bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interspecies competition and inhibition within the oral microbial flora: environmental factors influence the inhibition of Streptococcus mutans by Streptococcus oligofermentans
Authors: Liu Ying , Wu Ligeng , Wu Fei , Chu Lei , Liu Xinxin , Xia Keke , Wang Yinghui 
Published: April 2012

Liu Y, Wu L, Wu F, Chu L, Liu X, Xia K, Wang Y. Interspecies competition and inhibition within the oral microbial flora: environmental factors influence the inhibition of Streptococcus mutans by Streptococcus oligofermentans.  Eur J Oral Sci 2012; 120: 179–184. © 2012 Eur J Oral SciDental caries is a bacterial infectious disease. Streptococcus mutans is the primary pathogen that causes dental caries. Streptococcus oligofermentans is a new oral streptococcal species that can inhibit the growth of S. mutans specifically. The study aimed to assess the inhibition of S. mutans by S. oligofermentans under different oral environmental conditions. The inhibition under different carbohydrate and oxygen conditions was investigated in vitro using an interspecies interaction assay. The 4‐aminoantipyine (4‐ATTP) method was used to measure the yield and the initial production rate of H2O2 in S. oligofermentans. The inhibitory effect was enhanced when the bacteria were cultured with carbohydrates and under aerobic conditions, or when S. oligofermentans was inoculated earlier than S. mutans. The initial synthesis rates of H2O2 by S. oligofermentans were higher in the presence of carbohydrates and in aerobic culture conditions. In terms of the total H2O2 yield, the effect of the environmental conditions was as follows: no carbohydrates > sucrose > glucose, and aerobic conditions > anaerobic conditions. We conclude that the presence of carbohydrate and oxygen significantly affect the ability of S. oligofermentans to inhibit the growth of S. mutans. The difference in inhibitory effect may be attributed to changes in the capacity of S. oligofermentans to produce H2O2.
Resonance frequency analysis: a new diagnostic tool for dental ankylosis
Authors: Bertl Michael H. , Weinberger Thomas , Schwarz Kerstin , Gruber Reinhard , Crismani Adriano G. 
Published: April 2012

Bertl MH, Weinberger T, Schwarz K, Gruber R, Crismani AG. Resonance frequency analysis: a new diagnostic tool for dental ankylosis.   Eur J Oral Sci 2012; 120: 255–258. © 2012 Eur J Oral SciAnkylosed teeth are considered in orthodontic treatment planning; however, diagnostic tools to quantify the rigidity of the tooth‐to‐bone connection are rare. Resonance frequency analysis (RFA) can quantify the rigidity of the dental implant‐to‐bone connection and thus may serve as a potential diagnostic tool to identify ankylosed teeth. To test this assumption, we examined 15 and 30 primary mandibular molars, with and without clinical signs of ankylosis, using the Osstell Mentor system. A cut‐off implant stability quotient (ISQ) of 43 provided a specificity of 100% and a sensitivity of 53.3% when measured in the mesio‐distal direction or a sensitivity of 20% when measured in the bucco‐lingual direction. Based on a receiver–operating characteristic (ROC), the area under the curve (AUC) of 0.807 showed the mesio‐distal direction of measurement to be a test of moderate discriminatory power. Given its non‐invasiveness, RFA may serve as a quantitative diagnostic supplement to the clinical examination of potentially ankylosed primary molars.
Phylogenetic Grouping and Virulence Potential of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains in Cattle
Authors: Valat Charlotte , Auvray Frédéric , Forest Karine , Métayer Véronique , Gay Emilie , Peytavin de Garam Carine , Madec Jean-Yves , Haenni Marisa 
Published: April 2012

