By designing the circuit structure of preamplifier and selecting new elements such as ultra low noise operational amplifier and linear opto-coupler,some difficulties in EEG acquisition is overcome and the Common Mode Rejection Ratio(CMRR) of preamplifier is highly increased.So EEG can be amplified and detected well.

AIM: To observe the effects of oxygen free radical (OFR) and captopril on the level of asymmetric NG, NG-dimethyl-L-arginine (ADMA) in human vascular endothelial cells (HUVECs).METHODS: HUVECs of 3-6 th passage, cultured with modified Jaffes' method, were used in the experiment and divided into three groups: (1)Cells cultured with equivalence of DMEM medium as control; (2)OFR intervention groups, OFR at concentrations of 0 01 mmol/L, or 0 1 mmol/L, respectively, were added to the cell culture; (3)Drug intervention groups: the cell culture was treated with 0 1 mmol/L of OFR combined with 50 mg/L or 100 mg/L of captopril, respectively. Concentrations of ADMA, L-arginine, nitric oxide(NO), endothelin(ET) and the activity of angiotensin-converting enzyme(ACE) in conditioned medium were measured after 24 h exposure. RESULTS: Concentrations of ADMA, ET and the activity of ACE were increased, while the amount of NO decreased in OFR intervention groups compared with control group. After treatment with captopril, ADMA, ET concentrations and the activity of ACE were decreased, while the amount of NO increased, but the level of L-arginine had no obvious change. CONCLUSIONS: OFR induces endothelial dysfunction through increasing ADMA concentration, while captopril relieves endothelial dysfunction induced by ox-LDL through decreasing ADMA concentration.

Objective To investigate the interventional treatment strategy for occluding the intercristal ventricular septal defect (VSD) in order to improve the surgical safety and success rate. Methods During the period from January 2012 to December 2013, a total of 31 patients with intercristal VSD were admitted to authors’ hospital to receive interventional catheter occlusion therapy. Preoperative color Doppler ultrasound echocardiography showed that on the short axis view of the aorta the VSD interrupted port was situated at 12:00 - 1:00 o’clock region. Left ventricular and above aortic valve angiography indicated that the VSD location, shape and size, the split vent size on the left ventricle side and its distance from the aortic valve could be correctly measured when the VSD shunt was visualized , which were very helpful in guiding the operator to select the suitable occluder as well as to adjust the release pattern of the occluder. Postoperative imaging findings of the left ventricular and above aortic valve angiography were compared with the preoperative ones. Results Successful occlusion of VSD was obtained in 22 patients , in 13 among them the left ventricular angiography showed that the direction of blood flow beam at the defect hole was from the left ventricle to the right ventricle in an obliquely upward direction. The basal width of the defect on the left ventricle side was (5.12 ± 1.38) mm, and(6 - 10) mm occluder was employed. In the remaining 9 patients the left ventricular angiography showed that the direction of blood flow beam at the defect hole was from the left ventricle to the right ventricle in a direction almost parallel to the aortic valve , and the basal width of the defect on the left ventricle side was (7.18 ± 1.26) mm, and (9 - 12) mm zero-bias occluder was adopted. Interventional occlusion of VSD was unsuccessful in 9 cases as the intercristal hole was rather larger, and two of them had coexisting aortic sinus aneurysm complicated by mid-to-severe degree aortic valve regurgitation. Conclusion Based on the precise analysis of angiographic images by experienced radiologists optimal treatment scheme can be worked out. If conditions permit, symmetrical occluder should be employed so far as possible in order to reduce the degree of operation difficulty and improve the surgical safety and the success rate as well.