bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyamine Effects on Antibiotic Susceptibility in Bacteria
Authors: Kwon Dong-Hyeon , Lu Chung-Dar 
Published: April 2007

ABSTRACT

Biogenic polyamines (e.g., spermidine and spermine) are a group of essential polycationic compounds found in all living cells. The effects of spermine and spermidine on antibiotic susceptibility were examined with gram-negative
Escherichia coli
and
Salmonella enterica
serovar Typhimurium bacteria and clinical isolates of
Pseudomonas aeruginosa
and with gram-positive
Staphylococcus aureus
bacteria, including methicillin-resistant
S. aureus
(MRSA). Exogenous spermine exerted a dose-dependent inhibition effect on the growth of
E. coli
,
S. enterica
serovar Typhimurium, and
S. aureus
but not
P. aeruginosa
, as depicted by MIC and growth curve measurements. While the MICs of polymyxin and ciprofloxacin were in general increased by exogenous spermine and spermidine in
P. aeruginosa
, this adverse effect was not observed in enteric bacteria and
S. aureus
. It was found that spermine and spermidine can decrease the MICs of β-lactam antibiotics in all strains as well as other types of antibiotics in a strain-dependent manner. Significantly, the MICs of oxacillin for MRSA Mu50 and N315 were decreased more than 200-fold in the presence of spermine, and this effect of spermine was retained when assessed in the presence of divalent ions (magnesium or calcium; 3 mM) or sodium chloride (150 mM). The effect of spermine on the sensitization of
P. aeruginosa
and MRSA to antibiotics was further demonstrated by population analysis and time-killing assays. The results of checkerboard assays with
E. coli
and
S. aureus
indicated a strong synergistic effect of spermine in combination with β-lactams and chloramphenicol. The decreased MICs of β-lactams implied that the possible blockage of outer membrane porins by exogenous spermine or spermidine did not play a crucial role in most cases. In contrast, only the MIC of imipenem against
P. aeruginosa
was increased by exogenous spermine and spermidine, and this resistance effect was abolished in a mutant strain devoid of the outer membrane porin OprD. In
E. coli
, the MICs of carbenicillin, chloramphenicol, and tetracycline were decreased in two
acrA
mutants devoid of a major efflux pump, AcrAB. However, retention of the spermine effect on antibiotic susceptibility in two
acrA
mutants of
E. coli
suggested that the AcrAB efflux pump was not the target for a synergistic effect by spermine and antibiotics and ruled out the hypothesis of spermine serving as an efflux pump inhibitor in this organism. In summary, this interesting finding of the effect of spermine on antibiotic susceptibility provides the basis for a new potential approach against drug-resistant pathogens by use of existing β-lactam antibiotics.
Association between
embB
Codon 306 Mutations and Drug Resistance in
Mycobacterium tuberculosis
Authors: Shen Xin , Shen Guo-miao , Wu Jie , Gui Xiao-hong , Li Xia , Mei Jian , DeRiemer Kathryn , Gao Qian 
Published: April 2007

ABSTRACT

embB306
mutants were detected in both ethambutol (EMB)-resistant and EMB-susceptible strains of
Mycobacterium tuberculosis
. Multidrug-resistant (MDR) strains had a higher proportion of
embB306
mutants than non-MDR strains (odds ratio, 6.78;
P
< 0.001). The
embB306
locus is a candidate marker for rapid detection of MDR and extremely drug resistant tuberculosis.
A Novel
Giardia lamblia
Nitroreductase, GlNR1, Interacts with Nitazoxanide and Other Thiazolides
Authors: Müller Joachim , Wastling Jonathan , Sanderson Sanya , Müller Norbert , Hemphill Andrew 
Published: April 2007

ABSTRACT

The nitrothiazole analogue nitazoxanide [NTZ; 2-acetolyloxy-
N
-(5-nitro-2-thiazolyl)benzamide] represents the parent compound of a class of drugs referred to as thiazolides and exhibits a broad spectrum of activities against a wide variety of helminths, protozoa, and enteric bacteria infecting animals and humans. NTZ and other thiazolides are active against a wide range of other intracellular and extracellular protozoan parasites in vitro and in vivo, but their mode of action and respective subcellular target(s) have only recently been investigated. In order to identify potential targets of NTZ and other thiazolides in
Giardia lamblia
trophozoites, we have developed an affinity chromatography system using the deacetylated derivative of NTZ, tizoxanide (TIZ), as a ligand. Affinity chromatography on TIZ-agarose using cell extracts of
G. lamblia
trophozoites resulted in the isolation of an approximately 35-kDa polypeptide, which was identified by mass spectrometry as a nitroreductase (NR) homologue (EAA43030.1). NR was overexpressed as a six-histidine-tagged recombinant protein in
Escherichia coli
, purified, and then characterized using an assay for oxygen-insensitive NRs with dinitrotoluene as a substrate. This demonstrated that the NR was functionally active, and the protein was designated GlNR1. In this assay system, NR activity was severely inhibited by NTZ and other thiazolides, demonstrating that the antigiardial activity of these drugs could be, at least partially, mediated through inhibition of GlNR1.
Identification of Transferrin-Binding Domains in TbpB Expressed by
Neisseria gonorrhoeae
Authors: DeRocco Amanda J. , Cornelissen Cynthia Nau 
Published: April 2007

