bluuebunny/crossref_metadata_2025_split huggingface dataset:
Both Decorin-Binding Proteins A and B Are Critical for the Overall Virulence of
Borrelia burgdorferi
Authors: Shi Yanlin , Xu Qilong , McShan Kristy , Liang Fang Ting 
Published: January 2008

ABSTRACT

Both decorin-binding proteins (DbpA and DbpB) of the Lyme disease spirochete
Borrelia burgdorferi
bind decorin and glycosaminoglycans, two important building blocks of proteoglycans that are abundantly found in the extracellular matrix (ECM) and connective tissues as well as on cell surfaces of mammals. As an extracellular pathogen,
B. burgdorferi
resides primarily in the ECM and connective tissues and between host cells during mammalian infection. The interactions of
B. burgdorferi
with these host ligands mediated by DbpA and DbpB potentially influence various aspects of infection. Here, we show that both DbpA and DbpB are critical for the overall virulence of
B. burgdorferi
in the murine host. Disruption of the
dbpBA
locus led to nearly a 10
4
-fold increase in the 50% infectious dose (ID
50
). Complementation of the mutant with either
dbpA
or
dbpB
reduced the ID
50
from over 10
4
to roughly 10
3
organisms. Deletion of the
dbpBA
locus affected colonization in all tissues of infected mice. The lack of
dbpA
alone precluded the pathogen from colonizing the heart tissue, and
B. burgdorferi
deficient for DbpB was recovered only from 42% of the heart specimens of infected mice. Although
B. burgdorferi
lacking either
dbpA
or
dbpB
was consistently grown from joint specimens of almost all infected mice, it generated bacterial loads significantly lower than the control. The deficiency in either DbpA or DbpB did not reduce the bacterial load in skin, but lack of both significantly did. Taken together, the study results indicate that neither DbpA nor DbpB is essential for mammalian infection but that both are critical for the overall virulence of
B. burgdorferi
.
Detection of
Bacillus anthracis
Spore Germination In Vivo by Bioluminescence Imaging
Authors: Sanz Patrick , Teel Louise D. , Alem Farhang , Carvalho Humberto M. , Darnell Stephen C. , O'Brien Alison D. 
Published: January 2008

ABSTRACT

We sought to visualize the site of
Bacillus anthracis
spore germination in vivo. For that purpose, we constructed a reporter plasmid with the
lux
operon under control of the spore small acid-soluble protein B (
sspB
) promoter. In
B. subtilis
,
sspB
-driven synthesis of luciferase during sporulation results in incorporation of the enzyme in spores. We observed that
B. anthracis
Sterne transformed with our
sspBp
::
lux
plasmid was only luminescent during germination. In contrast, Sterne transformed with a similarly constructed plasmid with
lux
expression under control of the protective antigen promoter displayed luminescence only during vegetative growth. We then infected A/J mice intranasally with spores that harbored the germination reporter. Mice were monitored for up to 14 days with the Xenogen In Vivo Imaging System. While luminescence only became evident in live animals at 18 h, dissection after sacrificing infected mice at earlier time points revealed luminescence in lung tissue at 30 min after intranasal infection. Microscopic histochemical and immunofluorescence studies on luminescent lung sections and imprints revealed that macrophages were the first cells in contact with the
B. anthracis
spores. By 6 h after infection, polymorphonuclear leukocytes with intracellular spores were evident in the alveolar spaces. After 24 h, few free spores were observed in the alveolar spaces; most of the spores detected by immunofluorescence were in the cytoplasm of interstitial macrophages. In contrast, mediastinal lymph nodes remained nonluminescent throughout the infection. We conclude that in this animal system, the primary site of
B. anthracis
spore germination is the lungs.
Burkholderia cenocepacia
Requires the RpoN Sigma Factor for Biofilm Formation and Intracellular Trafficking within Macrophages
Authors: Saldías M. Soledad , Lamothe Julie , Wu Robert , Valvano Miguel A. 
Published: January 2008

