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J L Chen

Publications and source records attributed to J L Chen.

At least 55 records · Page 3Linked to original sources
PubMed2000

Identification of NY-ESO-1 peptide analogues capable of improved stimulation of tumor-reactive CTL.

Expression of NY-ESO-1 in a high proportion of different human tumors makes this protein a very attractive vaccine target. NY-ESO-1 peptides, recognized by HLA-A2-restricted CTL, have recently been described. However, it remains unclear how efficiently tumors generate these epitopes, and whether peptide analogues can be used for optimal expansion and activation of NY-ESO-1-specific HLA-A2-restricted CTL. By generating unique CTL clones, we demonstrate that NY-ESO-1-positive tumor cells are efficiently killed by HLA-A2-restricted CTL specific for the peptide epitope NY-ESO-1 157-165. Presentation of this epitope is not affected by the presence or absence of the proteasome subunits low molecular proteins 2 and 7 and is not blocked by proteasome inhibitors, while it is impaired in the TAP-deficient cell line LBL 721.174. NY-ESO-1 157-165 peptide analogues were compared for their antigenicity and immunogenicity using PBL from melanoma patients. Three peptides, containing the carboxyl-terminal cysteine substituted for either valine, isoleucine, or leucine, were recognized at least 100 times more efficiently than the wild-type peptide by specific CTL. Peptide analogues were capable of stimulating the expansion of NY-ESO-1-specific CTL from PBL of melanoma patients much more efficiently than wild-type peptide. These findings define the processing requirements for the generation of the NY-ESO-1 157-165 epitope. Identification of highly antigenic NY-ESO-1 peptide analogues may be important for the development of vaccines capable of expanding NY-ESO-1-specific CTL in cancer patients.

Amino Acid Substitution↗
PubMed2000

Phase I study in melanoma patients of a vaccine with peptide-pulsed dendritic cells generated in vitro from CD34(+) hematopoietic progenitor cells.

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that can be used for vaccination purposes, to induce a specific T-cell response in vivo against melanoma-associated antigens. We have shown that the sequential use of early-acting hematopoietic growth factors, stem cell factor, IL-3 and IL-6, followed by differentiation with IL-4 and granulocyte-macrophage colony-stimulating factor allows the in vitro generation of large numbers of immature DCs from CD34(+) peripheral blood progenitor cells. Maturation to interdigitating DCs could specifically be induced within 24 hr by addition of TNF-alpha. Here, we report on a phase I clinical vaccination trial in melanoma patients using peptide-pulsed DCs. Fourteen HLA-A1(+) or HLA-A2(+) patients received at least 4 i.v. infusions of 5 x 10(6) to 5 x 10(7) DCs pulsed with a pool of peptides including either MAGE-1, MAGE-3 (HLA-A1) or Melan-A, gp100, tyrosinase (HLA-A2), depending on the HLA haplotype. A total of 83 vaccinations were performed. Clinical side effects were mild and consisted of low-grade fever (WHO grade I-II). Clinical and immunological responses consisted of anti-tumor responses in 2 patients, increased melanoma peptide-specific delayed-type hypersensitivity reactions in 4 patients, significant expansion of Melan-A- and gp100-specific cytotoxic T lymphocytes in the peripheral blood lymphocytes of 1 patient after vaccination and development of vitiligo in another HLA-A2(+) patient. Our data indicate that the vaccination of peptide-pulsed DCs is capable of inducing clinical and systemic tumor-specific immune responses without provoking major side effects.

Adolescent↗
PubMed2000

Formation of charge-transfer complexes from neutral bis(porphyrin) sandwiches.

Lanthanide(III) bis(porphyrin) sandwich complexes of octaethyltetraazaporphyrin (OETAP) were synthesized and characterized by UV-vis, IR, and NMR spectroscopies. Cyclic voltammetry results indicate that these neutral sandwich complexes are very easily reduced. Charge-transfer reactions were performed in solution with Ln-(OETAP)2 sandwiches and zirconium(IV) bis(porphyrin) sandwiches. The lanthanide sandwiches partially oxidize the zirconium sandwiches in solution, and a solvent dependence of the charge-transfer reaction was observed. The solid-state properties of these charge-transfer materials were also studied. Magnetic susceptibility results suggest weak intermolecular interactions between the sandwiches. The conductivities of the charge-transfer species are greatly improved relative to those of the insulating undoped sandwiches, but the conductivities are in the lower semiconducting region. The low conductivity values are thought to be due to poor intermolecular overlap.

