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Sample records for apolipoprotein-e forms dimers

  1. Apolipoprotein-E forms dimers in human frontal cortex and hippocampus

    Directory of Open Access Journals (Sweden)

    Halliday Glenda M

    2010-02-01

    Full Text Available Abstract Background Apolipoprotein-E (apoE plays important roles in neurobiology and the apoE4 isoform increases risk for Alzheimer's disease (AD. ApoE3 and apoE2 are known to form disulphide-linked dimers in plasma and cerebrospinal fluid whereas apoE4 cannot form these dimers as it lacks a cysteine residue. Previous in vitro research indicates dimerisation of apoE3 has a significant impact on its functions related to cholesterol homeostasis and amyloid-beta peptide degradation. The possible occurrence of apoE dimers in cortical tissues has not been examined and was therefore assessed. Human frontal cortex and hippocampus from control and AD post-mortem samples were homogenised and analysed for apoE by western blotting under both reducing and non-reducing conditions. Results In apoE3 homozygous samples, ~12% of apoE was present as a homodimer and ~2% was detected as a 43 kDa heterodimer. The level of dimerisation was not significantly different when control and AD samples were compared. As expected, these dimerised forms of apoE were not detected in apoE4 homozygous samples but were detected in apoE3/4 heterozygotes at a level approximately 60% lower than seen in the apoE3 homozygous samples. Similar apoE3 dimers were also detected in lysates of SK-N-SH neuroblastoma cells and in freshly prepared rabbit brain homogenates. The addition of the thiol trapping agent, iodoacetamide, to block reactive thiols during both human and rabbit brain sample homogenisation and processing did not reduce the amount of apoE homodimer recovered. These data indicate that the apoE dimers we detected in the human brain are not likely to be post-mortem artefacts. Conclusion The identification of disulphide-linked apoE dimers in human cortical and hippocampal tissues represents a distinct structural difference between the apoE3 and apoE4 isoforms that may have functional consequences.

  2. Clinical chemistry of common apolipoprotein E isoforms

    NARCIS (Netherlands)

    Brouwer, DAJ; vanDoormaal, JJ; Muskiet, FAJ

    1996-01-01

    Apolipoprotein E plays a central role in clearance of lipoprotein remnants by serving as a ligand for low-density lipoprotein and apolipoprotein E receptors. Three common alleles (apolipoprotein E(2), E(3) and E(4)) give rise to six phenotypes. Apolipoprotein E(3) is the ancestral form. Common

  3. Dimeric form of peroxynitrite

    Science.gov (United States)

    Simon, K. V.; Tulub, A. V.

    2009-07-01

    The (ONOO)- anion, known as peroxynitrite, is characterized by a singlet spin state. A new stable dimer form of peroxynitrite [NO-O2]- in the triplet state at distances close to r(O-N) ≈ 2.885 Å between oxygen in the O2 structure and nitrogen has been established within the quantum-chemical CASSCF approximation. The vibrational motion of the dimer is significantly anharmonic; for the 16O and 14N isotopes, the differences in the energies of two neighboring levels correspond to frequencies of about 70-30 cm-1. The triplet dimer structure retains stability in the case of interaction with water molecules. The activation barriers caused by rearrangement of the peroxynitrite structure into the ground state of the NO{3/-} anion with the symmetry D 3 h are found.

  4. Apolipoprotein E and familial longevity

    DEFF Research Database (Denmark)

    Schupf, Nicole; Barral, Sandra; Perls, Thomas

    2013-01-01

    Exceptional longevity is associated with substantial heritability. The ε4 allele in apolipoprotein E and the linked G allele in rs2075650 of TOMM40 have been associated with increased mortality and the ε2 allele with decreased mortality, although inconsistently. Offspring from long-lived families...

  5. Multiple system atrophy and apolipoprotein E.

    Science.gov (United States)

    Ogaki, Kotaro; Martens, Yuka A; Heckman, Michael G; Koga, Shunsuke; Labbé, Catherine; Lorenzo-Betancor, Oswaldo; Wernick, Anna I; Walton, Ronald L; Soto, Alexandra I; Vargas, Emily R; Nielsen, Henrietta M; Fujioka, Shinsuke; Kanekiyo, Takahisa; Uitti, Ryan J; van Gerpen, Jay A; Cheshire, William P; Wszolek, Zbigniew K; Low, Phillip A; Singer, Wolfgang; Dickson, Dennis W; Bu, Guojun; Ross, Owen A

    2018-02-14

    Dysregulation of the specialized lipid metabolism involved in myelin synthesis and maintenance by oligodendrocytes has been associated with the unique neuropathology of MSA. We hypothesized that apolipoprotein E, which is associated with neurodegeneration, may also play a role in the pathogenesis of MSA. This study evaluated genetic associations of Apolipoprotein E alleles with risk of MSA and α-synuclein pathology, and also examined whether apolipoprotein E isoforms differentially affect α-synuclein uptake in a oligodendrocyte cell. One hundred sixty-eight pathologically confirmed MSA patients, 89 clinically diagnosed MSA patients, and 1,277 control subjects were genotyped for Apolipoprotein E. Human oligodendrocyte cell lines were incubated with α-synuclein and recombinant human apolipoprotein E, with internalized α-synuclein imaged by confocal microscopy and cells analyzed by flow cytometry. No significant association with risk of MSA or was observed for either Apolipoprotein E ɛ2 or ɛ4. α-Synuclein burden was also not associated with Apolipoprotein E alleles in the pathologically confirmed patients. Interestingly, in our cell assays, apolipoprotein E ɛ4 significantly reduced α-synuclein uptake in the oligodendrocytic cell line. Despite differential effects of apolipoprotein E isoforms on α-synuclein uptake in a human oligodendrocytic cell, we did not observe a significant association at the Apolipoprotein E locus with risk of MSA or α-synuclein pathology. © 2018 International Parkinson and Movement Disorder Society. © 2018 International Parkinson and Movement Disorder Society.

  6. Apolipoprotein E and cardiovascular disease

    Directory of Open Access Journals (Sweden)

    Adriana Moreno Valladares

    2006-01-01

    Full Text Available Apolipoprotein E is a polymorphic glycoprotein who interacts with the lipoprotein receptors (LRP-Receptor Related Protein and the receptors for low density lipoproteins of (LDL receptors. When lipoproteins bring up the receptors begins lipids captation and degradation which allows cholesterol utilization, taking place an intracellular auto regulation. The three isoforms of greater importance: Apo E2, E3 and E4 are product of three alleles e2, e3, e4 of one only gene. This factor is related with the amount of lipoproteins that contains ApoE for E/B receptors. A low concentration of lipoproteins with ApoE can increase the activity of LDL receptors and consequently downward the circulating LDL. In the other hand particles with Apo E3 or Apo E4, can cause a downward regulation of LDL and in this way produces a LDL plasma elevation. Many studies in human populations have concluded that this polymorphism of apoE and the plasma variation of lipoproteins are associated with cardiovascular risk. Cardiovascular disease is the result of different interaction between factors which are genetic factor specially ApoE polymorphism e4 allelic of ApoE can explain, in some degree, the greater frequency of cardiovascular disease in those who carries it.

  7. Palmitoylated APP Forms Dimers, Cleaved by BACE1

    Science.gov (United States)

    Fenn, Rebecca H.; Barren, Cory; Tanzi, Rudolph E.; Kovacs, Dora M.

    2016-01-01

    A major rate-limiting step for Aβ generation and deposition in Alzheimer’s disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8–10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors. PMID:27875558

  8. Dimeric forms of cholinesterase in Sipunculus nudus.

    Science.gov (United States)

    Talesa, V; Principato, G B; Giovannini, E; Di Giovanni, M V; Rosi, G

    1993-07-15

    In developing a research on the cholinesterase (ChE) evolution in Invertebrata, this enzyme was studied in the unsegmented marine worm Sipunculus nudus. ChE activity was solubilized through three successive steps of extraction. These fractions are noted as low-salt (LSS), detergent (DS) and high-salt soluble (HSS) and represent 27%, 68% and 5% of total activity, respectively. LSS and DS ChE were purified to homogeneity by affinity chromatography on edrophonium-Sepharose gel. Purification factors of 1700 (LSS) and 1090 (DS) were obtained. The small amount of HSS ChE prevented a similar purification and an extensive characterization. Based on SDS/PAGE and density-gradient centrifugation, both LSS and DS enzymes show a M(r) value of about 130,000 and are likely G2 globular dimers of a 67,000 subunit. Moreover, LSS ChE seems to be an amphiphilic form including a hydrophobic domain, while DS ChE is probably linked to the cell membrane by a phosphatidylinositol anchor. Both LSS and DS enzymes hydrolyze at the highest rate propionylthiocholine. However, they also show a fairly high catalytic efficiency with other thiocholine esters as substrates, thus suggesting a wide and little-specialized conformation of the active site. Based on immunological cross-reactivity trials, LSS and DS ChE from S. nudus show a reduced structural affinity with a molluscan (Murex brandaris) enzyme. HSS ChE, an acetylcholinesterase, is also solubilized by heparin, like typical vertebrate HSS asymmetric enzymes. However, it lacks fast-sedimenting forms and an enzyme-anchoring collagenous structure.

  9. The common polymorphism of apolipoprotein E

    DEFF Research Database (Denmark)

    Gerdes, Ulrik

    2003-01-01

    Apolipoprotein E (apoE) has important functions in systemic and local lipid transport, but also has other functions. The gene (APOE) shows a common polymorphism with three alleles--APOE*2, APOE*3, and APOE*4. Their frequencies vary substantially around the world, but APOE*3 is the most common...... from only 10-15% in southern Europe to 40-50% in the north. The gradient may be a trace of the demic expansion of agriculture that began about 10,000 years ago, but it may also reflect the possibility that APOE*4 carriers are less likely to develop vitamin D deficiency. The common APOE polymorphism...

  10. Role of apolipoprotein E in neurodegenerative diseases

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    Giau VV

    2015-07-01

    Full Text Available Vo Van Giau,1 Eva Bagyinszky,1 Seong Soo A An,1 SangYun Kim2 1Department of Bionano Technology, Gachon Medical Research Institute, Gachon University, Seongnam, South Korea; 2Department of Neurology, Seoul National University College of Medicine in Seoul National Bundang Hospital, Seoul, South Korea Abstract: Apolipoprotein E (APOE is a lipid-transport protein abundantly expressed in most neurons in the central nervous system. APOE-dependent alterations of the endocytic pathway can affect different functions. APOE binds to cell-surface receptors to deliver lipids and to the hydrophobic amyloid-β peptide, regulating amyloid-β aggregations and clearances in the brain. Several APOE isoforms with major structural differences were discovered and shown to influence the brain lipid transport, glucose metabolism, neuronal signaling, neuroinflammation, and mitochondrial function. This review will summarize the updated research progress on APOE functions and its role in Alzheimer’s disease, Parkinson’s disease, cardiovascular diseases, multiple sclerosis, type 2 diabetes mellitus, Type III hyperlipoproteinemia, vascular dementia, and ischemic stroke. Understanding the mutations in APOE, their structural properties, and their isoforms is important to determine its role in various diseases and to advance the development of therapeutic strategies. Targeting APOE may be a potential approach for diagnosis, risk assessment, prevention, and treatment of various neurodegenerative and cardiovascular diseases in humans. Keywords: apolipoprotein E, pathogenesis, diseases

  11. Interactions of metals and Apolipoprotein E in Alzheimer’s disease

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    He eXu

    2014-06-01

    Full Text Available Alzheimer’s disease (AD is the most common form of dementia, which is characterized by the neuropathological accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles (NFTs. Clinically, patients will endure a gradual erosion of memory and other higher order cognitive functions. Whilst the underlying etiology of the disease remains to be definitively identified, a body of work has developed over the last two decades demonstrating that AD plasma/serum and brain are characterized by a dyshomeostasis in a number of metal ions. Furthermore, these metals (such as zinc, copper and iron play roles in the regulation of the levels AD-related proteins, including the amyloid precursor protein (APP and tau. It is becoming apparent that metals also interact with other proteins, including apolipoprotein E (ApoE. The Apolipoprotein E gene (APOE is critically associated with AD, with APOE4 representing the strongest genetic risk factor for the development of late-onset AD whereas APOE2 appears to have a protective role. In this review we will summarize the evidence supporting a role for metals in the function of Apolipoprotein E (ApoE and its consequent role in the pathogenesis of AD.

  12. Apolipoprotein E gene polymorphism in Egyptian acute coronary ...

    African Journals Online (AJOL)

    Background: Apolipoprotein E (apo E) gene polymorphism was found to be associated with coronary artery disease in several studies. In this investigation, we aimed to study the association between apo E gene polymorphism and acute coronary syndrome in Egyptian population. Subjects and methods: The study included ...

  13. Apolipoprotein E gene and sporadic frontal lobe dementia.

    NARCIS (Netherlands)

    M. Stevens (Martijn); C.M. van Duijn (Cornelia); P. de Knijff (Peter); B.A. Oostra (Ben); M.F. Niermeijer (Martinus); J.C. van Swieten (John); P. Heutink (Peter); C. van Broeckhoven (Christine)

    1997-01-01

    textabstractThe apolipoprotein E gene has been associated with various types of dementia. We studied the connection between the APOE gene and the risk and onset of disease in 34 patients with clinically diagnosed frontal lobe dementia (FLD) derived from a population-based study in the Netherlands. A

  14. Apolipoprotein E genotype, cardiovascular biomarkers and risk of stroke

    DEFF Research Database (Denmark)

    Khan, Tauseef A; Shah, Tina; Prieto, David

    2013-01-01

    At the APOE gene, encoding apolipoprotein E, genotypes of the ε2/ε3/ε4 alleles associated with higher LDL-cholesterol (LDL-C) levels are also associated with higher coronary risk. However, the association of APOE genotype with other cardiovascular biomarkers and risk of ischaemic stroke is less c...

  15. Evidence for major gene inheritance of Alzheimer disease in families of patients with and without apolipoprotein E ε 4.

    NARCIS (Netherlands)

    V. Rao; L.A. Cupples (Adrienne); C.M. van Duijn (Cornelia); A. Kurz; R.C. Green (Robert); H. Chui (Helena); R. Duara; S.A. Auerbach; L. Volicer; J. Wells; J.H. Growdon (John); J.L. Haines (Jonathan); L.A. Farrer (Lindsay); C. van Broeckhoven (Christine)

    1996-01-01

    textabstractApolipoprotein E (APOE) genotype is the single most important determinant to the common form of Alzheimer disease (AD) yet identified. Several studies show that family history of AD is not entirely accounted for by APOE genotype. Also, there is evidence for an interaction between APOE

  16. DMPD: Regulation of endogenous apolipoprotein E secretion by macrophages. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18388328 Regulation of endogenous apolipoprotein E secretion by macrophages. Kockx ...svg) (.html) (.csml) Show Regulation of endogenous apolipoprotein E secretion by macrophages. PubmedID 18388...328 Title Regulation of endogenous apolipoprotein E secretion by macrophages. Aut

  17. Reversal of hypercholesterolemia in apolipoprotein E2 and apolipoprotein E3-Leiden transgenic mice by adenovirus-mediated gene transfer of the VLDL receptor

    NARCIS (Netherlands)

    Dijk, K.W. van; Vlijmen, B.J.M. van; Zee, A. van der; Hof, B. van 't; Boom, H. van der; Kobayashi, K.; Chan, L.; Havekes, L.M.; Hofker, M.H.

    1998-01-01

    We have investigated the interaction of apolipoprotein E2(Arg158- Cys) (apoE2) and apolipoprotein E3Leiden (apoE3-Leiden) with the very low density lipoprotein (VLDL) receptor in vivo and in vitro to define the possible role of this receptor in lipoprotein metabolism and atherosclerosis. The in vivo

  18. Structure of the dimeric form of CTP synthase from Sulfolobus solfataricus

    DEFF Research Database (Denmark)

    Lauritsen, Iben; Willemoës, Martin; Jensen, Kaj Frank

    2011-01-01

    CTP synthase catalyzes the last committed step in de novo pyrimidine-nucleotide biosynthesis. Active CTP synthase is a tetrameric enzyme composed of a dimer of dimers. The tetramer is favoured in the presence of the substrate nucleotides ATP and UTP; when saturated with nucleotide, the tetramer c....... solfataricus CTP synthase according to a structural alignment with the E. coli enzyme all have large thermal parameters in the dimeric form. Furthermore, they are seen to undergo substantial movement upon tetramerization....

  19. Core-to-core dimers forming switchable mesophase

    Czech Academy of Sciences Publication Activity Database

    Horčic, M.; Svoboda, J.; Novotná, Vladimíra; Pociecha, D.; Gorecka, E.

    2017-01-01

    Roč. 53, č. 18 (2017), s. 2721-2724 ISSN 1359-7345 R&D Projects: GA ČR GA15-02843S Institutional support: RVO:68378271 Keywords : liquid crystals * bent-core mesogens * dimers Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 6.319, year: 2016

  20. Function and Comorbidities of Apolipoprotein E in Alzheimer's Disease

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    Valérie Leduc

    2011-01-01

    Full Text Available Alzheimer's disease (AD—the most common type of dementia among the elderly—represents one of the most challenging and urgent medical mysteries affecting our aging population. Although dominant inherited mutation in genes involved in the amyloid metabolism can elicit familial AD, the overwhelming majority of AD cases, dubbed sporadic AD, do not display this Mendelian inheritance pattern. Apolipoprotein E (APOE, the main lipid carrier protein in the central nervous system, is the only gene that has been robustly and consistently associated with AD risk. The purpose of the current paper is thus to highlight the pleiotropic roles and the structure-function relationship of APOE to stimulate both the functional characterization and the identification of novel lipid homeostasis-related molecular targets involved in AD.

  1. Cardiovascular effects of uremia in apolipoprotein E-deficient mice

    DEFF Research Database (Denmark)

    Bro, Susanne

    2009-01-01

    The purpose of this thesis work was to establish an experimental mouse model for studying the pathogenesis and therapy of accelerated atherosclerosis in uremia. Uremia was induced by surgical 5/6 nephrectomy in apolipoprotein E-deficient (apoE-/-) mice and led to development of severe aortic...... atherosclerosis independently of BP and plasma homocysteine levels. Also, the accelerated atherosclerosis could not be fully explained by changes in total plasma cholesterol. Morphologic and biochemical analyses of aortas suggested that accelerated initiation and expansion rather than a specific uremic lesion...... composition characterize atherosclerosis in the uremic mice. Increased expression of inflammatory genes in aortas of uremic mice suggests that an augmented inflammatory response in the arterial wall might be an important impetus for accelerated atherosclerosis in uremia. A marked downregulation of expression...

  2. Antiatherogenic effects of oleanolic acid in apolipoprotein E knockout mice

    DEFF Research Database (Denmark)

    Buus, Niels Henrik; Hansson, Nicolaj Christopher; Rodriguez-Rodriguez, Rosalia

    2011-01-01

    Oleanolic acid (OA) is a plant triterpenoid steroid with potentially antiatherogenic properties. We investigated whether OA affected atherosclerosis development and vascular function in apolipoprotein E knockout (ApoE(-/-)) mice. ApoE(-/-) mice were fed a high cholesterol Western-type diet...... in combination with OA (100 mg/kg/day), fluvastatin (5 mg/kg/day) or vehicle, with wild type (WT) mice serving as controls. After 8 weeks of treatment atherosclerotic plaque areas in the aortic arch and plasma lipid concentrations were determined. Vasoconstriction and relaxation of the proximal part of aorta...... were investigated in vitro. Inducible nitric oxide synthase (iNOS) was visualized using immunoblotting. As opposed to WT and fluvastatin- and vehicle-treated mice, OA-fed ApoE(-/-) mice gained no weight during the treatment period. Plasma concentrations of total-cholesterol and triglyceride were...

  3. [Frequency of apolipoprotein E in a Nahua population].

    Science.gov (United States)

    Suástegui Román, Roberto Alfonso; Yescas Gómez, Petra; Guerrero Camacho, Jorge Luis; Ochoa Morales, Adriana; Granados, Julio; Jara Prado, Aurelio; López-Caro, Oscar Alejandro; Alonso Vilatela, Ma Elisa

    2002-01-01

    The presence of different ethnic groups in Mexico may give rise to genetic diversity between the native Indian population and the Mestizos. It is therefore of medical and anthropological interest to analyze the genotypes of disease-associated loci, such as polymorphism in the apolipoprotein E gene, whose 4/4 allele increases the risk of Alzheimer's disease and coronary heart disease in other populations. We studied a Nahua Indian-population in the State of Morelos (Santo Domingo Ocotitlan). The ABO blood type of all individuals was determined and compared with the findings of other Nahua group from the State of Puebla. Without statistical significant differences in O, A and AB groups between both populations (p > 0.05). The allelic and genotypic frequency of apolipoprotein E was similar to that observed in other Mexican indian (Mazatecans, Mayans) and Mestizo populations, however there was a statistically significant difference when the results were compared to the allelic frequencies of other Amerinds: The Cayapa (Ecuador) for the epsilon 3 and epsilon 4 alleles (p < 0.002); the Nuuk (Greenland) for epsilon 3 and epsilon 4 alleles (p < 0.0001 and p < 0.002 respectively); and the Ammssalik (Greenland) for both alleles with p < 0.0001 and p = 0.04 respectively. In the case of the genotypes, there was statistically significant difference for the 4/3 genotypes, but a non significant difference for the 4/4 genotype. This is a descriptive study which contributes to the knowledge of the genetic structure of Mexican population.

  4. Serum apolipoprotein e level is not increased in Alzheimer's disease : The Rotterdam study

    NARCIS (Netherlands)

    Slooter, A.J.C.; Knijff, P. de; Hofman, A.; Cruts, M.; Breteler, M.M.B.; Broeckhoven, C. van; Havekes, L.M.; Duijn, C.M. van

    1998-01-01

    The APOE*4 allele of the apolipoprotein E gene (APOE) is an important risk factor for Alzheimer's disease. It has been suggested that levels of apolipoprotein E (apoE) in plasma are increased in Alzheimer's disease. In this population-based study, we found that serum apoE levels were lower in

  5. Nicotinamidase/pyrazinamidase of Mycobacterium tuberculosis forms homo-dimers stabilized by disulfide bonds.

    Science.gov (United States)

    Rueda, Daniel; Sheen, Patricia; Gilman, Robert H; Bueno, Carlos; Santos, Marco; Pando-Robles, Victoria; Batista, Cesar V; Zimic, Mirko

    2014-12-01

    Recombinant wild-pyrazinamidase from H37Rv Mycobacterium tuberculosis was analyzed by gel electrophoresis under differential reducing conditions to evaluate its quaternary structure. PZAse was fractionated by size exclusion chromatography under non-reducing conditions. PZAse activity was measured and mass spectrometry analysis was performed to determine the identity of proteins by de novo sequencing and to determine the presence of disulfide bonds. This study confirmed that M. tuberculosis wild type PZAse was able to form homo-dimers in vitro. Homo-dimers showed a slightly lower specific PZAse activity compared to monomeric PZAse. PZAse dimers were dissociated into monomers in response to reducing conditions. Mass spectrometry analysis confirmed the existence of disulfide bonds (C72-C138 and C138-C138) stabilizing the quaternary structure of the PZAse homo-dimer. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Human cystatin C forms an inactive dimer during intracellular trafficking in transfected CHO cells

    DEFF Research Database (Denmark)

    Merz, G S; Benedikz, Eirikur; Schwenk, V

    1997-01-01

    To define the cellular processing of human cystatin C as well as to lay the groundwork for investigating its contribution to lcelandic Hereditary Cerebral Hemorrhage with Amyloidosis (HCHWA-I), we have characterized the trafficking, secretion, and extracellular fate of human cystatin C...... that the cystatin C dimer, formed during intracellular trafficking, is converted to monomer at or before secretion. Cells in which exit from the endoplasmic reticulum (ER) was blocked with brefeldin A contained the 33 kDa species, indicating that cystatin C dimerization occurs in the ER. After removal of brefeldin......, presumably as a consequence of the low pH of late endosome/lysosomes. As a dimer, cystatin C would be prevented from inhibiting the lysosomal cysteine proteases. These results reveal a novel mechanism, transient dimerization, by which cystatin C is inactivated during the early part of its trafficking through...

  7. Structural and Vibrational Study on Monomer and Dimer Forms and Water Clusters of Acetazolamide

    Directory of Open Access Journals (Sweden)

    Aysen E. Ozel

    2013-01-01

    Full Text Available Experimental IR and Raman spectra of solid acetazolamide have been analysed by computing the molecular structures and vibrational spectra of monomer and dimer forms and water clusters of acetazolamide. The possible stable conformers of free acetazolamide molecule in the ground state were obtained by scanning the potential energy surface through the dihedral angles, D1 (1S-2C-6S-9N, D2 (4N-5C-12N-14C, and D3 (5C-12N-14C-16C. The final geometry parameters for the obtained stable conformers were determined by means of geometry optimization, carried out at DFT/B3LYP/6-31G++(d,p theory level. Afterwards the possible dimer forms of the molecule and acetazolamide-H2O clusters were formed and their energetically preferred conformations were investigated using the same method and the same level of theory. The effect of BSSE on the structure and energy of acetazolamide dimer has been investigated. The assignment of the vibrational modes was performed based on the potential energy distribution of the vibrational modes, calculated by using GAR2PED program. The experimental vibrational wavenumbers of solid acetazolamide are found to be in better agreement with the calculated wavenumbers of dimer form of acetazolamide than those of its monomeric form. NBO analysis has been performed on both monomer and dimer geometries.

  8. Visfatin Destabilizes Atherosclerotic Plaques in Apolipoprotein E-Deficient Mice.

    Directory of Open Access Journals (Sweden)

    Bo Li

    Full Text Available Although there is evidence that visfatin is associated with atherogenesis, the effect of visfatin on plaque stability has not yet been explored.In vivo, vulnerable plaques were established by carotid collar placement in apolipoprotein E-deficient (ApoE-/- mice, and lentivirus expressing visfatin (lenti-visfatin was locally infused in the carotid artery. The lipid, macrophage, smooth muscle cell (SMC and collagen levels were evaluated, and the vulnerability index was calculated. In vitro, RAW264.7 cells were stimulated with visfatin, and the MMPs expressions were assessed by western blot and immunofluorescence. And the mechanism that involved in visfatin-induced MMP-8 production was investigated.Transfection with lenti-visfatin significantly promoted the expression of visfatin which mainly expressed in macrophages in the plaque. Lenti-visfatin transfection significantly promoted the accumulation of lipids and macrophages, modulated the phenotypes of smooth muscle cells and decreased the collagen levels in the plaques, which significantly decreased the plaque stability. Simultaneously, transfection with lenti-visfatin significantly up-regulated the expression of MMP-8 in vivo, as well as MMP-1, MMP-2 and MMP-9. Recombinant visfatin dose- and time-dependently up-regulated the in vitro expression of MMP-8 in macrophages. Visfatin promoted the translocation of NF-κB, and inhibition of NF-κB significantly reduced visfatin-induced MMP-8 production.Visfatin increased MMP-8 expression, promoted collagen degradation and increased the plaques vulnerability index.

  9. Apolipoprotein E: Essential Catalyst of the Alzheimer Amyloid Cascade

    Directory of Open Access Journals (Sweden)

    Huntington Potter

    2012-01-01

    Full Text Available The amyloid cascade hypothesis remains a robust model of AD neurodegeneration. However, amyloid deposits contain proteins besides Aβ, such as apolipoprotein E (apoE. Inheritance of the apoE4 allele is the strongest genetic risk factor for late-onset AD. However, there is no consensus on how different apoE isotypes contribute to AD pathogenesis. It has been hypothesized that apoE and apoE4 in particular is an amyloid catalyst or “pathological chaperone”. Alternatively it has been posited that apoE regulates Aβ clearance, with apoE4 been worse at this function compared to apoE3. These views seem fundamentally opposed. The former would indicate that removing apoE will reduce AD pathology, while the latter suggests increasing brain ApoE levels may be beneficial. Here we consider the scientific basis of these different models of apoE function and suggest that these seemingly opposing views can be reconciled. The optimal therapeutic target may be to inhibit the interaction of apoE with Aβ rather than altering apoE levels. Such an approach will not have detrimental effects on the many beneficial roles apoE plays in neurobiology. Furthermore, other Aβ binding proteins, including ACT and apo J can inhibit or promote Aβ oligomerization/polymerization depending on conditions and might be manipulated to effect AD treatment.

  10. Effects of hydrogen peroxide and apolipoprotein E isoforms on apolipoprotein E trafficking in HepG2 cells.

    Science.gov (United States)

    Sabaretnam, Tharani; Harris, Matthew J; Kockx, Maaike; Witting, Paul K; Le Couteur, David G; Kritharides, Leonard

    2009-12-01

    1. The major source of apolipoprotein E (apoE) is the liver. In the present study, the effects of oxidative stress and apoE isoforms on apoE distribution and trafficking were established using the HepG2 liver tumour cell line. 2. Hydrogen peroxide (0, 25, 250 and 1000 micromol/L) was associated with rapid and concentration-dependent redistribution of apoE into the early endosomal compartment. This redistribution was achieved with a much lower concentration (25 micromol/L) than that needed to induce changes in intracellular apoE mRNA expression, apoE protein levels and markers of oxidative stress (250-1000 micromol/L). 3. Live cell imaging of apoE3-green fluorescent protein revealed a significant decrease in traffic velocity in response to oxidative stress. 4. The E4 isoform was associated with reduced trafficking velocity compared with the E3 isoform under basal conditions. 5. The results indicate that oxidative stress and apoE isoforms influence apoE trafficking and distribution within HepG2 cells. Altered apoE hepatocyte trafficking may provide a mechanistic link between oxidative stress, ageing and some diseases in older people.

  11. Apolipoprotein E promotes lipid accumulation and differentiation in human adipocytes

    Energy Technology Data Exchange (ETDEWEB)

    Lasrich, Dorothee; Bartelt, Alexander [Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany); Grewal, Thomas, E-mail: thomas.grewal@sydney.edu.au [Faculty of Pharmacy A15, The University of Sydney, Sydney, NSW 2006 (Australia); Heeren, Joerg, E-mail: heeren@uke.de [Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany)

    2015-09-10

    Several studies in mice indicate a role for apolipoprotein E (APOE) in lipid accumulation and adipogenic differentiation in adipose tissue. However, little is yet known if APOE functions in a similar manner in human adipocytes. This prompted us to compare lipid loading and expression of adipocyte differentiation markers in APOE-deficient and control adipocytes using the differentiated human mesenchymal stem cell line hMSC-Tert as well as primary human and mouse adipocytes as model systems. Differentiated hMSC-Tert were stably transduced with or without siRNA targeting APOE while murine adipocytes were isolated from wild type and Apoe knockout mice. Human APOE knockdown hMSC-Tert adipocytes accumulated markedly less triglycerides compared to control cells. This correlated with strongly decreased gene expression levels of adipocyte markers such as adiponectin (ADIPOQ) and fatty acid binding protein 4 (FABP4) as well as the key transcription factor driving adipocyte differentiation, peroxisome proliferator activator receptor gamma (PPARG), in particular the PPARG2 isoform. Similarly, differentiation of murine Apoe-deficient adipocytes was characterized by reduced gene expression of Adipoq, Fabp4 and Pparg. Interestingly, incubation of APOE-deficient hMSC-Tert adipocytes with conditioned media from APOE3-overexpressing adipocytes or APOE-containing Very Low Density Lipoprotein (VLDL) partially restored triglyceride accumulation, but were unable to induce adipocyte differentiation, as judged by expression of adipocyte markers. Taken together, depletion of endogenous APOE in human adipocytes severely impairs lipid accumulation, which is associated with an inability to initiate differentiation. - Highlights: • Immortalized human mesenchymal stem cells were used to study adipocyte development. • Knockdown of endogenous APOE lead to impaired lipid accumulation and adipogenesis. • APOE supplementation partially restored lipid accumulation but not differentiation.

  12. Apolipoprotein E polymorphism in Brazilian dyslipidemic individuals: Ouro Preto study.

    Science.gov (United States)

    Mendes-Lana, A; Pena, G G; Freitas, S N; Lima, A A; Nicolato, R L C; Nascimento-Neto, R M; Machado-Coelho, G L L; Freitas, R N

    2007-01-01

    The influence of apolipoprotein E alleles and genotypes on plasma lipid levels was determined in 185 individuals of mixed ethnicity living in Ouro Preto, Brazil. DNA was obtained from blood samples and the genotypes were determined by an RFLP-PCR procedure. The *3 allele was the most frequent (72%), followed by *4 (20%) and *2 (8%); *4 frequency was higher and *2 frequency was lower in the dyslipidemic group than in the normal control group. The *2 carriers presented lower LDL and total cholesterol levels compared to the *3 and *4 carriers. All six expected genotypes were observed in the individuals genotyped: E2/2 (2.1%), E4/4 (2.7%), E2/4 (3.7%), E2/3 (8.0%), E3/3 (53.3%), E3/4 (29.9%); no difference in genotype frequencies was found between the normal and dyslipidemic groups. Compared with *2, the presence of *3 increases more than two times the risk for dyslipidemia (OR = 2.31; P = 0.025; 95% CI = 1.06-5.06) and the presence of *4 increases it three times (OR = 3.31; P = 0.006; 95% CI = 1.36-8.04). The only significant effect of genotype was an increased risk for dyslipidemia in the *4 genotype carriers (E3/4 + E4/4) compared with the *2 genotype carriers (E2/2 + E2/3) with OR = 3.69 (95% CI = 1.25-10.88). The present study indicates that in the Ouro Preto admixed population the presence of APOE *2 can confer a protective effect, whereas the presence of APOE *4 implies an enhanced risk for dyslipidemia.

  13. Sildenafil restores endothelial function in the apolipoprotein E knockout mouse

    Directory of Open Access Journals (Sweden)

    Balarini Camille M

    2013-01-01

    Full Text Available Abstract Background Atherosclerosis is an inflammatory process of the arterial walls and is initiated by endothelial dysfunction accompanied by an imbalance in the production of reactive oxygen species (ROS and nitric oxide (NO. Sildenafil, a selective phosphodiesterase-5 (PDE5 inhibitor used for erectile dysfunction, exerts its cardiovascular effects by enhancing the effects of NO. The aim of this study was to investigate the influence of sildenafil on endothelial function and atherosclerosis progression in apolipoprotein E knockout (apoE−/− mice. Methods ApoE−/− mice treated with sildenafil (Viagra®, 40 mg/kg/day, for 3 weeks, by oral gavage were compared to the untreated apoE−/− and the wild-type (WT mice. Aortic rings were used to evaluate the relaxation responses to acetylcholine (ACh in all of the groups. In a separate set of experiments, the roles of NO and ROS in the relaxation response to ACh were evaluated by incubating the aortic rings with L-NAME (NO synthase inhibitor or apocynin (NADPH oxidase inhibitor. In addition, the atherosclerotic lesions were quantified and superoxide production was assessed. Results Sildenafil restored the vasodilator response to acetylcholine (ACh in the aortic rings of the apoE−/− mice. Treatment with L-NAME abolished the vasodilator responses to ACh in all three groups of mice and revealed an augmented participation of NO in the endothelium-dependent vasodilation in the sildenafil-treated animals. The normalized endothelial function in sildenafil-treated apoE−/− mice was unaffected by apocynin highlighting the low levels of ROS production in these animals. Moreover, morphological analysis showed that sildenafil treatment caused approximately a 40% decrease in plaque deposition in the aorta. Conclusion This is the first study demonstrating the beneficial effects of chronic treatment with sildenafil on endothelial dysfunction and atherosclerosis in a model of spontaneous

  14. Thyroid hormones upregulate apolipoprotein E gene expression in astrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Roman, Corina; Fuior, Elena V.; Trusca, Violeta G. [Institute of Cellular Biology and Pathology “Nicolae Simionescu”, Bucharest (Romania); Kardassis, Dimitris [University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology of Hellas, Heraklion, Crete (Greece); Simionescu, Maya [Institute of Cellular Biology and Pathology “Nicolae Simionescu”, Bucharest (Romania); Gafencu, Anca V., E-mail: anca.gafencu@icbp.ro [Institute of Cellular Biology and Pathology “Nicolae Simionescu”, Bucharest (Romania)

    2015-12-04

    Apolipoprotein E (apoE), a protein mainly involved in lipid metabolism, is associated with several neurodegenerative disorders including Alzheimer's disease. Despite numerous attempts to elucidate apoE gene regulation in the brain, the exact mechanism is still uncovered. The mechanism of apoE gene regulation in the brain involves the proximal promoter and multienhancers ME.1 and ME.2, which evolved by gene duplication. Herein we questioned whether thyroid hormones and their nuclear receptors have a role in apoE gene regulation in astrocytes. Our data showed that thyroid hormones increase apoE gene expression in HTB14 astrocytes in a dose-dependent manner. This effect can be intermediated by the thyroid receptor β (TRβ) which is expressed in these cells. In the presence of triiodothyronine (T3) and 9-cis retinoic acid, in astrocytes transfected to overexpress TRβ and retinoid X receptor α (RXRα), apoE promoter was indirectly activated through the interaction with ME.2. To determine the location of TRβ/RXRα binding site on ME.2, we performed DNA pull down assays and found that TRβ/RXRα complex bound to the region 341–488 of ME.2. This result was confirmed by transient transfection experiments in which a series of 5′- and 3′-deletion mutants of ME.2 were used. These data support the existence of a biologically active TRβ binding site starting at 409 in ME.2. In conclusion, our data revealed that ligand-activated TRβ/RXRα heterodimers bind with high efficiency on tissue-specific distal regulatory element ME.2 and thus modulate apoE gene expression in the brain. - Highlights: • T3 induce a dose-dependent increase of apoE expression in astrocytes. • Thyroid hormones activate apoE promoter in a cell specific manner. • Ligand activated TRβ/RXRα bind on the distal regulatory element ME.2 to modulate apoE. • The binding site of TRβ/RXRα heterodimer is located at 409 bp on ME.2.

  15. Thyroid hormones upregulate apolipoprotein E gene expression in astrocytes

    International Nuclear Information System (INIS)

    Roman, Corina; Fuior, Elena V.; Trusca, Violeta G.; Kardassis, Dimitris; Simionescu, Maya; Gafencu, Anca V.

    2015-01-01

    Apolipoprotein E (apoE), a protein mainly involved in lipid metabolism, is associated with several neurodegenerative disorders including Alzheimer's disease. Despite numerous attempts to elucidate apoE gene regulation in the brain, the exact mechanism is still uncovered. The mechanism of apoE gene regulation in the brain involves the proximal promoter and multienhancers ME.1 and ME.2, which evolved by gene duplication. Herein we questioned whether thyroid hormones and their nuclear receptors have a role in apoE gene regulation in astrocytes. Our data showed that thyroid hormones increase apoE gene expression in HTB14 astrocytes in a dose-dependent manner. This effect can be intermediated by the thyroid receptor β (TRβ) which is expressed in these cells. In the presence of triiodothyronine (T3) and 9-cis retinoic acid, in astrocytes transfected to overexpress TRβ and retinoid X receptor α (RXRα), apoE promoter was indirectly activated through the interaction with ME.2. To determine the location of TRβ/RXRα binding site on ME.2, we performed DNA pull down assays and found that TRβ/RXRα complex bound to the region 341–488 of ME.2. This result was confirmed by transient transfection experiments in which a series of 5′- and 3′-deletion mutants of ME.2 were used. These data support the existence of a biologically active TRβ binding site starting at 409 in ME.2. In conclusion, our data revealed that ligand-activated TRβ/RXRα heterodimers bind with high efficiency on tissue-specific distal regulatory element ME.2 and thus modulate apoE gene expression in the brain. - Highlights: • T3 induce a dose-dependent increase of apoE expression in astrocytes. • Thyroid hormones activate apoE promoter in a cell specific manner. • Ligand activated TRβ/RXRα bind on the distal regulatory element ME.2 to modulate apoE. • The binding site of TRβ/RXRα heterodimer is located at 409 bp on ME.2.

  16. A novel peptide derived from human apolipoprotein E is an inhibitor of tumor growth and ocular angiogenesis.

    Directory of Open Access Journals (Sweden)

    Partha S Bhattacharjee

    2011-01-01

    Full Text Available Angiogenesis is a hallmark of tumor development and metastasis and now a validated target for cancer treatment. We previously reported that a novel dimer peptide (apoEdp derived from the receptor binding region of human apolipoprotein E (apoE inhibits virus-induced angiogenesis. However, its role in tumor anti-angiogenesis is unknown. This study demonstrates that apoEdp has anti-angiogenic property in vivo through reduction of tumor growth in a mouse model and ocular angiogenesis in a rabbit eye model. Our in vitro studies show that apoEdp inhibits human umbilical vein endothelial cell proliferation, migration, invasion and capillary tube formation. We document that apoEdp inhibits vascular endothelial growth factor-induced Flk-1 activation as well as downstream signaling pathways that involve c-Src, Akt, eNOS, FAK, and ERK1/2. These in vitro data suggest potential sites of the apoE dipeptide inhibition that could occur in vivo.This is the first evidence that a synthetic dimer peptide mimicking human apoE has anti-angiogenesis functions and could be an anti-tumor drug candidate.

  17. Domains of macrophage N(O) synthase have divergent roles in forming and stabilizing the active dimeric enzyme.

    Science.gov (United States)

    Ghosh, D K; Abu-Soud, H M; Stuehr, D J

    1996-02-06

    The cytokine-inducible NO synthase (iNOS) is a flavin-containing hemeprotein that must dimerize to generate NO. Trypsin cleaves the dimeric enzyme into an oxygenase domain fragment that remains dimeric, contains heme and H4biopterin, and binds L-arginine and a reductase domain fragment that is monomeric, binds NADPH, FAD, FMN, and catalyzes the reduction of cytochrome c [Ghosh, D. K. & Stuehr, D. J. (1995) Biochemistry 34, 801-807]. The current study investigates the isolated oxygenase and reductase domains of iNOS to understand how they form and stabilize the active dimeric enzyme. The dimeric oxygenase domain dissociated into folded, heme-containing monomers when incubated with 2-5 M urea, whereas the reductase domain unfolded under these conditions and lost its ability to catalyze NADPH-dependent cytochrome c reduction. Spectral analysis of the dissociation reaction showed that it caused structural changes within the oxygenase domain and exposed the distal side of the heme to solvent, enabling it to bind dithiothreitol as a sixth ligand. Importantly, the oxygenase domain monomers could reassociate into a dimeric form even in the absence of the reductase domain. The reaction required L-arginine and H4biopterin and completely reversed the structural changes in heme pocket and protein structure that occurred upon dissociating the original dimer. Together, this confirms that the oxygenase domain contains all of the determinants needed for subunit dimerization and indicates that the dimeric structure greatly affects the heme and protein environment in the oxygenase domain.

  18. Presenilin 1 polymorphism associated with Alzheimer's disease in apolipoprotein E4 carriers.

    Science.gov (United States)

    Martínez-García, Ana; Aldudo, Jesús; Recuero, María; Sastre, Isabel; Vilella-Cuadrada, Elisabet; Rosich-Estragó, Marcel; Frank, Ana; Valdivieso, Fernando; Bullido, María J

    2008-01-01

    Mutations of presenilin 1 (PSEN1) are associated with monogenic Alzheimer's disease (AD); polymorphisms at this gene may therefore be associated with the sporadic form of the disease. In fact, recent meta-analyses and whole-genome association studies indicate PSEN1 as one of the few genes significantly associated with AD risk. Several polymorphisms have been analyzed in PSEN1. The present work examined the possible modulation of the risk of AD by a PSEN1 polymorphism (dbSNP rs3025786) located in intron 7, which we found during a denaturing gradient gel electrophoresis mutation screening of the gene, and which was previously reported as 'suspected' in the public databases. The study of a Spanish case-control sample of 1,183 individuals showed this polymorphism to be associated with AD in an apolipoprotein E (APOE)-specific manner: more specifically, to carry the PSEN1 C allele was associated with a decreased AD risk among carriers of the APOE4 allele. Thus, the present results reinforce the possible involvement of PSEN1 in sporadic AD. Copyright 2008 S. Karger AG, Basel.

  19. Monomeric banana lectin at acidic pH overrules conformational stability of its native dimeric form.

    Directory of Open Access Journals (Sweden)

    Javed M Khan

    Full Text Available Banana lectin (BL is a homodimeric protein categorized among jacalin-related family of lectins. The effect of acidic pH was examined on conformational stability of BL by using circular dichroism, intrinsic fluorescence, 1-anilino-8-napthalene sulfonate (ANS binding, size exclusion chromatography (SEC and dynamic light scattering (DLS. During acid denaturation of BL, the monomerization of native dimeric protein was found at pH 2.0. The elution profile from SEC showed two different peaks (59.65 ml & 87.98 ml at pH 2.0 while single peak (61.45 ml at pH 7.4. The hydrodynamic radii (R h of native BL was 2.9 nm while at pH 2.0 two species were found with R h of 1.7 and 3.7 nm. Furthermore at, pH 2.0 the secondary structures of BL remained unaltered while tertiary structure was significantly disrupted with the exposure of hydrophobic clusters confirming the existence of molten globule like state. The unfolding of BL with different subunit status was further evaluated by urea and temperature mediated denaturation to check their stability. As inferred from high Cm and ΔG values, the monomeric form of BL offers more resistance towards chemical denaturation than the native dimeric form. Besides, dimeric BL exhibited a Tm of 77°C while no loss in secondary structures was observed in monomers even up to 95°C. To the best of our knowledge, this is the first report on monomeric subunit of lectins showing more stability against denaturants than its native dimeric state.

  20. SOXE transcription factors form selective dimers on non-compact DNA motifs through multifaceted interactions between dimerization and high-mobility group domains.

    Science.gov (United States)

    Huang, Yong-Heng; Jankowski, Aleksander; Cheah, Kathryn S E; Prabhakar, Shyam; Jauch, Ralf

    2015-05-27

    The SOXE transcription factors SOX8, SOX9 and SOX10 are master regulators of mammalian development directing sex determination, gliogenesis, pancreas specification and neural crest development. We identified a set of palindromic SOX binding sites specifically enriched in regulatory regions of melanoma cells. SOXE proteins homodimerize on these sequences with high cooperativity. In contrast to other transcription factor dimers, which are typically rigidly spaced, SOXE group proteins can bind cooperatively at a wide range of dimer spacings. Using truncated forms of SOXE proteins, we show that a single dimerization (DIM) domain, that precedes the DNA binding high mobility group (HMG) domain, is sufficient for dimer formation, suggesting that DIM : HMG rather than DIM:DIM interactions mediate the dimerization. All SOXE members can also heterodimerize in this fashion, whereas SOXE heterodimers with SOX2, SOX4, SOX6 and SOX18 are not supported. We propose a structural model where SOXE-specific intramolecular DIM:HMG interactions are allosterically communicated to the HMG of juxtaposed molecules. Collectively, SOXE factors evolved a unique mode to combinatorially regulate their target genes that relies on a multifaceted interplay between the HMG and DIM domains. This property potentially extends further the diversity of target genes and cell-specific functions that are regulated by SOXE proteins.

  1. SOXE transcription factors form selective dimers on non-compact DNA motifs through multifaceted interactions between dimerization and high-mobility group domains

    Science.gov (United States)

    Huang, Yong-Heng; Jankowski, Aleksander; Cheah, Kathryn S. E.; Prabhakar, Shyam; Jauch, Ralf

    2015-01-01

    The SOXE transcription factors SOX8, SOX9 and SOX10 are master regulators of mammalian development directing sex determination, gliogenesis, pancreas specification and neural crest development. We identified a set of palindromic SOX binding sites specifically enriched in regulatory regions of melanoma cells. SOXE proteins homodimerize on these sequences with high cooperativity. In contrast to other transcription factor dimers, which are typically rigidly spaced, SOXE group proteins can bind cooperatively at a wide range of dimer spacings. Using truncated forms of SOXE proteins, we show that a single dimerization (DIM) domain, that precedes the DNA binding high mobility group (HMG) domain, is sufficient for dimer formation, suggesting that DIM : HMG rather than DIM:DIM interactions mediate the dimerization. All SOXE members can also heterodimerize in this fashion, whereas SOXE heterodimers with SOX2, SOX4, SOX6 and SOX18 are not supported. We propose a structural model where SOXE-specific intramolecular DIM:HMG interactions are allosterically communicated to the HMG of juxtaposed molecules. Collectively, SOXE factors evolved a unique mode to combinatorially regulate their target genes that relies on a multifaceted interplay between the HMG and DIM domains. This property potentially extends further the diversity of target genes and cell-specific functions that are regulated by SOXE proteins. PMID:26013289

  2. Human apolipoprotein E genotypes differentially modify house dust mite-induced airway disease in mice

    DEFF Research Database (Denmark)

    Yao, Xianglan; Dai, Cuilian; Fredriksson, Karin

    2012-01-01

    Apolipoprotein E (apoE) is an endogenous negative regulator of airway hyperreactivity (AHR) and mucous cell metaplasia in experimental models of house dust mite (HDM)-induced airway disease. The gene encoding human apoE is polymorphic, with three common alleles (e2, e3, and e4) reflecting single...

  3. Capillary electrophoresis with laser-induced fluorescence detection for fast and reliable apolipoprotein E genotyping

    NARCIS (Netherlands)

    Somsen, GW; Welten, HTME; Mulder, FP; Swart, CW; Kema, IP; de Jong, GJ

    2002-01-01

    The use of capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection for the rapid determination of apolipoprotein E (apoE) genotypes was studied. High resolution and sensitive detection of the concerned DNA restriction fragments was achieved using CE buffers with

  4. Plasma levels of apolipoprotein E and risk of ischemic heart disease in the general population

    DEFF Research Database (Denmark)

    Rasmussen, Katrine L.; Tybjærg-Hansen, Anne; Nordestgaard, Børge G

    2016-01-01

    BACKGROUND AND AIMS: Triglyceride-rich lipoproteins are causally associated with high risk of ischemic heart disease (IHD), and apolipoprotein E (apoE) has a central role in their plasma clearance. While both quantitative and qualitative changes of apoE are established causes of rare dyslipidemia...

  5. Apolipoprotein E4 reduces evoked hippocampal acetylcholine release in adult mice

    Czech Academy of Sciences Publication Activity Database

    Dolejší, Eva; Liraz, O.; Rudajev, Vladimír; Zimčík, Pavel; Doležal, Vladimír; Michaelson, D. M.

    2016-01-01

    Roč. 136, č. 3 (2016), s. 503-509 ISSN 0022-3042 R&D Projects: GA MŠk(CZ) LH13269 Institutional support: RVO:67985823 Keywords : acetylcholine release * Alzheimer's disease (AD) * apolipoprotein E4 (apoE4) * hippocampus Subject RIV: FH - Neurology Impact factor: 4.083, year: 2016

  6. Biochemical, mutational and in silico structural evidence for a functional dimeric form of the ornithine decarboxylase from Entamoeba histolytica.

    Directory of Open Access Journals (Sweden)

    Preeti

    Full Text Available BACKGROUND: Entamoeba histolytica is responsible for causing amoebiasis. Polyamine biosynthesis pathway enzymes are potential drug targets in parasitic protozoan diseases. The first and rate-limiting step of this pathway is catalyzed by ornithine decarboxylase (ODC. ODC enzyme functions as an obligate dimer. However, partially purified ODC from E. histolytica (EhODC is reported to exist in a pentameric state. METHODOLOGY AND RESULTS: In present study, the oligomeric state of EhODC was re-investigated. The enzyme was over-expressed in Escherichia coli and purified. Pure protein was used for determination of secondary structure content using circular dichroism spectroscopy. The percentages of α-helix, β-sheets and random coils in EhODC were estimated to be 39%, 25% and 36% respectively. Size-exclusion chromatography and mass spectrophotometry analysis revealed that EhODC enzyme exists in dimeric form. Further, computational model of EhODC dimer was generated. The homodimer contains two separate active sites at the dimer interface with Lys57 and Cys334 residues of opposite monomers contributing to each active site. Molecular dynamic simulations were performed and the dimeric structure was found to be very stable with RMSD value ∼0.327 nm. To gain insight into the functional role, the interface residues critical for dimerization and active site formation were identified and mutated. Mutation of Lys57Ala or Cys334Ala completely abolished enzyme activity. Interestingly, partial restoration of the enzyme activity was observed when inactive Lys57Ala and Cys334Ala mutants were mixed confirming that the dimer is the active form. Furthermore, Gly361Tyr and Lys157Ala mutations at the dimer interface were found to abolish the enzyme activity and destabilize the dimer. CONCLUSION: To our knowledge, this is the first report which demonstrates that EhODC is functional in the dimeric form. These findings and availability of 3D structure model of EhODC dimer

  7. The export receptor Crm1 forms a dimer to promote nuclear export of HIV RNA.

    Science.gov (United States)

    Booth, David S; Cheng, Yifan; Frankel, Alan D

    2014-12-08

    The HIV Rev protein routes viral RNAs containing the Rev Response Element (RRE) through the Crm1 nuclear export pathway to the cytoplasm where viral proteins are expressed and genomic RNA is delivered to assembling virions. The RRE assembles a Rev oligomer that displays nuclear export sequences (NESs) for recognition by the Crm1-Ran(GTP) nuclear receptor complex. Here we provide the first view of an assembled HIV-host nuclear export complex using single-particle electron microscopy. Unexpectedly, Crm1 forms a dimer with an extensive interface that enhances association with Rev-RRE and poises NES binding sites to interact with a Rev oligomer. The interface between Crm1 monomers explains differences between Crm1 orthologs that alter nuclear export and determine cellular tropism for viral replication. The arrangement of the export complex identifies a novel binding surface to possibly target an HIV inhibitor and may point to a broader role for Crm1 dimerization in regulating host gene expression.

  8. Suppressive effects of cacao polyphenols on the development of atherosclerosis in apolipoprotein E-deficient mice.

    Science.gov (United States)

    Natsume, Midori; Baba, Seigo

    2014-01-01

    Previous studies in humans have shown that the cacao polyphenols, (-)-epicatechin and its oligomers, prevent in vitro and ex vivo low-density lipoprotein oxidation mediated by free radical generators and metal ions and also reduce plasma LDL-cholesterol levels. The aim of this study was to examine the effects of cacao polyphenols on the development of atherosclerosis in apolipoprotein E-deficient (-/-) mice. Mice aged 8 weeks (n = 90) were randomized into three groups, and fed either normal mouse chow (controls) or chow supplemented with 0.25 or 0.40 % cacao polyphenols for 16 weeks. The mean plaque area in cross-sections of the brachiocephalic trunk was measured and found to be lower in the 0.25 % cacao polyphenol group than in the control group (p cacao polyphenol group (p cacao polyphenols inhibit the development of atherosclerosis in apolipoprotein E-deficient (-/-) mice by reducing oxidative stress and inflammatory responses.

  9. Association of apolipoprotein E allele {epsilon}4 with late-onset sporadic Alzheimer`s disease

    Energy Technology Data Exchange (ETDEWEB)

    Lucotte, G.; David, F.; Berriche, S. [Regional Center of Neurogenetics, Reims (France)] [and others

    1994-09-15

    Apolipoprotein E, type {epsilon}4 allele (ApoE {epsilon}4), is associated with late-onset sporadic Alzheimer`s disease (AD) in French patients. The association is highly significant (0.45 AD versus 0.12 controls for {epsilon}4 allele frequencies). These data support the involvement of ApoE {epsilon}4 allele as a very important risk factor for the clinical expression of AD. 22 refs., 1 fig., 3 tabs.

  10. Euglena gracilis ascorbate peroxidase forms an intramolecular dimeric structure: its unique molecular characterization.

    Science.gov (United States)

    Ishikawa, Takahiro; Tajima, Naoko; Nishikawa, Hitoshi; Gao, Yongshun; Rapolu, Madhusudhan; Shibata, Hitoshi; Sawa, Yoshihiro; Shigeoka, Shigeru

    2010-02-09

    Euglena gracilis lacks a catalase and contains a single APX (ascorbate peroxidase) and enzymes related to the redox cycle of ascorbate in the cytosol. In the present study, a full-length cDNA clone encoding the Euglena APX was isolated and found to contain an open reading frame encoding a protein of 649 amino acids with a calculated molecular mass of 70.5 kDa. Interestingly, the enzyme consisted of two entirely homologous catalytic domains, designated APX-N and APX-C, and an 102 amino acid extension in the N-terminal region, which had a typical class II signal proposed for plastid targeting in Euglena. A computer-assisted analysis indicated a novel protein structure with an intramolecular dimeric structure. The analysis of cell fractionation showed that the APX protein is distributed in the cytosol, but not the plastids, suggesting that Euglena APX becomes mature in the cytosol after processing of the precursor. The kinetics of the recombinant mature FL (full-length)-APX and the APX-N and APX-C domains with ascorbate and H2O2 were almost the same as that of the native enzyme. However, the substrate specificity of the mature FL-APX and the native enzyme was different from that of APX-N and APX-C. The mature FL-APX, but not the truncated forms, could reduce alkyl hydroperoxides, suggesting that the dimeric structure is correlated with substrate recognition. In Euglena cells transfected with double-stranded RNA, the silencing of APX expression resulted in a significant increase in the cellular level of H2O2, indicating the physiological importance of APX to the metabolism of H2O2.

  11. Tor forms a dimer through an N-terminal helical solenoid with a complex topology

    Science.gov (United States)

    Baretić, Domagoj; Berndt, Alex; Ohashi, Yohei; Johnson, Christopher M.; Williams, Roger L.

    2016-04-01

    The target of rapamycin (Tor) is a Ser/Thr protein kinase that regulates a range of anabolic and catabolic processes. Tor is present in two complexes, TORC1 and TORC2, in which the Tor-Lst8 heterodimer forms a common sub-complex. We have determined the cryo-electron microscopy (EM) structure of Tor bound to Lst8. Two Tor-Lst8 heterodimers assemble further into a dyad-symmetry dimer mediated by Tor-Tor interactions. The first 1,300 residues of Tor form a HEAT repeat-containing α-solenoid with four distinct segments: a highly curved 800-residue N-terminal 'spiral', followed by a 400-residue low-curvature 'bridge' and an extended `railing' running along the bridge leading to the 'cap' that links to FAT region. This complex topology was verified by domain insertions and offers a new interpretation of the mTORC1 structure. The spiral of one TOR interacts with the bridge of another, which together form a joint platform for the Regulatory Associated Protein of TOR (RAPTOR) regulatory subunit.

  12. Mechanism of Lipid Binding of Human Apolipoprotein E3 by Hydrogen/Deuterium Exchange/Mass Spectrometry and Fluorescence Polarization.

    Science.gov (United States)

    Fabilane, Charina S; Nguyen, Patricia N; Hernandez, Roy V; Nirudodhi, Sasidhar; Duong, Mai; Maier, Claudia S; Narayanaswami, Vasanthy

    2016-01-01

    Human apolipoprotein E3 (apoE3) is an exchangeable apolipoprotein that plays a critical role in maintaining plasma cholesterol/triglyceride homeostasis. The C-terminal (CT) domain of apoE3 (residues 201-299) is composed of amphipathic α-helices C1: W210-S223, C2: V236-E266, and C3: D271-W276, which play a dominant role in mediating high-affinity lipid binding. The objective is to understand the accessibility of the CT domain at the sub-domain level and the mechanistic details regarding lipid-binding interaction. Hydrogen-deuterium exchange coupled to mass spectrometry (HDX/MS) of recombinant wild type (WT) apoE(201-299), chemical-induced unfolding monitored as changes in fluorescence polarization (FP) of labeled apoE(201-299) bearing a probe at specified sites, and lipid binding studies were carried out. HDX/MS revealed that residues towards the C-terminal end of the domain display significantly lower %D uptake compared to those towards the center, suggesting extensive protein-protein interaction in this segment. Functional assays showed that locking apoE(201-299) in an inter-molecular disulfide-bonded state at position 209, 223, 255, or 277 significantly decreases its ability to interact with lipids, especially when tethered towards the ends; this could be restored by reduction. Unfolding studies indicate that the C-terminal end offers less resistance to unfolding compared to the central portion of the domain. Taken together, our data suggest that two dimers of CT domain are juxtaposed around helix C3 leading to apoE3 tetramerization, and that dissociation to monomeric units is a required step in lipid binding, with helix C3 likely seeking stability via lipid interaction prior to helices C1 or C2.

  13. Allelic polymorphisms in the transcriptional regulatory region of apolipoprotein E gene.

    Science.gov (United States)

    Artiga, M J; Bullido, M J; Sastre, I; Recuero, M; García, M A; Aldudo, J; Vázquez, J; Valdivieso, F

    1998-01-09

    In this work, we explored the existence of genetic variants within the apolipoprotein E gene transcriptional regulatory region, using a denaturing gradient gel electrophoresis screening of a region comprising nucleotides -1017 to +406. Upon a population study, three new polymorphic sites (-491, -427 and -219) and two mutations were found. Functional effects of the polymorphisms, assayed by transient transfection and electrophoretic mobility shift assays in a human hepatoma cell line, showed that polymorphisms at sites -491 and -219 of the APOE promoter produce variations in the transcriptional activity of the gene, most probably through differential binding of nuclear proteins.

  14. LNA-enhanced detection of single nucleotide polymorphisms in the apolipoprotein E

    DEFF Research Database (Denmark)

    Jacobsen, Nana; Bentzen, Joan; Meldgaard, Michael

    2002-01-01

    Genotyping of single nucleotide polymorphisms (SNPs) in large populations presents a great challenge, especially if the SNPs are embedded in GC-rich regions, such as the codon 112 SNP in the human apolipoprotein E (apoE). In the present study, we have used immobilized locked nucleic acid (LNA...... was applied to a panel of patient samples with simultaneous genotyping of the patients by DNA sequencing. The apoE genotyping assays for the codons 112 and 158 SNPs resulted in unambiguous results for all patient samples, concurring with those obtained by DNA sequencing....

  15. Photo-physical properties of dimers formed by tri-aryl pyrylium salts: experimental and theoretical study

    International Nuclear Information System (INIS)

    Lampre, Isabelle

    1996-01-01

    This research thesis reports the study of dimers formed in solution by aggregation of tri-aryl pyrylium salts, in order to establish a direct correlation between properties and electronic structure of components, on the one hand, and molecular pattern, on the other hand. The author adopted a multidisciplinary approach by using experimental techniques and calculations based on the excitonic theory and methods of quantum chemistry. First, the properties of the first excited states of cationic chromophores have been studied (characterisation of electronic transitions, relaxation at the singlet excited state, formation of triplet state). Then, the author analysed dimerisation processes and showed that each dimer is formed by two pairs of ions. She discusses some original optical properties of dimers. The geometry of dimers is theoretically determined by minimising the system interaction potential energy. Electronic transitions are then determined as linear combinations of transitions of two monomers. Properties are thus calculated and are in agreement with those deduced from spectral analysis. The experimentally noticed polarisation change and large Stokes displacement are then explained in terms of emission for a localised state on a chromophore [fr

  16. Mutations of the domain forming the dimeric interface of the ArdA protein affect dimerization and antimodification activity but not antirestriction activity

    Science.gov (United States)

    Roberts, Gareth A; Chen, Kai; Bower, Edward K M; Madrzak, Julia; Woods, Arcadia; Barker, Amy M; Cooper, Laurie P; White, John H; Blakely, Garry W; Manfield, Iain; Dryden, David T F

    2013-01-01

    ArdA antirestriction proteins are encoded by genes present in many conjugative plasmids and transposons within bacterial genomes. Antirestriction is the ability to prevent cleavage of foreign incoming DNA by restriction-modification (RM) systems. Antimodification, the ability to inhibit modification by the RM system, can also be observed with some antirestriction proteins. As these mobile genetic elements can transfer antibiotic resistance genes, the ArdA proteins assist their spread. The consequence of antirestriction is therefore the enhanced dissemination of mobile genetic elements. ArdA proteins cause antirestriction by mimicking the DNA structure bound by Type I RM enzymes. The crystal structure of ArdA showed it to be a dimeric protein with a highly elongated curved cylindrical shape [McMahon SA et al. (2009) Nucleic Acids Res37, 4887–4897]. Each monomer has three domains covered with negatively charged side chains and a very small interface with the other monomer. We investigated the role of the domain forming the dimer interface for ArdA activity via site-directed mutagenesis. The antirestriction activity of ArdA was maintained when up to seven mutations per monomer were made or the interface was disrupted such that the protein could only exist as a monomer. The antimodification activity of ArdA was lost upon mutation of this domain. The ability of the monomeric form of ArdA to function in antirestriction suggests, first, that it can bind independently to the restriction subunit or the modification subunits of the RM enzyme, and second, that the many ArdA homologues with long amino acid extensions, present in sequence databases, may be active in antirestriction. Structured digital abstract ArdA and ArdA bind by molecular sieving (1, 2) ArdA and ArdA bind by cosedimentation in solution (1, 2) PMID:23910724

  17. Age-Related Changes in the Behavior of Apolipoprotein E Knockout Mice.

    Science.gov (United States)

    Fuentes, Dasha; Fernández, Nidia; García, Yenela; García, Teidy; Morales, Ana Ruth; Menéndez, Roberto

    2018-03-03

    The knockout mouse model, B6.129P2-Apoe tm1Unc is homozygotic for the Apolipoprotein E (ApoE) deletion; thus, it is capable of developing hyperlipidemia and atherosclerosis but ApoE is also a lipid-transport protein abundantly expressed in most neurons in the central nervous system, so these animals could also be models of neurodegenerative diseases. The aim of this study was to determine age-related changes in spontaneous behavior and in learning and memory of Apolipoprotein E knockout mice. Spontaneous behavioral measurements included sleeping pattern, motor coordination and balance by rotarod and open field activity, whereas learning and memory tests included forced alternation in Y-maze, novel object recognition and passive avoidance conditioning. Significant behavioral differences between aged knockout mice and age-matched wild type strain, C57Bl/6 were found in all the behavioral tests, except for the rotarod test. Genetically' modified mice exhibited less huddling contact during sleeping, decreased locomotor activity in novel environments and in learning and memory deficits. These results are consistent with the cognitive impairment and memory loss seen as the earliest clinical symptoms in neurodegenerative disorders such as Alzheimer's disease. The ApoE knockout mice might therefore be an appropriate model for studying the underlying mechanisms involved in behavioral changes caused by neurodegenerative diseases as well as for evaluating new therapies for these pathologies.

  18. FAD286, an aldosterone synthase inhibitor, reduced atherosclerosis and inflammation in apolipoprotein E-deficient mice.

    Science.gov (United States)

    Gamliel-Lazarovich, Aviva; Gantman, Anna; Coleman, Raymond; Jeng, Arco Y; Kaplan, Marielle; Keidar, Shlomo

    2010-09-01

    Aldosterone is known to be involved in atherosclerosis and cardiovascular disease and blockade of its receptor was shown to improve cardiovascular function. It was, therefore, hypothesized that inhibition of aldosterone synthesis would also reduce atherosclerosis development. To test this hypothesis, we examined the effect of FAD286 (FAD), an aldosterone synthase inhibitor, on the development of atherosclerosis in spontaneous atherosclerotic apolipoprotein E-deficient mice. Mice were divided into three treatment groups: normal diet, low-salt diet (LSD) and LSD treated with FAD at 30 mg/kg per day (LSD + FAD) for 10 weeks. Histomorphometry of the aortas obtained from these mice showed that atherosclerotic lesion area increased by three-fold under LSD compared with normal diet and FAD significantly reduced lesion area to values similar to normal diet. Changes in atherosclerosis were paralleled by changes in the expression of the inflammation markers (C-reactive protein, monocyte chemotactic protein-1, interleukin-6, nuclear factor kappa B and intercellular adhesion molecule-1) in peritoneal macrophages obtained from these mice. Surprisingly, whereas LSD increased serum or urine aldosterone levels, FAD did not alter these levels when evaluated at the end of the study. In J774A.1 macrophage-like cell line stimulated with lipopolysaccharide, FAD was shown to have a direct dose-dependent anti-inflammatory effect. In apolipoprotein E-deficient mice, FAD reduces atherosclerosis and inflammation. However, these actions appeared to be dissociated from its effect on inhibition of aldosterone synthesis.

  19. Influence of apolipoprotein-E gene on lipid profile, physical activity and body fat relationship

    Directory of Open Access Journals (Sweden)

    Thales Boaventura Rachid Nascimento

    2012-03-01

    Full Text Available Physical activity and body fat modify lipemia, and this effect seems to be influenced by apolipoprotein-E (APOE gene polymorphism. Thus, the purpose of this article was to review main results of studies that have analyzed the relation of APOE gene with physical activity and body fat on triglycerides, total cholesterol and low (LDL and high density lipoprotein (HDL concentrations. The Scientific Electronic Library Online – SciELO, Web of Science and PubMed database were used to locate the articles. The keywords used in combination were: apoe genotype, apolipoprotein-E polymorphism, physical exercise, physical activity, aerobic exercise, body fat and obesity. Originals scientific investigations performed with humans were included, and excluded those ones which involved samples with diseases, except obesity and/or lipemic disorders. It was observed a trend, that ε2 allele carriers are the ones with the greater improvements on lipemia from physical exercise. In addition, the body fat impact on the elevation of triglycerides and LDL are stronger in carriers of the ε2 and ε4 allele, respectively. Considering the small number of originals scientific investigations and their divergent results, reliable inferences can not be made about the APOE gene polymorphism influences on physical activity and body fat effect on lipemia. Thus, further studies with others populations and more volunteers for allele, as well as others exercise modalities and intensities, are necessary.

  20. Apolipoprotein E-deficient mice exhibit increased vulnerability to intermittent hypoxia-induced spatial learning deficits.

    Science.gov (United States)

    Kheirandish, Leila; Row, Barry W; Li, Richard C; Brittian, Kenneth R; Gozal, David

    2005-11-01

    Exposure to intermittent hypoxia, such as occurs in sleep-disordered breathing, is associated with oxidative stress, cognitive impairments, and increased neuronal apoptosis in brain regions involved in learning and memory. Apolipoprotein E (ApoE) has been implicated in neurodegenerative disorders, and in vitro studies suggest that one of the functions of ApoE may be to confer protection from oxidant stress-induced neuronal cell loss. Therefore, we hypothesized that ApoE-deficient (ApoE-/-) mice would display increased cognitive impairments following intermittent hypoxia. Twenty-four young adult male mice (ApoE-/-) and 24 wild-type littermates (ApoE +/+) were exposed to 14 days of normoxia (room air; n=12 per group) or intermittent hypoxia (5.7% O2 alternating with 21% O2 every 90 seconds, 12 daylight hours per day; n=12 per group). Behavioral testing consisting of a standard place-training reference memory task in the water maze revealed that ApoE+/+ and ApoE-/- mice exposed to intermittent hypoxia were found to require significantly longer times (latency) and distances (pathlength) to locate the hidden platform (P hypoxia-exposed ApoE-/- mice were impaired on the final two days of training (P E2 and malondiadehyde concentrations were present in hippocampal brain tissues following intermittent hypoxia but were significantly higher in ApoE-/- mice (P breathing and may underlie the increased prevalence of Apolipoprotein E4 in patients with sleep-disordered breathing.

  1. Selection on alleles affecting human longevity and late-life disease: the example of apolipoprotein E.

    Directory of Open Access Journals (Sweden)

    Fotios Drenos

    2010-04-01

    Full Text Available It is often claimed that genes affecting health in old age, such as cardiovascular and Alzheimer diseases, are beyond the reach of natural selection. We show in a simulation study based on known genetic (apolipoprotein E and non-genetic risk factors (gender, diet, smoking, alcohol, exercise that, because there is a statistical distribution of ages at which these genes exert their influence on morbidity and mortality, the effects of selection are in fact non-negligible. A gradual increase with each generation of the epsilon2 and epsilon3 alleles of the gene at the expense of the epsilon4 allele was predicted from the model. The epsilon2 allele frequency was found to increase slightly more rapidly than that for epsilon3, although there was no statistically significant difference between the two. Our result may explain the recent evolutionary history of the epsilon 2, 3 and 4 alleles of the apolipoprotein E gene and has wider relevance for genes affecting human longevity.

  2. Association of apolipoprotein E polymorphism in late-onset Alzheimer's disease and vascular dementia in Brazilians

    Directory of Open Access Journals (Sweden)

    D.R.S. Souza

    2003-07-01

    Full Text Available The genetic basis for dementias is complex. A common polymorphism in the apolipoprotein E (APOE gene is considered to be the major risk factor in families with sporadic and late-onset Alzheimer's disease as well as in the general population. The distribution of alleles and genotypes of the APOE gene in late-onset Alzheimer's disease (N = 68, other late-life dementias (N = 39, and in cognitively normal controls (N = 58 was determined, as also was the risk for Alzheimer's disease associated with the epsilon4 allele. Peripheral blood samples were obtained from a total of 165 individuals living in Brazil aged 65-82 years. Genomic DNA was amplified by the polymerase chain reaction and the products were digested with HhaI restriction enzyme. APOE epsilon2 frequency was considerably lower in the Alzheimer's disease group (1%, and the epsilon3 allele and epsilon3/epsilon3 genotype frequencies were higher in the controls (84 and 72%, respectively as were the epsilon4 allele and epsilon3/epsilon4 genotype frequencies in Alzheimer's disease (25 and 41%, respectively. The higher frequency of the epsilon4 allele in Alzheimer's disease confirmed its role as a risk factor, while epsilon2 provided a weak protection against development of the disease. However, in view of the unexpectedly low frequency of the epsilon4 allele, additional analyses in a more varied Brazilian sample are needed to clarify the real contribution of apolipoprotein E to the development of Alzheimer's disease in this population.

  3. Different β-alanine dimeric forms in trifluoromethanesulfonic acid salts. XRD and vibrational studies

    Science.gov (United States)

    Wołoszyn, Łukasz; Ilczyszyn, Maria M.

    2018-03-01

    Two new crystalline salts: β-alaninium trifluoromethanesulfonate (β-AlaOTf) and bis(β-alanine) trifluoromethanesulfonate (β-2AlaOTf) were obtained. The former one contains diprotonated β-alanine dimer, the latter one monoprotonated β-alanine dimer. Both compounds were studied by single crystal XRD, vibrational (IR and Raman) spectroscopy and calorimetric method. The quantum-mechanical calculations (DFT/B3LYP/6-311 ++G(2d,2p)) for the diprotonated dimer were carried out. The β-AlaOTf salt crystallizes in the P 1 bar space group of triclinic system (Z = 2), the β-2AlaOTf in the P21/m space group of monoclinic system (Z = 2). The vibrational data for the studied compounds are discussed in relation to their crystal structure, and provide insight into the character of hydrogen bonds and β-alanine protonation. The studied crystals do not exhibit phase transitions in the solid state.

  4. Computational Design of Apolipoprotein E4 Inhibitors for Alzheimer’s Disease Therapy from Traditional Chinese Medicine

    Directory of Open Access Journals (Sweden)

    Hung-Jin Huang

    2014-01-01

    Full Text Available Apolipoprotein E4 (Apo E4 is the major genetic risk factor in the causation of Alzheimer’s disease (AD. In this study we utilize virtual screening of the world’s largest traditional Chinese medicine (TCM database and investigate potential compounds for the inhibition of ApoE4. We present the top three TCM candidates: Solapalmitine, Isodesacetyluvaricin, and Budmunchiamine L5 for further investigation. Dynamics analysis and molecular dynamics (MD simulation were used to simulate protein-ligand complexes for observing the interactions and protein variations. Budmunchiamine L5 did not have the highest score from virtual screening; however, the dynamics pose is similar to the initial docking pose after MD simulation. Trajectory analysis reveals that Budmunchiamine L5 was stable over all simulation times. The migration distance of Budmunchiamine L5 illustrates that docked ligands are not variable from the initial docked site. Interestingly, Arg158 was observed to form H-bonds with Budmunchiamine L5 in the docking pose and MD snapshot, which indicates that the TCM compounds could stably bind to ApoE4. Our results show that Budmunchiamine L5 has good absorption, blood brain barrier (BBB penetration, and less toxicity according to absorption, distribution, metabolism, excretion, and toxicity (ADMET prediction and could, therefore, be safely used for developing novel ApoE4 inhibitors.

  5. Apolipoprotein E4 influences growth and cognitive responses to micronutrient supplementation in shantytown children from northeast Brazil

    Directory of Open Access Journals (Sweden)

    Sumeet S Mitter

    2012-01-01

    Full Text Available OBJECTIVE: Apolipoprotein E4 may benefit children during early periods of life when the body is challenged by infection and nutritional decline. We examined whether apolipoprotein E4 affects intestinal barrier function, improving short-term growth and long-term cognitive outcomes in Brazilian shantytown children. METHODS: A total of 213 Brazilian shantytown children with below-median height-for-age z-scores (HAZ received 200,000 IU of retinol (every four months, zinc (40 mg twice weekly, or both for one year, with half of each group receiving glutamine supplementation for 10 days. Height-for-age z-scores, weight-for-age z-scores, weight-forheight z-scores, and lactulose:mannitol ratios were assessed during the initial four months of treatment. An average of four years (range 1.4-6.6 later, the children underwent cognitive testing to evaluate non-verbal intelligence, coding, verbal fluency, verbal learning, and delayed verbal learning. Apolipoprotein E4 carriage was determined by PCR analysis for 144 children. RESULTS: Thirty-seven children were apolipoprotein E4(+, with an allele frequency of 13.9%. Significant associations were found for vitamin A and glutamine with intestinal barrier function. Apolipoprotein E4(+ children receiving glutamine presented significant positive Pearson correlations between the change in height-for-age z-scores over four months and delayed verbal learning, along with correlated changes over the same period in weight-for-age z-scores and weight-for-height z-scores associated with non-verbal intelligence quotients. There was a significant correlation between vitamin A supplementation of apolipoprotein E4(+ children and improved delta lactulose/mannitol. Apolipoprotein E4(- children, regardless of intervention, exhibited negative Pearson correlations between the change in lactulose-to-mannitol ratio over four months and verbal learning and non-verbal intelligence. CONCLUSIONS: During development, apolipoprotein E4 may

  6. Plasma lipid oxidation predicts atherosclerotic status better than cholesterol in diabetic apolipoprotein E deficient mice

    DEFF Research Database (Denmark)

    Petersen, Karen Ekkelund; Lykkesfeldt, Jens; Raun, Kirsten

    2017-01-01

    Increased levels of oxidative stress have been suggested to play a detrimental role in the development of diabetes-related vascular complications. Here, we investigated whether the concentration of malondialdehyde, a marker of lipid oxidation correlated to the degree of aortic plaque lesions...... in a proatherogenic diabetic mouse model. Three groups of apolipoprotein E knockout mice were studied for 20 weeks, a control, a streptozotocin-induced diabetic, and a diabetic enalapril-treated group. Enalapril was hypothesized to lower oxidative stress level and thus the plaque burden. Both diabetic groups were...... significantly different from the control group as they had higher blood glucose, HbA1c, total cholesterol, low-density lipoprotein, very low-density lipoprotein, together with a lower high-density lipoprotein concentration and body weight. Animals in the diabetic group had significantly higher plaque area...

