Biomedical subjects

Jiyan Chen

Publications and source records attributed to Jiyan Chen.

7 recordsLinked to original sources

PubMed2006

Purification method directly influences effectiveness of an epidermal growth factor-coupled targeting agent for noninvasive tumor detection in mice.

Receptor targeting is an effective method of enhancing fluorescence signal in tumors for optical imaging. We previously used epidermal growth factor (EGF) conjugated to IRDye 800CW to detect and track orthotopic prostate tumors in mice. In this study, our goal was to identify a reliable assay for targeting agent integrity in vitro that correlated with signal strength in vivo. Binding of IRDye 800CW EGF to intact A431 human epidermoid carcinoma cells was quantified in a microplate assay. Specificity was confirmed by competition with unlabeled EGF or monoclonal antibody blocking. Biological activity of intact and damaged targeting agents relative to unlabeled EGF was determined by binding and stimulation of extracellular signal-regulated kinase (ERK) phosphorylation. Both assays indicated a reduction of up to 60% of the fluorescence intensity with damaged agents. Using a research prototype imaging system optimized for IRDye 800CW detection, we compared the efficacy of intact and damaged targeting agents for imaging subcutaneous tumors in mice. In live animal images and in sections of the excised tumors, damaged targeting agents consistently yielded diminished fluorescence signals corresponding to the reduction observed in microplate assays. This is the first study to directly correlate targeting agent signal strength in whole cell binding, In-Cell Western, and in vivo near-infrared imaging.

Animals↗

PubMed2006

Hyaluronidase expression induces prostate tumor metastasis in an orthotopic mouse model.

Molecular mechanisms of prostate cancer progression are frequently studied in mice by orthotopic injection of aggressive cell lines, which yield primary tumors that spontaneously metastasize to lymph nodes. In this report, we characterized the human prostate carcinoma cell line 22Rv1 in an orthotopic system and evaluated the functional relevance of the hyaluronidase Hyal1, a correlate of invasive human prostate cancer, to progression in this model. To provide real-time insights into these processes, we first validated use of an epidermal growth factor-conjugated fluorophore to illuminate orthotopic prostate tumors and their metastases in whole animal imaging. Animals receiving intraprostatic injections were tracked throughout a 6-week period. Tumor sizes were correlated 92% with total fluorescence intensities of 22 prostate tumors. In contrast to the highly tumorigenic and metastatic PC3M-LN4 cells, the 22Rv1 line was orthotopically tumorigenic but not metastatic, despite larger tumor sizes. Lymph node metastasis was successfully imaged in animals with PC3M-LN4 tumors on endpoint dissection. Stable transfection of 22Rv1 cells with Hyal1 did not alter growth kinetics of primary orthotopic tumors, but all animals implanted with Hyal1 transfectants exhibited tumor-positive para-aortic lymph nodes. Hyal1 is implicated as an inducer of prostate cancer metastatic progression.

Animals↗

PubMed2005

RACTS: a prospective randomized antiplatelet trial of cilostazol versus ticlopidine in patients undergoing coronary stenting: long-term clinical and angiographic outcome.

We compared the efficacy of cilostazol for the prevention of late restenosis and acute or subacute stent thrombosis with that of ticlopidine. Cilostazol has been used for antiplatelet therapy after coronary stent implantation, but the results are controversial. Patients scheduled for stent implantation were randomly assigned to receive either cilostazol (100 mg twice daily for 6 months, n=201) or ticlopidine (250 mg twice daily for 1 month, n=196). All patients also received oral aspirin (100 mg once daily for 6 months). Coronary angiography was performed at baseline and immediately and 6 months after coronary stenting. Clinical follow-up was continued up to 9 months postprocedure. There was no significant difference in the composite incidence of death, myocardial infarction, stroke, and stent thrombosis between the 2 groups [cilostazol (1.5%) versus ticlopidine (3.6%), P=0.216], but the target lesion revascularization rate per patient was significantly lower in the cilostazol group than in the ticlopidine group (22.9% vs 32.7%, P=0.030) 9 months post-coronary stenting. Medication withdrawn because of drug-related side effects tended to be higher in the ticlopidine group than that in the cilostazol group (3.5% vs 8.2%, P=0.054). At follow-up angiography, the minimal luminal diameters (2.31+/-1.06 vs 2.10+/-1.16, P=0.057) tended to be larger and the restenosis rates lower (23.3% vs 30.9%, P=0.086) in the cilostazol group than in the ticlopidine group. Aspirin plus cilostazol is a comparable antithrombotic regimen to aspirin plus ticlopidine after elective coronary stenting, but the rate of target lesion revascularization was significantly lower in the cilostazol group than in the ticlopidine group.

