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  1. Book ; Online ; Thesis: Structural Studies of Variant Surface Glycoproteins on the Trypanosoma Surface

    Hempelmann, Alexander [Verfasser] / Papavasiliou, Nina [Akademischer Betreuer]

    2021  

    Author's details Alexander Hempelmann ; Betreuer: Nina Papavasiliou
    Keywords Naturwissenschaften ; Science
    Subject code sg500
    Language English
    Publisher Universitätsbibliothek Heidelberg
    Publishing place Heidelberg
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

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  2. Article ; Online: Rapid, adaptable and sensitive Cas13-based COVID-19 diagnostics using ADESSO.

    Casati, Beatrice / Verdi, Joseph Peter / Hempelmann, Alexander / Kittel, Maximilian / Klaebisch, Andrea Gutierrez / Meister, Bianca / Welker, Sybille / Asthana, Sonal / Di Giorgio, Salvatore / Boskovic, Pavle / Man, Ka Hou / Schopp, Meike / Ginno, Paul Adrian / Radlwimmer, Bernhard / Stebbins, Charles Erec / Miethke, Thomas / Papavasiliou, Fotini Nina / Pecori, Riccardo

    Nature communications

    2022  Volume 13, Issue 1, Page(s) 3308

    Abstract: During the ongoing COVID-19 pandemic, PCR testing and antigen tests have proven critical for helping to stem the spread of its causative agent, SARS-CoV-2. However, these methods suffer from either general applicability and/or sensitivity. Moreover, the ... ...

    Abstract During the ongoing COVID-19 pandemic, PCR testing and antigen tests have proven critical for helping to stem the spread of its causative agent, SARS-CoV-2. However, these methods suffer from either general applicability and/or sensitivity. Moreover, the emergence of variant strains creates the need for flexibility to correctly and efficiently diagnose the presence of substrains. To address these needs we developed the diagnostic test ADESSO (Accurate Detection of Evolving SARS-CoV-2 through SHERLOCK (Specific High Sensitivity Enzymatic Reporter UnLOCKing) Optimization) which employs Cas13 to diagnose patients in 1 h without sophisticated equipment. Using an extensive panel of clinical samples, we demonstrate that ADESSO correctly identifies infected individuals at a sensitivity and specificity comparable to RT-qPCR on extracted RNA and higher than antigen tests for unextracted samples. Altogether, ADESSO is a fast, sensitive and cheap method that can be applied in a point of care setting to diagnose COVID-19 and can be quickly adjusted to detect new variants.
    MeSH term(s) COVID-19/diagnosis ; COVID-19 Testing ; Humans ; Pandemics ; RNA, Viral/analysis ; RNA, Viral/genetics ; SARS-CoV-2 ; Sensitivity and Specificity
    Chemical Substances RNA, Viral
    Language English
    Publishing date 2022-06-08
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-022-30862-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Nanobody-mediated macromolecular crowding induces membrane fission and remodeling in the African trypanosome.

    Hempelmann, Alexander / Hartleb, Laura / van Straaten, Monique / Hashemi, Hamidreza / Zeelen, Johan P / Bongers, Kevin / Papavasiliou, F Nina / Engstler, Markus / Stebbins, C Erec / Jones, Nicola G

    Cell reports

    2021  Volume 37, Issue 5, Page(s) 109923

    Abstract: The dense variant surface glycoprotein (VSG) coat of African trypanosomes represents the primary host-pathogen interface. Antigenic variation prevents clearing of the pathogen by employing a large repertoire of antigenically distinct VSG genes, thus ... ...

