bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erwinia chrysanthemi tolCIs Involved in Resistance to Antimicrobial Plant Chemicals and Is Essential for Phytopathogenesis†
Authors: Barabote Ravi D. , Johnson Oswald L. , Zetina Eric , San Francisco Susan K. , Fralick Joe A. , San Francisco Michael J. D. 
Published: September 2003

ABSTRACTTolC is the outer-membrane component of several multidrug resistance (MDR) efflux pumps and plays an important role in the survival and virulence of many gram-negative bacterial animal pathogens. We have identified and characterized the outer-membrane protein-encoding genetolCin the bacterial plant pathogenErwinia chrysanthemiEC16. The gene was found to encode a 51-kDa protein with 70% identity to itsEscherichia colihomologue. TheE. chrysanthemigene was able to functionally complement theE. coli tolCgene with respect to its role in MDR efflux pumps. AtolCmutant ofE. chrysanthemiwas found to be extremely sensitive to antimicrobial agents, including several plant-derived chemicals. This mutant was unable to grow in planta and its ability to cause plant tissue maceration was severely compromised. ThetolCmutant was shown to be defective in the efflux of berberine, a model antimicrobial plant chemical. These results suggest that by conferring resistance to the antimicrobial compounds produced by plants, theE. chrysanthemi tolCplays an important role in the survival and colonization of the pathogen in plant tissue.
The Naphthalene Catabolic (
nag
) Genes of
Ralstonia
sp. Strain U2 Are an Operon That Is Regulated by NagR, a LysR-Type Transcriptional Regulator
Authors: Jones Rheinallt M. , Britt-Compton Bethan , Williams Peter A. 
Published: September 2003

ABSTRACT

In
Ralstonia
sp. strain U2, the
nag
catabolic genes, which encode the enzymes for the pathway that catabolizes naphthalene via the alternative ring cleavage gentisate pathway, are transcribed as an operon under the same promoter.
nagR
, which encodes a LysR-type transcriptional regulator, is divergently transcribed compared to the
nag
catabolic genes. A 4-bp frameshift deletion in
nagR
demonstrated that NagR is required for expression of the
nag
operon. The transcriptional start of the
nag
operon was mapped, and a putative −10, −35 σ
70
-type promoter binding site was identified. Further upstream, a site proximal to the promoter was identified as a site that has bases which have been found to be conserved in the activator-binding motif of other naphthalene pathways. Transcriptional fusion studies demonstrated that NagR regulates the expression of the
nag
operon positively in the presence of salicylate and to a lesser extent in the presence of 2-nitrobenzoate. Mutation of the LysR-type activator-binding motif in the
nag
promoter-proximal region resulted in a loss of inducibility of a
lacZ
reporter gene transcriptionally fused to
nagAa
, the first gene of the operon. However, other mutations in the region increased the effectiveness of salicylate as an inducer.
Dual Overlapping Promoters ControlnapF(Periplasmic Nitrate Reductase) Operon Expression inEscherichia coliK-12
Authors: Stewart Valley , Bledsoe Peggy J. , Williams Stanly B. 
Published: September 2003

ABSTRACTEscherichia colielaborates a flexible respiratory metabolism, involving differential synthesis of isoenzymes for many oxidation and reduction reactions. Periplasmic nitrate reductase, encoded by thenapFDAGHBCoperon, functions with concentrations of nitrate that are too low to support respiration by membrane-bound nitrate reductase. ThenapFoperon control region exhibits unusual organization of DNA binding sites for the transcription regulators Fnr and NarP, which activate transcription in response to anaerobiosis and nitrate, respectively. Previous studies have shown that thenapFoperon control region directs synthesis of two transcripts whose 5′ ends differ by about 3 nucleotides. We constructed mutant control regions in which either of the two promoter −10 regions is inactivated. Results indicate that the downstream promoter (P1) was responsible for Fnr- and NarP-regulatednapFoperon expression, whereas transcription from the upstream promoter (P2) was activated only weakly by the Fnr protein and was inhibited by phospho-NarP and -NarL proteins. The physiological function of promoter P2 is unknown. These results establish the unconventionalnapFoperon control region architecture, in which the major promoter P1 is activated by the Fnr protein bound to a site centered at −64.5 with respect to the transcription initiation site, working in conjunction with the phospho-NarP protein bound to a site centered at −44.5.
Characterization and Regulation of the Genes for a Novel Anthranilate 1,2-Dioxygenase from
Burkholderia cepacia
DBO1
Authors: Chang Hung-Kuang , Mohseni Paria , Zylstra Gerben J. 
Published: September 2003

