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  • 1
    Language: English
    In: Toxicon, 15 September 2012, Vol.60(4), pp.632-647
    Description: Cobra Venom Factor (CVF) is the complement-activating protein in cobra venom. CVF is structurally and functionally highly homologous to complement component C3. CVF, like C3b, the activated form of C3, forms a bimolecular complex with Factor B in serum, called C3/C5 convertase, an enzyme which activates complement components C3 and C5. Despite the high degree of homology, the two C3/C5 convertases exhibit significant functional differences. The most important difference is that the convertase formed with CVF (CVF,Bb) is physico-chemically far more stable than the convertase formed with C3b (C3b,Bb). In addition, the CVF,Bb convertase and CVF are completely resistant to inactivation by the complement regulatory proteins Factor H and Factor I. Furthermore, the CVF,Bb enzyme shows efficient C5-cleaving activity in fluid phase. In contrast, the C3b,Bb enzyme is essentially devoid of fluid-phase C5-cleaving activity. By taking advantage of the high degree of sequence identity at both the amino acid (85%) and DNA levels (93%) between CVF and cobra C3, we created hybrid proteins of CVF and cobra C3 where sections, or only a few amino acids, of the CVF sequence were replaced with the homologous amino acid sequence of cobra C3. In a first set of experiments, we created five hybrid proteins, termed H1 through H5, where the cobra C3 substitutions collectively spanned the entire length of the CVF protein. We also created three additional hybrid proteins where only four or five amino acid residues in CVF were exchanged with the corresponding amino acid residues from cobra C3. Collectively, these hybrid proteins, representing loss-of-function mutants of CVF, allowed the identification of regions and individual amino acid residues important for the CVF-specific functions. The results include the observation that the CVF β-chain is crucially important for forming a stable convertase, whereas the CVF α-chain appears to harbor no CVF-specific functions. Furthermore, the CVF γ-chain is additionally important for the fluid-phase C5-cleaving activity of CVF,Bb. Interestingly, the structural changes in the individual hybrid proteins differentially affected the molecular functions of the CVF,Bb enzyme such as convertase formation, C3 cleavage, and C5 cleavage.
    Keywords: Cobra Venom Factor ; Complement ; Complement Component C3 ; C3 Convertase ; Hybrid Proteins ; Cobra (Naja Sp.) ; Pharmacy, Therapeutics, & Pharmacology ; Anatomy & Physiology
    ISSN: 0041-0101
    E-ISSN: 1879-3150
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  • 2
    Language: German
    In: Nachrichten aus der Chemie, March 2006, Vol.54(3), pp.316-317
    Description: Genomische DNA lässt sich auch automatisch aus Pflanzenproben isolieren, so dass die Ergebnisse reproduzierbar sind und keine Kreuzkontaminationen auftreten.
    ISSN: 1439-9598
    E-ISSN: 1868-0054
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  • 3
    Language: German
    Description: Hamburg, Universiẗat, Diss., 2001.
    Keywords: Cobra Venom Factor
    Source: Networked Digital Library of Theses and Dissertations
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  • 4
    Language: English
    In: Immunopharmacology, 8/2000, Vol.49(1-2), p.94
    ISSN: 01623109
    Source: Elsevier (via CrossRef)
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  • 5
    In: Journal of Antimicrobial Chemotherapy, 2015, Vol. 70(11), pp.2992-2999
    Description: Objectives The objective of this study was to determine the activity of fidaxomicin and comparator antimicrobials against Clostridium difficile isolated from patients with C. difficile infection (CDI) in Australian hospitals and in the community. Methods One private and one public laboratory from five states in Australia submitted a total of 474 isolates/PCR-positive stool samples during three collection periods in August-September 2013 (n=175), February-March 2014 (n=134) and August-September 2014 (n=165). Isolate identification was confirmed by selective culture for C. difficile and a proportion of isolates from each state were characterized by PCR for toxin genes and PCR ribotyping. MICs of fidaxomicin and eight comparator antimicrobials were determined for all isolates using agar methodology. Results Site collection yielded 440 isolates of C. difficile and PCR revealed a heterogeneous strain population comprising 37 different PCR ribotypes (RTs), 95% of which were positive for tcdA and tcdB (A+B+). The most common RTs were 014 (29.8%) and 002 (15.9%). Epidemic RT 027 was not identified; however, small numbers of virulent RTs 078 and 244 were found. Resistance to vancomycin, metronidazole and fidaxomicin was not detected and resistance to moxifloxacin was very low (3.4%). Fidaxomicin showed potent in vitro activity against all 440 isolates (MIC sub(50)/MIC sub(90) 0.03/0.12 mg/L) and was superior to metronidazole (MIC sub(50)/MIC sub(90) 0.25/0.5 mg/L) and vancomycin (MIC sub(50)/MIC sub(90) 1/2 mg/L). Conclusions These data confirm the potent in vitro activity of fidaxomicin against C. difficile. Moreover, this study provides an important baseline for ongoing long-term surveillance of antimicrobial resistance and prospective tracking of prominent and emerging strain types.
