bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal and host‐related variation in frequencies of genes that enable Phyllotreta nemorum to utilize a novel host plant, Barbarea vulgaris
Authors: Nielsen Jens K. , De Jong Peter W. 
Published: April 2005

AbstractThe flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae), is an intermediate specialist feeding on a small number of plants within the family Brassicaceae. The most commonly used host plant is Sinapis arvensis L., whereas the species is found more rarely on Cardaria draba (L.) Desv., Barbarea vulgaris R.Br., and cultivated radish (Raphanus sativus L.). The interaction between flea beetles and Barbarea vulgaris ssp. arcuata (Opiz.) Simkovics seems to offer a good opportunity for experimental studies of coevolution. The plant is polymorphic, as it contains one type (the P‐type) that is susceptible to all flea beetle genotypes, and another type (the G‐type) that is resistant to some genotypes. At the same time, the flea beetle is also polymorphic, as some genotypes can utilize the G‐type whereas others cannot. The ability to utilize the G‐type of B. vulgaris ssp. arcuata is controlled by major dominant genes (R‐genes). The present investigation measured the frequencies of flea beetles with R‐genes in populations living on different host plants in 2 years (1999 and 2003). Frequencies of beetles with R‐genes were high in populations living on the G‐type of B. vulgaris ssp. arcuata in both years. Frequencies of beetles with R‐genes were lower in populations living on other host plants, and declining frequencies were observed in five out of six populations living on S. arvensis. Selection in favour of R‐genes in populations living on B. vulgaris is the most likely mechanism to account for the observed differences in the relative abundance of R‐genes in flea beetle populations utilizing different host plants. A geographic mosaic with differential levels of interactions between flea beetles and their host plants was demonstrated.
Diffusion Tensor Imaging of the Brain: Background and Review of Clinical Applications
Authors: Sundgren P. C. 
Published: April 2005

SummaryThis article reviews the basic theoretical background to diffusion tensor imaging (DTI) and some of the common clinical applications of DTI as of today such as cerebral ischaemia, brain maturation, ageing and cognitive impairment. The value of DTI in the work‐up of brain tumours, as a tool in the differentiation of radiation injury versus recurrent tumour, and in brain injury is reviewed. The potential use of this technique in diseases such as epilepsy, multiple sclerosis, Alzheimer's disease and metabolic disorders is also briefly reviewed.
Survival and Replication of Clinical
Mycobacterium tuberculosis
Isolates in the Context of Human Innate Immunity
Authors: Janulionis Ernestas , Sofer Carolina , Schwander Stephan K. , Nevels Denarra , Kreiswirth Barry , Shashkina Elena , Wallis Robert S. 
Published: April 2005

ABSTRACT

The initial host response to
Mycobacterium tuberculosis
is driven by innate immunity. For this study, we examined the ability of 18 recent clinical isolates and 5 reference strains to survive and replicate in the context of host innate immunity by using whole blood culture. Six healthy tuberculin-negative volunteers served as subjects. H
37
Ra showed the least capacity to replicate of any of the strains tested, decreasing in viability 1.3 log CFU during 72 h of whole blood culture, whereas H
37
Rv increased 0.32 log. Clinical isolates varied greatly in their ability to replicate in blood cells, ranging from −0.4 to +0.8 log (
P
< 0.001). Four showed significantly more growth than H
37
Rv, and one showed significantly reduced growth. Host mechanisms for restricting intracellular mycobacterial growth were more effective during the first 24 h of whole blood culture than during the 24- to 72-h period. Certain mycobacterial isolates appeared preferentially able to withstand host defenses during each of these intervals. Although there was relatively more homogeneity among subjects than among strains, one of the six subjects showed a reduced capacity to restrict intracellular mycobacterial growth due to a defect expressed during the first 24 h of culture. Our findings indicate substantial variability in the capacity of clinical tuberculosis isolates to replicate in host cells in the face of innate host immunity.
Molecular Cloning and Characterization of Three β-Defensins from Canine Testes
Authors: Sang Yongming , Ortega M. Teresa , Blecha Frank , Prakash Om , Melgarejo Tonatiuh 
Published: April 2005

