The phrase "a first challenge with" is correct and usable in written English.
It can be used when introducing or discussing an initial difficulty or obstacle encountered in a particular context or situation.
Example: "The team faced a first challenge with the new software implementation, which required extensive training for all employees."
Alternatives: "an initial challenge regarding" or "a primary challenge involving".
Moreover, after a long exposure with tumor cells, purified BMDC were unable to respond to a second challenge with TLR ligands.
Barcelona's initial appeal was rejected by the competition committee and the club lodged a second challenge with a higher appeals committee which ruled in their favour on Thursday.
However, preincubation for 10 min with Orai pharmacological inhibitors, YM58483 or Synta66, reduced the rate of Ca2+ influx observed in response to a second challenge with TNFα, to a value similar to basal (Fig. 2A middle and right).
Initial exposure of monocytes/macrophages to LPS induces hyporesponsiveness to a second challenge with LPS, a phenomenon termed LPS tolerance.
Conclusions While human endotoxemia attenuates the inflammatory response of a second challenge with endotoxin with approximately 70 %[2], it does not influence the Fluenz-induced local immune response and viral shedding.
A second challenge with trying to ferment biomass derived sugars is the presence and production of inhibitors which can cause the slowing or cessation of microbial cell growth, reduced ethanol productivity and low ethanol yield (Palmqvist and Hahn-Hägerdal 2000, Klinke et al. 2004, Almeida et al. 2007, Almeida et al. 2011).
We also showed that a second challenge with METH did not elicit any further decreases in DA markers.
Four months after the first sporozoite challenge, all animals received a second challenge with 100 P. knowlesi sporozoites given IV. Figure 5 shows the daily parasitemias for each monkey during the second challenge.
To induce a higher titer of B. pertussis-specific antibodies, B. pertussis-inoculated mice were allowed to convalesce for 28 days followed by a second challenge with B. pertussis and subsequent cardiac puncture 3 days post secondary inoculation.
A second challenge with antigen increased CD4+IL-17+ cells.
