618 results on '"Andreas Hofmann"'
Search Results
2. Small molecule induced STING degradation facilitated by the HECT ligase HERC4
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Merve Mutlu, Isabel Schmidt, Andrew I. Morrison, Benedikt Goretzki, Felix Freuler, Damien Begue, Oliver Simic, Nicolas Pythoud, Erik Ahrne, Sandra Kapps, Susan Roest, Debora Bonenfant, Delphine Jeanpierre, Thi-Thanh-Thao Tran, Rob Maher, Shaojian An, Amandine Rietsch, Florian Nigsch, Andreas Hofmann, John Reece-Hoyes, Christian N. Parker, and Danilo Guerini
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Science - Abstract
Abstract Stimulator of interferon genes (STING) is a central component of the cytosolic nucleic acids sensing pathway and as such master regulator of the type I interferon response. Due to its critical role in physiology and its’ involvement in a variety of diseases, STING has been a focus for drug discovery. Targeted protein degradation (TPD) has emerged as a promising pharmacology for targeting previously considered undruggable proteins by hijacking the cellular ubiquitin proteasome system (UPS) with small molecules. Here, we identify AK59 as a STING degrader leveraging HERC4, a HECT-domain E3 ligase. Additionally, our data reveals that AK59 is effective on the common pathological STING mutations, suggesting a potential clinical application of this mechanism. Thus, these findings introduce HERC4 to the fields of TPD and of compound-induced degradation of STING, suggesting potential therapeutic applications.
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- 2024
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3. DCAF1-based PROTACs with activity against clinically validated targets overcoming intrinsic- and acquired-degrader resistance
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Martin Schröder, Martin Renatus, Xiaoyou Liang, Fabian Meili, Thomas Zoller, Sandrine Ferrand, Francois Gauter, Xiaoyan Li, Frederic Sigoillot, Scott Gleim, Therese-Marie Stachyra, Jason R. Thomas, Damien Begue, Maryam Khoshouei, Peggy Lefeuvre, Rita Andraos-Rey, BoYee Chung, Renate Ma, Benika Pinch, Andreas Hofmann, Markus Schirle, Niko Schmiedeberg, Patricia Imbach, Delphine Gorses, Keith Calkins, Beatrice Bauer-Probst, Magdalena Maschlej, Matt Niederst, Rob Maher, Martin Henault, John Alford, Erik Ahrne, Luca Tordella, Greg Hollingworth, Nicolas H. Thomä, Anna Vulpetti, Thomas Radimerski, Philipp Holzer, Seth Carbonneau, and Claudio R. Thoma
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Science - Abstract
Abstract Targeted protein degradation (TPD) mediates protein level through small molecule induced redirection of E3 ligases to ubiquitinate neo-substrates and mark them for proteasomal degradation. TPD has recently emerged as a key modality in drug discovery. So far only a few ligases have been utilized for TPD. Interestingly, the workhorse ligase CRBN has been observed to be downregulated in settings of resistance to immunomodulatory inhibitory drugs (IMiDs). Here we show that the essential E3 ligase receptor DCAF1 can be harnessed for TPD utilizing a selective, non-covalent DCAF1 binder. We confirm that this binder can be functionalized into an efficient DCAF1-BRD9 PROTAC. Chemical and genetic rescue experiments validate specific degradation via the CRL4DCAF1 E3 ligase. Additionally, a dasatinib-based DCAF1 PROTAC successfully degrades cytosolic and membrane-bound tyrosine kinases. A potent and selective DCAF1-BTK-PROTAC (DBt-10) degrades BTK in cells with acquired resistance to CRBN-BTK-PROTACs while the DCAF1-BRD9 PROTAC (DBr-1) provides an alternative strategy to tackle intrinsic resistance to VHL-degrader, highlighting DCAF1-PROTACS as a promising strategy to overcome ligase mediated resistance in clinical settings.
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- 2024
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4. Structure-activity relationship and target investigation of 2-aryl quinolines with nematocidal activity
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Harrison T. Shanley, Aya C. Taki, Nghi Nguyen, Tao Wang, Joseph J. Byrne, Ching-Seng Ang, Michael G. Leeming, Shuai Nie, Nicholas Williamson, Yuanting Zheng, Neil D. Young, Pasi K. Korhonen, Andreas Hofmann, Bill C.H. Chang, Tim N.C. Wells, Cécile Häberli, Jennifer Keiser, Abdul Jabbar, Brad E. Sleebs, and Robin B. Gasser
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Anthelmintics ,Drug discovery ,Haemonchus contortus ,Target identification ,Thermal proteome profiling ,In silico docking ,Infectious and parasitic diseases ,RC109-216 - Abstract
Within the context of our anthelmintic discovery program, we recently identified and evaluated a quinoline derivative, called ABX464 or obefazimod, as a nematocidal candidate; synthesised a series of analogues which were assessed for activity against the free-living nematode Caenorhabditis elegans; and predicted compound-target relationships by thermal proteome profiling (TPP) and in silico docking. Here, we logically extended this work and critically evaluated the anthelmintic activity of ABX464 analogues on Haemonchus contortus (barber's pole worm) – a highly pathogenic nematode of ruminant livestock. First, we tested a series of 44 analogues on H. contortus (larvae and adults) to investigate the nematocidal pharmacophore of ABX464, and identified one compound with greater potency than the parent compound and showed moderate activity against a select number of other parasitic nematodes (including Ancylostoma, Heligmosomoides and Strongyloides species). Using TPP and in silico modelling studies, we predicted protein HCON_00074590 (a predicted aldo-keto reductase) as a target candidate for ABX464 in H. contortus. Future work aims to optimise this compound as a nematocidal candidate and investigate its pharmacokinetic properties. Overall, this study presents a first step toward the development of a new nematocide.
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- 2024
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5. The environmentally-regulated interplay between local three-dimensional chromatin organisation and transcription of proVWX in E. coli
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Fatema-Zahra M. Rashid, Frédéric G. E. Crémazy, Andreas Hofmann, David Forrest, David C. Grainger, Dieter W. Heermann, and Remus T. Dame
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Science - Abstract
Abstract Nucleoid associated proteins (NAPs) maintain the architecture of bacterial chromosomes and regulate gene expression. Thus, their role as transcription factors may involve three-dimensional chromosome re-organisation. While this model is supported by in vitro studies, direct in vivo evidence is lacking. Here, we use RT-qPCR and 3C-qPCR to study the transcriptional and architectural profiles of the H-NS (histone-like nucleoid structuring protein)-regulated, osmoresponsive proVWX operon of Escherichia coli at different osmolarities and provide in vivo evidence for transcription regulation by NAP-mediated chromosome re-modelling in bacteria. By consolidating our in vivo investigations with earlier in vitro and in silico studies that provide mechanistic details of how H-NS re-models DNA in response to osmolarity, we report that activation of proVWX in response to a hyperosmotic shock involves the destabilization of H-NS-mediated bridges anchored between the proVWX downstream and upstream regulatory elements (DRE and URE), and between the DRE and ygaY that lies immediately downstream of proVWX. The re-establishment of these bridges upon adaptation to hyperosmolarity represses the operon. Our results also reveal additional structural features associated with changes in proVWX transcript levels such as the decompaction of local chromatin upstream of the operon, highlighting that further complexity underlies the regulation of this model operon. H-NS and H-NS-like proteins are wide-spread amongst bacteria, suggesting that chromosome re-modelling may be a typical feature of transcriptional control in bacteria.
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- 2023
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6. Holistic Framework for the Implementation and Validation of PBF-LB/M with Risk Management for Individual Products through Predictive Process Stability
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Hajo Groneberg, Sven Oberdiek, Carolin Schulz, Andreas Hofmann, Alexander Schloske, and Frank Doepper
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additive manufacturing ,AM ,laser beam melting ,laser powder bed fusion ,PBF-LB/M ,risk management ,Production capacity. Manufacturing capacity ,T58.7-58.8 - Abstract
The additive manufacturing technology powder bed fusion of metal with a laser beam (PBF-LB/M) is industrially established for tool-free production of complex and individualized components and products. While the in-processing is based on a layer-by-layer build-up of material, both upstream and downstream process steps (pre-processing and post-processing) are necessary for demand-oriented production. However, there are increasing concerns in the industry about the efficient and economical implementation and validation of the PBF-LB/M. Individual products for mass personalization pose a particular challenge, as they are subject to sophisticated risk management, especially in highly regulated sectors such as medical technology. Additive manufacturing using PBF-LB/M is a suitable technology but a complex one to master in this environment. A structured system for holistic decision-making concerning technical and economic feasibility, as well as quality and risk-oriented process management, is currently not available. In the context of this research, a framework is proposed that demonstrates the essential steps for the systematic implementation and validation of PBF-LB/M in two structured phases. The intention is to make process-related key performance indicators such as part accuracy, surface finish, mechanical properties, and production efficiency controllable and ensure reliable product manufacturing. The framework is then visualized and evaluated using a practice-oriented case study environment.
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- 2024
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7. Fundamental Understanding and Quantification of Capacity Losses Involving the Negative Electrode in Sodium‐Ion Batteries
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Le Anh Ma, Alexander Buckel, Andreas Hofmann, Leif Nyholm, and Reza Younesi
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ageing ,electrolytes ,sodium‐ion batteries ,solid electrolyte interphase ,Science - Abstract
Abstract Knowledge about capacity losses related to the solid electrolyte interphase (SEI) in sodium‐ion batteries (SIBs) is still limited. One major challenge in SIBs is that the solubility of SEI species in liquid electrolytes is comparatively higher than the corresponding species formed in Li‐ion batteries. This study sheds new light on the associated capacity losses due to initial SEI formation, SEI dissolution and subsequent SEI reformation, charge leakage via SEI and subsequent SEI growth, and diffusion‐controlled sodium trapping in electrode particles. By using a variety of electrochemical cycling protocols, synchrotron‐based X‐ray photoelectron spectroscopy (XPS), gas chromatography coupled with mass spectrometry (GC‐MS), and proton nuclear magnetic resonance (1H‐NMR) spectroscopy, capacity losses due to changes in the SEI layer during different open circuit pause times are investigated in nine different electrolyte solutions. It is shown that the amount of capacity lost depends on the interplay between the electrolyte chemistry and the thickness and stability of the SEI layer. The highest capacity loss is measured in NaPF6 in ethylene carboante mixed with diethylene carbonate electrolyte (i.e., 5 µAh h−1/2pause or 2.78 mAh g·h−1/2pause) while the lowest value is found in NaTFSI in ethylene carbonate mixed with dimethoxyethance electrolyte (i.e., 1.3 µAh h−1/2pause or 0.72 mAh g·h−1/2pause).