  7. Apolipoproteins E and CIII interact to regulate HDL metabolism and coronary heart disease risk

    DEFF Research Database (Denmark)

    Morton, Allyson M; Koch, Manja; Mendivil, Carlos O

    2018-01-01

    BACKGROUND: Subspecies of HDL contain apolipoprotein E (apoE) and/or apoCIII. Both proteins have properties that could affect HDL metabolism. The relation between HDL metabolism and risk of coronary heart disease (CHD) is not well understood. METHODS: Eighteen participants were given a bolus...... infusion of [D3]L-leucine to label endogenous proteins on HDL. HDL was separated into subspecies containing apoE and/or apoCIII and then into 4 sizes. Metabolic rates for apoA-I in HDL subspecies and sizes were determined by interactive modeling. The concentrations of apoE in HDL that contain or lack apo......CIII were measured in a prospective study in Denmark including 1,949 incident CHD cases during 9 years. RESULTS: HDL containing apoE but not apoCIII is disproportionately secreted into the circulation, actively expands while circulating, and is quickly cleared. These are key metabolic steps in reverse...

  8. Association of Apolipoprotein E Polymorphism with Ischemic Stroke Subtypes in Taiwan

    Directory of Open Access Journals (Sweden)

    Chiou-Lian Lai

    2007-10-01

    Full Text Available The aim of this study was to clarify whether the apolipoprotein E gene (APOE is related to ischemic stroke subtypes in Taiwan's Chinese population. Using the classification of Cerebrovascular Diseases III, 143 patients with lacunar infarction, 114 patients with atherothrombotic infarction, and 112 healthy controls were enrolled. APOE genotype was determined using polymerase chain reaction. Regarding the distribution of APOE genotypes, the frequency of ϵ3/ϵ4 genotypes in lacunar patients was significantly different from that in control subjects, by logistic regression, using ϵ3/ϵ3 as a reference group. There was no significant difference between atherothrombotic patients and the control group in the distribution of APOE genotypes or alleles. The present finding suggests that there is a probable association between ϵ3/ϵ4 genotype and lacunar infarcts, but not atherothrombotic infarcts. This indicates that genetic factors may play a role, at least partially, in lacunar infarction in Taiwan's Chinese population.

  9. Analysis of the interaction of platelet collagen receptor glycoprotein VI (GPVI) with collagen. A dimeric form of GPVI, but not the monomeric form, shows affinity to fibrous collagen.

    Science.gov (United States)

    Miura, Yoshiki; Takahashi, Tsuyoshi; Jung, Stephanie M; Moroi, Masaaki

    2002-11-29

    Glycoprotein VI (GPVI) is a platelet-specific glycoprotein that has been indicated to react with collagen and activate platelets. Its structure was recently identified by cDNA cloning (Clemetson, J. M., Polgar, J., Magnenat, E., Wells, T. N., and Clemetson, K. J. (1999) J. Biol. Chem. 274, 29019-29024). However, the mechanism of the interaction between collagen and GPVI has not been analyzed in detail because both collagen and GPVI are insoluble molecules. In this study, we expressed the extracellular domain of GPVI as soluble forms as follows: the monomeric form (GPVIex) and the dimeric form of GPVI fused with the human immunoglobulin Fc domain (GPVI-Fc(2)). Purified GPVIex strongly inhibited convulxin (Cvx)-induced platelet aggregation but only weakly inhibited that induced by collagen-related peptide. However, only GPVI-Fc(2), and not GPVIex, inhibited collagen-induced platelet aggregation. The dimeric form of GPVI exhibits high affinity for collagen, as concluded from measurements of GPVI binding to immobilized collagen by both the enzyme-linked immunosorbent assay and surface plasmon resonance methods. GPVI-Fc(2) bound to the surface of immobilized collagen with a dissociation constant (K(D)) of 5.76 x 10(-7) m, but the binding of GPVIex was too weak to allow estimation of this parameter. Cvx did not inhibit the binding of dimeric GPVI to collagen, indicating that the binding site of GPVI to collagen was different from that to Cvx. Taken together, our data indicate that the high affinity binding site for collagen is composed from two chains of GPVI. Furthermore, they suggest that the binding sites for Cvx are different from the collagen-binding sites and do not need to be formed by two GPVI molecules. Because dimeric GPVI is the only form that shows high affinity to fibrous collagen, our results indicate that GPVI would be present as a dimeric form on the platelet. Moreover, surface plasmon resonance indicated that there is no detectable interaction between

  10. High-salt diet combined with elevated angiotensin II accelerates atherosclerosis in apolipoprotein E-deficient mice

    DEFF Research Database (Denmark)

    Johansson, Maria E; Bernberg, Evelina; Andersson, Irene J

    2009-01-01

    to atherosclerosis. METHODS: Apolipoprotein E-deficient (ApoE-/-) mice received standard or high-salt diet (8%) alone or in combination with fixed angiotensin II (Ang II) infusion (0.5 microg/kg per min). BP was measured using telemetry, and plaque burden was assessed in the thoracic aorta and innominate artery. We...

  11. Lipid profiles reflecting high and low risk for coronary heart disease: contribution of apolipoprotein E polymorphism and lifestyle.

    NARCIS (Netherlands)

    Boer, J.M.A.; Feskens, E.J.M.; Schouten, E.G.; Havekes, L.M.; Seidell, J.C.; Kromhout, D.

    1998-01-01

    To elucidate the role of modifiable factors and the apolipoprotein E polymorphism in explaining lipid profiles reflecting low, average and high risk for coronary heart disease, we selected subjects from a large population-based study. Subjects with low total cholesterol (TC) (<15th percentile)

  12. Altered lipid metabolism in apolipoprotein E-deficient mice does not affect cholesterol balance across the liver

    NARCIS (Netherlands)

    Kuipers, F; vanRee, JM; Hofker, MH; Wolters, H; Veld, GI; Havinga, R; Vonk, RJ; Princen, HMG; Havekes, LM

    Adaptation of cholesterol and bile acid synthesis and of biliary cholesterol secretion represent key metabolic responses to maintain cholesterol homeostasis and have been suggested to be influenced by apolipoprotein E (apoE) phenotype in humans, We have investigated hepatic metabolism and secretion

  13. Prevalence of the apolipoprotein E ε4 allele in amyloid β positive subjects across the spectrum of Alzheimer's disease

    DEFF Research Database (Denmark)

    Mattsson, Niklas; Groot, Colin; Jansen, Willemijn J

    2018-01-01

    INTRODUCTION: Apolipoprotein E (APOE) ε4 is the major genetic risk factor for Alzheimer's disease (AD), but its prevalence is unclear because earlier studies did not require biomarker evidence of amyloid β (Aβ) pathology. METHODS: We included 3451 Aβ+ subjects (853 AD-type dementia, 1810 mild cog...

  14. Apolipoprotein E phenotype is not related to late-life depression in a population-based sample

    NARCIS (Netherlands)

    Schmand, B.; Hooijer, C.; Jonker, C.; Lindeboom, J.; Havekes, L. M.

    1998-01-01

    Apolipoprotein E (ApoE) allele frequencies were examined in a population-based sample (n = 475: age range 65-84 years: Amsterdam Study of the Elderly). The relation of ApoE epsilon 4 with dementia and with various types of late-life depression was studied. Depression was measured with the Geriatric

  15. Role of apolipoprotein E polymorphism as a prognostic marker in traumatic brain injury and neurodegenerative disease: a critical review.

    Science.gov (United States)

    Maiti, Tanmoy Kumar; Konar, Subhas; Bir, Shyamal; Kalakoti, Piyush; Bollam, Papireddy; Nanda, Anil

    2015-11-01

    OBJECT The difference in course and outcome of several neurodegenerative conditions and traumatic injuries of the nervous system points toward a possible role of genetic and environmental factors as prognostic markers. Apolipoprotein E (Apo-E), a key player in lipid metabolism, is recognized as one of the most powerful genetic risk factors for dementia and other neurodegenerative diseases. In this article, the current understanding of APOE polymorphism in various neurological disorders is discussed. METHODS The English literature was searched for various studies describing the role of APOE polymorphism as a prognostic marker in neurodegenerative diseases and traumatic brain injury. The wide ethnic distribution of APOE polymorphism was discussed, and the recent meta-analyses of role of APOE polymorphism in multiple diseases were analyzed and summarized in tabular form. RESULTS Results from the review of literature revealed that the distribution of APOE is varied in different ethnic populations. APOE polymorphism plays a significant role in pathogenesis of neurodegeneration, particularly in Alzheimer's disease. APOE ε4 is considered a marker for poor prognosis in various diseases, but APOE ε2 rather than APOE ε4 has been associated with cerebral amyloid angiopathy-related bleeding and sporadic Parkinson's disease. The role of APOE polymorphism in various neurological diseases has not been conclusively elucidated. CONCLUSIONS Apo-E is a biomarker for various neurological and systemic diseases. Therefore, while analyzing the role of APOE polymorphism in neurological diseases, the interpretation should be done after adjusting all the confounding factors. A continuous quest to look for associations with various neurological diseases and wide knowledge of available literature are required to improve the understanding of the role of APOE polymorphism in these conditions and identify potential therapeutic targets.

  16. Evidence for major gene inheritance of Alzheimer disease in families of patients with and without Apolipoprotein E {epsilon}4

    Energy Technology Data Exchange (ETDEWEB)

    Rao, V.S.; Auerbach, S.A.; Farrer, L.A. [Boston Univ. School of Medicine, MA (United States)] [and others

    1996-09-01

    Apolipoprotein E (APOE) genotype is the single most important determinant to the common form of Alzheimer disease (AD) yet identified. Several studies show that family history of AD is not entirely accounted for by APOE genotype. Also, there is evidence for an interaction between APOE genotype and gender. We carried out a complex segregation analysis in 636 nuclear families of consecutively ascertained and rigorously diagnosed probands in the Multi-Institutional Research in Alzheimer Genetic Epidemiology study in order to derive models of disease transmission which account for the influences of APOE genotype of the proband and gender. In the total group of families, models postulating sporadic occurrence, no major gene effect, random environmental transmission, and Mendelian inheritance were rejected. Transmission of AD in families of probands with at least one {epsilon}4 allele best fit a dominant model. Moreover, single gene inheritance best explained clustering of the disorder in families of probands lacking E4, but a more complex genetic model or multiple genetic models may ultimately account for risk in this group of families. Our results also suggest that susceptibility to AD differs between men and women regardless of the proband`s APOE status. Assuming a dominant model, AD appears to be completely penetrant in women, whereas only 62%-65% of men with predisposing genotypes develop AD. However, parameter estimates from the arbitrary major gene model suggests that AD is expressed dominantly in women and additively in men. These observations, taken together with epidemiologic data, are consistent with the hypothesis of an interaction between genes and other biological factors affecting disease susceptibility. 76 refs., 4 tabs.

  17. IQ, educational attainment, memory and plasma lipids: associations with apolipoprotein E genotype in 5995 children.

    Science.gov (United States)

    Taylor, Amy E; Guthrie, Philip A I; Smith, George Davey; Golding, Jean; Sattar, Naveed; Hingorani, Aroon D; Deanfield, John E; Day, Ian N M

    2011-07-15

    Apolipoprotein E (APOE) genotype (ε2/ε3/ε4: rs429358 ε4 allele; rs7412 ε2 allele) is strongly associated with both lipid levels and Alzheimer's disease. Although there is also evidence of milder cognitive impairment in later life in carriers of the APOE ε4 allele, there have been few studies investigating the impact of APOE genotype on cognitive function in children. We determined APOE genotype in 5995 children from the Avon Longitudinal Study of Parents and Children and investigated associations between APOE genotype and plasma lipids (at age 9), IQ (at age 8), memory (at ages 8 and 10), and performance in school attainment tests (at ages 7, 11, and 14). Observed genotype group counts were consistent with Hardy-Weinberg equilibrium (χ(2)p value = .84). There were strong relationships between APOE genotype and low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides, which follow the same patterns as in adults. There was no strong evidence to suggest that APOE genotype was associated with IQ (all p values ≥ .46), memory function (p ≥ .35), or school attainment test results (p ≥ .28). Although APOE genotype does have strong associations with lipid levels in childhood, there does not seem to be meaningful effects on cognitive performance, suggesting that any detrimental effects of the ε4 allele on cognitive function are not important until later life. Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  18. Hippocampal infusions of apolipoprotein E peptides induce long-lasting cognitive impairment.

    Science.gov (United States)

    Eddins, Donnie; Klein, Rebecca C; Yakel, Jerrel L; Levin, Edward D

    2009-04-29

    The inheritance of the varepsilon4 allele of apolipoprotein E (ApoE4) and cholinergic system dysfunction have long been associated with the pathology of Alzheimer's disease (AD). Recently, in vitro studies have established a direct link between ApoE and cholinergic function in that synthetic peptides containing segments of the ApoE protein (ApoE(133-149) and ApoE(141-148)) interact with alpha7 nicotinic acetylcholine receptors (nAChRs) in the hippocampus. This raises the possibility that ApoE peptides may contribute to cognitive impairment in AD in that the hippocampus plays a key role in cognitive functioning. To test this, we acutely infused ApoE peptides into the ventral hippocampus of female Sprague-Dawley rats and assessed the resultant effects on radial-arm maze choice accuracy over a period of weeks after the infusion. Local ventral hippocampal infusion of ApoE peptides caused significant cognitive impairment in radial-arm maze learning that persisted several weeks after the acute infusion. This persisting deficit may be an important model for understanding the relationship between ApoE protein-induced neurotoxicity and cognitive impairment as well as serve as a platform for the development of new therapies to avoid neurotoxicity and cognitive decline.

  19. Apolipoprotein E4 Impairs Neuronal Insulin Signaling by Trapping Insulin Receptor in the Endosomes.

    Science.gov (United States)

    Zhao, Na; Liu, Chia-Chen; Van Ingelgom, Alexandra J; Martens, Yuka A; Linares, Cynthia; Knight, Joshua A; Painter, Meghan M; Sullivan, Patrick M; Bu, Guojun

    2017-09-27

    Diabetes and impaired brain insulin signaling are linked to the pathogenesis of Alzheimer's disease (AD). The association between diabetes and AD-associated amyloid pathology is stronger among carriers of the apolipoprotein E (APOE) ε4 gene allele, the strongest genetic risk factor for late-onset AD. Here we report that apoE4 impairs neuronal insulin signaling in human apoE-targeted replacement (TR) mice in an age-dependent manner. High-fat diet (HFD) accelerates these effects in apoE4-TR mice at middle age. In primary neurons, apoE4 interacts with insulin receptor and impairs its trafficking by trapping it in the endosomes, leading to impaired insulin signaling and insulin-stimulated mitochondrial respiration and glycolysis. In aging brains, the increased apoE4 aggregation and compromised endosomal function further exacerbate the inhibitory effects of apoE4 on insulin signaling and related functions. Together, our study provides novel mechanistic insights into the pathogenic mechanisms of apoE4 and insulin resistance in AD. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Apolipoprotein e genotype, plasma cholesterol, and cancer: a Mendelian randomization study.

    LENUS (Irish Health Repository)

    Trompet, Stella

    2009-12-01

    Observational studies have shown an association between low plasma cholesterol levels and increased risk of cancer, whereas most randomized clinical trials involving cholesterol-lowering medications have not shown this association. Between 1997 and 2002, the authors assessed the association between plasma cholesterol levels and cancer risk, free from confounding and reverse causality, in a Mendelian randomization study using apolipoprotein E (ApoE) genotype. ApoE genotype, plasma cholesterol levels, and cancer incidence and mortality were measured during a 3-year follow-up period among 2,913 participants in the Prospective Study of Pravastatin in the Elderly at Risk. Subjects within the lowest third of plasma cholesterol level at baseline had increased risks of cancer incidence (hazard ratio (HR) = 1.90, 95% confidence interval (CI): 1.34, 2.70) and cancer mortality (HR = 2.03, 95% CI: 1.23, 3.34) relative to subjects within the highest third of plasma cholesterol. However, carriers of the ApoE2 genotype (n = 332), who had 9% lower plasma cholesterol levels than carriers of the ApoE4 genotype (n = 635), did not have increased risk of cancer incidence (HR = 0.86, 95% CI: 0.50, 1.47) or cancer mortality (HR = 0.70, 95% CI: 0.30, 1.60) compared with ApoE4 carriers. These findings suggest that low cholesterol levels are not causally related to increased cancer risk.

  1. Distinct neural correlates of episodic memory among apolipoprotein E alleles in cognitively normal elderly.

    Science.gov (United States)

    Shu, Hao; Shi, Yongmei; Chen, Gang; Wang, Zan; Liu, Duan; Yue, Chunxian; Ward, B Douglas; Li, Wenjun; Xu, Zhan; Chen, Guangyu; Guo, Qi-Hao; Xu, Jun; Li, Shi-Jiang; Zhang, Zhijun

    2018-02-02

    The apolipoprotein E (APOE) ε4 and ε2 alleles are acknowledged genetic factors modulating Alzheimer's disease (AD) risk and episodic memory (EM) deterioration in an opposite manner. Mounting neuroimaging studies describe EM-related brain activity differences among APOE alleles but remain limited in elucidating the underlying mechanism. Here, we hypothesized that the APOE ε2, ε3, and ε4 alleles have distinct EM neural substrates, as a manifestation of degeneracy, underlying their modulations on EM-related brain activity and AD susceptibility. To test the hypothesis, we identified neural correlates of EM function by correlating intrinsic hippocampal functional connectivity networks with neuropsychological EM performances in a voxelwise manner, with 129 cognitively normal elderly subjects (36 ε2 carriers, 44 ε3 homozygotes, and 49 ε4 carriers). We demonstrated significantly different EM neural correlates among the three APOE allele groups. Specifically, in the ε3 homozygotes, positive EM neural correlates were characterized in the Papez circuit regions; in the ε4 carriers, positive EM neural correlates involved the lateral temporal cortex, premotor cortex/sensorimotor cortex/superior parietal lobule, and cuneus; and in the ε2 carriers, negative EM neural correlates appeared in the bilateral frontopolar, posteromedial, and sensorimotor cortex. Further, in the ε4 carriers, the interaction between age and EM function occurred in the temporoparietal junction and prefrontal cortex. Our findings suggest that the underlying mechanism of APOE polymorphism modulations on EM function and AD susceptibility is genetically related to the neural degeneracy of EM function across APOE alleles.

  2. Longitudinal Trajectories of Cholesterol from Midlife through Late Life according to Apolipoprotein E Allele Status

    Directory of Open Access Journals (Sweden)

    Brian Downer

    2014-10-01

    Full Text Available Background: Previous research indicates that total cholesterol levels increase with age during young adulthood and middle age and decline with age later in life. This is attributed to changes in diet, body composition, medication use, physical activity, and hormone levels. In the current study we utilized data from the Framingham Heart Study Original Cohort to determine if variations in apolipoprotein E (APOE, a gene involved in regulating cholesterol homeostasis, influence trajectories of total cholesterol, HDL cholesterol, and total: HDL cholesterol ratio from midlife through late life. Methods: Cholesterol trajectories from midlife through late life were modeled using generalized additive mixed models and mixed-effects regression models. Results: APOE e2+ subjects had lower total cholesterol levels, higher HDL cholesterol levels, and lower total: HDL cholesterol ratios from midlife to late life compared to APOE e3 and APOE e4+ subjects. Statistically significant differences in life span cholesterol trajectories according to gender and use of cholesterol-lowering medications were also detected. Conclusion: The findings from this research provide evidence that variations in APOE modify trajectories of serum cholesterol from midlife to late life. In order to efficiently modify cholesterol through the life span, it is important to take into account APOE allele status.

  3. Apolipoprotein E epsilon4 allele and outcomes of traumatic spinal cord injury.

    Science.gov (United States)

    Jha, Amitabh; Lammertse, Daniel P; Coll, Joseph R; Charlifue, Susan; Coughlin, Christopher T; Whiteneck, Gale G; Worley, Gordon

    2008-01-01

    To test the hypothesis that apolipoprotein E (APOE) polymorphisms are associated with outcomes after spinal cord injury (SCI). Retrospective cohort study, from rehabilitation admission to discharge. Convenience sample of 89 persons with cervical SCI (C3-C8) treated from 1995 through 2003. Median age was 30 years (range 14-70); 67 were male (75%) and 83 were white (93%). American Spinal Injury Association (ASIA) motor and sensory scores, ASIA Impairment Scale (AIS), time from injury to rehabilitation admission, and length of stay (LOS) in rehabilitation. Subjects with an APOE epsilon4 allele (n = 15; 17%) had significantly less motor recovery during rehabilitation than did individuals without an epsilon4 allele (median 3.0 vs 5.5; P rehabilitation LOS (median 106 vs 89 days; P = 0.04), but better sensory-pinprick recovery (median 5.0 vs 2.0; P= 0.03). There were no significant differences by APOE epsilon4 allele status in sensory-light touch recovery, likelihood of improving AIS Grade, or time from injury to rehabilitation admission. APOE epsilon4 allele was associated with differences in neurological recovery and longer rehabilitation LOS. Genetic factors may be among the determinants of outcome after SCI and warrant further study.

  4. Human plasma lipid modulation in schistosomiasis mansoni depends on apolipoprotein E polymorphism.

    Directory of Open Access Journals (Sweden)

    Caíque Silveira Martins da Fonseca

    Full Text Available Schistosomiasis mansoni is a parasitic liver disease, which causes several metabolic disturbances. Here, we evaluate the influence of Apolipoprotein E (APOE gene polymorphism, a known modulator of lipid metabolism, on plasma lipid levels in patients with hepatosplenic schistosomiasis.Blood samples were used for APOE genotyping and to measure total cholesterol (TC, LDL-C, HDL-C and triglycerides. Schistosomiasis patients had reduced TC, LDL-C and triglycerides (25%, 38% and 32% lower, respectively; Pε3>ε4 was absent in patients (ε2 or ε4>ε3, and the increase in HDL-C of ε2 or ε4 patients compared to ε3 patients was not seen in the control groups.We confirm that human schistosomiasis causes dyslipidemia and report for the first time that certain changes in plasma lipid and lipoprotein levels depend on APOE gene polymorphism. Importantly, we also concluded that S. mansoni disrupts the expected regulation of plasma lipids by the different ApoE isoforms. This finding suggests ways to identify new metabolic pathways affected by schistosomiasis and also potential molecular targets to treat associated morbidities.

  5. Apolipoprotein E4 and sex affect neurobehavioral performance in primary school children.

    Science.gov (United States)

    Acevedo, Summer F; Piper, Brian J; Craytor, Michael J; Benice, Ted S; Raber, Jacob

    2010-03-01

    Apolipoprotein E4 (apoE4) and female sex are risk factors for developing Alzheimer's disease. It is unclear whether apoE4 contributes to behavioral function at younger ages. Standard neuropsychological assessments [intelligence quotient (IQ), attention, and executive function] and a test developed in this laboratory (Memory Island test of spatial learning and memory) were used to determine whether E4 and sex affect neuropsychological performance in healthy primary school children (age 7-10). A medical history was also obtained from the mother to determine whether negative birth outcomes were associated with apoE4. Mothers of apoE4+ children were more likely to report that their newborn was placed in an intensive care unit. A sex difference in birth weight was noted among apoE4- (males > females), but not apoE4+, offspring. Conversely, among apoE4+, but not apoE4- children, there was a sex difference in the Wechsler Abbreviated Scale of Intelligence (WASI) vocabulary score favoring boys. ApoE4- girls had better visual recall than apoE4+ girls or apoE4- boys on the Family Pictures test. Finally, apoE4+, unlike apoE4-, children did not show spatial memory retention during the Memory Island probe trial. Thus, apoE4 may affect neurobehavioral performance, particularly spatial memory, and antenatal health decades before any clinical expression of neurodegenerative processes.

  6. Cognitive functions, lipid profile, and Apolipoprotein E gene polymorphism in postmenopausal women

    Directory of Open Access Journals (Sweden)

    Iwona Bojar

    2015-05-01

    Full Text Available The objective of the study was investigation of the relationship between cognitive functions and lipid profile, BMI and change of body weight in postmenopausal women carriers of Apolipoprotein E gene polymorphisms (APOE. A group of 170 women was recruited to the study. The inclusion criteria were: minimum of two years after the last menstruation, FSH concentration 30 U/ml and no signs of dementia on the Montreal Cognitive Assessment (MoCA. A computerized battery of Central Nervous System Vital Signs (CNS VS was used for diagnostic cognitive functions. APOE genotype was performed by multiplex PCR. In blood plasma were determined: triglycerides, total cholesterol and its fractions: HDL cholesterol and LDL cholesterol. Statistical analysis was performed using two-way analysis of variance in STATISTICA software. In the postmenopausal women examined, the carrier state of APOE gene polymorphism was associated with the level of triglycerides, and results concerning three cognitive functions: executive functions, psychomotor speed, and cognitive flexibility. Loss of body weight in postmenopausal women was related with lower results in neurocognitive index and the majority of cognitive functions. The results concerning cognitive functions in postmenopausal women in the study were not significantly related with lipid profile. Significant differences were observed according to APOE gene polymorphism in correlations between LDL/HDL and CHOL/HDL ratios, and results in the processing speed and reaction time, as well as between the BMI and results in processing speed in the postmenopausal women examined.

  7. Plasma levels of apolipoprotein-E in residents of the European North of Russia.

    Science.gov (United States)

    Kaneva, Anastasiya M; Bojko, Evgeny R; Potolitsyna, Natalya N; Odland, Jon O

    2013-03-27

    Apolipoprotein-E (apoE) is one of the metabolically active apoproteins and plays an important role in lipid metabolism. However, there are no data on levels of apoE in residents of the North in spite of the fact that specific features of lipid metabolism in the northerners are described. The present work was designed to study plasma levels of apoE in residents of the European North of Russia. A total of 937 native residents of the European North of Russia (463 men and 474 women) aged 13-60 years were included in the study. ApoE concentrations in the blood plasma were measured by immunoturbidimetric method. Plasma levels of apoE in residents of the European North of Russia were low. ApoE concentrations below the defined normal values were detected in 57.0% of the men and in 59.2% of the women. The mean plasma levels of apoE did not significantly differ in men and women (2.80 mg/dl vs 2.87 mg/dl). Plasma apoE concentrations in residents of the European North of Russia changed with age. Plasma levels of apoE decreased from 13 to 21 years in men and from 13 to 35 years in women and then increased in both sexes (p Russia shift towards lower values. Plasma levels of apoE below normal values were observed in approximately half of investigation subjects.

  8. Evolutionary analysis of apolipoprotein E by Maximum Likelihood and complex network methods

    Directory of Open Access Journals (Sweden)

    Leandro de Jesus Benevides

    Full Text Available Abstract Apolipoprotein E (apo E is a human glycoprotein with 299 amino acids, and it is a major component of very low density lipoproteins (VLDL and a group of high-density lipoproteins (HDL. Phylogenetic studies are important to clarify how various apo E proteins are related in groups of organisms and whether they evolved from a common ancestor. Here, we aimed at performing a phylogenetic study on apo E carrying organisms. We employed a classical and robust method, such as Maximum Likelihood (ML, and compared the results using a more recent approach based on complex networks. Thirty-two apo E amino acid sequences were downloaded from NCBI. A clear separation could be observed among three major groups: mammals, fish and amphibians. The results obtained from ML method, as well as from the constructed networks showed two different groups: one with mammals only (C1 and another with fish (C2, and a single node with the single sequence available for an amphibian. The accordance in results from the different methods shows that the complex networks approach is effective in phylogenetic studies. Furthermore, our results revealed the conservation of apo E among animal groups.

  9. Apolipoprotein E Gene Polymorphisms in Saudi Patients with Systemic Lupus Erythematosus

    Directory of Open Access Journals (Sweden)

    Hannan Al-Rayes

    2016-01-01

    Full Text Available Apolipoprotein E (APOE is a glycosylated protein with multiple biological properties. APOE gene polymorphism plays a central role in lipid metabolism and has recently been suggested to regulate inflammation. Our objective is to evaluate whether APOE polymorphism affects susceptibility to SLE. APOE genotyping was performed using ApoE StripAssay™ kit. Results indicated significantly higher frequencies of allele ∊4 and genotype ∊3/∊4 and lower frequencies of allele ∊3 and genotype ∊3/∊3 in SLE patients than controls. APOE ∊2 allele was found in three patients, whereas it was absent in controls. The frequencies of allele ∊4 and genotype ∊3/∊4 were significantly higher in SLE patients with renal involvement and those of alleles ∊2, ∊4 and genotypes ∊2/∊3, ∊3/∊4 were higher in patients with neuropsychiatric symptoms. It is concluded that APOE allele ∊4 is associated with susceptibility risk/clinical manifestations of SLE and ∊2 may increase its severity while ∊3 is protective for SLE in Saudis.

  10. Relation of apolipoprotein E polymorphism to lipid metabolism in obese children.

    Science.gov (United States)

    Parlier, G; Thomas, G; Bereziat, G; Fontaine, J L; Girardet, J P

    1997-05-01

    To determine whether the risk of obesity-associated dyslipidemia in children is influenced by apolipoprotein E (apoE) polymorphism, we studied 137 obese, nongenetically related children aged 2.2-14.4 y (mean age, 9.9 +/- 3.1 y) with a weight-for-height excess of 43.7 +/- 17.9%. The apoE genotype was determined by studying specific DNA restriction patterns. Total cholesterol, HDL-cholesterol, and triglycerides were assayed in plasma before dietary treatment initiation. ApoE allele and phenotype distributions were comparable to those reported in the Caucasian population at large. Fifty-five children (41%) had elevated lipid levels. Compared with obese children with the epsilon3 or epsilon4 allele, those with the epsilon2 allele were more likely to have hypertriglyceridemia (19.5% versus 52.9%, p < 0.05) and had a higher mean triglyceride level: children with the epsilon4 allele were more likely to have a LDL-cholesterol elevation (34.7% versus 13.4%, p < 0.05). Our data demonstrate that, even in childhood, obesity is associated with a marked increase in the risk of lipoprotein abnormalities and that the latter are influenced by apoE polymorphism.

  11. Association of apolipoprotein E polymorphism with plasma lipids and Alzheimer's disease in a Southern Brazilian population

    Directory of Open Access Journals (Sweden)

    de-Andrade F.M.

    2000-01-01

    Full Text Available Apolipoprotein E (protein: apo E; gene: APOE plays an important role in the multifactorial etiology of both Alzheimer's disease (AD and lipid level concentrations. The polymerase chain reaction (PCR was used to investigate the APOE gene polymorphism in 446 unrelated Caucasians, among them 23 AD patients, and 100 Afro-Brazilians living in Porto Alegre, Brazil. The frequencies of the APOE*2, APOE*3 and APOE*4 alleles were 0.075, 0.810 and 0.115 in Caucasians and 0.075, 0.700 and 0.225 in Afro-Brazilians, respectively (c2 = 8.72, P = 0.013. A highly significant association was observed between the APOE*4 allele and AD in this population-based sample. The APOE*4 frequency in AD patients (39% was about four times higher than in the general Caucasian population (11.5%. The influence of each of the three common APOE alleles on lipid traits was evaluated by the use of the average excess statistic. The E*2 allele is associated with lower levels of triglycerides and of total and non-HDL cholesterol in both men and women. Conversely, the E*4 allele is associated with higher levels of these traits in women only. The effect of APOE alleles was of greater magnitude in women.

  12. Meta-analysis of peripheral blood apolipoprotein E levels in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Chong Wang

    Full Text Available BACKGROUND: Peripheral blood Apolipoprotein E (ApoE levels have been proposed as biomarkers of Alzheimer's disease (AD, but previous studies on levels of ApoE in blood remain inconsistent. This meta-analysis was designed to re-examine the potential role of peripheral ApoE in AD diagnosis and its potential value as a candidate biomarker. METHODS: We conducted a systematic literature search of MEDLINE, EMBASE, the Cochrane library, and BIOSIS previews for case-control studies measuring ApoE levels in serum or plasma from AD subjects and healthy controls. The pooled weighted mean difference (WMD and 95% confidence interval (CI were used to estimate the association between ApoE levels and AD risk. RESULTS: Eight studies with a total of 2250 controls and 1498 AD cases were identified and analyzed. The pooled WMD from a random-effect model of AD participants compared with the healthy controls was -5.59 mg/l (95% CI: [-8.12, -3.06]. The overall pattern in WMD was not varied by characteristics of study, including age, country, assay method, publication year, and sample type. CONCLUSIONS: Our meta-analysis supports a lowered level of blood ApoE in AD patients, and indicates its potential value as an important risk factor for AD. Further investigation employing standardized assay for ApoE measurement are still warranted to uncover the precise role of ApoE in the pathophysiology of AD.

  13. Nanobody-Based Apolipoprotein E Immunosensor for Point-of-Care Testing.

    Science.gov (United States)

    Ren, Xiang; Yan, Junrong; Wu, Dan; Wei, Qin; Wan, Yakun

    2017-09-22

    Alzheimer's disease (AD) biomarkers can reflect the neurochemical indicators used to estimate the risk in clinical nephrology. Apolipoprotein E (ApoE) is an early biomarker for AD in clinical diagnosis. In this research, through bactrian camel immunization, lymphocyte isolation, RNA extraction, and library construction, ApoE-specific Nbs with high affinity were successfully separated from an immune phage display nanobody library. Herein, a colorimetric immunosensor was developed for the point-of-care testing of ApoE by layer-by-layer nanoassembly techniques and novel nanobodies (Nbs). Using highly oriented Nbs as the capture and detection antibodies, an on-site immunosensor was developed by detecting the mean gray value of fade color due to the glutaraldehyde@3-aminopropyltrimethoxysilane oxidation by H 2 O 2 . The detection limit of AopE is 0.42 pg/mL, and the clinical analysis achieves a good performance. The novel easily operated immunosensor may have potential application in the clinical diagnosis and real-time monitoring for AD.

  14. Gestational hyperlipidemia and acute pancreatitis with underlying partial lipoprotein lipase deficiency and apolipoprotein E3/E2 genotype.

    Science.gov (United States)

    Han, Dong Hee; Moh, In Ho; Kim, Doo-Man; Ihm, Sung Hee; Choi, Moon-Gi; Yoo, Hyung Joon; Hong, Eun-Gyoung

    2013-09-01

    We report the case of a patient who experienced extreme recurrent gestational hyperlipidemia. She was diagnosed with partial lipoprotein lipase (LPL) deficiency but without an associated LPL gene mutation in the presence of the apolipoprotein E3/2 genotype. This is the first reported case of extreme gestational hyperlipidemia with a partial LPL deficiency in the absence of an LPL gene mutation and the apolipoprotein E 3/2 genotype. She was managed with strict dietary control and medicated with omega-3 acid ethyl esters. A patient with extreme hyperlipidemia that is limited to the gestational period should be considered partially LPL-deficient. Extreme instances of hyperlipidemia increase the risk of acute pancreatitis, and the effect of parturition on declining plasma lipid levels can be immediate and dramatic. Therefore, decisions regarding the timing and route of delivery with extreme gestational hyperlipidemia are critical and should be made carefully.

  15. Protective activity ethanol extract of the fruits of Illicium verum against atherogenesis in apolipoprotein E knockout mice

    OpenAIRE

    Park, Sun Haeng; Sung, Yoon-Young; Nho, Kyoung Jin; Kim, Ho Kyoung

    2015-01-01

    Background Illicium verum Hook. fil. Illiciaceae (Illicium v.) has been traditionally used in herbal medicine for treating many inflammatory diseases, including skin inflammation and rheumatism. We investigated its use as a preventive agent against inflammatory and vascular diseases in a murine model of atherosclerosis using apolipoprotein E-knockout (ApoE ?/?) mice fed on a high-fat diet (HFD). Methods We investigated the effect of Illicium v. on cytotoxicity, NF-?B activity, and adhesion mo...

  16. Apolipoprotein E deficiency increases remnant lipoproteins and accelerates progressive atherosclerosis, but not xanthoma formation, in gene modified minipigs

    DEFF Research Database (Denmark)

    Shim, Jeong; Poulsen, Christian Bo; Hagensen, Mette K.

    2017-01-01

    Summary: Deficiency of apolipoprotein E (APOE) causes familial dysbetalipoproteinemia in humans resulting in a higher risk of atherosclerotic disease. In mice, APOE deficiency results in a severe atherosclerosis phenotype, but it is unknown to what extent this is unique to mice. In this study, APOE...... progressive atherosclerosis but not xanthoma formation. This indicates that remnant lipoproteinemia does not induce early lesions but is atherogenic in pre-existing atherosclerosis....

  17. Leisure activities, apolipoprotein E e4 status, and the risk of dementia.

    Science.gov (United States)

    Yang, Sheng-Ying; Weng, Pei-Hsuan; Chen, Jen-Hau; Chiou, Jeng-Min; Lew-Ting, Chih-Yin; Chen, Ta-Fu; Sun, Yu; Wen, Li-Li; Yip, Ping-Keung; Chu, Yi-Min; Chen, Yen-Ching

    2015-12-01

    Leisure activities have been associated with a decreased risk of dementia. However, to date, no study has explored how apolipoprotein E (ApoE) e4 status or vascular risk factors modified the association between leisure activities and dementia risks. This case-control study recruited patients (age ≥ 60 years) with Alzheimer's disease (AD; n = 292) and vascular dementia (VaD; n = 144) and healthy controls (n = 506) from three teaching hospitals in Taiwan between 2007 and 2010. Information on patient's leisure activities were obtained through a questionnaire. Conditional logistic regression models were used to assess the association of leisure activities and ApoE e4 status with the risk of dementia. High-frequency physical activity was associated with a decreased risk of AD [adjusted odds ratio (AOR) = 0.45], and the results become more evident among ApoE e4 carriers with AD (AOR = 0.30) and VaD (AOR = 0.26). Similar findings were observed for cognitive (AOR = 0.42) and social activities (AOR = 0.55) for AD. High-frequency physical, cognitive, and social activities were associated with a decreased risk of VaD (AOR = 0.29-0.60). Physical and social activities significantly interacted with each other on the risk of VaD (pinteraction = 0.04). Physical activity consistently protects against AD and VaD. Significant interactions were identified across different types of leisure activities in lowering dementia risk. Copyright © 2014. Published by Elsevier B.V.

  18. Atherosclerotic plaque disruption induced by stress and lipopolysaccharide in apolipoprotein E knockout mice.

    Science.gov (United States)

    Ni, Mei; Wang, Yan; Zhang, Mei; Zhang, Peng Fei; Ding, Shi Fang; Liu, Chun Xi; Liu, Xiao Ling; Zhao, Yu Xia; Zhang, Yun

    2009-05-01

    To establish an animal model with disruptions of atherosclerotic plaques, 96 male apolipoprotein E knockout (apoE(-/-)) mice were randomly divided into stress, lipopolysaccharide (LPS), stress+LPS, and control groups (n = 24 each). All mice were fed a high-fat diet throughout the experiment, and carotid atherosclerotic lesions were induced by placement of a constrictive perivascular collar. Four weeks after surgery, mice in the LPS and stress+LPS groups were intraperitoneally injected with LPS (1 mg/kg twice per week for 8 wk). Eight weeks after surgery, mice in the stress and stress+LPS groups were treated with intermittent physical stress (electric foot shock and noise stimulation) for 4 wk. Morphological analysis revealed a plaque disruption rate of 16.7% in control, 34.8% in LPS, 54.2% in stress, and 60.9% in stress+LPS groups. The disruption rates in stress and stress+LPS groups were both significantly higher than those of controls (P = 0.007 and P = 0.002, respectively). Luminal thrombosis secondary to plaque disruption was observed only in the stress+LPS group. Both stress and LPS stimulation significantly decreased fibrous cap thickness and increased macrophage and lipid contents in plaques. Moreover, the combination of stress and LPS stimulation further lowered cap thickness and enhanced accumulation of macrophages and expression of inflammatory cytokines and matrix metalloproteinases. Stress activated the sympathetic nervous system, as manifested by increased blood pressure and flow velocity. Plasma fibrinogen levels were remarkably elevated in the stress and stress+LPS groups. In conclusion, stress- and LPS-costimulated apoE(-/-) mice provide a useful model for studies of plaque vulnerability and interventions.

  19. Apolipoprotein E isoform dependently affects Tat-mediated HIV-1 LTR transactivation.

    Science.gov (United States)

    Khan, Nabab; Datta, Gaurav; Geiger, Jonathan D; Chen, Xuesong

    2018-03-20

    Apolipoprotein E (ApoE) is the major carrier protein that mediates the transport and delivery of cholesterol and other lipids in the brain. Three isoforms of ApoE (ApoE2, ApoE3, ApoE4) exist in humans, and their relative expression levels impact HIV-1 infection, HIV-1/AIDS disease progression, and cognitive decline associated with HIV-1-associated neurocognitive disorder. Because HIV-1 Tat, a viral protein essential for HIV-1 replication, can bind to low-density lipoprotein receptor-related protein 1 (LRP1) that controls ApoE uptake in the brain, we determined the extent to which different isoforms of ApoE affected Tat-mediated HIV-1 LTR transactivation. Using U87MG glioblastoma cells expressing LTR-driven luciferase, we determined the extent to which LRP1 as well as ApoE2, ApoE3, and ApoE4 affected Tat-mediated HIV-1 LTR transactivation. A specific LRP1 antagonist and siRNA knockdown of LRP1 both restricted significantly Tat-mediated LTR transactivation. Of the three ApoEs, ApoE4 was the least potent and effective at preventing HIV-1 Tat internalization and at decreasing Tat-mediated HIV-1 LTR transactivation. Further, Tat-mediated LTR transactivation was attenuated by an ApoE mimetic peptide, and ApoE4-induced restriction of Tat-mediated LTR transactivation was potentiated by an ApoE4 structure modulator that changes ApoE4 into an ApoE3-like phenotype. These findings help explain observed differential effects of ApoEs on HIV-1 infectivity and the prevalence of HAND in people living with HIV-1 infection and suggest that ApoE mimetic peptides and ApoE4 structure modulator might be used as a therapeutic strategy against HIV-1 infection and associated neurocognitive disorders.

  20. Functional network endophenotypes unravel the effects of apolipoprotein E epsilon 4 in middle-aged adults.

    Directory of Open Access Journals (Sweden)

    Joseph S Goveas

    Full Text Available Apolipoprotein E-ε4 (APOE-ε4 accentuates memory decline, structural volume loss and cerebral amyloid deposition in cognitively healthy adults. We investigated whether APOE-ε4 carriers will show disruptions in the intrinsic cognitive networks, including the default mode (DMN, executive control (ECN and salience (SN networks, relative to noncarriers in middle-aged healthy adults; and the extent to which episodic-memory performance is related to the altered functional connectivity (Fc in these networks. Resting-state functional connectivity MRI (R-fMRI was used to measure the differences in the DMN, ECN and SN Fc between 20 APOE-ε4 carriers and 26 noncarriers. Multiple linear regression analyses were performed to determine the relationship between episodic-memory performance and Fc differences in the three resting-state networks across all subjects. There were no significant differences in the demographic and neuropsychological characteristics and the gray-matter volumes in the carriers and noncarriers. While mostly diminished DMN and ECN functional connectivities were seen, enhanced connections to the DMN structures were found in the SN in ε4 carriers. Altered DMN and ECN were associated with episodic memory performance. Significant Fc differences in the brain networks implicated in cognition were seen in middle-aged individuals with a genetic risk for AD, in the absence of cognitive decline and gray-matter atrophy. Prospective studies are essential to elucidate the potential of R-fMRI technique as a biomarker for predicting conversion from normal to early AD in healthy APOE-ε4 carriers.

  1. Kaempferol regulates OPN–CD44 pathway to inhibit the atherogenesis of apolipoprotein E deficient mice

    International Nuclear Information System (INIS)

    Xiao, Hong-Bo; Lu, Xiang-Yang; Sun, Zhi-Liang; Zhang, Heng-Bo

    2011-01-01

    Recent studies show that osteopontin (OPN) and its receptor cluster of differentiation 44 (CD44) are two pro-inflammatory cytokines contributing to the development of atherosclerosis. The objective of this study was to explore the inhibitory effect of kaempferol, a naturally occurring flavonoid compound, on atherogenesis and the mechanisms involved. The experiments were performed in aorta and plasma from C57BL/6J control and apolipoprotein E-deficient (ApoE −/− ) mice treated or not with kaempferol (50 or 100 mg/kg, intragastrically) for 4 weeks. Kaempferol treatment decreased atherosclerotic lesion area, improved endothelium-dependent vasorelaxation, and increased the maximal relaxation value concomitantly with decrease in the half-maximum effective concentration, plasma OPN level, aortic OPN expression, and aortic CD44 expression in ApoE −/− mice. In addition, treatment with kaempferol also significantly decreased reactive oxygen species production in mice aorta. The present results suggest that kaempferol regulates OPN–CD44 pathway to inhibit the atherogenesis of ApoE −/− mice. -- Graphical abstract: Kaempferol regulates OPN–CD44 pathway to inhibit the atherogenesis of ApoE −/− mice. Highlights: ► OPN–CD44 pathway plays a critical role in the development of atherosclerosis. ► We examine lesion area, OPN and CD44 changes after kaempferol treatment. ► Kaempferol treatment decreased atherosclerotic lesion area in ApoE −/− mice. ► Kaempferol treatment decreased aortic OPN and CD44 expressions in ApoE −/− mice. ► Kaempferol regulates OPN–CD44 pathway to inhibit the atherogenesis.

  2. Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of apolipoprotein E deficient mice

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Hong-Bo, E-mail: xhbzhb@yahoo.com [College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128 (China); Lu, Xiang-Yang; Sun, Zhi-Liang [Hunan Agricultural University, Changsha 410128 (China); Zhang, Heng-Bo [Furong District Red Cross Hospital, Changsha 410126 (China)

    2011-12-15

    Recent studies show that osteopontin (OPN) and its receptor cluster of differentiation 44 (CD44) are two pro-inflammatory cytokines contributing to the development of atherosclerosis. The objective of this study was to explore the inhibitory effect of kaempferol, a naturally occurring flavonoid compound, on atherogenesis and the mechanisms involved. The experiments were performed in aorta and plasma from C57BL/6J control and apolipoprotein E-deficient (ApoE{sup -/-}) mice treated or not with kaempferol (50 or 100 mg/kg, intragastrically) for 4 weeks. Kaempferol treatment decreased atherosclerotic lesion area, improved endothelium-dependent vasorelaxation, and increased the maximal relaxation value concomitantly with decrease in the half-maximum effective concentration, plasma OPN level, aortic OPN expression, and aortic CD44 expression in ApoE{sup -/-} mice. In addition, treatment with kaempferol also significantly decreased reactive oxygen species production in mice aorta. The present results suggest that kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of ApoE{sup -/-} mice. -- Graphical abstract: Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of ApoE{sup -/-} mice. Highlights: Black-Right-Pointing-Pointer OPN-CD44 pathway plays a critical role in the development of atherosclerosis. Black-Right-Pointing-Pointer We examine lesion area, OPN and CD44 changes after kaempferol treatment. Black-Right-Pointing-Pointer Kaempferol treatment decreased atherosclerotic lesion area in ApoE{sup -/-} mice. Black-Right-Pointing-Pointer Kaempferol treatment decreased aortic OPN and CD44 expressions in ApoE{sup -/-} mice. Black-Right-Pointing-Pointer Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis.

  3. Different associations of apolipoprotein E polymorphism with metabolic syndrome by sex in an elderly Chinese population.

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    Tao, Meng Hua; Liu, Jian Wei; LaMonte, Michael J; Liu, Jing; Wang, Lei; He, Yao; Li, Xiao Ying; Wang, Lu Ning; Ye, Ling

    2011-10-01

    The metabolic syndrome (MetS) is characterized by a cluster of metabolic disorders including abnormal lipid and lipoprotein metabolism. Apolipoprotein E (ApoE) is involved in the regulation of the metabolism of cholesterol, lipoproteins, and triglycerides. The common ApoE polymorphism has been found to be associated with cardiovascular disease and diabetes. This study evaluated the ApoE genetic polymorphism and its relation to MetS defined by the modified National Cholesterol Education Program and International Diabetes Federation criteria in a population-based cross-sectional survey of an elderly Chinese population in Beijing, China. Genotypes of 937 men and 1385 women were included in the study. All participants were measured for blood pressure, anthropometric measurements, and fasting concentrations of glucose, triglycerides, cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. We applied a logistic regression model to derive adjusted odds ratios (ORs) and their 95% confidence intervals. In this Chinese population, the ɛ2, ɛ3, and ɛ4 allele frequencies were 8.3%, 83.4%, and 8.3% for men and 8.7%, 82.9%, and 8.4% for women, respectively. In men, concentrations of fasting triglycerides were higher among the APOE2 and E4 subjects; and a lower level of high-density lipoprotein cholesterol was observed in the APOE4 group. There were approximately linear associations of low-density lipoprotein cholesterol levels with APOE genotype groups in both men and women. We observed that the ɛ4 allele was associated with a significantly increased OR of MetS defined by the modified National Cholesterol Education Program criteria in men (OR, 1.75; 95% confidence interval, 1.17-2.63). In summary, our data show that common polymorphism of ApoE gene is associated with the presence of MetS in an elderly Chinese population. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Endothelial surface layer degradation by chronic hyaluronidase infusion induces proteinuria in apolipoprotein E-deficient mice.

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    Marijn C Meuwese

    Full Text Available OBJECTIVE: Functional studies show that disruption of endothelial surface layer (ESL is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL through enzymatic degradation would affect vascular barrier properties in an atherogenic model. METHODS: Eight week old male apolipoprotein E deficient mice on Western-type diet for 10 weeks received continuous active or heat-inactivated hyaluronidase (10 U/hr, i.v. through an osmotic minipump during 4 weeks. Blood chemistry and anatomic changes in both macrovasculature and kidneys were examined. RESULTS: Infusion with active hyaluronidase resulted in decreased ESL (0.32±0.22 mL and plasma volume (1.03±0.18 mL compared to inactivated hyaluronidase (0.52±0.29 mL and 1.28±0.08 mL, p<0.05 respectively.Active hyaluronidase increased proteinuria compared to inactive hyaluronidase (0.27±0.02 vs. 0.15±0.01 µg/µg protein/creatinin, p<0.05 without changes in glomerular morphology or development of tubulo-interstitial inflammation. Atherosclerotic lesions in the aortic branches showed increased matrix production (collagen, 32±5 vs. 18±3%; glycosaminoglycans, 11±5 vs. 0.1±0.01%, active vs. inactive hyaluronidase, p<0.05. CONCLUSION: ESL degradation in apoE deficient mice contributes to reduced increased urinary protein excretion without significant changes in renal morphology. Second, the induction of compositional changes in atherogenic plaques by hyaluronidase point towards increased plaque vulnerability. These findings support further efforts to evaluate whether ESL restoration is a valuable target to prevent (micro vascular disease progression.

  5. Safrole-2',3'-oxide induces atherosclerotic plaque vulnerability in apolipoprotein E-knockout mice.

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    Su, Le; Zhang, Haiyan; Zhao, Jing; Zhang, Shangli; Zhang, Yun; Zhao, Baoxiang; Miao, Junying

    2013-02-27

    Safrole-2',3'-oxide (SFO) is the major electrophilic metabolite of safrole (4-allyl-1, 2-methylenedioxybenzene), a natural plant constituent found in essential oils of numerous edible herbs and spices and in food containing these herbs, such as pesto sauce, cola beverages and bologna sausages. The effects of SFO in mammalian systems, especially the cardiovascular system, are little known. Disruption of vulnerable atherosclerotic plaques in atherosclerosis, a chronic inflammatory disease, is the main cause of cardiovascular events. In this study, we investigated SFO-induced atherosclerotic plaque vulnerability (possibility of rupture) in apolipoprotein E-knockout (apoE(-/-)) mice. Lipid area in vessel wall reached 59.8% in high dose SFO (SFO-HD) treated group, which is only 31.2% in control group. SFO treatment changed the lesion composition to an unstable phenotype, increased the number of apoptotic cells in plaque and the endothelium in plaques was damaged after SFO treatment. Furthermore, compared with control groups, the plaque endothelium level of p75(NTR) was 3-fold increased and the liver level of p75(NTR) was 17.4-fold increased by SFO-HD. Meanwhile, the serum level of KC (a functional homolog of IL-8 and the main proinflammatory alpha chemokine in mice) in apoE(-/-) mice was up to 357pg/ml in SFO-HD treated group. Thus, SFO contributes to the instability of atherosclerotic plaque in apoE(-/-) mice through activating p75(NTR) and IL-8 and cell apoptosis in plaque. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Apolipoprotein E (APOE) ε4 and episodic memory decline in Alzheimer's disease: A review.

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    El Haj, Mohamad; Antoine, Pascal; Amouyel, Philippe; Lambert, Jean-Charles; Pasquier, Florence; Kapogiannis, Dimitrios

    2016-05-01

    A growing body of research has examined the relationship between episodic memory decline, the cognitive hallmark of Alzheimer's disease (AD), and the presence of Apolipoprotein E ε4 (APOE ε4) allele, a major genetic risk factor for the disease. Our review attempts to summarize and critically evaluate this literature. We performed a systematic search for studies assessing episodic memory in AD patients who were genotyped for APOE ε4 and identified fourteen papers. Although most of these papers reported significant relationships between APOE ε4 and episodic memory decline in AD, some papers did not confirm this relationship. Our review links this controversy to the conflicting literature about the effects of APOE ε4 on general cognitive functioning in AD. We identify several shortcoming and limitations of the research on the relationship between APOE ε4 and episodic memory in AD, such as small sample sizes, non-representative populations, lack of comparison of early-onset vs. late-onset disease, and lack of comparison among different genotypes that include APOE ε4 (i.e., zero, one, or two ε4 alleles). Another major shortcoming of the reviewed literature was the lack of comprehensive evaluation of episodic memory decline, since episodic memory was solely evaluated with regard to encoding and retrieval, omitting evaluation of core episodic features that decline in AD, such as context recall (e.g., how, where, and when an episodic event has occurred) and subjective experience of remembering (e.g., reliving, emotion and feeling during episodic recollection). Future research taking these limitations into consideration could illuminate the nature of the relationship between APOE ε4 and episodic memory decline in AD. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Differential action of glucocorticoids on apolipoprotein E gene expression in macrophages and hepatocytes.

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    Trusca, Violeta Georgeta; Fuior, Elena Valeria; Fenyo, Ioana Madalina; Kardassis, Dimitris; Simionescu, Maya; Gafencu, Anca Violeta

    2017-01-01

    Apolipoprotein E (apoE) has anti-atherosclerotic properties, being involved in the transport and clearance of cholesterol-rich lipoproteins as well as in cholesterol efflux from cells. We hypothesized that glucocorticoids may exert anti-inflammatory properties by increasing the level of macrophage-derived apoE. Our data showed that glucocorticoids increased apoE expression in macrophages in vitro as well as in vivo. Dexamethasone increased ~6 fold apoE mRNA levels in cultured peritoneal macrophages and RAW 264.7 cells. Administered to C57BL/6J mice, dexamethasone induced a two-fold increase in apoE expression in peritoneal macrophages. By contrast, glucocorticoids did not influence apoE expression in hepatocytes, in vitro and in vivo. Moreover, dexamethasone enhanced apoE promoter transcriptional activity in RAW 264.7 macrophages, but not in HepG2 cells, as tested by transient transfections. Analysis of apoE proximal promoter deletion mutants, complemented by protein-DNA interaction assays demonstrated the functionality of a putative glucocorticoid receptors (GR) binding site predicted by in silico analysis in the -111/-104 region of the human apoE promoter. In hepatocytes, GR can bind to their specific site within apoE promoter but are not able to modulate the gene expression. The modulatory blockade in hepatocytes is a consequence of partial involvement of transcription factors and other signaling molecules activated through MEK1/2 and PLA2/PLC pathways. In conclusion, our study indicates that glucocorticoids (1) differentially target apoE gene expression; (2) induce a significant increase in apoE level specifically in macrophages. The local increase of apoE gene expression in macrophages at the level of the atheromatous plaque may have therapeutic implications in atherosclerosis.

  8. Differential action of glucocorticoids on apolipoprotein E gene expression in macrophages and hepatocytes.

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    Violeta Georgeta Trusca

    Full Text Available Apolipoprotein E (apoE has anti-atherosclerotic properties, being involved in the transport and clearance of cholesterol-rich lipoproteins as well as in cholesterol efflux from cells. We hypothesized that glucocorticoids may exert anti-inflammatory properties by increasing the level of macrophage-derived apoE. Our data showed that glucocorticoids increased apoE expression in macrophages in vitro as well as in vivo. Dexamethasone increased ~6 fold apoE mRNA levels in cultured peritoneal macrophages and RAW 264.7 cells. Administered to C57BL/6J mice, dexamethasone induced a two-fold increase in apoE expression in peritoneal macrophages. By contrast, glucocorticoids did not influence apoE expression in hepatocytes, in vitro and in vivo. Moreover, dexamethasone enhanced apoE promoter transcriptional activity in RAW 264.7 macrophages, but not in HepG2 cells, as tested by transient transfections. Analysis of apoE proximal promoter deletion mutants, complemented by protein-DNA interaction assays demonstrated the functionality of a putative glucocorticoid receptors (GR binding site predicted by in silico analysis in the -111/-104 region of the human apoE promoter. In hepatocytes, GR can bind to their specific site within apoE promoter but are not able to modulate the gene expression. The modulatory blockade in hepatocytes is a consequence of partial involvement of transcription factors and other signaling molecules activated through MEK1/2 and PLA2/PLC pathways. In conclusion, our study indicates that glucocorticoids (1 differentially target apoE gene expression; (2 induce a significant increase in apoE level specifically in macrophages. The local increase of apoE gene expression in macrophages at the level of the atheromatous plaque may have therapeutic implications in atherosclerosis.

  9. Relevance of apolipoprotein E4 for the lipid profile of Brazilian patients with coronary artery disease

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    D.R.S. Souza

    2007-02-01

    Full Text Available Apolipoprotein E (apoE - e2, e3, e4 alleles plays a role in the regulation of lipid metabolism, with the e4 considered to be a risk factor for coronary artery disease (CAD. We aimed to evaluate the apoE polymorphisms in Brazilians with CAD and their influence on the lipid profile and other risk factors (hypertension, diabetes mellitus, smoking. Two hundred individuals were examined: 100 patients with atherosclerosis confirmed by coronary angiography and 100 controls. Blood samples were drawn to determine apoE polymorphisms and lipid profile. As expected, the e3 allele was prevalent in the CAD (0.87 and non-CAD groups (0.81; P = 0.099, followed by the e4 allele (0.09 and 0.14, respectively; P = 0.158. The e3/3 (76 and 78% and e3/4 (16 and 23% were the most common genotypes for patients and controls, respectively. The lipid profile was altered in patients compared to controls (P < 0.05, independently of the e4 allele. However, in the controls this allele was prevalent in individuals with elevated LDL-cholesterol levels only (odds ratio = 2.531; 95% CI = 1.028-6.232. The frequency of risk factors was higher in the CAD group (P < 0.05, but their association with the lipid profile was not demonstrable in e4 carriers. In conclusion, the e4 allele is not associated with CAD or lipid profile in patients with atherosclerosis. However, its frequency in the non-CAD group is associated with increased levels of LDL-cholesterol, suggesting an independent effect of the e4 allele on lipid profile when the low frequency of other risk factors in this group is taken into account.

  10. Apolipoprotein E4 frequencies in a Japanese population with Alzheimer's disease and dementia with Lewy bodies.

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    Seiju Kobayashi

    Full Text Available BACKGROUND: The apolipoprotein E (APOE ε4 allele has been reported to be a risk factor for Alzheimer's disease (AD and dementia with Lewy bodies (DLB. Previous neuropathological studies have demonstrated similar frequencies of the APOE ε4 allele in AD and DLB. However, the few ante-mortem studies on APOE allele frequencies in DLB have shown lower frequencies than post-mortem studies. One reason for this may be inaccuracy of diagnosis. We examined APOE genotypes in subjects with AD, DLB, and a control group using the latest diagnostic criteria and MRI, SPECT, and MIBG myocardial scintigraphy. METHODS: The subjects of this study consisted of 145 patients with probable AD, 50 subjects with probable DLB, and a control group. AD subjects were divided into two groups based on age of onset: early onset AD (EOAD and late onset AD (LOAD. All subjects had characteristic features on MRI, SPECT, and/or myocardial scintigraphy. RESULTS: The rate of APOE4 carrier status was 18.3% and the frequency of the ε4 allele was 9.7% in controls. The rate of APOE4 carrier status and the frequency of the ε4 allele were 47% and 27% for LOAD, 50% and 31% for EOAD, and 42% and 31% for DLB, respectively. CONCLUSION: The APOE4 genotypes in this study are consistent with previous neuropathological studies suggesting accurate diagnosis of AD and DLB. APOE4 genotypes were similar in AD and DLB, giving further evidence that the ε4 allele is a risk factor for both disorders.

  11. Apolipoprotein E polymorphism in Omani dyslipidemic patients with and without coronary artery disease.

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    Al-Yahyaee, Said Ali S; Ganguly, Shyam Sundar; Al Kindi, Mohammed Nasser; Al-Bahrani, Ali Ihassan

    2007-02-01

    Apolipoprotein E (APOE) polymorphism is a predictor of interindividual variability in plasma levels of lipids and lipoproteins and a predictor of risk of coronary artery disease (CAD). We studied the relationship between APOE polymorphism and lipid profiles and risk of CAD in Omani dyslipidemic patients. This retrospective study included 244 dyslipidemic patients, of whom 67 had CAD. Fasting blood glucose, lipids, and plasma lipoprotein levels were measured using standard methods, and APOE genotypes were detected by PCR-RFLP. The dyslipidemic patients had the following APOE allele frequencies: APOE*2, 0.030; APOE*3, 0.894; and APOE*4, 0.076. APOE allele frequencies between patients with and without CAD showed no significant differences. Compared to APOE*3/*3 homozygotes, APOE*4 allele patients had higher mean levels of low-density lipoprotein (LDL) cholesterol (p = 0.014), apoB (p = 0.031), lower mean levels of apoA1 (p = 0.043), and a trend of higher mean level of total cholesterol (p = 0.084). Thirty-one percent of patients with CAD had the APOE*4 allele compared to 26% with the APOE*3 allele, but this difference was not significant. Compared with APOE*3/*3 homozygotes, patients with the APOE*4 allele had 1.3 times higher risk for CAD after ignoring dyslipidemia, but this risk was modified after adjusting for dyslipidemia. In conclusion, among dyslipidemic patients, carriers of APOE*4 compared to homozygous carriers of APOE*3 had significantly higher levels of LDL cholesterol and apoB, but no relationship with CAD was found.

  12. Omentin attenuates atherosclerotic lesion formation in apolipoprotein E-deficient mice.

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    Hiramatsu-Ito, Mizuho; Shibata, Rei; Ohashi, Koji; Uemura, Yusuke; Kanemura, Noriyoshi; Kambara, Takahiro; Enomoto, Takashi; Yuasa, Daisuke; Matsuo, Kazuhiro; Ito, Masanori; Hayakawa, Satoko; Ogawa, Hayato; Otaka, Naoya; Kihara, Shinji; Murohara, Toyoaki; Ouchi, Noriyuki

    2016-05-01

    Obesity is associated with the development of atherosclerosis. We previously demonstrated that omentin is a circulating adipokine that is downregulated in association with atherosclerotic diseases. Here, we examined the impact of omentin on the development of atherosclerosis with gain-of-function genetic manipulations and dissected its potential mechanism. Apolipoprotein E-deficient (apoE-KO) mice were crossed with transgenic mice expressing the human omentin gene (OMT-Tg) mice in fat tissue to generate apoE-KO/OMT-Tg mice. ApoE-KO/OMT-Tg mice exhibited a significant reduction of the atherosclerotic areas in aortic sinus, compared with apoE-KO mice despite similar lipid levels. ApoE-KO/OMT-Tg mice also displayed significant decreases in macrophage accumulation and mRNA expression of proinflammatory mediators including tumour necrosis factor-α, interleukin-6, and monocyte chemotactic protein-1 in aorta when compared with apoE-KO mice. Treatment of human monocyte-derived macrophages with a physiological concentration of human omentin protein led to reduction of lipid droplets and cholesteryl ester content. Treatment with human omentin protein also reduced lipopolysaccharide-induced expression of proinflammatory genes in human macrophages. Treatment of human macrophages with omentin promoted the phosphorylation of Akt. Inhibition of Akt signalling abolished the anti-inflammatory actions of omentin in macrophages. These data document for the first time that omentin reduces the development of atherosclerosis by reducing inflammatory response of macrophages through the Akt-dependent mechanisms. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  13. Exogenous supplement of N-acetylneuraminic acid ameliorates atherosclerosis in apolipoprotein E-deficient mice.

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    Guo, Shoudong; Tian, Hua; Dong, Rongrong; Yang, Nana; Zhang, Ying; Yao, Shutong; Li, Yongjun; Zhou, Yawei; Si, Yanhong; Qin, Shucun

    2016-08-01

    Previous studies investigating the correlation between plasma sialic acid and the severity of atherosclerosis present conflicting results. In atherosclerosis patients, plasma levels of N-acetylneuraminic acid (NANA) are increased; however, the underlying mechanisms have not yet been clarified. We assume the increased NANA level may be a compensatory mechanism due to oxidative stress and/or inflammation. The aim of this study is to investigate whether supplementation of NANA could attenuate the progression of atherosclerosis. Exogenous NANA was used to determine its effect on apolipoprotein E-deficient (apoE(-/-)) mice taking natural quercetin as a positive control. The effect of NANA on lipid lowering, antioxidant activity and anti-inflammation was investigated by methods of molecular biology. 1) NANA administration decreased 18.9% of the atherosclerotic plaque formation in the aorta and 26.7% of the lipid deposition in the liver of high-fat diet apoE(-/-) mice; 2) notably, NANA treatment reduced 62.6% of the triglyceride by improving lipoprotein lipase activity; 3) NANA lowered 17.5% of the plasma total cholesterol by up-regulating reverse cholesterol transport (RCT)-related protein expression such as ATP-binding cassette transporter (ABC) G1 and ABCG5 in liver or small intestine; 4) NANA administration notably decreased oxidative stress by increasing antioxidant enzymes activity and protein expression of paraoxonase 1 and 2; 5) NANA markedly reduced tumour necrosis factor-α and intercellular adhesion molecule-1 expression in aorta and liver. NANA exhibited triglyceride lowering, anti-oxidation, and RCT promoting activities, and therefore NANA supplementation may be a new strategy for prevention and treatment of atherosclerosis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Lack of effect of the apolipoprotein E ε4 genotype on cognition during healthy aging.

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    Knight, Robert G; Tsui, Helen S L; Abraham, Wickliffe C; Skeaff, C Murray; McMahon, Jennifer A; Cutfield, Nicholas J

    2014-01-01

    The apolipoprotein E (APOE) ε4 genotype is associated with an increased risk of Alzheimer's disease. In community surveys, older adults with this genotype have been found to have lower scores on neuropsychological tests than those who do not. It is possible that this is the consequence of subclinical changes in cognition in those persons who later develop dementia. The aim of this research was to determine whether the effect of APOE genotype on cognition would remain if those who subsequently became demented were retrospectively removed from the analysis of the baseline test data from a sample of healthy adults. A sample of 241 nondemented persons over the age of 65 for whom APOE genotyping was available were administered a range of neuropsychological tests at baseline and were followed up 10 years later. Significant differences between the ε4-present and ε4-absent groups were found for the delayed recall trial of the Rey Auditory Verbal Learning Test and the Trail Making Test. When those participants known to have developed dementia during the follow-up period were excluded from the analysis of the baseline data these differences disappeared. A total of 113 nondemented survivors from the original sample were retested, and no difference was found in the rate of decline on any measure between the ε4-present and ε4-absent groups. It is likely that the reported effect of the ε4 APOE genotype on cognition is the consequence of the ε4-present group containing persons whose cognition is subtly affected by the early stages of a dementing process. It is also unlikely that the presence of the ε4 allele by itself leads to a significantly accelerated rate of cognitive decline in the nondemented elderly.

  15. Melanocortin 1 Receptor Deficiency Promotes Atherosclerosis in Apolipoprotein E-/-Mice.

    Science.gov (United States)

    Rinne, Petteri; Kadiri, James J; Velasco-Delgado, Mauricio; Nuutinen, Salla; Viitala, Miro; Hollmén, Maija; Rami, Martina; Savontaus, Eriika; Steffens, Sabine

    2018-02-01

    The MC1-R (melanocortin 1 receptor) is expressed by monocytes and macrophages where it mediates anti-inflammatory actions. MC1-R also protects against macrophage foam cell formation primarily by promoting cholesterol efflux through the ABCA1 (ATP-binding cassette transporter subfamily A member 1) and ABCG1 (ATP-binding cassette transporter subfamily G member 1). In this study, we aimed to investigate whether global deficiency in MC1-R signaling affects the development of atherosclerosis. Apoe -/- (apolipoprotein E deficient) mice were crossed with recessive yellow (Mc1r e/e ) mice carrying dysfunctional MC1-R and fed a high-fat diet to induce atherosclerosis. Apoe -/- Mc1r e/e mice developed significantly larger atherosclerotic lesions in the aortic sinus and in the whole aorta compared with Apoe -/- controls. In terms of plaque composition, MC1-R deficiency was associated with less collagen and smooth muscle cells and increased necrotic core, indicative of more vulnerable lesions. These changes were accompanied by reduced Abca1 and Abcg1 expression in the aorta. Furthermore, Apoe -/- Mc1r e/e mice showed a defect in bile acid metabolism that aggravated high-fat diet-induced hypercholesterolemia and hepatic lipid accumulation. Flow cytometric analysis of leukocyte profile revealed that dysfunctional MC1-R enhanced arterial accumulation of classical Ly6C high monocytes and macrophages, effects that were evident in mice fed a normal chow diet but not under high-fat diet conditions. In support of enhanced arterial recruitment of Ly6C high monocytes, these cells had increased expression of L-selectin and P-selectin glycoprotein ligand 1. The present study highlights the importance of MC1-R in the development of atherosclerosis. Deficiency in MC1-R signaling exacerbates atherosclerosis by disturbing cholesterol handling and by increasing arterial monocyte accumulation. © 2017 The Authors.

  16. Effects of Apolipoprotein E Isoforms in Diabetic Nephropathy of Chinese Type 2 Diabetic Patients

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    YongWei Jiang

    2017-01-01

    Full Text Available Diabetic nephropathy (DN is one of the major chronic complications of diabetes. Genetic polymorphism of Apolipoprotein E (ApoE has been proposed to participating in DN. The purpose of the study was to evaluate the relationship between ApoE genetic polymorphism and the presence of DN in Chinese type 2 diabetic patients. We studied 845 diabetic patients who were divided into DN group (n=429 and control group (n=416. ApoE genotype was determined by ApoE genotyping chip and the plasmatic biochemical characterization was performed on all subjects. There were differences (P<0.001 in HbA1c, creatinine, and urinary albumin between the two groups. The ApoE ε2 allelic frequency was 7.69% in DN group versus 3.49% in control group (OR = 2.22, 95% CI = 1.41–3.47, and P<0.05, as expected, ApoE E2/E2 and E2/E3 genotype frequency were higher in DN group (13.75% versus 6.49%, P<0.05. The ApoE ε4 allelic frequency was 7.93% in DN group versus 11.54% in control group (OR = 0.70, 95% CI = 0.50–0.97, and P<0.05, and DN group presented a lower frequency of ApoE E3/E4 and E4/E4 genotype frequency (14.91% versus 19.96%, P<0.05. These results suggest ApoE ε2 allele may be a risk factor; however ApoE ε4 allele may play a protective role of DN in Chinese type 2 diabetic patients.

  17. Human apolipoprotein e resequencing by proteomic analysis and its application to serotyping.

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    Motoi Nishimura

    Full Text Available BACKGROUND: Apolipoprotein E (ApoE typing is considered important because of the association between ApoE and Alzheimer's disease and familial dyslipidemia and is currently performed by genetic testing (APOE genotyping. ApoE levels in plasma and serum are clinically determined by immunoassay. METHODS: Combining an ApoE immunoassay reagent with proteomic analysis using an Orbitrap mass spectrometer, we attempted to resequence ApoE from trace amounts of serum for typing (serotyping. Most (24 of 33 ApoE mutant proteins registered to date with Online Mendelian Inheritance in Man, such as ApoE2 and ApoE4, involve lysine and arginine mutations. Digestion of mutant ApoE with trypsin will thus result in fragments that differ substantially from wild-type ApoE3 in terms of mass, making serotyping ideally suited to mass spectrometry analysis. RESULTS: The mean coverage of the amino acid sequence of full-length ApoE was 91.6% in the protein resequence. Residues 112 and 158 (which are mutated in ApoE2 and ApoE4 were covered in all samples, and the protein sequences were used for serotyping. Serotypes including all heterozygous combinations (ApoE2/E3, E2/E4, E3/E4 corresponded exactly to the APOE genotyping results in each of the subjects. CONCLUSION: Our novel ApoE serotyping method with protein resequencing requires no synthesis of stable isotope-labeled peptides or genome analysis. The method can use residual blood from samples collected for routine clinical tests, thus enabling retrospective studies with preserved body fluids. The test could be applied to samples from subjects whose DNA is unavailable. In future studies, we hope to demonstrate the capability of our method to detect rare ApoE mutations.

  18. Apolipoprotein E gene polymorphisms are associated with primary hyperuricemia in a Chinese population.

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    Jie Wu

    Full Text Available OBJECTIVE: Primary hyperuricemia, an excess of uric acid in the blood, is a major public health problem. In addition to the morbidity that is attributable to gout, hyperuricemia is also associated with metabolic syndrome, hypertension, and cardiovascular disease. This study aims to assess the genetic associations between Apolipoprotein E (APOE polymorphisms and hyperuricemia in a Chinese population. METHODS: A total of 770 subjects (356 hyperuricemic cases and 414 normouricemic controls were recruited from the Ningxia Hui Autonomous Region, China. A physical examination was performed and fasting blood was collected for biochemical tests, including determination of the levels of serum lipid, creatinine, and uric acid. Multi-ARMS PCR was applied to determine the APOE genotypes, followed by an investigation of the distribution of APOE genotypes and alleles frequencies in the controls and cases. RESULTS: The frequencies of the APOE-ε2ε3 genotype (17.70% vs. 10.39%, P = 0.003 and the APOE-ε2 allele (10.53% vs. 5.80%, P = 0.001 were significantly higher in the hyperuricemic group than in the normouricemic group. Furthermore, male cases were more likely to have the APOE-ε2ε3 genotype and APOE-ε2 allele, compared with male controls. In both Han and Hui subjects, cases were more likely to have the APOE-ε2ε3 genotype and the APOE-ε2 allele compared with controls. Furthermore, multivariate logistic regression showed that carriers of the APOE-ε2ε3 genotype (P = 0.001, OR = 2.194 and the ε2 allele (P = 0.001, OR = 2.099 were significantly more likely to experience hyperuricemia than carriers of the ε3/ε3 genotype and the ε3 allele after adjustment for sex, body mass index (BMI, diastolic blood pressure (DBP, triglyceride (TG, low density lipoprotein cholesterol (LDL-C, creatinine (Cr and fasting blood glucose (FBG. CONCLUSIONS: The APOE-ε2ε3 genotype and the APOE-ε2 allele are associated with serum uric acid levels

  19. Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice

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    C.V. Araújo

    2015-06-01

    Full Text Available Apolipoprotein E (APOE=gene, apoE=protein is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE-/- and wild-type (APOE+/+ C57BL6J male and female mice (N=86 were given either Ala-Gln (100 mM or phosphate buffered saline (PBS by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU challenge (450 mg/kg, via intraperitoneal injection. Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1 and B-cell lymphoma 2 (Bcl-2 intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001 in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05 were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE-/- mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE+/+ mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE-/--challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU challenge.

