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Biomedical subjects

D Wei

Publications and source records attributed to D Wei.

At least 19 recordsLinked to original sources
PubMed2005

Magnetic field assisting DC electrodeposition: general methods for high-performance Ni nanowire array fabrication.

One-dimensional magnetic nanowires are generally thought to show fine axial magnetism for their special high aspect ratio of the shape. However, the magnetic nanowire arrays fabricated by DC electrodeposition in template pores always show a low squareness in parallel to the nanowire direction. We developed two general and simple methods to improve the squareness of the as-fabricated Ni nanowire arrays parallel to the nanowire direction. The nanowires are found to be polycrystalline. The magnetism of the nanowire is also analyzed based on the microstructure.

Journal Article↗
PubMed2004

Chemical-chemical interaction between cyanogenic toxicants and aldehydes: a mechanism-based QSAR approach to assess toxicological joint effects.

A QSAR approach was proposed to assess toxicological joint effects based on the mechanism of chemical-chemical interactions between cyanogenic toxicants and aldehydes. It has been observed that the chemical-chemical interaction between cyanogenic toxicants and aldehydes resulted in the formation of carbanion intermediates, and therefore this interaction led to different toxicological joint effects between cyanogenic toxicants and aldehydes. Analysis of this chemical-chemical interaction showed that the formation of carbanion intermediate highly depended on the charge of the carbon atom in the -CHO of aldehydes and this of the carbon atom (C*) in the carbochain of cyanogenic toxicant. By using the Hammett Constant (sigma(p)) to measure the charge of carbon atom in the -CHO of aldehydes, a mechanism-based QSAR approach (M = 0.316 - 4.386sigma(p) with r2 = 0.933, SE = 0.082, F = 55.389, p = 0.002, M = sum of toxic units) was proposed to assess the toxicological joint effects between alpha-hydroxy-isobutyronitrile and individual aliphatic aldehydes. Another one (M = 0.978 - 0.720sigma(p) with r2 = 0.852, SE = 0.152, F = 40.148, p = 0.0001) was also proposed to assess the toxicological joint effects between alpha-hydroxy-isobutyronitrile and individual aromatic aldehydes. Lastly, by using the charge of carbon atom (C*) in the carbochain of cyanogenic toxicant, a mechanism-based QSAR model (M = -0.161 - 7.721C* with r2 = 0.847, SE = 0.227, F = 27.657, p = 0.003) was derived to assess toxicological joint effects between p-nitrobenzaldehyde and cyanogenic toxicants.

Aldehydes↗
PubMed2003

Reversal of cancer multidrug resistance by tea polyphenol in KB cells.

Tea polyphenols, (-)-epigallocatechin gallate in particular, were examined for their modulating effects on the drug resistance KB-A-1 cells and drug sensitive KB-3-1 cells. Both KB-3-1 and KB-A-1 cells were equally sensitive to tea polyphenol and (-)-epigallocatechin gallate. When 10 microgram/ml (-)-epigallocatechin gallate or 40 microgram/ml tea polyphenol were present simultaneously with doxorubicin, the IC50 of doxorubicin on KB-A-1 cells decreased from 10.3 +/- 0.9 microgram/ml to 4.2 +/- 0.2 or 2.0 +/- 0.1 microgram/ml. Tea polyphenol and (-)-epigallocatechin gallate enhanced the cytotoxicity of doxorubicin on KB-A-1 cells by 5.2 and 2.5 times, respectively, but did not show a modulating effect on KB-3-1 cells. Both tea polyphenol and (-)-epigallocatechin gallate showed reversal effects on the multidrug resistance phenotype.

Camellia sinensis↗
PubMed2001

[Tumor targeted expression of adenovirus mediated CDglyTK gene regulated by irradiation via Egr-1 promoter].

OBJECTIVE: To construct adenoviral vecter of AdEgr-CD/TK in which CDglyTK gene was driven by Egr-1 promoter, and control the tumor targeted expression of CDglyTK gene by gamma irradiation so as to observe the effects of gene-radiotherapy of liver cancer. METHODS: Adenoviral vector of AdEgr-CD/TK was generated through homologous recombination in bacteria. The expression of CDglyTK gene in MM45T. Li cells infected with AdEgr-CD/TK and exposed to different doses of gamma irradiation were analyzed, and the relative survival rate of the cells in presence of prodrugs 5-FC and GCV was tested. In addition, the tumor suppression effects of different treatments were investigated in 64 mice bearing liver cancer by observing the size of tumor at interval of four days. RESULTS: In vitro experiment showed that gamma irradiation markedly and dose-dependently induced CDglyTK expression in MM45T. Li tumor cells, and significantly enhanced the sensitivity of MM45T. Li cells infected with AdEgr-CD/TK to prodrugs 5-FC or GCV resulting in cell being killed (P < 0.01). A synergetic cytotoxic effect was found when both 5-FC and GCV were added. In vivo experiment revealed that, compared with other control treatments, intratumoral injection of AdEgr-CD/TK combined with intraperitoneal injection of GCV + 5-FC and TLI obviously suppressed tumor growth (P < 0.01), with 30% of the tumor eradicated completely while without causing the increase of whole body cytotoxic effect. CONCLUSION: Tumor targeted expression of CDglyTK gene under the control of irradiation represents a novel strategy for safe and effective gene therapy of cancer and might have wide application in the future.

