bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biosynthesis of the red pigment bikaverin in Fusarium fujikuroi: genes, their function and regulation
Authors: Wiemann Philipp , Willmann Anita , Straeten Marcus , Kleigrewe Karin , Beyer Marita , Humpf Hans‐Ulrich , Tudzynski Bettina 
Published: April 2009

Summary Fusarium secondary metabolites are structurally diverse, have a variety of activities and are generally poorly understood biosynthetically. The F. fujikuroi polyketide synthase gene bik1 was previously shown to be responsible for formation of the mycelial pigment bikaverin. Here we present the characterization of five genes adjacent to bik1 as encoding a putative FAD‐dependent monooxygenase (bik2), an O‐methyltransferase (bik3), an NmrA‐like protein (bik4), a Zn(II)2Cys6 transcription factor (bik5) and an MFS transporter (bik6). Deletion of each gene resulted in total loss or significant reduction of bikaverin synthesis. Expression studies revealed that all bik genes are repressed by high amounts of nitrogen in an AreA‐independent manner and are subject to a time‐ and pH‐dependent regulation. Deletion of the pH regulatory gene pacC resulted in partial derepression while complementation with a dominant active allele resulted in repression of bik genes at acidic ambient pH. Transcription of all bik genes in strains lacking bik1, bik2 or bik3 was essentially eliminated, while transcription of some bik genes was detected in strains lacking bik4, bik5 or bik6. Thus, bikaverin synthesis is regulated by a complex regulatory network. Understanding how different factors influence the synthesis of this model secondary metabolite will aid understanding secondary metabolism in general.
Characterization of staphyloferrin A biosynthetic and transport mutants in Staphylococcus aureus
Authors: Beasley Federico C. , Vinés Enrique D. , Grigg Jason C. , Zheng Qin , Liu Suya , Lajoie Gilles A. , Murphy Michael E. P. , Heinrichs David E. 
Published: April 2009

SummaryIron is critical for virtually all forms of life. The production of high‐affinity iron chelators, siderophores, and the subsequent uptake of iron–siderophore complexes are a common strategy employed by microorganisms to acquire iron. Staphylococcus aureus produces siderophores but genetic information underlying their synthesis and transport is limited. Previous work implicated the sbn operon in siderophore synthesis and the sirABC operon in uptake. Here we characterize a second siderophore biosynthetic locus in S. aureus; the locus consists of four genes (in strain Newman these open reading frames are designated NWMN_2079–2082) which, together, are responsible for the synthesis and export of staphyloferrin A, a polycarboxylate siderophore. While deletion of the NWMN_2079–2082 locus did not affect iron‐restricted growth of S. aureus, strains bearing combined sbn and NWMN_2079–2082 locus deletions produced no detectable siderophore and demonstrated severely attenuated iron‐restricted growth. Adjacent to NWMN_2079–2082 resides the htsABC operon, encoding an ABC transporter previously implicated in haem acquisition. We provide evidence here that HtsABC, along with the FhuC ATPase, is required for the uptake of staphyloferrin A. The crystal structure of apo‐HtsA was determined and identified a large positively charged region in the substrate‐binding pocket, in agreement with a role in binding of anionic staphyloferrin A.
Impaired TLR‐2 expression and TLR‐2‐mediated cytokine secretion in macrophages from patients with atopic dermatitis
Authors: Niebuhr M. , Lutat C. , Sigel S. , Werfel T. 
Published: April 2009

Background:  In many patients with atopic dermatitis (AD), the disease is complicated by their enhanced susceptibility to bacterial skin infections, especially with Staphylococcus aureus. The pattern recognition receptor toll‐like receptor (TLR)‐2 recognizes components of S. aureus, for example, lipoteichoic acid (LTA) and peptidoglycan (PGN) and, therefore, might be crucial in the pathogenesis and flare‐ups of AD.Objective:  To investigate TLR‐2 expression and cytokine secretion in macrophages from patients with AD compared to healthy controls upon TLR‐2 stimulation with PGN, LTA and Pam3Cys.Methods:  Macrophages were cultivated from highly purified peripheral blood monocytes of AD patients and nonatopic healthy controls and stimulated with PGN, LTA and Pam3Cys in a time and dose–dependent manner. Afterwards, TLR‐2 expression and cytokine secretion were measured on protein and mRNA level. TLR‐1 and TLR‐6 expression were investigated on the mRNA level. Immunohistochemical stainings from punch biopsies were performed to investigate TLR‐2 expression in skin macrophages.Results:  We could clearly show that macrophages from patients with AD expressed significantly less TLR‐2, whereas the expression pattern of TLR‐1 and TLR‐6 were not altered. Macrophages had a reduced capacity to produce pro‐inflammatory cytokines such as IL‐6, IL‐8 and IL‐1β after stimulation with TLR‐2 ligands.Conclusion:  Our findings clearly show an impaired TLR‐2 expression and functional differences of TLR‐2‐mediated effects on macrophages of AD patients compared to healthy controls which might contribute to the enhanced susceptibility to skin infections with S. aureus in AD.
The size of the disease relevant IgE antibody fraction in relation to ‘total‐IgE’ predicts the efficacy of anti‐IgE (Xolair®) treatment
Authors: Johansson S. G. O. , Nopp A. , Öman H. , Ankerst J. , Cardell L. O. , Grönneberg R. , Matsols H. , Rudblad S. , Strand V. , Stålenheim G. 
Published: April 2009

