Chidan Wan

Surface-enhanced oxidation and detection of Sunset Yellow and Tartrazine using multi-walled carbon nanotubes film-modified electrode.

The insoluble multi-walled carbon nanotubes (MWNT) was successfully dispersed into water in the presence of hydrophobic surfactant. After that, MWNT film-coated glassy carbon electrode (GCE) was achieved via dip-coating and evaporating water. Owing to huge surface area, high sorption capacity and subtle electronic properties, MWNT film exhibits highly efficient accumulation efficiency as well as considerable surface enhancement effects to Sunset Yellow and Tartrazine. As a result, the oxidation peak currents of Sunset Yellow and Tartrazine remarkably increase at the MWNT film-modified GCE. Based on this, a novel electrochemical method was developed for the simultaneous determination of Sunset Yellow and Tartrazine. The limits of detection are 10.0 ng mL(-1) (2.2 x 10(-8)mol L(-1)) and 0.1 microg mL(-1) (1.88 x 10(-7)mol L(-1)) for Sunset Yellow and Tartrazine. Finally, the proposed method was successfully used to detect Sunset Yellow and Tartrazine in soft drinks.

Determination of kojic acid based on the interface enhancement effects of carbon nanotube/alizarin red S modified electrode.

Based on non-covalent interactions such as pi-pi stacking, van der Waals interactions and strong adsorption, alizarin red S (ARS) interacts with multi-walled carbon nanotubes (MWNT), improving the solubility of MWNT in water and resulting in a stable MWNT/ARS solution. By successive cyclic sweeps between 0.0 and 2.2V in the MWNT/ARS solution, a MWNT/ARS composite film was fabricated on an electrode surface. The electrochemical behaviors of kojic acid at the bare electrode, the ARS film-modified electrode and the MWNT/ARS film-modified electrode were investigated. It was found that the oxidation signal of kojic acid significantly increased at the MWNT/ARS film-modified electrode, which was attributed to the unique properties of MWNT such as large surface area, strong adsorptive ability and subtle electronic character. The effects of pH and cyclic number of electropolymerization were examined. A rapid, sensitive and simple electrochemical method was then developed for the determination of kojic acid. This method exhibits good linearity over the range from 4.0 x 10(-7) to 6.0 x 10(-5)mol L(-1), and the limit of detection is as low as 1.0 x 10(-7)mol L(-1). In order to validate feasibility, the MWNT/ARS film-modified electrode was used for quantitative analysis of kojic acid in food samples.

Electrochemical determination of chrysophanol based on the enhancement effect of acetylene black nanoparticles

Acetylene black (AB) nanoparticles were readily dispersed into water in the presence of dihexadecyl hydrogen phosphate. After evaporation of water, the surface of glassy carbon electrode (GCE) was coated with AB nanoparticles as confirmed from the scanning electron microscopy measurements. The transmission electron microscopy images indicated that AB nanoparticles possessed porous structure. Electrochemical behavior of chrysophanol was studied, and a sensitive oxidation peak was observed in pH 3.6 acetate buffer solution. Compared with the bare GCE, the AB nanoparticles-modified GCE greatly increased the oxidation peak current of chrysophanol, showing remarkable signal enhancement effect. The influences of pH value, amount of AB, accumulation potential and time on the signal enhancement of chrysophanol were studied. As a result, a novel electrochemical method was developed for the determination of chrysophanol. The linear range was from 1.5 to 200 μgL(-1), and the detection limit was 0.51 μgL(-1) (2.01 × 10(-9)M) after 2-min accumulation. Finally, this method was used in traditional Chinese medicines, and the results consisted with the values that obtained by high-performance liquid chromatography.

