Publications by authors named "Ch'en I"

Chimeric antigen receptor (CAR)-T cell therapies reprogram T cells to engage and eliminate cancer cells. Patients' T cells are transduced using lentiviral or retroviral vectors containing a CAR transgene. Following infusion, CAR-T cells expand and may persist in the peripheral blood and bone marrow for years.

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Exceptional clinical responses produced by the first chimeric antigen receptor T [CAR-T] cell therapies, and their entry into commercial markets prompted a logarithmic increase in the number of next generation CAR-T clinical trials. As a result, there is a growing interest in understanding the analytical approaches utilized for reliable monitoring of these "living" drugs, and the challenges encountered during their clinical development. Multiparametric flow cytometry (MFC) assays have played a crucial role in understanding the phenotype and function of first approved CAR-T therapies.

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Effective immune responses depend upon appropriate T cell differentiation in accord with the nature of an infectious agent, and the contingency of differentiation depends minimally on TCR, coreceptor, and cytokine signals. In this reverse genetic study, we show that the MAPK Erk2 is not essential for T cell proliferation in the presence of optimum costimulation. Instead, it has opposite effects on T-bet and Gata3 expression and, hence, on Th1 and Th2 differentiation.

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Cell populations are regulated in size by at least two forms of apoptosis. More recently, necroptosis, a parallel, nonapoptotic pathway of cell death, has been described, and this pathway is invoked in the absence of caspase 8. In caspase 8-deficient T cells, necroptosis occurs as the result of antigen receptor-mediated activation.

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Foxo transcription factors integrate extrinsic signals to regulate cell division, differentiation and survival, and specific functions of lymphoid and myeloid cells. Here, we showed the absence of Foxo1 severely curtailed the development of Foxp3(+) regulatory T (Treg) cells and those that developed were nonfunctional in vivo. The loss of function included diminished CTLA-4 receptor expression as the Ctla4 gene was a direct target of Foxo1.

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Programmed cell death (PCD) occurs widely in species from every kingdom of life. It has been shown to be an integral aspect of development in multicellular organisms, and it is an essential component of the immune response to infectious agents. An analysis of the phylogenetic origin of PCD now shows that it evolved independently several times, and it is fundamental to basic cellular physiology.

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Signals initiated through the TCR during development can result in either survival and differentiation or cell death. High affinity signals that induce death elicit a robust yet transient activation of signaling pathways, including Erk, whereas low affinity ligands, which promote survival, generate a gradual and weaker activation of the same pathways. It was recently demonstrated that Erk localizes to distinct cellular locations in response to high and low affinity ligands.

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Foxo transcription factors regulate cell cycle progression, cell survival and DNA-repair pathways. Here we demonstrate that deficiency in Foxo3 resulted in greater expansion of T cell populations after viral infection. This exaggerated expansion was not T cell intrinsic.

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Tissue homeostasis and regeneration are regulated by an intricate balance of seemingly competing processes-proliferation versus differentiation, and cell death versus survival. Here we demonstrate that the loss of epidermal caspase 8, an important mediator of apoptosis, recapitulates several phases of a wound healing response in the mouse. The epidermal hyperplasia in the caspase 8 null skin is the culmination of signals exchanged between epidermal keratinocytes, dermal fibroblasts and leukocytic cells.

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T cells enigmatically require caspase-8, an inducer of apoptosis, for antigen-driven expansion and effective antiviral responses, and yet the pathways responsible for this effect have been elusive. A defect in caspase-8 expression does not affect progression through the cell cycle but causes an abnormally high rate of cell death that is distinct from apoptosis and does not involve a loss of NFkappaB activation. Instead, antigen or mitogen activated Casp8-deficient T cells exhibit an alternative type of cell death similar to programmed necrosis that depends on receptor interacting protein (Ripk1).

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The NF-kappaB signaling system has important and distinct roles in determining cell fate decisions, such as cell proliferation and cell death. Specifically, recent evidence indicates that NF-B regulates several types of programmed cell death, such as apoptosis, necroptosis, necrosis, as well as cellular senescence, but its precise role in these is not fully understood. Distinguishing these cell fates experimentally is therefore important, and several techniques are available to researchers.

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Necroptosis is a cellular mechanism of necrotic cell death induced by apoptotic stimuli in the form of death domain receptor engagement by their respective ligands under conditions where apoptotic execution is prevented. Although it occurs under regulated conditions, necroptotic cell death is characterized by the same morphological features as unregulated necrotic death. Here we report that necrostatin-1, a previously identified small-molecule inhibitor of necroptosis, is a selective allosteric inhibitor of the death domain receptor-associated adaptor kinase RIP1 in vitro.