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- 2024
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8. Electrical Smoothing of the Powder Bed Surface in Laser-Based Powder Bed Fusion of Metals
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Andreas Hofmann, Tim Grotz, Nico Köstler, Alexander Mahr, and Frank Döpper
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additive manufacturing ,powder bed fusion ,powder bed surface quality ,powder bed leveling ,electrical smoothing ,Production capacity. Manufacturing capacity ,T58.7-58.8 - Abstract
Achieving a homogeneous and uniform powder bed surface as well as a defined, uniform layer thickness is crucial for achieving reproducible component properties that meet requirements when powder bed fusion of metals with a laser beam. The existing recoating processes cause wear of the recoater blade due to protruded, melted obstacles, which affects the powder bed surface quality locally. Impairments to the powder bed surface quality have a negative effect on the resulting component properties such as surface quality and relative density. This can lead either to scrapped components or to additional work steps such as surface reworking. In this work, an electric smoother is presented with which a wear-free and contactless smoothing of the powder bed can be realized. The achievable powder bed surface quality was analyzed using optical profilometry. It was found that the electric smoother can compensate for impairments in the powder bed surface and achieve a reproducible surface quality of the powder bed regardless of the initial extent of the impairments. Consequently, the electric smoother offers a promising opportunity to reduce the scrap rate in PBF-LB/M and to increase component quality.
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- 2024
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9. 3D Printed Hemispherically Radiating Antenna for Broadband Millimeter Wave Applications
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Lukas Engel, Danti Khouri, Konstantin Lomakin, Andreas Hofmann, Micha Kleinlein, Ingrid Ullmann, Martin Vossiek, and Gerald Gold
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broadband ,coverage ,hemispherical ,localization ,millimeter wave ,radar applications ,Telecommunication ,TK5101-6720 - Abstract
Nowadays, additive manufacturing provides far-reaching possibilities for use in radio frequency components. In addition to almost unlimited freedom of design as compared to conventional manufacturing, the absence of further assembly steps is a key aspect of 3D printing. In this paper, a 3D printed monolithic antenna for millimeter wave-sensing applications is presented with a full hemispherical coverage. The antenna is designed as an ensemble of a waveguide horn antenna and a differentially fed dipole antenna. The slotted waveguide approach was utilized to improve the manufacturing quality on the waveguide inside. The influence of two optimized antenna elements, a metal plane, and a cut-out window, on the beam pattern is comprehensively investigated. A huge half power beam width of 142° in both directions, elevation and azimuth, is presented at 79 GHz and a boresight gain of 4.7 dBi was measured. The beam pattern in the frequency range from 76 to 81 GHz is studied in greater detail, where a half power beam width of at least 112° is achieved. Due to the −10 dB matching capability bandwidth of over 28 GHz, the antenna is also suitable for extremely broadband applications with a −5 dB angular width of better than 100°. Furthermore, the system design describes how to integrate the antenna into hybrid circuit designs and the manufacturing tolerances are examined. The antenna offers attractive possibilities for millimeter wave-sensing applications in the area of assisted living and industrial monitoring, especially whenever blind spots have to be avoided.
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- 2023
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10. Cycling Stability of Lithium‐Ion Batteries Based on Fe–Ti‐Doped LiNi0.5Mn1.5O4 Cathodes, Graphite Anodes, and the Cathode‐Additive Li3PO4
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Pirmin Stüble, Marcus Müller, Thomas Bergfeldt, Joachim R. Binder, and Andreas Hofmann
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additive ,full cells ,LiNi0.5Mn1.5O4 ,lithium phosphate ,LNMO ,Science - Abstract
Abstract This study addresses the improved cycling stability of Li‐ion batteries based on Fe–Ti‐doped LiNi0.5Mn1.5O4 (LNMO) high‐voltage cathode active material and graphite anodes. By using 1 wt% Li3PO4 as cathode additive, over 90% capacity retention for 1000 charge–discharge cycles and remaining capacities of 109 mAh g−1 are reached in a cell with an areal capacity of 2.3 mAh cm−2 (potential range: 3.5–4.9 V). Cells without the additive, in contrast, suffer from accelerated capacity loss and increase polarization, resulting in capacity retention of only 78% over 1000 cycles. An electrolyte consisting of ethylene carbonate, dimethyl carbonate, and LiPF6 is used without additional additives. The significantly improved cycling stability of the full cells is mainly due to two factors, namely, the low MnIII content of the Fe–Ti‐doped LNMO active material and the use of the cathode‐additive Li3PO4. Crystalline Li3PO4 yields a drastic reduction of transition metal deposition on the graphite anode and prevents Li loss and the propagation of cell polarization. Li3PO4 is added to the cathode slurry that makes it a very simple and scalable process, first reported herein. The positive effects of crystalline Li3PO4 as electrode additive, however, should apply to other cell chemistries as well.
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- 2023
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11. Chromosome-scale Echinococcus granulosus (genotype G1) genome reveals the Eg95 gene family and conservation of the EG95-vaccine molecule
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Pasi K. Korhonen, Liina Kinkar, Neil D. Young, Huimin Cai, Marshall W. Lightowlers, Charles Gauci, Abdul Jabbar, Bill C. H. Chang, Tao Wang, Andreas Hofmann, Anson V. Koehler, Junhua Li, Jiandong Li, Daxi Wang, Jiefang Yin, Huanming Yang, David J. Jenkins, Urmas Saarma, Teivi Laurimäe, Mohammad Rostami-Nejad, Malik Irshadullah, Hossein Mirhendi, Mitra Sharbatkhori, Francisco Ponce-Gordo, Sami Simsek, Adriano Casulli, Houria Zait, Hripsime Atoyan, Mario Luiz de la Rue, Thomas Romig, Marion Wassermann, Sargis A. Aghayan, Hasmik Gevorgyan, Bicheng Yang, and Robin B. Gasser
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Biology (General) ,QH301-705.5 - Abstract
A high-quality genome for the parasitic tapeworm, Echinococcus granulosus, provides further insight into the EG95 vaccine target for cystic echinococcosis.
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- 2022
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12. Deciphering Electrolyte Degradation in Sodium-Based Batteries: The Role of Conductive Salt Source, Additives, and Storage Condition
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Mahir Hashimov and Andreas Hofmann
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sodium-based batteries ,electrolyte degradation ,GC-MS analysis ,Production of electric energy or power. Powerplants. Central stations ,TK1001-1841 ,Industrial electrochemistry ,TP250-261 - Abstract
This work investigates the stability of electrolyte systems used in sodium-ion-based batteries. The electrolytes consist of a 1:1 (v:v) mixture of ethylene carbonate (EC) and propylene carbonate (PC), a sodium-conducting salt (either NaPF6 or NaTFSI), and fluoroethylene carbonate (FEC), respectively, sodium difluoro(oxalato) borate (NaDFOB), as additives. Through systematic evaluation using gas chromatography coupled with mass spectrometry (GC-MS), we analyze the formation of degradation products under different conditions including variations in temperature, vial material, and the presence or absence of sodium metal. Our results reveal the significant influence of the conductive salt’s source on degradation. Furthermore, we observe that FEC’s stability is affected by the storage temperature, vial material, and presence of sodium metal, suggesting its active involvement in the degradation process. Additionally, our results highlight the role of NaDFOB as an additive in mitigating degradation. The study provides crucial insights into the complex network of degradation reactions occurring within the electrolyte, thus informing strategies for improved electrolyte systems in sodium-based batteries. Since the production, material selection and storage of electrolytes are often insufficiently described, we provide here an insight into the different behavior of electrolytes for Na-ion batteries.
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- 2023
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13. Telomerase subunit Est2 marks internal sites that are prone to accumulate DNA damage
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Satyaprakash Pandey, Mona Hajikazemi, Theresa Zacheja, Stephanie Schalbetter, Jonathan Baxter, Victor Guryev, Andreas Hofmann, Dieter W. Heermann, Stefan A. Juranek, and Katrin Paeschke
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DNA damage ,Genome stability ,Telomerase ,Yeast ,Biology (General) ,QH301-705.5 - Abstract
Abstract Background The main function of telomerase is at the telomeres but under adverse conditions telomerase can bind to internal regions causing deleterious effects as observed in cancer cells. Results By mapping the global occupancy of the catalytic subunit of telomerase (Est2) in the budding yeast Saccharomyces cerevisiae, we reveal that it binds to multiple guanine-rich genomic loci, which we termed “non-telomeric binding sites” (NTBS). We characterize Est2 binding to NTBS. Contrary to telomeres, Est2 binds to NTBS in G1 and G2 phase independently of Est1 and Est3. The absence of Est1 and Est3 renders telomerase inactive at NTBS. However, upon global DNA damage, Est1 and Est3 join Est2 at NTBS and telomere addition can be observed indicating that Est2 occupancy marks NTBS regions as particular risks for genome stability. Conclusions Our results provide a novel model of telomerase regulation in the cell cycle using internal regions as “parking spots” of Est2 but marking them as hotspots for telomere addition.