ABSTRACT

Chronic respiratory infections by
Burkholderia cenocepacia
in cystic fibrosis patients are associated with increased morbidity and mortality, but virulence factors determining the persistence of the infection in the airways are not well characterized. Using a chronic pulmonary infection model, we previously identified an attenuated mutant with an insertion in a gene encoding an RpoN activator protein, suggesting that RpoN and/or components of the RpoN regulon play a role in
B. cenocepacia
virulence. In this study, we demonstrate that a functional
rpoN
gene is required for bacterial motility and biofilm formation in
B. cenocepacia
K56-2. Unlike other bacteria, RpoN does not control flagellar biosynthesis, as evidenced by the presence of flagella in the
rpoN
mutant. We also demonstrate that, in macrophages, the
rpoN
mutant is rapidly trafficked to lysosomes while intracellular wild-type
B. cenocepacia
localizes in bacterium-containing vacuoles that exhibit a pronounced delay in phagolysosomal fusion. Rapid trafficking to the lysosomes is also associated with the release of red fluorescent protein into the vacuolar lumen, indicating loss of bacterial cell envelope integrity. Although a role for RpoN in motility and biofilm formation has been previously established, this study is the first demonstration that the RpoN regulon in
B. cenocepacia
is involved in delaying phagolysosomal fusion, thereby prolonging bacterial intracellular survival within macrophages.
In Vivo Fate and Distribution of Poly-γ-
d
-Glutamic Acid, the Capsular Antigen from
Bacillus anthracis
Authors: Sutherland Marjorie D. , Thorkildson Peter , Parks Samuel D. , Kozel Thomas R. 
Published: January 2008

ABSTRACT

Bacillus anthracis
is surrounded by an antiphagocytic capsule composed of poly-γ-
d
-glutamic acid (γDPGA). Bacterial and fungal capsular polysaccharides are shed into body fluids in large amounts during infection. The goal of our study was to examine the in vivo fate and distribution of the γDPGA capsular polypeptide. Mice were injected via the intravenous route with various amounts of purified γDPGA. Blood, urine, and various organs were harvested at different times after treatment. Sites of γDPGA accumulation were determined by immunoassay using monoclonal antibodies specific for γDPGA. The results showed that the liver and spleen were the primary sites for the accumulation of γDPGA. As found in previous studies of capsular polysaccharides, the Kupffer cells of the liver and splenic macrophages were sites for the cellular accumulation of γDPGA. Unlike capsular polysaccharides, the hepatic sinusoidal endothelial cells were also sites for γDPGA accumulation. γDPGA was rapidly cleared from serum and was excreted into the urine. γDPGA in the urine showed a reduced molecular size relative to native γDPGA. The results indicate that in vivo clearance of the polypeptide capsular antigen of
B. anthracis
shares several features with the clearance of capsular polysaccharides. Key differences between the in vivo behaviors of γDPGA and capsular polysaccharides include the accumulation of γDPGA in hepatic sinusoidal endothelial cells and a γDPGA clearance rate that was more rapid than the clearance reported for capsular polysaccharides.
Role and Regulation of Iron-Sulfur Cluster Biosynthesis Genes in
Shigella flexneri
Virulence
Authors: Runyen-Janecky Laura , Daugherty Aaron , Lloyd Benjamin , Wellington Christopher , Eskandarian Haig , Sagransky Matthew 
Published: January 2008

ABSTRACT

Shigella flexneri
, a causative agent of bacterial dysentery, possesses two predicted iron-sulfur cluster biosynthesis systems called Suf and Isc.
S. flexneri
strains containing deletion mutations in the entire
suf
operon (UR011) or the
iscSUA
genes (UR022) were constructed. Both mutants were defective in surviving exposure to oxidative stress. The
suf
mutant showed growth that was comparable to that of the parental strain in both iron-replete and iron-limiting media; however, the
isc
mutant showed reduced growth, relative to the parental strain, in both media. Although the
suf
mutant formed wild-type plaques on Henle cell monolayers, the
isc
mutant was unable to form plaques on Henle cell monolayers because the strain was noninvasive. Expression from both the
suf
and
isc
promoters increased in iron-limiting media and in the presence of hydrogen peroxide. Iron repression of the
suf
promoter was mediated by Fur, and increased
suf
expression in iron-limiting media was enhanced by the presence of IscR. Iron repression of the
isc
promoter was mediated by IscR. Hydrogen peroxide-dependent induction of
suf
expression, but not
isc
expression, was mediated by OxyR. Furthermore, IscR was a positive regulator of
suf
expression in the presence of hydrogen peroxide and a negative regulator of
isc
expression in the absence of hydrogen peroxide. Expression from the
S. flexneri suf
and
isc
promoters increased when
Shigella
was within Henle cells, and our data suggest that the intracellular signal mediating this increased expression is reduced iron levels.
Development of
Galleria mellonella
as an Alternative Infection Model for the
Burkholderia cepacia
Complex
Authors: Seed Kimberley D. , Dennis Jonathan J. 
Published: January 2008

