither translation in a rabbit reticulocyte system at concentrations up to 50 microM nor HIV-1 reverse transcriptase activity at concentrations up to 400 microM. They did not exert antifungal activity toward B. cinerea, M. arachidicola, and F. oxysporum when tested up to 16 microg. None of the aforementioned proteins demonstrated DNase, RNase, protease or lectin activity. PMID:15245882

  11. Double beta decay: present status

    OpenAIRE

    Barabash, A. S.

    2008-01-01

    The present status of double beta decay experiments (including the search for $2\\beta^{+}$, EC$\\beta^{+}$ and ECEC processes) are reviewed. The results of the most sensitive experiments are discussed. Average and recommended half-life values for two-neutrino double beta decay are presented. Conservative upper limits on effective Majorana neutrino mass and the coupling constant of the Majoron to the neutrino are established as $ < 0.75$ eV and $ < 1.9 \\cdot 10^{-4}$, respectively. Proposals fo...

  12. Simultaneous beta and gamma spectroscopy

    Science.gov (United States)

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  13. Antimicrobial Peptides (AMPs

    Directory of Open Access Journals (Sweden)

    Mehrzad Sadredinamin

    2016-04-01

    Full Text Available Antimicrobial peptides (AMPs are extensive group of molecules that produced by variety tissues of invertebrate, plants, and animal species which play an important role in their immunity response. AMPs have different classifications such as; biosynthetic machines, biological sources, biological functions, molecular properties, covalent bonding patterns, three dimensional structures, and molecular targets.These molecules have multidimensional properties including antimicrobial activity, antiviral activity, antifungal activity, anti-parasite activity, biofilm control, antitumor activity, mitogens activity and linking innate to adaptive immunity that making them promising agents for therapeutic drugs. In spite of this advantage of AMPs, their clinical developments have some limitation for commercial development. But some of AMPs are under clinical trials for the therapeutic purpose such as diabetic foot ulcers, different bacterial infections and tissue damage. In this review, we emphasized on the source, structure, multidimensional properties, limitation and therapeutic applications of various antimicrobial peptides.

  14. Scintillator based beta batteries

    Science.gov (United States)

    Rensing, Noa M.; Tiernan, Timothy C.; Shirwadkar, Urmila; O'Dougherty, Patrick; Freed, Sara; Hawrami, Rastgo; Squillante, Michael R.

    2013-05-01

    Some long-term, remote applications do not have access to conventional harvestable energy in the form of solar radiation (or other ambient light), wind, environmental vibration, or wave motion. Radiation Monitoring Devices, Inc. (RMD) is carrying out research to address the most challenging applications that need power for many months or years and which have undependable or no access to environmental energy. Radioisotopes are an attractive candidate for this energy source, as they can offer a very high energy density combined with a long lifetime. Both large scale nuclear power plants and radiothermal generators are based on converting nuclear energy to heat, but do not scale well to small sizes. Furthermore, thermo-mechanical power plants depend on moving parts, and RTG's suffer from low efficiency. To address the need for compact nuclear power devices, RMD is developing a novel beta battery, in which the beta emissions from a radioisotope are converted to visible light in a scintillator and then the visible light is converted to electrical power in a photodiode. By incorporating 90Sr into the scintillator SrI2 and coupling the material to a wavelength-matched solar cell, we will create a scalable, compact power source capable of supplying milliwatts to several watts of power over a period of up to 30 years. We will present the latest results of radiation damage studies and materials processing development efforts, and discuss how these factors interact to set the operating life and energy density of the device.

  15. Peptide nanofibers modified with a protein by using designed anchor molecules bearing hydrophobic and functional moieties.

    Science.gov (United States)

    Miyachi, Ayaka; Takahashi, Tsuyoshi; Matsumura, Sachiko; Mihara, Hisakazu

    2010-06-11

    Self-assembly of peptides and proteins is a key feature of biological functions. Short amphiphilic peptides designed with a beta-sheet structure can form sophisticated nanofiber structures, and the fibers are available as nanomaterials for arranging biomolecules. Peptide FI (H-PKFKIIEFEP-OH) self-assembles into nanofibers with a coiled fine structure, as reported in our previous work. We have constructed anchor molecules that have both a binding moiety for the fiber structure and a functional unit capable of capturing target molecules, with the purpose of arranging proteins on the designed peptide nanofibers. Designed anchors containing an alkyl chain as a binding unit and biotin as a functional moiety were found to bind to peptide fibers FI and F2i (H-ALEAKFAAFEAKLA-NH(2)). The surface-exposed biotin moiety on the fibers could capture an anti-biotin antibody. Moreover, hydrophobic dipeptide anchor units composed of iminodiacetate connected to Phe-Phe or Ile-Ile and a peptide composed of six histidine residues connected to biotin could also connect FI peptide fibers to the anti-biotin antibody through the chelation of Ni(2+) ions. This strategy of using designed anchors opens a novel approach to constructing nanoscale protein arrays on peptide nanomaterials. PMID:20419712

