Positional relationships between a tracheal diverticulum and the tracheal tube under general anesthesia: a single-center observational and simulation study.

BACKGROUND: Incomplete sealing of tracheal diverticula by a tracheal tube cuff during positive-pressure ventilation causes barotrauma but the concrete possibility of incomplete sealing has not been indicated. We aimed to assess the possibility of incomplete sealing in a simulated situation of tracheal intubation for patients with tracheal diverticula with tube fixation where the tracheal tube's vocal cord guide overlaps with the patient's vocal cord. METHODS: We retrospectively assessed the characteristics of tracheal diverticula based on thoracic computed tomography data in our institution from January 2018 to July 2020. Then, we assessed the structural parameters of three single-lumen tracheal tubes (Parker Flex-Tip [Parker Medical, Bridgewater, CT, USA], Portex Soft Seal [ICU Medical, San Clemente, CA, USA], and Shiley TaperGuard [Medtronic, Dublin, Ireland]; 6.0-8.0 mm inner diameter size) and simulated the positional relationships between tracheal diverticula and the tracheal tube during tracheal intubation where the vocal cord guide overlaps with the patient's vocal cord. We assessed each tube product's possibility of incompletely sealing tracheal diverticula and the possibility of unintended bronchial intubation. RESULTS: In 5,854 patients, the prevalence of tracheal diverticula was 5.7%. The mean (SD) length from the vocal cord to the distal end of the tracheal diverticula was 52.2 (12.8) mm. Tracheal tubes with length from the distal end of the tracheal cuff to the vocal cord guide of ≥ 70 mm had a low risk of incompletely sealing tracheal diverticula (< 5%) and length from the distal end of the tube to the vocal cord guide of ≤ 95 mm had a low risk of unintended bronchial intubation (< 5%). No products in this study satisfied both outcomes. CONCLUSIONS: Tube fixation, where the vocal cord guide overlaps with the patient's vocal cord, is associated with risk of incompletely sealing of tracheal diverticula depending on the tube's manufacturer and tube's inner diameter size, although it was not a high risk. The use of small inner diameter sized tube relative to patient's body size is high risk of incomplete sealing of tracheal diverticula. TRIAL REGISTRATION: This trial was prospectively registered at University Hospital Medical Information Network (UMIN). CLINICAL TRIAL NUMBER AND REGISTRY URL: UMIN000043317 (URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000048055 ).

Disruption of mitochondria is an early event during dolichyl monophosphate-induced apoptosis in U937 cells.

Dolichyl monophosphate (Dol-P) is involved in the attachment of carbohydrate chains to proteins in the formation of N-linked glycoprotein. We found that this compound induces apoptosis in human leukemia U937 cells. During this apoptotic execution, the increase of plasma membrane fluidity (5-20 min), reduction in mitochondrial transmembrane potential (delta psi m) and translocation of apoptosis-inducing factor (1-3 hr), caspase-3-like protease activation (2-4 hr), chromatin condensation and DNA ladder formation (3-4 hr) were observed successively. In this study, we examined mitochondrial morphological changes by electron microscopy and delta psi m by JC-1 from immediately after treatment of Dol-P. After 5 min of treatment, we observed clearly that mitochondrial cristae began to be disrupted ultrastructurally and almost all the cristae were disintegrated after 1 hr of treatment. The delta psi m of Dol-P treated cells was reduced to 34% as compared with that of control cells immediately after treatment and was quartered within 1 hr. The reduction in delta psi m was not inhibited by cyclosporin A, N-acetyl-L-cysteine and vitamin E. These results indicate that mitochondrial disruption is one of the first triggering events of Dol-P-induced apoptosis.

Mutation frequency of plasmid DNA and Escherichia coli following long-term space flight on Mir.

To elucidate the biological influence of space radiation, we studied the effects of long-term space flight on mutation of the bacterial ribosomal protein L gene (rpsL). We prepared dried samples of plasmid DNA and repair-deficient and wild type cells of Escherichia (E.) coli. After a 40-day space flight on board the Russian space station Mir, the mutation frequencies of the rpsL gene were estimated by transformation of E. coli and by assessment of conversion of rpsL wild type phenotype (SmS) to its mutant phenotype (SmR). The experimental findings indicate that mutation frequencies of space samples were not significantly different from those of ground control samples in plasmid DNA and both E. coli strains. It may suggest that space radiation did not influence mutation frequency.