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- 2021
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14. Thermal proteome profiling reveals Haemonchus orphan protein HCO_011565 as a target of the nematocidal small molecule UMW-868
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Aya C. Taki, Tao Wang, Nghi N. Nguyen, Ching-Seng Ang, Michael G. Leeming, Shuai Nie, Joseph J. Byrne, Neil D. Young, Yuanting Zheng, Guangxu Ma, Pasi K. Korhonen, Anson V. Koehler, Nicholas A. Williamson, Andreas Hofmann, Bill C. H. Chang, Cécile Häberli, Jennifer Keiser, Abdul Jabbar, Brad E. Sleebs, and Robin B. Gasser
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thermal proteome profiling ,anthelmintic discovery ,target identification ,structure modelling ,in silico docking ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Parasitic roundworms (nematodes) cause destructive diseases, and immense suffering in humans and other animals around the world. The control of these parasites relies heavily on anthelmintic therapy, but treatment failures and resistance to these drugs are widespread. As efforts to develop vaccines against parasitic nematodes have been largely unsuccessful, there is an increased focus on discovering new anthelmintic entities to combat drug resistant worms. Here, we employed thermal proteome profiling (TPP) to explore hit pharmacology and to support optimisation of a hit compound (UMW-868), identified in a high-throughput whole-worm, phenotypic screen. Using advanced structural prediction and docking tools, we inferred an entirely novel, parasite-specific target (HCO_011565) of this anthelmintic small molecule in the highly pathogenic, blood-feeding barber’s pole worm, and in other socioeconomically important parasitic nematodes. The “hit-to-target” workflow constructed here provides a unique prospect of accelerating the simultaneous discovery of novel anthelmintics and associated parasite-specific targets.
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- 2022
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15. Biophotonic sensors with integrated Si3N4-organic hybrid (SiNOH) lasers for point-of-care diagnostics
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Daria Kohler, Gregor Schindler, Lothar Hahn, Johannes Milvich, Andreas Hofmann, Kerstin Länge, Wolfgang Freude, and Christian Koos
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Applied optics. Photonics ,TA1501-1820 ,Optics. Light ,QC350-467 - Abstract
Optical biosensors: light source integration Optical sensors that comprise integrated lasers and that are compatible with cost-efficient mass manufacturing could be promising for point-of-care diagnostics. Daria Kohler and coworkers at Karlsruhe Institute of Technology (KIT) and Robert Bosch GmbH in Germany have now demonstrated biosensors that combine silicon-nitride (Si3N4) waveguides with co-integrated Si3N4-organic hybrid (SiNOH) lasers. The sensor consists of three main integrated parts: The optically-pumped SiNOH laser, a Mach-Zehnder interferometer acting as a biosensor, and a set of grating couplers for directing the output to a CCD camera. The SiNOH laser relies on a spiral Si3N4 waveguide, which is covered by a dye-doped organic cladding to provide optical gain. The devices are technically simple and can be efficiently realized by wafer-level printing techniques.
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- 2021
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16. Quasi-Coherent Phase-Based Localization and Tracking of Incoherently Transmitting Radio Beacons
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Erik Sippel, Markus Hehn, Tobias Koegel, Patrick Groschel, Andreas Hofmann, Stefan Bruckner, Johanna Geiss, Robert Schober, and Martin Vossiek
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Radar ,Kalman filters ,incoherent measurements ,localization ,array signal processing ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The direct measurement of distance-dependent information between wireless units represents a challenge for wireless locating systems, because it requires the exact time synchronization of separate wireless units. To avoid these synchronization efforts, many wireless locating systems only evaluate phase difference of arrival (PDOA) measurements. While simple PDOA localization techniques rely on multiangulation, advanced PDOA concepts like the holographic extended Kalman filter (HEKF) directly evaluate the measured phases without non-linear preprocessing. However, these differential phase measurement approaches are less sensitive than systems that can measure absolute phase variations, which allow the tracking of much smaller position changes than the signal’s carrier wavelength. This paper proposes to extend the HEKF by the evaluation of absolute phases in an incoherent measurement setup, which consists of a continuous wave (CW) beacon and several receivers. The developed quasi-coherent holographic extended Kalman filter (QCHEKF) uses the overdetermined PDOA measurements to estimate the phase–frequency relation between each beacon–receiver pair. Then, the established phase–frequency relations allow the evaluation of absolute phase measurements and, thus, the accurate localization and tracking of a simple, unsynchronized, narrowband CW beacon, even under severe multipath conditions. This novel concept is experimentally validated via 3D localization results in a challenging indoor scenario using a 24 GHz CW measurement setup. Here, the QCHEKF improves the achieved localization accuracy in comparison to the HEKF by 35 % from 0.78 cm to 0.51 cm, while the maximum deviation from the trajectory reduces by 68 % from 5 cm to 1.6 cm. Furthermore, the QCHEKF enables the exact tracking of fast changes in direction, which is usually a significant challenge for standard wireless target tracking systems.
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- 2021
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17. Dataset of propylene carbonate based liquid electrolyte mixtures for sodium-ion cells
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Andreas Hofmann, Zhengqi Wang, Sebastian Pinto Bautista, Marcel Weil, Freya Müller, Robert Löwe, Luca Schneider, Ijaz Ul Mohsin, and Thomas Hanemann
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Density data ,Viscosity data ,Conductivity data ,Gas chromatography dataset ,Life cycle analysis (LCA) data ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Science (General) ,Q1-390 - Abstract
In this manuscript, we present rheology, ionic conductivity, density, chromatography, and life cycle analysis data on the PC+X electrolyte system with and without LiClO4. In particular, the data are presented in contact with Na surfaces. In this case, photographic images of electrolyte-sodium mixtures are also shown. The data was analyzed using OriginPro software to visualize it in an appropriate manner. In our view, the data serve as comparative values, form a basis of a chromatography analysis and are also valuable for modeling. The analysis of the data is presented in the manuscript “Comprehensive characterization of propylene carbonate based liquid electrolyte mixtures for sodium-ion cells” [1].
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- 2022
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18. Effect of Flame Retardants and Electrolyte Variations on Li-Ion Batteries
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Natalia Fulik, Andreas Hofmann, Dorit Nötzel, Marcus Müller, Ingo Reuter, Freya Müller, Anna Smith, and Thomas Hanemann
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lithium-ion battery ,flame retardant ,gas release ,anode ,electrolyte ,Production of electric energy or power. Powerplants. Central stations ,TK1001-1841 ,Industrial electrochemistry ,TP250-261 - Abstract
Lithium-ion batteries are being increasingly used and deployed commercially. Cell-level improvements that address flammability characteristics and thermal runaway are currently being intensively tested and explored. In this study, three additives—namely, lithium oxalate, sodium fumarate and sodium malonate—which exhibit fire-retardant properties are investigated with respect to their incorporation into graphite anodes and their electro/chemical interactions within the anode and the cell material studied. It has been shown that flame-retardant concentrations of up to approximately 20 wt.% within the anode coating do not cause significant capacity degradation but can provide a flame-retardant effect due to their inherent, fire-retardant release of CO2 gas. The flame-retardant-containing layers exhibit good adhesion to the current collector. Their suitability in lithium-ion cells was tested in pouch cells and, when compared to pure graphite anodes, showed almost no deterioration regarding cell capacity when used in moderate (≤20 wt.%) concentrations.
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- 2023
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19. Domain Organization of the UBX Domain Containing Protein 9 and Analysis of Its Interactions With the Homohexameric AAA + ATPase p97 (Valosin-Containing Protein)
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Jana Riehl, Ramesh Rijal, Leonie Nitz, Christoph S. Clemen, Andreas Hofmann, and Ludwig Eichinger
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p97/VCP/CDC48/TER/VAT ATPase ,UBX domain containing protein 9 (UBXD9 ,TUG ,ASPL ,PUX1) ,IBMPFD (Inclusion Body Myopathy associated with Paget disease of bone and Fronto temporal Dementia) ,Biology (General) ,QH301-705.5 - Abstract
The abundant homohexameric AAA + ATPase p97 (also known as valosin-containing protein, VCP) is highly conserved from Dictyostelium discoideum to human and a pivotal factor of cellular protein homeostasis as it catalyzes the unfolding of proteins. Owing to its fundamental function in protein quality control pathways, it is regulated by more than 30 cofactors, including the UBXD protein family, whose members all carry an Ubiquitin Regulatory X (UBX) domain that enables binding to p97. One member of this latter protein family is the largely uncharacterized UBX domain containing protein 9 (UBXD9). Here, we analyzed protein-protein interactions of D. discoideum UBXD9 with p97 using a series of N- and C-terminal truncation constructs and probed the UBXD9 interactome in D. discoideum. Pull-down assays revealed that the UBX domain (amino acids 384–466) is necessary and sufficient for p97 interactions and that the N-terminal extension of the UBX domain, which folds into a β0-α–1-α0 lariat structure, is required for the dissociation of p97 hexamers. Functionally, this finding is reflected by strongly reduced ATPase activity of p97 upon addition of full length UBXD9 or UBXD9261–573. Results from Blue Native PAGE as well as structural model prediction suggest that hexamers of UBXD9 or UBXD9261–573 interact with p97 hexamers and disrupt the p97 subunit interactions via insertion of a helical lariat structure, presumably by destabilizing the p97 D1:D1’ intermolecular interface. We thus propose that UBXD9 regulates p97 activity in vivo by shifting the quaternary structure equilibrium from hexamers to monomers. Using three independent approaches, we further identified novel interaction partners of UBXD9, including glutamine synthetase type III as well as several actin-binding proteins. These findings suggest a role of UBXD9 in the organization of the actin cytoskeleton, and are in line with the hypothesized oligomerization-dependent mechanism of p97 regulation.