ABSTRACT

The transferrin iron acquisition system of
Neisseria gonorrhoeae
is necessary for iron uptake from transferrin in the human host and requires the participation of two distinct proteins: TbpA and TbpB. TbpA is a TonB-dependent outer membrane transporter responsible for the transport of iron into the cell. TbpB is a lipid-modified protein, for which a precise role in receptor function has not yet been elucidated. These receptor complex proteins show promise as vaccine candidates; therefore, it is important to identify surface-exposed regions of the proteins required for wild-type functions. In this study we examined TbpB, which has been reported to be surface exposed in its entirety; however, this hypothesis has never been tested experimentally. We placed the hemagglutinin (HA) epitope into TbpB with the dual purpose of examining the surface exposure of particular epitopes as well as their impact on receptor function. Nine insertion mutants were created, placing the epitope downstream of the signal peptidase II cleavage site. We report that the HA epitope is surface accessible in all mutants, indicating that the full-length TbpB is completely surface exposed. By expressing the TbpB-HA fusion proteins in
N. gonorrhoeae
, we were able to examine the impact of each insertion on the function of TbpB and the transferrin acquisition process. We propose that TbpB is comprised of two transferrin-binding-competent lobes, both of which are critical for efficient iron uptake from human transferrin.
Memory CD4 T Cells Enhance Primary CD8 T-Cell Responses
Authors: Krawczyk Connie M. , Shen Hao , Pearce Edward J. 
Published: April 2007

ABSTRACT
CD4 T-cell help is required for optimal memory CD8 T-cell responses. We have found that engaging preexisiting CD4 Th1, but not Th2, memory cells at the time of CD8 T-cell priming results in increased CD8 effector responses to both bacterial and viral pathogens. The enhanced responses are characterized by increased numbers of cytokine-producing, antigen-specific cells. These findings suggest that engaging endogenous memory Th1 cells may increase cellular responses in an immunotherapy or vaccination setting.
Rapid Escape of thedot/icmMutants ofLegionella pneumophilainto the Cytosol of Mammalian and Protozoan Cells
Authors: Molmeret Maëlle , Santic’ Marina , Asare Rexford , Carabeo Reynold A. , Kwaik Yousef Abu 
Published: April 2007

ABSTRACTTheLegionella pneumophila-containing phagosome evades endocytic fusion and intercepts endoplasmic reticulum (ER)-to-Golgi vesicle traffic, which is believed to be mediated by the Dot/Icm type IV secretion system. Although phagosomes harboringdot/icmmutants are thought to mature through the endosomal-lysosomal pathway, colocalization studies with lysosomal markers have reported contradictory results. In addition, phagosomes harboring thedot/icmmutants do not interact with endocytosed materials, which is inconsistent with maturation of the phagosomes in the endosomal-lysosomal pathway. Using multiple strategies, we show that thedot/icmmutants defective in the Dot/Icm structural apparatus are unable to maintain the integrity of their phagosomes and escape into the cytoplasm within minutes of entry into various mammalian and protozoan cells in a process independent of the type II secretion system. In contrast, mutants defective in cytoplasmic chaperones of Dot/Icm effectors andrpoS,letA/S, andletEregulatory mutants are all localized within intact phagosomes. Importantly, non-dot/icm L. pneumophilamutants whose phagosomes acquire late endosomal-lysosomal markers are all located within intact phagosomes. Using high-resolution electron microscopy, we show that phagosomes harboring thedot/icmtransporter mutants do not fuse to lysosomes but are free in the cytoplasm. Inhibition of ER-to-Golgi vesicle traffic by brefeldin A does not affect the integrity of the phagosomes harboring the parental strain ofL. pneumophila. We conclude that the Dot/Icm transporter is involved in maintaining the integrity of theL. pneumophilaphagosome, independent of interception of ER-to-Golgi vesicle traffic, which is a novel function of type IV secretion systems.
T Cells Are Essential for Bacterial Clearance, and Gamma Interferon, Tumor Necrosis Factor Alpha, and B Cells Are Crucial for Disease Development inCoxiella burnetiiInfection in Mice
Authors: Andoh Masako , Zhang Guoquan , Russell-Lodrigue Kasi E. , Shive Heather R. , Weeks Brad R. , Samuel James E. 
Published: April 2007

