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Publications and source records attributed to Jian Zhang.
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The leptomeninges play a central role in the antiinflammatory response through the glia-neuron interaction during systemic inflammation. In the present study, we examined the possible production of two potent antiinflammatory mediators, prostaglandin E(2) (PGE(2)) and transforming growth factor-beta1 (TGF-beta1) by leptomeningeal cells during systemic inflammation. After immunization with the complete Freund's adjuvant (CFA), cyclooxygenase (COX)-2 and membrane-bound PGE synthase-1 (mPGES-1) were induced in the leptomeninges. Primary cultured leptomeningeal cells secreted PGE(2) after treatment with lipopolysaccharide (LPS) or proinflammatory cytokines. The LPS-induced release of PGE(2) was depressed by a selective COX-2 inhibitor, NS-398. On the other hand, TGF-beta1 and TGF-beta receptor II (TGF-betaRII) both markedly increased in the leptomeninges and the parenchymal cells after the CFA injection. Double-staining immunohistochemistry demonstrated TGF-beta1 to be induced in both glial cells and cortical neurons, whereas TGF-betaRII was induced only in cortical neurons. Furthermore, the conditioned medium prepared from the leptomeningeal cells after LPS stimulation was able to induce an increased expression of TGF-beta1 and TGF-betaRII in the primary cultured glial cells and cortical neurons. This increased expression was suppressed by NS-398. PGE(2) was found to increase directly the production of TGF-beta1 and TGF-betaRII in the primary cultured cells. These observations strongly suggest that PGE(2), which is biosynthesized by the leptomeninges, mainly regulates the production of TGF-beta1 by glial cells and cortical neuron, thus playing a protective role in the cortical neurons during systemic inflammation. Furthermore, TGF-beta1 may also exert a protective effect directly on the cortical neurons.
BACKGROUND: The Pediatric Preclinical Testing Program (PPTP) is an initiative supported by the National Cancer Institute (NCI) to identify novel therapeutic agents that may have significant activity against childhood cancers. The PPTP has established panels of childhood cancer xenografts and cell lines to be used for in vivo and in vitro testing. These include panels for Wilms tumor, sarcomas (rhabdomyosarcoma, Ewing sarcoma, and osteosarcoma), neuroblastoma, brain tumors (glioblastoma, ependymoma, and medulloblastoma), rhabdoid tumors (CNS and renal), and acute lymphoblastic leukemia (ALL). Here, we describe the characteristics of the in vivo tumor panels and report results for the in vivo evaluation of two standard agents, vincristine and cyclophosphamide. PROCEDURES: Solid tumors were grown subcutaneously in immune-deficient mice and tumor dimensions were measured weekly. ALL xenografts were inoculated intravenously and human CD45-positive cells were enumerated weekly. RESULTS: Vincristine-induced objective responses in 6 of 24 (25%) and cyclophosphamide-induced objective responses in 18 of 28 (64%) solid tumor models. Comparable assessments of high levels of activity for these two agents were obtained using a tumor growth delay (TGD) measure. Both agents induced regressions in each of the ALL models evaluated. CONCLUSIONS: We have established 51 solid tumor and 10 ALL in vivo models. The models identify vincristine and cyclophosphamide as having broad-spectrum activity. The PPTP tumor panels appear to generally recapitulate the activity of these agents against specific childhood cancers and to have the potential for identifying novel agents having significant clinical activity.
Immunotherapy is an attractive therapeutic option for patients with haematological malignancies. Until recently, the progress in the development of tumour vaccines for haematological malignancies had been slow due to the lack of suitable targets. Cancer-testis (CT) antigens are potentially suitable molecules for tumour vaccines of haematological malignancies because of their high immunogenicity in vivo and their relatively restricted normal tissue distribution. This review evaluates the properties and potential functions of CT antigens. We discuss the expression of CT antigens in patient with haematological malignancies and provide evidence in support of their immunogenicity in vivo in these patients. We also address the role of 'epigenetic' regulation of CT antigens in haematological malignancies and how hypomethylating agents could induce the expression of some of these antigens in tumour cells to overcome the problem of heterogeneity of expression of the antigen within individual tumour specimens. Data implicating the interaction of the promoter genes of some of these CT antigens with the MeCP2 protein also suggest the potential role of the histone deacetylase inhibitors in inducing antigen expression in tumour cells. Finally, we discuss the direction of future research in advancing the development of tumour vaccines for haematological malignancies.