    Keywords: Ribotyping ; Metronidazole ; Agar ; Data Processing ; Epidemics ; Drug Resistance ; Infection ; Minimum Inhibitory Concentration ; Toxins ; Antimicrobial Agents ; Moxifloxacin ; Polymerase Chain Reaction ; Vancomycin ; Feces ; Hospitals ; Clostridium Difficile ; Antibiotics & Antimicrobials ; Antibiotics & Antimicrobials;
    ISSN: 0305-7453
    E-ISSN: 1460-2091
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  • 6
    Language: English
    In: Materials Science Forum, 2016, Vol.858, pp.410-413
    Description: The stability of 6.5 kV pn-diodes is dependent on the absence of critical crystal defects, such as basal plane dislocations. In this paper, we present a method to detect these defects on wafer level by utilizing photoluminescence (PL). The PL scan is performed immediately after epitaxy and also after the implantation process steps with subsequent high temperature annealing. The analysis of both scans enables the prediction of devices that will drift due to bipolar degradation, and devices that will exhibit non-drifting behaviour. To validate this PL scanning technique, forward bias electrical stress tests have been performed on the fabricated 6.5 kV pn-diodes.
    Keywords: Bipolar Degradation ; Defects ; Electrical Stress Test ; Photoluminescence ; Pn-Diode;
    ISBN: 9783035710427
    ISSN: 0255-5476
    E-ISSN: 1662-9752
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  • 7
    Language: English
    In: Anaerobe, February 2019, Vol.55, pp.117-123
    Description: Three patients with severe infection (CDI) caused by an unusual strain of , PCR ribotype (RT) 251, were identified in New South Wales, Australia. All cases presented with severe diarrhoea, two had multiple recurrences and one died following a colectomy. RT251 strains were isolated by toxigenic culture. Genetic characterisation was performed using techniques including toxin gene profiling, PCR ribotyping, whole genome sequencing (WGS), multi-locus-sequence-typing (MLST) and core-genome single nucleotide variant (SNV) analyses. Antimicrobial susceptibility was determined using an agar incorporation method. toxin production was confirmed by Vero cell cytotoxicity assay and pathogenicity was assessed in a murine model of CDI. All RT251 isolates contained toxin A ( ), toxin B ( ) and binary toxin ( and ) genes. Core-genome analyses revealed the RT251 strains were clonal, with 0–5 SNVs between isolates. WGS and MLST clustered RT251 in the same evolutionary clade (clade 2) as RT027. Despite comparatively lower levels of toxin production, in the murine model RT251 infection resembled RT027 infection. Mice showed marked weight loss, severe disease within 48 h post-infection and death. All isolates were susceptible to metronidazole and vancomycin. Our observations suggest RT251 causes severe disease and emphasise the importance of ongoing surveillance for new and emerging strains of with enhanced virulence.
    Keywords: Clostridium Difficile ; Ribotype 251 ; Severe Infection ; Fatal Infection ; Biology
    ISSN: 1075-9964
    E-ISSN: 1095-8274
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  • 8
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