Effects of pulmonary stretch reflex on lung injury in rabbits with acute respiratory distress syndrome

BACKGROUND： Pulmonary stretch reflex plays an important role in regulation of respiratorymovement. This study aimed to evaluate the effect of pulmonary stretch reflex on lung injury inrabbits with acute respiratory distress syndrome （ARDS）.METHODS： ARDS rabbits were given intratracheal infusion of hydrochloric acid and ventilatedwith neurally adjusted ventilatory assistance （NAVA） with a tidal volume （VT） of 6 mL/kg and theelectrical activity of diaphragm （EAdi）-determined positive end expiratory pressure. After isolation ofthe bilateral vagus nerve trunk, the rabbits were randomized into two groups： sham operation （SHAM）group （n=5） and bilateral vagotomy （VAG） group （n=5）. Gas exchange and respiratory mechanicswere detected at baseline, after lung injury and 1, 2, and 3 hours after ventilation respectively.Pulmonary permeability index, pathological changes and infl ammatory response were also measured.RESULTS： Compared with the SHAM group, PaO2/FiO2 in the VAG group decreased signifi cantly2 and 3 hours after ventilation （P〈0.05）. There was no significant difference in PaCO2 betweenthe SHAM and VAG groups （P〉0.05）, and the VAG group had a high VT, peak pressure （Ppeak）,and mean pressure （Pm） compared with the SHAM group 1, 2, 3 hours after ventilation （P〈0.05）.Compared to the SHAM group, dead space fraction （VD/VT） and respiratory system elastance （Ers）in the VAG group increased （P〈0.05） and static pulmonary compliance （Cst） decreased markedly（P〈0.05） after ventilation for 3 hours. Lung wet/dry weight ratio （W/D） （8.4±1.2 vs. 6.6±1.0）, lung injuryscore （6.3±1.8 vs. 3.8±1.3）, tumor necrosis factor-# （TNF-#） （779±372 pg/mL vs. 355±130 pg/mL）and interleukin-8 （IL-8） （169±21 pg/mL vs. 118±17 pg/mL） increased significantly in the VAG groupcompared with the SHAM group （P〈0.05）.CONCLUSION： Lung injury is aggravated after bilateral vagotomy, demonstrating thatpulmonary stretch refl ex may have protective effect on the lung.

Dexmedetomidine attenuates inflammation and pancreatic injury in a rat model of experimental severe acute pancreatitis via cholinergic anti-inflammatory pathway

Background:Excessive inflammatory responses play a critical role in the development of severe acute pancreatitis(SAP),and controlling such inflammation is vital for managing this often fatal disease.Dexmedetomidine has been reported to possess protective properties in inflammatory diseases.Therefore,this study aimed to investigate whether dexmedetomidine pre-treatment exerts an anti-inflammatory effect in rats with SAP induced by sodium taurocholate,and if so,to determine the potential mechanism.Methods:SAP was induced with sodium taurocholate.Rats received an intraperitoneal injection of dexmedetomidine 30 min before sodium taurocholate administration.α-bungarotoxin,a selective alpha-7 nicotinic acetylcholine receptor(α7nAchR)antagonist,was injected intra-peritoneally 30 min before dexmedetomidine administration.The role of the vagus nerve was evaluated by performing unilateral cervical vagotomy before the administration of dexmedetomidine.Efferent discharge of the vagal nerve was recorded by the BL-420F Data Acquisition&Analysis System.Six hours after onset,serum pro-inflammatory cytokine(tumor necrosis factorα[TNF-α]and interleukin 6[IL-6])levels and amylase levels were determined using an enzyme-linked immunosorbent assay and an automated biochemical analyzer,respectively.Histopathological changes in the pancreas were observed after hematoxylin and eosin staining and scored according to Schmidt criteria.Results:Pre-treatment with dexmedetomidine significantly decreased serum levels of TNF-α,IL-6,and amylase,strongly alleviating pathological pancreatic injury in the rat model of SAP(TNF-α:174.2±30.2 vs.256.1±42.4 pg/ml;IL-6:293.3±46.8 vs.421.7±48.3 pg/ml;amylase:2102.3±165.3 vs.3186.4±245.2 U/L).However,the anti-inflammatory and pancreatic protective effects were abolished after vagotomy or pre-administration ofα-bungarotoxin.Dexmedetomidine also significantly increased the discharge frequency and amplitude of the cervical vagus nerve in the SAP rat model(discharge frequency:456.8±50.3 vs.332.4±25.1 Hz;discharge amplitude:33.4±5.3 vs.20.5±2.9μV).Conclusions:Dexmedetomidine administration attenuated the systemic inflammatory response and local pancreatic injury caused by SAP in rats through the cholinergic anti-inflammatory pathway involving vagus-andα7nAChR-dependent mechanisms.

Henoch-Schonlein Purpura： A Rare Cause of Recurrent Acute Pancreatitis

To the Editor：Henoch-Schonlein purpura （HSP） is a generalized vasculitis that can cause a large variety of symptoms in different organs.[1,2] It usually presents as acute-onset palpable purpura mainly located on the lower extremities.Acute pancreatitis （AP） is a potentially life-threatening inflammatory disorder and rarely presents as a complication of HSP.AP secondary to HSP is extremely rare,[3] and it is even rarer as an initial presenting feature of HSP before the occurrence of characteristic palpable purpura.We herein described a patient whose underlying HSP became clinically apparent after the development of AP.To the best of our knowledge,this is a very rare report of recurrent AP induced by HSP.

Acute Pancreatitis as a Long-term Complication of Pancreatectomy

To the Editor： Acute pancreatitis （AP） is a common digestive disorder with a broad spectrum of etiologies, Apart from gallstones and alcohol abuse which are two of most common etiologies of AP, all of other potential causes need to be considered. Pancreatectomy is the surgical removal of all or part of the pancreas, which includes pancreaticoduodenectomy （PD）, distal pancreatectomy, segmental pancreatectomy, and total pancreatectomy.