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Biomedical subjects

Feng Li

Publications and source records attributed to Feng Li.

At least 73 records · Page 4Linked to original sources
PubMed2006

[Immune responses in rhesus induced by recombinant adenovirus Ad-LMP2].

BACKGROUND: To observe the LMP2 specific cellular and humoral immune responses after immunization with recombinant adenovirus Ad-LMP2 in rhesus. METHODS: The rhesuses were immunized with Ad-LMP2 through intra muscular injection in three groups, high dosage (4.5 x 10(11) VP/kg), medium dosage (1.5 x 10(11) VP/kg) and low dosage (0.5 x 10(11) VP/kg) groups. They were totally immunized six times at intervals of 5 days. The specific cellular immune responses were tested during the 7th week by ELISPOT after immunization. And the titers of anti-LMP2 antibody were tested by EIA throughout the period of immunization. RESULTS: LMP2 induced specific cellular and humoral immune responses in all three dosage group. The potency of immune responses was related with the dosage of immunization. Higher dosage elicited more potent immune response. Both the neutralizing antibody to adenovirus and anti-LMP2 antibody could be detected from 2 weeks after immunization. They would reach the peak during 3-4 weeks after immunization, then declined during the 7th week after immunization. CONCLUSION: The recombinant adenovirus LMP2 could induce specific cellular and humoral responses in rhesus after immunization.

Adenoviridae↗
PubMed2006

Integrating PET and CT information to improve diagnostic accuracy for lung nodules: A semiautomatic computer-aided method.

UNLABELLED: Our objective was to develop and evaluate 3 semiautomatic computer-aided diagnostic (CAD) schemes for distinguishing between benign and malignant pulmonary nodules by use of features extracted from CT, 18F-FDG PET, and both CT and 18F-FDG PET. METHODS: We retrospectively collected 92 consecutive cases of pulmonary nodules (<3 cm) in patients who underwent both thoracic CT and whole-body PET/CT. Forty-two of the nodules were malignant and 50 benign, as confirmed by pathologic examination and clinical follow-up. The interval between CT and PET was less than 1 mo. Four clinical parameters, including patient age, sex, smoking status, and history of previous malignancy, were used for the CAD schemes. Sixteen CT features based on size, shape, margin, and internal structure of nodules were independently rated subjectively by 2 chest radiologists. Four PET features were viewed on a PET/CT workstation. CAD schemes based on clinical parameters together with CT features, PET features, and both CT and PET features were then used to differentiate benign from malignant nodules. Finally, the output from the CAD schemes was evaluated by use of receiver-operating-characteristic analysis. RESULTS: When we used clinical parameters and CT features as input units (CAD scheme 1), the area under the receiver-operating-characteristic curve (A(z) value) of the CAD scheme was 0.83. When we used clinical parameters and PET features as input units (CAD scheme 2), the A(z) value for the computer output was 0.91. However, when we used all data as input units (CAD scheme 3), the A(z) value for the computer output was 0.95. The performance of CAD scheme 3 was better than that of CAD scheme 1 or 2. A statistically significant difference existed between the A(z) values of CAD schemes 3 and 2 (P = 0.037) and between those of CAD schemes 3 and 1 (P = 0.015). CONCLUSION: Our CAD scheme based on both PET and CT was better able to differentiate benign from malignant pulmonary nodules than were the CAD schemes based on PET alone and CT alone.

Aged↗
PubMed2006

[Content comparison of polyamines compounds in Penis et Testis Cervi].

OBJECTIVE: To compare the content of the main polyamines compositions in 10 samples of Penis et Testis Cervi from different species and habitats. MEHTODs: The putrescine spermidine and spermine in Penis et Testis Cervi were determined by HPLC. RESULTS: The contents of total Polyamine and 3 kinds of polyamines compositions in all samples were different. CONCLUSION: The content of the main polyamines compositions can be used to control the quality of Penis et Testis Cervi.

Animals↗
PubMed2006

[The design and applications of a non-invasive intelligent detector for cardiovascular functions].

An apparatus based on a high sensitive sensor which detects cardiovascular functions is introduced in this paper. Some intelligent detecting technologies, such as syntactic pattern recognition and a medical expert system are used in this detector. Its embedded single-chip microcomputer processes and analyzes pulse signals for gaining automatically the parameters about heart, blood vessel and blood etc., so as to get the health evaluation, correct medical diagnosis and prediction of cardiovascular diseases.

