Biomedical subjects

Wei Li

Publications and source records attributed to Wei Li.

At least 415 records · Page 23Linked to original sources

PubMed2005

[Forming mycelium pellet and decolorization of dye wastewater under opening conditions].

Removal of three water-soluble dyes through biosorption of four fungal strains was investigated. Some key factors affecting the formation of pellets and removal of dye under opening conditions was examined and the possibility of repeated inoculation of pellets was evaluated. The results show that removal of acid brilliant red B by 4 strains was almost 100%; the removal of all three tested dyes by Trichoderma sp. was more than 99%. Trichoderma sp. formed pellets well under opening conditions when its fragmentized mycelium obtained by 3 min grinding pellets at high concentration was inoculated, as 100% removal of acid brilliant red B was achieved by biosorption of newly growing pellets. Repeated inoculation of pellets accelerated dye removal, time for 100% decolorization reduced from first inoculation 72h to third inoculation 12h.

Aspergillus↗

PubMed2005

[Microscopic autofluorescence study of cardiac cancer and normal gastric tissues].

OBJECTIVE: To investigate the microscopic autofluorescent characteristics of cardiac cancer and autofluorescence distribution in different layers of gastric tissues. METHODS: A double-channel laser scanning confocal microscopy with Argon ion laser (excitation wavelength 488 nm) and Helium-Neon laser (excitation wavelength 543 nm) were used to detect the autofluorescence emitted from 16 surgical specimens of cardiac cancer and corresponding normal gastric tissue. The autofluorescence image was analyzed between the cardiac cancer tissue and normal gastric tissue. RESULTS: Autofluorescence was detected successfully in cardiac carcinoma and corresponding normal gastric corpus tissues of all 16 cases. In different layers of gastric tissue, fluorescence presented the strongest signal in submucosa,the second strong in luminal propria with fluorescence mostly distributed in the glands, fluorescence signal from gastric cancer was significantly decreased compared with those in the different layers of normal tissues (P< 0.01). CONCLUSION: There are significant differences in the shape, color, distribution and fluorescence intensity of microscopic autofluorescence between cardiac cancer tissues and normal gastric corpus tissues.

Aged↗

PubMed2005

[Chemical investingation of Chinese mangrove Sonneratia apetala II].

OBJECTIVE: Isolation and structural elucidation of the constituents of China mangrove Sonneratia apetala. METHOD: chromatography methods were used for isolation of compounds, spectroscopic methods were used for structural identifyication. RESULT: seven known compounds named (+/-) symgaresinol, betulinic acid, lupeol, lupeone, stigmast-5-ene-3beta, 7alpha-diol, beta-alpha myrin hexadecaneate, physcoion were isolated. CONCLUSION: these known compouns were unreported previously from this plant.

Magnoliopsida↗

PubMed2005

[Cytokines secretion by peripheral blood mononuclear cells from hepatitis C patients after stimulation with synthetic peptides at the highly variable region].

OBJECTIVE: Test the cytokines secretion by peripheral blood mononuclear cells (PBMC) from hepatitis C patients after stimulation with highly variable region (HVR1) synthetic peptides. METHODS: ELISA was used to test the cytokines secretion, flow cytometry to group the proliferated cells, and the antigenicity of synthetic peptide was predicted by the computer modeling. RESULTS: (1)There were PBMC proliferation when stimulated by HVR1 antigen synthetic peptides. (2) There was a rise of IFN-gamma, IL-4 and IL-10. But no rise of IL-2 and TNF-gamma was found. (3) The proliferated cells were mainly CD4+ lymphocytes. CONCLUSION: PMBC from hepatitis C patients tend to secret Th2 cytokines after stimulation with HVR1 designed by the authors.

Amino Acid Sequence↗

PubMed2005

[Evaluation on cytotoxicity of a new nano-hydroxyapatite as root canal filling sealer].

OBJECTIVE: To evaluated the cytotoxicity of a new nano-hydroxyapatite (n-HA) root canal sealer. METHODS: In this study, the cytotoxicity was evaluated by the method of MTT assay in vitro, and culture medium F12 as control, three concentrations of the soaking material cultured with mouse osteoblast separately, to test the cell relative growth rate (RGR) of every group. RESULTS: The toxicity graduation of the n-HA root canal sealer tends to 0 with the culture time increasing. The cell survival rate of n-HA root canal sealer showed high relatively. The OD value of cell was similar for the negative control and the extracts (P > 0.05). CONCLUSION: The result indicated that n-HA root canal sealer was compatible with the testcells.