The self-assembly of a series of hexadehydrotribenzo[12]annulene (DBA) derivatives has been scrutinized by scanning tunneling microscopy (STM) at the liquid-solid interface. First, the influence of core symmetry on the network structure was investigated by comparing the two-dimensional (2D) ordering of rhombic bisDBA 1a and triangular DBA 2a (Figure 1). BisDBA 1a forms a Kagomé network upon physisorption from 1,2,4-trichlorobenzene (TCB) onto highly oriented pyrolytic graphite (HOPG). Under similar experimental conditions, DBA 2a shows the formation of a honeycomb network. The core symmetry and location of alkyl substituents determine the network structure. The most remarkable feature of the DBA networks is the interdigitation of the nonpolar alkyl chains: they connect the pi-conjugated cores and direct their orientation. As a result, 2D open networks with voids are formed. Second, the effect of alkyl chain length on the structure of DBA patterns was investigated. Upon increasing the length of the alkyl chains (DBAs 3c-e) a transition from honeycomb networks to linear networks was observed in TCB, an observation attributed to stronger molecule-substrate interactions. Third, the effect of solvent on the structure of the nonpolar DBA networks was investigated in four different solvents: TCB as a polar aromatic solvent, 1-phenyloctane as a solvent having both aromatic and aliphatic moieties, n-tetradecane as an aliphatic solvent, and octanoic acid as a polar alkylated solvent. The solvent dramatically changes the structure of the DBA networks. The solvent effects are discussed in terms of factors that influence the mobility of molecules at the liquid-solid interface such as solvation.
The ability of foldamers to adopt a secondary structure in solution has been exploited to organize peripheral functionality. Our previously reported poly(ureidophthalimide) foldamer proved to be an excellent scaffold for the chiral organization of peripherally positioned oligo(p-phenylenevinylene) (OPV) chromophores. Facile high-yielding synthesis gave access to the required OPV-decorated building blocks. A condensation polymerization provided polymers of sufficient length to allow construction of a helical architecture comprising several turns. Short and long chains were separated by chromatography. Circular dichroism studies in THF of the longer chains indicate the presence of helically arranged OPVs. However, such an effect is not observed in CHCl3. Remarkable are the measurements of the OPV foldamers in heptane. A bisignate Cotton effect is observed in heptane of a sample with a THF history. No Cotton effect is observed in heptane of a sample with a CHCl3 history. In this example of supramolecular synthesis, the solvent dictates the expression of supramolecular chirality in a secondary structure. The short-chain oligomeric fractions that are unable to create a full turn revealed on scanning tunneling microscopy analysis the presence of circular architectures at the graphite/1-phenyloctane interface. This is in full agreement with the proposed conformation of the decorated foldamers.
SPAN-Xb is a novel cancer-testis antigen in multiple myeloma. We recently demonstrated that SPAN-Xb expression in myeloma cells is regulated through promoter methylation and could be upregulated by IL-7 and GM-CSF. In this present study, we set out to investigate the mechanism of SPAN-XB expression and the promoter association with the methyl-CpG binding protein (MeCP2). Elucidation of these interactions is likely shed light on potential therapeutic strategies to upregulate antigen levels for SPAN-Xb-based tumor vaccines. Using a panel of truncated promoter constructs, we localize the core sequence of SPAN-XB promoter to the 73 bp at the 3' end of the promoter, a region within the full length promoter that lacks CpG dinucleotides. Reporter gene expression assays showed that the core promoter function is significantly modulated by the adjacent CpG sequences. Chromatin immunoprecipitation assays revealed a specific association of MeCP2 with the promoter, and MeCP2 binding strongly correlated with repression of SPAN-XB gene. Reactivation of the SPAN-XB gene by 5-azacytidine treatment resulted in the loss of MeCP2 from this site. We, therefore, conclude that SPAN-XB core promoter function in myeloma cells is associated with MeCP2 protein binding and regulated by specific CpG dinucleotide sequences.
