bluuebunny/crossref_metadata_2025_split huggingface dataset:
Osteopontin plays an anti‐nucleation role in cholesterol gallstone formation
Authors: Yang Lin , Chen Jin‐Hong , Cai Duan , Wang Li‐Ying , Zha Xi‐Liang 
Published: March 2011

Aim:  To investigate the role of osteopontin in cholesterol gallstone formation.Methods:  Nucleation time was determined in model and human gallbladder bile in vitro. Effect of osteopontin on vesicles of bile was investigated via transmission electron microscopy. The mRNA and protein expression of osteopontin were detected in human calculus and normal gallbladder tissues, and then lipid compositions of human bile were determined via commercial kits.Results:  Osteopontin could prolong the nucleation time in a dose‐dependent manner, and inhibit the pro‐nucleation effect induced by calcium ion. Cholesterol crystal growth was inhibited by osteopontin in a dose‐dependent manner in model and human gallbladder bile, but not affected by calcium. Furthermore, the formation, aggregation and fusion of vesicles were suppressed by osteopontin in model and human bile as demonstrated by transmission electron microscopy. The mRNA and protein expression of osteopontin in calculus gallbladder tissues were lower than those in normal tissues. The concentrations of cholesterol, phospholipid and bile acids, and cholesterol saturated index were higher and the contents of osteopontin and calcium, nevertheless, were found to be lower in lithogenic bile than those in normal controls.Conclusion:  These findings indicated that osteopontin could inhibit the cholesterol gallstone formation as an anti‐nucleation factor, which may be involved in the pathogenesis of cholesterol gallstone formation.
Holter Monitoring in Clinically Healthy Cavalier King Charles Spaniels, Wire‐Haired Dachshunds, and Cairn Terriers
Authors: Rasmussen C.E. , Vesterholm S. , Ludvigsen T.P. , Häggström J. , Pedersen H.D. , Moesgaard S.G. , Olsen L.H. 
Published: March 2011

Background:Few reported studies describe normal values from 24‐hour ECG (Holter) recordings of small breed dogs.Objectives:To investigate influence of breed, age, sex, body weight, degree of recording artifact, and mitral valve prolapse (MVP) on Holter recordings of 3 breeds of small dogs that have differing predispositions for myxomatous mitral valve disease. The study also assessed if heart rate (HR) at clinical examination (HRex) was associated with HR during Holter monitoring and evaluated the reproducibility of Holter variables.Animals:Fifty clinically healthy, privately owned dogs of the breeds Cavalier King Charles Spaniel (CKCS), Wire‐haired Dachshund (wD), or Cairn Terrier (CT).Methods:Prospective, longitudinal observational study. Dogs were recruited for clinical examination, echocardiography, and Holter monitoring. In 8 CKCS, Holter recordings were performed twice with a 7‐day interval. Arrhythmia and heart rate variability (HRV) analysis (time and frequency domain analysis) were performed on Holter recordings.Results:Fifteen out of 27 Holter derived variables were significantly associated with breed (P< .03), but not with age (P> .7), sex (P> .2), body weight (P> .7), degree of recording artifact (P> .4), or MVP (P> .6). During Holter recording, minimum (P= .0001) and mean HR (P= .0001) were higher in CKCS compared with wD. CKCS had significantly lower values than wD, CT, or both in 10 out of 13 HRV variables (P< .03). Minimum and mean HR during Holter recording were correlated with HRex (r= 0.55,P= .0003). HR and time domain variables had a coefficient of variation <10%.Conclusions and Clinical Importance:There is an influence of breed on Holter‐derived variables in 3 breeds of small dogs. Arrhythmia and HRV analysis can be performed on 24‐hour ambulatory ECG (Holter) recordings. Arrhythmia analysis includes HR measurements and identification of arrhythmias.
Novel Model for Multispecies Biofilms That Uses Rigid Gas-Permeable Lenses
Authors: Peyyala Rebecca , Kirakodu Sreenatha S. , Ebersole Jeffrey L. , Novak Karen F. 
Published: March 2011