Journal Article↗
PubMed2000

Secondary structure of vertebrate telomerase RNA.

Telomerase is a ribonucleoprotein enzyme that maintains telomere length by adding telomeric sequence repeats onto chromosome ends. The essential RNA component of telomerase provides the template for telomeric repeat synthesis. To determine the secondary structure of vertebrate telomerase RNA, 32 new telomerase RNA genes were cloned and sequenced from a variety of vertebrate species including 18 mammals, 2 birds, 1 reptile, 7 amphibians, and 4 fishes. Using phylogenetic comparative analysis, we propose a secondary structure that contains four structural domains conserved in all vertebrates. Ten helical regions of the RNA are universally conserved while other regions vary significantly in length and sequence between different classes of vertebrates. The proposed vertebrate telomerase RNA structure displays a strikingly similar topology to the previously determined ciliate telomerase RNA structure, implying an evolutionary conservation of the global architecture of telomerase RNA.

Animals↗
PubMed2000

Anaerobic stability of aqueous physostigmine solution.

The anaerobic stability of physostigmine was studied in this report. Physostigmine and two important degradants, eseroline and rubreserine, were identified by a high-performance liquid chromatography (HPLC) system using a photodiode array detector and a UV detector at the retention times of 12.4, 9.2, and 7.9 min. Under anaerobic treatment, the minimum degradation rate constant was found at pH 3.4, evaluating from pH-rate profiles at 45 degrees C, 55 degrees C, and 70 degrees C with the pH range 2.4-6.8. The degradation of physostigmine was suggested as specific acid-base catalysis. Anaerobic activation energies of KH, K(OH), and Kobs were 9.4, 8.3, and 17.9 kcal/mol, respectively. The ratios of observed aerobic and anaerobic rate constants were 2-33 at 88 degrees C, which had a trend to increase ratios as pH increased in the range 2.4-5.2. The shelf life of physostigmine solution was estimated to be 4 years at room temperature under anaerobic conditions at pH 3.4.

Anaerobiosis↗
PubMed2000

When is hilar uptake of 67Ga-citrate indicative of residual disease after CHOP chemotherapy?

UNLABELLED: The purpose of this study was to evaluate the prevalence and characterize the patterns of hilar uptake (HU) on 67Ga-citrate imaging after cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy regimens for non-Hodgkin's lymphoma (NHL), to differentiate hilar lymphoma (HL) from HU of benign etiology. METHODS: A total of 930 studies (698 planar, 232 thoracic SPECT) was reviewed retrospectively in 100 NHL patients (29 low-grade, 60 intermediate-grade, and 11 high-grade) treated with CHOP and followed up longitudinally with serial gallium studies (planar: median, 7; range, 3-16 studies in 100 patients; SPECT: median, 1; range, 0-11 studies in 72 patients) over a median duration of 36 mo (range, 6-112 mo) from diagnosis. Clinical outcome and size changes over time on correlative CT and/or radiographs were used to evaluate benign versus malignant changes within the hila. RESULTS: HU after CHOP was present in 79% of patients (90% confidence interval [CI], 71%-85%), with 33% showing HU on SPECT alone. Once present, HU persisted for a median of 27 mo (range, 2-84 mo) from onset. The prevalence of HU and HL at various time points was as follows: baseline HU, 52% with HL 60%; mid-CHOP HU, 59% with HL2%; post-CHOP HU, 52% with HL6%; follow-up HU, 76% with HL 9%. HU of benign etiology was not significantly correlated with CHOP dosage. HU was symmetric in 90% of patients (90% CI, 82%-95%) and less intense than the original disease in 89% of patients (90% CI, 80%-95%), and these features were highly predictive of benign etiology (negative predictive value [NPV], 98.6% if symmetric; NPV, 96.5% if less than original disease; NPV, 100% if both present). Asymmetric HU equal in intensity to the original disease, however, was highly predictive of HL (positive predictive value [PPV], 87.5% if asymmetric; PPV, 85.7% if equal to original disease; PPV, 100% if both present). CONCLUSION: HU after CHOP is common (overall incidence, 79%), often seen only on SPECT, and most likely of benign etiology when symmetric and less intense than the original disease. Asymmetric HU that equals the intensity of the original disease, however, is a possible indicator for HL.

