bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Cell-Based Method To Detect Shiga Toxin 2 from
Escherichia coli
O157:H7 and Inhibitors of Toxin Activity
Authors: Quiñones Beatriz , Massey Shane , Friedman Mendel , Swimley Michelle S. , Teter Ken 
Published: January 2009

ABSTRACT

Escherichia coli
O157:H7 is a leading cause of food-borne illness. This human pathogen produces Shiga toxins (Stx1 and Stx2) which inhibit protein synthesis by inactivating ribosome function. The present study describes a novel cell-based assay to detect Stx2 and inhibitors of toxin activity. A Vero cell line harboring a destabilized variant (half-life, 2 h) of the enhanced green fluorescent protein (d2EGFP) was used to monitor the toxin-induced inhibition of protein synthesis. This Vero-d2EGFP cell line produced a fluorescent signal which could be detected by microscopy or with a plate reader. However, a greatly attenuated fluorescent signal was detected in Vero-d2EGFP cells that had been incubated overnight with either purified Stx2 or a cell-free culture supernatant from Stx1- and Stx2-producing
E. coli
O157:H7. Dose-response curves demonstrated that the Stx2-induced inhibition of enhanced green fluorescent protein fluorescence mirrored the Stx2-induced inhibition of overall protein synthesis and identified a picogram-per-milliliter threshold for toxin detection. To establish our Vero-d2EGFP assay as a useful tool for the identification of toxin inhibitors, we screened a panel of plant compounds for antitoxin activities. Fluorescent signals were maintained when Vero-d2EGFP cells were exposed to Stx1- and Stx2-containing medium in the presence of either grape seed or grape pomace extract. The antitoxin properties of the grape extracts were confirmed with an independent toxicity assay that monitored the overall level of protein synthesis in cells treated with purified Stx2. These results indicate that the Vero-d2EGFP fluorescence assay is an accurate and sensitive method to detect Stx2 activity and can be utilized to identify toxin inhibitors.
Identification and Characterization of Lactocyclicin Q, a Novel Cyclic Bacteriocin Produced by
Lactococcus
sp. Strain QU 12
Authors: Sawa Naruhiko , Zendo Takeshi , Kiyofuji Junko , Fujita Koji , Himeno Kohei , Nakayama Jiro , Sonomoto Kenji 
Published: January 2009

ABSTRACT

Lactococcus
sp. strain QU 12, which was isolated from cheese, produced a novel cyclic bacteriocin termed lactocyclicin Q. By using cation-exchange chromatography, hydrophobic interaction chromatography, and reverse-phase high-performance liquid chromatography, lactocyclicin Q was purified from culture supernatant, and its molecular mass was determined to be 6,062.8 Da by mass spectrometry. Lactocyclicin Q has been characterized by its unique antimicrobial spectrum, high level of protease resistance, and heat stability compared to other reported bacteriocins of lactic acid bacteria. The amino acid sequence of lactocyclicin Q was determined chemically, and this compound is composed of 61 amino acid residues that have a cyclic structure with linkage between the N and C termini by a peptide bond. It showed no homology to any other antimicrobial peptide, including cyclic bacteriocins. On the basis of the amino acid sequences obtained, the sequence of the gene encoding the prepeptide lactocyclicin Q was obtained. This is the first report of a cyclic bacteriocin purified from a strain belonging to the genus
Lactococcus
.
Sequencing and Analysis of Fungal rRNA Operons for Development of Broad-Range Fungal PCR Assays
Authors: Khot Prasanna D. , Ko Daisy L. , Fredricks David N. 
Published: January 2009

ABSTRACT
rRNA genes are attractive targets for developing PCR assays targeting human fungal pathogens. Most studies have focused on the 18S rRNA gene, internal transcribed spacers, and the 5′ end of the 28S rRNA gene. An approximately 2,900-bp region of the 28S rRNA gene remains largely unexplored because sequences of many medically relevant fungi are either unavailable or undefined in genomic databases. The internal transcribed spacers and 28S rRNA gene of nine medically and phylogenetically important fungi were sequenced. In addition, 42 sequences from this region were acquired from public databases, resulting in an alignment of 51 fungal sequences spanning 30 fungal genera. For the nearly 3,950-bp region from the 3′ end of 18S rRNA gene to the 3′ end of the 28S rRNA gene, 27 broad-range PCR primers were designed such that their sequence homology with the human rRNA gene was minimal. All 62 possible amplicons in the size range from 75 to 400 bp from 27 primers were screened using fungal genomic DNA from 26 species spanning 14 genera. Eleven of the 62 amplicons did not cross-react with 1 μg/PCR human DNA but simultaneously amplified 10 fg of fungal DNA. Phylogenetic distance matrices were calculated for regions covered by these 11 amplicons based on 51 fungi. Two of these 11 amplicons successfully amplified 30 fg of fungal DNA from 25 of 26 fungi and provided the most phylogenetic information for species identification based on the distance matrices. These PCR assays hold promise for detection and identification of fungal pathogens in human tissues.
Campylobacter jejuni
Drives MyD88-Independent Interleukin-6 Secretion via Toll-Like Receptor 2
Authors: Friis Lorna M. , Keelan Monika , Taylor Diane E. 
Published: January 2009