ABSTRACT

Anthranilate (2-aminobenzoate) is an important intermediate in tryptophan metabolism. In order to investigate the degradation of tryptophan through anthranilate by
Burkholderia cepacia
, several plasposon mutations were constructed of strain DBO1 and one mutant with the plasposon insertion in the anthranilate dioxygenase (AntDO) genes was chosen for further study. The gene sequence obtained from flanking DNA of the plasposon insertion site revealed unexpected information.
B. cepacia
DBO1 AntDO (designated AntDO-3C) is a three-component Rieske-type [2Fe-2S] dioxygenase composed of a reductase (AndAa), a ferredoxin (AndAb), and a two-subunit oxygenase (AndAcAd). This is in contrast to the two-component (an oxygenase and a reductase) AntDO enzyme from
Acinetobacter
sp. strain ADP1,
P. aeruginosa
PAO1, and
P. putida
P111. AntDO from strains ADP1, PAO1, and P111 are closely related to benzoate dioxygenase, while AntDO-3C is closely related to aromatic hydrocarbon dioxygenases from
Novosphingobium aromaticivorans
F199 and
Sphingomonas yanoikuyae
B1 and 2-chlorobenzoate dioxygenase from
P. aeruginosa
strains 142 and JB2.
Escherichia coli
cells expressing the functional AntDO-3C genes transform anthranilate and salicylate (but not 2-chlorobenzoate) to catechol. The enzyme includes a novel reductase whose absence results in less efficient transformation of anthranilate by the oxygenase and ferredoxin. AndR, a possible AraC/XylS-type transcriptional regulator, was shown to positively regulate expression of the
andAcAdAbAa
genes. Anthranilate was the only effector (of 12 aromatic compounds tested) that was able to induce expression of the genes.
Merging Fractal Image Compression and Wavelet Transform Methods
Authors: van de Walle A. 
Published: September 2003

Fractal image compression and wavelet transform methods can be combined into a single compression scheme by using an iterated function system to generate the wavelet coefficients. The main advantage of this approach is to significantly reduce the tiling artifacts: operating in wavelet space allows range blocks to overlap without introducing redundant coding. Our scheme also permits reconstruction in a finite number of iterations and lets us relax convergence criteria. Moreover, wavelet coefficients provide a natural and efficient way to classify domain blocks in order to shorten compression times. Conventional fractal compression can be seen as a particular case of our general algorithm if we choose the Haar wavelet decomposition. On the other hand, our algorithm gradually reduces to conventional wavelet compression techniques as more and more range blocks fail to be properly approximated by rescaled domain blocks.
Treatment of multiple myeloma
Authors: Barlogie Bart , Shaughnessy John , Tricot Guido , Jacobson Joth , Zangari Maurizio , Anaissie Elias , Walker Ron , Crowley John 
Published: September 2003

AbstractAutologous peripheral blood stem cell (PBSC)–supported high-dose melphalan is now considered standard therapy for myeloma, at least for younger patients. The markedly reduced toxicity of allotransplants using nonmyeloablative regimens (mini-allotransplantations) may hold promise for more widely exploiting the well-documented graft-versus-myeloma (GVM) effect. New active drugs include immunomodulatory agents, such as thalidomide and CC-5013 (Revimid; Celgene, Warren, NJ), and the proteasome inhibitor, PS 341 (Velcade; Millenium, Cambridge, MA), all of which not only target myeloma cells directly but also exert an indirect effect by suppressing growth and survival signals elaborated by the bone marrow microenvironment's interaction with myeloma cells. Among the prognostic factors evaluated, cytogenetic abnormalities (CAs), which are present in one third of patients with newly diagnosed disease, identify a particularly poor prognosis subgroup with a median survival not exceeding 2 to 3 years. By contrast, in the absence of CAs, 4-year survival rates of 80% to 90% can be obtained with tandem autotransplantations. Fundamental and clinical research should, therefore, focus on the molecular and biologic mechanisms of treatment failure in the high-risk subgroup.
Inhibitory effect of imatinib on normal progenitor cells in vitro
Authors: Bartolovic Kerol , Balabanov Stefan , Hartmann Ulrike , Komor Martina , Boehmler Andreas M. , Bühring Hans-Jörg , Möhle Robert , Hoelzer Dieter , Kanz Lothar , Hofmann Wolf-Karsten , Brümmendorf Tim H. 
Published: September 2003

