bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Serum Cytokines in Patients with Severe Acute Respiratory Syndrome
Authors: Zhang Yuanchun , Li Jing , Zhan Yuliang , Wu Lianqiu , Yu Xueying , Zhang Wenjian , Ye Liya , Xu Shiqing , Sun Ruihua , Wang Yunting , Lou Jinning
Published: July 2004

Severe acute respiratory syndrome (SARS) is an acute infectious disease of the respiratory system. Although a novel coronavirus has been identified as the causative agent of SARS, the pathogenic mechanisms of SARS are not understood. In this study, sera were collected from healthy donors, patients with SARS, patients with severe SARS, and patients with SARS in convalescence. The serum concentrations of interleukin-1 (IL-1), IL-4, IL-6, IL-8, IL-10, tumor growth factor beta (TGF-β), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) were measured by enzyme-linked immunosorbent assays (ELISA). The concentrations of IL-1 and TNF-α were not significantly different in different groups. The IL-6 concentration was increased in SARS patients and was significantly elevated in severe SARS patients, but the IL-6 concentrations were similar in convalescent patients and control subjects, suggesting that there was a positive relationship between the serum IL-6 concentration and SARS severity. The concentrations of IL-8 and TGF-β were decreased in SARS patients and significantly reduced in severe SARS patients, but they were comparable in convalescent SARS patients and control subjects, suggesting that there was a negative relationship between the IL-8 and TGF-β concentrations and SARS severity. The concentrations of IFN-γ, IL-4, and IL-10 showed significant changes only in convalescent SARS patients. The IFN-γ and IL-4 levels were decreased, while the levels of IL-10 were increased, and the differences between convalescent SARS patients and other patient groups were statistically significant. These results suggest that there are different immunoregulatory events during and after SARS and may contribute to our understanding of the pathogenesis of this syndrome.
Effects of the
Enterococcus faecalis hypR
Gene Encoding a New Transcriptional Regulator on Oxidative Stress Response and Intracellular Survival within Macrophages
Authors: Verneuil Nicolas , Sanguinetti Maurizio , Le Breton Yoann , Posteraro Brunella , Fadda Giovanni , Auffray Yanick , Hartke Axel , Giard Jean-Christophe
Published: July 2004

In order to identify regulators of the oxidative stress response in
Enterococcus faecalis
, an important human pathogen, several genes annotated as coding for transcriptional regulators were inactivated by insertional mutagenesis. One mutant, affected in the
ef2958
locus (designated
hypR
[hydrogen peroxide regulator]), appeared to be highly sensitive to oxidative challenge caused by hydrogen peroxide. Moreover, testing of the
hypR
mutant by using an in vivo-in vitro macrophage infection model resulted in a highly significant reduction in survival compared to the survival of parent strain JH2-2. Northern blot analyses were carried out with probes specific for genes encoding known antioxidant enzymes, and they showed that the
ahpCF
(alkyl hydro

p

eroxide reductase) transcript was expressed less in mutant cells. Mobility shift protein-DNA binding assays revealed that HypR regulated directly the expression of
hypR
itself and the
ahpCF
operon. Our combined results showed that HypR appeared to be directly involved in the expression of
ahpCF
genes under oxidative stress conditions and suggested that this regulator could contribute to the virulence of
E. faecalis
.
Gamma Interferon Production, but Not Perforin-Mediated Cytolytic Activity, of T Cells Is Required for Prevention of Toxoplasmic Encephalitis in BALB/c Mice Genetically Resistant to the Disease
Authors: Wang Xisheng , Kang Hoil , Kikuchi Takane , Suzuki Yasuhiro
Published: July 2004

We previously showed the requirement of both T cells and gamma interferon (IFN-γ)-producing non-T cells for the genetic resistance of BALB/c mice to the development of toxoplasmic encephalitis (TE). In order to define the role of IFN-γ production and the perforin-mediated cytotoxicity of T cells in this resistance, we obtained immune T cells from spleens of infected IFN-γ knockout (IFN-γ−/−), perforin knockout (PO), and wild-type BALB/c mice and transferred them into infected and sulfadiazine-treated athymic nude mice, which lack T cells but have IFN-γ-producing non-T cells. Control nude mice that had not received any T cells developed severe TE and died after discontinuation of sulfadiazine treatment due to the reactivation of infection. Animals that had received immune T cells from either wild-type or PO mice did not develop TE and survived. In contrast, nude mice that had received immune T cells from IFN-γ−/−mice developed severe TE and died as early as control nude mice. T cells obtained from the spleens of animals that had received either PO or wild-type T cells produced large amounts of IFN-γ after stimulation withToxoplasma gondiiantigens in vitro. In addition, the amounts of IFN-γ mRNA expressed in the brains of PO T-cell recipients did not differ from those in wild-type T-cell recipients. Furthermore, PO mice did not develop TE after infection, and their IFN-γ production was equivalent to or higher than that of wild-type animals. These results indicate that IFN-γ production, but not perforin-mediated cytotoxic activity, by T cells is required for the prevention of TE in genetically resistant BALB/c mice.
The Major Subunit of the Toxin-Coregulated Pilus TcpA Induces Mucosal and Systemic Immunoglobulin A Immune Responses in Patients with Cholera Caused by
Vibrio cholerae
O1 and O139
Authors: Asaduzzaman Muhammad , Ryan Edward T. , John Manohar , Hang Long , Khan Ashraful I. , Faruque A. S. G. , Taylor Ronald K. , Calderwood Stephen B. , Qadri Firdausi
Published: July 2004