Background:  Some patients with allergic asthma treated with anti‐IgE (Xolair®) do not become symptom free. Better criteria for response assessment than allergy skin tests or IgE determination are needed. The impact of the size of the disease relevant allergen‐specific IgE antibody fraction, i.e. the percentage of IgE antibody of total IgE, was evaluated in cat allergic patients treated with the recommended doses of Xolair®. Results were measured as changes in basophil allergen threshold sensitivity (CD‐sens).Methods:  In a double‐blind placebo controlled trial 20 patients with a high (>3.8%) and 18 with a low (<1%) percentage of IgE antibodies to cat were given Xolair® for 16 weeks and the change in CD‐sens was compared to 11 and 10 patients, respectively, in each group receiving placebo.Results:  The CD‐sens dropped significantly in both the high (P < 0.001) and low (P < 0.001) group on Xolair® but did not change significantly after placebo. For Xolair®‐treated patients, at the end of the trial there was a highly significant (P < 0.001) difference in CD‐sens between the high group, where no patients, and the low group, where 13/18 patients, had become negative.Conclusions:  The currently recommended doses of Xolair® very efficiently eliminate IgE antibodies if the IgE antibody fraction is <1% of total IgE but has not enough effect on allergen sensitivity if the fraction is >3–4%. Further studies will show if increased doses of Xolair® would help also these patients, who seem to represent about 1/3 of the patient population.
Genetic variation in CRTh2 influences development of allergic phenotypes
Authors: Cameron L. , Depner M. , Kormann M. , Klopp N. , Illig T. , Von Mutius E. , Kabesch M. 
Published: April 2009

Background:  Allergic disorders are characterized by an increase in the Th2 cytokines IL‐4, IL‐5 and IL‐13, produced primarily by Th2 cells. These cells are marked by the expression of CRTh2 (chemoattractant receptor‐homologous molecule expressed on Th2 cells), a receptor for prostaglandin D2. As genetic variation plays a significant role in the predisposition for allergic disorders, we investigated the influence of single nucleotide polymorphisms (SNPs) in CRTh2.Methods:  In a large study population of German children (n = 4264) from the International Study of Asthma and Allergy in Children (ISAAC II), six polymorphisms in CRTh2 were genotyped. Statistical analyses were performed using single SNP and haplotype analyses.Results:  Uncorrected associations among −6373G>A, +1431G>C and +1538A>G were observed with a number of allergic phenotypes (P < 0.05). After correction, association between +1431C and specific IgE to food allergens remained significant (P = 0.04). Associations of haplotype (H)3 (containing +1538G) with reduced risk for asthma and H2 (containing +1431C) with increased risk for specific IgE to food allergens also remained significant after correction for multiple testing (P = 0.004).Conclusions:  Genetic variation within CRTh2 modifies the development of allergic sensitization and asthma in a population of German children.
Decreased FOXP3 protein expression in patients with asthma
Authors: Provoost S. , Maes T. , Van Durme Y. M. , Gevaert P. , Bachert C. , Schmidt‐Weber C. B. , Brusselle G. G. , Joos G. F. , Tournoy K. G. 
Published: April 2009

