Biomedical subjects

Wen-Chung Chang

Publications and source records attributed to Wen-Chung Chang.

6 recordsLinked to original sources

PubMed2006

Fabrication of polymer waveguides by a replication method.

We have developed a soft-lithography method to replicate polymer waveguides. In this method, the waveguides are produced by a two-step molding process where a master mold is first formed on a negative-tone photoresist and subsequently transferred to a polydimethylsiloxane (PDMS) mold; a PDMS silicone rubber mold is then used as a stamp to transfer the final waveguide pattern onto an UV cure epoxy. Initial results show good pattern transferring in physical shape. The optical performance is measured based on the propagation loss. In our design, the loss was measured at 0.28 dB/cm for 1.3 microm and 0.26 dB/cm for 1.55 microm.

Journal Article↗

PubMed2006

Discovering meaningful information from large amounts of environment and health data to reduce uncertainties in formulating environmental policies.

This study uses knowledge discovery concepts to analyze large amounts of data step by step for the purpose of assisting in the formulation of environmental policy. We performed data cleansing and extracting from existing nation-wide databases, and used regression and classification techniques to analyze the data. The current water hardness in Kaohsiung, Taiwan contributes to the prevention of cardiovascular disease (CVD) but exacerbates the development of renal stones (RS). However, to focus on water hardness alone to control RS would not be cost effective at all, because the existing database parameters do not adequately allow for a clear understanding of RS. Analysis of huge amounts of data can most often turn up the most reliable and convincing results and the use of existing databases can be cost-effective.

Data Interpretation, Statistical↗

PubMed2005

Biophotonic cytotoxicity assay for high-throughput screening of cytolytic killing.

We have developed a highly sensitive biophotonic luciferase assay as an alternative to (51)Cr-release for assessment of cell-mediated cytotoxicity. The luciferin/ATP-dependent luminescent signal of target cells stably or transiently transfected with a firefly luciferase reporter gene (fLuc:Zeo) linearly correlates with viable target cell number. Upon incubation of fLuc:Zeo(+) target cells with CD8(+) CTLs, a rapid decrease in bioluminescence was detected that correlated with antigen-specific target cell lysis. The levels of specific lysis measured by (51)Cr-release assays correlated with the attenuation in biophotonic target cell signal, thus validating this approach as a sensitive and accurate method for the measurement of cytolysis. We show that this luminescent-based cytolytic assay (LCA) is amenable for high-throughput screening of effector cell cytolytic activity, allows for the rate of cytolysis to be measured in a single micro-plate, and permits the multiplexing of cytolytic killing with other lymphocyte functional assays such as cytokine release. Importantly, this method accurately measures the cytolytic killing of target cells that are either stably or transiently transfected with a fLuc reporter gene, and thus is ideal for monitoring cytolysis of both primary autologous and immortalized target cell lines. The versatility of the non-radioactive, high-throughput, biophotonic cytolytic assay should make this method an attractive alternative to chromium-release for quantifying effector cell cytolytic activity.

CD8-Positive T-Lymphocytes↗

PubMed2004

Enhanced antilymphoma efficacy of CD19-redirected influenza MP1-specific CTLs by cotransfer of T cells modified to present influenza MP1.

To enhance the in vivo antitumor activity of adoptively transferred, CD19-specific chimeric antigen receptor (CAR)-redirected cytotoxic T lymphocytes (CTLs), we studied the effect of restimulating CAR(+) CTLs through their endogenous virus-specific T-cell antigen receptor (TcR) by the cotransfer of engineered T-cell antigen-presenting cells (T-APCs). Using influenza A matrix protein 1 (MP1) as a model antigen, we show that ex vivo-expanded CD4(+) and CD8(+) T-APCs expressing a hygromycin phosphotransferase-MP1 fusion protein (HyMP1) process and present MP1 to autologous human leukocyte antigen (HLA)-restricted, MP1-specific CD4(+) and CD8(+) CTL precursors. The MP1-specific CTLs are amenable to subsequent genetic modification to express a CD19-specific CAR, designated CD19R, and acquire HLA-unrestricted reactivity toward CD19(+) leukemia and lymphoma tumor targets while maintaining HLA-restricted MP1 specificity. The restimulation of MP1xCD19 dual-specific CTLs in vivo by the adoptive transfer of irradiated HyMP1(+) T-APCs resulted in the enhanced antilymphoma potency of bispecific effector cells, as measured by elimination of the biophotonic signal of established firefly luciferase-expressing Burkitt lymphoma xenografts in nonobese diabetic/severe combined immunodeficiency (NOD/scid) animals compared with control groups restimulated by Hy(+)MP1(neg) T-APCs. Engineered T-APCs are a novel and versatile antigen-delivery system for generating antigen-specific T cells in vitro and enhancing the in vivo effector functioning of CAR-redirected antitumor effector cells.