Diarrhea caused by
Vibrio cholerae
is known to give long-lasting protection against subsequent life-threatening illness. The serum vibriocidal antibody response has been well studied and has been shown to correlate with protection. However, this systemic antibody response may be a surrogate marker for mucosal immune responses to key colonization factors of this organism, such as the toxin-coregulated pilus (TCP) and other factors. Information regarding immune responses to TCP, particularly mucosal immune responses, is lacking, particularly for patients infected with the El Tor biotype of
V. cholerae
O1 or
V. cholerae
O139 since highly purified TcpA from these strains has not been available previously for use in immune assays. We studied the immune responses to El Tor TcpA in cholera patients in Bangladesh. Patients had substantial and significant increases in TcpA-specific antibody-secreting cells in the circulation on day 7 after the onset of illness, as well as similar mucosal responses as determined by an alternate technique, the assay for antibody in lymphocyte supernatant. Significant increases in antibodies to TcpA were also seen in sera and feces of patients on days 7 and 21 after the onset of infection. Overall, 93% of the patients showed a TcpA-specific response in at least one of the specimens compared with the results obtained on day 2 and with healthy controls. These results demonstrate that TcpA is immunogenic following natural
V. cholerae
infection and suggest that immune responses to this antigen should be evaluated for potential protection against subsequent life-threatening illness.
Helicobacter pylori
Induces Apoptosis of Human Monocytes but Not Monocyte-Derived Dendritic Cells: Role of the
cag
Pathogenicity Island
Authors: Galgani Mario , Busiello Immacolata , Censini Stefano , Zappacosta Serafino , Racioppi Luigi , Zarrilli Raffaele
Published: July 2004

Monocytes are circulating precursors of the dendritic cell subset, professional antigen-presenting cells with a unique ability to initiate the innate and adaptive immune response. In this study, we have investigated the effects of wild-type
Helicobacter pylori
strains and their isogenic mutants with mutations in known bacterial virulence factors on monocytes and monocyte-derived dendritic cells. We show that
H. pylori
strains induce apoptosis of human monocytes by a mechanism that is dependent on the expression of a functional
cag
pathogenicity island. This effect requires an intact injection organelle for direct contact between monocytes and the bacteria but also requires a still-unidentified effector that is different from VacA or CagA. The exposure of in vitro-generated monocyte-derived dendritic cells to
H. pylori
stimulates the release of inflammatory cytokines by a similar mechanism. Of note is that dendritic cells are resistant to
H. pylori
-induced apoptosis. These phenomena may play a critical role in the evasion of the immune response by
H. pylori
, contributing to the persistence of the infection.
Characterization of an I-E-Restricted, gp63-Specific, CD4-T-Cell Clone fromLeishmania major-Resistant C3H Mice That Secretes Type 2 Cytokines and Exacerbates Infection withL. major
Authors: Theodos Cynthia M. , Morris Robin V. , Bishop Jeanette V. , Jones Jeremy D. , McMaster W. Robert , Titus Richard G.
Published: July 2004

A T-cell clone (designated KLmB-3) was derived from resistant C3H mice 2 weeks after infection withLeishmania major. KLmB-3 was a CD4-T-cell clone that utilized the Vβ8.1 T-cell receptor. When adoptively transferred to naive C3H mice, KLmB-3 unexpectedly exacerbated infection withL. major(it increased the cutaneous lesion size and the parasite burden within the lesion). The ability of KLmB-3 to exacerbate disease correlated with its ability to produce the type 2-associated cytokines interleukin-4 (IL-4), IL-5, IL-10, and transforming growth factor beta. Interestingly, KLmB-3 was specific for an epitope in the amino-terminal end of theL. majorsurface gp63 zinc metalloproteinase (leishmanolysin) that has been shown to be capable of inducing a protective immune response. Moreover, KLmB-3 was activated when this epitope was presented in the context of H-2 I-E rather than H-2 I-A.
Cytotoxicity of Hydrogen Peroxide Produced by
Enterococcus faecium
Authors: Moy Terence I. , Mylonakis Eleftherios , Calderwood Stephen B. , Ausubel Frederick M.
Published: July 2004

Although the opportunistic bacterial pathogen
Enterococcus faecium
is a leading source of nosocomial infections, it appears to lack many of the overt virulence factors produced by other bacterial pathogens, and the underlying mechanism of pathogenesis is not clear. Using
E. faecium
-mediated killing of the nematode worm
Caenorhabditis elegans
as an indicator of toxicity, we determined that
E. faecium
produces hydrogen peroxide at levels that cause cellular damage. We identified
E. faecium
transposon insertion mutants with altered
C. elegans
killing activity, and these mutants were altered in hydrogen peroxide production. Mutation of an NADH oxidase-encoding gene eliminated nearly all NADH oxidase activity and reduced hydrogen peroxide production. Mutation of an NADH peroxidase-encoding gene resulted in the enhanced accumulation of hydrogen peroxide.
E. faecium
is able to produce hydrogen peroxide by using glycerol-3-phosphate oxidase, and addition of glycerol to the culture medium enhanced the killing of
C. elegans
. Conversely, addition of glucose, which leads to the down-regulation of glycerol metabolism, prevented both
C. elegans
killing and hydrogen peroxide production. Lastly, detoxification of hydrogen peroxide either by exogenously added catalase or by a
C. elegans
transgenic strain overproducing catalase prevented
E. faecium
-mediated killing. These results suggest that hydrogen peroxide produced by
E. faecium
has cytotoxic effects and highlight the utility of
C. elegans
pathogenicity models for identifying bacterial virulence factors.
The Plague Virulence Protein YopM Targets the Innate Immune Response by Causing a Global Depletion of NK Cells
Authors: Kerschen Edward J. , Cohen Donald A. , Kaplan Alan M. , Straley Susan C.
Published: July 2004