AbstractImatinib is a novel tyrosine kinase inhibitor used for the treatment of Philadelphia chromosome–positive leukemias and other malignancies. Side effects are mostly moderate; however, a dose-dependent hematologic toxicity affecting all hematopoietic lineages is observed clinically. The aim of this study was to investigate the effect of imatinib on normal hematopoietic stem and progenitor cells in vitro. A dose-dependent decrease in proliferation potential was found when CD34+ cells were expanded in serum-free medium supplemented with 6 growth factors and imatinib. Functionally, a decrease in colony-forming capacity was observed under increasing doses of imatinib. However, no such effect on more primitive cobblestone area–forming cells was detectable. Both withdrawal of stem cell factor from our expansion cultures or functional inhibition of c-kit led to a similar degree of inhibition of expansion, whereas the effect of imatinib was substantially greater at all dose levels tested. These data suggest a significant inhibitory effect of imatinib on normal CD34+ progenitor (but not stem) cells that is largely independent of c-kit signaling.
Distinctive response of naïve lymphocytes from cord blood to primary activation via TCR
Authors: Cantó Elisabet , Rodriguez-Sanchez Jose Luis , Vidal Silvia 
Published: September 2003

AbstractUmbilical cord blood (UCB) is now being considered an alternative to bone marrow for restoring hematopoiesis after myeloablative therapy. The lower risk of acute and chronic graft-versus-host disease in patients who received UCB cells seems related to the nature of UCB–T cells. Phenotypically, UCB–CD3+ cells are mostly naive (CD45RA+) and represent a transitional population between thymocytes and adult T cells. We examined the immune reactivity of highly purified, negatively selected CD4+CD45RA+ cells by mimicking activation via T cell receptor (TCR). All experiments included the extensively characterized adult peripheral blood (APB) cells as reference. On the contrary to APB, naive UCB–CD4+ cells were able to proliferate with anti-CD3 stimulation alone. With addition of interleukin (IL)-2 or costimulatory signal, both populations reached similar proliferation. Forty-eight hours after anti-CD3 stimulation, CD4+CD45RA+ from UCB, but not APB, showed characteristic blastic morphology and significant expression of CD25 on the surface. A low concentration of IL-2 was detected at 24 h by anti-CD3-stimulated UCB CD4+CD45RA+, which rapidly disappeared. By 72 h after activation, CD4+CD45RA+ UCB cells showed extensive apoptosis, whereas CD4+CD45RA+ APB cells showed low levels of apoptosis. Using RNase protection assay, we observed that CD95L levels were significantly higher in naive CD4+ cells from UCB than from APB after activation. However, neutralizing Fas-Fc protein was unable to inhibit anti-CD3-induced apoptosis, suggesting that this was a CD95-independent mechanism. These results indicate that UCB–CD4+CD45RA+ cells are able to start proliferating as a result of early IL-2 production after TCR engagement alone, but probably, as a result of the consumption of this IL-2, they undergo cell death.
HIV-1 gp120 induces anergy in naive T lymphocytes through CD4-independent protein kinase-A-mediated signaling
Authors: Masci Anna Maria , Galgani Mario , Cassano Silvana , De Simone Salvatore , Gallo Adriana , De Rosa Veronica , Zappacosta Serafino , Racioppi Luigi 
Published: September 2003

AbstractThe ability of the envelope glycoprotein gp120 [human immunodeficiency virus (HIV) env] to induce intracellular signals is thought to contribute to HIV-1 pathogenesis. In the present study, we found that the exposure of CD4+ CD45RA+ naive T cells to HIVenv results in a long-lasting hyporesponsiveness to antigen stimulation. This phenomenon is not dependent on CD4-mediated signals and also can be generated by the exposure of naive T cell to soluble CD4-HIVenv complexes. The analysis of the proximal signaling reveals that HIVenv does not activate Lck as well as the mitogen-activated protein kinase intermediate cascade. Conversely, the envelope glycoprotein stimulates the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) activity and induces the progressive accumulation of the phosphorylated form of the cAMP-responsive element binding. Of note, the ligation of CXCR4 by stromal cell-derived factor-1α but not the engagement of CD4 by monoclonal antibody stimulates the PKA activity and induces a long-lasting hyporesponsivity state in naive CD4+ lymphocytes. The pretreatment of lymphocytes with H89, a cell-permeable PKA inhibitor, prevents the induction of anergy. These findings reveal a novel mechanism by which HIVenv may modulate the processes of clonal expansion, homeostatic proliferation, and terminal differentiation of the naive T lymphocyte subset.
Calcium-Sensing Receptor Induces Messenger Ribonucleic Acid of Human Securin, Pituitary Tumor Transforming Gene, in Rat Testicular Cancer
Authors: Tfelt-Hansen Jacob , Schwarz Peter , Terwilliger Ernest F. , Brown Edward M. , Chattopadhyay Naibedya 
Published: September 2003