ABSTRACTMammalian β-defensins are small cationic peptides possessing broad antimicrobial and physiological activities. Because dogs are particularly resilient to sexually transmitted diseases, it has been proposed that their antimicrobial peptide repertoire might provide insight into novel antimicrobial therapeutics and treatment regimens. To investigate this proposal, we cloned the full-length cDNA of three canine β-defensin isoforms (cBD-1,-2, and-3) from canine testicular tissues. Their predicted peptides share identical N-terminal 65-amino-acid residues, including the β-defensin consensus six-cysteine motif. The two longer isoforms,cBD-2and-3, possess 4 and 34 additional amino acids, respectively, at the C terminus. To evaluate the antimicrobial activity of cBD, a 34-amino-acid peptide derived from the shared mature peptide region was synthesized. Canine β-defensin displayed broad antimicrobial activity against gram-positive bacteria (Listeria monocytogenesandStaphylococcus aureus; MICs of 6 and 100 μg/ml, respectively), gram-negative bacteria (Escherichia coli,Klebsiella pneumoniae, andNeisseria gonorrhoeae; MICs of 20 to 50, 20, and 50 μg/ml, respectively), and yeast (Candida albicans; MIC of 5 to 50 μg/ml) and lower activity againstUreaplasma urealyticumandU. canigenitalium(MIC of 200 μg/ml). Antimicrobial potency was significantly reduced at salt concentrations higher than 140 mM. All three canine β-defensins were highly expressed in testis. In situ hybridization indicated thatcBD-1was expressed primarily in Sertoli cells within the seminiferous tubules. In contrast,cBD-2was located primarily within Leydig cells. The longest isoform,cBD-3, was detected in Sertoli cells and to a lesser extent in the interstitium. The tissue-specific expression and broad antimicrobial activity suggest that canine β-defensins play an important role in host defense and other physiological functions of the male reproductive system.
Intranasal Vaccination Induces Protective Immunity against Intranasal Infection with VirulentFrancisella tularensisBiovar A
Authors: Wu Terry H. , Hutt Julie A. , Garrison Kristin A. , Berliba Lyudmila S. , Zhou Yan , Lyons C. Rick 
Published: April 2005

ABSTRACTThe inhalation ofFrancisella tularensisbiovar A causes pneumonic tularemia associated with high morbidity and mortality rates in humans. Exposure toF. tularensisusually occurs by accident, but there is increasing awareness thatF. tularensismay be deliberately released in an act of bioterrorism or war. The development of a vaccine against pneumonic tularemia has been limited by a lack of information regarding the mechanisms required to protect against this disease. Vaccine models forF. tularensisin inbred mice would facilitate investigations of the protective mechanisms and significantly enhance vaccine development. Intranasal vaccination with the attenuated live vaccine strain (LVS) ofF. tularensisreproducibly protected BALB/c mice, but not C57BL/6 mice, against intranasal and subcutaneous challenges with a virulent clinical isolate ofF. tularensisbiovar A (NMFTA1). The resistance of LVS-vaccinated BALB/c mice to intranasal NMFTA1 challenge was increased 100-fold by boosting with live NMFTA1 but not with LVS. The protective response was specific forF. tularensisand required both CD4 and CD8 T cells. The vaccinated mice appeared outwardly healthy for more than 2 months after NMFTA1 challenge, even though NMFTA1 was recovered from more than half of the vaccinated mice. These results show that intranasal vaccination induces immunity that protects BALB/c mice from intranasal infection byF. tularensisbiovar A.
Use of In Vivo-Induced Antigen Technology for Identification of
Escherichia coli
O157:H7 Proteins Expressed during Human Infection
Authors: John Manohar , Kudva Indira T. , Griffin Robert W. , Dodson Allen W. , McManus Bethany , Krastins Bryan , Sarracino David , Progulske-Fox Ann , Hillman Jeffrey D. , Handfield Martin , Tarr Phillip I. , Calderwood Stephen B. 
Published: April 2005