Yersinia pestis, the etiologic agent of plague, delivers sixYersiniaouter proteins (Yops) into host cells upon direct bacterial contact. One of these, YopM, is necessary for virulence in a mouse model of septicemic plague, but its pathogenic function is unknown. We report here the immune processes affected by YopM during infection. To test whether the innate or adaptive immune system is targeted by YopM, C57BL/6 (B6) and B6 SCID mice were infected with either the conditionally virulentY. pestisKIM5 or ayopMdeletion mutant and evaluated for bacterial growth in spleen and liver. Both B6 and SCID mice succumbed to infection withY. pestisKIM5, whereas both mouse strains survived infection by the YopM−mutant. These data showed that YopM counteracts innate defenses present in SCID mice. The YopM−strain grew more slowly than the parentY. pestisduring the first 4 days of infection in both mouse strains, indicating an early pathogenic role for YopM. In B6 mice, populations of cells of the immune system were not differentially affected by the twoY. pestisstrains, with one major exception: the parentY. pestisKIM5 but not the YopM−mutant caused a significant global decrease in NK cell numbers (blood, spleen, and liver), beginning early in infection. NK cells and macrophages isolated early (day 2) from livers and spleens of mice infected with eitherY. pestisstrain contained comparable levels of cytokine mRNA: interleukin (IL)-1β, IL-12, IL-15, IL-18, and tumor necrosis factor alpha in macrophages and gamma interferon in NK cells. However, by day 4 postinfection, cells from mice infected with the parentY. pestisexpressed lower levels of these messages, while those from mice infected with the mutant retained strong expression. Significantly, mRNA for the IL-15 receptor α chain was not expressed in NK cells fromY. pestisKIM5-infected mice as early as day 2 postinfection. These findings suggest that YopM interferes with innate immunity by causing depletion of NK cells, possibly by affecting the expression of IL-15 receptor α and IL-15.
Inbred Strains Derived from Feral Mice Reveal New Pathogenic Mechanisms of Experimental Leishmaniasis Due toLeishmania major
Authors: Babay Besma E. C. , Louzir Hechmi , Kebaïer Chahnaz , Boubaker Samir , Dellagi Koussay , Cazenave Pierre-André
Published: July 2004

Two inbred mouse strains, derived from feral founders, are susceptible to experimental leishmaniasis due toLeishmania majorand support a disease of a severity intermediate between those observed in strains C57BL/6 and BALB/c. Mice of the MAI strain develop a severe, nonhealing, but nonfatal disease with no resistance to a secondary parasite challenge. The immunological responses showed a TH2 dominance characterized by an early peak of interleukin-4 (IL-4) and IL-13. However, neutralization of IL-4, which leads to a resistance phenotype in BALB/c mice, has no effect on disease progression in MAI mice. Mice of strain PWK develop a protracted but self-healing disease, characterized by a mixed TH1-plus-TH2 pattern of immune responses in which IL-10 plays an aggravating role, and acquire resistance to a secondary challenge. These features are close to those observed in human cutaneous leishmaniasis due toL. majorand make PWK mice a suitable model for the human disease.
Gamma Interferon Production by Bovine γδ T Cells following Stimulation with Mycobacterial Mycolylarabinogalactan Peptidoglycan
Authors: Vesosky B. , Turner O. C. , Turner J. , Orme I. M.
Published: July 2004

A large percentage of lymphocytes in the blood of cattle express the γδ T-cell receptor, but specific functions for these cells have not yet been clearly defined. There is evidence, however, that human, murine, and bovine γδ T cells have a role in the immune response to mycobacteria. This study investigated the ability of bovine γδ T cells to expand and produce gamma interferon (IFN-γ) in response to stimulation with mycobacterial products. Bovine γδ T cells, isolated from the peripheral blood of healthy cattle, expanded following in vitro stimulation with live mycobacteria, mycobacterial crude cell wall extract, andMycobacterium bovisculture filtrate proteins. In addition, purified γδ T cells, cocultured with purified monocytes and interleukin-2, consistently produced significant amounts of IFN-γ in response to mycobacterial cell wall. The IFN-γ-inducing component of the cell wall was further identified as a proteolytically resistant, non-sodium dodecyl sulfate-soluble component of the mycolylarabinogalactan peptidoglycan.
Multiple Functions of the Leucine-Rich Repeat Protein LrrA of
Treponema denticola
Authors: Ikegami Akihiko , Honma Kiyonobu , Sharma Ashu , Kuramitsu Howard K.
Published: July 2004

The gene
lrrA
, encoding a leucine-rich repeat protein, LrrA, that contains eight consensus tandem repeats of 23 amino acid residues, has been identified in
Treponema denticola
ATCC 35405. A leucine-rich repeat is a generally useful protein-binding motif, and proteins containing this repeat are typically involved in protein-protein interactions. Southern blot analysis demonstrated that
T. denticola
ATCC 35405 expresses the
lrrA
gene, but the gene was not identified in
T. denticola
ATCC 33520. In order to analyze the functions of LrrA in
T. denticola
, an
lrrA
-inactivated mutant of strain ATCC 35405 and an
lrrA
gene expression transformant of strain ATCC 33520 were constructed. Characterization of the mutant and transformant demonstrated that LrrA is associated with the extracytoplasmic fraction of
T. denticola
and expresses multifunctional properties. It was demonstrated that the attachment of strain ATCC 35405 to HEp-2 cell cultures and coaggregation with
Tannerella forsythensis
were attenuated by the
lrrA
mutation. In addition, an in vitro binding assay demonstrated specific binding of LrrA to a portion of the
Tannerella forsythensis
leucine-rich repeat protein, BspA, which is mediated by the N-terminal region of LrrA. It was also observed that the
lrrA
mutation caused a reduction of swarming in
T. denticola
ATCC 35405 and consequently attenuated tissue penetration. These results suggest that the leucine-rich repeat protein LrrA plays a role in the attachment and penetration of human epithelial cells and coaggregation with
Tannerella forsythensis
. These properties may play important roles in the virulence of
T. denticola
.
Mucosally DeliveredSalmonellaLive Vector Vaccines Elicit Potent Immune Responses against a Foreign Antigen in Neonatal Mice Born to Naive and Immune Mothers
Authors: Capozzo Alejandra V. E. , Cuberos Lilian , Levine Myron M. , Pasetti Marcela F.
Published: July 2004

