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Tanaka, Shota, Koshi Nakagawa, Yosuke Kanagawa, Takashi Katsurahara, Kazuki Kozakai, Ken Tsuhako, Fumitaka Yoshikawa, Soh Gotoh, Kensuke Osanai, Madoka Sono, Hironori Inoue, Shuji Sakanashi, Hiroyuki Takahashi, and Hideharu Tanaka. Quality of cardiopulmonary resuscitation in avalanche victims with a single rescuer: a prospective, crossover, manikin pilot study. High Alt Med Biol . 25:60-67, 2024. Background: Winter outdoor recreational activities such as off-piste skiing have gained popularity and, as a result, the number of avalanche-related deaths has increased. However, the quality of cardiopulmonary resuscitation (CPR) at avalanche sites remains unclear. Our study compared the quality of CPR performed in a simulated avalanche burial on a snowy mountain with that performed indoors. Methods: Ten prehospital health care providers participated in the crossover pilot study. Various methods, including over-the-head CPR (OTH-CPR) and standard CPR, were used to perform avalanche resuscitation, with five rescue breaths, followed by 30 chest compressions and two breaths. The quality CPR was judged by four variables of chest compression and ventilation. Results: The OTH-CPR performed indoors was better in quality: 5.33% [95% confidence interval (CI) -14.2 to 3.5] higher in adequate compression depth (94.3 ± 10.6% on the snow vs. 99.3 ± 1.1% indoors), 3.4% [95% CI -16.1 to 22.9] higher in adequate compression rate (70.4 ± 38.0% vs. 76.1 ± 35.7%), and 2.3% [95% CI -6.4 to 1.72] higher in adequate recoil (96.9 ± 4.8% vs. 99.2 ± 1.6%) than OTH-CPR on the snow. In terms of ventilation quality, OTH-CPR performed indoors had a 50% higher ventilation score [95% CI -73.0 to -27.0] than OTH-CPR on the snow (1.4 ± 4.3% vs. 45.9 ± 32.6%, Cohen's d  = -1.81). Conclusions: Chest compression quality was slightly impaired in the avalanche scenarios on the snow than in indoor settings. Asphyxiation is the main cause of avalanche-related deaths; however, low ventilation quality was observed on snow compared with the indoor setting.

Bioconversion of peptidyl amino acids into enzyme cofactors is an important post-translational modification. Here, we report a flavoprotein, essential for biosynthesis of a protein-derived quinone cofactor, cysteine tryptophylquinone, contained in a widely distributed bacterial enzyme, quinohemoprotein amine dehydrogenase. The purified flavoprotein catalyzes the single-turnover dihydroxylation of the tryptophylquinone-precursor, tryptophan, in the protein substrate containing triple intra-peptidyl crosslinks that are pre-formed by a radical S-adenosylmethionine enzyme within the ternary complex of these proteins. Crystal structure of the peptidyl tryptophan dihydroxylase reveals a large pocket that may dock the protein substrate with the bound flavin adenine dinucleotide situated close to the precursor tryptophan. Based on the enzyme-protein substrate docking model, we propose a chemical reaction mechanism of peptidyl tryptophan dihydroxylation catalyzed by the flavoprotein monooxygenase. The diversity of the tryptophylquinone-generating systems suggests convergent evolution of the peptidyl tryptophan-derived cofactors in different proteins.