Adult↗
PubMed2000

Generation and purification of CD8+ melan-A-specific cytotoxic T lymphocytes for adoptive transfer in tumor immunotherapy.

Tumor antigens that might serve as potential targets for adoptive T-cell therapy have been defined in different tumor entities, especially in malignant melanoma. To generate conditions to induce primary T-cell responses against different HLA-A*0201-restricted melanoma peptides and to allow further expansion of peptide-specific T cells for adoptive transfer, CD8+-purified T cells from healthy donors were stimulated with Melan-A-pulsed autologous dendritic cells. Dendritic cells were generated in vitro from monocytes with granulocyte macrophage colony-stimulating factor, interleukin-4, and transforming growth factor-beta1. After 3-4 weekly stimulation cycles with Melan-A-pulsed DCs, we were able to induce a strong peptide-specific CTL response in vitro. MHC-peptide tetramer staining revealed a frequency of up to 3.5% CD8+/Melan-A+ T cells. Additional antigen-independent expansion with anti-CD3/anti-CD28 monoclonal antibodies together with interleukin-2 gave rise to 600-fold expansion of CD8+ CTLs that maintained Melan-A specificity and were able to efficiently lyse Melan-A-expressing melanoma cells. To enrich antigen-specific T cells in vitro, we used a recently established technology for analysis and sorting of live cells according to secreted cytokines. In the present study, we demonstrated that Melan-A-specific T cells can be purified by magnetic separation according to secreted IFN-gamma. These cells revealed a very potent monospecific CTL response, even at low E:T ratios, against Melan-A-pulsed and Melan-A-expressing target cells. Altogether, our study demonstrated that we have developed an efficient method for generating large numbers of peptide-specific T cells in vitro that may be used for adoptive T-cell transfer in tumor immunotherapy.

Adoptive Transfer↗
PubMed2000

[A study on the chemical components of essential oil of oak moss concrete by gas chromatography/mass spectrometry].

The essential oil of oak moss concrete was extracted by volatile oil content equipment. The chemical compositions and their relative contents were analyzed by GC and GC/MS. A Supelco-5 fused silica capillary column (30 m x 0.32 mm i.d.; 0.25 micron thickness) and a flame ionization detector (FID) were employed in GC analysis. The temperature program included temperature increase of 4 degrees C/min from 50 degrees C to 250 degrees C, and a 10 min isothermal period at 250 degrees C. Mass spectra were obtained by electron impact at 70 eV and a source temperature of 170 degrees C. Twenty-four volatile compounds of oak mass concrete were identified, which comprised more than 83% of volatile fraction. The major components were diethyl phthalate, alpha-terpineol, cedrane and linalool.

Acyclic Monoterpenes↗
PubMed1999

Synthesis and analytical properties of a novel columnar metallomesogenic polymer.

A metallomesogenic side-chain polymer with copper carboxylato discotic units in stacks prepared by covalent bonding of 14-pentadecenoic acid, stearic acid and poly(methylhydrosiloxane) is described. The physico-chemical and thermal properties of both monomeric and polymeric metallomesogens were determined by elemental analysis, IR, polarizing optical microscopy, thermal gravimetric analysis and differential scanning calorimetry. The polymeric states showed a discotic lamellar phase at 50-95 degrees C and an ordered discotic hexagonal phase at 95-200 degrees C. By dynamic coating, the metallomesogenic polymer was crosslinked to the capillary wall via benzoyl peroxide. The wall-coated capillary columns (15 m x 0.25 mm I.D.) were used for the separation of phenols. Factors affecting the retention and the sample selectivity were examined. Van 't Hoff plots as a function of temperature indicated that phase transitions were occurring. Thermodynamic properties of the analytes in this system were also studied. For the determination of a mixture of 3-aminophenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, o-methylphenol, m-methylphenol, p-methylphenol, 2,4-dichlorophenol, 2,4-dimethylphenol, 2,4-dinitrophenol, 2,4,6-trichlorophenol, 2,4,6-trimethylphenol, 4-bromophenol, 3-methyl-4-chlorophenol, pentachlorophenol, and unsubstituted phenol, the calibration graphs for most phenols were linear over the range of 10-1000 microg ml(-1) and the mass detection limits were in the ng range based on three times standard deviation of seven measurements of the lowest peak that could be detected.