Background:  T‐regulatory cells (Treg) are important in balancing immune responses and maintaining peripheral tolerance. Current evidence suggests that asthma is characterized by a relative deficiency in Treg, allowing T helper 2 cells to expand. In this study, we aimed to evaluate circulating Treg, defined by the protein FOXP3, in both control subjects and patients with stable asthma.Methods:  Peripheral blood mononuclear cells (PBMC) of control (n = 14) and asthmatic patients (n = 29) were labeled for CD4, CD25, and intracellular FOXP3 and analyzed using flow cytometry. In CD3/CD28 stimulated PBMC, the effects of dexamethasone on the transcription factors T‐bet, GATA‐3, FOXP3, and RORc2 and representative cytokines were studied.Results:  In control subjects and asthmatic patients, numbers of peripheral blood CD4+CD25high and CD4+CD25highFOXP3+ T‐cells were similar. However, FOXP3 protein expression within CD4+CD25high T‐cells was significantly decreased in asthmatic patients. There was a tendency for increased FOXP3 expression within CD4+CD25high T‐cells in glucocorticosteroid‐treated patients when compared to steroid‐naive asthmatic patients. In stimulated PBMC, dexamethasone treatment increased the anti‐/proinflammatory transcription ratios of FOXP3/GATA‐3, FOXP3/T‐bet, and FOXP3/RORc2.Conclusion:  Asthmatic patients have decreased FOXP3 protein expression within their CD4+CD25high Treg. Our findings also suggest that treatment with inhaled glucocorticosteroids in asthmatics might increase this FOXP3 protein expression within the CD4+CD25high T‐cell population.
Neutrophilic airway inflammation is a main feature of induced sputum in nonatopic asthmatic children
Authors: Drews A. C. , Pizzichini M. M. M. , Pizzichini E. , Pereira M. U. , Pitrez P. M. , Jones M. H. , Sly P. D. , Stein R. T. 
Published: April 2009

Background:  Asthma phenotypes are well described among children. However, there are few studies comparing airway inflammation in different clinical presentations of pediatric asthma. We tested the hypothesis that nonatopic asthma is associated with a predominant noneosinophilic inflammation in the airways, as assessed by induced sputum. The objective of this study was to evaluate the cytological characteristics of induced sputum (IS) in atopic (AA), nonatopic asthmatics (NAA) and nonatopic nonasthmatic children (NANA).Methods:  Of 90 selected children, 77 met eligibility criteria for performing IS and were classified as: AA, n = 28, NAA, n = 29 and NANA, n = 19. Subjects answered to a set of ISAAC‐based questions and were skin‐tested for common aeroallergens. A defined series of exclusion criteria was applied.Results:  Induced sputum was obtained from 54 (70.1%) subjects (21 AA, 20 NAA and 13 NANA). Demographic data and mean FEV1 were similar in the three groups. The proportion of eosinophils [median, inter quartile range (IQR)] was significantly higher in the sputum of AA [(6.0.)12)] compared with NAAs [0 (2)] and NANAs [0 (1)], P < 0.001. The proportion of children with sputum eosinophilia (eos > 3%) was also significantly higher in AA (71.4%) when compared with NAA (28.6%); none of the NANA had sputum eosinophilia. Nonatopic asthmatic children had significantly higher proportions and absolute number of neutrophils than AA and controls.Conclusions:  The results suggest that nonatopic children present IS with a cell pattern that is predominantly neutrophilic while eosinophilia is the hallmark of airway inflammation in the majority of atopic wheezing children not treated with inhaled steroids.
Cross‐reactivity and tolerability of imipenem in patients with delayed‐type, cell‐mediated hypersensitivity to β‐lactams
Authors: Schiavino D. , Nucera E. , Lombardo C. , Decinti M. , Pascolini L. , Altomonte G. , Buonomo A. , Patriarca G. 
Published: April 2009

Background: Administration of imipenem‐cilastatin to patients with IgE‐mediated hypersensitivity to β‐lactams has always been considered potentially harmful. Recent studies have demonstrated the tolerability of carbapenems (imipenem‐cilastatin and meropenem) in patients with IgE‐mediated hypersensitivity to β‐lactams; there are no studies on this topic regarding patients with cell‐mediated allergy to β‐lactams. The aim of this study is to assess cross‐reactivity and tolerability of imipenem in patients with cell‐mediated allergy to β‐lactams.Methods: From our database we selected 73 patients with cell‐mediated allergy to β‐lactams, diagnosed by means of immediate‐type skin tests, delayed reading intradermal tests, patch tests and detection of specific IgE. Patients with negative patch tests with imipenem‐cilastatin underwent an intramuscular test dosing.Results: Our patients had a total of 94 nonimmediate reactions to penicillins. All patients had positive patch tests and/or delayed reading intradermal tests for at least one of the penicillin reagent tested and negative immediate‐type skin tests and specific IgE. Four patients out of 73 had a positive patch tests to at least one penicillin reagent and imipenem‐cilastatin showing cross‐reactivity. Sixty‐four patients underwent the imipenem‐cilastatin intramuscular test dosing and none of them had a clinical reaction.Conclusions: Our rate of cross‐reactivity between imipenem‐cilastatin and other β‐lactams was 5.5%. This result is different from previous findings and this may be explained by the fact that we investigated patients with cell‐mediated allergy to β‐lactams. Patients with cell‐mediated allergy to β‐lactams should undergo patch tests and a tolerance challenge test before treatment with imipenem‐cilastatin.
Oral cavity is not a reservoir for Helicobacter pylori in infected patients with functional dyspepsia
Authors: Silva Rossi‐Aguiar V. P. , Navarro‐Rodriguez T. , Mattar R. , Siqueira de Melo Peres M. P. , Correa Barbuti R. , Silva F. M. , Carrilho F. J. , Eisig J. N. 
Published: April 2009

