There are limited data on rates of failure and airway injury with the use of airway exchange catheters. We performed a single-center retrospective analysis of airway exchange catheters to determine the incidence and associated factors for tube exchange failure and airway injury. Among 1177 cases, failed intubation during attempted tube exchange was noted in 73/527 (13.8%). Airway exchange failure rates were greatest during exchange catheter use for double-lumen tube insertion and when intubation was attempted over the catheter postoperatively. Pneumothorax was noted after 1.5% of attempted tube exchanges. Difficult tube exchange was encountered in 6 of 8 patients with pneumothorax.

In recent years, protein labeling has been routinely performed with various fluorescent markers. [1] The labeling of proteins allows monitoring of the specific location, movement, and interaction of proteins with other intracellular components using fluorescence microscopy. [2] For several decades, the labeling strategy mostly dealt with green fluorescent protein (GFP) and its variants. In order to overcome the unaltered fluorescent property and uncontrolled expression time of GFP, small molecular probe-based labeling approaches for live-cell imaging methods have been developed. [3] However, most of the reported small-molecule labeling probes do not show different fluorescence properties for the labeled and unlabeled states. Fluorescein-based arsenical hairpin binder (FlAsH) and resorufin-based arsenical hairpin binder (ReAsH) are the pioneer techniques for fluorogenic protein labeling with small molecular probes. [4] In our earlier studies, we developed a site-specific protein labeling technique that employs a genetically modified blactamase (BL-tag). [5] Mutation at a specific position in TEM-1 (class A b-lactamases) provides turn-on fluorogenic biosensors involving a b-lactam ring. The reaction of wildtype TEM-1 (WT TEM) with the b-lactam moiety involves acylation and deacylation steps. [6] We have utilized the BLtag protein for covalent attachment with a substrate. Despite the similar molecular weights of the BL-tag and GFP, fluorogenicity can be introduced only through the BL-tag technology.We have developed a fluorogenic mechanism based on aggregation-elimination processes for highly selective protein labeling with a fluorophore of desired color using the BLtag technology. We have also shown a broad applicability of dinitrobenzene (DNB) as a quencher. [5c,d] However, the limitation of the technology is a slow fluorogenic response of the synthesized probes such as CCDNB, which carries a coumarin fluorophore moiety, a cephalosporin moiety, and DNB (Figure 1). The necessary incubation time for a cell imaging experiment using CCDNB was 60 minutes. To reduce the incubation time for the imaging experiments, we aimed at developing more sophisticated probes that possess the DNB quencher. Herein, we report two newly designed probes with shorter linkers compared to those of CCDNB. In addition, we modified slightly the quencher in one probe. The probe with the modified quencher showed a comparatively fast fluorogenicity in vitro and in live-cell imaging studies. Fluorescence lifetime measurements indicated a different quenching mechanism for the most active probe. A detailed analysis of this new fluorogenic mechanism revealed a photoinduced electron transfer (PET) process [7] from the fluorophore donor to the quencher acceptor.The two new probes CC2 DNB and CC3 DNB that have a comparatively short or no linker between the b-lactam and quencher, respectively, are depicted in Figure 1. 2-(2-Aminoethoxy)ethanamine was used as the linker between the cephalosporin part and the DNB quencher in CC2 DNB. A coumarin deri...

Fluorogenic protein labeling helps to localize a protein within the cell in the presence of an excess amount of quenched probes. In their Communication on , K. Kikuchi et al. propose an alternative fast approach for fluorogenic protein labeling. The fluorogenicity can be introduced by the removal of a photoinduced electron transfer‐based dynamic quencher. This strategy is more effective compared to the removal of a static aggregated quencher. The cover picture illustrates the better visibility of fireworks at the dynamic state (photo taken at the Hanabi festival in Japan; Sujata Kar Saha helped with cover design).