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  • 1
    Online Resource
    Online Resource
    Influence of the Cooling Time on the Microstructural Evolution and Mechanical Performance of a Double Pulse Resistance Spot Welded Medium-Mn Steel
    MDPI AG ; 2021
    In:  Metals Vol. 11, No. 2 ( 2021-02-05), p. 270-
    Details
    In: Metals, MDPI AG, Vol. 11, No. 2 ( 2021-02-05), p. 270-
    Abstract: In the present work, the influence of the cooling time on the mechanical performance, hardness, and microstructural features of a double pulse resistance spot welded medium-Mn steel are investigated. Curves of the electrical resistance throughout the welding revealed that the cooling time strongly influences the heat generation during the second pulse. A second pulse after a short cooling time re-melts the center, and heat treats the edge of the primary fusion zone. This desired in-process heat treatment leads to a modification of the cast-like martensitic structure by recrystallization illustrated by electron backscatter diffraction measurements and to a homogenization of manganese segregations, visualized by energy-dispersive X-ray spectroscopy, which results in an enhanced mechanical performance during the cross tension strength test. In contrast, during excessively long cooling times, the resistance drops to a level where the heat generation due to the second pulse is too low to sufficiently re-heat the edge of the primary FZ. As a consequence, the signs of recrystallization disappear, and the manganese segregations are still present at the edge of the fusion zone, which leads to a deterioration of the mechanical properties.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    URL: Article
    DOI: 10.3390/met11020270
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662252-X
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  • 2
    Online Resource
    Online Resource
    5′RNA Trans-Splicing Repair of COL7A1 Mutant Transcripts in Epidermolysis Bullosa
    MDPI AG ; 2022
    In:  International Journal of Molecular Sciences Vol. 23, No. 3 ( 2022-02-02), p. 1732-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 23, No. 3 ( 2022-02-02), p. 1732-
    Abstract: Mutations within the COL7A1 gene underlie the inherited recessive subtype of the blistering skin disease dystrophic epidermolysis bullosa (RDEB). Although gene replacement approaches for genodermatoses are clinically advanced, their implementation for RDEB is challenging and requires endogenous regulation of transgene expression. Thus, we are using spliceosome-mediated RNA trans-splicing (SMaRT) to repair mutations in COL7A1 at the mRNA level. Here, we demonstrate the capability of a COL7A1-specific RNA trans-splicing molecule (RTM), initially selected using a fluorescence-based screening procedure, to accurately replace COL7A1 exons 1 to 64 in an endogenous setting. Retroviral RTM transduction into patient-derived, immortalized keratinocytes resulted in an increase in wild-type transcript and protein levels, respectively. Furthermore, we revealed accurate deposition of recovered type VII collagen protein within the basement membrane zone of expanded skin equivalents using immunofluorescence staining. In summary, we showed for the first time the potential of endogenous 5′ trans-splicing to correct pathogenic mutations within the COL7A1 gene. Therefore, we consider 5′ RNA trans-splicing a suitable tool to beneficially modulate the RDEB-phenotype, thus targeting an urgent need of this patient population.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms23031732
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Microstructure and Local Mechanical Properties of the Heat-Affected Zone of a Resistance Spot Welded Medium-Mn Steel
    MDPI AG ; 2021
    In:  Materials Vol. 14, No. 12 ( 2021-06-17), p. 3362-
    Details
    In: Materials, MDPI AG, Vol. 14, No. 12 ( 2021-06-17), p. 3362-
    Abstract: The properties of the heat-affected zone (HAZ) are reported to have a great influence on the mechanical performance of resistance spot welded advanced high strength steels. Therefore, in the present work, the HAZ of a medium-Mn steel is characterized regarding its microstructure and its mechanical properties depending on the distance to the fusion zone (FZ). In order to obtain the local mechanical properties of the HAZ, samples were heat-treated in a joule-heating thermal simulator using different peak temperatures to physically simulate the microstructure of the HAZ. By comparing the microstructure and the hardness of these heat-treated samples and the HAZ, the local peak temperatures within the HAZ could be determined. Subsequently, tensile tests were conducted, and the austenite phase fraction was measured magnetically on the physically simulated HAZ samples in order to determine the local mechanical properties of the HAZ. As verified by energy-dispersive X-ray spectroscopy, peak temperatures above 1200 °C led to a uniform distribution of manganese, resulting in a predominantly martensitic microstructure with high strength and low total elongation after quenching. Below 1100 °C, the diffusion of manganese is restricted, and considerable fractions of austenite remain stable. The austenite fraction increases almost linearly with decreasing peak temperature, which leads to an increase of the total elongation and to a slight decrease in the strength, depending on the distance to the FZ. Temperatures below 700 °C exhibit hardly any effect on the initial microstructure and mechanical properties.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma14123362