ABSTRACTCoxiella burnetii, the etiological agent of Q fever, has two phase variants. Phase I has a complete lipopolysaccharide (LPS), is highly virulent, and causes Q fever in humans and pathology in experimental animals. Phase II lacks an LPS O side chain, is avirulent, and does not grow well in immunocompetent animals. To understand the pathogenicity of Q fever, we investigated the roles of immune components in animals infected with Nine Mile phase I (NM I) or Nine Mile phase II (NM II) bacteria. Immunodeficient mice, including SCID mice (deficient in T and B cells), SCIDbg mice (deficient in T, B, and NK cells), nude mice (deficient in T cells), muMT mice (deficient in B cells), bg mice (deficient in NK cells), mice deficient in tumor necrosis factor alpha (TNF-α−/−mice), and mice deficient in gamma interferon (IFN-γ−/−mice), were compared for their responses to infection. SCID, SCIDbg, nude, and IFN-γ−/−mice showed high susceptibility to NM I, and TNF-α−/−mice showed modest susceptibility. Disease caused by NM I in SCID, SCIDbg, and nude mice progressed slowly, while disease in IFN-γ−/−and TNF-α−/−mice advanced rapidly. B- and NK-cell deficiencies did not enhance clinical disease development or alter bacterial clearance but did increase the severity of histopathological changes, particularly in the absence of B cells. Mice infected with NM II showed no apparent clinical disease, but T-cell-deficient mice had histopathological changes. These results suggest that T cells are critical for clearance ofC. burnetii, either NM I or NM II, that IFN-γ and TNF-α are essential for the early control of infection, and that B cells are important for the prevention of tissue damage.
The Cytotoxic Necrotizing Factors from
Yersinia pseudotuberculosis
and from
Escherichia coli
Bind to Different Cellular Receptors but Take the Same Route to the Cytosol
Authors: Blumenthal Britta , Hoffmann Claudia , Aktories Klaus , Backert Steffen , Schmidt Gudula 
Published: April 2007

ABSTRACT

The cytotoxic necrotizing factors CNF1 and CNF2 produced by pathogenic
Escherichia coli
strains and CNF
Y
of
Yersinia pseudotuberculosis
constitutively activate small GTPases of the Rho family. They deamidate a glutamine (Gln63 in RhoA), which is crucial for GTP hydrolysis. CNF1 and CNF
Y
exhibit 61% identity on the amino acid level, with equal distribution over the whole molecule. Although the two toxins are homologous in the receptor binding domain, we show that they bind to different cellular receptors. CNF
Y
does not enter Caco-2 and CHO-K1 cells, which are responsive to CNF1. In contrast, HeLa, Hep-2, and HEK 293 cells do respond to both toxins. Competition studies with catalytically inactive mutants of the toxins revealed that binding of CNF1 has no influence on the uptake of CNF
Y
into HeLa cells. In contrast, uptake of CNF1 is retarded after preincubation of HeLa cells with the catalytically inactive mutant of CNF
Y
, suggesting that the toxin receptors overlap. Moreover, we compared the pathways of the toxins from receptor binding into the cytosol and showed that both toxins are taken up independent of the presence of clathrin or lipid rafts and are released into the cytosol from acidified endosomes.
A Functional NADPH Oxidase Prevents Caspase Involvement in the Clearance of Phagocytic Neutrophils
Authors: Wilkie Rachel P. , Vissers Margret C. M. , Dragunow Mike , Hampton Mark B. 
Published: April 2007

