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Biomedical subjects

Chun Chen

Publications and source records attributed to Chun Chen.

47 records · Page 3Linked to original sources
PubMed2002

Interaction of p58(PITSLRE), a G2/M-specific protein kinase, with cyclin D3.

The p58(PITSLRE) is a p34(cdc2)-related protein kinase that plays an important role in normal cell cycle progression. Elevated expression of p58(PITSLRE) in eukaryotic cells prevents them from undergoing normal cytokinesis and appears to delay them in late telophase. To investigate the molecular mechanism of p58(PITSLRE) action, we used the yeast two-hybrid system, screened a human fetal liver cDNA library, and identified cyclin D3 as an interacting partner of p58(PITSLRE). In vitro binding assay, in vivo coimmunoprecipitation, and immunofluorescence cell staining further confirmed the association of p58(PITSLRE) with cyclin D3. This binding was observed only in the G(2)/M phase but not in the G(1)/S phase of the cell cycle; meanwhile, no interaction between p110(PITSLRE) and cyclin D3 was observed in all the cell cycle. The overexpression of cyclin D3 in 7721 cells leads to an exclusively accumulation of p58(PITSLRE) in the nuclear region, affecting its cellular distribution. Histone H1 kinase activity of p58(PITSLRE) was greatly enhanced upon interaction with cyclin D3. Furthermore, kinase activity of p58(PITSLRE) was found to increase greatly in the presence of cyclin D3 using a specific substrate, beta-1,4-galactosyltransferase 1. These data provide a new clue to our understanding of the cellular function of p58(PITSLRE) and cyclin D3.

Cyclin D3↗
PubMed2002

Different effects of p58PITSLRE on the apoptosis induced by etoposide, cycloheximide and serum-withdrawal in human hepatocarcinoma cells.

Minimal overexpression of the p58PITSLRE protein kinase in Chinese hamster ovary cells induces telephase delay, abnormal cytokinesis, retarded cell growth and apoptosis. Fas mediated T cell death is correlated with p58PITSLRE proteolysis and an increase in its histone H1 kinase activity. In this study, it was found that p58PITSLRE had different effects on the apoptosis induced by etoposide, cycloheximide and serum-withdrawal in human hepatocarcinoma cells. The ectopic expression of p58PITSLRE in human hepatocarcinoma cells suppressed apoptosis induced by etoposide, while enhancing the apoptosis induced by cycloheximide and serum-withdrawal respectively. Elevated expression of p58PITSLRE was found during the apoptosis induced by etoposide, whereas most of p58PITSLRE was proteolytically processed during apoptosis induced by cycloheximide and serum-withdrawal. Furthermore, transient transfection of p50PITSLRE resembling the proteolytic form of p58PITSLRE enhanced the 7,721 cells susceptibility to apoptosis induced by all the three stimuli. These findings suggest that the full-length p58PITSLRE might protect the cells from the apoptosis induced by etoposide and its proteolysis might contribute to and enhance the apoptosis induced by cycloheximide and serum-withdrawal respectively.

Apoptosis↗
PubMed2002

Endocardial mapping and ablation of tachycardia guided by noncontact balloon catheter mapping system.

OBJECTIVE: To describe a new noncontact balloon catheter mapping system and to assess the clinical utility of this system for guiding endocardial mapping and ablation of tachycardia. METHODS: Five patients with tachycardia underwent endocardial mapping and radiofrequency ablation using the noncontact balloon catheter mapping system. A 9 French, 64-electrode balloon catheter and a conventional 7 French electrode catheter for mapping and ablation were positioned in the same ventricular chamber. Ventricular three-dimensional geometry was established by the computerized mapping system. Using a boundary element inverse solution, 3360 virtual endocardial electrograms were computerized and used to derive isopotential maps. The earliest endocardial activation site, the exit site and the activation sequence of tachycardia or the critical isthmus of the reentry circuit were identified. Radiofrequency ablation with circular or linear lesion was performed at the target sites guided by the locator system. RESULTS: Six clinical types of tachycardia, 5 of which were ventricular tachycardia and one was concealed fasciculoventricular fiber mediated tachycardia, were induced by programmed stimulation. The mean cycle length of these tachycardias was 336.6 +/- 42.69 msec. The earliest activation site and the exit site of 5 mapped tachycardias were all identified using the system. One type of ventricular tachycardia was hemodynamically unstable and difficult to terminate, and could not be mapped. Among the 6 types of tachycardias, radiofrequency ablation was successful in 4. There was no complication during and after the procedure. During the mean follow-up of 6 months, no tachycardia recurred in the patients with a successful ablation. CONCLUSIONS: The noncontact mapping system described in this study has advantage over conventional mapping techniques for refractory tachycardia. It is not only helpful for understanding the electrophysiologic mechanism of a complex case, but also suitable for mapping hemodynamically intolerated and nonsustained ventricular tachycardia.