  20. Apolipoprotein E as a novel therapeutic neuroprotection target after traumatic spinal cord injury.

    Science.gov (United States)

    Cheng, Xiaoxin; Zheng, Yiyan; Bu, Ping; Qi, Xiangbei; Fan, Chunling; Li, Fengqiao; Kim, Dong H; Cao, Qilin

    2018-01-01

    Apolipoprotein E (apoE), a plasma lipoprotein well known for its important role in lipid and cholesterol metabolism, has also been implicated in many neurological diseases. In this study, we examined the effect of apoE on the pathophysiology of traumatic spinal cord injury (SCI). ApoE-deficient mutant (apoE -/- ) and wild-type mice received a T9 moderate contusion SCI and were evaluated using histological and behavioral analyses after injury. At 3days after injury, the permeability of spinal cord-blood-barrier, measured by extravasation of Evans blue dye, was significantly increased in apoE -/- mice compared to wild type. The inflammation and spared white matter was also significantly increased and decreased, respectively, in apoE -/- mice compared to the wild type ones. The apoptosis of both neurons and oligodendrocytes was also significantly increased in apoE -/- mice. At 42days after injury, the inflammation was still robust in the injured spinal cord in apoE -/- but not wild type mice. CD45+ leukocytes from peripheral blood persisted in the injured spinal cord of apoE -/- mice. The spared white matter was significantly decreased in apoE -/- mice compared to wild type ones. Locomotor function was significantly decreased in apoE -/- mice compared to wild type ones from week 1 to week 8 after contusion. Treatment of exogenous apoE mimetic peptides partially restored the permeability of spinal cord-blood-barrier in apoE -/- mice after SCI. Importantly, the exogenous apoE peptides decreased inflammation, increased spared white matter and promoted locomotor recovery in apoE -/- mice after SCI. Our results indicate that endogenous apoE plays important roles in maintaining the spinal cord-blood-barrier and decreasing inflammation and spinal cord tissue loss after SCI, suggesting its important neuroprotective function after SCI. Our results further suggest that exogenous apoE mimetic peptides could be a novel and promising neuroprotective reagent for SCI. Copyright

  1. Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice

    International Nuclear Information System (INIS)

    Araújo, C.V.; Lazzarotto, C.R.; Aquino, C.C.; Figueiredo, I.L.; Costa, T.B.; Oliveira Alves, L.A. de; Ribeiro, R.A.; Bertolini, L.R.; Lima, A.A.M.; Brito, G.A.C.; Oriá, R.B.

    2015-01-01

    Apolipoprotein E (APOE=gene, apoE=protein) is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln) treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE -/- ) and wild-type (APOE +/+ ) C57BL6J male and female mice (N=86) were given either Ala-Gln (100 mM) or phosphate buffered saline (PBS) by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU) challenge (450 mg/kg, via intraperitoneal injection). Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1) and B-cell lymphoma 2 (Bcl-2) intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001) in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05) were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE -/- mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE +/+ mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE -/- -challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU challenge

  2. Smoking, apolipoprotein E genotypes, and mortality (the Ludwigshafen RIsk and Cardiovascular Health study).

    Science.gov (United States)

    Grammer, Tanja B; Hoffmann, Michael M; Scharnagl, Hubert; Kleber, Marcus E; Silbernagel, Günther; Pilz, Stefan; Tomaschitz, Andreas; Lerchbaum, Elisabeth; Siekmeier, Rüdiger; März, Winfried

    2013-05-01

    The genetic polymorphism of apolipoprotein E (APOE) has been suggested to modify the effect of smoking on the development of coronary artery disease (CAD) in apparently healthy persons. The interaction of these factors in persons undergoing coronary angiography is not known. We analysed the association between the APOE-genotype, smoking, angiographic CAD, and mortality in 3263 participants of the LUdwigshafen RIsk and Cardiovascular Health study. APOE-genotypes were associated with CAD [ε22 or ε23: odds ratio (OR) 0.56, 95% confidence interval (CI) 0.43-0.71; ε24 or ε34 or ε44: OR 1.10, 95% CI 0.89-1.37 compared with ε33] and moderately with cardiovascular mortality [ε22 or ε23: hazard ratio (HR) 0.71, 95% CI 0.51-0.99; ε33: HR 0.92, 95% CI 0.75-1.14 compared with ε24 or ε34 or ε44]. HRs for total mortality were 1.39 (95% CI 0.39-0.1.67), 2.29 (95% CI 1.85-2.83), 2.07 (95% CI 1.64-2.62), and 2.95 (95% CI 2.10-4.17) in ex-smokers, current smokers, current smokers without, or current smokers with one ε4 allele, respectively, compared with never-smokers. Carrying ε4 increased mortality in current, but not in ex-smokers (HR 1.66, 95% CI 1.04-2.64 for interaction). These findings applied to cardiovascular mortality, were robust against adjustment for cardiovascular risk factors, and consistent across subgroups. No interaction of smoking and ε4 was seen regarding non-cardiovascular mortality. Smokers with ε4 had reduced average low-density lipoprotein (LDL) diameters, elevated oxidized LDL, and lipoprotein-associated phospholipase A2. In persons undergoing coronary angiography, there is a significant interaction between APOE-genotype and smoking. The presence of the ε4 allele in current smokers increases cardiovascular and all-cause mortality.

  3. Apolipoprotein E genotype and the diagnostic accuracy of cerebrospinal fluid biomarkers for Alzheimer disease.

    Science.gov (United States)

    Lautner, Ronald; Palmqvist, Sebastian; Mattsson, Niklas; Andreasson, Ulf; Wallin, Anders; Pålsson, Erik; Jakobsson, Joel; Herukka, Sanna-Kaisa; Owenius, Rikard; Olsson, Bob; Hampel, Harald; Rujescu, Dan; Ewers, Michael; Landén, Mikael; Minthon, Lennart; Blennow, Kaj; Zetterberg, Henrik; Hansson, Oskar

    2014-10-01

    Several studies suggest that the apolipoprotein E (APOE) ε4 allele modulates cerebrospinal fluid (CSF) levels of β-amyloid 42 (Aβ42). Whether this effect is secondary to the association of the APOE ε4 allele with cortical Aβ deposition or whether APOE ε4 directly influences CSF levels of Aβ42 independently of Aβ pathology remains unknown. To evaluate whether the APOE genotype affects the diagnostic accuracy of CSF biomarkers for Alzheimer disease (AD), in particular Aβ42 levels, and whether the association of APOE ε4 with CSF biomarkers depends on cortical Aβ status. We collected data from 4 different centers in Sweden, Finland, and Germany. Cohort A consisted of 1345 individuals aged 23 to 99 years with baseline CSF samples, including 309 with AD, 287 with prodromal AD, 399 with stable mild cognitive impairment, 99 with dementias other than AD, and 251 controls. Cohort B included 105 nondemented younger individuals (aged 20-34 years) with CSF samples available. Cohort C included 118 patients aged 60 to 80 years with mild cognitive symptoms who underwent flutemetamol F 18 ([18F]flumetamol) positron emission tomography amyloid imaging and CSF tap. Standard care. Cerebrospinal fluid levels of Aβ42 and total and phosphorylated tau in relation to the APOE ε2/ε3/ε4 polymorphism in different diagnostic groups and in cases with or without cortical uptake of [18F]flutemetamol. The CSF levels of Aβ42 but not total and phosphorylated tau were lower in APOE ε4 carriers compared with noncarriers irrespective of diagnostic group (cohort A). Despite this, CSF levels of Aβ42 differed between participants with AD when compared with controls and those with stable mild cognitive impairment, even when stratifying for APOE genotype (P Alzheimer's Disease Neuroimaging Initiative (ADNI) using carbon 11-labeled Pittsburgh Compound B scanning. Cerebrospinal fluid levels of Aβ42 are strongly associated with the diagnosis of AD and cortical Aβ accumulation independent

  4. Apolipoprotein E gene polymorphism and risk of type 2 diabetes and cardiovascular disease.

    Science.gov (United States)

    El-Lebedy, Dalia; Raslan, Hala M; Mohammed, Asmaa M

    2016-01-22

    Lipoprotein-related mechanisms have been associated with damage to the cardiovascular system in diabetic patients. Apolipoprotein E gene which affects the clearance of lipoproteins and consequently the lipid profile in our body is one of the most studied candidate genes and recently has been reported to be associated with T2DM and CAD. In this work, we studied the association of apoE gene polymorphism with T2DM and CVD and its effect on plasma lipids profile. Our study was conducted on 284 subjects categorized into 100 patients with T2DM, 100 patients with T2DM complicated with CVD and 84 normal control subjects. ApoE gene polymorphism was genotyped by real-time PCR using TaqMan(®) SNP Genotyping Assay. ApoE E3/E3 genotype was the most common in our subjects. The frequencies of E3/E4 genotype and ε4 allele were increased in both T2DM patients and CVD patients as compared with controls, but were significant only in CVD patients (p = 0.004 and 0.007, respectively). Diabetic patients who carried E3/E4 genotype were at 2.4-fold increased risk to develop CVD (95 % CI 1.14-5.19, P = 0.02) and the ε4 allele associated with 2.23-fold higher CVD risk (95 % CI 1.09-4.59, P = 0.02). After adjustment for other established risk factors, E3/E4 genotype was an independent risk factor for CVD (OR = 2.3, p = 0.009) but not for T2DM (OR = 1.7, p = 0.28), while ε4 allele was an independent risk factor for both T2DM (OR = 2.2, p = 0.04) and CVD (OR = 3.0, p = 0.018) with 5.9-fold increased risk to develop CVD in T2DM patients (p = 0.019). E3/E4 genotype associated with significantly higher levels of TC and non HDL-C in all groups and with significantly higher levels of LDL-C in both T2DM and CVD patients. ApoE gene polymorphisms associate with CVD and affect the lipid profile. The ε4 allele is an independent risk factor for both T2DM and CVD. Further genetic studies to add information beyond the traditional cardiovascular risk factors in T2DM and to identify risk genotypes will

  5. Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice

    Energy Technology Data Exchange (ETDEWEB)

    Araújo, C.V. [Laboratório da Biologia da Cicatrização, Ontogenia e Nutrição de Tecidos, INCT - Instituto de Biomedicina do Semiárido Brasileiro, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Lazzarotto, C.R. [Laboratório de Biologia Molecular e do Desenvolvimento, Universidade de Fortaleza, Fortaleza, CE (Brazil); Aquino, C.C.; Figueiredo, I.L.; Costa, T.B.; Oliveira Alves, L.A. de [Laboratório da Biologia da Cicatrização, Ontogenia e Nutrição de Tecidos, INCT - Instituto de Biomedicina do Semiárido Brasileiro, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Ribeiro, R.A. [Laboratório da Inflamação e Câncer, INCT - Instituto de Biomedicina do Semiárido Brasileiro, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Bertolini, L.R. [Laboratório de Biologia Molecular e do Desenvolvimento, Universidade de Fortaleza, Fortaleza, CE (Brazil); Lima, A.A.M. [Laboratório de Doenças Infecciosas, INCT - Instituto de Biomedicina do Semiárido Brasileiro, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Brito, G.A.C. [Laboratório da Inflamação e Câncer, INCT - Instituto de Biomedicina do Semiárido Brasileiro, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE (Brazil); Oriá, R.B. [Laboratório da Biologia da Cicatrização, Ontogenia e Nutrição de Tecidos, INCT - Instituto de Biomedicina do Semiárido Brasileiro, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE (Brazil)

    2015-04-28

    Apolipoprotein E (APOE=gene, apoE=protein) is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln) treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE{sup -/-}) and wild-type (APOE{sup +/+}) C57BL6J male and female mice (N=86) were given either Ala-Gln (100 mM) or phosphate buffered saline (PBS) by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU) challenge (450 mg/kg, via intraperitoneal injection). Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1) and B-cell lymphoma 2 (Bcl-2) intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001) in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05) were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE{sup -/-} mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE{sup +/+} mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE{sup -/-}-challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU

  6. High-salt diet combined with elevated angiotensin II accelerates atherosclerosis in apolipoprotein E-deficient mice

    DEFF Research Database (Denmark)

    Johansson, Maria E; Bernberg, Evelina; Andersson, Irene J

    2009-01-01

    OBJECTIVES: High-salt diet likely elevates blood pressure (BP), thus increasing the risk of cardiovascular events. We hypothesized that a high-salt diet plays a critical role in subjects whose renin-angiotensin systems cannot adjust to variable salt intake, rendering them more susceptible...... to atherosclerosis. METHODS: Apolipoprotein E-deficient (ApoE-/-) mice received standard or high-salt diet (8%) alone or in combination with fixed angiotensin II (Ang II) infusion (0.5 microg/kg per min). BP was measured using telemetry, and plaque burden was assessed in the thoracic aorta and innominate artery. We...

  7. Characterization of the unfolding process of the tetrameric and dimeric forms of Cratylia mollis seed lectin (CRAMOLL 1): effects of natural fragmentation on protein stability.

    Science.gov (United States)

    Varejão, Nathalia; Correia, Maria Tereza S; Foguel, Debora

    2011-08-30

    pCRAMOLL 1 is a major, non-glycosylated isolectin found in seeds of Cratylia mollis, which belongs to the Leguminosae family and the Diocleinae subtribe. The lectin (~25 kDa) consists of 236 amino acids, sharing 82% identity and virtually identical topological architecture with concanavalin A. Both lectins also share the same pH-dependent dimer-tetramer equilibrium and the ability to recognize Glc/Man moieties. Intricate post-translational events occurring in Diocleinae seed cotyledons result in a mixture of intact and fragmented monomers within the oligomeric assemblies of pCRAMOLL 1. In an earlier report, we demonstrated the production, purification, and characterization of the bacterially expressed form of CRAMOLL 1 (rCRAMOLL 1). The recombinant lectin retained sugar-binding activity and several other biophysical properties of pCRAMOLL 1, but its tetramers, which are composed of intact monomers only, show little enhancement in stability when probed with acidification, high temperatures, or hydrostatic pressure. Here we examined the urea-induced unfolding of the nonfragmented tetramers and dimers of rCRAMOLL 1 and compared this behavior with that of the mixed plant lectin counterparts. Using fluorescence, circular dichroism, size-exclusion chromatography, and chemical cross-linking experiments, we posited that the absence of fragmentation lent greater firmness to tetramers, but not to dimers. Dimeric and tetrameric pCRAMOLL 1 unfolded via a compact monomeric intermediate. In contrast, dimers of rCRAMOLL 1 behaved similarly to the plant dimer counterpart, but its tetrameric form remarkably showed no evidence of such partially unfolded monomers. By analyzing the crystal structure of pCRAMOLL 1, we were able to dissect the importance of the fragmentation to lectin stability.

  8. Evolution of magnetization due to asymmetric dimerization: theoretical considerations and application to aberrant oligomers formed by apoSOD1(2SH).

    Science.gov (United States)

    Sekhar, Ashok; Bain, Alex D; Rumfeldt, Jessica A O; Meiering, Elizabeth M; Kay, Lewis E

    2016-02-17

    A set of coupled differential equations is presented describing the evolution of magnetization due to an exchange reaction whereby a pair of identical monomers form an asymmetric dimer. In their most general form the equations describe a three-site exchange process that reduces to two-site exchange under certain limiting conditions that are discussed. An application to the study of sparsely populated, transiently formed sets of aberrant dimers, symmetric and asymmetric, of superoxide dismutase is presented. Fits of concentration dependent CPMG relaxation dispersion profiles provide measures of the dimer dissociation constants and both on- and off-rates. Dissociation constants on the order of 70 mM are extracted from fits of the data, with dimeric populations of ∼2% and lifetimes of ∼6 and ∼2 ms for the symmetric and asymmetric complexes, respectively. This work emphasizes the important role that NMR relaxation experiments can play in characterizing very weak molecular complexes that remain invisible to most biophysical approaches.

  9. Subunit b-Dimer of the Escherichia coli ATP Synthase Can Form Left-Handed Coiled-Coils

    Science.gov (United States)

    Wise, John G.; Vogel, Pia D.

    2008-01-01

    One remaining challenge to our understanding of the ATP synthase concerns the dimeric coiled-coil stator subunit b of bacterial synthases. The subunit b-dimer has been implicated in important protein interactions that appear necessary for energy conservation and that may be instrumental in energy conservation during rotary catalysis by the synthase. Understanding the stator structure and its interactions with the rest of the enzyme is crucial to the understanding of the overall catalytic mechanism. Controversy exists on whether subunit b adopts a classic left-handed or a presumed right-handed dimeric coiled-coil and whether or not staggered pairing between nonhomologous residues in the homodimer is required for intersubunit packing. In this study we generated molecular models of the Escherichia coli subunit b-dimer that were based on the well-established heptad-repeat packing exhibited by left-handed, dimeric coiled-coils by employing simulated annealing protocols with structural restraints collected from known structures. In addition, we attempted to create hypothetical right-handed coiled-coil models and left- and right-handed models with staggered packing in the coiled-coil domains. Our analyses suggest that the available structural and biochemical evidence for subunit b can be accommodated by classic left-handed, dimeric coiled-coil quaternary structures. PMID:18326648

  10. Site-specific effects of apolipoprotein E expression on diet-induced obesity and white adipose tissue metabolic activation.

    Science.gov (United States)

    Hatziri, Aikaterini; Kalogeropoulou, Christina; Xepapadaki, Eva; Birli, Eleni; Karavia, Eleni A; Papakosta, Eugenia; Filou, Serafoula; Constantinou, Caterina; Kypreos, Kyriakos E

    2018-02-01

    Apolipoprotein E (APOE) has been strongly implicated in the development of diet induced obesity. In the present study, we investigated the contribution of brain and peripherally expressed human apolipoprotein E3 (APOE3), the most common human isoform, to diet induced obesity. In our studies APOE3 knock-in (Apoe3 knock-in ), Apoe-deficient (apoe -/- ) and brain-specific expressing APOE3 (Apoe3 brain ) mice were fed western-type diet for 12week and biochemical analyses were performed. Moreover, AAV-mediated gene transfer of APOE3 to apoe -/- mice was employed, as a means to achieve APOE3 expression selectively in periphery, since peripherally expressed APOE does not cross blood brain barrier (BBB) or blood-cerebrospinal fluid barrier (BCSFB). Our data suggest a bimodal role of APOE3 in visceral white adipose tissue (WAT) mitochondrial metabolic activation that is highly dependent on its site of expression and independent of postprandial dietary lipid deposition. Our findings indicate that brain APOE3 expression is associated with a potent inhibition of visceral WAT mitochondrial oxidative phosphorylation, leading to significantly reduced substrate oxidation, increased fat accumulation and obesity. In contrast, peripherally expressed APOE3 is associated with a notable shift of substrate oxidation towards non-shivering thermogenesis in visceral WAT mitochondria, leading to resistance to obesity. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Mycobacterium tuberculosis UvrB forms dimers in solution and interacts with UvrA in the absence of ligands.

    Science.gov (United States)

    Lahiri, Samarpita; Rizzi, Menico; Rossi, Franca; Miggiano, Riccardo

    2018-01-01

    During its life cycle Mycobacterium tuberculosis (MTB) must face a variety of environmental and endogenous physical and chemical stresses that could produce genotoxic damage. However, MTB possesses efficient systems to counteract the harmful effects of DNA-damaging assaults. The nucleotide excision repair (NER) is a highly conserved multi-enzymatic cascade that is initiated by the concerted action of three core proteins, that is UvrA, UvrB, and UvrC. Although the functional roles of these enzymes are well characterized, the intra-pathway coordination of the NER components and the dynamics of their association is still a matter of debate. In the presented study, we analyzed the hydrodynamic properties and the oligomeric state of the MTB UvrB protein (MtUvrB) that we expressed and purified to homogeneity in a tag-free form. Our results show that, differently to what has been previously observed for the His-tagged version of the protein, MtUvrB forms dimers in solution, which are characterized by an elongated shape, as determined by small-angle X-ray scattering analysis. Moreover, to gain insights into the mycobacterial UvrA/UvrB lesion sensing/tracking complex we adopted a size-exclusion chromatography-based approach, revealing that the two proteins interact in the absence of ligands, leading to the assembling of A 2 B 2 hetero-tetramers in solution. Surface plasmon resonance analysis showed that the dissociation constant of the MtUvrA/MtUvrB complex falls in the low micromolar range that could represent the basis for a fine modulation of the complex architecture accompanying the multi-step DNA repair activity of mycobacterial NER. © 2017 Wiley Periodicals, Inc.

  12. A Phytophthora sojae effector PsCRN63 forms homo-/hetero-dimers to suppress plant immunity via an inverted association manner.

    Science.gov (United States)

    Li, Qi; Zhang, Meixiang; Shen, Danyu; Liu, Tingli; Chen, Yanyu; Zhou, Jian-Min; Dou, Daolong

    2016-05-31

    Oomycete pathogens produce a large number of effectors to promote infection. Their mode of action are largely unknown. Here we show that a Phytophthora sojae effector, PsCRN63, suppresses flg22-induced expression of FRK1 gene, a molecular marker in pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI). However, PsCRN63 does not suppress upstream signaling events including flg22-induced MAPK activation and BIK1 phosphorylation, indicating that it acts downstream of MAPK cascades. The PsCRN63-transgenic Arabidopsis plants showed increased susceptibility to bacterial pathogen Pseudomonas syringae pathovar tomato (Pst) DC3000 and oomycete pathogen Phytophthora capsici. The callose deposition were suppressed in PsCRN63-transgenic plants compared with the wild-type control plants. Genes involved in PTI were also down-regulated in PsCRN63-transgenic plants. Interestingly, we found that PsCRN63 forms an dimer that is mediated by inter-molecular interactions between N-terminal and C-terminal domains in an inverted association manner. Furthermore, the N-terminal and C-terminal domains required for the dimerization are widely conserved among CRN effectors, suggesting that homo-/hetero-dimerization of Phytophthora CRN effectors is required to exert biological functions. Indeed, the dimerization was required for PTI suppression and cell death-induction activities of PsCRN63.

  13. Apolipoprotein E e4 allele does not increase the risk of early postoperative delirium after major surgery.

    Science.gov (United States)

    Abelha, Fernando José; Fernandes, Vera; Botelho, Miguela; Santos, Patricia; Santos, Alice; Machado, J C; Barros, Henrique

    2012-02-01

    BACKGROUND: A relationship between patients with a genetic predisposition to and those who develop postoperative delirium has not been yet determined. The aim of this study was to determine whether there is an association between apolipoprotein E epsilon 4 allele (APOE4) and delirium after major surgery. METHODS: Of 230 intensive care patients admitted to the post anesthesia care unit (PACU) over a period of 3 months, 173 were enrolled in the study. Patients' demographics and intra- and postoperative data were collected. Patients were followed for the development of delirium using the Intensive Care Delirium Screening Checklist, and DNA was obtained at PACU admission to determine apolipoprotein E genotype. RESULTS: Fifteen percent of patients developed delirium after surgery. Twenty-four patients had one copy of APOE4. The presence of APOE4 was not associated with an increased risk of early postoperative delirium (4% vs. 17%; P = 0.088). The presence of APOE4 was not associated with differences in any studied variables. Multivariate analysis identified age [odds ratio (OR) 9.3, 95% confidence interval (CI) 2.0-43.0, P = 0.004 for age ≥65 years), congestive heart disease (OR 6.2, 95% CI 2.0-19.3, P = 0.002), and emergency surgery (OR 59.7, 95% CI 6.7-530.5, P < 0.001) as independent predictors for development of delirium. The Simplified Acute Physiology Score II (SAPS II) and The Acute Physiology and Chronic Health Evaluation II (APACHE II) were significantly higher in patients with delirium (P < 0.001 and 0.008, respectively). Hospital mortality rates of these patients was higher and they had a longer median PACU stay. CONCLUSIONS: Apolipoprotein e4 carrier status was not associated with an increased risk for early postoperative delirium. Age, congestive heart failure, and emergency surgery were independent risk factors for the development of delirium after major surgery.

  14. High-salt diet combined with elevated angiotensin II accelerates atherosclerosis in apolipoprotein E-deficient mice

    DEFF Research Database (Denmark)

    Johansson, Maria E; Bernberg, Evelina; Andersson, Irene J

    2009-01-01

    OBJECTIVES: High-salt diet likely elevates blood pressure (BP), thus increasing the risk of cardiovascular events. We hypothesized that a high-salt diet plays a critical role in subjects whose renin-angiotensin systems cannot adjust to variable salt intake, rendering them more susceptible...... to atherosclerosis. METHODS: Apolipoprotein E-deficient (ApoE-/-) mice received standard or high-salt diet (8%) alone or in combination with fixed angiotensin II (Ang II) infusion (0.5 microg/kg per min). BP was measured using telemetry, and plaque burden was assessed in the thoracic aorta and innominate artery. We...... used urinary isoprostane as a marker for oxidative stress. RESULTS: Although high-salt diet per se did not affect plaque extension, high salt combined with Ang II increased plaque area significantly in both the aorta and the innominate artery as compared with Ang II or salt alone (P

  15. Proteomic Profile of Unstable Atheroma Plaque: Increased Neutrophil Defensin 1, Clusterin, and Apolipoprotein E Levels in Carotid Secretome.

    Science.gov (United States)

    Aragonès, Gemma; Auguet, Teresa; Guiu-Jurado, Esther; Berlanga, Alba; Curriu, Marta; Martinez, Salomé; Alibalic, Ajla; Aguilar, Carmen; Hernández, Esteban; Camara, María-Luisa; Canela, Núria; Herrero, Pol; Ruyra, Xavier; Martín-Paredero, Vicente; Richart, Cristóbal

    2016-03-04

    Because of the clinical significance of carotid atherosclerosis, the search for novel biomarkers has become a priority. The aim of the present study was to compare the protein secretion profile of the carotid atherosclerotic plaque (CAP, n = 12) and nonatherosclerotic mammary artery (MA, n = 10) secretomes. We used a nontargeted proteomic approach that incorporated tandem immunoaffinity depletion, iTRAQ labeling, and nanoflow liquid chromatography coupled to high-resolution mass spectrometry. In total, 162 proteins were quantified, of which 25 showed statistically significant differences in secretome levels between carotid atherosclerotic plaque and nondiseased mammary artery. We found increased levels of neutrophil defensin 1, apolipoprotein E, clusterin, and zinc-alpha-2-glycoprotein in CAP secretomes. Results were validated by ELISA assays. Also, differentially secreted proteins are involved in pathways such as focal adhesion and leukocyte transendothelial migration. In conclusion, this study provides a subset of identified proteins that are differently expressed in secretomes of clinical significance.

  16. Haptoglobin Phenotype and Apolipoprotein E Polymorphism: Relationship to Post-Traumatic Seizures and Neuropsychological Functioning after Traumatic Brain Injury

    Science.gov (United States)

    Anderson, Gail D; Temkin, Nancy R; Dikmen, Sureyya S.; Diaz-Arrastia, Ramon; Machamer, Joan E.; Farhrenbruch, Carol; Miller, John W; Sadrzadeh, SM Hossein

    2009-01-01

    The relationship between genetic predisposition to reduced iron capacity and apolipoprotein E (APOE) with post-traumatic seizures (PTS) and neuropsychological outcomes was investigated in patients with traumatic brain injuries (TBI) from a prior valproate clinical study. Haptoglobin (Hp) concentration/phenotype and APOE genotype was determined in 25 PTS and 26 controls (no PTS) subjects ~10 year after TBI. Hp phenotype was also determined in previously collected frozen samples for 25 additional PTS and 32 no PTS subjects. There was no relationship between Hp phenotype or APOE genotype and occurrence of PTS. APOE genotype was not related to neuropsychological outcome; however when adjustments were made for differences in educational levels, APOE ε4 subjects did worse especially on verbal intellectual and verbal memory skills. In contrast to our hypothesis, those with Hp 1-1 (high affinity binder of hemoglobin), scored somewhat worse on verbal IQ and Tapping D at 1 and 12 month after injury. PMID:19766540

  17. Long-term Western diet fed apolipoprotein E-deficient rats exhibit only modest early atherosclerotic characteristics

    DEFF Research Database (Denmark)

    Rune, Ida; Rolin, Bidda; Lykkesfeldt, Jens

    2018-01-01

    In the apolipoprotein E-deficient mouse, the gut microbiota has an impact on the development of atherosclerosis, but whether such correlations are also present in rats requires investigation. Therefore, we studied female SD-Apoe tm1sage (Apoe -/-) rats fed either a Western diet or a low-fat control...... diet with or without gluten, which is known to promote gut microbiota changes, until 20 weeks of age. We hypothesized that the manifestation of atherosclerosis would be more severe in Apoe -/- rats fed the Western high-fat diet, as compared with rats fed the low-fat diet, and that atherosclerosis would...... be accelerated by gluten. Both Western diet-feeding and gluten resulted in significant changes in gut microbiota, but the microbiota impact of gluten was transient. Compared with Apoe -/- rats fed a low-fat diet, Western diet-fed Apoe -/- rats were heavier and became glucose intolerant with increased levels...

  18. Plasma apolipoprotein E levels and risk of dementia-A Mendelian randomization study of 106,562 individuals

    DEFF Research Database (Denmark)

    Rasmussen, Katrine L; Tybjærg-Hansen, Anne; Nordestgaard, Børge G

    2017-01-01

    INTRODUCTION: In recent prospective studies, low plasma levels of apolipoprotein E (apoE) are associated with high risk of dementia. Whether this reflects a causal association remains to be established. METHODS: Using a Mendelian randomization approach, we studied 106,562 and 75,260 individuals...... from the general population in observational and genetic analyses, respectively. RESULTS: In observational analyses risk of Alzheimer disease and all dementia increased stepwise as a function of stepwise lower apoE levels (P for trend, 2 × 10(-17) and 9 × 10(-21)). APOE-weighted allele scores were...... associated with stepwise decreases in apoE (P for trend, genetically determined lower apoE were 1.41 (1.27-1.57) for Alzheimer disease and 1.33 (1.25-1.43) for all dementia (F-statistics = 3821). DISCUSSION: Genetic...

  19. Smooth muscle cells healing atherosclerotic plaque disruptions are of local, not blood, origin in apolipoprotein E knockout mice

    DEFF Research Database (Denmark)

    Bentzon, Jacob F.; Sondergaard, Claus S.; Kassem, Moustapha

    2007-01-01

    GFP+ SMCs were detected. To examine the origin of healing SMCs in a model that recapitulates more features of human plaque rupture and healing, we developed a mechanical technique that produced consistent plaque disruption, superimposed thrombosis, and SMC-mediated plaque healing in apoE-/- mice. Mechanical......BACKGROUND: Signs of preceding episodes of plaque rupture and smooth muscle cell (SMC)-mediated healing are common in atherosclerotic plaques, but the source of the healing SMCs is unknown. Recent studies suggest that activated platelets adhering to sites of injury recruit neointimal SMCs from...... circulating bone marrow-derived progenitor cells. Here, we analyzed the contribution of this mechanism to plaque healing after spontaneous and mechanical plaque disruption in apolipoprotein E knockout (apoE-/-) mice. METHODS AND RESULTS: To determine the origin of SMCs after spontaneous plaque disruption...

  20. Apolipoprotein E4 is associated with improved cognitive function in Amazonian forager-horticulturalists with a high parasite burden.

    Science.gov (United States)

    Trumble, Benjamin C; Stieglitz, Jonathan; Blackwell, Aaron D; Allayee, Hooman; Beheim, Bret; Finch, Caleb E; Gurven, Michael; Kaplan, Hillard

    2017-04-01

    The apolipoprotein E4 (E4) allele is present worldwide, despite its associations with higher risk of cardiovascular morbidity, accelerated cognitive decline during aging, and Alzheimer 's disease (AD). The E4 allele is especially prevalent in some tropical regions with a high parasite burden. Equatorial populations also face a potential dual burden of high E4 prevalence combined with parasitic infections that can also reduce cognitive performance. We examined the interactions of E4, parasite burden, and cognitive performance in a traditional, nonindustrialized population of Amazonian forager-horticulturalists ( N = 372) to test whether E4 protects against cognitive decline in environments with a heavy pathogen burden. Contrary to observations in industrial populations, older adult E4 carriers with high parasite burdens either maintained or showed slight improvements in cognitive performance, whereas non-E4 carriers with a high parasite burden showed reduced cognitive performance. Being an E4 carrier is the strongest risk factor to date of AD and cognitive decline in industrial populations; it is associated with greater cognitive performance in individuals facing a high parasite and pathogen load, suggesting advantages to the E4 allele under certain environmental conditions. The current mismatch between postindustrial hygienic lifestyles and active parasite-rich environs may be critical for understanding genetic risk for cognitive aging.-Trumble, B. C., Stieglitz, J., Blackwell, A. D., Allayee, H., Beheim, B., Finch, C. E., Gurven, M., Kaplan, H. Apolipoprotein E4 is associated with improved cognitive function in Amazonian forager-horticulturalists with a high parasite burden. © FASEB.

  1. Proteomic Analysis of Plasma from California Sea Lions (Zalophus californianus Reveals Apolipoprotein E as a Candidate Biomarker of Chronic Domoic Acid Toxicosis.

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    Benjamin A Neely

    Full Text Available Domoic acid toxicosis (DAT in California sea lions (Zalophus californianus is caused by exposure to the marine biotoxin domoic acid and has been linked to massive stranding events and mortality. Diagnosis is based on clinical signs in addition to the presence of domoic acid in body fluids. Chronic DAT further is characterized by reoccurring seizures progressing to status epilepticus. Diagnosis of chronic DAT is often slow and problematic, and minimally invasive tests for DAT have been the focus of numerous recent biomarker studies. The goal of this study was to retrospectively profile plasma proteins in a population of sea lions with chronic DAT and those without DAT using two dimensional gel electrophoresis to discover whether individual, multiple, or combinations of protein and clinical data could be utilized to identify sea lions with DAT. Using a training set of 32 sea lion sera, 20 proteins and their isoforms were identified that were significantly different between the two groups (p<0.05. Interestingly, 11 apolipoprotein E (ApoE charge forms were decreased in DAT samples, indicating that ApoE charge form distributions may be important in the progression of DAT. In order to develop a classifier of chronic DAT, an independent blinded test set of 20 sea lions, seven with chronic DAT, was used to validate models utilizing ApoE charge forms and eosinophil counts. The resulting support vector machine had high sensitivity (85.7% with 92.3% negative predictive value and high specificity (92.3% with 85.7% positive predictive value. These results suggest that ApoE and eosinophil counts along with machine learning can perform as a robust and accurate tool to diagnose chronic DAT. Although this analysis is specifically focused on blood biomarkers and routine clinical data, the results demonstrate promise for future studies combining additional variables in multidimensional space to create robust classifiers.

  2. Apolipoprotein E epsilon 4 (APOE-ε4) genotype is associated with decreased 6-month verbal memory performance after mild traumatic brain injury

    NARCIS (Netherlands)

    J.K. Yue (John); Robinson, C.K. (Caitlin K.); J.F. Burke (John F.); E.A. Winkler (Ethan A.); Deng, H. (Hansen); M.C. Cnossen (Maryse); H.F. Lingsma (Hester); A.R. Ferguson (Adam); McAllister, T.W. (Thomas W.); J. Rosand (Jonathan); E.G. Burchard (Esteban); M.D. Sorani (Marco); S. Sharma (Sourabh); J.L. Nielson (Jessica L.); G.G. Satris (Gabriela G.); Talbott, J.F. (Jason F.); P.E. Tarapore (Phiroz E.); F.K. Korley (Frederick K.); Wang, K.K.W. (Kevin K.W.); E.L. Yuh (Esther); P. Mukherjee (Pratik); R. Diaz-Arrastia (Ramon); A.B. Valadka (Alex); D. Okonkwo (David); G. Manley (Geoffrey)

    2017-01-01

    textabstractIntroduction: The apolipoprotein E (APOE) ε4 allele associates with memory impairment in neurodegenerative diseases. Its association with memory after mild traumatic brain injury (mTBI) is unclear. Methods: mTBI patients (Glasgow Coma Scale score 13–15, no neurosurgical intervention,

  3. Apolipoprotein E Genotype and educational attainment predict the rate of cognitive decline in normal aging? A 12-year follow-up of the Maastricht Aging Study

    NARCIS (Netherlands)

    van Gerven, P.W.; van Boxtel, M.P.J.; Bekers, O.; Ausems, E.E.B.; Jolles, J.

    2012-01-01

    Objective: We investigated suspected longitudinal interaction effects of apolipoprotein E (APOE) genotype and educational attainment on cognitive decline in normal aging. Method: Our sample consisted of 571 healthy, nondemented adults aged between 49 and 82 years. Linear mixed-models analyses were

  4. Convulxin forms a dimer in solution and can bind eight copies of glycoprotein VI: implications for platelet activation.

    Science.gov (United States)

    Horii, Katsunori; Brooks, Monica T; Herr, Andrew B

    2009-04-07

    Convulxin (CVX) is a C-type lectin-like protein from the venom of the South American rattlesnake that functions as a potent agonist of the platelet collagen receptor glycoprotein VI (GPVI). Although CVX is widely used as a platelet agonist, the molecular basis for its extremely high potency is not clear. In order to delineate possible mechanisms for CVX-induced GPVI activation, we used analytical ultracentrifugation to determine the assembly state of CVX in solution and surface plasmon resonance in order to understand the affinity, kinetics, and stoichiometry of GPVI binding to CVX. We show here that CVX exists in solution as a dimer of alpha4beta4 rings, yielding eight potential binding sites for GPVI. Binding studies confirm that all eight sites are able to bind GPVI tightly, each with high picomolar or low nanomolar affinity. Reanalysis of previously determined crystal structures of CVX revealed the dimer in both structures. The dimeric nature of CVX and its ability to bind eight GPVI molecules suggest that it might be capable of binding to GPVI expressed on two opposing surfaces. Agglutination assays using GPVI-coated beads confirm that CVX is able to bridge distinct GPVI-coated surfaces and indicate that CVX agglutination of platelets is dependent on GPVI binding. Thus, in addition to clustering up to eight GPVI receptors, CVX may facilitate platelet activation by bridging platelets directly.

  5. Apolipoprotein E-knockout mice on high-fat diet show autoimmune injury on kidney and aorta

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuehai [Cardiovascular Department, Liaocheng People’s Hospital of Shandong University, Liaocheng, Shandong 252000 (China); Cardiovascular Department, The Second Clinical Medical College of Fujian Medical University, Quanzhou, Fujian 362000 (China); Lu, Huixia [The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Jinan, Shandong 250012 (China); Huang, Ziyang, E-mail: huangziyang666@126.com [Cardiovascular Department, The Second Clinical Medical College of Fujian Medical University, Quanzhou, Fujian 362000 (China); Lin, Huili [Cardiovascular Department, The Second Clinical Medical College of Fujian Medical University, Quanzhou, Fujian 362000 (China); Lei, Zhenmin [Department of OB/GYN, University of Louisville School of Medicine, Louisville, KY 40292 (United States); Chen, Xiaoqing [Department of Rheumatism and Immunology, The Second Clinical Medical College of Fujian Medical University, Quanzhou, Fujian 362000 (China); Tang, Mengxiong; Gao, Fei; Dong, Mei [The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Jinan, Shandong 250012 (China); Li, Rongda [Department of Rheumatism and Immunology, The Second Clinical Medical College of Fujian Medical University, Quanzhou, Fujian 362000 (China); Lin, Ling, E-mail: qzlinl@163.com [Department of Rheumatism and Immunology, The Second Clinical Medical College of Fujian Medical University, Quanzhou, Fujian 362000 (China)

    2014-07-18

    Highlights: • Titers of ANA and anti-dsDNA antibodies were similar in ApoE{sup −/−} and Fas{sup −/−} mice. • The spleen weights and glomerular areas were similar in ApoE{sup −/−} and Fas{sup −/−} mice. • Expressions of IgG and C3 in glomeruli were similar in ApoE{sup −/−} and Fas{sup −/−} mice. • IgG, C3 and macrophage infiltration in aortic plaques were found in ApoE{sup −/−} mice. - Abstract: Background: Apolipoprotein E-knockout (ApoE{sup −/−}) mice is a classic model of atherosclerosis. We have found that ApoE{sup −/−} mice showed splenomegaly, higher titers of serum anti-nuclear antibody (ANA) and anti-dsDNA antibody compared with C57B6/L (B6) mice. However, whether ApoE{sup −/−} mice show autoimmune injury remains unclear. Methods and results: Six females and six males in each group, ApoE{sup −/−}, Fas{sup −/−} and B6 mice, were used in this study. The titers of serum ANA, anti-dsDNA antibody and creatinine and urine protein were measured by ELISA after 4 months of high-fat diet. The spleen weight and the glomerular area were determined. The expressions of IgG, C3 and macrophage in kidney and atherosclerotic plaque were detected by immunostaining followed by morphometric analysis. Similar to the characteristics of Fas{sup −/−} mice, a model of systemic lupus erythematosus (SLE), ApoE{sup −/−} mice, especially female, displayed significant increases of spleen weight and glomerular area when compared to B6 mice. Also, elevated titers of serum ANA, anti-dsDNA antibody and creatinine and urine protein. Moreover, the expressions of IgG, C3 and macrophage in glomeruli and aortic plaques were found in ApoE{sup −/−} mice. In addition, the IgG and C3 expressions in glomeruli and plaques significantly increased (or a trend of increase) in female ApoE{sup −/−} mice compared with males. Conclusions: Apolipoprotein E-knockout mice on high-fat diet show autoimmune injury on kidney and aorta.

  6. Apolipoprotein E-knockout mice on high-fat diet show autoimmune injury on kidney and aorta

    International Nuclear Information System (INIS)

    Wang, Yuehai; Lu, Huixia; Huang, Ziyang; Lin, Huili; Lei, Zhenmin; Chen, Xiaoqing; Tang, Mengxiong; Gao, Fei; Dong, Mei; Li, Rongda; Lin, Ling

    2014-01-01

    Highlights: • Titers of ANA and anti-dsDNA antibodies were similar in ApoE −/− and Fas −/− mice. • The spleen weights and glomerular areas were similar in ApoE −/− and Fas −/− mice. • Expressions of IgG and C3 in glomeruli were similar in ApoE −/− and Fas −/− mice. • IgG, C3 and macrophage infiltration in aortic plaques were found in ApoE −/− mice. - Abstract: Background: Apolipoprotein E-knockout (ApoE −/− ) mice is a classic model of atherosclerosis. We have found that ApoE −/− mice showed splenomegaly, higher titers of serum anti-nuclear antibody (ANA) and anti-dsDNA antibody compared with C57B6/L (B6) mice. However, whether ApoE −/− mice show autoimmune injury remains unclear. Methods and results: Six females and six males in each group, ApoE −/− , Fas −/− and B6 mice, were used in this study. The titers of serum ANA, anti-dsDNA antibody and creatinine and urine protein were measured by ELISA after 4 months of high-fat diet. The spleen weight and the glomerular area were determined. The expressions of IgG, C3 and macrophage in kidney and atherosclerotic plaque were detected by immunostaining followed by morphometric analysis. Similar to the characteristics of Fas −/− mice, a model of systemic lupus erythematosus (SLE), ApoE −/− mice, especially female, displayed significant increases of spleen weight and glomerular area when compared to B6 mice. Also, elevated titers of serum ANA, anti-dsDNA antibody and creatinine and urine protein. Moreover, the expressions of IgG, C3 and macrophage in glomeruli and aortic plaques were found in ApoE −/− mice. In addition, the IgG and C3 expressions in glomeruli and plaques significantly increased (or a trend of increase) in female ApoE −/− mice compared with males. Conclusions: Apolipoprotein E-knockout mice on high-fat diet show autoimmune injury on kidney and aorta

  7. Demographic and Lifestyle Characteristics, but Not Apolipoprotein E Genotype, Are Associated with Intelligence among Young Chinese College Students.

    Directory of Open Access Journals (Sweden)

    Xiao-Fen Chen

    Full Text Available Intelligence is an important human feature that strongly affects many life outcomes, including health, life-span, income, educational and occupational attainments. People at all ages differ in their intelligence but the origins of these differences are much debated. A variety of environmental and genetic factors have been reported to be associated with individual intelligence, yet their nature and contribution to intelligence differences have been controversial.To investigate the contribution of apolipoprotein E (APOE genotype, which is associated with the risk for Alzheimer's disease, as well as demographic and lifestyle characteristics, to the variation in intelligence.A total of 607 Chinese college students aged 18 to 25 years old were included in this prospective observational study. The Chinese revision of Wechsler Adult Intelligence Scale (the fourth edition, short version was used to determine the intelligence level of participants. Demographic and lifestyle characteristics data were obtained from self-administered questionnaires.No significant association was found between APOE polymorphic alleles and different intelligence quotient (IQ measures. Interestingly, a portion of demographic and lifestyle characteristics, including age, smoking and sleep quality were significantly associated with different IQ measures.Our findings indicate that demographic features and lifestyle characteristics, but not APOE genotype, are associated with intelligence measures among young Chinese college students. Thus, although APOE ε4 allele is a strong genetic risk factor for Alzheimer's disease, it does not seem to impact intelligence at young ages.

  8. Age-dependent effect of apolipoprotein E4 on functional outcome after controlled cortical impact in mice.

    Science.gov (United States)

    Mannix, Rebekah C; Zhang, Jimmy; Park, Juyeon; Zhang, Xuan; Bilal, Kiran; Walker, Kendall; Tanzi, Rudolph E; Tesco, Giuseppina; Whalen, Michael J

    2011-01-01

    The apolipoprotein E4 (APOE4) gene leads to increased brain amyloid beta (Aβ) and poor outcome in adults with traumatic brain injury (TBI); however, its role in childhood TBI is controversial. We hypothesized that the transgenic expression of human APOE4 worsens the outcome after controlled cortical impact (CCI) in adult but not immature mice. Adult and immature APOE4 mice had worse motor outcome after CCI (P<0.001 versus wild type (WT)), but the Morris water maze performance was worse only in adult APOE4 mice (P=0.028 at 2 weeks, P=0.019 at 6 months versus WT), because immature APOE4 mice had performance similar to WT for up to 1 year after injury. Brain lesion size was similar in adult APOE4 mice but was decreased (P=0.029 versus WT) in injured immature APOE4 mice. Microgliosis was similar in all groups. Soluble brain Aβ(40) was increased at 48 hours after CCI in adult and immature APOE4 mice and in adult WT (P<0.05), and was dynamically regulated during the chronic period by APOE4 in adults but not immature mice. The data suggest age-dependent effects of APOE4 on cognitive outcome after TBI, and that therapies targeting APOE4 may be more effective in adults versus children with TBI.

  9. Lactobacillus acidophilus ATCC 4356 Prevents Atherosclerosis via Inhibition of Intestinal Cholesterol Absorption in Apolipoprotein E-Knockout Mice

    Science.gov (United States)

    Wang, Jinfeng; Quan, Guihua; Wang, Xiaojun; Yang, Longfei; Zhong, Lili

    2014-01-01

    The objective of this study was to investigate the effect of Lactobacillus acidophilus ATCC 4356 on the development of atherosclerosis in apolipoprotein E-knockout (ApoE−/−) mice. Eight-week-old ApoE−/− mice were fed a Western diet with or without L. acidophilus ATCC 4356 daily for 16 weeks. L. acidophilus ATCC 4356 protected ApoE−/− mice from atherosclerosis by reducing their plasma cholesterol levels from 923 ± 44 to 581 ± 18 mg/dl, likely via a marked decrease in cholesterol absorption caused by modulation of Niemann-Pick C1-like 1 (NPC1L1). In addition, suppression of cholesterol absorption induced reverse cholesterol transport (RCT) in macrophages through the peroxisome proliferator-activated receptor/liver X receptor (PPAR/LXR) pathway. Fecal lactobacillus and bifidobacterium counts were significantly (P intestine, colon, and feces during the feeding trial. The bacterial levels remained high even after the administration of lactic acid bacteria had been stopped for 2 weeks. These results suggest that administration of L. acidophilus ATCC 4356 can protect against atherosclerosis through the inhibition of intestinal cholesterol absorption. Therefore, L. acidophilus ATCC 4356 may be a potential therapeutic material for preventing the progression of atherosclerosis. PMID:25261526

  10. Chicory, a typical vegetable in Mediterranean diet, exerts a therapeutic role in established atherosclerosis in apolipoprotein E-deficient mice.

    Science.gov (United States)

    Lin, Weiqun; Liu, Chaoqun; Yang, Hai; Wang, Wenting; Ling, Wenhua; Wang, Dongliang

    2015-09-01

    Since protocatechuic acid exerts an atheroprotective role, we investigated how chicory (Cichorium intybus L. var. foliosum, Belgian endive) rich in protocatechuic acid, a typical vegetable in Mediterranean diet, affects preestablished atherosclerosis progression. Apolipoprotein E-deficient mice fed AIN diets containing 0.5% freeze-dried chicory for 10 weeks displayed a reduction in lesion size with a concomitant improvement in lesion stability indicated by fewer macrophages and more collagen content. Chicory consumption suppressed aortic cholesterol accumulation and intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and monocyte chemoattractant protein-1 expression, whereas it increased aortic ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1) expression. Furthermore, chicory consumption improved peritoneal macrophage phenotype with less cellular cholesterol associated with an enhancement of cholesterol efflux capacity through upregulation of ABCA1 and ABCG1, less cellular oxidative stress associated with an inhibition of nicotinamide adenine dinucleotide phosphate oxidase activity, and weaker inflammatory responses associated with an inhibition of nuclear factor-κB activation. Interestingly, ABCA1 and ABCG1 silencing tended to completely block beneficial effects of chicory in peritoneal macrophages. Chicory exerts an atheroprotective role in mice possibly by regulating lesional macrophage content and phenotype, suggesting that chicory is one underrated contributor to Mediterranean Diet-induced atheroprotection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Apolipoprotein E epsilon 4 allele and outcomes of traumatic spinal cord injury in a Chinese Han population.

    Science.gov (United States)

    Sun, Chongyi; Ji, Guangrong; Liu, Qingpeng; Yao, Meng

    2011-10-01

    The association between apolipoprotein E (APOE) epsilon 4 (ε4) allele and outcomes of traumatic spinal cord injury (SCI) is still controversial and ambiguous. The objective of this study was to test the hypothesis that APOE polymorphisms are associated with outcomes after SCI in Chinese Han patients. APOE polymorphisms were determined in 100 patients with cervical SCI (C3-C8). The genotype frequency of this polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. Patients with an APOE ε4 allele had significantly less motor recovery during rehabilitation than did patients without an APOE ε4 allele (mean 3.7 vs. 6.1; P = 0.04) and a longer rehabilitation length of stay (LOS) (mean 117.4 vs. 94.5; P = 0.02), but better sensory-pinprick recovery (mean 6.1 vs. 4.0; P = 0.03). There were no significant differences by APOE ε4 allele status in sensory-light touch recovery or acute LOS. This study suggests that the APOE ε4 allele is associated with outcomes after SCI and longer rehabilitation LOS in Chinese Han patients.

  12. Dietary Flaxseed Oil Prevents Western-Type Diet-Induced Nonalcoholic Fatty Liver Disease in Apolipoprotein-E Knockout Mice

    Directory of Open Access Journals (Sweden)

    Hao Han

    2017-01-01

    Full Text Available The prevalence of nonalcoholic fatty liver disease (NAFLD has dramatically increased globally during recent decades. Intake of n-3 polyunsaturated fatty acids (PUFAs, mainly eicosapentaenoic acid (EPA, C20:5n-3 and docosahexaenoic acid (DHA, C22:6n-3, is believed to be beneficial to the development of NAFLD. However, little information is available with regard to the effect of flaxseed oil rich in α-linolenic acid (ALA, C18:3n-3, a plant-derived n-3 PUFA, in improving NAFLD. This study was to gain the effect of flaxseed oil on NAFLD and further investigate the underlying mechanisms. Apolipoprotein-E knockout (apoE-KO mice were given a normal chow diet, a western-type high-fat and high-cholesterol diet (WTD, or a WTD diet containing 10% flaxseed oil (WTD + FO for 12 weeks. Our data showed that consumption of flaxseed oil significantly improved WTD-induced NAFLD, as well as ameliorated impaired lipid homeostasis, attenuated oxidative stress, and inhibited inflammation. These data were associated with the modification effects on expression levels of genes involved in de novo fat synthesis (SREBP-1c, ACC, triacylglycerol catabolism (PPARα, CPT1A, and ACOX1, inflammation (NF-κB, IL-6, TNF-α, and MCP-1, and oxidative stress (ROS, MDA, GSH, and SOD.

  13. Whole Body Vibration Retards Progression of Atherosclerosis via Insulin-Like Growth Factor 1 in Apolipoprotein E-Deficient Mice

    Directory of Open Access Journals (Sweden)

    He Wu

    2018-01-01

    Full Text Available Whole body vibration (WBV has a marked impact on lipid metabolism and the endocrine system, which is related to the progression of atherosclerosis (AS. To investigate the effects of WBV, we measured the atherosclerotic plaque area of apolipoprotein E-knockout (ApoE−/− AS mice, which were trained by WBV (15 Hz, 30 min for 12 weeks. Simultaneously, serum levels of lipids, insulin-like growth factor 1 (IGF-1, insulin-like growth factor 1 receptor (IGF-1R, interleukin 6 (IL-6, and the mRNA and protein levels of the same in the aorta were compared between the control and WBV groups. The results indicated that WBV significantly reduced the atherosclerotic plaque area with lower very low-density lipoprotein (VLDL and oxidized low-density lipoprotein (ox-LDL in the blood. Moreover, the levels of IGF-1 in serum and expression of IL-6, IGF-1R, and p-IGF-1R protein in the mice aorta decreased significantly in the WBV group. In addition, we found that serum IGF-1 in mice increased to the highest concentration in 30 min after WBV for 10, 30, 60, and 120 minutes. These results suggested that appropriate WBV may delay the progression of AS, which was associated with acutely elevated serum IGF-1 and lower levels of IGF-1 and IL-6 in the aorta for long-term treatment.

  14. Whole Body Vibration Retards Progression of Atherosclerosis via Insulin-Like Growth Factor 1 in Apolipoprotein E-Deficient Mice.

    Science.gov (United States)

    Wu, He; Zhang, Yibo; Yang, Xuan; Li, Xian; Shao, Zhenya; Zhou, Zipeng; Li, Yuanlong; Pan, Shuwen; Liu, Chang

    2018-01-01

    Whole body vibration (WBV) has a marked impact on lipid metabolism and the endocrine system, which is related to the progression of atherosclerosis (AS). To investigate the effects of WBV, we measured the atherosclerotic plaque area of apolipoprotein E-knockout (ApoE -/- ) AS mice, which were trained by WBV (15 Hz, 30 min) for 12 weeks. Simultaneously, serum levels of lipids, insulin-like growth factor 1 (IGF-1), insulin-like growth factor 1 receptor (IGF-1R), interleukin 6 (IL-6), and the mRNA and protein levels of the same in the aorta were compared between the control and WBV groups. The results indicated that WBV significantly reduced the atherosclerotic plaque area with lower very low-density lipoprotein (VLDL) and oxidized low-density lipoprotein (ox-LDL) in the blood. Moreover, the levels of IGF-1 in serum and expression of IL-6, IGF-1R, and p-IGF-1R protein in the mice aorta decreased significantly in the WBV group. In addition, we found that serum IGF-1 in mice increased to the highest concentration in 30 min after WBV for 10, 30, 60, and 120 minutes. These results suggested that appropriate WBV may delay the progression of AS, which was associated with acutely elevated serum IGF-1 and lower levels of IGF-1 and IL-6 in the aorta for long-term treatment.

  15. Apolipoprotein E epsilon 4 allele distribution in Wernicke-Korsakoff syndrome with or without global intellectual deficits.

    Science.gov (United States)

    Muramatsu, T; Kato, M; Matsui, T; Yoshimasu, H; Yoshino, A; Matsushita, S; Higuchi, S; Kashima, H

    1997-01-01

    Recent genetic studies show that the apolipoprotein E (ApoE) epsilon 4 allele is a risk factor for Alzheimer's disease (AD). Whether this allele is associated with other dementing diseases is the next important question. The information could provide a clue to the pathogenetic role of ApoE. In the present study, patients with Wernicke-Korsakoff syndrome (WKS) of alcoholic etiology were divided into two groups according to the severity of intellectual deficits, i.e., those of "classical" Korsakoff patients with preserved intellectual function other than amnesia and those with global intellectual deficits. Genotyping showed that the frequency of ApoE epsilon 4 allele was significantly higher in the patients with global deficits, suggesting the involvement of this allele in the intellectual decline of WKS. In contrast, distributions of other two markers, alpha 1-antichymotrypsin and presenilin-1, did not differ between the two groups. These results added further support to the notion that the consequence of acute insult to the brain is influenced by the ApoE genotype, and suggested ApoE's role in the development of a certain group of "alcoholic dementia."

  16. Spatial pattern separation differences in older adult carriers and non-carriers for the apolipoprotein E epsilon 4 allele.

    Science.gov (United States)

    Sheppard, David P; Graves, Lisa V; Holden, Heather M; Delano-Wood, Lisa; Bondi, Mark W; Gilbert, Paul E

    2016-03-01

    We examined the performance of healthy young (n=57) and older adults (n=43) genotyped as apolipoprotein E-ε4 (APOE-ε4) carriers or APOE-ε4 non-carriers on a delayed match-to-sample task involving varying degrees of spatial interference hypothesized to assess spatial pattern separation. Older adult ε4 carriers were further divided into "impaired" and "unimpaired" groups based on their performance on a standardized test of verbal memory. We found that performance on the spatial pattern separation test increased as a function of decreased spatial interference across all groups. The older ε4 carriers in the impaired group performed significantly worse (ppattern separation may be less efficient in a subset of healthy older adults with subtle memory decline who are carriers of the ε4 allele. However, pattern separation performance may be comparable to that of young adults in a subset of older adult ε4 carriers and more broadly among non-carriers. Our findings offer additional evidence that pattern separation may vary in older adults, and they provide novel insight into pattern separation efficiency in ε4-positive older adults. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Apolipoprotein E gene polymorphism and its effect on anthropometric measures in normoglycemic subjects and type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Tabatabaei-Malazy Ozra

    2012-10-01

    Full Text Available Abstract Background Apolipoprotein E (apo E plays a major role in lipid metabolism, obesity and accordingly in development of diabetes and coronary heart disease (CHD. Our main objective was to evaluate the association between apo E gene polymorphism with anthropometric measures. Methods Participants were selected from zone 17 Tehran/Iran. We assessed height, weight, body mass index (BMI, waist circumference (WC, blood pressure, serum fasting blood sugar, total cholesterol and triglycerides. Genotyping for apo E gene polymorphism was carried out using PCR-RFLP technique. Results Among total study population (n=311, 156 subjects were diabetic. The apo E3/E3 was the most common genotype in our population while E2 and E4 alleles had lower frequencies, respectively. After adjustment for diabetes, the apo E2 and E4 alleles were significantly associated with hypercholesterolemia and WC, respectively (p= 0.009, 0.034. This association was also related to sex and age. The probability of having abdominal obesity in E4 allele carriers was increased from 0.22 to 8.12 in women and to 3.08 in age ≥ 50 years. Conclusions Apo E polymorphism had significant influences on WC and total cholesterol level in patients with type 2 diabetes. This study highlights the importance of lifestyle modifications which may be more beneficial in hypercholesterolemic women carriers of E2 and E4 alleles concomitant central obesity.

  18. Demographic and Lifestyle Characteristics, but Not Apolipoprotein E Genotype, Are Associated with Intelligence among Young Chinese College Students.

    Science.gov (United States)

    Chen, Xiao-Fen; Wei, Zichen; Wang, Tingting; Zhang, Zhen-Lian; Wang, Yiwei; Heckman, Michael G; Diehl, Nancy N; Zhang, Yun-Wu; Xu, Huaxi; Bu, Guojun

    2015-01-01

    Intelligence is an important human feature that strongly affects many life outcomes, including health, life-span, income, educational and occupational attainments. People at all ages differ in their intelligence but the origins of these differences are much debated. A variety of environmental and genetic factors have been reported to be associated with individual intelligence, yet their nature and contribution to intelligence differences have been controversial. To investigate the contribution of apolipoprotein E (APOE) genotype, which is associated with the risk for Alzheimer's disease, as well as demographic and lifestyle characteristics, to the variation in intelligence. A total of 607 Chinese college students aged 18 to 25 years old were included in this prospective observational study. The Chinese revision of Wechsler Adult Intelligence Scale (the fourth edition, short version) was used to determine the intelligence level of participants. Demographic and lifestyle characteristics data were obtained from self-administered questionnaires. No significant association was found between APOE polymorphic alleles and different intelligence quotient (IQ) measures. Interestingly, a portion of demographic and lifestyle characteristics, including age, smoking and sleep quality were significantly associated with different IQ measures. Our findings indicate that demographic features and lifestyle characteristics, but not APOE genotype, are associated with intelligence measures among young Chinese college students. Thus, although APOE ε4 allele is a strong genetic risk factor for Alzheimer's disease, it does not seem to impact intelligence at young ages.

  19. Effect of apolipoprotein E variants on plasma lipids and apolipoproteins in the Orang Asli ('aborigines') of Malaysia.

    Science.gov (United States)

    Gajra, B; Candlish, J K; Saha, N; Mak, J W; Tay, J S

    1994-01-01

    Members of the Semai group of Orang Asli ('aborigines') in peninsular Malaysia were examined for apolipoprotein E (apo E) variants in relation to plasma total cholesterol (TC), high density lipoprotein cholesterol, low density lipoprotein cholesterol (LDLC), triglycerides (TG), apolipoprotein AI and apolipoprotein B (apo B). The e2 and e4 alleles were found to be higher than in most other groups as reported. The sample as a whole was normotriglyceridaemic (mean plasma TG, 1.5 mmol/l) and very markedly hypocholesterolaemic (mean plasma TC 1.7 mmol/l). The distribution of apo E variants was not related to any of the plasma lipids or apolipoprotein fractions using results from all subjects, but if a distinctly hypertriglyceridaemic sub-section was omitted (TG > 1.7 mmol/l) then apo E variants were determinants of plasma TC, LDLC, and apo B concentrations, the lower values of these being associated with the 2-2 and 2-3 genotypes, and the higher with 3-4, and 4-4.

  20. Inhalation exposure of gas-metal arc stainless steel welding fume increased atherosclerotic lesions in apolipoprotein E knockout mice.

    Science.gov (United States)

    Erdely, Aaron; Hulderman, Tracy; Salmen-Muniz, Rebecca; Liston, Angie; Zeidler-Erdely, Patti C; Chen, Bean T; Stone, Samuel; Frazer, David G; Antonini, James M; Simeonova, Petia P

    2011-07-04

    Epidemiological studies suggest that welding, a process which generates an aerosol of inhalable gases and metal rich particulates, increases the risk for cardiovascular disease. In this study we analyzed systemic inflammation and atherosclerotic lesions following gas metal arc-stainless steel (GMA-SS) welding fume exposure. Apolipoprotein E knockout (apoE(-/-)) mice, fed a Western diet, were exposed to GMA-SS at 40mg/m(3) for 3h/day for ten days (∼8.26μg daily alveolar deposition). Mice were sacrificed two weeks after exposure and serum chemistry, serum protein profiling and aortic lesion area were determined. There were no significant changes in serum total cholesterol, triglycerides or alanine aminotransferase. Serum levels of uric acid, a potent antioxidant, were decreased perhaps suggesting a reduced capacity to combat systemic oxidative stress. Inflammatory serum proteins interleukin 1 beta (IL-1β) and monocyte chemoattractant protein 3 (MCP-3) were increased two weeks after GMA-SS exposure. Analysis of atherosclerotic plaques showed an increase in lesion area as the result of GMA-SS exposure. In conclusion, GMA-SS exposure showed evidence of systemic inflammation and increased plaque progression in apoE(-/-) mice. These results complement epidemiological and functional human studies that suggest welding may result in adverse cardiovascular effects. Published by Elsevier Ireland Ltd.

  1. Influence of apolipoprotein E genotype on the transmission of Alzheimer disease in a community-based sample

    Energy Technology Data Exchange (ETDEWEB)

    Jarvik, G.P.; Larson, E.B.; Goddard, K. [Univ. of Washington Medical Center, Seattle, WA (United States)] [and others

    1996-01-01

    The {epsilon}4 allele of the apolipoprotein E locus (APOE) has been found to be an important predictor of Alzheimer disease (AD). However, linkage analysis has not clarified the role of APOE in the transmission of AD. The results of the current study provide evidence that the pattern of transmission of memory disorders differs in nuclear families in which the AD-affected proband did carry an {epsilon}4 allele versus those families in which the AD-affected proband did not carry an {epsilon}4 allele. Further, risk of AD due to APOE genotype in the probands is modified by family history of memory disorders, suggesting gene-by-gene interactions. Family history remained a significant predictor of AD for affected probands with some, but not all, APOE genotypes in a logistic regression analysis. Though nonadditive in the prediction of AD, APOE genotype and family history acted additively in the prediction of age at AD onset. The results of complex segregation analysis were inconsistent with Mendelian segregation of memory disorders both in families of affected probands who did or did not carry an {epsilon}4 allele, yet these two groups had significantly different parameter estimates for their transmission models. These results are consistent with gene-by-gene interactions, but also could result from common elements in the familial environment. 41 refs., 1 fig., 7 tabs.

  2. Long-term Western diet fed apolipoprotein E-deficient rats exhibit only modest early atherosclerotic characteristics.

    Science.gov (United States)

    Rune, Ida; Rolin, Bidda; Lykkesfeldt, Jens; Nielsen, Dennis Sandris; Krych, Łukasz; Kanter, Jenny E; Bornfeldt, Karin E; Kihl, Pernille; Buschard, Karsten; Josefsen, Knud; Fels, Johannes Josef; Mortensen, Alan; Christoffersen, Berit; Kirk, Rikke Kaae; Hansen, Axel Kornerup

    2018-04-03

    In the apolipoprotein E-deficient mouse, the gut microbiota has an impact on the development of atherosclerosis, but whether such correlations are also present in rats requires investigation. Therefore, we studied female SD-Apoe tm1sage (Apoe -/- ) rats fed either a Western diet or a low-fat control diet with or without gluten, which is known to promote gut microbiota changes, until 20 weeks of age. We hypothesized that the manifestation of atherosclerosis would be more severe in Apoe -/- rats fed the Western high-fat diet, as compared with rats fed the low-fat diet, and that atherosclerosis would be accelerated by gluten. Both Western diet-feeding and gluten resulted in significant changes in gut microbiota, but the microbiota impact of gluten was transient. Compared with Apoe -/- rats fed a low-fat diet, Western diet-fed Apoe -/- rats were heavier and became glucose intolerant with increased levels of oxidative stress. They developed early fatty streak lesions in their aortic sinus, while there was no evidence of atherosclerosis in the thoracic aorta. No conclusions could be made on the impact of gluten on atherosclerosis. Although Western diet-fed Apoe -/- rats exhibited a more human-like LDL dominated blood lipid profile, signs of obesity, type 2 diabetes and cardiovascular disease were modest.

  3. Glycine Transporter Dimers

    Science.gov (United States)

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette; Dutertre, Sébastien; Hastrup, Hanne; Jha, Alok; Gether, Ulrik; Sitte, Harald H.; Betz, Heinrich; Eulenburg, Volker

    2015-01-01

    Different Na+/Cl−-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma membrane based on hydrodynamic and native gel electrophoretic studies. Here, we used cysteine substitution and oxidative cross-linking to show that of GlyT1 and GlyT2 also form dimeric complexes within the plasma membrane. GlyT oligomerization at the cell surface was confirmed for both GlyT1 and GlyT2 by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization that was retained intracellulary. Based on these results and GlyT structures modeled by using the crystal structure of the bacterial homolog LeuTAa, as a template, residues located within the extracellular loop 3 and at the beginning of transmembrane domain 6 are proposed to contribute to the dimerization interface of GlyTs. PMID:18252709

  4. Estimation of apolipoprotein E genotype-specific relative mortality risks from the distribution of genotypes in centenarians and middle-aged men

    DEFF Research Database (Denmark)

    Gerdes, U.; Jeune, Bernard; Andersen-Ranberg, Karen

    2000-01-01

    We developed a method to estimate genotype-specific average relative mortality risk, R, from genotype distributions in cross-sectional studies of people belonging to different age-groups, and applied the method to new data from a study of apolipoprotein E genotypes (apoE) in 177 Danish centenaria...... of this kind, they are more impressive and may propagate the misconception that apoE is a "longevity gene"....

  5. Impact of psychological stress on the associations between apolipoprotein E variants and metabolic traits: findings in an American sample of caregivers and controls

    DEFF Research Database (Denmark)

    Kring, Sofia Iqbal; Brummett, Beverly H; Barefoot, John

    2010-01-01

    To examine the association between apolipoprotein E (APOE) gene variants and waist circumference, fasting plasma glucose, serum insulin, serum high-density lipoprotein cholesterol, and serum triglycerides, all metabolic traits known as cardiovascular disease (CVD) endophenotypes, in a population ...... of stressed individuals and controls. Abdominal obesity, insulin resistance, elevated serum lipid concentration, and APOE polymorphisms have been associated with CVD risk. Current evidence supports the hypothesis that gene-environment interactions modulate serum lipid concentrations....

  6. The Dipeptidyl Peptidase-4 Inhibitor Sitagliptin Protects against Dyslipidemia-Related Kidney Injury in Apolipoprotein E Knockout Mice

    Directory of Open Access Journals (Sweden)

    Jingjing Li

    2014-06-01

    Full Text Available The goal of this study was to investigate the possible protective effects of sitagliptin against dyslipidemia-related kidney injury in apolipoprotein E knockout (apoE−/− mice. Eight-week-old male apoE−/− mice were randomized to receive either a high fat diet (HFD, apoE−/− group or HFD mixed with sitagliptin (sita + apoE−/− group for 16 weeks. A control group of age- and gender-matched C57BL/6J mice were fed a HFD. The apoE−/− group exhibited increases in body weight and serum lipid levels in addition to high-density lipoprotein, and increases in 24-h urinary 8-hydroxy-2-deoxyguanosine and albuminuria excretion. Decreased insulin sensitivity was also observed in the apoE−/− group. These mice additionally contained enlargements of the glomerular mesangial matrix area, lipid deposition area, and renal interstitium collagen area. The apoE−/− group also demonstrated down-regulation of phosphorylated AMP-activated protein kinase (AMPK, increases in renal mRNA expression of transforming growth factor-beta 1 (TGF-β1 and fibronectin (FN, and increased protein expression of Akt, TGF-β1, FN and p38/ERK mitogen-activated protein kinase (MAPK. Sitagliptin treatment successfully ameliorated all the deleterious effects of dyslipidemia tested. To our knowledge, this is the first time that sitagliptin has been shown to reverse the renal dysfunction and structural damage induced by dyslipidemia in apoE−/− mice. Our results suggest that the renoprotective mechanism of sitagliptin may be due to a reduction in Akt levels, a restoration of AMPK activity, and inhibition of TGF-β1, FN, and p38/ERK MAPK signaling pathways.

  7. Metformin reduces the endotoxin-induced down-regulation of apolipoprotein E gene expression in macrophages

    Energy Technology Data Exchange (ETDEWEB)

    Stavri, Simona; Trusca, Violeta G.; Simionescu, Maya; Gafencu, Anca V., E-mail: anca.gafencu@icbp.ro

    2015-05-29

    The atheroprotective role of macrophage-derived apolipoprotein E (apoE) is well known. Our previous reports demonstrated that inflammatory stress down-regulates apoE expression in macrophages, aggravating atherogenesis. Metformin, extensively used as an anti-diabetic drug, has also anti-inflammatory properties, and thus confers vascular protection. In this study, we questioned whether metformin could have an effect on apoE expression in macrophages in normal conditions or under lipopolysaccharide (LPS)-induced stress. The results showed that metformin slightly increases the apoE expression only at high doses (5–10 mM). Low doses of metformin (1–3 mM) significantly reduce the LPS down-regulatory effect on apoE expression in macrophages. Our experiments demonstrated that LPS-induced NF-κB binds to the macrophage-specific distal regulatory element of apoE gene, namely to the multienhancer 2 (ME.2) and its 5′-deletion fragments. The NF-κB binding on ME.2 and apoE promoter has a down-regulatory effect. In addition, data revealed that metformin impairs NF-κB nuclear translocation, and thus, improves the apoE levels in macrophages under inflammatory stress. The positive effect of metformin in the inflammatory states, its clinical safety and low cost, make this drug a potential adjuvant in the therapeutic strategies for atherosclerosis. - Highlights: • High doses of metformin slightly increase apoE expression in macrophages. • Low doses of metformin up-regulate apoE gene in endotoxin-stressed macrophages. • Metformin reduces the negative effect of LPS on apoE expression by NF-κB inhibition.

  8. Effects of radiation and apolipoprotein E on lipid profile among workers of nuclear power plants in Korea

    International Nuclear Information System (INIS)

    Ki-Eun Moon; Mee-Seon Jung; Suk-Hee Sung; Youn-Koun Chang; Il-Keun Park; Yun-Mi Paek; Tae-In Choi; Soo-Geun Kim

    2007-01-01

    Complete text of publication follows. Several studies reported that the radiation was positively related to fatty liver, low HDL cholesterol, and hypertriglyceridemia. Genetic polymorphism affect prevalence of chronic disease by molecular epidemiology studies. Apolipoprotein E is an important genetic determinant of cardiovascular disease (CVD), namely through its influence on lipid metabolism. Thus, we investigated whether radiation and apo E polymorphism, and environmental factors contribute to the lipid profile in workers of nuclear power plants in Korea. DNA was extracted from the whole blood of 6896 study subjects (6357 males and 359 females), and apo E polymorphism was investigated using PCR. Plasma lipid profiles were measured by standardized enzymatic procedures and radiation dose was measured by the thermoluminescence dosemeter (TLD). Environmental factors such as exercise, smoking were measured from health management database of KHNP. Total of 6802 subjects (aged 20-58) were investigated and radiation exposure dose was 168.51±463.94 mSv in the recent 1-year dose and 248.24±559.21 mSv in the total accumulative dose. In addition, Apo E polymorphism was associated with significant differences in total cholesterol, HDL cholesterol, radiation dose, AI but others no significant. The multiple regression model showed that total cholesterol was positively correlated with age, SBP, BMI, AI, fasting glucose. HDL cholesterol was negatively correlated with AI. LDL cholesterol was positively correlated with age, BMI, fasting glucose. And triglyceride was significantly correlated in the BMI, AI, somking dose, vegetables but others no significant. Metabolic syndrome did not show any relation to the others; only age, SBP, DBP, BMI, fasting glucose, HOMA-IR influenced. However, there was no significant association between radiation dose and lipid profile. In conclusion, Apo E and well-known variables such as SBP, BMI were significantly associated with lipid profile level

  9. Analysis of the Association Between Apolipoprotein E Polymorphism and Cardiovascular Risk Factors in an Elderly Population with Longevity

    Directory of Open Access Journals (Sweden)

    Schwanke Carla Helena Augustin

    2002-01-01

    Full Text Available OBJECTIVE: To establish the allelic and genotypic frequencies related to apolipoprotein E (ApoE polymorphism and association of the genotypes with risk factors and cardiovascular morbidity in an elderly population with longevity. METHODS: We analyzed 70 elderly patients aged 80 years or more who were part of the Projeto Veranópolis. We used the gene amplification technique through the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP and cleavage with the restriction enzyme Hha I to identify the ApoE genotypes. The most frequent genotypes were compared considering biological variables and cardiovascular risks and morbidity. RESULTS: The frequencies of the E2, E3, and E4 alleles were 0.05, 0.84, and 0.11, respectively, and of the genotypes were as follows: E3E3 (0.70, E3E4 (0.22, E2E3 (0.06, and E2E2 (0.02. Individuals with the E3E4 had a mean age greater than those with the E3E3. No association was observed between the genotypes and the variables analyzed, except for obesity, which was associated with the E3E3 genotype. Individuals with the E3E4 genotype had high levels of LDL-cholesterol and fibrinogen as compared with those with the E3E3 genotype. CONCLUSION: The results suggest that the E4E4 genotype may be associated with early mortality. A balance between the protective or neutral factors and the cardiovascular risk factors may occur among the individuals with different genotypes, attenuating the negative effects of the E4 allele.

  10. Apolipoprotein E4 Allele and Gait Performance in Mild Cognitive Impairment: Results From the Gait and Brain Study.

    Science.gov (United States)

    Sakurai, Ryota; Montero-Odasso, Manuel

    2017-11-09

    The apolipoprotein E polymorphism ε4 allele (ApoE4) and gait impairment are both known risk factors for developing cognitive decline and dementia. However, it is unclear the interrelationship between these factors, particularly among older adults with mild cognitive impairment (MCI) who are considered as prodromal for Alzheimer's disease. This study aimed to determine whether ApoE4 carrier individuals with MCI may experience greater impairment in gait performance. Fifty-six older adults with MCI from the "Gait and Brain Study" who were identified as either ApoE4 carriers (n = 20) or non-ApoE4 carriers (n = 36) with 1 year of follow-up were included. Gait variability, the main outcome variable, was assessed as stride time variability with an electronic walkway. Additional gait variables and cognitive performance (mini-mental state examination [MMSE] and Montreal Cognitive Assessment [MoCA]) were also recorded. Covariates included age, sex, education level, body mass index, and number of comorbidities. Baseline characteristics were similar for both groups. Repeated measures analysis of covariance showed that gait stride time and stride length variabilities significantly increased in ApoE4 carriers but was maintained in the non-ApoE4 carriers. Similarly, ApoE4 carriers showed greater decrease in MMSE score at follow-up. In this sample of older adults with MCI, the presence of at least one copy of ApoE4 was associated with the development of both increased gait variability and cognitive decline during 1 year of follow-up. ApoE4 genotype might be considered as a potential mediator of decline in mobility function in MCI; future studies with larger samples are needed to confirm our preliminary findings. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Loss of PDZK1 causes coronary artery occlusion and myocardial infarction in Paigen diet-fed apolipoprotein E deficient mice.