Animals↗

PubMed2005

[Study on the comet-tail system of 12C16O+ in the near-infrared region].

The molecular cation CO+ is a very important transient molecular radical, and the spectra of the ion has been investigated by numerous researchers. Optical-heterodyne-magnetic-rotation-enhanced velocity modulation spectroscopy(OH-MR-VMS) was employed to measure the comet-tail system (A2 pi(i)-X2 sigma+) of 12C16O+ molecular ion. The vibrational rotation absorption spectra wereobserved in the near-infrared region, including three bands of (0, 3), (1, 4) and (3, 6). A set of precise molecular constants for the A2 pi(i) (v' = 0, 1, 3) were determined using the least-squares fit. This experiment has further proved that OH-MR-VMS is very valuable in measuring absorption spectra of molecular ions.

Cations↗

PubMed2005

[Fabrication of relative humidity optical fiber sensor based on nafion-crystal violet sensing film].

With two kinds of sensing methods for relative humidity based on fluorescence and visible absorption respectively, crystal violet was opted as the molecule probe for humidity. The optical chemical sensing film for humidity was prepared when crystal violet was embedded in the Nafion gel. The relative humidity sensor was fabricated after the sensing film had been coupled with other components, such as optical fiber and detector, which possessed short response time ( < 2 min), high sensitivity (< or = 5% RH), wide dynamic range (30%-100%) and good reversibility (RSD < or = 2.6%) for relative humidity at 640 nm wavelength.

Air↗

PubMed2005

[Agrobacterium tumefaciens-mediated transformation of the white-rot basidiomycete, phanerochaete chrysosporium].

Agrobacterium tumefaciens has been used to transfer its T-DNA to filamentous fungus Phanerochaete chrysosporium. A DNA fragment containing recombinant hygromycin B phosphotransferase gene (rhyg(r)) which is controlled by a promoter from P. chrysosporium and the lignin peroxidase gene terminator was cut out from pCH6, and inserted into a plant binary plasmid pCAMB1300, resulted in the recombinant plasmid pCH6-1300. The plasmid pCH6-1300 was then transformed into Agrobacterium tumefaciens strain A208, which was used to infect conidia or protoplasts of P. chrysosporium. Sixteen hygromycin B-resistant P. chrysosporium colonies were obtained. The transformation frequency is about 8 - 9 transformants per 106 conidia or protoplasts, which had no significant difference with the values obtained from conidia or protoplasts. One of the transformants named AT18, whose colony morphology was different from the wild-type strain. The results from both PCR and Southern blot analysis of transformants demonstrated that the rHyg(r) gene was integrated into the host genome with single copy. This approach may not require any instrument and digestion of fungal cell walls. A . tumefaciens-facilitated transformation should be very useful for further studies of the molecular genetics of P. chrysosporium.

Agrobacterium tumefaciens↗

PubMed2005

[Screening of antineoplastic components in Radix et Rhizoma Rhei using chromatographic fingerprints].

A new strategy for screening of antineoplastic components in the traditional Chinese medicine of Radix et Rhizoma Rhei has been developed using chromatographic fingerprints before and after metabolism by high performance liquid chromatography-mass spectrometry. The metabolizing method was established based on the in vitro metabolism by Sprague-Dawley (SD) rat liver homogenate. By means of the metabolism methods in vitro, the antineoplastic activity of the extracts, metabolites and components of Radix et Rhizoma Rhei were determined by microculture tetrazolium (MTT) assays in vitro. It was observed that the inhibition rate of the crude extract for HeLa cell was increased from 26.7% to 36.2% after 60 min of metabolism. The changes of activities resulted from the changes of components' structures and the bioactive components were discovered simultaneously in view of metabolism by inhibiting rate assay for the components in Radix et Rhizoma Rhei. It is concluded that the antineoplastic activity of the crude extract from Radix et Rhizoma Rhei was increased after in vitro metabolism because the antineoplastic activity of aloe-emodin, the metabolite of chrysophanol, is higher than its parent compounds.