ABSTRACT

Gastrointestinal disease caused by
Campylobacter jejuni
is characterized by localized inflammation and the destruction of the epithelial cell barrier that forms host innate protection against pathogens. This can lead to an imbalance in fluid transport across the gastrointestinal tract, resulting in severe diarrhea. The mechanisms of host cell receptor recognition of
C. jejuni
and downstream immune signaling pathways leading to this inflammatory disease, however, remain unclear. The aim of this study was to analyze the mechanisms involved in
C. jejuni
induction of the acute-phase inflammatory response regulator interleukin-6 (IL-6). Polarized intestinal epithelial Caco-2 monolayers responded to infections with
Salmonella enterica
serovar Typhimurium and eight isolates of
C. jejuni
by an increase in levels of expression and secretion of IL-6. No such IL-6 response, however, was produced upon infection with the human commensal organism
Lactobacillus rhamnosus
GG. The IL-6 signaling pathway was further characterized using short interfering RNA complexes to block gene expression. The inhibition of myeloid differentiation primary response protein 88 (MyD88) expression in this manner did not affect
C. jejuni
-induced IL-6 secretion, suggesting a MyD88-independent route to IL-6 signal transduction in
C. jejuni
-infected human epithelial cells. However, a significant reduction in levels of IL-6 was evident in the absence of Toll-like receptor 2 (TLR-2) expression, implying a requirement for TLR-2 in
C. jejuni
recognition. Caco-2 cells were also treated with heat-inactivated and purified membrane components of
C. jejuni
to isolate the factor responsible for triggering IL-6 signaling. The results demonstrate that
C. jejuni
surface polysaccharides induce IL-6 secretion from intestinal epithelial cells via TLR-2 in a MyD88-independent manner.
Evidence for Multiple B- and T-Cell Epitopes inPlasmodium falciparumLiver-Stage Antigen 3
Authors: Toure-Balde Aissatou , Perlaza Blanca-Liliana , Sauzet Jean-Pierre , Ndiaye Mouhamadou , Aribot Georgette , Tall Adama , Sokhna Cheikh , Rogier Christophe , Corradin Giampietro , Roussilhon Christian , Druilhe Pierre 
Published: January 2009

ABSTRACTLiver-stage antigen 3 (LSA-3) is a new vaccine candidate that can induce protection againstPlasmodium falciparumsporozoite challenge. Using a series of long synthetic peptides (LSP) encompassing most of the 210-kDa LSA-3 protein, a study of the antigenicity of this protein was carried out in 203 inhabitants from the villages of Dielmo (n= 143) and Ndiop (n= 60) in Senegal (the level of malaria transmission differs in these two villages). Lymphocyte responses to each individual LSA-3 peptide were recorded, some at high prevalences (up to 43%). Antibodies were also detected to each of the 20 peptides, many at high prevalence (up to 84% of responders), and were directed to both nonrepeat and repeat regions. Immune responses to LSA-3 were detectable even in individuals of less than 5 years of age and increased with age and hence exposure to malaria, although they were not directly related to the level of malaria transmission. Thus, several valuable T- and B-cell epitopes were characterized all along the LSA-3 protein, supporting the antigenicity of thisP. falciparumvaccine candidate. Finally, antibodies specific for peptide LSP10 located in a nonrepeat region of LSA-3 were found significantly associated with a lower risk of malaria attack over 1 year of daily clinical follow-up in children between the ages of 7 and 15 years, but not in older individuals.
Regulation of the
Vibrio vulnificus hupA
Gene by Temperature Alteration and Cyclic AMP Receptor Protein and Evaluation of Its Role in Virulence
Authors: Oh Man Hwan , Lee Sung Min , Lee Dong Hwan , Choi Sang Ho 
Published: January 2009

