A hydroxypropyl methylcellulose plaque assay for human respiratory syncytial virus

ウイルスの研究において感染性のあるウイルス粒子を正確に定量することは，病原性の評価のみならずウイルスに対する新規治療薬の効果を客観的に評価するために極めて重要な手技である．プラークアッセイ法はウイルス粒子を定量するために不可欠な技術であるが，Respiratory syncytial virus（RSV）において，プラークアッセイ法を安定して行うことはしばしば困難である．今回我々は，overlay material（充填化合物）が細胞増殖に与える影響を中心にRSVおよびhuman metapneumovirus（hMPV）におけるプラークアッセイ法の最適化の検討を行った

18. asırda "Hırkai şerif" ziyareti

Taha Toros Arşivi, Dosya No: 120-Saraylar. Not: Gazetenin "Tarihten Sahifeler" köşesinde yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Discovery of Biologically Optimized Polymyxin Derivatives Facilitated by Peptide Scanning and In Situ Screening Chemistry

Peptides can be converted to highly active compounds by introducing appropriate substituents on the suitable amino acid residue. Although modifiable residues in peptides can be systematically identified by peptide scanning methodologies, there is no practical method for optimization at the scanned position. With the purpose of using derivatives not only for scanning but also as a starting point for further chemical functionalization, we herein report the scanning and direct derivatization strategy through chemoselective acylation of embedded threonine residues by a serine/threonine ligation (STL) with the help of in situ screening chemistry. We have applied this strategy to the optimization of the polymyxin antibiotics, which were selected as a model system to highlight the power of the rapid derivatization of active scanning derivatives. Using this approach, we explored the structure-activity relationships of the polymyxins and successfully prepared derivatives with activity against polymyxin-resistant bacteria and those with Pseudomonas aeruginosa selective antibacterial activity. This strategy opens up efficient structural exploration and further optimization of peptide sequences

Synthesis and biological evaluation of a MraY selective analogue of tunicamycins

Tunicamycins, which are nucleoside natural products, inhibit both bacterial phospho-N-acetylmuraminic acid (MurNAc)-pentapeptide translocase (MraY) and human UDP-N-acetylglucosamine (GlcNAc): polyprenol phosphate translocase (GPT). The improved synthesis and detailed biological evaluation of an MraY-selective inhibitor, 2, where the GlcNAc moiety was modified to a MurNAc amide, has been described

Amino Acid Substitutions in GyrA and ParC are Associated with Fluoroquinolone Resistance in Mycoplasma bovis Isolates from Japanese Dairy Calves

We investigated the contribution of quinolone resistance-determining region (QRDR) mutations to fluoroquinolone (enrofloxacin, orbifloxacin and danofloxacin) susceptibility in 58 Mycoplasma bovis isolates from dairy cattle in Japan. Fluoroquinolone non-resistant isolates (fluoroquinolone-MICs≤2μg/ml) possessed no QRDR mutations (19 isolates) or Ser83Leu in GyrA (32 isolates). Fluoroquinoloneresistant isolates (fluoroquinolone-MICs≥4μg/ml) possessed Ser83Leu in GyrA and Ser81Pro in ParC (3 isolates) or Ser83Phe in GyrA and Ser80Ile in ParC (4 isolates). Laboratory-derived fluoroquinolone-resistant mutants selected from 2 isolates (possessing Ser83Leu in GyrA) had an amino acid substitution in ParC at the same position (Ser80Ile or Ser81Tyr) as fluoroquinolone-resistant isolates, suggesting a concurrent amino acid substitution in ParC (Ser80 or Ser81) is important in fluoroquinolone resistance in M. bovis isolates

Colistin Susceptibility in Companion Animal-Derived Escherichia coli, Klebsiella spp., and Enterobacter spp. in Japan : Frequent Isolation of Colistin-Resistant Enterobacter cloacae Complex

Transmission of colistin-resistant Enterobacterales from companion animals to humans poses a clinical risk as colistin is a last-line antimicrobial agent for treatment of multidrug-resistant Gram-negative bacteria including Enterobacterales. In this study, we investigated the colistin susceptibility of 285 Enterobacterales (including 140 Escherichia coli, 86 Klebsiella spp., and 59 Enterobacter spp.) isolated from companion animals in Japan. We further characterized colistin-resistant isolates by multilocus sequence typing (MLST), phylogenetic analysis of hsp60 sequences, and population analysis profiling, to evaluate the potential clinical risk of companion animal-derived colistin-resistant Enterobacterales to humans in line with the One Health approach. All E. coli isolates were susceptible to colistin, and only one Klebsiella spp. isolate (1.2%, 1/86 isolates) was colistin resistant. Enterobacter spp. isolates were frequently colistin resistant (20.3%, 12/59 isolates). In colistin-resistant Enterobacter spp., all except one isolate exhibited colistin heteroresistance by population analysis profiling. These colistin-heteroresistant isolates belonged to clusters I, II, IV, VIII, and XII based on hsp60 phylogeny. MLST analysis revealed that 12 colistin-resistant Enterobacter spp. belonged to the Enterobacter cloacae complex; five Enterobacter kobei (four ST591 and one ST1577), three Enterobacter asburiae (one ST562 and two ST1578), two Enterobacter roggenkampii (ST606 and ST1576), and Enterobacter hormaechei (ST1579) and E. cloacae (ST765) (each one strain). Forty-two percent of the colistin-resistant E. cloacae complex isolates (predominantly ST562 and ST591) belonged to lineages with human clinical isolates. Four E. kobei ST591 isolates were resistant to third-generation cephalosporines, aminoglycosides, and fluroquinolones but remained susceptible to carbapenems. In conclusion, our study is the first to our knowledge to report the frequent isolation of the colistin-resistant E. cloacae complex from companion animals. Furthermore, a subset of isolates belonged to human-associated lineages with resistance to multiple classes of antibiotics. These data warrant monitoring carriage of the colistin-resistant E. cloacae complex in companion animals as part of a domestic infection control procedure in line with the One Health approach