    Abstract The dense variant surface glycoprotein (VSG) coat of African trypanosomes represents the primary host-pathogen interface. Antigenic variation prevents clearing of the pathogen by employing a large repertoire of antigenically distinct VSG genes, thus neutralizing the host's antibody response. To explore the epitope space of VSGs, we generate anti-VSG nanobodies and combine high-resolution structural analysis of VSG-nanobody complexes with binding assays on living cells, revealing that these camelid antibodies bind deeply inside the coat. One nanobody causes rapid loss of cellular motility, possibly due to blockage of VSG mobility on the coat, whose rapid endocytosis and exocytosis are mechanistically linked to Trypanosoma brucei propulsion and whose density is required for survival. Electron microscopy studies demonstrate that this loss of motility is accompanied by rapid formation and shedding of nanovesicles and nanotubes, suggesting that increased protein crowding on the dense membrane can be a driving force for membrane fission in living cells.
    Language English
    Publishing date 2021-11-03
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2649101-1
    ISSN 2211-1247 ; 2211-1247
    ISSN (online) 2211-1247
    ISSN 2211-1247
    DOI 10.1016/j.celrep.2021.109923
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Structure of trypanosome coat protein VSGsur and function in suramin resistance.

    Zeelen, Johan / van Straaten, Monique / Verdi, Joseph / Hempelmann, Alexander / Hashemi, Hamidreza / Perez, Kathryn / Jeffrey, Philip D / Hälg, Silvan / Wiedemar, Natalie / Mäser, Pascal / Papavasiliou, F Nina / Stebbins, C Erec

    Nature microbiology

    2021  Volume 6, Issue 3, Page(s) 392–400

    Abstract: Suramin has been a primary early-stage treatment for African trypanosomiasis for nearly 100 yr. Recent studies revealed that trypanosome strains that express the variant surface glycoprotein (VSG) VSGsur possess heightened resistance to suramin. Here, we ...

    Abstract Suramin has been a primary early-stage treatment for African trypanosomiasis for nearly 100 yr. Recent studies revealed that trypanosome strains that express the variant surface glycoprotein (VSG) VSGsur possess heightened resistance to suramin. Here, we show that VSGsur binds tightly to suramin but other VSGs do not. By solving high-resolution crystal structures of VSGsur and VSG13, we also demonstrate that these VSGs define a structurally divergent subgroup of the coat proteins. The co-crystal structure of VSGsur with suramin reveals that the chemically symmetric drug binds within a large cavity in the VSG homodimer asymmetrically, primarily through contacts of its central benzene rings. Structure-based, loss-of-contact mutations in VSGsur significantly decrease the affinity to suramin and lead to a loss of the resistance phenotype. Altogether, these data show that the resistance phenotype is dependent on the binding of suramin to VSGsur, establishing that the VSG proteins can possess functionality beyond their role in antigenic variation.
    MeSH term(s) Antigenic Variation/drug effects ; Antigenic Variation/immunology ; Binding Sites ; Crystallography, X-Ray ; Drug Resistance/genetics ; Drug Resistance/immunology ; Endocytosis/genetics ; Immune Evasion ; Mutation ; Protein Binding ; Protein Conformation ; Suramin/metabolism ; Suramin/toxicity ; Trypanocidal Agents/metabolism ; Trypanocidal Agents/toxicity ; Trypanosoma brucei rhodesiense/chemistry ; Trypanosoma brucei rhodesiense/drug effects ; Trypanosoma brucei rhodesiense/immunology ; Trypanosoma brucei rhodesiense/metabolism ; Trypanosomiasis, African/parasitology ; Variant Surface Glycoproteins, Trypanosoma/chemistry ; Variant Surface Glycoproteins, Trypanosoma/genetics ; Variant Surface Glycoproteins, Trypanosoma/metabolism
    Chemical Substances Trypanocidal Agents ; VSGsur protein, Trypanosoma brucei rhodesiense ; Variant Surface Glycoproteins, Trypanosoma ; Suramin (6032D45BEM)
    Language English
    Publishing date 2021-01-18
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 2058-5276
    ISSN (online) 2058-5276
    DOI 10.1038/s41564-020-00844-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Book: Near simultaneous X-ray and optical observations of the RS CVn binary SV Cam