    Directory of Open Access Journals (Sweden)

    Ayce Yesilaltay

    2009-12-01

    Full Text Available PDZK1 is a four PDZ-domain containing protein that binds to the carboxy terminus of the HDL receptor, scavenger receptor class B type I (SR-BI, and regulates its expression, localization and function in a tissue-specific manner. PDZK1 knockout (KO mice are characterized by a marked reduction of SR-BI protein expression ( approximately 95% in the liver (lesser or no reduction in other organs with a concomitant 1.7 fold increase in plasma cholesterol. PDZK1 has been shown to be atheroprotective using the high fat/high cholesterol ('Western' diet-fed murine apolipoprotein E (apoE KO model of atherosclerosis, presumably because of its role in promoting reverse cholesterol transport via SR-BI.Here, we have examined the effects of PDZK1 deficiency in apoE KO mice fed with the atherogenic 'Paigen' diet for three months. Relative to apoE KO, PDZK1/apoE double KO (dKO mice showed increased plasma lipids (33% increase in total cholesterol; 49 % increase in unesterified cholesterol; and 36% increase in phospholipids and a 26% increase in aortic root lesions. Compared to apoE KO, dKO mice exhibited substantial occlusive coronary artery disease: 375% increase in severe occlusions. Myocardial infarctions, not observed in apoE KO mice (although occasional minimal fibrosis was noted, were seen in 7 of 8 dKO mice, resulting in 12 times greater area of fibrosis in dKO cardiac muscle.These results show that Paigen-diet fed PDZK1/apoE dKO mice represent a new animal model useful for studying coronary heart disease and suggest that PDZK1 may represent a valuable target for therapeutic intervention.

  12. Enhanced capillary electrophoretic screening of Alzheimer based on direct apolipoprotein E genotyping and one-step multiplex PCR.

    Science.gov (United States)

    Woo, Nain; Kim, Su-Kang; Sun, Yucheng; Kang, Seong Ho

    2018-01-01

    Human apolipoprotein E (ApoE) is associated with high cholesterol levels, coronary artery disease, and especially Alzheimer's disease. In this study, we developed an ApoE genotyping and one-step multiplex polymerase chain reaction (PCR) based-capillary electrophoresis (CE) method for the enhanced diagnosis of Alzheimer's. The primer mixture of ApoE genes enabled the performance of direct one-step multiplex PCR from whole blood without DNA purification. The combination of direct ApoE genotyping and one-step multiplex PCR minimized the risk of DNA loss or contamination due to the process of DNA purification. All amplified PCR products with different DNA lengths (112-, 253-, 308-, 444-, and 514-bp DNA) of the ApoE genes were analyzed within 2min by an extended voltage programming (VP)-based CE under the optimal conditions. The extended VP-based CE method was at least 120-180 times faster than conventional slab gel electrophoresis methods In particular, all amplified DNA fragments were detected in less than 10 PCR cycles using a laser-induced fluorescence detector. The detection limits of the ApoE genes were 6.4-62.0pM, which were approximately 100-100,000 times more sensitive than previous Alzheimer's diagnosis methods In addition, the combined one-step multiplex PCR and extended VP-based CE method was also successfully applied to the analysis of ApoE genotypes in Alzheimer's patients and normal samples and confirmed the distribution probability of allele frequencies. This combination of direct one-step multiplex PCR and an extended VP-based CE method should increase the diagnostic reliability of Alzheimer's with high sensitivity and short analysis time even with direct use of whole blood. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Osteoprotegerin deficiency limits angiotensin II-induced aortic dilatation and rupture in the apolipoprotein E-knockout mouse.

    Science.gov (United States)

    Moran, Corey S; Jose, Roby J; Biros, Erik; Golledge, Jonathan

    2014-12-01

    Mounting evidence links osteoprotegerin with cardiovascular disease. Elevated serum and aortic tissue osteoprotegerin are associated with the presence and growth of abdominal aortic aneurysm in humans; however, a role for osteoprotegerin in abdominal aortic aneurysm pathogenesis remains to be shown. We examined the functional significance of osteoprotegerin in aortic aneurysm using an Opg-deficient mouse model and in vitro investigations. Homozygous deletion of Opg in apolipoprotein E-deficient mice (ApoE(-/-)Opg(-/-)) inhibited angiotensin II-induced aortic dilatation. Survival free from aortic rupture was increased from 67% in ApoE(-/-)Opg(+/+) controls to 94% in ApoE(-/-)Opg(-/-) mice (P=0.040). Serum concentrations of proinflammatory cytokines/chemokines, and aortic expression for cathepsin S (CTSS), matrix metalloproteinase 2, and matrix metalloproteinase 9 after 7 days (early-phase) of angiotensin II infusion were significantly reduced in ApoE(-/-)Opg(-/-) mice compared with ApoE(-/-)Opg(+/+) controls. In addition, aortic expression of markers for an inflammatory phenotype in aortic vascular smooth muscle cells in response to early-phase of angiotensin II infusion was significantly lower in Opg-deficient mice. In vitro, human abdominal aortic aneurysm vascular smooth muscle cells produced more CTSS and exhibited increased CTSS-derived elastolytic activity than healthy aortic vascular smooth muscle cells, whereas recombinant human osteoprotegerin stimulated CTSS-dependent elastase activity in aortic vascular smooth muscle cells. These findings support a role for osteoprotegerin in aortic aneurysm through upregulation of CTSS, matrix metalloproteinase 2, and matrix metalloproteinase 9 within the aorta, promoting an inflammatory phenotype in aortic vascular smooth muscle cells in response to angiotensin II. © 2014 American Heart Association, Inc.

  14. The relationship of the apolipoprotein E gene polymorphism in Turkish Type 2 Diabetic Patients with and without diabetic foot ulcers.

    Science.gov (United States)

    Mehmet, Erdogan; Zuhal, Eroglu; Mustafa, Kulaksizoglu; Soner, Solmaz; Aslı, Tetik; Sevki, Cetinkalp

    2016-01-01

    The aim of this study was to investigate the association between Apolipoprotein E (ApoE) gene polymorphism in the development of diabetic foot ulcers in Type 2 diabetes Turkish patients. The ApoE genotypes were determined retrospectively in 50 patients with diabetic foot and 50 without diabetic foot and a control group of 50 healthy individuals. The genotype ApoE distribution did differ between the control group (E2E3 44%, E3E3 38%, E3E4 18%) and Type 2 Diabetic Patients (E2E3 6%, E3E3 81%, E3E4 16%) (pDiabetic Patients group (E2E3 4%, E3E3 86%, E3E4 4%) and diabetic foot ulcers (E2E3 8%, E3E3 76%, E3E4 16%) (p>0.05). The frequency of the E2,E3,E4 allele in between the control group and Type 2 Diabetic Patients were no similar for the groups (E2 22%, E3 69%, E4 9% and E2 3%, E3 90.5%, E4 6.5%, respectively) (pDiabetic Patients and diabetic foot ulcers were similar for the groups (E2 2%, E3 93%, E4 5% and E2 4%, E3 88%, E4 8%, respectively) (p>0.05). The gene polymorphism of ApoE and E3 allele are a risk factor for diabetes, but gene polymorphism of ApoE is not an independent risk factor for diabetic foot. Lack of association between ApoE gene polymorphism and Type 2 diabetic foot ulcers might be due to ethnic differences. Copyright © 2015 Diabetes India. Published by Elsevier Ltd. All rights reserved.

  15. Apolipoprotein E (APOE) genotype has dissociable effects on memory and attentional-executive network function in Alzheimer's disease.

    Science.gov (United States)

    Wolk, David A; Dickerson, Bradford C

    2010-06-01

    The epsilon4 allele of the apolipoprotein E (APOE) gene is the major genetic risk factor for Alzheimer's disease (AD), but limited work has suggested that APOE genotype may modulate disease phenotype. Carriers of the epsilon4 allele have been reported to have greater medial temporal lobe (MTL) pathology and poorer memory than noncarriers. Less attention has focused on whether there are domains of cognition and neuroanatomical regions more affected in noncarriers. Further, a major potential confound of prior in vivo studies is the possibility of different rates of clinical misdiagnosis for carriers vs. noncarriers. We compared phenotypic differences in cognition and topography of regional cortical atrophy of epsilon4 carriers (n = 67) vs. noncarriers (n = 24) with mild AD from the Alzheimer's Disease Neuroimaging Initiative, restricted to those with a cerebrospinal fluid (CSF) molecular profile consistent with AD. Between-group comparisons were made for psychometric tests and morphometric measures of cortical thickness and hippocampal volume. Carriers displayed significantly greater impairment on measures of memory retention, whereas noncarriers were more impaired on tests of working memory, executive control, and lexical access. Consistent with this cognitive dissociation, carriers exhibited greater MTL atrophy, whereas noncarriers had greater frontoparietal atrophy. Performance deficits in particular cognitive domains were associated with disproportionate regional brain atrophy within nodes of cortical networks thought to subserve these cognitive processes. These convergent cognitive and neuroanatomic findings in individuals with a CSF molecular profile consistent with AD support the hypothesis that APOE genotype modulates the clinical phenotype of AD through influence on specific large-scale brain networks.

  16. MicroRNA-182 Promotes Lipoprotein Lipase Expression and Atherogenesisby Targeting Histone Deacetylase 9 in Apolipoprotein E-Knockout Mice.

    Science.gov (United States)

    Cheng, Hai-Peng; Gong, Duo; Zhao, Zhen-Wang; He, Ping-Ping; Yu, Xiao-Hua; Ye, Qiong; Huang, Chong; Zhang, Xin; Chen, Ling-Yan; Xie, Wei; Zhang, Min; Li, Liang; Xia, Xiao-Dan; Ouyang, Xin-Ping; Tan, Yu-Lin; Wang, Zong-Bao; Tian, Guo-Ping; Zheng, Xi-Long; Yin, Wei-Dong; Tang, Chao-Ke

    2017-12-25

    Lipoprotein lipase (LPL) expressed in macrophages plays an important role in promoting the development of atherosclerosis or atherogenesis. MicroRNA-182 (miR-182) is involved in the regulation of lipid metabolism and inflammation. However, it remains unclear how miR-182 regulates LPL and atherogenesis.Methods and Results:Using bioinformatics analyses and a dual-luciferase reporter assay, we identified histone deacetylase 9 (HDAC9) as a target gene of miR-182. Moreover, miR-182 upregulated LPL expression by directly targetingHDAC9in THP-1 macrophages. Hematoxylin-eosin (H&E), Oil Red O and Masson's trichrome staining showed that apolipoprotein E (ApoE)-knockout (KO) mice treated with miR-182 exhibited more severe atherosclerotic plaques. Treatment with miR-182 increased CD68 and LPL expression in atherosclerotic lesions in ApoE-KO mice, as indicated by double immunofluorescence staining in the aortic sinus. Increased miR-182-induced increases in LPL expression in ApoE-KO mice was confirmed by real-time quantitative polymerase chain reaction and western blotting analyses. Treatment with miR-182 also increased plasma concentrations of proinflammatory cytokines and lipids in ApoE-KO mice. The results of the present study suggest that miR-182 upregulates LPL expression, promotes lipid accumulation in atherosclerotic lesions, and increases proinflammatory cytokine secretion, likely through targetingHDAC9, leading to an acceleration of atherogenesis in ApoE-KO mice.

  17. MicroRNA-134 Promotes the Development of Atherosclerosis Via the ANGPTL4/LPL Pathway in Apolipoprotein E Knockout Mice.

    Science.gov (United States)

    Ye, Qiong; Tian, Guo-Ping; Cheng, Hai-Peng; Zhang, Xin; Ou, Xiang; Yu, Xiao-Hua; Tan, Ru-Qi; Yang, Feng-Yun; Gong, Duo; Huang, Chong; Pan, Yan-Jun; Zhang, Jie; Chen, Ling-Yan; Zhao, Zhen-Wang; Xie, Wei; Li, Liang; Zhang, Min; Xia, Xiao-Dan; Zheng, Xi-Long; Tang, Chao-Ke

    2018-03-01

    Atherosclerosis is the most common cause of cardiovascular disease, such as myocardial infarction and stroke. Previous study revealed that microRNA (miR)-134 promotes lipid accumulation and proinflammatory cytokine secretion through angiopoietin-like 4 (ANGPTL4)/lipid lipoprotein (LPL) signaling in THP-1 macrophages. ApoE KO male mice on a C57BL/6 background were fed a high-fat/high-cholesterol Western diet, from 8 to 16 weeks of age. Mice were divided into four groups, and received a tail vein injection of miR-134 agomir, miR-134 antagomir, or one of the corresponding controls, respectively, once every 2 weeks after starting the Western diet. After 8 weeks we measured aortic atherosclerosis, LPL Activity, mRNA and protein levels of ANGPTL4 and LPL, LPL/ low-density lipoprotein receptor related protein 1 Complex Formation, proinflammatory cytokine secretion and lipid levels. Despite this finding, the influence of miR-134 on atherosclerosis in vivo remains to be determined. Using the well-characterized mouse atherosclerosis model of apolipoprotein E knockout, we found that systemic delivery of miR-134 agomir markedly enhanced the atherosclerotic lesion size, together with a significant increase in proinflammatory cytokine secretion and peritoneal macrophages lipid contents. Moreover, overexpression of miR-134 decreased ANGPTL4 expression but increased LPL expression and activity in both aortic tissues and peritoneal macrophages, which was accompanied by increased formation of LPL/low-density lipoprotein receptor-related protein 1 complexes in peritoneal macrophages. However, an opposite effect was observed in response to miR-134 antagomir. These findings suggest that miR-134 accelerates atherogenesis by promoting lipid accumulation and proinflammatory cytokine secretion via the ANGPTL4/LPL pathway. Therefore, targeting miR-134 may offer a promising strategy for the prevention and treatment of atherosclerotic cardiovascular disease.

  18. Panax Notoginseng Saponins Promote Endothelial Progenitor Cell Mobilization and Attenuate Atherosclerotic Lesions in Apolipoprotein E Knockout Mice

    Directory of Open Access Journals (Sweden)

    Ya Liu

    2013-09-01

    Full Text Available Background: Endothelial progenitor cells (EPCs derived from the bone marrow (BM play a key role in the homeostasis of vascular repair by enhanced reendothelialization. Panax notoginseng saponins (PNS, a highly valued traditional Chinese medicine, has been shown to reduce morbidity and mortality from coronary artery disease. The present research was designed to explore the contribution of progenitor cells to the progression of atherosclerotic plaques and the possible modulatory role of PNS in this process. Methods: PNS (60 or 120 mg/kg via intraperitoneal injection was administered over 8 weeks in apolipoprotein E knockout mice on an atherogenic diet. The sizes and histochemical alteration of atherosclerotic lesions and numbers of EPCs in BM and peripheral blood were analyzed. The expression of chemokine stromal cell-derived factor 1α (SDF-1α and its receptor, CXCR4, was monitored as well. Results: PNS significantly reduced the lesion area and intima-to-media ratio compared to vehicle treatment. PNS also augmented endothelialization and reduced the smooth muscle cell (SMCs content of the lesions. The number of c-kit and sca-1 double-positive progenitor cells and flk-1 and sca-1 double-positive progenitor cells were significantly increased in the BM and the peripheral blood of the PNS-treated groups. PNS treatment increased the plasma levels of SDF-1α and SCF as well as the BM levels of matrix metalloproteinase-9 (MMP-9. Moreover, the mRNA levels of SDF-1α and protein levels of CXCR4 were both increased in the BM of mice treated with PNS, while SDF-1α expression decreased. Conclusion: PNS reduce the size of atherosclerotic plaques, and this effect appears to involve progenitor cell mobilization. SDF-1α-CXCR4 interactions and the possible modulatory role of PNS in this process may contribute to the increased progenitor cell mobilization.

  19. Apolipoprotein E polymorphisms and severity of cerebral palsy: a cross-sectional study in 255 children in Norway

    Science.gov (United States)

    LIEN, ESPEN; ANDERSEN, GURO L; BAO, YONGDE; GORDISH-DRESSMAN, HEATHER; SKRANES, JON S; VIK, TORSTEIN; BLACKMAN, JAMES A

    2012-01-01

    Aim The aim of this study was to examine whether the presence of the apolipoprotein E (ApoE) allele APOEε4 is associated with less severe manifestations of cerebral palsy (CP), consistent with the suggested beneficial effect of this allele on neurodevelopment in children. Method ApoE genotyping was performed on buccal epithelial cells from 255 children (141 males 114 females; mean age 12y, SD 2y 3mo, range 9–17y) recorded in the Cerebral Palsy Register of Norway. The main outcome measure of CP severity was the Gross Motor Function Classification System (GMFCS). Secondary outcome measures were fine motor function, epilepsy, and the need for gastrostomy tube feeding (GTF). Results There was no association between the APOEε4 genotype and GMFCS levels (odds ratio [OR] 1.15; 95% confidence interval [CI] 0.66–1.99). However, the APOEε4 genotype was more often present among children with epilepsy (OR 2.2; 95% CI 1.1–4.2) and/or receiving GTF (OR 2.7; 95% CI 1.1–6.6). Among children with unilateral CP, the presence of APOEε4 was associated with more severe fine motor impairment (OR 2.6; 95% CI 1.3–6.9). Interpretation Our main hypothesis that APOEε4 would have a protective effect on neurodevelopment was not supported. Instead, subgroup analyses suggested an adverse effect of the APOEε4 genotype on the developing brain after injury. PMID:23384326

  20. Impact of apolipoprotein E ε4 and HIV on cognition and brain atrophy: antagonistic pleiotropy and premature brain aging.

    Science.gov (United States)

    Chang, L; Andres, M; Sadino, J; Jiang, C S; Nakama, H; Miller, E; Ernst, T

    2011-10-15

    The apolipoprotein E (APOE) ε4 allele may accelerate the progression of HIV disease, and increase the risk for developing HIV-associated neurocognitive disorder (HAND). Whether APOEε4 allele(s) and age may influence brain atrophy in HIV patients is unknown and was evaluated. Automated morphometry on magnetic resonance images, using FreeSurfer analyses, neuropsychological testing and APOE genotyping were performed in 139 subjects [70 seronegative controls (SN); 69 clinically-stable HIV subjects]. Compared to SN, HIV subjects had smaller volumes throughout the brain regardless of their HAND status. Compared to APOEε4- subjects, SN controls with APOEε4 had better memory and larger global brain volumes (cerebral white matter and cortex) while HIV subjects with the APOEε4 allele(s) had poorer cognition (verbal fluency, learning, executive function and memory) and smaller cerebral and cerebellar white matter and subcortical structures. Further stratification of age showed that younger (younger APOEε4+HIV subjects had poorer performance on verbal fluency and smaller brain volumes [3-way (HIV-status×APOEε4×Age) interaction-p-values=0.005 to 0.03]. These findings suggest that APOEε4 allele(s) may show antagonistic pleiotropy on cognition and brain atrophy in SN controls, but may lead to premature aging with neurodegeneration in younger HIV patients prior to the development of HAND. Potential mechanisms for such interactions may include stronger neuro-inflammation or greater amyloid deposition in younger HIV subjects with APOEε4 allele(s). Early screening for the APOEε4 allele and brain atrophy with morphometry may guide neuroprotective intervention of cognitively normal HIV subjects prior to the development of HAND. Longitudinal follow-up studies and larger sample sizes are needed to validate these cross-sectional results. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Apolipoprotein E Genotype-Dependent Paradoxical Short-Term Effects of 56Fe Irradiation on the Brain

    International Nuclear Information System (INIS)

    Haley, Gwendolen E.; Villasana, Laura; Dayger, Catherine; Davis, Matthew J.; Raber, Jacob

    2012-01-01

    Purpose: In humans, apolipoprotein E (apoE) is encoded by three major alleles (ε2, ε3, and ε4) and, compared to apoE3, apoE4 increases the risk of developing Alzheimer disease and cognitive impairments following various environmental challenges. Exposure to irradiation, including that of 56 Fe, during space missions poses a significant risk to the central nervous system, and apoE isoform might modulate this risk. Methods and Materials: We investigated whether apoE isoform modulates hippocampus-dependent cognitive performance starting 2 weeks after 56 Fe irradiation. Changes in reactive oxygen species (ROS) can affect cognition and are induced by irradiation. Therefore, after cognitive testing, we assessed hippocampal ROS levels in ex vivo brain slices, using the ROS-sensitive fluorescent probe, dihydroethidium (DHE). Brain levels of 3-nitrotyrosine (3-NT), CuZn superoxide dismutase (CuZnSOD), extracellular SOD, and apoE were assessed using Western blotting analysis. Results: In the water maze, spatial memory retention was impaired by irradiation in apoE2 and apoE4 mice but enhanced by irradiation in apoE3 mice. Irradiation reduced DHE-oxidation levels in the enclosed blade of the dentate gyrus and levels of 3-NT and CuZnSOD in apoE2 but not apoE3 or apoE4 mice. Finally, irradiation increased apoE levels in apoE3 but not apoE2 or apoE4 mice. Conclusions: The short-term effects of 56 Fe irradiation on hippocampal ROS levels and hippocampus-dependent spatial memory retention are apoE isoform-dependent.

  2. The intravenous injection of oxidized LDL- or Apolipoprotein B100 – Coupled splenocytes promotes Th1 polarization in wildtype and Apolipoprotein E – Deficient mice

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    Steinmetz, Martin, E-mail: martin.steinmetz@ukb.uni-bonn.de [INSERM, Unit 970, Paris Cardiovascular Research Center, 75015 Paris (France); Internal Medicine II, University Hospital Bonn, 53105 Bonn (Germany); Ponnuswamy, Padmapriya; Laurans, Ludivine; Esposito, Bruno; Tedgui, Alain [INSERM, Unit 970, Paris Cardiovascular Research Center, 75015 Paris (France); Mallat, Ziad [INSERM, Unit 970, Paris Cardiovascular Research Center, 75015 Paris (France); Division of Cardiovascular Medicine, University of Cambridge, Addenbrooke' s Hospital, Cambridge, CB2 2QQ (United Kingdom)

    2015-08-14

    Background: Th1 responses in atherosclerosis are mainly associated with the aggravation of atherosclerotic plaques, whereas Th2 responses lead to a less pronounced disease in mouse models. The fixation of antigens on cells by means of ethylene carbodiimide (ECDI), and subsequent injection of these antigen-coupled splenocytes (Ag-SP) to induce tolerance against the attached antigens, has been successfully used to treat murine type 1 diabetes or encephalomyelitis in. We analyzed this approach in a mouse model for atherosclerosis. Methods and results: OTII-transgenic mice that were treated with a single dose of 5 × 10{sup 7} OVA-coupled splenocytes (OVA-SP), had decreased splenocyte proliferation, and lower IFNγ production in vitro upon antigen recall. However, in vivo CD4 cell activation was increased. To try lipoprotein-derived, “atherosclerosis-associated” antigens, we first tested human oxidized LDL. In wild type mice, an increase of IFNγ production upon in vitro recall was detected in the oxLDL-SP group. In Apolipoprotein E − deficient (ApoE−/−) mice that received oxLDL-SP every 5 weeks for 20 weeks, we did not find any difference of atherosclerotic plaque burden, but again increased IFNγ production. To overcome xenogenous limitations, we then examined the effects of mouse Apolipoprotein B100 peptides P3 and P6. ApoB100-SP treatment again promoted a more IFNγ pronounced response upon in vitro recall. Flow cytometry analysis of cytokine secreting spleen cells revealed CD4 positive T cells to be mainly the source for IFNγ. In ApoE−/− mice that were administered ApoB100-SP during 20 weeks, the atherosclerotic plaque burden in aortic roots as well as total aorta was unchanged compared to PBS treated controls. Splenocyte proliferation upon antigen recall was not significantly altered in ApoB100-SP treated ApoE−/− mice. Conclusion: Although we did not observe a relevant anti-atherosclerotic benefit, the treatment with antigen

  3. The intravenous injection of oxidized LDL- or Apolipoprotein B100 – Coupled splenocytes promotes Th1 polarization in wildtype and Apolipoprotein E – Deficient mice

    International Nuclear Information System (INIS)

    Steinmetz, Martin; Ponnuswamy, Padmapriya; Laurans, Ludivine; Esposito, Bruno; Tedgui, Alain; Mallat, Ziad

    2015-01-01

    Background: Th1 responses in atherosclerosis are mainly associated with the aggravation of atherosclerotic plaques, whereas Th2 responses lead to a less pronounced disease in mouse models. The fixation of antigens on cells by means of ethylene carbodiimide (ECDI), and subsequent injection of these antigen-coupled splenocytes (Ag-SP) to induce tolerance against the attached antigens, has been successfully used to treat murine type 1 diabetes or encephalomyelitis in. We analyzed this approach in a mouse model for atherosclerosis. Methods and results: OTII-transgenic mice that were treated with a single dose of 5 × 10 7 OVA-coupled splenocytes (OVA-SP), had decreased splenocyte proliferation, and lower IFNγ production in vitro upon antigen recall. However, in vivo CD4 cell activation was increased. To try lipoprotein-derived, “atherosclerosis-associated” antigens, we first tested human oxidized LDL. In wild type mice, an increase of IFNγ production upon in vitro recall was detected in the oxLDL-SP group. In Apolipoprotein E − deficient (ApoE−/−) mice that received oxLDL-SP every 5 weeks for 20 weeks, we did not find any difference of atherosclerotic plaque burden, but again increased IFNγ production. To overcome xenogenous limitations, we then examined the effects of mouse Apolipoprotein B100 peptides P3 and P6. ApoB100-SP treatment again promoted a more IFNγ pronounced response upon in vitro recall. Flow cytometry analysis of cytokine secreting spleen cells revealed CD4 positive T cells to be mainly the source for IFNγ. In ApoE−/− mice that were administered ApoB100-SP during 20 weeks, the atherosclerotic plaque burden in aortic roots as well as total aorta was unchanged compared to PBS treated controls. Splenocyte proliferation upon antigen recall was not significantly altered in ApoB100-SP treated ApoE−/− mice. Conclusion: Although we did not observe a relevant anti-atherosclerotic benefit, the treatment with antigen

  4. Nuclear uptake of an amino-terminal fragment of apolipoprotein E4 promotes cell death and localizes within microglia of the Alzheimer's disease brain.

    Science.gov (United States)

    Love, Julia E; Day, Ryan J; Gause, Justin W; Brown, Raquel J; Pu, Xinzhu; Theis, Dustin I; Caraway, Chad A; Poon, Wayne W; Rahman, Abir A; Morrison, Brad E; Rohn, Troy T

    2017-01-01

    Although harboring the apolipoprotein E4 ( APOE4 ) allele is a well known risk factor in Alzheimer's disease (AD), the mechanism by which it contributes to disease risk remains elusive. To investigate the role of proteolysis of apoE4 as a potential mechanism, we designed and characterized a site-directed cleavage antibody directed at position D151 of the mature form of apoE4 and E3. Characterization of this antibody indicated a high specificity for detecting synthesized recombinant proteins corresponding to the amino acid sequences 1-151 of apoE3 and E4 that would generate the 17 kDa (p17) fragment. In addition, this antibody also detected a ~17 kDa amino-terminal fragment of apoE4 following incubation with collagenase and matrix metalloproteinase-9 (MMP-9), but did not react with full-length apoE4. Application of this amino-terminal apoE cleavage-fragment (nApoECFp17) antibody, revealed nuclear labeling within glial cells and labeling of a subset of neurofibrillary tangles in the human AD brain. A quantitative analysis indicated that roughly 80% of labeled nuclei were microglia. To confirm these findings, cultured BV2 microglia cells were incubated with the amino-terminal fragment of apoE4 corresponding to the cleavage site at D151. The results indicated efficient uptake of this fragment and trafficking to the nucleus that also resulted in significant cell death. In contrast, a similarly designed apoE3 fragment showed no toxicity and primarily localized within the cytoplasm. These data suggest a novel cleavage event by which apoE4 is cleaved by the extracellular proteases, collagenase and MMP-9, generating an amino-terminal fragment that is then taken up by microglia, traffics to the nucleus and promotes cell death. Collectively, these findings provide important mechanistic insights into the mechanism by which harboring the APOE4 allele may elevate dementia risk observed in AD.

  5. Protective activity ethanol extract of the fruits of Illicium verum against atherogenesis in apolipoprotein E knockout mice.

    Science.gov (United States)

    Park, Sun Haeng; Sung, Yoon-Young; Nho, Kyoung Jin; Kim, Ho Kyoung

    2015-07-15

    Illicium verum Hook. fil. Illiciaceae (Illicium v.) has been traditionally used in herbal medicine for treating many inflammatory diseases, including skin inflammation and rheumatism. We investigated its use as a preventive agent against inflammatory and vascular diseases in a murine model of atherosclerosis using apolipoprotein E-knockout (ApoE(-/-)) mice fed on a high-fat diet (HFD). We investigated the effect of Illicium v. on cytotoxicity, NF-κB activity, and adhesion molecule expression in TNF-α--stimulated HASMCs (Human Aortic smooth muscle cells). ApoE(-/-)mice, fed a HFD and treated daily for 12 weeks by oral administration of either Illicium v. (100 or 200 mg/kg) or atorvastatin (10 mg/kg), were evaluated for atherosclerotic lesions and inflammatory responses by performing Oil red O and iNOS staining, respectively. Expression of inflammatory cytokines (i.e., NF-κB, TNF-α, IL-1β, COX, IκB-α, Iκκ-α/β) and adhesion molecules in the aorta were measured by western blot analysis. In TNF-α-stimulated HASMCs, Illicium v. treatment decreased NF-κB transcriptional activity, and NF-κB protein levels were reduced in a dose-dependent manner over a range of 10-100 μg/mL Illicium v. Also, Illicium v. attenuated the expression of adhesion molecules that are responsible for inflammation in these cells. In animal experiments, treatment with Illicium v. or atorvastatin counteracted the characteristic changes in body weight, blood pressure, and lipid levels seen in HFD-fed ApoE(-/-) mice. In addition, Illicium v. treatment reduced aortic atherosclerotic plaque lesions and the immunoreactivity of iNOS activation. The aortic expression of inflammatory adhesion molecules and cytokines (TNF-α, IL-1β, NF-κB, COX, IκB-α, Iκκ-α/β), which is characteristic of HFD-fed ApoE(-/-) mice, was attenuated by 12-week treatment with daily oral administration of Illicium v. or atorvastatin, and the most potent effect was seen with the herbal tincture. The beneficial

  6. N-3 PUFAs protect against aortic inflammation and oxidative stress in angiotensin II-infused apolipoprotein E-/- mice.

    Directory of Open Access Journals (Sweden)

    Kathryn M Wales

    Full Text Available Abdominal aortic aneurysm is associated with infiltration of inflammatory cells into the aortic wall. The inflammatory response is also evident in animal models, such as apolipoprotein E-deficient (ApoE-/- mice that have been infused with angiotensin II, prior to development of aortic aneurysm. Since omega-3 polyunsaturated fatty acids (n-3 PUFAs and their metabolites have anti-inflammatory and pro-resolving activity, we hypothesised that dietary supplementation with n-3 PUFAs would protect against inflammatory processes in this mouse model. Twenty C57 and 20 ApoE-/- 3-4 week old male mice were supplemented with a low (0.14%, n = 10/group or high (0.70%, n = 10/group n-3 PUFA diet for 8 weeks before 2-day infusion with 0.9% saline or angiotensin II (1000 ng/kg/min. Four ApoE-/- mice on the low n-3 PUFA diet and none of the ApoE-/- mice on the high n-3 PUFA diet showed morphological evidence of abdominal aortic dissection. The plasma concentration of the n-3 PUFA metabolite, resolvin D1 was higher in angiotensin II-infused ApoE-/- mice fed the high, compared to the low n-3 PUFA diet. The number of neutrophils and macrophages infiltrating the abdominal aorta was elevated in ApoE-/- mice on the low n-3 PUFA diet, and this was significantly attenuated in mice that were fed the high n-3 PUFA diet. Most neutrophils and macrophages were associated with dissected aortas. Immunoreactivity of the catalytic subunit of nicotinamide-adenine dinucleotide phosphate (NADPH oxidase, Nox2, and superoxide were elevated in ApoE-/- mice that were fed the low n-3 PUFA diet, and this was also significantly attenuated in mice that were fed the high n-3 PUFA diet. Together, the findings indicate that supplementation of ApoE-/- mice with a diet high in n-3 PUFA content protected the mice against pro-inflammatory and oxidative stress responses following short-term infusion with angiotensin II.

  7. Measurement of apolipoprotein E and amyloid β clearance rates in the mouse brain using bolus stable isotope labeling

    Science.gov (United States)

    2012-01-01

    Background Abnormal proteostasis due to alterations in protein turnover has been postulated to play a central role in several neurodegenerative diseases. Therefore, the development of techniques to quantify protein turnover in the brain is critical for understanding the pathogenic mechanisms of these diseases. We have developed a bolus stable isotope-labeling kinetics (SILK) technique coupled with multiple reaction monitoring mass spectrometry to measure the clearance of proteins in the mouse brain. Results Cohorts of mice were pulse labeled with 13 C6-leucine and the brains were isolated after pre-determined time points. The extent of label incorporation was measured over time using mass spectrometry to measure the ratio of labeled to unlabeled apolipoprotein E (apoE) and amyloid β (Aβ). The fractional clearance rate (FCR) was then calculated by analyzing the time course of disappearance for the labeled protein species. To validate the technique, apoE clearance was measured in mice that overexpress the low-density lipoprotein receptor (LDLR). The FCR in these mice was 2.7-fold faster than wild-type mice. To demonstrate the potential of this technique for understanding the pathogenesis of neurodegenerative disease, we applied our SILK technique to determine the effect of ATP binding cassette A1 (ABCA1) on both apoE and Aβ clearance. ABCA1 had previously been shown to regulate both the amount of apoE in the brain, along with the extent of Aβ deposition, and represents a potential molecular target for lowering brain amyloid levels in Alzheimer's disease patients. The FCR of apoE was increased by 1.9- and 1.5-fold in mice that either lacked or overexpressed ABCA1, respectively. However, ABCA1 had no effect on the FCR of Aβ, suggesting that ABCA1 does not regulate Aβ metabolism in the brain. Conclusions Our SILK strategy represents a straightforward, cost-effective, and efficient method to measure the clearance of proteins in the mouse brain. We expect that

  8. Apolipoprotein E4 (1–272 fragment is associated with mitochondrial proteins and affects mitochondrial function in neuronal cells

    Directory of Open Access Journals (Sweden)

    Michikawa Makoto

    2009-08-01

    Full Text Available Abstract Background Apolipoprotein E allele ε4 (apoE4 is a strong risk factor for developing Alzheimer's disease (AD. Secreted apoE has a critical function in redistributing lipids among central nervous system cells to maintain normal lipid homeostasis. In addition, previous reports have shown that apoE4 is cleaved by a protease in neurons to generate apoE4(1–272 fragment, which is associated with neurofibrillary tanglelike structures and mitochondria, causing mitochondrial dysfunction. However, it still remains unclear how the apoE fragment associates with mitochondria and induces mitochondrial dysfunction. Results To clarify the molecular mechanism, we carried out experiments to identify intracellular apoE-binding molecules and their functions in modulating mitochondria function. Here, we found that apoE4 binds to ubiquinol cytochrome c reductase core protein 2 (UQCRC2 and cytochrome C1, both of which are components of mitochondrial respiratory complex III, and cytochrome c oxidase subunit 4 isoform 1 (COX IV 1, which is a component of complex IV, in Neuro-2a cells. Interestingly, these proteins associated with apoE4(1–272 more strongly than intact apoE4(1–299. Further analysis showed that in Neuro-2a cells expressing apoE4(1–272, the enzymatic activities of mitochondrial respiratory complexes III and IV were significantly lower than those in Neuro-2a cells expressing apoE4(1–299. Conclusion ApoE4(1–272 fragment expressed in Neuro2a cells is associated with mitochondrial proteins, UQCRC2 and cytochrome C1, which are component of respiratory complex III, and with COX IV 1, which is a member of complex IV. Overexpression of apoE4(1–272 fragment impairs activities of complex III and IV. These results suggest that the C-terminal-truncated fragment of apoE4 binds to mitochondrial complexes and affects their activities, and thereby leading to neurodegeneration.

  9. Association between amylin and amyloid-β peptides in plasma in the context of apolipoprotein E4 allele.

    Directory of Open Access Journals (Sweden)

    Wei Qiao Qiu

    Full Text Available Amylin, a pancreatic peptide that readily crosses the blood brain barrier (BBB, and amyloid-beta peptide (Aβ, the main component of amyloid plaques and a major component of Alzheimer's disease (AD pathology in the brain, share several features. These include having similar β-sheet secondary structures, binding to the same receptor, and being degraded by the same protease. Thus, amylin may be associated with Aβ, but the nature of their relationship remains unclear. In this study, we used human samples to study the relationship between plasma amylin and Aβ in the context of the apolipoprotein E alleles (ApoE. We found that concentrations of Aβ1-42 (P<0.0001 and Aβ1-40 (P<0.0001 increased with each quartile increase of amylin. Using multivariate regression analysis, the study sample showed that plasma amylin was associated with Aβ1-42 (β = +0.149, SE = 0.025, P<0.0001 and Aβ1-40 (β = +0.034, SE = 0.016, P = 0.04 as an outcome after adjusting for age, gender, ethnicity, ApoE4, BMI, diabetes, stroke, kidney function and lipid profile. This positive association between amylin and Aβ1-42 in plasma was found regardless of the ApoE genotype. In contrast, the relationship between amylin and Aβ1-40 in plasma seen in ApoE4 non-carriers disappeared in the presence of ApoE4. Using AD mouse models, our recent study demonstrates that intraperitoneal (i.p. injection of synthetic amylin enhances the removal of Aβ from the brain into blood, thus resulting in increased blood levels of both amylin and Aβ. The positive association between amylin and Aβ, especially Aβ1-42, in human blood samples is probably relevant to the findings in the AD mouse models. The presence of ApoE4 may attenuate amylin's capacity to remove Aβ, especially Aβ1-40, from the AD brain.

  10. Acrolein Modification Impairs Key Functional Features of Rat Apolipoprotein E: Identification of Modified Sites by Mass Spectrometry

    Science.gov (United States)

    Tran, Tuyen N.; Kosaraju, Malathi G.; Tamamizu-Kato, Shiori; Akintunde, Olayemi; Zheng, Ying; Bielicki, John K.; Pinkerton, Kent; Uchida, Koji; Lee, Yuan Yu; Narayanaswami, Vasanthy

    2014-01-01

    Apolipoprotein E (apoE), an anti-atherogenic apolipoprotein, plays a significant role in the metabolism of lipoproteins. It lowers plasma lipid levels by acting as a ligand for low-density lipoprotein receptor (LDLr) family of proteins, in addition to playing a role in promoting macrophage cholesterol efflux in atherosclerotic lesions. The objective of this study is to examine the effect of acrolein modification on the structure and function of rat apoE and to determine sites and nature of modification by mass spectrometry. Acrolein is a highly reactive aldehyde, which is generated endogenously as one of the products of lipid peroxidation and is present in the environment in pollutants such as tobacco smoke and heated oils. In initial studies, acrolein-modified apoE was identified by immunoprecipitation using an acrolein-lysine specific antibody, in the plasma of ten-week old male rats that were exposed to filtered air (FA) or low doses of environmental tobacco smoke (ETS). While both groups displayed acrolein-modified apoE in the lipoprotein fraction, the ETS group had higher levels in lipid-free fraction compared to the FA group. This observation provided the rationale to further investigate the effect of acrolein modification on rat apoE at a molecular level. Treatment of recombinant rat apoE with a 10-fold molar excess of acrolein resulted in: (i) a significant decrease in lipid-binding and cholesterol efflux abilities, (ii) impairment in the LDLr- and heparin-binding capabilities, and (iii) significant alterations in the overall stability of the protein. The disruption in the functional abilities is attributed directly or indirectly to acrolein modification yielding: an aldimine adduct at K149 and K155 (+38); a propanal adduct at K135 and K138 (+56); an Nε-(3-methylpyridinium)lysine (MP-lysine) at K64, K67 and K254 (+76), and Nε-(3-formyl-3,4-dehydropiperidino)lysine (FDP-lysine) derivative at position K68 (+94), as determined by Matrix-Assisted Laser

  11. Polychlorinated biphenyl 77 augments angiotensin II-induced atherosclerosis and abdominal aortic aneurysms in male apolipoprotein E deficient mice

    Energy Technology Data Exchange (ETDEWEB)

    Arsenescu, Violeta [Graduate Center for Nutritional Sciences, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0200 (United States); Arsenescu, Razvan [Digestive Diseases and Nutrition, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0200 (United States); Parulkar, Madhura; Karounos, Michael [Graduate Center for Nutritional Sciences, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0200 (United States); Zhang, Xuan [Graduate Center for Toxicology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0200 (United States); Baker, Nicki [Graduate Center for Nutritional Sciences, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0200 (United States); Cassis, Lisa A., E-mail: lcassis@uky.edu [Graduate Center for Nutritional Sciences, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0200 (United States)

    2011-11-15

    Infusion of angiotensin II (AngII) to hyperlipidemic mice augments atherosclerosis and causes formation of abdominal aortic aneurysms (AAAs). Each of these AngII-induced vascular pathologies exhibit pronounced inflammation. Previous studies demonstrated that coplanar polychlorinated biphenyls (PCBs) promote inflammation in endothelial cells and adipocytes, two cell types implicated in AngII-induced vascular pathologies. The purpose of this study was to test the hypothesis that administration of PCB77 to male apolipoprotein E (ApoE) -/- mice promotes AngII-induced atherosclerosis and AAA formation. Male ApoE-/- mice were administered vehicle or PCB77 (49 mg/kg, i.p.) during week 1 and 4 (2 divided doses/week) of AngII infusion. Body weights and total serum cholesterol concentrations were not influenced by administration of PCB77. Systolic blood pressure was increased in AngII-infused mice administered PCB77 compared to vehicle (156 {+-} 6 vs 137 {+-} 5 mmHg, respectively). The percentage of aortic arch covered by atherosclerotic lesions was increased in AngII-infused mice administered PCB77 compared to vehicle (2.0 {+-} 0.4 vs 0.9 {+-} 0.1%, respectively). Lumen diameters of abdominal aortas determined by in vivo ultrasound and external diameters of excised suprarenal aortas were increased in AngII-infused mice administered PCB77 compared to vehicle. In addition, AAA incidence increased from 47 to 85% in AngII-infused mice administered PCB77. Adipose tissue in close proximity to AAAs from mice administered PCB77 exhibited increased mRNA abundance of proinflammatory cytokines and elevated expression of components of the renin-angiotensin system (angiotensinogen, angiotensin type 1a receptor (AT1aR)). These results demonstrate that PCB77 augments AngII-induced atherosclerosis and AAA formation. -- Highlights: Black-Right-Pointing-Pointer Polychlorinated biphenyl 77 (PCB77) promotes AngII-induced hypertension. Black-Right-Pointing-Pointer PCB77 augments Ang

  12. Apolipoprotein E-knockout mice show increased titers of serum anti-nuclear and anti-dsDNA antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuehai [Cardiovascular Department, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Huang, Ziyang, E-mail: huangziyang666@126.com [Cardiovascular Department, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Lu, Huixia [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University, Qilu Hospital, Jinan, Shandong 250012 (China); Lin, Huili; Wang, Zhenhua [Cardiovascular Department, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Chen, Xiaoqing [Department of Rheumatism and Immunology, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Ouyang, Qiufang [Cardiovascular Department, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Tang, Mengxiong; Hao, Panpan [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University, Qilu Hospital, Jinan, Shandong 250012 (China); Ni, Jingqin [Cardiovascular Department, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Xu, Dongming [Department of Rheumatism and Immunology, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); Zhang, Mingxiang; Zhang, Qunye [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University, Qilu Hospital, Jinan, Shandong 250012 (China); Lin, Ling [Department of Rheumatism and Immunology, Second Clinical Medical College, Fujian Medical University, Quanzhou, Fujian 362000 (China); and others

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer Titers of ANA and anti-dsDNA antibodies were higher in ApoE{sup -/-} than C57B6/L mice. Black-Right-Pointing-Pointer Spleen was greater and splenocyte apoptosis lower in ApoE{sup -/-} than B6 mice. Black-Right-Pointing-Pointer Level of TLR4 was lower in spleen tissue of ApoE{sup -/-} than B6 mice. Black-Right-Pointing-Pointer The TLR4 pathway may participate in maintaining the balance of splenocyte apoptosis. Black-Right-Pointing-Pointer The TLR4 pathway may participate in antibody production in spleen tissue. -- Abstract: Apolipoprotein E-knockout (ApoE{sup -/-}) mice, atherosclerosis-prone mice, show an autoimmune response, but the pathogenesis is not fully understood. We investigated the pathogenesis in female and male ApoE{sup -/-} mice. The spleens of all ApoE{sup -/-} and C57BL/6 (B6) mice were weighed. The serum IgG level and titers of anti-nuclear antibody (ANA) and anti-double-stranded DNA (anti-dsDNA) antibody were assayed by ELISA. Apoptosis of spleen tissue was evaluated by TUNEL. TLR4 level in spleen tissue was tested by immunohistochemistry and Western blot analysis. Levels of MyD88, p38, phosphorylated p38 (pp38), interferon regulatory factor 3 (IRF3) and Bcl-2-associated X protein (Bax) in spleen tissue were detected by Western blot analysis. We also survey the changes of serum autoantibodies, spleen weight, splenocyte apoptosis and the expressions of TLR4, MyD88, pp38, IRF3 and Bax in spleen tissue in male ApoE{sup -/-} mice after 4 weeks of lipopolysaccharide (LPS), Toll-like receptor 4 ligand, administration. ApoE{sup -/-} mice showed splenomegaly and significantly increased serum level of IgG and titers of ANA and anti-dsDNA antibody as compared with B6 mice. Splenocyte apoptosis and the expression of TLR4, MyD88, pp38, IRF3 and Bax in spleen tissue were significantly lower in ApoE{sup -/-} than B6 mice. The expression of TLR4, MyD88, IRF3, pp38, and Bax differed by sex in ApoE{sup -/-} spleen tissue. The

  13. Development of new quantitative mass spectrometry and semi-automatic isofocusing methods for the determination of Apolipoprotein E typing.

    Science.gov (United States)

    Hirtz, Christophe; Vialaret, Jerome; Nouadje, Georges; Schraen, Susanna; Benlian, Pascale; Mary, Sandrine; Philibert, Pascal; Tiers, Laurent; Bros, Pauline; Delaby, Constance; Gabelle, Audrey; Lehmann, Sylvain

    2016-02-15

    Apolipoprotein E (Apo E) is a 36 Kda glycoprotein involved in lipid transport. It exists in 3 major isoforms: E2, E3 and E4. ApoE status is known to be a major risk factor for late-onset Alzheimer's and cardiovascular diseases. Genotyping is commonly used to obtain ApoE status but can show technical issues with ambiguous determinations. Phenotyping can be an alternative, not requiring genetic material. We evaluated the ability to accurately type ApoE isoforms by 2 phenotyping tests in comparison with genotyping. Two phenotyping techniques were used: (1) LC-MS/MS detection of 4 ApoE specific peptides (6490 Agilent triple quadripole): After its denaturation, serum was either reduced and alkylated, or only diluted, and then trypsin digested. Before analysis, desalting, evaporation and resuspension were performed. (2) Isoelectric focusing and immunoprecipitation: serum samples were neuraminidase digested, delipidated and electrophoresed on Hydragel ApoE (Sebia agarose gel) using Hydrasys 2 Scan instrument (Sebia, Lisses, France). ApoE isoforms bands were directly immunofixed in the gel using a polyclonal anti human ApoE antibody. Then, incubation of the gel with HRP secondary antibody followed by TTF1/TTF2 substrate allowed the visualization of ApoE bands. The results of the two techniques were compared to genotyping. Sera from 35 patients previously genotyped were analyzed with the 2 phenotyping techniques. 100% concordance between both phenotyping assays was obtained for the tested phenotypes (E2/E2, E2/E3, E2/E4, E3/E3, E3/E4, E4/E4). When compared to genotyping, 3 samples were discordant. After reanalyzing them by both phenotyping tests and DNA sequencing, 2/3 discrepancies were confirmed. Those can be explained by variants or rare ApoE alleles or by unidentified technical issues. 102 additional samples were then tested on LC-MS/MS only and compared to genotyping. The data showed 100% concordance. Our 2 phenotyping methods represent a valuable alternative to

  14. A disulfide-linked amyloid-beta peptide dimer forms a protofibril-like oligomer through a distinct pathway from amyloid fibril formation.

    Science.gov (United States)

    Yamaguchi, Takahiro; Yagi, Hisashi; Goto, Yuji; Matsuzaki, Katsumi; Hoshino, Masaru

    2010-08-24

    The conversion of the soluble, nontoxic amyloid-beta (Abeta) peptide into an aggregated, toxic form rich in beta-sheets is considered a key step in the development of Alzheimer's disease. Whereas growing evidence indicates that the Abeta amyloid fibrils consist of in-register parallel beta-sheets, little is known about the structure of soluble oligomeric intermediates because of their transient nature. To understand the mechanism by which amyloid fibrils form, especially the initial development of the "nucleus" oligomeric intermediates, we prepared covalently linked dimeric Abeta peptides and analyzed the kinetics of the fibril-forming process. A covalent bond introduced between two Abeta molecules dramatically facilitated the spontaneous formation of aggregates with a beta-sheet structure and affinity for thioflavin T. Transmission electron microscopy revealed, however, that these aggregates differed in morphology from amyloid fibrils, more closely resembling protofibrils. The protofibril-like aggregates were not the most thermodynamically stable state but were a kinetically trapped state. The results emphasize the importance of the conformational flexibility of the Abeta molecule and a balance in the association and dissociation rate for the formation of rigid amyloid fibrils.

  15. Cannabidiol-2',6'-dimethyl ether stimulates body weight gain in apolipoprotein E-deficient BALB/c. KOR/Stm Slc-Apoe(shl) mice.

    Science.gov (United States)

    Takeda, Shuso; Hirota, Rena; Teradaira, Sari; Takeda-Imoto, Masumi; Watanabe, Kazuhito; Toda, Akihisa; Aramaki, Hironori

    2015-12-01

    The biological activities of cannabidiol (CBD), a major non-psychotropic constituent of the fiber-type cannabis plant, have been examined in detail (e.g., CBD modulation of body weight in mice and rats). However, few studies have investigated the biological activities of cannabidiol-2',6'-dimethyl ether (CBDD), a dimethyl ether derivative of the parent CBD. We herein focused on the effects of CBDD on body weight changes in mice, and demonstrated that it stimulated body weight gain in apolipoprotein E (ApoE)-deficient BALB/c. KOR/Stm Slc-Apoe(shl) mice, especially between 10 and 20 weeks of age.

  16. Effect of 12-O-tetradecanoylphorbol-13-acetate-induced psoriasis-like skin lesions on systemic inflammation and atherosclerosis in hypercholesterolaemic apolipoprotein E deficient mice

    DEFF Research Database (Denmark)

    Madsen, Marie; Hansen, Peter Riis; Nielsen, Lars Bo

    2016-01-01

    BACKGROUND: Risk of cardiovascular disease is increased in patients with psoriasis, but molecular mechanisms linking the two conditions have not been clearly established. Lack of appropriate animal models has hampered generation of new knowledge in this area of research and we therefore sought...... to develop an animal model with combined atherosclerosis and psoriasis-like skin inflammation. METHODS: Topical 12-O-tetradecanoylphorbol-13-acetate (TPA) was applied to the ears twice per week for 8 weeks in atherosclerosis-prone apolipoprotein E deficient (ApoE(-/-)) mice. RESULTS: TPA led to localized...

  17. Influence of apolipoprotein-E gene on lipid profile, physical activity and body fat relationship. DOI:10.5007/1980-0037.2012v14n2p221

    Directory of Open Access Journals (Sweden)

    Thales Boaventura Rachid Nascimento

    2012-02-01

    Full Text Available Physical activity and body fat modify lipemia, and this effect seems to be influenced by apolipoprotein-E (APOE gene polymorphism. Thus, the purpose of this article was to review main results of studies that have analyzed the relation of APOE gene with physical activity and body fat on triglycerides, total cholesterol and low (LDL and high density lipoprotein (HDL concentrations. The Scientific Electronic Library Online – SciELO, Web of Science and PubMed database were used to locate the articles. The keywords used in combination were: apoe genotype, apolipoprotein-E polymorphism, physical exercise, physical activity, aerobic exercise, body fat and obesity. Originals scientific investigations performed with humans were included, and excluded those ones which involved samples with diseases, except obesity and/or lipemic disorders. It was observed a trend, that ε2 allele carriers are the ones with the greater improvements on lipemia from physical exercise. In addition, the body fat impact on the elevation of triglycerides and LDL are stronger in carriers of the ε2 and ε4 allele, respectively. Considering the small number of originals scientific investigations and their divergent results, reliable inferences can not be made about the APOE gene polymorphism influences on physical activity and body fat effect on lipemia. Thus, further studies with others populations and more volunteers for allele, as well as others exercise modalities and intensities, are necessary.

  18. Crystallization and preliminary x-ray crystallography data of the dimer of tetramer s (abcd)2 of extracellular hemoglobin from Glossoscolex paulistus in cyano met form

    International Nuclear Information System (INIS)

    Ferreira, Frederico M.; Oliveira, Paulo S.L. de; Oliva, Glaucius

    1996-01-01

    Full text. The extracellular hemoglobin from Glossoscolex paulistus has a molecular weight near to 3.1 x 10 6 Da and a structure organized in a double-layered hexagonal oligomer. The tertiary complex of dimer of tetramers (abcd) 2 was obtained by chromography in Sephadex G-200, in pH 9.0, as a result of alkaline dissociation. Aiming to obtain a better understanding of the oligomeric structure and specially for the inter subunit interactions the extracellular hemoglobins, we have obtained crystals of dimer of tetramers (abcd) 2 of hemoglobin from Glossoscolex and we are studying the in behavior in different conditions of precipitants and pH's. Our goal is to solve the crystal structure in order to characterize, at atomic level, the subunits contacts, heme environment and differences in residues involved in oxygenation in order to understand in this hemoglobin. The crystallization experiments the protein concentration in the cyanomet form was about 10 mg/ml and the experiments were carried out at 18 0 C. The optimal crystallization condition achieved from factorial assays was 10% (w/v). Polyethylene glycol (PEG) 8,000 and 8%(v/v) ethylene glycol in 100 mM HEPES pH 7.5. The optimization of this condition was carried out with the variation of PEG concentrations from 6% up to 10% (by 1% step) and pH between 7.0 and 8.0. A quite critical p-H-dependence has been observed on crystal nucleation, decreasing from pH 7.0, in which the number of microcrystals in higher, up to pH 8.0, in which crystals did not appear even at higher PEG 8,000 (10% w/v). As several structures of hemoglobin from different sources (vertebrate and invertebrates) are available, we hope to solve their structure of hemoglobin from Glossoscolex paulistus by Molecular Replacement, even though the tetramer organization may be different in the earthworm as compared related to other known tetrameric hemoglobin structures. (author)

  19. Structural Basis for Enhanced HIV-1 Neutralization by a Dimeric Immunoglobulin G Form of the Glycan-Recognizing Antibody 2G12

    Directory of Open Access Journals (Sweden)

    Yunji Wu

    2013-12-01

    Full Text Available The human immunoglobulin G (IgG 2G12 recognizes high-mannose carbohydrates on the HIV type 1 (HIV-1 envelope glycoprotein gp120. Its two antigen-binding fragments (Fabs are intramolecularly domain exchanged, resulting in a rigid (Fab2 unit including a third antigen-binding interface not found in antibodies with flexible Fab arms. We determined crystal structures of dimeric 2G12 IgG created by intermolecular domain exchange, which exhibits increased breadth and >50-fold increased neutralization potency compared with monomeric 2G12. The four Fab and two fragment crystalline (Fc regions of dimeric 2G12 were localized at low resolution in two independent structures, revealing IgG dimers with two (Fab2 arms analogous to the Fabs of conventional monomeric IgGs. Structures revealed three conformationally distinct dimers, demonstrating flexibility of the (Fab2-Fc connections that was confirmed by electron microscopy, small-angle X-ray scattering, and binding studies. We conclude that intermolecular domain exchange, flexibility, and bivalent binding to allow avidity effects are responsible for the increased potency and breadth of dimeric 2G12.

  20. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: A combined experimental and theoretical study

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-01

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm-1 and 4000-50 cm-1, respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion-1 and anion-2 conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1sbnd C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed.

  1. Apolipoprotein E genotype, cardiovascular biomarkers and risk of stroke : Systematic review and meta-analysis of 14 015 stroke cases and pooled analysis of primary biomarker data from up to 60 883 individuals

    NARCIS (Netherlands)

    Khan, Tauseef A.; Shah, Tina; Prieto, David; Zhang, Weili; Price, Jackie; Fowkes, Gerald R.; Cooper, Jackie; Talmud, Philippa J.; Humphries, Steve E.; Sundstrom, Johan; Hubacek, Jaroslav A.; Ebrahim, Shah; Lawlor, Debbie A.; Ben-Shlomo, Yoav; Abdollahi, Mohammad R.; Slooter, Arjen J. C.; Szolnoki, Zoltan; Sandhu, Manjinder; Wareham, Nicholas; Frikke-Schmidt, Ruth; Tybjaerg-Hansen, Anne; Fillenbaum, Gerda; Heijmans, Bastiaan T.; Katsuya, Tomohiro; Gromadzka, Grazyna; Singleton, Andrew; Ferrucci, Luigi; Hardy, John; Worrall, Bradford; Rich, Stephen S.; Matarin, Mar; Whittaker, John; Gaunt, Tom R.; Whincup, Peter; Morris, Richard; Deanfield, John; Donald, Ann; Smith, George Davey; Kivimaki, Mika; Kumari, Meena; Smeeth, Liam; Khaw, Kay-Tee; Nalls, Michael; Meschia, James; Sun, Kai; Hui, Rutai; Day, Ian; Hingorani, Aroon D.; Casas, Juan P.

    Background At the APOE gene, encoding apolipoprotein E, genotypes of the epsilon 2/epsilon 3/epsilon 4 alleles associated with higher LDL-cholesterol (LDL-C) levels are also associated with higher coronary risk. However, the association of APOE genotype with other cardiovascular biomarkers and risk

  2. Dynamic interplay between adhesive and lateral E-cadherin dimers

    DEFF Research Database (Denmark)

    Klingelhöfer, Jörg; Laur, Oscar Y; Troyanovsky, Regina B

    2002-01-01

    E-cadherin, an adhesive transmembrane protein of epithelial adherens junctions, forms two types of detergent-resistant dimers: adhesive dimers consisting of cadherin molecules derived from two neighboring cells and lateral dimers incorporating cadherins of the same cell. Both dimers depend...... on the integrity of the same residue, Trp156. While the relative amounts of these complexes are not certain, we show here that in epithelial A-431 cells, adhesive dimers may be a prevalent form. Inactivation of the calcium-binding sites, located between successive cadherin ectodomains, drastically reduced...... the amount of adhesive dimers and concomitantly increased the amount of lateral dimers. A similar interdependence of adhesive and lateral dimers was observed in digitonin-permeabilized cells. In these cells, adhesive dimers immediately disassembled after lowering the Ca2+ concentration below 0.1 m...

  3. RecFOR Is Not Required for Pneumococcal Transformation but Together with XerS for Resolution of Chromosome Dimers Frequently Formed in the Process

    Science.gov (United States)

    Johnston, Calum; Mortier-Barrière, Isabelle; Granadel, Chantal; Polard, Patrice; Martin, Bernard; Claverys, Jean-Pierre

    2015-01-01

    Homologous recombination (HR) is required for both genome maintenance and generation of diversity in eukaryotes and prokaryotes. This process initiates from single-stranded (ss) DNA and is driven by a universal recombinase, which promotes strand exchange between homologous sequences. The bacterial recombinase, RecA, is loaded onto ssDNA by recombinase loaders, RecBCD and RecFOR for genome maintenance. DprA was recently proposed as a third loader dedicated to genetic transformation. Here we assessed the role of RecFOR in transformation of the human pathogen Streptococcus pneumoniae. We firstly established that RecFOR proteins are not required for plasmid transformation, strongly suggesting that DprA ensures annealing of plasmid single-strands internalized in the process. We then observed no reduction in chromosomal transformation using a PCR fragment as donor, contrasting with the 10,000-fold drop in dprA - cells and demonstrating that RecFOR play no role in transformation. However, a ∼1.45-fold drop in transformation was observed with total chromosomal DNA in recFOR mutants. To account for this limited deficit, we hypothesized that transformation with chromosomal DNA stimulated unexpectedly high frequency (>30% of cells) formation of chromosome dimers as an intermediate in the generation of tandem duplications, and that RecFOR were crucial for dimer resolution. We validated this hypothesis, showing that the site-specific recombinase XerS was also crucial for dimer resolution. An even higher frequency of dimer formation (>80% of cells) was promoted by interspecies transformation with Streptococcus mitis chromosomal DNA, which contains numerous inversions compared to pneumococcal chromosome, each potentially promoting dimerization. In the absence of RecFOR and XerS, dimers persist, as confirmed by DAPI staining, and can limit the efficiency of transformation, since resulting in loss of transformant chromosome. These findings strengthen the view that different HR

  4. RecFOR is not required for pneumococcal transformation but together with XerS for resolution of chromosome dimers frequently formed in the process.

    Directory of Open Access Journals (Sweden)

    Calum Johnston

    2015-01-01

    Full Text Available Homologous recombination (HR is required for both genome maintenance and generation of diversity in eukaryotes and prokaryotes. This process initiates from single-stranded (ss DNA and is driven by a universal recombinase, which promotes strand exchange between homologous sequences. The bacterial recombinase, RecA, is loaded onto ssDNA by recombinase loaders, RecBCD and RecFOR for genome maintenance. DprA was recently proposed as a third loader dedicated to genetic transformation. Here we assessed the role of RecFOR in transformation of the human pathogen Streptococcus pneumoniae. We firstly established that RecFOR proteins are not required for plasmid transformation, strongly suggesting that DprA ensures annealing of plasmid single-strands internalized in the process. We then observed no reduction in chromosomal transformation using a PCR fragment as donor, contrasting with the 10,000-fold drop in dprA- cells and demonstrating that RecFOR play no role in transformation. However, a ∼1.45-fold drop in transformation was observed with total chromosomal DNA in recFOR mutants. To account for this limited deficit, we hypothesized that transformation with chromosomal DNA stimulated unexpectedly high frequency (>30% of cells formation of chromosome dimers as an intermediate in the generation of tandem duplications, and that RecFOR were crucial for dimer resolution. We validated this hypothesis, showing that the site-specific recombinase XerS was also crucial for dimer resolution. An even higher frequency of dimer formation (>80% of cells was promoted by interspecies transformation with Streptococcus mitis chromosomal DNA, which contains numerous inversions compared to pneumococcal chromosome, each potentially promoting dimerization. In the absence of RecFOR and XerS, dimers persist, as confirmed by DAPI staining, and can limit the efficiency of transformation, since resulting in loss of transformant chromosome. These findings strengthen the view that

  5. A substrate specificity-determining unit of three Lin12-Notch repeat modules is formed in trans within the pappalysin-1 dimer and requires a sequence stretch C-terminal to the third module

    DEFF Research Database (Denmark)

    Weyer, Kathrin; Boldt, Henning Bünsow; Poulsen, Christine Bruun

    2007-01-01

    of such a functional LNR unit depends on dimerization, as dissociation of a mutated non-covalent PAPP-A dimer results in reduced activity against IGFBP-4, but not IGFBP-5. Using PAPP-A/PAPP-A2 chimeras, we demonstrate that PAPP-A2 LNR1-2, but not LNR3, are functionally conserved with respect to IGFBP proteolysis...... activity against IGFBP-4, cleaves IGFBP-4 when co-expressed with a PAPP-A variant, which is mutated in the active site. This suggests that LNR3 from the inactive subunit interacts in trans with LNR1-2 of the truncated PAPP-A subunit to form a functional trimeric LNR unit. We also show that formation...

  6. CAT‐2003: A novel sterol regulatory element‐binding protein inhibitor that reduces steatohepatitis, plasma lipids, and atherosclerosis in apolipoprotein E*3‐Leiden mice

    Science.gov (United States)

    Bista, Pradeep; Benson, Ericka L.; Lee, Diana Y.; Liu, Feng; Picarella, Dominic; Vega, Rick B.; Vu, Chi B.; Yeager, Maisy; Ding, Min; Liang, Guosheng; Horton, Jay D.; Kleemann, Robert; Kooistra, Teake; Morrison, Martine C.; Wielinga, Peter Y.; Milne, Jill C.; Jirousek, Michael R.; Nichols, Andrew J.

    2017-01-01

    CAT‐2003 is a novel conjugate of eicosapentaenoic acid (EPA) and niacin designed to be hydrolyzed by fatty acid amide hydrolase to release EPA inside cells at the endoplasmic reticulum. In cultured liver cells, CAT‐2003 blocked the maturation of sterol regulatory element‐binding protein (SREBP)‐1 and SREBP‐2 proteins and decreased the expression of multiple SREBP target genes, including HMGCR and PCSK9. Consistent with proprotein convertase subtilisin/kexin type 9 (PCSK9) reduction, both low‐density lipoprotein receptor protein at the cell surface and low‐density lipoprotein particle uptake were increased. In apolipoprotein E*3‐Leiden mice fed a cholesterol‐containing western diet, CAT‐2003 decreased hepatic inflammation and steatosis as evidenced by fewer inflammatory cell aggregates in histopathologic sections, decreased nuclear factor kappa B activity in liver lysates, reduced inflammatory gene expression, reduced intrahepatic cholesteryl ester and triglyceride levels, and decreased liver mass. Plasma PCSK9 was reduced and hepatic low‐density lipoprotein receptor protein expression was increased; plasma cholesterol and triglyceride levels were lowered. Aortic root segments showed reduction of several atherosclerotic markers, including lesion size, number, and severity. CAT‐2003, when dosed in combination with atorvastatin, further lowered plasma cholesterol levels and decreased hepatic expression of SREBP target genes. Conclusion: SREBP inhibition is a promising new strategy for the prevention and treatment of diseases associated with abnormal lipid metabolism, such as atherosclerosis and nonalcoholic steatohepatitis. (Hepatology Communications 2017;1:311–325) PMID:29404461

  7. Exploring the effects of the atherosclerosis progression and the choice of affected arteries in the design of experiments with Apolipoprotein E-deficient mice.

    Science.gov (United States)

    Riera-Borrull, Marta; Sabench, Fàtima; del Castillo, Daniel; Camps, Jordi; Joven, Jorge

    2016-01-01

    The objective of this study is to explore the longitudinal progression of atherosclerosis and the correlation between methods to measure the lesion in apolipoprotein E-deficient mice. Atherosclerosis progression was assessed by measurements of foam cell-rich depositions in their proximal aortas, and/or in surgically excised arteries, to assess the histological luminal narrowing. A longitudinal study was performed by comparing the values for carotid, aorta, and femoral and iliac arteries using common histological techniques. There were no significant differences in progression between different arteries, but correlation with the classical measurement of atherosclerosis in the aortic root was poor. Each laboratory requires specific standardization. Carotid arteries were sensitive to atherosclerosis in these mice, and progression was exponential. In conclusion, morphometric data show the importance of the choice of the duration of treatment, the appropriate controls, and the age at which to begin the experiments. Copyright © 2015 Sociedad Española de Arteriosclerosis. Published by Elsevier España. All rights reserved.

  8. Analysis of the Relationship between Estradiol and Follicle-Stimulating Hormone Concentrations and Polymorphisms of Apolipoprotein E and LeptinGenes in Women Post-Menopause.

    Science.gov (United States)

    Rył, Aleksandra; Jasiewicz, Andrzej; Grzywacz, Anna; Adler, Grażyna; Skonieczna-Żydecka, Karolina; Rotter, Iwona; Sipak-Szmigiel, Olimpia; Rumianowski, Bogdan; Karakiewicz, Beata; Jurczak, Anna; Parczewski, Miłosz; Urbańska, Anna; Grabowska, Marta; Laszczyńska, Maria

    2016-05-28

    Menopause is the permanent cessation of menstruation due to loss of ovarian follicular activity. A review of the available literature indicates that correlations between the changes that take place in a woman's body after menopause and different genetic variants are still being sought. The study was conducted in 252 women who had completed physiological menopause. The women were divided into groups according to the time elapsed since menopause. The total concentrations of estradiol and follicle-stimulating hormone were determined by means of electrochemiluminescence. The apolipoprotein E (APOE) and lepitn (LEP) genotypes were determined by real-time PCR and polymerase chain reaction-restriction fragment length polymorphism, respectively. We observed that people with the APOE3/E3 genotype entered menopause insignificantly later compared to other genotypes. Additionally, in the group of patients with the APOE3/E3 genotypes, differences in the E2 concentration were significantly related to the time since their last menstruation. There is no association found in the literature between these polymorphisms of the LEP gene and hormones. To date, attempts to formulate a model describing the association between E2 and FSH concentration with the polymorphisms of various genes of menopause in women have not been successful. This relationship is difficult to study because of the number of nongenetic factors. Environmental factors can explain variation in postmenopausal changes in hormone levels.

  9. Apolipoprotein E-Mimetic Peptide COG1410 Promotes Autophagy by Phosphorylating GSK-3β in Early Brain Injury Following Experimental Subarachnoid Hemorrhage

    Directory of Open Access Journals (Sweden)

    Xinshen Li

    2018-03-01

    Full Text Available COG1410, a mimetic peptide derived from the apolipoprotein E (apoE receptor binding region, exerts positive effect on neurological deficits in early brain injury (EBI after experimental subarachnoid hemorrhage (SAH. Currently the neuroprotective effect of COG1410 includes inhibiting BBB disruption, reducing neuronal apoptosis, and neuroinflammation. However, the effect and mechanism of COG1410 to subcellular organelles disorder have not been fully investigated. As the main pathway for recycling long-lived proteins and damaged organelles, neuronal autophagy is activated in SAH and exhibits neuroprotective effects by reducing the insults of EBI. Pharmacologically elevated autophagy usually contributes to alleviated brain injury, while few of the agents achieved clinical transformation. In this study, we explored the activation of autophagy during EBI by measuring the Beclin-1 and LC3B-II protein levels. Administration of COG1410 notably elevated the autophagic markers expression in neurons, simultaneously reversed the neurological deficits. Furthermore, the up-regulated autophagy by COG1410 was further promoted by p-GSK-3β agonist, whereas decreased by p-GSK-3β inhibitor. Taken together, these data suggest that the COG1410 might be a promising therapeutic strategy for EBI via promoting autophagy in SAH.

  10. Differential interaction of Apolipoprotein-E isoforms with insulin receptors modulates brain insulin signaling in mutant human amyloid precursor protein transgenic mice.

    Science.gov (United States)

    Chan, Elizabeth S; Chen, Christopher; Cole, Gregory M; Wong, Boon-Seng

    2015-09-08

    It is unclear how human apolipoprotein E4 (ApoE4) increases the risk for Alzheimer's disease (AD). Although Aβ levels can lead to insulin signaling impairment, these experiments were done in the absence of human ApoE. To examine ApoE role, we crossed the human ApoE-targeted replacement mice with mutant human amyloid precursor protein (APP) mice. In 26 week old mice with lower Aβ levels, the expression and phosphorylation of insulin signaling proteins remained comparable among APP, ApoE3xAPP and ApoE4xAPP mouse brains. When the mice aged to 78 weeks, these proteins were markedly reduced in APP and ApoE4xAPP mouse brains. While Aβ can bind to insulin receptor, how ApoE isoforms modulate this interaction remains unknown. Here, we showed that ApoE3 had greater association with insulin receptor as compared to ApoE4, regardless of Aβ42 concentration. In contrast, ApoE4 bound more Aβ42 with increasing peptide levels. Using primary hippocampal neurons, we showed that ApoE3 and ApoE4 neurons are equally sensitive to physiological levels of insulin. However, in the presence of Aβ42, insulin failed to elicit a downstream response only in ApoE4 hippocampal neurons. Taken together, our data show that ApoE genotypes can modulate this Aβ-mediated insulin signaling impairment.

  11. Analysis of the Relationship between Estradiol and Follicle-Stimulating Hormone Concentrations and Polymorphisms of Apolipoprotein E and LeptinGenes in Women Post-Menopause

    Directory of Open Access Journals (Sweden)

    Aleksandra Rył

    2016-05-01

    Full Text Available Background: Menopause is the permanent cessation of menstruation due to loss of ovarian follicular activity. A review of the available literature indicates that correlations between the changes that take place in a woman’s body after menopause and different genetic variants are still being sought. Methods: The study was conducted in 252 women who had completed physiological menopause. The women were divided into groups according to the time elapsed since menopause. The total concentrations of estradiol and follicle-stimulating hormone were determined by means of electrochemiluminescence. The apolipoprotein E (APOE and lepitn (LEP genotypes were determined by real-time PCR and polymerase chain reaction–restriction fragment length polymorphism, respectively. Results: We observed that people with the APOE3/E3 genotype entered menopause insignificantly later compared to other genotypes. Additionally, in the group of patients with the APOE3/E3 genotypes, differences in the E2 concentration were significantly related to the time since their last menstruation. There is no association found in the literature between these polymorphisms of the LEP gene and hormones. Conclusions: To date, attempts to formulate a model describing the association between E2 and FSH concentration with the polymorphisms of various genes of menopause in women have not been successful. This relationship is difficult to study because of the number of nongenetic factors. Environmental factors can explain variation in postmenopausal changes in hormone levels.

  12. Coupling of an indicator-free electrochemical DNA biosensor with polymerase chain reaction for the detection of DNA sequences related to the apolipoprotein E

    Energy Technology Data Exchange (ETDEWEB)

    Lucarelli, Fausto; Marrazza, Giovanna; Palchetti, Ilaria; Cesaretti, S.; Mascini, Marco

    2002-09-26

    This paper describes a disposable indicator-free electrochemical DNA biosensor applied to the detection of apolipoprotein E (apoE) sequences in PCR samples. In the indicator-free assays, the duplex formation was detected by measuring the electrochemical signal of the guanine base of nucleic acids. The biosensor format involved the immobilisation of an inosine-modified (guanine-free) probe onto a screen-printed electrode (SPE) transducer and the detection of the duplex formation in connection with the square-wave voltammetric measurement of the oxidation peak of the guanine of the target sequence. The indicator-free scheme has been characterised using 23-mer oligonucleotides as model: parameters affecting the hybridisation assay such as probe immobilisation conditions, hybridisation time, use of hybridisation accelerators were examined and optimised. The analysis of PCR samples (244 bp DNA fragments, obtained by amplification of DNA extracted from human blood) required a further optimisation of the experimental procedure. In particular, a lower steric hyndrance of the probe modified surface was essential to allow an efficient hybridisation of the target DNA fragment. Negative controls have been performed using the PCR blank and amplicons unrelated to the immobilised probe. A 10 min hybridisation time allowed a full characterisation of each sample.

  13. Genetic influence of apolipoprotein E4 genotype on hippocampal morphometry: An N = 725 surface-based Alzheimer's disease neuroimaging initiative study.

    Science.gov (United States)

    Shi, Jie; Leporé, Natasha; Gutman, Boris A; Thompson, Paul M; Baxter, Leslie C; Caselli, Richard J; Wang, Yalin

    2014-08-01

    The apolipoprotein E (APOE) e4 allele is the most prevalent genetic risk factor for Alzheimer's disease (AD). Hippocampal volumes are generally smaller in AD patients carrying the e4 allele compared to e4 noncarriers. Here we examined the effect of APOE e4 on hippocampal morphometry in a large imaging database-the Alzheimer's Disease Neuroimaging Initiative (ADNI). We automatically segmented and constructed hippocampal surfaces from the baseline MR images of 725 subjects with known APOE genotype information including 167 with AD, 354 with mild cognitive impairment (MCI), and 204 normal controls. High-order correspondences between hippocampal surfaces were enforced across subjects with a novel inverse consistent surface fluid registration method. Multivariate statistics consisting of multivariate tensor-based morphometry (mTBM) and radial distance were computed for surface deformation analysis. Using Hotelling's T(2) test, we found significant morphological deformation in APOE e4 carriers relative to noncarriers in the entire cohort as well as in the nondemented (pooled MCI and control) subjects, affecting the left hippocampus more than the right, and this effect was more pronounced in e4 homozygotes than heterozygotes. Our findings are consistent with previous studies that showed e4 carriers exhibit accelerated hippocampal atrophy; we extend these findings to a novel measure of hippocampal morphometry. Hippocampal morphometry has significant potential as an imaging biomarker of early stage AD. Copyright © 2014 Wiley Periodicals, Inc.

  14. Influences of a-tocopherol on cholesterol metabolism and fatty streak development in apolipoprotein E-deficient mice fed an atherogenic diet

    Directory of Open Access Journals (Sweden)

    Peluzio M.C.G.

    2001-01-01

    Full Text Available Although the role of oxidized lipoproteins is well known in atherogenesis, the role of vitamin E supplementation is still controversial. There is also little information about cholesterol metabolism (hepatic concentration and fecal excretion in the new models of atherosclerosis. In the present study, we evaluated the effect of moderate vitamin E supplementation on cholesterol metabolism and atherogenesis in apolipoprotein E (apo E-deficient mice. Apo E-deficient mice were fed an atherogenic diet containing 40 or 400 mg/kg of alpha-tocopherol acetate for 6 weeks. Total cholesterol in serum and liver and 3-OH-alpha-sterols in feces, and fecal excretion of bile acids were determined and histological analyses of aortic lesion were performed. A vitamin E-rich diet did not affect body weight, food intake or serum cholesterol. Serum and hepatic concentrations of cholesterol as well as sterol concentration in feces were similar in both groups. However, when compared to controls, the alpha-tocopherol-treated mice showed a reduction of about 60% in the atherosclerotic lesions when both the sum of lesion areas and the average of the largest lesion area were considered. These results demonstrate that supplementation of moderate doses of alpha-tocopherol was able to slow atherogenesis in apo E-deficient mice and to reduce atherogenic lipoproteins without modifying the hepatic pool or fecal excretion of cholesterol and bile acids.