ABSTRACT

Burkholderia
is an important bacterial genus with a complex taxonomy that contains species of both ecological and pathogenic importance, including nine closely related species collectively termed the
Burkholderia cepacia
complex (BCC). In order to more thoroughly investigate the virulence of this bacterial complex of microorganisms, alternative infection models would be useful. To this end, we have adapted and developed the use of the
Galleria mellonella
wax moth larvae as a host for examining BCC infections. The experimental conditions affecting the BCC killing of the “wax worm” were optimized. BCC virulence levels were determined using 50% lethal doses, and differences were observed between both species and strains of the BCC. The BCC pathogenicity trends obtained compare favorably with results acquired using other published alternative infection models, as well as mammalian infection models. In addition, BCC killing activity was determined by directly measuring relative bacterial loads in three different BCC strains, thus demonstrating innate differences in BCC strain virulence. Finally, genetically mutated BCC strains were compared to a wild-type BCC strain in order to show concomitant reduction of BCC virulence and increased wax worm survival. For experimentation examining the virulent properties of the BCC, the wax worm has proven to be a useful alternative infection model.
Critical Involvement of Pneumolysin in Production of Interleukin-1α and Caspase-1-Dependent Cytokines in Infection withStreptococcus pneumoniaeIn Vitro: a Novel Function of Pneumolysin in Caspase-1 Activation
Authors: Shoma Shereen , Tsuchiya Kohsuke , Kawamura Ikuo , Nomura Takamasa , Hara Hideki , Uchiyama Ryosuke , Daim Sylvia , Mitsuyama Masao 
Published: January 2008

ABSTRACTPneumolysin is a pore-forming cytolysin known as a major virulence determinant ofStreptococcus pneumoniae. This protein toxin has also been shown to activate the Toll-like receptor 4 (TLR4) signaling pathway. In this study, a mutantS. pneumoniaestrain deficient in pneumolysin (Δply) and a recombinant pneumolysin protein (rPLY) were constructed. Upon infection of macrophages in vitro, the ability to induce the production of interleukin-1α (IL-1α), IL-1β, and IL-18 was severely impaired in the Δplymutant, whereas there was no marked difference in the induction of tumor necrosis factor alpha (TNF-α) and IL-12p40 between the wild type and the Δplymutant ofS. pneumoniae. When macrophages were stimulated with rPLY, the production of IL-1α, IL-1β, and IL-18 was strongly induced in a TLR4-dependent manner, whereas lipopolysaccharide, a canonical TLR4 agonist, hardly induced these cytokines. In contrast, lipopolysaccharide was more potent than rPLY in inducing the production of TNF-α, IL-6, and IL-12p40, the cytokines requiring no caspase activation. Activation of caspase-1 was observed in macrophages stimulated with rPLY but not in those stimulated with lipopolysaccharide, and the level of activation was higher in macrophages infected with wild-typeS. pneumoniaethan in those infected with the Δplymutant. These results clearly indicate that pneumolysin plays a key role in the host response toS. pneumoniae, particularly in the induction of caspase-1-dependent cytokines.
Host Airway Proteins Interact withStaphylococcus aureusduring Early Pneumonia
Authors: Ventura Christy L. , Higdon Roger , Kolker Eugene , Skerrett Shawn J. , Rubens Craig E. 
Published: January 2008

ABSTRACTStaphylococcus aureusis a major cause of hospital-acquired pneumonia and is emerging as an important etiological agent of community-acquired pneumonia. Little is known about the specific host-pathogen interactions that occur whenS. aureusfirst enters the airway. A shotgun proteomics approach was utilized to identify the airway proteins associated withS. aureusduring the first 6 h of infection. Host proteins eluted from bacteria recovered from the airways of mice 30 min or 6 h following intranasal inoculation under anesthesia were subjected to liquid chromatography and tandem mass spectrometry. A total of 513 host proteins were associated withS. aureus30 min and/or 6 h postinoculation. A majority of the identified proteins were host cytosolic proteins, suggesting thatS. aureuswas rapidly internalized by phagocytes in the airway and that significant host cell lysis occurred during early infection. In addition, extracellular matrix and secreted proteins, including fibronectin, antimicrobial peptides, and complement components, were associated withS. aureusat both time points. The interaction of 12 host proteins shown to bind toS. aureusin vitro was demonstrated in vivo for the first time. The association of hemoglobin, which is thought to be the primary staphylococcal iron source during infection, withS. aureusin the airway was validated by immunoblotting. Thus, we used our recently developedS. aureuspneumonia model and shotgun proteomics to validate previous in vitro findings and to identify nearly 500 other proteins that interact withS. aureusin vivo. The data presented here provide novel insights into the host-pathogen interactions that occur whenS. aureusenters the airway.
Toll-Like Receptor 5-Deficient Mice Have Dysregulated Intestinal Gene Expression and Nonspecific Resistance to
Salmonella
-Induced Typhoid-Like Disease
Authors: Vijay-Kumar Matam , Aitken Jesse D. , Kumar Amrita , Neish Andrew S. , Uematsu Satoshi , Akira Shizuo , Gewirtz Andrew T. 
Published: January 2008

