Objective To determine the effective target plasma propofol concentration required to prevent the response to fibercolonoscope examination in 50% of patients (EC50) .Methods Sixty ASA Ⅰ or Ⅱ patients aged 18-60 yrs weighing 45-70 kg undergoing fibercolonoscope examination were enrolled in this study. The initial target plasma propofol concentration was set at 5.0 ?g?ml-1 . EC50 was determined by up-and-down sequential experiment. The effect of TCI of propofol was based on the movement on the movement of the body in response to fibercolonoscope examination. If effective the target plasma propofol concentration was set at a lower concentration in the next patient and vice sersa. Each time the target plasma propofol concentration increased/decreased by 0.5 ?g?ml-1. The up-and-down sequences were analyzed by using the Dixon and Massey method to determine the EC50.Results The EC50 of propofol for fibercolonoscope examination was 4.9 ?g?ml-1 [95% confidence interval (CI) 4.5-5.4 ?g?ml-1] . Four patients developed respiratory depression during examination (6.67%). Conclusion The EC50 of propofol for fibercolonoscope examination is 4.9 ?g?ml-1.

Objective To evaluate effects of ropivacaine combined with different concentrations of fentanyl for epidural labor analgesia. Methods In this multicenter double-blinded randomized study 128 parturients at full term and 2-3 cm of cervical dilatation who requested epidural analgesia were randomly allocated to one of 4 groups: group F0 received epidural ropivacaine alone (n = 33); group F1 received epidural ropivacaine with fentanyl 1 ?g?ml-1 (n = 30) ; group F2 epidural ropivacaine + fentanyl 2?g?ml-1(n = 33) and group F3 epidural ropivacaine + fentanyl 3 ?g?ml-1(n = 32). Epidural catheter was placed at L2,3 and advanced 4 cm into the epidural space in cephalad direction. A bolus of 15 ml of ropivacaine alone or with fentanyl was given after correct epidural placement was confirmed. EC50 of epidural ropivacaine was determined by up-and-down sequential experiment. The initial concentration of epidural ropivacaine was 0. 12% . If effective the next parturient received ropivacaine of lower concentration; if ineffective the ropivacaine concentration was increased. Each time the concentration of epidural ropivacaine increased/decreased by 0.01% . The analgesia was assessed using VAS score (0-10 0 = no pain, 10 = worst pain) . If VAS score was less than 3 within 30 min of ropivacaine administration, analgesia was defined as effective. EC50 of ropivacaine was calculated according to Dixon and Massey. Results Four of the 128 parturients enrolled were excluded because of uncertain results of interrupted observation. The EC50 of epidural ropivacaine for labor analgesia and the 95% confidence interval (95% CI) of EC50 were 0.110% (95% CI 0.109 0%-0.111 6%) in group F0; 0.089% (95% CI 0.087 7%-0.091 1%) in group F1; 0.073% (95% CI 0. 071 7%-0.0744%) in group F2 and 0.060% (95% CI 0.056 0%-0.634%) in group F3 respectively. The EC50 was significantly higher in group F0 than in group F1, F2 and F3 (P0.05) . The incidence of side-effect was significantly higher in group F3 than in group F0(P

Parkinson′s disease (PD) is the common progressive neurodegenerative disorder affecting older adults. Alterations of the circadian system occur in PD patients. However, the molecular mechanisms and pathophysiological process remain elusive. Circadian rhythm is modulated by both internal and external factors and using bright light and melatonin as chronotherapeutic tools may be potential therapies to improve symptoms of PD in the future. This article reviewed the abnormal changes of circadian parameters in clinical symptoms of PD and the possible mechanisms of circadian rhythm to provide basis for exploring the therapeutic strategies of circadian rhythm in PD.