Introduction:  Helicobacter pylori infection is very prevalent in Brazil, infecting almost 65% of the population. The aim of this study was to evaluate the presence of this bacterium in the oral cavity of patients with functional dyspepsia (epigastric pain syndrome), establish the main sites of infection in the mouth, and assess the frequency of cagA and vacA genotypes of oral H. pylori.Methods:  All 43 outpatients with epigastric pain syndrome, who entered the study, were submitted to upper gastrointestinal endoscopy to rule out organic diseases. Helicobacter pylori infection in the stomach was confirmed by a rapid urease test and urea breath tests. Samples of saliva, the tongue dorsum and supragingival dental plaque were collected from the oral cavity of each subject and subgingival dental plaque samples were collected from the patients with periodontitis; H. pylori infection was verified by polymerase chain reaction using primers that amplify the DNA sequence of a species‐specific antigen present in all H. pylori strains; primers that amplify a region of urease gene, and primers for cagA and vacA (m1, m2, s1a, s1b, s2) genotyping.Results:  Thirty patients harbored H. pylori in the stomach, but it was not possible to detect H. pylori in any oral samples using P1/P2 and Urease A/B. The genotype cagA was also negative in all samples and vacA genotype could not be characterized (s‐m‐).Conclusion:  The oral cavity may not be a reservoir for H. pylori in patients with epigastric pain syndrome, the bacterium being detected exclusively in the stomach.
Prevalence, intensity and identity of bacteraemia following conservative dental procedures in children
Authors: Sonbol H. , Spratt D. , Roberts G. J. , Lucas V. S. 
Published: April 2009

Introduction:  The aim of this study was to investigate the prevalence, intensity and microbial identity of bacteraemia following conservative dental procedures. The procedures were placement of rubber dam, use of the fast drill, use of the slow drill and placement of a matrix band and wedge.Method:  Two hundred and five children and adolescents undergoing general anaesthesia for dental treatment at the Eastman Dental Hospital were recruited. Each subject was randomly allocated to one of the procedure groups. A baseline blood sample was taken before any dental treatment was carried out. A second blood sample was taken 30 s after a single conservative procedure. The blood samples were processed using lysis filtration. All bacterial isolates were identified using comparative 16 S ribosomal RNA gene sequencing. Oral Streptococcus spp. and coagulase‐negative Staphylococcus spp. were further identified by comparative sodA gene sequencing.Results:  The prevalence of bacteraemia was significantly greater following placement of rubber dam (P = 0.01) and placement of matrix band and wedge, compared with baseline. The intensity of bacteraemia was significantly greater following placement of rubber dam (P = 0.001) and placement of matrix band and wedge (P = 0.0001). The most frequently isolated bacteria were Streptococcus spp. (56%), Actinomyces spp. (15%) and coagulase‐negative Staphylococcus spp. (15%).Conclusion:  Conservative dental procedures are a significant cause of bacteraemia.
Expression of receptor activator of nuclear factor‐κB ligand by B cells in response to oral bacteria
Authors: Han X. , Lin X. , Seliger A. R. , Eastcott J. , Kawai T. , Taubman M. A. 
Published: April 2009

