Biomedical subjects

Jun Wang

Publications and source records attributed to Jun Wang.

At least 433 records · Page 24Linked to original sources

PubMed2003

DNA immunization of the grafted liver by particle-mediated gene gun.

BACKGROUND: Direct DNA vaccination of liver allografts before transplantation may provide an effective strategy for inducing protective immunity to infection and malignancy. METHODS: In this study, the authors examined the feasibility of gene gun-mediated vaccination of liver grafts. Using plasmids expressing luciferase and green fluorescent proteins, their expression was tested in a graft liver. RESULTS: Protein expression was observed in the graft liver and significantly enhanced in hepatectomized rats. A short course of tacrolimus (FK506) also evoked the expression of these proteins. Effects of primary immunization to the liver on the humoral response were then tested using an expression plasmid encoding hepatitis B virus surface (HBs) antigen and were compared to that of skin immunization alone. The results showed that local immunization to the liver strongly induced antibody formation. Furthermore, the combination of an immunized partial liver graft with tacrolimus significantly enhanced antibody production against HBs antigen. CONCLUSIONS: A DNA vaccine to the liver may be one strategy for preventing infectious disease associated with liver transplantation under tacrolimus treatment.

Animals↗

PubMed2003

Capillary array electrophoresis with confocal fluorescence rotary scanner.

A capillary array electrophoresis system with a rotary confocal fluorescence scanner is reported. A high speed direct current rotary motor, combined with a rotary encoder and a reflection mirror, has been designed to direct the excitation laser beam precisely to a round array of capillaries which are symmetrically distributed around the motor. The rotary encoder is introduced to accurately orientate the position of each capillary and its output signal triggers the data acquisition system to record the fluorescence signal corresponding to each capillary. Separation of enantiomers of glutamic acid, methionine and tryptophan with different additives are demonstrated by this system. The experimental results indicate that this setup can be used to optimize separation methods for capillary electrophoresis as quickly as possible.

Amino Acids↗

PubMed2003

Effect of side-chain structures on gene transfer efficiency of biodegradable cationic polyphosphoesters.

Cationic polyphosphoesters (PPEs) with different side-chain charge groups were designed and synthesized as biodegradable gene carriers. Poly(N-methyl-2-aminoethyl propylene phosphate) (PPE-MEA), with a secondary amino group (-CH(2)CH(2)NHCH3) side chain released DNA in several hours at N/P (amino group of polymer to phosphate group of DNA) ratios from 0.5 to 5; whereas PPE-HA, bearing -CH(2)(CH2)(4)CH(2)NH(2) groups in the side chain, did not release DNA at the same ratio range for 30 days. Hydrolytic degradation and DNA binding results suggested that side chain cleavage, besides the polymer degradation, was the predominant factor affected the DNA release and transfection efficiencies. The side chain of PPE-MEA was cleaved faster than that of PPE-HA, resulting poor cellular uptake and no transgene expression for PPE-MEA/DNA complexes in COS-7 cells at charge ratios from 4 to 12. In contrast, PPE-HA/DNA complexes were stable enough to be internalized by cells and effected gene transfection (3400 folds higher than background at a charge ratio of 12). Interestingly, gene expression levels mediated by PPE-MEA and PPE-HA in mouse muscle following intramuscular injection of complexes showed a reversed order: PPE-MEA/DNA complexes mediated a 1.5-2-fold higher luciferase expression in mouse muscle as compared with naked DNA injection, while PPE-HA/DNA complexes induced delayed and lowered luciferase expression than naked DNA. These results suggested that the side chain structure is a crucial factor determining the mechanism and kinetics of hydrolytic degradation of PPE carriers, which in turn influenced the kinetics of DNA release from PPE/DNA complexes and their transfection abilities in vitro and in vivo.

Animals↗

PubMed2003

Functioning styles of personality disorders and five-factor normal personality traits: a correlation study in Chinese students.

