Biomedical subjects

Jin Wen

Publications and source records attributed to Jin Wen.

9 recordsLinked to original sources

PubMed2006

Protein-induced DNA bending clarifies the architectural organization of the sigma54-dependent glnAp2 promoter.

Sigma54-RNA polymerase (Esigma54) predominantly contacts one face of the DNA helix in the closed promoter complex, and interacts with the upstream enhancer-bound activator via DNA looping. Up to date, the precise face of Esigma54 that contacts the activator to convert the closed complex to an open one remains unclear. By introducing protein-induced DNA bends at precise locations between upstream enhancer sequences and the core promoter of the sigma54-dependent glnAp2 promoter without changing the distance in-between, we observed a strong enhanced or decreased promoter activity, especially on linear DNA templates in vitro. The relative positioning and orientations of Esigma54, DNA bending protein and enhancer-bound activator on linear DNA were determined by in vitro footprinting analysis. Intriguingly, the locations from which the DNA bending protein exerted its optimal stimulatory effects were all found on the opposite face of the DNA helix compared with the DNA bound Esigma54 in the closed complex. Therefore, these results provide evidence that the activator must approach the Esigma54 closed complexes from the unbound face of the promoter DNA helix to catalyse open complex formation. This proposal is further supported by the modelling of activator-promoter DNA-Esigma54 complex.

Base Sequence↗

PubMed2005

Purification and preliminary X-ray crystallographic analysis of the ligand-binding domain of Sinorhizobium meliloti DctB.

Sinorhizobium meliloti DctBD is a well-characterized two-component system. It is believed that DctB senses the concentration of C4-dicarboxylate compounds on the outside of the bacterium and phosphorylates DctD, which in turn activates transcription of the dctA gene, coding for a gene of C4-dicarboxylate permease. The structure and function of the ligand-binding domain of DctB has not been thoroughly investigated. In this study, this domain was produced in E. coli in soluble form, and purified to homogeneity. Crystals were obtained by hanging-drop vapor-diffusion method. The crystals diffracted to 2.3 A resolution and belonged to P42 space group with unit cell dimensions of a = b = 71.77 A, c = 227.14 A. The asymmetric unit contains four molecules with a corresponding VM of 2.4 A3 Da(-1) and a solvent content of 49.1%.

Bacterial Proteins↗

PubMed2005

[Analysis of hepatitis virus infection in hepatocellular carcinoma patients receiving surgical operation in China and Japan].

OBJECTIVE: To describe and compare the hepatitis virus infection in hepatocellular carcinoma (HCC) patients receiving surgical operation in China and Japan. METHODS: Information of surgical HCC patients was retrieved from the medical records. The concerned characteristics of the HCC cases from two countries were described and compared. RESULTS: A total of 425 diagnosed cases that underwent surgical resection for HCC in China were investigated, and the corresponding cases in Japan were 247. The proportion of the hepatitis virus infection was 75.53% in patients with HCC from China. Within the infection cases, 91.28% were positive for HBsAg but negative for anti-HCV. The proportion was 82.59% in patients with HCC from Japan. Within the infection cases, 77.94% were positive for anti-HCV but negative for HBsAg. The proportion of hepatocirrhosis in the hepatitis virus infection patients with HCC were 89.10% and 68.14% in China and Japan, respectively. CONCLUSION: The hepatitis B virus infection showed be a main cause of HCC in China, however, the HCC in Japan be mostly related to hepatitis C virus infection.

Adolescent↗

PubMed2005

[Time-series analysis on road traffic injury in China].

OBJECTIVE: To establish the predictive models of road traffic injury(RTI) in China, to know the trend of RTI, and to provide the reference data for controlling RTI in China. METHODS: The China RTI data from 1951 to 2003 were collected, and in view of the problem of missing values, the method of intrapolation was adopted. The Box-Jenkins technique was used to analyze and predict the trend of RTI in China. Following the process for stationary time-series analysis, model identification, parameter estimation and model diagnosis, the predictive equation for RTI would be established. RESULTS: A series of predictive equations on RTI were finally established based on ARIMA models. The curve fitting is effective and the predictive data of RTI in 2003 are close to the true statistical data. CONCLUSION: The time-series model thus established proves to be of significant usefulness in RTI prediction.

Accidents, Traffic↗

PubMed2005

[A case-crossover study on road traffic injury].

OBJECTIVE: To explore the risk factors of road traffic injury (RTI), and to provide evidence for stretagy development on the prevention and control of RTI. METHODS: Case-crossover study was used. 402 drivers were face to face interviewed by specially designed questionnaire including the items as drinking alcohol before driving, onset anger scale (OAS), anxiety/irritation, Stanford sleepiness scale (SSS), vehicle breakdown, carelessness, violating the rules on right of way and traffic signs when driving. Tables related to case-control study on 1:1 matching was used for single factor analysis, and conditional logistic regression was used for multifactor analysis. RESULTS: The risk factors that were associated with RTI including high OAS (OAS = 5-7, OR = 114.88, 95% CI:4.29-3074.86), violating the rules on right of way (OR = 46.96, 95% CI:12.74-173.11), violating traffic signs when driving(OR = 24.57, 95% CI: 8.69-69.45), carelessness (OR = 14. 54,95% CI: 6.85-30.86), unsafe distance between vehicles( OR = 14.30,95% CI: 3.68-55.60), wrong judgement (OR = 14.67,95% CI:4.88-44.10), vehicle breakdown (OR = 8.57, 95% CI: 1.38- 53.27) and improper measure ( OR = 8.46, 95% CI: 2.46-29.14) etc. CONCLUSION: Improper driving behaviors, abnormal psychological status and driving skills of drivers were related to RTI, suggesting that it was necessary to carry out continous traffic security education to the drivers.

