[Study on antiangiogenesis effect of Vaccaria segetalis].

OBJECTIVE: To study the inhibiting effect of Vaccaria segetalis extracts on neovascularization. METHODS: The effect of Vaccaria segetalis extracts on the proliferation, migration in vitro and tube formation on Matrigel of endothelial cell (HMEC) in vivo were examined by MTT assay and Matrigel plug assay. RESULTS: The proliferation and migration of HMEC were inhibited significantly by Vaccaria segetalis extracts in a dose-dependent manner (IC50 = 50 microg/mL). It also inhibited angiogenesis in Matrigel plug mouse model. CONCLUSION: Vaccaria segetalis extracts can inhibit angiogenensis obviously, and it could be developed as an effective antiangiogenic drug.

Identification of binding peptides of the ADAM15 disintegrin domain using phage display.

ADAM15 plays an important role in tumour development by interacting with integrins. In this study, we investigated the target peptides of the ADAM15 disintegrin domain. First, we successfully produced the recombinant human ADAM15 disintegrin domain (RADD) that could inhibit melanoma cell adhesion by using Escherichia coli. Second, four specific binding peptides (peptides A, B, C, and D) were selected using a phage display 12-mer peptide library. The screening protocol involved 4 rounds of positive panning on RADD and 2 rounds of subtractive selection with streptavidin. By using the BLAST software and a relevant protein database, integrin alpha v beta 3 was found to be homologous to peptide A. Synthetic peptide A had a highly inhibitory effect on RADD-integrin alpha v beta 3 binding. The results demonstrate the potential application of short peptides for disrupting high-affinity ADAM-integrin interactions.

Anti-angiogenic activity of julibroside J8, a natural product isolated from Albizia julibrissin.

PURPOSE: The purpose of this study was to investigate the anti-angiogenic properties of julibroside J(8), a triterpenoid saponin isolated from Albizia julibrissin. METHODS: In the presence of juliborside J(8,) the growth of human microvascular endothelial cells (HMEC-1), four human tumor cell lines, and a normal cell line (MRC-5) was evaluated by MTT assay. The in vivo anti-angiogenic effect of julibroside J(8) was evaluated on a chorioallantoic membrane (CAM) and in transplanted colon carcinoma cells in a nude mice neovascularisation model. RESULTS: Treatment with 0.5-4 microg/ml julibroside J(8) resulted in dose-dependent inhibition of growth, migration, and tube formation in HMEC-1 cells; julibroside J(8) also inhibited the formation of microvessels on CAM at a concentration of 10-50 microg/egg and reduced vessel density within tumor at a concentration of 0.5-3mg/kg. CONCLUSIONS: Julibroside J(8) may be a potent anti-angiogenetic and cytotoxic drug; further investigation is warranted.

Dual-label time-resolved fluoroimmunoassay for simultaneous detection of aflatoxin B1 and ochratoxin A.

A dual-label time-resolved fluoroimmunoassay (TRFIA) for simultaneous quantification of aflatoxin B1 (AFB1) and ochratoxin A (OTA) is described. For this, microtitration wells were coated with AFB1-horse radish peroxidase (HRP) and OTA-bovine serum albumin. The standards and samples were loaded on the coated plates, and diluted antibodies and Eu3+- and Sm3+-labeled IgG were then added. Our results showed that the sensitivity of TRFIA for AFB1 was 0.02 microg/L (range 0.02-100 microg/L). The intra- and inter-batch coefficient of variation (CV) was 3.2 and 7.3%, respectively, and the average recovery rate was 88.1%. On the other hand, the sensitivity of OTA was 0.05 microg/L (range 0.05-50 microg/L), the intra- and inter-batch CV was 2.9 and 7.9%, respectively, and the average recovery rate was 89.9%. In the AFB1/OTA-TRFIA, AFB1 and OTA did not mutually interfere. The correlation coefficients between the dual-label AFB1/OTA-TRFIA and the single-label AFB1-TRFIA or OTA-TRFIA were 0.972 and 0.981, respectively, indicating that the results were consistent. Our study suggests that AFB1/OTA-TRFIA allows the simultaneous detection of AFB1 and OTA; is a simple, fast, and economic method for screening large quantities of samples, and has good prospects of application.

Preparation and biological evaluation of a glycosylated fusion interferon directed to hepatic receptors.

