IN VITRO SELECTION OF ACTINIDIA DELICIOSA CLONES TOLERANT TO NACL AND THEIR MOLECULAR AND IN VIVO ECOPHYSIOLOGICAL CHARACTERISATION

2003 ◽  
pp. 77-83 ◽  
Author(s):  
E. Caboni ◽  
S. Anselmi ◽  
E. Donato ◽  
F. Manes
Keyword(s):  
In Vitro Selection ◽  
Actinidia Deliciosa ◽  
Selection Of

scholarly journals Robotic QM/MM-driven maturation of antibody combining sites

2016 ◽  
Vol 2 (10) ◽  
pp. e1501695 ◽  
Author(s):  
Ivan V. Smirnov ◽  
Andrey V. Golovin ◽  
Spyros D. Chatziefthimiou ◽  
Anastasiya V. Stepanova ◽  
Yingjie Peng ◽  
...  
Keyword(s):  
Immune Response ◽  
In Vitro Selection ◽  
Single Point ◽  
Combinatorial Libraries ◽  
Single Point Mutation ◽  
Wild Type ◽  
Selection Of ◽  
Maturation Function

In vitro selection of antibodies from large repertoires of immunoglobulin (Ig) combining sites using combinatorial libraries is a powerful tool, with great potential for generating in vivo scavengers for toxins. However, addition of a maturation function is necessary to enable these selected antibodies to more closely mimic the full mammalian immune response. We approached this goal using quantum mechanics/molecular mechanics (QM/MM) calculations to achieve maturation in silico. We preselected A17, an Ig template, from a naïve library for its ability to disarm a toxic pesticide related to organophosphorus nerve agents. Virtual screening of 167,538 robotically generated mutants identified an optimum single point mutation, which experimentally boosted wild-type Ig scavenger performance by 170-fold. We validated the QM/MM predictions via kinetic analysis and crystal structures of mutant apo-A17 and covalently modified Ig, thereby identifying the displacement of one water molecule by an arginine as delivering this catalysis.

In vitro Selection of a Peptide with High Selectivity for Cardiomyocytes In vivo

2004 ◽  
Vol 342 (1) ◽  
pp. 171-182 ◽  
Author(s):  
Michael J. McGuire ◽  
Kausar N. Samli ◽  
Stephen Albert Johnston ◽  
Kathlynn C. Brown
Keyword(s):  
In Vitro Selection ◽  
High Selectivity ◽  
Selection Of

scholarly journals In-Vitro Selection of Ceftazidime/Avibactam Resistance in OXA-48-Like-Expressing Klebsiella pneumoniae: In-Vitro and In-Vivo Fitness, Genetic Basis and Activities of β-Lactam Plus Novel β-Lactamase Inhibitor or β-Lactam Enhancer Combinations

Antibiotics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1318
Author(s):  
Snehal Palwe ◽  
Yamuna Devi Bakthavatchalam ◽  
Kshama Khobragadea ◽  
Arun S. Kharat ◽  
Kamini Walia ◽  
...  
Keyword(s):  
In Vitro Selection ◽  
Whole Genome Sequence ◽  
Serial Transfer ◽  
Resistance Selection ◽  
Clinical Resistance ◽  
Growth Properties ◽  
Outer Membrane Permeability ◽  
Selection Of

Ceftazidime/avibactam uniquely demonstrates activity against both KPC and OXA-48-like carbapenemase-expressing Enterobacterales. Clinical resistance to ceftazidime/avibactam in KPC-producers was foreseen in in-vitro resistance studies. Herein, we assessed the resistance selection propensity of ceftazidime/avibactam in K. pneumoniae expressing OXA-48-like β-lactamases (n = 10), employing serial transfer approach. Ceftazidime/avibactam MICs (0.25–4 mg/L) increased to 16–256 mg/L after 15 daily-sequential transfers. The whole genome sequence analysis of terminal mutants showed modifications in proteins linked to efflux (AcrB/AcrD/EmrA/Mdt), outer membrane permeability (OmpK36) and/or stress response pathways (CpxA/EnvZ/RpoE). In-vitro growth properties of all the ceftazidime/avibactam-selected mutants were comparable to their respective parents and they retained the ability to cause pulmonary infection in neutropenic mice. Against these mutants, we explored the activities of various combinations of β-lactams (ceftazidime or cefepime) with structurally diverse β-lactamase inhibitors or a β-lactam enhancer, zidebactam. Zidebactam, in combination with either cefepime or ceftazidime, overcame ceftazidime/avibactam resistance (MIC range 0.5–8 mg/L), while cefepime/avibactam was the second best (MIC: 0.5–16 mg/L) in yielding lower MICs. The present work revealed the possibility of ceftazidime/avibactam resistance in OXA-48-like K. pneumoniae through mutations in proteins involved in efflux and/or porins without concomitant fitness cost mandating astute monitoring of ceftazidime/avibactam resistance among OXA-48 genotypes.

