Objective To establish a HPLC method for the determination of strychnine content in Cidan Capsules. Methods Using Hypersil- C18 as the column and 1 % Acetic acid-acetonitrile (88 ∶ 12) as the mobile phase, HPLC was performed. The detection wavelength was 254 nm. Results The linear range was 0.112～ 0.560 ? g(r=0.999 9). The average recovery rate was 97.36 % , RSD was 1.00 % ( n=5) . Conclusion This method is accurate and specific.

BACKGROUND:Previous studies have performed three-dimensional finite element analysis on lumbar fracture fixation. However, a few studies concerned three-dimensional finite element analysis of lumbar spinal pedicle screw fixation.
OBJECTIVE:To analyze the biomechanical characteristics of one-way screw and universal screw fixation for lumbar fractures using finite element method.
METHODS:Models of lumbar fractures treated with one-way screw and universal screw fixation were established. Three-dimensional finite element method was used to analyze and compare the maximum axial displacement, maximum bending degree, maximum stress on thepedicle screw fixation system and maximum stress of intervertebral disc in normal vertebral fracture model, one-way and universal pedicle screw fixation models.
RESULTS AND CONCLUSION:(1) The maximum axial displacement at anteflexion, posterior extension, left lateral curvature and right lateral curvature was significantly lower in the one-way fixation group and universal fixation group than in the normal group (P< 0.05-0.01). The maximum axial displacement at above directions was lower in the universalfixation group than in the one-way fixation group. (2) The maximum bending degree was significantly lower in the one-way and universal fixation groups than in the normal group (P< 0.05-0.01). The maximum bending degree at various directions was lower in the universal fixation group than in the one-way fixation group. (3) The maximum stress on the pedicle screw fixation system at various directions was lower in the universal fixation group than in the one-way fixation group (P< 0.05-0.01). (4) The maximumstress of intervertebral disc was significantly lower in the one-way and universal fixation groups than in the normal group (P< 0.05-0.01). The maximum stress of intervertebral disc at various directions was lower in the universal fixation group than in the one-way fixation group. (5) Results suggested that one-way and universal screw fixation for lumbar fracture can bear most of the stress, obviously decrease the maximum axial displacement, maximum bending degree, maximum stress on the pedicle screw fixation system and maximum stress of intervertebral disc. The stability of universal screw fixation was better than that of one-way screw fixation.

Objective To explore the ultrasound characteristics of carotid atherosclerosis in acute stroke patients with early neurological deterioration (END). Methods END was defined as a increase by at least two points in the National Institutes of Health Stroke Scale between admission and day 7. Among 128 patients with acute stroke in whom carotid ultrasound examinations were performed within 24 hours after admission, 38 patients with END and 40risk-matched patients without END were included in the END group and the non-END group,respectively. The ultrasound characteristics of carotid atherosclerosis were compared in both groups. Results Plaque score (16.7 ±4.4 mm vs. 13.3 ±3.5 mm, t=2.673, P=0.009),intima-media cross-sectional area (26. 4 ± 8. 5 mm2 vs. 20. 5 ± 6. 8 mm2, t = 3. 394, P =0. 001), arterial stiffness index (28. 94 ±4. 29 vs. 21. 22 ±5. 85, t = 6. 618, P =0. 000), and the rates of unstable plaque (66. 7% υs. 43. 3%, χ2=9. 164, P =0. 003), eccentric plaque (62. 8% vs. 45. 6%, χ2=5. 008, P =0. 025), stenosis ≥50% (71. 1% vs. 37. 5%, χ2=8. 828, P =0. 003), and negative remodeling (28. 9% vs. 7. 5%, χ2=6.087, P =0.014) in the END group were significantly higher than those in the non-END group, while the distensibility coefficient ([14. 74 ±8. 66]×10-6/P υs. [19. 16 ±9.35] × 10-6/Pa, t =2. 163, P=0. 034)and compliance coefficient ([0.49 ±0. 13] × 10-4 mm2/Pa υs. [0. 58 ±0. 11] × 10-4 mm2/Pa,t =3.307, P =0. 001) were significantly lower than those in the non-END group. Conclusions The ultrasound characteristics such as plaque score, intima-media cross-sectional area, arterial stiffness index, unstable plaque, eccentric plaque, stenosis ≥ 50%, negative remodeling,distensibility and compliance may be useful to predict END in patients with acute stroke.