  15. Upregulation of Mineralocorticoid Receptor in the Hypothalamus Associated with a High Anxiety-like Level in Apolipoprotein E4 Transgenic Mice.

    Science.gov (United States)

    Meng, Fan-Tao; Zhao, Jun; Fang, Hui; Zhang, Li-Feng; Wu, Hui-Mei; Liu, Ya-Jing

    2017-07-01

    Anxiety symptoms occur in a large portion of Alzheimer's disease (AD) patients. ApolipoproteinE-4 (ApoE ε4 allele), a risk factor for AD, has been recognized as an important contributor to psychiatric disorders. In the present study, we aimed to investigate the corticosterone level in relation to anxiety-like behavior changes in transgenic male mice with different glial fibrillary acidic protein (GFAP)-ApoE isoforms. GFAP-ApoE4 transgenic mice aged 3 months showed higher anxiety-like behavior in open field, light-dark box and elevated plus maze tasks compared with that of age-matched GFAP-ApoE3 mice. However, corticotropin releasing factor levels in the hypothalamus and plasma corticosterone secretion were similar in GFAP-ApoE3 and GFAP-ApoE4 transgenic male mice. Additionally, increased expression of the mineralocorticoid receptor (MR) and unchanged expression of the glucocorticoid receptor were observed in the hypothalamus of GFAP-ApoE4 mice. However, no significant differences were found in the expression levels of the MR in GFAP-ApoE3 and GFAP-ApoE4 mice at postnatal day 2. In conclusion, we found that MR upregulation rather than corticosterone level changes in the early stage of adulthood was associated with the higher anxiety-like level measured in GFAP-ApoE4 mice.

  16. Does Apolipoprotein e4 Status Moderate the Association of Family Environment with Long-Term Child Functioning following Early Moderate to Severe Traumatic Brain Injury? A Preliminary Study.

    Science.gov (United States)

    Treble-Barna, Amery; Zang, Huaiyu; Zhang, Nanhua; Martin, Lisa J; Yeates, Keith Owen; Taylor, H Gerry; Wade, Shari L; Kurowski, Brad G

    2016-09-01

    To examine whether apolipoprotein e4 (APOE) status moderates the association of family environment with child functioning following early traumatic brain injury (TBI). Sixty-five children with moderate to severe TBI and 70 children with orthopedic injury (OI) completed assessments 6, 12, 18 months, and 3.5 and 6.8 years post injury. DNA was extracted from saliva samples and genotyped for APOE e4 status. Linear mixed models examined moderating effects of APOE e4 status on associations between two family environment factors (parenting style, home environment) and three child outcomes (executive functioning, behavioral adjustment, adaptive functioning). Children with TBI who were carriers of the e4 allele showed poorer adaptive functioning relative to non-carriers with TBI and children with OI in the context of low authoritarianism. At high levels of authoritarianism, non-carriers with TBI showed the poorest adaptive functioning among groups. There were no main effects or interactions involving APOE and executive functioning or behavioral adjustment. The APOE e4 allele was detrimental for long-term adaptive functioning in the context of positive parenting, whereas in less optimal parenting contexts, being a non-carrier was detrimental. We provide preliminary evidence for an interaction of APOE e4 status and parenting style in predicting long-term outcomes following early TBI. (JINS, 2016, 22, 859-864).

  17. Associations between apolipoprotein E genotypes and serum levels of glucose, cholesterol, and triglycerides in a cognitively normal aging Han Chinese population.

    Science.gov (United States)

    Tao, Qing-Qing; Chen, Yan; Liu, Zhi-Jun; Sun, Yi-Min; Yang, Ping; Lu, Shen-Ji; Xu, Miao; Dong, Qin-Yun; Yang, Jia-Jun; Wu, Zhi-Ying

    2014-01-01

    To determine the associations between apolipoprotein E (APOE) genotypes and serum levels of glucose, total cholesterol, and triglycerides in a cognitively normal aging Han Chinese population. There were 1,003 cognitively normal aging subjects included in this study. APOE genotypes were analyzed and biochemical parameters were tested. All the subjects were divided into three groups according to APOE genotypes: (1) E2/2 or E2/3 (APOE E2); (2) E3/3 (APOE E3); and (3) E2/4, E3/4, or E4/4 (APOE E4). Correlations of serum levels of glucose, total cholesterol, and triglycerides with APOE genotypes were assessed. E2, E3, and E4 allele frequencies were found to be 6.2%, 82.1%, and 11.7%, respectively. Serum levels of total cholesterol were higher in the APOE E4 group (Paging population. However, there was no correlation between APOE genotypes and serum levels of glucose or total triglycerides.

  18. The role of apolipoprotein E as a risk factor for an earlier age at onset for Machado-Joseph disease is doubtful.

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    Qi Zhou

    Full Text Available Machado-Joseph disease (MJD is an inherited neurodegenerative disease caused by an expanded CAG repeat in the ATXN3 gene. Although the principal genetic determinant of the age at onset (AAO is the length of the expanded CAG repeat, the additional genetic contribution of MJD toward the AAO has mostly not yet been clarified. It was recently suggested in two independent studies that apolipoprotein E (APOE might be associated with AAO variability in MJD patients. To identify the potential modifier effect of APOE polymorphisms on the AAO of MJD patients, 403 patients with MJD (confirmed by molecular tests from eastern and southeastern China were enrolled in the present study. CAG repeats in the ATXN3 and APOE polymorphisms were genotyped. Data were analyzed using a statistical package. No contribution of APOE polymorphisms to the variance in disease onset was observed using ANCOVA (F = 0.183, P = 0.947. However, significant effects on the AAO of MJD were found for the normal ATXN3 allele and for the interaction of mutant and normal ATXN3 alleles in a multiple linear regression model (P = 0.043 and P = 0.035, respectively. Our study does not support a role for APOE as a genetic modifier of the AAO of MJD. Additionally, our study presents evidence that the normal ATXN3 allele and its interaction with mutant alleles contribute toward AAO variance in MJD patients.

  19. [Prevalence of Variants in the Apolipoprotein E (APOE) Gene in a General Population of Adults from an Urban Area of Medellin (Antioquia)].

    Science.gov (United States)

    Arango Viana, Juan Carlos; Valencia, Ana Victoria; Páez, Ana Lucía; Montoya Gómez, Nilton; Palacio, Carlos; Arbeláez, María Patricia; Bedoya Berrío, Gabriel; García Valencia, Jenny

    2014-01-01

    To determine the allelic and genotype frequencies of apolipoproteine E (APOE) gene in a representative sample of the adult population of Medellin in 2010. A representative sample of the adult population of Medellin, was obtained by means of a multi-stage, stratified, conglomerate based sampling method. APOE genotyping was carried out on each of the participants. The sampling design was taken into consideration for the frequencies and association analysis. The frequencies of the APOE alleles E2, E3 and E4 were 3.9, 92.0 and 4.1%, respectively. The frequencies of the different APOE genotypes were as follows: 2/2, 0.2%; 2/3, 6.8%; 2/4, 0.6%; 3/3, 85.0%; 3/4, 7.2%, and 4/4, 0.3%. The allelic and genotype frequencies of APOE in an adult population of Medellin did not differ substantially from other series reported in South America. These data are important to determine the real impact of APOE on the population risk of several psychiatric diseases. Copyright © 2013 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

  20. High-Fat Diet Changes Hippocampal Apolipoprotein E (ApoE in a Genotype- and Carbohydrate-Dependent Manner in Mice.

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    Courtney Lane-Donovan

    Full Text Available Alzheimer's disease is a currently incurable neurodegenerative disease affecting millions of individuals worldwide. Risk factors for Alzheimer's disease include genetic risk factors, such as possession of ε4 allele of apolipoprotein E (ApoE4 over the risk-neutral ApoE3 allele, and lifestyle risk factors, such as diet and exercise. The intersection of these two sources of disease risk is not well understood. We investigated the impact of diet on ApoE levels by feeding wildtype, ApoE3, and ApoE4 targeted replacement (TR mice with chow, high-fat, or ketogenic (high-fat, very-low-carbohydrate diets. We found that high-fat diet affected both plasma and hippocampal levels of ApoE in an isoform-dependent manner, with high-fat diet causing a surprising reduction of hippocampal ApoE levels in ApoE3 TR mice. Conversely, the ketogenic diet had no effect on hippocampal ApoE. Our findings suggest that the use of dietary interventions to slow the progression AD should take ApoE genotype into consideration.

  1. Quantitative analysis of senile plaques in Alzheimer disease: observation of log-normal size distribution and molecular epidemiology of differences associated with apolipoprotein E genotype and trisomy 21 (Down syndrome).

    OpenAIRE

    Hyman, B T; West, H L; Rebeck, G W; Buldyrev, S V; Mantegna, R N; Ukleja, M; Havlin, S; Stanley, H E

    1995-01-01

    The discovery that the epsilon 4 allele of the apolipoprotein E (apoE) gene is a putative risk factor for Alzheimer disease (AD) in the general population has highlighted the role of genetic influences in this extremely common and disabling illness. It has long been recognized that another genetic abnormality, trisomy 21 (Down syndrome), is associated with early and severe development of AD neuropathological lesions. It remains a challenge, however, to understand how these facts relate to the...

  2. Calix[4]arene supported clusters: a dimer of [Mn(III)Mn(II)] dimers

    DEFF Research Database (Denmark)

    Taylor, Stephanie M; McIntosh, Ruaraidh D; Beavers, Christine M

    2011-01-01

    Phosphinate ligands allow for the transformation of a calix[4]arene supported [Mn(III)(2)Mn(II)(2)] tetramer cluster motif into an unusual [Mn(III)Mn(II)](2) dimer of dimers; the clusters self-assemble in the crystal to form bi-layer arrays reminiscent of the typical packing of calixarene solvates....

  3. Liquid crystal dimers

    CERN Document Server

    Kumar Pal, Santanu

    2017-01-01

    This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.

  4. Simultaneous analysis of (13)C-glutathione as its dimeric form GSSG and its precursor [1-(13)C]glycine using liquid chromatography/isotope ratio mass spectrometry.

    Science.gov (United States)

    Schierbeek, Henk; Rook, Denise; te Braake, Frans W J; Dorst, Kristien Y; Voortman, Gardi; Godin, Jean-Philippe; Fay, Laurent-Bernard; van Goudoever, Johannes B

    2009-09-01

    Determination of glutathione kinetics using stable isotopes requires accurate measurement of the tracers and tracees. Previously, the precursor and synthesized product were measured with two separate techniques, liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In order to reduce sample volume and minimize analytical effort we developed a method to simultaneously determine (13)C-glutathione as its dimeric form (GSSG) and its precursor [1-(13)C]glycine in a small volume of erythrocytes in one single analysis. After having transformed (13)C-glutathione into its dimeric form GSSG, we determined both the intra-erythrocytic concentrations and the (13)C-isotopic enrichment of GSSG and glycine in 150 microL of whole blood using liquid chromatography coupled to LC/IRMS. The results show that the concentration (range of micromol/mL) was reliably measured using cycloleucine as internal standard, i.e. with a precision better than 0.1 micromol/mL. The (13)C-isotopic enrichment of GSSG and glycine measured in the same run gave reliable values with excellent precision (standard deviation (sd) variety of kinetic studies with relatively low dose administration of tracers, reducing the total cost of the study design. In addition, only a minimal sample volume is required, enabling studies even in very small subjects, such as preterm infants. Copyright (c) 2009 John Wiley & Sons, Ltd.

  5. The relationship between apolipoprotein E gene ε2/ε3/ε4 polymorphism and breast cancer risk: a systematic review and meta-analysis

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    Liu YL

    2016-03-01

    Full Text Available Yun-Long Liu,1 Hao-Min Zhang,1 Hong-Ming Pan,2 Yu-Hang Bao,2 Jing Xue,2 Tian-Chang Wang,1 Xiao-Cheng Dong,1 Xiao-Ling Li,3 Hong-Guang Bao1 1Department of Chest Surgery, The Second Affiliated Hospital of Qiqihar Medical University, 2Basic Medical Science College, Qiqihar Medical University, Qiqihar, Heilongjiang, People’s Republic of China; 3Department of Anatomy, Basic Medical Science College, Qiqihar Medical University, Qiqihar, Heilongjiang, People’s Republic of China Objective: We conducted a systematic review and meta-analysis aiming to assess the relationship between apolipoprotein E (APOE gene ε2/ε3/ε4 polymorphism and breast cancer risk. Methods: Yun-Long Liu and Hao-Min Zhang independently completed literature retrieval and data collection, and statistical analyses were performed by Stata. Individual odds ratio (OR and 95% confidence interval (CI were pooled in a random-effects model using the DerSimonian–Laird method. Heterogeneity was evaluated by I2 statistic at a significance level of 50%. Publication bias was assessed by Egger’s test. Results: Eleven articles including 2,074 breast cancer patients and 2,372 controls were summarized. Using the most common allele ε3 as a reference, the ε2 (OR =0.87, 95% CI =0.72–1.05, P=0.154, I2=0.0% and ε4 (OR =1.07, 95% CI =0.80–1.42, P=0.654, I2=71.8% alleles were not found to be significantly associated with breast cancer risk in the overall analyses. Subgroup analyses revealed that the comparison of allele ε4 with ε3 was significant in Asians (OR =1.58, 95% CI =1.17–6.32, P=0.003, I2=12.1% and in studies that used the restriction fragment length polymorphism (RFLP genotyping method (OR =1.27; 95% CI =1.01–1.61, P=0.045, I2=34.3%, and was marginally significant in hospital-based studies (OR =1.33; 95% CI =0.98–1.79, P=0.065, I2=30.2%, without heterogeneity. Moreover, the presence of the ε2 allele was significantly associated with breast cancer in small studies (total

  6. The effect of tocopheryl phosphates (TPM) on the development of atherosclerosis in apolipoprotein-E deficient mice.

    Science.gov (United States)

    Libinaki, Roksan; Vinh, Antony; Tesanovic-Klajic, Sonja; Widdop, Robert; Gaspari, Tracey

    2017-12-01

    α-Tocopheryl phosphate (TP) is a naturally occurring form of vitamin E found in the body. In the present study we compared the ability of an α-TP mixture (TPM) against a standard vitamin E supplement, α-tocopherol acetate (TA) on the development of atherosclerotic lesions in ApoE-deficient mice. Mice were maintained on either a normal chow diet for 24 weeks (Normal Diet), vs a group in which the final 8 weeks of the 24-week period mice were placed on a high fat (21%), high cholesterol (0.15%) challenge diet (HFHC), to exacerbate atherosclerotic lesion development.. The difference in these two control groups established the extent of the diet-induced atherosclerotic lesion development. Mice in the various treatment groups received either TA (300 mg/kg chow) or TPM (6.7-200 mg/kg chow) for 24 weeks, with TPM treatment resulting in dose-dependent significant reductions in atherosclerotic lesion formation and plasma levels of pro-inflammatory cytokines. TA-treated mice, with the tocopherol equivalent TPM dose (200 mg/kg chow), showed no significant reduction in plasma lipid levels or evidence for aortic lesion regression. At this TPM equivalent TA dose, a 44% reduction in aortic lesion formation was observed. In addition, these TPM treated mice, also showed a marked reduction in aortic superoxide formation and decreased circulating plasma levels of known pro-inflammatory markers IL-6, MCP-1, IL-1β, IFN-γ and TNF-α. These findings indicate that TPM treatment slows progression of atherosclerotic lesions in ApoE-deficient mice with this effect potentially involving reduced oxidative stress and decreased inflammation. © 2017 John Wiley & Sons Australia, Ltd.

  7. Obesity, Apolipoprotein E ε4, and Difficulties in Activities of Daily Living Among Older Adults: a 6-Year Follow-up Study.

    Science.gov (United States)

    Chen, Li-Jung; Steptoe, Andrew; Ku, Po-Wen

    2017-04-01

    Obesity has been associated with increased physical limitations among older adults, although few studies have adjusted for important covariates. There is limited information about the relationship between apolipoprotein E (APOE) polymorphisms and physical limitations, and the findings have been inconsistent. This study examined the longitudinal associations of obesity and APOE ε4 with difficulties in activities of daily living (ADLs) over a 6-year follow-up period controlling for multiple covariates. Data were analyzed from the Social Environment and Biomarkers of Aging Study (SEBAS) in Taiwan collected in 2000 and 2006, involving a cohort of 639 participants (mean age = 66). Body mass index (BMI) was used to define obesity at a baseline, and the APOE genotype was classified into an APOE ε4 carrier and non-carrier status. The combination of basic and instrumental activities of daily living (ADLs and IADLs) was used to define impaired ADLs. APOE ε4 carriers had greater difficulties in combined ADLs (incident rate ratio; IRR = 1.87, 95 % CI = 1.40-2.51) than non-carriers. Obese but not overweight adults had greater difficulties in activities of daily living (IRR = 1.59, 95 % CI = 1.20-2.10) compared with the normal/underweight group. Obese older adults without APOE ε4 had greater subsequent difficulties in ADLs than non-obese non-carriers. Among APOE ε4 carriers, obesity was not a significant risk factor for the development of impaired ADLs in older adults, indicating an interaction between genotype and obesity. The interaction between genotype and obesity phenotype adds new information about the determinants of physical impairment.

  8. Polymorphisms of apolipoprotein E gene and cognitive functions of postmenopausal women, measured by battery of computer tests - Central Nervous System Vital Signs.

    Science.gov (United States)

    Bojar, Iwona; Wojcik-Fatla, Angelina; Owoc, Alfred; Lewinski, Andrzej

    2012-01-01

    Apolipoprotein E (APOE) gene belongs to the group of genes increasing the risk of the Alzheimer's disease (AD) development. The purpose of the study was the analysis of cognitive functions in postmenopausal women having different polymorphisms of APOE gene; battery of computer tests - Central Nervous System Vital Signs (CNS-VS) were employed. The women were qualified into the examined group on the grounds of clinical symptoms (minimum 2 years after the last menstruation), as well as on the basis of FSH concentration. At the qualification stage, a short test - Montreal Scale of Cognitive Function Assessment (MoCA) was conducted. The assessment of cognitive functions was made with the use of diagnostic CNS-Vital Signs equipment. Genomic DNA isolation was extracted from human whole blood. Multiplex PCR reactions have been performed in a single reaction tube with six (6) primers, consisting of 2 common primers and 4 specific primers [2 - for each of 2 single nucleotide polymorphism (SNP) sites]. About half of the examined postmenopausal women were placed below average in the majority of the examined cognitive functions. The biggest impairments occurred in the field of processing speed, and the smallest - in the field of verbal and visual memory. Polymorphisms of APOE gene were considerably linked with the level of results of the majority of cognitive functions among postmenopausal women, as measured by battery of computer tests - CNS-VS. The presence of ε2/ε3 polymorphism of APOE gene impacted positively the obtained results of cognitive functions, whereas the presence of ε3/ε4, or ε4/ε4 polymorphisms worsened the obtained results.

  9. Apolipoprotein E deficiency and high-fat diet cooperate to trigger lipidosis and inflammation in the lung via the toll-like receptor 4 pathway.

    Science.gov (United States)

    Ouyang, Qiufang; Huang, Ziyang; Lin, Huili; Ni, Jingqin; Lu, Huixia; Chen, Xiaoqing; Wang, Zhenhua; Lin, Ling

    2015-08-01

    Apolipoprotein E deficiency (ApoE(-/-)) combined with a high-fat Western-type diet (WD) is known to activate the toll-like receptor (TLR4) pathway and promote atherosclerosis. However, to date, the pathogenic effects of these conditions on the lung have not been extensively studied. Therefore, the present study examined the effects of ApoE(-/-) and a WD on lung injury and investigated the underlying mechanisms. ApoE(-/-) and wild-type mice were fed a WD or normal chow diet for 4, 12 and 24 weeks. Lung inflammation, lung cholesterol content and cytokines profiles in broncho-alveolar lavage fluid (BALF) were determined. TLR4 and its main downstream molecules were analyzed with western blot analysis. In addition, the role of the TLR4 pathway was further validated using TLR4-targeted gene silencing. The results showed that ApoE(-/-) mice developed lung lipidosis following 12 weeks of receiving a WD, as evidenced by an increased lung cholesterol content. Moreover, dependent on the time period of receiving the diet, those mice exhibited pulmonary inflammation, which was manifested by initial leukocyte recruitment (at 4 weeks), by increased alveolar septal thickness and mean linear intercept as well as elevated production of inflammation mediators (at 12 weeks), and by granuloma formation (at 24 weeks). The expression levels of TLR4, myeloid differentiation primary response 88 (MyD88) and nuclear factor kappa B were markedly upregulated in ApoE(-/-) WD mice at week 12. However, these effects were ameliorated by shRNA-mediated knockdown of TLR4. By contrast, ApoE(-/-) ND or wild-type WD mice exhibited low-grade or no inflammation and mild lipidosis. The levels of TLR4 and MyD88 in those mice showed only minor changes. In conclusion, ApoE deficiency acts synergistically with a WD to trigger lung lipidosis and inflammation at least in part via TLR4 signaling.

  10. Apolipoprotein E epsilon-4 polymorphism is associated with younger age at referral to a lipidology clinic and a poorer response to lipid-lowering therapy

    Directory of Open Access Journals (Sweden)

    Monteiro Pedro

    2011-03-01

    Full Text Available Abstract Background The risk of coronary heart disease (CHD is related to environmental factors and genetic variants. Apolipoprotein E (apoE polymorphisms are heritable determinants of total and low-density lipoprotein cholesterol, with some authors suggesting an association between the ε4 allele and CHD. We investigated the relationship between apoE genotype and age at referral to a specialized lipid clinic by the primary care physician and whether the benefits of treatment with statin differed between genotypes. Methods We assessed individual apoE genotypes and lipid blood profile in a total of 463 patients followed at a specialized lipid clinic due to dyslipidemia, with a 3-year median follow-up time. The primary care physician at the time of the referral had no access to the apoE genotyping results. Carriers of apoE ε4/ε2 genotype were excluded. Results The frequencies of ε2, ε3 and ε4 alleles were 7.8, 78.9 and 13.3%, respectively. There were no significant differences between genders. Although with similar lipid profiles and antidyslipidemic drug usage at baseline, ε4-carriers were referred to the clinic at a younger age (44.2 ± 14.7 years compared with non-ε4 carriers (50.6 ± 13.8 years (p Conclusion Our findings support the concept that there is a reduced response to anti-dyslipidemic treatment in ε4 carriers; this can be a contributing factor for the earlier referral of these patients to our specialized lipid clinic and reinforces the usefulness of apoE genotyping in predicting patients response to lipid lowering therapies.

  11. Associations of apolipoprotein E and low-density lipoprotein receptor-related protein 5 polymorphisms with dyslipidemia and generalized aggressive periodontitis in a Chinese population.

    Science.gov (United States)

    Gao, H; Tian, Y; Meng, H; Hou, J; Xu, L; Zhang, L; Shi, D; Lu, R; Feng, X; Wang, X; Chen, Z

    2015-08-01

    Dyslipidemia is associated with aggressive periodontitis, a condition characterized by the rapid destruction of the periodontium. Apolipoprotein E (APOE) and low-density lipoprotein receptor-related protein 5 (LRP5) are involved in immunomodulation and inflammatory activity. We evaluated the association of LRP5 and APOE polymorphisms with serum lipid concentrations and generalized aggressive periodontitis within a Chinese population. Mean serum lipid concentrations were compared across LRP5 and APOE polymorphisms, among cases (n = 185) and controls (n = 138). Multivariable logistic regression was used to evaluate the independent and combined associations of LRP5 and APOE polymorphisms with generalized aggressive periodontitis. Compared with controls, individuals with generalized aggressive periodontitis exhibited significantly lower serum total cholesterol (TC) and lower high-density lipoprotein cholesterol (HDL-c). Individuals with LRP5 polymorphisms (rs682429-AA or rs312016-GG) exhibited higher TC, higher HDL-c and decreased odds for generalized aggressive periodontitis. Haplotype (A-G), determined by rs682429 and rs312016, was also associated with decreased odds for generalized aggressive periodontitis. Furthermore, individuals with the combined polymorphisms (LRP5-rs682429-AA and APOE-rs429358-CC/CT) had higher levels of low-density lipoprotein cholesterol, higher levels of TC and decreased odds for generalized aggressive periodontitis. Independently or combined with APOE, LRP5 polymorphisms may lead to dyslipidemia and are associated with generalized aggressive periodontitis. Dyslipidemia may be a risk indicator for generalized aggressive periodontitis in the Chinese population. Furthermore, two LRP5 polymorphisms (rs682429 and rs312016) might be useful for identifying subjects at higher risk of generalized aggressive periodontitis. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Modest vasomotor dysfunction induced by low doses of C60 fullerenes in apolipoprotein E knockout mice with different degree of atherosclerosis

    Directory of Open Access Journals (Sweden)

    Loft Steffen

    2009-02-01

    Full Text Available Abstract Background Exposure to small size particulate matter in urban air is regarded as a risk factor for cardiovascular effects, whereas there is little information about the impact on the cardiovascular system by exposure to pure carbonaceous materials in the nano-size range. C60 fullerenes are nano-sized particles that are expected to have a widespread use, including cosmetics and medicines. Methods We investigated the association between intraperitoneal injection of pristine C60 fullerenes and vasomotor dysfunction in the aorta of 11–13 and 40–42 weeks old apolipoprotein E knockout mice (apoE-/- with different degree of atherosclerosis. Results The aged apoE-/-mice had lower endothelium-dependent vasorelaxation elicited by acetylcholine in aorta segments mounted in myographs and the phenylephrine-dependent vasoconstriction response was increased. One hour after an intraperitoneal injection of 0.05 or 0.5 mg/kg of C60 fullerenes, the young apoE-/- mice had slightly reduced maximal endothelium-dependent vasorelaxation. A similar tendency was observed in the old apoE-/- mice. Hampered endothelium-independent vasorelaxation was also observed as slightly increased EC50 of sodium nitroprusside-induced vasorelaxation response in young apoE-/- mice. Conclusion Treatment with C60 fullerenes affected mainly the response to vasorelaxation in young apoE-/- mice, whereas the vasomotor dysfunction in old apoE-/- mice with more advanced atherosclerosis was less affected by acute C60 fullerene treatment. These findings represent an important step in the hazard characterization of C60 fullerenes by showing that intraperitoneal administration is associated with a moderate decrease in the vascular function of mice with atherosclerosis.

  13. Apolipoprotein E genotype is associated with temporal and hippocampal atrophy rates in healthy elderly adults: a tensor-based morphometry study.

    Science.gov (United States)

    Lu, Po H; Thompson, Paul M; Leow, Alex; Lee, Grace J; Lee, Agatha; Yanovsky, Igor; Parikshak, Neelroop; Khoo, Theresa; Wu, Stephanie; Geschwind, Daniel; Bartzokis, George

    2011-01-01

    Apolipoprotein E (ApoE) ε4 genotype is a strong risk factor for developing Alzheimer's disease (AD). Conversely, the presence of the ε2 allele has been shown to mitigate cognitive decline. Tensor-based morphometry (TBM), a novel computational approach for visualizing longitudinal progression of brain atrophy, was used to determine whether cognitively intact elderly participants with the ε4 allele demonstrate greater volume reduction than those with the ε2 allele. Healthy "younger elderly" volunteers, aged 55-75, were recruited from the community and hospital staff. They were evaluated with a baseline and follow-up MRI scan (mean scan interval = 4.72 years, s.d. = 0.55) and completed ApoE genotyping. Twenty-seven participants were included in the study of which 16 had the ε4 allele (all heterozygous ε3ε4 genotype) and 11 had the ε2ε3 genotype. The two groups did not differ significantly on any demographic characteristics and all subjects were cognitively "normal" at both baseline and follow-up time points. TBM was used to create 3D maps of local brain tissue atrophy rates for individual participants; these spatially detailed 3D maps were compared between the two ApoE groups. Regional analyses were performed and the ε4 group demonstrated significantly greater annual atrophy rates in the temporal lobes (p = 0.048) and hippocampus (p = 0.016); greater volume loss was observed in the right hippocampus than the left. TBM appears to be useful in tracking longitudinal progression of brain atrophy in cognitively asymptomatic adults. Possession of the ε4 allele is associated with greater temporal and hippocampal volume reduction well before the onset of cognitive deficits.

  14. Impact of psychological stress on the associations between apolipoprotein E variants and metabolic traits: findings in an American sample of caregivers and controls.

    Science.gov (United States)

    Kring, Sofia I Iqbal; Brummett, Beverly H; Barefoot, John; Garrett, Melanie E; Ashley-Koch, Allison E; Boyle, Stephen H; Siegler, Ilene C; Sørensen, Thorkild I A; Williams, Redford B

    2010-06-01

    To examine the association between apolipoprotein E (APOE) gene variants and waist circumference, fasting plasma glucose, serum insulin, serum high-density lipoprotein cholesterol, and serum triglycerides, all metabolic traits known as cardiovascular disease (CVD) endophenotypes, in a population of stressed individuals and controls. Abdominal obesity, insulin resistance, elevated serum lipid concentration, and APOE polymorphisms have been associated with CVD risk. Current evidence supports the hypothesis that gene-environment interactions modulate serum lipid concentrations. The association between rs769450, rs405509, rs439401, and metabolic traits were analyzed in a U.S. sample of 126 white caregivers of a relative with Alzheimer';s disease or other major dementia and 122 white controls. The associations were analyzed, using multivariate analysis of variance adjusted for age, sex, and medications. Significant multivariate interactions were found, using both additive (p = .009) and dominant (p = .047) models between rs439401 (C/T) and caregiver stress in relation to a profile of metabolic variables. Univariate analyses found the TT genotype to be associated with more adverse levels of waist circumference (interaction, p = .026), triglycerides (interaction, p = .001) and high-density lipoprotein cholesterol (interaction, p = .001) among caregivers but with a more favorable profile of these endophenotypes among controls. There were no significant associations or interactions involving the other two single nucleotide polymorphisms. The APOE rs439401 TT genotype is associated with an adverse metabolic profile among chronically stressed individuals compared with individuals not similarly stressed in whom a more favorable profile is expressed. Confirmation of these results in further research would indicate that the TT genotype can be used to identify persons at high risk for CVD when subjected to chronic stress.

  15. Apolipoprotein E4, Gender, Body Mass Index, Inflammation, Insulin Resistance, and Air Pollution Interactions: Recipe for Alzheimer's Disease Development in Mexico City Young Females.

    Science.gov (United States)

    Calderón-Garcidueñas, Lilian; de la Monte, Suzanne M

    2017-01-01

    Given the epidemiological trends of increasing Alzheimer's disease (AD) and growing evidence that exposure and lifestyle factors contribute to AD risk and pathogenesis, attention should be paid to variables such as air pollution, in order to reduce rates of cognitive decline and dementia. Exposure to fine particulate matter (PM2.5) and ozone (O3) above the US EPA standards is associated with AD risk. Mexico City children experienced pre- and postnatal high exposures to PM2.5, O3, combustion-derived iron-rich nanoparticles, metals, polycyclic aromatic hydrocarbons, and endotoxins. Exposures are associated with early brain gene imbalance in oxidative stress, inflammation, innate and adaptive immune responses, along with epigenetic changes, accumulation of misfolded proteins, cognitive deficits, and brain structural and metabolic changes. The Apolipoprotein E (APOE) 4 allele, the most prevalent genetic risk for AD, plays a key role in the response to air pollution in young girls. APOE 4 heterozygous females with >75% to <94% BMI percentiles are at the highest risk of severe cognitive deficits (1.5-2 SD from average IQ). This review focused on the relationships between gender, BMI, systemic and neural inflammation, insulin resistance, hyperleptinemia, dyslipidemia, vascular risk factors, and central nervous system involvement in APOE4 urbanites exposed to PM2.5 and magnetite combustion-derived iron-rich nanoparticles that can reach the brain. APOE4 young female heterozygous carriers constitute a high-risk group for a fatal disease: AD. Multidisciplinary intervention strategies could be critical for prevention or amelioration of cognitive deficits and long-term AD progression in young individuals at high risk.

  16. Cadmium-induced malignant transformation of rat liver cells: Potential key role and regulatory mechanism of altered apolipoprotein E expression in enhanced invasiveness.

    Science.gov (United States)

    Suzuki, Masayo; Takeda, Shuso; Teraoka-Nishitani, Noriko; Yamagata, Akane; Tanaka, Takahiro; Sasaki, Marika; Yasuda, Natsuki; Oda, Makiko; Okano, Tatsuji; Yamahira, Kazuhiro; Nakamura, Yuta; Kobayashi, Takanobu; Kino, Katsuhito; Miyazawa, Hiroshi; Waalkes, Michael P; Takiguchi, Masufumi

    2017-05-01

    Cadmium is a transition metal that is classified as human carcinogen by the International Agency for Research on Cancer (IARC) with multiple target sites. Many studies using various model systems provide evidence of cadmium-induced malignancy formation in vivo or malignant cell transformation in vitro. Nonetheless, further studies are needed to completely understand the mechanisms of cadmium carcinogenicity. Our prior studies have utilized a rat liver epithelial cell line (TRL 1215) as a model for cadmium-induced malignant transformation. In the present study, we focused on the molecular mechanisms of this malignant transformation, especially with regard to hyper-invasiveness stimulated by cadmium transformation. By performing a series of biochemical analyses on cadmium transformed cells, it was determined that cadmium had significantly down-regulated the expression of apolipoprotein E (ApoE). ApoE was recently established as a suppressor of cell invasion. A key factor in the suppression of ApoE by cadmium appeared to be that the metal evoked a 5-aza-2'-deoxycytidine-sensitive hypermethylation of the regulatory region of ApoE, coupled with interference of the action of liver X receptor α (LXRα), a transcriptional regulator for ApoE. Furthermore, the expression of LXRα itself was suppressed by cadmium-mediated epigenetic modification. Re-expression of ApoE clearly abrogated the cell invasion stimulated by cadmium-induced malignant transformation. Together, the current results suggest that the cadmium-mediated enhanced cell invasion is linked to down-regulation of ApoE during malignant transformation these liver cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Apolipoprotein E polymorphism in India

    DEFF Research Database (Denmark)

    Singh, P; Singh, M; Gerdes, Lars Ulrik

    2001-01-01

    , India. Three alleles APOE*E2, APOE*E3 and APOE*E4 were observed in Ramgarhia and Ramdasia with the frequencies of 0.031, 0.913, 0.056 and 0.043, 0.886 and 0.071, respectively. Higher heterozygosity (20.8%) in Ramdasia reflects greater variation at the APOE locus. The APOE*E3 allele is found...... to be the highest (0.913) in Ramgarhia in comparison to forty-one populations of the world. A decreasing cline from south to north was evident for *E2 and *E4 allele frequencies (y = -0.002x + 0.141, r = 0.78 and y = -0.004x + 0.229, r = 0.83, respectively, and an increasing cline for the *E3 allele towards north...

  18. Apolipoproteine E en familiale dysbetalipoproteinemie

    NARCIS (Netherlands)

    Havekes, L.M.

    1989-01-01

    Familiale dysbèta-lipoproteïnemie (F.D.; type III hyperlipoproteïnemie volgens Frederickson) wordt gekenmerkt door een verhoogd plasmacholesterol- en triglyceridegehalte ten gevolge van een gestoorde opneming door de lever van de atherogene chylomicron- en V.L.D.L.-remnants. Voor de opneming van

  19. Apolipoprotein E genotype does not moderate the associations of depressive symptoms, neuroticism and allostatic load with cognitive ability and cognitive aging in the Lothian Birth Cohort 1936.

    Directory of Open Access Journals (Sweden)

    Zander Crook

    Full Text Available In this replication-and-extension study, we tested whether depressive symptoms, neuroticism, and allostatic load (multisystem physiological dysregulation were related to lower baseline cognitive ability and greater subsequent cognitive decline in older adults, and whether these relationships were moderated by the E4 allele of the apolipoprotein E (APOE gene. We also tested whether allostatic load mediated the relationships between neuroticism and cognitive outcomes.We used data from the Lothian Birth Cohort 1936 (n at Waves 1-3: 1,028 [M age = 69.5 y]; 820 [M duration since Wave 1 = 2.98 y]; 659 [M duration since Wave 1 = 6.74 y]. We fitted latent growth curve models of general cognitive ability (modeled using five cognitive tests with groups of APOE E4 non-carriers and carriers. In separate models, depressive symptoms, neuroticism, and allostatic load predicted baseline cognitive ability and subsequent cognitive decline. In addition, models tested whether allostatic load mediated relationships between neuroticism and cognitive outcomes.Baseline cognitive ability had small-to-moderate negative associations with depressive symptoms (β range = -0.20 to -0.17, neuroticism (β range = -0.27 to -0.23, and allostatic load (β range = -0.11 to 0.09. Greater cognitive decline was linked to baseline allostatic load (β range = -0.98 to -0.83 and depressive symptoms (β range = -1.00 to -0.88. However, APOE E4 allele possession did not moderate the relationships of depressive symptoms, neuroticism and allostatic load with cognitive ability and cognitive decline. Additionally, the associations of neuroticism with cognitive ability and cognitive decline were not mediated through allostatic load.Our results suggest that APOE E4 status does not moderate the relationships of depressive symptoms, neuroticism, and allostatic load with cognitive ability and cognitive decline in healthy older adults. The most notable positive finding in the current research was

  20. High ethanol and acetaldehyde impair spatial memory in mouse models: opposite effects of aldehyde dehydrogenase 2 and apolipoprotein E on memory.

    Science.gov (United States)

    Jamal, Mostofa; Ameno, Kiyoshi; Miki, Takanori; Tanaka, Naoko; Ono, Junichiro; Shirakami, Gotaro; Sultana, Ruby; Yu, Nakamura; Kinoshita, Hiroshi

    2012-05-01

    Aldehyde dehydrogenase 2 deficiency may directly contribute to excess acetaldehyde (AcH) accumulation after ethanol (EtOH) drinking and AcH mediates some of the behavioral effects of EtOH. Apolipoprotein E has been suggested to be involved in the alteration of attention and memory. We have chosen Aldh2-knockout (Aldh2-KO), ApoE-KO, and their wild-type (WT) control mice to examine the effects of EtOH and AcH on spatial memory and to compare the possible relationship between genetic deficiency and memory using two behavioral assessments. Mice were trained for 4 days, with EtOH (0.5, 1.0, 2.0 g/kg) being given intraperitoneally on day 4. A probe trial was given on day 5 in the non-EtOH state in the Morris water maze (MWM). The results showed that 2.0 g/kg EtOH increased errors, indicating memory impairment on the eight-arm radial maze (RAM) for all the mice studied. One gram per kilogram EtOH impaired the performance of Aldh2-KO and ApoE-KO mice, but not WT mice. We found similar effects of EtOH on the MWM performance, with 2.0 g/kg EtOH increasing the latencies. One gram per kilogram EtOH increased the latencies of Aldh2-KO and WT mice, but not ApoE-KO mice. The 2.0 g/kg EtOH-induced memory impairment in Aldh2-KO mice was greater, suggesting an AcH effect. Furthermore, time spent on the probe trial was shorter in mice that had previously received 2.0 g/kg EtOH. ApoE-KO mice learned more slowly, while Aldh2-KO mice learned more quickly. Both the RAM and MWM results suggest that high EtOH and AcH impair spatial memory in mice, while lower doses do not have consistent memory effects. In addition, we conclude that genetic differences might underlie some of EtOH's effects on memory. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. MicroRNA-27 Prevents Atherosclerosis by Suppressing Lipoprotein Lipase-Induced Lipid Accumulation and Inflammatory Response in Apolipoprotein E Knockout Mice.

    Directory of Open Access Journals (Sweden)

    Wei Xie

    Full Text Available Atherosclerotic lesions are lipometabolic disorder characterized by chronic progressive inflammation in arterial walls. Previous studies have shown that macrophage-derived lipoprotein lipase (LPL might be a key factor that promotes atherosclerosis by accelerating lipid accumulation and proinflammatory cytokine secretion. Increasing evidence indicates that microRNA-27 (miR-27 has beneficial effects on lipid metabolism and inflammatory response. However, it has not been fully understood whether miR-27 affects the expression of LPL and subsequent development of atherosclerosis in apolipoprotein E knockout (apoE KO mice. To address these questions and its potential mechanisms, oxidized low-density lipoprotein (ox-LDL-treated THP-1 macrophages were transfected with the miR-27 mimics/inhibitors and apoE KO mice fed high-fat diet were given a tail vein injection with miR-27 agomir/antagomir, followed by exploring the potential roles of miR-27. MiR-27 agomir significantly down-regulated LPL expression in aorta and peritoneal macrophages by western blot and real-time PCR analyses. We performed LPL activity assay in the culture media and found that miR-27 reduced LPL activity. ELISA showed that miR-27 reduced inflammatory response as analyzed in vitro and in vivo experiments. Our results showed that miR-27 had an inhibitory effect on the levels of lipid both in plasma and in peritoneal macrophages of apoE KO mice as examined by HPLC. Consistently, miR-27 suppressed the expression of scavenger receptors associated with lipid uptake in ox-LDL-treated THP-1 macrophages. In addition, transfection with LPL siRNA inhibited the miR-27 inhibitor-induced lipid accumulation and proinflammatory cytokines secretion in ox-LDL-treated THP-1 macrophages. Finally, systemic treatment revealed that miR-27 decreased aortic plaque size and lipid content in apoE KO mice. The present results provide evidence that a novel antiatherogenic role of miR-27 was closely related to

  2. Adverse Effects of the Apolipoprotein E ε4 Allele on Episodic Memory, Task Switching and Gray Matter Volume in Healthy Young Adults

    Directory of Open Access Journals (Sweden)

    Jianfei Nao

    2017-06-01

    Full Text Available Many studies have shown that healthy elderly subjects and patients with Alzheimer’s disease (AD who carry the apolipoprotein E (ApoE ε4 allele have worse cognitive function and more severe brain atrophy than non-carriers. However, it remains unclear whether this ApoE polymorphism leads to changes of cognition and brain morphology in healthy young adults. In this study, we used an established model to measure verbal episodic memory and core executive function (EF components (response inhibition, working memory and task switching in 32 ApoE ε4 carriers and 40 non-carriers between 20 years and 40 years of age. To do this, we carried out an adapted auditory verbal learning test and three computerized EF tasks. High-resolution head magnetic resonance scans were performed in all participants and voxel-based morphometry (VBM was used for image processing and analysis. Multivariate analysis of variance (ANOVA performed on memory measures showed that the overall verbal episodic memory of ApoE ε4 carriers was significantly worse than non-carriers (Wilk’s λ = 4.884, P = 0.004. No significant differences were detected in overall EF between the two groups. Post hoc analyses revealed group differences in terms of immediate recall, recognition and task switching, which favored non-carriers. VBM analysis showed gray matter (GM bilateral reductions in the medial and dorsolateral frontal, parietal and left temporal cortices in the carrier group relative to the non-carrier group, which were most significant in the bilateral anterior and middle cingulate gyri. However, these changes in GM volume were not directly associated with changes in cognitive function. Our data show that the ApoE ε4 allele is associated with poorer performance in verbal episodic memory and task switching, and a reduction in GM volume in healthy young adults, suggesting that the effects of ApoE ε4 upon cognition and brain morphology exist long before the possible occurrence of AD.

  3. Effects of an Aβ-antibody fragment on Aβ aggregation and astrocytic uptake are modulated by apolipoprotein E and J mimetic peptides.

    Directory of Open Access Journals (Sweden)

    Laia Montoliu-Gaya

    Full Text Available Aβ-Immunotherapy has long been studied in the treatment of Alzheimer's disease (AD, but not how other molecules involved in the disease can affect antibody performance. We previously designed an antibody fragment, scFv-h3D6, and showed that it precludes Aβ-induced cytotoxicity by withdrawing Aβ oligomers from the amyloid pathway towards a non-toxic, worm-like pathway. ScFv-h3D6 was effective at the behavioral, cellular, and molecular levels in the 3xTg-AD mouse model. Because scFv-h3D6 treatment restored apolipoprotein E (apoE and J (apoJ concentrations to non-pathological values, and Aβ internalization by glial cells was found to be decreased in the presence of these apolipoproteins, we now aimed to test the influence of scFv-h3D6 on Aβ aggregation and cellular uptake by primary human astrocytes in the presence of therapeutic apoE and apoJ mimetic peptides (MPs. Firstly, we demonstrated by CD and FTIR that the molecules used in this work were well folded. Next, interactions between apoE or apoJ-MP, scFv-h3D6 and Aβ were studied by CD. The conformational change induced by the interaction of Aβ with apoE-MP was much bigger than the induced with apoJ-MP, in line with the observed formation of protective worm-like fibrils by the scFv-h3D6/Aβ complex in the presence of apoJ-MP, but not of apoE-MP. ScFv-h3D6, apoJ-MP, and apoE-MP to a different extent reduced Aβ uptake by astrocytes, and apoE-MP partially interfered with the dramatic reduction by scFv-h3D6 while apoJ-MP had no effect on scFv-h3D6 action. As sustained Aβ uptake by astrocytes may impair their normal functions, and ultimately neuronal viability, this work shows another beneficence of scFv-h3D6 treatment, which is not further improved by the use of apoE or apoJ mimetic peptides.

  4. 2-Ethynylpyridine dimers

    DEFF Research Database (Denmark)

    Bakarić, Danijela; Spanget-Larsen, Jens

    2018-01-01

    are used to study possible 2-EP dimer structures as well as their distribution in an inert solvent such as tetrachloroethene. Experimentally, the ≡C–H stretching vibration of the 2-EPmonomer absorbs close to 3300 cm−1, whereas a broad band withmaximum around 3215 cm−1 emerges as the concentration rises...... model with counterpoise correction predict that the two most stable dimers are of the pi-stacked variety, closely followed by dimers with intermolecular ≡C–H···N hydrogen bonding; the predicted red shifts of the ≡C–H stretching wavenumbers due to hydrogen bonding are in the range 54 – 120 cm–1...

  5. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen

    1986-01-01

    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...... excitations are modulated by an interference term reflecting the distance between the magnetic ions within the dimers. The INS technique is particularly powerful for the study of effects like: temperature dependence of exchange, the role of biquadratic exchange, the combination of crystal-field and exchange...

  6. Dimers in nucleating vapors

    Science.gov (United States)

    Lushnikov, A. A.; Kulmala, M.

    1998-09-01

    The dimer stage of nucleation may affect considerably the rate of the nucleation process at high supersaturation of the nucleating vapor. Assuming that the dimer formation limits the nucleation rate, the kinetics of the particle formation-growth process is studied starting with the definition of dimers as bound states of two associating molecules. The partition function of dimer states is calculated by summing the Boltzmann factor over all classical bound states, and the equilibrium population of dimers is found for two types of intermolecular forces: the Lennard-Jones (LJ) and rectangular well+hard core (RW) potentials. The principle of detailed balance is used for calculating the evaporation rate of dimers. The kinetics of the particle formation-growth process is then investigated under the assumption that the trimers are stable with respect to evaporation and that the condensation rate is a power function of the particle mass. If the power exponent λ=n/(n+1) (n is a non-negative integer), the kinetics of the process is described by a finite set of moments of particle mass distribution. When the characteristic time of the particle formation by nucleation is much shorter than that of the condensational growth, n+2 universal functions of a nondimensional time define the kinetic process. These functions are calculated for λ=2/3 (gas-to-particle conversion in the free molecular regime) and λ=1/2 (formation of islands on surfaces).

  7. Adsorption of dimeric surfactants in lamellar silicates

    Energy Technology Data Exchange (ETDEWEB)

    Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2015-12-01

    Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  8. Age-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study.

    Directory of Open Access Journals (Sweden)

    Darren M Lipnicki

    2017-03-01

    Full Text Available The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4 carrier status were associated with decline.We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States, for a total of 42,170 individuals aged 54-105 y (42% male, including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2-16 assessment waves (median = 3 and a follow-up duration of 2-15 y. We analyzed standardized Mini-Mental State Examination (MMSE and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade (95% confidence interval [CI] [-0.35, -0.16], p < 0.001 for processing speed. Rates of decline accelerated slightly with age, with executive functioning showing the largest additional rate of decline with every further decade of age (-0.07 SD/decade, 95% CI [-0.10, -0.03], p = 0.002. There was a considerable degree of heterogeneity in the associations across cohorts, including a slightly faster decline (p = 0.021 on the MMSE for Asians (-0.20 SD/decade, 95% CI [-0.28, -0.12], p < 0.001 than for whites (-0.09 SD/decade, 95% CI [-0.16, -0.02], p = 0.009. Males declined on the MMSE at a slightly slower rate than females (difference = 0.023 SD/decade, 95% CI [0.011, 0

  9. Age-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study.

    Science.gov (United States)

    Lipnicki, Darren M; Crawford, John D; Dutta, Rajib; Thalamuthu, Anbupalam; Kochan, Nicole A; Andrews, Gavin; Lima-Costa, M Fernanda; Castro-Costa, Erico; Brayne, Carol; Matthews, Fiona E; Stephan, Blossom C M; Lipton, Richard B; Katz, Mindy J; Ritchie, Karen; Scali, Jacqueline; Ancelin, Marie-Laure; Scarmeas, Nikolaos; Yannakoulia, Mary; Dardiotis, Efthimios; Lam, Linda C W; Wong, Candy H Y; Fung, Ada W T; Guaita, Antonio; Vaccaro, Roberta; Davin, Annalisa; Kim, Ki Woong; Han, Ji Won; Kim, Tae Hui; Anstey, Kaarin J; Cherbuin, Nicolas; Butterworth, Peter; Scazufca, Marcia; Kumagai, Shuzo; Chen, Sanmei; Narazaki, Kenji; Ng, Tze Pin; Gao, Qi; Reppermund, Simone; Brodaty, Henry; Lobo, Antonio; Lopez-Anton, Raúl; Santabárbara, Javier; Sachdev, Perminder S

    2017-03-01

    The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4) carrier status were associated with decline. We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States), for a total of 42,170 individuals aged 54-105 y (42% male), including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2-16 assessment waves (median = 3) and a follow-up duration of 2-15 y. We analyzed standardized Mini-Mental State Examination (MMSE) and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade) (95% confidence interval [CI] [-0.35, -0.16], p education was associated with a rate of decline slightly slower for the MMSE (0.004 SD/decade less, 95% CI [0.002, 0.006], p = 0.001), but slightly faster for language (-0.007 SD/decade more, 95% CI [-0.011, -0.003], p = 0.001). APOE*4 carriers declined slightly more rapidly than non-carriers on most cognitive measures, with processing speed showing the greatest difference (-0.08 SD/decade, 95% CI [-0.15, -0.01], p = 0.019). The same overall pattern of results was found when analyses were repeated with baseline dementia cases excluded. We used only one test to represent cognitive domains, and though a prototypical one, we

  10. Association of Brain Amyloid-β With Slow Gait in Elderly Individuals Without Dementia: Influence of Cognition and Apolipoprotein E ε4 Genotype.

    Science.gov (United States)

    Nadkarni, Neelesh K; Perera, Subashan; Snitz, Beth E; Mathis, Chester A; Price, Julie; Williamson, Jeff D; DeKosky, Steven T; Klunk, William E; Lopez, Oscar L

    2017-01-01

    Motor slowing appears in preclinical Alzheimer disease (AD), progresses with AD progression, and is associated with AD pathologic findings at autopsy. Whether amyloid-β (Aβ) is associated with gait speed in elderly individuals without dementia and whether cognition and apolipoprotein E ε4 (APOE ε4) influence this association remain unknown. To examine the association between Aβ and gait speed in elderly individuals without dementia and to study the influence of cognition and APOE ε4 status on this association. This cross-sectional analysis included 183 elderly individuals without dementia, including a cognitively normal (CN) subsample of 144 adults, enrolled in the Ginkgo Evaluation of Memory study at a university center from January 1, 2000, through December 31, 2009, and enrolled in a follow-up substudy a mean (SD) of 10 (3) months after the initial study closeout. Data analysis was performed from October 1, 2015, to June 1, 2016. We assessed cerebral Aβ on Pittsburgh Compound B (PiB) positron emission tomography, gait speed over 4.57 m (15 ft), and cognition on the Mini-Mental State Examination and Trail Making Test Parts A and B. We grouped participants into high Aβ (PiB+) and low Aβ (PiB-) groups on standardized global PiB cutoffs and examined group differences. We studied the influence of cognition and APOE ε4 on the global and regional associations between gait speed and Aβ in the whole sample and the CN subsample. Among the 183 study participants, mean (SD) age was 85.5 (3) years, 76 were women (41.5%), and 177 were white (96.7%). The PiB+ individuals were comparable to the PiB- individuals on demographics, comorbidities, cognition, hippocampal volume, and small-vessel disease but not on gait speed (0.85 vs 0.92 m/s, P = .01) or proportion of APOE ε4 carriers (29 [29.0%] vs 5 [6.0%], P gait withstood adjustment for covariates (β = -0.068, P = .03 and β = -0.074, P = .04, respectively); however, this association was

  11. Apolipoprotein E4 and Alzheimer's disease in São Paulo - Brazil Apolipoproteina E 4 e doença de Alzheimer em São Paulo - Brasil

    Directory of Open Access Journals (Sweden)

    Osvaldo P. Almeida

    1997-01-01

    Full Text Available Several recently published studies showed the existence of an association between the allele ε4 of the apolipoprotein E and Alzheimer's disease (AD in developed countries. We examined this association in 55 patients with possible or probable AD and 56 elderly controls referred to outpatient clinics at the "Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo" and "Centro de Saúde Escola da Faculdade de Saúde Pública da Universidade de São Paulo". The allele ε4 was significantly more frequent among patients than controls (20.9% vs 8.9%, p=0.038. Thirty-six percent of the cases presented with at least one allele ε4 compared with only 17.9% of the controls (p=0.027. The presence of at least one ε4 allele increased by 2.63 times the risk of subjects being diagnosed as suffering from AD. All three ε4ε4 patients were male and had a pre-senile onset of the disease. There was no significant difference between senile and pre-senile cases (41.9% vs 29.2%, p=0.326 nor between men and women (36.0% vs 36.7%, p=0.959 regarding their risk of being ε4. The age at onset of symptoms did not differ among the different genotype groups, although ε4ε4 cases showed a consistent trend for earlier onset. When only patients with the diagnosis of "probable AD" were included in the analysis (n=43, we observed that 22.1% of the alleles were e4, a rate that was significantly higher than the 8.9% of controls (p=0.024. This study supports the association between the presence of the ε4 allele and AD and extend this finding to Brazilian patients. Nonetheless, the presence of this allele is not necessary nor sufficient for the development of the disease and it is possible that its contribution to the pathogenesis of the disorder depends on the subject's ethnic group.Vários estudos publicados durante os últimos dois anos demonstraram a existência de uma forte associação entre o alelo ε4 da apolipoproteina E e a doença de Alzheimer (AD

  12. A Novel Dimer of α-Tocopherol

    Directory of Open Access Journals (Sweden)

    Anjan Patel

    2008-01-01

    Full Text Available Decomposition of the complex 4, formed between the α-tocopherol ortho-quinone methide (2 and NMMO, by fast heating from −78∘C to 70∘C in inert solvents produces a novel α-tocopherol dimer with 6H,12H-dibenzo[b,f][1,5]dioxocine structure (5 which—in contrast to the well-known spiro-dimer of α-tocopherol (3—is symmetrical. This is the first example of a direct reaction of the highly transient zwitterionic, aromatic precursor 2a in the formation of the ortho-quinone methide 2.

  13. Selective amine catalysed steroidal dimerization

    Indian Academy of Sciences (India)

    steroid dimers in which carbon atoms comprise a ben- zene nucleus.6 A standard colour test for the presence of cholesterol is the formation of a green colour in concentrated sulphuric acid, and this was shown to be due to a polyenyl steroidal dimer carbocation.7–9 Many dimeric and oligomeric steroids exhibit interesting.

  14. Association between polymorphisms of apolipoprotein E, bone mineral density of the lower forearm, quantitative ultrasound of the calcaneus and osteoporotic fractures in postmenopausal women with hip or lower forearm fracture

    DEFF Research Database (Denmark)

    Sennels, Henriette Pia; Sand, J C; Madsen, B

    2003-01-01

    are contradictory. The aim of this study was to examine the association between polymorphisms of APOE, BMD of the lower forearm, quantitative ultrasound of the calcaneus and osteoporotic fractures in a population of postmenopausal women with hip or lower forearm fractures admitted to a department of orthopaedic......A genetic contribution to the development of osteoporosis is well documented. Although the association between the common allelic variation of apolipoprotein E (APOE), fracture risk, bone loss and bone mineral density (BMD) has been examined in several studies, the results of these investigations...... surgery and age-matched controls from the population register. The APOE genotypes of 327 women were studied: 73 with lower forearm fractures, 43 with hip fractures and 211 age-matched controls. The participants were not receiving antiosteoporotic treatment. Polymerase chain reaction restriction fragment...

  15. Dimerization of Protegrin-1 in Different Environments

    Directory of Open Access Journals (Sweden)

    Yiannis N. Kaznessis

    2010-09-01

    Full Text Available The dimerization of the cationic β-hairpin antimicrobial peptide protegrin-1 (PG1 is investigated in three different environments: water, the surface of a lipid bilayer membrane, and the core of the membrane. PG1 is known to kill bacteria by forming oligomeric membrane pores, which permeabilize the cells. PG1 dimers are found in two distinct, parallel and antiparallel, conformations, known as important intermediate structural units of the active pore oligomers. What is not clear is the sequence of events from PG1 monomers in solution to pores inside membranes. The step we focus on in this work is the dimerization of PG1. In particular, we are interested in determining where PG1 dimerization is most favorable. We use extensive molecular dynamics simulations to determine the potential of mean force as a function of distance between two PG1 monomers in the aqueous subphase, the surface of model lipid bilayers and the interior of these bilayers. We investigate the two known distinct modes of dimerization that result in either a parallel or an antiparallel β-sheet orientation. The model bilayer membranes are composed of anionic palmitoyl-oleoyl-phosphatidylglycerol (POPG and palmitoyl-oleoyl-phosphatidylethanolamine (POPE in a 1:3 ratio (POPG:POPE. We find the parallel PG1 dimer association to be more favorable than the antiparallel one in water and inside the membrane. However, we observe that the antiparallel PG1 β-sheet dimer conformation is somewhat more stable than the parallel dimer association at the surface of the membrane. We explore the role of hydrogen bonds and ionic bridges in peptide dimerization in the three environments. Detailed knowledge of how networks of ionic bridges and hydrogen bonds contribute to peptide stability is essential for the purpose of understanding the mechanism of action for membrane-active peptides as well as for designing peptides which can modulate membrane properties. The findings are suggestive of the

  16. Precise control of quantum dot location within the P3HT-b-P2VP/QD nanowires formed by crystallization-driven 1D growth of hybrid dimeric seeds.

    Science.gov (United States)

    Kim, Yong-Jae; Cho, Chul-Hee; Paek, Kwanyeol; Jo, Mijung; Park, Mi-kyoung; Lee, Na-Eun; Kim, Youn-joong; Kim, Bumjoon J; Lee, Eunji

    2014-02-19

    Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3-hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs. In particular, the location of the QD arrays within the single strand of P3HT-b-P2VP can be controlled precisely by manipulating the regioregularity (RR) values of P3HT block and the relative lengths of P2VP block. The degree of coaxiality of the QD arrays was shown to depend on the coplanarity of the thiophene rings of P3HT block, which can be controlled by the RR value of P3HT block. In addition, the location of QDs could be regulated at the specific-local site of P3HT-b-P2VP NW according to the surface characteristics of QDs. As an example, the comparison of two different QDs coated with hydrophobic alkyl-terminated and hydroxyl-terminated molecules, respectively, is used to elucidate the effect of the surface properties of QDs on their nanolocation in the NW.

  17. Glycine transporter dimers: evidence for occurrence in the plasma membrane

    DEFF Research Database (Denmark)

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette

    2008-01-01

    by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization......Different Na(+)/Cl(-)-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma...

  18. End binding proteins are obligatory dimers.

    Directory of Open Access Journals (Sweden)

    Indrani Sen

    Full Text Available End binding (EB proteins are responsible for the recruitment of an array of microtubule plus-end tracking proteins (+TIPs to growing microtubules ends. EBs encompass an N-terminal calponin homology domain that confers microtubule tip tracking activity to the protein. The C-terminal domain of EBs contains a coiled coil that mediates the parallel dimerization of EB monomers. This part of the protein is also responsible for partner binding. While dimerization is not essential for microtubule tip tracking by EBs it is a prerequisite for +TIP partner binding. The concentration of EBs in cells has been estimated to be in the range of hundreds of nanomoles. In contrast, in in vitro single molecule experiments EB concentrations of subnanomoles are employed. From a mechanistic point of view it is important to assess the oligomerization state of EBs at physiologically and experimentally relevant protein concentrations, in particular if the goal of a study is to model the behavior of EB-dependent dynamic +TIP networks. Here we have determined the stability of the EB1 and EB3 dimers using multi-angle light scattering and fluorescence analytical ultracentrifugation. We show that these EBs form stable dimers and do not dissociate even at very low nanomolar concentrations. The dimers remained stable at both room temperature as well as at the physiologically relevant temperature of 37°C. Together, our results reveal that EBs are obligatory dimers, a conclusion that has implications for the mechanistic understanding of these key proteins involved in the orchestration of dynamic protein networks at growing microtubule ends.

  19. Family C 7TM receptor dimerization and activation

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Sheikh, Søren P; Hansen, Jakob Lerche

    2006-01-01

    The family C seven transmembrane (7TM) receptors constitutes a small and especially well characterized subfamily of the large 7TM receptor superfamily. Approximately 50% of current prescription drugs target 7TM receptors, this biologically important family represents the largest class of drug......-targets today. It is well established that family C 7TM receptors form homo- or hetero-dimers on the cell surface of living cells. The large extra-cellular domains (ECD) have been crystallized as a dimer in the presence and absence of agonist. Upon agonist binding, the dimeric ECD undergoes large conformational...... changes that lead to receptor activation. Despite extensive studies of the receptor transmembrane domain, several key features, including the exact organization of the complete receptor dimer, the sequence of events leading to receptor activation, and the functional significance of dimerization, have yet...

  20. Alkane dimers interaction

    DEFF Research Database (Denmark)

    Ferrighi, Lara; Madsen, Georg Kent Hellerup; Hammer, Bjørk

    2010-01-01

    The interaction energies of a series of n-alkane dimers, from methane to decane, have been investigated with Density Functional Theory (DFT), using the MGGA-M06-L density functional. The results are compared both to the available wavefunction-based values as well as to dispersion corrected DFT...... values. The MGGA-M06-L density functional is a semi-local functional designed and has proven to provide accurate estimates of dispersion interactions for several systems at moderate computational cost. In the present application, it reproduces the trends obtained by the more expensive wavefunction...

  1. Spectroscopic Observation of CS_2 Dimer

    Science.gov (United States)

    Rezaei, M.; Oliaee, J. Norooz; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2011-06-01

    Infrared spectra of the CS_2 dimer are observed in the region of the CS_2 ν_3 fundamental band (˜ 1535 Cm-1) using a tuneable diode laser spectrometer. The weakly-bound complex is formed in a pulsed supersonic slit-jet expansion of a dilute gas mixture of carbon disulfide in helium. Contrary to the planar slipped-parallel geometry previously observed for (CO_2)_2, (N_2O)_2 and (OCS)_2, the CS_2 dimer exhibits a cross-shaped structure with D2d symmetry. Two bands were observed and analyzed: the fundamental (C-S asymmetric stretch) and a combination involving this mode plus an intermolecular vibration. In both cases, the rotational structure corresponds to a perpendicular (Δ K = ± 1) band of a symmetric rotor molecule. The intermolecular center of mass separation (C-C distance) is determined to be 3.539(7) {Å}. Thanks to symmetry, this is the only parameter required to characterize the structure, if the monomer geometry is assumed to remain unchanged in the dimer. From the band centers of the fundamental and combination band an intermolecular frequency of 10.96 Cm-1 is obtained, which we assign as the torsional bending mode. This constitutes the first high resolution spectroscopic investigation of CS_2 dimer.

  2. Subsurface dimerization in III-V semiconductor (001) surfaces

    DEFF Research Database (Denmark)

    Kumpf, C.; Marks, L.D.; Ellis, D.

    2001-01-01

    We present the atomic structure of the c(8 X 2) reconstructions of InSb-, InAs-, and GaAs-(001) surfaces as determined by surface x-ray diffraction using direct methods. Contrary to common belief, group III dimers are not prominent on the surface, instead subsurface dimerization of group m atoms...... takes place in the second bilayer, accompanied by a major rearrangement of the surface atoms above the dimers to form linear arrays. By varying the occupancies of four surface sites the (001)-c(8 X 2) reconstructions of III-V semiconductors can be described in a unified model....

  3. Selective amine catalysed steroidal dimerization

    Indian Academy of Sciences (India)

    of cholesterol is the formation of a green colour in concentrated sulphuric acid, and this was shown to be due to a polyenyl steroidal dimer carbocation.7–9 Many dimeric and oligomeric steroids exhibit interesting micellular, detergent and liquid crystal behaviour.10,11. Most of the steroidal dimmers are also well-known.

  4. Thymine Dimerization in DNA is an Ultrafast Photoreaction

    OpenAIRE

    Schreier, Wolfgang J.; Schrader, Tobias E.; Koller, Florian O.; Gilch, Peter; Crespo-Hernández, Carlos E.; Swaminathan, Vijay N.; Carell, Thomas; Zinth, Wolfgang; Kohler, Bern

    2007-01-01

    Femtosecond time-resolved infrared spectroscopy is used to study the formation of cyclobutane dimers in the all-thymine oligonucleotide (dT)18 by ultraviolet light at 272 nanometers. The appearance of marker bands in time-resolved spectra indicate that dimers are fully formed ∼1 picosecond after ultraviolet excitation. The ultrafast appearance of this mutagenic photolesion points to an approximately barrierless excited-state reaction for bases that are properly oriented at the instant of ligh...

  5. Advances in Chemistry and Pharmacology of Triterpenoid Synthetic Dimers.

    Science.gov (United States)

    Bednarczyk-Cwynar, Barbara; Günther, Andrzej

    2017-01-01

    This review focuses on advances in chemistry and pharmacology of synthetic triterpenoid dimers, obtained from natural compounds. Synthetic triterpenoid dimers are divided into specific subgroups based on the structure of main triterpenoid monomeric skeleton. Synthetic triterpenoid derivatives of dimeric structure can be obtained through the covalent linkage of the C-3 hydroxyl or another group, via the C-2 atom or the C-17 carboxyl group (mainly anhydrides, amides or esters). Some triterpenes can undergo chemical transformations leading to the formation of cyclic dimers or other types of dimers. Most of the obtained triterpenoid dimers have been subjected to pharmacological tests evaluating their biological activity, mainly antiviral (HIV-1 RT, HCVpp, VSVpp, HIV-RT-C8166-CCR5), cytotoxic (against e.g. 388, MCF-7, SF-268, NCIH460, KM20L2, DU-145, Hep-G2, A549, BGC-823, PC-3), anti-inflammatory (iNOS, RAW 264.7) and antidiabetic (RMGPa inhibition). The authors also reported the ability of some of the obtained cyclic triterpenoid dimers to recognize anions and to form self-assembled structures. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  6. Association between ε2/3/4, promoter polymorphism (-491A/T, -427T/C, and -219T/G) at the apolipoprotein E gene, and mental retardation in children from an iodine deficiency area, China.

    Science.gov (United States)

    Li, Jun; Zhang, Fuchang; Wang, Yunliang; Wang, Yan; Qin, Wei; Xing, Qinghe; Qian, Xueqing; Guo, Tingwei; Gao, Xiaocai; He, Lin; Gao, Jianjun

    2014-01-01

    Several common single-nucleotide polymorphisms (SNPs) at apolipoprotein E (ApoE) have been linked with late onset sporadic Alzheimer's disease and declining normative cognitive ability in elder people, but we are unclear about their relationship with cognition in children. We studied -491A/T, -427T/C, and -219G/T promoter polymorphisms and ε2/ε3/ε4 at ApoE among children with mental retardation (MR, n = 130), borderline MR (n = 124), and controls (n = 334) from an iodine deficiency area in China. The allelic and genotypic distribution of individual locus did not significantly differ among three groups with Mantel-Haenszel χ (2) test (P > 0.05). However, frequencies of haplotype of -491A/-427T/-219T/ε4 were distributed as MR > borderline MR > controls (P uncorrected = 0.004), indicating that the presence of this haplotype may increase the risk of disease. In this large population-based study in children, we did not find any significant association between single locus of the four common ApoE polymorphisms (-491A/T, -427T/C, -219T/G, and ε2/3/4) and MR or borderline MR. However, we found that the presence of ATTε4 haplotype was associated with an increased risk of MR and borderline MR. Our present work may help enlarge our knowledge of the cognitive role of ApoE across the lifespan and the mechanisms of human cognition.

  7. Quantitative analysis of senile plaques in Alzheimer disease: observation of log-normal size distribution and molecular epidemiology of differences associated with apolipoprotein E genotype and trisomy 21 (Down syndrome).

    Science.gov (United States)

    Hyman, B T; West, H L; Rebeck, G W; Buldyrev, S V; Mantegna, R N; Ukleja, M; Havlin, S; Stanley, H E

    1995-04-11

    The discovery that the epsilon 4 allele of the apolipoprotein E (apoE) gene is a putative risk factor for Alzheimer disease (AD) in the general population has highlighted the role of genetic influences in this extremely common and disabling illness. It has long been recognized that another genetic abnormality, trisomy 21 (Down syndrome), is associated with early and severe development of AD neuropathological lesions. It remains a challenge, however, to understand how these facts relate to the pathological changes in the brains of AD patients. We used computerized image analysis to examine the size distribution of one of the characteristic neuropathological lesions in AD, deposits of A beta peptide in senile plaques (SPs). Surprisingly, we find that a log-normal distribution fits the SP size distribution quite well, motivating a porous model of SP morphogenesis. We then analyzed SP size distribution curves in genotypically defined subgroups of AD patients. The data demonstrate that both apoE epsilon 4/AD and trisomy 21/AD lead to increased amyloid deposition, but by apparently different mechanisms. The size distribution curve is shifted toward larger plaques in trisomy 21/AD, probably reflecting increased A beta production. In apoE epsilon 4/AD, the size distribution is unchanged but the number of SP is increased compared to apoE epsilon 3, suggesting increased probability of SP initiation. These results demonstrate that subgroups of AD patients defined on the basis of molecular characteristics have quantitatively different neuropathological phenotypes.

  8. Targeted delivery of rosmarinic acid across the blood-brain barrier for neuronal rescue using polyacrylamide-chitosan-poly(lactide-co-glycolide) nanoparticles with surface cross-reacting material 197 and apolipoprotein E.

    Science.gov (United States)

    Kuo, Yung-Chih; Rajesh, Rajendiran

    2017-08-07

    Rosmarinic acid-loaded polyacrylamide-chitosan-poly(lactide-co-glycolide) nanoparticles (RA-PAAM-CH-PLGA NPs) were grafted with cross-reacting material 197 (CRM197) and apolipoprotein E (ApoE) for targeting of the blood-brain barrier (BBB) and rescuing degenerated neurons. The polymeric nanocarriers were prepared by microemulsion, solvent diffusion, grafting, and surface modification, and CRM197-ApoE-RA-PAAM-CH-PLGA NPs were used to treat human brain-microvascular endothelial cells, RWA264.7 cells, and Aβ-insulted SK-N-MC cells. Experimental results revealed that an increase in the weight percentage of PAAM decreased the particle size, zeta potential, and grafting efficiency of CRM197 and ApoE. In addition, surface DSPE-PEG(2000) could protect CRM197-ApoE-RA-PAAM-CH-PLGA NPs against uptake by RWA264.7 cells. An increase in the concentration of CRM197 and ApoE decreased the transendothelial electrical resistance and increased the ability of propidium iodide and RA to cross the BBB. The order in the viability of apoptotic SK-N-MC cells was CRM197-ApoE-RA-PAAM-CH-PLGA NPs > CRM197-RA-PAAM-CH-PLGA NPs > RA. Thus, CRM197-ApoE-RA-PAAM-CH-PLGA NPs can be a promising formulation to deliver RA to Aβ-insulted neurons in the pharmacotherapy of Alzheimer's disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Gender, apolipoprotein E genotype, and mesial temporal atrophy: 2-year follow-up in patients with stable mild cognitive impairment and with progression from mild cognitive impairment to Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Spampinato, M.V.; Patrick, K.E.; Collins, H. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Langdon, B.R. [Medical University of South Carolina, Department of Internal Medicine, Charleston, SC (United States); Parker, R.O. [Vanderbilt University, Department of Anesthesiology, Nashville, TN (United States); Pravata' , E. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Ospedale Regionale di Lugano, Department of Neuroradiology, Neurocenter of Southern Switzerland, Lugano (Switzerland); Collaboration: For the Alzheimer' s Disease Neuroimaging Initiative

    2016-11-15

    This study aimed to examine the relationship between gender, apolipoprotein E (APOE) genotype, and mesial temporal atrophy in mild cognitive impairment (MCI) with and without progression to Alzheimer's disease (AD). We evaluated 236 MCI patients with (n = 121) and without (n = 115) AD progression. Longitudinal MRI-based hippocampal volumes (HV) and entorhinal cortex (ERC) thickness were obtained. The Clinical Dementia Rating Sum of Boxes (CDR-SB) score was used to assess disease severity. We found a significant effect of APOE, gender, and clinical course (stable MCI versus MCI-AD progression) on HV. There was a significant effect of clinical course and APOE, but not gender, on ERC. Baseline HV and APOE4 status predicted MCI-AD progression in women. Baseline ERC and APOE4 status predicted MCI-AD progression in men. There were significant differences in CDR-SB scores between patients with and without MCI-AD progression, but not between males and females, or APOE4 carriers and non-carriers. HV, but not ERC, is strongly influenced by gender in MCI. The effects of gender and APOE4 on neuroimaging biomarkers have potentially important implications in the prediction of MCI-AD progression and should be taken into account in clinical trials. (orig.)

  10. Acetic acid dimers in a nitrogen matrix: Observation of structures containing the higher-energy conformer

    Science.gov (United States)

    Lopes, Susy; Domanskaya, Alexandra V.; Räsänen, Markku; Khriachtchev, Leonid; Fausto, Rui

    2015-09-01

    Acetic acid (AA) dimers are studied experimentally by infrared spectroscopy in a N2 matrix and theoretically at the MP2/6-311++G(2d,2p) level of approximation. This work is focused on the first preparation and characterization of structures containing the higher-energy (cis) conformer of AA. Nine trans-trans, fourteen trans-cis, and six cis-cis dimers are theoretically predicted. Five trans-trans and a number of trans-cis dimers are identified in the experiments, but no indication of cis-cis dimers is found. Two trans-trans dimers and the trans-cis dimers are reported for the first time. One trans-cis dimer is prepared by selective vibrational excitation of the structurally related trans-trans dimer, which converts one of the trans subunits to the cis form. Several trans-cis dimers are obtained by annealing of a matrix containing both trans and cis monomers of AA. Tunneling-induced conversion of the trans-cis dimers into trans-trans forms (including two new trans-trans forms) is observed at low temperatures.

  11. Enriched environment reduces apolipoprotein E (ApoE) in reactive astrocytes and attenuates inflammation of the peri-infarct tissue after experimental stroke

    DEFF Research Database (Denmark)

    Ruscher, Karsten; Johannesson, Emelie; Brugiere, Elena

    2009-01-01

    that differentially improve recovery after occlusion of the middle cerebral artery occlusion (MCAO). We found that after MCAO the ApoE levels increased in the injured hemisphere over a 30 days recovery period. The exception was a proximal narrow peri-infarct rim, in which ApoE was solely localized in S100beta...... lower in animals housed in an enriched environment. We propose that during the subacute phase after experimental stroke a zone for tissue reorganization with low cellular ApoE levels is formed. We conclude that the strong sensori-motor stimulation provided by enriched housing conditions mitigates...

  12. Observation of an aromatic radical anion dimer: (C10F8)2 sm-bullet -

    International Nuclear Information System (INIS)

    Werst, D.W.

    1994-01-01

    Radical cation dimers are observed for many alkenes and aromatic hydrocarbons as products of the reaction between monomer radical cation and neutral molecule. In most cases, the dimer radical anions, formed via reaction of the monomer radical anion with a neutral molecule, have not been observed. Here we report the observation of the dimer radical anion of octafluoronaphthalene, formed by reaction of C 10 F 8 ·- with the neutral parent molecules in nonpolar solvents following pulse radiolysis. Both monomer and dimer ions have been characterized by EPR spectra obtained by the time-resolved fluorescence-detected magnetic resonance

  13. MspA nanopores from subunit dimers.

    Directory of Open Access Journals (Sweden)

    Mikhail Pavlenok

    Full Text Available Mycobacterium smegmatis porin A (MspA forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated that the peptide linkers did not prohibit correct folding and localization of MspA. However, expression levels were reduced by 10-fold compared to wild-type MspA. MspA is ideal for nanopore sequencing due to its unique pore geometry and its robustness. To assess the usefulness of MspA made from dimeric subunits for DNA sequencing, we linked two M1-MspA monomers, whose constriction zones were modified to enable DNA translocation. Lipid bilayer experiments demonstrated that this construct also formed functional channels. Voltage gating of MspA pores made from M1 monomers and M1-M1 dimers was identical indicating similar structural and dynamic channel properties. Glucose uptake in M. smegmatis cells lacking porins was restored by expressing the dimeric mspA M1 gene indicating correct folding and localization of M1-M1 pores in their native membrane. Single-stranded DNA hairpins produced identical ionic current blockades in pores made from monomers and subunit dimers demonstrating that M1-M1 pores are suitable for DNA sequencing. This study provides the proof of principle that production of single-chain MspA pores in M. smegmatis is feasible and paves the way for generating MspA pores with altered stoichiometries. Subunit dimers enable better control of the chemical and physical properties of the constriction zone of MspA. This approach will be valuable both in understanding transport across the outer membrane in mycobacteria and in tailoring MspA for nanopore

  14. Synthesis and antimicrobial activity of the symmetric dimeric form of Temporin A based on 3-N,N-di(3-aminopropyl)amino propanoic acid as the branching unit.

