Biomedical subjects

Shan Zhao

Publications and source records attributed to Shan Zhao.

9 recordsLinked to original sources

PubMed2006

Inhibition of human tumor xenograft growth in nude mice by a conjugate of monoclonal antibody LA22 to epidermal growth factor receptor with anti-tumor antibiotics mitomycin C.

Anti-EGFR monoclonal antibodies LA22 and Erbitux bind to different epitopes of EGFR. The chemimmunoconjugates of MMC with LA22 or Erbitux were prepared, and in vitro cytotoxicity assays with A549 cells showed that LA22-MMC was much more potent than Erbitux or Erbitux-MMC. Viabilities of A549 cells treated with LA22-MMC, Erbitux or Erbitux-MMC were 35%, 94%, and 81%, respectively. Immunoscintigraphy of xenografts of human A431 and A549 cells in nude mice both showed that (125)I-labeled-LA22-MMC enriched in tumor sites prominently. Most importantly, in vivo assays showed LA22-MMC was significantly more effective than free drug MMC in the treatment of subcutaneous xenografts of human A431 cells in nude mice (83% inhibition for LA22-MMC and 30% for MMC). We concluded that LA22-MMC could be a very potent drug for treatment of solid tumors.

Animals↗

PubMed2004

Development of miniaturized competitive immunoassays on a protein chip as a screening tool for drugs.

BACKGROUND: Doping in sports has become a serious problem. Gas chromatography-mass spectrometry (GC-MS) serves as an effective reference method, but it is limited by low throughput and is therefore not suitable for large-scale screening. Use of protein chips for high-throughput screening of all athletes for prohibited substances could become an important complementary tool to GC-MS. METHODS: We developed a protein chip based on an aldehyde-activated glass slide containing 10 physically isolated arrays. The chip was used to screen urine from 1347 athletes for prohibited substances and to screen a negative control group consisting of 200 females and 120 males. Urine samples from 66 individuals known to be abusers, provided by the China Doping Control Center (CDCC), and 129 standard prohibited substances were tested as positive controls. RESULTS: All 1347 urine samples screened by means of the protein chips were also subjected to reference analysis by GC-MS at the CDCC. There was no qualitative difference between the results obtained with the two methods. The correlation coefficient (r(2)) for the quantitative results obtained with the protein chip and GC-MS was 0.991. CONCLUSIONS: The protein chip could be used to screen for a series of 16 prohibited drugs in urine samples. This system has the potential to become an effective screening method to test substances prohibited by the International Olympic Committee.

Doping in Sports↗

PubMed2004

Preparation of steroid antibodies and parallel detection of multianabolic steroid abuse with conjugated hapten microarray.

A conjugated hapten microarray based on miniature immunoassay for fast and multiplex detection of anabolic steroids is reported for the first time. This preliminary study investigated the possibility of using a microarray technology as a multisteroid detection assay. The microarray system used eight monoclonal antibodies raised against three steroid conjugates, 4-androsten-4-chloro-17beta-ol-3-one, 1,5alpha-androsten-1beta-methyl-17beta-ol-3-one, and 5beta-androsten-1-en-17beta-ol-3-one, which were conjugated to BSA by the active ester method. In addition to 4 commercial conjugated haptens, 18 steroid-BSA conjugates were synthesized and from all these a conjugated hapten microarray was fabricated. The analyzed substances included 42 types of anabolic steroid reference materials and 28 positive urine samples. Of these, 24 anabolic steroids and 12 positive urines were successfully detected.

Anabolic Agents↗

PubMed2004

Analysis of benzyldimethyldodecylammonium bromide in chemical disinfectants by liquid chromatography and capillary electrophoresis.

Two novel analytical methodologies using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were developed and compared for the determination of benzyldimethyldodecylammonium bromide (BAB) in commercial compound chemical disinfectants. The LC analysis was performed with a Kromasil C18 (200 mm x 4.6 mm, 5 microm) column and a mobile phase of A:B = 80:20 (A: acetonitrile, B: 4 mmol/L octanesulfonic sodium--0.02 mol/L acetic sodium, adjusted with acetic acid to pH 5.2) at a flow rate of 1.0 mL/min. Detection was by ultraviolet absorption at 262 nm. The CE analysis was performed in a bare fused-silica capillary with 75 microm i.d. and total length of 46.4 cm with a buffer solution of 50% acetonitrile -50 mmol/L NaH2PO4, pH 2.24. The applied voltage was 20 kV. Detection was by ultraviolet absorption at 214 nm. Under optimized conditions, the HPLC retention time and CE migration time for BAB was 9.18 and 5.08 min, respectively. Calibration curves of peak area versus concentration gave correlation coefficients of 0.9996 for HPLC and 0.9994 for CE. The detection limits for HPLC and CE were 1.6 mg/L and 0.2 mg/L, respectively. Average recoveries at three concentration levels (50, 100, 200 mg/L for HPLC: 20, 40, 100 mg/L for CE) were 99.94 +/- 1.5, 99.64 +/- 1.3 and 99.61 +/- 0.4% for HPLC and 120.47 +/- 2.6, 102.06 +/- 8.7 and 103.05 +/- 3.0% for CE, respectively. Although both methods were shown to be suitable for the determination of BAB in commercial disinfectant compounds, CE provided analysis with less solvent purchase/disposal and better column efficiency, whereas HPLC provided superior precision.

