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Li Zheng

Publications and source records attributed to Li Zheng.

At least 55 records · Page 3Linked to original sources
PubMed2004

A conformation-constrained peptide library based on insect defensin A.

Here, we reported a conformation-constrained peptide library, that was constructed based on the scaffold of a 29 amino acids peptide derived from insect defensin A. The peptide scaffold was designed utilizing the InsightII molecular modeling software and then displayed on M13 filamentous bacteriophage by fusion with coat protein III. The library was constructed by randomization of seven positions located within the two loops of the peptide scaffold generating approximately 8.3 x 10(8) transformants. Sequences from 14 randomly selected phage clones indicated that the distribution of nucleotides and amino acids paralleled with the expected frequency. Screening against the target proteins: tumor necrosis factor alpha, TNF receptor 1, TNF receptor 2 and monoclonal antibody against BMP-2 showed significant enrichment in all cases. The results presented here show that the reconstructed insect defensin A domain will be a promising non-antibody protein scaffold for the presentation of a phage-displayed constrained peptide library.

Amino Acid Sequence↗
PubMed2004

Downregulation of wild-type p53 protein by HER-2/neu mediated PI3K pathway activation in human breast cancer cells: its effect on cell proliferation and implication for therapy.

Overexpression and activation of HER-2/neu (also known as c-erbB-2), a proto-oncogene, was found in about 30% of human breast cancers, promoting cancer growth and making cancer cells resistant to chemo- and radio-therapy. Wild-type p53 is crucial in regulating cell growth and apoptosis and is found to be mutated or deleted in 60-70% of human cancers. And some cancers with a wild-type p53 do not have normal p53 function, suggesting that it is implicated in a complex process regulated by many factors. In the present study, we showed that the overexpression of HER-2/neu could decrease the amount of wild-type p53 protein via activating PI3K pathway, as well as inducing MDM2 nuclear translocation in MCF7 human breast cancer cells. Blockage of PI3K pathway with its specific inhibitor LY294002 caused G1-S phase arrest, decreased cell growth rate and increased chemo- and radio-therapeutic sensitivity in MCF7 cells expressing wild-type p53. However, it did not increase the sensitivity to adriamycin in MDA-MB-453 breast cancer cells containing mutant p53. Our study indicates that blocking PI3K pathway activation mediated by HER-2/neu overexpression may be useful in the treatment of breast tumors with HER-2/neu overexpression and wild-type p53.

Breast Neoplasms↗
PubMed2004

Antipyretic, analgesic and anti-inflammatory activities of ketoprofen beta-cyclodextrin inclusion complexes in animals.

Ketoprofen is a nonsteroidal anti-inflammatory drug (NSAID) orally effective in treating fever, pain, and inflammation but gastrointestinal side effects were observed. Preparation of ketoprofen beta-cyclodextrin inclusion complexes was to increase the solubility and reduce the irritation. The complexes were prepared and preliminarily confirmed using X-ray diffraction and dissolution test. Antipyretic, analgesic and anti-inflammatory models were induced by 10% yeast using rabbits, 0.8% acetic acid using mice and 1% carrageenin using rats, respectively. Results showed that the dissolution rate of ketoprofen was significantly improved by complexation. X-Ray diffraction pattern of the complexes exhibited a diffuse pattern that differed from that of physical mixture of ketoprofen and beta-cyclodextrin. Ketoprofen markedly inhibited the fever reactions at a single dose of 2 mg/kg as follows: 64.53% (inhibition rate %) at 1 h for ketoprofen, 73.04% at 1 h for ketoprofen beta-cyclodextrin inclusion complexes, respectively. Alleviating pain reaction rates following a single dose of 8 mg/kg at 20 min were 39.25% for the inclusion complexes and 26.72% for ketoprofen, respectively. Inhibition rates to rat edema following a single dose of 5 mg/kg at 1 h were 39.47% for the inclusion complexes and 23.86% for ketoprofen. Results for antipyretic, analgesic and anti-inflammatory activities showed that the rapid and stronger effects were found in the treatment group of ketoprofen beta-cyclodextrin inclusion complexes in comparison with those of free ketoprofen.