The development of effective vaccines for neonates and very young infants has been impaired by their weak, short-lived, and Th-2 biased responses and by maternal antibodies that interfere with vaccine take. We investigated the ability ofSalmonella entericaserovars Typhi and Typhimurium to mucosally deliver tetanus toxin fragment C (Frag C) as a model antigen in neonatal mice. We hypothesize thatSalmonella, by stimulating innate immunity (contributing to adjuvant effects) and inducing Th-1 cytokines, can enhance neonatal dendritic cell maturation and T-cell activation and thereby prime humoral and cell-mediated immunity. We demonstrate for the first time that intranasal immunization of newborn mice with 109CFU ofS. entericaserovar Typhi CVD 908-htrAandS. entericaserovar Typhimurium SL3261 carrying plasmid pTETlppon days 7 and 22 after birth elicits high titers of Frag C antibodies, previously found to protect against tetanus toxin challenge and similar to those observed in adult mice.Salmonellalive vectors colonized and persisted primarily in nasal tissue. Mice vaccinated as neonates induced Frag C-specific mucosal and systemic immunoglobulin A (IgA)- and IgG-secreting cells, T-cell proliferative responses, and gamma interferon secretion. A mixed Th1- and Th2-type response to Frag C was established 1 week after the boost and was maintained thereafter.S. entericaserovar Typhi carrying pTETlppinduced Frag C-specific antibodies and cell-mediated immunity in the presence of high levels of maternal antibodies. This is the first report that demonstrates the effectiveness ofSalmonellalive vector vaccines in early life.
Role of p38 Mitogen-Activated Protein Kinase in Middle Ear Mucosa Hyperplasia during Bacterial Otitis Media
Authors: Palacios Sean D. , Pak Kwang , Rivkin Alexander Z. , Kayali Ayse G. , Austen Darrell , Aletsee Christoph , Melhus Åsa , Webster Nicholas J. G. , Ryan Allen F.
Published: July 2004

Hyperplasia of the middle ear mucosa contributes to the sequelae of acute otitis media. Understanding the signal transduction pathways that mediate hyperplasia could lead to the development of new therapeutic interventions for this disease and its sequelae. Endotoxin derived from bacteria involved in middle ear infection can contribute to the hyperplastic response. The p38 mitogen-activated protein kinase (MAPK) is known to be activated by endotoxin as well as cytokines and other inflammatory mediators that have been documented in otitis media. We assessed the activation of p38 in the middle ear mucosa of an in vivo rat bacterial otitis media model. Strong activity of p38 was observed 1 to 6 h after bacterial inoculation. Activity continued at a lower level for at least 7 days. The effects of p38 activation were assessed using an in vitro model of rat middle ear mucosal hyperplasia in which mucosal growth is stimulated by nontypeableHaemophilus influenzaeduring acute otitis media. Hyperplastic mucosal explants treated with the p38α and p38β inhibitor SB203580 demonstrated significant inhibition of otitis media-stimulated mucosal growth. The results of this study suggest that intracellular signaling via p38 MAPK influences the hyperplastic response of the middle ear mucosa during bacterial otitis media.
In Vitro Models of Tissue Penetration and Destruction by
Porphyromonas gingivalis
Authors: Andrian Elisoa , Grenier Daniel , Rouabhia Mahmoud
Published: July 2004

Porphyromonas gingivalis
is a gram-negative anaerobic bacterium that is considered the key etiologic agent of chronic periodontitis. Arg- and Lys-gingipain cysteine proteinases produced by
P. gingivalis
are key virulence factors and are believed to be essential for significant tissue component degradation, leading to host tissue invasion by periodontopathogens. Two in vitro models were used to determine the extent to which
P. gingivalis
can reach connective tissue. The tissue penetration potential of
P. gingivalis
was first investigated by using an engineered human oral mucosa model composed of normal human epithelial cells and fibroblasts. Internalized bacteria were assessed by transmission electron microscopy. Bacteria were observed within multilayered gingival epithelial cells and in the space between the stratified epithelium and the lamina propria. A gingipain-null mutant strain of
P. gingivalis
was found to be less potent in penetrating tissue than the wild-type strain. Proinflammatory responses to
P. gingivalis
infection were evaluated.
P. gingivalis
increased the secretion of interleukin-1β, interleukin-6, interleukin-8, and tumor necrosis factor alpha. In the second part of the study, the contribution of
P. gingivalis
gingipains to tissue penetration was investigated by using a reconstituted basement membrane model (Matrigel). The penetration of
14
C-labeled
P. gingivalis
cells through Matrigel was significantly reduced when leupeptin, a specific inhibitor of Arg-gingipain activity, was added or when a gingipain-null mutant was used. The results obtained with these two relevant models support the capacities of
P. gingivalis
to infiltrate periodontal tissue and to modulate the proinflammatory response and suggest a critical role of gingipains in tissue destruction.
Reinfection withAnaplasma phagocytophilumin BALB/c Mice and Cross-Protection between Two Sympatric Isolates
Authors: Levin Michael L. , Coble Dondrae J. , Ross Danielle E.
Published: July 2004