ABSTRACT

Availability of free iron is extremely limited in the mammalian host, and the acquisition of iron in the host is essential for successful infection by pathogenic bacteria. Expression of many genes involved in acquiring iron is regulated in response to the level of iron availability, and iron regulation is mediated by Fur. In this study, cellular levels of
Vibrio vulnificus
HupA, a heme receptor protein, and the
hupA
transcript were found to increase in cells grown at 40°C compared to cells grown at 30°C. The results suggested that change in growth temperature, in addition to iron availability, is an environmental cue controlling the expression of the
hupA
gene. The influence of global regulatory proteins on the expression of
hupA
was examined, and the cyclic AMP receptor protein (CRP) was found to activate the expression of
hupA
at the transcriptional level. CRP exerts its effects by directly binding to DNA upstream of the
hupA
promoter P

hupA

, and a CRP binding site, centered at 174 bp upstream of the transcription start site, was identified by a DNase I protection assay. Finally, a
hupA
mutant showed reduced virulence in mice and in tissue cultures, in which growth of the
hupA
mutant was impaired, indicating that HupA of
V. vulnificus
is essential for survival and multiplication during infection.
Genetic Polymorphisms of Mannose-Binding Lectin Do Not Influence Placental Malaria but Are Associated with Preterm Deliveries
Authors: Thévenon Audrey D. , Leke Rose G. F. , Suguitan Amorsolo L. , Zhou James A. , Taylor Diane Wallace 
Published: January 2009

ABSTRACTDuring pregnancy,Plasmodium falciparum-infected erythrocytes (IE) sequester in the placenta where they induce pathology and increase the risk of low-birth-weight (LBW) babies. The innate immune mediator, mannose-binding lectin (MBL), enhances phagocytosis of pathogens. Since MBL is reported to bind to IE, we hypothesized that it might aid in clearance of IE from the placenta, thereby reducing the risk of LBW babies. To test this hypothesis, molecular genotyping was used to detect polymorphisms at codon 57 (A/C) in exon 1 ofMBL2in 401 pregnant Cameroonian women, with or without placental malaria, who had LBW and normal-weight babies. Polymorphisms in the promoter region at positions −550 (H/L), −221 (X/Y), and +4 (P/Q) were also determined, and plasma MBL levels were measured during pregnancy and at delivery. The expected correlation between genotype and plasma MBL levels was confirmed. However, asymptomatic infections were not associated with an increase in MBL levels in the peripheral blood, and MBL levels were similar in the placental and cord blood of women with or without placental malaria at delivery. There was no evidence that MBL levels at delivery were associated with malaria-related poor pregnancy outcomes. Women with the LXPA haplotype, however, were more likely to have LBW babies, but the risk was not related to malaria. These results do not support the hypothesis that MBL aids in the clearance of parasites from the placenta but suggest that Cameroonian women with LXPA are at risk of having LBW babies due to other causes.
Effect of Chlamydiaphage φCPG1 on the Course of Conjunctival Infection with “
Chlamydia caviae
” in Guinea Pigs
Authors: Rank Roger G. , Bowlin Anne K. , Cané Stefania , Shou Huizhong , Liu Zhi , Nagarajan Uma M. , Bavoil Patrik M. 
Published: January 2009

ABSTRACT

Over the last several years, four different phages of chlamydiae, in addition to a phage associated with
Chlamydia psittaci
isolated from an ornithosis infection in ducks over 25 years ago, have been described and characterized. While these phages and their chlamydial host specificities have been characterized in vitro, there is virtually nothing known about the interaction of the phage with chlamydiae in their natural animal host. φCPG1 is a lytic phage specific for “
Chlamydia caviae
,” which is a natural parasite of the guinea pig. In this study, guinea pigs were inoculated in the conjunctiva with suspensions of φCPG1 and
C. caviae
and the effect on the development of pathology and on the course of chlamydial infection in the conjunctiva was determined. The presence of phage delayed the appearance of the peak level of chlamydiae in the animal and decreased the pathological response. Evidence for replication of the phage in
C. caviae
in the conjunctival tissue was observed. Modifying the ratio of phage to chlamydiae altered the course of infection and affected phage replication. There was no evidence for the phage increasing the virulence of
C. caviae
infection.
Role of Complement in Host Defense against Pneumococcal Otitis Media
Authors: Sabharwal Vishakha , Ram Sanjay , Figueira Marisol , Park In Ho , Pelton Stephen I. 
Published: January 2009

