Biomedical subjects

C Y Zheng

Publications and source records attributed to C Y Zheng.

7 recordsLinked to original sources

PubMed2002

Harmonic modulation instability and spatiotemporal chaos.

It is shown from the conserved Zakharov equations that many solitary patterns are formed from the modulational instability of unstable harmonic modes that are excited by a perturbative wave number. Pattern selection in our case is discussed. It is found that the evolution of solitary patterns may appear in three states: spatiotemporal coherence, chaos in time but the partial coherence in space, and spatiotemporal chaos. The spatially partial coherent state is essentially due to ion-acoustic wave emission, while spatiotemporal chaos characterized by its incoherent patterns in both space and time is caused by collision and fusion among patterns in stochastic motion. So energy carried by patterns in the system is redistributed.

Journal Article↗

PubMed2001

Regulation of surface and intracellular expression of CTLA-4 on human peripheral T cells.

Cytotoxic T-lymphocyte-associated antigen (CTLA-4) is an important downregulator of T-cell activation. In order to analyze the expression and regulation of CTLA-4 on human peripheral T cells, CTLA-4 mRNA and protein expression were determined using analysis by reverse transcription-polymerase chain reaction (RT-PCR) and FACs, respectively. Intracellular CTLA-4 was constitutively expressed in unstimulated CD4+ and CD8+ T cells. Interleukin (IL)-2 induced a dose-dependent increase of both intracellular and surface expression of CTLA-4 (CD152). Most of the CD4+ and CD8+ cells expressing CTLA-4 also expressed CD25. Interferon (IFN)-gamma induced the upregulation of CTLA-4 expression via antigen-presenting cells (APC) activation. The CTLA-4delTM mRNA (550 bp) had a shorter half-life than the full length CTLA-4 mRNA and the expression was downregulated upon activation of the cells by treatment with IL-2. Given an inhibitory role of CTLA-4 and CD4+ CD25+ T cells in immune responses, the present findings suggest that IL-2-induced immunosuppression may result from its stimulatory effect of the CTLA-4 expression.

Abatacept↗

PubMed1997

Characteristics of a cell line established from a case of acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia is uncommon and comprises about 5% of acute nonlymphoid leukemias in the French-American-British classification. Cell lines from such leukemias are relatively rare with only about 8 reported in the literature. We established a cell line from a case of acute megakaryoblastic leukemia arising in a 2-year-old child. Surface marker studies of the cells confirmed their megakaryoblastic nature, with 54% of the cells being CD61 positive and peroxidase and esterase negative. The cells had a doubling time of 72 h. Emperipolesis (a phenomenon in which a cell, usually a lymphocyte or neutrophil, enters another cell, moves about and leaves without undergoing phagocytosis) of one blast into another, larger one, was occasionally seen, and a review of the original bone marrow specimen also showed emperipolesis of neutrophils into the megakaryoblasts. The cells responded to interleukin 3 and were inhibited with all-trans-retinoic acid. The karyotype of the cells was the 46,XX,-16 with a marker chromosome. The marker chromosome is possibly chromosome 16 with a small segment of a chromosome translocated to the terminal portion of chromosome 16.

Antigens, CD↗

PubMed1996

Establishment of cell lines derived from chronic lymphocytic leukaemic cells by transfection with myc and ras.

Seventy-one samples from 37 cases of chronic lymphocytic leukaemia (CLL) were transfected with human c-myc and/or N-ras. In only three cases did the CLL cells further transform and four cell lines were established following transfection with myc plus ras. Surface marker profiles and immunoglobulin gene rearrangement studies confirm that all cell lines have arisen from the original CLL cells. The cell lines are EBNA positive but negative for EBV latent membrane protein (LMP). Karyotyping of the cell lines is as follows: SA4, 46,XY; SA4-2, 45,XY, 20; RK4, 48,XY,+ 5,+ 12; EHC4, 47,XY, t(14;18)(q32;q21), + 12. Although the majority of CLL cells appear resistant to transformation in vitro with myc and ras with the methods used, it does occur in a small percentage (about 8%). There appeared to be no correlation between the ability to transform in vitro and clinical behaviour.

Base Sequence↗

PubMed1994

Characteristics of a cell line established from a T cell acute leukemia by transfection with the bcl-2 gene.

The bcl-2 gene product inhibits apoptosis and thus its over-expression may promote development of the malignant phenotype under certain circumstances. We have introduced the bcl-2 alpha and bcl-2 beta genetic elements into T cell acute lymphoblastic leukemic blasts. These transfectants were able to survive and grow in liquid culture with the establishment of cell lines while the untransfected blast cells died off. Thus transfection of the bcl-2 genes appears to give additional survival advantages to already malignant cells. Although the original leukemic blasts did not have cytoplasmic granules, the established transfectants have a morphology and surface marker profile compatible with large granular lymphoid cells.

Apoptosis↗

PubMed1992

Transfection of chronic lymphocytic leukemic cells with myc and ras.

Thirty samples of cells from twenty-one cases of chronic lymphocytic leukemia (CLL) were transfected with myc and/or ras. Transformation, as assessed by growth in liquid culture and change in morphology, occurred in only one case. Colony culture in semi-solid media, however, does not occur with these cells. It would appear that the neoplastic genotype of CLL cells does not predispose the cells to readily transform, even with transfection with these two oncogenes.

Cell Transformation, Neoplastic↗

PubMed1986

Study on the association of HLA with malignant lymphoma.

The association of HLA with malignant lymphomas in 50 Chinese patients of the HAN nationality was investigated. The frequencies of antigens HLA-A and -C and the majority of HLA-B phenotypes were not significantly different between the patient and control groups, whereas the antigen frequency of HLA-B16 was increased significantly (P less than 0.025) in the patient group. The relative risk associated with HLA-B16 was 2.5694. The association of this antigen with malignant lymphoma might be unique for Oriental patients.

Antigens, Neoplasm↗