Sedation by dexmedetomidine, like natural sleep, often causes bradycardia. We explored the nature of heart rate (HR) changes as they occur during natural sleep versus those occurring during dexmedetomidine sedation. The present study included 30 patients who were scheduled to undergo elective surgery with spinal anesthesia. To assess HR and sedation, a pulse oximeter and bispectral index (BIS) monitor were attached to the patient in the ward and the operating room. After measuring HR and BIS at baseline, as the patients slept and once their BIS was below 70, HR and BIS were measured at 5-minute intervals during sleep. Baseline HR and BIS were also recorded before spinal anesthesia measured at 5-minute intervals after dexmedetomidine injection. During natural sleep, HR changes ranged from 2 to 19 beats/min (13.4 ± 4.4 beats/min), while in dexmedetomidine sedation, HR ranged from 9 to 40 beats/min (25.4 ± 8.5 beats/min). Decrease in HR was significantly correlated between natural sleep and dexmedetomidine sedation (R2 = 0.41, P < 0.001). The lowest HR was reached in 66 min during natural sleep (59 beats/min) and in 13 min with dexmedetomidine sedation (55 beats/min). The time to reach minimum HR was significantly different (P < 0.001), but there was no difference in the lowest HR obtained (P = 0.09). There was a correlation between the change in HR during natural sleep and dexmedetomidine sedation. The bradycardia that occurs when using dexmedetomidine may be a normal physiologic change, that can be monitored rather than corrected.

Aminoacyl-tRNA synthetase-interacting multifunctional proteins (AIMPs) are auxiliary factors involved in protein synthesis related to aminoacyl-tRNA synthetases (ARSs). AIMPs, which are well known as nonenzymatic factors, include AIMP1/p43, AIMP2/p38, and AIMP3/p18. The canonical functions of AIMPs include not only protein synthesis via multisynthetase complexes but also maintenance of the structural stability of these complexes. Several recent studies have demonstrated nontypical (noncanonical) functions of AIMPs, such as roles in apoptosis, inflammatory processes, DNA repair, and so on. However, these noncanonical functions of AIMPs have not been studied in peripheral nerves related to motor and sensory functions. Peripheral nerves include two types of structures: peripheral axons and Schwann cells. The myelin sheath formed by Schwann cells produces saltatory conduction, and these rapid electrical signals control motor and sensory functioning in the service of survival in mammals. Schwann cells play roles not only in myelin sheath formation but also as modulators of nerve degeneration and regeneration. Therefore, it is important to identify the main functions of Schwann cells in peripheral nerves. Here, using immunofluorescence technique, we demonstrated that AIMPs are essential morphological indicators of peripheral nerve degeneration, and their actions are limited to peripheral nerves and not the dorsal root ganglion and the ventral horn of the spinal cord.

Han Seo, Hyun-Chae Lee, Ki Chul Lee, Doosik Kim, Jiwook Kim, Donghee Kang, Hyung-Joo Chung, Hee-Jae Cha, Jeongtae Kim, and Kyoung Seob Song. Mol. Cells 2023;46:700-9. https://doi.org/10.14348/molcells.2023.0107

Ki-Hoon Park, Youngbuhm Huh, Hyung-Joo Chung, Hiroyuki Konishi, Junyang Jung, Na Young Jeong. Anat Cell Biol -0001;0:. https://doi.org/10.5115/acb.24.290