ABSTRACTStrategies to limit complement deposition onStreptococcus pneumoniaeare established as virulence features for invasive disease, but their role in respiratory tract infection requires further analysis. We evaluated complement C3 protein deposition on discordantS. pneumoniaeisolates of the same serotype (6A) and their capacity to cause nasopharyngeal (NP) colonization and experimental otitis media (EOM) in an animal model. We compared C3 binding to five 6A isolates from asymptomatic NP carriers with five 6A strains that caused invasive disease, and we observed less C3 (∼10-fold less fluorescence) binding to invasive isolates. We selected two high-level C3-binding carriage and two low-level C3-binding invasive 6A isolates for further study. In the EOM model, 11/12 (92%) ears challenged with a low-level C3-binding 6A strain became infected. Only 2/8 (25%) ears challenged with the discordant high-level C3-binding 6A isolate developed disease (P= 0.005). Results with the second discordant 6A isolate pair were comparable. Cobra venom factor (CoVF) treatment, which depletes C3 and consumes complement, restored virulence of the high-level C3-binding strain; 8/8 (100%) ears in CoVF-treated animals developed EOM compared to only 25% of ears in naïve animals (P= 0.007). These studies demonstrate the critical role for complement evasion in pneumococcal EOM. Colonization with carriage isolates that bound high levels of C3 caused EOM in fewer animals compared to low-level C3-binding invasive strains. Thus, limiting C3 deposition on the surface ofS. pneumoniaecorrelates with increased incidence of EOM following NP colonization and barotrauma in the animal model.
Sex differences in self-reported symptoms after aerobic exercise in non-injured athletes: implications for concussion management programmes
Authors: Gaetz M B , Iverson G L 
Published: January 2009

Background:After a concussion, when symptoms have decreased substantially at rest, it is recommended that athletes begin light aerobic exercise before progressing to sport specific exercise. The British Columbia Concussion Rehabilitation Programme (BC-CRP) uses a standardized cognitive and exercise test protocol designed to indicate when an athlete should progress to sport-specific exercise after a concussion.Objective:To document the effects of exercise on symptom reporting in healthy, uninjured, male and female amateur athletes.Design:Quasi-experimental, pretest–post-test, nonequivalent groups design.Methods:Before the exercise protocol, 45 female and 30 male young amateur athletes completed computerized cognitive testing, symptom ratings and balance testing. The 15-minute cycle ergometry protocol, conducted at 90 revolutions/minute, was as follows: 0–2 minutes at 0 W tension, 2–5 minutes at 50 W, 5–8 minutes at 100 W, 8–11 minutes at 150 W and 11–14 minutes at 200 W tension followed by a 1-minute cooling-down period. After exercise, participants completed symptom ratings, balance testing and perceived exertion ratings. Self-reported symptoms were assessed using an abbreviated version of the Post-Concussion Scale.Results:Significant increases in self-reported balance problems, numbness and tingling were seen for both genders after aerobic exercise. For women, emotional symptoms such as irritability, sadness, nervousness and feeling more emotional decreased significantly after aerobic exercise. Headache also decreased in the women, but no significant change was seen in the men.Conclusions:Sex differences exist for symptom reporting after aerobic exercise. Both genders report increases in somatic symptoms, but only women report decreases in emotional symptoms. The concept of being “asymptomatic” after exercise should be reconsidered to include expected mild increases and decreases in certain symptoms.
Contribution of frequency-augmented inward Ca2+current to myocardial contractility
Authors: Parilak Leonard D. , Taylor David G. , Song Yejia , Burkart Thomas , Shryock John C. , Curtis Anne B. , Knot Harm J. 
Published: January 2009

The sarcoplasmic reticular Ca2+pump (SERCA) is thought to be the primary determinant of heart rate-dependent increases in myocardial contractile [Ca2+]iand force (force–frequency relationship (FFR)), an important mechanism to increase cardiac output. This report demonstrates a rate-dependent role for inward Ca2+current (ICa) in the human and rat FFR. Human action potential plateau height increased linearly with contractility when heart rate increased in vivo, as measured by monophasic action potential catheter and echocardiography. Rat rate-dependent developed force and cytosolic [Ca2+]itransients were quantified in isolated left ventricular papillary muscles, and ICaand action potential duration in cardiomyocytes. ICaand SERCA measurements better reflected [Ca2+]iand force transients than SERCA activity alone. These data support a direct and (or) indirect contribution to myocardial contractility by ICaat heart rates from approximately 1 to 3–4 Hz (60 to 180–240 bpm) in tandem with SERCA to sustain the typical ‘bell shape’ of the FFR across species.
Chronic treatment with angiotensin AT1receptor antagonists reduced serum but not bone TGF-β1levels in ovariectomized rats
Authors: Li Yong-Qi , Ji Hui , Shen Yang , Ding Li-Ju , Zhuang Pei , Yang Yu-Lin , Huang Qiu-Ju 
Published: January 2009

