Purpose: Controlling the cerebral and systemic hemodynamic responses to laryngoscopy and tracheal intubation may play a role in determining clinical outcome in pediatric neurosurgical patients. This study compared the effects of remifentanil and fentanyl on cerebral blood flow velocity (CBFV) and hemodynamic profile during laryngoscopy and tracheal intubation in children under sevoflurane anesthesia.Methods: Sixty healthy children aged two to six years undergoing dental surgery under general anesthesia were enrolled. Each child was randomly assigned to receive a remifentanil or fentanyl infusion, at a rate of 0.75, 1.0, or 1.5 mug(.)kg(-1.)min(-1) after induction of anesthesia with 2% sevoflurane. Middle cerebral artery blood flow velocity was measured by transcranial Doppler (TCD) sonography. Once a baseline set of hemodynamic variables and TCD measurements were recorded, the opioid infusion was started. Measurements were taken at two-minute intervals, starting four minutes prior to laryngoscopy until four minutes following naso-tracheal intubation.Results: Remifentanil caused a more significant decrease in mean arterial pressure and CBFV prior to tracheal intubation than did fentanyl (P < 0.001). During laryngoscopy and for two minutes following tracheal intubation, CBFV increased in all remifentanil groups (P < 0.05), whereas it remained stable in all fentanyl groups.Conclusion: This study suggests that fentanyl was more effective than remifentanil at preventing increases in CBFV during and immediately following laryngoscopy and tracheal intubation in children undergoing sevoflurane anesthesia. Fentanyl also seemed to provide a more stable hemodynamic profile prior to laryngoscopy and tracheal intubation when compared to remifentanil.
Assemble four-arm DNA junctions into nanoweb
作者:Chunqing Zhou、Zukun Tan、Chen Wang、Chunli Bai、Enhua Cao
DOI:10.1007/bf02900620
日期:2001.10
DNA is of structural polymorphism, which is useful in nanoarchitecture; especially, four-arm DNA junctions can be used to assemble nanowebs. The static four-arm DNA junctions were designed and synthesized. One-arm DNA and two-arm DNA came out simultaneously with the four-arm DNA junction's formation. A new method, termed the two-step method, was proposed and the productivity of four-arm DNA junctions was Increased. A nanoweb was assembled successfully, but it showed irregularity itself. It was not the same as we expected. We consider that it is a result from the flexibility of four-arm DNA junction.
MIXANTEVA O. N.; VOISHCHEVA O. V.; POMAHOBA V. S.; MIXANTEV V. B., IZV. VUZOV. XIMIYA I XIM. TEXNOL., 1981, 24, HO 6, 681-684
作者:MIXANTEVA O. N.、 VOISHCHEVA O. V.、 POMAHOBA V. S.、 MIXANTEV V. B.