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Biomedical subjects

H-Y Chen

Publications and source records attributed to H-Y Chen.

9 recordsLinked to original sources
PubMed2006

The role of the VEGF-C/VEGFR-3 axis in cancer progression.

Vascular endothelial growth factor (VEGF) receptor 3 (VEGFR-3) (also called VEGFR-3) is activated by its specific ligand, VEGF-C, which promotes cancer progression. The VEGF-C/VEGFR-3 axis is expressed not only by lymphatic endothelial cells but also by a variety of human tumour cells. Activation of the VEGF-C/VEGFR-3 axis in lymphatic endothelial cells can facilitate metastasis by increasing the formation of lymphatic vessels (lymphangiogenesis) within and around tumours. The VEGF-C/VEGFR-3 axis plays a critical role in leukaemic cell proliferation, survival, and resistance to chemotherapy. Moreover, activation of the VEGF-C/VEGFR-3 axis in several types of solid tumours enhances cancer cell mobility and invasion capabilities, promoting cancer cell metastasis. In this review, we discuss the novel function and molecular mechanism of the VEGF-C/VEGFR-3 axis in cancer progression.

Disease Progression↗
PubMed2006

The presence of X- and Y-chromosomes in oocytes leads to impairment in the progression of the second meiotic division.

The oocytes of B6.Y(TIR) sex-reversed female mice can be fertilized but the resultant embryos die at early cleavage stages. In the present study, we examined chromosome segregation at meiotic divisions in the oocytes of XY female mice, compared to those of XX littermates. The timing and frequency of oocyte maturation in culture were comparable between the oocytes from both types of females. At the first meiotic division, the X- and Y-chromosomes segregated independently and were retained in oocytes at equal frequencies. However, more oocytes retained the correct number of chromosomes than anticipated from random segregation. The oocytes that had reached MII-stage were activated by fertilization or incubation with SrCl(2). As expected, the majority of oocytes from XX females completed the second meiotic division and reached the 2-cell stage in 24 h. By contrast, more than half of oocytes from XY females initially remained at the MII-stage while the rest precociously entered interphase after SrCl(2) activation; very few oocytes were seen at the second anaphase or telophase and they often showed impairment of sister-chromatid separation. Eventually the majority of oocytes entered interphase and formed pronuclei, but very few reached the 2-cell stage. Similar results were obtained after fertilization. We conclude that the XY chromosomal composition in oocyte leads to impairment in the progression of the second meiotic division.

Animals↗
PubMed2006

Local tunneling spectroscopy as a signature of the Fulde-Ferrell-Larkin-Ovchinnikov state in s- and d-wave superconductors.

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states for two-dimensional s- and d-wave superconductors (s- and d-SCs) are self-consistently studied under an in-plane magnetic field. While the stripe solution of the order parameter is found to have lower free energy in s-SCs, a square lattice solution appears to be energetically more favorable in the case of d-SCs. At certain symmetric sites, we find that the features in the local density of states (LDOS) can be ascribed to two types of bound states. We also show that the LDOS maps for d-SCs exhibit bias-energy-dependent checkerboard patterns. These characteristics can serve as signatures of the FFLO states.

Journal Article↗
PubMed2006

C2GnT-M is downregulated in colorectal cancer and its re-expression causes growth inhibition of colon cancer cells.

Changes in carbohydrates on the cell surface are associated with tumor malignancy. The mucin-type core 2 beta-1,6-N-acetylglucosaminyltransferase (C2GnT-M) is highly expressed in the gastrointestinal tract and catalyses the formation of core 2, core 4, and blood group I branches on O-glycans. In the present study, we evaluated the role of C2GnT-M in colorectal cancer. C2GnT-M downexpression was observed in 73.6% of the primary tumors from colorectal cancer patients (39 of 53) analysed by cancer profiling array. Consistently, the majority of colon cancer cell lines and primary colon tumors expressed lower levels of C2GnT-M than did normal colon tissues by RT-PCR. HCT116 cells stably transfected with C2GnT-M inhibited expression of the core 1 structure, Galbeta1,3GalNAcalpha1-Ser/Thr, on the cell surface. Moreover, C2GnT-M expression suppressed cell adhesion, motility, and invasion as well as colony formation ability. The growth of C2GnT-M-transfected HCT116 and SW480 cells was dramatically suppressed, and the cell death induced by C2GnT-M was demonstrated by an increase in the annexin V-positive cells. Interestingly, C2GnT-M inhibited cell adhesion to collagen IV and fibronectin, and decreased tyrosine phosphorylation of paxillin, indicating that the changes in cancer behavior may be partly mediated by integrin-signaling pathways. Tumor growth in vivo was also significantly suppressed by C2GnT-M in the xenografts of nude mice. These results demonstrate that C2GnT-M is frequently downregulated in colorectal cancer and suppresses colon cancer cell growth.

Animals↗
PubMed2006

The role of simeticone in small-bowel preparation for capsule endoscopy.