ABSTRACT

The recognition of flagellin by Toll-like receptor 5 (TLR5) is the dominant means by which model intestinal epithelia activate proinflammatory gene expression in response to
Salmonella enterica
. The role of the flagellin-TLR5 interaction in vivo has been addressed primarily via studies that use flagellar mutants. Such studies suggest that host recognition of flagellin promotes rapid neutrophil recruitment that protects the host from this pathogen. However, these works do not directly address the role of TLR5 and are subject to the caveat that flagellar mutations may broadly affect
Salmonella
gene expression. Thus, we examined the role of the flagellin-TLR5 interaction via the use of TLR5-deficient (TLR5KO) mice. We utilized both the traditional model of murine
Salmonella
infection, wherein low-dose oral infection of mice with
Salmonella enterica
subsp.
enterica
serovar Typhimurium results in systemic typhoid-like disease, and a more recently characterized model in which mice are pretreated with streptomycin to result in gut-restricted acute enteritis. In the enteritis model, TLR5KO mice had more severe gut pathology, thus “phenocopying” previous results obtained with
Salmonella
mutants. In contrast, TLR5KO mice were resistant to
Salmonella
-induced typhoid-like disease. However, such resistance was not specific for flagellated serovar Typhimurium, but rather, TLR5KO mice were also resistant to challenges by flagellin-deficient serovar Typhimurium. Such resistance associated with elevations in the microbiota was ablated by antibiotic pretreatment and correlated with basal elevations in intestinal host defense gene expression. All together, these results indicate that the resistance of TLR5KO mice to
Salmonella
-induced typhoid-like illness resulted from alterations in their basal phenotype rather than from the lack of TLR5 ligation during the infection per se.
SIMULATION OF DEMOGRAPHIC CHANGE IN PALESTINIAN TERRITORIES
Authors: SUMOUR M. A. , El-ASTAL A. H. , SHABAT M. M. , RADWAN M. A. 
Published: January 2008

Mortality, birth rates and retirement play a major role in demographic changes. In most cases, mortality rates decreased in the past century without noticeable decrease in fertility rates, leading to a significant increase in population growth. In many poor countries like Palestinian Territories the number of births has fallen and the life expectancy increased. In this paper we concentrate on measuring, analyzing and extrapolating the age structure in Palestine a few decades ago into the future. A Fortran program has been designed and used for the simulation and analysis of our statistical data. This study of demographic change in Palestine has shown that Palestinians will have in future problems as the strongest age cohorts are the above-60-year olds. We therefore recommend the increase of both the retirement age and female employment.
Prospective tracing of MLL-FRYL clone with low MEIS1 expression from emergence during neuroblastoma treatment to diagnosis of myelodysplastic syndrome
Authors: Robinson Blaine W. , Cheung Nai-Kong V. , Kolaris Christos P. , Jhanwar Suresh C. , Choi John K. , Osheroff Neil , Felix Carolyn A. 
Published: January 2008

