BACKGROUND: Limb ischemia reperfusion (LIR) as a stressor leads to gastric mucosal injury, and then results in the occurrence of stress ulcer.OBJECTIVE: To observe the effects of LIR on gastric mucosal injury, investigate part of the mechanism, and the role of several transient limb ischemia in the occurrence of gastric mucosal injury.DESIGN: A randomized grouping design and controlled animal experiment.SETTING: Department of Pathophysiology of North China Coal Medical College.MATERIALS: The experiment was carried out in the pathophysiological laboratory of North China Coal Medical College from January to June 2002. Fifty-four healthy adult male Wistar rats were randomly divided into three groups with 18 rats in each group. Ischemia reperfusion (I/R) group: The rats were duplicated into models according to the Rosenthal method that under superficial anesthesia with ether, the roots of both hindlimbs were ligated by wrapping with rubber strap, blood flow was blocked for 4 hours and then recovered to perfusion for 4 hours, and finally killed by bleeding from abdominal aorta. Ischemic preconditioning group: Before model establishment, blood flow of both hindlimbs was blocked for 5 minutes, and then recovered to perfusion for 5 minutes, which was repeated for four times, and the following operations were the same as those in the I/R group. Control group: The operations were the same as those in the I/R group,but both hindlimbs were ligated at relaxation without blocking the blood flow.METHODS: Sections of gastric mucosa were prepared, and then observed under light microscope and electron microscope, and the index of gastric mucosal injury was determined according to the Guth standard. The colorimetric assay was performed with 721 spectrophotometer at 650 nm, and the amount of gastric combining mucus was calculated.Meanwhile, the blood flow of gastric mucosa, contents of phospholipid and hexosamine in gastric mucus, content of nitric oxide in plasma and gastric tissue and activity of nitric oxide synthase (NOS) in gastric mucosa were determined.MAIN OUTCOME MEASURES: Index of gastric mucosal injury, amount of gastric combining mucus, blood flow of gastric mucosa, contents of phospholipid and hexosamine in gastric mucus, contents of nitric oxide in plasma and gastric tissue and NOS activity in gastric mucosa.RESULTS: All the 54 rats were involved in the analysis of results. ① In the I/R group, gastric mucosal injury was serious, edema, hyperemia, erosion and disintegration of gland of mucosal glands were observed, infiltration of inflammatory cells (formation of ulcer) was observed in basal and inferior mucosa. In the ischemic preconditioning group, the gastric mucosa was complete, and the damaged severity was milder than that in the I/R group; Under electron microscope, the organell structures of gastric parietal and chief cells were incomplete and destroyed. The cell injuries in the ischemic preconditioning group were milder than those in the I/R group (index of injury: 18.00±10.71, 34.00±15.01, P＜ 0.01). ② The blood flow and combining mucosal amount of gastric mucosa, contents of phospholipid and hexosamine in gastric mucus in the ischemic preconditioning group and I/R group were all obviously lower than those in the control group [(2.12±0.56), (10.84±2.56), (25.52±2.97) mL/(kg·h); (2.01±0.91), (2.79±0.73), (3.99±0.87) mg;(7.68±1.95), (9.74±1.04), (11.98±1.98) mg/g; (3.83±1.18), (5.42±0.47), (5.76±1.21) mg/g, P ＜ 0.05, 0.01], those the above indexes were all higher in the ischemic preconditioning group than in the I/R group. ③ The contents of nitric oxide in plasma and gastric tissue and NOS activity in gastric mucosa in the ischemic preconditioning group and I/R group were significantly lower than those in the control group [(250.0±5.6), (270.0±11.3), (210.0±7.4) μmol/L; (9.34±0.67), (11.34±1.00), (7.50±0.67) μ kat/g, P ＜ 0.01], those were also signficantly higher in the ischemic preconditioning group than in the I/R group.CONCLUSION: As a stressor, LIR can lead to gastric mucosal injury, and cause stress ulcer.Ischemic preconditioning can alleviate the gastric mucosal injury following LIR

AIM: To observe the degree of gastric mucosal injury following limb ischemia/reperfusion(LIR),and to investigate the mechanism of gastric mucosal injury and the influence of the series of brief ischemia/reperfusion of hind limbs of rats on gastric mucosal injury. METHODS: Referring to Rosenthal's method, the model rats which underwent 4 hours of ischemia and 4 hours of reperfusion in hind limbs were made. The indexes of gastric mucosal injury after LIR and ischemic preconditioning (IPC) + LIR were determined. The morphologic changes were observed with light microscope and transmission electron microscop respectively. The GMBF,histologic lesion score, gastric barrier mucus, phospholipids, hexosamine, nitric oxide and nitric oxide synthase in mucus were measured in different groups. RESULTS: Serious damage in gastric mucosa was observed under microscope and EM after LIR. But less serious damage was observed in the IPC group. After LIR, compared to the control group, the GMBF and the content of gastric barrier mucus, phospholipids and hexosamine in mucus decreased significantly. There was significant difference in most indexes between the control group and the IPC group, but compared to LIR group, the histologic lesion score decreased significantly and the GMBF and the content of gastric barrier mucus, phospholipids, hexosamine ,nitric oxide and nitric oxide synthase in mucus increased significantly. CONCLUSION: LIR caused the gastric mucosa injury. IPC alleviated the damage of gastric mucosa following ischemia/reperfusion in hind limbs.

Closed-loop transcranial ultrasound stimulation technology is based on real-time feedback signals, and has the potential for precise regulation of neural activity. In this paper, firstly the local field potential (LFP) and electromyogram (EMG) signals of mice under different intensities of ultrasound stimulation were recorded, then the mathematical model of ultrasound intensity and mouse LFP peak/EMG mean was established offline based on the data, and the closed-loop control system of LFP peak and EMG mean based on PID neural network control algorithm was simulated and built to realize closed-loop control of LFP peak and EMG mean of mice. In addition, using the generalized minimum variance control algorithm, the closed-loop control of theta oscillation power was realized. There was no significant difference between the LFP peak, EMG mean and theta power under closed-loop ultrasound control and the given value, indicating a significant control effect on the LFP peak, EMG mean and theta power of mice. Transcranial ultrasound stimulation based on closed-loop control algorithms provides a direct tool for precise modulation of electrophysiological signals in mice.
Mice ; Animals ; Deep Brain Stimulation ; Algorithms ; Electromyography