Endoscopic minimal invasive cholecystolithotomy vs laparoscopic cholecystectomy in treatment of cholecystolithiasis in China: A meta-analysis

INTRODUCTION Endoscopic minimal invasive cholecystolithotomy (EMIC) is recently popular in China which may offer advantages over laparoscopic cholecystectomy (LC). We try to find out the most favorable treatment for the patients underwent cholecystolithiasis. METHODS Databases PubMed, Elsevier, Wiley Online Library, The Cochrane library, CNKI, WanFang Data, and Chongqing VIP were searched for randomized controlled trials (RCTs) and on EMIC vs LC from 2009 to 2013. Odds ratio (OR), risk difference (RD) and weight mean difference (WMD) were calculated with 95% confidence intervals (CI). RESULTS 14 RCTs including 2030 patients were selected. No significant difference was present in operating time between EMIC and LC. EMIC shown significant less blood lost (WMD -23.45; 95% CI -30.34, -16.55; Z=6.66; P<0.00001) compared to LC. Shortened exhaust time (WMD -14.11; 95% CI -18.34, -9.88; Z=6.53; P<0.00001) and hospital stay (WMD -1.31; 95% CI -1.91, -0.71; Z=4.29; P<0.00001) were present in EMIC group. And EMIC shown decreased complication proportion (OR -0.14, 95% CI -0.09 to -0.21; Z=8.53; P<0.00001) in comparison with LC. There is no difference present in the recurrence of stones in two procedures but a significantly decreased recurrence rate of gallstones was present in EMIC compared to conventional cholecystolithotomy. CONCLUSION Patients treated with EMIC shown faster recovery and less complication which were superior to LC.

Expression of NALP3 in the spleen of mice with portal hypertension

SummaryThis study examined the mRNA expression of NALP3 in the spleen of the mice with hypersplenism due to portal hypertension (PH). The mouse hypersplenism models were established by oral administration of tetrachloromethane (2 mL/kg/week for 12 weeks by oral gavage). All the mice were randomly divided into a control group and an experimental group. The blood routine test was conducted, spleen index was calculated and spleen was histologically examined. Portal vein sera were taken for detection of the level of uric acid. The mRNA expressions of NALP3 and IL-1β in the spleen were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that the platelet count was significantly lower in the experimental group [(674±102)×109/L] than in the control group [(1307±181)×109/L] (P<0.05), while the spleen index was significantly higher [(9.83±1.36) μg/g] in the experimental group than in the control group [(4.11±0.47) μg/g] (P<0.05). The histopathological changes of spleen followed the pattern of congestive splenomegaly. No significant difference was found in the uric acid level in the portal vein between the control group and the experiment group. The mRNA expressions of NALP3 and IL-1β were up-regulated significantly in the spleen in the experimental group as compared with those in the control group (P<0.05). It was concluded that NALP3 and IL-1β may play important roles in the pathogenesis of hypersplenism.This study examined the mRNA expression of NALP3 in the spleen of the mice with hypersplenism due to portal hypertension (PH). The mouse hypersplenism models were established by oral administration of tetrachloromethane (2 mL/kg/week for 12 weeks by oral gavage). All the mice were randomly divided into a control group and an experimental group. The blood routine test was conducted, spleen index was calculated and spleen was histologically examined. Portal vein sera were taken for detection of the level of uric acid. The mRNA expressions of NALP3 and IL-1β in the spleen were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that the platelet count was significantly lower in the experimental group [(674±102)×109/L] than in the control group [(1307±181)×109/L] (P<0.05), while the spleen index was significantly higher [(9.83±1.36) μg/g] in the experimental group than in the control group [(4.11±0.47) μg/g] (P<0.05). The histopathological changes of spleen followed the pattern of congestive splenomegaly. No significant difference was found in the uric acid level in the portal vein between the control group and the experiment group. The mRNA expressions of NALP3 and IL-1β were up-regulated significantly in the spleen in the experimental group as compared with those in the control group (P<0.05). It was concluded that NALP3 and IL-1β may play important roles in the pathogenesis of hypersplenism.