ABSTRACT

Oral biofilms comprise complex multispecies consortia aided by specific inter- and intraspecies interactions occurring among commensals and pathogenic bacterial species. Oral biofilms are primary initiating factors of periodontal disease, although complex multifactorial biological influences, including host cell responses, contribute to the individual outcome of the disease. To provide a system to study initial stages of interaction between oral biofilms and the host cells that contribute to the disease process, we developed a novel
in vitro
model system to grow biofilms on rigid gas-permeable contact lenses (RGPLs), which enable oxygen to permeate through the lens material. Bacterial species belonging to early- and late-colonizing groups were successfully established as single- or three-species biofilms, with each group comprising
Streptococcus gordonii
,
Streptococcus oralis
, and
Streptococcus sanguinis
;
S. gordonii
,
Actinomyces naeslundii
, and
Fusobacterium nucleatum
; or
S. gordonii
,
F. nucleatum
, and
Porphyromonas gingivalis
. Quantification of biofilm numbers by quantitative PCR (qPCR) revealed substantial differences in the magnitude of bacterial numbers in single-species and multispecies biofilms. We evaluated cell-permeable conventional nucleic acid stains acridine orange, hexidium iodide, and Hoechst 33258 and novel SYTO red, blue, and green fluorochromes for their effect on bacterial viability and fluorescence yield to allow visualization of the aggregates of individual bacterial species by confocal laser scanning microscopy (CLSM). Substantial differences in the quantity and distribution of the species in the multispecies biofilms were identified. The specific features of these biofilms may help us better understand the role of various bacteria in local challenge of oral tissues.
Protection of Arabidopsis thaliana against Leaf-Pathogenic Pseudomonas syringae by Sphingomonas Strains in a Controlled Model System
Authors: Innerebner Gerd , Knief Claudia , Vorholt Julia A. 
Published: March 2011

ABSTRACT

Diverse bacterial taxa live in association with plants without causing deleterious effects. Previous analyses of phyllosphere communities revealed the predominance of few bacterial genera on healthy dicotyl plants, provoking the question of whether these commensals play a particular role in plant protection. Here, we tested two of them,
Methylobacterium
and
Sphingomonas
, with respect to their ability to diminish disease symptom formation and the proliferation of the foliar plant pathogen
Pseudomonas syringae
pv. tomato DC3000 on
Arabidopsis thaliana
. Plants were grown under gnotobiotic conditions in the absence or presence of the potential antagonists and then challenged with the pathogen. No effect of
Methylobacterium
strains on disease development was observed. However, members of the genus
Sphingomonas
showed a striking plant-protective effect by suppressing disease symptoms and diminishing pathogen growth. A survey of different
Sphingomonas
strains revealed that most plant isolates protected
A. thaliana
plants from developing severe disease symptoms. This was not true for
Sphingomonas
strains isolated from air, dust, or water, even when they reached cell densities in the phyllosphere comparable to those of the plant isolates. This suggests that plant protection is common among plant-colonizing
Sphingomonas
spp. but is not a general trait conserved within the genus
Sphingomonas
. The carbon source profiling of representative isolates revealed differences between protecting and nonprotecting strains, suggesting that substrate competition plays a role in plant protection by
Sphingomonas
. However, other mechanisms cannot be excluded at this time. In conclusion, the ability to protect plants as shown here in a model system may be an unexplored, common trait of indigenous
Sphingomonas
spp. and may be of relevance under natural conditions.
Production of Hydrogen from α-1,4- and β-1,4-Linked Saccharides by Marine Hyperthermophilic Archaea
Authors: Oslowski Daniel M. , Jung Jong-Hyun , Seo Dong-Ho , Park Cheon-Seok , Holden James F. 
Published: March 2011

ABSTRACT

Nineteen hyperthermophilic heterotrophs from deep-sea hydrothermal vents, plus the control organism
Pyrococcus furiosus
, were examined for their ability to grow and produce H
2
on maltose, cellobiose, and peptides and for the presence of the genes encoding proteins that hydrolyze starch and cellulose. All of the strains grew on these disaccharides and peptides and converted maltose and peptides to H
2
even when elemental sulfur was present as a terminal electron acceptor. Half of the strains had at least one gene for an extracellular starch hydrolase, but only
P. furiosus
had a gene for an extracellular β-1,4-endoglucanase.
P. furiosus
was serially adapted for growth on CF11 cellulose and H
2
production, which is the first reported instance of hyperthermophilic growth on cellulose, with a doubling time of 64 min. Cell-specific H
2
production rates were 29 fmol, 37 fmol, and 54 fmol of H
2
produced cell
−1
doubling
−1
on α-1,4-linked sugars, β-1,4-linked sugars, and peptides, respectively. The highest total community H
2
production rate came from growth on starch (2.6 mM H
2
produced h
−1
). Hyperthermophilic heterotrophs may serve as an important alternate source of H
2
for hydrogenotrophic microorganisms in low-H
2
hydrothermal environments, and some are candidates for H
2
bioenergy production in bioreactors.
Link between Genotype and Antimicrobial Resistance in Bovine Mastitis-Related Staphylococcus aureus Strains, Determined by Comparing Swiss and French Isolates from the Rhône Valley
Authors: Sakwinska Olga , Morisset Delphine , Madec Jean-Yves , Waldvogel Andreas , Moreillon Philippe , Haenni Marisa 
Published: March 2011