ABSTRACT

In line with recent reports of extended-spectrum beta-lactamases (ESBLs) in
Escherichia coli
isolates of highly virulent serotypes, such as O104:H4, we investigated the distribution of phylogroups (A, B1, B2, D) and virulence factor (VF)-encoding genes in 204 ESBL-producing
E. coli
isolates from diarrheic cattle. ESBL genes, VFs, and phylogroups were identified by PCR and a commercial DNA array (Alere, France). ESBL genes belonged mostly to the CTX-M-1 (65.7%) and CTX-M-9 (27.0%) groups, whereas those of the CTX-M-2 and TEM groups were much less represented (3.9% and 3.4%, respectively). One ESBL isolate was
stx
1
and
eae
positive and belonged to a major enterohemorrhagic
E. coli
(EHEC) serotype (O111:H8). Two other isolates were
eae
positive but
stx
negative; one of these had serotype O26:H11. ESBL isolates belonged mainly to phylogroup A (55.4%) and, to lesser extents, to phylogroups D (25.5%) and B1 (15.6%), whereas B2 strains were quasi-absent (1/204). The number of VFs was significantly higher in phylogroup B1 than in phylogroups A (
P
= 0.04) and D (
P
= 0.02). Almost all of the VFs detected were found in CTX-M-1 isolates, whereas only 64.3% and 33.3% of them were found in CTX-M-9 and CTX-M-2 isolates, respectively. These results indicated that the widespread dissemination of the
bla
CTX-M
genes within the
E. coli
population from cattle still spared the subpopulation of EHEC/Shiga-toxigenic
E. coli
(STEC) isolates. In contrast to other reports on non-ESBL-producing isolates from domestic animals, B1 was not the main phylogroup identified. However, B1 was found to be the most virulent phylogroup, suggesting host-specific distribution of virulence determinants among phylogenetic groups.
Biotransformation Strategy To Reduce Allergens in Propolis
Authors: Gardana Claudio , Barbieri Andrea , Simonetti Paolo , Guglielmetti Simone 
Published: April 2012

ABSTRACT

Propolis (bee glue) is a resinous, sticky, dark-colored material produced by honeybees. Propolis today, due to its medicinal properties, is increasingly popular and is extensively used in food, beverages, and cosmetic products. Besides its numerous positive properties, propolis may also have adverse effects, such as, principally, allergic eczematous contact dermatitis in apiarists and in consumers with an allergic predisposition. In this study, we found appropriate conditions for removing caffeate esters, which are the main allergenic components, from raw propolis. The proposed method consists of the resuspension of propolis in a food grade solvent, followed by a biotransformation based on the cinnamoyl esterase activity of
Lactobacillus helveticus
. We showed that the reduction of caffeate esters by
L. helveticus
did not affect the content of flavonoids, which are the main bioactive molecules of propolis. Furthermore, we verified that the biotransformation of propolis did not cause a loss of antimicrobial activity. Finally, we demonstrated that the ability of
L. helveticus
to hydrolyze caffeate esters in propolis is strain specific. In conclusion, the proposed strategy is simple, employs food grade materials, and is effective in selectively removing allergenic molecules without affecting the bioactive fraction of propolis. This is the first study demonstrating that the allergenic caffeate esters of propolis can be eliminated by means of a bacterial biotransformation procedure.
Multilocus Sequence Typing Scheme for the Characterization of 936-Like Phages Infecting Lactococcus lactis
Authors: Moisan Maxim , Moineau Sylvain 
Published: April 2012

ABSTRACT

Lactococcus lactis
phage infections are costly for the dairy industry because they can slow down the fermentation process and adversely impact product safety and quality. Although many strategies have been developed to better control phage populations, new virulent phages continue to emerge. Thus, it is beneficial to develop an efficient method for the routine identification of new phages within a dairy plant to rapidly adapt antiphage tactics. Here, we present a multilocus sequence typing (MLST) scheme for the characterization of the 936-like phages, the most prevalent phage group infecting
L. lactis
strains worldwide. The proposed MLST system targets the internal portion of five highly conserved genomic sequences belonging to the packaging, morphogenesis, and lysis modules. Our MLST scheme was used to analyze 100 phages with different restriction fragment length polymorphism (RFLP) patterns isolated from 11 different countries between 1971 and 2010. PCR products were obtained for all the phages analyzed, and sequence analysis highlighted the high discriminatory power of the MLST system, detecting 93 different sequence types. A conserved locus within the
lys
gene (coding for endolysin) was the most discriminative, with 65 distinct alleles. The locus within the
mcp
gene (major capsid protein) was the most conserved (54 distinct alleles). Phylogenetic analyses of the concatenated sequences exhibited a strong concordance of the clusters with the phage host range, indicating the clonal evolution of these phages. A public database has been set up for the proposed MLST system, and it can be accessed at
http://pubmlst.org/bacteriophages/
.
Requirement of Siderophore Biosynthesis for Plant Colonization by Salmonella enterica
Authors: Hao Ling-yun , Willis David Kyle , Andrews-Polymenis Helene , McClelland Michael , Barak Jeri D. 
Published: April 2012

