Showing papers by "Jun Lu published in 2002"

Tumor-associated B7-H1 promotes T-cell apoptosis: a potential mechanism of immune evasion

Abstract: B7-H1, a recently described member of the B7 family of costimulatory molecules, is thought to be involved in the regulation of cellular and humoral immune responses through the PD-1 receptor on activated T and B cells. We report here that, except for cells of the macrophage lineage, normal human tissues do not express B7-H1. In contrast, B7-H1 is abundant in human carcinomas of lung, ovary and colon and in melanomas. The pro-inflammatory cytokine interferon-gamma upregulates B7-H1 on the surface of tumor cell lines. Cancer cell-associated B7-H1 increases apoptosis of antigen-specific human T-cell clones in vitro, and the apoptotic effect of B7-H1 is mediated largely by one or more receptors other than PD-1. In addition, expression of B7-H1 on mouse P815 tumor increases apoptosis of activated tumor-reactive T cells and promotes the growth of highly immunogenic B7-1(+) tumors in vivo. These findings have implications for the design of T cell-based cancer immunotherapy.

The sedative component of anesthesia is mediated by GABA(A) receptors in an endogenous sleep pathway.

Abstract: We investigated the role of regionally discrete GABA (gamma-aminobutyric acid) receptors in the sedative response to pharmacological agents that act on GABA(A) receptors (muscimol, propofol and pentobarbital; 'GABAergic agents') and to ketamine, a general anesthetic that does not affect GABA(A) receptors. Behavioral studies in rats showed that the sedative response to centrally administered GABAergic agents was attenuated by the GABA(A) receptor antagonist gabazine (systemically administered). The sedative response to ketamine, by contrast, was unaffected by gabazine. Using c-Fos as a marker of neuronal activation, we identified a possible role for the tuberomammillary nucleus (TMN): when gabazine was microinjected directly into the TMN, it attenuated the sedative response to GABAergic agents. Furthermore, the GABA(A) receptor agonist muscimol produced a dose-dependent sedation when it was administered into the TMN. We conclude that the TMN is a discrete neural locus that has a key role in the sedative response to GABAergic anesthetics.

Afferents to the ventrolateral preoptic nucleus.

Abstract: Sleep is influenced by diverse factors such as circadian time, affective states, ambient temperature, pain, etc., but pathways mediating these influences are unknown. To identify pathways that may influence sleep, we examined afferents to the ventrolateral preoptic nucleus (VLPO), an area critically implicated in promoting sleep. Injections of the retrograde tracer cholera toxin B subunit (CTB) into the VLPO produced modest numbers of CTB-labeled monoaminergic neurons in the tuberomammillary nucleus, raphe nuclei, and ventrolateral medulla, as well as a few neurons in the locus coeruleus. Immunohistochemistry for monoaminergic markers showed dense innervation of the VLPO by histaminergic, noradrenergic, and serotonergic fibers. Along with previous findings, these results suggest that the VLPO and monoaminergic nuclei may be reciprocally connected. Retrograde and anterograde tracing showed moderate or heavy inputs to the VLPO from hypothalamic regions including the median preoptic nucleus, lateral hypothalamic area, and dorsomedial hypothalamic nucleus (DMH), autonomic regions including the infralimbic cortex and parabrachial nucleus, and limbic regions including the lateral septal nucleus and ventral subiculum. Light to moderate inputs arose from orexin and melanin concentrating hormone neurons, but cholinergic or dopaminergic inputs were extremely sparse. Suprachiasmatic nucleus (SCN) projections to the VLPO were sparse, but the heavy input to the VLPO from the DMH, which receives direct and indirect SCN inputs, could provide an alternate pathway regulating the circadian timing of sleep. These robust pathways suggest candidate mechanisms by which sleep may be influenced by brain systems regulating arousal, autonomic, limbic, and circadian functions.