Infection withAnaplasma phagocytophilumin white-footed mice results in partial protection against reinfection with the same agent. However, humans and domestic animals may be sequentially exposed to different isolates of the agent circulating in the same or adjacent foci. We investigated whether immune response to a tick-borne infection withA. phagocytophilumprovides protection against homologous and heterologous challenges. BALB/c mice were infected with one of the two sympatric isolates ofA. phagocytophilumvia tick bite and challenged 16 weeks later byIxodes scapularisnymphs infected with either the same or the alternative isolate. As controls, groups of infected mice were challenged by uninfected ticks to confirm an absence of reactivation of the original infection or groups of naive mice were fed upon by ticks from cohorts used for an infectious challenge. XenodiagnosticI. scapularislarvae were fed upon each mouse at 14 and 21 days postchallenge (PCH) and tested for the presence ofA. phagocytophilumas freshly molted nymphs. Blood samples for quantitative PCR were collected at 7, 14, 21, and 70 days PCH. Serum samples were collected weekly to monitor development of immune response. The proportion of infected animals, levels of bacteremia, and the prevalence of infection in xenodiagnostic ticks were higher in groups of control mice exposed toA. phagocytophilumfor the first time than in mice reinfected with either homologous or heterologous isolates. The presence of antibodies againstA. phagocytophilumdid not protect mice from a challenge with either homologous or heterologous isolates, however the ensuing reinfection was significantly milder and of a shorter duration than the first infection with either isolate.
Anaplasma phagocytophilumUtilizes Multiple Host Evasion Mechanisms To Thwart NADPH Oxidase-Mediated Killing during Neutrophil Infection
Authors: Carlyon Jason A. , Latif Dalia Abdel , Pypaert Marc , Lacy Paige , Fikrig Erol
Published: July 2004

Anaplasma phagocytophilum, the etiologic agent of human anaplasmosis, is a bacterial pathogen that specifically colonizes neutrophils. Neutrophils utilize the NADPH oxidase complex to generate superoxide (O2−) and initiate oxidative killing of microorganisms.A. phagocytophilum's unique tropism for neutrophils, however, indicates that it subverts and/or avoids oxidative killing. We therefore examined the effects ofA. phagocytophiluminfection on neutrophil NADPH oxidase assembly and reactive oxygen species (ROS) production. Following neutrophil binding,Anaplasmainvasion requires at least 240 min. During its prolonged association with the neutrophil plasma membrane,A. phagocytophilumstimulates NADPH oxidase assembly, as indicated by increased cytochromeb558mobilization to the membrane, as well as colocalization of Rac and p22phox. This initial stimulation taxes the host neutrophil's finite oxidase reserves, as demonstrated by time- and bacterial-dose-dependent decreases in secondary activation byN-formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA). This stimulation is modest, however, and does not diminish oxidase stores to nearly the extent thatEscherichia coli, serum-opsonized zymosan, FMLP, or PMA do. Despite the apparent activation of NADPH oxidase, no change in ROS-dependent chemiluminescence is observed upon the addition ofA. phagocytophilumto neutrophils, indicating that the bacterium may scavenge exogenous O2−. Indeed,A. phagocytophilumrapidly detoxifies O2−in a cell-free system. Once internalized, the bacterium resides within a protective vacuole that excludes p22phoxand gp91phox. Thus,A. phagocytophilumemploys at least two strategies to protect itself from neutrophil NADPH oxidase-mediated killing.
YAPI, a New
Yersinia pseudotuberculosis
Pathogenicity Island
Authors: Collyn François , Billault Alain , Mullet Chantal , Simonet Michel , Marceau Michaël
Published: July 2004

Pathogenicity islands (PAIs) are chromosomal clusters of pathogen-specific virulence genes often found at tRNA loci. In the
Yersinia pseudotuberculosis
32777 chromosome, we characterized a 98-kb segment that has all of the characteristic features of a PAI, including insertion in a (phenylalanine) tRNA gene, the presence of a bacteriophage-like integrase-encoding gene, and direct repeats at the integration sites. The G+C content of the segment ranges from 31 to 60%, reflecting a genetic mosaic: this is consistent with the notion that the sequences were horizontally acquired. The PAI, termed YAPI (for
Yersinia
adhesion pathogenicity island), carries 95 open reading frames and includes (i) the previously described
pil
operon, encoding a type IV pilus that contributes to pathogenicity (F. Collyn et al., Infect. Immun. 70:6196-6205, 2002); (ii) a block of genes potentially involved in general metabolism; (iii) a gene cluster for a restriction-modification system; and (iv) a large number of mobile genetic elements. Furthermore, the PAI can excise itself from the chromosome at low frequency and in a precise manner, and deletion does not result in a significant decrease of bacterial virulence compared to inactivation of the fimbrial gene cluster alone. The prevalence and size of the PAI vary from one
Y. pseudotuberculosis
strain to another, and it can be found integrated into either of the two
phe
tRNA loci present on the species' chromosome. YAPI was not detected in the genome of the genetically closely related species
Y. pestis
, whereas a homologous PAI is harbored by the
Y. enterocolitica
chromosome.
Interaction of Dr Adhesin with Collagen Type IV Is a Critical Step in
Escherichia coli
Renal Persistence
Authors: Selvarangan Rangaraj , Goluszko Pawel , Singhal Jyotsana , Carnoy Christophe , Moseley Steve , Hudson Billy , Nowicki Stella , Nowicki Bogdan
Published: July 2004