Calorimetry, Differential Scanning↗
PubMed1999

Role of synaptic vesicle proton gradient and protein phosphorylation on ATP-mediated activation of membrane-associated brain glutamate decarboxylase.

Previously, we have shown that the soluble form of brain glutamic acid decarboxylase (GAD) is inhibited by ATP through protein phosphorylation and is activated by calcineurin-mediated protein dephosphorylation (Bao, J., Cheung, W. Y., and Wu, J. Y. (1995) J. Biol. Chem. 270, 6464-6467). Here we report that the membrane-associated form of GAD (MGAD) is greatly activated by ATP, whereas adenosine 5'-[beta,gamma-imido]triphosphate (AMP-PNP), a non-hydrolyzable ATP analog, has no effect on MGAD activity. ATP activation of MGAD is abolished by conditions that disrupt the proton gradient of synaptic vesicles, e.g. the presence of vesicular proton pump inhibitor, bafilomycin A1, the protonophore carbonyl cyanide m-chorophenylhydrazone or the ionophore gramicidin, indicating that the synaptic vesicle proton gradient is essential in ATP activation of MGAD. Furthermore, direct incorporation of (32)P from [gamma-(32)P]ATP into MGAD has been demonstrated. In addition, MGAD (presumably GAD65, since it is recognized by specific monoclonal antibody, GAD6, as well as specific anti-GAD65) has been reported to be associated with synaptic vesicles. Based on these results, a model linking gamma-aminobutyric acid (GABA) synthesis by MGAD to GABA packaging into synaptic vesicles by proton gradient-mediated GABA transport is presented. Activation of MGAD by phosphorylation appears to be mediated by a vesicular protein kinase that is controlled by the vesicular proton gradient.

Adenosine Triphosphate↗
PubMed1999

Cutting edge: rapid cloning of tumor-specific CTL suitable for adoptive immunotherapy of melanoma.

Adoptive immunotherapy using CTL has provided some clinical benefit to patients with metastatic melanoma. Use of cloned CTL of known specificity might improve clinical effect, but technical difficulties have limited exploration of this possibility. We have used fluorescence-driven cell sorting to clone tumor-specific CTL after staining with tetrameric MHC class I/peptide complexes. CTL specific for the melanoma Ags melan-A, tyrosinase, and MAGE3 were cloned from the peripheral blood, tumor-infiltrated lymph nodes, and skin metastases of five patients. Clones were isolated and characterized in as little as 6 weeks, much faster than is possible with previous techniques. We show that these CTL clones express markers compatible with immunotherapeutic use in melanoma, including the cutaneous lymphocyte Ag, which is associated with homing to skin.

Adult↗
PubMed1999

Randomized clinical trial of urokinase versus heparin in unstable angina.

