bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

ABSTRACTInfection 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

ABSTRACTAnaplasma 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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACTN19, 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

ABSTRACT

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

ABSTRACTThe 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

ABSTRACT

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

ABSTRACT

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.