Adjuvants, Pharmaceutic↗
PubMed2004

[Effect of XK469 and adriamycin on the growth of H460 cells in vitro and its mechanism].

OBJECTIVE: To investigate the inhibitory effect of XK469 on the in vitro growth of H460 cells and its mechanism. METHODS: The survival curves of H460 cells treated with XK469, XN472 and adriamycin, respectively, were obtained by MTT analysis, and the effect of XK469 and adriamycin on the cell cycle of H460 cells examined by flow cytometry. Western blotting was adopted for detecting the expression of cdc2 and phos-cdc2 induced by XK469 and adriamycin. RESULTS: Different concentrations of XK469 and adriamycin could significantly inhibit the growth of H460 cells, induce their G2/M phase arrest, and increase phos-cdc2 expression; XN472 had a lesser effect on the growth of H460 cells. CONCLUSION: XK469 can increase phos-cdc2 expression and induce G2/M phase cell cycle arrest of H460 cells, resulting in inhibition of H460 cell growth. The inhibitory effect of XK469 on H460 cell growth is attributed to the chlorine in the 7-positon of its structure.

CDC2 Protein Kinase↗
PubMed2004

[Prognostic factors in patients with stage III and IV non-small cell lung cancer].

OBJECTIVE: To investigate the prognostic factors in non-small cell lung cancer (NSCLC) at stage III and IV and establish a reliable model of clinical prognostic index. METHODS: Kaplan-Meier and Cox regression were used to analyze the relationship between the prognostic factors and survival time in 114 cases of NSCLC. The prognostic factors included clinical-pathological features and serum levels of cytokeratin fragment 19 (Cyfra21-1), CEA, neuron-specific enolase (NSE), CA125, interleukin-2 (IL-2) and soluble interleukin-2 receptors (sIL-2R). RESULTS: Kaplan-Meier analysis showed that KPS, sex, disease stage, treatment, Cyfra21-1, sIL-2R and CA125 were related to prognosis. Multivariate analysis indicated that Cyfra21-1, stage and treatment were independent prognostic factors. When Cyfra21-1 > 3.5 mg/L, stage IV and chemotherapy < 3 cycles, the relative risk (RR) was 1.691, 2.229 and 3.035, respectively. In patients given 3 or more cycles of chemotherapy, serum Cyfra21-1, sIL-2R and stage at diagnosis were significantly independent prognostic factors. Three of these prognostic factors were used to establish a prognostic index (PI) model based on a simple algorithm: PI = Cyfra21-1 + sIL-2R + stage. The median survival period of patients with 3 or more cycles of chemotherapy were 18 months if PI = 0, 8 months if PI = 1 or 2, and 5 months if PI = 3. CONCLUSION: The serum Cyfra21-1, sIL-2R and disease stage in unresectable NSCLC were independent prognostic factors. PI calculated on the basis of Cyfra21-1, sIL-2R and stage is recommended to predict the survival period of NSCLC.

Antigens, Neoplasm↗
PubMed2004

[Overexpression of HER2/neu downregulates wild p53 protein expression via PI3K and Ras/Raf/MEK/ERK pathways in human breast cancer cells].