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- 2021
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20. Assessment of the structural and functional diversities of plant microbiota: Achievements and challenges – A review
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Anton Hartmann, Doreen Fischer, Linda Kinzel, Soumitra Paul Chowdhury, Andreas Hofmann, Jose Ivo Baldani, and Michael Rothballer
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Medicine (General) ,R5-920 ,Science (General) ,Q1-390 - Abstract
Analyses of the spatial localization and the functions of bacteria in host plant habitats through in situ identification by immunological and molecular genetic techniques combined with high resolving microscopic tools and 3D-image analysis contributed substantially to a better understanding of the functional interplay of the microbiota in plants. Among the molecular genetic methods, 16S-rRNA genes were of central importance to reconstruct the phylogeny of newly isolated bacteria and to localize them in situ. However, they usually do not allow resolution for phylogenetic affiliations below genus level. Especially, the separation of opportunistic human pathogens from plant beneficial strains, currently allocated to the same species, needs genome-based resolving techniques. Whole bacterial genome sequences allow to discriminate phylogenetically closely related strains. In addition, complete genome sequences enable strain-specific monitoring for biotechnologically relevant strains. In this mini-review we present high resolving approaches for analysis of the composition and key functions of plant microbiota, focusing on interactions of diazotrophic plant growth promoting bacteria, like Azospirillum brasilense, with non-legume host plants. Combining high resolving microscopic analyses with specific immunological detection methods and molecular genetic tools, including especially transcriptome analyses of both the bacterial and plant partners, enables new insights into key traits of beneficial bacteria-plant interactions in holobiontic systems. Keywords: Holobiont, Diazotrophic plant beneficial bacteria, Azospirillum, Opportunistic human pathogens, Metagenome and transcriptome analyses, N-acyl-homoserine lactones
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- 2019
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21. DRfit: a Java tool for the analysis of discrete data from multi-well plate assays
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Andreas Hofmann, Sarah Preston, Megan Cross, H. M. P. Dilrukshi Herath, Anne Simon, and Robin B. Gasser
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Biochemical assays ,Data analysis ,Dose-response experiments ,Drug discovery ,Enzyme assays ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Biology (General) ,QH301-705.5 - Abstract
Abstract Background Analyses of replicates in sets of discrete data, typically acquired in multi-well plate formats, is a recurring task in many contemporary areas in the Life Sciences. The availability of accessible cross-platform data analysis tools for such fundamental tasks in varied projects and environments is an important prerequisite to ensuring a reliable and timely turnaround as well as to provide practical analytical tools for student training. Results We have developed an easy-to-use, interactive software tool for the analysis of multiple data sets comprising replicates of discrete bivariate data points. For each dataset, the software identifies the replicate data points from a defined matrix layout and calculates their means and standard errors. The averaged values are then automatically fitted using either a linear or a logistic dose response function. Conclusions DRfit is a practical and convenient tool for the analysis of one or multiple sets of discrete data points acquired as replicates from multi-well plate assays. The design of the graphical user interface and the built-in analysis features make it a flexible and useful tool for a wide range of different assays.
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- 2019
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22. Tetrahydroquinoxalines induce a lethal evisceration phenotype in Haemonchus contortus in vitro
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Yaqing Jiao, Sarah Preston, Jose F. Garcia-Bustos, Jonathan B. Baell, Sabatino Ventura, Thuy Le, Nicole McNamara, Nghi Nguyen, Antony Botteon, Cameron Skinner, Jill Danne, Sarah Ellis, Anson V. Koehler, Tao Wang, Bill C.H. Chang, Andreas Hofmann, Abdul Jabbar, and Robin B. Gasser
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Infectious and parasitic diseases ,RC109-216 - Abstract
In the present study, the anthelmintic activity of a human tyrosine kinase inhibitor, AG-1295, and 14 related tetrahydroquinoxaline analogues against Haemonchus contortus was explored. These compounds were screened against parasitic larvae - exsheathed third-stage (xL3) and fourth-stage (L4) - using a whole-organism screening assay. All compounds were shown to have inhibitory effects on larval motility, development and growth, and induced evisceration through the excretory pore in xL3s. The estimated IC50 values ranged from 3.5 to 52.0 μM for inhibition of larval motility or development. Cytotoxicity IC50 against human MCF10A cells was generally higher than 50 μM. Microscopic studies revealed that this eviscerated (Evi) phenotype occurs rapidly (
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- 2019
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23. Selected α-pyrones from the plants Cryptocarya novoguineensis (Lauraceae) and Piper methysticum (Piperaceae) with activity against Haemonchus contortus in vitro
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H.M.P. Dilrukshi Herath, Sarah Preston, Abdul Jabbar, Jose Garcia-Bustos, Russell S. Addison, Sasha Hayes, Topul Rali, Tao Wang, Anson V. Koehler, Bill C.H. Chang, Andreas Hofmann, Rohan A. Davis, and Robin B. Gasser
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Infectious and parasitic diseases ,RC109-216 - Abstract
Due to the widespread occurrence and spread of anthelmintic resistance, there is a need to develop new drugs against resistant parasitic nematodes of livestock animals. The Nobel Prize-winning discovery and development of the anti-parasitic drugs avermectin and artemisinin has renewed the interest in exploring natural products as anthelmintics. In the present study, we screened 7500 plant extracts for in vitro-activity against the barber's pole worm, Haemonchus contortus, a highly significant pathogen of ruminants. The anthelmintic extracts from two plants, Cryptocarya novoguineensis and Piper methysticum, were fractionated by high-performance liquid chromatography (HPLC). Subsequently, compounds were purified from fractions with significant biological activity. Four α-pyrones, namely goniothalamin (GNT), dihydrokavain (DHK), desmethoxyyangonin (DMY) and yangonin (YGN), were purified from fractions from the two plants, GNT from C. novoguineensis, and DHK, DMY and YGN (= kavalactones) from P. methysticum. The three kavalactones induced a lethal, eviscerated (Evi) phenotype in treated exsheathed third-stage larvae (xL3s), and DMY and YGN had moderate potencies (IC50 values of 31.7 ± 0.23 μM and 23.7 ± 2.05 μM, respectively) at inhibiting the development of xL3s to fourth-stage larvae (L4s). Although GNT had limited potency (IC50 of 200–300 μM) at inhibiting L4 development, it was the only compound that reduced L4 motility (IC50 of 6.25–12.50 μM). The compounds purified from each plant affected H. contortus in an irreversible manner. These findings suggest that structure-activity relationship studies of α-pyrones should be pursued to assess their potential as anthelmintics. Keywords: Haemonchus contortus, Anthelmintic, Natural products, Cryptocarya novoguineensis, Piper methysticum, α-pyrones
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- 2019
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24. Comparative bioinformatic analysis suggests that specific dauer-like signalling pathway components regulate Toxocara canis development and migration in the mammalian host
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Guangxu Ma, Tao Wang, Pasi K. Korhonen, Shuai Nie, Gavin E. Reid, Andreas J. Stroehlein, Anson V. Koehler, Bill C. H. Chang, Andreas Hofmann, Neil D. Young, and Robin B. Gasser
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Toxocara canis ,Ascaris suum ,Dauer signalling pathway ,Dafachronic acid ,Arrested development ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Toxocara canis is quite closely related to Ascaris suum but its biology is more complex, involving a phase of arrested development (diapause or hypobiosis) in tissues as well as transplacental and transmammary transmission routes. In the present study, we explored and compared dauer-like signalling pathways of T. canis and A. suum to infer which components in these pathways might associate with, or regulate, this added complexity in T. canis. Methods Guided by information for Caenorhabditis elegans, we bioinformatically inferred and compared components of dauer-like signalling pathways in T. canis and A. suum using genomic and transcriptomic data sets. In these two ascaridoids, we also explored endogenous dafachronic acids (DAs), which are known to be critical in regulating larval developmental processes in C. elegans and other nematodes, by liquid chromatography-mass spectrometry (LC-MS). Results Orthologues of C. elegans dauer signalling genes were identified in T. canis (n = 55) and A. suum (n = 51), inferring the presence of a dauer-like signalling pathway in both species. Comparisons showed clear differences between C. elegans and these ascaridoids as well as between T. canis and A. suum, particularly in the transforming growth factor-β (TGF-β) and insulin-like signalling pathways. Specifically, in both A. suum and T. canis, there was a paucity of genes encoding SMAD transcription factor-related protein (daf-3, daf-5, daf-8 and daf-14) and insulin/insulin-like peptide (daf-28, ins-4, ins-6 and ins-7) homologues, suggesting an evolution and adaptation of the signalling pathway in these parasites. In T. canis, there were more orthologues coding for homologues of antagonist insulin-like peptides (Tc-ins-1 and Tc-ins-18), an insulin receptor substrate (Tc-ist-1) and a serine/threonine kinase (Tc-akt-1) than in A. suum, suggesting potentiated functional roles for these molecules in regulating larval diapause and reactivation. A relatively conserved machinery was proposed for DA synthesis in the two ascaridoids, and endogenous Δ4- and Δ7-DAs were detected in them by LC-MS analysis. Differential transcription analysis between T. canis and A. suum suggests that ins-17 and ins-18 homologues are specifically involved in regulating development and migration in T. canis larvae in host tissues. Conclusion The findings of this study provide a basis for functional explorations of insulin-like peptides, signalling hormones (i.e. DAs) and related nuclear receptors, proposed to link to development and/or parasite-host interactions in T. canis. Elucidating the functional roles of these molecules might contribute to the discovery of novel anthelmintic targets in ascaridoids.
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- 2019
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25. Novel Phosphonium-Based Ionic Liquid Electrolytes for Battery Applications
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Andreas Hofmann, Daniel Rauber, Tzu-Ming Wang, Rolf Hempelmann, Christopher W. M. Kay, and Thomas Hanemann
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ionic liquid ,phosphonium ,electrochemistry ,batteries ,Organic chemistry ,QD241-441 - Abstract
In this study, we address the fundamental question of the physicochemical and electrochemical properties of phosphonium-based ionic liquids containing the counter-ions bis(trifluoromethanesulfonyl)imide ([TFSI]−) and bis(fluorosulfonyl)imide ([FSI]−). To clarify these structure–property as well as structure–activity relationships, trimethyl-based alkyl- and ether-containing phosphonium ILs were systematically synthesized, and their properties, namely density, flow characteristics, alkali metal compatibility, oxidative stability, aluminum corrosivity as well as their use in Li-ion cells were examined comprehensively. The variable moiety on the phosphonium cation exhibited a chain length of four and five, respectively. The properties were discussed as a function of the side chain, counter-ion and salt addition ([Li][TFSI] or [Li][FSI]). High stability coupled with good flow characteristics were found for the phosphonium IL [P1114][TFSI] and the mixture [P1114][TFSI] + [Li][TFSI], respectively.