ABSTRACT

Contaminated fresh produce has become the number one vector of nontyphoidal salmonellosis to humans. However,
Salmonella enterica
genes essential for the life cycle of the organism outside the mammalian host are for the most part unknown. Screening deletion mutants led to the discovery that an
aroA
mutant had a significant root colonization defect due to a failure to replicate. AroA is part of the chorismic acid biosynthesis pathway, a central metabolic node involved in aromatic amino acid and siderophore production. Addition of tryptophan or phenylalanine to alfalfa root exudates did not restore
aroA
mutant replication. However, addition of ferrous sulfate restored replication of the
aroA
mutant, as well as alfalfa colonization. Tryptophan and phenylalanine auxotrophs had minor plant colonization defects, suggesting that suboptimal concentrations of these amino acids in root exudates were not major limiting factors for
Salmonella
replication. An
entB
mutant defective in siderophore biosynthesis had colonization and growth defects similar to those of the
aroA
mutant, and the defective phenotype was complemented by the addition of ferrous sulfate. Biosynthetic genes of each
Salmonella
siderophore, enterobactin and salmochelin, were upregulated in alfalfa root exudates, yet only enterobactin was sufficient for plant survival and persistence. Similar results in lettuce leaves indicate that siderophore biosynthesis is a widespread or perhaps universal plant colonization fitness factor for
Salmonella
, unlike phytobacterial pathogens, such as
Pseudomonas
and
Xanthomonas
.
Investigating the Function of Ddr48p in Candida albicans
Authors: Cleary I. A. , MacGregor N. B. , Saville S. P. , Thomas D. P. 
Published: April 2012

ABSTRACTCandidiasis now represents the fourth most frequent nosocomial infection both in the United States and worldwide.Candida albicansis an increasingly common threat to human health as a consequence of AIDS, steroid therapy, organ and tissue transplantation, cancer therapy, broad-spectrum antibiotics, and other immune defects. The pathogenic potential ofC. albicansis intimately related to certain key processes, including biofilm formation and filamentation. Ddr48p is a damage response protein that is significantly upregulated during both biofilm formation and filamentation, but its actual function is unknown. Previous studies have indicated that this protein may be essential inC. albicansbut notSaccharomyces cerevisiae. Here we examined the function of Ddr48p and investigated the role of this protein in biofilm formation and filamentation. We demonstrated that this protein is not essential inC. albicansand appears to be dispensable for filamentation. However,DDR48is required for the flocculation response stimulated by 3-aminotriazole-induced amino acid starvation. Furthermore, we examined the response of this deletion strain to a wide variety of environmental stressors and antifungal compounds. We observed several mild sensitivity or resistance phenotypes and also found that Ddr48p contributes to the DNA damage response ofC. albicans. The results of this study reveal that the role of this highly expressed protein goes beyond a general stress response and impinges on a key facet of pathogenesis, namely, the ability to sense and respond to changes in the host environment.
Mechanism for Regulation of the Putrescine Utilization Pathway by the Transcription Factor PuuR in Escherichia coli K-12
Authors: Nemoto Naoki , Kurihara Shin , Kitahara Yuzuru , Asada Kei , Kato Kenji , Suzuki Hideyuki 
Published: April 2012

ABSTRACT

In
Escherichia coli
, putrescine is metabolized to succinate for use as a carbon and nitrogen source by the putrescine utilization pathway (Puu pathway). One gene in the
puu
gene cluster encodes a transcription factor, PuuR, which has a helix-turn-helix DNA-binding motif. DNA microarray analysis of an
E. coli puuR
mutant, in which three amino acid residues in the helix-turn-helix DNA binding motif of PuuR were mutated to alanine to eliminate DNA binding of PuuR, suggested that PuuR is a negative regulator of
puu
genes. Results of gel shift and DNase I footprint analyses suggested that PuuR binds to the promoter regions of
puuA
and
puuD
. The binding of wild-type PuuR to a DNA probe containing PuuR recognition sites was diminished with increasing putrescine concentrations
in vitro
. These results suggest that PuuR regulates the intracellular putrescine concentration by the transcriptional regulation of genes in the Puu pathway, including
puuR
itself. The
puu
gene cluster is found in
E. coli
and closely related enterobacteria, but this gene cluster is uncommon in other bacterial groups.
E. coli
and related enterobacteria may have gained the Puu pathway as an adaptation for survival in the mammalian intestine, an environment in which polyamines exist at relatively high concentrations.
Cyclic Diguanylate Inversely Regulates Motility and Aggregation in Clostridium difficile
Authors: Purcell Erin B. , McKee Robert W. , McBride Shonna M. , Waters Christopher M. , Tamayo Rita 
Published: April 2012

