To compare the effects of upper limb remote ischemic preconditioning (RIPC) with different pressure modes on enhancing high-altitude acclimatization in healthy adult males rapidly exposed to high-altitude environments.

In May 2024, 86 male adult residents living plain areas planning a high-altitude travel were recruited through advertisements in Chongqing by Department of Anesthesiology at the Second Affiliated Hospital of Army Medical University. The participants were randomly divided into a variable pressure training group (n=29), a constant pressure training group (n=29), and a control group (n=28). The variable pressure training group underwent RIPC training in a variable pressure mode [occlusion pressure was set at systolic blood pressure (SBP) + 40 mmHg], while the constant pressure training group received RIPC training in a constant pressure mode (fixed occlusion pressure of 200 mmHg). Both groups completed a bilateral upper limb RIPC training (twice daily, 5 cycles per time of 10-min occlusion followed by 5-min reperfusion) for 14 d. The control group received no such training. On the 3rd day post-training, all participants entered a simulated 4 500 m altitude chamber for 7 h. The incidence and severity of acute mountain sickness (AMS) were observed and evaluated, and the vital signs and cerebral tissue oxygenation index (CTOI) were recorded.

The incidence of AMS was 23.1% in the variable pressure training group (RR=0.4, 95%CI: 0.2~0.8, Chi-square=9.433, P=0.002) and 16.0% in the constant pressure training group (RR=0.2, 95%CI: 0.1~0.6, Chi-square=12.833, P<0.001), and both incidences were significantly lower than that in the control group (65.4%). The AMS symptom score in the variable pressure training group [1.5 (0.8, 3.0) vs (3.1±1.9), P=0.018] and the score in the constant pressure training group [1.0 (1.0, 2.0) vs (3.1±1.9), P=0.001] were significantly lower than that in the control group. The dizziness score was obviously lower in the variable pressure training group [0 (0, 1.0) vs 1.0 (1.0, 1.0), P=0.001] and the constant pressure training group [1.0 (0,1.0) vs 1.0 (1.0,1.0), P=0.003] than the control group, so was the fatigue/weakness score in the variable pressure training group [0 (0, 0.3) vs 1.0 (0,1.0), P=0.006], the constant pressure training group [0 vs 1.0(0, 1.0), P<0.001], and the control group. The change of CTOI (ΔCTOI) in the variable pressure training group (P=0.010) and the constant pressure training group (P= 0.042) was significantly lower than that in the control group. There were no statistical differences in the 3 groups in terms of SpO₂, HR, SBP or DBP (P>0.05). What’s more, no significant differences were observed in the incidence of AMS, AMS score, dizziness score, fatigue/weakness score, or ΔCTOI between the variable pressure training group and the constant pressure training group (P>0.05).

Both upper limb RIPC protocols, variable-pressure (SBP+40 mmHg) and fixed-pressure (200 mmHg), can effectively enhance high-altitude acclimatization by reducing AMS incidence, symptom severity, and cerebral oxygen desaturation.

To analyze the incidence and related risk factors of postoperative pneumonia (POP) in patients with acute type A aortic dissection(ATAAD) after surgery.

A multi-hospital retrospective cohort study was conducted, consecutively enrolling 493 ATAAD patients who underwent surgical treatment at the Second Affiliated Hospital of Army Medical University, Affiliated Hospital of Southwest Medical University, and Chongqing Emergency Medical Center between January 2018 and December 2022. Clinical data were collected, including general characteristics, preoperative comorbidities, surgical indicators, and postoperative monitoring parameters. The participants were divided into a POP group (n=138) and a control group (n=355) based on POP occurrence. Univariate analysis was used to screen the risk variables related to the occurrence of POP(P<0.15), followed by multivariate logistic regression using forward, backward, and enter methods to identify the independent risk factors. Receiver operating characteristic(ROC) curve analysis was used to assess the predictive efficacy of continuous variables and determine optimal cut-off values.

Among the 493 patients, the incidence of POP was 28.0%(138/ 493). The POP group exhibited significantly prolonged postoperative mechanical ventilation time(92.6±68.5 vs 45.3±32.8 h, P<0.001), length of intensive care unit(ICU) stay(156.8±88.3 vs 102.5±65.7 h, P<0.001), and length of total hospitalization stay(27.3±14.6 vs 19.8±10.2 d, P<0.001), along with significantly higher in-hospital mortality(18.8% vs 7.9%, P<0.001) when compared with the control group. Multivariate logistic regression analysis identified preoperative chronic obstructive pulmonary disease(COPD)(OR=2.447, 95%CI: 1.191 to 5.026, P=0.015), history of aspiration pneumonia(OR=2.282, 95%CI: 0.992 to 5.246, P=0.052), mechanical ventilation duration ≥68 h(OR=3.619, 95%CI: 1.963 to 6.672, P<0.001), red blood cell transfusion volume≥10 U(OR=1.984, 95%CI: 1.113 to 3.536, P=0.020), intraoperative peak blood glucose ≥11 mmol/L(OR=2.134, 95%CI: 1.190 to 3.826, P=0.011), and postoperative 24 h total drainage ≥ 1100 mL(OR=1.808, 95%CI: 1.032 to 3.169, P=0.039) as independent risk factors for POP in ATAAD patients. ROC curve analysis further validated the predictive efficacy of these continuous variables, with mechanical ventilation duration demonstrating an AUC value of 0.762(95%CI: 0.718 to 0.806), red blood cell transfusion a value of 0.682(95%CI: 0.632 to 0.732), intraoperative peak blood glucose a value of 0.658 (95%CI: 0.606 to 0.710), and postoperative 24 h drainage a value of 0.642(95%CI: 0.589 to 0.695).

The incidence of POP in ATAAD patients is as high as 28.0%, significantly increasing the mortality and hospital stay. Individualized preventive strategies targeting preoperative COPD, aspiration pneumonia history, prolonged mechanical ventilation, massive red blood cell transfusion, intraoperative hyperglycemia, and early postoperative high-volume drainage may reduce the incidence of POP and improve the prognosis of patients.

To investigate the intrinsic neural mechanism of aggressive behavior in CD1 mice.

CD1 mice with aggressive behavior were screened out by resident intruder test. After the aggressive conditioned pair preference was further verified, the activated brain regions of the whole brain were labeled with c-Fos, and the types of neurons activated by the aggressive behavior were analyzed by double immunofluorescence labeling. Finally, the effects of activity of these neurons regulated by optogenetics on aggressive behavior were observed.

The c-Fos screening revealed that about 82% of the CD1 mice showed aggressive behavior. After the occurrence of aggressive behavior, the main activation occured in the medial prefrontal cortex (mPFC), and the results of immunofluorescence double labeling showed that the c-Fos positive neurons in the mPFC were mainly glutamatergic neurons. Finally, glutamatergic neurons in the mPFC could be activated by optogenetics, and the activation inhibited the aggressive behavior of CD1 mice. In contrast, optogenetics could inhibit glutamatergic neurons in the mPFC and then promote the aggressive behavior of CD1 mice.

Glutamatergic neurons in the mPFC are an important component in the regulation of aggressive behavior in CD1 mice.