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- 2022
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26. Arylpyrrole and fipronil analogues that inhibit the motility and/or development of Haemonchus contortus in vitro
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H.M.P. Dilrukshi Herath, Hongjian Song, Sarah Preston, Abdul Jabbar, Tao Wang, Sean L. McGee, Andreas Hofmann, Jose Garcia-Bustos, Bill C.H. Chang, Anson V. Koehler, Yuxiu Liu, Qiaoqiao Ma, Pengxiang Zhang, Qiqi Zhao, Qingmin Wang, and Robin B. Gasser
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Infectious and parasitic diseases ,RC109-216 - Abstract
Due to widespread drug resistance in parasitic nematodes, there is a need to develop new anthelmintics. Given the cost and time involved in developing a new drug, the repurposing of known chemicals can be a promising, alternative approach. In this context, we tested a library (n = 600) of natural product-inspired pesticide analogues against exsheathed third stage-larvae (xL3s) of Haemonchus contortus (barber's pole worm) using a whole-organism, phenotypic screening technique that measures the inhibition of motility and development in treated larvae. In the primary screen, we identified 32 active analogues derived from chemical scaffolds of arylpyrrole or fipronil. The seven most promising compounds, selected based on their anthelmintic activity and/or limited cytotoxicity, are arylpyrroles that reduced the motility of fourth-stage larvae (L4s) with significant potency (IC50 values ranged from 0.04 ± 0.01 μM to 4.25 ± 0.82 μM, and selectivity indices ranged from 10.6 to 412.5). Since the parent structures of the active compounds are uncouplers of oxidative phosphorylation, we tested the effect of selected analogues on oxygen consumption in xL3s using the Seahorse XF24 flux analyser. Larvae treated with the test compounds showed a significant increase in oxygen consumption compared with the untreated control, demonstrating their uncoupling activity. Overall, the results of the present study have identified natural product-derived molecules that are worth considering for chemical optimisation as anthelmintic drug leads. Keywords: Arylpyrrole, Fipronil, Haemonchus contortus, Anthelmintic, Drug discovery
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- 2018
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27. A Helminth-Derived Chitinase Structurally Similar to Mammalian Chitinase Displays Immunomodulatory Properties in Inflammatory Lung Disease
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Friederike Ebner, Katja Lindner, Katharina Janek, Agathe Niewienda, Piotr H. Malecki, Manfred S. Weiss, Tara E. Sutherland, Arnd Heuser, Anja A. Kühl, Jürgen Zentek, Andreas Hofmann, and Susanne Hartmann
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Immunologic diseases. Allergy ,RC581-607 - Abstract
Immunomodulation of airway hyperreactivity by excretory-secretory (ES) products of the first larval stage (L1) of the gastrointestinal nematode Trichuris suis is reported by us and others. Here, we aimed to identify the proteins accounting for the modulatory effects of the T. suis L1 ES proteins and studied six selected T. suis L1 proteins for their immunomodulatory efficacy in a murine OVA-induced allergic airway disease model. In particular, an enzymatically active T. suis chitinase mediated amelioration of clinical signs of airway hyperreactivity, primarily associated with suppression of eosinophil recruitment into the lung, the associated chemokines, and increased numbers of RELMα+ interstitial lung macrophages. While there is no indication of T. suis chitinase directly interfering with dendritic cell activation or antigen presentation to CD4 T cells, treatment of allergic mice with the worm chitinase influenced the hosts’ own chitinase activity in the inflamed lung. The three-dimensional structure of the T. suis chitinase as determined by high-resolution X-ray crystallography revealed high similarities to mouse acidic mammalian chitinase (AMCase) but a unique ability of T. suis chitinase to form dimers. Our data indicate that the structural similarities between the parasite and host chitinase contribute to the disease-ameliorating effect of the helminth-derived chitinase on allergic lung inflammation.
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- 2021
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28. Single Molecule Localization Microscopy Analyses of DNA-Repair Foci and Clusters Detected Along Particle Damage Tracks
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Michael Hausmann, Charlotte Neitzel, Elizaveta Bobkova, David Nagel, Andreas Hofmann, Tatyana Chramko, Elena Smirnova, Olga Kopečná, Eva Pagáčová, Alla Boreyko, Evgeny Krasavin, Iva Falkova, Dieter W. Heermann, Götz Pilarczyk, Georg Hildenbrand, Felix Bestvater, and Martin Falk
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heavy ion irradiation ,single molecule localization microscopy ,Ripley distance frequency analysis ,topological analysis ,persistent homologies ,ionizing radiation-induced foci ,Physics ,QC1-999 - Abstract
High-LET (Linear Energy Transfer) particle irradiation as being provided from heavy ion accelerator facilities has an increasing impact on bio-medical research and cancer treatment. Nevertheless, there are a lot of open questions concerning the understanding of damaging mechanisms and repair processes within the light of radio-sensitivity and thus, individualized medical applications. The three-dimensional architecture of genomes on the meso- and nano-scale acts in combination with epigenetic gene activation as an important player of gene regulation and fundamental biological processes such as DNA damage response and repair. So far only little is known about the impact of high-LET particles on the chromatin architecture along the passing track when they are “lumbering” through the cell nucleus. How does a cell nucleus manage such complex damages and re-organize the chromatin toward functionally intact units? Is there a radio-sensitivity related difference in this reaction? Here, we present some approaches to investigate spatial and topological parameters of chromatin to glimpse some aspects related to these questions. Two cell lines, a radio-resistant glioblastoma and a radio-sensitive fibroblast cell line, were used and irradiated by 15N-ions in 90° and 10° radiation beam geometry. Nano-probing of particle induced damage sites along particle tracks, and the recruited DNA repair proteins (as presented here for 53BP1 and Rad51) in combination with super-resolution Single Molecule Localization Microscopy (SMLM) are powerful methods for geometric and topological analyses to study particle related mechanisms of chromatin conformation and repair complexes in single cells. We used variable tools for such investigations based on image free high precision SMLM, nano-scaled molecule distribution analyses, appropriate metrics following Ripley’s distance frequencies and cluster formation analyses, as well as topological quantifications employing persistence homology. The data reveal a cell type specific nano-architecture of DNA damage foci along particle tracks and their dynamic molecular re-arrangements during repair. Comparing the topology of repair foci by persistence homology suggests similarities of repair cluster formation along given particle tracks. Our studies contribute to the molecular understanding of cellular radiation response at sub-light microscopic chromatin levels; thereby showing how chromatin architecture around complex damage sites and repair foci nano-architecture may contribute to ongoing repair processing. The methodological approach presented here may give a basis for improved biological dosimetry or radiotherapies in the future.
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- 2020
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29. Author Correction to: Telomerase subunit Est2 marks internal sites that are prone to accumulate DNA damage
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Satyaprakash Pandey, Mona Hajikazemi, Theresa Zacheja, Stephanie Schalbetter, Matthew J. Neale, Jonathan Baxter, Victor Guryev, Andreas Hofmann, Dieter W. Heermann, Stefan A. Juranek, and Katrin Paeschke
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Biology (General) ,QH301-705.5 - Abstract
An amendment to this paper has been published and can be accessed via the original article.
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- 2022
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30. Poly(ionic liquid) Based Composite Electrolytes for Lithium Ion Batteries
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Robert Löwe, Thomas Hanemann, Tatiana Zinkevich, and Andreas Hofmann
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lithium ion batteries ,polymerizable ionic liquids ,poly(ionic liquid)s ,composite polymer electrolytes ,ionogel electrolyte ,lithium diffusion ,Organic chemistry ,QD241-441 - Abstract
Polymerized ionic liquids (PIL) are an interesting substance class, which is discussed to transfer the outstanding properties and tunability of ionic liquids into a solid material. In this study we extend our previous research on ammonium based PIL and discuss the influence of additives and their usability as polymer electrolyte membranes for lithium ion batteries. The polymer electrolyte is thereby used as replacement for the commercially widespread system of a separator that is soaked with liquid electrolyte. The influence of the material composition on the ionic conductivity (via electrochemical impedance spectroscopy) and the diffusion coefficients (via pulsed-field-gradient nuclear magnetic resonance spectroscopy) were studied and cell tests with adapted membrane materials were performed. High amounts of the additional ionic liquid (IL) MPPyrr-TFSI (1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide) increased the ionic conductivity of the materials up to 1.3·10−4 S·cm−1 but made the usage of a cross-linker necessary to obtain mechanically stable membranes. The application of liquid electrolyte mixtures with ethylene carbonate (EC) and MPPyrr-TFSI decreased ionic conductivity values down to the 10−9 S·cm−1 range, but increased 7Li diffusion coefficients with increasing amounts of EC up to 1.7·10−10 m2·s−1. Cell tests with two membrane mixtures proofed that it is possible to build electrolyte membranes on basis of the polymerized ionic liquids, but also showed that further research is necessary to ensure stable and efficient cell cycling.
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- 2021
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31. Additive Manufactured Waveguide for E-Band Using Ceramic Materials
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Florian Hubert, Tobias Bader, Larissa Wahl, Andreas Hofmann, Konstantin Lomakin, Mark Sippel, Nahum Travitzky, and Gerald Gold
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printing ,additive manufacturing (AM) ,ceramics ,rectangular waveguides ,rapid prototyping ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Ceramic materials are chemical- and temperature-resistant and, therefore, enable novel application fields ranging from automotive to aerospace. With this in mind, this contribution focuses on developing an additive manufacturing approach for 3D-printed waveguides made of ceramic materials. In particular, a special design approach for ceramic waveguides, which introduces non-radiating slots into the waveguides sidewalls, and a customized metallization process, are presented. The developed process allows for using conventional stereolithographic desktop-grade 3D-printers. The proposed approach has, therefore, benefits such as low-cost fabrication, moderate handling effort and independence of the concrete waveguide geometry. The performance of a manufactured ceramic WR12 waveguide is compared to a commercial waveguide and a conventionally printed counterpart. For that reason, relevant properties, such as surface roughness and waveguide geometry, are characterized. Parsing the electrical measurements, the ceramic waveguide specimen features an attenuation coefficient of 30–60 dB/m within the E-Band. The measured attenuation coefficient is 200% and 300% higher compared to the epoxy resin and the commercial waveguide and is attributed to the increased surface roughness of the ceramic substrate.