Animals↗

PubMed2005

[Determination of phenylarsenic compounds in environmental samples by high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic method was developed for simultaneous determination of phenylarsonic acid (PAA), phenylarsine oxide (PAO), diphenylarsinic acid (DPAA), bis (diphenylarsine) oxide (BDPAO) and triphenylarsine (TPA) in soil samples. The extraction solvent for soil samples was acetonitrile and ultrasound was used in the extraction. Good separation was achieved by using an Inertsil CN-3 column (250 mm x 4.6 mm i.d., 5 microm) with the following conditions: gradient program of mobile phase, a 10 min linear gradient from 100% A (a mixture of acetonitrile-2.5 g/L KH2PO4 (pH 2.0) buffer (5:95, v/v) ) to 100% B ( a mixture of acetonitrile-2. 5 g/L KH2PO4 (pH 2.0) buffer (50:50, v/v)), and isocratic at 100% B from 10.01 min to 28 min; flow rate of 1.0 mL/min; time-programmed UV detection at 210 nm (0 - 10.5 min, 20 - 28 min) and 268 nm (10. 5 - 20 min). The linear range of PAA, PAO, DPAA, BDPAO and TPA were 8 - 30, 5 - 40, 20 -4000, 120 - 8000 and 1 - 60 mg/L, respectively. The detection limits at a signal-to-noise ratio of 3 were 0.1, 0.1, 0.2, 10, and 0.1 mg/L for PAA, PAO, DPAA, BDPAO and TPA, respectively.

Arsenicals↗

PubMed2005

[Establishment and application of real-time fluorescence polymerase chain reaction based on the TaqMan probes for detection of Yersinia pestis].

OBJECTIVE: Establishing and developing methods for quick, special and of Yersinia pestis (Y. pestis). METHODS: Using real-time fluorescence polymerase chain reaction (PCR) based on TaqMan technology with UDG anti-contamination systems and ROX reference dye, we established a method to detect Y. pestis. Probes and primers from pla, caf1, hms and inv gene were designed. An internal positive control was added to the reaction mixture in order to detect the presence of PCR inhibitors that were often found in biological samples. Sensitivity was evaluated by serial dilution of colons, internal template and Y. pestis strains while specificity was confirmed by amplifying real DNAs from bacteria, the representative Y. pestis strains and blind assay. RESULTS: The methods used could provide quick, special and sensitive detection of Y. pestis, with sensitivities of pla, f1, hms as 10, 1 and 1 copie(s) respectively. CONCLUSION: The newly developed technologies seemed to be well suited to identify the Y. pestis in case of emergency, bio-terrorist attack and surveillance of the epidemics.

Animals↗

PubMed2005

[Apoptosis and its molecular mechanism in vestibular hair cell after gentamycin toxicity].

OBJECTIVE: To investigate the character of damaged vestibular hair cells caused by gentamycin, and to identify whether apoptosis and phosphorylation of JNK occurs in the damaged cells. METHOD: Healthy guinea pigs were divided into experimental group and control group randomly with 15 in each group, animals in experimental and control group received systemic injection of gentamycin [100 mg/(kg x d)] and saline respectively for 7 consequent days. All the animals were sacrificed on the 8th day, the crista vestibular of each were observed by preparation and frozen dissection. The apoptosis of hair cell were detected by TUNEL method and phosphorylation of JNK were detected by immunochemistry. RESULT: The lesion and apoptosis of hair cells could be seen in the experimental group,and the phosphorylation could be observed too; the hair cells of control group showed no sign of apoptosis or phosphorylation of JNK. CONCLUSION: Gentamycin cause vestibular hair lesion by inducing apoptosis and activation of JNK plays an important role in the procedure of apoptosis.

Animals↗

PubMed2005

[Microbial reduction of Fe(III) (EDTA) in the system of nitric oxide removal by metal chelate absorption].

