Comparison of blast lung injury in infant and adult rabbits

Impact of acute stress disorder on surfactant protein D levels in acute lung injury

Many people sustain acute lung injuries in road traffic collisions, but few studies have dealt with such injuries in live models. This study aimed to explore the basic pathophysiological and inflammatory changes in adult rabbits following acute thoracic trauma. We randomly assigned 50 rabbits to control and injury groups. Rabbits in the injury group were subjected to right chest pressure (2600 g) using a Hopkinson bar. Measurements were taken in the control group and 0, 24, 48, and 72 h after injury in the injury group. Injury severity was evaluated in gross view; with haematoxylin and eosin (H&E) staining; and through the serum changes of tumor necrosis factor alpha (TNF-α), surfactant protein D (SP-D), and neutrophils. Secretion changes in SP-D in right lung injured tissues were estimated by western blotting and qPCR. Serum TNF-α levels increased rapidly immediately after injury, gradually recovering after 24, 48, and 72 h (p < 0.01). The percentage of neutrophils in the accompanying blood showed a consistent trend. Gross necropsy and H&E staining indicated different levels of bleeding, alveoli exudation, and inflammatory transformation after impact. ELISA depicted the same trend in circulation (F = 22.902, p < 0.01). Western blotting showed that SP-D protein levels in tissues decreased at 0 h and increased at 24, 48, and 72 h. We demonstrate the feasibility of a model of impact lung injury. Primary impact caused injury without external signs. Inflammation began immediately, and the lungs began recovering at 24, 48, and 72 h, as shown by increased SP-D levels in circulation and tissues.With complaints of ALI and inflammation, SP-D may be a potential biomarker after chest trauma.

Pathophysiological changes and injury markers for acute lung injury from blunt impact in infant rabbits

Background

Traffic accidents, particularly blunt impacts, cause serious injuries in children. We aimed to assess inflammatory and injury responses in infant rabbits subjected to acute lung injury resulting from blunt impact, with the goal of identifying potential circulatory injury markers.

Methods

Forty 4-week-old infant rabbits were subjected to a right chest impact using a Hopkinson bar with 2,600 g. Computed tomography was employed to assess injury severity. Pathological changes were observed using hematoxylin and eosin staining in the control, 0, 24, and 72 h groups, post-injury. Immunohistochemistry was used to examine surfactant protein A (SP-A) changes in right lung tissues and upper main bronchi. Serum levels of interleukin-6 (IL-6), IL-8, and SP-A were measured using ELISA within 24 h post-injury in the control, 0 h, and 24 h groups.

Results

Following blunt injury, significant increases were observed in blood white blood cell count (F = 101.556, P < 0.01) and neutrophil percentage (F = 104.228, P < 0.01), which gradually decreased after 24 and 72 h. The lung wet/dry weight ratio indicated significant edema (F = 79.677, P < 0.01), corroborated by hematoxylin and eosin staining showing edema, exudation, and marked granulocyte infiltration in the control, 0 h, 24 h and 72 h groups. SP-A levels decreased rapidly at 0 h, and recovered between 24 and 72 h in the right lung tissues (F = 6.7, P < 0.05), left lung (F = 15.825, P < 0.05) and upper main bronchi (F = 59.552, P < 0.01). The ELISA results showed increasing trends for the control and 0 h groups, while decreasing trends were observed in 24 h group for IL-6 (F = 58.328, P < 0.01) and IL-8 (F = 41.802, P < 0.01). Conversely, SP-A exhibited a decreasing trend in the control and 0 h groups but increased in the serum of 24 h group (F = 52.629, P < 0.01).

Discussion

In cases of direct chest trauma in infant rabbits, particularly mild injuries without rib fractures. SP-A levels correlated with pathological changes across all groups and may serve as biomarkers for pediatric blunt lung impact.

Esophageal pressure monitoring and its clinical significance in severe blast lung injury

Background

The incidence of blast lung injury (BLI) has been escalating annually due to military conflicts and industrial accidents. Currently, research into these injuries predominantly uses animal models. Despite the availability of various models, there remains a scarcity of studies focused on monitoring respiratory mechanics post-BLI. Consequently, our objective was to develop a model for monitoring esophageal pressure (Pes) following BLI using a biological shock tube (BST), aimed at providing immediate and precise monitoring of respiratory mechanics parameters post-injury.

Methods

Six pigs were subjected to BLI using a BST, during which Pes was monitored. We assessed vital signs; conducted blood gas analysis, hemodynamics evaluations, and lung ultrasound; and measured respiratory mechanics before and after the inflicted injury. Furthermore, the gross anatomy of the lungs 3 h post-injury was examined, and hematoxylin and eosin staining was conducted on the injured lung tissues for further analysis.

Results

The pressure in the experimental section of the BST reached 402.52 ± 17.95 KPa, with a peak pressure duration of 53.22 ± 1.69 ms. All six pigs exhibited an anatomical lung injury score ≥3, and pathology revealed classic signs of severe BLI. Post-injury vital signs showed an increase in HR and SI, along with a decrease in MAP (p < 0.05). Blood gas analyses indicated elevated levels of Lac, CO2-GAP, A-aDO2, HB, and HCT and reduced levels of DO2, OI, SaO2, and OER (p < 0.05). Hemodynamics and lung ultrasonography findings showed increased ELWI, PVPI, SVRI, and lung ultrasonography scores and decreased CI, SVI, GEDI, and ITBI (p < 0.05). Analysis of respiratory mechanics revealed increased Ppeak, Pplat, Driving P, MAP, PEF, Ri, lung elastance, MP, Ptp, Ppeak - Pplat, and ΔPes, while Cdyn, Cstat, and time constant were reduced (p < 0.05).

Conclusion

We have successfully developed a novel respiratory mechanics monitoring model for severe BLI. This model is reliable, repeatable, stable, effective, and user-friendly. Pes monitoring offers a non-invasive and straightforward alternative to blood gas analysis, facilitating early clinical decision-making. Our animal study lays the groundwork for the early diagnosis and management of severe BLI in clinical settings.

The impact of acute stress disorder on gallbladder interstitial cells of Cajal

Physical and psychological stress exerts a substantial effect on gastrointestinal motility disorders, where trauma enhances symptoms of digestive dysfunction. Interstitial cells of Cajal (ICCs) act as pacemakers for gastrointestinal motility regulation and are likely important in stress-associated gastrointestinal motility disorders. This study explored the mechanisms underlying gallbladder ICCs function under acute stress conditions using a rabbit chest puncture and cholecystectomy model. The stem cell factor (SCF)/c-kit pathway is essential for the development of ICCs, and gene expression was investigated to identify stress-induced transcriptional alterations. Immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling assays were used to determine ICCs apoptosis, whereas western blot analysis and reverse-transcription polymerase chain reaction were used to detect changes in the SCF/c-kit signaling pathway. These methods revealed a reduction in ICCs via apoptosis following stress, and ICCs increased over time after stressor removal. Therefore, this study demonstrates the impact of stress on ICCs development and survival and further confirms the link between stress and gastrointestinal motility.