ABSTRACT

Clostridium difficile
-associated disease is increasing in incidence and is costly to treat. Our understanding of how this organism senses its entry into the host and adapts for growth in the large bowel is limited. The small-molecule second messenger cyclic diguanylate (c-di-GMP) has been extensively studied in Gram-negative bacteria and has been shown to modulate motility, biofilm formation, and other processes in response to environmental signals, yet little is known about the functions of this signaling molecule in Gram-positive bacteria or in
C. difficile
specifically. In the current study, we investigated the function of the second messenger c-di-GMP in
C. difficile
. To determine the role of c-di-GMP in
C. difficile
, we ectopically expressed genes encoding a diguanylate cyclase enzyme, which synthesizes c-di-GMP, or a phosphodiesterase enzyme, which degrades c-di-GMP. This strategy allowed us to artificially elevate or deplete intracellular c-di-GMP, respectively, and determine that c-di-GMP represses motility in
C. difficile
, consistent with previous studies in Gram-negative bacteria, in which c-di-GMP has a negative effect on myriad modes of bacterial motility. Elevated c-di-GMP levels also induced clumping of
C. difficile
cells, which may signify that
C. difficile
is capable of forming biofilms in the host. In addition, we directly quantified, for the first time, c-di-GMP production in a Gram-positive bacterium. This work demonstrates the effect of c-di-GMP on the motility of a Gram-positive bacterium and on aggregation of
C. difficile
, which may be relevant to the function of this signaling molecule during infection.
Complete DNA Sequence Analysis of Enterohemorrhagic Escherichia coli Plasmid pO157_2 in β-Glucuronidase-Positive E. coli O157:H7 Reveals a Novel Evolutionary Path
Authors: Rump L. V. , Meng J. , Strain E. A. , Cao G. , Allard M. W. , Gonzalez-Escalona N. 
Published: April 2012

ABSTRACT

Strains of enterohemorragic
Escherichia coli
(EHEC) O157:H7 that are non-sorbitol fermenting (NSF) and β-glucuronidase negative (GUD
−
) carry a large virulence plasmid, pO157 (>90,000 bp), whereas closely related sorbitol-fermenting (SF)
E. coli
O157:H
−
strains carry plasmid pSFO157 (>120,000 bp). GUD
+
NSF O157:H7 strains are presumed to be precursors of GUD
−
NSF O157:H7 strains that also carry pO157. In this study, we report the complete sequence of a novel virulence plasmid, pO157-2 (89,762 bp), isolated from GUD
+
NSF O157:H7 strain G5101. PCR analysis confirmed the presence of pO157-2 in six other strains of GUD
+
NSF O157:H7. pO157-2 carries genes associated with virulence (e.g., hemolysin genes) and conjugation (
tra
and
trb
genes) but lacks
katP
and
espP
present in pO157. Comparative analysis of the three EHEC plasmids shows that pO157-2 is highly related to pO157 and pSFO157 but not ancestral to pO157. These results indicated that GUD
+
NSF O157:H7 strains might not be direct precursors to GUD
−
NSF O157:H7 as previously proposed but rather have evolved independently from a common ancestor.
Effects of Lipopolysaccharide Biosynthesis Mutations on K1 Polysaccharide Association with the Escherichia coli Cell Surface
Authors: Jiménez Natalia , Senchenkova Sofya N. , Knirel Yuriy A. , Pieretti Giuseppina , Corsaro Maria M. , Aquilini Eleonora , Regué Miguel , Merino Susana , Tomás Juan M. 
Published: April 2012

ABSTRACT

The presence of cell-bound K1 capsule and K1 polysaccharide in culture supernatants was determined in a series of in-frame nonpolar core biosynthetic mutants from
Escherichia coli
KT1094 (K1, R1 core lipopolysaccharide [LPS] type) for which the major core oligosaccharide structures were determined. Cell-bound K1 capsule was absent from mutants devoid of phosphoryl modifications on
l
-
glycero
-
d
-
manno
-heptose residues (HepI and HepII) of the inner-core LPS and reduced in mutants devoid of phosphoryl modification on HepII or devoid of HepIII. In contrast, in all of the mutants, K1 polysaccharide was found in culture supernatants. These results were confirmed by using a mutant with a deletion spanning from the
hldD
to
waaQ
genes of the
waa
gene cluster to which individual genes were reintroduced. A nuclear magnetic resonance (NMR) analysis of core LPS from HepIII-deficient mutants showed an alteration in the pattern of phosphoryl modifications. A cell extract containing both K1 capsule polysaccharide and LPS obtained from an O-antigen-deficient mutant could be resolved into K1 polysaccharide and core LPS by column chromatography only when EDTA and deoxycholate (DOC) buffer were used. These results suggest that the K1 polysaccharide remains cell associated by ionically interacting with the phosphate-negative charges of the core LPS.
The Response Regulator RcsB Activates Expression of Mat Fimbriae in Meningitic Escherichia coli
Authors: Lehti Timo A. , Heikkinen Johanna , Korhonen Timo K. , Westerlund-Wikström Benita 
Published: April 2012