The pathogenic mechanism of recurrent or chronic urinary tract infection is poorly understood.
Escherichia coli
cells bearing Dr fimbriae display unique tropism to the basement membrane (BM)-renal interstitium that enables the bacteria to cause chronic pyelonephritis in experimental mice. The renal receptors for Dr-fimbriated
E. coli
are type IV collagen and decay-accelerating factor (DAF). We hypothesized that type IV collagen receptor-mediated BM-interstitial tropism is essential for
E. coli
to cause chronic pyelonephritis. To test the role of the type IV collagen tropism of Dr-fimbriated
E. coli
in renal persistence, we constructed an isogenic mutant in the DraE adhesin subunit that was unable to bind type IV collagen but retained binding to DAF and examined its virulence in the mouse model. The collagen-binding mutant DrI113T was eliminated from the mouse renal tissues in 6 to 8 weeks, while the parent strain caused persistent renal infection that lasted at least 14 weeks (
P
≤ 0.02). Transcomplementation with the intact Dr operon restored collagen-binding activity, BM-interstitial tropism, and the ability to cause persistent renal infection. We conclude that type IV collagen binding mediated by DraE adhesin is a critical step for the development of persistent renal infection in a murine model of
E. coli
pyelonephritis.
Aeromonas hydrophila
Beta-Hemolysin Induces Active Chloride Secretion in Colon Epithelial Cells (HT-29/B6)
Authors: Epple H. J. , Mankertz J. , Ignatius R. , Liesenfeld O. , Fromm M. , Zeitz M. , Chakraborty T. , Schulzke J. D.
Published: July 2004

The diarrheal mechanisms in
Aeromonas
enteritis are not completely understood. In this study we investigated the effect of aeromonads and of their secretory products on ion secretion and barrier function of monolayers of human intestinal cells (HT-29/B6). Ion secretion was determined as a short-circuit current (I
SC
) of HT-29/B6 monolayers mounted in Ussing-type chambers. Transepithelial resistance (R
t
) served as a measure of permeability. A diarrheal strain of
Aeromonas hydrophila
(strain Sb) added to the mucosal side of HT-29/B6 monolayers induced a significant I
SC
(39 ± 3 μA/cm
2
) and decreased the R
t
to ∼10% of the initial value. A qualitatively identical response was obtained with sterile supernatant of strain Sb, and
Aeromonas
supernatant also induced a significant I
SC
in totally stripped human colon. Tracer flux and ion replacement studies revealed the I
SC
to be mainly accounted for by electrogenic Cl
−
secretion. Supernatant applied serosally completely abolished basal I
SC
. The supernatant-induced I
SC
was inhibited by the protein kinase C inhibitor chelerythrine, whereas a protein kinase A inhibitor (H8) and a Ca
2+
chelator (BAPTA-AM) had no effect. Physicochemical properties indicated that the supernatant's active compound was an aerolysin-related
Aeromonas
beta-hemolysin. Accordingly, identical I
SC
and R
t
responses were obtained with
Escherichia coli
lysates harboring the cloned beta-hemolysin gene from strain SB or the
aerA
gene encoding for aerolysin. Sequence comparison revealed a 64% homology between aerolysin and the beta-hemolysin cloned from
Aeromonas
sp. strain Sb. In conclusion, beta-hemolysin secreted by pathogenic aeromonads induces active Cl
−
secretion in the intestinal epithelium, possibly by channel insertion into the apical membrane and by activation of protein kinase C.
Elevated Nitric Oxide Production in Children with Malarial Anemia: Hemozoin-Induced Nitric Oxide Synthase Type 2 Transcripts and Nitric Oxide in Blood Mononuclear Cells
Authors: Keller Christopher C. , Kremsner Peter G. , Hittner James B. , Misukonis Mary A. , Weinberg J. Brice , Perkins Douglas J.
Published: July 2004

Experiments outlined here investigate the role of nitric oxide (NO) in the pathogenesis of
Plasmodium falciparum
-induced malarial anemia (MA). The results show that ex vivo and in vitro NO synthase (NOS) activity in peripheral blood mononuclear cells (PBMCs) is significantly elevated in children with MA and inversely associated with hemoglobin levels. Additional experiments using PBMCs from non-malaria-exposed donors demonstrate that physiologic amounts of
P. falciparum
-derived hemozoin augment NOS type 2 (NOS2) transcripts and NO production. Results of these experiments illustrate that elevated NO production in children with MA is associated with decreased hemoglobin concentrations and that hemozoin can induce NOS2-derived NO formation in cultured blood mononuclear cells.
Genetic Susceptibility of Mice to
Candida albicans
Vaginitis Correlates with Host Estrogen Sensitivity
Authors: Clemons Karl V. , Spearow Jimmy L. , Parmar Rachana , Espiritu Marife , Stevens David A.
Published: July 2004

We compared susceptibility to
Candida
vaginitis in derived murine substrains differing in sensitivity to estrogen (CD-1 and CD10, resistant; CD3 and C57BL/6 responsive), and in F1 crosses. The order of decreasing resistance was CD-1 ≥ CD10 ≥ CD10 × CD3F1 > CD10 × B6F1 > CD3 > C57BL/6 and correlated with estrogen responsiveness in endocrine disruptor assays. Resistance to
Candida
vaginitis appears additive in CD10 × B6F1 animals and dominant in CD10 × CD3F1 animals.
Mycoplasma penetrans
Is Capable of Activating Vγ9/Vδ2 T Cells While Other Human Pathogenic Mycoplasmas Fail To Do So
Authors: Eberl Matthias , Hintz Martin , Jamba Zandraa , Beck Ewald , Jomaa Hassan , Christiansen Gunna
Published: July 2004