BACKGROUND AND STUDY AIMS: Capsule endoscopy is a new diagnostic method allowing painless visualization of the entire small bowel. However, there is as yet no standardized protocol for bowel preparation before the examination. The aim of this study was to assess the effectiveness of simeticone in reducing bowel gas bubbles in patients undergoing capsule endoscopy. PATIENTS AND METHODS: A randomized, prospective, and controlled study was conducted, including 56 patients, from March to October 2004. The patients were randomly allocated to groups receiving either simeticone or no simeticone, on the basis of a computer-generated random number table. Patients in the simeticone group (n = 28) received 300 mg simeticone for bowel preparation 20 min before capsule endoscopy, while patients in the non-simeticone group (n = 28) received no medication for bowel preparation. Two experienced endoscopists assessed and graded the visibility of the mucosa and intraluminal gas bubbles in a single-blinded fashion. RESULTS: The visibility of the mucosa in the proximal small bowel in patients who received preparation with simeticone was considered to be better, with fewer intraluminal bubbles, than in those without bowel preparation ( P < 0.025). Interobserver agreement was excellent ( R > or = 0.8, P < 0.05). No adverse effects of simeticone were observed. CONCLUSIONS: Simeticone administration before capsule endoscopy improves the visualization of the mucosa in the proximal small intestine.

Adolescent↗
PubMed2004

Silica-nanoparticle-based interface for the enhanced immobilization and sequence-specific detection of DNA.

A biocompatible and uniform interface based on silica nanoparticles derivatized with amino groups has been constructed for the effective immobilization and sensitive sequence-specific detection of calf thymus DNA. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) results showed that a monolayer of silica nanoparticles can be formed on a gold electrode under our experimental conditions using cysteine self-assembly monolayer as binder medium. Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy (XPS) verified the successful immobilization of DNA on silica-nanoparticle-modified gold electrodes. Quantitative results demonstrated that enhanced immobilization of single-strand DNA (ss-DNA) up to 1.6 x 10(-8) mol cm(-2) could be achieved owing to the larger surface area and the special properties of silica nanoparticles. In addition, hybridization experiments demonstrated that the immobilized ss-DNA on silica nanoparticles could specifically interact with complementary DNA in solutions.

Animals↗
PubMed2004

Surface plasmon resonance detection of interactions between peptide fragments of N-telopeptide and its monoclonal antibodies.

As populations age, osteoporosis is becoming an important public health care problem. Urinary level of the cross-linked N-telopeptide of type I collagen has been reported to be a sensitive marker of bone resorption. Recently, we synthesized and characterized 10 overlapping peptides covering the N-telopeptide of alpha-2 type I collagen and reported their relative binding response to anti-type I collagen cross-linked N-telopeptide (NTX) antibodies determined by a competitive-inhibition enzyme-linked immunosorbent assay (ELISA). In this study, we design an assay based on the surface plasmon resonance (SPR) technology to detect binding interaction of each peptide fragment of NTX with the anti-NTX monoclonal antibodies. Anti-NTX monoclonal antibodies were immobilized on the surface of sensor chip by amine-coupling procedure. Serial dilutions of each peptide were prepared and injected separately onto the antibodies-immobilized sensor chip. The real-time association and dissociation interactions of each peptide were detected and reported as sensorgrams. Binding response of each peptide to the monoclonal antibodies was determined, and the SPR results were compared with the ELISA results. We demonstrate that the trends of binding potency of peptide fragments detected by SPR are in good correlation to the results obtained by ELISA, indicating that our developed SPR-based method can be further applied to detect the NTX fragments in urine and to monitor the bone loss in humans. The potent peptide fragments identified by both assays are promising for further preparation of specific monoclonal antibodies in order to develop bioassays for bone loss in humans.

Antibodies, Monoclonal↗
PubMed2003

Increased incidence of cytomegalovirus but not Chlamydia pneumoniae in atherosclerotic lesions of arteries of lower extremities from patients with diabetes mellitus undergoing amputation.

AIMS: To evaluate the association between cytomegalovirus (CMV) or Chlamydia pneumoniae infection and the development of accelerated atherosclerotic lesions in patients with diabetes who are known to have an impaired immune response to infection and a high incidence of atherosclerosis. METHODS: Two hundred arterial samples from patients with diabetes who had undergone surgical amputation for gangrenous lower limbs were selected to assess the presence of CMV or C pneumoniae nucleic acid by means of the polymerase chain reaction. RESULTS: CMV nucleic acid sequences were detected in 64 of 200 (32%) samples and C pneumoniae in seven of 200 (3.5%) arterial samples with severe atherosclerosis. Of those positive for C pneumoniae, six were also positive for CMV. CONCLUSION: The significantly higher incidence of CMV nucleic acid sequences in the arterial samples of patients with diabetes supports the hypothesis that this organism is involved in the pathogenesis of atherosclerosis in patients with diabetic mellitus. It is possible that the potential role of different infectious agents in the pathogenesis of atherosclerosis might rely on their biological properties and their infectivity in hosts with varying immunological status.

Aged↗