OBJECTIVE: To evaluate the effect of HER2/neu overexpression on wild p53 protein expression and to delineate the related signal pathways. METHODS: Lipofectin method was used to transfer HER2/neu into human breast tumor cell line MCF7. Overexpression of HER2/neu was then determined by Western blot. Western blot was also used to detect the quantity of p53, Akt, p-Akt, p-Raf, p-MEK, p-ERK protein. Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to detect p53 mRNA expression. PI3K pathway inhibitor LY294002 and MEK inhibitor U0126 were used to block the two pathways. The subsequent effect on p53 protein expression was then determined. RESULTS: HER2/neu-overexpressed MCF7 clone (MCF7-neu3) was successfully established, in which the amount of HER2/neu protein was 13 times more than that in parental MCF7 cells. The amount of p53 protein in MCF7-neu3 was 40% of that in parental MCF7 cells (P < 0.01), while there was no difference on p53 mRNA level. There were 2.5, 2.0, 1.6 and 1.6 fold increase in the amount of p-Akt, p-Raf, p-MEK, p-ERK protein respectively in MCF7-neu3 to that in parental MCF7 cells (P < 0.01). When treated with LY294002 or U0126 for 24 hours, the amount of wild p53 protein in MCF7-neu3 cells was 1.7 or 1.5 times higher than those in DMSO treated cells. There were 4.7 or 5.3 times increase in the p53 protein when MCF7-neu3 cells were treated with LY294002 or U0126 for 48 hours (P < 0.01). Similar results were not seen in MDA-MB-453 cells which contained mutant p53. CONCLUSIONS: HER2/neu overexpression can activate PI3K and Ras/Raf/MEK/ERK pathways, resulting in reduction of wild p53 protein expression. This may be the molecular mechanism responsible for the poor prognosis and therapeutic non-responsiveness in HER2/neu-overexpressed breast cancer patients.

Breast Neoplasms↗
PubMed2004

[Effect of hot and humid environment on bone marrow and spleen of mice exposed to gamma irradiation].

OBJECTIVE: To study the effect of hot and humid environment (HHE) on the bone marrow and spleen in mouse exposed to gamma irradiation. METHODS: After exposure to gamma irradiation at the dosage of 6.5 Gy, the mice were subjected to treatment in HHE for 1 h or at room temperature (RT) respectively. After exposure to HHE, the mice in HHE group were kept at RT. The bone marrow and spleen of the mice in both RT and HHE groups were examined at 1, 3, 5, 9 and 15 days after irradiation for bone marrow cellularity, DNA content in the bone marrow cells, and spleen/body weight ratio. RESULTS: Compared with the RT group, mice in the HEE group showed aggravation of decreases in bone marrow cells, DNA content and spleen/body weight ratio. CONCLUSIONS: HHE aggravates radiation injury of the bone marrow and spleen in mice.

Animals↗
PubMed2004

[The effect of HER2/neu overexpression on p53 gene expression, cell proliferation and sensitivity to gamma-irradiation via the PI3K/Akt pathway in breast cancer cell MCF7].

OBJECTIVE: To investigate the effect of HER2/neu overexpression on the wild p53 gene expression, cell proliferation and sensitivity to gamma-irradiation via phosphatidylinositol 3-kinase (PI3K) pathway in human breast cancer cell MCF7. METHODS: Lipofectin-mediated gene transfection method was used to transfer HER2/neu into MCF7 cells. Expression of HER2/neu, p53, Akt and p-Akt protein after PI3K pathway inhibitor LY294002 treatment was determined by Western blot. Cell proliferation and cell surviving fraction after gamma-irradiation treatment were assayed by MTT. RESULTS: Eighteen of HER2/neu stably transfected MCF7 cell clones were established, one of them was HER2/neu overexpressing. HER2/neu overexpressing MCF7 cells showed higher p-Akt expression and lower p53 expression than those of parental MCF7 cells, which could be abrogated by LY294002. HER2/neu overexpressing MCF7 cells had higher proliferation rate and lower sensitivity to gamma-irradiation than those of parental MCF7 cells, which could be opposed by LY294002. CONCLUSION: Overexpression of HER2/neu induces reduced expression of wild-type p53 protein, relatively high cell proliferation and low sensitivity to gamma-irradiation in breast cancer cell MCF7 by activating PI3K/Akt pathway, which may contribute to therapeutic resistance in some breast cancer patients with wild-type p53 gene status.