Selective Activation of the Extended Ventrolateral Preoptic Nucleus during Rapid Eye Movement Sleep

Abstract: We found previously that damage to a cluster of sleep-active neurons (Fos-positive during sleep) in the ventrolateral preoptic nucleus (VLPO) decreases non-rapid eye movement (NREM) sleep in rats, whereas injury to the sleep-active cells extending dorsally and medially from the VLPO cluster (the extended VLPO) diminishes REM sleep. These results led us to examine whether neurons in the extended VLPO are activated during REM sleep and the connectivity of these neurons with pontine sites implicated in producing REM sleep: the laterodorsal tegmental nucleus (LDT), dorsal raphe nucleus (DRN), and locus ceruleus (LC). After periods of dark exposure that triggered enrichment of REM sleep, the number of Fos-positive cells in the extended VLPO was highly correlated with REM but not NREM sleep. In contrast, the number of Fos-positive cells in the VLPO cluster was correlated with NREM but not REM sleep. Sixty percent of sleep-active cells in the extended VLPO and 90% of sleep-active cells in the VLPO cluster in dark-treated animals contained galanin mRNA. Retrograde tracing from the LDT, DRN, and LC demonstrated more labeled cells in the extended VLPO than the VLPO cluster, and 50% of these in the extended VLPO were sleep-active. Anterograde tracing showed that projections from the extended VLPO and VLPO cluster targeted the cell bodies and dendrites of DRN serotoninergic neurons and LC noradrenergic neurons but were not apposed to cholinergic neurons in the LDT. The connections and physiological activity of the extended VLPO suggest a specialized role in the regulation of REM sleep.

Roads to polyploidy: the megakaryocyte example.

Abstract: Polyploidy, recognized by multiple copies of the haploid chromosome number, has been described in plants, insects, and in mammalian cells such as, the platelet precursors, the megakaryocytes. Several of these cell types reach high ploidy via a different cell cycle. Megakaryocytes undergo an endomitotic cell cycle, which consists of an S phase interrupted by a gap, during which the cells enter mitosis but skip anaphase B and cytokinesis. Here, we review the mechanisms that lead to this cell cycle and to polyploidy in megakaryocytes, while also comparing them to those described for other systems in which high ploidy is achieved. Overall, polyploidy is associated with an orchestrated change in expression of several genes, of which, some may be a result of high ploidy and hence a determinant of a new cell physiology, while others are inducers of polyploidization. Future studies will aim to further explore these two groups of genes.

Properties of hafnium oxide films grown by atomic layer deposition from hafnium tetraiodide and oxygen

Abstract: Polycrystalline monoclinic HfO2 films were atomic layer deposited on Si(100) substrates by a nonhydrous carbon-free process of HfI4 and O2. The oxygen to hafnium ratio corresponded to the stoichiometric dioxide within the limits of accuracy of ion beam analysis. A 1.5–2.0 nm thick SiO2 interface layer formed between the HfO2 films and Si substrates. Hysteresis of the capacitance–voltage curves was observed in Al/HfO2/p-Si(100) structures with oxide grown in the substrate temperature range of 570–755 °C. The hysteresis ceased with an increase in O2 pressure. The effective permittivity of the dielectric layers varied between 12 and 16. The breakdown voltages were found to be lower in the case of higher oxygen doses and higher HfO2 deposition temperatures.

Strategies for antigen loading of dendritic cells to enhance the antitumor immune response.

Abstract: Dendritic cells (DCs) primed with tumor antigens can effectively mediatethe regression of a variety of established solid malignancies in both murine and human models. Despite such clinical efficacy, the optimal means of DC priming is unknown. The goal of this study was to compare three methods of tumor preparation: irradiation, boiling, or freeze thaw lysis for DC priming. Mouse bone marrow-derived DCs were loaded with defined ratios of E.G7 tumor cells expressing a model tumor antigen, OVA. Sensitized DCs were used for stimulation of OVA-specific CTLs derived from OT-1 T-cell receptor transgenic mice. IFN-γ release, determined by ELISA at 24 and 48 h, was used to assess the expression of antigens by DCs. DCs loaded with irradiated tumors were effective stimulators for OT-1 CTLs, whereas DCs stimulated with freeze-thawed or boiled tumors did not stimulate IFN-γ production. Freeze-thaw lysis appeared to inhibit CTL activity in vitro and in two of three cases, this effect was not overcome by the addition of OVA. The ability to load irradiated tumor cells was reproduced in two analogous human melanoma models using melanoma cell lines expressing gp100 and CTL clones specific for a gp100 melanoma antigen. Consistent with the in vitro data, only DC/irradiated tumor vaccines were effective in preventing or delaying outgrowth of E.G7 and a poorly immunogenic murine squamous cell carcinoma (SCCVII), on local tumor challenge. These data demonstrate that the method of tumor cell preparation clearly influences the ability of DCs to present antigen to T cells. Correlation of in vitro data with the generation of protective immunity in vivo suggests the utility of irradiated tumor-primed DCs as a means to generate protective immunity in patients with solid malignancies.