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Caspase-8 is an essential component of death receptor-mediated apoptosis. Along with Fas-associated death domain protein, it is also essential for T cell proliferation in response to antigenic or mitogenic stimuli. To determine whether caspase-8 is also required for B cell proliferation, we generated mice with a B cell-specific Casp8 deficiency.

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Stimulation of the TCR leads to an oscillatory release of free calcium that activates members of the calcium/calmodulin-dependent protein kinase II (CaMKII) family. The CaMKII molecules have profound and lasting effects on cellular signaling in several cell types, yet the role of CaMKII in T cells is still poorly characterized. In this report we describe a splice variant of CaMKIIbeta, CaMKIIbeta'e, in mouse T cells.

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LIM domain factors and associated cofactors are important developmental regulators in pattern formation and organogenesis. In addition, overexpression of two LIM-only factors (LMOs) causes acute lymphocytic leukemia. The more recently discovered LMO factor LMO4 is highly expressed in proliferating epithelial cells, and frequently overexpressed in breast carcinoma.

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The purpose of this study was to examine hepatic lesions with a sequence designed to yield improved T2 measurements and evaluate the clinical utility of these measurements in distinguishing malignant from benign disease. Using a modified Carr-Purcell sequence incorporating features designed to compensate for imperfections in the imaging system, including a train of refocusing pulses emitted in an MLEV pattern oriented in composite fashion along all three coordinate axes, and a single spatially selective pulse placed immediately before a spiral readout, 14 benign lesions and 13 malignant lesions were evaluated prospectively with a conventional 1.5 T imager.

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Purpose: Virtual colonoscopy is a new method of colon examination in which computer-aided 3D visualization of spiral CT simulates fiberoptic colonoscopy. We used a colon phantom containing various-sized spheres to determine the influence of CT acquisition parameters on lesion detectability and sizing.

Method: Spherical plastic beads with diameters of 2.

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Objective: Our objective was to evaluate the accuracy of MR imaging strategy that uses primarily fast spin-echo sequences for the diagnosis of anterior cruciate ligament tears.

Materials And Methods: The original clinical interpretations of MR images of 217 examinations of the knee joint were correlated with subsequent arthroscopic results. Each MR examination included a double-echo fast spin-echo sequence as the only imaging sequence in the sagittal plane.

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Purpose: We assessed the utility of power Doppler imaging (PDI) in preoperative planning and postoperative evaluation of microvascular tissue transfers.

Methods: Twenty-five PDI studies were performed on 23 patients using a 5-10-MHz linear-array transducer. Thirteen patients were assessed preoperatively for patency of the desired donor vessel; 8 of them had surgical scars overlying the desired vascular territory.

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Purpose: To determine if dogs and humans with chronic mesenteric ischemia demonstrate a decrease in the percentage of oxygenated hemoglobin (%HbO2) in the superior mesenteric vein (SMV) after a meal.

Materials And Methods: In 10 dogs, ameroid rings were surgically implanted around the superior mesenteric arteries to create gradual stenosis. Pre- and postoperative angiograms and pre- and postprandial magnetic resonance (MR) oximetry measurements of the SMV %HbO2, with flow-independent T2 measurements of venous blood, were obtained at different times.

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Our goal was to determine if arterial phase images from dual phase helical CT improve either the detection or the characterization of hepatic metastases in patients with colorectal carcinoma. Sixty-two patients with known colorectal cancer underwent 65 dual phase helical CT examinations to evaluate for possible liver metastases. Three blinded reviewers independently evaluated the portal venous phase images alone to determine if hepatic metastases were present or absent.

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Objective: The purpose of this study was to determine whether recently described criteria, including hyperintense T2-weighted signal or other abnormalities revealed by MR imaging within deep fascial planes, are specific for necrotizing soft-tissue infections.

Materials And Methods: We reviewed 22 MR imaging examinations that revealed abnormally high signal intensity within deep fascial planes on T2-weighted images. Twenty-one of the patients had clinical diagnoses other than necrotizing soft-tissue infection, including nonnecrotizing cellulitis (n = 4), abscess without evidence of necrotizing fasciitis (n = 5), and cellulitis with accompanying vascular thrombosis (n = 2).

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Rationale And Objectives: The authors tested the hypothesis that changes in oxygen saturation (%HbO2) in the superior mesenteric vein (SMV), as measured with in vivo magnetic resonance (MR) oximetry, correlate with the degree of acute superior mesenteric artery (SMA) flow reduction.

Methods: Ten mongrel dogs were studied. A catheter was inserted into the SMV, and a perivascular ultrasonic flow probe and an adjustable mechanical occluder were placed around the SMA.

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We report two cases of scrotal cystocele. In patients suspected of having a scrotal cystocele, we believe that ultrasonography is the initial examination of choice. Emptying of a scrotal cystocele with voiding is an important diagnostic feature.

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