While most mycoplasma species appear to have evolutionarily lost the ability to synthesize isoprenoid precursors,
Mycoplasma penetrans
has retained the nonmevalonate pathway that proceeds via the immunogenic intermediate (
E
)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP). Consequently, this pathogen is capable of stimulating human Vγ9/Vδ2 T cells.
N19 Polyepitope as a Carrier for Enhanced Immunogenicity and Protective Efficacy of Meningococcal Conjugate Vaccines
Authors: Baraldo Karin , Mori Elena , Bartoloni Antonella , Petracca Roberto , Giannozzi Aldo , Norelli Francesco , Rappuoli Rino , Grandi Guido , Del Giudice Giuseppe
Published: July 2004

N19, a string of human universal CD4 T-cell epitopes from various pathogen-derived antigens, was shown to exert a stronger carrier effect than CRM197 for the induction of anti-group CNeisseria meningitidiscapsular polysaccharide (MenC), after immunization of mice with various dosages of N19-MenC or CRM-MenC conjugate vaccines. After two immunizations, the N19-based construct induced anti-MenC antibody and protective bactericidal antibody titers higher than those induced by three doses of the CRM-MenC conjugate and required lower amounts of conjugate. N19-based conjugates are superior to CRM-based conjugates to induce protective immune responses to MenC conjugates.
Biofilm Formation In Vitro and Virulence In Vivo of Mutants of
Klebsiella pneumoniae
Authors: Lavender Heather F. , Jagnow Jennifer R. , Clegg Steven
Published: July 2004

One of the early stages of
Klebsiella pneumoniae
airway infections may involve biofilm formation. Bacterial biofilm formation is frequently investigated using in vitro techniques that facilitate identification and analysis of individual genes. We investigated the correlation between
K. pneumoniae
biofilm formation in vitro and ability to cause infection in vivo following construction of a bank of mini-Tn
5
mutants.
Inhibition of Nitric Oxide Synthase Exacerbates Group BStreptococcusSepsis and Arthritis in Mice
Authors: Puliti Manuela , von Hunolstein Christina , Bistoni Francesco , Orefici Graziella , Tissi Luciana
Published: July 2004

The role of nitric oxide in group BStreptococcus(GBS) infection was evaluated by inhibiting its production with aminoguanidine (AG). AG-treated mice displayed higher mortality rates and more frequent and severe arthritis than controls. Worsening of arthritis correlated with a higher number of GBS cells in the joints and local interleukin-1β production.
Involvement of the Chemokine RANTES (CCL5) in Resistance to Experimental Infection with
Leishmania major
Authors: da Costa Santiago Helton , Oliveira Carolina Ferreira , Santiago Luciana , Oliveira Ferraz Fernanda , da Glória de Souza Daniele , Rodrigues De-Freitas Luiz Antônio , Crocco Afonso Luís Carlos , Teixeira Mauro Martins , Gazzinelli Ricardo Tostes , Vieira Leda Quercia
Published: July 2004

The expression and putative role of chemokines during infection with
Leishmania major
in mice were investigated. CCL5 expression correlates with resistance, and blockade of CCL5 rendered mice more susceptible to infection. CCL5 is part of the cascade of events leading to efficient parasite control in
L. major
infection.
DNA-
Salmonella enterica
Serovar Typhimurium Primer-Booster Vaccination Biases towards T Helper 1 Responses and Enhances Protection against
Leishmania major
Infection in Mice
Authors: Lange Uta G. , Mastroeni Pietro , Blackwell Jenefer M. , Stober Carmel B.
Published: July 2004

Successful resolution of infections by intracellular pathogens requires gamma interferon (IFN-γ). DNA vaccines promote T helper 1 (Th1) responses by triggering interleukin-12 (IL-12) release by dendritic cells (DC) through Toll-like receptor 9 (TLR9). In humans TLR9 is restricted to plasmacytoid DC. Here we show that DNA-
Salmonella enterica
serovar Typhimurium primer-booster vaccination, which provides alternative ligands to bind TLR4 on myeloid DC, strongly biases towards Th1 responses compared to vaccination with DNA alone. This results in higher immunoglobulin G2a (IgG2a) responses compared to IgG1 responses, higher IFN-γ responses compared to IL-10 CD4
+
-T-cell responses, and enhanced protection against
Leishmania major
infection in susceptible BALB/c mice.
A survey of flexibility training protocols and hamstring strains in professional football clubs in England
Authors: Dadebo B , White J , George K P
Published: July 2004

Objectives:To investigate the relation between current flexibility training protocols, including stretching, and hamstring strain rates (HSRs) in English professional football clubs.

Method:Questionnaire based data on flexibility training methods and HSRs were collected from 30 English professional football clubs in the four divisions during the 1998/99 season. Data were coded and analysed using cross tabulation, correlation, and multiple regression.

Results:Flexibility training protocols were characterised by wide variability, with static stretching the most popular stretching technique used. Hamstring strains represented 11% of all injuries and one third of all muscle strains. About 14% of hamstring strains were reinjuries. HSRs were highest in the Premiership (13.3 (9.4)/1000 hours) with the lowest rates in Division 2 (7.8 (2.9)/1000 hours); values are mean (SD). Most (97%) hamstring strains were grade I and II, two thirds of which occurred late during training/matches. Forwards were injured most often. Use of the standard stretching protocol (SSP) was the only factor significantly related to HSR (r =  −0.45, p  =  0.031) in the correlation analysis, suggesting that the more SSP is used, the lower the HSR. About 80% of HSR variability was accounted for by stretching holding time (SHT), SSP, and stretching technique (STE) in the multiple regression equation: HSR  =  37.79 − (0.33SHT − 10.05SSP + 2.24STE) ± 2.34. SHT (negatively correlated with HSR) was the single highest predictor, and accounted for 30% of HSR variability, and an additional 40% in combination with SSP.