The antiviral activity and biodistribution of a glycosylated fusion interferon directed to hepatic receptors were evaluated to determine whether its pharmaceutical concentration in the liver could be improved. The novel glycosylated fusion interferon, galactosyl-human serum albumin-interferon-alpha2b (G-HSA-IFN) was obtained from a long-term recombinant fusion protein (HSA-IFN) by covalent coupling with a bifunctional reagent, 2-imino-2-ethyloxymethy1-1-thiogalactose. There are about 24 thiogalactose residues in each G-HSA-IFN molecular on average. The antiviral activities of IFNalpha2b, HSA-IFN, and G-HSA-IFN were compared in a cytopathic effect inhibition assay with the WISH/VSV system in vitro, and the modification had little effect on its antiviral activity. Both G-HSA-IFN and HSA-IFN were labeled with 125I and the radiochemical purity of 125I-G-HSA-IFN was greater than 96%. 125I-G-HSA-IFN bound to the asialoglycoprotein receptor (ASGP-R) on hepatic cells much more specifically than 125I-HSA-IFN, with specific binding rates of 89.53% and 6.66%, respectively (p < 0.01). Biodistribution research in mice showed that 125I-G-HSA-IFN could concentrate effectively in the liver (>45%/g) and suggested that it also could be a good imaging agent of hepatic receptors.

Enhancement of recombinant human ADAM15 disintegrin domain expression level by releasing the rare codons and amino acids restriction.

This study was aimed at increasing the production of the recombinant human ADAM15 disintegrin domain (RADD) in Escherichia coli by releasing the rare codons and restricting amino acid residues. Three different strategies for increasing RADD production were examined: to select the suitable host strain, to optimize the rare codons, and to delete the amino acids residues. The total fusion protein glutathione-S-transferase (GST)-RADD concentration of 298 mg/l and 326 mg/l were achieved by selecting E. coli Rosetta (DE3) as the host strain and by changing GGA to GGC at the GST-RADD cassette, respectively. The RADD concentration was increased by 35.7% by eliminating the "Pro-Glu-Phe" residues at the GST-RADD junction. By combinational utilizing the preferred codon introduction and amino acid sequence optimization in E. coli Rosetta (DE3), the highest RADD concentration of 68 mg/l was achieved. The proposed strategy may provide an alternative approach for other enhanced recombinant protein production by E. coli.

[Improving production and bioactivity of recombinant human disintegrin domain of ADAM15 (rhADAM15) in Escherichia coli].

OBJECTIVE: To enhance the production and bioactivity of recombinant human disintegrin domain of ADAM15 (A Disintegrin and Metalloproteinase 15) (rhADAM15) in Escherichia coli. METHODS: The expression host was chose and the recombinant expression plasmid pGEX-ADAM15 was constructed, based on analysis of the cDNA sequence of rhADAM15. RESULTS: (1) 298 mg/L GST (Glutathione-S-transferase)-ADAM15 and 42 mg/L rhADAM15 were achieved when choosing E. coli Rosetta (DE3) as the expression host that could supply additional tRNA for rare codons. (2) The GST-ADAM15 expression level increased to 326 mg/L after changing the rare codon GGA (Gly425) to GGC by PCR (Polymerase Chain Reaction)-based site-directed mutagenesis. (3) The rhADAM15 concentration increased to 57 mg/L by deleting the "Pro-Glu-Phe" at the GST-ADAM15 junction to improve the thrombin cleavage efficiency. (4) Finally, by combinational introduction of the favorable codons and suitably eliminating of certain amino acid sequence, rhADAM15 concentration reached the highest level (68 mg/L). CONCLUSION: The high expression of heterologous protein could be achieved by releasing rare codon usage and amino acids residues restriction.

Screening cellular proteins involved in the anti-proliferative effect of the ADAM15 disintegrin domain in murine melanoma cells.

A disintegrin and metalloprotease protein 15 (ADAM15), a membrane-anchored glycoprotein, is believed to function in cell-cell interactions via an integrin binding motif within its disintegrin domain. To screen its target proteins, the recombinant ADAM15 disintegrin domain (RADD) was expressed in Escherichia coli, biotinylated and used in a protein pull-down assay in vitro. A total of eight kinds of proteins were identified by 2DE/LC-MS-MS. One of them, p38 kinase, was selected for further investigation of its involvement in the anti-proliferative effect of RADD on melanoma cells. Phosphorylation of p38 kinase in melanoma cells was detected upon treatment with RADD. Furthermore, the suppression of p38 kinase activity resulted in a decrease in the RADD inhibitory effect on melanoma cell proliferation. These results provide evidence that RADD inhibits melanoma cell proliferation partly through p38 kinase activation.

Expression, purification, and characterization of recombinant human serum albumin fusion protein with two human glucagon-like peptide-1 mutants in Pichia pastoris.