Adenoviridae↗
PubMed2001

Conformational dynamics of an alanine dipeptide analog: an ab initio molecular dynamics study.

An ab initio molecular dynamics (MD) simulation technique employing the Born-Oppenheimer approach in the framework of a Gaussian implementation of Kohn-Sham density functional theory is used to study the gas-phase conformational dynamics of an alanine dipeptide analog. It is found that conformational transformation between C5 and C7(eq) occurs on the picosecond time scale. Classical MD simulations using most of the popular force fields do not yield a transition even after nanoseconds. An analysis is given of the difference, for this small gas-phase system, between ab initio MD and traditional MD simulation using force fields.

Alanine↗
PubMed2001

Systemic administration of a matrix-targeted retroviral vector is efficacious for cancer gene therapy in mice.

Targeting cytocidal vectors to tumors and associated vasculature in vivo is a long-standing goal of human gene therapy. In the present study, we demonstrated that intravenous infusion of a matrix (i.e., collagen)-targeted retroviral vector provided efficacious gene delivery of a cytocidal mutant cyclin G1 construct (designated Mx-dnG1) in human cancer xenografts in nude mice. A nontargeted CAE-dnG1 vector (p = 0.014), a control matrix-targeted vector bearing a marker gene (Mx-nBg; p = 0.004), and PBS served as controls (p = 0.001). Enhanced vector penetration and transduction of tumor nodules (35.7 +/- 1.4%, mean +/- SD) correlated with therapeutic efficacy without associated toxicity. Kaplan-Meier survival studies were conducted in mice treated with PBS placebo, the nontargeted CAE-dnG1 vector, and the matrix-targeted Mx-dnG1 vector. Using the Tarone log-rank test, the overall p value for comparing all three groups simultaneously was 0.003, with a trend that was significant to a level of 0.004, indicating that the probability of long-term control of tumor growth was significantly greater with the matrix-targeted Mx-dnG1 vector than with the nontargeted CAE-dnG1 vector or PBS placebo. The present study demonstrates that a matrix-targeted retroviral vector deployed by peripheral vein injection (1) accumulated in angiogenic tumor vasculature within 1 hr, (2) transduced tumor cells with high-level efficiency, and (3) enhanced therapeutic gene delivery and long-term efficacy without eliciting appreciable toxicity.

Animals↗
PubMed2001

Photosonochemical degradation of phenol in water.

The combination of ultrasound (US) and photochemistry has been used to degrade an aqueous solution of phenol. It was considerably more effective than ultrasound or ultraviolet (UV) light alone. Based on the results of total organic carbon (TOC) removal, it was shown that the synergistic action of ultrasound and ultraviolet light existed. Identification of the first intermediates of the reaction (hydroquinone, catechol, benzoquinone and resorcin) indicates that OH radicals are involved in the photosonochemical degradation mechanisms. The effects of parameters such as pH, saturating gases, and Fe2+ on the photosonochemical degradation have been studied. The experimental results have shown that lower pH and higher concentration of dissolved oxygen favor the phenol degradation and that the presence of Fe2+ enhanced TOC removal of phenol solutions.

Disinfectants↗
PubMed2001

Photosonochemical degradation of trichloroacetic acid in aqueous solution.

The degradation of trichloroacetic acid (TCA) was studied with ultraviolet (UV) photolysis, ultrasound (US) sonolysis and their combination. It was found that the degradation in the combined processes was more significant than in the UV photolysis or sonolysis alone. The effects of pH and dissolved gases on the rate of photosonochemical degradation of TCA were investigated and the degradation kinetics, mechanism and possible degradation products were discussed in detail.

Caustics↗
PubMed2001

Progressive study and robustness test of QSAR model based on quantum chemical parameters for predicting BCF of selected polychlorinated organic compounds (PCOCs).