ABSTRACTNeutrophils play a prominent role in host defense. Phagocytosis of bacteria leads to the formation of an active NADPH oxidase complex that generates reactive oxygen species for bactericidal purposes. A critical step in the resolution of inflammation is the uptake of neutrophils by macrophages; however, there are conflicting reports on the mechanisms leading to the apoptosis of phagocytic neutrophils. The aim of this study was to clarify the role of effector caspases in these processes. Caspase activity was measured by DEVDase activity assays or immunofluorescence detection of active caspase-3. With normal human and wild-type murine neutrophils there was no caspase activation following phagocytosis ofStaphylococcus aureus. However, caspase activity was observed in phagocytic neutrophils with a defective NADPH oxidase, including neutrophils isolated from X-linked gp91phoxknockout chronic granulomatous disease mice. These results indicate that a functional NADPH oxidase and the generation of oxidants in the neutrophil phagosome prevent the activation of the cytoplasmic caspase cascade.
SV40 Oncoproteins Enhance Asbestos-Induced DNA Double-Strand Breaks and Abrogate Senescence in Murine Mesothelial Cells
Authors: Pietruska Jodie R. , Kane Agnes B. 
Published: April 2007

Abstract
SV40 virus has emerged as a potential cofactor with asbestos in the development of diffuse malignant mesothelioma, but its precise role in the pathogenesis of this tumor is unclear. SV40 large T antigen is known to inactivate cellular proteins involved in DNA damage and senescence, including p53 and pRb. We hypothesize that SV40 oncoproteins will sensitize mesothelial cells to DNA damage induced by asbestos or chemotherapeutic agents. SV40 oncoprotein expression in murine mesothelial cell lines enhanced spontaneous and asbestos-induced double-strand breaks, indicated by γ-H2AX foci, and potentiated micronucleus formation. Mesothelial cells exposed to asbestos or bleomycin for 96 h acquired senescent-like morphology and displayed elevated senescence-associated β-galactosidase activity, reduced bromodeoxyuridine (BrdUrd) incorporation, and reduced colony formation. SV40 oncoprotein expression abrogated the senescent phenotype, and transfected cell lines showed an increase in both BrdUrd incorporation and colony formation after prolonged DNA damage. Murine mesothelial cell lines lacking wild-type p53 due to a point mutation or gene rearrangement also failed to senesce in response to asbestos or chemotherapeutic agents. In addition, stress-induced senescence in human mesothelial cell lines was impaired by SV40 oncoprotein expression (MeT-5A), p53 small interfering RNA, or spontaneous p53 mutation (REN). These studies suggest that exposure to DNA-damaging agents can induce senescence in both murine and human mesothelioma cell lines and suggest a major, although not exclusive, role for p53 in this response. SV40 virus may contribute to mesothelioma progression by impairing stress-induced senescence, in part through p53 inactivation, thereby favoring survival and proliferation of mesothelial cells that have sustained DNA damage. [Cancer Res 2007;67(8):3637–45]
Characterization of a Germ-Line Deletion, Including the Entire INK4/ARF Locus, in a Melanoma-Neural System Tumor Family: Identification of ANRIL, an Antisense Noncoding RNA Whose Expression Coclusters with ARF
Authors: Pasmant Eric , Laurendeau Ingrid , Héron Delphine , Vidaud Michel , Vidaud Dominique , Bièche Ivan 
Published: April 2007

Abstract
We have previously detected a large germ-line deletion, which included the entire p15/CDKN2B-p16/CDKN2A-p14/ARF gene cluster, in the largest melanoma-neural system tumor (NST) syndrome family known to date by means of heterozygosity mapping based on microsatellite markers. Here, we used gene dose mapping with sequence-tagged site real-time PCR to locate the deletion end points, which were then precisely characterized by means of long-range PCR and nucleotide sequencing. The deletion was exactly 403,231 bp long and included the entire p15/CDKN2B, p16/CDKN2A, and p14/ARF genes. We then developed a simple and rapid assay to detect the junction fragment and to serve as a direct predictive DNA test for this large French family. We identified a new large antisense noncoding RNA (named ANRIL) within the 403-kb germ-line deletion, with a first exon located in the promoter of the p14/ARF gene and overlapping the two exons of p15/CDKN2B. Expression of ANRIL mainly coclustered with p14/ARF both in physiologic (various normal human tissues) and in pathologic conditions (human breast tumors). This study points to the existence of a new gene within the p15/CDKN2B-p16/CDKN2A-p14/ARF locus putatively involved in melanoma-NST syndrome families and in melanoma-prone families with no identified p16/CDKN2A mutations as well as in somatic tumors. [Cancer Res 2007;67(8):3963–9]
Expression of Tumor-Associated Differentiation Antigens, MUC1 Glycoforms and CEA, in Human Thymic Epithelial Cells: Implications for Self-Tolerance and Tumor Therapy
Authors: Cloosen Silvie , Arnold Janna , Thio Marco , Bos Gerard M.J. , Kyewski Bruno , Germeraad Wilfred T.V. 
Published: April 2007

