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Biomedical subjects

Yi Tang

Publications and source records attributed to Yi Tang.

115 records · Page 7Linked to original sources
PubMed2002

[Detection of DNA damage of human sperm using single cell electrophoresis].

OBJECTIVES: To detect the sperm DNA damage and to evaluate its significance in male reproductive using single cell gel electrophoresis (SCGE). METHODS: Four hundred and eighteen sperm samples were analysed using the computer assisted analysis system and SCGE. The sperms samples were divided into five grades according to the extent of the sperm nuclear DNA damage. RESULTS: 1. When the sperm density is less than 20 x 10(6)/ml, the occurence of grade II and III are increased significantly; 2. In the unmotile grade d sperm the occurence of grade I comet amounts was 5.39%, the occurence of grade II and III was remarkably increased. There was a evidently variance between the grade d and grade a + b sperm. CONCLUSIONS: SCGE can be used to detect the sperm DNA breakage and to evaluate the sperm quality and damage.

Adolescent↗
PubMed2002

[Determination of trace element Cu, Zn, Mg, Cr in serum of women with barrenness and hysteromyoma disease].

Using AAs method, we detected serum Zn, Cu, Mg, Cr in the women with barrenness and hysteromyoma disease. The results showed that the level of serum Cu and Cr of women with hysteromyoma were significantly higher than those in the healthy control group. (P < 0.01), the level of serum Zn of those were significantly lower than those in the control (P < 0.01). In the serum of those with barrenness disease, the level of Zn, Cr is significantly lower than the control group (P < 0.01). It is suggested that trace element Cu, Zn, Cr are interrelated with hysteromyoma disease, Zn, Cr are interrelated with women barrenness disease.

Adult↗
PubMed2001

[Establishment of the Cell Line U937-ASPI3K with Stable Expression of Antisense ATM/PI3K]

In order to provide a valuable cell model for studying the mechanism of DNA damage to kill tumor cells and enhance the curative effect, an antisense cDNA, which effectively expressed ATM gene encoding carboxyl terminal 100 kD domain fragment, was constructed, and a cell line U937-ASPI3K, which stably expressed the antisense ATM/PI3K cDNA was established through transfection and Zeocin selection. The results showed the constructed ATM/PI3K cDNA is in the opposite orientation in expression vector pZeoSV2(+) through examination of gene sequence. The cell line U937-ASPI3K was total loss of constitutive ATM protein, while the ATM abundance was not influenced in both the control cell lines U937-pZeoSV(-) and U937. The present experiment provided a practical cell model to elusidate mechanism of cell cycle checkpoints in DNA damage signal transduction pathway and search a new approach for tumor therapy.

Journal Article↗
PubMedDate not supplied

Near-infrared fluorescent nanoparticles as combined MR/optical imaging probes.

A number of quantitative three-dimensional tomographic near-infrared fluorescence imaging techniques have recently been developed and combined with MR imaging to yield highly detailed anatomic and molecular information in living organisms (1, 2). Here we describe magnetic nanoparticle based MR contrast agents that have a near-infrared fluorescence (NIRF) that is activated by certain enzymes. The probes are prepared by conjugation of arginyl peptides to cross-linked iron oxide amine (amino-CLIO), either by a disulfide linkage or a thioether linker, followed by the attachment of the indocyanine dye Cy5.5. The NIRF of disulfide-linked conjugate was activated by DTT, while the NIRF of thioether-linked conjugate was activated by trypsin. Fluorescent quenching of the attached fluorochrome occurs in part due to the interaction with iron oxide, as evident by the activation of fluorescence with DTT when nanoparticles that have less than one dye attached per particle. With a SC injection of the probe, axillary and brachial lymph nodes were darkened on MR images and easily delineated by NIRF imaging. The probes may provide the basis for a new class of so-called smart nanoparticles, capable of pinpointing their position through their magnetic properties, while providing information on their environment by optical imaging techniques.

Animals↗
PubMedDate not supplied

Enhanced tumor detection using a folate receptor-targeted near-infrared fluorochrome conjugate.

Fluorescence optical imaging technologies are currently being developed to image specific molecular targets in vivo. Detection technologies range from those providing microscopic detail to whole body imaging systems with potential clinical use. A number of target-specific near-infrared imaging probes have recently been developed to image receptors, antigens, and enzymes. The goal of the current study was to evaluate a new near-infrared (NIR) folate receptor (FR)-targeted imaging probe for its ability to improve detection of FR-positive cancers. We hypothesized that modification of folate would retain receptor affinity in vivo, despite the bulkier NIR fluorochrome, NIR2 (em = 682 nm). Cellular uptake of the NIR conjugates was significantly higher in FR-positive nasopharyngeal epidermoid carcinoma, KB cells, compared to FR-negative human fibrosarcoma, HT1080 cells. When tumors were implanted in vivo, equal-sized KB tumors showed a 2.4-fold higher signal intensity compared to HT1080 tumors (24 h). The maximum signal-to-background ratio (3-fold) was observed at 24 h in KB tumor. Injection of the unmodified NIR2 fluorochrome did not result in persistent contrast increases under similar conditions. Furthermore, tumor enhancement with the NIR2-folate probe persisted over 48 h and was inhibitable in vivo by administration of unlabeled folate. These results indicate that folate-modified NIR fluorochrome conjugate can be used for improved detection of FR-positive tumors.

Animals↗
PubMedDate not supplied

A novel method for imaging apoptosis using a caspase-1 near-infrared fluorescent probe.

Here we describe a novel method for imaging apoptosis in cells using a near-infrared fluorescent (NIRF) probe selective for caspase-1 (interleukin 1beta-converting enzyme, ICE). This biocompatible, optically quenched ICE-NIRF probe incorporates a peptide substrate, which can be selectively cleaved by caspase-1, resulting in the release of fluorescence signal. The specificity of this probe for caspase-1 is supported by various lines of evidence: 1) activation by purified caspase-1, but not another caspase in vitro; 2) activation of the probe by infection of cells with a herpes simplex virus amplicon vector (HGC-ICE-lacZ) expressing a catalytically active caspase-1-lacZ fusion protein; 3) inhibition of HGC-ICE-lacZ vector-induced activation of the probe by coincubation with the caspase-1 inhibitor YVAD-cmk, but not with a caspase-3 inhibitor; and 4) activation of the probe following standard methods of inducing apoptosis with staurosporine, ganciclovir, or ionizing radiation in culture. These results indicate that this novel ICE-NIRF probe can be used in monitoring endogenous and vector-expressed caspase-1 activity in cells. Furthermore, tumor implant experiments indicate that this ICE-NIRF probe can be used to detect caspase-1 activity in living animals. This novel ICE-NIRF probe should prove useful in monitoring endogenous and vector-expressed caspase-1 activity, and potentially apoptosis in cell culture and in vivo.

Animals↗