Systematic analyses on the effects of chemical structures of 31 polychlorinated organic compounds (PCOCs) on their bioconcentration behavior in rainbow trout (Oncorhynchus mykiss) were conducted using quantitative structure-activity relationship (QSAR) techniques. The cluster analyses of individual variables as well as the quality control chart of QSAR model implies the existence of outliers, while the simulation model excluding such samples showed an extreme robustness even if it was tested with different methods. Furthermore, the quantum chemical parameters entering into QSAR model were used to describe the bioconcentration pathways, and the results indicated that bioconcentration behaviors of selected compounds were complicated processes involving permeation stages as well as bio-chemical reaction stages.

Animals↗
PubMed2001

Characterization of t(11;19)(q23;p13.3) by fluorescence in situ hybridization analysis in a pediatric patient with therapy-related acute myelogenous leukemia.

This case presents a Caucasian girl diagnosed with early pre-B cell acute lymphoblastic leukemia at age 2 years. The only chromosomal anomaly detected in her bone marrow cells at this time was an add(12p). By age 4 years, she had a bone marrow and central nervous system (CNS) relapse of ALL and was treated with chemotherapy that included etoposide. She was in complete remission for 2 years following chemotherapy with etoposide, but later developed therapy-related acute myeloid leukemia (t-AML). At this time, a t(11;19)(q23;p13.3) rearrangement was detected in her bone marrow cells. The AML relapsed again 1 year after allogeneic bone marrow transplant (BMT). The presence of a chromosome 11 abnormality involving band 11q23 in this patient suggests that the transformation from ALL to t-AML was a consequence of etoposide included in her chemotherapy. Studies have shown that the 11q23 breakpoint in the t(11;19) rearrangement is consistent, and involves the MLL gene in t-AML patients. However, the breakpoint in 19p is variable in that it could be located either at 19p13.1 or 19p13.3 and thus could involve either of two genes: ELL (11-19 lysine-rich leukemia gene) on 19p13.1 or ENL (11-19 leukemia gene) on 19p13.3. In this study, the t(11;19)(q23;p13.3) was further characterized and the breakpoint regions were defined by fluorescence in situ hybridization (FISH) analysis.

Child, Preschool↗
PubMed2001

High-throughput high-performance liquid chromatography/mass spectrometry for modern drug discovery.

High-throughput high-performance liquid chromatography/mass spectrometry can be used in the analysis of high-throughput organic synthesis products, bioanalytical target analysis for preclinical and clinical studies, and early absorption, distribution, metabolism and excretion (ADME) screening. New techniques are emerging, including system automation, faster analysis, programmed multiple extraction and analysis columns, multiple electrospray ionization channels, and automated 96-well sample preparation.

Chromatography, High Pressure Liquid↗
PubMed2001

Inhibition of HIV-1 infection by down-regulation of the CXCR4 co-receptor using an intracellular single chain variable fragment against CXCR4.

CXCR4 is the major co-receptor used by X4 strains of human immunodeficiency virus type I (HIV-1). In HIV-1-infected patients, the appearance of X4 strains (T cell line-tropic) correlates with disease progression. Since its discovery, the CXCR4 co-receptor has been a major target for different agents which block its function, such as stromal-derived factor 1alpha (SDF-1alpha) and the anti-CXCR4 monoclonal antibody, 12G5. In the present studies, the 12G5 hybridoma was used to construct a single-chain variable antibody fragment (SFv). Murine leukemia virus (MLV) and simian virus 40 (SV(40)) were utilized as delivery vehicles for the anti-CXCR4 SFv. Intracellular expression of the anti-CXCR4 SFv led to down-regulation of this critical co-receptor, as demonstrated by immunostaining. This effect significantly and specifically protected transduced cells from challenge with HIV-1, as measured by HIV-1 p24 antigen expression. Inhibition of HIV-1 replication was specific for X4 HIV-1 strains as demonstrated by MAGI assays. HeLa-CD4/betagal-CCR5 cells expressing the anti-CXCR4 SFv showed significant inhibition of infectivity by the X4 HIV-1 strain NL4-3, but not with the R5 HIV-1 strain Bal. Thus, this anti-HIV-1 molecular therapy has the potential to inhibit HIV-1 replication and virion spread. Targeting CXCR4 by intracellular immunization could be of additional benefit to certain HIV-1-infected patients on highly active antiretroviral therapy (HAART).

Animals↗
PubMed2001

Normal human fibroblasts express pattern recognition receptors for fungal (1-->3)-beta-D-glucans.