Adult↗
PubMed2002

Antropyloroduodenal motility after resection of esophageal cancer.

OBJECTIVE: To study the mechanism of delayed emptying indigestible solids in thoracic stomach after the resection of esophageal cancer by monitoring the variety of antropyloroduodenal migrating motor complex (MMC) during interdigestion. METHODS: Esophagectomy and gastroesophagostomy in the neck was performed in 5 men with esophageal cancer. An eight-lumen manometric sleeve assembly was passed through a nostril into the duodenum during operation. The sleeve was astride the pylorus. Antropyloroduodenal manometry was performed for at least 300 min with a polygraphic system (PC POLYGRAF HR) 7 - 11 days after operation. RESULTS: Twenty-eight MMCs were recorded in the pylorus and duodenum, 12 MMC(s) in the antrum, and 33% (4/12) of the motility frequency of antral phases III started after that of pyloroduodenal phases III. The number of MMC in the antrum was lower than that in the duodenum after the operation. The mean duration of MMC of the antrum, pylorus and duodenum was (49.2 +/- 10.5) min, (46.5 +/- 10.4) min and (45.9 +/- 10.0) min respectively. The mean duration of phases III was respectively (6.7 +/- 3.5) min in the antrum, (10.0 +/- 3.5) min in pylorus, and (8.0 +/- 3.9) min in duodenum. The mean wave amplitude of phases III was respectively (83 +/- 30) mm Hg in the antrum, (60 +/- 12) mm Hg in pylorus, and (55 +/- 4) mm Hg in duodenum. The mean duration of MMC of the antrum and duodenum was shorter in patients than that in healthy volunteers, and the mean wave amplitude of phases III of the antrum was lower in patients than that in healthy volunteers. CONCLUSIONS: Diminution of the number of MMC and the mean wave amplitude of phases III in the antrum, incoordination of the antropyloroduodenal phases III should be the most important one of the mechanisms of delayed emptying of indigestible solids in thoracic stomach after the resection of esophageal cancer.

Duodenum↗
PubMed2002

[Association of the relationship between HLA-DQB1 alleles and major beta-thalassemia in 42 guangdong Chinese].

To investigate the relationship between HLA-DQB1* alleles and major beta-thalassemia, the HLA-DQB1* loci typing was performed with polymerase chain reaction-sequence specific primer (PCR-SSP) in 42 unrelated (unconsanguineous) patients with major beta-thalassemia and 45 normal control individuals in Guangdong Province. Results showed that the frequency of HLA-DQB1*06 allele in patient group (19.0%) was higher than that in the control group (4.4%) kappa(2) = 8.961, p < 0.01). Our data suggests that HLA-DQB1*06 allele is associated with pathogenesis of the major beta-thalassemia in Guangdong area.

Alleles↗
PubMed2001

[Clinical Study on A Patient with Intestinal Acute Graft-Versus-Host Disease Grade IV after Allo-Peripheral Blood Stem Cell Transplantation]

The purpose of this study was to designed to analyze and explore the diagnosis and treatment on a patient with beta-thalassemia major accompanied with intestinal acute graft-versus-host disease (aGVHD) grade IV after allo-peripheral blood stem cell transplantation (allo-PBSCT). The conditioning regimen was consisted of busulfan (18 mg/kg), cyclophosphamide (200 mg/kg), thiotepa (6 mg/kg) and horse anti-thymocyte globulin (110 mg/kg). The nucleated cells (10.6 x 10(9)/kg) and CD34(+) CD38(-) cells (11.7 x 10(6)/kg) were infused. At +14 days PBSCT, ANC and WBC achieved 0.66 x 10(9)/L and 1.4 x 10(9)/L respectively. The engraftment was successful but the patient depended on transfusion. The range of blood WBC was from 1.4 x 10(9)/L to 2.4 x 10(9)/L. The myelogram showed aplastic anemia. Hematopoiesis was restored continually after the second transfusion of the donor's cells. At +11 days the patient was suffered from cutaneous aGVHD grade II. Diarrhea occurred at +33 day when cutaneous aGVHD had been improved, and exaggerated obviously after the second transfusion at +39 days. The serious diarrhea continued for 2 months and intestinal aGVHD grade IV was finally diagnosed. Our conclusion was that intestinal aGVHD possibly occurred even when cutaneous aGVHD was improved. For a patient with refractory diarrhea after allo-PBSCT, intestinal aGVHD was considered first when the engraftment evidence was definited but peripheral blood cells and bone marrow were abnormal.

