Objective To explore the comparative effects of the application of ECG characteristic P-wave in PICC tip alignment. Methods Totals of 136 patients who needed PICC intubation were randomly divided into the experimental group and the control group, with 68 cases in each group. In the experimental group,after the PICC was successfully delivered to the right sternoclavicular joint, the ECG monitor was connected and based on the changes of P-wave on ECG to determine the optimum position of the end of catheter. In the control group,after the PICC was successfully delivered tothe predictive position, patients were sent to the Radiology Department to receive X-ray and located to the optimum position. The alignment accuracy rate, intervention time, costs, the predictive position and practical position, and general information were compared. Results The alignment accuracy rate in the experimental group was 94. 1%, which had no significant difference (χ2 =2. 318,P>0. 05). The intervention time and cost of the experimental group were (3. 16 ± 1.57) min and (7.12 ±0.56) yuan, which were significantly different from those in the control group (t=8. 819,27. 336;P < 0. 05 ). The results of general information and the predictive position and practical positionhad no significant difference (P>0. 05). Conclusions ECG alignment is accurate, time-saving and with low costs and it can avoid the radiation harm for nurses and patients in X-ray alignment. ECG alignment can replace the traditional X-ray alignment and become another alignment method for PICC intubation in clinical application.

We studied the mutation effect of subsites -3(Lys47), -7(146-152), and cyclization center (Tyr195) in active domain on product specificity of alpha-cyclodextrin glucanotransferase (alpha-CGTase) from Paenibacillus macerans sp. 602-1. The Lys47 was replaced by Thr47 and Tyr195 by Ile195, and the amino acids from 146 to 152 were replaced by Ile (named as delta6). All these mutant alpha-CGTases were actively expressed in E. coli BL21. Compared with the wild-type alpha-CGTase, the starch-degrading activities of all the mutant enzymes were declined. For mutant Y195I, the percentage of alpha-CD was decreased from 68% to 30%, and beta-CD was raised from 22.2% to 33.3%. Interestingly, gamma-CD was increased from 8.9% to 36.7% and became the main product, while the actual yield was increased from 0.4 g/L to 1.1 g/L. Mutant K47T and delta6 still produced alpha-CD as main product though the percentage of beta- and gamma-CD increased. Purified Y195I CGTase showed similar optimum temperature with the wild-type alpha-CGTase, but its optimum pH shifted from 5.0 to 6.0 with better pH stability. In summary, mutant Y195I CGTase has the potential to produce gamma-CD as the main product.
Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; genetics ; metabolism ; Mutant Proteins ; genetics ; metabolism ; Mutation ; Paenibacillus ; enzymology ; Recombinant Proteins ; genetics ; gamma-Cyclodextrins ; metabolism