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- 2021
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32. Dysidenin from the Marine Sponge Citronia sp. Affects the Motility and Morphology of Haemonchus contortus Larvae In Vitro
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Kelsey S. Ramage, Aya C. Taki, Kah Yean Lum, Sasha Hayes, Joseph J. Byrne, Tao Wang, Andreas Hofmann, Merrick G. Ekins, Jonathan M. White, Abdul Jabbar, Rohan A. Davis, and Robin B. Gasser
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Haemonchus contortus ,parasitic nematode ,nematocidal ,marine natural products ,NatureBank ,biodiscovery ,Biology (General) ,QH301-705.5 - Abstract
High-throughput screening of the NatureBank marine extract library (n = 7616) using a phenotypic assay for the parasitic nematode Haemonchus contortus identified an active extract derived from the Australian marine sponge Citronia sp. Bioassay-guided fractionation of the CH2Cl2/MeOH extract from Citronia sp. resulted in the purification of two known hexachlorinated peptides, dysidenin (1) and dysideathiazole (2). Compound 1 inhibited the growth/development of H. contortus larvae and induced multiple phenotypic changes, including a lethal evisceration (Evi) phenotype and/or somatic cell and tissue destruction. This is the first report of anthelmintic activity for these rare and unique polychlorinated peptides.
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- 2021
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33. Screening of the ‘Open Scaffolds’ collection from Compounds Australia identifies a new chemical entity with anthelmintic activities against different developmental stages of the barber's pole worm and other parasitic nematodes
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Sarah Preston, Yaqing Jiao, Jonathan B. Baell, Jennifer Keiser, Simon Crawford, Anson V. Koehler, Tao Wang, Moana M. Simpson, Ray M. Kaplan, Karla J. Cowley, Kaylene J. Simpson, Andreas Hofmann, Abdul Jabbar, and Robin B. Gasser
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Infectious and parasitic diseases ,RC109-216 - Abstract
The discovery and development of novel anthelmintic classes is essential to sustain the control of socioeconomically important parasitic worms of humans and animals. With the aim of offering novel, lead-like scaffolds for drug discovery, Compounds Australia released the ‘Open Scaffolds’ collection containing 33,999 compounds, with extensive information available on the physicochemical properties of these chemicals. In the present study, we screened 14,464 prioritised compounds from the ‘Open Scaffolds’ collection against the exsheathed third-stage larvae (xL3s) of Haemonchus contortus using recently developed whole-organism screening assays. We identified a hit compound, called SN00797439, which was shown to reproducibly reduce xL3 motility by ≥ 70%; this compound induced a characteristic, “coiled” xL3 phenotype (IC50 = 3.46–5.93 μM), inhibited motility of fourth-stage larvae (L4s; IC50 = 0.31–12.5 μM) and caused considerable cuticular damage to L4s in vitro. When tested on other parasitic nematodes in vitro, SN00797439 was shown to inhibit (IC50 = 3–50 μM) adults of Ancylostoma ceylanicum (hookworm) and first-stage larvae of Trichuris muris (whipworm) and eventually kill (>90%) these stages. Furthermore, this compound completely inhibited the motility of female and male adults of Brugia malayi (50–100 μM) as well as microfilariae of both B. malayi and Dirofilaria immitis (heartworm). Overall, these results show that SN00797439 acts against genetically (evolutionarily) distant parasitic nematodes i.e. H. contortus and A. ceylanicum [strongyloids] vs. B. malayi and D. immitis [filarioids] vs. T. muris [enoplid], and, thus, might offer a novel, lead-like scaffold for the development of a relatively broad-spectrum anthelmintic. Our future work will focus on assessing the activity of SN00797439 against other pathogens that cause neglected tropical diseases, optimising analogs with improved biological activities and characterising their targets. Keywords: ‘Open Scaffolds’ compound collection, Whole organism screening, Haemonchus, Nematodes, Anthelmintic
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- 2017
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34. High Throughput Screening of the NatureBank ‘Marine Collection’ in a Haemonchus Bioassay Identifies Anthelmintic Activity in Extracts from a Range of Sponges from Australian Waters
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Aya C. Taki, Joseph J. Byrne, Abdul Jabbar, Kah Yean Lum, Sasha Hayes, Russell S. Addison, Kelsey S. Ramage, Andreas Hofmann, Merrick G. Ekins, Tao Wang, Bill C. H. Chang, Rohan A. Davis, and Robin B. Gasser
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high throughput screening ,Haemonchus contortus ,parasitic nematode ,anthelmintic ,marine natural products ,sponge ,Organic chemistry ,QD241-441 - Abstract
Widespread resistance in parasitic nematodes to most classes of anthelmintic drugs demands the discovery and development of novel compounds with distinct mechanisms of action to complement strategic or integrated parasite control programs. Products from nature—which assume a diverse ‘chemical space’—have significant potential as a source of anthelmintic compounds. In the present study, we screened a collection of extracts (n = 7616) derived from marine invertebrates sampled from Australian waters in a high throughput bioassay for in vitro anti-parasitic activity against the barber’s pole worm (Haemonchus contortus)—an economically important parasitic nematode of livestock animals. In this high throughput screen (HTS), we identified 58 active extracts that reduced larval motility by ≥70% (at 90 h), equating to an overall ‘hit rate’ of ~0.8%. Of these 58 extracts, 16 also inhibited larval development by ≥80% (at 168 h) and/or induced ‘non-wild-type’ (abnormal) larval phenotypes with reference to ‘wild-type’ (normal) larvae not exposed to extract (negative controls). Most active extracts (54 of 58) originated from sponges, three from chordates (tunicates) and one from a coral; these extracts represented 37 distinct species/taxa of 23 families. An analysis of samples by 1H NMR fingerprinting was utilised to dereplicate hits and to prioritise a set of 29 sponge samples for future chemical investigation. Overall, these results indicate that a range of sponge species from Australian waters represents a rich source of natural compounds with nematocidal or nematostatic properties. Our plan now is to focus on in-depth chemical investigations of the sample set prioritised herein.
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- 2021
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35. Structure-Property Relation of Trimethyl Ammonium Ionic Liquids for Battery Applications
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Daniel Rauber, Andreas Hofmann, Frederik Philippi, Christopher W. M. Kay, Tatiana Zinkevich, Thomas Hanemann, and Rolf Hempelmann
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ionic liquids ,ammonium ,batteries ,electrolytes− ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Ionic liquids are attractive and safe electrolytes for diverse electrochemical applications such as advanced rechargeable batteries with high energy densities. Their properties that are beneficial for energy storage and conversion include negligible vapor-pressure, intrinsic conductivity as well as high stability. To explore the suitability of a series of ionic liquids with small ammonium cations for potential battery applications, we investigated their thermal and transport properties. We studied the influence of the symmetrical imide-type anions bis(trifluoromethanesulfonyl)imide ([TFSI]−) and bis(fluorosulfonyl)imide ([FSI]−), side chain length and functionalization, as well as lithium salt content on the properties of the electrolytes. Many of the samples are liquid at ambient temperature, but their solidification temperatures show disparate behavior. The transport properties showed clear trends: the dynamics are accelerated for samples with the [FSI]− anion, shorter side chains, ether functionalization and lower amounts of lithium salts. Detailed insight was obtained from the diffusion coefficients of the different ions in the electrolytes, which revealed the formation of aggregates of lithium cations coordinated by anions. The ionic liquid electrolytes exhibit sufficient stability in NMC/Li half-cells at elevated temperatures with small current rates without the need of additional liquid electrolytes, although Li-plating was observed. Electrolytes containing [TFSI]− anions showed superior stability compared to those with [FSI]− anions in battery tests.
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- 2021
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36. Enzyme characteristics of pathogen-specific trehalose-6-phosphate phosphatases
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Megan Cross, Siji Rajan, Janine Chekaiban, Jake Saunders, Chloe Hamilton, Jeong-Sun Kim, Mark J. Coster, Robin B. Gasser, and Andreas Hofmann
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Medicine ,Science - Abstract
Abstract Owing to the key role of trehalose in pathogenic organisms, there has recently been growing interest in trehalose metabolism for therapeutic purposes. Trehalose-6-phosphate phosphatase (TPP) is a pivotal enzyme in the most prominent biosynthesis pathway (OtsAB). Here, we compare the enzyme characteristics of recombinant TPPs from five important nematode and bacterial pathogens, including three novel members of this protein family. Analysis of the kinetics of trehalose-6-phosphate hydrolysis reveals that all five enzymes display a burst-like kinetic behaviour which is characterised by a decrease of the enzymatic rate after the pre-steady state. The observed super-stoichiometric burst amplitudes can be explained by multiple global conformational changes in members of this enzyme family during substrate processing. In the search for specific TPP inhibitors, the trapping of the complex conformational transitions in TPPs during the catalytic cycle may present a worthwhile strategy to explore.
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- 2017
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37. Assessing the anthelmintic activity of pyrazole-5-carboxamide derivatives against Haemonchus contortus
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Yaqing Jiao, Sarah Preston, Hongjian Song, Abdul Jabbar, Yuxiu Liu, Jonathan Baell, Andreas Hofmann, Dana Hutchinson, Tao Wang, Anson V. Koehler, Gillian M. Fisher, Katherine T. Andrews, Benoît Laleu, Michael J. Palmer, Jeremy N. Burrows, Timothy N. C. Wells, Qingmin Wang, and Robin B. Gasser
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Haemonchus contortus ,Phenotypic screening ,Tolfenpyrad ,Synthetic pyrazole-5-carboxamide derivatives ,Mitochondrial respiratory chain ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background In this study, we tested five series of pyrazole-5-carboxamide compounds (n = 55) for activity against parasitic stages of the nematode Haemonchus contortus (barber’s pole worm), one of the most pathogenic parasites of ruminants. Methods In an optimised, whole-organism screening assay, using exsheathed third-stage (xL3) and fourth-stage (L4) larvae, we measured the inhibition of larval motility and development of H. contortus. Results Amongst the 55 compounds, we identified two compounds (designated a-15 and a-17) that reproducibly inhibit xL3 motility as well as L4 motility and development, with IC50 values ranging between ~3.4 and 55.6 μM. We studied the effect of these two ‘hit’ compounds on mitochondrial function by measuring oxygen consumption. This assessment showed that xL3s exposed to each of these compounds consumed significantly less oxygen and had less mitochondrial activity than untreated xL3s, which was consistent with specific inhibition of complex I of the respiratory electron transport chain in arthropods. Conclusions The present findings provide a sound basis for future work, aimed at identifying the targets of compounds a-15 and a-17 and establishing the modes of action of these chemicals in H. contortus.