Abstract
Pituitary tumor transforming gene (PTTG), the human ortholog of securin, is an oncogene. Few normal tissues express PTTG, although in the testis, it is more abundantly expressed. In cancer, however, its wide expression has been directly correlated with the proliferation and angiogenesis, although very little is known about the overall regulation of the PTTG gene. In this study, we investigate the role of the calcium-sensing receptor (CaR), a G protein-coupled receptor (GPCR), in regulating PTTG in a widely used model of humoral hypercalcemia of malignancy, the rat H-500 Leydig cell testicular cancer. We show that extracellular calcium (Ca2+o) up-regulates PTTG mRNA. This up-regulation has a rapid onset, starting at 0.5 h, and remains up-regulated until 40 h. The up-regulation was also Ca2+o concentration dependent, with increases (mean ± se) of 4.22 ± 1.61-fold, 5.11 ± 1.11-fold, and 5.64 ± 1.92-fold at 5, 7.5, and 10 mm calcium, respectively, compared with 0.5 mm Ca2+o. This effect was abolished by overexpression of a dominant-negative CaR (R185Q), thereby confirming that the effect of high Ca2+o is CaR mediated. Another GPCR agonist, ADP, had no effect on PTTG expression. Because PTTG has been reported to induce angiogenesis, we investigated the effect of elevated Ca2+o on vascular endothelial growth factor (VEGF) expression. Indeed high calcium up-regulated VEGF mRNA by 1.59 ± 0.22-fold. In conclusion, we show for the first time that a GPCR, the CaR, stimulates the synthesis of PTTG mRNA in a nonmetastasizing model for humoral hypercalcemia of malignancy and, in the process, might induce angiogenesis via VEGF.
Inhibition of Prolactin (PRL)-Induced Proliferative Signals in Breast Cancer Cells by a Molecular Mimic of Phosphorylated PRL, S179D-PRL
Authors: Schroeder Matthew D. , Brockman Jennifer L. , Walker Ameae M. , Schuler Linda A. 
Published: September 2003

Abstract
Posttranslational modifications of prolactin (PRL), including phosphorylation, vary with physiologic state and alter biologic activity. In light of the growing evidence for a role for PRL in proliferation in mammary cancer, we examined the ability of a mimic of phosphorylated human PRL, S179D-PRL, to initiate signals to several pathways in mammary tumor cells alone and in combination with unmodified PRL. Unmodified PRL employed multiple pathways to increase cellular proliferation and cyclin D1 levels in PRL-deficient MCF-7 cells. S179D-PRL was a weak agonist compared with unmodified PRL with regard to cellular proliferation, cyclin D1 levels, and phosphorylation of signal transducer and activator of transcription 5 and ERKs. However, S179D-PRL was a potent antagonist of unmodified PRL to these endpoints. In contrast to the reduced levels of the long isoform of the PRL receptor observed in response to a 3-d incubation with unmodified PRL, S179D-PRL up-regulated expression of this isoform, 4-fold. These studies support the utility of this mutant as a PRL antagonist to proliferative signals in mammary epithelial cells, including a potential role in breast cancer therapeutics.
Peptide Purification, Complementary Deoxyribonucleic Acid (DNA) and Genomic DNA Cloning, and Functional Characterization of Ghrelin in Rainbow Trout
Authors: Kaiya Hiroyuki , Kojima Masayasu , Hosoda Hiroshi , Moriyama Shunsuke , Takahashi Akiyoshi , Kawauchi Hiroshi , Kangawa Kenji 
Published: September 2003