Reduction of Fe(III) (EDTA) with cultivated microorganisms in the system of nitric oxide removal by metal chelate absorption was investigated. Supplemental glucose stimulates the formation of Fe(II) (EDTA) more than ethanol and methanol as the carbon sources. Ammonium salt was used to be as the nitric source instead of nitrate, which inhibits the reduction of Fe(III) (EDTA) due to the competition between the two electron acceptors. The optimal pH value was from 6 to 7. The reduction percentage of Fe(III) (EDTA) varied little with the range of 30 degrees C - 40 degrees C and decreased quickly with a temperature higher than 40 degrees C. The bio-reduction could be achieved efficiently with enough carbon source and cell inoculation. The reduction rate did not increase with adding more amount of carbon source or cell inoculation. The bio-reduction rate could be described by Michaelis-Menten equation and fitted to the first order reaction kinetics. The maximum reaction rates gamma max and the Michaelis constant k(m) were 1.3 mmol x (L x h)(-1) and 53.5 mmol x L(-1)respectively.

Absorption↗

PubMed2005

[Sequencing and analysis of Vibrio cholerae typing phage VP3 genome].

DNA sequence and the genome of phage VP3 (a typing phage of V. cholera) were analyzed. A random library of VP3 DNA was constructed by shot-gun library method. The VP3 genome sequence was assembled with contigs sequences, the gaps between different contigs were filled with sequencing data from primer walking. ORFs were predicted; Phylogeny of DNA polymerase sequences was analyzed to determine the class of VP3; The activity of putative promoter genes were analyzed using lacZ report system. VP3 genome is a 39504bp of circular double-stranded DNA. Twenty-seven out of forty-nine putative ORFs were annotated; twenty gene products were homologous with T7-like phages, including DNAP, DNA replicative protein, capsid, tail tubular, tail fiber protein, and DNA packaged protein. The activity of the putative promoter regions was confirmed through cloning those regions to LacZ-fuse plasmid pRS1274 and analysis of the expression of beta galactosidase. The complete genomic sequence of VP3 and phylogenetic tree analysis suggests VP3 is a member of T7 phage family.

Bacteriophage T7↗

PubMed2005

The experiment research of subconjunctival injections with etoposide for the treatment of retinoblastoma mice.

PURPOSE: To evaluate the efficacy of subconjunctival injections of Etoposide for retinoblastoma(RB) mice. METHOD: Twenty-five RB mice were divided into 5 groups for the study(GO-G4). GO for control group received 0.9% sodium chloride injection subconjunctival. G1: 5 RB mice for systemic delivery received 6 systemic administration of Etoposide 150 microg and Cyclosporin A (CSA ) 1.0mg at 3 days intervals, respectively. G2-G4: 5 RB mice in each group received 6 subconjunctival delivery of Etoposide in 50, 75, 150 microg at 3 days intervals, respectively.To observe the changes of the volume of RB in anterior chamber and the part of conjunctiva for injections of chemotherapeutic drugs. All eyes and conjunctiva and scleras of the part for drugs injections were obtained at 6 weeks after experiment for histopathologic examination. The findings under the light microscope were analysed with software to measure the areas of RB in anterior chambers and the tumor inhibition rate. RESULTS: The volume of RB in anterior chambers for G1 and G2 increase quickly and none of the mice exhibited tumor control. The RB volume increase slowly in G3 and exhibit tumor control in G4. The areas of tumors in GO-G4 are 0.710,0.659,0.634, 0.515,0.235 mm(2), respectively. The rate for tumor inhibition in GO-G4 are 0.0%, 7.18%, 10.70%, 27.43% , 66.90%, respectively. There are statistical significant difference between the G1 and G4 for the volumes of tumors and the rate of tumor inhibition. The pathologic examination of subconjunctiva and sclera for the injective sites showed no pathologic changes. CONCLUSIONS: There are significant effects for the method of subconjunctival delivery of Etoposide in RB control, demonstrating a positive dose-related relationship. Subconjunctival injection of Etoposide reached better efficacy in controlling and inhibiting RB cells than systemic delivery of Etoposide for the same dose. The pathologic results showed the subconjunctival delivery of etoposide were safety for conjunctiva and sclera. It would be one of effective and safety method of chemotherapy for RB.

Animals↗

PubMed2004

Quantification of zolmitriptan in plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry.