Experimental study on the cryopreservation of LLC-PK1 epithelial cells with hypoxic UW solution

The effects of oxygen partial pressure on cryopreservation of the cells with organ preservation solution were explored. Hypoxic UW solution was made by purging the UW solution with argon. The pig proximal tubule epithelial cells (LLC-PK1 cells) were cryopreserved in hypoxic UW solution (Ar-UW group) or standard UW solution (UW group) at 4°C for 48 h. Trypan blue staining and LDH detection were performed to evaluate the injury of the cells. The results showed that the oxygen partial pressure in Ar-UW group was significantly declined from 242±6 mmHg to 83±10 mmHg. After cryopreservation at 4°C for 48 h, LDH leakage rate and Trypan blue-stained rate in Ar-UW group were (11.3±3.4)% and (10.5±4.7)%, respectively, which were significantly lower than in UW group [(49.5±6.9)% and (47.6±9.3)% respectively, both P<0.01]. It was concluded that lower oxygen partial pressure of UW solution was more beneficial to the cryopreservation of LLC.

Proliferation and differentiation of duct epithelial cells after partial pancreatectomy in rats.

The proliferation and differentiation of pancreatic duct epithelial cells in remnant pancreas during regeneration after partial pancreatectomy in rats were studied, and the source of pancreatic stem cells was characterized. Partial (90 %) pancreatectomy was performed on 4-to 5-week-old Sprague-Dawley rats, and different duct epithelial cells and acinar cells were detected by immunohistrochemical stain method and scored using 5-bromo-2′-deoxyuridine (BrdU) labeling index (LI) at various time points after partial pancreatectomy. It was found that at 24 h after partial pancreatectomy proliferation started in the main, large and small duct cells, and persisted in small duct cells to day 5. There was significant difference between the experimental group and the control group (P<0.001). Acinar cells positive for BrdU were greatly increased and reached the peak LI on day 5. The destroyed lobular architecture almost totally recovered on day 7, and the newly islet cells appeared around the pancreatic ducts. These results suggest that regeneration after partial pancreatectomy is involved in proliferation and differentiation of pancreatic stem cells, and pancreatic stem cells may locate in the pancreatic ductules.

Effect of Target-directed Regulation of Uncoupling Protein-2 Gene Expression on Ischemia-reperfusion Injury of Hepatocytes *

The effect of target-directed regulation of the uncoupling protein-2 (UCP-2) gene expression on the ischemia-reperfusion injury of hepatocytes under different conditions was investigated. The expression plasmid and RNAi plasmid targeting UCP-2 gene were constructed and transfected into normal hepatocytes and fatty liver cells, respectively. The expression of UCP-2 mRNA was detected by real time PCR. The cells were divided into normal cell group (NCG), group of normal cells transfected with empty vector (EVNCG), group of normal cells transfected with expression plasmid (EPNCG), fatty liver cell group (FCG) and group of fatty liver cells transfected with RNAi plasmid (RPFCG). The ischemia-reperfusion model in vitro was established. One, 6, 12 and 24 h after reperfusion, Annexin V/PI flow cytometry was used to measure cell necrosis rate, apoptosis rate and survival rate. Simultaneously, the intracellular ATP, ROS and MDA levels were determined. The results showed that 1, 6, 12 and 24 h after ischemia-reperfusion, the intracellular ROS, MDA and ATP levels and cell survival rate in EPNCG were significantly lower, and cell necrosis rate significantly higher than in NCG and EVNCG, but there was no significant difference in apoptosis rate among NCG, EVNCG and EPNCG (P>005). Six, 12 and 24 h after reperfusion there was no significant difference in ROS, MDA levels and apoptosis rate between FCG and RPFCG (P>0.05), but the ATP level and survival rate of cells in RPFCG were higher than in FCG (P<0.05). It was concluded that down-regulation of the UCP-2 gene expression in steatotic hepatocytes could alleviate the ischemia-reperfusion injury of liver cells.SummaryThe effect of target-directed regulation of the uncoupling protein-2 (UCP-2) gene expression on the ischemia-reperfusion injury of hepatocytes under different conditions was investigated. The expression plasmid and RNAi plasmid targeting UCP-2 gene were constructed and transfected into normal hepatocytes and fatty liver cells, respectively. The expression of UCP-2 mRNA was detected by real time PCR. The cells were divided into normal cell group (NCG), group of normal cells transfected with empty vector (EVNCG), group of normal cells transfected with expression plasmid (EPNCG), fatty liver cell group (FCG) and group of fatty liver cells transfected with RNAi plasmid (RPFCG). The ischemia-reperfusion model in vitro was established. One, 6, 12 and 24 h after reperfusion, Annexin V/PI flow cytometry was used to measure cell necrosis rate, apoptosis rate and survival rate. Simultaneously, the intracellular ATP, ROS and MDA levels were determined. The results showed that 1, 6, 12 and 24 h after ischemia-reperfusion, the intracellular ROS, MDA and ATP levels and cell survival rate in EPNCG were significantly lower, and cell necrosis rate significantly higher than in NCG and EVNCG, but there was no significant difference in apoptosis rate among NCG, EVNCG and EPNCG (P>005). Six, 12 and 24 h after reperfusion there was no significant difference in ROS, MDA levels and apoptosis rate between FCG and RPFCG (P>0.05), but the ATP level and survival rate of cells in RPFCG were higher than in FCG (P<0.05). It was concluded that down-regulation of the UCP-2 gene expression in steatotic hepatocytes could alleviate the ischemia-reperfusion injury of liver cells.