Benzalkonium Compounds↗

PubMed2004

[Simultaneous determination of seven sexual hormones in cosmetics by reversed-phase high performance liquid chromatography].

An efficient method for analyzing seven sexual hormones in cosmetics, namely, estriol, estradiol-17beta, estrone, testosterone, methyl-testosterone, progesterone and diethylstilbestrol by reversed-phase high performance liquid chromatography was developed. Samples were saponified with 20 g/L sodium hydroxide. The sexual hormones were then extracted with dichloromethane-acetic acetate (40:1, v/v) under acidic conditions (pH 3, adjusted with 1 mol/L HCl). An XTerra RP18 column was employed and a mixture of water-methanol-acetonitrile (50:32:18, v/v) was used as mobile phase. The seven sexual hormones were detected at 230 nm. The average spiked recoveries for the seven sexual hormones ranged from 75.6% to 97.8% with relative standard deviations of 1.9% to 7.2%. The linear ranges of determination were from 5 to 50 mg/L with correlation coefficients of 0.9999, and the limits of detection were from 3.7 to 12 ng. The method is suitable to simultaneously assay the seven sexual hormones in cosmetics with simplicity and accuracy in a single injection.

Chromatography, High Pressure Liquid↗

PubMed2003

Local spectral time-domain method for electromagnetic wave propagation.

We explore the feasibility of using a local spectral time-domain (LSTD) method to solve Maxwell's equations that arise in optical and electromagnetic applications. The discrete singular convolution (DSC) algorithm is implemented in the LSTD method for spatial derivatives. Fourier analysis of the dispersive error of the DSC algorithm indicates that its grid density requirement for accurate simulations can be as low as approximately two grid points per wavelength. The analysis is further confirmed by numerical experiments. Our study reveals that the LSTD method has the potential to yield high resolution for solving large-scale electromagnetic problems.

Journal Article↗

PubMed2003

[Analysis of kojic acid in Aspergillus oryzae ferment by ion-pair reversed-phase high performance liquid chromatography].

A new and an efficient method for analyzing kojic acid in aspergillus oryzae ferment by ion-pair reversed-phase high performance liquid chromatography was developed. The kojic acid was well separated on a C18 column using methanol-0.01 mol/L disodium hydrogen phosphate and 2 mmol tetrabutylammonium bromide (4:96) as the mobile phase, followed by an UV detection at 226 nm. The detection limit was 0.012 microgram/ml. The spiked recoveries in wort-yeast culture, wort-peptone culture and potato-yeast-sugar culture were 98.2%, 103.4% and 97.2%, respectively. The RSD values were 0.51%, 0.45% and 0.43% respectively.

Aspergillus oryzae↗

PubMed2002

Synchronization and information processing by an on-off coupling.

This paper proposes an on-off coupling process for chaos synchronization and information processing. An in depth analysis for the net effect of a conventional coupling is performed. The stability of the process is studied. We show that the proposed controlled coupling process can locally minimize the smoothness and the fidelity of dynamical data. A digital filter expression for the on-off coupling process is derived and a connection is made to the Hanning filter. The utility and robustness of the proposed approach is demonstrated by chaos synchronization in Duffing oscillators, the spatiotemporal synchronization of noisy nonlinear oscillators, the estimation of the trend of a time series, and restoration of the contaminated solution of the nonlinear Schrödinger equation.

Journal Article↗

PubMed2002

[Rapid determination of metallothioneins in foods by capillary zone electrophoresis].

A rapid method for the analysis of metallothioneins (MT) in foods by capillary zone electrophoresis(CZE) was developed. Two isomers of MT (MT1, MT2) in foods were separated and determined. After a series of optimization, the separation and determination of MT1 and MT2 were obtained within 10 min by using the phosphate buffer system consisting of 0.02 mol/L Na2HPO4 and 0.02 mol/L NaH2PO4 (pH 7.0), and UV detection at 200 nm. Under the optimal experimental conditions, the minimum detectable limit was 1 mg/L, and the added standard recoveries of MT1, MT2 in foods were found to be in the range of 82.0%-93.4%. The relative standard deviations (RSD) were found to be lower than 10%. Therefore, with this simple and rapid method, the contents of two isomers in foods can be determined by external standard method after sample pretreatment.

Animals↗