Algorithms↗
PubMed2006

Establishment of cell free conversion system with biotin-labelled recombinant PrPsen expressed in E. coli.

OBJECTIVE: To report a protocol using biotin-labelled PrP protein in cell free conversion assay instead of isotope. METHODS: A hamster PrP protein (HaPrP) was expressed in E. coli and purified with HIS-tag affinity chromatograph. After being labelled with biotin, HaPrP was mixed with PrPSc preparation from scrapie strain 263K. RESULTS: Protease-resistant bands were detected after four-day incubation. CONCLUSION: The new conversion model provides a reliable, easily handling, and environment-friendly method for studies of prion and transmissible spongiform encephalopathies.

Animals↗
PubMed2006

[Glycinebetaine applied through roots protects the photosynthetic apparatus of tobacco seedlings under water stress].

Two tobacco (Nicotiana tabacum L.) cultivars (DHJ5210 and ZY100) with different drought tolerance were used to study the photosynthetic response to different water stress and the effects of glycinebetaine applied through roots on photosynthetic capacity. The physiological mechanisms of the improvement of tobacco photosynthesis by glycinebetaine applied through roots were analyzed. The results indicated that photosynthetic apparatus of tobacco leaves were more brittle and damaged by water stress, accompanied by negative changes of RWC (Fig. 2), chlorophyll content (Fig. 3), PSII photochemistry efficiency (Fig. 4), activity of Hill reaction (Fig. 5) and ATPase (Fig. 6), and the damage was more serious to ZY100 (drought sensitive cultivar) than DHJ5210 (drought resistant cultivar) under the same stress condition. Glycinebetaine applied through roots could be absorbed by tobacco roots and then accumulated in leaves (Fig. 1), which alleviated the decrease in photosynthetic variables of two cultivars and the improvement was more significant on ZY100 than DHJ5210. The positive function of glycinebetaine might be involved in its protective effect on antioxidant enzymes (Fig. 8), chloroplast protein and thylakoid membrane (Fig. 7).

Adaptation, Physiological↗
PubMed2006

[Chip-based capillary electrophoresis on-line coupled with atomic fluorescence spectrometry and its application to rapid speciation analysis].

Chip-based capillary electrophoresis (chip-CE) is under rapid progress due to its high efficiency, fast separation, little sample consumption and integration. Due to the short optical path (30-50 microm), the conventional UV absorbance cannot satisfy the chip detection needs. Atomic fluorescence spectrometer (AFS) is a selective and sensitive detector for hydride-forming elements. With the strong points of low cost and easy operation, AFS is attractive as an ideal detector of chip-CE for mercury, arsenic and selenium, etc. A few important practical aspects of coupling chip-CE to AFS are critically discussed. These include the design of the chip, chip-AFS interface, gas-liquid separator, AFS atomizer, and elimination of the effect of backpressure on separation. The application of the developed chip-CE-AFS to the mercury speciation analysis is highlighted.

English Abstract↗
PubMed2006

[Design of the image browser for PACS image workstation].

The design of PACS image workstation based on DICOM3.0 is introduced in the paper, then the designing method of the PACS image browser based on the control system theory is presented,focusing on two main units:DICOM analyzer and the information mapping transformer.

Data Display↗
PubMed2005

Suppression of cyclin-dependent kinase 5 activation by amyloid precursor protein: a novel excitoprotective mechanism involving modulation of tau phosphorylation.

Alzheimer's disease is cytopathologically characterized by loss of synapses and neurons, neuritic amyloid plaques consisting of beta-amyloid (Abeta) peptides, and neurofibrillary tangles consisting of hyperphosphorylated tau protein in susceptible brain regions. Abeta, which triggers a cascade of pathogenic events including tau phosphorylation and neuronal excitotoxicity, is proteolytically derived from beta-amyloid precursor protein (APP); the pathological and physiological functions of APP, however, remain undefined. Here we demonstrate that the level of tau phosphorylation in cells and brains deficient in APP is significantly higher than that in wild-type controls, resulting from activation of cyclin-dependent kinase 5 (CDK5) but not glycogen synthase kinase 3, the two major tau kinases. In addition, we show that overexpression of APP or its non-amyloidogenic homolog amyloid precursor-like protein 1 suppresses both basal and stress-induced CDK5 activation. The ectodomain of APP, sAPPalpha, is responsible for inhibiting CDK5 activation. Furthermore, neurons derived from APP-deficient mice exhibit reduced metabolism and survival rates and are more susceptible to excitotoxic glutamate-induced apoptosis. These neurons also manifest significant defects in neurite outgrowth compared with neurons from the wild-type littermates. The observed neuronal excitotoxicity/apoptosis is mediated through a mechanism involving CDK5 activation. Our study defines a novel neuroprotective function for APP in preventing tau hyperphosphorylation via suppressing overactivation of CDK5. We suggest that CDK5 activation, through a calcium/calpain/p25 pathway, plays a key role in neuronal excitotoxicity and represents an underlying mechanism for the physiological functions of APP.