Breast Neoplasms↗
PubMed2004

[A primary study on antimicrobial and cytotoxic activity of marine bacteria].

Marine bacteria were isolated from marine organisms including invertebrates and seaweeds and from sea water and sediments of different sea area. Ethyl acetate extractions of marine bacterial fermentation were screened for antimicrobial and cytotoxicity activities by using the methods of agar diffusion and MTT assay, and the relationship of active bacteria and their origin was studied. The results showed that 42 strains among total 341 isolated marine bacteria had antimicrobial activity, and 7 strains had cytotoxicity activity. The proportion of active bacteria associated with marine invertebrates and seaweeds (22% and 11%) was higher than that isolated from sea water and sediments (7% and 5%). The most active marine bacteria were assigned to the Pseudomonas, Photobacterium, Clostridium, Alteromonas and Flavobacterium group.

Anti-Bacterial Agents↗
PubMed2004

[Correlation study of expression levels of prostate-specific membrane antigen and prostate-specific antigen with Gleason score of prostate carcinoma].

OBJECTIVE: To study the correlation of prostate-specific membrane antigen (PSMA) and prostate-specific antigen (PSA) expression with Gleason score of prostate carcinoma. METHODS: Monoclonal antibodies against epitopes of PSMA extracellular domain were prepared, with which the expression of PSMA of prostate carcinoma (PC) was determined by immunohistochemical staining. Correlation of its expression with Gleason score of PC was statistically analyzed, and compared with that of PSA. RESULTS: Eight hybridoma cell lines secreting monoclonal antibodies specific for PSMA were prepared. PSMA expression level was positively correlated with Gleason score. In poorly differentiated prostate carcinoma, the expression intensity of PSMA was higher than that of medium-and well-differentiated prostate carcinoma (P < 0.01). However, there was no correlation between level of PSA expression and Gleason score (P > 0.05). CONCLUSION: PSMA expression level may be used as a useful surrogate marker in Gleason grading of prostate carcinoma. It may be a more suitable target than PSA in antibody mediated immunotherapy against poorly differentiated prostate carcinoma which is usually not sensitive to hormonal therapy.

Antigens, Surface↗
PubMed2003

Interaction and stimulation of human FEN-1 nuclease activities by heterogeneous nuclear ribonucleoprotein A1 in alpha-segment processing during Okazaki fragment maturation.

High-fidelity DNA replication depends on both accurate incorporation of nucleotides in the newly synthesized strand and the maturation of Okazaki fragments. In eukaryotic cells, the latter is accomplished by a series of coordinated actions of a set of structure-specific nucleases, which, with the assistance of accessory proteins, recognize branched RNA/DNA configurations. In the current model of Okazaki fragment maturation, displacement of a 27-nucleotide or longer flap is envisioned to attract replication protein A (RPA), which inhibits flap endonuclease-1 (FEN-1) but stimulates Dna2 nuclease for cleavage. Dna2 cleavage generates a short flap of 5-7 nucleotides, which resists binding by RPA and further cleavage by Dna2. FEN-1 then removes the remaining flap to produce a suitable substrate for ligation. However, FEN-1 is not efficient in cleaving the short flap, and we therefore set out to identify cellular factors that might regulate FEN-1 activity. Through co-immunoprecipitation experiments, we have isolated heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), which forms a direct complex with FEN-1 and stimulates its enzymatic activities. The stimulation by hnRNP A1 is most dramatic using DNA substrates with short flaps. With longer flap substrates the hnRNP A1 effect is more modest and is suppressed by the addition of RPA. A model is provided to explain the possible in vivo role of this interaction and activity in Okazaki fragment maturation.

Binding Sites↗
PubMed2003

Identification of anti-TNFalpha peptides with consensus sequence.