Pancreatic Ductal Cells Acquire Mesenchymal Characteristics through Cell Fusion with Bone Marrow-Derived Mesenchymal Stem Cells and SIRT1 Attenuates the Apoptosis of Hybrid Cells

Bone marrow-derived mesenchymal stem cells (bMSCs) contribute to tissue repair and regeneration. Cell fusion between somatic cells and bMSCs to form hybrid cells may have an important role in tissue repair through the subsequent reprogramming of the somatic cell nucleus. Few studies have assessed the mesenchymal characteristics of fusion-induced hybrid cells and their survival mechanisms. In this study, we investigated the effect of cell fusion on the biological characteristics of pancreatic ductal cells (PDCs) and on the survival mechanism of hybrid cells. To this end, we generated mouse-mouse hybrid cells in vitro by polyethylene glycol-mediated fusion of primary mouse bMSCs with primary mouse PDCs. Hybrid cells showed an enhanced capacity for proliferation and self-renewal compared with PDCs. No PDC had the capacity for anchorage-independent growth or invasion into Matrigel, but some hybrid cells were able to form colonies in soft agar and invade Matrigel. Expression of the tumor suppressor protein p53, which initiates apoptosis, was detected in hybrid cells but not in PDCs or bMSCs. However, the p53 deacetylase, sirtuin 1 (SIRT1), was also detected in hybrid cells, and the level of acetylated p53, the active form, was low. The addition of nicotinamide (Nam) inhibited the deacetylation activity of SIRT1 on p53 and induced cell apoptosis in hybrid cells. This study demonstrated that PDCs could obtain high proliferation rates, self-renewal capabilities, and mesenchymal characteristics by fusion with bMSCs. SIRT1 expression in the hybrid cells attenuated their apoptosis.

Relationship between the apoptosis and notch-1 expression in acute pancreatitis.

In order to investigate the expression of Notch-1 in rats with acute pancreatitis (AP) and its relation with apoptosis of pancreatic cells, mild AP (MAP) and severe AP (SAP) models were established by retrograde injection of different concentrations of sodium taurocholae into pancreatic duct. The apoptosis index and the expression of Notch-1 protein and mRNA were detected by using TUNEL, Western blot and real-time PCR in MAP and SAP at different time intervals. The results showed that in MAP group the apoptosis index was significantly elevated during 4 to 24 h after induction of pancreatitis, but there was no significant difference among different time intervals. In SAP group, the apoptosis index reached the peak at 4th h after induction of pancreatitis, then gradually declined. There was significant difference in apoptosis index between MAP and SAP groups. Starting from 4th after induction of pancreatitis, the expression of Notch-1 in both MAP and SAP group was increased at different time intervals, but that in SAP group was significantly higher than in MAP group (P<0.05). The expression of Notch in MAP and SAP groups reached the peak at 12th and 8th h respectively after induction of pancreatitis. It was concluded that there was significant difference in apoptosis index and the Notch-1 expression in different types of AP. The overexpression of Notch-1 could aggravate AP by inhibiting the apoptosis of pancreatic cells.