Thiamin pyrophosphate (TPP) is a thiamine (vitamin B1) derivative and an essential cofactor in oxidative metabolism of the sugars,fatty acids and amino acids in living cells.By now,numerous TPP-dependent artificial riboswitch systems have been developed to regulate target gene expression but limited in bacteria,fungi or plant cells.Herein,the activating (switch-on) and inhibiting (switch-off) TPP-depended hammerhead ribozyme switches,which are from previous reported structures of prokaryotes screening,were investigated in mammalian cells.These ribozyme switches were inserted into the 3'UTR of the enhanced green fluorescence protein (EGFP) gene to construct the efficient ribozyme-based artificial switches through overlap extension PCR cloning.The HEK293 cells were transfected with the engineered ribozyme switches at increasing concentration of TPP.The EGFP gene-regulatory ability was analyzed with fluorescent microscope and flow cytometry.These TPP-inducible gene regulation devices showed the obvious ligand dose-dependency and excellent specificity.Two switch-on and one switch-off constructs demonstrated 3.1-fold or 1.9-fold increment and 2.3-fold reduction of EGFP level respectively with 150 μ mol/L TPP.The ligand-responsive ribozyme switches,by tuning the change of TPP concentration into the visual reporter genetic expression in cells,enable an efficient development of label-free,noninvasive and high-specific biosensors in living mammalian cells.

【Objective】 To investigate the effect of intravenous immunoglobulin(IVIG) with different Aβ antibody content on the cognitive function of Alzheimer′s disease model mice. 【Methods】 IVIG from 8 domestic blood products companies were selected. Enzyme-linked immunosorbent assay(ELISA) was used to detect the content of Aβ40/42 antibody. Three kinds of IVIG with high, middle and low Aβ42/40 antibody levels were selected to treat 3xTg-AD mice. Forty 3-month-old 3xTg-AD mice were randomly divided into 4 groups with 10 mice in each group(half male and half female). Three treat groups were intraperitoneally injected with three kinds of IVIG with 1g·kg^-1 for 12 weeks(twice a week). The controls were injected with the same volume of saline. Behavioral tests were performed immediately by using the mouse behavior analysis system after a total of 24 injections. 【Results】 The concentrations of antibodies(μg/mL) against Aβ40 monomer in IVIG ranged 0.7±0.05 to 3.1±0.05, concentrations of antibodies against Aβ40 oligomer ranged 11.7±0.7 to 32.0±2.2, concentrations of antibodies against Aβ42 monomer ranged 1.8±0.1 to 27.9±0.3, and concentrations of antibodies against Aβ42 oligomeric ranged 2.3±0.1 to 49.4±2. High(IVIG-1), medium(IVIG-8) and low(IVIG-6) IVIG were selected for mice study. In the open field test, the time of four groups of mice entering the central area(s) was 0.5±0.9, 23.4±6.1(P<0.0001), 4.6±2.8 and 2.6±2.3, respectively; the number of feces(grains) was 1.6±0.7(P<0.0001), 1.2±0.4(P<0.0001), 2.4±0.5(P<0.001) and 3.8±0.8, respectively. In the novel object recognition test, the scores of exploring new objects were 71.3±29.5(P<0.05), 71.8±20.5(P<0.05), 75.9±26.9(P<0.01) and 25.6±23.7, respectively. In the Barnes maze test, the time of exploring the target hole in the IVIG-8 group was significantly longer than that in the control on the 6^th day(50.3±19.3 vs 21±14.6, P<0.05) and the 13^th day(58.2±20.9 vs 19.2±15.9, P<0.005), but there was no significant difference between the IVIG-1, 6 groups and the control. 【Conclusion】 There is a significant difference in the level of Aβ40/42 antibody among 8 kinds of domestic IVIG. Domestic IVIG could improve the cognitive function of 3-month-old 3xTg-AD mice after continuous intervention for 3 months. The improvement effect, however, was related to the Aβ antibody in IVIG, but not to the antibody concentration.