Phage displayed peptide library was used to select tumor necrosis factor alpha (TNFalpha) binding peptides. After three sequential rounds of biopanning, some linear TNFalpha-binding peptides were identified from a 12-mer peptide library. A consensus sequence (L/M)HEL(Y/F)(L/M)X(W/Y/F), where X might be variable residue, was deduced from sequences of these peptides. The phages bearing these peptides showed specific binding to immobilized TNFalpha, with over 80% of phages bound being competitively eluted by free TNFalpha. To confirm the binding activity and to explore further functional properties, three peptides with typical structure were selected and expressed as GST-fused protein. These recombinant peptides effectively competed for [125I]TNFalpha binding to TNFR1 in a dose-dependent manner, with IC(50) from 10 to 160 microM. Furthermore, the GST-fused derivatives showed inhibitory effects on TNFalpha-induced cytotoxicity. Taken together, these data demonstrate that the TNFalpha-binding peptides are effective antagonists of TNFalpha and the deduced motif might be useful in development of novel low molecular weight anti-TNFalpha drugs.

Bacteriophages↗
PubMed2003

Complementary functions of the Saccharomyces cerevisiae Rad2 family nucleases in Okazaki fragment maturation, mutation avoidance, and chromosome stability.

Rad2 family nucleases, identified by sequence similarity within their catalytic domains, function in multiple pathways of DNA metabolism. Three members of the Saccharomyces cerevisiae Rad2 family, Rad2, Rad27, and exonuclease 1 (Exo1), exhibit both 5' exonuclease and flap endonuclease activities. Deletion of RAD27 results in defective Okazaki fragment maturation, DNA repair, and subsequent defects in mutation avoidance and chromosomal stability. However, strains lacking Rad27 are viable. The expression profile of EXO1 during the cell cycle is similar to that of RAD27 and other genes encoding proteins that function in DNA replication and repair, suggesting Exo1 may function as a back up nuclease for Rad27 in DNA replication. We show that overexpression of EXO1 suppresses multiple rad27 null mutation-associated phenotypes derived from DNA replication defects, including temperature sensitivity, Okazaki fragment accumulation, the rate of minichromosome loss, and an elevated mutation frequency. While generally similar findings were observed with RAD2, overexpression of RAD2, but not EXO1, suppressed the MMS sensitivity of the rad27 null mutant cells. This suggests that Rad2 can uniquely complement Rad27 in base excision repair (BER). Furthermore, Rad2 and Exo1 complemented the mutator phenotypes and cell cycle defects of rad27 mutant strains to differing extents, suggesting distinct in vivo nucleic acid substrates.

Cell Cycle↗
PubMed2003

Expression, refolding, and activation of the catalytic domain of human blood coagulation factor XII.

Human blood coagulation factor XII (FXII; 80 kDa) contains a C-terminal serine protease zymogen domain, which becomes activated upon contacting a negative surface. Activated FXII (alphaFXIIa) brings about reciprocal activation of FXII and kallikrein that by further hydrolysis produces the free catalytic domain (betaFXIIa; 28 kDa). Increased levels of alphaFXIIa are associated with coronary heart disease, sepsis, and diabetes. Biophysical investigation of the structural basis of activation, substrate specificity, and regulation of FXII requires an efficient bacterial system for producing the wild-type and mutant recombinant proteins. Here, the cDNA of the zymogen domain of FXII (betaFXII) was cloned into the pET-28a(+) vector and the plasmid was transformed into Escherichia coli strain BL21 (DE3) and overexpressed. The multi-disulfide, recombinant protein, His(6)-betaFXII (rbetaFXII), expressed as an inclusion body, was purified by means of a Ni(2+)-charged resin. The matrix-bound rbetaFXII was subjected to refolding with the glutathione redox system and activated by the in vivo activator, kallikrein. The active form, rbetaFXIIa, obtained in milligram quantities, exhibited similar structural and comparable functional properties relative to human betaFXIIa, as indicated by circular dichroism spectroscopy and kinetics of substrate hydrolysis. Thermodynamics of enzyme:inhibitor complex formation, including the expected 1:1 stoichiometry, was determined for rbetaFXIIa by isothermal calorimetric titration with a specific recombinant protein inhibitor, Cucurbita maxima trypsin inhibitor-V (rCMTI-V; 7kDa).