Adolescent↗

PubMed2003

[Cause and measure of short of quality control on Chinese medicine herbs].

Chinese medicine is short of quality control for three reasons. Firstly, near 90 percent Chinese medicine herbs are lack of quality standards and hard to be evaluated. Secondly, basal study falls behind relatively, which limites development speed of quality control and quality standard. Finally, Chinese medicine herbs haven't uniform refine operating norm. We must strengthen basal study, constitute the inspection norm of Chinese medicine herbs quality and establish perfect technical supervise system as fast as possible.

Animals↗

PubMed2002

Thiol-reactive lanthanide chelates for phasing protein X-ray diffraction data.

Lanthanides can contribute a large anomalous component to X-ray scattering when present and ordered in a target crystal. This large anomalous signal is a useful source of phase information in X-ray crystallographic studies of biological macromolecules. Thiol-reactive lanthanide chelates were tested as a means of incorporation of lanthanides into protein crystals. Two compounds, each capable of being loaded with a lanthanide of choice, were synthesized: diethylenetriaminepentaacetic 3-(2-pyridyldithio)propionyl hydrazide (DTPA-PDPH) and 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic 3-(2-pyridyldithio)propionyl hydrazide (DOTA-PDPH). A cysteine mutant of the 34 kDa phosphate-binding protein (PBP-A197C) from Escherichia coli was used as a test case. PBP-A197C was labeled with DTPA-PDPH loaded with dysprosium. Characteristics of DTPA-PDPH enabled spectroscopic monitoring of the labeling reaction. Complete labeling of PBP-A197C was confirmed by mass spectrometry and SDS-PAGE analysis. Labeled PBP-A197C (PBP-A197C-DTPA-Dy) crystallized identically to unlabeled protein. X-ray diffraction data were collected from PBP-A197C-DTPA-Dy crystals in-house with a Cu Kalpha rotating-anode source and with a tuneable synchrotron source (ALS 5.0.2). Synchrotron data were collected at energies corresponding to the Dy L(III) edge f" peak and a high-energy remote. Each data set was treated as an independent SAD experiment. A large anomalous signal was present in the data collected in-house and at the synchrotron. The Dy site was easily located in anomalous difference Patterson maps calculated from each of the data sets. In each case, SAD phasing resulted in high-quality electron-density maps, as evidenced by the success of automated model building. The generality of the method was analyzed with several other test proteins. Labeling of some of these proteins with thiol-reactive lanthanide chelates was deleterious to protein solubility or crystallization. In two of the cases the lanthanide chelate was disordered in the crystals. These results suggest that this method may not be well suited for high-throughput crystallography. However, for difficult cases requiring a large anomalous signal, thiol-reactive lanthanide chelates may prove to be a valuable tool.

Chelating Agents↗

PubMed2002

[Non-technical causes of fakes existing in Chinese medicinal material markets].

Non-technical causes of fakes existing in Chinese medicinal materials markets come from three aspects. Source of Chinese medicinal materials is complex and it is difficult to trace back to a source; lawless add impurities and use inferior goods pretending to superior quality and illegally seek for profit; supervising department lack strict blow and deterrent force is limitted.

China↗

PubMed2002

[Study concept of traditional Chinese medicine quality standards].

Chinese medicinal materials quality was controlled mainly by modern analytic approach, secondly by traditional identification method, popularizing based on improvement. Chinese medicine prepared slice quality was controlled mainly by traditional identification method, secondly by modern analytic approach, improving based on popularization.

Chromatography↗