  16. Tuning peptide amphiphile supramolecular structure for biomedical applications

    Science.gov (United States)

    Pashuck, Eugene Thomas, III

    The use of biomaterials in regenerative medicine has been an active area of research for more than a decade. Peptide amphiphiles, which are short peptide sequences coupled to alkyl tails, have been studied in the Stupp group since the beginning of the decade and been used for a variety of biomedical applications. Most of the work has focused on the bioactive epitopes places on the periphery of the PA molecules, but the interior amino acids, known as the beta-sheet region, give the PA nanofiber gel much of its mechanical strength. To study the important parameters in the beta-sheet region, six PA molecules were constructed to determine the influence of beta-sheet length and order of the amino acids in the beta-sheet. It was found that having beta-sheet forming amino acids near the center of the fiber improves PA gel stiffness, and that having extra amino acids that have preferences for other secondary structures, like alpha-helix decreased the gels stiffness. Using FTIR and circular dichroism it was found that the mechanical properties are influenced by the amount of twist in the beta-sheet, and PAs that have more twisted beta-sheets form weaker gels. The effect amino acid properties have on peptide amphiphile self-assembly where studied by synthesizining molecules with varying side group size and hydrophobicity. It was found that smaller amino acids lead to stiffer gels and when two amino acids had the same size the amino acid with the larger beta-sheet propensity lead to a stiffer gel. Furthermore, small changes in peptide structure were found to lead to big changes in nanostructure, as leucine and isoleucine, which have the same size but slightly different structures, form flat ribbons and cylindrical nanofibers, respectively. Phenylalanine and alanine were studied more indepth because they represent the effects of adding an aromatic group to amino acids in the beta-sheet regon. These phenylalanine PAs formed short, twisted ribbons when freshly dissolved in water

  17. Beta section Beta: biogeographical patterns of variation and taxonomy.

    NARCIS (Netherlands)

    Letschert, J.P.W.

    1993-01-01

    In Chapter 1 an account is given of the historical subdivision of the genus Beta and its sections, and the relations of the sections are discussed. Emphasis is given to the taxonomic treatment of wild section Beta by various authors. The Linnaean names B. vulgaris L. and B. maritima L. are lectotypi

  18. Reaction of the hydrated electron with amino acids, peptides, and proteins in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Faraggi, M. (Ohio State Univ., Columbus); Bettelheim, A.

    1977-08-01

    The reaction rate constants of e/sup -//sub aq/ with glycyl-histidine (Gly-His) and ..beta..-alanylhistidine (Carnosine, ..beta..-Ala-His) were determined and compared to those of ..beta..-alanylalanine (..beta..-Ala-Ala), alanyl-alanine ((Ala)/sub 2/), and histidine (His). The rate constants were found to be pH dependent. Below the pK value of the imidazole ring, the rate constants of the histidyl peptides are similar to that of His. This indicates that the main site of the e/sup -//sub aq/ reaction is the protonated ring. Above this pK value the pH dependent rate constants were less in the His amino acids than in the His peptides. This difference was attributed to the presence of the carbonyl grup in the peptides. This group, which is known to react quite rapidly with e/sup -//sub aq/, exhibits its presence when the imidazole ring loses its reactivity after deprotonation. The difference in reactivity toward e/sup -//sub aq/ between the ..cap alpha.. and ..beta.. His peptides is explained by the relative position of the protonated amino groups with respect to the carbonyl groups. A similar difference was also found in (Ala)/sub 2/ and ..beta..-Ala-Ala. The transient absorption spectra resulting from the reaction of e/sup -//sub aq/ with the His peptides were recorded and examined with respect to peptide concentration and pH dependence. Here again, at pH values below the pK of the imidazole, the transient absorption spectra are similar to that of histidine. In alkaline solutions, however, proper experimental conditions could be attained only for Gly-His. In His and ..beta..-Ala-His the interference of the OH radical reaction was observed. In Gly/sup -/His it was found that the band characterizing the imidazole transient (lambda/sub max/ = 360 nm) disappears with a simultaneous appearance of a band at lambda/sub max/ similarly ordered 410 nm.

  19. Folic acid deficiency enhances abeta accumulation in APP/PS1 mice brain and decreases amyloid-associated miRNAs expression.

    Science.gov (United States)

    Liu, Huan; Tian, Tian; Qin, Shanchun; Li, Wen; Zhang, Xumei; Wang, Xuan; Gao, Yuxia; Huang, Guowei

    2015-12-01

    Recent efforts have revealed the microRNA (miRNA) pathways in the pathogenesis of Alzheimer's disease (AD). Epidemiological studies have revealed an association between folic acid deficiency and AD risk. However, the effects of folic acid deficiency on miRNA expression in AD animals have not been observed. We aimed to find if folic acid deficiency may