    Science.gov (United States)

    Hujakka, H; Ratilainen, J; Korjamo, T; Lankinen, H; Kuusela, P; Santa, H; Laatikainen, R; Närvänen, A

    2001-06-01

    Dimeric derivative of antimicrobial peptide amide Temporin A (TA) was synthesized by using a new branching unit 3-N,N-di(3-aminopropyl)amino propanoic acid (DAPPA), which allows building of the parallelly symmetric alpha-helical structures. Antimicrobial effect of the original peptide amide, its monomeric carboxy (TAc) and novel dimeric (TAd) analogues were tested against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). Both TA and TAd completely inhibited the growth of S. aureus at the concentrations of 5 and 10 microM, respectively, whereas TAc did not show any inhibitory activity. The activities of TAc, TA and TAd correlate directly with the net charges of the molecules, +1, +2 and +4, respectively. Interestingly, TAd displayed antibacterial effect against E. coli at a concentration of 10 microM, where as monomeric TA did not show any activity at concentration as high as 20 microM. The results indicate that the novel structural modification improves the antibacterial properties of Temporin A especially towards Gram-negative bacteria.

  15. Two Lung Cancer Development-Related Genes, Forkhead Box M1 (FOXM1) and Apolipoprotein E (APOE), are overexpressed in Bronchial of Patients after Long-Term Exposure to Sulfur Mustard.

    Science.gov (United States)

    Tahmasbpour, Eisa; Ghanei, Mostafa; Panahi, Yunes

    2017-01-01

    Sulfur mustard (SM) is a strong alkylating and mutagenic compound that targets human airway system. We considered the expression of Forkhead box M1 ( FOXM1 ) and apolipoprotein E ( APOE ) genes, which are responsible for cell proliferation, differentiation, tumorigenesis, and increased risk of lung cancer, in the lung bronchial tissue of patients exposed to SM. After performing pulmonary functional tests (PFTs), 11 human subjects (five controls and six SM-exposed patients) were entered in this study. Total RNA were extracted from all biopsy samples and then cDNA was synthesised for each specimen using RT-PCR. Changes in gene expression were measured using a RT 2 Profiler ™PCR Array. PFTs have demonstrated more obstructive and restrictive spirometric patterns among patients compared to the controls. A higher expression was recorded for both examined genes in bronchial of SM-exposed patients. Expression of FOXM1 and APOE genes in bronchial of the patients was significantly ( p < 0.001) overexpressed by 14.8316 and 3.9504-folds, respectively. Mustard lungs were associated with increased expression of FOXM1 and APOE genes, which suggests an increased risk of lung cancer among these patients. Since FOXM1 and APOE are considered as oxidative stress responsive genes, we speculate that increased expression of these genes is more likely linked to overproduction of reactive oxygen species (ROS) and oxidative stress (OS) in mustard lungs. Further studies are required at protein level among SM-exposed patients with lung cancer to use these genes as lung cancer biomarkers among these patients.

  16. Dimerization of 3He in 3He-4He mixture films

    International Nuclear Information System (INIS)

    Bashkin, E.

    1994-01-01

    3 He atoms dissolved in superfluid 4 He may form dimers ( 3 He) 2 in two-dimensional geometries. Dimer formation is studied in films of dilute 3 He- 4 He mixture. After designing a schematic 3 He- 3 He interaction potential, the dimer binding energy is calculated for various substrates. It is shown that 3 He impurity states localized near the substrate give rise to the highest magnitudes of the binding energy. (author). 32 refs., 6 figs.,; 1 tab

  17. A potential new, stable state of the E-cadherin strand-swapped dimer in solution.

    Science.gov (United States)

    Schumann-Gillett, Alexandra; Mark, Alan E; Deplazes, Evelyne; O'Mara, Megan L

    2018-01-01

    E-cadherin is a transmembrane glycoprotein that facilitates inter-cellular adhesion in the epithelium. The ectodomain of the native structure is comprised of five repeated immunoglobulin-like domains. All E-cadherin crystal structures show the protein in one of three alternative conformations: a monomer, a strand-swapped trans homodimer and the so-called X-dimer, which is proposed to be a kinetic intermediate to forming the strand-swapped trans homodimer. However, previous studies have indicated that even once the trans strand-swapped dimer is formed, the complex is highly dynamic and the E-cadherin monomers may reorient relative to each other. Here, molecular dynamics simulations have been used to investigate the stability and conformational flexibility of the human E-cadherin trans strand-swapped dimer. In four independent, 100 ns simulations, the dimer moved away from the starting structure and converged to a previously unreported structure, which we call the Y-dimer. The Y-dimer was present for over 90% of the combined simulation time, suggesting that it represents a stable conformation of the E-cadherin dimer in solution. The Y-dimer conformation is stabilised by interactions present in both the trans strand-swapped dimer and X-dimer crystal structures, as well as additional interactions not found in any E-cadherin dimer crystal structures. The Y-dimer represents a previously unreported, stable conformation of the human E-cadherin trans strand-swapped dimer and suggests that the available crystal structures do not fully capture the conformations that the human E-cadherin trans homodimer adopts in solution.

  18. Short lived maleimide triplet dimers. Kinetics and consequences

    International Nuclear Information System (INIS)

    Von Sonntag, J.

    2002-01-01

    Complete text of publication follows. The photochemistry of maleimide in non-aqueous solution is governed by the coexistence of two different triplet states, the keto triplet and a dimer triplet. This biradical is formed in the reaction of the keto triplet adding to the double bond of a ground state maleimide, in competition with electron transfer, (k 3 MI+MI = 2.6 x 10 9 dm 3 mol -1 s -1 ). Its spectrum is identical with that of the maleimide H-adduct radical (λ max = 370 ... 380 nm, broad, λ max = 255 nm, narrow, λ min = 290 nm). Its lifetime is 110 ns. While protolysis is confined to maleimide and aqueous solutions, the dimer triplet is found in acetonitrile as well. Dimer triplet formation is also observed with N-ethylmaleimide. Multi-wavelength 'global' analysis of the time profiles allowed us to separate the transient spectra and kinetics of the monomer and dimer triplet. The cyclobutane dimer yield (determined by GC) is independent of maleimide concentration. This proves that the dimer triplet does not contribute significantly to the initiation of a free-radical polymerisation. Time-dependent Hartree-Fock calculations agree with the experimental data and further confirm the proposed mechanisms

  19. Glycine transporter dimers: evidence for occurrence in the plasma membrane.

    Science.gov (United States)

    Bartholomäus, Ingo; Milan-Lobo, Laura; Nicke, Annette; Dutertre, Sébastien; Hastrup, Hanne; Jha, Alok; Gether, Ulrik; Sitte, Harald H; Betz, Heinrich; Eulenburg, Volker

    2008-04-18

    Different Na(+)/Cl(-)-dependent neurotransmitter transporters of the SLC6a family have been shown to form dimers or oligomers in both intracellular compartments and at the cell surface. In contrast, the glycine transporters (GlyTs) GlyT1 and -2 have been reported to exist as monomers in the plasma membrane based on hydrodynamic and native gel electrophoretic studies. Here, we used cysteine substitution and oxidative cross-linking to show that of GlyT1 and GlyT2 also form dimeric complexes within the plasma membrane. GlyT oligomerization at the cell surface was confirmed for both GlyT1 and GlyT2 by fluorescence resonance energy transfer microscopy. Endoglycosidase treatment and surface biotinylation further revealed that complex-glycosylated GlyTs form dimers located at the cell surface. Furthermore, substitution of tryptophan 469 of GlyT2 by an arginine generated a transporter deficient in dimerization that was retained intracellulary. Based on these results and GlyT structures modeled by using the crystal structure of the bacterial homolog LeuT(Aa), as a template, residues located within the extracellular loop 3 and at the beginning of transmembrane domain 6 are proposed to contribute to the dimerization interface of GlyTs.

  20. Comparative DFT study of van der Waals complexes: rare-gas dimers, alkaline-earth dimers, zinc dimer, and zinc-rare-gas dimers.

    Science.gov (United States)

    Zhao, Yan; Truhlar, Donald G

    2006-04-20

    Recent interest in the application of density functional theory prompted us to test various functionals for the van der Waals interactions in the rare-gas dimers, the alkaline-earth metal dimers, zinc dimer, and zinc-rare-gas dimers. In the present study, we report such tests for 18 DFT functionals, including both some very recent functionals and some well-established older ones. We draw the following conclusions based on the mean errors in binding energies and complex geometries: (1) B97-1 gives the best performance for predicting the geometry of rare-gas dimers, whereas M05-2X and B97-1 give the best energetics for rare-gas dimers. (2) PWB6K gives the best performance for the prediction of the geometry of the alkaline-earth metal dimers, zinc dimers, and zinc-rare-gas dimers. M05-2X gives the best energetics for the metal dimers, whereas B97-1 gives the best energetics for the zinc-rare-gas dimers. (3) The M05 functional is unique in providing good accuracy for both covalent transition-metal dimers and van der Waals metal dimers. (4) The combined mean percentage unsigned error in geometries and energetics shows that M05-2X and MPWB1K are the overall best methods for the prediction of van der Waals interactions in metal and rare-gas van der Waals dimers.

  1. The common polymorphism of apolipoprotein E

    DEFF Research Database (Denmark)

    Gerdes, Ulrik

    2003-01-01

    almost everywhere and is often considered to be the ancestral or "wild-type" allele for that reason. However, there are several arguments for APOE*4 being the ancestral allele. But then, why has APOE*3 become so frequent? And why has APOE*4 not become extinct? The proportion of APOE*4 carriers increases...

  2. ApoE (Apolipoprotein E) Genotyping

    Science.gov (United States)

    ... Autoantibodies Digoxin Direct Antiglobulin Test Direct LDL Cholesterol Drug Abuse Testing EGFR Mutation Testing Electrolytes Emergency and Overdose ... the American Academy of Family Physicians [On-line journal]. Available online at http://www.aafp.org/afp/ ...

  3. Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor

    International Nuclear Information System (INIS)

    Goffinont, S.; Davidkova, M.; Spotheim-Maurizot, M.

    2009-01-01

    The wild type lactose repressor of Escherichia coli is a tetrameric protein formed by two identical dimers. They are associated via a C-terminal 4-helix bundle (called tetramerization domain) whose stability is ensured by the interaction of leucine zipper motifs. Upon in vitro γ-irradiation the repressor losses its ability to bind the operator DNA sequence due to damage of its DNA-binding domains. Using an engineered dimeric repressor for comparison, we show here that irradiation induces also the change of repressor oligomerisation state from tetramer to dimer. The splitting of the tetramer into dimers can result from the oxidation of the leucine residues of the tetramerization domain.

  4. Dimer and String Formation during Low Temperature Silicon Deposition on Si(100)

    DEFF Research Database (Denmark)

    Smith, A. P.; Jonsson, Hannes

    1996-01-01

    We present theoretical results based on density functional theory and kinetic Monte Carlo simulations of silicon deposition and address observations made in recently reported low temperature scanning tunneling microscopy studies. A mechanism is presented which explains dimer formation on top...... of the substrate's dimer rows at 160 K and up to room temperature, while between-row dimers and longer strings of adatoms (''diluted dimer rows'') form at higher temperature. A crossover occurs at around room temperature between two different mechanisms for adatom diffusion in our model....

  5. Adventures in Holographic Dimer Models

    Energy Technology Data Exchange (ETDEWEB)

    Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Karch, Andreas; /Washington U., Seattle; Yaida, Sho; /Stanford U., Phys. Dept.

    2011-08-12

    We abstract the essential features of holographic dimer models, and develop several new applications of these models. Firstly, semi-holographically coupling free band fermions to holographic dimers, we uncover novel phase transitions between conventional Fermi liquids and non-Fermi liquids, accompanied by a change in the structure of the Fermi surface. Secondly, we make dimer vibrations propagate through the whole crystal by way of double trace deformations, obtaining nontrivial band structure. In a simple toy model, the topology of the band structure experiences an interesting reorganization as we vary the strength of the double trace deformations. Finally, we develop tools that would allow one to build, in a bottom-up fashion, a holographic avatar of the Hubbard model.

  6. Effects of Dimerization of Serratia marcescens Endonuclease on Water Dynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chuanying; Beck, Brian W.; Krause, Kurt; Weksberg, Tiffany E.; Pettitt, Bernard M.

    2007-02-15

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The dynamics and structure of Serratia marcescens endonuclease and its neighboring solvent are investigated by molecular dynamics (MD). Comparisons are made with structural and biochemical experiments. The dimer form is physiologic and functions more processively than the monomer. We previously found a channel formed by connected clusters of waters from the active site to the dimer interface. Here, we show that dimerization clearly changes correlations in the water structure and dynamics in the active site not seen in the monomer. Our results indicate that water at the active sites of the dimer is less affected compared with bulk solvent than in the monomer where it has much slower characteristic relaxation times. Given that water is a required participant in the reaction, this gives a clear advantage to dimerization in the absence of an apparent ability to use both active sites simultaneously.

  7. Synthesis and Diels–Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers

    Directory of Open Access Journals (Sweden)

    Bilal Nişancı

    2009-08-01

    Full Text Available Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels–Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All compounds were characterized properly using NMR spectroscopy.

  8. Acute perioperative-stress-induced increase of atherosclerotic plaque volume and vulnerability to rupture in apolipoprotein-E-deficient mice is amenable to statin treatment and IL-6 inhibition

    Directory of Open Access Journals (Sweden)

    Henrike Janssen

    2015-09-01

    Full Text Available Myocardial infarction and stroke are frequent after surgical procedures and consume a considerable amount of benefit of surgical therapy. Perioperative stress, induced by surgery, is composed of hemodynamic and inflammatory reactions. The effects of perioperative stress on atherosclerotic plaques are ill-defined. Murine models to investigate the influence of perioperative stress on plaque stability and rupture are not available. We developed a model to investigate the influence of perioperative stress on plaque growth and stability by exposing apolipoprotein-E-deficient mice, fed a high cholesterol diet for 7 weeks, to a double hit consisting of 30 min of laparotomy combined with a substantial blood loss (approximately 20% of total blood volume; 400 µl. The innominate artery was harvested 72 h after the intervention. Control groups were sham and baseline controls. Interleukin-6 (IL-6 and serum amyloid A (SAA plasma levels were determined. Plaque load, vascular smooth muscle cell (VSMC and macrophage content were quantified. Plaque stability was assessed using the Stary score and frequency of signs of plaque rupture were assessed. High-dose atorvastatin (80 mg/kg body weight/day was administered for 6 days starting 3 days prior to the double hit. A single dose of an IL-6-neutralizing antibody or the fusion protein gp130-Fc selectively targeting IL-6 trans-signaling was subcutaneously injected. IL-6 plasma levels increased, peaking at 6 h after the intervention. SAA levels peaked at 24 h (n=4, P<0.01. Plaque volume increased significantly with the double hit compared to sham (n=8, P<0.01. More plaques were scored as complex or bearing signs of rupture after the double hit compared to sham (n=5-8, P<0.05. Relative VSMC and macrophage content remained unchanged. IL-6-inhibition or atorvastatin, but not blocking of IL-6 trans-signaling, significantly decreased plaque volume and complexity (n=8, P<0.01. Using this model, researchers

  9. Associations of egg and cholesterol intakes with carotid intima-media thickness and risk of incident coronary artery disease according to apolipoprotein E phenotype in men: the Kuopio Ischaemic Heart Disease Risk Factor Study.

    Science.gov (United States)

    Virtanen, Jyrki K; Mursu, Jaakko; Virtanen, Heli Ek; Fogelholm, Mikael; Salonen, Jukka T; Koskinen, Timo T; Voutilainen, Sari; Tuomainen, Tomi-Pekka

    2016-03-01

    In general populations, the effects of dietary cholesterol on blood cholesterol concentrations are modest. However, the relation is stronger in those with an ɛ4 allele in the apolipoprotein E gene (APOE). There is little information on the association between cholesterol intake and the risk of coronary artery disease (CAD) among those with the ApoE4 phenotype. We investigated the associations of intakes of cholesterol and eggs, a major source of dietary cholesterol, with carotid intima-media thickness and the risk of incident CAD in middle-aged and older men from eastern Finland. The study included 1032 men aged 42-60 y in 1984-1989 at the baseline examinations of the prospective, population-based Kuopio Ischaemic Heart Disease Risk Factor Study. Data on common carotid artery intima-media thickness (CCA-IMT) were available for 846 men. Dietary intakes were assessed with 4-d food records. Associations with incident CAD and baseline CCA-IMT were analyzed by using Cox regression and ANCOVA, respectively. The ApoE4 phenotype was found in 32.5% of the men. During the average follow-up of 20.8 y, 230 CAD events occurred. Egg or cholesterol intakes were not associated with the risk of CAD. Each 1 additional egg (55 g)/d was associated with a multivariable-adjusted HR of 1.17 (95% CI: 0.85, 1.61) in the ApoE4 noncarriers and an HR of 0.93 (95% CI: 0.50, 1.72) in the ApoE4 carriers (P-interaction = 0.34). Each 100-mg/d higher cholesterol intake was associated with an HR of 1.04 (95% CI: 0.89, 1.22) in the ApoE4 noncarriers and an HR of 0.95 (95% CI: 0.73, 1.25) in the ApoE4 carriers (P-interaction = 0.81). Egg or cholesterol intakes were also not associated with increased CCA-IMT. Egg or cholesterol intakes were not associated with increased CAD risk, even in ApoE4 carriers (i.e., in highly susceptible individuals). © 2016 American Society for Nutrition.

  10. Crystal structure of an unknown solvate of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-κ(4) O,N,N',O'}(N-ferrocenylisonicotinamide-κN (1))cobalt(II): a Co(II)-salen complex that forms hydrogen-bonded dimers.

    Science.gov (United States)

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-09-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red-brown solid by mixing equimolar amounts of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di-chloro-methane under nitro-gen and was characterized by ESI-MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N-H groups and phenolate O atoms on an adjacent mol-ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter-actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl-idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol-ecules. These solvent molecules' contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] available in PLATON.

  11. Rotational Spectrum of Propargyl Alcohol Dimer

    Science.gov (United States)

    Mani, Devendra; Arunan, E.

    2013-06-01

    Propargyl alcohol is a molecule of interest to astrophysics as well as combustion studies. Rotational-tunneling spectra of propargyl alcohol monomer is well known and shows that the molecule exists in gauche form. Recently we reported microwave spectra of Ar...propargyl alcohol complex. Propargyl alcochol exists in gauche form in the complex as well. In this study we have recorded pure rotational spectra of propargyl alcohol dimer between 4-13 GHz range.A total of 47 transitions, 24 a-type, 16 b-type and 7 c-type, have been observed and fitted with semi rigid rotor asymmetric top hamiltonian. The fitted rotational constants are: A = 2321.83323(47) MHz, B = 1150.47726(24) MHz and C = 1124.89000(20) MHz. The standard deviation for the fit is 2.5 kHz. The experimental rotational constants are very close to the structure predicted by ab-initio calculations in which two gauche-propargyl alcohol moieties are in three point contact stabilized by O-H...O, O-H...pi and C-H...pi interactions. Few transitions for duterated isotopologues of the dimer have also been observed and search for the remaining transitions is in progress. Details will be presented in the talk. E. Hirota,J. Mol. Spectrosc. 26 (1968) 335-350. J.C. Pearson, B.J. Drouin, J. Mol. Spectrosc. 234 (2005) 149-156. D. Mani, E. Arunan, ChemPhysChem 14 (2013) 754-763.

  12. Kinetics of DNA tile dimerization.

    Science.gov (United States)

    Jiang, Shuoxing; Yan, Hao; Liu, Yan

    2014-06-24

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile-tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency.

  13. Theoretical investigation on the 2e/12c bond and second hyperpolarizability of azaphenalenyl radical dimers: Strength and effect of dimerization

    Science.gov (United States)

    Zhong, Rong-Lin; Xu, Hong-Liang; Sun, Shi-Ling; Qiu, Yong-Qing; Zhao, Liang; Su, Zhong-Min

    2013-09-01

    An increasing number of chemists have focused on the investigations of two-electron/multicenter bond (2e/mc) that was first introduced to describe the structure of radical dimers. In this work, the dimerization of two isoelectronic radicals, triazaphenalenyl (TAP) and hexaazaphenalenyl (HAP) has been investigated in theory. Results show TAP2 is a stable dimer with stronger 2e/12c bond and larger interaction energy, while HAP2 is a less stable dimer with larger diradical character. Interestingly, the ultraviolet-visible absorption spectra suggest that the dimerization induces a longer wavelength absorption in visible area, which is dependent on the strength of dimerization. Significantly, the amplitude of second hyperpolarizability (γyyyy) of HAP2 is 1.36 × 106 a.u. that is larger than 7.79 × 104 a.u. of TAP2 because of the larger diradical character of HAP2. Therefore, the results indicate that the strength of radical dimerization can be effectively detected by comparing the magnitude of third order non-linear optical response, which is beneficial for further theoretical and experimental studies on the properties of complexes formed by radical dimerization.

  14. Dynamics and energetics of Ge(001) dimers

    NARCIS (Netherlands)

    van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Henricus J.W.

    2006-01-01

    The dynamic behavior of surface dimers on Ge(001) has been studied by positioning the tip of a scanning tunneling microscope over single flip-flopping dimers and measuring the tunneling current as a function of time. We observe that not just symmetric, but also asymmetric appearing dimers exhibit

  15. Species A rotavirus NSP3 acquires its translation inhibitory function prior to stable dimer formation.

    Directory of Open Access Journals (Sweden)

    Hugo I Contreras-Treviño

    Full Text Available Species A rotavirus non-structural protein 3 (NSP3 is a translational regulator that inhibits or, under some conditions, enhances host cell translation. NSP3 binds to the translation initiation factor eIF4G1 and evicts poly-(A binding protein (PABP from eIF4G1, thus inhibiting translation of polyadenylated mRNAs, presumably by disrupting the effect of PABP bound to their 3'-ends. NSP3 has a long coiled-coil region involved in dimerization that includes a chaperone Hsp90-binding domain (HS90BD. We aimed to study the role in NSP3 dimerization of a segment of the coiled-coil region adjoining the HS90BD. We used a vaccinia virus system to express NSP3 with point mutations in conserved amino acids in the coiled-coil region and determined the effects of these mutations on translation by metabolic labeling of proteins as well as on accumulation of stable NSP3 dimers by non-dissociating Western blot, a method that separates stable NSP3 dimers from the monomer/dimerization intermediate forms of the protein. Four of five mutations reduced the total yield of NSP3 and the formation of stable dimers (W170A, K171E, R173E and R187E:K191E, whereas one mutation had the opposite effects (Y192A. Treatment with the proteasome inhibitor MG132 revealed that stable NSP3 dimers and monomers/dimerization intermediates are susceptible to proteasome degradation. Surprisingly, mutants severely impaired in the formation of stable dimers were still able to inhibit host cell translation, suggesting that NSP3 dimerization intermediates are functional. Our results demonstrate that rotavirus NSP3 acquires its function prior to stable dimer formation and remain as a proteasome target throughout dimerization.

  16. Discrete Dipole Approximation Simulation of Nearly Touching Plasmonic Au Dimers and Influence of Particle Shape Assembly on Optical Response.

    Science.gov (United States)

    Xu, Xi-Bin; Wang, Yu-Ying; Yi, Zao; Li, Xi-Bo; Luo, Jiang-Shan; Luo, Bing-Chi; Yi, You-Gen; Tang, Yong-Jian

    2016-01-01

    The method Discrete Dipole Approximation (DDA) is used to calculate the extinction spectra and field distribution of three types of dimers. In the paper we provide a systematic analysis of the optical response of different nanoscopic dimer structures with relatively small gap distances. A description is given about how the energy and excitation cross sections of dimer plasmons depend on nanoparticle separation. Resonance peaks of dimers show red-shift compared with single nanoparticle. Dimers formed by different single particle display distinct optical response. Interaction junctions in dimers can serve as hot spots for field enhancement. Field distribution in gaps made of two flat planes is nearly continuous. Changing gaps between two particles in dimers can tune the resonance wavelength effectively as well as different particle ensembles. Existence of sharp corners can attract and change field distribution. It is not effective volume but the effective cross-section that dominates the extinction efficiency.

  17. Rubidium dimers in paraffin-coated cells

    International Nuclear Information System (INIS)

    Acosta, V M; Windes, D; Corsini, E; Ledbetter, M P; Karaulanov, T; Budker, D; Jarmola, A; Auzinsh, M; Rangwala, S A; Jackson Kimball, D F

    2010-01-01

    Measurements were made to determine the density of rubidium dimer vapor in paraffin-coated cells. The number density of dimers and atoms in similar paraffin-coated and uncoated cells was measured by optical spectroscopy. Due to the relatively low melting point of paraffin, a limited temperature range of 43-80 0 C was explored, with the lower end corresponding to a dimer density of less than 10 7 cm -3 . With 1 min integration time, a sensitivity to dimer number density of better than 10 6 cm -3 was achieved. No significant difference in dimer density between the cells was observed.

  18. Reversible dimerization of 20 kilodalton human growth hormone (hGH).

    Science.gov (United States)

    Nagatomi, Y; Ikeda, M; Uchida, H; Wada, M; Kobayashi, H; Hashimoto, Y; Mabuchi, K; Hayakawa, M; Kusuhara, N; Honjo, M

    2000-08-01

    A noncovalent dimer of the 22 kilodalton human growth hormone (22 K-hGH) is known to have diminished somatogenic activity compared with monomeric 22 K-hGH. In the present study, we examined the biological activity and physicochemical behaviour of a noncovalent dimer of the 20 kilodalton human growth hormone (20 K-hGH), an isoform of 22 K-hGH. Analysis of the equilibrium between monomeric and associated forms revealed that the associated 20 K-hGH was present in the dimeric form in aqueous solution. The kinetics of dimerization in rat plasma followed the theory of dissociation-association equilibrium, and more than 99% of 20 K-hGH molecules existed as a monomer in the equilibrium state at the physiological hGH concentration. Analysis of the pharmacokinetics showed that the ratio of the administrated dimer in rat circulation decreased from 43% to less than 4% in 2 h. A preparation of noncovalent dimeric 20 K-hGH had essentially the same degree of biological potency as that of a monomer in both in vitro and in vivo bioassays. In conclusion, dimerization of 20 K-hGH is reversible both in vitro and in vivo and a noncovalent dimer can function as a pharmaceutically active component of a 20 K-hGH preparation, in contrast to a 22 K-hGH preparation. Copyright 2000 Harcourt Publishers Ltd.

  19. Fiber optic D dimer biosensor

    Science.gov (United States)

    Glass, Robert S.; Grant, Sheila A.

    1999-01-01

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

  20. Dissociative attachment to lithium dimers

    International Nuclear Information System (INIS)

    Wadehra, J.M.

    1987-01-01

    The cross sections and the rates of production of negative ions of atomic lithium by the process of dissociative electron attachment to lithium dimers are obtained by using the resonant scattering theory. Both the cross sections as well as the rates of attachment are enhanced if the lithium molecule is initially vibrationally excited. General expressions for approximately obtaining the rates of electron attachment to any vibrational level of Li 2 are presented

  1. Detectability of H2-Ar and H2-Ne Dimers in Jovian Atmospheres

    Directory of Open Access Journals (Sweden)

    Young-Key Minn

    1997-12-01

    Full Text Available The detection of jovian hydrogen-hydrogen dimers through the clear telluric 2-micron window(Kim et al. 1995, Trafton et al. 1997 suggests possibility to detect noble gases in the form of dimer with hydrogen in jovian atmospheres. Since noble gases do not have spectral structures in the infrared, it has been difficult to derive their abundances in the atmospheres of jovian planets. If there is a significant component of noble gases other than helium in the jovian atmospheres. it might be detected through its dimer spectrum with hydrogen molecule. The relatively sharp spectral structures of hydrogen-argon and hydrogen-neon dimers compared with those of hydrogen-hydrogen dimers are useful for the detection, if an adequate signal-to-noise (S/N is obtained. If we use a large telescope, such as the Keck telescope, with a long exposure time (>24 hours, then H2-Ar spectral structure may be detected.

  2. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Norrman, Mathias; Strauss, Holger M.

    2012-01-01

    An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers...... and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization...

  3. Crystal structure of an unknown solvate of {2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato-κ4 O,N,N′,O′}(N-ferrocenylisonicotinamide-κN 1)cobalt(II): a CoII–salen complex that forms hydrogen-bonded dimers

    Science.gov (United States)

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-01-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red–brown solid by mixing equimolar amounts of {2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di­chloro­methane under nitro­gen and was characterized by ESI–MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N—H groups and phenolate O atoms on an adjacent mol­ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter­actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl­idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol­ecules. These solvent molecules’ contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9–18] available in PLATON. PMID:26396858

  4. Study of structural stability and damaging effect on membrane for four Aβ42 dimers.

    Directory of Open Access Journals (Sweden)

    Wei Feng

    Full Text Available Increasing evidence shows that Aβ oligomers are key pathogenic molecules in Alzheimer's disease. Among Aβ oligomers, dimer is the smallest aggregate and toxic unit. Therefore, understanding its structural and dynamic properties is quite useful to prevent the formation and toxicity of the Aβ oligomers. In this study, we performed molecular dynamic simulations on four Aβ42 dimers, 2NCb, CNNC, NCNC and NCCN, within the hydrated DPPC membrane. Four Aβ42 dimers differ in the arrangements of two Aβ42 peptides. This study aims to investigate the impact of aggregation pattern of two Aβ peptides on the structural stability of the Aβ42 dimer and its disruption to the biological membrane. The MD results demonstrate that the NCCN, CNNC and NCNC have the larger structural fluctuation at the N-terminus of Aβ42 peptide, where the β-strand structure converts into the coil structure. The loss of the N-terminal β-strand further impairs the aggregate ability of Aβ42 dimer. In addition, inserting Aβ42 dimer into the membrane can considerably decrease the average APL of DPPC membrane. Moreover this decrease effect is largely dependent on the distance to the location of Aβ42 dimer and its secondary structure forms. Based on the results, the 2NCb is considered as a stable dimeric unit for aggregating the larger Aβ42 oligomer, and has a potent ability to disrupt the membrane.

  5. Synchronized oscillations of dimers in biphasic charged fd-virus suspensions.

    Science.gov (United States)

    Kang, K; Piao, S H; Choi, H J

    2016-08-01

    Micron-sized colloidal spheres that are dispersed in an isotropic-nematic biphasic host suspension of charged rods (fd-virus particles) are shown to spontaneously form dimers, which exhibit a synchronized oscillatory motion. Dimer formation is not observed in the monophase of isotropic and nematic suspensions. The synchronized oscillations of dimers are connected to the inhomogeneous state of the host suspension of charged rods (fd viruses) where nematic domains are in coexistence with isotropic regions. The synchronization of oscillations occurs in bulk states, in the absence of an external field. With a low field strength of an applied electric field, the synchronization is rather reduced, but it recovers again when the field is turned off. In this Rapid Communication, we report this observation as an example of the strange attractor, occurring in the mixture of PS (polystyrene) dimers in an isotropic-nematic coexistence biphasic fd-virus network. Furthermore, we highlight that the synchronization of PS-dimer oscillations is the result of a global bifurcation diagram, driven by a delicate balance between the short-attractive "twisted" interaction of PS dimers and long-ranged electrostatic repulsive interactions of charged fd rods. The interest is then in the local enhancement of "twist-nematic" elasticity in reorientation of the dimer oscillations. An analysis of image-time correlations is provided with the data movies and Fourier transforms of averaged orientations for the synchronized oscillations of dimers in the biphasic I-N coexistence concentration of charged fd-virus suspensions.

  6. Cold-active alkaline phosphatase is irreversibly transformed into an inactive dimer by low urea concentrations.

    Science.gov (United States)

    Hjörleifsson, Jens Guðmundur; Ásgeirsson, Bjarni

    2016-07-01

    Alkaline phosphatase is a homodimeric metallo-hydrolase where both Zn(2+) and Mg(2+) are important for catalysis and stability. Cold-adapted alkaline phosphatase variants have high activity at low temperatures and lower thermal stability compared with variants from mesophilic hosts. The instability, and thus inactivation, could be due to loose association of the dimers and/or loosely bound Mg(2)(+) in the active site, but this has not been studied in detail for the cold-adapted variants. Here, we focus on using the intrinsic fluorescence of Trp in alkaline phosphatase from the marine bacterium Vibrio splendidus (VAP) to probe for dimerization. Trp→Phe substitutions showed that two out of the five native Trp residues contributed mostly to the fluorescence emission. One residue, 15Å away from the active site (W460) and highly solvent excluded, was phosphorescent and had a distant role in substrate binding. An additional Trp residue was introduced to the dimer interface to act as a possible probe for dimerization. Urea denaturation curves indicated that an inactive dimer intermediate, structurally equivalent to the native state, was formed before dimer dissociation took place. This is the first example of the transition of a native dimer to an inactive dimer intermediate for alkaline phosphatase without using mutagenesis, ligands, or competitive inhibition. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Plant Kinesin-Like Calmodulin Binding Protein Employs Its Regulatory Domain for Dimerization.

    Directory of Open Access Journals (Sweden)

    Maia V Vinogradova

    Full Text Available Kinesin-like calmodulin binding protein (KCBP, a Kinesin-14 family motor protein, is involved in the structural organization of microtubules during mitosis and trichome morphogenesis in plants. The molecular mechanism of microtubule bundling by KCBP remains unknown. KCBP binding to microtubules is regulated by Ca(2+-binding proteins that recognize its C-terminal regulatory domain. In this work, we have discovered a new function of the regulatory domain. We present a crystal structure of an Arabidopsis KCBP fragment showing that the C-terminal regulatory domain forms a dimerization interface for KCBP. This dimerization site is distinct from the dimerization interface within the N-terminal domain. Side chains of hydrophobic residues of the calmodulin binding helix of the regulatory domain form the C-terminal dimerization interface. Biochemical experiments show that another segment of the regulatory domain located beyond the dimerization interface, its negatively charged coil, is unexpectedly and absolutely required to stabilize the dimers. The strong microtubule bundling properties of KCBP are unaffected by deletion of the C-terminal regulatory domain. The slow minus-end directed motility of KCBP is also unchanged in vitro. Although the C-terminal domain is not essential for microtubule bundling, we suggest that KCBP may use its two independent dimerization interfaces to support different types of bundled microtubule structures in cells. Two distinct dimerization sites may provide a mechanism for microtubule rearrangement in response to Ca(2+ signaling since Ca(2+- binding proteins can disengage KCBP dimers dependent on its C-terminal dimerization interface.

  8. Solitary waves in dimer binary collision model

    Science.gov (United States)

    Ahsan, Zaid; Jayaprakash, K. R.

    2017-01-01

    Solitary wave propagation in nonlinear diatomic (dimer) chains is a very interesting topic of research in the study of nonlinear lattices. Such waves were recently found to be supported by the essentially nonlinear granular lattice and Toda lattice. An interesting aspect of this discovery is attributed to the realization of a spectrum of the mass ratio (the only system parameter governing the dynamics) that supports the propagation of such waves corresponding to the considered interaction potential. The objective of this exposition is to explore solitary wave propagation in the dimer binary collision (BC) model. Interestingly, the dimer BC model supports solitary wave propagation at a discrete spectrum of mass ratios similar to those observed in granular and Toda dimers. Further, we report a qualitative and one-to-one correspondence between the spectrum of the mass ratio corresponding to the dimer BC model and those corresponding to granular and Toda dimer chains.

  9. Biological activity and dimerization state of modified phytochrome A proteins.

    Directory of Open Access Journals (Sweden)

    Peng Liu

    Full Text Available To assess potential physical interactions of type I phyA with the type II phyB-phyE phytochromes in vivo, transgenes expressing fusion gene forms of phyA were introduced into the Arabidopsis phyA mutant background. When a single c-Myc (myc epitope is added to either the N- or C-terminus of phyA, the constructs completely complement phyA mutant phenotypes. However, addition of larger tags, such as six consecutive myc epitopes or the yellow fluorescent protein sequence, result in fusion proteins that show reduced activity. All the tagged phyA proteins migrate as dimers on native gels and co-immunoprecipitation reveals no binding interaction of phyA to any of the type II phys in the dark or under continuous far-red light. Dimers of the phyA 1-615 amino acid N-terminal photosensory domain (NphyA, generated in vivo with a yeast GAL4 dimerization domain and attached to a constitutive nuclear localization sequence, are expressed at a low level and, although they cause a cop phenotype in darkness and mediate a very low fluence response to pulses of FR, have no activity under continuous FR. It is concluded that type I phyA in its Pr form is present in plants predominantly or exclusively as a homodimer and does not stably interact with type II phys in a dimer-to-dimer manner. In addition, its activity in mediating response to continuous FR is sensitive to modification of its N- or C-terminus.

  10. Fe65-PTB2 Dimerization Mimics Fe65-APP Interaction

    Directory of Open Access Journals (Sweden)

    Lukas P. Feilen

    2017-05-01

    Full Text Available Physiological function and pathology of the Alzheimer’s disease causing amyloid precursor protein (APP are correlated with its cytosolic adaptor Fe65 encompassing a WW and two phosphotyrosine-binding domains (PTBs. The C-terminal Fe65-PTB2 binds a large portion of the APP intracellular domain (AICD including the GYENPTY internalization sequence fingerprint. AICD binding to Fe65-PTB2 opens an intra-molecular interaction causing a structural change and altering Fe65 activity. Here we show that in the absence of the AICD, Fe65-PTB2 forms a homodimer in solution and determine its crystal structure at 2.6 Å resolution. Dimerization involves the unwinding of a C-terminal α-helix that mimics binding of the AICD internalization sequence, thus shielding the hydrophobic binding pocket. Specific dimer formation is validated by nuclear magnetic resonance (NMR techniques and cell-based analyses reveal that Fe65-PTB2 together with the WW domain are necessary and sufficient for dimerization. Together, our data demonstrate that Fe65 dimerizes via its APP interaction site, suggesting that besides intra- also intermolecular interactions between Fe65 molecules contribute to homeostatic regulation of APP mediated signaling.

  11. Spectroscopic observation and structure of CS2 dimer

    Science.gov (United States)

    Rezaei, M.; Norooz Oliaee, J.; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2011-04-01

    Infrared spectra of the CS2 dimer are observed in the region of the CS2 ν3 fundamental band (˜1535 cm-1) using a tunable diode laser spectrometer. The weakly bound complex is formed in a pulsed supersonic slit-jet expansion of a dilute gas mixture of carbon disulfide in helium. Contrary to the planar slipped-parallel geometry previously observed for (CO2)2, (N2O)2, and (OCS)2, the CS2 dimer exhibits a cross-shaped structure with D2d symmetry. Two bands were observed and analyzed: the fundamental (C-S asymmetric stretch) and a combination involving this mode plus an intermolecular vibration. In both cases, the rotational structure corresponds to a perpendicular (ΔK = ±1) band of a symmetric rotor molecule. The intermolecular center of mass separation (C-C distance) is determined to be 3.539(7) Å. Thanks to symmetry, this is the only parameter required to characterize the structure, if the monomer geometry is assumed to remain unchanged in the dimer. From the band centers of the fundamental and combination band an intermolecular frequency of 10.96 cm-1 is obtained, which we assign as the torsional bending mode. This constitutes the first high resolution spectroscopic investigation of CS2 dimer.

  12. Emergence of biaxial nematic phases in solutions of semiflexible dimers

    Science.gov (United States)

    Vaghela, Arvin; Teixeira, Paulo I. C.; Terentjev, Eugene M.

    2017-10-01

    We investigate the isotropic, uniaxial nematic and biaxial nematic phases, and the transitions between them, for a model lyotropic mixture of flexible molecules consisting of two rigid rods connected by a spacer with variable bending stiffness. We apply density-functional theory within the Onsager approximation to describe strictly excluded-volume interactions in this athermal model and to self-consistently find the orientational order parameters dictated by its complex symmetry, as functions of the density. Earlier work on lyotropic ordering of rigid bent-rod molecules is reproduced and extended to show explicitly the continuous phase transition at the Landau point, at a critical bend angle of 36∘. For flexible dimers with no intrinsic biaxiality, we find that a biaxial nematic phase can nevertheless form at a sufficiently high density and low bending stiffness. For bending stiffness κ >0.86 kBT , this biaxial phase manifests as dimer bending fluctuations occurring preferentially in one plane. When the dimers are more flexible, κ the modal shape of the fluctuating dimer is a V with an acute opening angle, and one of the biaxial order parameters changes sign, indicating a rotation of the directors. These two regions are separated by a narrow strip of uniaxial nematic in the phase diagram, which we generate in terms of the spacer stiffness and particle density.

  13. Morphological and physiological retinal degeneration induced by intravenous delivery of vitamin A dimers in rabbits

    Directory of Open Access Journals (Sweden)

    Jackie Penn

    2015-02-01

    Full Text Available The eye uses vitamin A as a cofactor to sense light and, during this process, some vitamin A molecules dimerize, forming vitamin A dimers. A striking chemical signature of retinas undergoing degeneration in major eye diseases such as age-related macular degeneration (AMD and Stargardt disease is the accumulation of these dimers in the retinal pigment epithelium (RPE and Bruch’s membrane (BM. However, it is not known whether dimers of vitamin A are secondary symptoms or primary insults that drive degeneration. Here, we present a chromatography-free method to prepare gram quantities of the vitamin A dimer, A2E, and show that intravenous administration of A2E to the rabbit results in retinal degeneration. A2E-damaged photoreceptors and RPE cells triggered inflammation, induced remolding of the choroidal vasculature and triggered a decline in the retina’s response to light. Data suggest that vitamin A dimers are not bystanders, but can be primary drivers of retinal degeneration. Thus, preventing dimer formation could be a preemptive strategy to address serious forms of blindness.

  14. Effect of thermal sterilization on ferulic, coumaric and cinnamic acids: dimerization and antioxidant activity.

    Science.gov (United States)

    Arrieta-Baez, Daniel; Dorantes-Álvarez, Lidia; Martinez-Torres, Rocio; Zepeda-Vallejo, Gerardo; Jaramillo-Flores, Maria Eugenia; Ortiz-Moreno, Alicia; Aparicio-Ozores, Gerardo

    2012-10-01

    Some phenolic compounds, such as ferulic acid and p-coumaric acid, exist in the form of free acids, in fruits, rice, corn and other grains. Thermal treatment (121 °C at 15-17 psi) for different times on ferulic, p-coumaric and cinnamic acids as well as equimolar mixtures of these acids was investigated. Ferulic and p-coumaric acids underwent decarboxylation, yielding dimeric products formed through their corresponding radical intermediates, while cinnamic acid was recovered unreacted. High-performance liquid chromatography analysis showed no cross-dimerization when equimolar mixtures of pairs of hydroxycinnamic acids were treated under the same conditions. Dimers were characterized as (E)-4',4″-(but-1-ene-1,3-diyl)bis(2'-methoxyphenol)) (dimer of 4-vinylguaiacol) and (E)-4,4'-(but-1-ene-1,3-diyl)diphenol) (dimer of 4-vinylphenol) by nuclear magnetic resonance and mass spectrometry. Sterilization by thermal processing produced dimers of ferulic and coumaric acid. The antioxidant activity of these dimers was greater than that of the respective hydroxycinnamic acids. These results may be relevant for fruits and grains that contain hydroxycinnamic acids and undergo sterilization processes such as canning. Copyright © 2012 Society of Chemical Industry.

  15. Stereoselective C9 carbon-carbon couplings of quinine: synthesis and conformational analysis of new C2-symmetric dimers.

    Science.gov (United States)

    Boratyński, Przemysław J; Turowska-Tyrk, Ilona; Skarzewski, Jacek

    2008-09-19

    An unexpected stereoselective direct dimerization occurred when 9-quinine halide was treated with butyllithium. The reaction of either (9S)- or (9R)-chloroquinine gave the same C2-symmetric dimer with 9R configuration (X-ray structure). A tentative mechanism involving radical recombination is discussed. This highly congested dimer forms two atropisomers, and their reversible interconversion was studied by NMR. Another C2-symmetric (9S)-quinine dimer connected solely by carbon-carbon bonds was obtained by the stereoselective coupling of bis(arylbromomagnesium) derivative with (9S)-chloroquinine.

  16. Overall conformation of covalently stabilized domain-swapped dimer of human cystatin C in solution

    Science.gov (United States)

    Murawska, Magdalena; Szymańska, Aneta; Grubb, Anders; Kozak, Maciej

    2017-11-01

    Human cystatin C (HCC), a small protein, plays a crucial role in inhibition of cysteine proteases. The most common structural form of human cystatin C in crystals is a dimer, which has been evidenced both for the native protein and its mutants. In these structures, HCC dimers were formed through the mechanism of domain swapping. The structure of the monomeric form of human cystatin C was determined for V57N mutant and the mutant with the engineered disulfide bond (L47C)-(G69C) (known as stab1-HCC). On the basis of stab1-HCC, a number of covalently stabilized oligomers, including also dimers have been obtained. The aim of this study was to analyze the structure of the covalently stabilized dimer HCC in solution by the small angle X-ray scattering (SAXS) technique and synchrotron radiation. Experimental data confirmed that in solution this protein forms a dimer, which is characterized by the radius of gyration RG = 3.1 nm and maximum intramolecular distance Dmax = 10.3 nm. Using the ab initio method and program DAMMIN, we propose a low resolution structure of stabilized covalently cystatin C in solution. Stab-HCC dimer adopts in solution an elongated conformation, which is well reconstructed by the ab initio model.

  17. A redox-dependent dimerization switch regulates activity and tolerance for reactive oxygen species of barley seed glutathione peroxidase

    DEFF Research Database (Denmark)

    Navrot, Nicolas; Skjoldager, Nicklas; Bunkenborg, Jakob

    2015-01-01

    Monomeric and dimeric forms of recombinant barley (Hordeum vulgare subsp. vulgare) glutathione peroxidase 2 (HvGpx2) are demonstrated to display distinctly different functional properties in vitro. Monomeric HvGpx2 thus has five fold higher catalytic efficiency than the dimer towards tert-butyl h...

  18. Biosynthesis of intestinal microvillar proteins. Dimerization of aminopeptidase N and lactase-phlorizin hydrolase

    DEFF Research Database (Denmark)

    Danielsen, E M

    1990-01-01

    of dimers of this enzyme therefore occurs prior to the Golgi-associated processing, and the slow rate of dimerization may be the rate-limiting step in the transport from the endoplasmic reticulum to the Golgi complex. For lactase-phlorizin hydrolase, the posttranslational processing includes a proteolytic......The pig intestinal brush border enzymes aminopeptidase N (EC 3.4.11.2) and lactase-phlorizin hydrolase (EC 3.2.1.23-62) are present in the microvillar membrane as homodimers. Dimethyl adipimidate was used to cross-link the two [35S]methionine-labeled brush border enzymes from cultured mucosal...... explants. For aminopeptidase N, dimerization did not begin until 5-10 min after synthesis, and maximal dimerization by cross-linking of the transient form of the enzyme required 1 h, whereas the mature form of aminopeptidase N cross-linked with unchanged efficiency from 45 min to 3 h of labeling. Formation...

  19. Enzymatic oxidative dimerization of silymarin flavonolignans

    Czech Academy of Sciences Publication Activity Database

    Gavezzotti, P.; Vavříková, Eva; Valentová, Kateřina; Fronza, G.; Kudanga, T.; Kuzma, Marek; Riva, S.; Biedermann, David; Křen, Vladimír

    2014-01-01

    Roč. 109, NOV 2014 (2014), s. 24-30 ISSN 1381-1177 R&D Projects: GA MŠk(CZ) LD13041; GA ČR(CZ) GP14-14373P Institutional support: RVO:61388971 Keywords : Silybin dimers * Silydianin dimer * Silymarin Subject RIV: CE - Biochemistry Impact factor: 2.128, year: 2014

  20. Designer interface peptide grafts target estrogen receptor alpha dimerization

    International Nuclear Information System (INIS)

    Chakraborty, S.; Asare, B.K.; Biswas, P.K.; Rajnarayanan, R.V.

    2016-01-01

    The nuclear transcription factor estrogen receptor alpha (ERα), triggered by its cognate ligand estrogen, regulates a variety of cellular signaling events. ERα is expressed in 70% of breast cancers and is a widely validated target for anti-breast cancer drug discovery. Administration of anti-estrogen to block estrogen receptor activation is still a viable anti-breast cancer treatment option but anti-estrogen resistance has been a significant bottle-neck. Dimerization of estrogen receptor is required for ER activation. Blocking ERα dimerization is therefore a complementary and alternative strategy to combat anti-estrogen resistance. Dimer interface peptide “I-box” derived from ER residues 503–518 specifically blocks ER dimerization. Recently using a comprehensive molecular simulation we studied the interaction dynamics of ERα LBDs in a homo-dimer. Based on this study, we identified three interface recognition peptide motifs LDKITDT (ERα residues 479–485), LQQQHQRLAQ (residues 497–506), and LSHIRHMSNK (residues 511–520) and reported the suitability of using LQQQHQRLAQ (ER 497–506) as a template to design inhibitors of ERα dimerization. Stability and self-aggregation of peptide based therapeutics poses a significant bottle-neck to proceed further. In this study utilizing peptide grafted to preserve their pharmacophoric recognition motif and assessed their stability and potential to block ERα mediated activity in silico and in vitro. The Grafted peptides blocked ERα mediated cell proliferation and viability of breast cancer cells but did not alter their apoptotic fate. We believe the structural clues identified in this study can be used to identify novel peptidometics and small molecules that specifically target ER dimer interface generating a new breed of anti-cancer agents. - Highlights: • Designer peptide grafts retain core molecular recognition motif during MD simulations. • Designer peptide grafts with Poly-ALA helix form stable

  1. Designer interface peptide grafts target estrogen receptor alpha dimerization

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, S. [Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, Tougaloo, MS 39174 (United States); Asare, B.K. [Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY 14214 (United States); Biswas, P.K., E-mail: pbiswas@tougaloo.edu [Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, Tougaloo, MS 39174 (United States); Rajnarayanan, R.V., E-mail: rajendra@buffalo.edu [Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY 14214 (United States)

    2016-09-09

    The nuclear transcription factor estrogen receptor alpha (ERα), triggered by its cognate ligand estrogen, regulates a variety of cellular signaling events. ERα is expressed in 70% of breast cancers and is a widely validated target for anti-breast cancer drug discovery. Administration of anti-estrogen to block estrogen receptor activation is still a viable anti-breast cancer treatment option but anti-estrogen resistance has been a significant bottle-neck. Dimerization of estrogen receptor is required for ER activation. Blocking ERα dimerization is therefore a complementary and alternative strategy to combat anti-estrogen resistance. Dimer interface peptide “I-box” derived from ER residues 503–518 specifically blocks ER dimerization. Recently using a comprehensive molecular simulation we studied the interaction dynamics of ERα LBDs in a homo-dimer. Based on this study, we identified three interface recognition peptide motifs LDKITDT (ERα residues 479–485), LQQQHQRLAQ (residues 497–506), and LSHIRHMSNK (residues 511–520) and reported the suitability of using LQQQHQRLAQ (ER 497–506) as a template to design inhibitors of ERα dimerization. Stability and self-aggregation of peptide based therapeutics poses a significant bottle-neck to proceed further. In this study utilizing peptide grafted to preserve their pharmacophoric recognition motif and assessed their stability and potential to block ERα mediated activity in silico and in vitro. The Grafted peptides blocked ERα mediated cell proliferation and viability of breast cancer cells but did not alter their apoptotic fate. We believe the structural clues identified in this study can be used to identify novel peptidometics and small molecules that specifically target ER dimer interface generating a new breed of anti-cancer agents. - Highlights: • Designer peptide grafts retain core molecular recognition motif during MD simulations. • Designer peptide grafts with Poly-ALA helix form stable

  2. Dimerization of the Glucan Phosphatase Laforin Requires the Participation of Cysteine 329

    Science.gov (United States)

    Sánchez-Martín, Pablo; Raththagala, Madushi; Bridges, Travis M.; Husodo, Satrio; Gentry, Matthew S.; Sanz, Pascual; Romá-Mateo, Carlos

    2013-01-01

    Laforin, encoded by a gene that is mutated in Lafora Disease (LD, OMIM 254780), is a modular protein composed of a carbohydrate-binding module and a dual-specificity phosphatase domain. Laforin is the founding member of the glucan-phosphatase family and regulates the levels of phosphate present in glycogen. Multiple reports have described the capability of laforin to form dimers, although the function of these dimers and their relationship with LD remains unclear. Recent evidence suggests that laforin dimerization depends on redox conditions, suggesting that disulfide bonds are involved in laforin dimerization. Using site-directed mutagenesis we constructed laforin mutants in which individual cysteine residues were replaced by serine and then tested the ability of each protein to dimerize using recombinant protein as well as a mammalian cell culture assay. Laforin-Cys329Ser was the only Cys/Ser mutant unable to form dimers in both assays. We also generated a laforin truncation lacking the last three amino acids, laforin-Cys329X, and this truncation also failed to dimerize. Interestingly, laforin-Cys329Ser and laforin-Cys329X were able to bind glucans, and maintained wild type phosphatase activity against both exogenous and biologically relevant substrates. Furthermore, laforin-Cys329Ser was fully capable of participating in the ubiquitination process driven by a laforin-malin complex. These results suggest that dimerization is not required for laforin phosphatase activity, glucan binding, or for the formation of a functional laforin-malin complex. Cumulatively, these results suggest that cysteine 329 is specifically involved in the dimerization process of laforin. Therefore, the C329S mutant constitutes a valuable tool to analyze the physiological implications of laforin’s oligomerization. PMID:23922729

  3. Directed diffusion of reconstituting dimers

    Energy Technology Data Exchange (ETDEWEB)

    Barma, Mustansir [Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Grynberg, Marcelo D [Departamento de Fisica, Universidad Nacional de La Plata (1900) La Plata (Argentina); Stinchcombe, Robin B [Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge CB3 0EH (United Kingdom)

    2007-02-14

    We discuss the dynamical aspects of an asymmetric version of assisted diffusion of hard core particles on a ring studied by Menon et al (1997 J. Stat. Phys. 86 1237). The asymmetry brings in phenomena like kinematic waves and effects of the Kardar-Parisi-Zhang non-linearity, which combine with the feature of strongly broken ergodicity, a characteristic of the model. A central role is played by a single non-local invariant, the irreducible string, whose interplay with the driven motion of reconstituting dimers, arising from the assisted hopping, determines the asymptotic dynamics and scaling regimes. These are investigated both analytically and numerically through sector-dependent mappings to the asymmetric simple exclusion process.

  4. Structural features of the KPI domain control APP dimerization, trafficking, and processing.

    Science.gov (United States)

    Ben Khalifa, Naouel; Tyteca, Donatienne; Marinangeli, Claudia; Depuydt, Mathieu; Collet, Jean-François; Courtoy, Pierre J; Renauld, Jean-Christophe; Constantinescu, Stefan; Octave, Jean-Noël; Kienlen-Campard, Pascal

    2012-02-01

    The two major isoforms of human APP, APP695 and APP751, differ by the presence of a Kunitz-type protease inhibitor (KPI) domain in the extracellular region. APP processing and function is thought to be regulated by homodimerization. We used bimolecular fluorescence complementation (BiFC) to study dimerization of different APP isoforms and mutants. APP751 was found to form significantly more homodimers than APP695. Mutation of dimerization motifs in the TM domain did not affect fluorescence complementation, but native folding of KPI is critical for APP751 homodimerization. APP751 and APP695 dimers were mostly localized at steady state in the Golgi region, suggesting that most of the APP751 and 695 dimers are in the secretory pathway. Mutation of the KPI led to the retention of the APP homodimers in the endoplasmic reticulum. We finally showed that APP751 is more efficiently processed through the nonamyloidogenic pathway than APP695. These findings provide new insight on the particular role of KPI domain in APP dimerization. The correlation observed between dimerization, subcellular localization, and processing suggests that dimerization acts as an efficient regulator of APP trafficking in the secretory compartments that has major consequences on its processing.

  5. Dynamic models of G-protein coupled receptor dimers: indications of asymmetry in the rhodopsin dimer from molecular dynamics simulations in a POPC bilayer

    Science.gov (United States)

    Filizola, Marta; Wang, Simon X.; Weinstein, Harel

    2006-08-01

    Based on the growing evidence that G-protein coupled receptors (GPCRs) form homo- and hetero-oligomers, models of GPCR signaling are now considering macromolecular assemblies rather than monomers, with the homo-dimer regarded as the minimal oligomeric arrangement required for functional coupling to the G-protein. The dynamic mechanisms of such signaling assemblies are unknown. To gain some insight into properties of GPCR dimers that may be relevant to functional mechanisms, we study their current structural prototype, rhodopsin. We have carried out nanosecond time-scale molecular dynamics (MD) simulations of a rhodopsin dimer and compared the results to the monomer simulated in the same type of bilayer membrane model composed of an equilibrated unit cell of hydrated palmitoyl-oleoyl-phosphatidyl choline (POPC). The dynamic representation of the homo-dimer reveals the location of structural changes in several regions of the monomeric subunits. These changes appear to be more pronounced at the dimerization interface that had been shown to be involved in the activation process [Proc Natl Acad Sci USA 102:17495, 2005]. The results are consistent with a model of GPCR activation that involves allosteric modulation through a single GPCR subunit per dimer.

  6. Biosynthesis of intestinal microvillar proteins. Dimerization of aminopeptidase N and lactase-phlorizin hydrolase

    Energy Technology Data Exchange (ETDEWEB)

    Danielsen, E.M. (Univ. of Cophenhagen (Denmark))

    1990-01-09

    The pig intestinal brush border enzymes aminopeptidase and lactase-phlorizin hydrolase are present in the microvilla membrane as homodimers. Dimethyl adipimidate was used to cross-link the two ({sup 35}S)methionine-labeled brush border enzymes from cultured mucosal explants. For aminopeptidase N, dimerization did not begin until 5-10 min after synthesis, and maximal dimerization by cross-linking of the transient form of the enzyme required 1 h, whereas the mature form of aminopeptidase N cross-linked with unchanged efficiency from 45 min to 3 h of labeling. Formation of dimers of this enzyme therefore occurs prior to the Golgi-associated processing, and the slow rate of dimerization may be the rate-limiting step in the transport from the endoplasmic reticulum to the Golgi complex. For lactase-phlorizin hydrolase, the posttranslational processing includes a proteolytic cleavage of its high molecular weight precursor. Since only the mature form and not the precursor of this enzyme could be cross-linked, formation of tightly associated dimers only takes place after transport out of the endoplasmic reticulum. Dimerization of the two brush border enzymes therefore seems to occur in different organelles of the enterocyte.

  7. HLA-G Dimers in the Prolongation of Kidney Allograft Survival

    Directory of Open Access Journals (Sweden)

    Maureen Ezeakile

    2014-01-01

    Full Text Available Human leukocyte antigen-G (HLA-G contributes to acceptance of allografts in solid organ/tissue transplantation. Most studies have determined that soluble HLA-G isoforms are systematically detected in serum/plasma of transplanted patients with significantly fewer episodes of acute and/or chronic rejection of allogeneic tissue/organ. Current models of the interactions of HLA-G and its specific receptors explain it as functioning in a monomeric form. However, in recent years, new data has revealed the ability of HLA-G to form disulfide-linked dimeric complexes with high preferential binding and functional activities. Limited data are available on the role of soluble HLA-G dimers in clinical pathological conditions. We describe here the presence of soluble HLA-G dimers in kidney transplant patients. Our study showed that a high level of HLA-G dimers in plasma and increased expression of the membrane-bound form of HLA-G on monocytes are associated with prolongation of kidney allograft survival. We also determined that the presence of soluble HLA-G dimers links to the lower levels of proinflammatory cytokines, suggesting a potential role of HLA-G dimers in controlling the accompanying inflammatory state.

  8. Solution structure of the dimeric cytoplasmic domain of syndecan-4

    DEFF Research Database (Denmark)

    Shin, J; Lee, W; Lee, D

    2001-01-01

    cytoplasmic domain is dependent on its oligomeric status, the conformation of the syndecan-4 cytoplasmic domain itself is important in the understanding of its biological roles. Gel filtration results show that the syndecan-4 cytoplasmic domain (4L) itself forms a dimer stabilized by ionic interactions......The syndecans, transmembrane proteoglycans which are involved in the organization of cytoskeleton and/or actin microfilaments, have important roles as cell surface receptors during cell-cell and/or cell-matrix interactions. Since previous studies indicate that the function of the syndecan-4...... in the center of the dimeric twist similar to our previously reported 4V structure. The overall topology of the central variable region within the 4L structure is very similar to that of 4V complexed with the phosphatidylinositol 4,5-bisphosphate; however, the intersubunit interaction mode is affected...

  9. Antiviral activity of α-helical stapled peptides designed from the HIV-1 capsid dimerization domain

    Directory of Open Access Journals (Sweden)

    Cowburn David

    2011-05-01

    Full Text Available Abstract Background The C-terminal domain (CTD of HIV-1 capsid (CA, like full-length CA, forms dimers in solution and CTD dimerization is a major driving force in Gag assembly and maturation. Mutations of the residues at the CTD dimer interface impair virus assembly and render the virus non-infectious. Therefore, the CTD represents a potential target for designing anti-HIV-1 drugs. Results Due to the pivotal role of the dimer interface, we reasoned that peptides from the α-helical region of the dimer interface might be effective as decoys to prevent CTD dimer formation. However, these small peptides do not have any structure in solution and they do not penetrate cells. Therefore, we used the hydrocarbon stapling technique to stabilize the α-helical structure and confirmed by confocal microscopy that this modification also made these peptides cell-penetrating. We also confirmed by using isothermal titration calorimetry (ITC, sedimentation equilibrium and NMR that these peptides indeed disrupt dimer formation. In in vitro assembly assays, the peptides inhibited mature-like virus particle formation and specifically inhibited HIV-1 production in cell-based assays. These peptides also showed potent antiviral activity against a large panel of laboratory-adapted and primary isolates, including viral strains resistant to inhibitors of reverse transcriptase and protease. Conclusions These preliminary data serve as the foundation for designing small, stable, α-helical peptides and small-molecule inhibitors targeted against the CTD dimer interface. The observation that relatively weak CA binders, such as NYAD-201 and NYAD-202, showed specificity and are able to disrupt the CTD dimer is encouraging for further exploration of a much broader class of antiviral compounds targeting CA. We cannot exclude the possibility that the CA-based peptides described here could elicit additional effects on virus replication not directly linked to their ability to bind

  10. Proteolysis of truncated hemolysin A yields a stable dimerization interface

    Energy Technology Data Exchange (ETDEWEB)

    Novak, Walter R.P.; Bhattacharyya, Basudeb; Grilley, Daniel P.; Weaver, Todd M. (Wabash); (UW)

    2017-02-21

    Wild-type and variant forms of HpmA265 (truncated hemolysin A) fromProteus mirabilisreveal a right-handed, parallel β-helix capped and flanked by segments of antiparallel β-strands. The low-salt crystal structures form a dimeric structureviathe implementation of on-edge main-chain hydrogen bonds donated by residues 243–263 of adjacent monomers. Surprisingly, in the high-salt structures of two variants, Y134A and Q125A-Y134A, a new dimeric interface is formedviamain-chain hydrogen bonds donated by residues 203–215 of adjacent monomers, and a previously unobserved tetramer is formed. In addition, an eight-stranded antiparallel β-sheet is formed from the flap regions of crystallographically related monomers in the high-salt structures. This new interface is possible owing to additional proteolysis of these variants after Tyr240. The interface formed in the high-salt crystal forms of hemolysin A variants may mimic the on-edge β-strand positioning used in template-assisted hemolytic activity.

  11. Biotransformation and Cytotoxic Activity of Guaiacol Dimer

    Directory of Open Access Journals (Sweden)

    Galuh Widiyarti

    2014-07-01

    Full Text Available Guaiacol, a phenolic compound is known as an anticancer. Dimerization of guaiacol has been done by biotransformation using peroxidase enzyme as biocatalyst. This enzyme was isolated from Indonesian plant, kailan (Brassica oleraceae var. alboglabra. Analysis of dimerization product was carried out by TLC, IR, LC-MS, and NMR. Whilst analysis of in-vitro cytotoxic activity was carried out by MTT method against breast cancer T47D and MCF7 cells. The result showed that the dimerization reaction gave O-para dehydroguaiacol. The in-vitro cytotoxic activity analysis showed that O-para dehydroguaiacol compound has potency as anti-breast cancer.

  12. Ortho and para hydrogen dimers on G/SiC(0001): combined STM and DFT study.

    Science.gov (United States)

    Merino, P; Švec, M; Martínez, J I; Mutombo, P; Gonzalez, C; Martín-Gago, J A; de Andres, P L; Jelinek, P

    2015-01-01

    The hydrogen (H) dimer structures formed upon room-temperature H adsorption on single layer graphene (SLG) grown on SiC(0001) are addressed using a combined theoretical-experimental approach. Our study includes density functional theory (DFT) calculations for the full (6√3 × 6√3)R30° unit cell of the SLG/SiC(0001) substrate and atomically resolved scanning tunneling microscopy images determining simultaneously the graphene lattice and the internal structure of the H adsorbates. We show that H atoms normally group in chemisorbed coupled structures of different sizes and orientations. We make an atomic scale determination of the most stable experimental geometries, the small dimers and ellipsoid-shaped features, and we assign them to hydrogen adsorbed in para dimers and ortho dimers configuration, respectively, through comparison with the theory.

  13. Structural proof of a dimeric positive modulator bridging two identical AMPA receptor-binding sites

    DEFF Research Database (Denmark)

    Kaae, Birgitte Høiriis; Harpsøe, Kasper; Kastrup, Jette Sandholm Jensen

    2007-01-01

    have dramatically increased potencies, more than three orders of magnitude higher than the corresponding monomers. Dimer (R,R)-2a was cocrystallized with the GluR2-S1S2J construct, and an X-ray crystallographic analysis showed (R,R)-2a to bridge two identical binding pockets on two neighboring GluR2......Dimeric positive allosteric modulators of ionotropic glutamate receptors were designed, synthesized, and characterized pharmacologically in electrophysiological experiments. The designed compounds are dimers of arylpropylsulfonamides and have been constructed without a linker. The monomeric...... arylpropylsulfonamides were derived from known modulators and target the cyclothiazide-binding site at the AMPA receptors. The three stereoisomers--R,R, meso, and S,S--of the two constructed dimers were prepared, and in vitro testing showed the R,R forms to be the most potent stereoisomers. The biarylpropylsulfonamides...

  14. Transformations of griseofulvin in strong acidic conditions--crystal structures of 2'-demethylgriseofulvin and dimerized griseofulvin.

    Science.gov (United States)

    Leśniewska, Barbara; Jebors, Said; Coleman, Anthony W; Suwińska, Kinga

    2012-03-01

    The structure of griseofulvic acid, C16H15ClO6, at 100 K has orthorhombic (P2(1)2(1)2) symmetry. It is of interest with respect to biological activity. The structure displays intermolecular O-H...O, C-H...O hydrogen bonding as well as week C-H...pi and pi...pi interactions. In strong acidic conditions the griseofulvin undergoes dimerization. The structure of dimerized griseofulvin, C34H32C12O12 x C2H6O x H2O, at 100 K has monoclinic (P2(1)) symmetry. The molecule crystallized as a solvate with one ethanol and one water molecule. The dimeric molecules form intermolecular O-H...O hydrogen bonds to solvents molecules only but they interact via week C-H...O, C-H...pi, C-Cl...pi and pi...pi interactions with other dimerized molecules.

  15. Overexpression and characterization of dimeric and tetrameric forms ...

    Indian Academy of Sciences (India)

    Serine hydroxymethyltransferase (SHMT), a pyridoxal-5′-phosphate (PLP) dependent enzyme catalyzes the interconversion of L-Ser and Gly using tetrahydrofolate as a substrate. The gene encoding for SHMT was amplified by PCR from genomic DNA of Bacillus stearothermophilus and the PCR product was cloned and ...

  16. Overexpression and characterization of dimeric and tetrameric forms ...

    Indian Academy of Sciences (India)

    Unknown

    Matthews R G, Drummond J T and Webb H K 1998 Cobalamin- dependent methionine synthase and serine hydroxymethyl- transferase: targets for chemotherapeutic intervention?; Adv. Enzyme Regul. 38 377–392. McClung C R, Hsu M, Painter J E , Gagne J M, Karlsberg S D and Salome P A 2000 Integrated temporal ...

  17. Dimerization of 3He in 3He-4He dilute mixtures filling narrow channels

    International Nuclear Information System (INIS)

    Bashkin, Eugene P.; Wojdylo, John

    2000-01-01

    We consider dimerization of 3 He in a dilute solution of 3 He in superfluid 4 He filling straight narrow channels that can be found in nanoscale porous media. Dimer formation is facilitated by the restricted geometry and occurs despite the fact that in bulk fluid the interparticle interaction is too weak to lead to a bound state. Dimerization results in the effective 'bosonization' of the system: a Bose quantum fluid of ( 3 He) 2 arises in place of the 3 He Fermi component. At high temperatures, when the 3 He impurity quasiparticles form a Maxwell-Boltzmann gas, a drastic change in the thermodynamics occurs due to the presence of dimers. The specific heat and magnetic susceptibility of the 3 He component, which we calculate at arbitrary degrees of dimerization, show a marked deviation from behavior expected of an undimerized 3 He component. We show that the binding energy--which depends on the channel width--is expected to be sufficiently high to make experimental observation feasible. The presence of ( 3 He) 2 dimers gives rise to an extra absorption mechanism for first sound propagating through the superfluid 4 He, due to resonant absorption and decay of dimers in the acoustic field. We have calculated the absorption coefficient. Several experiments suggest themselves, utilizing, perhaps, K-L zeolites or carbon nanotubes. If the dimers themselves turn out to be attractive, then quadrumers may appear: it may even be the case that a single 3 He polymer will form over the entire length of the channel

  18. Synthesis of new dimeric carvacrol compounds

    Directory of Open Access Journals (Sweden)

    Uttam B. More

    2008-12-01

    Full Text Available The polymer supported carvacrol anion was reacted with 1,2-dibromoethane, 1,4-dibromoethane, oxalyl dichloride, malonyl dichloride, succinyl dichloride, glutaroyl dichloride, and adipoyl dichloride to afford the corresponding dimeric carvacryl ethers or esters

  19. Neutral dipole-dipole dimers: A new field in science

    Science.gov (United States)

    Kosower, Edward M.; Borz, Galina

    2018-03-01

    Dimer formation with dipole neutralization produces species such as low polarity water (LPW) compatible with hydrophobic surfaces (Phys. Chem. Chem. Phys. 2015, 17, 24895-24900) Dimerization and dipole neutralization occurs for N-methylacetamide on polyethylene, a behavior drastically different from its contortions in acetonitrile on AgBr:AgCl planar crystals (AgX) (ChemPhysChem 2014, 15, 3598-3607). The weak infrared absorption of the amide dimer on polyethylene is shown experimentally. Dimerization of palmitic acid is shown along with some of the many ramifications for intracellular systems. Polyoligomers of water are present on polyethylene surfaces. Some high resolution spectra of three of the polyoligomers of water are shown along with a mechanistic scheme for polyoligomer formation and dissolution. The structures of some of the oligomers are known from spectroscopic studies of water on AgX. The scope of the article begins with PE, generally accepted as hydrophobic. The IR of PE revealed not only that water was present but that it appeared in two forms, oligomers (O) and polyoligomers (PO). How did we recognize what they were? These species had been observed as especially strong "marker" peaks in the spectra1 of water placed on planar AgX, a platform developed by Katzir and his coworkers [6]. But there was a problem: the proximity to PE of oligomers with substantial (calculated) dipole moments and thus polarity, including cyclic hexamers of water (chair and boat forms), the cyclic pentamer, the books I and II, and the cyclic trimer [7a]. Another link was needed, a role perfectly fit by the already cited low polarity water (LPW). The choice was experimentally supported by the detection of low intensity absorption in the bending region.Some important generalities flow from these results. What other dimers might be present in the biological or chemical world? Palmitic acid dimer (PAD) would be a candidate for decreasing the polarity of the acid (PA). Another

  20. The two-state dimer receptor model: a general model for receptor dimers.

    Science.gov (United States)

    Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferrada, Carla; Ferré, Sergi; Fuxe, Kjell; Cortés, Antoni; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

    2006-06-01

    Nonlinear Scatchard plots are often found for agonist binding to G-protein-coupled receptors. Because there is clear evidence of receptor dimerization, these nonlinear Scatchard plots can reflect cooperativity on agonist binding to the two binding sites in the dimer. According to this, the "two-state dimer receptor model" has been recently derived. In this article, the performance of the model has been analyzed in fitting data of agonist binding to A(1) adenosine receptors, which are an example of receptor displaying concave downward Scatchard plots. Analysis of agonist/antagonist competition data for dopamine D(1) receptors using the two-state dimer receptor model has also been performed. Although fitting to the two-state dimer receptor model was similar to the fitting to the "two-independent-site receptor model", the former is simpler, and a discrimination test selects the two-state dimer receptor model as the best. This model was also very robust in fitting data of estrogen binding to the estrogen receptor, for which Scatchard plots are concave upward. On the one hand, the model would predict the already demonstrated existence of estrogen receptor dimers. On the other hand, the model would predict that concave upward Scatchard plots reflect positive cooperativity, which can be neither predicted nor explained by assuming the existence of two different affinity states. In summary, the two-state dimer receptor model is good for fitting data of binding to dimeric receptors displaying either linear, concave upward, or concave downward Scatchard plots.

  1. Retroviral RNA Dimerization: From Structure to Functions

    Directory of Open Access Journals (Sweden)

    Noé Dubois

    2018-03-01

    Full Text Available The genome of the retroviruses is a dimer composed by two homologous copies of genomic RNA (gRNA molecules of positive polarity. The dimerization process allows two gRNA molecules to be non-covalently linked together through intermolecular base-pairing. This step is critical for the viral life cycle and is highly conserved among retroviruses with the exception of spumaretroviruses. Furthermore, packaging of two gRNA copies into viral particles presents an important evolutionary advantage for immune system evasion and drug resistance. Recent studies reported RNA switches models regulating not only gRNA dimerization, but also translation and packaging, and a spatio-temporal characterization of viral gRNA dimerization within cells are now at hand. This review summarizes our current understanding on the structural features of the dimerization signals for a variety of retroviruses (HIVs, MLV, RSV, BLV, MMTV, MPMV…, the mechanisms of RNA dimer formation and functional implications in the retroviral cycle.

  2. Direct assessment of the effect of the Gly380Arg achondroplasia mutation on FGFR3 dimerization using quantitative imaging FRET.

    Directory of Open Access Journals (Sweden)

    Jesse Placone

    Full Text Available The Gly380Arg mutation in FGFR3 is the genetic cause for achondroplasia (ACH, the most common form of human dwarfism. The mutation has been proposed to increase FGFR3 dimerization, but the dimerization propensities of wild-type and mutant FGFR3 have not been compared. Here we use quantitative imaging FRET to characterize the dimerization of wild-type FGFR3 and the ACH mutant in plasma membrane-derived vesicles from HEK293T cells. We demonstrate a small, but statistically significant increase in FGFR3 dimerization due to the ACH mutation. The data are consistent with the idea that the ACH mutation causes a structural change which affects both the stability and the activity of FGFR3 dimers in the absence of ligand.

  3. Direct Assessment of the Effect of the Gly380Arg Achondroplasia Mutation on FGFR3 Dimerization Using Quantitative Imaging FRET

    Science.gov (United States)

    Placone, Jesse; Hristova, Kalina

    2012-01-01

    The Gly380Arg mutation in FGFR3 is the genetic cause for achondroplasia (ACH), the most common form of human dwarfism. The mutation has been proposed to increase FGFR3 dimerization, but the dimerization propensities of wild-type and mutant FGFR3 have not been compared. Here we use quantitative imaging FRET to characterize the dimerization of wild-type FGFR3 and the ACH mutant in plasma membrane-derived vesicles from HEK293T cells. We demonstrate a small, but statistically significant increase in FGFR3 dimerization due to the ACH mutation. The data are consistent with the idea that the ACH mutation causes a structural change which affects both the stability and the activity of FGFR3 dimers in the absence of ligand. PMID:23056398

  4. Aromatic C-Nitroso Compounds and Their Dimers: A Model for Probing the Reaction Mechanisms in Crystalline Molecular Solids

    Directory of Open Access Journals (Sweden)

    Ivana Biljan

    2017-12-01

    Full Text Available This review is focused on the dimerization and dissociation of aromatic C-nitroso compounds and their dimers, the reactions that could be used as a convenient model for studying the thermal organic solid-state reaction mechanisms. This molecular model is simple because it includes formation or breaking of only one covalent bond between two nitrogen atoms. The crystalline molecular solids of nitroso dimers (azodioxides dissociate by photolysis under the cryogenic conditions, and re-dimerize by slow warming. The thermal re-dimerization reaction is examined under the different topotactic conditions in crystals: disordering, surface defects, and phase transformations. Depending on the conditions, and on the molecular structure, aromatic C-nitroso compounds can associate to form one-dimensional polymeric structures and are able to self-assemble on gold surfaces.