Glucagon-like peptide-1 (GLP-1) is a 30-residue peptide hormone secreted by intestinal L-cells in response to nutrient ingestion. In the present study, overlapping PCR technology was employed to construct two GLP-1 mutants (GLP-1(A2G))2 and human albumin (HSA) genes in vitro without linker. The spliced gene, (GLP-1(A2G))2-HSA, was over expressed under the control of promoter AOX1 and Mat alpha signal peptide in Pichia pastoris. SDS-PAGE and Western blotting were applied to assay the recombinant fusion protein in the culture broth. The results demonstrated that the recombinant (GLP-1(A2G))2-HSA concentration in the broth could reach a level of 245.0 mg/L and the expressed fusion protein was capable of cross-reacting with anti-human GLP-1 and anti-human albumin antibody. The recombinant (GLP-1(A2G))2-HSA protein was purified by ultrafiltration, columns of Q-sepharose fast flow and Superdex 75 size-exclusion. The recombinant (GLP-1(A2G))2-HSA protein obtained could lower in vivo glucose concentration in blood and stimulate in vitro islet cell proliferation. In mouse model, the fusion protein was detectable in plasma even 308 h after a single subcutaneous dose of 1.25 mg/kg. The result showed that the terminal biological half-time of the protein was about 54.2 h which is 650-fold longer than that of GLP-1. The pharmacokinetic analysis of the protein suggests its promising application in clinical medicine.

[Effect and mechanism of recombinant hirudin on fibrinolysis].

AIM: To study the effect of recombinant hirudin (rH) on tPA-induced fibrinolysis and the possible mechanism of its action. METHODS: The effect of rH on thrombin-fibrin complex (Th-Fn) was detected by 99mTc labeled rH. In the in vitro clot lysis, tPA as plasminogen activator, and recalcified plasma as plasminogen resource were used to study the influence of rH on fibrinolysis by detecting TAFIa, D-Dimer and FXIII. RESULTS: In a canine model of femoral artery thrombosis, a clear radioactivity strip was imaged in 30 - 60 min on a part image, and the femoral vein thrombosis developed at 30 min. rH efficiently inhibited clot regeneration. Addition of TM could inhibit clot lysis obviously, and CPI could shorten the delay of clot lysis which due to TAFIa. There was a dose-dependent relationship with TM concentration and TAFI activation. FXIII activation was inhibited by low concentration of rH ( < or = 0.2 u x mL(-1)), and the level of fibrinolysis product, D-Dimer, increased. CONCLUSION: rH could inhibit the thrombin binding to fibrin. rH inhibited the activation of TAFI and FXIII by combining with thrombin which resulted in enhancement of thrombolysis.

[Studies on active substance of anticancer effect in Polygonum cuspidatum].

OBJECTIVE: To supply the scientific basis of research and development of the medicinal value of Polygonum cuspidatum. METHODS: One composition was isolated from the roots of Polygonum cuspidatum by cytotoxicity based fractionation and identified by HPLC-MS, UV scanning and IR. The inhibition and morphology of L-02, Hep G2, SHZ-888, MCF-7, MCF-7/ADM cells growth caused by this composition was determined by MTT assay and HE dyeing. RESULTS: This composition was identified as trans-and cis-resveratrol. It could specifically inhibit proliferation of many cancer cells but not human normal liver cell. We investigated the cytotoxicity of resveratrol to adriamycin-resistant MCF-7 cell in virtro. CONCLUSION: Resveratrol is a new anticancer composition which is less toxicity and higher efficiency in Polygonum cuspidatum.

[Use of ultrasensitive time-resolved fluoroimmunoassay for rapid detection of clenbuterol hydrochloride in urine].

OBJECTIVE: In order to provide a rapid and selectivity method for the determination of clenbuterol(CBL), an indirect competitive time-resolved fluoroimmunoassay (TRFIA) was developed. METHODS: Anti-CBL antibody, was raised by immunization against CBL-BSA in rabbits. CBL-OVA was coated by physical adsorption onto the microtitre plate, CBL or sample with CBL as a competitor. Both them were incubated with limited anti- CBL antibody. and a goat antirabbit IgG-Eu3+ conjugate was used as a tracer. RESULTS: The sensitivity of CBL-TRFIA was 0.01microg/L, and the recovery rate was 99.7%. RSD of CBL-TRFIA was 3.9% . The sensitivity of CBL-TRFIA provided a linear response from 0.01 - 25microg/L, with ED50 of (1.47+/-0.11) microg/L or ED80 of (0.07+/-0.01)microg/L and ED, of (23.6+/- 0.56) microg/L. The cross reactivity of the CBL-TRFIA with salbutamol, epinephrine hydrochloride and epinephrine bitartrate was negligible, while that with isoprenaline hydrochloride was 0.01% . Both CBL-TRFIA and CBL-ELISA test were applied for the quantitative measurement of CBL in the same urine, and the coefficient of correlation was 0.932. CONCLUSION: The CBL-TRFIA could be applied to detect the CBL in urine and it is useful to screening easily for CBL contamination in meat or foods.