Conclusions:Flexibility training protocols in the professional clubs were variable and appeared to depend on staffing expertise. Hamstring stretching was the most important training factor associated with HSR. The use of SSP, STE, and SHT are probably involved in a complex synergism which may reduce hamstring strains. Modification of current training patterns, especially stretching protocols, may reduce HSRs in professional footballers.
Do team gymnasts compete in spite of symptoms from an injury?
Authors: Harringe M L , Lindblad S , Werner S
Published: July 2004

Background:Gymnasts practise many hours a week, and symptoms from injuries do not seem to stop them from continuing with practice. They may even compete with symptoms from injuries, which could increase the risk of reinjury, or of the occurrence of a more severe injury.

Objectives:To investigate whether team gymnasts compete at high level in spite of symptoms from an injury.

Methods:188 male and female competitors participating in the Swedish Cup for juniors and seniors answered a questionnaire about symptoms from injuries on the day of the competition.

Results:More than half the gymnasts (58%) competed despite having symptoms from an injury on the day of the competition. More seniors than juniors competed in spite of symptoms from an injury (p = 0.006). Two of three team gymnasts (65%) reported symptoms from the lower extremities and around one in five (22%) reported back symptoms. Fifty five per cent of the gymnasts reported recurrence of an injury at the same site (reinjury).

Conclusions:There was a high prevalence of symptoms from injuries on the day of competition. This did not stop the team gymnasts from competing.
Master’s performance in the New York City Marathon 1983–1999
Authors: Jokl P , Sethi P M , Cooper A J
Published: July 2004

Background:Physical activity in older people is believed to slow down the natural aging process through its effects on disuse atrophy.

Objectives:To show that elite master (age above 50) male and female athletes, as a group, have improved their running times over the last two decades at a greater rate than their younger counterparts.

Methods:Running time, age, and sex of all 415 000 runners in the New York City Marathon from 1983 to 1999 were examined using linear regression analysis.

Results:The number of master participants increased at a greater rate than their younger counterparts (p<0.05). Running times for the top 50 male and female finishers over the past two decades showed significantly greater improvement in the master groups than in the younger age groups (p<0.001).

Conclusions:Participation in the New York City Marathon is increasing at a higher rate in the master groups than in other age groups. Male and female masters continued to improve running times at a greater rate than the younger athletes, whose performance levels have plateaued. This is the largest study to compare master athletic performance with younger counterparts and men with women.
Mutations in the hereditary haemochromatosis gene HFE in professional endurance athletes
Authors: Chicharro J L , Hoyos J , Gómez-Gallego F , Villa J G , Bandrés F , Celaya P , Jiménez F , Alonso J M , Córdova A , Lucia A
Published: July 2004

Background:Hereditary haemochromatosis, a disease that affects iron metabolism, progresses with a greater or lesser tendency to induce iron overload, possibly leading to severe organ dysfunction. Most elite endurance athletes take iron supplements during their active sporting life, which could aggravate this condition.

Objective:To determine the prevalence and discuss potential clinical implications of mutations of HFE (the gene responsible for hereditary haemochromatosis) in endurance athletes.

Methods:Basal concentrations of iron, ferritin, and transferrin and transferrin saturation were determined in the period before competition in 65 highly trained athletes. Possible mutations in the HFE gene were evaluated in each subject by extracting genomic DNA from peripheral blood. The restriction enzymesSnaBI andBclI were used to detect the mutations 845G→A (C282Y) and 187C→G (H63D).

Results:Our findings indicate a high prevalence of HFE gene mutations in this population (49.2%) compared with sedentary controls (33.5%). No association was detected in the athletes between mutations and blood iron markers.

Conclusions:The findings support the need to assess regularly iron stores in elite endurance athletes.
Evaluation of physiological standard pressures of the forearm flexor muscles during sport specific ergometry in sport climbers
Authors: Schoeffl V , Klee S , Strecker W
Published: July 2004

Background:Chronic exertional compartment syndromes (CECS) are well known in sports medicine. Most commonly affected is the tibialis anterior muscle compartment in runners and walkers. Only a few cases of CECS of the forearm flexor muscles have been reported.

Objectives:To determine pressure levels inside the deep flexor compartment of the forearms during a sport specific stress test.

Method:Ten healthy, high level climbers were enrolled in a prospective study. All underwent climbing specific ergometry, using a rotating climbing wall (step test, total climbing time 9–15 minutes). Pressure was measured using a slit catheter placed in the deep flexor compartment of the forearm. Pressure, blood lactate, and heart rate were recorded every three minutes and during recovery.

Results:In all the subjects, physical exhaustion of the forearms defined the end point of the climbing ergometry. Blood lactate increased with physical stress, reaching a mean of 3.48 mmol/l. Compartment pressure was related to physical stress, exceeding 30 mm Hg in only three subjects. A critical pressure of more than 40 mm Hg was never observed. After the test, the pressure decreased to normal levels within three minutes in seven subjects. The three with higher pressure levels (>30 mm Hg) required a longer time to recover.

Conclusions:For further clinical and therapeutic consequences, an algorithm was derived. Basic pressure below 15 mm Hg and stress pressure below 30 mm Hg as well as pressures during the 15 minute recovery period below 15 mm Hg are physiological. Pressures of 15–30 mm Hg during recovery suggest high risk of CECS, and pressures above 30 mm Hg confirm CECS.