  5. Investigation of the hydrated 7-hydroxy-4-methylcoumarin dimer by combined IR/UV spectroscopy

    International Nuclear Information System (INIS)

    Stamm, A.; Schwing, K.; Gerhards, M.

    2014-01-01

    The first molecular beam investigations on a coumarin dimer and clusters of a coumarin dimer with water both in the neutral (S 0 ) and cationic (D 0 ) electronic ground state are performed. The structure and structural changes due to ionization of the isolated 7-hydroxy-4-methylcoumarin dimer (7H4MC) 2 as well as its mono- and dihydrate (7H4MC) 2 (H 2 O) 1-2 are analyzed by applying combined IR/UV spectroscopy compared with density functional theory calculations. In case of the neutral dimer of 7H4MC a doubly hydrogen-bonded structure is formed. This doubly hydrogen-bonded arrangement opens to a singly hydrogen-bonded structure in the ion presenting a rearrangement reaction within an isolated dimer. By attaching one or two water molecules to the neutral 7H4MC dimer water is inserted into the hydrogen bonds. In contrast to the non-hydrated species this general binding motif with water in a bridging function does not change via ionization but especially for the dihydrate the spatial arrangement of the two 7H4MC units changes strengthening the interaction between the aromatic chromophores. The presented analyses illustrate the strong dependence of binding motifs as a function of successive hydration and charge including a rearrangement reaction

  6. Dimerization interface of 3-hydroxyacyl-CoA dehydrogenase tunes the formation of its catalytic intermediate.

    Directory of Open Access Journals (Sweden)

    Yingzhi Xu

    Full Text Available 3-Hydroxyacyl-CoA dehydrogenase (HAD, EC 1.1.1.35 is a homodimeric enzyme localized in the mitochondrial matrix, which catalyzes the third step in fatty acid β-oxidation. The crystal structures of human HAD and subsequent complexes with cofactor/substrate enabled better understanding of HAD catalytic mechanism. However, numerous human diseases were found related to mutations at HAD dimerization interface that is away from the catalytic pocket. The role of HAD dimerization in its catalytic activity needs to be elucidated. Here, we solved the crystal structure of Caenorhabditis elegans HAD (cHAD that is highly conserved to human HAD. Even though the cHAD mutants (R204A, Y209A and R204A/Y209A with attenuated interactions on the dimerization interface still maintain a dimerization form, their enzymatic activities significantly decrease compared to that of the wild type. Such reduced activities are in consistency with the reduced ratios of the catalytic intermediate formation. Further molecular dynamics simulations results reveal that the alteration of the dimerization interface will increase the fluctuation of a distal region (a.a. 60-80 that plays an important role in the substrate binding. The increased fluctuation decreases the stability of the catalytic intermediate formation, and therefore the enzymatic activity is attenuated. Our study reveals the molecular mechanism about the essential role of the HAD dimerization interface in its catalytic activity via allosteric effects.

  7. Structure of a Rabbit Muscle Fructose-1,6-Bisphosphate Aldolase A Dimer Variant

    Energy Technology Data Exchange (ETDEWEB)

    Sherawat,M.; Tolan, D.; Allen, K.

    2008-01-01

    Fructose-1,6-bisphosphate aldolase (aldolase) is an essential enzyme in glycolysis and gluconeogenesis. In addition to this primary function, aldolase is also known to bind to a variety of other proteins, a property that may allow it to perform 'moonlighting' roles in the cell. Although monomeric and dimeric aldolases possess full catalytic activity, the enzyme occurs as an unusually stable tetramer, suggesting a possible link between the oligomeric state and these noncatalytic cellular roles. Here, the first high-resolution X-ray crystal structure of rabbit muscle D128V aldolase, a dimeric form of aldolase mimicking the clinically important D128G mutation in humans associated with hemolytic anemia, is presented. The structure of the dimer was determined to 1.7 Angstroms resolution with the product DHAP bound in the active site. The turnover of substrate to produce the product ligand demonstrates the retention of catalytic activity by the dimeric aldolase. The D128V mutation causes aldolase to lose intermolecular contacts with the neighboring subunit at one of the two interfaces of the tetramer. The tertiary structure of the dimer does not significantly differ from the structure of half of the tetramer. Analytical ultracentrifugation confirms the occurrence of the enzyme as a dimer in solution. The highly stable structure of aldolase with an independent active site is consistent with a model in which aldolase has evolved as a multimeric scaffold to perform other noncatalytic functions.

  8. Quantitation of pyrimidine dimers in DNA from UVB-irradiated alfalfa (Medicago sativa L.) seedlings

    International Nuclear Information System (INIS)

    Quaite, F.E.; Sutherland, B.M.; Sutherland, J.C.

    1991-01-01

    Depletion of stratospheric ozone will increase the solar ultraviolet radiation in the range from 290-320 nm (UVB) that reaches the surface of the earth, placing an increased UV burden on exposed organisms. One consequence of increased UVB may be decreased productivity of crop plants. A principal lesion caused by UV in DNA is the cyclobutyl pyrimidine dimer. We have adapted a method for measuring these dimers in nanogram quantities of non-radioactive DNA for use in UV-irradiated plants. We find that biologically relevant doses of broad band UVB radiation induce easily detectable frequencies of pyrimidine dimers in the DNA of irradiated alfalfa sprout leaves and that the dose response for dimer formation is linear up to doses of at least 690 J/m 2 . We also find easily measurable frequencies of dimers in the leaves of seedlings grown in glass filtered sunlight but not exposed to additional UVB, suggesting that significant number of dimers are formed in plants exposed to normal sunlight. 27 refs., 3 figs., 1 tab

  9. Investigation of the hydrated 7-hydroxy-4-methylcoumarin dimer by combined IR/UV spectroscopy.

    Science.gov (United States)

    Stamm, A; Schwing, K; Gerhards, M

    2014-11-21

    The first molecular beam investigations on a coumarin dimer and clusters of a coumarin dimer with water both in the neutral (S0) and cationic (D0) electronic ground state are performed. The structure and structural changes due to ionization of the isolated 7-hydroxy-4-methylcoumarin dimer (7H4MC)2 as well as its mono- and dihydrate (7H4MC)2(H2O)1-2 are analyzed by applying combined IR/UV spectroscopy compared with density functional theory calculations. In case of the neutral dimer of 7H4MC a doubly hydrogen-bonded structure is formed. This doubly hydrogen-bonded arrangement opens to a singly hydrogen-bonded structure in the ion presenting a rearrangement reaction within an isolated dimer. By attaching one or two water molecules to the neutral 7H4MC dimer water is inserted into the hydrogen bonds. In contrast to the non-hydrated species this general binding motif with water in a bridging function does not change via ionization but especially for the dihydrate the spatial arrangement of the two 7H4MC units changes strengthening the interaction between the aromatic chromophores. The presented analyses illustrate the strong dependence of binding motifs as a function of successive hydration and charge including a rearrangement reaction.

  10. Dislocations and vacancies in two-dimensional mixed crystals of spheres and dimers

    KAUST Repository

    Gerbode, Sharon J.

    2010-10-15

    In colloidal crystals of spheres, dislocation motion is unrestricted. On the other hand, recent studies of relaxation in crystals of colloidal dimer particles have demonstrated that the dislocation dynamics in such crystals are reminiscent of glassy systems. The observed glassy dynamics arise as a result of dislocation cages formed by certain dimer orientations. In the current study, we use experiments and simulations to investigate the transition that arises when a pure sphere crystal is doped with an increasing concentration of dimers. Specifically, we focus on both dislocation caging and vacancy motion. Interestingly, we find that any nonzero fraction of dimers introduces finite dislocation cages, suggesting that glassy dynamics are present for any mixed crystal. However, we have also identified a vacancy-mediated uncaging mechanism for releasing dislocations from their cages. This mechanism is dependent on vacancy diffusion, which slows by orders of magnitude as the dimer concentration is increased. We propose that in mixed crystals with low dimer concentrations vacancy diffusion is fast enough to uncage dislocations and delay the onset of glassy dislocation dynamics. © 2010 The American Physical Society.

  11. Formation of oxidative and non-oxidative dimers in metallothioneins: Implications for charge-state analysis for structural determination.

    Science.gov (United States)

    Irvine, Gordon W; Heinlein, Lina; Renaud, Justin B; Sumarah, Mark W; Stillman, Martin J

    2017-12-30

    Metallothioneins (MTs) are a class of dynamic proteins that have been investigated extensively using mass spectrometric methods due to their amenability to ionization. Here we detect the formation of oxidative and non-oxidative MT dimers using high-resolution mass spectrometry (HRMS) which has previously been overlooked with lower-resolution techniques. Recombinant human MT1a and its isolated domain fragments were analyzed by high-resolution Thermo Q-Exactive and Bruker time-of-flight (TOF) mass spectrometers. Covalent Cys modification was performed using N-ethylmalemide to probe the effect of Cys oxidation on dimer formation. Dimerization was detected in the analysis of select charge states of Zn 7 MT and apo-βMT. Specifically, high resolution (140 k) revealed the +6 dimer peaks overlapping with the +3 charge state, but not with the other charge states (+4, +5, +6). The proteins with covalently modified Cys did not show dimer formation in any of their charge states. Apo-α and apo-βαMT also did not form dimers under the conditions tested. Dimerization of MT was detected for zinc metalated and certain apo-MT forms with HRMS, which was not seen with lower-resolution techniques. These dimers appear overlapped only with certain charge states, confounding their analysis for structural characterization of MTs. The Zn-MT dimers appeared to be non-oxidative; however, the formation of dimers in the apo-protein is likely dependent on Cys oxidation. Copyright © 2017 John Wiley & Sons, Ltd.

  12. D-dimers (DD) in CVST.

    Science.gov (United States)

    Wang, Hui Fang; Pu, Chuan Qiang; Yin, Xi; Tian, Cheng Lin; Chen, Ting; Guo, Jun Hong; Shi, Qiang

    2017-06-01

    We were interested in further confirming whether D-dimers (DD) are indeed elevated in cerebral venous sinus thrombosis (CVST) as reported in those studies. CVST patients who had a plasma D-dimer test (139 cases) were included and divided into two groups: elevated D-dimer group (EDG) (>0.5 μg/mL; 65 cases) and normal D-dimer group (NDG) (≤0.5 μg/mL; 74 cases). The two groups were compared in terms of demographic data, clinical manifestation, laboratory and imaging data, using inferential statistical methods. The chi-squared and Fisher exact test showed that, compared to the NDG (74 cases), patients with elevated D-dimer levels were more likely to have a shorter symptom duration (SD) (30 ± 83.9 versus 90 ± 58.9 d, p = 0.003), more risk factors (75.4% versus 52.7%, p = 0.006), higher multiple venous sinus involvement (75.4% versus 59.5%, p = 0.037), increased fibrinogen (43.1% versus 18.9%, p = 0.037) and higher levels of blood glucose (18.3% versus 11%, p = 0.037). According to correlation analyses, D-dimer levels were positively correlated with number of venous sinuses involvement (NVS) (r = 0.321, p = 0.009) in the EDG. Multivariate logistic regression analysis showed that SD (OR, 0.025; 95% CI, 1.324-6.043; p = 0.000), NVS (OR, 1.573; 95% CI, 1.15-2.151; p = 0.005) and risk factors (OR, 3.321; 95% CI, 1.451-7.564; p = 0.004) were significantly different between the two groups. D-dimer is elevated in patients with acute/subacute CVST.

  13. Camelliin B and nobotanin I, macrocyclic ellagitannin dimers and related dimers, and their antitumor activity.

    Science.gov (United States)

    Yoshida, T; Chou, T; Haba, K; Okano, Y; Shingu, T; Miyamoto, K; Koshiura, R; Okuda, T

    1989-11-01

    Camelliin B and nobotanin I, dimeric hydrolyzable tannins of a new class having macrocyclic structures, were isolated from Camellia japonica and Heterocentron roseum, respectively. Nobotanin G and H of the structures related to nobotanin I, were also obtained from H. roseum. Camelliin B and also woodfordin C, a macrocyclic dimer from Woodfordia fruticosa, exhibited marked host-mediated antitumor activities.

  14. Characterization of human immunodeficiency virus type 2 envelope glycoproteins: Dimerization of the glycoprotein precursor during processing

    International Nuclear Information System (INIS)

    Rey, M.A.; Krust, B.; Laurent, A.G.; Montagnier, L.; Hovanessian, A.G.

    1989-01-01

    For glycoproteins with apparent molecular weights of 300,000, 140,000, 125,000, and 36,000 (gp300, gp140, gp125, and gp36) were detectable in human immunodeficiency virus type 2 (HIV-2)-infected cells. They have identical isoelectric points, suggesting that gp300 might be a dimeric form of the immature precursor, gp140. The purified gp300 can be dissociated in a slightly acidic buffer to give rise to monomers of 140,000 molecular weight. Such dissociated monomers and the purified gp140 showed identical patterns of polypeptides after partial proteolysis with Staphylococcus aureus V8 protease. Pulse-chase experiments indicated that gp300 is formed after synthesis of gp140 and before the detection of the mature external envelope glycoprotein, gp125. These results were confirmed by using various inhibitors of glycosylation and inhibitors of trimming enzymes. Dimer formation of the envelope glycoprotein precursor was also observed in cells infected with simian immunodeficiency virus (SIV), a virus closely related to HIV-2. On the other hand, the envelope glycoprotein precursor of HIV-1 did not form a dimer during its processing. Therefore, dimer formation seems to be a specific property of HIV-2 and SIV envelope gene expression. Such transient dimerization of the glycoprotein precursor might be required for its efficient transport to the Golgi apparatus and for its processing

  15. Plasmonic nanospherical dimers for color pixels

    KAUST Repository

    Alrasheed, Salma

    2018-04-20

    Display technologies are evolving more toward higher resolution and miniaturization. Plasmonic color pixels can offer solutions to realize such technologies due to their sharp resonances and selective scattering and absorption at particular wavelengths. Metal nanosphere dimers are capable of supporting plasmon resonances that can be tuned to span the entire visible spectrum. In this article, we demonstrate numerically bright color pixels that are highly polarized and broadly tuned using periodic arrays of metal nanosphere dimers on a glass substrate. We show that it is possible to obtain RGB pixels in the reflection mode. The longitudinal plasmon resonance of nanosphere dimers along the axis of the dimer is the main contributor to the color of the pixel, while far-field diffractive coupling further enhances and tunes the plasmon resonance. The computational method used is the finite-difference time-domain method. The advantages of this approach include simplicity of the design, bright coloration, and highly polarized function. In addition, we show that it is possible to obtain different colors by varying the angle of incidence, the periodicity, the size of the dimer, the gap, and the substrate thickness.

  16. Multiply charged monopoles in cubic dimer model

    Science.gov (United States)

    Ganesh Jaya, Sreejith; Powell, Stephen

    2015-03-01

    The classical cubic dimer model is a 3D statistical mechanical system whose degrees of freedom are dimers that occupy the edges between nearest neighbour vertices of a cubic lattice. Dimer occupancies are subject to the local constraint that every vertex is associated with exactly one dimer. In the presence of an aligning interaction, it is known that the system exhibits an unconventional continuous thermal phase transition from a symmetry broken columnar phase to a Coulomb-phase. The transition is in the NCCP1 universality class, which also describes the Neel-VBS transition in the JQ model and the S =1/2 Heisenberg model with suppression of hedgehog defects. Using Monte-Carlo simulations of a pair of defects in a background of fluctuating dimers, we calculate the scaling exponents for fugacities of monopole defects of charge Q = 2 and 3 at this critical point. Our estimates suggest that Q = 3 monopoles are relevant and could therefore drive the JQ model away from the NCCP1 critical point on a hexagonal lattice.

  17. A single β-octyl glucoside molecule induces HIV-1 Nef dimer formation in the absence of partner protein binding.

    Directory of Open Access Journals (Sweden)

    Mousheng Wu

    Full Text Available The HIV-1 Nef accessory protein is essential for viral pathogenicity and AIDS progression. Nef forms complexes with multiple host cell factors to facilitate viral replication and promote immune escape of HIV-infected cells. Previous X-ray crystal structures demonstrate that Nef forms homodimers, the orientation of which are influenced by host cell binding partners. In cell-based fluorescence complementation assays, Nef forms homodimers at the plasma membrane. However, recombinant Nef proteins often exist as monomers in solution, suggesting that membrane interaction may also trigger monomer to dimer transitions. In this study, we show that monomeric Nef core proteins can be induced to form dimers in the presence of low concentrations of the non-ionic surfactant, β-octyl glucoside (βOG. X-ray crystallography revealed that a single βOG molecule is present in the Nef dimer, with the 8-carbon acyl chain of the ligand binding to a hydrophobic pocket formed by the dimer interface. This Nef-βOG dimer interface involves helix αB, as observed in previous dimer structures, as well as a helix formed by N-terminal residues 54-66. Nef dimer formation is stabilized in solution by the addition of βOG, providing biochemical validation for the crystal structure. These observations together suggest that the interaction with host cell lipid mediators or other hydrophobic ligands may play a role in Nef dimerization, which has been previously linked to multiple Nef functions including host cell protein kinase activation, CD4 downregulation, and enhancement of HIV-1 replication.

  18. Structure of a rabbit muscle fructose-1, 6-bisphosphate aldolase A dimer variant

    Energy Technology Data Exchange (ETDEWEB)

    Sherawat, Manashi [Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2394 (United States); Tolan, Dean R., E-mail: tolan@bu.edu [Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215 (United States); Allen, Karen N., E-mail: tolan@bu.edu [Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2394 (United States)

    2008-05-01

    The X-ray crystallographic structure of a dimer variant of fructose-1, 6-bisphosphate aldolase demonstrates a stable oligomer that mirrors half of the native tetramer. The presence of product demonstrates that this is an active form. Fructose-1, 6-bisphosphate aldolase (aldolase) is an essential enzyme in glycolysis and gluconeogenesis. In addition to this primary function, aldolase is also known to bind to a variety of other proteins, a property that may allow it to perform ‘moonlighting’ roles in the cell. Although monomeric and dimeric aldolases possess full catalytic activity, the enzyme occurs as an unusually stable tetramer, suggesting a possible link between the oligomeric state and these noncatalytic cellular roles. Here, the first high-resolution X-ray crystal structure of rabbit muscle D128V aldolase, a dimeric form of aldolase mimicking the clinically important D128G mutation in humans associated with hemolytic anemia, is presented. The structure of the dimer was determined to 1.7 Å resolution with the product DHAP bound in the active site. The turnover of substrate to produce the product ligand demonstrates the retention of catalytic activity by the dimeric aldolase. The D128V mutation causes aldolase to lose intermolecular contacts with the neighboring subunit at one of the two interfaces of the tetramer. The tertiary structure of the dimer does not significantly differ from the structure of half of the tetramer. Analytical ultracentrifugation confirms the occurrence of the enzyme as a dimer in solution. The highly stable structure of aldolase with an independent active site is consistent with a model in which aldolase has evolved as a multimeric scaffold to perform other noncatalytic functions.

  19. Photoionization of helium dimers; Photoionisation von Heliumdimeren

    Energy Technology Data Exchange (ETDEWEB)

    Havermeier, Tilo

    2010-06-09

    The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)

  20. Dimerization specificity of adult and neonatal chicken skeletal muscle myosin heavy chain rods.

    Science.gov (United States)

    Singh, Sheetal; Bandman, Everett

    2006-04-18

    The dimerization specificity of the recombinantly expressed and purified rod domain of adult and neonatal chicken myosin heavy chain was analyzed using metal chelation chromatography. Our results indicate that full-length adult and neonatal rods preferentially formed homodimers when renatured from an equimolar mixture of the two isoforms denatured in guanidine hydrochloride. The contribution made toward the dimerization specificity by subdomains of the rod has been addressed by making a chimeric protein consisting of the subfragment 2 (S2) region of the adult isoform and the light meromyosin region of the neonatal isoform. The proportion of heterodimers formed in exchange experiments between the chimera and the neonatal and adult rods rose with increase in the sequence homology between the two exchanging proteins. This suggests that multiple regions of the rod domain of chicken MyHC including S2 can contribute toward dimerization specificity.

  1. Active thermochemical tables: water and water dimer.

    Science.gov (United States)

    Ruscic, Branko

    2013-11-21

    A new partition function for water dimer in the temperature range 200-500 K was developed by exploiting the equations of state for real water vapor, liquid water, and ice, and demonstrated to be significantly more accurate than any proposed so far in the literature. The new partition function allows the Active Thermochemical Tables (ATcT) approach to be applied on the available experimental and theoretical data relating to water dimer thermochemistry, leading to accurate water dimer enthalpies of formation of -499.115 ± 0.052 kJ mol(-1) at 298.15 K and -491.075 ± 0.080 kJ mol(-1) at 0 K. With the current ATcT enthalpy of formation of the water monomer, -241.831 ± 0.026 kJ mol(-1) at 298.15 K (-238.928 kJ mol(-1) at 0 K), this leads to the dimer bond dissociation enthalpy at 298.15 K of 15.454 ± 0.074 kJ mol(-1) and a 0 K bond dissociation energy of 13.220 ± 0.096 kJ mol(-1) (1105 ± 8 cm(-1)), the latter being in perfect agreement with recent experimental and theoretical determinations. The new partition function of water dimer allows the extraction and tabulation of heat capacity, entropy, enthalpy increment, reduced Gibbs energy, enthalpy of formation, and Gibbs energy of formation. Newly developed tabulations of analogous thermochemical properties for gas-phase water monomer and for water in condensed phases are also given, allowing the computations of accurate equilibria between the dimer and monomer in the 200-500 K range of temperatures.

  2. Laser isotope separation using selective inhibition and encouragement of dimer formation

    International Nuclear Information System (INIS)

    Kivel, B.

    1979-01-01

    Method and apparatus for inhibiting dimer formation of molecules of a selected isotope type in a cooled flow of gas to enhance the effectiveness of mass difference isotope separation techniques are described. Molecules in the flow containing atoms of the selected isotope type are selectively excited by infrared radiation in order to inhibit the formation of dimers and larger clusters of such molecules, while the molecules not containing atoms of the selected, excited type are encouraged to form dimers and higher order aggregates by the cooling of the gaseous flow. The molecules with the excited isotope will predominate in monomers and will constitute the enriched product stream, while the aggregated group comprising molecules having the unexcited isotope will predominate in dimers and larger clusters of molecules, forming the tails stream. The difference in diffusion coefficientts between particles of the excited and unexcited isotopes is enhanced by the greater mass differences resulting from aggregation of unexcited particles into dimers and larger clusters. Prior art separation techniques which exploit differences in isotopic diffusion rates will consequently exhibit enhanced enrichment per stage by the utilization of the present invention

  3. On the asymptotics of dimers on tori

    OpenAIRE

    Kenyon, Richard W.; Sun, Nike; Wilson, David B.

    2013-01-01

    We study asymptotics of the dimer model on large toric graphs. Let $\\mathbb L$ be a weighted $\\mathbb{Z}^2$-periodic planar graph, and let $\\mathbb{Z}^2 E$ be a large-index sublattice of $\\mathbb{Z}^2$. For $\\mathbb L$ bipartite we show that the dimer partition function on the quotient $\\mathbb{L}/(\\mathbb{Z}^2 E)$ has the asymptotic expansion $\\exp[A f_0 + \\text{fsc} + o(1)]$, where $A$ is the area of $\\mathbb{L}/(\\mathbb{Z}^2 E)$, $f_0$ is the free energy density in the bulk, and $\\text{fsc...

  4. Factorized ground state in dimerized spin chains

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, Gian Luca, E-mail: gianluca@ifisc.uib-csic.e [Institute for Cross-Disciplinary Physics and Complex Systems, IFISC (CSIC-UIB), Campus Universitat Illes Balears, E-07122 Palma de Mallorca (Spain)

    2010-09-01

    The possibility of observing factorized ground states in dimerized spin systems is studied. A set of sufficient conditions is derived which allows one to establish whether or not it is possible to have factorization both in nearest-neighbour and long-range Hamiltonians. These conditions can be derived by forcing factorization for each of the pairwise terms of the total Hamiltonian. Due to the peculiar structure of a dimerized chain, an antiferromagnetic factorized ground state of the kind |nearr), |nearr), |nwarr), |nwarr) (forbidden in regular chains) is possible.

  5. Free radicals impair the anti-oxidative stress activity of DJ-1 through the formation of SDS-resistant dimer.

    Science.gov (United States)

    Yasuda, Tatsuki; Niki, Takeshi; Ariga, Hiroyoshi; Iguchi-Ariga, Sanae M M

    2017-04-01

    DJ-1 is a causative gene for familial Parkinson's disease (PD). Loss-of-function of DJ-1 protein is suggested to contribute to the onset of PD, but the causes of DJ-1 dysfunction remain insufficiently elucidated. In this study, we found that the SDS-resistant irreversible dimer of DJ-1 protein was formed in human dopaminergic neuroblastoma SH-SY5Y cells when the cells were exposed to massive superoxide inducers such as paraquat and diquat. The dimer was also formed in vitro by superoxide in PQ redox cycling system and hydroxyl radical produced in Fenton reaction. We, thus, found a novel phenomenon that free radicals directly affect DJ-1 to form SDS-resistant dimers. Moreover, the formation of the SDS-resistant dimer impaired anti-oxidative stress activity of DJ-1 both in cell viability assay and H 2 O 2 -elimination assay in vitro. Similar SDS-resistant dimers were steadily formed with several mutants of DJ-1 found in familial PD patients. These findings suggest that DJ-1 is impaired due to the formation of SDS-resistant dimer when the protein is directly attacked by free radicals yielded by external and internal stresses and that the DJ-1 impairment is one of the causes of sporadic PD.

  6. Chiroptical properties, binding affinity, and photostability of a conjugated zinc porphyrin dimer complexed with left-handed Z-DNA and right-handed B-DNA.

    Science.gov (United States)

    Choi, Jung Kyu; Reed, Aisha; Balaz, Milan

    2014-01-14

    We have studied the UV-vis absorption and chiroptical properties, binding affinity and photostability of a conjugated positively charged butadiyne-linked Zn(ii) porphyrin dimer bound to DNA sequence poly(dG-dC)2. Right-handed B-DNA, spermine-induced Z-DNA and Co(iii)-induced Z-DNA have been explored. Resonance light scattering (RLS) spectra showed formation of porphyrin aggregates in the presence of all DNA forms with the largest aggregates formed with B-DNA. The porphyrin dimer gave rise to induced bisignate circular dichroism (CD) signals in the presence of the left-handed Z-DNA conformations. On the other hand, the dimer stayed nearly chiroptically silent when complexed with the B-form of poly(dG-dC)2. Our results indicated that the conjugated Zn(ii) porphyrin dimer can be used as a sensor for the chiroptical detection of Z-DNA in the visible (400-500 nm) and near-infrared region of the electromagnetic spectrum (700-800 nm). The helicity of DNA had little effect on the dimer binding affinities. The photostability of the porphyrin dimer complexed with any form of DNA was higher than that of the free molecule. The porphyrin dimer bound to Z-DNA exhibited slower photobleaching than the B-DNA dimer complex.

  7. Biological consequences of cyclobutane pyrimidine dimers

    NARCIS (Netherlands)

    Vink, A.A.; Roza, L.

    2001-01-01

    In the skin many molecules may absorb ultraviolet (UV) radiation upon exposure. In particular, cellular DNA strongly absorbs shorter wavelength solar UV radiation, resulting in various types of DNA damage. Among the DNA photoproducts produced the cyclobutane pyrimidine dimers (CPDs) are predominant.

  8. Stability and Formation of Isobutylene Dimers.

    Science.gov (United States)

    Goldsmith, Robert H.

    1983-01-01

    Isobutylene is an important bulk chemical for the petroleum industry. Dimerization and hydrogenation reactions produce the standard fuel octane rating comparison. This classic chemistry is often misrepresented in modern texts, however, and this paper attempts to correlate the physical organic principles that apply. (Author)

  9. Synthesis and characterization of monomeric and dimeric ...

    African Journals Online (AJOL)

    The two complexes are isostructural, with the central metal atom lying on a crystallographic 2-fold axis. Both complexes are approximately octahedral, the coordination being provided by two trans pyridine nitrogen atoms and two cis amine nitrogen atoms from the oxime ligands, and by two cis chlorides. The dimeric ...

  10. Oligomerization state of photosynthetic core complexes is correlated with the dimerization affinity of a transmembrane helix.

    Science.gov (United States)

    Hsin, Jen; LaPointe, Loren M; Kazy, Alla; Chipot, Christophe; Senes, Alessandro; Schulten, Klaus

    2011-09-07

    In the Rhodobacter (Rba.) species of photosynthetic purple bacteria, a single transmembrane α-helix, PufX, is found within the core complex, an essential photosynthetic macromolecular assembly that performs the absorption and the initial processing of light energy. Despite its structural simplicity, many unresolved questions surround PufX, the most important of which is its location within the photosynthetic core complex. One proposed placement of PufX is at the center of a core complex dimer, where two PufX helices associate in the membrane and form a homodimer. Inability for PufX of certain Rba. species to form a homodimer is thought to lead to monomeric core complexes. In the present study, we employ a combination of computational and experimental techniques to test the hypothesized homodimerization of PufX. We carry out a systematic investigation to measure the dimerization affinity of PufX from four Rba. species, Rba. blasticus , Rba. capsulatus , Rba. sphaeroides , and Rba. veldkampii , using a molecular dynamics-based free-energy method, as well as experimental TOXCAT assays. We found that the four PufX helices have substantially different dimerization affinities. Both computational and experimental techniques demonstrate that species with dimeric core complexes have PufX that can potentially form a homodimer, whereas the one species with monomeric core complexes has a PufX with little to no dimerization propensity. Our analysis of the helix-helix interface revealed a number of positions that may be important for PufX dimerization and the formation of a hydrogen-bond network between these GxxxG-containing helices. Our results suggest that the different oligomerization states of core complexes in various Rba. species can be attributed, among other factors, to the different propensity of its PufX helix to homodimerize.

  11. Liposomes of dimeric artesunate phospholipid: A combination of dimerization and self-assembly to combat malaria.

    Science.gov (United States)

    Ismail, Muhammad; Ling, Longbing; Du, Yawei; Yao, Chen; Li, Xinsong

    2018-05-01

    Artemisinin and its derivatives are highly effective drugs in the treatment of P. falciparum malaria. However, their clinical applications face challenges because of short half-life, poor bioavailability and growing drug resistance. In this article, novel dimeric artesunate phospholipid (Di-ART-GPC) based liposomes were developed by combination of dimerization and self-assembly to address these shortcomings. Firstly, Di-ART-GPC conjugate was synthesized by a facile esterification of artesunate (ART) and glycerophosphorylcholine (GPC) and confirmed by MS, 1 H NMR and 13 C NMR. The conjugate was then assembled to form liposomes without excipient by thin film hydration method. The assembled Di-ART-GPC liposomes have typical multilamellar vesicle structure with bilayer morphology as determined by transmission electron microscopy (TEM) and cryogenic electron microscopy (cryo-EM). Moreover, the liposomes displayed an average hydrodynamic diameter of 190 nm and negative zeta potential at -20.35 mV as determined by Zetasizer. The loading capacity of ART was calculated approximately 77.6% by weight with this liposomal formulation after a simple calculation. In vitro drug release and degradation results showed that the Di-ART-GPC liposomes were stable in neutral physiological conditions but effectively degraded to release parent ART in simulated weakly acidic microenvironment. In vivo pharmacokinetics study revealed that Di-ART-GPC liposomes and conjugate have longer retention half-life in bloodstream. Importantly, Di-ART-GPC liposomes (IC 50 0.39 nM) and the conjugate (IC 50 1.90 nM) demonstrated excellent in vitro antiplasmodial activities without causing hemolysis of erythrocytes, which were superior to free ART (IC 50 5.17 nM) and conventional ART-loaded liposomes (IC 50 3.13 nM). Furthermore, the assembled liposomes resulted in enhanced parasites killing in P. berghei-infected mice in vivo with delayed recrudescence and improved survivability

  12. Reversible Dimerization of Acid-Denatured ACBP Controlled by Helix A4

    DEFF Research Database (Denmark)

    Fieber, Wolfgang; Kragelund, Birthe Brandt; Meldal, Morten Peter

    2005-01-01

    denaturing conditions at pH 2.3, helix conformations are still populated in 24% of the ensemble of molecules. The structure of HA4 at atomic resolution was assessed using nuclear magnetic resonance (NMR) spectroscopy. Long-range NOEs between remote residues at opposite peptide ends suggested the formation...... of dimers and revealed a cooperative stabilization of helix A4 in this process. This emphasizes its special role in the structure formation in the denatured state of ACBP. No dimers are formed in the presence of guanidine hydrochloride, which underlines the fundamental difference between the nature...

  13. DNA repair in B. subtilis: an inducible dimer-specific W-reactivation system

    International Nuclear Information System (INIS)

    Fields, P.I.; Yasbin, R.E.

    1982-01-01

    The W-reactivation system of Bacillus subtilis can repair pyrimidine dimers in bacteriophage DNA. This inducible repair system can be activated by treatment of the bacteria with uv, alkylating agents, cross-linking agents and gamma irradiation. However, bacteriophage treated with agents other than those that cause pyrimidine dimers to be produced was not repaired by this unique form of W-reactivation. In contrast, the W-reactivation system of Escherichia coli can repair a variety of damages placed in the bacteriophage DNA

  14. Determination of the Tetramer-Dimer Equilibrium Constant of Rabbit ...

    African Journals Online (AJOL)

    Hemoglobin is a tetrameric protein which is able to dissociate into dimers. The dimers can in turn dissociate into tetramers. It has been found that dimers are more reactive than tetramers. The difference in the reactivity of these two species has been used to determine the tetramerdimer dissociation constant of various ...

  15. Stochastic optimization-based study of dimerization kinetics

    Indian Academy of Sciences (India)

    Keywords. Stochastic optimization; dimerization kinetics; sensitivity analysis; stochastic simulation algorithm; probability distribution function. ... To this end, we study dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three ...

  16. Ultraviolet Spectrum And Chemical Reactivity Of CIO Dimer

    Science.gov (United States)

    Demore, William B.; Tschuikow-Roux, E.

    1992-01-01

    Report describes experimental study of ultraviolet spectrum and chemical reactivity of dimer of chlorine monoxide (CIO). Objectives are to measure absorption cross sections of dimer at near-ultraviolet wavelengths; determine whether asymmetrical isomer (CIOCIO) exists at temperatures relevant to Antarctic stratosphere; and test for certain chemical reactions of dimer. Important in photochemistry of Antarctic stratosphere.

  17. Ethanol water azeotrope Study. Molecular characterization of ethanol dimers, hetero dimers and hetero trimers of ethanol water

    International Nuclear Information System (INIS)

    Mejia, Sol M; Espinal, Juan F; Mondragon, Fanor

    2006-01-01

    In this investigation, as a first stage, we studied the structure and stability of the dimers,hetero dimers and hetero trimers like aggregates of ethanol and ethanol water respectively. Molecular modelling using hybrid B3LYP of the density functional theory (DFT) was used in this research. O-H bond lengths, hydrogen bond distances, CCOH dihedral angles, enthalpies and Gibbs free energies of dimerization and trimerization and vibrational frequencies of stretching O-H for the dimers and hetero dimers in function of the redshift undergone by proton donor molecules were analyzed. The results shows that the monomers arrange into aggregates which undergo geometric changes induced by the hydrogen bonds. For hetero dimers and hetero trimers the enhancement of the hydrogen bonds where the proton donor molecule corresponds to water was observed. In general, the dimers are more stable than the hetero dimers. We propose the formation of C-H-O hydrogen bonds in some hetero trimers

  18. Live cell imaging unveils multiple domain requirements for in vivo dimerization of the glucocorticoid receptor.

    Directory of Open Access Journals (Sweden)

    Diego M Presman

    2014-03-01

    Full Text Available Glucocorticoids are essential for life, but are also implicated in disease pathogenesis and may produce unwanted effects when given in high doses. Glucocorticoid receptor (GR transcriptional activity and clinical outcome have been linked to its oligomerization state. Although a point mutation within the GR DNA-binding domain (GRdim mutant has been reported as crucial for receptor dimerization and DNA binding, this assumption has recently been challenged. Here we have analyzed the GR oligomerization state in vivo using the number and brightness assay. Our results suggest a complete, reversible, and DNA-independent ligand-induced model for GR dimerization. We demonstrate that the GRdim forms dimers in vivo whereas adding another mutation in the ligand-binding domain (I634A severely compromises homodimer formation. Contrary to dogma, no correlation between the GR monomeric/dimeric state and transcriptional activity was observed. Finally, the state of dimerization affected DNA binding only to a subset of GR binding sites. These results have major implications on future searches for therapeutic glucocorticoids with reduced side effects.

  19. The immunity-related GTPase Irga6 dimerizes in a parallel head-to-head fashion.

    Science.gov (United States)

    Schulte, Kathrin; Pawlowski, Nikolaus; Faelber, Katja; Fröhlich, Chris; Howard, Jonathan; Daumke, Oliver

    2016-03-02

    The immunity-related GTPases (IRGs) constitute a powerful cell-autonomous resistance system against several intracellular pathogens. Irga6 is a dynamin-like protein that oligomerizes at the parasitophorous vacuolar membrane (PVM) of Toxoplasma gondii leading to its vesiculation. Based on a previous biochemical analysis, it has been proposed that the GTPase domains of Irga6 dimerize in an antiparallel fashion during oligomerization. We determined the crystal structure of an oligomerization-impaired Irga6 mutant bound to a non-hydrolyzable GTP analog. Contrary to the previous model, the structure shows that the GTPase domains dimerize in a parallel fashion. The nucleotides in the center of the interface participate in dimerization by forming symmetric contacts with each other and with the switch I region of the opposing Irga6 molecule. The latter contact appears to activate GTP hydrolysis by stabilizing the position of the catalytic glutamate 106 in switch I close to the active site. Further dimerization contacts involve switch II, the G4 helix and the trans stabilizing loop. The Irga6 structure features a parallel GTPase domain dimer, which appears to be a unifying feature of all dynamin and septin superfamily members. This study contributes important insights into the assembly and catalytic mechanisms of IRG proteins as prerequisite to understand their anti-microbial action.

  20. Model-Based Comparison of Antibody Dimerization in Continuous and Batch-Wise Downstream Processing

    Directory of Open Access Journals (Sweden)

    Anton Sellberg

    2015-07-01

    Full Text Available Monoclonal antibodies are generally produced using a generic platform approach in which several chromatographic separations assure high purity of the product. Dimerization can occur during the fermentation stage and may occur also during the downstream processing. We present here simulations in which a traditional platform approach that consist of protein A capture, followed by cation-exchange and anion-exchange chromatography for polishing is compared to a continuous platform in which dimer removal and virus inactivation are carried out on a size-exclusion column. A dimerization model that takes pH, salt concentration and the concentration of antibodies into account is combined with chromatographic models, to be able to predicted both the separation and the degree to which dimers are formed. Purification of a feed composition that contained 1% by weight of dimer and a total antibody concentration of 1 g/L was modeled using both approaches, and the amount of antibodies in the continuous platform was at least 4 times lower than in the traditional platform. The total processing time was also lower, as the cation-exchange polish could be omitted.

  1. Modulation of Coiled-Coil Dimer Stability through Surface Residues while Preserving Pairing Specificity.

    Science.gov (United States)

    Drobnak, Igor; Gradišar, Helena; Ljubetič, Ajasja; Merljak, Estera; Jerala, Roman

    2017-06-21

    The coiled-coil dimer is a widespread protein structural motif and, due to its designability, represents an attractive building block for assembling modular nanostructures. The specificity of coiled-coil dimer pairing is mainly based on hydrophobic and electrostatic interactions between residues at positions a, d, e, and g of the heptad repeat. Binding affinity, on the other hand, can also be affected by surface residues that face away from the dimerization interface. Here we show how design of the local helical propensity of interacting peptides can be used to tune the stabilities of coiled-coil dimers over a wide range. By designing intramolecular charge pairs, regions of high local helical propensity can be engineered to form trigger sequences, and dimer stability is adjusted without changing the peptide length or any of the directly interacting residues. This general principle is demonstrated by a change in thermal stability by more than 30 °C as a result of only two mutations outside the binding interface. The same approach was successfully used to modulate the stabilities in an orthogonal set of coiled-coils without affecting their binding preferences. The stability effects of local helical propensity and peptide charge are well described by a simple linear model, which should help improve current coiled-coil stability prediction algorithms. Our findings enable tuning the stabilities of coiled-coil-based building modules match a diverse range of applications in synthetic biology and nanomaterials.

  2. The tripartite motif coiled-coil is an elongated antiparallel hairpin dimer

    Science.gov (United States)

    Sanchez, Jacint G.; Okreglicka, Katarzyna; Chandrasekaran, Viswanathan; Welker, Jordan M.; Sundquist, Wesley I.; Pornillos, Owen

    2014-01-01

    Tripartite motif (TRIM) proteins make up a large family of coiled-coil-containing RING E3 ligases that function in many cellular processes, particularly innate antiviral response pathways. Both dimerization and higher-order assembly are important elements of TRIM protein function, but the atomic details of TRIM tertiary and quaternary structure have not been fully understood. Here, we present crystallographic and biochemical analyses of the TRIM coiled-coil and show that TRIM proteins dimerize by forming interdigitating antiparallel helical hairpins that position the N-terminal catalytic RING domains at opposite ends of the dimer and the C-terminal substrate-binding domains at the center. The dimer core comprises an antiparallel coiled-coil with a distinctive, symmetric pattern of flanking heptad and central hendecad repeats that appear to be conserved across the entire TRIM family. Our studies reveal how the coiled-coil organizes TRIM25 to polyubiquitylate the RIG-I/viral RNA recognition complex and how dimers of the TRIM5α protein are arranged within hexagonal arrays that recognize the HIV-1 capsid lattice and restrict retroviral replication. PMID:24550273

  3. Effects of Cd{sup 2+} on cis-dimer structure of E-cadherin in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Hiroshi, E-mail: hirotake@sapmed.ac.jp

    2014-02-21

    Highlights: • The effects of Cd on the dimer of cadherin in living cells was analyzed. • Cd induced cadherin dimer formation was not detected in living cell with low Ca. • Ca mediated structural cooperativity and allostery in the native cadherin. • Ca concentration-dependent competitive displacement of Cd from cadherin is proposed. - Abstract: E-cadherin, a calcium (Ca{sup 2+})-dependent cell–cell adhesion molecule, plays a key role in the maintenance of tissue integrity. We have previously demonstrated that E-cadherin functions in vivo as a cis-dimer through chemical cross-linking reagents. Ca{sup 2+} plays an important role in the cis-dimer formation of cadherin. However, the molecular mechanisms by which Ca{sup 2+} interacts with the binding sites that regulate cis-dimer structures have not been completely elucidated. As expected for a Ca{sup 2+} antagonist, cadmium (Cd{sup 2+}) disrupts cadherin function by displacing Ca{sup 2+} from its binding sites on the cadherin molecules. We used Cd{sup 2+} as a probe for investigating the role of Ca{sup 2+} in the dynamics of the E-cadherin extracellular region that involve cis-dimer formation and adhesion. While cell–cell adhesion assembly was completely disrupted in the presence of Cd{sup 2+}, the amount of cis-dimers of E-cadherin that formed at the cell surface was not affected. In our “Cd{sup 2+}-switch” experiments, we did not find that Cd{sup 2+}-induced E-cadherin cis-dimer formation in EL cells when they were incubated in low-Ca{sup 2+} medium. In the present study, we demonstrated for the first time the effects of Cd{sup 2+} on the cis-dimer structure of E-cadherin in living cells using a chemical cross-link analysis.

  4. Large D-Dimer Fluctuation in Normal Pregnancy

    DEFF Research Database (Denmark)

    Hedengran, Katrine K; Andersen, Malene R; Stender, Steen

    2016-01-01

    Introduction. D-dimer levels increase throughout pregnancy, hampering the usefulness of the conventional threshold for dismissing thromboembolism. This study investigates the biological fluctuation of D-dimer in normal pregnancy. Methods. A total of 801 healthy women with expected normal...... pregnancies were recruited. D-dimer was repeatedly measured during pregnancy, at active labor, and on the first and second postpartum days. Percentiles for each gestational week were calculated. Each individual D-dimer was normalized by transformation into percentiles for the relevant gestational age...... normal pregnancy, repeated D-dimer measurements are of no clinical use in the evaluation of thromboembolic events during pregnancy....

  5. Even-odd alternation of the formation of dimer isomers in irradiated polycrystalline alkanes: evidence from product analysis

    International Nuclear Information System (INIS)

    Baudson, T.; Tilquin, B.

    1984-01-01

    Recent ESR studies on n-alkanes from n-C 11 to n-C 25 have shown that a prominent chain end (-CH 2 -CH 2 ) alkyl radical is formed in odd members of the series. In this preliminary discussion of our study, we shall report the capillary chromatogram in the dimer isomers range for n-alkanes ranging from n-C 11 to n-C 17 irradiated at 80 kGy. Dimer isomers, produced in part by the combination of chain end radicals, are eluted at the end chromatogram. The combination of two chain end radicals gives the dimer (D 11 ) isomer eluted at the last place. It is shown that dimers produced by the combination of chain end alkyl radicals are more important for the odd members of the series than for the even members. (author)

  6. Small RNA Library Preparation Method for Next-Generation Sequencing Using Chemical Modifications to Prevent Adapter Dimer Formation.

    Science.gov (United States)

    Shore, Sabrina; Henderson, Jordana M; Lebedev, Alexandre; Salcedo, Michelle P; Zon, Gerald; McCaffrey, Anton P; Paul, Natasha; Hogrefe, Richard I

    2016-01-01

    For most sample types, the automation of RNA and DNA sample preparation workflows enables high throughput next-generation sequencing (NGS) library preparation. Greater adoption of small RNA (sRNA) sequencing has been hindered by high sample input requirements and inherent ligation side products formed during library preparation. These side products, known as adapter dimer, are very similar in size to the tagged library. Most sRNA library preparation strategies thus employ a gel purification step to isolate tagged library from adapter dimer contaminants. At very low sample inputs, adapter dimer side products dominate the reaction and limit the sensitivity of this technique. Here we address the need for improved specificity of sRNA library preparation workflows with a novel library preparation approach that uses modified adapters to suppress adapter dimer formation. This workflow allows for lower sample inputs and elimination of the gel purification step, which in turn allows for an automatable sRNA library preparation protocol.

  7. Structures of DNA containing psoralen crosslink and thymine dimer

    International Nuclear Information System (INIS)

    Kim, S.H.; Pearlman, D.A.; Holbrook, S.R.; Pirkle, D.

    1985-01-01

    UV irradiation by itself or in conjunction with other chemicals can cause covalent damages to DNA in living cells. To overcome the detrimental effect of DNA damage, cells developed a repair mechanism by which damaged DNA is repaired. In the absence of such repair, cell malfunction or cell death can occur. Two most studied radiation-induced DNA damage are thymine dimer formation by UV irradiation and psoralen crosslink by combination of psoralens and UV: In the former, two adjacent thymine bases on a strand of DNA are fused by forming cyclobutane ring, and in the latter, one pyrimidine on one DNA strand is crosslinked to another pyrimidine on the other strand via a psoralen. The authors' objective is to deduce the structure of DNA segment which contains a psoralen crosslink or a thymine dimer using the combination of results of X-ray crystallographic studies, molecular model building, and energy minimization. These structural features may be important for understanding the biological effects of such damages and for the recognition by the repair enzymes

  8. Dimerization of a Viral SET Protein Endows its Function

    Energy Technology Data Exchange (ETDEWEB)

    H Wei; M Zhou

    2011-12-31

    Histone modifications are regarded as the most indispensible phenomena in epigenetics. Of these modifications, lysine methylation is of the greatest complexity and importance as site- and state-specific lysine methylation exerts a plethora of effects on chromatin structure and gene transcription. Notably, paramecium bursaria chlorella viruses encode a conserved SET domain methyltransferase, termed vSET, that functions to suppress host transcription by methylating histone H3 at lysine 27 (H3K27), a mark for eukaryotic gene silencing. Unlike mammalian lysine methyltransferases (KMTs), vSET functions only as a dimer, but the underlying mechanism has remained elusive. In this study, we demonstrate that dimeric vSET operates with negative cooperativity between the two active sites and engages in H3K27 methylation one site at a time. New atomic structures of vSET in the free form and a ternary complex with S-adenosyl homocysteine and a histone H3 peptide and biochemical analyses reveal the molecular origin for the negative cooperativity and explain the substrate specificity of H3K27 methyltransferases. Our study suggests a 'walking' mechanism, by which vSET acts all by itself to globally methylate host H3K27, which is accomplished by the mammalian EZH2 KMT only in the context of the Polycomb repressive complex.

  9. Biocompatible Amphiphilic Hydrogel-Solid Dimer Particles as Colloidal Surfactants.

    Science.gov (United States)

    Chen, Dong; Amstad, Esther; Zhao, Chun-Xia; Cai, Liheng; Fan, Jing; Chen, Qiushui; Hai, Mingtan; Koehler, Stephan; Zhang, Huidan; Liang, Fuxin; Yang, Zhenzhong; Weitz, David A

    2017-12-26

    Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.

  10. Fibrillar dimer formation of islet amyloid polypeptides

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Chi-cheng [Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States); de Pablo, Juan J. [Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  11. Fibrillar dimer formation of islet amyloid polypeptides

    Science.gov (United States)

    Chiu, Chi-cheng; de Pablo, Juan J.

    2015-09-01

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 - 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 - 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  12. An introduction to the dimer model

    International Nuclear Information System (INIS)

    Kenyon, R.

    2004-01-01

    A perfect matching of a graph is a subset of edges which covers every vertex exactly once, that is, for every vertex there is exactly one edge in the set with that vertex as endpoint. The dimer model is the study of the set of perfect matchings of a (possibly infinite) graph. The most well-known example is when the graph is Z 2 , for which perfect matchings are equivalent (via a simple duality) to domino tilings, that is, tilings of the plane with 2 x 1 and 1 x 2 rectangles. In the first three sections we study domino tilings of the plane and of finite polygonal regions, or equivalently, perfect matchings on Z 2 and subgraphs of Z 2 . In the last two sections we study the FK-percolation model and the dimer model on a more general family of planar graphs

  13. PT -symmetric dimer of coupled nonlinear oscillators

    Indian Academy of Sciences (India)

    In this case there are three solutions of the coupled dimer eqs (1) and (2) out of which we present two solutions now and the third one (a novel superposed solution) in the next subsection. Solution I: It is easy to check that u(t) = ±v(t) = Adn[β(t + t0), m]. (22) is an exact solution provided. (ǫ + δ)β2 = −2β2, (2 − m)β2 = −1 ± k.

  14. Electronic structure of the water dimer cation

    Czech Academy of Sciences Publication Activity Database

    Pieniazek, P. A.; Vande Vondele, J.; Jungwirth, Pavel; Krylov, A. I.; Bradforth, S. E.

    2008-01-01

    Roč. 112, č. 27 (2008), s. 6159-6170 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA202/06/0286 Grant - others:NSF(US) CHE-0617060 Institutional research plan: CEZ:AV0Z40550506 Keywords : water dimer * ionization * proton transfer * ab initio Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.871, year: 2008

  15. On the dimerization of linear polymers

    International Nuclear Information System (INIS)

    Aragao Carvalho, C. de.

    1988-08-01

    We use the continuum limit of the Su-Schrieffer-Heeger model for linear polymers to construct its effective potential (Gibbs free energy) both at zero and finite temperature. We study both trans and cis-polymers. Our results show that, depending on a renormalization condition to be extracted from experiment, there are several possibilities for the minima of the dimerized ground state of cis-polymers. All calculations are done in the one-loop approximation. (author). 16 refs, 3 figs

  16. Association between ε2/3/4, Promoter Polymorphism (−491A/T, −427T/C, and −219T/G) at the Apolipoprotein E Gene, and Mental Retardation in Children from an Iodine Deficiency Area, China

    Science.gov (United States)

    Zhang, Fuchang; Wang, Yunliang; Wang, Yan; Qin, Wei; Xing, Qinghe; Qian, Xueqing; Guo, Tingwei; Gao, Xiaocai; He, Lin; Gao, Jianjun

    2014-01-01

    Background. Several common single-nucleotide polymorphisms (SNPs) at apolipoprotein E (ApoE) have been linked with late onset sporadic Alzheimer's disease and declining normative cognitive ability in elder people, but we are unclear about their relationship with cognition in children. Results. We studied −491A/T, −427T/C, and −219G/T promoter polymorphisms and ε2/ε3/ε4 at ApoE among children with mental retardation (MR, n = 130), borderline MR (n = 124), and controls (n = 334) from an iodine deficiency area in China. The allelic and genotypic distribution of individual locus did not significantly differ among three groups with Mantel-Haenszel χ 2 test (P > 0.05). However, frequencies of haplotype of −491A/−427T/−219T/ε4 were distributed as MR > borderline MR > controls (P uncorrected = 0.004), indicating that the presence of this haplotype may increase the risk of disease. Conclusions. In this large population-based study in children, we did not find any significant association between single locus of the four common ApoE polymorphisms (−491A/T, −427T/C, −219T/G, and ε2/3/4) and MR or borderline MR. However, we found that the presence of ATTε4 haplotype was associated with an increased risk of MR and borderline MR. Our present work may help enlarge our knowledge of the cognitive role of ApoE across the lifespan and the mechanisms of human cognition. PMID:24790992

  17. Dimeric architecture of the Hendra virus attachment glycoprotein: evidence for a conserved mode of assembly.

    Science.gov (United States)

    Bowden, Thomas A; Crispin, Max; Harvey, David J; Jones, E Yvonne; Stuart, David I

    2010-06-01

    Hendra virus is a negative-sense single-stranded RNA virus within the Paramyxoviridae family which, together with Nipah virus, forms the Henipavirus genus. Infection with bat-borne Hendra virus leads to a disease with high mortality rates in humans. We determined the crystal structure of the unliganded six-bladed beta-propeller domain and compared it to the previously reported structure of Hendra virus attachment glycoprotein (HeV-G) in complex with its cellular receptor, ephrin-B2. As observed for the related unliganded Nipah virus structure, there is plasticity in the Glu579-Pro590 and Lys236-Ala245 ephrin-binding loops prior to receptor engagement. These data reveal that henipaviral attachment glycoproteins undergo common structural transitions upon receptor binding and further define the structural template for antihenipaviral drug design. Our analysis also provides experimental evidence for a dimeric arrangement of HeV-G that exhibits striking similarity to those observed in crystal structures of related paramyxovirus receptor-binding glycoproteins. The biological relevance of this dimer is further supported by the positional analysis of glycosylation sites from across the paramyxoviruses. In HeV-G, the sites lie away from the putative dimer interface and remain accessible to alpha-mannosidase processing on oligomerization. We therefore propose that the overall mode of dimer assembly is conserved for all paramyxoviruses; however, while the geometry of dimerization is rather closely similar for those viruses that bind flexible glycan receptors, significant (up to 60 degrees ) and different reconfigurations of the subunit packing (associated with a significant decrease in the size of the dimer interface) have accompanied the independent switching to high-affinity protein receptor binding in Hendra and measles viruses.

  18. Van der Waals bond in dimers: H2Ne, H2Ar, H2Kr

    International Nuclear Information System (INIS)

    Waaijer, M.

    1981-01-01

    The H 2 -inert gas dimers H 2 X, and particularly H 2 Ne, H 2 Ar and H 2 Kr, form the subject of this thesis and are loosely bound van der Waals complexes, which is reflected in the low number of bound states and the small anisotropic interaction. The H 2 X dimers studied are formed in a supersonic nozzle expansion, in which the internal energy is converted into the macroscopic flow energy, establishing an internal temperature drop to 3 K, which favours dimer formation. Because of this cooling the H 2 X dimers relax to the lowest rotational states. The hyperfine transitions have been measured using magnetic beam resonance and yield information about the isotropic as well as the anisotropic intermolecular potential in the range between the classical turning points and in the adjacent part of the repulsive branch. The sensitivity of the method is very high and slight changes in the intermolecular potential cause significant effects. The analysis of the measured hyperfine transitions incorporates all interacting states of the molecule, bound as well as unbound (continuum) states. For H 2 Ne, which is the best studied H 2 -inert gas system from the experimental point of view, the author succeeded in establishing an intermolecular potential, that provides a solid ground for comparison with future ab initio calculations. (Auth.)

  19. Study of dimerization reaction during cathodic splitting of halogen. Dimerization during reduction of butyl iodide

    International Nuclear Information System (INIS)

    Tomilov, A.P.

    2001-01-01

    The process of electrochemical reduction of butyl iodide in methanol in the presence of sodium methylate was studied. It was ascertained that the yield of dimer product, i. e. octane, depends essentially on the cathode material. Copper and iron (steel 3) proved the most active agents in dimerization process. Conditions (current density 0.03-0.10 A/cm 2 , 0 deg C, 0.005 M CH 3 ONa), under which octane yield amounts to 83-84% in matter, were found [ru

  20. The Structure of the Poxvirus A33 Protein Reveals a Dimer of Unique C-Type Lectin-Like Domains

    Energy Technology Data Exchange (ETDEWEB)

    Su, Hua-Poo; Singh, Kavita; Gittis, Apostolos G.; Garboczi, David N. (NIH)

    2010-11-03

    The current vaccine against smallpox is an infectious form of vaccinia virus that has significant side effects. Alternative vaccine approaches using recombinant viral proteins are being developed. A target of subunit vaccine strategies is the poxvirus protein A33, a conserved protein in the Chordopoxvirinae subfamily of Poxviridae that is expressed on the outer viral envelope. Here we have determined the structure of the A33 ectodomain of vaccinia virus. The structure revealed C-type lectin-like domains (CTLDs) that occur as dimers in A33 crystals with five different crystal lattices. Comparison of the A33 dimer models shows that the A33 monomers have a degree of flexibility in position within the dimer. Structural comparisons show that the A33 monomer is a close match to the Link module class of CTLDs but that the A33 dimer is most similar to the natural killer (NK)-cell receptor class of CTLDs. Structural data on Link modules and NK-cell receptor-ligand complexes suggest a surface of A33 that could interact with viral or host ligands. The dimer interface is well conserved in all known A33 sequences, indicating an important role for the A33 dimer. The structure indicates how previously described A33 mutations disrupt protein folding and locates the positions of N-linked glycosylations and the epitope of a protective antibody.

  1. Hydrolysis at One of the Two Nucleotide-binding Sites Drives the Dissociation of ATP-binding Cassette Nucleotide-binding Domain Dimers*

    Science.gov (United States)

    Zoghbi, Maria E.; Altenberg, Guillermo A.

    2013-01-01

    The functional unit of ATP-binding cassette (ABC) transporters consists of two transmembrane domains and two nucleotide-binding domains (NBDs). ATP binding elicits association of the two NBDs, forming a dimer in a head-to-tail arrangement, with two nucleotides “sandwiched” at the dimer interface. Each of the two nucleotide-binding sites is formed by residues from the two NBDs. We recently found that the prototypical NBD MJ0796 from Methanocaldococcus jannaschii dimerizes in response to ATP binding and dissociates completely following ATP hydrolysis. However, it is still unknown whether dissociation of NBD dimers follows ATP hydrolysis at one or both nucleotide-binding sites. Here, we used luminescence resonance energy transfer to study heterodimers formed by one active (donor-labeled) and one catalytically defective (acceptor-labeled) NBD. Rapid mixing experiments in a stop-flow chamber showed that NBD heterodimers with one functional and one inactive site dissociated at a rate indistinguishable from that of dimers with two hydrolysis-competent sites. Comparison of the rates of NBD dimer dissociation and ATP hydrolysis indicated that dissociation followed hydrolysis of one ATP. We conclude that ATP hydrolysis at one nucleotide-binding site drives NBD dimer dissociation. PMID:24129575

  2. Dimerization of inositol monophosphatase Mycobacterium tuberculosis SuhB is not constitutive, but induced by binding of the activator Mg2+

    Directory of Open Access Journals (Sweden)

    Nigou Jérôme

    2007-08-01

    Full Text Available Abstract Background The cell wall of Mycobacterium tuberculosis contains a wide range of phosphatidyl inositol-based glycolipids that play critical structural roles and, in part, govern pathogen-host interactions. Synthesis of phosphatidyl inositol is dependent on free myo-inositol, generated through dephosphorylation of myo-inositol-1-phosphate by inositol monophosphatase (IMPase. Human IMPase, the putative target of lithium therapy, has been studied extensively, but the function of four IMPase-like genes in M. tuberculosis is unclear. Results We determined the crystal structure, to 2.6 Å resolution, of the IMPase M. tuberculosis SuhB in the apo form, and analysed self-assembly by analytical ultracentrifugation. Contrary to the paradigm of constitutive dimerization of IMPases, SuhB is predominantly monomeric in the absence of the physiological activator Mg2+, in spite of a conserved fold and apparent dimerization in the crystal. However, Mg2+ concentrations that result in enzymatic activation of SuhB decisively promote dimerization, with the inhibitor Li+ amplifying the effect of Mg2+, but failing to induce dimerization on its own. Conclusion The correlation of Mg2+-driven enzymatic activity with dimerization suggests that catalytic activity is linked to the dimer form. Current models of lithium inhibition of IMPases posit that Li+ competes for one of three catalytic Mg2+ sites in the active site, stabilized by a mobile loop at the dimer interface. Our data suggest that Mg2+/Li+-induced ordering of this loop may promote dimerization by expanding the dimer interface of SuhB. The dynamic nature of the monomer-dimer equilibrium may also explain the extended concentration range over which Mg2+ maintains SuhB activity.

  3. Interaction of the αβ dimers of the insulin-like growth factor I receptor required for receptor autophosphorylation

    International Nuclear Information System (INIS)

    Tollesfsen, S.E.; Stoszek, R.M.; Thompson, K.

    1991-01-01

    The authors have recently found that association of the two αβ dimers of the insulin-like growth factor I (IGF I) receptor is required for formation of a high-affinity binding site for IGF I. To determine the structural requirements for IGF I activated kinase activity, they have examined the effect of dissociation of the two αβ dimers of the IGF I receptor on β subunit autophosphorylation. The αβ dimers formed after treatment with 2 mM dithiothreitol (DTT) at pH 8.75 for 5 min were separated from IGF I receptor remaining as tetramers after DTT treatment by fast protein liquid chromatography on a Superose 6 gel filtration column. Purification of the αβ dimers was confirmed by Western blot analysis using 125 I-labeled αIR-3, a monoclonal antibody to the IGF I receptor. Autophosphorylation of the IGF I receptor (αβ) 2 tetramer, treated without DTT or remaining after DTT treatment, is stimulated 1.6-2.9-fold by IGF I. In contrast, autophosporylation of the αβ dimers incubated in the presence or absence of IGF I (100 ng/mL) does not occur. Both IGF I receptor dimers and tetramers exhibit similar kinase activities using the synthetic substrate Arg-Arg-Leu-Ile-Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Gly, indicating that the failure to detect autophosphorylation of the IGF I receptor dimers does not result from inactivation of the kinase by DTT treatment. They conclude that autophosphorylation of the IGF I receptor depends upon the interaction of the two αβ dimers

  4. Apolipoprotein E gene polymorphism in Egyptian acute coronary ...

    African Journals Online (AJOL)

    Aida A. Mahmoud

    2015-09-07

    Sep 7, 2015 ... phisms (SNPs) at positions +2059 (T/C), located in the codon that codes for amino acid 112 and +2197 (C/T), that codes ... (2059-T) of the gene defines a cysteine at position 112 (Cys. 112), whereas 2059-C defines an arginine for the ... atherogenic occlusion. The inclusion criteria for the controls were; no ...

  5. Apolipoprotein E: from cardiovascular disease to neurodegenerative disorders.

    Science.gov (United States)

    Mahley, Robert W

    2016-07-01

    Apolipoprotein (apo) E was initially described as a lipid transport protein and major ligand for low density lipoprotein (LDL) receptors with a role in cholesterol metabolism and cardiovascular disease. It has since emerged as a major risk factor (causative gene) for Alzheimer's disease and other neurodegenerative disorders. Detailed understanding of the structural features of the three isoforms (apoE2, apoE3, and apoE4), which differ by only a single amino acid interchange, has elucidated their unique functions. ApoE2 and apoE4 increase the risk for heart disease: apoE2 increases atherogenic lipoprotein levels (it binds poorly to LDL receptors), and apoE4 increases LDL levels (it binds preferentially to triglyceride-rich, very low density lipoproteins, leading to downregulation of LDL receptors). ApoE4 also increases the risk for neurodegenerative diseases, decreases their age of onset, or alters their progression. ApoE4 likely causes neurodegeneration secondary to its abnormal structure, caused by an interaction between its carboxyl- and amino-terminal domains, called domain interaction. When neurons are stressed or injured, they synthesize apoE to redistribute cholesterol for neuronal repair or remodeling. However, because of its altered structure, neuronal apoE4 undergoes neuron-specific proteolysis, generating neurotoxic fragments (12-29 kDa) that escape the secretory pathway and cause mitochondrial dysfunction and cytoskeletal alterations, including tau phosphorylation. ApoE4-associated pathology can be prevented by small-molecule structure correctors that block domain interaction by converting apoE4 to a molecule that resembles apoE3 both structurally and functionally. Structure correctors are a potential therapeutic approach to reduce apoE4 pathology in both cardiovascular and neurological disorders.

  6. Apolipoprotein E4 allele does not influence serum triglyceride ...

    African Journals Online (AJOL)

    This study investigated how the APOε4 allele affects the serum triglyceride response after a fatmeal in apparently healthy black South African young adults. Sixty students were successfully screened for APOE genotype using Restriction Fragment Length Polymorphism (RFLP) and were divided into four groups; the ε2 allele ...

  7. Cardiovascular effects of uremia in apolipoprotein E-deficient mice

    DEFF Research Database (Denmark)

    Bro, Susanne

    2009-01-01

    degeneration. Furthermore, the studies suggested that vascular inflammation and systemic oxidative stress may explain some of the proatherogenic effects of uremia in mice. Interestingly, the accelerated atherosclerosis could be prevented by RAS inhibition, or markedly reduced by RAGE blockade, probably through...

  8. Atomic resolution crystal structure of VcLMWPTP-1 from Vibrio cholerae O395: Insights into a novel mode of dimerization in the low molecular weight protein tyrosine phosphatase family

    Energy Technology Data Exchange (ETDEWEB)

    Nath, Seema; Banerjee, Ramanuj; Sen, Udayaditya, E-mail: udayaditya.sen@saha.ac.in

    2014-07-18

    Highlights: • VcLMWPTP-1 forms dimer in solution. • The dimer is catalytically active unlike other reported dimeric LMWPTPs. • The formation of extended dimeric surface excludes the active site pocket. • The surface bears closer resemblance to eukaryotic LMWPTPs. - Abstract: Low molecular weight protein tyrosine phosphatase (LMWPTP) is a group of phosphotyrosine phosphatase ubiquitously found in a wide range of organisms ranging from bacteria to mammals. Dimerization in the LMWPTP family has been reported earlier which follows a common mechanism involving active site residues leading to an enzymatically inactive species. Here we report a novel form of dimerization in a LMWPTP from Vibrio cholera 0395 (VcLMWPTP-1). Studies in solution reveal the existence of the dimer in solution while kinetic study depicts the active form of the enzyme. This indicates that the mode of dimerization in VcLMWPTP-1 is different from others where active site residues are not involved in the process. A high resolution (1.45 Å) crystal structure of VcLMWPTP-1 confirms a different mode of dimerization where the active site is catalytically accessible as evident by a tightly bound substrate mimicking ligand, MOPS at the active site pocket. Although being a member of a prokaryotic protein family, VcLMWPTP-1 structure resembles very closely to LMWPTP from a eukaryote, Entamoeba histolytica. It also delineates the diverse surface properties around the active site of the enzyme.

  9. Dimeric assembly of enterocyte brush border enzymes

    DEFF Research Database (Denmark)

    Danielsen, E M

    1994-01-01

    The noncovalent, dimeric assembly of small intestinal brush border enzymes was studied by sedimentation analysis in density gradients of extracts of pulse-labeled pig jejunal mucosal explants. Like aminopeptidase N (EC 3.4.11.2), sucrase-isomaltase (EC 3.2.1.48-10), aminopeptidase A (EC 3...... appearance of the liposome-reconstituted enzyme [Norén et al. (1986) J. Biol. Chem. 261, 12306-12309], showing only the inner, membrane-anchored domains of the monomers to be in close contact with one another while the outer domains are far apart. In contrast to the other brush border enzymes studied...

  10. Dimerization and oligomerization of the chaperone calreticulin

    DEFF Research Database (Denmark)

    Jørgensen, Charlotte S; Ryder, L Rebekka; Steinø, Anne

    2003-01-01

    protein. Using PAGE, urea gradient gel electrophoresis, capillary electrophoresis and MS, we show that dimerization through the SH group can be induced by lowering the pH to 5-6, heating, or under conditions that favour partial unfolding such as urea concentrations above 2.6 m or SDS concentrations above...... that favour partial unfolding or an intramolecular local conformational change that allows oligomerization, resulting in a heterogeneous mixture of oligomers consisting of up to 10 calreticulin monomers. The oligomeric calreticulin was very stable, but oligomerization was partially reversed by addition of 8 m...

  11. Phosphorous dimerization in GaP high-pressure polymorph

    Energy Technology Data Exchange (ETDEWEB)

    Lavina, Barbara [Univ. of Nevada, Las Vegas, NV (United States). High Pressure Science and Engineering Center (HiPSEC), Dept. of Physics and Astronomy; Kim, Eunja [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Physics and Astronomy; Cynn, Hyunchae [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Weck, Philippe F [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seaborg, Kelly [Univ. of Nevada, Las Vegas, NV (United States). High Pressure Science and Engineering Center (HiPSEC), Dept. of Physics and Astronomy; Siska, Emily [Univ. of Nevada, Las Vegas, NV (United States). High Pressure Science and Engineering Center (HiPSEC); Meng, Yue [Carnegie Inst. of Washington, Argonne, IL (United States). Geophysical Lab., High Pressure Collaborative Access Team (HPCAT); Evans, Williams [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-06-01

    We report on the experimental and theoretical characterization of a novel GaP polymorph formed by laser heating of a single crystal of GaP-II in its stable region near 43 GPa. Thereby formed unstrained multigrain sample at 43 GPa and 1300 K, allowed high-resolution crystallographic analysis. We find an oS24 as an energetically optimized crystal structure contrary to oS8 reported by Nelmes et al. (1997). Our DFT calculation confirms a stable existence of oS24 between 18 – 50 GPa. The emergence of the oS24 structure is related to the differentiation of phosphorous atoms between those forming P-P dimers and those forming P-Ga bonds only. Bonding anisotropy explains the symmetry lowering with respect to what is generally expected for semiconductors high-pressure polymorphs. The metallization of GaP does not occur through a uniform change of the nature of its bonds but through the formation of an anisotropic phase containing different bond types.

  12. Viscosity and sedimentation behaviors of the magnetorheological suspensions with oleic acid/dimer acid as surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jianjian; Yan, Hua; Hu, Zhide; Ding, Ding

    2016-11-01

    This work deals with the role of polar interactions on the viscosity and sedimentation behaviors of magnetorheological suspensions with micro-sized magnetic particles dispersed in oil carriers. The oleic acid and dimer acid were employed to make an adjustment of the hydrophobicity of iron particles, in the interest of performing a comparative evaluation of the contributions of the surface polarity. The viscosity tests show that the adsorbed surfactant layer may impose a hindrance to the movement of iron particles in the oil medium. The polar attractions between dimer acid covered particles gave rise to a considerable increase in viscosity, indicating flocculation structure developed in the suspensions. The observed plateau-like region in the vicinity of 0.1 s{sup −1} for MRF containing dimer acid is possibly due to the flocculation provoked by the carboxylic polar attraction, in which the structure is stable against fragmentation. Moreover, a quick recovery of the viscosity and a higher viscosity-temperature index also suggest the existence of particle-particle polar interaction in the suspensions containing dimer acid. The sedimentation measurements reveal that the steric repulsion of oleic acid plays a limited role in the stability of suspensions only if a large quantity of surfactant was used. The sedimentation results observed in the dimer acid covered particles confirm that loose and open flocculation was formed and enhanced sedimentation stability. - Highlights: • Surfactants were employed to make adjustments of the hydrophobicity of particles. • Polar attractions between particles increased the viscosity considerably. • Loose and open flocculation was formed in CI/DA suspension. • The steric repulsion of oleic acid played a limited role in the stability.

  13. High-speed atomic force microscopy reveals structural dynamics of α -synuclein monomers and dimers

    Science.gov (United States)

    Zhang, Yuliang; Hashemi, Mohtadin; Lv, Zhengjian; Williams, Benfeard; Popov, Konstantin I.; Dokholyan, Nikolay V.; Lyubchenko, Yuri L.

    2018-03-01

    α-Synuclein (α-syn) is the major component of the intraneuronal inclusions called Lewy bodies, which are the pathological hallmark of Parkinson's disease. α-Syn is capable of self-assembly into many different species, such as soluble oligomers and fibrils. Even though attempts to resolve the structures of the protein have been made, detailed understanding about the structures and their relationship with the different aggregation steps is lacking, which is of interest to provide insights into the pathogenic mechanism of Parkinson's disease. Here we report the structural flexibility of α-syn monomers and dimers in an aqueous solution environment as probed by single-molecule time-lapse high-speed AFM. In addition, we present the molecular basis for the structural transitions using discrete molecular dynamics (DMD) simulations. α-Syn monomers assume a globular conformation, which is capable of forming tail-like protrusions over dozens of seconds. Importantly, a globular monomer can adopt fully extended conformations. Dimers, on the other hand, are less dynamic and show a dumbbell conformation that experiences morphological changes over time. DMD simulations revealed that the α-syn monomer consists of several tightly packed small helices. The tail-like protrusions are also helical with a small β-sheet, acting as a "hinge". Monomers within dimers have a large interfacial interaction area and are stabilized by interactions in the non-amyloid central (NAC) regions. Furthermore, the dimer NAC-region of each α-syn monomer forms a β-rich segment. Moreover, NAC-regions are located in the hydrophobic core of the dimer.

  14. Kinetics of the dimerization of retroviral proteases: The "fireman's grip" and dimerization

    Czech Academy of Sciences Publication Activity Database

    Ingr, Marek; Kondrová, Taťána; Stříšovský, Kvido; Majerová, E.; Konvalinka, Jan

    2003-01-01

    Roč. 12, - (2003), s. 2173-2182 ISSN 0961-8368 R&D Projects: GA MZd NI6339 Institutional research plan: CEZ:AV0Z4055905 Keywords : retroviral protease * dimerization * HIV protease Subject RIV: CE - Biochemistry Impact factor: 3.787, year: 2003

  15. Tunneling anisotropic magnetoresistance via molecular π orbitals of Pb dimers

    Science.gov (United States)

    Schöneberg, Johannes; Ferriani, Paolo; Heinze, Stefan; Weismann, Alexander; Berndt, Richard

    2018-01-01

    Pb dimers on a ferromagnetic surface are shown to exhibit large tunneling anisotropic magnetoresistance (TAMR) due to molecular π orbitals. Dimers oriented differently with respect to the magnetization directions of a ferromagnetic Fe double layer on W(110) were made with a scanning tunneling microscope. Depending on the dimer orientations, TAMR is absent or as large as 20% at the Fermi level. General arguments and first-principles calculations show that mixing of molecular orbitals due to spin-orbit coupling, which leads to TAMR, is maximal when the magnetization is oriented parallel to the dimer axis.

  16. FAK dimerization controls its kinase-dependent functions at focal adhesions

    KAUST Repository

    Brami-Cherrier, Karen

    2014-01-30

    Focal adhesion kinase (FAK) controls adhesion-dependent cell motility, survival, and proliferation. FAK has kinase-dependent and kinase-independent functions, both of which play major roles in embryogenesis and tumor invasiveness. The precise mechanisms of FAK activation are not known. Using x-ray crystallography, small angle x-ray scattering, and biochemical and functional analyses, we show that the key step for activation of FAK\\'s kinase-dependent functions-autophosphorylation of tyrosine-397-requires site-specific dimerization of FAK. The dimers form via the association of the N-terminal FERM domain of FAK and are stabilized by an interaction between FERM and the C-terminal FAT domain. FAT binds to a basic motif on FERM that regulates co-activation and nuclear localization. FAK dimerization requires local enrichment, which occurs specifically at focal adhesions. Paxillin plays a dual role, by recruiting FAK to focal adhesions and by reinforcing the FAT:FERM interaction. Our results provide a structural and mechanistic framework to explain how FAK combines multiple stimuli into a site-specific function. The dimer interfaces we describe are promising targets for blocking FAK activation. © 2014 The Authors.

  17. The dynamics of a polariton dimer in a disordered coupled array of cavities

    Science.gov (United States)

    Aiyejina, Abuenameh; Andrews, Roger

    2018-03-01

    We investigate the effect of disorder in the laser intensity on the dynamics of dark-state polaritons in an array of 20 cavities, each containing an ensemble of four-level atoms that is described by a Bose-Hubbard Hamiltonian. We examine the evolution of the polariton number in the cavities starting from a state with either one or two polaritons in one of the cavities. For the case of a single polariton without disorder in the laser intensity, we calculate the wavefunction of the polariton and find that it disperses away from the initial cavity with time. The addition of disorder results in minimal suppression of the dispersal of the wavefunction. In the case of two polaritons with an on-site repulsion to hopping strength ratio of 20, we find that the polaritons form a repulsively bound state or dimer. Without disorder the dimer wavefunction disperses similarly to the single polariton wavefunction but over a longer time period. The addition of sufficiently strong disorder results in localization of the polariton dimer. The localization length is found to be described by a power law with exponent - 1.31. We also find that we can localise the dimer at any given time by switching on the disorder.