Accidents, Traffic↗

PubMed2003

Fluorescence of dietary porphyrins as a basis for real-time detection of fecal contamination on meat.

Digestion of green plants in the gastrointestinal (GI) tract produces degradation products from chlorophyll that cause ingesta and feces to be highly fluorescent. This property was exploited for development and construction of instruments to noninvasively detect minute quantities of feces on meat samples in real time. The presence of feces on meat products is a primary source of foodborne pathogens, such as Escherichia coli O157:H7 and Salmonella. This new technology provides a rapid and accurate alternative to the practice of visual inspection and augments more time-consuming biological testing methods. This innovation can assist meat processors and government inspectors in their efforts to provide safe and wholesome food to consumers.

Animals↗

PubMed2003

Triterpenoids from Schisandra henryi with cytotoxic effect on leukemia and Hela cells in vitro.

Four known lanostane triterpenoids, schiprolactone A (1), schisanlactone B (2), nigranoic acid (3) and schisandronic acid (4) were isolated from the stems of Schisandra henryi for the first time. Their structures were characterized by IR, MS and NMR techniques. Compounds 1, 2 and 4 showed moderate cytotoxic activity against Leukemia cells in vitro. Cytotoxic activity of compounds 1-4 showed IC50 of 0.0097, 0.01, 0.097 and 0.0099 micromol/mL respectively toward Leukemia cells and IC50 of 0.097, 0.1, 0.097 and 0.099 micromol/mL toward Hela cells respectively. It is the first report that these compounds possess cytotoxic activity on Leukemia and Hela cells.

Animals↗

PubMed2002

[Establishment of delayed encephalopathy rat model of carbon monoxide poisoning].

OBJECTIVE: To establish the delayed encephalopathy rat model of carbon monoxide (CO) poisoning. METHODS: 40 Wistar rats were randomly divided into 4 groups of 10 rats and were placed in the chambers of inside-built 10-chamber poisoning box. Mixed gas is ventilated with the volume fractions of 10.0 x 10(-4), 15.0 x 10(-4) and 16.5 x 10(-4) of CO in air into the chambers for group A, B and C respectively, and pure air was ventilated for group D. The gas flow rate was 800 L/h in the first 5 hours, 1,000 L/h in the middle 4 hours, and 1,200 L/h in the last 3 hours, with a whole ventilation time of 12 hours. Before and after CO poisoning maze test with radial eight-arm maze was conducted to assess the rats' intelligence. The appearance of coma or less than 3 correct arm-enterings in maze test between the 3rd and 28th day after poisoning was considered as the indications of delayed encephalopathy. TUNEL method, flow cytometry, and transmission electron microscopy were adopted to examine the cellular apoptosis in cerebral cortex and hippocampus area. RESULTS: There were 4 rats with delayed encephalopathy changes in groups B and C respectively, while no similar behavioral change appeared in groups A and D. TUNEL method showed an apoptotic rate of 45.0% to 65.0% in the rats with delayed encephalopathy of group B and an apoptotic rate of 55.0% to 80.0% in the rats with delayed encephalopathy of group C, most of the apoptotic cells being neurons. Flow cytometry showed an apoptotic rate of 50.5% +/- 4.2% in the rats with delayed encephalopathy of group B and an apoptotic rate of 55.9% +/- 7.8% in the rats with delayed encephalopathy of group C. By electron microscopy the percentage of typical apoptotic neurons was 5.0% approximately 15% in group B and 10.0% to 20.0% in group C, less than 5.0% in group A, and less than 1.6% in group D. CONCLUSION: A delayed encephalopathy rat model of CO poisoning has been successfully established based on the volume fraction of 15.0 x 10(-4) to 16.5 x 10(-4) of CO in air and a poisoning time of 12 hours. The pathological change is a mass neuron apoptosis in cerebral cortex and hippocampus.

Animals↗

PubMed2002

Toward the molecular flashlight: preparation, properties, and photophysics of a hypericin-luciferin tethered molecule.

The synthesis of a molecule containing hypericin and luciferin moieties joined by a tether is reported. The light-induced (in vitro) antiviral activity as well as the photophysical properties of this new compound are measured and compared with those of the parent compounds, hypericin and pseudohypericin. This tethered molecule exhibits excited-state behavior that is very similar to that of its parent compounds and antiviral activity that is identical, within experimental error, to that of its more closely related parent compound, pseudohypericin. The implications for a photodynamic therapy that is independent of external light sources are discussed.

Anthracenes↗