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- 2017
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38. Self-organised segregation of bacterial chromosomal origins
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Andreas Hofmann, Jarno Mäkelä, David J Sherratt, Dieter Heermann, and Seán M Murray
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self-organisation ,SMC ,chromosome organisation ,Turing patterning ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
The chromosomal replication origin region (ori) of characterised bacteria is dynamically positioned throughout the cell cycle. In slowly growing Escherichia coli, ori is maintained at mid-cell from birth until its replication, after which newly replicated sister oris move to opposite quarter positions. Here, we provide an explanation for ori positioning based on the self-organisation of the Structural Maintenance of Chromosomes complex, MukBEF, which forms dynamically positioned clusters on the chromosome. We propose that a non-trivial feedback between the self-organising gradient of MukBEF complexes and the oris leads to accurate ori positioning. We find excellent agreement with quantitative experimental measurements and confirm key predictions. Specifically, we show that oris exhibit biased motion towards MukBEF clusters, rather than mid-cell. Our findings suggest that MukBEF and oris act together as a self-organising system in chromosome organisation-segregation and introduces protein self-organisation as an important consideration for future studies of chromosome dynamics.
- Published
- 2019
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39. Experimental dataset on electrolyte mixtures containing fluoroethylene carbonate and lithium bis(trifluoromethanesulfonyl)imide
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Zhengqi Wang, Andreas Hofmann, and Thomas Hanemann
- Subjects
Computer applications to medicine. Medical informatics ,R858-859.7 ,Science (General) ,Q1-390 - Abstract
These data and analyses support the research article “Low-flammable electrolytes with fluoroethylene carbonate based solvent mixtures and lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) for lithium-ion batteries” [1]. The data and analyses presented here include fitted data for density measurements, temperature dependence of density and specific volume of the mixtures, detailed viscosity measurements and conductivity data, current density plots with respect to anodic aluminum dissolution, half-cell C-rate capability of mixtures with the additives used in research article as well as the SEM images and EDX data of the full-cell with the electrolyte selected and controlled.
- Published
- 2019
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40. Structure–Property Relationship of Polymerized Ionic Liquids for Solid-State Electrolyte Membranes
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Robert Löwe, Thomas Hanemann, Tatiana Zinkevich, and Andreas Hofmann
- Subjects
polymerizable ionic liquids ,ionogel ,structure–property relationship ,ionic conductivity ,ionic liquids ,lithium-ion battery ,Organic chemistry ,QD241-441 - Abstract
Eight new polymerized ammonium-based ionic liquids were prepared as thin membrane films and evaluated within the scope of their usage in lithium-ion batteries. The focus of this work is to get a better understanding of the influence of structural modifications of the monomers on the polymerized materials. Further, different concentrations of a lithium-ion conducting salt were applied in order to receive an optimized combination of monomer structure and lithium salt concentration. It was found that an increased side chain length of the studied ammonium-based polymerized ionic liquids leads to a reduction in glass transition temperatures and increased ionic conductivity values. As a result of the addition of conducting salt to the PIL membranes, the glass transition temperatures and the ionic conductivity values decreases. Nevertheless, PFG-NMR reveals a higher lithium-ion mobility for a sample with higher conducting salt content.
- Published
- 2021
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41. Elucidation of the Clustered Nano-Architecture of Radiation-Induced DNA Damage Sites and Surrounding Chromatin in Cancer Cells: A Single Molecule Localization Microscopy Approach
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Michael Hausmann, Martin Falk, Charlotte Neitzel, Andreas Hofmann, Abin Biswas, Theresa Gier, Iva Falkova, Dieter W. Heermann, and Georg Hildenbrand
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topology of DNA double strand breaks ,nano-architecture ,ionizing radiation-induced foci (IRIF) ,chromatin rearrangements after irradiation ,single molecule localization microscopy (SMLM) ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
In cancer therapy, the application of (fractionated) harsh radiation treatment is state of the art for many types of tumors. However, ionizing radiation is a “double-edged sword”—it can kill the tumor but can also promote the selection of radioresistant tumor cell clones or even initiate carcinogenesis in the normal irradiated tissue. Individualized radiotherapy would reduce these risks and boost the treatment, but its development requires a deep understanding of DNA damage and repair processes and the corresponding control mechanisms. DNA double strand breaks (DSBs) and their repair play a critical role in the cellular response to radiation. In previous years, it has become apparent that, beyond genetic and epigenetic determinants, the structural aspects of damaged chromatin (i.e., not only of DSBs themselves but also of the whole damage-surrounding chromatin domains) form another layer of complex DSB regulation. In the present article, we summarize the application of super-resolution single molecule localization microscopy (SMLM) for investigations of these structural aspects with emphasis on the relationship between the nano-architecture of radiation-induced repair foci (IRIFs), represented here by γH2AX foci, and their chromatin environment. Using irradiated HeLa cell cultures as an example, we show repair-dependent rearrangements of damaged chromatin and analyze the architecture of γH2AX repair clusters according to topological similarities. Although HeLa cells are known to have highly aberrant genomes, the topological similarity of γH2AX was high, indicating a functional, presumptively genome type-independent relevance of structural aspects in DSB repair. Remarkably, nano-scaled chromatin rearrangements during repair depended both on the chromatin domain type and the treatment. Based on these results, we demonstrate how the nano-architecture and topology of IRIFs and chromatin can be determined, point to the methodological relevance of SMLM, and discuss the consequences of the observed phenomena for the DSB repair network regulation or, for instance, radiation treatment outcomes.
- Published
- 2021
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42. Phylogenomic and biogeographic reconstruction of the Trichinella complex
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Pasi K. Korhonen, Edoardo Pozio, Giuseppe La Rosa, Bill C. H. Chang, Anson V. Koehler, Eric P. Hoberg, Peter R. Boag, Patrick Tan, Aaron R. Jex, Andreas Hofmann, Paul W. Sternberg, Neil D. Young, and Robin B. Gasser
- Subjects
Science - Abstract
Trichinellosis is a globally important food-borne disease caused by roundworms of the Trichinella complex. Here the authors present genomic sequences representing all 12 recognized Trichinellaspecies and genotypes, and reconstruct their phylogeny and biogeography.
- Published
- 2016
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43. The Haemonchus contortus kinome - a resource for fundamental molecular investigations and drug discovery
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Andreas J. Stroehlein, Neil D. Young, Pasi K. Korhonen, Abdul Jabbar, Andreas Hofmann, Paul W. Sternberg, and Robin B. Gasser
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Haemonchus contortus ,Protein kinases ,Kinome ,Caenorhabditis elegans ,Bioinformatics ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Protein kinases regulate a plethora of essential signalling and other biological pathways in all eukaryotic organisms, but very little is known about them in most parasitic nematodes. Methods Here, we defined, for the first time, the entire complement of protein kinases (kinome) encoded in the barber’s pole worm (Haemonchus contortus) through an integrated analysis of transcriptomic and genomic datasets using an advanced bioinformatic workflow. Results We identified, curated and classified 432 kinases representing ten groups, 103 distinct families and 98 subfamilies. A comparison of the kinomes of H. contortus and Caenorhabditis elegans (a related, free-living nematode) revealed considerable variation in the numbers of casein kinases, tyrosine kinases and Ca2+/calmodulin-dependent protein kinases, which likely relate to differences in biology, habitat and life cycle between these worms. Moreover, a suite of kinase genes was selectively transcribed in particular developmental stages of H. contortus, indicating central roles in developmental and reproductive processes. In addition, using a ranking system, drug targets (n = 13) and associated small-molecule effectors (n = 1517) were inferred. Conclusions The H. contortus kinome will provide a useful resource for fundamental investigations of kinases and signalling pathways in this nematode, and should assist future anthelmintic discovery efforts; this is particularly important, given current drug resistance problems in parasitic nematodes.
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- 2015
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44. Natural Compounds from the Marine Brown Alga Caulocystis cephalornithos with Potent In Vitro-Activity against the Parasitic Nematode Haemonchus contortus
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Aya C. Taki, Robert Brkljača, Tao Wang, Anson V. Koehler, Guangxu Ma, Jill Danne, Sarah Ellis, Andreas Hofmann, Bill C. H. Chang, Abdul Jabbar, Sylvia Urban, and Robin B. Gasser
- Subjects
algae ,Caulocystis cephalornithos ,natural compound ,anthelmintic ,in vitro-activity ,Haemonchus contortus ,Medicine - Abstract
Eight secondary metabolites (1 to 8) were isolated from a marine sponge, a marine alga and three terrestrial plants collected in Australia and subsequently chemically characterised. Here, these natural product-derived compounds were screened for in vitro-anthelmintic activity against the larvae and adult stages of Haemonchus contortus (barber’s pole worm)—a highly pathogenic parasitic nematode of ruminants. Using an optimised, whole-organism screening system, compounds were tested on exsheathed third-stage larvae (xL3s) and fourth-stage larvae (L4s). Anthelmintic activity was initially evaluated on these stages based on the inhibition of motility, development and/or changes in morphology (phenotype). We identified two compounds, 6-undecylsalicylic acid (3) and 6-tridecylsalicylic acid (4) isolated from the marine brown alga, Caulocystis cephalornithos, with inhibitory effects on xL3 and L4 motility and larval development, and the induction of a “skinny-straight” phenotype. Subsequent testing showed that these two compounds had an acute nematocidal effect (within 1–12 h) on adult males and females of H. contortus. Ultrastructural analysis of adult worms treated with compound 4 revealed significant damage to subcuticular musculature and associated tissues and cellular organelles including mitochondria. In conclusion, the present study has discovered two algal compounds possessing acute anthelmintic effects and with potential for hit-to-lead progression. Future work should focus on undertaking a structure-activity relationship study and on elucidating the mode(s) of action of optimised compounds.