Recognition of prostate tumor cells by cytotoxic T lymphocytes specific for prostate-specific membrane antigen

Abstract: The development of immunotherapy for cancer, such as synthetic peptide-based vaccines, relies heavily on the identification of appropriate epitopes capable of eliciting antitumor T-cell responses. We have used a combination of computer-based algorithms to predict peptide sequences from prostate-specific membrane antigen (PSMA) capable of stimulating in vitro CTLs restricted by the HLA-A2 MHC molecule. Four of the five peptides that were predicted by these algorithms were capable of inducing antigen-specific CTLs that killed target cells that were pulsed exogenously with the corresponding peptides. However, only one of the four peptides, PSMA(27), induced CTLs that were effective at recognizing prostate tumor cells expressing the HLA-A2 and PSMA molecules. These results underline the importance of demonstrating antitumor reactivity of peptide-induced CTLs for the selection of epitopes destined to become immunotherapeutic for prostate cancer.

Direct Costimulation of Tumor-reactive CTL by Helper T Cells Potentiate Their Proliferation, Survival, and Effector Function

Abstract: The survival and proliferation of CTL during the effector phase of the immune response is critical for the elimination of infectious agents and tumor cells. We report here that in an in vitro model system, the expansion and cytolytic function of tumor-reactive human CTL can be enhanced by CD4(+) helper T lymphocytes through costimulatory signals that are mediated by cell surface molecules. The results presented here suggest that costimulatory receptors on CTL such as CD27, CD134 (4-1BB), and MHC class II are capable of directly interacting with the corresponding ligands on T-helper lymphocytes resulting in enhanced proliferation and survival of the CTL during the effector phase of antitumor immune responses. These findings underline the importance of antigen-specific helper T lymphocytes for the regulation and maintenance of CTL immunity, and have implications for the design of therapeutic vaccines for cancer.

Interleukin 15 promotes antigen-independent in vitro expansion and long-term survival of antitumor cytotoxic T lymphocytes.

Abstract: The survival and expansion of effector cytotoxic T lymphocytes (CTLs) during an immunological response are critical for the successful elimination of life-threatening attacks by microorganisms, parasites, or malignant cells. Among the numerous factors that regulate the immune response, interleukin (IL)-2, and its close relative, IL-15 are known to function as growth and survival factors for antigen-experienced T cells. However, major differences appear to exist between these lymphokines in their capacity to act on various T-cell types such as CD4+ versus CD8+ or effector versus memory T lymphocytes. Although several studies have been done in the mouse system, less information is available regarding the function of these lymphokines in the human system. Here, we report that IL-15 or high concentrations of IL-2 induced antigen-independent expansion of effector CD8+ CTLs. Neither IL-2 nor IL-15 induced the proliferation of CD4+ T cells. In the absence of antigen, at least one of these lymphokines was required for the long-term survival of the cells in tissue culture. Most significantly, the effector cytolytic activity of CTLs expanded and maintained in IL-15 for up to 60 days remained stable, indicating that these cells do not differentiate into a memory functional phenotype. The expression of IL-15Rα, which was detected on CD8+ CTLs but not on CD4+ helper T cells, suggests that this receptor subunit somehow participates in the transduction of the mitogenic signals of IL-15. The present findings have practical implications for the propagation of antigen-specific T-cell lines in vitro and could be useful for expansion of therapeutic T cells for adoptive transfer.

Role of hydrogen for the elastic properties of alumina thin films

Abstract: We describe the role of the presence of hydrogen on the elastic properties of AlxOyHz (0.32less than or equal toxless than or equal to0.4, 0.54less than or equal toyless than or equal to0.6, 3x10(- ...

Self-assembled two-dimensional hexagonal networks

Abstract: A new compound, 1,3,5-tris(carboxymethoxy)benzene, which forms infinite two-dimensional hexagonal networks, has been synthesized. Its self-assembly behavior at gas–solid interfaces has been studied by scanning tunneling microscopy.

Octaphenylbiphenylene and dodecaphenyltriptycene.