ABSTRACT

Using in vivo-induced antigen technology (IVIAT), a modified immunoscreening technique that circumvents the need for animal models, we directly identified immunogenic
Escherichia coli
O157:H7 (O157) proteins expressed either specifically during human infection but not during growth under standard laboratory conditions or at significantly higher levels in vivo than in vitro. IVIAT identified 223 O157 proteins expressed during human infection, several of which were unique to this study. These in vivo-induced (ivi) proteins, encoded by ivi genes, mapped to the backbone, O islands (OIs), and pO157. Lack of in vitro expression of O157-specific ivi proteins was confirmed by proteomic analysis of a mid-exponential-phase culture of
E. coli
O157 grown in LB broth. Because ivi proteins are expressed in response to specific cues during infection and might help pathogens adapt to and counter hostile in vivo environments, those identified in this study are potential targets for drug and vaccine development. Also, such proteins may be exploited as markers of O157 infection in stool specimens.
PavA ofStreptococcus pneumoniaeModulates Adherence, Invasion, and Meningeal Inflammation
Authors: Pracht Daniela , Elm Christine , Gerber Joachim , Bergmann Simone , Rohde Manfred , Seiler Marleen , Kim Kwang S. , Jenkinson Howard F. , Nau Roland , Hammerschmidt Sven 
Published: April 2005

ABSTRACTPneumococcal adherence and virulence factor A (PavA) is displayed to the cell outer surface ofStreptococcus pneumoniaeand mediates pneumococcal binding to immobilized fibronectin. PavA, which lacks a typical gram-positive signal sequence and cell surface anchorage motif, is essential for pneumococcal virulence in a mouse infection model of septicemia. In this report the impact of PavA on pneumococcal adhesion to and invasion of eukaryotic cells and on experimental pneumococcal meningitis was investigated. In the experimental mouse meningitis model, the virulence of thepavAknockout mutant ofS. pneumoniaeD39, which did not show alterations of subcellular structures as indicated by electron microscopic studies, was strongly decreased. Pneumococcal strains deficient in PavA showed substantially reduced adherence to and internalization of epithelial cell lines A549 and HEp-2. Similar results were obtained with human brain-derived microvascular endothelial cells and human umbilical vein-derived endothelial cells. Attachment and internalization of pneumococci were not significantly affected by preincubation or cocultivations of pneumococci with anti-PavA antisera. Pneumococcal adherence was also not significantly affected by the addition of PavA protein. Complementation of thepavAknockout strain with exogenously added PavA polypeptide did not restore adherence of the mutant. These data suggest that PavA affects pneumococcal colonization by modulating expression or function of important virulence determinants ofS. pneumoniae.
Pneumocystis cariniiActivates the NF-κB Signaling Pathway in Alveolar Epithelial Cells
Authors: Wang Jing , Gigliotti Francis , Maggirwar Sanjay , Johnston Carl , Finkelstein Jacob N. , Wright Terry W. 
Published: April 2005

ABSTRACTPneumocystis cariniipneumonia (PcP) is a clinically important infection of immunocompromised patients. Although the interaction ofPneumocystiswith the alveolar epithelium has been well documented, very little information regarding the epithelial response toPneumocystisis currently available. In order to studyPneumocystis-epithelium interactions, a murine cell line derived specifically from an alveolar epithelial cell (AEC) was utilized. The coculture of murine AECs with mousePneumocystisinduced a dose- and time-dependent release of the CXC chemokine MIP-2. Importantly, the specific removal ofPneumocystisfrom the preparation, or the pretreatment of AECs with sulfasalazine, a potent and specific inhibitor of NF-κB, nearly completely abrogated the chemokine response toPneumocystis. Since the murine MIP-2 promoter contains consensus κB binding sequences, the ability ofPneumocystisto stimulate NF-κB signaling in AECs was examined.Pneumocystisstimulation of an AEC line stably transfected with a κB-dependent reporter construct triggered the NF-κB signaling pathway and reporter production. These data were confirmed in gel shift assays, providing direct evidence thatPneumocystisinduced the nuclear translocation of the p50/p65 heterodimeric form of NF-κB. Maximal NF-κB activation was dependent upon direct contact with viablePneumocystisorganisms. These data demonstrate thatPneumocystisactivates NF-κB signaling in AECs and establish a reporter cell line for studying NF-κB activation in AECs. Given the global regulatory functions of the NF-κB family, these findings suggest thatPneumocystisdirectly alters AEC gene expression in a manner that promotes pulmonary immune and inflammatory responses.
Cross-Reactive Surface Epitopes on Chondroitin Sulfate A-AdherentPlasmodium falciparum-Infected Erythrocytes Are Associated with Transcription ofvar2csa
Authors: Elliott Salenna R. , Duffy Michael F. , Byrne Timothy J. , Beeson James G. , Mann Emily J. , Wilson Danny W. , Rogerson Stephen J. , Brown Graham V. 
Published: April 2005