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- 2020
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45. Global Prevalence Estimates of Toxascaris leonina Infection in Dogs and Cats
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Ali Rostami, Seyed Mohammad Riahi, Vahid Fallah Omrani, Tao Wang, Andreas Hofmann, Aliyar Mirzapour, Masoud Foroutan, Yadolah Fakhri, Calum N. L. Macpherson, and Robin B. Gasser
- Subjects
Toxascaris leonina ,global prevalence ,dogs ,cats ,meta-analysis ,Medicine - Abstract
Toxascaris leonina is an ascaridoid nematode of dogs and cats; this parasite affects the health of these animals. This study estimated the global prevalence of Ta. leonina infection in dogs and cats using random effects meta-analysis as well as subgroup, meta-regression and heterogeneity analyses. The data were stratified according to geographical region, the type of dogs and cats and environmental variables. A quantitative analysis of 135 published studies, involving 119,317 dogs and 25,364 cats, estimated prevalence rates of Ta. leonina in dogs and cats at 2.9% and 3.4%, respectively. Prevalence was highest in the Eastern Mediterranean region (7.2% for dogs and 10.0% for cats) and was significantly higher in stray dogs (7.0% vs. 1.5%) and stray cats (7.5% vs. 1.8%) than in pets. The findings indicate that, worldwide, ~26 million dogs and ~23 million cats are infected with Ta. leonina; these animals would shed substantial numbers of Ta. leonina eggs into the environment each year and might represent reservoirs of infection to other accidental or paratenic hosts. It is important that populations of dogs and cats as well as other canids and felids be monitored and dewormed for Ta. leonina and (other) zoonotic helminths.
- Published
- 2020
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46. Synthetic Kavalactone Analogues with Increased Potency and Selective Anthelmintic Activity against Larvae of Haemonchus contortus In Vitro
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H.M.P. Dilrukshi Herath, Aya C. Taki, Nghi Nguyen, José Garcia-Bustos, Andreas Hofmann, Tao Wang, Guangxu Ma, Bill C.H. Chang, Abdul Jabbar, Brad E. Sleebs, and Robin B. Gasser
- Subjects
kavalactone ,synthetic analogues ,anthelmintic ,in vitro-activity ,Haemonchus contortus ,Organic chemistry ,QD241-441 - Abstract
Kava extract, an aqueous rhizome emulsion of the plant Piper methysticum, has been used for centuries by Pacific Islanders as a ceremonial beverage, and has been sold as an anxiolytic agent for some decades. Kavalactones are a major constituent of kava extract. In a previous investigation, we had identified three kavalactones that inhibit larval development of Haemonchus contortus in an in vitro-bioassay. In the present study, we synthesized two kavalactones, desmethoxyyangonin and yangonin, as well as 17 analogues thereof, and evaluated their anthelmintic activities using the same bioassay as employed previously. Structure activity relationship (SAR) studies showed that a 4-substituent on the pendant aryl ring was required for activity. In particular, compounds with 4-trifluoromethoxy, 4-difluoromethoxy, 4-phenoxy, and 4-N-morpholine substitutions had anthelmintic activities (IC50 values in the range of 1.9 to 8.9 µM) that were greater than either of the parent natural products—desmethoxyyangonin (IC50 of 37.1 µM) and yangonin (IC50 of 15.0 µM). The synthesized analogues did not exhibit toxicity on HepG2 human hepatoma cells in vitro at concentrations of up to 40 µM. These findings confirm the previously-identified kavalactone scaffold as a promising chemotype for new anthelmintics and provide a basis for a detailed SAR investigation focused on developing a novel anthelmintic agent.
- Published
- 2020
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- View/download PDF
47. Expression of N471D strumpellin leads to defects in the endolysosomal system
- Author
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Lin Song, Ramesh Rijal, Malte Karow, Maria Stumpf, Oliver Hahn, Laura Park, Robert Insall, Rolf Schröder, Andreas Hofmann, Christoph S. Clemen, and Ludwig Eichinger
- Subjects
Spastic paraplegia 8 ,Strumpellin ,WASH complex ,Dictyostelium discoideum ,Endolysosomal system ,Exocytosis ,Lysosome ,Medicine ,Pathology ,RB1-214 - Abstract
Hereditary spastic paraplegias (HSPs) are genetically diverse and clinically characterised by lower limb weakness and spasticity. The N471D and several other point mutations of human strumpellin (Str; also known as WASHC5), a member of the Wiskott–Aldrich syndrome protein and SCAR homologue (WASH) complex, have been shown to cause a form of HSP known as spastic paraplegia 8 (SPG8). To investigate the molecular functions of wild-type (WT) and N417D Str, we generated Dictyostelium Str− cells and ectopically expressed StrWT-GFP or StrN471D-GFP in Str− and WT cells. Overexpression of both proteins apparently caused a defect in cell division, as we observed a clear increase in multinucleate cells. Real-time PCR analyses revealed no transcriptional changes in WASH complex subunits in Str− cells, but western blots showed a twofold decrease in the SWIP subunit. GFP-trap experiments in conjunction with mass-spectrometric analysis revealed many previously known, as well as new, Str-interacting proteins, and also proteins that no longer bind to StrN471D. At the cellular level, Str− cells displayed defects in cell growth, phagocytosis, macropinocytosis, exocytosis and lysosomal function. Expression of StrWT-GFP in Str− cells rescued all observed defects. In contrast, expression of StrN471D-GFP could not rescue lysosome morphology and exocytosis of indigestible material. Our results underscore a key role for the WASH complex and its core subunit, Str, in the endolysosomal system, and highlight the fundamental importance of the Str N471 residue for maintaining lysosome morphology and dynamics. Our data indicate that the SPG8-causing N471D mutation leads to a partial loss of Str function in the endolysosomal system. This article has an associated First Person interview with the first author of the paper.
- Published
- 2018
- Full Text
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48. Interaction of High Flash Point Electrolytes and PE-Based Separators for Li-Ion Batteries
- Author
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Andreas Hofmann, Christoph Kaufmann, Marcus Müller, and Thomas Hanemann
- Subjects
Li-ion battery ,electrolytes ,separators ,contact angle ,safety ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
In this study, promising electrolytes for use in Li-ion batteries are studied in terms of interacting and wetting polyethylene (PE) and particle-coated PE separators. The electrolytes are characterized according to their physicochemical properties, where the flow characteristics and the surface tension are of particular interest for electrolyte–separator interactions. The viscosity of the electrolytes is determined to be in a range of η = 4–400 mPa∙s and surface tension is finely graduated in a range of γL = 23.3–38.1 mN∙m−1. It is verified that the technique of drop shape analysis can only be used in a limited matter to prove the interaction, uptake and penetration of electrolytes by separators. Cell testing of Li|NMC half cells reveals that those cell results cannot be inevitably deduced from physicochemical electrolyte properties as well as contact angle analysis. On the other hand, techniques are more suitable which detect liquid penetration into the interior of the separator. It is expected that the results can help fundamental researchers as well as users of novel electrolytes in current-day Li-ion battery technologies for developing and using novel material combinations.
- Published
- 2015
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- View/download PDF
49. Mechanism of environmentally driven conformational changes that modulate H-NS DNA-bridging activity
- Author
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Ramon A van der Valk, Jocelyne Vreede, Liang Qin, Geri F Moolenaar, Andreas Hofmann, Nora Goosen, and Remus T Dame
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H-NS ,Hha ,YdgT ,nucleoid ,bacterial chromatin ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Bacteria frequently need to adapt to altered environmental conditions. Adaptation requires changes in gene expression, often mediated by global regulators of transcription. The nucleoid-associated protein H-NS is a key global regulator in Gram-negative bacteria and is believed to be a crucial player in bacterial chromatin organization via its DNA-bridging activity. H-NS activity in vivo is modulated by physico-chemical factors (osmolarity, pH, temperature) and interaction partners. Mechanistically, it is unclear how functional modulation of H-NS by such factors is achieved. Here, we show that a diverse spectrum of H-NS modulators alter the DNA-bridging activity of H-NS. Changes in monovalent and divalent ion concentrations drive an abrupt switch between a bridging and non-bridging DNA-binding mode. Similarly, synergistic and antagonistic co-regulators modulate the DNA-bridging efficiency. Structural studies suggest a conserved mechanism: H-NS switches between a ‘closed’ and an ‘open’, bridging competent, conformation driven by environmental cues and interaction partners.
- Published
- 2017
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50. A Plea for Temperature in Descriptions of the Oceanic Oxygen Status
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Peter G. Brewer and Andreas Hofmann
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ocean temperature ,ocean oxygen ,ocean warming ,Oceanography ,GC1-1581 - Abstract
For over 50 years, the ocean science community has traditionally reported hypoxic limits for marine animals simply as a concentration value independent of temperature and pressure, implying the same limit for the warmest shallow gulf or the coldest deep fjord. Similarly, deep-sea oxygen consumption rates are typically reported as exponential functions of depth. In implicitly combining temperature, pressure, and multiple other properties into a single variable, it becomes difficult to describe the future of an ocean under changing climate conditions. We report here on a series of recent papers that seek to provide improved descriptions, by mapping the ocean pO2 field and then matching it to the various concentration limits proposed. We describe the availability of O2 to marine animals as being governed by a diffusive boundary rate process similar to well-known descriptions of air-sea gas exchange. We also describe the challenge for a deep-sea animal exporting CO2 through the same boundary layer with known chemical reactivity imposed. The end result is a clear sense that ocean warming in most regions will add stress to the aerobic functioning of marine life, that the oxygen minimum zones appear to be more challenging than ever, and that the deepest abyssal ocean will retain quite favorable aerobic conditions
- Published
- 2014
- Full Text
- View/download PDF
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