Blood Coagulation↗
PubMed2003

The effect of emotional stress on the primary humoral immunity of rats.

The effect of exposure to emotional stress on humoral immune function after injection with ovalbumin, a novel antigen, was studied in adult male Wistar rats. Emotional stress was induced by randomly giving empty water bottles to rats trained to drink water at set times. The results showed that emotional stress induced the decrease in spleen weight and specific immunoglobulin G antibody level to ovalbumin, and increased levels of epinephrine, norepinephrine and corticosterone. A decrease of antibody levels correlated negatively with an increase in plasma norepinephrine levels. These findings suggest that emotional stress can modulate immune function, and that sympathetic nervous system may be involved in this immunomodulation.

Animals↗
PubMed2003

Total coenzyme Q10 concentrations in Asian men following multiple oral 50-mg doses administered as coenzyme Q10 sustained release tablets or regular tablets.

Coenzyme Q(10) (CoQ(10)), a highly lipophilic compound present in the inner mitochondrial membrane, is essential for production of cellular energy in the form of ATP. CoQ(10) is used as a dietary supplement and for treatment of various cardiovascular disorders. Our goal was to compare the CoQ(10) levels in Asians following multiple oral doses administered as sustained release or regular tablets. Twenty healthy male volunteers (19-23 years old) were divided into two equal groups. Each subject in Group I received 50 mg oral doses of coenzyme Q(10) as sustained release tablets once a day for fifteen days, while subject in Group II received 50 mg doses of coenzyme Q(10) regular tablets. The CoQ(10) levels were measured by HPLC-UV (reverse phase ODS column, 10 microm, 250 x 4.6 mm; oven temperature 30 degrees C). Mobile phase was constituted by methanol-ethanol 9 : 1 v/v. Flow rate was 1.5 ml/min and UV detection was carried out at 275 nm. Coenzyme Q(9) was used as an internal standard. CoQ(10) baseline in the morning was 0.88+/-0.48 mg/l. Following 1 week 50 mg/d dosing of CoQ(10), plasma CoQ(10) concentrations increased to 1.85+/-1.03 mg/l for sustained release tablets and up to 1.37+/-0.74mg/l for regular tablets. The net increment proportion in AUC for sustained release and regular tablets were 148.26+/-176.56%, 102.57+/-130.00%, respectively. Both preparations significantly increased the systemic exposure when compared to endogenous baseline.

Adult↗
PubMed2003

[Study on the strategy of Japanese encephalitis immunization using live attenuated vaccine combined with inactivated vaccine].

OBJECTIVE: Using the advantages of Japanese encephalitis live attenuated and inactivated vaccine, to reduce the rate of immunization reaction and to increase the effect, we conducted a study on the strategy of immunization in Japanese encephalitis using live attenuated vaccine combined with inactivated vaccine. METHODS: Observing the safety and immune effects of different groups. RESULTS: Data on side effect showed that the rate of moderate and severe systematic reactions of the group who were inoculated with combined vaccine was 0.73%, with local reaction 1.46% while the combined rate of moderate and severe systematic reaction of the group who were inoculated with inactivated vaccine was 2.8%. Under the detection of serum neutralizing antibody, the GMT rose from 1:1.05 - 1:3.35 before vaccination to 1:47.34 - 1:101.30 after vaccination in the different groups. Neutralizing antibody was detected in 97.67% of the combined group. There was a significant difference by comparing neutralizing antibody seroconversion rate of the combined group with the inactivated group (chi(2) = 3.89, P < 0.05), but no significant difference with attenuated group (chi(2) = 0.74, P > 0.05). CONCLUSION: Results showed that in children who previously had been immunized with two doses of inactivated vaccine, the booster administration of live attenuated vaccine was both effective and safe.

Antibodies, Viral↗