Biomedical subjects

Xiao-Yu Zhao

Publications and source records attributed to Xiao-Yu Zhao.

4 recordsLinked to original sources

PubMed2005

[Purification and renaturation of recombinant human Cu, Zn-SOD by metal-chelating affinity chromatography].

Overexpression of recombinant Human Cu, Zn-Superoxide Dismutase (rhCu, Zn-SOD) in E. coli results in the form of insoluble inclusion body. Purity of rhSOD inclusion body was over 80% by isolation and purification. After preliminary renaturation by conventional dilution or dialysis, enzyme preparations was respectively purified by using Copper Metals-Chelating Affinity Chromatography (Copper-MCAC). RhSOD specific activity purified by MCAC (from the sample renatured partly by dialysis) was 2.2 times as much as that by dialysis and protein recovery was 64%. RhSOD specific activity purified by MCAC (from the sample renatured partly by dilution) was 5.3 times as much as that by dilution and protein recovery was 25%. The two rhSOD preparations purified by MCAC had specific activities about 5000 u/mg and activity recoveries were all over 130% of the enzyme activities in the samples renatured partly by dilution or dialysis. The above-mentioned results indicated that Copper-MCAC resulted in a purification and further renaturation of target protein. SDS-PAGE showed that the target protein rhSOD (19 kD) was purified homogeneously and NBT activity identification proved that the purified and renatured rhSOD had very strong SOD activity. In conclusion, Copper Metals-Chelaing Affinity Chromatography appears to be a simple, rapid and efficient procedure for purifying and further renaturing rhCu, Zn-SOD by dilution or dialysis. The method provided a new idea for purifying and renaturing recombinant proteins expressed in the form of inclusion body in E. coli.

Chelating Agents↗

PubMed2004

Decryption of pure-position permutation algorithms.

Pure position permutation image encryption algorithms, commonly used as image encryption investigated in this work are unfortunately frail under known-text attack. In view of the weakness of pure position permutation algorithm, we put forward an effective decryption algorithm for all pure-position permutation algorithms. First, a summary of the pure position permutation image encryption algorithms is given by introducing the concept of ergodic matrices. Then, by using probability theory and algebraic principles, the decryption probability of pure-position permutation algorithms is verified theoretically; and then, by defining the operation system of fuzzy ergodic matrices, we improve a specific decryption algorithm. Finally, some simulation results are shown.

Algorithms↗

PubMed2004

[The tendency of physiological and psychological change of the armored vehicle drivers working continuously in hot environment].

OBJECTIVE: To probe the tendency of physiological and psychological change of armored vehicle drivers working continuously in hot environment. METHODS: Ten cross-designed standard subjects were divided into control group and driver group. The driver group worked continuously in 32 degrees C approximately 38 degrees C and RH 50% approximately 80% environment. Heart rate, body temperature, systolic blood pressure and pulse pressure were synchronously and dynamically determined during work. Psychological parameters such as profile of mood states (POMS) questionnaire, serial addition/subtraction (SAS) and two-digit search (TDS) selected from neurobehavioral evaluation system (NES) before and after work were also tested. RESULTS: The curves of the four main physiological parameters rapidly synchro-rose to a peak at (36 +/- 3) min, whereafter the curves descended smoothly. At (144 +/- 8) min, the curves climbed up to the second peak. The determination of the behavioral psychology revealed that the degree of fatigue of the drivers increased gradually when the working time prolonged, and the grip descended by great extent, excitement reduced markedly after work, but the negative mood, such as confusion and depression were increased, error of visual apperceive-operation was increased, right decreased, intelligence reduced, rapidity and delicacy of movement reduced. CONCLUSION: The physiological parameters of armored vehicle drivers working continuously in the hot condition appeared double-peak effect, the 1st peak was at (36 +/- 3) min, and the body was in mobilizing stage. Whereafter, the body was in smooth stage. And at (144 +/- 8) min, when the 2nd peak appeared, the body then was in physiological tolerance limit stage.

Adaptation, Physiological↗

PubMedDate not supplied

Cathodic electrochemiluminescence of Ru(bpy)(3)(2+)/Nafion coated on graphite oxide electrode in purely aqueous solution.

Two cathodic electrochemiluminescence (ECL) peaks have been obtained at -0.99 and -1.80 V (vs. SCE), respectively, from Ru(bpy)(3)(2+)/Nafion coated onto a graphite oxide electrode in purely aqueous solution under cyclic voltammetric (CV) conditions, without addition of any reducing or oxidative reagents. These two ECL peaks were found to correlate to initial scan direction, pH, and reversal potential. Nafion played an important role in the generation of these two ECL peaks because no cathodic emission was observed in the system without Nafion. It seems that a part of Ru(bpy)(3) (3+) electrogenerated at positive potential can remain in the Nafion, even at negative potentials. It was con fi rmed that Ru(bpy)(+) was formed at -1.80 V by addition of S(2)O(8) (2-). The ECL peak at -0.99 V is attributed to the reaction of Ru(bpy)(3+) and OH(-). The ECL peak at -1.80 V is probably due to the annihilation reaction of Ru(bpy)(3+) and Ru(bpy)(+).

2,2'-Dipyridyl↗