ABSTRACTMalaria in pregnancy is associated with placental accumulation ofPlasmodium falciparum-infected erythrocytes (IE) that adhere to chondroitin sulfate A (CSA). Adhesion is mediated byP. falciparumerythrocyte membrane protein 1 (PfEMP1), a variant parasite protein expressed on the surface of IE and encoded byvargenes. Rabbit antiserum was generated against the CSA-adherentP. falciparumline CS2, in which the dominantvartranscribed isvar2csa, a relatively conservedvargene that has been associated with CSA adhesion. Anti-CS2 recognized genetically distinct CSA-adherentP. falciparumlines but not CD36-adherent parent lines. Reactivity with anti-CS2 correlated with the level of adhesion to CSA. Fluorescence-activated cell sorting according to binding of anti-CS2 showed reactivity was associated with CSA adhesion and transcription ofvar2csa. These data are consistent with the hypothesis thatvar2csaencodes a PfEMP1 expressed on the surface of IE, which mediates adhesion to CSA and is relatively conserved between genetically distinct strains ofP. falciparum.
Effects of Oligopeptide Permease in Group A Streptococcal Infection
Authors: Wang Chih-Hung , Lin Chia-Yu , Luo Yueh-Hsia , Tsai Pei-Jane , Lin Yee-Shin , Lin Ming T. , Chuang Woei-Jer , Liu Ching-Chuan , Wu Jiunn-Jong 
Published: April 2005

ABSTRACTThe oligopeptide permease (Opp) of group A streptococci (GAS) is a membrane-associated protein and belongs to the ATP-binding cassette transporter family. It is encoded by a polycistronic operon containingoppA,oppB,oppC,oppD, andoppF. The biological function of these genes in GAS is poorly understood. In order to understand more about the effects of Opp on GAS virulence factors, anoppAisogenic mutant was constructed by using an integrative plasmid to disrupt theoppoperon and confirmed by Southern blot hybridization. No transcript was detected in theoppAisogenic mutant by Northern blot analysis and reverse transcriptase PCR. The growth curve for theoppAisogenic mutant was similar to that for wild-type strain A-20. TheoppAisogenic mutant not only decreased the transcription ofspeB,speX, androfAbut also increased the transcription ofspeF,sagA(streptolysin S-associated gene A),slo(streptolysin O),pel(pleotrophic effect locus), anddppA(dipeptide permease). No effects on the transcription ofemm,sda,speJ,speG,rgg, andcsrRwere found. The phenotypes of theoppAmutant were restored by theoppArevertant and by the complementation strain. TheoppAmutant caused less mortality and tissue damage than the wild-type strain when inoculated into BALB/c mice via an air pouch. Based on these data, we suggest that theoppoperon plays an important role in the pathogenesis of GAS infection.
Characterization of the Major Secreted Zinc Metalloprotease- Dependent Glycerophospholipid:Cholesterol Acyltransferase, PlaC, of
Legionella pneumophila
Authors: Banerji Sangeeta , Bewersdorff Mayte , Hermes Björn , Cianciotto Nicholas P. , Flieger Antje 
Published: April 2005

