Effect of facemask oxygenation with and without positive pressure ventilation on gastric volume during anesthesia induction in patients undergoing laparoscopic cholecystectomy or partial hepatectomy: a randomized controlled trial.

BACKGROUND: Studies focusing on the relationship between gastric volume and facemask oxygenation without ventilation during apnea in anesthesia induction are scarce. This study compared the change in gastric volume during apnea in anesthesia induction using facemask ventilation and facemask oxygenation without ventilation in adults undergoing laparoscopic surgery. METHODS: In this prospective, randomized, double-blinded trial, 70 adults undergoing laparoscopic surgery under general anesthesia were divided into two groups to receive facemask oxygenation with and without ventilation for 60 seconds after loss of consciousness. Before anesthesia induction and after endotracheal intubation, the gastric antral cross-sectional area was measured with ultrasound imaging. Arterial blood gases were tested at baseline (T1), after preoxygenation (T2), after loss of consciousness (T3), and before and after endotracheal intubation (T4 and T5, respectively). RESULTS: Sixty patients were included (ventilation n = 30; non ventilation n = 30, 10 patients were excluded). The median [IQR] change of gastric antral cross-sectional area in ventilation group was significantly higher than in non ventilation group (0.83 [0.20 to 1.54] vs. 0.10 [- 0.11 to 0.56] cm2, P = 0.001). At T4 and T5, the PaO2 in ventilation group was significantly higher than in non ventilation group (T4: 391.83 ± 61.53 vs. 336.23 ± 74.99 mmHg, P < 0.01; T5: 364.00 ± 58.65 vs. 297.13 ± 86.95 mmHg, P < 0.01), while the PaCO2 in non ventilation group was significantly higher (T4: 46.57 ± 5.78 vs. 37.27 ± 6.10 mmHg, P < 0.01; T5: 48.77 ± 6.59 vs. 42.63 ± 6.03 mmHg, P < 0.01) and the pH value in non ventilation group was significantly lower (T4: 7.35 ± 0.029 vs 7.42 ± 0.047, P < 0.01; T5: 7.34 ± 0.033 vs 7.39 ± 0.044, P < 0.01). At T4, the HCO3- in non ventilation group was significantly higher (25.79 ± 2.36 vs. 23.98 ± 2.18 mmol l- 1, P < 0.01). CONCLUSIONS: During apnoea, the increase in gastric volume was milder in patients undergoing facemask oxygenation without ventilation than with positive pressure ventilation. TRIAL REGISTRATION: ChiCTR2100054193, 10/12/2021, Title: "Effect of positive pressure and non-positive pressure ventilation on gastric volume during induction of general anesthesia in laparoscopic surgery: a randomized controlled trial". Website: https://www.chictr.ogr.cn .

Apocynin protects endothelial cells from endoplasmic reticulum stress-induced apoptosis via IRE1α engagement.

Endoplasmic reticulum (ER) stress-induced endothelial cell (EC) apoptosis has been implicated in a variety of human diseases. In addition to being regarded as an NADPH oxidase (NOX) inhibitor, apocynin (APO) exhibits an anti-apoptotic effect in various cells. The present study aimed to identify the protective role of apocynin in ER stress-mediated EC apoptosis and the underlying mechanisms. We found that ER stress resulted in a significant increase in c-Jun N-terminal kinase phosphorylation, and elicited caspase 3 cleavage and apoptosis. However, apocynin obviously attenuated EC apoptosis and this effect was partly dependent on ER stress sensor inositol-requiring enzyme 1α (IRE1α). Importantly, apocynin upregulated IRE1α expression in both protein and mRNA levels and promoted the pro-survival XBP1 splicing. Our results suggest that apocynin protects ECs against ER stress-induced apoptosis via IRE1α involvement. These findings may provide a novel mechanistic explanation for the anti-apoptotic effect of apocynin in ER stress.

IRE1α Signaling Pathways Involved in Mammalian Cell Fate Determination.

A diverse array of cellular stresses can lead to accumulation of misfolded or unfolded proteins in endoplasmic reticulum (ER), which subsequently elicits ER stress. Inositol-requiring enzyme 1α (IRE1α) is the most sensitive of the three unfolded protein response (UPR) branches which are triggered to cope with ER stress in mammalian cells. IRE1α signaling is quite context-specific on account of many adaptor and modulator proteins that directly interact with it, including heat shock proteins (HSPs), RING finger protein 13 (RNF13), poly (ADP-ribose) polymerase 16 (PARP16), Bax/Bak, and Bax inhibitor-1 (BI-1). The activated IRE1α triggers different downstream pathways depending on the UPRosome formed by distinct modulator proteins. At the initial phase of ER stress, IRE1α-XBP1 axis functions as an adaptive response. While ER stress sustains or intensifies, signals shift to apoptotic responses. Furthermore, IRE1α signaling can be exploited to the development of a wide range of prevalent human diseases, with cancer the most characterized. Here we provide an overview of recent insights into the complex IRE1α signaling network which makes IRE1α an intriguing cell fate switch. Besides, the functional relevance is presented since IRE1α activation also participates in some other physiological processes beyond protein-folding status.