Approximately 50% of hypertensive patients are postmenopausal women; therefore, any antihypertensive therapy must not adversely affect bone loss in this population. Recently, however, concern has been raised that use of angiotensin AT1receptor antagonists may increase the tendency to develop postmenopausal osteoporosis by decreasing transforming growth factor-β1(TGF-β1), which has been implicated in bone mass maintenance. In the present study, we selected telmisartan and valsartan as representatives of angiotensin AT1receptor antagonists and used ovariectomized (OVX) rats as a model of human postmenopausal osteoporosis. After 3 months treatment with telmisartan (5 mg/kg daily) or valsartan (10 mg/kg daily), OVX rats showed no signs of adverse effects on bone mineral density of the lumbar vertebrae (L1–L5) or the total femur, nor did treatment affect serum levels of osteocalcin and osteoclast-derived tartrate-resistant acid phosphatase (TRACP-5b). Bone TGF-β1content remained unchanged, although treatment with telmisartan and valsartan significantly reduced serum TGF-β1levels (p < 0.05). In conclusion, chronic treatment with angiotensin AT1receptor antagonists reduced serum but not bone TGF-β1levels and did not accelerate ovariectomy-induced bone loss in rats.
Sirt1 hyperexpression in SHR heart related to left ventricular hypertrophy
Authors: Li Ling , Zhao Lei , Yi-Ming Wuliya , Yu Yong-Sheng , Xia Chun-Yan , Duan Jun-Li , Su Ding-Feng 
Published: January 2009

Sirt1 is a human homologue of the silent information regulator factor 2 (Sir2) and has an NAD+-dependent histone deacetylase activity. This protein is reported to have a pathogenetic role in muscle differentiation, diabetic nephropathy, and heart failure. In this study, we investigated the expression of sirt1 in spontaneously hypertensive rat (SHR) to obtain insight into the function of sirt1 in hypertensive cardiovascular hypertrophy. The gene and protein expression of sirt1 was increased in the heart in SHR compared with normotensive WKY rats. Sirt1 mRNA was not different in the aorta between SHR and WKY rats. Sirt1 mRNA expression in heart and aorta was not related to hemodynamic parameters in SHR. Hypertensive left ventricular hypertrophy was significantly and positively related to the expression of heart tissue sirt1 mRNA in SHR. Aortic hypertrophy, however, was not related to sirt1 mRNA in the aorta. The increased sirt1 protein expression was accompanied by severe cardiac hypertrophy in older SHR. These results suggest that the increase of sirt1 gene and protein expression in the heart was associated with cardiac hypertrophy.
Diethyl dithiocarbamic acid, a possible nuclear factor kappa B inhibitor, attenuates ischemic postconditioning-induced attenuation of cerebral ischemia–reperfusion injury in mice
Authors: Rehni Ashish K. , Bhateja Pradeep , Singh Nirmal 
Published: January 2009

The present study was designed to pharmacologically investigate the possible role of nuclear factor kappa B (NF-κB) in the reversal of global cerebral injury induced by ischemia and reperfusion after ischemic postconditioning. Bilateral carotid artery occlusion for 17 min followed by reperfusion for 24 h was employed to produce ischemia- and reperfusion-induced cerebral injury in mice. Cerebral infarct size was measured by using triphenyltetrazolium chloride staining. Memory was evaluated using the Morris water maze test. The rotarod test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced a marked increase in cerebral infarct size, impairment of memory, and motor coordination. A set of 5 episodes of carotid artery occlusion for a period of 10 s and reperfusion of 10 s (ischemic postconditioning) significantly prevented ischemia–reperfusion-induced cerebral infarct size and behavioral deficits measured in terms of loss of memory and motor coordination. Diethyl dithiocarbamic acid sodium salt trihydrate (DDA) (100 mg/kg, i.p.), an inhibitor of NF-κB, given 30 min before ischemia attenuated the beneficial effects of ischemic postconditioning. It may be concluded that the beneficial effects of ischemic postconditioning on global cerebral ischemia- and reperfusion-induced cerebral injury and behavioral deficits may involve activation of the NF-κB-linked pathway.