Journal Article↗
PubMedDate not supplied

Allogeneic peripheral blood stem cell transplantation in beta-thalassemia.

Six transfusion-dependent beta-thalassemia major patients were treated with allogeneic peripheral blood stem cell (PBSC) transplant. The donors were HLA identical siblings except one donor who was a father with one-antigen mismatch of HLA-B loci. The donors were mobilized with G-CSF and PBSC was infused without manipulation. Engraftment was documented in all patients. Acute graft versus host disease (GvHD) was present in 4 patients but could be controlled with steroid or/and ATG. One patient died of hepatic veno-occlusive disease (HVOD) and survivors were all transfusion independent (ex-thalassemia). Chronic GvHD occurred in one patient. Allogeneic PBSC transplantation could achieve disease-free survival in beta-thalassemia major patients.

Adolescent↗
PubMedDate not supplied

Immunosuppressive treatment of aplastic anemia in Chinese children with antithymocyte globulin and cyclosporine.

Fifty-one children with aplastic anemia (AA) from 1993 to 2004 in the authors' institution were treated by 3 therapies: 11 patients in group 1 received the SSL-6 protocol; 16 patients in group 2 had CsA alone, where the dose of CsA began from 9-12 mg/kg in the initial 2 weeks and tapered off to 5 mg/kg later; 24 patients in group 3 were treated combining rabbit ATG (Pasteur, Merieux) 2.5 mg/kg for 5 days with CsA, which was the same dose as in group 2. The response was 27, 50, and 79%, respectively. The statistical analysis showed that the protocol of intensive immunosuppressive treatment (IST) was the most effective one and CsA was better than that of SSL-6. None of our patients developed clone diseases although the follow-up was as long as more than to 9 years. The data suggest that children with AA should receive IST as first-line therapy in developing countries. Hematopoietic stem cell transplantation (HSCT) is effective treatment for patients with aplastic anemia (AA). However, HSCT is not widely used in China for economic reasons and lack of donors. Immunosuppressive therapy (IST) is now the mainstay treatment for AA. To evaluate the effect of immunosuppressive therapy, combining antithymocyte globulin (ATG) with cyclosporine (CsA), a retrospective study on 51 children with AA from January 1993 to December 2004 treated in the authors' department was performed.

Adolescent↗
PubMedDate not supplied

A color based face detection system using multiple templates.

A color based system using multiple templates was developed and implemented for detecting human faces in color images. The algorithm consists of three image processing steps. The first step is human skin color statistics. Then it separates skin regions from non-skin regions. After that, it locates the frontal human face(s) within the skin regions. In the first step, 250 skin samples from persons of different ethnicities are used to determine the color distribution of human skin in chromatic color space in order to get a chroma chart showing likelihoods of skin colors. This chroma chart is used to generate, from the original color image, a gray scale image whose gray value at a pixel shows its likelihood of representing the skin. The algorithm uses an adaptive thresholding process to achieve the optimal threshold value for dividing the gray scale image into separate skin regions from non skin regions. Finally, multiple face templates matching is used to determine if a given skin region represents a frontal human face or not. Test of the system with more than 400 color images showed that the resulting detection rate was 83%, which is better than most color-based face detection systems. The average speed for face detection is 0.8 second/image (400 x 300 pixels) on a Pentium 3 (800MHz) PC.

Adult↗
PubMedDate not supplied

Web multimedia information retrieval using improved Bayesian algorithm.

The main thrust of this paper is application of a novel data mining approach on the log of user's feedback to improve web multimedia information retrieval performance. A user space model was constructed based on data mining, and then integrated into the original information space model to improve the accuracy of the new information space model. It can remove clutter and irrelevant text information and help to eliminate mismatch between the page author's expression and the user's understanding and expectation. User space model was also utilized to discover the relationship between high-level and low-level features for assigning weight. The authors proposed improved Bayesian algorithm for data mining. Experiment proved that the authors' proposed algorithm was efficient.

Algorithms↗