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2487261-1
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  • 4
    Online Resource
    Online Resource
    Preclinical Assessment of Bacteriophage Therapy against Experimental Acinetobacter baumannii Lung Infection
    MDPI AG ; 2021
    In:  Viruses Vol. 14, No. 1 ( 2021-12-24), p. 33-
    Details
    In: Viruses, MDPI AG, Vol. 14, No. 1 ( 2021-12-24), p. 33-
    Abstract: Respiratory infections caused by multidrug-resistant Acinetobacter baumannii are difficult to treat and associated with high mortality among critically ill hospitalized patients. Bacteriophages (phages) eliminate pathogens with high host specificity and efficacy. However, the lack of appropriate preclinical experimental models hampers the progress of clinical development of phages as therapeutic agents. Therefore, we tested the efficacy of a purified lytic phage, vB_AbaM_Acibel004, against multidrug-resistant A. baumannii clinical isolate RUH 2037 infection in immunocompetent mice and a human lung tissue model. Sham- and A. baumannii-infected mice received a single-dose of phage or buffer via intratracheal aerosolization. Group-specific differences in bacterial burden, immune and clinical responses were compared. Phage-treated mice not only recovered faster from infection-associated hypothermia but also had lower pulmonary bacterial burden, lower lung permeability, and cytokine release. Histopathological examination revealed less inflammation with unaffected inflammatory cellular recruitment. No phage-specific adverse events were noted. Additionally, the bactericidal effect of the purified phage on A. baumannii was confirmed after single-dose treatment in an ex vivo human lung infection model. Taken together, our data suggest that the investigated phage has significant potential to treat multidrug-resistant A. baumannii infections and further support the development of appropriate methods for preclinical evaluation of antibacterial efficacy of phages.
    Type of Medium: Online Resource
    ISSN: 1999-4915
    URL: Article
    DOI: 10.3390/v14010033
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2516098-9
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  • 5
    Online Resource
    Online Resource
    A Combination of Structural, Genetic, Phenotypic and Enzymatic Analyses Reveals the Importance of a Predicted Fucosyltransferase to Protein O-Glycosylation in the Bacteroidetes
    MDPI AG ; 2021
    In:  Biomolecules Vol. 11, No. 12 ( 2021-11-30), p. 1795-
    Details
    In: Biomolecules, MDPI AG, Vol. 11, No. 12 ( 2021-11-30), p. 1795-
    Abstract: Diverse members of the Bacteroidetes phylum have general protein O-glycosylation systems that are essential for processes such as host colonization and pathogenesis. Here, we analyzed the function of a putative fucosyltransferase (FucT) family that is widely encoded in Bacteroidetes protein O-glycosylation genetic loci. We studied the FucT orthologs of three Bacteroidetes species—Tannerella forsythia, Bacteroides fragilis, and Pedobacter heparinus. To identify the linkage created by the FucT of B. fragilis, we elucidated the full structure of its nine-sugar O-glycan and found that l-fucose is linked β1,4 to glucose. Of the two fucose residues in the T. forsythia O-glycan, the fucose linked to the reducing-end galactose was shown by mutational analysis to be l-fucose. Despite the transfer of l-fucose to distinct hexose sugars in the B. fragilis and T. forsythia O-glycans, the FucT orthologs from B. fragilis, T. forsythia, and P. heparinus each cross-complement the B. fragilis ΔBF4306 and T. forsythia ΔTanf_01305 FucT mutants. In vitro enzymatic analyses showed relaxed acceptor specificity of the three enzymes, transferring l-fucose to various pNP-α-hexoses. Further, glycan structural analysis together with fucosidase assays indicated that the T. forsythia FucT links l-fucose α1,6 to galactose. Given the biological importance of fucosylated carbohydrates, these FucTs are promising candidates for synthetic glycobiology.
    Type of Medium: Online Resource
    ISSN: 2218-273X
    URL: Article
    DOI: 10.3390/biom11121795
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2701262-1
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