scholarly journals A Simple Model for Assessment of Anti-Toxin Antibodies

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Alex Skvortsov ◽  
Peter Gray
Keyword(s):  
In Vitro Selection ◽  
Receptor Complex ◽  
Simple Mathematical Model ◽  
Antibody Affinity ◽  
In Vivo Evaluation ◽  
Degree Of Protection ◽  
Protective Antibodies ◽  
Selection Of

The toxins associated with infectious diseases are potential targets for inhibitors which have the potential for prophylactic or therapeutic use. Many antibodies have been generated for this purpose, and the objective of this study was to develop a simple mathematical model that may be used to evaluate the potential protective effect of antibodies. This model was used to evaluate the contributions of antibody affinity and concentration to reducing antibody-receptor complex formation and internalization. The model also enables prediction of the antibody kinetic constants and concentration required to provide a specified degree of protection. We hope that this model, once validated experimentally, will be a useful tool for in vitro selection of potentially protective antibodies for progression to in vivo evaluation.

scholarly journals Convergent In Vivo and In Vitro Selection of Ceftazidime Resistance Mutations at Position 167 of CTX-M-3 β-Lactamase in Hypermutable Escherichia coli Strains

2008 ◽  
Vol 52 (4) ◽  
pp. 1297-1301 ◽  
Author(s):  
Marina N. Stepanova ◽  
Maxim Pimkin ◽  
Anatoly A. Nikulin ◽  
Varvara K. Kozyreva ◽  
Elena D. Agapova ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Typing ◽  
In Vitro Selection ◽  
Resistance Mutations ◽  
Natural Evolution ◽  
E Coli ◽  
Low Activity ◽  
Selection Of

ABSTRACT We report on a novel CTX-M extended-spectrum β-lactamase (ESBL), designated CTX-M-42, with enhanced activity toward ceftazidime. CTX-M-42 was identified in a hypermutable Escherichia coli nosocomial isolate (isolate Irk2320) and is a Pro167Thr amino acid substitution variant of CTX-M-3. By molecular typing of ESBL-producing E. coli strains previously isolated in the same hospital ward, we were able to identify a putative progenitor (strain Irk1224) of Irk2320, which had a mutator phenotype and harbored the CTX-M-3 β-lactamase. To reproduce the natural evolution of CTX-M-3, we selected for ceftazidime resistance mutations in bla CTX-M-3 gene in vitro both in clinical isolate Irk1224 and in laboratory-derived hypermutable (mutD5) strain GM2995. These experiments yielded CTX-M-3Pro167Ser and CTX-M-3Asn136Lys mutants which conferred higher levels of resistance to ceftazidime than to cefotaxime. CTX-M-3Asn136Lys had a level of low activity toward ampicillin, which may explain its absence from clinical isolates. We conclude that the selection of CTX-M-42 could have occurred in vivo following treatment with ceftazidime and was likely facilitated by the hypermutable background.

scholarly journals In vitro selection of winter triticale for salt resistance

1970 ◽  
pp. 247-251
Author(s):  
S. V. Pykalo ◽  
O. V. Dubrovna ◽  
O. A. Demydov
Keyword(s):  
Salt Stress ◽  
Cell Lines ◽  
In Vitro Selection ◽  
High Survival ◽  
Winter Triticale ◽  
Step Type ◽  
Callus Lines ◽  
Selection Of

Aim. To obtain of cell lines and plant-regenerants of winter triticale resistant for salt stress the in vitro selection was carried out. Methods. In order to select resistant to salt stress forms of triticale the efficiency of using direct and step-type in vitro selection with application of selective system based on sodium chloride has been investigated. Results. The direct and step-type in vitro selection was conducted and the selection of callus lines of triticale being resistant to simu-lated salinity was carried out. As a result, from line 38/1296 and variety Obriy respectively, 5 and 4 resistant callus lines were identified that had a high survival rate on the selective medium with 1.2 % NaCl and maintained morphogenetic potential. From the resistant lines plant regenerants were induced and their rearing, rooting and transfer to in vivo condi-tions were optimized. Conclusions. A step-type in vitro selection was more effective, because resulted from the selec-tion more resistant callus forms were identified. First cell lines of winter triticale with resistance to salt stress were de-rived.Keywords: Triticale, in vitro selection, callus, salt stress, resistance.

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