We describe the synthesis, supramolecular ordering on surfaces and in solution, and photophysical characterization of OPV4UT-PERY, an oligo(p-phenylenevinylene) (OPV) with a covalently attached perylene bisimide moiety. In chloroform, the molecule forms dimers through quadruple hydrogen bonding of the ureido-s-triazine array. This is supported by scanning tunneling microscopy (STM) studies, which reveal dimer formation at the liquid (1,2,4-trichlorobenzene)/solid (graphite) interface. Moreover, contrast reversal in bias-dependent STM imaging provides information on the ordering and different electronic properties of the oligo(p-phenylenevinylene) and perylene bisimide moieties. In dodecane, the molecule self-assembles into H-type aggregates that are still soluble as a result of the hydrophobic shell formed by the dodecyloxy wedges. The donor-acceptor molecule is characterized by efficient energy transfer from the photoexcited OPV to the perylene bisimide. Mixed assemblies with analogous OPVs lacking the perylene bisimide unit have been prepared in dodecane solution and energy transfer to the incorporated perylene bisimides has been studied by fluorescence spectroscopy.
Various isomers of macropolyhedral borane ions [B20H18]n (n = 0, -2, -4) are investigated by using the density functional theory methods at RB3LYP/6-31+G* and RB3LYP/6-31G* levels to obtain the optimized geometries, harmonic vibrational frequencies, electron structures, and the stability order. The calculated results show that optimized bond lengths are consistent with the available experimental values and the natural populations, taking [a2 -B20H18]4- (4) as an example, are also in agreement with NMR spectra. The calculated vibrational frequencies are all real, so all of these isomers could be stable, among which [a2 -B20H18]2- (3) and [a2 -B20H18]0 (7) are considered for the first time in this paper. On the basis of the contour maps of molecular orbitals, the delocalized characteristic of molecular orbitals and the possible redox mechanism of these ions are also discussed. Moreover, the analysis on counting of skeletal bonding electrons shows that the isomers (1)-(6) obey the electronic requirement predicted by the mno rule, whereas the newly predicted isomer (7) does not match the mno rule.
Naturally occurring camptothecins (CPT) are important sources of chemotherapeutic agents for clinical treatment of cancer. Extraction of CPT from Camptotheca acuminata trees remains to be a cost-effective way in the supply equation compared with a total synthesis. This study conducted a series of experiments to determine efficient solvent for the maximal extraction of CPT and its two derivatives, hydroxycamptothecin (HCPT) and methoxycamptothecin, from seeds and leaves of C. acuminata. Methanol as an extraction solvent demonstrated in seeds a significantly higher recovery of these three alkaloids than dichloromethane and acetone. Methanol concentrations at 70% in water resulted in maximum extraction of all the three alkaloids regardless of the type of plant materials. However, other strengths of methanol, lower or higher, either decreased the extracting power or showed no improvement in the extraction. Seed extract contained all the three alkaloids whereas leaf extract was absent of HCPT. A stable ratio of the three alkaloids was discovered but it was dependent upon seed or leaf extract of C. acuminata, which with various compositions can be produced. Ecological and medicinal implications of the leaf and seed extract characterized with different chemical compositions are discussed.
By using immunocytochemical techniques, we demonstrate that there are two distinct, nonoverlapping populations of horizontal cells (HCs) in the tiger salamander retina: GABA-positive cells account for about 72% and GABA-negative (calretinin-positive) cells account for 28% of the total HC somas. The calretinin-positive HCs have relatively sparse and thick dendrites: soma diameter of 19.72 +/- 0.29 microm, and soma density of 140 +/- 13 cells/mm(2), morphological features very much like the A-type HCs described in the accompanying article. The GABA-positive HCs have thinner dendritic and coarse axon-terminal-like processes of higher density: soma diameter of 18 +/- 0.18 microm, and soma density of 364 +/- 18 cells/mm(2), features that very much resemble the B-type HCs and B-type HC axon terminals in the accompanying article. By using double and triple immunostaining techniques we found that only 18% of the non-GABAergic HC dendritic clusters contact rods, whereas the remaining 82% of the dendritic clusters contact cones. This is consistent with the physiological finding in the accompanying article that the A-type HCs are cone-dominated. On the other hand, 32% of GABAergic HC dendrites contact rod pedicles and 68% contact cone pedicles, consistent with the physiological finding that B-type HCs and B-type HC axon terminals receive mixed rod/cone inputs. Detailed confocal microscope analysis shows that 4% rods, 6% principal double cones/single cones, and 100% accessory double cones contact calretinin-positive HCs, and 79% rods, 100% principal double cones, 14% accessory double cones, and 82% single cones contact GABAergic HCs. These results suggest that GABAergic and non-GABAergic HC input/output synapses differ and they may mediate different functional pathways in the outer retina.