ABSTRACT

Staphylococcus aureus
is a major bovine mastitis pathogen. Although the reported antimicrobial resistance was generally low, the emergence of new genetic clusters in bovine mastitis requires examination of the link between antimicrobial resistance and genotypes. Here, amplified fragment length polymorphism (AFLP) profiles and standard antimicrobial resistance profiles were determined in order to characterize a total of 343
S. aureus
cow mastitis isolates from two geographically close regions of Switzerland and France. AFLP profiles revealed similar population compositions in the two regions, with 4 major clusters (C8, C20, C97, and C151), but the proportions of isolates in each cluster significantly diverged between the two countries (
P
= 9.2 × 10
−9
). Antimicrobial resistance was overall low (<5% resistance to all therapeutically relevant molecules), with the exception of penicillin resistance, which was detected in 26% of the isolates. Penicillin resistance proportions differed between clusters, with only 1 to 2% of resistance associated with C20 and C151 and up to 70% associated with bovine C97. The prevalence of C20 and C8 was unexpectedly high and requires further investigation into the mechanism of adaptation to the bovine host. The strong association of penicillin resistance with few clusters highlights the fact that the knowledge of local epidemiology is essential for rational choices of antimicrobial treatment in the absence of susceptibility testing. Taken together, these observations argue in favor of more routine scrutiny of antimicrobial resistance and antibiotic-resistant clones in cattle and the farm environment.
Cyclopropanation of Membrane Unsaturated Fatty Acids Is Not Essential to the Acid Stress Response of Lactococcus lactis subsp. cremoris
Authors: To Thi Mai Huong , Grandvalet Cosette , Tourdot-Maréchal Raphaëlle 
Published: March 2011

ABSTRACT

Cyclopropane fatty acids (CFAs) are synthetized
in situ
by the transfer of a methylene group from
S
-adenosyl-
l
-methionine to a double bond of unsaturated fatty acid chains of membrane phospholipids. This conversion, catalyzed by the Cfa synthase enzyme, occurs in many bacteria and is recognized to play a key role in the adaptation of bacteria in response to a drastic perturbation of the environment. The role of CFAs in the acid tolerance response was investigated in the lactic acid bacterium
Lactococcus lactis
MG1363. A mutant of the
cfa
gene was constructed by allelic exchange. The
cfa
gene encoding the Cfa synthase was cloned and introduced into the mutant to obtain the complemented strain for homologous system studies. Data obtained by gas chromatography (GC) and GC-mass spectrometry (GC-MS) validated that the mutant could not produce CFA. The CFA levels in both the wild-type and complemented strains increased upon their entry to stationary phase, especially with acid-adapted cells or, more surprisingly, with ethanol-adapted cells. The results obtained by performing quantitative reverse transcription-PCR (qRT-PCR) experiments showed that transcription of the
cfa
gene was highly induced by acidity (by 10-fold with cells grown at pH 5.0) and by ethanol (by 9-fold with cells grown with 6% ethanol) in comparison with that in stationary phase. Cell viability experiments were performed after an acidic shock on the mutant strain, the wild-type strain, and the complemented strain, as a control. The higher viability level of the acid-adapted cells of the three strains after 3 h of shock proved that the cyclopropanation of unsaturated fatty acids is not essential for
L. lactis
subsp.
cremoris
survival under acidic conditions. Moreover, fluorescence anisotropy data showed that CFA itself could not maintain the membrane fluidity level, particularly with ethanol-grown cells.
Insights into Physiological and Genetic Mupirocin Susceptibility in Bifidobacteria
Authors: Serafini Fausta , Bottacini Francesca , Viappiani Alice , Baruffini Enrico , Turroni Francesca , Foroni Elena , Lodi Tiziana , van Sinderen Douwe , Ventura Marco 
Published: March 2011