Fungal cell wall glucans nonspecifically stimulate various aspects of innate immunity. Glucans are thought to mediate their effects via interaction with membrane receptors on macrophages, neutrophils, and NK cells. There have been no reports of glucan receptors on nonimmune cells. We investigated the binding of a water-soluble glucan in primary cultures of normal human dermal fibroblasts (NHDF). Membranes from NHDF exhibited saturable binding with an apparent dissociation constant (K(D)) of 8.9 +/- 1.9 microg of protein per ml and a maximum binding of 100 +/- 8 resonance units. Competition studies demonstrated the presence of at least two glucan binding sites on NHDF. Glucan phosphate competed for all binding sites, with a K(D) of 5.6 microM (95% confidence interval [CI], 3.0 to 11 microM), while laminarin competed for 69% +/- 6% of binding sites, with a K(D) of 3.7 microM (95% CI, 1.9 to 7.3 microM). Glucan (1 microg/ml) stimulated fibroblast NF-kappaB nuclear binding activity and interleukin 6 (IL-6) gene expression in a time-dependent manner. NF-kappaB was activated at 4, 8, and 12 h, while IL-6 mRNA levels were increased by 48% at 8 h. This is the first report of pattern recognition receptors for glucan on human fibroblasts and the first demonstration of glucan binding sites on cells other than leukocytes. It also provides the first evidence that glucans can directly modulate the functional activity of NHDF. These results provide new insights into the mechanisms by which the host recognizes and responds to fungal (1-->3)-beta-D-glucans and suggests that the response to glucans may not be confined to cells of the immune system.

Binding Sites↗
PubMed2001

[Combined gene therapy for murine liver cancer with interleukin-18 and cytosine deaminase genes].

OBJECTIVE: To investigate the synergistic antitumor effects of murine IL-18 and CD/5FC gene therapy on mice bearing liver cancer. METHODS: A retrovirus vector pGCEN/IL-18 containing murine interleukin-18 gene was constructed. The retrovirus carrying IL-18 gene was used to infect murine liver cancer cell MM45T.Li, and proved to secret biological active IL-18. In mice bearing liver cancer, (60)Co-irradiated MM45T.Li/IL-18 vaccine was inoculated subcutaneously once a week for two weeks, and/or AdCD was injected intratumorally with 5FC injected i.p. for 8 days. RESULTS: Thirty days from the treatment, the tumor volume of control group was 1580 approximately 1625 mm(3), MM45T.Li/IL-18 vaccine group was 366 +/- 159 mm(3), AdCD/5FC group was 438 +/- 65 mm(3), and combined IL-18 and AdCD/ 5FC therapy group was 15 +/- 7 mm(3) (P<0.05). The tumor volume in single gene therapy group reduced to the smallest after three-week treatment, but grew large again, while the tumor volume in combined therapy group still remained small. The median survival time in control group was 50.0 approximately 51.5 days, MM45T.Li/IL-18 group was 65 days, AdCD/5FC group was 57 days versus 75 days for combined gene therapy group (P<0.05), and with more abundant infiltration of CD4+ and CD8+ lymphocytes around the tumor in combined gene therapy group. CONCLUSIONS: Combined gene therapy with IL-18 and CD/5FC can reduce the tumor volume and elicit the antitumor immunity of the host, which is superior to the single gene therapy for murine liver cancer.

Animals↗
PubMed2001

[Influence of fertilization depth on root system senescence of upland wheat after anthesis].

A soil column study showed that fertilization in a depth of 20-40 cm sustained the activities of superoxide dismatase (SOD) and catalase (CAT) in root system at a high level, meanwhile the root system vigor, the soluble protein content in root system decreased slowly, and the content of malondiadehyde (MDA) in wheat root system decreased, which delayed its senescence. It is considered that the depth (20-40 cm) of fertilization could be used as an index for delaying senescence.

Catalase↗
PubMed2001

[A study on the mechanism of the biological roles of danshensu on fibroblast].

OBJECTIVE: To explore the effects of danshensu on fibroblast apoptosis and the expression of procollagen gene. METHODS: Danshensu was added to in vitro culture of human cutaneous fibroblasts, and the nuclear proteins and total RNA were harvested from the cells. Electrophoretic mobility shift assay (EMSA) was adopted to determine the combining activity of nuclear transcription factors NF-kB and NF-1. Cell apoptosis was analyzed by DNA ladder fragmentation. The procollagen gene expression was analyzed by RT-PCR. RESULTS: Eight hours after the action of danshensu on the culture fibroblasts, the NF-kB combining activity was almost inhibited completely and the NF-1 combining activity decreased by about 50%. In addition, ladder-like DNA fragments were revealed clearly by sepharose electrophoresis. The mRNA levels of type I procollagen alpha1 and alpha2 decreased by 56% and 59%, respectively. CONCLUSION: Danshensu could inhibit the nuclear transcription factor NF-kB activity of fibroblast and induce the occurrence of its apoptosis. Furthermore, danshensu could also inhibit the nuclear transcription factor NF-1 activity of fibroblast and modulate the synthesis and secretion of collagen.

Apoptosis↗