AbstractExpression of tissue-restricted self-antigens in the thymus, termed promiscuous gene expression, imposes T cell tolerance and protects from autoimmune diseases. This antigen pool also includes various types of tumor-associated antigens (TAA) previously thought to be secluded from the immune system. The scope of promiscuous gene expression has been defined by mRNA analysis at the global level of isolated medullary thymic epithelial cells (mTECs). Information at the protein level on the frequency of mTECs expressing a given antigen, on coexpression patterns, and post-translational modifications is largely missing. We report here promiscuous expression at the protein level of two TAA, MUC1 and CEA, in situ and in purified human mTECs. Both antigens are expressed in 1% to 3% of mTECs, either individually or coexpressed in the same cell. Using a panel of anti-MUC1 monoclonal antibodies recognizing different post-translational modifications, i.e., glycoforms of MUC1, we show that only fully glycosylated forms of MUC1 and the differentiation-dependent glycoforms were detected on mTECs, but not the cancer-associated glycoforms. Our findings imply that MUC1 and CEA are amenable to central tolerance induction, which might, however, be incomplete in case of tumor cell–restricted MUC1 glycoforms. Knowledge of these subtleties in promiscuous gene expression may, in the future, assist the selection of T cell tumor vaccines for clinical trials. [Cancer Res 2007;67(8):3919–26]
Shared MHC Class II–Dependent Melanoma Ribosomal Protein L8 Identified by Phage Display
Authors: Swoboda Rolf K. , Somasundaram Rajasekharan , Caputo Laura , Ochoa Elizabeth M. , Gimotty Phyllis A. , Marincola Francesco M. , Van Belle Patricia , Barth Stephen , Elder David , Guerry DuPont , Czerniecki Brian , Schuchter Lynn , Vonderheide Robert H. , Herlyn Dorothee 
Published: April 2007

AbstractAntigens recognized by T helper (Th) cells in the context of MHC class II molecules have vaccine potential against cancer and infectious agents. We have described previously a melanoma patient's HLA-DR7–restricted Th cell clone recognizing an antigen, which is shared among melanoma and glioma cells derived from various patients. Here, this antigen was cloned using a novel antigen phage display approach. The antigen was identified as the ribosomal protein L8 (RPL8). A peptide of RPL8 significantly stimulated proliferation and/or cytokine expression of the Th cell clone and lymphocytes in four of nine HLA-DR7+ melanoma patients but not in healthy volunteers. The RPL8 antigen may represent a relevant vaccine target for patients with melanoma, glioma, and breast carcinoma whose tumors express this protein. [Cancer Res 2007;67(8):3555–9]
Proteomic Analysis of Waldenstrom Macroglobulinemia
Authors: Hatjiharissi Evdoxia , Ngo Hai , Leontovich Alexey A. , Leleu Xavier , Timm Michael , Melhem Mona , George Diane , Lu Ganwei , Ghobrial Joanna , Alsayed Yazan , Zeismer Steven , Cabanela Miguel , Nehme Alex , Jia Xiaoying , Moreau Anne Sophie , Treon Steven P. , Fonseca Rafael , Gertz Morie A. , Anderson Kenneth C. , Witzig Thomas E. , Ghobrial Irene M. 
Published: April 2007

Abstract
To better understand the molecular changes that occur in Waldenstrom macroglobulinemia (WM), we employed antibody-based protein microarrays to compare patterns of protein expression between untreated WM and normal bone marrow controls. Protein expression was defined as a &gt;2-fold or 1.3-fold change in at least 67% of the tumor samples. Proteins up-regulated by &gt;2-fold included Ras family proteins, such as Rab-4 and p62DOK, and Rho family proteins, such as CDC42GAP and ROKα. Other proteins up-regulated by &gt;1.3-fold included cyclin-dependent kinases, apoptosis regulators, and histone deacetylases (HDAC). We then compared the samples of patients with symptomatic and asymptomatic WM and showed similar protein expression signatures, indicating that the dysregulation of signaling pathways occurs early in the disease course. Three proteins were different by &gt;2-fold in symptomatic versus asymptomatic, including the heat shock protein HSP90. Elevated protein expression was confirmed by immunohistochemistry and immunoblotting. Functional significance was validated by the induction of apoptosis and inhibition of proliferation using specific HDAC and HSP90 inhibitors. This study, therefore, identifies, for the first time, multiple novel proteins that are dysregulated in WM, which both enhance our understanding of disease pathogenesis and represent targets of novel therapeutics. [Cancer Res 2007;67(8):3777–8]