AbstractWe prospectively observed a child exposed to intensive multimodality therapy for metastatic neuroblastoma from emergence of a MLL translocation to disease diagnosis. The t(4;11)(p12;q23) was detected in the marrow 17 months after starting treatment following topoisomerase II poisons, alkylating agents, local radiation, hematopoietic stem cell transplantation, anti-GD2 monoclonal antibody with granulocyte macrophage–colony-stimulating factor, and a high cumulative dose of oral etoposide. Reciprocal genomic breakpoint junctions and fusion transcripts joined MLL with FRYL, the Drosophila melanogaster protein homologue of which regulates cell fate. Etoposide metabolites induced topoisomerase II cleavage complexes that could form both breakpoint junctions. Cells harboring the translocation replaced the marrow without clinical evidence of leukemia and differentiation appeared unaffected for 37 months. Subsequent bilineage dysplasia and increased blasts in addition to the translocation fulfilled criteria for MDS. The MEIS1 target gene of typical MLL fusion oncoproteins was underexpressed before and at MDS diagnosis. These results are consistent with repair of topoisomerase II cleavage from etoposide metabolites as the translocation mechanism, whereas other agents in the regimen may have contributed to progression of the clone with the translocation to MDS. MLL-FRYL did not increase MEIS1 expression, conferred a proliferative advantage without altering differentiation, and had protracted latency to disease.
Clonal heterogeneity in polycythemia vera patients with JAK2 exon12 and JAK2-V617F mutations
Authors: Li Sai , Kralovics Robert , De Libero Gennaro , Theocharides Alexandre , Gisslinger Heinz , Skoda Radek C. 
Published: January 2008

AbstractWe studied the lineage distribution of JAK2 mutations in peripheral blood of 8 polycythemia vera (PV) patients with exon 12 mutations and in 21 PV patients with JAK2-V617F. Using a quantitative allele discrimination assay, we detected exon 12 mutations in purified granulocytes, monocytes, and platelets of 8 patients studied, but lymphoid cells showed variable involvement and the mutation was absent in T cells. Endogenous erythroid colonies grew in all patients analyzed. One patient displayed erythroid colonies homozygous for the exon 12 mutation with evidence for mitotic recombination on chromosome 9p. In some patients with exon 12 mutations or JAK2-V617F, a proportion of endogenous erythroid colonies were negative for both JAK2 mutations. One patient carried 2 independent clones: one with an exon 12 mutation and a second with JAK2-V617F. The finding of clonal heterogeneity is compatible with the hypothesis that additional clonal events are involved in the pathogenesis of PV.
Increased numbers of circulating hematopoietic stem/progenitor cells are chronically maintained in patients treated with the CD49d blocking antibody natalizumab
Authors: Bonig Halvard , Wundes Annette , Chang Kai-Hsin , Lucas Sylvia , Papayannopoulou Thalia 
Published: January 2008

AbstractBlockade of CD49d-mediated lymphocyte trafficking has been used therapeutically for certain autoimmune diseases, such as multiple sclerosis (MS). In addition to negative effects on the trafficking of mature lymphocytes to sites of inflammation, CD49d blockade in mice and monkeys rapidly mobilizes hematopoietic stem/progenitor cells (HSPCs) capable of short- and long-term engraftment. Here we aimed to ascertain the effects of treatment with antifunctional anti-CD49d antibody in humans (MS patients receiving infusions of the CD49d-blocking antibody natalizumab) on levels of circulating HSPCs after a single dose of antibody or after long-term treatment. On average, 6-fold elevated levels of circulating CD34+ cells and colony-forming unit-culture (CFU-C) were achieved within 1 day of the first dose of natalizumab, and similar levels were continuously maintained under monthly natalizumab infusions. The blood of natalizumab-treated subjects also contained SCID-repopulating cells. The fate of these circulating HSPCs and their clinical relevance for MS patients remains to be determined.
Differential requirement for DOCK2 in migration of plasmacytoid dendritic cells versus myeloid dendritic cells
Authors: Gotoh Kazuhito , Tanaka Yoshihiko , Nishikimi Akihiko , Inayoshi Ayumi , Enjoji Munechika , Takayanagi Ryoichi , Sasazuki Takehiko , Fukui Yoshinori 
Published: January 2008

Abstract
The migratory properties of dendritic cells (DCs) are important for their functions. Although several chemokines and their receptors have been implicated in DC migration, the downstream signaling molecules are largely unknown. Here we show that DOCK2, a hematopoietic cell-specific CDM family protein, is indispensable for migration of plasmacytoid DCs (pDCs), but not myeloid DCs (mDCs). Although DOCK2-deficiency did not affect development of pDCs, DOCK2-deficient (DOCK2−/−) mice exhibited a severe reduction of pDCs in the spleen and lymph nodes. Adoptive transfer experiments revealed that DOCK2−/− pDCs failed to migrate into the periarteriolar lymphoid sheaths of the spleen. In DOCK2−/− pDCs, chemokine-induced Rac activation was severely impaired, resulting in the reduction of motility and the loss of polarity during chemotaxis. In contrast, DOCK2−/− mDCs did not show any defects in Rac activation and migration. These results indicate that pDCs and mDCs use distinct molecules to activate Rac during chemotaxis.