Light responses, dendritic/axonal morphology, receptive field diameters, patterns of dye coupling, and relative rod/cone inputs of various types of horizontal cells (HCs) were studied using intracellular recording and Lucifer yellow/neurobiotin dye injection methods in the flatmount tiger salamander retina. Three physiologically and morphologically distinct types of HC entities were identified. 1) The A-type HCs are somas that do not bear axons, with average (+/-SE) soma diameters of 20.01 +/- 0.59 microm, relatively sparse and thick dendrites, and they resemble the A-type HC in mammals. The average receptive field diameter of these cells is 529.6 +/- 10.87 microm and they receive inputs predominantly from cones. 2) The B-type HCs are broad-field somas that bear thin and long axons, with average soma diameters of 17.67 +/- 0.38 microm, thinner dendrites of higher density, and they resemble the B-type HC in mammals. The average receptive field diameter of these cells is 1,633.55 +/- 37.34 microm and they receive mixed inputs from rods and cones. 3) The B-type HC axon terminals are broad-field, coarse axon terminal processes and they resemble the B-type HC axon terminal in rabbits. The average receptive field diameter of these axon terminals is 1,291.67 +/- 24.02 microm and they receive mixed inputs from rods and cones. All these types of HC are dye-coupled with adjacent HCs of the same type. Additionally, B-type HCs and axon terminals are dye-coupled with subpopulations of bipolar cells whose axon terminals ramify in the proximal half of the inner plexiform layer, raising the possibility that these HCs may send feedforward antagonistic surround responses to depolarizing bipolar cells through electrical synapses.
BACKGROUND: Coagulase-negative Staphylococcus epidermidis has become a major frequent cause of infections in relation to the use of implanted medical devices. The pathogenicity of S. epidermidis has been attributed to its capacity to form biofilms on surfaces of medical devices, which greatly increases its resistance to many conventional antibiotics and often results in chronic infection. It has an urgent need to design novel antibiotics against staphylococci infections, especially those can kill cells embedded in biofilm. RESULTS: In this report, a series of novel inhibitors of the histidine kinase (HK) YycG protein of S. epidermidis were discovered first using structure-based virtual screening (SBVS) from a small molecular lead-compound library, followed by experimental validation. Of the 76 candidates derived by SBVS targeting of the homolog model of the YycG HATPase_c domain of S. epidermidis, seven compounds displayed significant activity in inhibiting S. epidermidis growth. Furthermore, five of them displayed bactericidal effects on both planktonic and biofilm cells of S. epidermidis. Except for one, the compounds were found to bind to the YycG protein and to inhibit its auto-phosphorylation in vitro, indicating that they are potential inhibitors of the YycG/YycF two-component system (TCS), which is essential in S. epidermidis. Importantly, all these compounds did not affect the stability of mammalian cells nor hemolytic activities at the concentrations used in our study. CONCLUSION: These novel inhibitors of YycG histidine kinase thus are of potential value as leads for developing new antibiotics against infecting staphylococci. The structure-based virtual screening (SBVS) technology can be widely used in screening potential inhibitors of other bacterial TCSs, since it is more rapid and efficacious than traditional screening technology.
The exocyst is a multiprotein complex essential for tethering secretory vesicles to specific domains of the plasma membrane for exocytosis. Here, we report that the exocyst component Exo70 interacts with the Arp2/3 complex, a key regulator of actin polymerization. We further show that the exocyst-Arp2/3 interaction is regulated by epidermal growth factor (EGF) signalling. Inhibition of Exo70 by RNA interference (RNAi) or antibody microinjection blocks the formation of actin-based membrane protrusions and affects various aspects of cell motility. We propose that Exo70, in addition to functioning in exocytosis, also regulates actin at the leading edges of migrating cells, therefore coordinating cytoskeleton and membrane traffic during cell migration.
NDRG2, a member of N-Myc downstream regulated gene family, exerts the important functions in cell differentiation and tumor suppression. Although the ectopic expressed Ndrg2 inhibits the proliferation of tumor cells, its intracellular signal transduction pathway is hardly known. Here, we identified MSP58, a 58-kDa microspherule protein, as an interacting partner of human Ndrg2 by using yeast two-hybrid screening. The interaction was confirmed by glutathione S-transferase pull-down assay in vitro and by co-immune-precipitation assay in vivo. The forkhead associated domain of MSP58 is essential for its interaction with Ndrg2. Ndrg2 could co-localize with MSP58 in nuclear of HeLa cell during cell stress. Furthermore, the modulation of Ndrg2 level influences the cell cycle process together with MSP58. In conclusion, the findings offered a novel insight into the physiological roles of Ndrg2.