ABSTRACT

The common colonization factor of
Escherichia coli
, the Mat (also termed ECP) fimbria, functions to advance biofilm formation on inert surfaces as well as bacterial adherence to epithelial cells and subsequent colonization. We used global mini-Tn
5
transposon mutagenesis to identify novel regulators of biofilm formation by the meningitic
E. coli
isolate IHE 3034. Of the 4,418 transformants, we found 17 that were impaired in biofilm formation. Most of these mutants were affected in lipopolysaccharide synthesis and were reduced in growth but not in Mat fimbria expression. In contrast, two mutants grew well but did not express Mat fimbria. The insertions in these two mutants were located at different sites of the
rcsB
gene, which encodes a DNA-binding response regulator of the Rcs response regulon. The mutations abrogated temperature-dependent biofilm formation by IHE 3034, and the phenotype correlated with loss of
mat
expression. The defect in biofilm formation in the
rcsB
mutant was reversed upon complementation with
rcsB
as well as by overexpression of structural
mat
genes but not by overexpression of the fimbria-specific activator gene
matA
. Monitoring of the
mat
operon promoter activity with chromosomal reporter fusions showed that the RcsB protein and an RcsAB box in the
mat
regulatory region, but not RcsC, RcsD, AckA, and Pta, are essential for initiation of
mat
transcription. Gel retardation assays showed that RcsB specifically binds to the
mat
promoter DNA, which enables its function in promoting biofilm formation by
E. coli
.
Fitness levels and physical activity among class A drug users entering prison
Authors: Fischer Jan , Butt Christine , Dawes Helen , Foster Charlie , Neale Joanne , Plugge Emma , Wheeler Carly , Wright Nat 
Published: April 2012

BackgroundPhysical activity could benefit drug users' physiological and mental health. Previous research has suggested that physical activity levels change when drug users enter prison.MethodsTwenty-five class A drug users who were new to prison answered physical activity and drug use cross-sectional questionnaires, took a submaximal fitness test and wore a pedometer for 1 week.ResultsParticipants' mean aerobic capacity was estimated as 49 mls O2/kg/min (±12 SD). Their mean self-reported walking distance outside of prison was 4.67 miles on an average day (±4.14 SD). Pedometer data suggest they walked a mean of 1.8 miles/day in prison.ConclusionMany class A drug users entering prison had high levels of fitness and physical activity before admission, often gained from walking. Walking activity reduced when they entered prison, posing a challenge to maintaining healthy activity levels.
Thiazolidinediones for plaque psoriasis: a systematic review and meta-analysis
Authors: Malhotra Anita , Shafiq Nusrat , Rajagopalan Sujit , Dogra Sunil , Malhotra Samir 
Published: April 2012

BackgroundThere is some evidence for the role of inflammation and insulin resistance in the pathophysiology of plaque psoriasis. Thiazolidinediones are antidiabetic drugs that act by improving insulin sensitivity and also possess anti-inflammatory effects. Evidence from in vitro, animal and human studies has accumulated suggesting that these drugs may be of use in psoriasis.ObjectiveThis systematic review and meta-analysis was performed to assess the efficacy of thiazolidinediones on psoriasis severity.Study selectionRandomised, open-label or single blind or double blind, published as well as unpublished, studies of thiazolidinedione administration compared with placebo, given to patients with plaque psoriasis for at least 8 weeks were considered for inclusion in this review. The primary outcomes were as follows: mean or mean percent change in Psoriasis Area and Severity Index (PASI) from baseline to end of treatment with pioglitazone, proportion of patients showing >75% improvement in PASI score, and proportion of patients showing >50% improvement in PASI score. Data analysis was done using Revman 5.FindingsTwenty-seven relevant citations were identified. Two studies each for pioglitazone and rosiglitazone were included in the meta-analysis. There was a significantly greater mean decrease in PASI scores from baseline to end of treatment (−4.24 (95% CI −5.35 to −3.12)) in the pioglitazone group as compared to placebo. There was a non-significant improvement in PASI50/70 in the pooled analysis of rosiglitazone trials.ConclusionPioglitazone appears to have efficacy for the treatment of psoriasis. The clinical significance of the effect and role in management of psoriasis deserve further study.