Adoptive Transfer↗

PubMed2004

Genetic engineering of cytolytic T lymphocytes for adoptive T-cell therapy of neuroblastoma.

BACKGROUND: Disease relapse is the leading cause of mortality for children diagnosed with disseminated neuroblastoma. The adoptive transfer of tumor-specific T cells is an attractive approach to target minimal residual disease following conventional therapies. We describe here the genetic engineering of human cytotoxic T lymphocytes (CTL) to express a chimeric immunoreceptor for re-directed HLA-independent recognition of neuroblastoma. METHODS: The CE7R chimeric immunoreceptor was constructed by PCR splice overlap extension and is composed of a single-chain antibody extracellular domain (scFv) derived from the L1-CAM-specific murine CE7 hybridoma fused to human IgG1 hinge-Fc, the transmembrane portion of human CD4, and the cytoplasmic tail of huCD3-zeta chain (scFvFc:zeta). Primary human T cells were genetically modified by naked DNA electrotransfer of plasmid expression vector CE7R-pMG then analyzed by Western blotting, flow cytometry for CE7R expression and cell surface trafficking, 4-h chromium release assay for re-directed neuroblastoma lysis, and ELISA for tumor-specific activation of cytokine production. RESULTS: CE7R is expressed as an intact chimeric protein that trafficks to the cell surface as a type I transmembrane protein. Primary human CE7R-expressing CD8(+) CTL clones specifically recognize human neuroblastoma tumor cells and are activated for tumor cell lysis and T(c)1 cytokine production. CONCLUSIONS: These data demonstrate the utility of CE7R for re-directing the effector function of CTL to neuroblastoma and have provided the rationale to initiate a FDA-authorized (BB-IND#9149) pilot clinical trial to establish the feasibility and safety of adoptive transfer of autologous CE7R(+)CD8(+) CTL clones to children with recurrent/refractory neuroblastoma.

CD3 Complex↗

PubMed2002

T-cell clones can be rendered specific for CD19: toward the selective augmentation of the graft-versus-B-lineage leukemia effect.

Relapse of B-lineage acute lymphoblastic leukemia (B-ALL) after allogeneic hematopoietic stem cell transplantation (HSCT) commonly results from the failure of a graft-versus-leukemia (GVL) effect to eradicate minimal residual disease. Augmenting the GVL effect by the adoptive transfer of donor-derived B-ALL-specific T-cell clones is a conceptually attractive strategy to decrease relapse rates without exacerbating graft-versus-host disease (GVHD). Toward this end, we investigated whether a genetic engineering approach could render CD8(+) cytotoxic T lymphocytes (CTLs) specific for tumor cells that express the B-cell lineage cell surface molecule CD19. This was accomplished by the genetic modification of CTLs to express a chimeric immunoreceptor composed of a CD19-specific single-chain immunoglobulin extracellular targeting domain fused to a CD3-zeta intracellular signaling domain. CD19-redirected CTL clones display potent CD19-specific lytic activity and chimeric immunoreceptor-regulated cytokine production and proliferation. Because B-ALL cells can evade T-cell/natural killer- cell recognition by down-regulation of cell surface accessory molecules that participate in the formation of a functional immunologic synapse, we compared the CD19-specific effector function of genetically modified CD8(+) CTLs toward CD19(+) cells with disparate levels of intercellular adhesion molecule 1 (ICAM-1), leukocyte function-associated antigen 1 (LFA-1), and LFA-3. We observed that recognition of B-lineage tumor lines by CD19-specific CTLs was not impaired by low levels of ICAM-1, LFA-1, and LFA-3 cell surface expression, a functional attribute that is likely a consequence of our high-affinity CD19-specific chimeric immunoreceptor. Furthermore, the CD19-specific CTLs could lyse primary B-ALL blasts. These preclinical observations form the basis for implementing clinical trials using donor-derived CD19-specific T-cell clones to treat or prevent relapse of B-ALL after allogeneic HSCT.

Adoptive Transfer↗