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Conversion and Calculations between Different Commercial Toxin Products
Published in Yates Yen-Yu Chao, Optimizing Aesthetic Toxin Results, 2022
Jürgen Frevert, Yates Yen-Yu Chao, Jürgen Frevert, Yates Yen-Yu Chao
After growth and lysis of the clostridia, the neurotoxin is purified by applying different purification protocols (Figure 4.1): onabotulinumtoxin is purified by precipitation with ethanol, followed by a series of ammonium sulphate precipitation, and dissolution (“crystallization”) resulting in a large complex (900 kDa complex) (Schantz & Johnson 1992) composed of the 150kDa neurotoxin attached to several other proteins, the so-called complexing proteins or neurotoxin associated proteins (NAPs). Abobotulinumtoxin A is processed by applying ion exchange chromatography (Panjwani et al. 2008), providing a mixture of complexes whose identity is not published by the manufacturer. In addition, aboboutulinumtoxin contains an additional bacterial protein (not a complexing protein), flagellin (see Chapter 3 on immunogenicity). On the other hand, incobotulinumtoxin is purified in a series of chromatographic steps, resulting in a pure 150 kDa neurotoxin without any other clostridial proteins or other impurities such as nucleic acids, which are found in onabotulinumtoxin (Groenewald & Frevert 2015). The complexing proteins are unnecessary for the therapeutic effect, as they do not influence the biological activity. In addition, they do not have any benefit for the pharmaceutical properties of the products (Frevert & Dressler 2010).
Antibiotics: The Need for Innovation
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
Other antibiotics target bacterial protein synthesis by acting on nucleic acid transcription and replication. Examples of the structures of this class of antibiotics are given in Figure 3 of the Supporting Material∗. Quinolone compounds, such as nalidixic acid, are particularly useful for the short-term treatment of urinary tract infections. Resistance soon develops to these compounds; consequently new analogues had to be developed. Modifications to the structure of nalidixic acid were found to increase he spectrum of activity against both gram-negative and gram-positive bacteria.
All is changed – changed utterly
Published in Brendan Curran, A Terrible Beauty is Born, 2020
Genes have been cloned from a surprisingly wide variety of sources, allowing the transgenic plants to make specific products to enhance their ability to survive pests, weeds, adverse weather conditions or whatever. A gene for a bacterial protein toxic to insects (but not to us) has been transferred into crops making them poisonous and thus resistant to attack by those insects without any adverse effects on humans. Another gene encodes an enzyme which makes the host plant resistant to certain herbicides, so allowing the use of weed-killer in fields of crops without having to resort to hand weeding. A gene encoding an anti-freeze protein in Arctic fish has been used to confer frost tolerance on plants. All of these modifications are aimed at increasing the quantity of produce.
Impact of chronic medications in the perioperative period: mechanisms of action and adverse drug effects (Part I)
Published in Postgraduate Medicine, 2021
Ofelia Loani Elvir-Lazo, Paul F White, Hillenn Cruz Eng, Firuz Yumul, Raissa Chua, Roya Yumul
Bacteriostatic antibiotics usually function by inhibiting bacterial protein synthesis pathways. Common bacteriostatic antibiotic classes include tetracyclines that work by reversibly inhibiting 30S bacterial ribosomal subunit, macrolides that inhibit the larger 50S subunit of bacterial ribosomes and lincosamides (e.g. clindamycin) also inhibit the 50S bacterial subunit but at a different site than the macrolides. Another class of bacteriostatic antibiotics, the oxazolidinones (e.g. linezolid), inhibits the formation of the initiation complex of the 50S ribosome, ultimately preventing the formation of bacterial ribosomes rather than preventing protein synthesis. Lastly, sulfonamides (e.g. trimethoprim/sulfamethoxazole) inhibit bacterial synthesis of tetrahydrofolic acid, preventing the processing of folic acid and its derivatives in bacteria [48–52].
An integrated workflow for enhanced taxonomic and functional coverage of the mouse fecal metaproteome
Published in Gut Microbes, 2021
Nicolas Nalpas, Lesley Hoyles, Viktoria Anselm, Tariq Ganief, Laura Martinez-Gili, Cristina Grau, Irina Droste-Borel, Laetitia Davidovic, Xavier Altafaj, Marc-Emmanuel Dumas, Boris Macek
We initially established a benchmarked standard by processing the HeLa measurement only against an H. sapiens database, which resulted in approximately 5,000 human (eukaryota) protein groups identified for the single-step search at FDR ≤ .01 (Figure 2a, Table S2). Notably, the same database used in a two-step search identified less than 1% additional protein groups in comparison to a single-step search, despite nearly twice as much processing time. We then processed our HeLa measurement against the H. sapiens database supplemented with 1×, 2×, 5×, 10× and 20× bacterial protein sequences, resulting in increasingly large databases (Figure S2A, Table S2). For the single-step database search against the 1:20 database, we observed a 10% decline in the number of human protein groups identified, while 132 bacterial protein groups were identified (false positives). On the contrary, the 1:20 two-step database search resulted only in a 1% decrease compared to the benchmarked standard. This processing also revealed a large number of bacterial protein groups identification (980 protein groups). Furthermore, the two-step search led to large number of MS/MS spectra to be assigned to different sequences (or newly assigned) in comparison to the benchmarked standard (Figure S2B, Table S2); this phenomenon was much less pronounced when performing the single-step search.
Current techniques to accurately measure anti-retinal autoantibodies
Published in Expert Review of Ophthalmology, 2020
We designed antigen panels, considering information from other assays and the frequency of antibody positivity in relation to clinical diseases. The most important factor in the preparation of a panel of autoantigens is the source of antigen (native protein vs. recombinant protein) and the purity of proteins used. In most cases, recombinant autoantigens are a convenient and reliable source of antigens that can be used in detection systems, but the purity of each protein needs to be examined by gel electrophoresis and tested with positive and negative controls of a given antibody before they are used in AAb testing. In particular, bacterial protein contaminations in recombinant protein preparations can yield a fault-positive result. Also, recombinant proteins may lack posttranslational modifications or maybe improperly protein folded, and as such do not express epitopes in the same way as native antigens and may not fully correlate with that of native antigens. In such cases, the use of native proteins purified from mammalian tissues, or recombinant proteins produced in eukaryotic cells, may be necessary. The isolation of native antigenic proteins from natural sources also has limitations, such as purity, yield, and reproducibility.