A sensitive and specific liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and quantification of zolmitriptan in human plasma. After the addition of the internal standard (IS) and 1.0 M sodium hydroxide solution, plasma samples were extracted with methylene chloride:ethyl acetate mixture (20:80, v/v). The organic layer was evaporated under a stream of nitrogen at 40 degrees C. The residue was reconstituted with 100 microl mobile phase. The compounds were separated on a prepacked Lichrospher CN (5 microm, 150 mm x 2.0 mm) column using a mixture of methanol:water (10 mM NH(4)AC, pH 4.0) = 78:22 as mobile phase. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The method was proved to be sensitive and specific by testing six different plasma batches. Linearity was established for the range of concentrations 0.30-16.0 ng/ml with a coefficient of determination (r) of 0.9998 and good back-calculated accuracy and precision. The intra- and inter-day precision (R.S.D.%) were lower than 15% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.30 ng/ml. The proposed method enables the unambiguous identification and quantification of zolmitriptan for pharmacokinetic, bioavailability or bioequivalence studies.

Humans↗

PubMed2004

Regulation of connexin43-protein binding in astrocytes in response to chemical ischemia/hypoxia.

Connexin-protein interactions are believed to be critical for the regulation of gap junctional intercellular communication and for the function of gap junctions formed by these complexes. We have primarily used immunoprecipitation strategies to investigate whether connexin43 binds to selected signaling and cytoskeletal proteins and whether connexin43-protein binding is altered in cultured astrocytes exposed to chemical ischemia/hypoxia, a treatment that resembles ischemia in vivo. Chemical ischemia/hypoxia induced marked dephosphorylation of connexin43, which was accompanied by increased association of connexin43 with c-Src, ERK1/2, and mitogen-activated protein kinase phosphatase-1 and by decreased association between connexin43 and beta-actin. Moreover, we found that endogenous c-Src in normal astrocytes exists primarily in the Triton X-100-soluble membrane fraction, distinct from the Triton-insoluble fraction, which contains gap junctions. After chemical ischemia/hypoxia, c-Src appeared in the Triton-insoluble fraction and was co-immunoprecipitated with connexin43, suggesting that chemical ischemia/hypoxia induced translocation of c-Src to the Triton-insoluble fraction and association with connexin43. Furthermore, the "dephosphorylated" form of connexin43 was immunoprecipitated by a phosphotyrosine antibody, suggesting tyrosine phosphorylation of connexin43 by c-Src. In addition, the association between connexin43 and c-Src was blocked by inhibition of connexin43 dephosphorylation, suggesting that the interaction between connexin43 and c-Src can be regulated by alterations in the phosphorylation state of connexin43. These results identify new binding partners for connexin43 and demonstrate that interactions between connexin43 and protein kinases and phosphatases are dynamically altered as a consequence of connexin43 phosphorylation.

Animals↗

PubMed2004

Light signaling in scotopic conditions in the rabbit, mouse and rat retina: a physiological and anatomical study.

In the dark, light signals are conventionally routed through the following circuit: rods synapse onto rod bipolar (RB) cells, which in turn contact AII amacrine cells. AII cells segregate the light signal into the on and off pathways by making electrical synapses with on cone bipolar (CB) cells and glycinergic inhibitory chemical synapses with off CB cells. These bipolar cells synapse onto their respective ganglion cells, which transfer on and off signals to the visual centers of the brain. Two alternative pathways have recently been postulated for the signal transfer in scotopic conditions: 1) electrical coupling between rods and cones, and 2) a circuit independent of cone photoreceptors, implying direct contacts between rods and off CB cells. Anatomical evidence supports the existence of both these circuits. To investigate the contribution of these alternative pathways to scotopic vision in the mammalian retina, we have performed patch-clamp recordings from ganglion cells in the dark-adapted retina of the rabbit, mouse, and rat. Approximately one-half of the ganglion cells in the rabbit retina received off signals through a circuit that was independent of RB cells. This was shown by their persistence in the presence of the glutamate agonist 2-amino-4-phosphonobutyric acid (APB), which blocks rod-->RB cell signaling. Consistent with this result, strychnine, a glycine receptor antagonist, was unable to abolish these off responses. In addition, we were able to show that some off cone bipolar dendrites terminate at rod spherules and make potential contacts. In the mouse retina, however, there seems to be a very low proportion of off signals carried by an APB-resistant pathway. No ganglion cells in the rat retina displayed APB- and strychnine-resistant responses. Our data support signaling through flat contacts between rods and off CB cells as the alternative route, but suggest that the significance of this pathway differs between species.

Aminobutyrates↗