Amyloid beta-Protein Precursor↗
PubMed2005

Hyperlipemia and oxidation of LDL induce vascular smooth muscle cell growth: an effect mediated by the HLH factor Id3.

Hyperlipemia and oxidized LDL (ox-LDL) are important independent cardiovascular risk factors. Ox-LDL has been shown to stimulate vascular smooth muscle cell (VSMC) proliferation. However, the effects of hyperlipemia and the molecular mechanisms mediating hyperlipemia and ox-LDL effects on VSMC growth are poorly understood. The helix-loop-helix (HLH) transcription factor, Id3, is a redox-sensitive gene expressed in VSMC in response to mitogen stimulation and vascular injury. Accordingly, we hypothesize that Id3 is an important mediator of ox-LDL and hyperlipemia-induced VSMC growth. Aortas harvested from hyperlipemic pigs demonstrated significantly more Id3 than normolipemic controls. Primary VSMC were stimulated with ox-LDL, native LDL, sera from hyperlipemic pigs, or normolipemic pigs. VSMC exposed to hyperlipemic sera demonstrated increased Id3 expression, VSMC growth and S-phase entry and decreased p21cip1 expression and transcription. Cells stimulated with ox-LDL demonstrated similar findings of increased growth and Id3 expression and decreased p21cip1 expression. Moreover, the effects of ox-LDL on growth were abolished in cells devoid of the Id3 gene. Results provide evidence that the HLH factor Id3 mediates the mitogenic effect of hyperlipemic sera and ox-LDL in VSMC via inhibition of p21cip1 expression, subsequently increasing DNA synthesis and proliferation.

Animals↗
PubMed2005

New insight into the solid electrolyte interphase with use of a focused ion beam.

The formation and evolution of the solid electrolyte interphase (SEI) film on the surface of natural graphite spheres in the electrolyte of 1 M LiPF6 in ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio 1:1) were investigated with use of focused ion beam (FIB) technology. Secondary electron FIB images clearly show the surface and cross-section morphology of the SEI film. The composition variation along the surface and cross section of the SEI film was also explored by the elemental line scan analysis (ELSA). The initial SEI film with an apparent thickness range of approximately 450 to approximately 980 nm is rough in morphology and nonuniform in composition, and contains small splits. After certain electrochemical cycles, the thickened SEI film displays microscale holes and obvious cracks on the surface, and the content of organic compounds increases. In addition, the concept of "internal SEI film" is first proposed based on the characterization of the cross section of the natural graphite spheres with the aid of FIB. Finally, the capacity fading mechanisms of the natural graphite spheres corresponding to different electrochemical stages are discussed.

Journal Article↗
PubMed2005

Could MYC induction of mitochondrial biogenesis be linked to ROS production and genomic instability?

MYC has been linked separately to genomic instability and to reactive oxygen species production, but the connection between these two processes has not been firmly established. Our recent study along with previous reports demonstrate that Myc induces nuclear encoded mitochondrial gene expression and mitochondrial biogenesis, thereby directly associating Myc's transcriptional properties, to the production of mitochondrial ROS and the promotion of genomic oxidative damage and genomic instability.

Animals↗
PubMed2005

Synthesis and rheological properties of polylactide/poly(ethylene glycol) multiblock copolymers.

Ring-opening polymerization of D,L-lactide was carried out in the presence of poly(ethylene glycol), using Zn powder as catalyst. The hydroxyl-capped PLA-PEG-PLA triblock copolymers were coupled with adipoyl chloride at different molar ratios under mild conditions. N-Dimethylaminopyridine (DMAP) was used as catalyst of the coupling reaction. The resulting PLA/PEG multiblock copolymers were characterized by various analytical techniques such as IR, 1H NMR, SEC, and DSC. Sol-gel transition properties of the multiblock copolymers were investigated by mechanical rheology. The data showed that the sol-gel transition temperature and the transition modulus increased with increasing molecular weight and the solution concentration of the multiblock copolymers. [Graph: see text] Variation of storage modulus (G') and loss modulus (G'') as a function of temperature for a 20% sample of MB3.