  18. n-Dopants Based on Dimers of Benzimidazoline Radicals: Structures and Mechanism of Redox Reactions

    KAUST Repository

    Zhang, Siyuan

    2015-06-18

    Dimers of 2-substituted N,N\\'-dimethylbenzimidazoline radicals, (2-Y-DMBI)2 (Y=cyclohexyl (Cyc), ferrocenyl (Fc), ruthenocenyl (Rc)), have recently been reported as n-dopants for organic semiconductors. Here their structural and energetic characteristics are reported, along with the mechanisms by which they react with acceptors, A (PCBM, TIPS-pentacene), in solution. X-ray data and DFT calculations both indicate a longer C-C bond for (2-Cyc-DMBI)2 than (2-Fc-DMBI)2, yet DFT and ESR data show that the latter dissociates more readily due to stabilization of the radical by Fc. Depending on the energetics of dimer (D2) dissociation and of D2-to-A electron transfer, D2 reacts with A to form D+ and A- by either of two mechanisms, differing in whether the first step is endergonic dissociation or endergonic electron transfer. However, the D+/0.5D2 redox potentials-the effective reducing strengths of the dimers-vary little within the series (ca. -1.9V vs. FeCp2+/0) (Cp=cyclopentadienyl) due to cancelation of trends in the D+/0 potential and D2 dissociation energy. The implications of these findings for use of these dimers as n-dopants, and for future dopant design, are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Insights into Strand Exchange in BTB Domain Dimers from the Crystal Structures of FAZF and Miz1

    Energy Technology Data Exchange (ETDEWEB)

    Stogios, Peter J.; Cuesta-Seijo, Jose Antonio; Chen, Lu; Pomroy, Neil C.; Privé, Gilbert G. (Toronto); (OCI)

    2010-09-22

    The BTB domain is a widely distributed protein-protein interaction motif that is often found at the N-terminus of zinc finger transcription factors. Previous crystal structures of BTB domains have revealed tightly interwound homodimers, with the N-terminus from one chain forming a two-stranded anti-parallel {beta}-sheet with a strand from the other chain. We have solved the crystal structures of the BTB domains from Fanconi anemia zinc finger (FAZF) and Miz1 (Myc-interacting zinc finger 1) to resolutions of 2.0 {angstrom} and 2.6 {angstrom}, respectively. Unlike previous examples of BTB domain structures, the FAZF BTB domain is a nonswapped dimer, with each N-terminal {beta}-strand associated with its own chain. As a result, the dimerization interface in the FAZF BTB domain is about half as large as in the domain-swapped dimers. The Miz1 BTB domain resembles a typical swapped BTB dimer, although it has a shorter N-terminus that is not able to form the interchain sheet. Using cysteine cross-linking, we confirmed that the promyelocytic leukemia zinc finger (PLZF) BTB dimer is strand exchanged in solution, while the FAZF BTB dimer is not. A phylogenic tree of the BTB fold based on both sequence and structural features shows that the common ancestor of the BTB domain in BTB-ZF (bric a brac, tramtrack, broad-complex zinc finger) proteins was a domain-swapped dimer. The differences in the N-termini seen in the FAZF and Miz1 BTB domains appear to be more recent developments in the structural evolution of the domain.

  20. The role of dimerization in prion replication.

    Science.gov (United States)

    Tompa, Peter; Tusnády, Gábor E; Friedrich, Peter; Simon, István

    2002-04-01

    The central theme in prion diseases is the conformational transition of a cellular protein from a physiologic to a pathologic (so-called scrapie) state. Currently, two alternative models exist for the mechanism of this autocatalytic process; in the template assistance model the prion is assumed to be a monomer of the scrapie conformer, whereas in the nucleated polymerization model it is thought to be an amyloid rod. A recent variation on the latter assumes disulfide reshuffling as the mechanism of polymerization. The existence of stable dimers, let alone their mechanistic role, is not taken into account in either of these models. In this paper we review evidence supporting that the dimerization of either the normal or the scrapie state, or both, has a decisive role in prion replication. The contribution of redox changes, i.e., the temporary opening and possible rearrangement of the intramolecular disulfide bridge is also considered. We present a model including these features largely ignored so far and show that it adheres satisfactorily to the observed phenomenology of prion replication.

  1. Development of β-linked quaterthiophene and tetrathiafulvalene dimers as new organic semiconductors

    International Nuclear Information System (INIS)

    Ashizawa, Minoru; Yu, Yan; Niimura, Takuro; Tsuboi, Kazuma; Matsumoto, Hidetoshi; Tanioka, Akihiko; Mori, Takehiko

    2010-01-01

    A series of β-linked quaterthiophene and tetrathiafulvalene dimers 1-4 has been prepared. Their redox and optical properties are almost the same as the parent monomers indicative of very little interaction between the monomers. Crystal structures of 1, 2, and 4 are highly one-dimensional, in which molecular structure of 1 is planar whereas those of 2 and 4 are in a bent form.

  2. Stochastic optimization-based study of dimerization kinetics

    Indian Academy of Sciences (India)

    Abstract. We investigate the potential of numerical algorithms to decipher the kinetic parameters involved in multi-step chemical reactions. To this end, we study dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three different.

  3. Exact Solution of a Generalized Nonlinear Schrodinger Equation Dimer

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Maniadis, P.; Tsironis, G.P.

    1998-01-01

    We present exact solutions for a nonlinear dimer system defined throught a discrete nonlinear Schrodinger equation that contains also an integrable Ablowitz-Ladik term. The solutions are obtained throught a transformation that maps the dimer into a double Sine-Gordon like ordinary nonlinear...

  4. Two Populations Mean-Field Monomer-Dimer Model

    Science.gov (United States)

    Alberici, Diego; Mingione, Emanuele

    2018-04-01

    A two populations mean-field monomer-dimer model including both hard-core and attractive interactions between dimers is considered. The pressure density in the thermodynamic limit is proved to satisfy a variational principle. A detailed analysis is made in the limit of one population is much smaller than the other and a ferromagnetic mean-field phase transition is found.

  5. Dimerization of translationally controlled tumor protein is essential for its cytokine-like activity.

    Directory of Open Access Journals (Sweden)

    Miyoung Kim

    Full Text Available BACKGROUND: Translationally Controlled Tumor Protein (TCTP found in nasal lavage fluids of allergic patients was named IgE-dependent histamine-releasing factor (HRF. Human recombinant HRF (HrHRF has been recently reported to be much less effective than HRF produced from activated mononuclear cells (HRFmn. METHODS AND FINDINGS: We found that only NH(2-terminal truncated, but not C-terminal truncated, TCTP shows cytokine releasing activity compared to full-length TCTP. Interestingly, only NH(2-terminal truncated TCTP, unlike full-length TCTP, forms dimers through intermolecular disulfide bonds. We tested the activity of dimerized full-length TCTP generated by fusing it to rabbit Fc region. The untruncated-full length protein (Fc-HrTCTP was more active than HrTCTP in BEAS-2B cells, suggesting that dimerization of TCTP, rather than truncation, is essential for the activation of TCTP in allergic responses. We used confocal microscopy to evaluate the affinity of TCTPs to its putative receptor. We detected stronger fluorescence in the plasma membrane of BEAS-2B cells incubated with Del-N11TCTP than those incubated with rat recombinant TCTP (RrTCTP. Allergenic activity of Del-N11TCTP prompted us to see whether the NH(2-terminal truncated TCTP can induce allergic airway inflammation in vivo. While RrTCTP had no influence on airway inflammation, Del-N11TCTP increased goblet cell hyperplasia in both lung and rhinal cavity. The dimerized protein was found in sera from allergic patients, and bronchoalveolar lavage fluids from airway inflamed mice. CONCLUSIONS: Dimerization of TCTP seems to be essential for its cytokine-like activity. Our study has potential to enhance the understanding of pathogenesis of allergic disease and provide a target for allergic drug development.

  6. Dimer self-organization of impurity ytterbium ions in synthetic forsterite single crystals

    Science.gov (United States)

    Tarasov, V. F.; Sukhanov, A. A.; Dudnikova, V. B.; Zharikov, E. V.; Lis, D. A.; Subbotin, K. A.

    2017-07-01

    Paramagnetic centers formed by impurity Yb3+ ions in synthetic forsterite (Mg2SiO4) grown by the Czochralski technique are studied by X-band CW and pulsed EPR spectroscopy. These centers are single ions substituting magnesium in two different crystallographic positions denoted M1 and M2, and dimer associates formed by two Yb3+ ions in nearby positions M1. It is established that there is a pronounced mechanism favoring self-organization of ytterbium ions in dimer associates during the crystal growth, and the mechanism of the spin-spin coupling between ytterbium ions in the associate has predominantly a dipole-dipole character, which makes it possible to control the energy of the spin-spin interaction by changing the orientation of the external magnetic field. The structural computer simulation of cluster ytterbium centers in forsterite crystals is carried out by the method of interatomic potentials using the GULP 4.0.1 code (General Utility Lattice Program). It is established that the formation of dimer associates in the form of a chain parallel to the crystallographic axis consisting of two ytterbium ions with a magnesium vacancy between them is the most energetically favorable for ytterbium ions substituting magnesium in the position M1.

  7. Palladium dimers adsorbed on graphene: A DFT study

    International Nuclear Information System (INIS)

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-01-01

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd 2 ) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd 2 -graphene system are calculated. Both horizontal and vertical orientations of Pd 2 on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen

  8. Metal membrane with dimer slots as a universal polarizer

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Zalkovskij, Maksim; Malureanu, Radu

    2014-01-01

    for the electromagnetic response of an arbitrary dimer based on the Green functions approach. The theory confirms that a great variety of polarization properties, such as birefringence, chirality and elliptical dichroism, can be achieved in a metal layer with such slot-dimer patterning (i.e. in a metasurface). Optical......In this work, we show theoretically and confirm experimentally that thin metal membranes patterned with an array of slot dimers (or their Babinet analogue with metal rods) can function as a versatile spectral and polarization filter. We present a detailed covariant multipole theory...... properties of the metasurface can be extensively tuned by varying the geometry (shape and dimensions) of the dimer, for example, by adjusting the sizes and mutual placement of the slots (e.g. inter-slot distance and alignment angle). Three basic shapes of dimers are analyzed: II-shaped (parallel slots), V...

  9. Dimer Coverings on Random Polyomino Chains

    Science.gov (United States)

    Xiao, Chuanqi; Chen, Haiyan

    2015-06-01

    A polyomino chain is a planar square lattice that can be constructed by successively attaching squares to the previous one in two possible ways. A random polyomino chain is then generated by incorporating the Bernoulli distribution to the two types of attachment, which describes a zeroth-order Markov process. Let (ℜn, p) be the ensemble of random polyomino chains with n squares, where p∈[0,1] is a constant. Then, in this paper, we determine the explicit expression for the expectation of the number of dimer coverings over (ℜn, p). Our result shows that, with only one exception, i.e., p = 0, the average of the logarithm of this expectation is asymptotically nonzero when n → ∞.

  10. Dualism of Sensitivity and Selectivity of Porphyrin Dimers in Electroanalysis.

    Science.gov (United States)

    Lisak, Grzegorz; Tamaki, Takashi; Ogawa, Takuji

    2017-04-04

    This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely, freebase-freebase, Zn-Zn, Zn-freebase, and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion- and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion- and cation-sensitive sensors. With respect to the lipophilic salt added, both porphyrins dimers were found anion- and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion- and cation-selective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane. Furthermore, the selectivity of cation-sensitive dimer based sensors was found significantly superior to the ones measured for the single porphyrin unit based sensors (precursors of the porphyrin dimers). Thus, the dimerization of single porphyrins may actually be a factor to increase or modulate porphyrin selectivity. Moreover, in the case of cation-sensitive sensors, the selectivity vastly depended on the order of porphyrin units in the dimer. This opens a new approach of regulating and adjusting sensitivity and selectivity of the sensor through the application of complex porphyrin systems with more than one porphyrin units with mix sensitive porphyrins.

  11. Efficient isolation of major procyanidin A-type dimers from peanut skins and B-type dimers from grape seeds

    NARCIS (Netherlands)

    Appeldoorn, M.M.; Sanders, M.B.; Vincken, J.P.; Cheynier, V.; Guerneve, Le C.; Gruppen, H.

    2009-01-01

    In order to fully explore the biofunctional potential of proanthocyanidins (PA), isolated and well-characterised PA dimers are of great importance. Current methods to obtain pure A- and B-type dimers are laborious, because they comprise multiple chromatographic steps, often yielding only one or two

  12. Elastic and viscous properties of the nematic dimer CB7CB

    Science.gov (United States)

    Babakhanova, Greta; Parsouzi, Zeinab; Paladugu, Sathyanarayana; Wang, Hao; Nastishin, Yu. A.; Shiyanovskii, Sergij V.; Sprunt, Samuel; Lavrentovich, Oleg D.

    2017-12-01

    We present a comprehensive set of measurements of optical, dielectric, diamagnetic, elastic, and viscous properties in the nematic (N) phase formed by a liquid crystalline dimer. The studied dimer, 1,7-bis-4-(4'-cyanobiphenyl) heptane (CB7CB), is composed of two rigid rodlike cyanobiphenyl segments connected by a flexible aliphatic link with seven methyl groups. CB7CB and other nematic dimers are of interest due to their tendency to adopt bent configurations and to form two states possessing a modulated nematic director structure, namely, the twist-bend nematic, NTB, and the oblique helicoidal cholesteric, C hOH , which occurs when the achiral dimer is doped with a chiral additive and exposed to an external electric or magnetic field. We characterize the material parameters as functions of temperature in the entire temperature range of the N phase, including the pretransitional regions near the N -NTB and N-to-isotropic (I) transitions. The splay constant K11 is determined by two direct and independent techniques, namely, detection of the Frederiks transition and measurement of director fluctuation amplitudes by dynamic light scattering (DLS). The bend K33 and twist K22 constants are measured by DLS. K33, being the smallest of the three constants, shows a strong nonmonotonous temperature dependence with a negative slope in both N-I and N -NTB pretransitional regions. The measured ratio K11/K22 is larger than 2 in the entire nematic temperature range. The orientational viscosities associated with splay, twist, and bend fluctuations in the N phase are comparable to those of nematics formed by rodlike molecules. All three show strong temperature dependence, increasing sharply near the N -NTB transition.

  13. Structure-Function Analysis of Peroxisomal ATP-binding Cassette Transporters Using Chimeric Dimers*

    Science.gov (United States)

    Geillon, Flore; Gondcaille, Catherine; Charbonnier, Soëli; Van Roermund, Carlo W.; Lopez, Tatiana E.; Dias, Alexandre M. M.; Pais de Barros, Jean-Paul; Arnould, Christine; Wanders, Ronald J.; Trompier, Doriane; Savary, Stéphane

    2014-01-01

    ABCD1 and ABCD2 are two closely related ATP-binding cassette half-transporters predicted to homodimerize and form peroxisomal importers for fatty acyl-CoAs. Available evidence has shown that ABCD1 and ABCD2 display a distinct but overlapping substrate specificity, although much remains to be learned in this respect as well as in their capability to form functional heterodimers. Using a cell model expressing an ABCD2-EGFP fusion protein, we first demonstrated by proximity ligation assay and co-immunoprecipitation assay that ABCD1 interacts with ABCD2. Next, we tested in the pxa1/pxa2Δ yeast mutant the functionality of ABCD1/ABCD2 dimers by expressing chimeric proteins mimicking homo- or heterodimers. For further structure-function analysis of ABCD1/ABCD2 dimers, we expressed chimeric dimers fused to enhanced GFP in human skin fibroblasts of X-linked adrenoleukodystrophy patients. These cells are devoid of ABCD1 and accumulate very long-chain fatty acids (C26:0 and C26:1). We checked that the chimeric proteins were correctly expressed and targeted to the peroxisomes. Very long-chain fatty acid levels were partially restored in transfected X-linked adrenoleukodystrophy fibroblasts regardless of the chimeric construct used, thus demonstrating functionality of both homo- and heterodimers. Interestingly, the level of C24:6 n-3, the immediate precursor of docosahexaenoic acid, was decreased in cells expressing chimeric proteins containing at least one ABCD2 moiety. Our data demonstrate for the first time that both homo- and heterodimers of ABCD1 and ABCD2 are functionally active. Interestingly, the role of ABCD2 (in homo- and heterodimeric forms) in the metabolism of polyunsaturated fatty acids is clearly evidenced, and the chimeric dimers provide a novel tool to study substrate specificity of peroxisomal ATP-binding cassette transporters. PMID:25043761

  14. Structure-function analysis of peroxisomal ATP-binding cassette transporters using chimeric dimers.

    Science.gov (United States)

    Geillon, Flore; Gondcaille, Catherine; Charbonnier, Soëli; Van Roermund, Carlo W; Lopez, Tatiana E; Dias, Alexandre M M; Pais de Barros, Jean-Paul; Arnould, Christine; Wanders, Ronald J; Trompier, Doriane; Savary, Stéphane

    2014-08-29

    ABCD1 and ABCD2 are two closely related ATP-binding cassette half-transporters predicted to homodimerize and form peroxisomal importers for fatty acyl-CoAs. Available evidence has shown that ABCD1 and ABCD2 display a distinct but overlapping substrate specificity, although much remains to be learned in this respect as well as in their capability to form functional heterodimers. Using a cell model expressing an ABCD2-EGFP fusion protein, we first demonstrated by proximity ligation assay and co-immunoprecipitation assay that ABCD1 interacts with ABCD2. Next, we tested in the pxa1/pxa2Δ yeast mutant the functionality of ABCD1/ABCD2 dimers by expressing chimeric proteins mimicking homo- or heterodimers. For further structure-function analysis of ABCD1/ABCD2 dimers, we expressed chimeric dimers fused to enhanced GFP in human skin fibroblasts of X-linked adrenoleukodystrophy patients. These cells are devoid of ABCD1 and accumulate very long-chain fatty acids (C26:0 and C26:1). We checked that the chimeric proteins were correctly expressed and targeted to the peroxisomes. Very long-chain fatty acid levels were partially restored in transfected X-linked adrenoleukodystrophy fibroblasts regardless of the chimeric construct used, thus demonstrating functionality of both homo- and heterodimers. Interestingly, the level of C24:6 n-3, the immediate precursor of docosahexaenoic acid, was decreased in cells expressing chimeric proteins containing at least one ABCD2 moiety. Our data demonstrate for the first time that both homo- and heterodimers of ABCD1 and ABCD2 are functionally active. Interestingly, the role of ABCD2 (in homo- and heterodimeric forms) in the metabolism of polyunsaturated fatty acids is clearly evidenced, and the chimeric dimers provide a novel tool to study substrate specificity of peroxisomal ATP-binding cassette transporters. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Hsa-miR-1587 G-quadruplex formation and dimerization induced by NH4+, molecular crowding environment and jatrorrhizine derivatives.

    Science.gov (United States)

    Tan, Wei; Yi, Long; Zhu, Zhentao; Zhang, Lulu; Zhou, Jiang; Yuan, Gu

    2018-03-01

    A guanine-rich human mature microRNA, miR-1587, was discovered to form stable intramolecular G-quadruplexes in the presence of K + , Na + and low concentration of NH 4 + (25mM) by electrospray ionization mass spectrometry (ESI-MS) combined with circular dichroism (CD) spectroscopy. Furthermore, under high concentration of NH 4 + (100mM) or molecular crowding environments, miR-1587 formed a dimeric G-quadruplex through 3'-to-3' stacking of two monomeric G-quadruplex subunits with one ammonium ion sandwiched between the interfaces. Specifically, two synthesized jatrorrhizine derivatives with terminal amine groups could also induce the dimerization of miR-1587 G-quadruplex and formed 1:1 and 2:1 complexes with the dimeric G-quadruplex. In contrast, jatrorrhizine could bind with the dimeric miR-1587 G-quadruplex, but could not induce dimerization of miR-1587 G-quadruplex. These results provide a new strategy to regulate the functions of miR-1587 through induction of G-quadruplex formation and dimerization. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Optical Fluoride Sensor Based on Monomer-Dimer Equilibrium of Scandium(III)-Octaethylporphyrin in a Plasticized Polymeric Film

    OpenAIRE

    Kang, Youngjea; Kampf, Jeff W.; Meyerhoff, Mark E.

    2007-01-01

    A fluoride-selective optical sensor based on scandium(III) octaethylporphyrin (Sc(III)OEP) as an ionophore within a plasticized PVC film is described. The presence of fluoride ion in the aqueous sample phase increases the formation of a difluoro-bridged Sc(III)OEP dimer species in the polymer film. The ability of the Sc(III) porphyrin to form the dimeric structure in the presence of fluoride is confirmed by UV-Vis spectroscopy and X-ray crystallography. For more practical sensing applications...

  17. Dimerization and DNA-binding of ASR1, a small hydrophilic protein abundant in plant tissues suffering from water loss

    International Nuclear Information System (INIS)

    Maskin, Laura; Frankel, Nicolas; Gudesblat, Gustavo; Demergasso, Maria J.; Pietrasanta, Lia I.; Iusem, Norberto D.

    2007-01-01

    The Asr gene family is present in Spermatophyta. Its members are generally activated under water stress. We present evidence that tomato ASR1, one of the proteins of the family, accumulates in seed during late stages of embryogenesis, a physiological process characterized by water loss. In vitro, electrophoretic assays show a homo-dimeric structure for ASR1 and highlight strong non-covalent interactions between monomers prone to self-assemble. Direct visualization of single molecules by atomic force microscopy (AFM) confirms that ASR1 forms homodimers and that uncovers both monomers and dimers bind double stranded DNA

  18. Complex forms of mitochondrial DNA in human B cells transformed by Epstein-Barr virus (EBV)

    DEFF Research Database (Denmark)

    Christiansen, Gunna; Christiansen, C; Zeuthen, J

    1983-01-01

    Human lymphocytes and lymphoid cell lines were analyzed for the presence of complex forms of mitochondrial DNA (mtDNA) by electron microscopy. A high frequency (9%-14.5%) of catenated dimers, circular dimers, or oligomers were found in samples from Epstein-Barr-virus-(EBV) transformed lymphoblast......Human lymphocytes and lymphoid cell lines were analyzed for the presence of complex forms of mitochondrial DNA (mtDNA) by electron microscopy. A high frequency (9%-14.5%) of catenated dimers, circular dimers, or oligomers were found in samples from Epstein-Barr-virus-(EBV) transformed...

  19. DENV gene of bacteriophage T4 codes for both pyrimidine dimer-DNA glycosylase and apyrimidinic endonuclease activities

    International Nuclear Information System (INIS)

    McMillan, S.; Edenberg, H.J.; Radany, E.H.; Friedberg, R.C.; Friedberg, E.C.

    1981-01-01

    Recent studies have shown that purified preparations of phage T4 UV DNA-incising activity (T4 UV endonuclease or endonuclease V of phase T4) contain a pyrimidine dimer-DNA glycosylase activity that catalyzes hydrolysis of the 5' glycosyl bond of dimerized pyrimidines in UV-irradiated DNA. Such enzyme preparations have also been shown to catalyze the hydrolysis of phosphodiester bonds in UV-irradiated DNA at a neutral pH, presumably reflecting the action of an apurinic/apyrimidinic endonuclease at the apyrimidinic sites created by the pyrimidine dimer-DNA glycosylase. In this study we found that preparations of T4 UV DNA-incising activity contained apurinic/apyrimidinic endonuclease activity that nicked depurinated form I simian virus 40 DNA. Apurinic/apyrimidinic endonuclease activity was also found in extracts of Escherichia coli infected with T4 denV + phage. Extracts of cells infected with T4 denV mutants contained significantly lower levels of apurinic/apyrimidinic endonuclease activity; these levels were no greater than the levels present in extracts of uninfected cells. Furthermore, the addition of DNA containing UV-irradiated DNA and T4 enzyme resulted in competition for pyrimidine dimer-DNA glycosylase activity against the UV-irradiated DNA. On the basis of these results, we concluded that apurinic/apyrimidinic endonuclease activity is encoded by the denV gene of phage T4, the same gene that codes for pyrimidine dimer-DNA glycosylase activity

  20. Conformational landscape of the SF6dimer as revealed by high resolution infrared spectroscopy and complexation with rare gas atoms.

    Science.gov (United States)

    Asselin, Pierre; Potapov, Alexey; Turner, Andrew C; Boudon, Vincent; Bruel, Laurent; Gaveau, Marc-André; Mons, Michel

    2017-07-14

    Taking advantage of a versatile set-up, combining pulsed pin hole or slit nozzle supersonic expansion with an external cavity quantum cascade laser, the rovibrational absorption spectrum of the SF 6 dimer in the ν 3 mode region has been revisited at high resolution under various experimental conditions in SF 6 :He mixtures. Two new rotationally resolved spectral bands have been identified in the range of the parallel band of the dimer spectrum in addition to that previously reported. Among these three spectral features, two of them are assigned to conformations of the dimer (noted #1 and #2), clearly distinguished from their different S-S interatomic distances, i.e. 474 and 480 pm respectively. The third one is assigned to a (SF 6 ) 2 -He complex, from comparison with additional experiments in which (SF 6 ) 2 -Rg heterotrimers (Rg = Ne, Ar, Kr, Xe) are observed. A schematic picture of the potential energy landscape of the SF 6 dimer in terms of a nearly flat surface is proposed to account for the conformational relaxation observed in the expansions and for the structure of the (SF 6 ) 2 -Rg heterotrimers, which are exclusively formed from the conformer #2 dimer. Although modelling qualitatively supports this picture, much effort has still to be achieved from a theoretical point of view to reach a quantitative agreement with the present benchmark experimental data both in terms of structure and energetics.

  1. Developmental regulation of synthesis and dimerization of the amyloidogenic protease inhibitor cystatin C in the hematopoietic system.

    Science.gov (United States)

    Xu, Yuekang; Lindemann, Petra; Vega-Ramos, Javier; Zhang, Jian-Guo; Villadangos, Jose A

    2014-04-04

    The cysteine protease inhibitor cystatin C is thought to be secreted by most cells and eliminated in the kidneys, so its concentration in plasma is diagnostic of kidney function. Low extracellular cystatin C is linked to pathologic protease activity in cancer, arthritis, atherosclerosis, aortic aneurism, and emphysema. Cystatin C forms non-inhibitory dimers and aggregates by a mechanism known as domain swapping, a property that reportedly protects against Alzheimer disease but can also cause amyloid angiopathy. Despite these clinical associations, little is known about the regulation of cystatin C production, dimerization, and secretion. We show that hematopoietic cells are major contributors to extracellular cystatin C levels in healthy mice. Among these cells, macrophages and dendritic cells (DC) are the predominant producers of cystatin C. Both cell types synthesize monomeric and dimeric cystatin C in vivo, but only secrete monomer. Dimerization occurs co-translationally in the endoplasmic reticulum and is regulated by the levels of reactive oxygen species (ROS) derived from mitochondria. Drugs or stimuli that reduce the intracellular concentration of ROS inhibit cystatin C dimerization. The extracellular concentration of inhibitory cystatin C is thus partly dependent on the abundance of macrophages and DC, and the ROS levels. These results have implications for the diagnostic use of serum cystatin C as a marker of kidney function during inflammatory processes that induce changes in DC or macrophage abundance. They also suggest an important role for macrophages, DC, and ROS in diseases associated with the protease inhibitory activity or amyloidogenic properties of cystatin C.

  2. Developmental Regulation of Synthesis and Dimerization of the Amyloidogenic Protease Inhibitor Cystatin C in the Hematopoietic System*

    Science.gov (United States)

    Xu, Yuekang; Lindemann, Petra; Vega-Ramos, Javier; Zhang, Jian-Guo; Villadangos, Jose A.

    2014-01-01

    The cysteine protease inhibitor cystatin C is thought to be secreted by most cells and eliminated in the kidneys, so its concentration in plasma is diagnostic of kidney function. Low extracellular cystatin C is linked to pathologic protease activity in cancer, arthritis, atherosclerosis, aortic aneurism, and emphysema. Cystatin C forms non-inhibitory dimers and aggregates by a mechanism known as domain swapping, a property that reportedly protects against Alzheimer disease but can also cause amyloid angiopathy. Despite these clinical associations, little is known about the regulation of cystatin C production, dimerization, and secretion. We show that hematopoietic cells are major contributors to extracellular cystatin C levels in healthy mice. Among these cells, macrophages and dendritic cells (DC) are the predominant producers of cystatin C. Both cell types synthesize monomeric and dimeric cystatin C in vivo, but only secrete monomer. Dimerization occurs co-translationally in the endoplasmic reticulum and is regulated by the levels of reactive oxygen species (ROS) derived from mitochondria. Drugs or stimuli that reduce the intracellular concentration of ROS inhibit cystatin C dimerization. The extracellular concentration of inhibitory cystatin C is thus partly dependent on the abundance of macrophages and DC, and the ROS levels. These results have implications for the diagnostic use of serum cystatin C as a marker of kidney function during inflammatory processes that induce changes in DC or macrophage abundance. They also suggest an important role for macrophages, DC, and ROS in diseases associated with the protease inhibitory activity or amyloidogenic properties of cystatin C. PMID:24570004

  3. Conformationally constrained peptides target the allosteric kinase dimer interface and inhibit EGFR activation.

    Science.gov (United States)

    Fulton, Melody D; Hanold, Laura E; Ruan, Zheng; Patel, Sneha; Beedle, Aaron M; Kannan, Natarajan; Kennedy, Eileen J

    2018-03-15

    Although EGFR is a highly sought-after drug target, inhibitor resistance remains a challenge. As an alternative strategy for kinase inhibition, we sought to explore whether allosteric activation mechanisms could effectively be disrupted. The kinase domain of EGFR forms an atypical asymmetric dimer via head-to-tail interactions and serves as a requisite for kinase activation. The kinase dimer interface is primarily formed by the H-helix derived from one kinase monomer and the small lobe of the second monomer. We hypothesized that a peptide designed to resemble the binding surface of the H-helix may serve as an effective disruptor of EGFR dimerization and activation. A library of constrained peptides was designed to mimic the H-helix of the kinase domain and interface side chains were optimized using molecular modeling. Peptides were constrained using peptide "stapling" to structurally reinforce an alpha-helical conformation. Peptide stapling was demonstrated to notably enhance cell permeation of an H-helix derived peptide termed EHBI2. Using cell-based assays, EHBI2 was further shown to significantly reduce EGFR activity as measured by EGFR phosphorylation and phosphorylation of the downstream signaling substrate Akt. To our knowledge, this is the first H-helix-based compound targeting the asymmetric interface of the kinase domain that can successfully inhibit EGFR activation and signaling. This study presents a novel, alternative targeting site for allosteric inhibition of EGFR. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Structural basis for the cooperative DNA recognition by Smad4 MH1 dimers

    Science.gov (United States)

    Baburajendran, Nithya; Jauch, Ralf; Tan, Clara Yueh Zhen; Narasimhan, Kamesh; Kolatkar, Prasanna R.

    2011-01-01

    Smad proteins form multimeric complexes consisting of the ‘common partner’ Smad4 and receptor regulated R-Smads on clustered DNA binding sites. Deciphering how pathway specific Smad complexes multimerize on DNA to regulate gene expression is critical for a better understanding of the cis-regulatory logic of TGF-β and BMP signaling. To this end, we solved the crystal structure of the dimeric Smad4 MH1 domain bound to a palindromic Smad binding element. Surprisingly, the Smad4 MH1 forms a constitutive dimer on the SBE DNA without exhibiting any direct protein–protein interactions suggesting a DNA mediated indirect readout mechanism. However, the R-Smads Smad1, Smad2 and Smad3 homodimerize with substantially decreased efficiency despite pronounced structural similarities to Smad4. Therefore, intricate variations in the DNA structure induced by different Smads and/or variant energetic profiles likely contribute to their propensity to dimerize on DNA. Indeed, competitive binding assays revealed that the Smad4/R-Smad heterodimers predominate under equilibrium conditions while R-Smad homodimers are least favored. Together, we present the structural basis for DNA recognition by Smad4 and demonstrate that Smad4 constitutively homo- and heterodimerizes on DNA in contrast to its R-Smad partner proteins by a mechanism independent of direct protein contacts. PMID:21724602

  5. pH controlled assembly of a self-complementary halogen-bonded dimer.

    Science.gov (United States)

    Maugeri, Leonardo; Jamieson, Ellen M G; Cordes, David B; Slawin, Alexandra M Z; Philp, Douglas

    2017-02-01

    Phenols and their corresponding phenoxide anions can form halogen bonds with neutral iodotriazoles. The strength of these interactions depends critically on the protonation state of the oxygen atom - the interaction of the phenoxide anion is more than an order of magnitude stronger than the corresponding phenol. The assembly of a molecule bearing both an iodotriazole and a phenoxide anion into a self-complementary dimer, stabilised by two halogen bonds between the phenoxide anions and the neutral iodotriazoles has been demonstrated. The corresponding phenol shows no halogen bond mediated assembly either in the solid or in the solution state. This assembly process can be actuated simply by a change in protonation state - treatment of the phenol with one equivalent of base results in deprotonation and assembly of the dimer. The structure of the homodimer formed by the phenoxide-bearing iodotriazole has been determined in the solid state and 19 F NMR spectroscopy demonstrates that the assembled dimer persists in solution and that it has significant stability. 19 F NMR spectroscopy has also been used to demonstrate that the assembly process is completely reversible.

  6. Insights into the photochemical disproportionation of transition metal dimers on the picosecond time scale.

    Science.gov (United States)

    Lomont, Justin P; Nguyen, Son C; Harris, Charles B

    2013-05-09

    The reactivity of five transition metal dimers toward photochemical, in-solvent-cage disproportionation has been investigated using picosecond time-resolved infrared spectroscopy. Previous ultrafast studies on [CpW(CO)3]2 established the role of an in-cage disproportionation mechanism involving electron transfer between 17- and 19-electron radicals prior to diffusion out of the solvent cage. New results from time-resolved infrared studies reveal that the identity of the transition metal complex dictates whether the in-cage disproportionation mechanism can take place, as well as the more fundamental issue of whether 19-electron intermediates are able to form on the picosecond time scale. Significantly, the in-cage disproportionation mechanism observed previously for the tungsten dimer does not characterize the reactivity of four out of the five transition metal dimers in this study. The differences in the ability to form 19-electron intermediates are interpreted either in terms of differences in the 17/19-electron equilibrium or of differences in an energetic barrier to associative coordination of a Lewis base, whereas the case for the in-cage vs diffusive disproportionation mechanisms depends on whether the 19-electron reducing agent is genuinely characterized by 19-electron configuration at the metal center or if it is better described as an 18 + δ complex. These results help to better understand the factors that dictate mechanisms of radical disproportionation and carry implications for radical chain mechanisms.

  7. Asymmetric monometallic nanorod nanoparticle dimer and related compositions and methods

    KAUST Repository

    Han, Yu

    2016-03-31

    The fabrication of asymmetric monometallic nanocrystals with novel properties for plasmonics, nanophotonics and nanoelectronics. Asymmetric monometallic plasmonic nanocrystals are of both fundamental synthetic challenge and practical significance. In an example, a thiol-ligand mediated growth strategy that enables the synthesis of unprecedented Au Nanorod-Au Nanoparticle (AuNR-AuNP) dimers from pre-synthesized AuNR seeds. Using high-resolution electron microscopy and tomography, crystal structure and three-dimensional morphology of the dimer, as well as the growth pathway of the AuNP on the AuNR seed, was investigated for this example. The dimer exhibits an extraordinary broadband optical extinction spectrum spanning the UV, visible, and near infrared regions (300 - 1300 nm). This unexpected property makes the AuNR-AuNP dimer example useful for many nanophotonic applications. In two experiments, the dimer example was tested as a surface- enhanced Raman scattering (SERS) substrate and a solar light harvester for photothermal conversion, in comparison with the mixture of AuNR and AuNP. In the SERS experiment, the dimer example showed an enhancement factor about 10 times higher than that of the mixture, when the excitation wavelength (660 nm) was off the two surface plasmon resonance (SPR) bands of the mixture. In the photothermal conversion experiment under simulated sunlight illumination, the dimer example exhibited an energy conversion efficiency about 1.4 times as high as that of the mixture.

  8. Role of cyclobutane dimers in UV-denaturation of DNA

    International Nuclear Information System (INIS)

    Zavil'gel'skij, G.B.; Zuev, A.V.

    1978-01-01

    UV irradiation of double-stranded DNA produces local denatured regions. The evidence presented indicates that these single-stranded regions arise from photoproducts other than pyrimidine dimers. The irradiation of T2 DNA at 8x10 4 erg/mm 2 (254 nm) produces 6-8% thymine dimers, amd Tsub(mel) drops by 12-14 deg C, accompanied by a significant broadening of the transition profile. The kinetics of denatured region formation and lowering Tsub(mel) corresponds to that of formation of crosslinkages and differs markedly from the kinetics of formation of cyclobutane pyrimidine dimers. Treatment of UV-irradiated DNA with light in the presence of yeast photoreactivating enzyme monomerizes almost all thymine dimers but does not change the Tsub(mel). Local denatured regions are detected in UV-irradiated DNA and are absent from AcPhM-sensibilized DNA, which contains 20-25% thymine dimers, as determined by the accridine orange fluorescence technique. S1 nuclease from Aspergillis oryzae produces single-strand breaks in UV-irradiated DNA of phage PM2 but is not active on AcPhM-treated PM2 DNA, which contains about 50 thymine dimers. It is supposed that the formation of a cyclobutane dimer only weakens the hydrogen bonds in the AT base pair rather than breaks them. Local denatured regions are thought to arise from the accumulation in UV-irradiated DNA (254 nm) of the sufficient number of photoproducts with impaired ability to base pairing

  9. Formation and occurrence of dimer esters of pinene oxidation products in atmospheric aerosols

    DEFF Research Database (Denmark)

    Kristensen, K.; Enggrob, Kirsten; King, Stephanie Michelle

    2013-01-01

    The formation of carboxylic acids and dimer esters from alpha-pinene oxidation was investigated in a smog chamber and in ambient aerosol samples collected during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX). Chamber experiments of alpha-pinene ozonolysis in dry air...... precursors. However, the sampling time resolution precluded conclusive evidence regarding formation from gas- or particle-phase processes. CCN activities of the particles formed in the smog chamber displayed a modest variation during the course of experiments, with kappa values in the range 0......-diaterpenyl ester was found at higher concentrations under higher temperature conditions, both in the smog-chamber study and in ambient air aerosol samples, and exhibited much higher concentrations at night relative to day-time in line with previous results. We conclude that analysis of pinyl dimer esters provides...

  10. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    understanding of form per se, or, to use an expression from this text, of form as form. This challenge can be reduced to one question: how can design teaching support students in achieving not only the ability to recognize and describe different form-related concepts in existing design (i.e. analytical...... and concepts from real designs by studying form in abstract contexts. The challenge for the first approach is how to support students in decoupling form from the work as a whole. The challenge for the second approach is how to translate general form into real design. Hence, choosing between the two approaches...

  11. Vison excitations in near-critical quantum dimer models

    Science.gov (United States)

    Strübi, G.; Ivanov, D. A.

    2011-06-01

    We study vison excitations in a quantum dimer model interpolating between the Rokhsar-Kivelson models on the square and triangular lattices. In the square-lattice case, the model is known to be critical and characterized by U(1) topological quantum numbers. Introducing diagonal dimers brings the model to a Z2 resonating-valence-bond phase. We study variationally the emergence of vison excitations at low concentration of diagonal dimers, close to the critical point. We find that, in this regime, vison excitations are large in size and their structure resembles vortices in type-II superconductors.

  12. Family C 7TM receptor dimerization and activation

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Sheikh, Søren P; Hansen, Jakob Lerche

    2006-01-01

    changes that lead to receptor activation. Despite extensive studies of the receptor transmembrane domain, several key features, including the exact organization of the complete receptor dimer, the sequence of events leading to receptor activation, and the functional significance of dimerization, have yet...... to be fully defined. This review presents the biochemical support for family C 7TM receptor dimerization and discusses its importance for receptor biosynthesis, surface expression, ligand binding and activation, since lessons learnt here may well be applicable to the whole superfamily of 7TM receptors....

  13. Photoelectron Spectroscopy of 4-Bromochlorobenzene Dimer and Trimer Anions

    International Nuclear Information System (INIS)

    Kim, Namdoo

    2013-01-01

    I investigated the electron attachment to 4-BCB dimer and trimer anions using anion photoelectron spectroscopy and theoretical calculations. I found that an excess electron can be delocalized to these clusters through extended π-network. However, the nature of the ion core is different for the dimer and trimer. For the heterodimer anions, the geometry is determined by the differences in electronegativity of the molecules. Dimer anions with a large electronegativity difference have T-shaped geometries and those with a small electronegativity difference have PD geometries

  14. Self-Assembling Multifunctional Peptide Dimers for Gene Delivery Systems

    Directory of Open Access Journals (Sweden)

    Kitae Ryu

    2015-01-01

    Full Text Available Self-assembling multifunctional peptide was designed for gene delivery systems. The multifunctional peptide (MP consists of cellular penetrating peptide moiety (R8, matrix metalloproteinase-2 (MMP-2 specific sequence (GPLGV, pH-responsive moiety (H5, and hydrophobic moiety (palmitic acid (CR8GPLGVH5-Pal. MP was oxidized to form multifunctional peptide dimer (MPD by DMSO oxidation of thiols in terminal cysteine residues. MPD could condense pDNA successfully at a weight ratio of 5. MPD itself could self-assemble into submicron micelle particles via hydrophobic interaction, of which critical micelle concentration is about 0.01 mM. MPD showed concentration-dependent but low cytotoxicity in comparison with PEI25k. MPD polyplexes showed low transfection efficiency in HEK293 cells expressing low level of MMP-2 but high transfection efficiency in A549 and C2C12 cells expressing high level of MMP-2, meaning the enhanced transfection efficiency probably due to MMP-induced structural change of polyplexes. Bafilomycin A1-treated transfection results suggest that the transfection of MPD is mediated via endosomal escape by endosome buffering ability. These results show the potential of MPD for MMP-2 targeted gene delivery systems due to its multifunctionality.

  15. Bright Solitons in a PT-Symmetric Chain of Dimers

    Directory of Open Access Journals (Sweden)

    Omar B. Kirikchi

    2016-01-01

    Full Text Available We study the existence and stability of fundamental bright discrete solitons in a parity-time- (PT- symmetric coupler composed by a chain of dimers that is modelled by linearly coupled discrete nonlinear Schrödinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anticontinuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, in contrast to the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quartet of complex eigenvalues. In general, the gain-loss term can be considered parasitic as it reduces the stability region of the onsite solitons. Additionally, we analyse the dynamic behaviour of the onsite and intersite solitons when unstable, where typically it is either in the form of travelling solitons or soliton blow-ups.

  16. Dimer-based model for heptaspanning membrane receptors.

    Science.gov (United States)

    Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferré, Sergi; Fuxe, Kjell; Cortés, Antonio; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

    2005-07-01

    The existence of intramembrane receptor-receptor interactions for heptaspanning membrane receptors is now fully accepted, but a model considering dimers as the basic unit that binds to two ligand molecules is lacking. Here, we propose a two-state-dimer model in which the ligand-induced conformational changes from one component of the dimer are communicated to the other. Our model predicts cooperativity in binding, which is relevant because the other current models fail to address this phenomenon satisfactorily. Our two-state-dimer model also predicts the variety of responses elicited by full or partial agonists, neutral antagonists and inverse agonists. This model can aid our understanding of the operation of heptaspanning receptors and receptor channels, and, potentially, be important for improving the treatment of cardiovascular, neurological and neuropsychyatric diseases.

  17. Dimers on Surface Graphs and Spin Structures. I

    DEFF Research Database (Denmark)

    Cimasoni, David; Reshetikhin, Nicolai

    2007-01-01

    Partition functions for dimers on closed oriented surfaces are known to be alternating sums of Pfaffians of Kasteleyn matrices. In this paper, we obtain the formula for the coefficients in terms of discrete spin structures....

  18. Naturally Occurring Diterpenoid Dimers: Source, Biosynthesis, Chemistry and Bioactivities.

    Science.gov (United States)

    Lin, Li-Gen; Ung, Carolina Oi Lam; Feng, Zhe-Ling; Huang, Li; Hu, Hao

    2016-10-01

    Diterpenoid dimers are rare in nature and mainly found in higher plants including the families Acanthaceae, Annonaceae, Asteraceae, Calceolariaceae, Chrysobalanaceae, Cupressaceae, Euphorbiaceae, Fabaceae, Lamiaceae, Liliaceae, Meliaceae, Rhizophoraceae, Taxaceae, Velloziaceae, and Zingiberaceae. In addition, a few diterpenoid dimers have been also reported from fungi (Psathyrellaceae), liverworts (Scapaniaceae), and a gorgonian (Gorgoniidae). They feature a wide variety of structures due to different core skeletons, linkage patterns, substituents, and configurations. Accordingly, diterpenoid dimers exhibit a broad range of bioactivities, including cytotoxic, anti-inflammatory, antimicrobial, antimalarial, and antifouling properties, which have attracted more and more research interests in the past decades. This review with 176 metabolites from 109 references provides a comprehensive and up-to-date overview of the source, biosynthesis, structure, synthesis, and bioactivities of diterpenoid dimers. Georg Thieme Verlag KG Stuttgart · New York.

  19. Atomic model for the dimeric FOregion of mitochondrial ATP synthase.

    Science.gov (United States)

    Guo, Hui; Bueler, Stephanie A; Rubinstein, John L

    2017-11-17

    Mitochondrial adenosine triphosphate (ATP) synthase produces the majority of ATP in eukaryotic cells, and its dimerization is necessary to create the inner membrane folds, or cristae, characteristic of mitochondria. Proton translocation through the membrane-embedded F O region turns the rotor that drives ATP synthesis in the soluble F 1 region. Although crystal structures of the F 1 region have illustrated how this rotation leads to ATP synthesis, understanding how proton translocation produces the rotation has been impeded by the lack of an experimental atomic model for the F O region. Using cryo-electron microscopy, we determined the structure of the dimeric F O complex from Saccharomyces cerevisiae at a resolution of 3.6 angstroms. The structure clarifies how the protons travel through the complex, how the complex dimerizes, and how the dimers bend the membrane to produce cristae. Copyright © 2017, American Association for the Advancement of Science.

  20. Antiplasmodial dimeric chalcone derivatives from the roots of Uvaria siamensis.

    Science.gov (United States)

    Salae, Abdul-Wahab; Chairerk, Orapan; Sukkoet, Piyanut; Chairat, Therdsak; Prawat, Uma; Tuntiwachwuttikul, Pittaya; Chalermglin, Piya; Ruchirawat, Somsak

    2017-03-01

    Four dimeric chalcone derivatives, 8″,9″-dihydrowelwitschin H, uvarins A-C, a naphthalene derivative, 2-hydroxy-3-methoxy-6-(4'- hydroxyphenyl)naphthalene, and the known dimeric chalcones, dependensin and welwitschin E, flavonoids, a cyclohexane oxide derivative, an aromatic aldehyde were isolated from the roots of Uvaria siamensis (Annonaceae). The structures of the compounds were elucidated by spectroscopic analysis, as well as by comparison with literature data. The isolated compounds with a sufficient amount for biological assays were evaluated for their antimalarial, antimycobacterial, and cytotoxic activities. The dimeric chalcones 8″,9″-dihydrowelwitschin H, uvarins B and C, dependensin and welwitschin E showed strong antiplasmodial activity with IC 50 values of 3.10, 3.02, 3.09, 4.21 and 3.99 μg/mL, respectively. A possible biosynthesis pathway of the dimeric chalcones is discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Aberrant phenotypes of transgenic mice expressing dimeric human erythropoietin

    Directory of Open Access Journals (Sweden)

    Yun Seong-Jo

    2012-01-01

    Full Text Available Abstract Background Dimeric human erythropoietin (dHuEPO peptides are reported to exhibit significantly higher biological activity than the monomeric form of recombinant EPO. The objective of this study was to produce transgenic (tg mice expressing dHuEPO and to investigate the characteristics of these mice. Methods A dHuEPO-expressing vector under the control of the goat beta-casein promoter, which produced a dimer of human EPO molecules linked by a 2-amino acid peptide linker (Asp-Ile, was constructed and injected into 1-cell fertilized embryos by microinjection. Mice were screened using genomic DNA samples obtained from tail biopsies. Blood samples were obtained by heart puncture using heparinized tubes, and hematologic parameters were assessed. Using the microarray analysis tool, we analyzed differences in gene expression in the spleens of tg and control mice. Results A high rate of spontaneous abortion or death of the offspring was observed in the recipients of dHuEPO embryos. We obtained 3 founder lines (#4, #11, and #47 of tg mice expressing the dHuEPO gene. However, only one founder line showed stable germline integration and transmission, subsequently establishing the only transgenic line (#11. We obtained 2 F1 mice and 3 F2 mice from line #11. The dHuEPO protein could not be obtained because of repeated spontaneous abortions in the tg mice. Tg mice exhibited symptoms such as short lifespan and abnormal blood composition. The red blood cell count, white blood cell count, and hematocrit levels in the tg mice were remarkably higher than those in the control mice. The spleens of the tg mice (F1 and F2 females were 11- and -21-fold larger than those of the control mice. Microarray analysis revealed 2,672 spleen-derived candidate genes; more genes were downregulated than upregulated (849/764. Reverse transcriptase-polymerase chain reaction (RT-PCR and quantitative real-time PCR (qRT-PCR were used for validating the results of the microarray

  2. The influence of strain on the diffusion of Si dimers on Si(001)

    NARCIS (Netherlands)

    Zoethout, E.; Zoethout, E.; Gurlu, O.; Gürlü, O.; Zandvliet, Henricus J.W.; Poelsema, Bene

    2000-01-01

    The influence of lattice mismatch-induced tensile strain on the diffusion of Si dimers on Si(001) has been studied. The rate of surface diffusion of a Si dimer along the substrate dimer rows is relatively insensitive to tensile strain, whereas the rate of diffusion for a Si dimer across the

  3. Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers

    Science.gov (United States)

    Pease, Christopher; Etheridge, J.; Wijesinghe, H. S.; Pierce, C. J.; Prikockis, M. V.; Sooryakumar, R.

    Chains of micro-magnetic particles are often rotated with external magnetic fields for many lab-on-a-chip technologies such as transporting beads or mixing fluids. These applications benefit from faster responses of the actuated particles. In a rotating magnetic field, the magnetization of superparamagnetic beads, created from embedded magnetic nano-particles within a polymer matrix, is largely characterized by induced dipoles mip along the direction of the field. In addition there is often a weak dipole mop that orients out-of-phase with the external rotating field. On a two-bead dimer, the simplest chain of beads, mop contributes a torque Γm in addition to the torque from mip. For dimers with beads unbound to each other, mop rotates individual beads which generate an additional hydrodynamic torque on the dimer. Whereas, mop directly torques bound dimers. Our results show that Γm significantly alters the average frequency-dependent dimer rotation rate for both bound and unbound monomers and, when mop exceeds a critical value, increases the maximum dimer rotation frequency. Models that include magnetic and hydrodynamics torques provide good agreement with the experimental findings over a range of field frequencies.

  4. Pair Interaction of Catalytical Sphere Dimers in Chemically Active Media

    Directory of Open Access Journals (Sweden)

    Jing-Min Shi

    2018-01-01

    Full Text Available We study the pair dynamics of two self-propelled sphere dimers in the chemically active medium in which a cubic autocatalytic chemical reaction takes place. Concentration gradient around the dimer, created by reactions occurring on the catalytic sphere surface and responsible for the self-propulsion, is greatly influenced by the chemical activities of the environment. Consequently, the pair dynamics of two dimers mediated by the concentration field are affected. In the particle-based mesoscopic simulation, we combine molecular dynamics (MD for potential interactions and reactive multiparticle collision dynamics (RMPC for solvent flow and bulk reactions. Our results indicate three different configurations between a pair of dimers after the collision, i.e., two possible scenarios of bound dimer pairs and one unbound dimer pair. A phase diagram is sketched as a function of the rate coefficients of the environment reactions. Since the pair interactions are the basic elements of larger scale systems, we believe the results may shed light on the understanding of the collective dynamics.

  5. VUV spectroscopy of rare gas van der Waals dimers

    International Nuclear Information System (INIS)

    Dehmer, P.M.; Pratt, S.T.

    1982-01-01

    We have undertaken a systematic study of the photoionization spectra of the homonuclear and heteronuclear rare gas dimers in order to better understand the nature of the bonding in the Rydberg states adnd ions of these molecules. We have obtained results for Ar 2 , Kr 2 , Xe 2 , NeAr, NeKr, NeXe, ArKr, ArXe, and KrXe. Of the remaining dimer species (Ne 2 and the Herare gas dimers), only Ne 2 has been studied using photoionization mass spectrometry. The results of the present series of experiments provide information both on the excited states of the neutral dimers and on the ground and excited states of the dimer ions. Using the data obtained in these measurements, we are able to compile for the first time a nearly complete list of ground state dissociation energies for the homonuclear and heteronuclear rare gas dimer ions. Somewhat less complete results are obtained for the excited states of these species. The observed trends in binding energy provide an excellent example of the systematic changes that occur as a result of changes in atomic orbital energies, polarizability, and internuclear distance, and these trends can be explained qualitatively in terms of simple molecular orbital theory

  6. Emergence of long-range order in sheets of magnetic dimers

    Science.gov (United States)

    Haravifard, S.; Banerjee, A.; van Wezel, J.; Silevitch, D. M.; dos Santos, A. M.; Lang, J. C.; Kermarrec, E.; Srajer, G.; Gaulin, B. D.; Molaison, J. J.; Dabkowska, H. A.; Rosenbaum, T. F.

    2014-01-01

    Quantum spins placed on the corners of a square lattice can dimerize and form singlets, which then can be transformed into a magnetic state as the interactions between dimers increase beyond threshold. This is a strictly 2D transition in theory, but real-world materials often need the third dimension to stabilize long-range order. We use high pressures to convert sheets of Cu2+ spin 1/2 dimers from local singlets to global antiferromagnet in the model system SrCu2(BO3)2. Single-crystal neutron diffraction measurements at pressures above 5 GPa provide a direct signature of the antiferromagnetic ordered state, whereas high-resolution neutron powder and X-ray diffraction at commensurate pressures reveal a tilting of the Cu spins out of the plane with a critical exponent characteristic of 3D transitions. The addition of anisotropic, interplane, spin–orbit terms in the venerable Shastry–Sutherland Hamiltonian accounts for the influence of the third dimension. PMID:25246541

  7. Atom-dimer scattering in a heteronuclear mixture with a finite intraspecies scattering length

    Science.gov (United States)

    Gao, Chao; Zhang, Peng

    2018-04-01

    We study the three-body problem of two ultracold identical bosonic atoms (denoted by B ) and one extra atom (denoted by X ), where the scattering length aB X between each bosonic atom and atom X is resonantly large and positive. We calculate the scattering length aad between one bosonic atom and the shallow dimer formed by the other bosonic atom and atom X , and investigate the effect induced by the interaction between the two bosonic atoms. We find that even if this interaction is weak (i.e., the corresponding scattering length aB B is of the same order of the van der Waals length rvdW or even smaller), it can still induce a significant effect for the atom-dimer scattering length aad. Explicitly, an atom-dimer scattering resonance can always occur when the value of aB B varies in the region with | aB B|≲ rvdW . As a result, both the sign and the absolute value of aad, as well as the behavior of the aad-aB X function, depends sensitively on the exact value of aB B. Our results show that, for a good quantitative theory, the intraspecies interaction is required to be taken into account for this heteronuclear system, even if this interaction is weak.

  8. Electron spectral functions in a quantum dimer model for topological metals

    Science.gov (United States)

    Huber, Sebastian; Feldmeier, Johannes; Punk, Matthias

    2018-02-01

    We study single-electron spectral functions in a quantum dimer model introduced by Punk, Allais, and Sachdev in Ref. [M. Punk, A. Allais, and S. Sachdev, Proc. Natl. Acad. Sci. U.S.A. 112, 9552 (2015), 10.1073/pnas.1512206112]. The Hilbert space of this model is spanned by hard-core coverings of the square lattice with two types of dimers: ordinary bosonic spin singlets, as well as fermionic dimers carrying charge +e and spin 1/2, which can be viewed as bound states of spinons and holons in a doped resonating valence bond (RVB) liquid. This model realizes a metallic phase with topological order and captures several properties of the pseudogap phase in hole-doped cuprates, such as a reconstructed Fermi surface with small hole pockets and a highly anisotropic quasiparticle residue in the absence of any broken symmetries. Using a combination of exact diagonalization and analytical methods, we compute electron spectral functions and show that this model indeed exhibits a sizable antinodal pseudogap, with a momentum dependence deviating from a simple d -wave form, in accordance with experiments on underdoped cuprates.

  9. Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNA.

    Science.gov (United States)

    Gamache, Eric R; Doh, Jung H; Ritz, Justin; Laederach, Alain; Bellaousov, Stanislav; Mathews, David H; Curcio, M Joan

    2017-04-26

    The genomic RNA of the retrotransposon Ty1 is packaged as a dimer into virus-like particles. The 5' terminus of Ty1 RNA harbors cis -acting sequences required for translation initiation, packaging and initiation of reverse transcription (TIPIRT). To identify RNA motifs involved in dimerization and packaging, a structural model of the TIPIRT domain in vitro was developed from single-nucleotide resolution RNA structural data. In general agreement with previous models, the first 326 nucleotides of Ty1 RNA form a pseudoknot with a 7-bp stem (S1), a 1-nucleotide interhelical loop and an 8-bp stem (S2) that delineate two long, structured loops. Nucleotide substitutions that disrupt either pseudoknot stem greatly reduced helper-Ty1-mediated retrotransposition of a mini-Ty1, but only mutations in S2 destabilized mini-Ty1 RNA in cis and helper-Ty1 RNA in trans. Nested in different loops of the pseudoknot are two hairpins with complementary 7-nucleotide motifs at their apices. Nucleotide substitutions in either motif also reduced retrotransposition and destabilized mini- and helper-Ty1 RNA. Compensatory mutations that restore base-pairing in the S2 stem or between the hairpins rescued retrotransposition and RNA stability in cis and trans. These data inform a model whereby a Ty1 RNA kissing complex with two intermolecular kissing-loop interactions initiates dimerization and packaging.

  10. Quantitative determination of cyclobutane thymine dimers in DNA by stable isotope-dilution mass spectrometry

    International Nuclear Information System (INIS)

    Podmore, I.D.; Cooke, M.S.; Herbert, K.E.; Lunec, J.

    1996-01-01

    In order to understand the role of UV-induced DNA lesions in biological processes such as mutagenesis and carcinogenesis, it is essential to detect and quantify DNA damage in cells. In this paper we present a novel and both highly selective and sensitive assay using capillary gas chromatography (GC) combined with mass spectrometry (MS) for the detection and accurate quantitation of a major product of UV-induced DNA damage (cis-syb cyclobutadithymine). Quantitation of the cyclobutane thymine dimer was achieved by the use of an internal standard in the form of a stable 2 H-labeled analogue. Both isotopically labeled and nonlabeled dimers were prepared directly from their corresponding monomers. Each was identified as their trimethylsilyl ether derivative by GC-MS. Calibration plots were obtained for known quantities of both nonlabeled and analyte and internal standard. Quantitation of cis-syn cyclobutadithymine was demonstrated in DNA exposed to UVC radiation over a dose range of 0 3500 J m -2 . Under the conditions used, the limit of detection was found to be 20-50 fmol on column (equivalent to 0.002-0.005 nmol dimer per mg DNA). The results of the present study indicate that capillary GC-MS is an ideally suited technique for selective and sensitive quantification of cis-syn cyclobutadithymine in DNA and hence UV-induced DNA damage. (author)

  11. Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNA

    Directory of Open Access Journals (Sweden)

    Eric R. Gamache

    2017-04-01

    Full Text Available The genomic RNA of the retrotransposon Ty1 is packaged as a dimer into virus-like particles. The 5′ terminus of Ty1 RNA harbors cis-acting sequences required for translation initiation, packaging and initiation of reverse transcription (TIPIRT. To identify RNA motifs involved in dimerization and packaging, a structural model of the TIPIRT domain in vitro was developed from single-nucleotide resolution RNA structural data. In general agreement with previous models, the first 326 nucleotides of Ty1 RNA form a pseudoknot with a 7-bp stem (S1, a 1-nucleotide interhelical loop and an 8-bp stem (S2 that delineate two long, structured loops. Nucleotide substitutions that disrupt either pseudoknot stem greatly reduced helper-Ty1-mediated retrotransposition of a mini-Ty1, but only mutations in S2 destabilized mini-Ty1 RNA in cis and helper-Ty1 RNA in trans. Nested in different loops of the pseudoknot are two hairpins with complementary 7-nucleotide motifs at their apices. Nucleotide substitutions in either motif also reduced retrotransposition and destabilized mini- and helper-Ty1 RNA. Compensatory mutations that restore base-pairing in the S2 stem or between the hairpins rescued retrotransposition and RNA stability in cis and trans. These data inform a model whereby a Ty1 RNA kissing complex with two intermolecular kissing-loop interactions initiates dimerization and packaging.

  12. Explicit correlation treatment of the potential energy surface of CO{sub 2} dimer

    Energy Technology Data Exchange (ETDEWEB)

    Kalugina, Yulia N., E-mail: kalugina@phys.tsu.ru [Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation); Buryak, Ilya A. [Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow (Russian Federation); Chemistry Department, Lomonosov Moscow State University, Moscow (Russian Federation); Ajili, Yosra [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 Bd Descartes, 77454 Marne-La-Vallée (France); Laboratoire de Spectroscopie Atomique, Moléculaire et Applications - LSAMA Université de Tunis El Manar (Tunisia); Vigasin, Andrei A. [Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow (Russian Federation); Jaidane, Nejm Eddine [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications - LSAMA Université de Tunis El Manar (Tunisia); Hochlaf, Majdi [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 Bd Descartes, 77454 Marne-La-Vallée (France)

    2014-06-21

    We present an extensive study of the four-dimensional potential energy surface (4D-PES) of the carbon dioxide dimer, (CO{sub 2}){sub 2}. This PES is developed over the set of intermolecular coordinates. The electronic computations are carried out at the explicitly correlated coupled cluster method with single, double, and perturbative triple excitations [CCSD(T)-F12] level of theory in connection with the augmented correlation-consistent aug-cc-pVTZ basis set. An analytic representation of the 4D-PES is derived. Our extensive calculations confirm that “Slipped Parallel” is the most stable form and that the T-shaped structure corresponds to a transition state. Later on, this PES is employed for the calculations of the vibrational energy levels of the dimer. Moreover, the temperature dependence of the dimer second virial coefficient and of the first spectral moment of rototranslational collision-induced absorption spectrum is derived. For both quantities, a good agreement is found between our values and the experimental data for a wide range of temperatures. This attests to the high quality of our PES. Generally, our PES and results can be used for modeling CO{sub 2} supercritical fluidity and examination of its role in planetary atmospheres. It can be also incorporated into dynamical computations of CO{sub 2} capture and sequestration. This allows deep understanding, at the microscopic level, of these processes.

  13. Rapid dimerization of quercetin through an oxidative mechanism in the presence of serum albumin decreases its ability to induce cytotoxicity in MDA-MB-231 cells

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Anh; Bortolazzo, Anthony [Department of Biological Sciences, San Jose State University, San Jose, CA 95192-0100 (United States); White, J. Brandon, E-mail: Brandon.White@sjsu.edu [Department of Biological Sciences, San Jose State University, San Jose, CA 95192-0100 (United States)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer Quercetin cannot be detected intracellularly despite killing MDA-MB-231 cells. Black-Right-Pointing-Pointer Quercetin forms a heterodimer through oxidation in media with serum. Black-Right-Pointing-Pointer The quercetin heterodimer does not kill MDA-MB-231 cells. Black-Right-Pointing-Pointer Ascorbic acid stabilizes quercetin increasing cell death in quercetin treated cells. Black-Right-Pointing-Pointer Quercetin, and not a modified form, is responsible for apoptosis and cell death. -- Abstract: Quercetin is a member of the flavonoid family and has been previously shown to have a variety of anti-cancer activities. We and others have reported anti-proliferation, cell cycle arrest, and induction of apoptosis of cancer cells after treatment with quercetin. Quercetin has also been shown to undergo oxidation. However, it is unclear if quercetin or one of its oxidized forms is responsible for cell death. Here we report that quercetin rapidly oxidized in cell culture media to form a dimer. The quercetin dimer is identical to a dimer that is naturally produced by onions. The quercetin dimer and quercetin-3-O-glucopyranoside are unable to cross the cell membrane and do not kill MDA-MB-231 cells. Finally, supplementing the media with ascorbic acid increases quercetin's ability to induce cell death probably by reduction oxidative dimerization. Our results suggest that an unmodified quercetin is the compound that elicits cell death.

  14. Structural basis underlying CAC RNA recognition by the RRM domain of dimeric RNA-binding protein RBPMS

    Energy Technology Data Exchange (ETDEWEB)

    Teplova, Marianna; Farazi, Thalia A.; Tuschl, Thomas; Patel, Dinshaw J.

    2015-09-08

    Abstract

    RNA-binding protein with multiple splicing (designated RBPMS) is a higher vertebrate mRNA-binding protein containing a single RNA recognition motif (RRM). RBPMS has been shown to be involved in mRNA transport, localization and stability, with key roles in axon guidance, smooth muscle plasticity, as well as regulation of cancer cell proliferation and migration. We report on structure-function studies of the RRM domain of RBPMS bound to a CAC-containing single-stranded RNA. These results provide insights into potential topologies of complexes formed by the RBPMS RRM domain and the tandem CAC repeat binding sites as detected by photoactivatable-ribonucleoside-enhanced crosslinking and immunoprecipitation. These studies establish that the RRM domain of RBPMS forms a symmetrical dimer in the free state, with each monomer binding sequence-specifically to all three nucleotides of a CAC segment in the RNA bound state. Structure-guided mutations within the dimerization and RNA-binding interfaces of RBPMS RRM on RNA complex formation resulted in both disruption of dimerization and a decrease in RNA-binding affinity as observed by size exclusion chromatography and isothermal titration calorimetry. As anticipated from biochemical binding studies, over-expression of dimerization or RNA-binding mutants of Flag-HA-tagged RBPMS were no longer able to track with stress granules in HEK293 cells, thereby documenting the deleterious effects of such mutationsin vivo.

  15. Complementation analysis of mutants of 1-aminocyclopropane- 1-carboxylate synthase reveals the enzyme is a dimer with shared active sites.

    Science.gov (United States)

    Tarun, A S; Theologis, A

    1998-05-15

    The pyridoxal phosphate-dependent enzyme 1-aminocyclopropane-1-carboxylate synthase (ACS, EC 4.4.1.14) catalyzes the rate-limiting step in the ethylene biosynthetic pathway. ACS shares the conservation of 11 invariant residues with a family of aminotransferases that includes aspartate aminotransferase. Site-directed mutagenesis on two of these residues, Tyr-92 and Lys-278, in the tomato isoenzyme Le-ACS2 greatly reduces enzymatic activity, indicating their importance in catalysis. These mutants have been used in complementation experiments either in vivo in Escherichia coli or in an in vitro transcription/translation assay to study whether the enzyme functions as a dimer. When the Y92L mutant is coexpressed with the K278A mutant protein, there is partial restoration of enzyme activity, suggesting that the mutant proteins can dimerize and form active heterodimers. Coexpressing a double mutant with the wild-type protein reduces wild-type activity, indicating that inactive heterodimers are formed between the wild-type and the double mutant protein subunits. Furthermore, hybrid complementation shows that another tomato isoenzyme, Le-ACS4, can dimerize and that Le-ACS2 and Le-ACS4 have limited capacity for heterodimerization. The data suggest that ACS functions as a dimer with shared active sites.

  16. Magnetic properties of a classical XY spin dimer in a “planar” magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ciftja, Orion, E-mail: ogciftja@pvamu.edu [Department of Physics, Prairie View A& M University, Prairie View, TX 77446 (United States); Prenga, Dode [Department of Physics, Faculty of Natural Sciences, University of Tirana, Bul. Zog I, Tirana (Albania)

    2016-10-15

    Single-molecule magnetism originates from the strong intra-molecular magnetic coupling of a small number of interacting spins. Such spins generally interact very weakly with the neighboring spins in the other molecules of the compound, therefore, inter-molecular spin couplings are negligible. In certain cases the number of magnetically coupled spins is as small as a dimer, a system that can be considered the smallest nanomagnet capable of storing non-trivial magnetic information on the molecular level. Additional interesting patterns arise if the spin motion is confined to a two-dimensional space. In such a scenario, clusters consisting of spins with large-spin values are particularly attractive since their magnetic interactions can be described well in terms of classical Heisenberg XY spins. In this work we calculate exactly the magnetic properties of a nanomagnetic dimer of classical XY spins in a “planar” external magnetic field. The problem is solved by employing a mathematical approach whose idea is the introduction of auxiliary spin variables into the starting expression of the partition function. Results for the total internal energy, total magnetic moment, spin–spin correlation function and zero-field magnetic susceptibility can serve as a basis to understand the magnetic properties of large-spin dimer building blocks. - Highlights: • Exact magnetic properties of a dimer system of classical XY spins in magnetic field. • Partition function in nonzero magnetic field obtained in closed-form. • Novel exact analytic results are important for spin models in a magnetic field. • Result provides benchmarks to gauge the accuracy of computational techniques.

  17. Crystal Structure of a Dimerized Cockroach Allergen Bla g 2 Complexed with a Monoclonal Antibody

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mi; Gustchina, Alla; Alexandratos, Jerry; Wlodawer, Alexander; Wünschmann, Sabina; Kepley, Christopher L.; Chapman, Martin D.; Pomes, Anna (INDOOR Bio.); (VCU); (NIH)

    2008-09-03

    The crystal structure of a 1:1 complex between the German cockroach allergen Bla g 2 and the Fab' fragment of a monoclonal antibody 7C11 was solved at 2.8-{angstrom} resolution. Bla g 2 binds to the antibody through four loops that include residues 60-70, 83-86, 98-100, and 129-132. Cation-{pi} interactions exist between Lys-65, Arg-83, and Lys-132 in Bla g 2 and several tyrosines in 7C11. In the complex with Fab', Bla g 2 forms a dimer, which is stabilized by a quasi-four-helix bundle comprised of an {alpha}-helix and a helical turn from each allergen monomer, exhibiting a novel dimerization mode for an aspartic protease. A disulfide bridge between C51a and C113, unique to the aspartic protease family, connects the two helical elements within each Bla g 2 monomer, thus facilitating formation of the bundle. Mutation of these cysteines, as well as the residues Asn-52, Gln-110, and Ile-114, involved in hydrophobic interactions within the bundle, resulted in a protein that did not dimerize. The mutant proteins induced less {beta}-hexosaminidase release from mast cells than the wild-type Bla g 2, suggesting a functional role of dimerization in allergenicity. Because 7C11 shares a binding epitope with IgE, the information gained by analysis of the crystal structure of its complex provided guidance for site-directed mutagenesis of the allergen epitope. We have now identified key residues involved in IgE antibody binding; this information will be useful for the design of vaccines for immunotherapy.

  18. Nitrobenzene anti-parallel dimer formation in non-polar solvents

    Directory of Open Access Journals (Sweden)

    Toshiyuki Shikata

    2014-06-01

    Full Text Available We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz, which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime, respectively. The fast mode was simply attributed to the rotational motion of the (monomeric NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz2, due to a strong dipole-dipole interaction between nitro groups.

  19. Woodfordin C, a macro-ring hydrolyzable tannin dimer with antitumor activity, and accompanying dimers from Woodfordia fruticosa flowers.

    Science.gov (United States)

    Yoshida, T; Chou, T; Nitta, A; Miyamoto, K; Koshiura, R; Okuda, T

    1990-05-01

    Three new dimeric hydrolyzable tannins, woodfordins A, B and C, along with seven known hydrolyzable tannins, including oenothein B, a dimer exhibiting marked host-mediated antitumor activity, were isolated from an Indonesian crude drug, Sidowayah [dried flowers of Woodfordia fruticosa (L.) Kurz (Lythraceae)]. The structures of the new tannins were elucidated based on chemical and spectral evidence. Woodfordin C, having a macro-ring structure, was also found to exhibit a significant antitumor activity.

  20. NMR elucidation of monomer-dimer transition and conformational heterogeneity in histone-like DNA binding protein of Helicobacter pylori.

    Science.gov (United States)

    Jaiswal, Nancy; Raikwal, Nisha; Pandey, Himanshu; Agarwal, Nipanshu; Arora, Ashish; Poluri, Krishna Mohan; Kumar, Dinesh

    2017-12-14

    Helicobacter pylori (H. pylori) colonizes under harsh acidic/oxidative stress conditions of human gastrointestinal tract and can survive there for infinitely longer durations of host life. The bacterium expresses several harbinger proteins to facilitate its persistent colonization under such conditions. One such protein in H. pylori is histone-like DNA binding protein (Hup), which in its homo-dimeric form binds to DNA to perform various DNA dependent cellular activities. Further, it also plays an important role in protecting the genomic DNA from oxidative stress and acidic denaturation. Legitimately, if the binding of Hup to DNA is suppressed, it will directly impact on the survival of the bacterium, thus making Hup a potential therapeutic target for developing new anti-H. pylori agents. However, to inhibit the binding of Hup to DNA, it is necessary to gain detailed insights into the molecular and structural basis of Hup-dimerization and its binding mechanism to DNA. As a first step in this direction, we report here the nuclear magnetic resonance (NMR) assignments and structural features of Hup at pH 6.0. The study revealed the occurrence of dynamic equilibrium between its monomer and dimer conformations. The dynamic equilibrium was found to shifting towards dimer both at low temperature and low pH; whereas DNA binding studies evidenced that the protein binds to DNA in its dimeric form. These preliminary investigations correlate very well with the diverse functionality of protein and will form the basis for future studies aiming to develop novel anti-H. pylori agents employing structure-based-rational drug discovery approach. Copyright © 2017 John Wiley & Sons, Ltd.

  1. Crystal Structure of PKG I:cGMP Complex Reveals a cGMP-Mediated Dimeric Interface that Facilitates cGMP-Induced Activation

    KAUST Repository

    Kim, Jeong Joo

    2016-04-09

    Cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) is a key regulator of smooth muscle and vascular tone and represents an important drug target for treating hypertensive diseases and erectile dysfunction. Despite its importance, its activation mechanism is not fully understood. To understand the activation mechanism, we determined a 2.5 Å crystal structure of the PKG I regulatory (R) domain bound with cGMP, which represents the activated state. Although we used a monomeric domain for crystallization, the structure reveals that two R domains form a symmetric dimer where the cGMP bound at high-affinity pockets provide critical dimeric contacts. Small-angle X-ray scattering and mutagenesis support this dimer model, suggesting that the dimer interface modulates kinase activation. Finally, structural comparison with the homologous cyclic AMP-dependent protein kinase reveals that PKG is drastically different from protein kinase A in its active conformation, suggesting a novel activation mechanism for PKG. Kim et al. obtain the first crystal structure of the PKG I R domain bound with cGMP representing its activated state. It reveals a symmetric R dimer where cGMP molecules provide dimeric contacts. This R-R interaction prevents the high-affinity inhibitory interaction between R-C domain and sustains activation. © 2016 Elsevier Ltd.

  2. Structural modeling of the AhR:ARNT complex in the bHLH-PASA-PASB region elucidates the key determinants of dimerization.

    Science.gov (United States)

    Corrada, Dario; Denison, Michael S; Bonati, Laura

    2017-05-02

    Elucidation of the dimerization process of the aryl hydrocarbon receptor (AhR) with the AhR nuclear translocator (ARNT) is crucial for understanding the mechanisms underlying the functional activity of AhR, including mediation of the toxicity of environmental contaminants. In this work, for the first time a structural model of the AhR:ARNT dimer encompassing the entire bHLH-PASA-PASB domain region is proposed. It is developed by using a template-based modeling approach, relying on the recently available crystallographic structures of two dimers of homologous systems in the bHLH-PAS family of proteins: the CLOCK:BMAL1 and the HIF2α:ARNT heterodimers. The structural and energetic characteristics of the modeled AhR:ARNT protein-protein interface are determined by evaluating the variations in solvent accessible surface area, the total binding free energy and the per-residue free energy contributions obtained by the MM-GBSA method and the Energy Decomposition Analysis. The analyses of the intricate network of inter-domain interactions at the dimerization interfaces provide insights into the key determinants of dimerization. These are confirmed by comparison of the computational findings with the available experimental mutagenesis and functional analysis data. The results presented here on the AhR:ARNT dimer structure and interactions provide a framework to start analyzing the mechanism of AhR transformation into its functional DNA binding form.

  3. The specific monomer/dimer equilibrium of the corticotropin-releasing factor receptor type 1 is established in the endoplasmic reticulum.

    Science.gov (United States)

    Teichmann, Anke; Gibert, Arthur; Lampe, André; Grzesik, Paul; Rutz, Claudia; Furkert, Jens; Schmoranzer, Jan; Krause, Gerd; Wiesner, Burkhard; Schülein, Ralf

    2014-08-29

    G protein-coupled receptors (GPCRs) represent the most important drug targets. Although the smallest functional unit of a GPCR is a monomer, it became clear in the past decades that the vast majority of the receptors form dimers. Only v