BACKGROUND: Previous studies show that both the categorical and dimensional descriptors of personality disorders are correlated with normal personality traits. Recently, a 92-item inventory, the Parker Personality Measure (PERM) was designed as a more efficient and precise first-level assessment of personality disorders. Whether the PERM constructs are correlated with those of the five-factor models of personality needs to be clarified. METHODS: We therefore invited 913 students from poly-technical schools and colleges in China to answer the PERM, the Five-Factor Nonverbal Personality Questionnaire (FFNPQ), and the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ). RESULTS: Most personality constructs had satisfactory internal alphas. PERM constructs were loaded with FFNPQ and ZKPQ traits clearly on four factors, which can be labelled as Dissocial, Emotional Dysregulation, Inhibition and Compulsivity, as reported previously. FFNPQ Openness to Experience, Conscientiousness and Extraversion formed another Factor, named Experience Hunting, which was not clearly covered by PERM or ZKPQ. CONCLUSION: The PERM constructs were loaded in a predictable way on the disordered super-traits, suggesting the PERM might offer assistance measuring personality function in clinical practice.

Adolescent↗

PubMed2003

Discovery of a small molecule that inhibits cell division by blocking FtsZ, a novel therapeutic target of antibiotics.

The emergence of bacterial resistance to antibiotics is a major health problem and, therefore, it is critical to develop new antibiotics with novel modes of action. FtsZ, a tubulin-like GTPase, plays an essential role in bacterial cell division, and its homologs are present in almost all eubacteria and archaea. During cell division, FtsZ forms polymers in the presence of GTP that recruit other division proteins to make the cell division apparatus. Therefore, inhibition of FtsZ polymerization will prevent cells from dividing, leading to cell death. Using a fluorescent FtsZ polymerization assay, the screening of >100,000 extracts of microbial fermentation broths and plants followed by fractionation led to the identification of viriditoxin, which blocked FtsZ polymerization with an IC50 of 8.2 microg/ml and concomitant GTPase inhibition with an IC50 of 7.0 microg/ml. That the mode of antibacterial action of viriditoxin is via inhibition of FtsZ was confirmed by the observation of its effects on cell morphology, macromolecular synthesis, DNA-damage response, and increased minimum inhibitory concentration as a result of an increase in the expression of the FtsZ protein. Viriditoxin exhibited broad-spectrum antibacterial activity against clinically relevant Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci, without affecting the viability of eukaryotic cells.

Anti-Bacterial Agents↗

PubMed2003

[Correlation between iron levels and degeneration of dopaminergic neurons in rat nigrostriatal system during the early 6-OHDA lesions in medial forebrain bundle].

In the present study, using fast cyclic voltammetry (FCV), atomic absorption/flame emission spectrophotometry and immunohistochemistry, we investigated the correlation between iron levels and degeneration of dopaminergic neurons in rat nigrostriatal system during the early 6-OHDA lesions in the medial forebrain bundle (MFB). The results showed that 1 d or 3 d after lesions in MFB, there was a 45% or 66% reduction, respectively, in the density of tyrosine hydroxylase (TH) immunoreactive cells in the substantia nigra (SN) of the lesioned side accompanied by an increase in iron staining intensity and iron concentration; while there was no change in dopamine (DA) release in the striatum (Str) of the lesioned side compared with the unlesioned side and the normal rats. There was no difference in the iron staining and concentration of SN and DA release of Str on the lesioned side between one-day group and three-days group. These results suggest that an iron level elevation in SN may be involved at the early stage of degeneration of DA neurons in SN. However, DA release in Str was unchanged due to the immense compensatory mechanism of DA system.

Animals↗

PubMed2003

Amplified voltammetric detection of DNA hybridization via oxidation of ferrocene caps on gold nanoparticle/streptavidin conjugates.