【Objective】 To compare the desalination effects of five desalination methods and their effects on the components for human coagulation factor Ⅷ(FⅧ), and provide reference for selection of protein desalination methods. 【Methods】 Sephadex G-25 Medium gel, Fractogel EMD BioSEC gel, ultrafiltration, room temperature dialysis and 4℃ dialysis were used to desalt human FⅧ. The desalination effect was evaluated by the removal rate of Na +, citrate ion and glycine. FⅧ protein recovery, FⅧ activity (FⅧ∶C), VWF antigen (VWF∶Ag), VWF activity(VWF∶Ac), VWF polymers and SDS-PAGE analysis before and after desalination were compared to evaluate the effect of desalination on FⅧ components. 【Results】 In terms of desalination effect, the removal rate of Na⁺ was the lowest in ultrafiltration desalination, while that of Fractogel EMD BioSEC gel was the highest [(97.90±0.06) % vs (99.82±0.07) %]. Except that there was no statistical significance between Sephadex G-25 Medium gel desalination and Fractogel EMD BioSEC gel desalination (P=0.90), the removal rates of the other four methods were statistically significant. The removal rate of glycine was the lowest in ultrafiltration desalination, wihle that of Fractogel EMD BioSEC gel desalination was the highest [(95.78±0.42) % vs (99.81±0.08) %]. Significant difference in glycine removal was noticed in ultrafiltration desalination, but not among the other four desalination methods. There was no significant difference in the removal rate of citrate ions among the five methods (P=0.85). For the effect of FⅧ components, FⅧ∶C, VWF∶Ag, VWF∶Ac and protein recovery rates of ultrafiltration desalination were the highest, with (18.34±1.99) IU/mL, (11.81±0.33) IU/mL, (12.26±0.58) IU/mL and (97.13±1.37) %, respectively. There was no significant change in VWF∶Ac/VWF∶Ag before and after desalination by the five methods. SDS-PAGE and VWF polymer analysis showed that different desalination methods had no significant impact on protein composition. 【Conclusion】 Although different desalination methods had no significant effect on the composition of FⅧ protein, the desalination effect was different. Moreover, different desalination methods had significant effects on protein recovery, FⅧ∶C, VWF∶Ag and VWF∶Ac. The selection of desalination methods should be more considered during protein processing,

【Objective】 To explore the risk of Alzheimer′s disease (AD) transmitted by blood transfusion. 【Methods】 There were 10 APP/PS1 mice of 3, 6 and 9 months old, half female and half male, and the cognitive and behavioral abilities of C57 mice of the same age were measured, and the blood of the oldest APP/PS1 mice with no behavioral changes were collected to detect the contents of Aβ40 and Aβ42. The polymers Aβ40 and Aβ42 were prepared and Western blotting analysis was conducted. Kunming mice aged from 6 to 7 months were randomly divided into 6 groups (10 mice/ group, half male and half female). The blood of APP/PS1 mice was injected intravenously in experimental group 1-2(100 μL/mouse) with high frequency injection (3 times/week) and low frequency injection (1 time/week), respectively. In experimental group 3-4, Aβ40 and Aβ42 polymerized mixture (100 μL/mouse) were injected in high frequency and low frequency, respectively. The control group 1-2 was injected with the same amount of normal saline, with high frequency and low frequency, respectively. The above groups were injected for 4 weeks, and the cognitive and behavioral abilities were tested and analyzed one week after injection. Finally, the contents of Aβ40 and Aβ42 in blood of Kunming mice were detected. 【Results】 Change in cognitive and behavioral ability showed in 9 months old APP/PS1 mice, but not in 3 and 6 months old APP/PS1 mice. The contents of Aβ40 and Aβ42 (pg/mL) in blood of 6-7 months old APP/PS1 mice were 418.40±2.18 and 15.68±0.20, respectively. Except for monomers, most of the polymerized mixtures of Aβ40 and Aβ42 were dimers and trimers. In both high frequency and low frequency, Kunming mice transfused with blood of APP/PS1 mice (experimental group 1-2) showed a certain degree of anxiety-like behavior and short-term memory shortening in open-field test and conditioned fear test, but without significant difference. There was no significant difference in open field test, new object recognition, Barnes maze and cognitive behavior analysis of conditioned fear between experimental group 3-4 and the control group. The levels of blood Aβ40 and Aβ42(pg/mL) of Kunming mice detected by ELISA were 10.30±0.08 and 3.360±0.005, respectively, and there was no significant difference between the two groups. 【Conclusion】 Blood transfusion of APP/PS1 mice and the mixture of Aβ40 and Aβ42 have no significant effect on the cognitive function of healthy Kunming mice in a short time, and the risk of AD transmission is relatively low.