ABSTRACT

Legionella pneumophila
, an intracellular pathogen causing a severe pneumonia, possesses distinct lipolytic activities which have not been completely assigned to specific enzymes so far. We cloned and characterized a gene,
plaC
, encoding a protein with high homology to PlaA, the major secreted lysophospholipase A of
L. pneumophila
and to other hydrolytic enzymes belonging to the GDSL family. Here we show that
L. pneumophila plaC
mutants possessed reduced phospholipase A and lysophospholipase A activities and lacked glycerophospholipid:cholesterol acyltransferase activity in their culture supernatants. The mutants' reduced phospholipase A and acyltransferase activities were complemented by reintroduction of an intact copy of
plaC
. Additionally,
plaC
conferred increased lysophospholipase A and glycerophospholipid:cholesterol acytransferase activities to recombinant
Escherichia coli
. Furthermore, PlaC was shown to be another candidate exported by the
L. pneumophila
type II secretion system and was activated by a factor present in the bacterial culture supernatant dependent on the zinc metalloprotease. Finally, the role of
plaC
in intracellular infection of
Acanthamoeba castellanii
and U937 macrophages with
L. pneumophila
was assessed, and
plaC
was found to be dispensable. Thus,
L. pneumophila
possesses another secreted lipolytic enzyme, a protein with acyltransferase, phospholipase A, and lysophospholipase A activities. This enzyme is distinguished from the previously characterized phospholipases A and lysophospholipases A by its capacity not only to cleave fatty acids from lipids but to transfer them to cholesterol. Cholesterol is an important compound of eukaryotic membranes, and an acyltransferase might be a tool for host cell modification to fit the needs of the bacterium.
Escherichia coli
K1 RS218 Interacts with Human Brain Microvascular Endothelial Cells via Type 1 Fimbria Bacteria in the Fimbriated State
Authors: Teng Ching-Hao , Cai Mian , Shin Sooan , Xie Yi , Kim Kee-Jun , Khan Naveed Ahmed , Di Cello Francescopaolo , Kim Kwang Sik 
Published: April 2005

ABSTRACT

Escherichia coli
K1 is a major gram-negative organism causing neonatal meningitis.
E. coli
K1 binding to and invasion of human brain microvascular endothelial cells (HBMEC) are a prerequisite for
E. coli
penetration into the central nervous system in vivo. In the present study, we showed using DNA microarray analysis that
E. coli
K1 associated with HBMEC expressed significantly higher levels of the
fim
genes compared to nonassociated bacteria. We also showed that
E. coli
K1 binding to and invasion of HBMEC were significantly decreased with its
fimH
deletion mutant and type 1 fimbria locked-off mutant, while they were significantly increased with its type 1 fimbria locked-on mutant.
E. coli
K1 strains associated with HBMEC were predominantly type 1 fimbria phase-on (i.e., fimbriated) bacteria. Taken together, we showed for the first time that type 1 fimbriae play an important role in
E. coli
K1 binding to and invasion of HBMEC and that type 1 fimbria phase-on
E. coli
is the major population interacting with HBMEC.
Extracellular Carbohydrate-Containing Polymers of a Model Biofilm-Producing Strain,
Staphylococcus epidermidis
RP62A
Authors: Sadovskaya Irina , Vinogradov Evgueny , Flahaut Sigrid , Kogan Grigorij , Jabbouri Saïd 
Published: April 2005

ABSTRACT

Staphylococcus aureus
and coagulase-negative staphylococci, primarily
Staphylococcus epidermidis
, are recognized as a major cause of nosocomial infections associated with the use of implanted medical devices. It has been established that clinical isolates often produce a biofilm, which is involved in adherence to biomaterials and provides enhanced resistance of bacteria against host defenses and antibiotic treatments. It has been thought that the staphylococcal biofilm contains two polysaccharides, one responsible for primary cell adherence to biomaterials (polysaccharide/adhesin [PS/A]) and an antigen that mediates bacterial aggregation (polysaccharide intercellular adhesin [PIA]). In the present paper we present an improved procedure for preparation of PIA that conserves its labile substituents and avoids contamination with by-products. Based on structural analysis of the polysaccharide antigens and a thorough overview of the previously published data, we concluded that PIA from
S. epidermidis
is structurally identical to the recently described poly-β-(1→6)-
N
-acetylglucosamine from PS/A-overproducing strain
S. aureus
MN8m. We also show that another carbohydrate-containing polymer, extracellular teichoic acid (EC TA), is an essential component of
S. epidermidis
RP62A biofilms. We demonstrate that the relative amounts of extracellular PIA and EC TA produced depend on the growth conditions. Moderate shaking or static culture in tryptic soy broth favors PIA production, while more EC TA is produced in brain heart infusion medium.