Adipates↗
PubMed2005

The effect of salt concentration on DNA conformation transition: a molecular-dynamics study.

We performed three 3-ns molecular dynamics simulations of d(CGCGAATTCGCG)2 using the AMBER 8 package to determine the effect of salt concentration on DNA conformational transitions. All the simulations were started with A-DNA, with different salt concentrations, and converged with B-DNA with similar conformational parameters. However, the dynamic processes of the three MD simulations were very different. We found that the conformation transition was slow in the solution with higher salt concentration. To determine the cause of this retardation, we performed three additional 1.5-ns simulations starting with B-DNA and with the salt concentrations corresponding to the simulations mentioned above. However, astonishingly, there was no delayed conformation evolution found in any of the three simulations. Thus, our simulation conclusion is that higher salt concentrations slows the A --> B conformation transition, but have no effect on the final stable structure. [Figure: see text].

Carbohydrates↗
PubMed2005

Ump1 extends yeast lifespan and enhances viability during oxidative stress: central role for the proteasome?

Increasing evidence suggests that the proteasome may play an important role in both oxidative stress response and cellular aging, although considerable controversy exists as to the exact role the proteasome plays in each of these paradigms. In the present study we examined the contribution of impaired proteasome function to the regulation of oxidative damage (oxidized protein levels) following the administration of oxidative stressors, and to the cytotoxicity observed in aging and oxidatively challenged cells. In these studies the preservation of proteasome-mediated protein degradation was achieved via increased expression of the proteasome assembly protein Ump1. We observed that Saccharomyces cerevisiae transformed to express increased levels of Ump1 exhibited increased viability in response to a variety of oxidative stressors (menadione, hydrogen peroxide, 4-hydroxynonenal). The increased viability observed in each of these paradigms was associated with an enhanced preservation of proteasome-mediated protein degradation, consistent with the preservation of proteasome function being sufficient to ameliorate oxidative stress-induced cytotoxicity. Interestingly, cells expressing Ump1 were observed to initially have robust elevations in oxidized protein levels following the addition of oxidative stressors, but exhibited a significantly reduced level of oxidized proteins following the removal of oxidative stressors. Cells expressing elevated levels of Ump1 also exhibited an enhanced preservation of proteasome-mediated protein degradation, and enhanced viability during stationary-phase aging. Taken together these data strongly support a role for the proteasome serving as a central regulator of cellular viability during oxidative stress and during aging.

Aging↗
PubMed2005

Cross dipole stacking in the crystal of distyrylbenzene derivative: the approach toward high solid-state luminescence efficiency.

Through adding two substituent phenyl groups on distyrylbenzene, we have obtained the cross stacking of 2,5-diphenyl-1,4-distyrylbenzene with two trans double bonds (trans-DPDSB) in crystalline state. In such a cross-stacking mode, the solid-state emission exhibits high-intensity, having characteristics similar to its single molecule. The organic light-emiiting diodes (OLEDs) with attractive performance have been achieved using trans-DPDSB as a light-emitting layer, and the amplified spontaneous emission of the needlelike crystals has been observed.

Benzene Derivatives↗
PubMed2005

Study on adsorption of glyphosate (N-phosphonomethyl glycine) pesticide on MgAl-layered double hydroxides in aqueous solution.

MgAl-layered double hydroxides with different interlayer anions (nitrate, carbonate and chloride) were evaluated for their abilities to adsorb the organic pesticide glyphosate (N-phosphonomethyl glycine, Gly). The adsorption isotherms of Gly on layered double hydroxides (LDHs) nitrate were described by the Langmuir equation at lower equilibrium concentration of Gly (C(e)<1.0 mmol/L), and the Gly adsorption capacity on LDHs increased with the layer charge density, i.e. the structural Al3+/Mg2+ ratio. Gly adsorption on LDHs nitrate generally occurred through two processes, external surface adsorption and interlayer anion exchange. The adsorption amount on LDHs at C(e)=1.0 mmol/L decreased in the order of interlayer anions: Cl(-)>NO3(-)>CO3(2-).

Aluminum Compounds↗