Gold nanoparticle/streptavidin conjugates covered with 6-ferrocenylhexanethiol were attached onto a biotinylated DNA detection probe of a sandwich DNA complex. Due to the elasticity of the DNA strands, the ferrocene caps on gold nanoparticle/streptavidin conjugates are positioned in close proximity to the underlying electrode modified with a mixed DNA capture probe/hexanethiol self-assembled monolayer and can undergo reversible electron-transfer reactions. A detection level, down to 2.0 pM (10 amol for the 5 microL of sample needed) for oligodeoxynucleotide samples was obtained. The amplification of the voltammetric signals was attributed to the attachment of a large number of redox (ferrocene) markers per DNA duplex formed. The ferrocene oxidation current increased with the target concentration and began to level off at a target concentration of 10 nM. An Excellent linearity was found within the range between 6.9 and 150.0 pM and reasonable relative standard deviations (between 3.0 and 13.0%) were obtained. The amenability of this method to the analyses of polynucleotides (i.e., PCR products of the pre-S gene of hepatitis B virus in serum samples) was also demonstrated. The method is shown to be simple, selective, reproducible, and cost-effective and does not require labeling of the DNA targets.

DNA↗

PubMed2003

Global dissipativity of continuous-time recurrent neural networks with time delay.

This paper addresses the global dissipativity of a general class of continuous-time recurrent neural networks. First, the concepts of global dissipation and global exponential dissipation are defined and elaborated. Next, the sets of global dissipativity and global exponentially dissipativity are characterized using the parameters of recurrent neural network models. In particular, it is shown that the Hopfield network and cellular neural networks with or without time delays are dissipative systems.

Journal Article↗

PubMed2003

Anomalous difference signal in protein crystals.

A scattering-angle-dependent formula is obtained for estimation of anomalous diffraction signals in Friedel pairs in protein crystals. In addition to the angle dependences of atomic form factor and temperature factor, a correlation form factor is introduced for the first time to take into account anomalous-scattering clusters such as disulfide bonds. Good agreements with experimental observations suggest that such correlated anomalous difference signals may be visible from measurements before a complete structural solution is obtained.

Crystallization↗

PubMed2003

Folding behaviors of lattice model proteins with three kinds of contact potentials.

The interaction potentials between the amino acids are very important in the study of protein folding and design. In this work, the folding behaviors of lattice model protein chains are studied using three kinds of contact potentials between the beads. For these three cases, a number of sequences are designed using the Z-score method, and then their folding behaviors are obtained via Monte Carlo simulations for different sizes of the chains. It is found that the proper weakening of hydrophobicity may speed up the folding and the elimination of the mixing interaction terms may deteriorate the foldability. The different features of the foldability are discussed by comparing the characteristics of the energy landscapes of these model chains. The formations of various contacts are also analyzed, which provide us with some microscopic information on the model systems and interaction potentials.

Biophysics↗

PubMed2003

[Expressions of GDNF, GDNFR alpha and Ret proteins in the brain of rats with seizures induced by pilocarpine].

OBJECTIVE: To observe the dynamic expression of GDNF and their receptors in the brain of rats after status epilepticus(SE). METHODS: The lithium-pilocarpine-induced rat SE model was used. The expression patterns of GNDF, GDNFR alpha and Ret were observed dynamically with immunohisto-chemical technique, and the extent of neuron damage was assessed by HE stain. RESULTS: (1) GDNF positive cells began to appear 2 hours after SE and reached the peak in 1 and 3 days, then decreased to the normal level; (2) GDNFR alpha positive cells in the cortex increased rapidly to the peak 2 hours after SE, and only few such cells were found in hippocampus; (3) Ret positive cells were found both in the cortex and hippocampus, with the maximum of expressions 6-8 hours after SE; (4) There were some connection between GDNF expression levels and extent of neurons damage. CONCLUSION: There exist time-dependent upregulations of GDNF, GDNFR alpha and Ret protein in the cortex and hippocampus of rats after SE. GDNF and their receptors involve in the response to neuron damage after SE, which might have the protective effect of neurons.

Animals↗

PubMed2003

In vivo quantification of optical contrast agent dynamics in rat tumors by use of diffuse optical spectroscopy with magnetic resonance imaging coregistration.