ABSTRACT

Mupirocin is an antibiotic commonly used in selective media for the isolation of bifidobacteria. However, little is known about the genetic traits responsible for bifidobacterial resistance to mupirocin. Our investigation demonstrates that all of the bifidobacteria tested exhibit a phenotype of generally high resistance to this antibiotic. The genotypic reason for bifidobacterial mupirocin resistance was further characterized by sequencing of the isoleucyl-tRNA synthetase gene (
ileS
) coupled with three-dimensional modeling of the encoded protein and cloning of the
ileS
gene of
Bifidobacterium bifidum
PRL2010 in a mupirocin-sensitive
Escherichia coli
strain. These analyses revealed key amino acid residues of the IleS protein that apparently are crucial for conferring a mupirocin resistance phenotype to bifidobacteria.
In Silico
Evidence for the Horizontal Transfer of
gsiB
, a σ
Β
-Regulated Gene in Gram-Positive Bacteria, to Lactic Acid Bacteria
Authors: Asteri Ioanna-Areti , Boutou Effrossyni , Anastasiou Rania , Pot Bruno , Vorgias Constantinos E. , Tsakalidou Effie , Papadimitriou Konstantinos 
Published: March 2011

ABSTRACT

gsiB
, coding for glucose starvation-inducible protein B, is a characteristic member of the σ
Β
stress regulon of
Bacillus subtilis
and several other Gram-positive bacteria. Here we provide
in silico
evidence for the horizontal transfer of
gsiB
in lactic acid bacteria that are devoid of the σ
Β
factor.
Genotypic-Phenotypic Discrepancies between Antibiotic Resistance Characteristics of Escherichia coli Isolates from Calves in Management Settings with High and Low Antibiotic Use
Authors: Davis Margaret A. , Besser Thomas E. , Orfe Lisa H. , Baker Katherine N. K. , Lanier Amelia S. , Broschat Shira L. , New Daniel , Call Douglas R. 
Published: March 2011

ABSTRACT

We hypothesized that bacterial populations growing in the absence of antibiotics will accumulate more resistance gene mutations than bacterial populations growing in the presence of antibiotics. If this is so, the prevalence of dysfunctional resistance genes (resistance pseudogenes) could provide a measure of the level of antibiotic exposure present in a given environment. As a proof-of-concept test, we assayed field strains of
Escherichia coli
for their resistance genotypes using a resistance gene microarray and further characterized isolates that had resistance phenotype-genotype discrepancies. We found a small but significant association between the prevalence of isolates with resistance pseudogenes and the lower antibiotic use environment of a beef cow-calf operation versus a higher antibiotic use dairy calf ranch (Fisher's exact test,
P
= 0.044). Other significant findings include a very strong association between the dairy calf ranch isolates and phenotypes unexplained by well-known resistance genes (Fisher's exact test,
P
< 0.0001). Two novel resistance genes were discovered in
E. coli
isolates from the dairy calf ranch, one associated with resistance to aminoglycosides and one associated with resistance to trimethoprim. In addition, isolates resistant to expanded-spectrum cephalosporins but negative for
bla
CMY-2
had mutations in the promoter regions of the chromosomal
E. coli
ampC
gene consistent with reported overexpression of native AmpC beta-lactamase. Similar mutations in hospital
E. coli
isolates have been reported worldwide. Prevalence or rates of
E. coli
ampC
promoter mutations may be used as a marker for high expanded-spectrum cephalosporin use environments.
Mechanisms of Resistance to Bacteriocins Targeting the Mannose Phosphotransferase System
Authors: Kjos Morten , Nes Ingolf F. , Diep Dzung B. 
Published: March 2011