The aim of this study was to evaluate the clinical effect of urokinase (UK) in unstable angina (UA). This study was a multicenter, single-blind, heparin-controlled, randomized clinical trial. Entry criteria was that effort angina was significantly aggravated within 96 hours and angina attack at rest within 24 hours. In addition to the control group, thrombolytic therapy was divided into two groups according to the dose of UK. The high-dose group was 18,000 IU/kg, and the total dose was no more than 1.5 million IU (no bolus of heparin in this dose). The low-dose group was 14,000 IU/kg, and the total dose was no more than 1 million IU. All patients were treated by aspirin 300 mg/day and heparin 3000 U IV bolus before thrombolytic therapy (except for the high-dose group), then subcutaneous heparin 7,500 U q12h. The primary endpoint for the comparison between the thrombolytic and control groups was death and AMI (cardiac event) within 30 days of enrollment. Five hundred and fifty-six patients with UA were selected, and 272 and 284 patients were enrolled in thrombolytic group and control groups, respectively. The 30-day incidence of cardiac events was a little higher, but not significantly, in the thrombolytic group than in the control group (7.0% vs. 5.3%, ns), but the rate for cardiac events was much lower in the low-dose UK group than in the high-dose UK group. The difference was significant (3.3% vs. 10.0%, P < 0.05). Even if the rate was also lower than in the control group, this difference was not significant (3.3% vs. 5.3%, P > 0.05). The time interval between enrollment and the AMIs was quite different in these two groups. The majority of AMIs (73.7%) occurred within 24 hours, including 37% of AMIs that occurred within 2 hours after the beginning of thrombolytic therapy in the UK group. However, only small number of AMIs (20%) occurred within 24 hours of enrollment in the control group. The increase in AMI risk on the first day of thrombolytic therapy in this study might be closely related to thrombolysis and to the lack of strong antithrombin therapy. The risk of AMI might be remarkably reduced by using low-dose UK in combination with antithrombin therapy before thrombolytic therapy.

Adult↗
PubMed1999

Possible experimental measure theory for the XXX-Heisenberg chain.

Raising and lowering operators for the XXX-Heisenberg chain are derived explicitly; as a result the dipole moment operator is established. Based on the dipole transition mechanism in an external time-dependent magnetic field, we propose a possible experimental measure theory to detect the energy spectrum of the spin chain.

Journal Article↗
PubMed1999

Adenovirus-mediated overexpression of uncoupling protein-2 in pancreatic islets of Zucker diabetic rats increases oxidative activity and improves beta-cell function.

The discovery of uncoupling protein (UCP)-2, a ubiquitously expressed protein homologous to UCP-1, has raised the possibility that energy balance of cells might be regulated in tissues other than brown adipocytes. In normal pancreatic islets, UCP-2 is upregulated by leptin and is low in leptin-resistant islets of ZDF rats. To determine whether UCP-2 does, in fact, have uncoupling activity and, if so, whether such activity would favorably influence the abnormalities in leptin-unresponsive UCP-2-underexpressing islets of diabetic ZDF rats, we transferred the UCP-2 gene to the islets of diabetic ZDF rats and lean (+/+) ZDF control rats. Although ATP was reduced by 23% in both groups of islets, the ATP:ADP ratio increased by 42 and 141%, respectively. [3H]palmitate oxidation was increased by 50%, and [3H]glucose oxidation was 42-63% higher. Preproinsulin mRNA was 2.9-fold above control levels, and glucose-stimulated insulin secretion, which was negligible in control ZDF rat islets, was improved in UCP-2-overexpressing islets. The high fat content of the islets was not reduced, however. We conclude that UCP-2 has uncoupling function when overexpressed in leptin-insensitive islets and that its overexpression corrects the underexpression of the insulin gene and ameliorates glucose-stimulated insulin secretion, possibly by increasing the ATP:ADP ratio.

Adenosine Diphosphate↗
PubMed1998

Ex vivo staining of metastatic lymph nodes by class I major histocompatibility complex tetramers reveals high numbers of antigen-experienced tumor-specific cytolytic T lymphocytes.

Characterization of cytolytic T lymphocyte (CTL) responses to tumor antigens has been impeded by a lack of direct assays of CTL activity. We have synthesized reagents ("tetramers") that specifically stain CTLs recognizing melanoma antigens. Tetramer staining of tumor-infiltrated lymph nodes ex vivo revealed high frequencies of tumor-specific CTLs which were antigen-experienced by surface phenotype. In vitro culture of lymph node cells with cytokines resulted in very large expansions of tumor-specific CTLs that were dependent on the presence of tumor cells in the lymph nodes. Tetramer-guided sorting by flow cytometer allowed isolation of melanoma-specific CTLs and confirmation of their specificity and their ability to lyse autologous tumor cells. Our results demonstrate the value of these novel reagents for monitoring tumor-specific CTL responses and for generating CTLs for adoptive immunotherapy. These data also indicate that strong CTL responses to melanoma often occur in vivo, and that the reactive CTLs have substantial proliferative and tumoricidal potential.

Adult↗