We present a study of the dynamics of optical contrast agents indocyanine green (ICG) and methylene blue (MB) in an adenocarcinoma rat tumor model. Measurements are conducted with a combined frequency-domain and steady-state optical technique that facilitates rapid measurement of tissue absorption in the 650-1000-nm spectral region. Tumors were also imaged by use of contrast-enhanced magnetic resonance imaging (MRI) and coregistered with the location of the optical probe. The absolute concentrations of contrast agent, oxyhemoglobin, deoxyhemoglobin, and water are measured simultaneously each second for approximately 10 min. The differing tissue uptake kinetics of ICG and MB in these late-stage tumors arise from differences in their effective molecular weights. ICG, because of its binding to plasma proteins, behaves as a macromolecular contrast agent with a low vascular permeability. A compartmental model describing ICG dynamics is used to quantify physiologic parameters related to capillary permeability. In contrast, MB behaves as a small-molecular-weight contrast agent that leaks rapidly from the vasculature into the extravascular, extracellular space, and is sensitive to blood flow and the arterial input function.

Adenocarcinoma↗

PubMed2003

Coregistration of diffuse optical spectroscopy and magnetic resonance imaging in a rat tumor model.

We report coregistration of near-infrared diffuse optical spectroscopy (DOS) and magnetic resonance imaging (MRI) for the study of animal model tumors. A combined broadband steady-state and frequency-domain apparatus was used to determine tissue oxyhemoglobin, deoxyhemoglobin, and water concentration locally in tumors. Simultaneous MRI coregistration provided structural (T2-weighted) and contrast-enhanced images of the tumor that were correlated with the optical measurements. By use of Monte Carlo simulations, the optically sampled volume was superimposed on the MR images, showing precisely which tissue structure was probed optically. DOS and MRI coregistration measurements were performed on seven rats over 20 days and were separated into three tumor tissue classifications: viable, edematous, and necrotic. A ratio of water concentration to total hemoglobin concentration, as measured optically, was performed for each tissue type and showed values for edematous tissue to be greater than viable tissue (1.2 +/- 0.49 M/microM versus 0.48 +/- 0.15 M/microM). Tissue hemoglobin oxygen saturation (StO2) also showed a large variation between tissue types: viable tissue had an optically measured StO2 value of 61 +/- 5%, whereas StO2 determined for necrotic tissue was 43 +/- 6%.

Adenocarcinoma↗

PubMed2003

[The epidemiologic characteristics of patients with severe acute respiratory syndrome (SARS)].

OBJECTIVE: To study the epidemiologic characteristics of patients with Severe Acute Respiratory Syndrome (SARS) and to investigate the transmission way of the disease. METHODS: A total of 80 clinically diagnosed SARS patients was enrolled in this study. RESULTS: The result showed that 72/80 patients had exposed to SARS patient, and the least contact time was only 20 minutes, the average incubation period was (7.6 +/- 4.3) days (range 2 to 20 days); 53 (66.3%) subjects were hospital stuffs in this group, and 92.5% hospital stuffs (49/53) and 85.2% non-hospital stuffs (23/27) had the history of direct contact with SARS patients, respectively. The incubation period for the hospital stuffs and non-hospital stuffs were similar. More nurses (54.7%) were infected than doctors (34%) and nurse assistance (11.3%). The lack of isolation and self-protection was the most important factor for the hospital infection, and early isolation could efficiently prevent the spread of the disease. CONCLUSION: Close exposure was the most important way for the transmission of SARS and the aggregation of the disease is common. The incubation period was around 7 days. The efficient isolation and self-protection could reduce the infection and prevent the spread of the disease.

Adolescent↗

PubMed2003

[The clinical characteristics and outcome of 45 early stage patients with SARS].