    Hempelmann, Alexander

    (Preprint series / Astrophysikalisches Institut Potsdam ; 96,09)

    1996  

    Institution Astrophysikalisches Institut Potsdam
    Author's details Astrophysikalisches Institut Potsdam. A. Hempelmann
    Series title Preprint series / Astrophysikalisches Institut Potsdam ; 96,09
    Language English
    Size 17 S, graph. Darst, 30 cm
    Publisher AIP
    Publishing place Potsdam
    Document type Book
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  6. Article ; Online: Structural Basis of Nanobodies Targeting the Prototype Norovirus.

    Ruoff, Kerstin / Kilic, Turgay / Devant, Jessica / Koromyslova, Anna / Ringel, Alessa / Hempelmann, Alexander / Geiss, Celina / Graf, Juliane / Haas, Michelle / Roggenbach, Imme / Hansman, Grant

    Journal of virology

    2019  Volume 93, Issue 6

    Abstract: Human norovirus infections are a major disease burden. In this study, we analyzed three new norovirus-specific Nanobodies that interacted with the prototype human norovirus (i.e., genogroup I genotype 1 [GI.1]). We showed that the Nanobodies bound on the ...

    Abstract Human norovirus infections are a major disease burden. In this study, we analyzed three new norovirus-specific Nanobodies that interacted with the prototype human norovirus (i.e., genogroup I genotype 1 [GI.1]). We showed that the Nanobodies bound on the side (Nano-7 and Nano-62) and top (Nano-94) of the capsid-protruding (P) domain using X-ray crystallography. Nano-7 and Nano-62 bound at a similar region on the P domain, but the orientations of these two Nanobodies clashed with the shell (S) domain and neighboring P domains on intact particles. This finding suggested that the P domains on the particles should shift in order for Nano-7 and Nano-62 to bind to intact particles. Interestingly, both Nano-7 and Nano-94 were capable of blocking norovirus virus-like particles (VLPs) from binding to histo-blood group antigens (HBGAs), which are important cofactors for norovirus infection. Previously, we showed that the GI.1 HBGA pocket could be blocked with the soluble human milk oligosaccharide 2-fucosyllactose (2'FL). In the current study, we showed that a combined treatment of Nano-7 or Nano-94 with 2'FL enhanced the blocking potential with an additive (Nano-7) or synergistic (Nano-94) effect. We also found that GII Nanobodies with 2'FL also enhanced inhibition. The Nanobody inhibition likely occurred by different mechanisms, including particle aggregation or particle disassembly, whereas 2'FL blocked the HBGA binding site. Overall, these new data showed that the positive effect of the addition of 2'FL was not limited to a single mode of action of Nanobodies or to a single norovirus genogroup.
    MeSH term(s) Binding Sites/immunology ; Blood Group Antigens/immunology ; Caliciviridae Infections/immunology ; Capsid/immunology ; Capsid Proteins/immunology ; Crystallography, X-Ray/methods ; Epitopes/immunology ; Escherichia coli/virology ; Norovirus/immunology ; Protein Binding/immunology ; Single-Domain Antibodies/immunology
    Chemical Substances Blood Group Antigens ; Capsid Proteins ; Epitopes ; Single-Domain Antibodies
    Keywords covid19
    Language English
    Publishing date 2019-03-05
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80174-4
    ISSN 1098-5514 ; 0022-538X
    ISSN (online) 1098-5514
    ISSN 0022-538X
    DOI 10.1128/JVI.02005-18
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 609: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  7. Article: Solar torsional oscillations as due to the magnetic quenching of the Reynolds stress

    Hempelmann, Alexander / Schmitt, J. H. M. M / Stepieǹ, K

    Solar torsional oscillations as due to the magnetic quenching of the Reynolds stress, Küker, Manfred. - Potsdam : Astrophysikalisches Inst.

    1995  

    Document type Article
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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