Abstract: Octaphenylbiphenylene, the expected dimer of tetraphenylbenzyne, has been prepared in low yield by diazotization of 3,4,5,6-tetraphenylanthranilic acid, and its X-ray structure has been determined. The X-ray structure of a second, abnormal dimer of tetraphenylbenzyne, 1,2,3,8,9,10-hexaphenyldibenzo[fg,op]naphthacene has also been determined; this is a saddle-shaped polycyclic aromatic hydrocarbon. 1,2,3,4,5,6,7,8,13,14,15,16-Dodecaphenyltriptycene, perhaps the most crowded triptycene derivative yet prepared, has been made by the reaction of tetraphenylbenzyne with 1,2,3,4,5,6,7,8-octaphenylanthracene, which in turn was synthesized in two steps from commercial starting materials. The X-ray structure of the dodecaphenyltriptycene nonabenzene solvate is a remarkable channel containing structure in which more than 50% of the unit cell volume is occupied by the benzene molecules.

Enhancing Immunogenicity of a CTL Epitope from Carcinoembryonic Antigen by Selective Amino Acid Replacements

Abstract: Purpose: Many epitopes from tumor antigens recognized by CTLs canbe poorly immunogenic. This low immunogenicity can be improved by carrying out amino acid replacements in their sequence. We have applied this strategy to enhance the immunogenicity of the HLA-A2-restricted CTL epitope CEA691 (IMIGVLVGV) from carcinoembryonic antigen (CEA), which is expressed by a wide variety of tumors. Experimental Design: Substituted peptides from CEA691 were synthesized and tested in HLA-A2-binding assays, and in recognition by CEA691-specific CTL. Selected peptides were used to induce CTL responses in vivo in HLA-A2Kb transgenic mice and in vitro with human cells. Results: Our experiments afforded several peptides with enhanced binding and/or recognition by CTL specific of CEA691. However, when HLA-A2Kb mice were immunized with these peptides only a few induced a CTL response that cross-reacted with CEA691. Additional replacement of their NH 2 -terminal amino acid by Y (tyrosine) afforded peptides YMIGMLVGV and YMIGVLLGV with enhanced in vivo and in vitro immunogenicity than CEA691. Indeed, they activated a greater number of precursor cells that recognized CEA691-pulsed cells and tumor cells expressing CEA. Conclusions: Our results widen the possibility of treating CEA-expressing tumors with enhanced efficacy.

Solution structure of the Vam7p PX domain.

Abstract: PX domains have been recently found to act as phosphoinositide binding modules. In the yeast SNARE protein Vam7p, the PX domain binds to PtdIns(3)P and is required for vacuolar targeting. To gain i...

Interlayer exchange coupling and giant magnetoresistance in Fe/V (001) superlattices

Abstract: Magnetization and magnetoresistivity studies of Fe/V (001) superlattices are reported. The first giant magnetoresistance peak with respect to the vanadium and iron layer thicknesses is investigated. The interlayer antiferromagnetic coupling strength is found to show a peak at a vanadium layer thickness of 13 atomic monolayers $(\ensuremath{\approx}20 \mathrm{\AA{}})$ with a full width at half maximum of about 2 monolayers. The antiferromagnetic coupling shows a maximum at an iron layer thickness of about 6 monolayers $(\ensuremath{\approx}9 \mathrm{\AA{}})$ for series of superlattices with vanadium thicknesses around 13 monolayers. The magnitude of the giant magnetoresistance shows a similar variation as the antiferromagnetic coupling strength.

Iodide-Based Atomic Layer Deposition of ZrO2 : Aspects of Phase Stability and Dielectric Properties

Abstract: This study is an investigation into the influence of temperature, substrate, and thickness on the properties of ZrO2 thin films grown by atomic layer deposition (ALD) ZrI4 and H2O2 were used as so

Growth of nano-sized copper seed layer on TiN and TaSiN by new non-toxic electroless plating

Abstract: The purpose of this research is to explore the properties of a copper seed layer grown by electroless plating on TiN. We have developed a displacement layer made of amorphous silicon (a-Si) and copper contact displacement process to improve the island structure of copper activated layer which can then be grown directly on the surface of TiN. Furthermore, this research proposes glyoxylic acid as a replacement for formaldehyde, which is commonly used at present as a reductant but regarded as a carcinogen, and is of high volatility. The copper seed layer has been grown by the electroless plating method on an activated surface of TiN, at the set temperature of 60/spl deg/C with the plating bath consisting of the copper source, complexing agent, stabilizer and surfactant. The existence of a copper seed layer provides not only the conduction layer, but also the copper nucleation layer, to help the growth of electroplated copper on the surface of TiN. Moreover, based on the results of the studies can lead us to grow a nano-sized Cu seed layer on the top of a TaSiN layer.