OBJECTIVE: To investigate the clinical characteristics and therapeutic effect in the early stage of patients with Severe Acute Respiratory Syndrome (SARS). METHODS: A total of 45 clinical diagnosed SARS patients were enrolled in the study. RESULTS: 43 (95.6%) of all 45 patients had exposure to SARS patients and the average incubation time was (7.3 +/- 4.7) days (range 2 to 20 days). The clinical features including fatigue (60%), dry cough (68.9%), dyspnea (53.3%), joint pain (26.7%) and diarrhea (26.7%). The laboratory test show that 33% patients with leukopenia and thrombocytopenia, 53.3% with elevated serum aminotransferase and 26.6% with increased creatinine kinase levels. The occurrence of abnormal chest radiographs was (4.2 +/- 2.9) days from the onset, and CT scanning was better than X-ray in the early diagnosis. The average time for the progression and improvement of the chest radiographs were (9.3 +/- 4.1) and (14.5 +/- 5.0) days, respectively. The administration of corticosteroids was started (4.8 +/- 3.5) days from the onset and the maximal dosage using of steroids was (8.4 +/- 3.9) days. There was a significant difference in the dosage of steroid between severe and mild patients [(610.6 +/- 212.4) mg/day vs (268.1 +/- 202.5) mg/day, P < 0.001)]. The IgG antibody was detected in 22 out of 34 (64.7%) patients and the average time for the occurrence of antibody was (18.2 +/- 6.4) days (range 9-27 days). CONCLUSION: Exposure to the SARS patients happened in most patients. The most common clinical features were fever and fatigue. The most common laboratory abnormalities were leukopenia and thrombocytopenia. Serum antibody was not detected until on the 9th day of the course of illness; CT is a more sensitive method for detection of the abnormal chest radiographs than regular X-ray test. The early usage of cortiscosteroids was an efficient method for the treatment, and the dosage of steroids should be individualized.

Adrenal Cortex Hormones↗

PubMed2003

Polyphosphoesters in drug and gene delivery.

Polymers with repeating phosphoester bonds in the backbone are structurally versatile, and biodegradable through hydrolysis, and possibly enzymatic digestion at the phosphoester linkages under physiological conditions. These biodegradable polyphosphoesters are appealing for biological and pharmaceutical applications because of their potential biocompatibility and similarity to bio-macromolecules such as nucleic acids. In the first part of this review, we will focus on one particular structure synthesized by extending oligomeric lactide prepolymers with ethylphosphate groups. This amorphous to semi-crystalline polymer is promising in delivering anti-cancer therapeutics in the form of microspheres. In the second half, we will discuss the conjugation of charged groups to the side chain of the phosphate, constituting one of the few biodegradable cationic polymers in the field for non-viral gene delivery. Capable of delivering exogenous genes to a cell nucleus or providing an extracellular sustained release of DNA, these cationic polyphosphoesters also serve as a valuable model to understand the important characteristics that render a polymer an effective gene carrier.

Animals↗

PubMed2003

Recursive direct phasing with reference-beam diffraction.

The reference-beam diffraction technique provides a practical way to measure a large number of triplet phases in a standard oscillating-crystal diffraction experiment for protein crystals. The triplet-phase data set from such reference-beam measurements contains a unique phase-occurrence pattern that leads to a new recursive phasing algorithm for the individual structure-factor phases. Application of the new algorithm is demonstrated for tetragonal lysozyme using 7360 triplet phases measured in a reference-beam experiment with a median phase discrepancy of 45 degrees. An electron-density map obtained using this phasing algorithm and the measured triplet phases shows good agreement with the known protein structure.

Algorithms↗

PubMed2003

[Relationship between the human zygote type and embryo implantation potential].

OBJECTIVE: To evaluate the relationship between the human zygote types and the quality of embryos, the embryo implantation rate, the multiple pregnancy rate in IVF-ET. METHODS: By using the criteria based on the number and distribution of nucleolar precursor bodies in each pronucleus, zygotes were divided into 0-5 types according to Tesarik's methods. In order to understand the best embryo rates that came from various types of zygote, on the one hand we compared the embryo implantation rate of different kinds of zygotes, on the other hand we defined the relationship between the multiple pregnancy rate and embryo which came from 0 type or non-0 type zygotes. RESULTS: The fine embryo rate coming from 0 type zygotes wasn't different from other types. Due to using of 0 type zygote criteria, embryo implantation rate of the experimental group was high. Along with the embryo number coming from 0 type zygotes was growing, the multiple pregnancy rate was increasing. CONCLUSION: Fine embryos coming from 0 type zygotes have high implantation potency. If the transferred fine embryos came from 0 type zygotes completely, we should limit the number of transferred embryos in order to reduce the multiple pregnancy rate.

Cell Nucleus↗