Introduction:  We investigated receptor activator of nuclear factor‐κB ligand (RANKL) expression by B lymphocytes during early and late aspects of the immune response to Aggregatibacter actinomycetemcomitans, a gram‐negative, anaerobic bacterium associated with aggressive periodontal disease.Methods:  Expression of messenger RNA transcripts (tumor necrosis factor‐α, Toll‐like receptors 4 and 9, interleukins 4 and 10, and RANKL) involved in early (1‐day) and late (10‐day) responses in cultured rat splenocytes was examined by reverse transcription–polymerase chain reaction (RT‐PCR). The immune cell distribution (T, B, and natural killer cells and macrophages) in cultured rat splenocytes and RANKL expression in B cells were determined by flow cytometric analyses. B‐cell capacity for induction of osteoclast differentiation was evaluated by coculture with RAW 264.7 cells followed by a tartrate‐resistant acid phosphatase (TRAP) activity assay.Results:  The expression levels of interleukins 4 and 10 in cultured cells were not changed in the presence of A. actinomycetemcomitans until cultured for 3 days, and peaked after 7 days. After culture for 10 days, the percentages of B and T cells, the overall RANKL messenger RNA transcripts, and the percentage of RANKL‐expressing immunoglobulin G‐positive cells were significantly increased in the presence of A. actinomycetemcomitans. These increases were considerably greater in cells isolated from A. actinomycetemcomitans‐immunized animals than from non‐immunized animals. RAW 264.7 cells demonstrated significantly increased TRAP activity when cocultured with B cells from A. actinomycetemcomitans‐immunized animals. The addition of human osteoprotegerin‐Fc to the culture significantly diminished such increases.Conclusion:  This study suggests that B‐lymphocyte involvement in the immune response to A. actinomycetemcomitans through upregulation of RANKL expression potentially contribute to bone resorption in periodontal disease.
Comparative whole‐genome analysis of Streptococcus mutans isolates within and among individuals of different caries status
Authors: Zhang L. , Foxman B. , Drake D. R. , Srinivasan U. , Henderson J. , Olson B. , Marrs C. F. , Warren J. J. , Marazita M. L. 
Published: April 2009

Introduction:  Genotypic analyses of Streptococcus mutans using fingerprinting methods depend on a few genetic loci being different but do not reveal the underlying genome‐wide differences between strains.Methods:  We used comparative genomic hybridization (CGH) with 70‐mer oligonucleotide microarrays containing open reading frames (ORFs) from S. mutans strain UA159 to examine the genetic diversity of 44 isolates from nine children selected from a local study population in Eastern Iowa.Results:  Unique strains (clones) within each child initially identified by arbitrary‐priming polymerase chain reaction were confirmed by CGH. There was a wide range of variation in the hybridization patterns of the 1948 ORFs among the test isolates examined. Between 87 and 237 ORFs failed to give a positive signal among individual isolates. A total of 323 of the UA159 ORFs were absent from one or more of the test strains. These 323 variable genes seemed to be distributed across the entire UA159 genome and across all the predicted functional categories.Conclusion:  This set of very close geographically and temporally collected S. mutans isolates had a degree of gene content variation as high as a previously examined global set of strains. Comparing the frequency of these variable genes, the majority of which have unknown function, among strains of different origins (i.e. different caries status) could help to determine their relevance in S. mutans cariogenicity.
Genes responsible for dextran‐dependent aggregation of Streptococcus sobrinus strain 6715
Authors: Sato Y. , Okamoto‐Shibayama K. , Takada K. , Igarashi T. , Hirasawa M. 
Published: April 2009

Introduction:  Streptococcus sobrinus exhibits more significant dextran‐dependent aggregation mediated by glucan‐binding proteins than Streptococcus mutans. We have identified four glucan‐binding protein C gene (gbpC) homologues designated as gbpC1, gbpC2, dblA and dblB in S. sobrinus in contrast to the single gene gbpC in S. mutans. We attempted to determine which gene is most responsible for the dextran‐dependent aggregation of S. sobrinus.Methods:  We introduced mutation with a chemical mutagen, 1‐methyl‐3‐nitro‐1‐nitrosoguanidine, into S. sobrinus strain 6715 and analysed the four gbpC homologous gene sequences in the parental strain 6715 and an obtained aggregation‐negative mutant NUM‐Ssg99. We also examined the localization of proteins encoded by these genes in the mutant NUM‐Ssg99.Results:  The nucleotide sequences of the gbpC1, gbpC2 and dblA genes in NUM‐Ssg99 were 100% identical to the homologous genes in parental strain 6715. In contrast, a truncated mutation was detected in the dblB gene and the mutant protein devoid of the LPXTG motif was confirmed by Western blot analysis to be released into the extracellular milieu.Conclusion:  We conclude that the dblB gene among the four GbpC homologous protein genes is most responsible for aggregation in strain 6715.