Shikimate kinase (SK) is the fifth enzyme in the shikimate pathway and catalyzes the phosphate transfer from ATP to shikimate in generating shikimate 3-phosphate and ADP. SK has been developed as a promising target for the discovery of antibacterial agents. In this report, two small molecular inhibitors (compound 1, 3-methoxy-4-{[2-({2-methoxy-4-[(4-oxo-2-thioxo-1,3-thiazolidin-5-ylidene)methyl]phenoxy}methyl)benzyl]oxy}benzaldehyde; compound 2, 5-bromo-2-(5-{[1-(3,4-dichlorophenyl)-3,5-dioxo-4-pyrazolidinylidene]methyl}-2-furyl)benzoic acid) against Helicobacter pylori SK (HpSK) were successfully identified with IC(50) values of 5.5+/-1.2 and 6.4+/-0.4 microM, respectively. The inhibition kinetics shows that compound 1 is a noncompetitive inhibitor with respect to both shikimate and MgATP, and compound 2 is a competitive inhibitor toward shikimate and noncompetitive inhibitor with respect to MgATP. The surface plasmon resonance (SPR) technology based analysis reveals that the equilibrium dissociation constants (K(D)s) of compounds 1 and 2 with HpSK enzyme are 4.39 and 3.74 microM, respectively. The molecular modeling and docking of two inhibitors with HpSK reveals that the active site of HpSK is rather roomy and deep, forming an L-shape channel on the surface of the protein, and compound 1 prefers the corner area of L-shape channel, while compound 2 binds the short arm of the channel of SK in the binding interactions. It is expected that our current work might supply useful information for the development of novel SK inhibitors.
Recombinant human prolactin (rhPRL) was administered to huPBL-SCID mice to determine its effects on production of human immunoglobulin (Ig). The huPBL-SCID mice were injected intraperitoneally (i.p.) with 10 mug rhPRL every other day for a total of 10 injections. The results reconfirmed that rhPRL significantly increased the numbers of human CD3+ T cells and human CD19+ B cells in spleens, lymph nodes, and thymuses of huPBL-SCID mice. The huPBL-SCID mice were then concurrently given various doses of diphtheria-tetanus (DT) vaccine and 10-mug i.p. injections of rhPRL and were examined for the presence of human DT-specific proliferation of lymph node cells in vitro and antibody production in vivo. rhPRL greatly improved the engraftment of functional human lymphocytes (CD3+ T cells and CD19+ B cells) in DT-immunized huPBL-SCID mice. The rhPRL-treated, DT-immunized huPBL-SCID mice produced significantly larger amounts of DT-specific antibodies in response to the vaccine. The predominant Ig isotype induced after immunization was IgG. Thus, rhPRL stimulation promotes human secondary IgG responses in huPBL-SCID mice.
Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a 4Fe4S flavoprotein located in the inner mitochondrial membrane. It catalyzes ubiquinone (UQ) reduction by ETF, linking oxidation of fatty acids and some amino acids to the mitochondrial respiratory chain. Deficiencies in ETF or ETF-QO result in multiple acyl-CoA dehydrogenase deficiency, a human metabolic disease. Crystal structures of ETF-QO with and without bound UQ were determined, and they are essentially identical. The molecule forms a single structural domain. Three functional regions bind FAD, the 4Fe4S cluster, and UQ and are closely packed and share structural elements, resulting in no discrete structural domains. The UQ-binding pocket consists mainly of hydrophobic residues, and UQ binding differs from that of other UQ-binding proteins. ETF-QO is a monotopic integral membrane protein. The putative membrane-binding surface contains an alpha-helix and a beta-hairpin, forming a hydrophobic plateau. The UQ-flavin distance (8.5 A) is shorter than the UQ-cluster distance (18.8 A), and the very similar redox potentials of FAD and the cluster strongly suggest that the flavin, not the cluster, transfers electrons to UQ. Two possible electron transfer paths can be envisioned. First, electrons from the ETF flavin semiquinone may enter the ETF-QO flavin one by one, followed by rapid equilibration with the cluster. Alternatively, electrons may enter via the cluster, followed by equilibration between centers. In both cases, when ETF-QO is reduced to a two-electron reduced state (one electron at each redox center), the enzyme is primed to reduce UQ to ubiquinol via FAD.