Abstract
We have identified ghrelin from the stomach of rainbow trout. Four isoforms of ghrelin peptide were isolated: the C-terminal amidated type of rainbow trout ghrelin (rt ghrelin) composed of 24 amino acids (GSSFLSPSQKPQVRQGKGKPPRV-amide) is a basic form; des-VRQ-rt ghrelin, which deleted three amino acids (V13R14Q15) from rt ghrelin; and further two types of rt ghrelin that retained the glycine residue at the C terminus, rt ghrelin-Gly, and des-VRQ-rt ghrelin-Gly. The third serine residue was modified by octanoic acid, decanoic acid, or the unsaturated form of those fatty acids. In agreement with the isolated peptides, two cDNAs of different lengths were isolated. The rt ghrelin gene has five exons and four introns, and two different mRNA molecules are predicted to be produced by alternative splicing of the gene. A high level of ghrelin mRNA expression was detected in the stomach, and moderate levels were detected in the brain, hypothalamus, and intestinal tracts. Des-VRQ-rt ghrelin stimulated the release of GH in the rat in vivo. Furthermore, des-VRQ-rt ghrelin stimulated the release of GH, but not the release of prolactin and somatolactin in rainbow trout in vivo and in vitro. These results indicate that ghrelin is a novel GH secretagogue in rainbow trout that may affect somatic growth or osmoregulation through GH. Because ghrelin is expressed in various tissues other than stomach, it may play important role(s) in cellular function as a local regulator.
Behavior of polyoxyethylene‐containing interpenetrating polymer networks and their LiCLO4 complexes as phase transfer catalysts and ionic conductors
Authors: Xie Hong‐Quan , Wang Gui‐Gui , Guo Jun‐Shi 
Published: September 2003

AbstractSimultaneous grafted interpenetrating polymer networks (IPNs) based on [castor oil–poly(ethylene glycol) (PEG)] polyurethane and poly(alkyl methacrylate) were synthesized by simultaneously coupling castor oil and PEG with 2,4‐toluene diisocyanate and by radical polymerization of alkyl methacrylate with castor oil. The gel content of the IPNs is ∼96% in most cases. The IPNs were characterized by infrared spectroscopy. The effects of compositional variation of the IPNs on phase transfer catalytic efficiency and mechanical properties, and conductivity of the IPNs complexed with LiClO4 were also studied. The results show that the IPNs have good phase transfer catalytic ability in the Williamson reaction and exhibit a maximum conversion of potassium phenolate at 55% polyoxyethylene (PEO). The phase transfer catalytic ability of the IPN increases with molecular weight of PEG used in the IPN synthesis and with the length of alkyl groups of the grafts, but decreases with increasing crosslinking degree. The complex of the IPNs with LiClO4 exhibits good ionic conductivity at room temperature in the range 10−5–3 × 10−4 S/cm. This ionic conductivity decreases with increasing either the crosslinking degree or the molecular weight of PEG used, but increases with increasing PEO content. The more compatible are the grafts with PEO, the lower is the conductivity. Either butyl methacrylate or ethyl methacrylate is a good choice for the monomer in the synthesis of the IPNs for use as phase transfer catalysts and ion conducting materials. The IPNs showed high tensile strength in the range 10–20 MPa. The good mechanical properties of the IPNs favor their applications as a strong solid polymer electrolyte film and an easily recoverable phase transfer catalyst. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 830–836, 2003
Novel sorbents based on silica coated with polyethylenimine and crosslinked with poly(carboxylic acid): Preparation and characterization
Authors: Ghoul M. , Bacquet M. , Crini G. , Morcellet M. 
Published: September 2003

AbstractNovel sorbents based on silica coated with polyethylenimine (SilPEI) and crosslinked with poly(carboxylic acid) were prepared and characterized. These sorbents are to be used for heavy metal decontamination of aqueous solutions and have to be prepared in easy and ecological ways. A part of the carboxylic moieties [from ethylenediaminetetraacetic acid (EDTA) or citric acid] reacts with some of the amine groups of polyethylenimine, initially coated onto the silica, whereas the other part remains free for further metal complexation. By changing various parameters (temperature, pH, presence or absence of an amide‐forming agent), the conditions to prepare the best sorbent—that is, the sorbent exhibiting both a high capacity for metal complexation and good stability in an acidic medium (conditions for metal desorption or stripping)—were defined. The sorbent was prepared by a reaction of 1 g of SilPEI and 1 g of EDTA in water at 0°C, pH 6, during 10 h, using 0.5 g of 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride as a coupling agent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 799–805, 2003
Preparation and adsorption properties of resins containing amine, sulfonic acid, and carboxylic acid moieties
Authors: Rivas Bernabé L. , Castro Alejandro 
Published: September 2003

AbstractCompletely water‐insoluble resins containing amine, carboxylic acid, and sulfonic acid as ligand groups were synthesized by radical polymerization in solution. The yield was higher than 97%. The resins were characterized by FTIR spectroscopy and thermal analysis. The metal ion retention properties at different pH values were investigated by a batch method. Metal ions studied were: Cu(II), Cd(II), Zn(II), Hg(II), Pb(II), and Cr(III). The metal ion binding ability depended strongly on the pH. The retention properties were also tested under competitive conditions. Elution of the metal ion was investigated in acid medium at different concentrations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 700–705, 2003