ABSTRACT

The membrane proteins IIC and IID of the mannose phosphotransferase system (Man-PTS) together form a membrane-located complex that serves as a receptor for several different bacteriocins, including the pediocin-like class IIa bacteriocins and the class IIc bacteriocin lactococcin A. Bacterial strains sensitive to class IIa bacteriocins readily give rise to resistant mutants upon bacteriocin exposure. In the present study, we have therefore investigated lactococcin A-resistant mutants of
Lactococcus lactis
as well as natural food isolates of
Listeria monocytogenes
with different susceptibilities to class IIa bacteriocins. We found two major mechanisms of resistance. The first involves downregulation of Man-PTS gene expression, which takes place both in spontaneous resistant mutants and in natural resistant isolates. The second involves normal expression of the Man-PTS system, but the underlying mechanism of resistance for these cells is unknown. In some cases, the resistant phenotype was linked to a shift in the metabolism; i.e., reduced growth on glucose due to reduction in Man-PTS expression was accompanied by enhanced growth on another sugar, such as galactose. The implications of these findings in terms of metabolic heterogeneity are discussed.
Bacterial Hand Contamination and Transfer after Use of Contaminated Bulk-Soap-Refillable Dispensers
Authors: Zapka Carrie A. , Campbell Esther J. , Maxwell Sheri L. , Gerba Charles P. , Dolan Michael J. , Arbogast James W. , Macinga David R. 
Published: March 2011

ABSTRACT

Bulk-soap-refillable dispensers are prone to extrinsic bacterial contamination, and recent studies demonstrated that approximately one in four dispensers in public restrooms are contaminated. The purpose of this study was to quantify bacterial hand contamination and transfer after use of contaminated soap under controlled laboratory and in-use conditions in a community setting. Under laboratory conditions using liquid soap experimentally contaminated with 7.51 log
10
CFU/ml of
Serratia marcescens
, an average of 5.28 log
10
CFU remained on each hand after washing, and 2.23 log
10
CFU was transferred to an agar surface. In an elementary-school-based field study, Gram-negative bacteria on the hands of students and staff increased by 1.42 log
10
CFU per hand (26-fold) after washing with soap from contaminated bulk-soap-refillable dispensers. In contrast, washing with soap from dispensers with sealed refills significantly reduced bacteria on hands by 0.30 log
10
CFU per hand (2-fold). Additionally, the mean number of Gram-negative bacteria transferred to surfaces after washing with soap from dispensers with sealed-soap refills (0.06 log
10
CFU) was significantly lower than the mean number after washing with contaminated bulk-soap-refillable dispensers (0.74 log
10
CFU;
P
< 0.01). Finally, significantly higher levels of Gram-negative bacteria were recovered from students (2.82 log
10
CFU per hand) than were recovered from staff (2.22 log
10
CFU per hand) after washing with contaminated bulk soap (
P
< 0.01). These results demonstrate that washing with contaminated soap from bulk-soap-refillable dispensers can increase the number of opportunistic pathogens on the hands and may play a role in the transmission of bacteria in public settings.
Investigation of Genotypes of Borrelia burgdorferi in Ixodes scapularis Ticks Collected during Surveillance in Canada
Authors: Ogden N. H. , Margos G. , Aanensen D. M. , Drebot M. A. , Feil E. J. , Hanincová K. , Schwartz I. , Tyler S. , Lindsay L. R. 
Published: March 2011

ABSTRACTThe genetic diversity ofBorrelia burgdorferisensu stricto, the agent of Lyme disease in North America, has consequences for the performance of serological diagnostic tests and disease severity. To investigateB. burgdorferidiversity in Canada, where Lyme disease is emerging, bacterial DNA in 309 infected adultIxodes scapularisticks collected in surveillance was characterized by multilocus sequence typing (MLST) and analysis of outer surface protein C gene (ospC) alleles. Six ticks carriedBorrelia miyamotoi, and one tick carried the novel speciesBorrelia kurtenbachii. 142 ticks carriedB. burgdorferisequence types (STs) previously described from the United States. Fifty-eight ticks carriedB. burgdorferiof 1 of 19 novel or undescribed STs, which were single-, double-, or triple-locus variants of STs first described in the United States. Clonal complexes with founder STs from the United States were identified. SeventeenospCalleles were identified in 309B. burgdorferi-infected ticks. Positive and negative associations in the occurrence of different alleles in the same tick supported a hypothesis of multiple-niche polymorphism forB. burgdorferiin North America. Geographic analysis of STs andospCalleles were consistent with south-to-north dispersion of infected ticks from U.S. sources on migratory birds. These observations suggest that the genetic diversity ofB. burgdorferiin eastern and central Canada corresponds to that in the United States, but there was evidence for founder events skewing the diversity in emerging tick populations. Further studies are needed to investigate the significance of these observations for the performance of diagnostic tests and clinical presentation of Lyme disease in Canada.